summaryrefslogtreecommitdiffstats
path: root/module/zfs/spa.c
blob: 5e0338d3eca945cb1a73c4925f70137d4992b52e (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
2230
2231
2232
2233
2234
2235
2236
2237
2238
2239
2240
2241
2242
2243
2244
2245
2246
2247
2248
2249
2250
2251
2252
2253
2254
2255
2256
2257
2258
2259
2260
2261
2262
2263
2264
2265
2266
2267
2268
2269
2270
2271
2272
2273
2274
2275
2276
2277
2278
2279
2280
2281
2282
2283
2284
2285
2286
2287
2288
2289
2290
2291
2292
2293
2294
2295
2296
2297
2298
2299
2300
2301
2302
2303
2304
2305
2306
2307
2308
2309
2310
2311
2312
2313
2314
2315
2316
2317
2318
2319
2320
2321
2322
2323
2324
2325
2326
2327
2328
2329
2330
2331
2332
2333
2334
2335
2336
2337
2338
2339
2340
2341
2342
2343
2344
2345
2346
2347
2348
2349
2350
2351
2352
2353
2354
2355
2356
2357
2358
2359
2360
2361
2362
2363
2364
2365
2366
2367
2368
2369
2370
2371
2372
2373
2374
2375
2376
2377
2378
2379
2380
2381
2382
2383
2384
2385
2386
2387
2388
2389
2390
2391
2392
2393
2394
2395
2396
2397
2398
2399
2400
2401
2402
2403
2404
2405
2406
2407
2408
2409
2410
2411
2412
2413
2414
2415
2416
2417
2418
2419
2420
2421
2422
2423
2424
2425
2426
2427
2428
2429
2430
2431
2432
2433
2434
2435
2436
2437
2438
2439
2440
2441
2442
2443
2444
2445
2446
2447
2448
2449
2450
2451
2452
2453
2454
2455
2456
2457
2458
2459
2460
2461
2462
2463
2464
2465
2466
2467
2468
2469
2470
2471
2472
2473
2474
2475
2476
2477
2478
2479
2480
2481
2482
2483
2484
2485
2486
2487
2488
2489
2490
2491
2492
2493
2494
2495
2496
2497
2498
2499
2500
2501
2502
2503
2504
2505
2506
2507
2508
2509
2510
2511
2512
2513
2514
2515
2516
2517
2518
2519
2520
2521
2522
2523
2524
2525
2526
2527
2528
2529
2530
2531
2532
2533
2534
2535
2536
2537
2538
2539
2540
2541
2542
2543
2544
2545
2546
2547
2548
2549
2550
2551
2552
2553
2554
2555
2556
2557
2558
2559
2560
2561
2562
2563
2564
2565
2566
2567
2568
2569
2570
2571
2572
2573
2574
2575
2576
2577
2578
2579
2580
2581
2582
2583
2584
2585
2586
2587
2588
2589
2590
2591
2592
2593
2594
2595
2596
2597
2598
2599
2600
2601
2602
2603
2604
2605
2606
2607
2608
2609
2610
2611
2612
2613
2614
2615
2616
2617
2618
2619
2620
2621
2622
2623
2624
2625
2626
2627
2628
2629
2630
2631
2632
2633
2634
2635
2636
2637
2638
2639
2640
2641
2642
2643
2644
2645
2646
2647
2648
2649
2650
2651
2652
2653
2654
2655
2656
2657
2658
2659
2660
2661
2662
2663
2664
2665
2666
2667
2668
2669
2670
2671
2672
2673
2674
2675
2676
2677
2678
2679
2680
2681
2682
2683
2684
2685
2686
2687
2688
2689
2690
2691
2692
2693
2694
2695
2696
2697
2698
2699
2700
2701
2702
2703
2704
2705
2706
2707
2708
2709
2710
2711
2712
2713
2714
2715
2716
2717
2718
2719
2720
2721
2722
2723
2724
2725
2726
2727
2728
2729
2730
2731
2732
2733
2734
2735
2736
2737
2738
2739
2740
2741
2742
2743
2744
2745
2746
2747
2748
2749
2750
2751
2752
2753
2754
2755
2756
2757
2758
2759
2760
2761
2762
2763
2764
2765
2766
2767
2768
2769
2770
2771
2772
2773
2774
2775
2776
2777
2778
2779
2780
2781
2782
2783
2784
2785
2786
2787
2788
2789
2790
2791
2792
2793
2794
2795
2796
2797
2798
2799
2800
2801
2802
2803
2804
2805
2806
2807
2808
2809
2810
2811
2812
2813
2814
2815
2816
2817
2818
2819
2820
2821
2822
2823
2824
2825
2826
2827
2828
2829
2830
2831
2832
2833
2834
2835
2836
2837
2838
2839
2840
2841
2842
2843
2844
2845
2846
2847
2848
2849
2850
2851
2852
2853
2854
2855
2856
2857
2858
2859
2860
2861
2862
2863
2864
2865
2866
2867
2868
2869
2870
2871
2872
2873
2874
2875
2876
2877
2878
2879
2880
2881
2882
2883
2884
2885
2886
2887
2888
2889
2890
2891
2892
2893
2894
2895
2896
2897
2898
2899
2900
2901
2902
2903
2904
2905
2906
2907
2908
2909
2910
2911
2912
2913
2914
2915
2916
2917
2918
2919
2920
2921
2922
2923
2924
2925
2926
2927
2928
2929
2930
2931
2932
2933
2934
2935
2936
2937
2938
2939
2940
2941
2942
2943
2944
2945
2946
2947
2948
2949
2950
2951
2952
2953
2954
2955
2956
2957
2958
2959
2960
2961
2962
2963
2964
2965
2966
2967
2968
2969
2970
2971
2972
2973
2974
2975
2976
2977
2978
2979
2980
2981
2982
2983
2984
2985
2986
2987
2988
2989
2990
2991
2992
2993
2994
2995
2996
2997
2998
2999
3000
3001
3002
3003
3004
3005
3006
3007
3008
3009
3010
3011
3012
3013
3014
3015
3016
3017
3018
3019
3020
3021
3022
3023
3024
3025
3026
3027
3028
3029
3030
3031
3032
3033
3034
3035
3036
3037
3038
3039
3040
3041
3042
3043
3044
3045
3046
3047
3048
3049
3050
3051
3052
3053
3054
3055
3056
3057
3058
3059
3060
3061
3062
3063
3064
3065
3066
3067
3068
3069
3070
3071
3072
3073
3074
3075
3076
3077
3078
3079
3080
3081
3082
3083
3084
3085
3086
3087
3088
3089
3090
3091
3092
3093
3094
3095
3096
3097
3098
3099
3100
3101
3102
3103
3104
3105
3106
3107
3108
3109
3110
3111
3112
3113
3114
3115
3116
3117
3118
3119
3120
3121
3122
3123
3124
3125
3126
3127
3128
3129
3130
3131
3132
3133
3134
3135
3136
3137
3138
3139
3140
3141
3142
3143
3144
3145
3146
3147
3148
3149
3150
3151
3152
3153
3154
3155
3156
3157
3158
3159
3160
3161
3162
3163
3164
3165
3166
3167
3168
3169
3170
3171
3172
3173
3174
3175
3176
3177
3178
3179
3180
3181
3182
3183
3184
3185
3186
3187
3188
3189
3190
3191
3192
3193
3194
3195
3196
3197
3198
3199
3200
3201
3202
3203
3204
3205
3206
3207
3208
3209
3210
3211
3212
3213
3214
3215
3216
3217
3218
3219
3220
3221
3222
3223
3224
3225
3226
3227
3228
3229
3230
3231
3232
3233
3234
3235
3236
3237
3238
3239
3240
3241
3242
3243
3244
3245
3246
3247
3248
3249
3250
3251
3252
3253
3254
3255
3256
3257
3258
3259
3260
3261
3262
3263
3264
3265
3266
3267
3268
3269
3270
3271
3272
3273
3274
3275
3276
3277
3278
3279
3280
3281
3282
3283
3284
3285
3286
3287
3288
3289
3290
3291
3292
3293
3294
3295
3296
3297
3298
3299
3300
3301
3302
3303
3304
3305
3306
3307
3308
3309
3310
3311
3312
3313
3314
3315
3316
3317
3318
3319
3320
3321
3322
3323
3324
3325
3326
3327
3328
3329
3330
3331
3332
3333
3334
3335
3336
3337
3338
3339
3340
3341
3342
3343
3344
3345
3346
3347
3348
3349
3350
3351
3352
3353
3354
3355
3356
3357
3358
3359
3360
3361
3362
3363
3364
3365
3366
3367
3368
3369
3370
3371
3372
3373
3374
3375
3376
3377
3378
3379
3380
3381
3382
3383
3384
3385
3386
3387
3388
3389
3390
3391
3392
3393
3394
3395
3396
3397
3398
3399
3400
3401
3402
3403
3404
3405
3406
3407
3408
3409
3410
3411
3412
3413
3414
3415
3416
3417
3418
3419
3420
3421
3422
3423
3424
3425
3426
3427
3428
3429
3430
3431
3432
3433
3434
3435
3436
3437
3438
3439
3440
3441
3442
3443
3444
3445
3446
3447
3448
3449
3450
3451
3452
3453
3454
3455
3456
3457
3458
3459
3460
3461
3462
3463
3464
3465
3466
3467
3468
3469
3470
3471
3472
3473
3474
3475
3476
3477
3478
3479
3480
3481
3482
3483
3484
3485
3486
3487
3488
3489
3490
3491
3492
3493
3494
3495
3496
3497
3498
3499
3500
3501
3502
3503
3504
3505
3506
3507
3508
3509
3510
3511
3512
3513
3514
3515
3516
3517
3518
3519
3520
3521
3522
3523
3524
3525
3526
3527
3528
3529
3530
3531
3532
3533
3534
3535
3536
3537
3538
3539
3540
3541
3542
3543
3544
3545
3546
3547
3548
3549
3550
3551
3552
3553
3554
3555
3556
3557
3558
3559
3560
3561
3562
3563
3564
3565
3566
3567
3568
3569
3570
3571
3572
3573
3574
3575
3576
3577
3578
3579
3580
3581
3582
3583
3584
3585
3586
3587
3588
3589
3590
3591
3592
3593
3594
3595
3596
3597
3598
3599
3600
3601
3602
3603
3604
3605
3606
3607
3608
3609
3610
3611
3612
3613
3614
3615
3616
3617
3618
3619
3620
3621
3622
3623
3624
3625
3626
3627
3628
3629
3630
3631
3632
3633
3634
3635
3636
3637
3638
3639
3640
3641
3642
3643
3644
3645
3646
3647
3648
3649
3650
3651
3652
3653
3654
3655
3656
3657
3658
3659
3660
3661
3662
3663
3664
3665
3666
3667
3668
3669
3670
3671
3672
3673
3674
3675
3676
3677
3678
3679
3680
3681
3682
3683
3684
3685
3686
3687
3688
3689
3690
3691
3692
3693
3694
3695
3696
3697
3698
3699
3700
3701
3702
3703
3704
3705
3706
3707
3708
3709
3710
3711
3712
3713
3714
3715
3716
3717
3718
3719
3720
3721
3722
3723
3724
3725
3726
3727
3728
3729
3730
3731
3732
3733
3734
3735
3736
3737
3738
3739
3740
3741
3742
3743
3744
3745
3746
3747
3748
3749
3750
3751
3752
3753
3754
3755
3756
3757
3758
3759
3760
3761
3762
3763
3764
3765
3766
3767
3768
3769
3770
3771
3772
3773
3774
3775
3776
3777
3778
3779
3780
3781
3782
3783
3784
3785
3786
3787
3788
3789
3790
3791
3792
3793
3794
3795
3796
3797
3798
3799
3800
3801
3802
3803
3804
3805
3806
3807
3808
3809
3810
3811
3812
3813
3814
3815
3816
3817
3818
3819
3820
3821
3822
3823
3824
3825
3826
3827
3828
3829
3830
3831
3832
3833
3834
3835
3836
3837
3838
3839
3840
3841
3842
3843
3844
3845
3846
3847
3848
3849
3850
3851
3852
3853
3854
3855
3856
3857
3858
3859
3860
3861
3862
3863
3864
3865
3866
3867
3868
3869
3870
3871
3872
3873
3874
3875
3876
3877
3878
3879
3880
3881
3882
3883
3884
3885
3886
3887
3888
3889
3890
3891
3892
3893
3894
3895
3896
3897
3898
3899
3900
3901
3902
3903
3904
3905
3906
3907
3908
3909
3910
3911
3912
3913
3914
3915
3916
3917
3918
3919
3920
3921
3922
3923
3924
3925
3926
3927
3928
3929
3930
3931
3932
3933
3934
3935
3936
3937
3938
3939
3940
3941
3942
3943
3944
3945
3946
3947
3948
3949
3950
3951
3952
3953
3954
3955
3956
3957
3958
3959
3960
3961
3962
3963
3964
3965
3966
3967
3968
3969
3970
3971
3972
3973
3974
3975
3976
3977
3978
3979
3980
3981
3982
3983
3984
3985
3986
3987
3988
3989
3990
3991
3992
3993
3994
3995
3996
3997
3998
3999
4000
4001
4002
4003
4004
4005
4006
4007
4008
4009
4010
4011
4012
4013
4014
4015
4016
4017
4018
4019
4020
4021
4022
4023
4024
4025
4026
4027
4028
4029
4030
4031
4032
4033
4034
4035
4036
4037
4038
4039
4040
4041
4042
4043
4044
4045
4046
4047
4048
4049
4050
4051
4052
4053
4054
4055
4056
4057
4058
4059
4060
4061
4062
4063
4064
4065
4066
4067
4068
4069
4070
4071
4072
4073
4074
4075
4076
4077
4078
4079
4080
4081
4082
4083
4084
4085
4086
4087
4088
4089
4090
4091
4092
4093
4094
4095
4096
4097
4098
4099
4100
4101
4102
4103
4104
4105
4106
4107
4108
4109
4110
4111
4112
4113
4114
4115
4116
4117
4118
4119
4120
4121
4122
4123
4124
4125
4126
4127
4128
4129
4130
4131
4132
4133
4134
4135
4136
4137
4138
4139
4140
4141
4142
4143
4144
4145
4146
4147
4148
4149
4150
4151
4152
4153
4154
4155
4156
4157
4158
4159
4160
4161
4162
4163
4164
4165
4166
4167
4168
4169
4170
4171
4172
4173
4174
4175
4176
4177
4178
4179
4180
4181
4182
4183
4184
4185
4186
4187
4188
4189
4190
4191
4192
4193
4194
4195
4196
4197
4198
4199
4200
4201
4202
4203
4204
4205
4206
4207
4208
4209
4210
4211
4212
4213
4214
4215
4216
4217
4218
4219
4220
4221
4222
4223
4224
4225
4226
4227
4228
4229
4230
4231
4232
4233
4234
4235
4236
4237
4238
4239
4240
4241
4242
4243
4244
4245
4246
4247
4248
4249
4250
4251
4252
4253
4254
4255
4256
4257
4258
4259
4260
4261
4262
4263
4264
4265
4266
4267
4268
4269
4270
4271
4272
4273
4274
4275
4276
4277
4278
4279
4280
4281
4282
4283
4284
4285
4286
4287
4288
4289
4290
4291
4292
4293
4294
4295
4296
4297
4298
4299
4300
4301
4302
4303
4304
4305
4306
4307
4308
4309
4310
4311
4312
4313
4314
4315
4316
4317
4318
4319
4320
4321
4322
4323
4324
4325
4326
4327
4328
4329
4330
4331
4332
4333
4334
4335
4336
4337
4338
4339
4340
4341
4342
4343
4344
4345
4346
4347
4348
4349
4350
4351
4352
4353
4354
4355
4356
4357
4358
4359
4360
4361
4362
4363
4364
4365
4366
4367
4368
4369
4370
4371
4372
4373
4374
4375
4376
4377
4378
4379
4380
4381
4382
4383
4384
4385
4386
4387
4388
4389
4390
4391
4392
4393
4394
4395
4396
4397
4398
4399
4400
4401
4402
4403
4404
4405
4406
4407
4408
4409
4410
4411
4412
4413
4414
4415
4416
4417
4418
4419
4420
4421
4422
4423
4424
4425
4426
4427
4428
4429
4430
4431
4432
4433
4434
4435
4436
4437
4438
4439
4440
4441
4442
4443
4444
4445
4446
4447
4448
4449
4450
4451
4452
4453
4454
4455
4456
4457
4458
4459
4460
4461
4462
4463
4464
4465
4466
4467
4468
4469
4470
4471
4472
4473
4474
4475
4476
4477
4478
4479
4480
4481
4482
4483
4484
4485
4486
4487
4488
4489
4490
4491
4492
4493
4494
4495
4496
4497
4498
4499
4500
4501
4502
4503
4504
4505
4506
4507
4508
4509
4510
4511
4512
4513
4514
4515
4516
4517
4518
4519
4520
4521
4522
4523
4524
4525
4526
4527
4528
4529
4530
4531
4532
4533
4534
4535
4536
4537
4538
4539
4540
4541
4542
4543
4544
4545
4546
4547
4548
4549
4550
4551
4552
4553
4554
4555
4556
4557
4558
4559
4560
4561
4562
4563
4564
4565
4566
4567
4568
4569
4570
4571
4572
4573
4574
4575
4576
4577
4578
4579
4580
4581
4582
4583
4584
4585
4586
4587
4588
4589
4590
4591
4592
4593
4594
4595
4596
4597
4598
4599
4600
4601
4602
4603
4604
4605
4606
4607
4608
4609
4610
4611
4612
4613
4614
4615
4616
4617
4618
4619
4620
4621
4622
4623
4624
4625
4626
4627
4628
4629
4630
4631
4632
4633
4634
4635
4636
4637
4638
4639
4640
4641
4642
4643
4644
4645
4646
4647
4648
4649
4650
4651
4652
4653
4654
4655
4656
4657
4658
4659
4660
4661
4662
4663
4664
4665
4666
4667
4668
4669
4670
4671
4672
4673
4674
4675
4676
4677
4678
4679
4680
4681
4682
4683
4684
4685
4686
4687
4688
4689
4690
4691
4692
4693
4694
4695
4696
4697
4698
4699
4700
4701
4702
4703
4704
4705
4706
4707
4708
4709
4710
4711
4712
4713
4714
4715
4716
4717
4718
4719
4720
4721
4722
4723
4724
4725
4726
4727
4728
4729
4730
4731
4732
4733
4734
4735
4736
4737
4738
4739
4740
4741
4742
4743
4744
4745
4746
4747
4748
4749
4750
4751
4752
4753
4754
4755
4756
4757
4758
4759
4760
4761
4762
4763
4764
4765
4766
4767
4768
4769
4770
4771
4772
4773
4774
4775
4776
4777
4778
4779
4780
4781
4782
4783
4784
4785
4786
4787
4788
4789
4790
4791
4792
4793
4794
4795
4796
4797
4798
4799
4800
4801
4802
4803
4804
4805
4806
4807
4808
4809
4810
4811
4812
4813
4814
4815
4816
4817
4818
4819
4820
4821
4822
4823
4824
4825
4826
4827
4828
4829
4830
4831
4832
4833
4834
4835
4836
4837
4838
4839
4840
4841
4842
4843
4844
4845
4846
4847
4848
4849
4850
4851
4852
4853
4854
4855
4856
4857
4858
4859
4860
4861
4862
4863
4864
4865
4866
4867
4868
4869
4870
4871
4872
4873
4874
4875
4876
4877
4878
4879
4880
4881
4882
4883
4884
4885
4886
4887
4888
4889
4890
4891
4892
4893
4894
4895
4896
4897
4898
4899
4900
4901
4902
4903
4904
4905
4906
4907
4908
4909
4910
4911
4912
4913
4914
4915
4916
4917
4918
4919
4920
4921
4922
4923
4924
4925
4926
4927
4928
4929
4930
4931
4932
4933
4934
4935
4936
4937
4938
4939
4940
4941
4942
4943
4944
4945
4946
4947
4948
4949
4950
4951
4952
4953
4954
4955
4956
4957
4958
4959
4960
4961
4962
4963
4964
4965
4966
4967
4968
4969
4970
4971
4972
4973
4974
4975
4976
4977
4978
4979
4980
4981
4982
4983
4984
4985
4986
4987
4988
4989
4990
4991
4992
4993
4994
4995
4996
4997
4998
4999
5000
5001
5002
5003
5004
5005
5006
5007
5008
5009
5010
5011
5012
5013
5014
5015
5016
5017
5018
5019
5020
5021
5022
5023
5024
5025
5026
5027
5028
5029
5030
5031
5032
5033
5034
5035
5036
5037
5038
5039
5040
5041
5042
5043
5044
5045
5046
5047
5048
5049
5050
5051
5052
5053
5054
5055
5056
5057
5058
5059
5060
5061
5062
5063
5064
5065
5066
5067
5068
5069
5070
5071
5072
5073
5074
5075
5076
5077
5078
5079
5080
5081
5082
5083
5084
5085
5086
5087
5088
5089
5090
5091
5092
5093
5094
5095
5096
5097
5098
5099
5100
5101
5102
5103
5104
5105
5106
5107
5108
5109
5110
5111
5112
5113
5114
5115
5116
5117
5118
5119
5120
5121
5122
5123
5124
5125
5126
5127
5128
5129
5130
5131
5132
5133
5134
5135
5136
5137
5138
5139
5140
5141
5142
5143
5144
5145
5146
5147
5148
5149
5150
5151
5152
5153
5154
5155
5156
5157
5158
5159
5160
5161
5162
5163
5164
5165
5166
5167
5168
5169
5170
5171
5172
5173
5174
5175
5176
5177
5178
5179
5180
5181
5182
5183
5184
5185
5186
5187
5188
5189
5190
5191
5192
5193
5194
5195
5196
5197
5198
5199
5200
5201
5202
5203
5204
5205
5206
5207
5208
5209
5210
5211
5212
5213
5214
5215
5216
5217
5218
5219
5220
5221
5222
5223
5224
5225
5226
5227
5228
5229
5230
5231
5232
5233
5234
5235
5236
5237
5238
5239
5240
5241
5242
5243
5244
5245
5246
5247
5248
5249
5250
5251
5252
5253
5254
5255
5256
5257
5258
5259
5260
5261
5262
5263
5264
5265
5266
5267
5268
5269
5270
5271
5272
5273
5274
5275
5276
5277
5278
5279
5280
5281
5282
5283
5284
5285
5286
5287
5288
5289
5290
5291
5292
5293
5294
5295
5296
5297
5298
5299
5300
5301
5302
5303
5304
5305
5306
5307
5308
5309
5310
5311
5312
5313
5314
5315
5316
5317
5318
5319
5320
5321
5322
5323
5324
5325
5326
5327
5328
5329
5330
5331
5332
5333
5334
5335
5336
5337
5338
5339
5340
5341
5342
5343
5344
5345
5346
5347
5348
5349
5350
5351
5352
5353
5354
5355
5356
5357
5358
5359
5360
5361
5362
5363
5364
5365
5366
5367
5368
5369
5370
5371
5372
5373
5374
5375
5376
5377
5378
5379
5380
5381
5382
5383
5384
5385
5386
5387
5388
5389
5390
5391
5392
5393
5394
5395
5396
5397
5398
5399
5400
5401
5402
5403
5404
5405
5406
5407
5408
5409
5410
5411
5412
5413
5414
5415
5416
5417
5418
5419
5420
5421
5422
5423
5424
5425
5426
5427
5428
5429
5430
5431
5432
5433
5434
5435
5436
5437
5438
5439
5440
5441
5442
5443
5444
5445
5446
5447
5448
5449
5450
5451
5452
5453
5454
5455
5456
5457
5458
5459
5460
5461
5462
5463
5464
5465
5466
5467
5468
5469
5470
5471
5472
5473
5474
5475
5476
5477
5478
5479
5480
5481
5482
5483
5484
5485
5486
5487
5488
5489
5490
5491
5492
5493
5494
5495
5496
5497
5498
5499
5500
5501
5502
5503
5504
5505
5506
5507
5508
5509
5510
5511
5512
5513
5514
5515
5516
5517
5518
5519
5520
5521
5522
5523
5524
5525
5526
5527
5528
5529
5530
5531
5532
5533
5534
5535
5536
5537
5538
5539
5540
5541
5542
5543
5544
5545
5546
5547
5548
5549
5550
5551
5552
5553
5554
5555
5556
5557
5558
5559
5560
5561
5562
5563
5564
5565
5566
5567
5568
5569
5570
5571
5572
5573
5574
5575
5576
5577
5578
5579
5580
5581
5582
5583
5584
5585
5586
5587
5588
5589
5590
5591
5592
5593
5594
5595
5596
5597
5598
5599
5600
5601
5602
5603
5604
5605
5606
5607
5608
5609
5610
5611
5612
5613
5614
5615
5616
5617
5618
5619
5620
5621
5622
5623
5624
5625
5626
5627
5628
5629
5630
5631
5632
5633
5634
5635
5636
5637
5638
5639
5640
5641
5642
5643
5644
5645
5646
5647
5648
5649
5650
5651
5652
5653
5654
5655
5656
5657
5658
5659
5660
5661
5662
5663
5664
5665
5666
5667
5668
5669
5670
5671
5672
5673
5674
5675
5676
5677
5678
5679
5680
5681
5682
5683
5684
5685
5686
5687
5688
5689
5690
5691
5692
5693
5694
5695
5696
5697
5698
5699
5700
5701
5702
5703
5704
5705
5706
5707
5708
5709
5710
5711
5712
5713
5714
5715
5716
5717
5718
5719
5720
5721
5722
5723
5724
5725
5726
5727
5728
5729
5730
5731
5732
5733
5734
5735
5736
5737
5738
5739
5740
5741
5742
5743
5744
5745
5746
5747
5748
5749
5750
5751
5752
5753
5754
5755
5756
5757
5758
5759
5760
5761
5762
5763
5764
5765
5766
5767
5768
5769
5770
5771
5772
5773
5774
5775
5776
5777
5778
5779
5780
5781
5782
5783
5784
5785
5786
5787
5788
5789
5790
5791
5792
5793
5794
5795
5796
5797
5798
5799
5800
5801
5802
5803
5804
5805
5806
5807
5808
5809
5810
5811
5812
5813
5814
5815
5816
5817
5818
5819
5820
5821
5822
5823
5824
5825
5826
5827
5828
5829
5830
5831
5832
5833
5834
5835
5836
5837
5838
5839
5840
5841
5842
5843
5844
5845
5846
5847
5848
5849
5850
5851
5852
5853
5854
5855
5856
5857
5858
5859
5860
5861
5862
5863
5864
5865
5866
5867
5868
5869
5870
5871
5872
5873
5874
5875
5876
5877
5878
5879
5880
5881
5882
5883
5884
5885
5886
5887
5888
5889
5890
5891
5892
5893
5894
5895
5896
5897
5898
5899
5900
5901
5902
5903
5904
5905
5906
5907
5908
5909
5910
5911
5912
5913
5914
5915
5916
5917
5918
5919
5920
5921
5922
5923
5924
5925
5926
5927
5928
5929
5930
5931
5932
5933
5934
5935
5936
5937
5938
5939
5940
5941
5942
5943
5944
5945
5946
5947
5948
5949
5950
5951
5952
5953
5954
5955
5956
5957
5958
5959
5960
5961
5962
5963
5964
5965
5966
5967
5968
5969
5970
5971
5972
5973
5974
5975
5976
5977
5978
5979
5980
5981
5982
5983
5984
5985
5986
5987
5988
5989
5990
5991
5992
5993
5994
5995
5996
5997
5998
5999
6000
6001
6002
6003
6004
6005
6006
6007
6008
6009
6010
6011
6012
6013
6014
6015
6016
6017
6018
6019
6020
6021
6022
6023
6024
6025
6026
6027
6028
6029
6030
6031
6032
6033
6034
6035
6036
6037
6038
6039
6040
6041
6042
6043
6044
6045
6046
6047
6048
6049
6050
6051
6052
6053
6054
6055
6056
6057
6058
6059
6060
6061
6062
6063
6064
6065
6066
6067
6068
6069
6070
6071
6072
6073
6074
6075
6076
6077
6078
6079
6080
6081
6082
6083
6084
6085
6086
6087
6088
6089
6090
6091
6092
6093
6094
6095
6096
6097
6098
6099
6100
6101
6102
6103
6104
6105
6106
6107
6108
6109
6110
6111
6112
6113
6114
6115
6116
6117
6118
6119
6120
6121
6122
6123
6124
6125
6126
6127
6128
6129
6130
6131
6132
6133
6134
6135
6136
6137
6138
6139
6140
6141
6142
6143
6144
6145
6146
6147
6148
6149
6150
6151
6152
6153
6154
6155
6156
6157
6158
6159
6160
6161
6162
6163
6164
6165
6166
6167
6168
6169
6170
6171
6172
6173
6174
6175
6176
6177
6178
6179
6180
6181
6182
6183
6184
6185
6186
6187
6188
6189
6190
6191
6192
6193
6194
6195
6196
6197
6198
6199
6200
6201
6202
6203
6204
6205
6206
6207
6208
6209
6210
6211
6212
6213
6214
6215
6216
6217
6218
6219
6220
6221
6222
6223
6224
6225
6226
6227
6228
6229
6230
6231
6232
6233
6234
6235
6236
6237
6238
6239
6240
6241
6242
6243
6244
6245
6246
6247
6248
6249
6250
6251
6252
6253
6254
6255
6256
6257
6258
6259
6260
6261
6262
6263
6264
6265
6266
6267
6268
6269
6270
6271
6272
6273
6274
6275
6276
6277
6278
6279
6280
6281
6282
6283
6284
6285
6286
6287
6288
6289
6290
6291
6292
6293
6294
6295
6296
6297
6298
6299
6300
6301
6302
6303
6304
6305
6306
6307
6308
6309
6310
6311
6312
6313
6314
6315
6316
6317
6318
6319
6320
6321
6322
6323
6324
6325
6326
6327
6328
6329
6330
6331
6332
6333
6334
6335
6336
6337
6338
6339
6340
6341
6342
6343
6344
6345
6346
6347
6348
6349
6350
6351
6352
6353
6354
6355
6356
6357
6358
6359
6360
6361
6362
6363
6364
6365
6366
6367
6368
6369
6370
6371
6372
6373
6374
6375
6376
6377
6378
6379
6380
6381
6382
6383
6384
6385
6386
6387
6388
6389
6390
6391
6392
6393
6394
6395
6396
6397
6398
6399
6400
6401
6402
6403
6404
6405
6406
6407
6408
6409
6410
6411
6412
6413
6414
6415
6416
6417
6418
6419
6420
6421
6422
6423
6424
6425
6426
6427
6428
6429
6430
6431
6432
6433
6434
6435
6436
6437
6438
6439
6440
6441
6442
6443
6444
6445
6446
6447
6448
6449
6450
6451
6452
6453
6454
6455
6456
6457
6458
6459
6460
6461
6462
6463
6464
6465
6466
6467
6468
6469
6470
6471
6472
6473
6474
6475
6476
6477
6478
6479
6480
6481
6482
6483
6484
6485
6486
6487
6488
6489
6490
6491
6492
6493
6494
6495
6496
6497
6498
6499
6500
6501
6502
6503
6504
6505
6506
6507
6508
6509
6510
6511
6512
6513
6514
6515
6516
6517
6518
6519
6520
6521
6522
6523
6524
6525
6526
6527
6528
6529
6530
6531
6532
6533
6534
6535
6536
6537
6538
6539
6540
6541
6542
6543
6544
6545
6546
6547
6548
6549
6550
6551
6552
6553
6554
6555
6556
6557
6558
6559
6560
6561
6562
6563
6564
6565
6566
6567
6568
6569
6570
6571
6572
6573
6574
6575
6576
6577
6578
6579
6580
6581
6582
6583
6584
6585
6586
6587
6588
6589
6590
6591
6592
6593
6594
6595
6596
6597
6598
6599
6600
6601
6602
6603
6604
6605
6606
6607
6608
6609
6610
6611
6612
6613
6614
6615
6616
6617
6618
6619
6620
6621
6622
6623
6624
6625
6626
6627
6628
6629
6630
6631
6632
6633
6634
6635
6636
6637
6638
6639
6640
6641
6642
6643
6644
6645
6646
6647
6648
6649
6650
6651
6652
6653
6654
6655
6656
6657
6658
6659
6660
6661
6662
6663
6664
6665
6666
6667
6668
6669
6670
6671
6672
6673
6674
6675
6676
6677
6678
6679
6680
6681
6682
6683
6684
6685
6686
6687
6688
6689
6690
6691
6692
6693
6694
6695
6696
6697
6698
6699
6700
6701
6702
6703
6704
6705
6706
6707
6708
6709
6710
6711
6712
6713
6714
6715
6716
6717
6718
6719
6720
6721
6722
6723
6724
6725
6726
6727
6728
6729
6730
6731
6732
6733
6734
6735
6736
6737
6738
6739
6740
6741
6742
6743
6744
6745
6746
6747
6748
6749
6750
6751
6752
6753
6754
6755
6756
6757
6758
6759
6760
6761
6762
6763
6764
6765
6766
6767
6768
6769
6770
6771
6772
6773
6774
6775
6776
6777
6778
6779
6780
6781
6782
6783
6784
6785
6786
6787
6788
6789
6790
6791
6792
6793
6794
6795
6796
6797
6798
6799
6800
6801
6802
6803
6804
6805
6806
6807
6808
6809
6810
6811
6812
6813
6814
6815
6816
6817
6818
6819
6820
6821
6822
6823
6824
6825
6826
6827
6828
6829
6830
6831
6832
6833
6834
6835
6836
6837
6838
6839
6840
6841
6842
6843
6844
6845
6846
6847
6848
6849
6850
6851
6852
6853
6854
6855
6856
6857
6858
6859
6860
6861
6862
6863
6864
6865
6866
6867
6868
6869
6870
6871
6872
6873
6874
6875
6876
6877
6878
6879
6880
6881
6882
6883
6884
6885
6886
6887
6888
6889
6890
6891
6892
6893
6894
6895
6896
6897
6898
6899
6900
6901
6902
6903
6904
6905
6906
6907
6908
6909
6910
6911
6912
6913
6914
6915
6916
6917
6918
6919
6920
6921
6922
6923
6924
6925
6926
6927
6928
6929
6930
6931
6932
6933
6934
6935
6936
6937
6938
6939
6940
6941
6942
6943
6944
6945
6946
6947
6948
6949
6950
6951
6952
6953
6954
6955
6956
6957
6958
6959
6960
6961
6962
6963
6964
6965
6966
6967
6968
6969
6970
6971
6972
6973
6974
6975
6976
6977
6978
6979
6980
6981
6982
6983
6984
6985
6986
6987
6988
6989
6990
6991
6992
6993
6994
6995
6996
6997
6998
6999
7000
7001
7002
7003
7004
7005
7006
7007
7008
7009
7010
7011
7012
7013
7014
7015
7016
7017
7018
7019
7020
7021
7022
7023
7024
7025
7026
7027
7028
7029
7030
7031
7032
7033
7034
7035
7036
7037
7038
7039
7040
7041
7042
7043
7044
7045
7046
7047
7048
7049
7050
7051
7052
7053
7054
7055
7056
7057
7058
7059
7060
7061
7062
7063
7064
7065
7066
7067
7068
7069
7070
7071
7072
7073
7074
7075
7076
7077
7078
7079
7080
7081
7082
7083
7084
7085
7086
7087
7088
7089
7090
7091
7092
7093
7094
7095
7096
7097
7098
7099
7100
7101
7102
7103
7104
7105
7106
7107
7108
7109
7110
7111
7112
7113
7114
7115
7116
7117
7118
7119
7120
7121
7122
7123
7124
7125
7126
7127
7128
7129
7130
7131
7132
7133
7134
7135
7136
7137
7138
7139
7140
7141
7142
7143
7144
7145
7146
7147
7148
7149
7150
7151
7152
7153
7154
7155
7156
7157
7158
7159
7160
7161
7162
7163
7164
7165
7166
7167
7168
7169
7170
7171
7172
7173
7174
7175
7176
7177
7178
7179
7180
7181
7182
7183
7184
7185
7186
7187
7188
7189
7190
7191
7192
7193
7194
7195
7196
7197
7198
7199
7200
7201
7202
7203
7204
7205
7206
7207
7208
7209
7210
7211
7212
7213
7214
7215
7216
7217
7218
7219
7220
7221
7222
7223
7224
7225
7226
7227
7228
7229
7230
7231
7232
7233
7234
7235
7236
7237
7238
7239
7240
7241
7242
7243
7244
7245
7246
7247
7248
7249
7250
7251
7252
7253
7254
7255
7256
7257
7258
7259
7260
7261
7262
7263
7264
7265
7266
7267
7268
7269
7270
7271
7272
7273
7274
7275
7276
7277
7278
7279
7280
7281
7282
7283
7284
7285
7286
7287
7288
7289
7290
7291
7292
7293
7294
7295
7296
7297
7298
7299
7300
7301
7302
7303
7304
7305
7306
7307
7308
7309
7310
7311
7312
7313
7314
7315
7316
7317
7318
7319
7320
7321
7322
7323
7324
7325
7326
7327
7328
7329
7330
7331
7332
7333
7334
7335
7336
7337
7338
7339
7340
7341
7342
7343
7344
7345
7346
7347
7348
7349
7350
7351
7352
7353
7354
7355
7356
7357
7358
7359
7360
7361
7362
7363
7364
7365
7366
7367
7368
7369
7370
7371
7372
7373
7374
7375
7376
7377
7378
7379
7380
7381
7382
7383
7384
7385
7386
7387
7388
7389
7390
7391
7392
7393
7394
7395
7396
7397
7398
7399
7400
7401
7402
7403
7404
7405
7406
7407
7408
7409
7410
7411
7412
7413
7414
7415
7416
7417
7418
7419
7420
7421
7422
7423
7424
7425
7426
7427
7428
7429
7430
7431
7432
7433
7434
7435
7436
7437
7438
7439
7440
7441
7442
7443
7444
7445
7446
7447
7448
7449
7450
7451
7452
7453
7454
7455
7456
7457
7458
7459
7460
7461
7462
7463
7464
7465
7466
7467
7468
7469
7470
7471
7472
7473
7474
7475
7476
7477
7478
7479
7480
7481
7482
7483
7484
7485
7486
7487
7488
7489
7490
7491
7492
7493
7494
7495
7496
7497
7498
7499
7500
7501
7502
7503
7504
7505
7506
7507
7508
7509
7510
7511
7512
7513
7514
7515
7516
7517
7518
7519
7520
7521
7522
7523
7524
7525
7526
7527
7528
7529
7530
7531
7532
7533
7534
7535
7536
7537
7538
7539
7540
7541
7542
7543
7544
7545
7546
7547
7548
7549
7550
7551
7552
7553
7554
7555
7556
7557
7558
7559
7560
7561
7562
7563
7564
7565
7566
7567
7568
7569
7570
7571
7572
7573
7574
7575
7576
7577
7578
7579
7580
7581
7582
7583
7584
7585
7586
7587
7588
7589
7590
7591
7592
7593
7594
7595
7596
7597
7598
7599
7600
7601
7602
7603
7604
7605
7606
7607
7608
7609
7610
7611
7612
7613
7614
7615
7616
7617
7618
7619
7620
7621
7622
7623
7624
7625
7626
7627
7628
7629
7630
7631
7632
7633
7634
7635
7636
7637
7638
7639
7640
7641
7642
7643
7644
7645
7646
7647
7648
7649
7650
7651
7652
7653
7654
7655
7656
7657
7658
7659
7660
7661
7662
7663
7664
7665
7666
7667
7668
7669
7670
7671
7672
7673
7674
7675
7676
7677
7678
7679
7680
7681
7682
7683
7684
7685
7686
7687
7688
7689
7690
7691
7692
7693
7694
7695
7696
7697
7698
7699
7700
7701
7702
7703
7704
7705
7706
7707
7708
7709
7710
7711
7712
7713
7714
7715
7716
7717
7718
7719
7720
7721
7722
7723
7724
7725
7726
7727
7728
7729
7730
7731
7732
7733
7734
7735
7736
7737
7738
7739
7740
7741
7742
7743
7744
7745
7746
7747
7748
7749
7750
7751
7752
7753
7754
7755
7756
7757
7758
7759
7760
7761
7762
7763
7764
7765
7766
7767
7768
7769
7770
7771
7772
7773
7774
7775
7776
7777
7778
7779
7780
7781
7782
7783
7784
7785
7786
7787
7788
7789
7790
7791
7792
7793
7794
7795
7796
7797
7798
7799
7800
7801
7802
7803
7804
7805
7806
7807
7808
7809
7810
7811
7812
7813
7814
7815
7816
7817
7818
7819
7820
7821
7822
7823
7824
7825
7826
7827
7828
7829
7830
7831
7832
7833
7834
7835
7836
7837
7838
7839
7840
7841
7842
7843
7844
7845
7846
7847
7848
7849
7850
7851
7852
7853
7854
7855
7856
7857
7858
7859
7860
7861
7862
7863
7864
7865
7866
7867
7868
7869
7870
7871
7872
7873
7874
7875
7876
7877
7878
7879
7880
7881
7882
7883
7884
7885
7886
7887
7888
7889
7890
7891
7892
7893
7894
7895
7896
7897
7898
7899
7900
7901
7902
7903
7904
7905
7906
7907
7908
7909
7910
7911
7912
7913
7914
7915
7916
7917
7918
7919
7920
7921
7922
7923
7924
7925
7926
7927
7928
7929
7930
7931
7932
7933
7934
7935
7936
7937
7938
7939
7940
7941
7942
7943
7944
7945
7946
7947
7948
7949
7950
7951
7952
7953
7954
7955
7956
7957
7958
7959
7960
7961
7962
7963
7964
7965
7966
7967
7968
7969
7970
7971
7972
7973
7974
7975
7976
7977
7978
7979
7980
7981
7982
7983
7984
7985
7986
7987
7988
7989
7990
7991
7992
7993
7994
7995
7996
7997
7998
7999
8000
8001
8002
8003
8004
8005
8006
8007
8008
8009
8010
8011
8012
8013
8014
8015
8016
8017
8018
8019
8020
8021
8022
8023
8024
8025
8026
8027
8028
8029
8030
8031
8032
8033
8034
8035
8036
8037
8038
8039
8040
8041
8042
8043
8044
8045
8046
8047
8048
8049
8050
8051
8052
8053
8054
8055
8056
8057
8058
8059
8060
8061
8062
8063
8064
8065
8066
8067
8068
8069
8070
8071
8072
8073
8074
8075
8076
8077
8078
8079
8080
8081
8082
8083
8084
8085
8086
8087
8088
8089
8090
8091
8092
8093
8094
8095
8096
8097
8098
8099
8100
8101
8102
8103
8104
8105
8106
8107
8108
8109
8110
8111
8112
8113
8114
8115
8116
8117
8118
8119
8120
8121
8122
8123
8124
8125
8126
8127
8128
8129
8130
8131
8132
8133
8134
8135
8136
8137
8138
8139
8140
8141
8142
8143
8144
8145
8146
8147
8148
8149
8150
8151
8152
8153
8154
8155
8156
8157
8158
8159
8160
8161
8162
8163
8164
8165
8166
8167
8168
8169
8170
8171
8172
8173
8174
8175
8176
8177
8178
8179
8180
8181
8182
8183
8184
8185
8186
8187
8188
8189
8190
8191
8192
8193
8194
8195
8196
8197
8198
8199
8200
8201
8202
8203
8204
8205
8206
8207
8208
8209
8210
8211
8212
8213
8214
8215
8216
8217
8218
8219
8220
8221
8222
8223
8224
8225
8226
8227
8228
8229
8230
8231
8232
8233
8234
8235
8236
8237
8238
8239
8240
8241
8242
8243
8244
8245
8246
8247
8248
8249
8250
8251
8252
8253
8254
8255
8256
8257
8258
8259
8260
8261
8262
8263
8264
8265
8266
8267
8268
8269
8270
8271
8272
8273
8274
8275
8276
8277
8278
8279
8280
8281
8282
8283
8284
8285
8286
8287
8288
8289
8290
8291
8292
8293
8294
8295
8296
8297
8298
8299
8300
8301
8302
8303
8304
8305
8306
8307
8308
8309
8310
8311
8312
8313
8314
8315
8316
8317
8318
8319
8320
8321
8322
8323
8324
8325
8326
8327
8328
8329
8330
8331
8332
8333
8334
8335
8336
8337
8338
8339
8340
8341
8342
8343
8344
8345
8346
8347
8348
8349
8350
8351
8352
8353
8354
8355
8356
8357
8358
8359
8360
8361
8362
8363
8364
8365
8366
8367
8368
8369
8370
8371
8372
8373
8374
8375
8376
8377
8378
8379
8380
8381
8382
8383
8384
8385
8386
8387
8388
8389
8390
8391
8392
8393
8394
8395
8396
8397
8398
8399
8400
8401
8402
8403
8404
8405
8406
8407
8408
8409
8410
8411
8412
8413
8414
8415
8416
8417
8418
8419
8420
8421
8422
8423
8424
8425
8426
8427
8428
8429
8430
8431
8432
8433
8434
8435
8436
8437
8438
8439
8440
8441
8442
8443
8444
8445
8446
8447
8448
8449
8450
8451
8452
8453
8454
8455
8456
8457
8458
8459
8460
8461
8462
8463
8464
8465
8466
8467
8468
8469
8470
8471
8472
8473
8474
8475
8476
8477
8478
8479
8480
8481
8482
8483
8484
8485
8486
8487
8488
8489
8490
8491
8492
8493
8494
8495
8496
8497
8498
8499
8500
8501
8502
8503
8504
8505
8506
8507
8508
8509
8510
8511
8512
8513
8514
8515
8516
8517
8518
8519
8520
8521
8522
8523
8524
8525
8526
8527
8528
8529
8530
8531
8532
8533
8534
8535
8536
8537
8538
8539
8540
8541
8542
8543
8544
8545
8546
8547
8548
8549
8550
8551
8552
8553
8554
8555
8556
8557
8558
8559
8560
8561
8562
8563
8564
8565
8566
8567
8568
8569
8570
8571
8572
8573
8574
8575
8576
8577
8578
8579
8580
8581
8582
8583
8584
8585
8586
8587
8588
8589
8590
8591
8592
8593
8594
8595
8596
8597
8598
8599
8600
8601
8602
8603
8604
8605
8606
8607
8608
8609
8610
8611
8612
8613
8614
8615
8616
8617
8618
8619
8620
8621
8622
8623
8624
8625
8626
8627
8628
8629
8630
8631
8632
8633
8634
8635
8636
8637
8638
8639
8640
8641
8642
8643
8644
8645
8646
8647
8648
8649
8650
8651
8652
8653
8654
8655
8656
8657
8658
8659
8660
8661
8662
8663
8664
8665
8666
8667
8668
8669
8670
8671
8672
8673
8674
8675
8676
8677
8678
8679
8680
8681
8682
8683
8684
8685
8686
8687
8688
8689
8690
8691
8692
8693
8694
8695
8696
8697
8698
8699
8700
8701
8702
8703
8704
8705
8706
8707
8708
8709
8710
8711
8712
8713
8714
8715
8716
8717
8718
8719
8720
8721
8722
8723
8724
8725
8726
8727
8728
8729
8730
8731
8732
8733
8734
8735
8736
8737
8738
8739
8740
8741
8742
8743
8744
8745
8746
8747
8748
8749
8750
8751
8752
8753
8754
8755
8756
8757
8758
8759
8760
8761
8762
8763
8764
8765
8766
8767
8768
8769
8770
8771
8772
8773
8774
8775
8776
8777
8778
8779
8780
/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
 * Copyright (c) 2011, 2019 by Delphix. All rights reserved.
 * Copyright (c) 2018, Nexenta Systems, Inc.  All rights reserved.
 * Copyright (c) 2014 Spectra Logic Corporation, All rights reserved.
 * Copyright 2013 Saso Kiselkov. All rights reserved.
 * Copyright (c) 2014 Integros [integros.com]
 * Copyright 2016 Toomas Soome <tsoome@me.com>
 * Copyright (c) 2016 Actifio, Inc. All rights reserved.
 * Copyright 2018 Joyent, Inc.
 * Copyright (c) 2017 Datto Inc.
 * Copyright 2017 Joyent, Inc.
 * Copyright (c) 2017, Intel Corporation.
 */

/*
 * SPA: Storage Pool Allocator
 *
 * This file contains all the routines used when modifying on-disk SPA state.
 * This includes opening, importing, destroying, exporting a pool, and syncing a
 * pool.
 */

#include <sys/zfs_context.h>
#include <sys/fm/fs/zfs.h>
#include <sys/spa_impl.h>
#include <sys/zio.h>
#include <sys/zio_checksum.h>
#include <sys/dmu.h>
#include <sys/dmu_tx.h>
#include <sys/zap.h>
#include <sys/zil.h>
#include <sys/ddt.h>
#include <sys/vdev_impl.h>
#include <sys/vdev_removal.h>
#include <sys/vdev_indirect_mapping.h>
#include <sys/vdev_indirect_births.h>
#include <sys/vdev_initialize.h>
#include <sys/vdev_trim.h>
#include <sys/vdev_disk.h>
#include <sys/metaslab.h>
#include <sys/metaslab_impl.h>
#include <sys/mmp.h>
#include <sys/uberblock_impl.h>
#include <sys/txg.h>
#include <sys/avl.h>
#include <sys/bpobj.h>
#include <sys/dmu_traverse.h>
#include <sys/dmu_objset.h>
#include <sys/unique.h>
#include <sys/dsl_pool.h>
#include <sys/dsl_dataset.h>
#include <sys/dsl_dir.h>
#include <sys/dsl_prop.h>
#include <sys/dsl_synctask.h>
#include <sys/fs/zfs.h>
#include <sys/arc.h>
#include <sys/callb.h>
#include <sys/systeminfo.h>
#include <sys/spa_boot.h>
#include <sys/zfs_ioctl.h>
#include <sys/dsl_scan.h>
#include <sys/zfeature.h>
#include <sys/dsl_destroy.h>
#include <sys/zvol.h>

#ifdef	_KERNEL
#include <sys/fm/protocol.h>
#include <sys/fm/util.h>
#include <sys/callb.h>
#include <sys/zone.h>
#endif	/* _KERNEL */

#include "zfs_prop.h"
#include "zfs_comutil.h"

/*
 * The interval, in seconds, at which failed configuration cache file writes
 * should be retried.
 */
int zfs_ccw_retry_interval = 300;

typedef enum zti_modes {
	ZTI_MODE_FIXED,			/* value is # of threads (min 1) */
	ZTI_MODE_BATCH,			/* cpu-intensive; value is ignored */
	ZTI_MODE_NULL,			/* don't create a taskq */
	ZTI_NMODES
} zti_modes_t;

#define	ZTI_P(n, q)	{ ZTI_MODE_FIXED, (n), (q) }
#define	ZTI_PCT(n)	{ ZTI_MODE_ONLINE_PERCENT, (n), 1 }
#define	ZTI_BATCH	{ ZTI_MODE_BATCH, 0, 1 }
#define	ZTI_NULL	{ ZTI_MODE_NULL, 0, 0 }

#define	ZTI_N(n)	ZTI_P(n, 1)
#define	ZTI_ONE		ZTI_N(1)

typedef struct zio_taskq_info {
	zti_modes_t zti_mode;
	uint_t zti_value;
	uint_t zti_count;
} zio_taskq_info_t;

static const char *const zio_taskq_types[ZIO_TASKQ_TYPES] = {
	"iss", "iss_h", "int", "int_h"
};

/*
 * This table defines the taskq settings for each ZFS I/O type. When
 * initializing a pool, we use this table to create an appropriately sized
 * taskq. Some operations are low volume and therefore have a small, static
 * number of threads assigned to their taskqs using the ZTI_N(#) or ZTI_ONE
 * macros. Other operations process a large amount of data; the ZTI_BATCH
 * macro causes us to create a taskq oriented for throughput. Some operations
 * are so high frequency and short-lived that the taskq itself can become a
 * point of lock contention. The ZTI_P(#, #) macro indicates that we need an
 * additional degree of parallelism specified by the number of threads per-
 * taskq and the number of taskqs; when dispatching an event in this case, the
 * particular taskq is chosen at random.
 *
 * The different taskq priorities are to handle the different contexts (issue
 * and interrupt) and then to reserve threads for ZIO_PRIORITY_NOW I/Os that
 * need to be handled with minimum delay.
 */
const zio_taskq_info_t zio_taskqs[ZIO_TYPES][ZIO_TASKQ_TYPES] = {
	/* ISSUE	ISSUE_HIGH	INTR		INTR_HIGH */
	{ ZTI_ONE,	ZTI_NULL,	ZTI_ONE,	ZTI_NULL }, /* NULL */
	{ ZTI_N(8),	ZTI_NULL,	ZTI_P(12, 8),	ZTI_NULL }, /* READ */
	{ ZTI_BATCH,	ZTI_N(5),	ZTI_P(12, 8),	ZTI_N(5) }, /* WRITE */
	{ ZTI_P(12, 8),	ZTI_NULL,	ZTI_ONE,	ZTI_NULL }, /* FREE */
	{ ZTI_ONE,	ZTI_NULL,	ZTI_ONE,	ZTI_NULL }, /* CLAIM */
	{ ZTI_ONE,	ZTI_NULL,	ZTI_ONE,	ZTI_NULL }, /* IOCTL */
	{ ZTI_N(4),	ZTI_NULL,	ZTI_ONE,	ZTI_NULL }, /* TRIM */
};

static void spa_sync_version(void *arg, dmu_tx_t *tx);
static void spa_sync_props(void *arg, dmu_tx_t *tx);
static boolean_t spa_has_active_shared_spare(spa_t *spa);
static int spa_load_impl(spa_t *spa, spa_import_type_t type, char **ereport);
static void spa_vdev_resilver_done(spa_t *spa);

uint_t		zio_taskq_batch_pct = 75;	/* 1 thread per cpu in pset */
boolean_t	zio_taskq_sysdc = B_TRUE;	/* use SDC scheduling class */
uint_t		zio_taskq_basedc = 80;		/* base duty cycle */

boolean_t	spa_create_process = B_TRUE;	/* no process ==> no sysdc */

/*
 * Report any spa_load_verify errors found, but do not fail spa_load.
 * This is used by zdb to analyze non-idle pools.
 */
boolean_t	spa_load_verify_dryrun = B_FALSE;

/*
 * This (illegal) pool name is used when temporarily importing a spa_t in order
 * to get the vdev stats associated with the imported devices.
 */
#define	TRYIMPORT_NAME	"$import"

/*
 * For debugging purposes: print out vdev tree during pool import.
 */
int		spa_load_print_vdev_tree = B_FALSE;

/*
 * A non-zero value for zfs_max_missing_tvds means that we allow importing
 * pools with missing top-level vdevs. This is strictly intended for advanced
 * pool recovery cases since missing data is almost inevitable. Pools with
 * missing devices can only be imported read-only for safety reasons, and their
 * fail-mode will be automatically set to "continue".
 *
 * With 1 missing vdev we should be able to import the pool and mount all
 * datasets. User data that was not modified after the missing device has been
 * added should be recoverable. This means that snapshots created prior to the
 * addition of that device should be completely intact.
 *
 * With 2 missing vdevs, some datasets may fail to mount since there are
 * dataset statistics that are stored as regular metadata. Some data might be
 * recoverable if those vdevs were added recently.
 *
 * With 3 or more missing vdevs, the pool is severely damaged and MOS entries
 * may be missing entirely. Chances of data recovery are very low. Note that
 * there are also risks of performing an inadvertent rewind as we might be
 * missing all the vdevs with the latest uberblocks.
 */
unsigned long	zfs_max_missing_tvds = 0;

/*
 * The parameters below are similar to zfs_max_missing_tvds but are only
 * intended for a preliminary open of the pool with an untrusted config which
 * might be incomplete or out-dated.
 *
 * We are more tolerant for pools opened from a cachefile since we could have
 * an out-dated cachefile where a device removal was not registered.
 * We could have set the limit arbitrarily high but in the case where devices
 * are really missing we would want to return the proper error codes; we chose
 * SPA_DVAS_PER_BP - 1 so that some copies of the MOS would still be available
 * and we get a chance to retrieve the trusted config.
 */
uint64_t	zfs_max_missing_tvds_cachefile = SPA_DVAS_PER_BP - 1;

/*
 * In the case where config was assembled by scanning device paths (/dev/dsks
 * by default) we are less tolerant since all the existing devices should have
 * been detected and we want spa_load to return the right error codes.
 */
uint64_t	zfs_max_missing_tvds_scan = 0;

/*
 * Debugging aid that pauses spa_sync() towards the end.
 */
boolean_t	zfs_pause_spa_sync = B_FALSE;

/*
 * ==========================================================================
 * SPA properties routines
 * ==========================================================================
 */

/*
 * Add a (source=src, propname=propval) list to an nvlist.
 */
static void
spa_prop_add_list(nvlist_t *nvl, zpool_prop_t prop, char *strval,
    uint64_t intval, zprop_source_t src)
{
	const char *propname = zpool_prop_to_name(prop);
	nvlist_t *propval;

	VERIFY(nvlist_alloc(&propval, NV_UNIQUE_NAME, KM_SLEEP) == 0);
	VERIFY(nvlist_add_uint64(propval, ZPROP_SOURCE, src) == 0);

	if (strval != NULL)
		VERIFY(nvlist_add_string(propval, ZPROP_VALUE, strval) == 0);
	else
		VERIFY(nvlist_add_uint64(propval, ZPROP_VALUE, intval) == 0);

	VERIFY(nvlist_add_nvlist(nvl, propname, propval) == 0);
	nvlist_free(propval);
}

/*
 * Get property values from the spa configuration.
 */
static void
spa_prop_get_config(spa_t *spa, nvlist_t **nvp)
{
	vdev_t *rvd = spa->spa_root_vdev;
	dsl_pool_t *pool = spa->spa_dsl_pool;
	uint64_t size, alloc, cap, version;
	const zprop_source_t src = ZPROP_SRC_NONE;
	spa_config_dirent_t *dp;
	metaslab_class_t *mc = spa_normal_class(spa);

	ASSERT(MUTEX_HELD(&spa->spa_props_lock));

	if (rvd != NULL) {
		alloc = metaslab_class_get_alloc(mc);
		alloc += metaslab_class_get_alloc(spa_special_class(spa));
		alloc += metaslab_class_get_alloc(spa_dedup_class(spa));

		size = metaslab_class_get_space(mc);
		size += metaslab_class_get_space(spa_special_class(spa));
		size += metaslab_class_get_space(spa_dedup_class(spa));

		spa_prop_add_list(*nvp, ZPOOL_PROP_NAME, spa_name(spa), 0, src);
		spa_prop_add_list(*nvp, ZPOOL_PROP_SIZE, NULL, size, src);
		spa_prop_add_list(*nvp, ZPOOL_PROP_ALLOCATED, NULL, alloc, src);
		spa_prop_add_list(*nvp, ZPOOL_PROP_FREE, NULL,
		    size - alloc, src);
		spa_prop_add_list(*nvp, ZPOOL_PROP_CHECKPOINT, NULL,
		    spa->spa_checkpoint_info.sci_dspace, src);

		spa_prop_add_list(*nvp, ZPOOL_PROP_FRAGMENTATION, NULL,
		    metaslab_class_fragmentation(mc), src);
		spa_prop_add_list(*nvp, ZPOOL_PROP_EXPANDSZ, NULL,
		    metaslab_class_expandable_space(mc), src);
		spa_prop_add_list(*nvp, ZPOOL_PROP_READONLY, NULL,
		    (spa_mode(spa) == FREAD), src);

		cap = (size == 0) ? 0 : (alloc * 100 / size);
		spa_prop_add_list(*nvp, ZPOOL_PROP_CAPACITY, NULL, cap, src);

		spa_prop_add_list(*nvp, ZPOOL_PROP_DEDUPRATIO, NULL,
		    ddt_get_pool_dedup_ratio(spa), src);

		spa_prop_add_list(*nvp, ZPOOL_PROP_HEALTH, NULL,
		    rvd->vdev_state, src);

		version = spa_version(spa);
		if (version == zpool_prop_default_numeric(ZPOOL_PROP_VERSION)) {
			spa_prop_add_list(*nvp, ZPOOL_PROP_VERSION, NULL,
			    version, ZPROP_SRC_DEFAULT);
		} else {
			spa_prop_add_list(*nvp, ZPOOL_PROP_VERSION, NULL,
			    version, ZPROP_SRC_LOCAL);
		}
		spa_prop_add_list(*nvp, ZPOOL_PROP_LOAD_GUID,
		    NULL, spa_load_guid(spa), src);
	}

	if (pool != NULL) {
		/*
		 * The $FREE directory was introduced in SPA_VERSION_DEADLISTS,
		 * when opening pools before this version freedir will be NULL.
		 */
		if (pool->dp_free_dir != NULL) {
			spa_prop_add_list(*nvp, ZPOOL_PROP_FREEING, NULL,
			    dsl_dir_phys(pool->dp_free_dir)->dd_used_bytes,
			    src);
		} else {
			spa_prop_add_list(*nvp, ZPOOL_PROP_FREEING,
			    NULL, 0, src);
		}

		if (pool->dp_leak_dir != NULL) {
			spa_prop_add_list(*nvp, ZPOOL_PROP_LEAKED, NULL,
			    dsl_dir_phys(pool->dp_leak_dir)->dd_used_bytes,
			    src);
		} else {
			spa_prop_add_list(*nvp, ZPOOL_PROP_LEAKED,
			    NULL, 0, src);
		}
	}

	spa_prop_add_list(*nvp, ZPOOL_PROP_GUID, NULL, spa_guid(spa), src);

	if (spa->spa_comment != NULL) {
		spa_prop_add_list(*nvp, ZPOOL_PROP_COMMENT, spa->spa_comment,
		    0, ZPROP_SRC_LOCAL);
	}

	if (spa->spa_root != NULL)
		spa_prop_add_list(*nvp, ZPOOL_PROP_ALTROOT, spa->spa_root,
		    0, ZPROP_SRC_LOCAL);

	if (spa_feature_is_enabled(spa, SPA_FEATURE_LARGE_BLOCKS)) {
		spa_prop_add_list(*nvp, ZPOOL_PROP_MAXBLOCKSIZE, NULL,
		    MIN(zfs_max_recordsize, SPA_MAXBLOCKSIZE), ZPROP_SRC_NONE);
	} else {
		spa_prop_add_list(*nvp, ZPOOL_PROP_MAXBLOCKSIZE, NULL,
		    SPA_OLD_MAXBLOCKSIZE, ZPROP_SRC_NONE);
	}

	if (spa_feature_is_enabled(spa, SPA_FEATURE_LARGE_DNODE)) {
		spa_prop_add_list(*nvp, ZPOOL_PROP_MAXDNODESIZE, NULL,
		    DNODE_MAX_SIZE, ZPROP_SRC_NONE);
	} else {
		spa_prop_add_list(*nvp, ZPOOL_PROP_MAXDNODESIZE, NULL,
		    DNODE_MIN_SIZE, ZPROP_SRC_NONE);
	}

	if ((dp = list_head(&spa->spa_config_list)) != NULL) {
		if (dp->scd_path == NULL) {
			spa_prop_add_list(*nvp, ZPOOL_PROP_CACHEFILE,
			    "none", 0, ZPROP_SRC_LOCAL);
		} else if (strcmp(dp->scd_path, spa_config_path) != 0) {
			spa_prop_add_list(*nvp, ZPOOL_PROP_CACHEFILE,
			    dp->scd_path, 0, ZPROP_SRC_LOCAL);
		}
	}
}

/*
 * Get zpool property values.
 */
int
spa_prop_get(spa_t *spa, nvlist_t **nvp)
{
	objset_t *mos = spa->spa_meta_objset;
	zap_cursor_t zc;
	zap_attribute_t za;
	int err;

	err = nvlist_alloc(nvp, NV_UNIQUE_NAME, KM_SLEEP);
	if (err)
		return (err);

	mutex_enter(&spa->spa_props_lock);

	/*
	 * Get properties from the spa config.
	 */
	spa_prop_get_config(spa, nvp);

	/* If no pool property object, no more prop to get. */
	if (mos == NULL || spa->spa_pool_props_object == 0) {
		mutex_exit(&spa->spa_props_lock);
		goto out;
	}

	/*
	 * Get properties from the MOS pool property object.
	 */
	for (zap_cursor_init(&zc, mos, spa->spa_pool_props_object);
	    (err = zap_cursor_retrieve(&zc, &za)) == 0;
	    zap_cursor_advance(&zc)) {
		uint64_t intval = 0;
		char *strval = NULL;
		zprop_source_t src = ZPROP_SRC_DEFAULT;
		zpool_prop_t prop;

		if ((prop = zpool_name_to_prop(za.za_name)) == ZPOOL_PROP_INVAL)
			continue;

		switch (za.za_integer_length) {
		case 8:
			/* integer property */
			if (za.za_first_integer !=
			    zpool_prop_default_numeric(prop))
				src = ZPROP_SRC_LOCAL;

			if (prop == ZPOOL_PROP_BOOTFS) {
				dsl_pool_t *dp;
				dsl_dataset_t *ds = NULL;

				dp = spa_get_dsl(spa);
				dsl_pool_config_enter(dp, FTAG);
				err = dsl_dataset_hold_obj(dp,
				    za.za_first_integer, FTAG, &ds);
				if (err != 0) {
					dsl_pool_config_exit(dp, FTAG);
					break;
				}

				strval = kmem_alloc(ZFS_MAX_DATASET_NAME_LEN,
				    KM_SLEEP);
				dsl_dataset_name(ds, strval);
				dsl_dataset_rele(ds, FTAG);
				dsl_pool_config_exit(dp, FTAG);
			} else {
				strval = NULL;
				intval = za.za_first_integer;
			}

			spa_prop_add_list(*nvp, prop, strval, intval, src);

			if (strval != NULL)
				kmem_free(strval, ZFS_MAX_DATASET_NAME_LEN);

			break;

		case 1:
			/* string property */
			strval = kmem_alloc(za.za_num_integers, KM_SLEEP);
			err = zap_lookup(mos, spa->spa_pool_props_object,
			    za.za_name, 1, za.za_num_integers, strval);
			if (err) {
				kmem_free(strval, za.za_num_integers);
				break;
			}
			spa_prop_add_list(*nvp, prop, strval, 0, src);
			kmem_free(strval, za.za_num_integers);
			break;

		default:
			break;
		}
	}
	zap_cursor_fini(&zc);
	mutex_exit(&spa->spa_props_lock);
out:
	if (err && err != ENOENT) {
		nvlist_free(*nvp);
		*nvp = NULL;
		return (err);
	}

	return (0);
}

/*
 * Validate the given pool properties nvlist and modify the list
 * for the property values to be set.
 */
static int
spa_prop_validate(spa_t *spa, nvlist_t *props)
{
	nvpair_t *elem;
	int error = 0, reset_bootfs = 0;
	uint64_t objnum = 0;
	boolean_t has_feature = B_FALSE;

	elem = NULL;
	while ((elem = nvlist_next_nvpair(props, elem)) != NULL) {
		uint64_t intval;
		char *strval, *slash, *check, *fname;
		const char *propname = nvpair_name(elem);
		zpool_prop_t prop = zpool_name_to_prop(propname);

		switch (prop) {
		case ZPOOL_PROP_INVAL:
			if (!zpool_prop_feature(propname)) {
				error = SET_ERROR(EINVAL);
				break;
			}

			/*
			 * Sanitize the input.
			 */
			if (nvpair_type(elem) != DATA_TYPE_UINT64) {
				error = SET_ERROR(EINVAL);
				break;
			}

			if (nvpair_value_uint64(elem, &intval) != 0) {
				error = SET_ERROR(EINVAL);
				break;
			}

			if (intval != 0) {
				error = SET_ERROR(EINVAL);
				break;
			}

			fname = strchr(propname, '@') + 1;
			if (zfeature_lookup_name(fname, NULL) != 0) {
				error = SET_ERROR(EINVAL);
				break;
			}

			has_feature = B_TRUE;
			break;

		case ZPOOL_PROP_VERSION:
			error = nvpair_value_uint64(elem, &intval);
			if (!error &&
			    (intval < spa_version(spa) ||
			    intval > SPA_VERSION_BEFORE_FEATURES ||
			    has_feature))
				error = SET_ERROR(EINVAL);
			break;

		case ZPOOL_PROP_DELEGATION:
		case ZPOOL_PROP_AUTOREPLACE:
		case ZPOOL_PROP_LISTSNAPS:
		case ZPOOL_PROP_AUTOEXPAND:
		case ZPOOL_PROP_AUTOTRIM:
			error = nvpair_value_uint64(elem, &intval);
			if (!error && intval > 1)
				error = SET_ERROR(EINVAL);
			break;

		case ZPOOL_PROP_MULTIHOST:
			error = nvpair_value_uint64(elem, &intval);
			if (!error && intval > 1)
				error = SET_ERROR(EINVAL);

			if (!error && !spa_get_hostid())
				error = SET_ERROR(ENOTSUP);

			break;

		case ZPOOL_PROP_BOOTFS:
			/*
			 * If the pool version is less than SPA_VERSION_BOOTFS,
			 * or the pool is still being created (version == 0),
			 * the bootfs property cannot be set.
			 */
			if (spa_version(spa) < SPA_VERSION_BOOTFS) {
				error = SET_ERROR(ENOTSUP);
				break;
			}

			/*
			 * Make sure the vdev config is bootable
			 */
			if (!vdev_is_bootable(spa->spa_root_vdev)) {
				error = SET_ERROR(ENOTSUP);
				break;
			}

			reset_bootfs = 1;

			error = nvpair_value_string(elem, &strval);

			if (!error) {
				objset_t *os;
				uint64_t propval;

				if (strval == NULL || strval[0] == '\0') {
					objnum = zpool_prop_default_numeric(
					    ZPOOL_PROP_BOOTFS);
					break;
				}

				error = dmu_objset_hold(strval, FTAG, &os);
				if (error != 0)
					break;

				/*
				 * Must be ZPL, and its property settings
				 * must be supported by GRUB (compression
				 * is not gzip, and large dnodes are not
				 * used).
				 */

				if (dmu_objset_type(os) != DMU_OST_ZFS) {
					error = SET_ERROR(ENOTSUP);
				} else if ((error =
				    dsl_prop_get_int_ds(dmu_objset_ds(os),
				    zfs_prop_to_name(ZFS_PROP_COMPRESSION),
				    &propval)) == 0 &&
				    !BOOTFS_COMPRESS_VALID(propval)) {
					error = SET_ERROR(ENOTSUP);
				} else if ((error =
				    dsl_prop_get_int_ds(dmu_objset_ds(os),
				    zfs_prop_to_name(ZFS_PROP_DNODESIZE),
				    &propval)) == 0 &&
				    propval != ZFS_DNSIZE_LEGACY) {
					error = SET_ERROR(ENOTSUP);
				} else {
					objnum = dmu_objset_id(os);
				}
				dmu_objset_rele(os, FTAG);
			}
			break;

		case ZPOOL_PROP_FAILUREMODE:
			error = nvpair_value_uint64(elem, &intval);
			if (!error && intval > ZIO_FAILURE_MODE_PANIC)
				error = SET_ERROR(EINVAL);

			/*
			 * This is a special case which only occurs when
			 * the pool has completely failed. This allows
			 * the user to change the in-core failmode property
			 * without syncing it out to disk (I/Os might
			 * currently be blocked). We do this by returning
			 * EIO to the caller (spa_prop_set) to trick it
			 * into thinking we encountered a property validation
			 * error.
			 */
			if (!error && spa_suspended(spa)) {
				spa->spa_failmode = intval;
				error = SET_ERROR(EIO);
			}
			break;

		case ZPOOL_PROP_CACHEFILE:
			if ((error = nvpair_value_string(elem, &strval)) != 0)
				break;

			if (strval[0] == '\0')
				break;

			if (strcmp(strval, "none") == 0)
				break;

			if (strval[0] != '/') {
				error = SET_ERROR(EINVAL);
				break;
			}

			slash = strrchr(strval, '/');
			ASSERT(slash != NULL);

			if (slash[1] == '\0' || strcmp(slash, "/.") == 0 ||
			    strcmp(slash, "/..") == 0)
				error = SET_ERROR(EINVAL);
			break;

		case ZPOOL_PROP_COMMENT:
			if ((error = nvpair_value_string(elem, &strval)) != 0)
				break;
			for (check = strval; *check != '\0'; check++) {
				if (!isprint(*check)) {
					error = SET_ERROR(EINVAL);
					break;
				}
			}
			if (strlen(strval) > ZPROP_MAX_COMMENT)
				error = SET_ERROR(E2BIG);
			break;

		case ZPOOL_PROP_DEDUPDITTO:
			if (spa_version(spa) < SPA_VERSION_DEDUP)
				error = SET_ERROR(ENOTSUP);
			else
				error = nvpair_value_uint64(elem, &intval);
			if (error == 0 &&
			    intval != 0 && intval < ZIO_DEDUPDITTO_MIN)
				error = SET_ERROR(EINVAL);
			break;

		default:
			break;
		}

		if (error)
			break;
	}

	if (!error && reset_bootfs) {
		error = nvlist_remove(props,
		    zpool_prop_to_name(ZPOOL_PROP_BOOTFS), DATA_TYPE_STRING);

		if (!error) {
			error = nvlist_add_uint64(props,
			    zpool_prop_to_name(ZPOOL_PROP_BOOTFS), objnum);
		}
	}

	return (error);
}

void
spa_configfile_set(spa_t *spa, nvlist_t *nvp, boolean_t need_sync)
{
	char *cachefile;
	spa_config_dirent_t *dp;

	if (nvlist_lookup_string(nvp, zpool_prop_to_name(ZPOOL_PROP_CACHEFILE),
	    &cachefile) != 0)
		return;

	dp = kmem_alloc(sizeof (spa_config_dirent_t),
	    KM_SLEEP);

	if (cachefile[0] == '\0')
		dp->scd_path = spa_strdup(spa_config_path);
	else if (strcmp(cachefile, "none") == 0)
		dp->scd_path = NULL;
	else
		dp->scd_path = spa_strdup(cachefile);

	list_insert_head(&spa->spa_config_list, dp);
	if (need_sync)
		spa_async_request(spa, SPA_ASYNC_CONFIG_UPDATE);
}

int
spa_prop_set(spa_t *spa, nvlist_t *nvp)
{
	int error;
	nvpair_t *elem = NULL;
	boolean_t need_sync = B_FALSE;

	if ((error = spa_prop_validate(spa, nvp)) != 0)
		return (error);

	while ((elem = nvlist_next_nvpair(nvp, elem)) != NULL) {
		zpool_prop_t prop = zpool_name_to_prop(nvpair_name(elem));

		if (prop == ZPOOL_PROP_CACHEFILE ||
		    prop == ZPOOL_PROP_ALTROOT ||
		    prop == ZPOOL_PROP_READONLY)
			continue;

		if (prop == ZPOOL_PROP_VERSION || prop == ZPOOL_PROP_INVAL) {
			uint64_t ver;

			if (prop == ZPOOL_PROP_VERSION) {
				VERIFY(nvpair_value_uint64(elem, &ver) == 0);
			} else {
				ASSERT(zpool_prop_feature(nvpair_name(elem)));
				ver = SPA_VERSION_FEATURES;
				need_sync = B_TRUE;
			}

			/* Save time if the version is already set. */
			if (ver == spa_version(spa))
				continue;

			/*
			 * In addition to the pool directory object, we might
			 * create the pool properties object, the features for
			 * read object, the features for write object, or the
			 * feature descriptions object.
			 */
			error = dsl_sync_task(spa->spa_name, NULL,
			    spa_sync_version, &ver,
			    6, ZFS_SPACE_CHECK_RESERVED);
			if (error)
				return (error);
			continue;
		}

		need_sync = B_TRUE;
		break;
	}

	if (need_sync) {
		return (dsl_sync_task(spa->spa_name, NULL, spa_sync_props,
		    nvp, 6, ZFS_SPACE_CHECK_RESERVED));
	}

	return (0);
}

/*
 * If the bootfs property value is dsobj, clear it.
 */
void
spa_prop_clear_bootfs(spa_t *spa, uint64_t dsobj, dmu_tx_t *tx)
{
	if (spa->spa_bootfs == dsobj && spa->spa_pool_props_object != 0) {
		VERIFY(zap_remove(spa->spa_meta_objset,
		    spa->spa_pool_props_object,
		    zpool_prop_to_name(ZPOOL_PROP_BOOTFS), tx) == 0);
		spa->spa_bootfs = 0;
	}
}

/*ARGSUSED*/
static int
spa_change_guid_check(void *arg, dmu_tx_t *tx)
{
	ASSERTV(uint64_t *newguid = arg);
	spa_t *spa = dmu_tx_pool(tx)->dp_spa;
	vdev_t *rvd = spa->spa_root_vdev;
	uint64_t vdev_state;

	if (spa_feature_is_active(spa, SPA_FEATURE_POOL_CHECKPOINT)) {
		int error = (spa_has_checkpoint(spa)) ?
		    ZFS_ERR_CHECKPOINT_EXISTS : ZFS_ERR_DISCARDING_CHECKPOINT;
		return (SET_ERROR(error));
	}

	spa_config_enter(spa, SCL_STATE, FTAG, RW_READER);
	vdev_state = rvd->vdev_state;
	spa_config_exit(spa, SCL_STATE, FTAG);

	if (vdev_state != VDEV_STATE_HEALTHY)
		return (SET_ERROR(ENXIO));

	ASSERT3U(spa_guid(spa), !=, *newguid);

	return (0);
}

static void
spa_change_guid_sync(void *arg, dmu_tx_t *tx)
{
	uint64_t *newguid = arg;
	spa_t *spa = dmu_tx_pool(tx)->dp_spa;
	uint64_t oldguid;
	vdev_t *rvd = spa->spa_root_vdev;

	oldguid = spa_guid(spa);

	spa_config_enter(spa, SCL_STATE, FTAG, RW_READER);
	rvd->vdev_guid = *newguid;
	rvd->vdev_guid_sum += (*newguid - oldguid);
	vdev_config_dirty(rvd);
	spa_config_exit(spa, SCL_STATE, FTAG);

	spa_history_log_internal(spa, "guid change", tx, "old=%llu new=%llu",
	    oldguid, *newguid);
}

/*
 * Change the GUID for the pool.  This is done so that we can later
 * re-import a pool built from a clone of our own vdevs.  We will modify
 * the root vdev's guid, our own pool guid, and then mark all of our
 * vdevs dirty.  Note that we must make sure that all our vdevs are
 * online when we do this, or else any vdevs that weren't present
 * would be orphaned from our pool.  We are also going to issue a
 * sysevent to update any watchers.
 */
int
spa_change_guid(spa_t *spa)
{
	int error;
	uint64_t guid;

	mutex_enter(&spa->spa_vdev_top_lock);
	mutex_enter(&spa_namespace_lock);
	guid = spa_generate_guid(NULL);

	error = dsl_sync_task(spa->spa_name, spa_change_guid_check,
	    spa_change_guid_sync, &guid, 5, ZFS_SPACE_CHECK_RESERVED);

	if (error == 0) {
		spa_write_cachefile(spa, B_FALSE, B_TRUE);
		spa_event_notify(spa, NULL, NULL, ESC_ZFS_POOL_REGUID);
	}

	mutex_exit(&spa_namespace_lock);
	mutex_exit(&spa->spa_vdev_top_lock);

	return (error);
}

/*
 * ==========================================================================
 * SPA state manipulation (open/create/destroy/import/export)
 * ==========================================================================
 */

static int
spa_error_entry_compare(const void *a, const void *b)
{
	const spa_error_entry_t *sa = (const spa_error_entry_t *)a;
	const spa_error_entry_t *sb = (const spa_error_entry_t *)b;
	int ret;

	ret = memcmp(&sa->se_bookmark, &sb->se_bookmark,
	    sizeof (zbookmark_phys_t));

	return (AVL_ISIGN(ret));
}

/*
 * Utility function which retrieves copies of the current logs and
 * re-initializes them in the process.
 */
void
spa_get_errlists(spa_t *spa, avl_tree_t *last, avl_tree_t *scrub)
{
	ASSERT(MUTEX_HELD(&spa->spa_errlist_lock));

	bcopy(&spa->spa_errlist_last, last, sizeof (avl_tree_t));
	bcopy(&spa->spa_errlist_scrub, scrub, sizeof (avl_tree_t));

	avl_create(&spa->spa_errlist_scrub,
	    spa_error_entry_compare, sizeof (spa_error_entry_t),
	    offsetof(spa_error_entry_t, se_avl));
	avl_create(&spa->spa_errlist_last,
	    spa_error_entry_compare, sizeof (spa_error_entry_t),
	    offsetof(spa_error_entry_t, se_avl));
}

static void
spa_taskqs_init(spa_t *spa, zio_type_t t, zio_taskq_type_t q)
{
	const zio_taskq_info_t *ztip = &zio_taskqs[t][q];
	enum zti_modes mode = ztip->zti_mode;
	uint_t value = ztip->zti_value;
	uint_t count = ztip->zti_count;
	spa_taskqs_t *tqs = &spa->spa_zio_taskq[t][q];
	uint_t flags = 0;
	boolean_t batch = B_FALSE;

	if (mode == ZTI_MODE_NULL) {
		tqs->stqs_count = 0;
		tqs->stqs_taskq = NULL;
		return;
	}

	ASSERT3U(count, >, 0);

	tqs->stqs_count = count;
	tqs->stqs_taskq = kmem_alloc(count * sizeof (taskq_t *), KM_SLEEP);

	switch (mode) {
	case ZTI_MODE_FIXED:
		ASSERT3U(value, >=, 1);
		value = MAX(value, 1);
		flags |= TASKQ_DYNAMIC;
		break;

	case ZTI_MODE_BATCH:
		batch = B_TRUE;
		flags |= TASKQ_THREADS_CPU_PCT;
		value = MIN(zio_taskq_batch_pct, 100);
		break;

	default:
		panic("unrecognized mode for %s_%s taskq (%u:%u) in "
		    "spa_activate()",
		    zio_type_name[t], zio_taskq_types[q], mode, value);
		break;
	}

	for (uint_t i = 0; i < count; i++) {
		taskq_t *tq;
		char name[32];

		(void) snprintf(name, sizeof (name), "%s_%s",
		    zio_type_name[t], zio_taskq_types[q]);

		if (zio_taskq_sysdc && spa->spa_proc != &p0) {
			if (batch)
				flags |= TASKQ_DC_BATCH;

			tq = taskq_create_sysdc(name, value, 50, INT_MAX,
			    spa->spa_proc, zio_taskq_basedc, flags);
		} else {
			pri_t pri = maxclsyspri;
			/*
			 * The write issue taskq can be extremely CPU
			 * intensive.  Run it at slightly less important
			 * priority than the other taskqs.  Under Linux this
			 * means incrementing the priority value on platforms
			 * like illumos it should be decremented.
			 */
			if (t == ZIO_TYPE_WRITE && q == ZIO_TASKQ_ISSUE)
				pri++;

			tq = taskq_create_proc(name, value, pri, 50,
			    INT_MAX, spa->spa_proc, flags);
		}

		tqs->stqs_taskq[i] = tq;
	}
}

static void
spa_taskqs_fini(spa_t *spa, zio_type_t t, zio_taskq_type_t q)
{
	spa_taskqs_t *tqs = &spa->spa_zio_taskq[t][q];

	if (tqs->stqs_taskq == NULL) {
		ASSERT3U(tqs->stqs_count, ==, 0);
		return;
	}

	for (uint_t i = 0; i < tqs->stqs_count; i++) {
		ASSERT3P(tqs->stqs_taskq[i], !=, NULL);
		taskq_destroy(tqs->stqs_taskq[i]);
	}

	kmem_free(tqs->stqs_taskq, tqs->stqs_count * sizeof (taskq_t *));
	tqs->stqs_taskq = NULL;
}

/*
 * Dispatch a task to the appropriate taskq for the ZFS I/O type and priority.
 * Note that a type may have multiple discrete taskqs to avoid lock contention
 * on the taskq itself. In that case we choose which taskq at random by using
 * the low bits of gethrtime().
 */
void
spa_taskq_dispatch_ent(spa_t *spa, zio_type_t t, zio_taskq_type_t q,
    task_func_t *func, void *arg, uint_t flags, taskq_ent_t *ent)
{
	spa_taskqs_t *tqs = &spa->spa_zio_taskq[t][q];
	taskq_t *tq;

	ASSERT3P(tqs->stqs_taskq, !=, NULL);
	ASSERT3U(tqs->stqs_count, !=, 0);

	if (tqs->stqs_count == 1) {
		tq = tqs->stqs_taskq[0];
	} else {
		tq = tqs->stqs_taskq[((uint64_t)gethrtime()) % tqs->stqs_count];
	}

	taskq_dispatch_ent(tq, func, arg, flags, ent);
}

/*
 * Same as spa_taskq_dispatch_ent() but block on the task until completion.
 */
void
spa_taskq_dispatch_sync(spa_t *spa, zio_type_t t, zio_taskq_type_t q,
    task_func_t *func, void *arg, uint_t flags)
{
	spa_taskqs_t *tqs = &spa->spa_zio_taskq[t][q];
	taskq_t *tq;
	taskqid_t id;

	ASSERT3P(tqs->stqs_taskq, !=, NULL);
	ASSERT3U(tqs->stqs_count, !=, 0);

	if (tqs->stqs_count == 1) {
		tq = tqs->stqs_taskq[0];
	} else {
		tq = tqs->stqs_taskq[((uint64_t)gethrtime()) % tqs->stqs_count];
	}

	id = taskq_dispatch(tq, func, arg, flags);
	if (id)
		taskq_wait_id(tq, id);
}

static void
spa_create_zio_taskqs(spa_t *spa)
{
	for (int t = 0; t < ZIO_TYPES; t++) {
		for (int q = 0; q < ZIO_TASKQ_TYPES; q++) {
			spa_taskqs_init(spa, t, q);
		}
	}
}

/*
 * Disabled until spa_thread() can be adapted for Linux.
 */
#undef HAVE_SPA_THREAD

#if defined(_KERNEL) && defined(HAVE_SPA_THREAD)
static void
spa_thread(void *arg)
{
	psetid_t zio_taskq_psrset_bind = PS_NONE;
	callb_cpr_t cprinfo;

	spa_t *spa = arg;
	user_t *pu = PTOU(curproc);

	CALLB_CPR_INIT(&cprinfo, &spa->spa_proc_lock, callb_generic_cpr,
	    spa->spa_name);

	ASSERT(curproc != &p0);
	(void) snprintf(pu->u_psargs, sizeof (pu->u_psargs),
	    "zpool-%s", spa->spa_name);
	(void) strlcpy(pu->u_comm, pu->u_psargs, sizeof (pu->u_comm));

	/* bind this thread to the requested psrset */
	if (zio_taskq_psrset_bind != PS_NONE) {
		pool_lock();
		mutex_enter(&cpu_lock);
		mutex_enter(&pidlock);
		mutex_enter(&curproc->p_lock);

		if (cpupart_bind_thread(curthread, zio_taskq_psrset_bind,
		    0, NULL, NULL) == 0)  {
			curthread->t_bind_pset = zio_taskq_psrset_bind;
		} else {
			cmn_err(CE_WARN,
			    "Couldn't bind process for zfs pool \"%s\" to "
			    "pset %d\n", spa->spa_name, zio_taskq_psrset_bind);
		}

		mutex_exit(&curproc->p_lock);
		mutex_exit(&pidlock);
		mutex_exit(&cpu_lock);
		pool_unlock();
	}

	if (zio_taskq_sysdc) {
		sysdc_thread_enter(curthread, 100, 0);
	}

	spa->spa_proc = curproc;
	spa->spa_did = curthread->t_did;

	spa_create_zio_taskqs(spa);

	mutex_enter(&spa->spa_proc_lock);
	ASSERT(spa->spa_proc_state == SPA_PROC_CREATED);

	spa->spa_proc_state = SPA_PROC_ACTIVE;
	cv_broadcast(&spa->spa_proc_cv);

	CALLB_CPR_SAFE_BEGIN(&cprinfo);
	while (spa->spa_proc_state == SPA_PROC_ACTIVE)
		cv_wait(&spa->spa_proc_cv, &spa->spa_proc_lock);
	CALLB_CPR_SAFE_END(&cprinfo, &spa->spa_proc_lock);

	ASSERT(spa->spa_proc_state == SPA_PROC_DEACTIVATE);
	spa->spa_proc_state = SPA_PROC_GONE;
	spa->spa_proc = &p0;
	cv_broadcast(&spa->spa_proc_cv);
	CALLB_CPR_EXIT(&cprinfo);	/* drops spa_proc_lock */

	mutex_enter(&curproc->p_lock);
	lwp_exit();
}
#endif

/*
 * Activate an uninitialized pool.
 */
static void
spa_activate(spa_t *spa, int mode)
{
	ASSERT(spa->spa_state == POOL_STATE_UNINITIALIZED);

	spa->spa_state = POOL_STATE_ACTIVE;
	spa->spa_mode = mode;

	spa->spa_normal_class = metaslab_class_create(spa, zfs_metaslab_ops);
	spa->spa_log_class = metaslab_class_create(spa, zfs_metaslab_ops);
	spa->spa_special_class = metaslab_class_create(spa, zfs_metaslab_ops);
	spa->spa_dedup_class = metaslab_class_create(spa, zfs_metaslab_ops);

	/* Try to create a covering process */
	mutex_enter(&spa->spa_proc_lock);
	ASSERT(spa->spa_proc_state == SPA_PROC_NONE);
	ASSERT(spa->spa_proc == &p0);
	spa->spa_did = 0;

#ifdef HAVE_SPA_THREAD
	/* Only create a process if we're going to be around a while. */
	if (spa_create_process && strcmp(spa->spa_name, TRYIMPORT_NAME) != 0) {
		if (newproc(spa_thread, (caddr_t)spa, syscid, maxclsyspri,
		    NULL, 0) == 0) {
			spa->spa_proc_state = SPA_PROC_CREATED;
			while (spa->spa_proc_state == SPA_PROC_CREATED) {
				cv_wait(&spa->spa_proc_cv,
				    &spa->spa_proc_lock);
			}
			ASSERT(spa->spa_proc_state == SPA_PROC_ACTIVE);
			ASSERT(spa->spa_proc != &p0);
			ASSERT(spa->spa_did != 0);
		} else {
#ifdef _KERNEL
			cmn_err(CE_WARN,
			    "Couldn't create process for zfs pool \"%s\"\n",
			    spa->spa_name);
#endif
		}
	}
#endif /* HAVE_SPA_THREAD */
	mutex_exit(&spa->spa_proc_lock);

	/* If we didn't create a process, we need to create our taskqs. */
	if (spa->spa_proc == &p0) {
		spa_create_zio_taskqs(spa);
	}

	for (size_t i = 0; i < TXG_SIZE; i++) {
		spa->spa_txg_zio[i] = zio_root(spa, NULL, NULL,
		    ZIO_FLAG_CANFAIL);
	}

	list_create(&spa->spa_config_dirty_list, sizeof (vdev_t),
	    offsetof(vdev_t, vdev_config_dirty_node));
	list_create(&spa->spa_evicting_os_list, sizeof (objset_t),
	    offsetof(objset_t, os_evicting_node));
	list_create(&spa->spa_state_dirty_list, sizeof (vdev_t),
	    offsetof(vdev_t, vdev_state_dirty_node));

	txg_list_create(&spa->spa_vdev_txg_list, spa,
	    offsetof(struct vdev, vdev_txg_node));

	avl_create(&spa->spa_errlist_scrub,
	    spa_error_entry_compare, sizeof (spa_error_entry_t),
	    offsetof(spa_error_entry_t, se_avl));
	avl_create(&spa->spa_errlist_last,
	    spa_error_entry_compare, sizeof (spa_error_entry_t),
	    offsetof(spa_error_entry_t, se_avl));

	spa_keystore_init(&spa->spa_keystore);

	/*
	 * This taskq is used to perform zvol-minor-related tasks
	 * asynchronously. This has several advantages, including easy
	 * resolution of various deadlocks (zfsonlinux bug #3681).
	 *
	 * The taskq must be single threaded to ensure tasks are always
	 * processed in the order in which they were dispatched.
	 *
	 * A taskq per pool allows one to keep the pools independent.
	 * This way if one pool is suspended, it will not impact another.
	 *
	 * The preferred location to dispatch a zvol minor task is a sync
	 * task. In this context, there is easy access to the spa_t and minimal
	 * error handling is required because the sync task must succeed.
	 */
	spa->spa_zvol_taskq = taskq_create("z_zvol", 1, defclsyspri,
	    1, INT_MAX, 0);

	/*
	 * Taskq dedicated to prefetcher threads: this is used to prevent the
	 * pool traverse code from monopolizing the global (and limited)
	 * system_taskq by inappropriately scheduling long running tasks on it.
	 */
	spa->spa_prefetch_taskq = taskq_create("z_prefetch", boot_ncpus,
	    defclsyspri, 1, INT_MAX, TASKQ_DYNAMIC);

	/*
	 * The taskq to upgrade datasets in this pool. Currently used by
	 * feature SPA_FEATURE_USEROBJ_ACCOUNTING/SPA_FEATURE_PROJECT_QUOTA.
	 */
	spa->spa_upgrade_taskq = taskq_create("z_upgrade", boot_ncpus,
	    defclsyspri, 1, INT_MAX, TASKQ_DYNAMIC);
}

/*
 * Opposite of spa_activate().
 */
static void
spa_deactivate(spa_t *spa)
{
	ASSERT(spa->spa_sync_on == B_FALSE);
	ASSERT(spa->spa_dsl_pool == NULL);
	ASSERT(spa->spa_root_vdev == NULL);
	ASSERT(spa->spa_async_zio_root == NULL);
	ASSERT(spa->spa_state != POOL_STATE_UNINITIALIZED);

	spa_evicting_os_wait(spa);

	if (spa->spa_zvol_taskq) {
		taskq_destroy(spa->spa_zvol_taskq);
		spa->spa_zvol_taskq = NULL;
	}

	if (spa->spa_prefetch_taskq) {
		taskq_destroy(spa->spa_prefetch_taskq);
		spa->spa_prefetch_taskq = NULL;
	}

	if (spa->spa_upgrade_taskq) {
		taskq_destroy(spa->spa_upgrade_taskq);
		spa->spa_upgrade_taskq = NULL;
	}

	txg_list_destroy(&spa->spa_vdev_txg_list);

	list_destroy(&spa->spa_config_dirty_list);
	list_destroy(&spa->spa_evicting_os_list);
	list_destroy(&spa->spa_state_dirty_list);

	taskq_cancel_id(system_delay_taskq, spa->spa_deadman_tqid);

	for (int t = 0; t < ZIO_TYPES; t++) {
		for (int q = 0; q < ZIO_TASKQ_TYPES; q++) {
			spa_taskqs_fini(spa, t, q);
		}
	}

	for (size_t i = 0; i < TXG_SIZE; i++) {
		ASSERT3P(spa->spa_txg_zio[i], !=, NULL);
		VERIFY0(zio_wait(spa->spa_txg_zio[i]));
		spa->spa_txg_zio[i] = NULL;
	}

	metaslab_class_destroy(spa->spa_normal_class);
	spa->spa_normal_class = NULL;

	metaslab_class_destroy(spa->spa_log_class);
	spa->spa_log_class = NULL;

	metaslab_class_destroy(spa->spa_special_class);
	spa->spa_special_class = NULL;

	metaslab_class_destroy(spa->spa_dedup_class);
	spa->spa_dedup_class = NULL;

	/*
	 * If this was part of an import or the open otherwise failed, we may
	 * still have errors left in the queues.  Empty them just in case.
	 */
	spa_errlog_drain(spa);
	avl_destroy(&spa->spa_errlist_scrub);
	avl_destroy(&spa->spa_errlist_last);

	spa_keystore_fini(&spa->spa_keystore);

	spa->spa_state = POOL_STATE_UNINITIALIZED;

	mutex_enter(&spa->spa_proc_lock);
	if (spa->spa_proc_state != SPA_PROC_NONE) {
		ASSERT(spa->spa_proc_state == SPA_PROC_ACTIVE);
		spa->spa_proc_state = SPA_PROC_DEACTIVATE;
		cv_broadcast(&spa->spa_proc_cv);
		while (spa->spa_proc_state == SPA_PROC_DEACTIVATE) {
			ASSERT(spa->spa_proc != &p0);
			cv_wait(&spa->spa_proc_cv, &spa->spa_proc_lock);
		}
		ASSERT(spa->spa_proc_state == SPA_PROC_GONE);
		spa->spa_proc_state = SPA_PROC_NONE;
	}
	ASSERT(spa->spa_proc == &p0);
	mutex_exit(&spa->spa_proc_lock);

	/*
	 * We want to make sure spa_thread() has actually exited the ZFS
	 * module, so that the module can't be unloaded out from underneath
	 * it.
	 */
	if (spa->spa_did != 0) {
		thread_join(spa->spa_did);
		spa->spa_did = 0;
	}
}

/*
 * Verify a pool configuration, and construct the vdev tree appropriately.  This
 * will create all the necessary vdevs in the appropriate layout, with each vdev
 * in the CLOSED state.  This will prep the pool before open/creation/import.
 * All vdev validation is done by the vdev_alloc() routine.
 */
static int
spa_config_parse(spa_t *spa, vdev_t **vdp, nvlist_t *nv, vdev_t *parent,
    uint_t id, int atype)
{
	nvlist_t **child;
	uint_t children;
	int error;

	if ((error = vdev_alloc(spa, vdp, nv, parent, id, atype)) != 0)
		return (error);

	if ((*vdp)->vdev_ops->vdev_op_leaf)
		return (0);

	error = nvlist_lookup_nvlist_array(nv, ZPOOL_CONFIG_CHILDREN,
	    &child, &children);

	if (error == ENOENT)
		return (0);

	if (error) {
		vdev_free(*vdp);
		*vdp = NULL;
		return (SET_ERROR(EINVAL));
	}

	for (int c = 0; c < children; c++) {
		vdev_t *vd;
		if ((error = spa_config_parse(spa, &vd, child[c], *vdp, c,
		    atype)) != 0) {
			vdev_free(*vdp);
			*vdp = NULL;
			return (error);
		}
	}

	ASSERT(*vdp != NULL);

	return (0);
}

/*
 * Opposite of spa_load().
 */
static void
spa_unload(spa_t *spa)
{
	int i;

	ASSERT(MUTEX_HELD(&spa_namespace_lock));

	spa_import_progress_remove(spa_guid(spa));
	spa_load_note(spa, "UNLOADING");

	/*
	 * Stop async tasks.
	 */
	spa_async_suspend(spa);

	if (spa->spa_root_vdev) {
		vdev_t *root_vdev = spa->spa_root_vdev;
		vdev_initialize_stop_all(root_vdev, VDEV_INITIALIZE_ACTIVE);
		vdev_trim_stop_all(root_vdev, VDEV_TRIM_ACTIVE);
		vdev_autotrim_stop_all(spa);
	}

	/*
	 * Stop syncing.
	 */
	if (spa->spa_sync_on) {
		txg_sync_stop(spa->spa_dsl_pool);
		spa->spa_sync_on = B_FALSE;
	}

	/*
	 * Even though vdev_free() also calls vdev_metaslab_fini, we need
	 * to call it earlier, before we wait for async i/o to complete.
	 * This ensures that there is no async metaslab prefetching, by
	 * calling taskq_wait(mg_taskq).
	 */
	if (spa->spa_root_vdev != NULL) {
		spa_config_enter(spa, SCL_ALL, spa, RW_WRITER);
		for (int c = 0; c < spa->spa_root_vdev->vdev_children; c++)
			vdev_metaslab_fini(spa->spa_root_vdev->vdev_child[c]);
		spa_config_exit(spa, SCL_ALL, spa);
	}

	if (spa->spa_mmp.mmp_thread)
		mmp_thread_stop(spa);

	/*
	 * Wait for any outstanding async I/O to complete.
	 */
	if (spa->spa_async_zio_root != NULL) {
		for (int i = 0; i < max_ncpus; i++)
			(void) zio_wait(spa->spa_async_zio_root[i]);
		kmem_free(spa->spa_async_zio_root, max_ncpus * sizeof (void *));
		spa->spa_async_zio_root = NULL;
	}

	if (spa->spa_vdev_removal != NULL) {
		spa_vdev_removal_destroy(spa->spa_vdev_removal);
		spa->spa_vdev_removal = NULL;
	}

	if (spa->spa_condense_zthr != NULL) {
		zthr_destroy(spa->spa_condense_zthr);
		spa->spa_condense_zthr = NULL;
	}

	if (spa->spa_checkpoint_discard_zthr != NULL) {
		zthr_destroy(spa->spa_checkpoint_discard_zthr);
		spa->spa_checkpoint_discard_zthr = NULL;
	}

	spa_condense_fini(spa);

	bpobj_close(&spa->spa_deferred_bpobj);

	spa_config_enter(spa, SCL_ALL, spa, RW_WRITER);

	/*
	 * Close all vdevs.
	 */
	if (spa->spa_root_vdev)
		vdev_free(spa->spa_root_vdev);
	ASSERT(spa->spa_root_vdev == NULL);

	/*
	 * Close the dsl pool.
	 */
	if (spa->spa_dsl_pool) {
		dsl_pool_close(spa->spa_dsl_pool);
		spa->spa_dsl_pool = NULL;
		spa->spa_meta_objset = NULL;
	}

	ddt_unload(spa);

	/*
	 * Drop and purge level 2 cache
	 */
	spa_l2cache_drop(spa);

	for (i = 0; i < spa->spa_spares.sav_count; i++)
		vdev_free(spa->spa_spares.sav_vdevs[i]);
	if (spa->spa_spares.sav_vdevs) {
		kmem_free(spa->spa_spares.sav_vdevs,
		    spa->spa_spares.sav_count * sizeof (void *));
		spa->spa_spares.sav_vdevs = NULL;
	}
	if (spa->spa_spares.sav_config) {
		nvlist_free(spa->spa_spares.sav_config);
		spa->spa_spares.sav_config = NULL;
	}
	spa->spa_spares.sav_count = 0;

	for (i = 0; i < spa->spa_l2cache.sav_count; i++) {
		vdev_clear_stats(spa->spa_l2cache.sav_vdevs[i]);
		vdev_free(spa->spa_l2cache.sav_vdevs[i]);
	}
	if (spa->spa_l2cache.sav_vdevs) {
		kmem_free(spa->spa_l2cache.sav_vdevs,
		    spa->spa_l2cache.sav_count * sizeof (void *));
		spa->spa_l2cache.sav_vdevs = NULL;
	}
	if (spa->spa_l2cache.sav_config) {
		nvlist_free(spa->spa_l2cache.sav_config);
		spa->spa_l2cache.sav_config = NULL;
	}
	spa->spa_l2cache.sav_count = 0;

	spa->spa_async_suspended = 0;

	spa->spa_indirect_vdevs_loaded = B_FALSE;

	if (spa->spa_comment != NULL) {
		spa_strfree(spa->spa_comment);
		spa->spa_comment = NULL;
	}

	spa_config_exit(spa, SCL_ALL, spa);
}

/*
 * Load (or re-load) the current list of vdevs describing the active spares for
 * this pool.  When this is called, we have some form of basic information in
 * 'spa_spares.sav_config'.  We parse this into vdevs, try to open them, and
 * then re-generate a more complete list including status information.
 */
void
spa_load_spares(spa_t *spa)
{
	nvlist_t **spares;
	uint_t nspares;
	int i;
	vdev_t *vd, *tvd;

#ifndef _KERNEL
	/*
	 * zdb opens both the current state of the pool and the
	 * checkpointed state (if present), with a different spa_t.
	 *
	 * As spare vdevs are shared among open pools, we skip loading
	 * them when we load the checkpointed state of the pool.
	 */
	if (!spa_writeable(spa))
		return;
#endif

	ASSERT(spa_config_held(spa, SCL_ALL, RW_WRITER) == SCL_ALL);

	/*
	 * First, close and free any existing spare vdevs.
	 */
	for (i = 0; i < spa->spa_spares.sav_count; i++) {
		vd = spa->spa_spares.sav_vdevs[i];

		/* Undo the call to spa_activate() below */
		if ((tvd = spa_lookup_by_guid(spa, vd->vdev_guid,
		    B_FALSE)) != NULL && tvd->vdev_isspare)
			spa_spare_remove(tvd);
		vdev_close(vd);
		vdev_free(vd);
	}

	if (spa->spa_spares.sav_vdevs)
		kmem_free(spa->spa_spares.sav_vdevs,
		    spa->spa_spares.sav_count * sizeof (void *));

	if (spa->spa_spares.sav_config == NULL)
		nspares = 0;
	else
		VERIFY(nvlist_lookup_nvlist_array(spa->spa_spares.sav_config,
		    ZPOOL_CONFIG_SPARES, &spares, &nspares) == 0);

	spa->spa_spares.sav_count = (int)nspares;
	spa->spa_spares.sav_vdevs = NULL;

	if (nspares == 0)
		return;

	/*
	 * Construct the array of vdevs, opening them to get status in the
	 * process.   For each spare, there is potentially two different vdev_t
	 * structures associated with it: one in the list of spares (used only
	 * for basic validation purposes) and one in the active vdev
	 * configuration (if it's spared in).  During this phase we open and
	 * validate each vdev on the spare list.  If the vdev also exists in the
	 * active configuration, then we also mark this vdev as an active spare.
	 */
	spa->spa_spares.sav_vdevs = kmem_zalloc(nspares * sizeof (void *),
	    KM_SLEEP);
	for (i = 0; i < spa->spa_spares.sav_count; i++) {
		VERIFY(spa_config_parse(spa, &vd, spares[i], NULL, 0,
		    VDEV_ALLOC_SPARE) == 0);
		ASSERT(vd != NULL);

		spa->spa_spares.sav_vdevs[i] = vd;

		if ((tvd = spa_lookup_by_guid(spa, vd->vdev_guid,
		    B_FALSE)) != NULL) {
			if (!tvd->vdev_isspare)
				spa_spare_add(tvd);

			/*
			 * We only mark the spare active if we were successfully
			 * able to load the vdev.  Otherwise, importing a pool
			 * with a bad active spare would result in strange
			 * behavior, because multiple pool would think the spare
			 * is actively in use.
			 *
			 * There is a vulnerability here to an equally bizarre
			 * circumstance, where a dead active spare is later
			 * brought back to life (onlined or otherwise).  Given
			 * the rarity of this scenario, and the extra complexity
			 * it adds, we ignore the possibility.
			 */
			if (!vdev_is_dead(tvd))
				spa_spare_activate(tvd);
		}

		vd->vdev_top = vd;
		vd->vdev_aux = &spa->spa_spares;

		if (vdev_open(vd) != 0)
			continue;

		if (vdev_validate_aux(vd) == 0)
			spa_spare_add(vd);
	}

	/*
	 * Recompute the stashed list of spares, with status information
	 * this time.
	 */
	VERIFY(nvlist_remove(spa->spa_spares.sav_config, ZPOOL_CONFIG_SPARES,
	    DATA_TYPE_NVLIST_ARRAY) == 0);

	spares = kmem_alloc(spa->spa_spares.sav_count * sizeof (void *),
	    KM_SLEEP);
	for (i = 0; i < spa->spa_spares.sav_count; i++)
		spares[i] = vdev_config_generate(spa,
		    spa->spa_spares.sav_vdevs[i], B_TRUE, VDEV_CONFIG_SPARE);
	VERIFY(nvlist_add_nvlist_array(spa->spa_spares.sav_config,
	    ZPOOL_CONFIG_SPARES, spares, spa->spa_spares.sav_count) == 0);
	for (i = 0; i < spa->spa_spares.sav_count; i++)
		nvlist_free(spares[i]);
	kmem_free(spares, spa->spa_spares.sav_count * sizeof (void *));
}

/*
 * Load (or re-load) the current list of vdevs describing the active l2cache for
 * this pool.  When this is called, we have some form of basic information in
 * 'spa_l2cache.sav_config'.  We parse this into vdevs, try to open them, and
 * then re-generate a more complete list including status information.
 * Devices which are already active have their details maintained, and are
 * not re-opened.
 */
void
spa_load_l2cache(spa_t *spa)
{
	nvlist_t **l2cache = NULL;
	uint_t nl2cache;
	int i, j, oldnvdevs;
	uint64_t guid;
	vdev_t *vd, **oldvdevs, **newvdevs;
	spa_aux_vdev_t *sav = &spa->spa_l2cache;

#ifndef _KERNEL
	/*
	 * zdb opens both the current state of the pool and the
	 * checkpointed state (if present), with a different spa_t.
	 *
	 * As L2 caches are part of the ARC which is shared among open
	 * pools, we skip loading them when we load the checkpointed
	 * state of the pool.
	 */
	if (!spa_writeable(spa))
		return;
#endif

	ASSERT(spa_config_held(spa, SCL_ALL, RW_WRITER) == SCL_ALL);

	oldvdevs = sav->sav_vdevs;
	oldnvdevs = sav->sav_count;
	sav->sav_vdevs = NULL;
	sav->sav_count = 0;

	if (sav->sav_config == NULL) {
		nl2cache = 0;
		newvdevs = NULL;
		goto out;
	}

	VERIFY(nvlist_lookup_nvlist_array(sav->sav_config,
	    ZPOOL_CONFIG_L2CACHE, &l2cache, &nl2cache) == 0);
	newvdevs = kmem_alloc(nl2cache * sizeof (void *), KM_SLEEP);

	/*
	 * Process new nvlist of vdevs.
	 */
	for (i = 0; i < nl2cache; i++) {
		VERIFY(nvlist_lookup_uint64(l2cache[i], ZPOOL_CONFIG_GUID,
		    &guid) == 0);

		newvdevs[i] = NULL;
		for (j = 0; j < oldnvdevs; j++) {
			vd = oldvdevs[j];
			if (vd != NULL && guid == vd->vdev_guid) {
				/*
				 * Retain previous vdev for add/remove ops.
				 */
				newvdevs[i] = vd;
				oldvdevs[j] = NULL;
				break;
			}
		}

		if (newvdevs[i] == NULL) {
			/*
			 * Create new vdev
			 */
			VERIFY(spa_config_parse(spa, &vd, l2cache[i], NULL, 0,
			    VDEV_ALLOC_L2CACHE) == 0);
			ASSERT(vd != NULL);
			newvdevs[i] = vd;

			/*
			 * Commit this vdev as an l2cache device,
			 * even if it fails to open.
			 */
			spa_l2cache_add(vd);

			vd->vdev_top = vd;
			vd->vdev_aux = sav;

			spa_l2cache_activate(vd);

			if (vdev_open(vd) != 0)
				continue;

			(void) vdev_validate_aux(vd);

			if (!vdev_is_dead(vd))
				l2arc_add_vdev(spa, vd);
		}
	}

	sav->sav_vdevs = newvdevs;
	sav->sav_count = (int)nl2cache;

	/*
	 * Recompute the stashed list of l2cache devices, with status
	 * information this time.
	 */
	VERIFY(nvlist_remove(sav->sav_config, ZPOOL_CONFIG_L2CACHE,
	    DATA_TYPE_NVLIST_ARRAY) == 0);

	if (sav->sav_count > 0)
		l2cache = kmem_alloc(sav->sav_count * sizeof (void *),
		    KM_SLEEP);
	for (i = 0; i < sav->sav_count; i++)
		l2cache[i] = vdev_config_generate(spa,
		    sav->sav_vdevs[i], B_TRUE, VDEV_CONFIG_L2CACHE);
	VERIFY(nvlist_add_nvlist_array(sav->sav_config,
	    ZPOOL_CONFIG_L2CACHE, l2cache, sav->sav_count) == 0);

out:
	/*
	 * Purge vdevs that were dropped
	 */
	for (i = 0; i < oldnvdevs; i++) {
		uint64_t pool;

		vd = oldvdevs[i];
		if (vd != NULL) {
			ASSERT(vd->vdev_isl2cache);

			if (spa_l2cache_exists(vd->vdev_guid, &pool) &&
			    pool != 0ULL && l2arc_vdev_present(vd))
				l2arc_remove_vdev(vd);
			vdev_clear_stats(vd);
			vdev_free(vd);
		}
	}

	if (oldvdevs)
		kmem_free(oldvdevs, oldnvdevs * sizeof (void *));

	for (i = 0; i < sav->sav_count; i++)
		nvlist_free(l2cache[i]);
	if (sav->sav_count)
		kmem_free(l2cache, sav->sav_count * sizeof (void *));
}

static int
load_nvlist(spa_t *spa, uint64_t obj, nvlist_t **value)
{
	dmu_buf_t *db;
	char *packed = NULL;
	size_t nvsize = 0;
	int error;
	*value = NULL;

	error = dmu_bonus_hold(spa->spa_meta_objset, obj, FTAG, &db);
	if (error)
		return (error);

	nvsize = *(uint64_t *)db->db_data;
	dmu_buf_rele(db, FTAG);

	packed = vmem_alloc(nvsize, KM_SLEEP);
	error = dmu_read(spa->spa_meta_objset, obj, 0, nvsize, packed,
	    DMU_READ_PREFETCH);
	if (error == 0)
		error = nvlist_unpack(packed, nvsize, value, 0);
	vmem_free(packed, nvsize);

	return (error);
}

/*
 * Concrete top-level vdevs that are not missing and are not logs. At every
 * spa_sync we write new uberblocks to at least SPA_SYNC_MIN_VDEVS core tvds.
 */
static uint64_t
spa_healthy_core_tvds(spa_t *spa)
{
	vdev_t *rvd = spa->spa_root_vdev;
	uint64_t tvds = 0;

	for (uint64_t i = 0; i < rvd->vdev_children; i++) {
		vdev_t *vd = rvd->vdev_child[i];
		if (vd->vdev_islog)
			continue;
		if (vdev_is_concrete(vd) && !vdev_is_dead(vd))
			tvds++;
	}

	return (tvds);
}

/*
 * Checks to see if the given vdev could not be opened, in which case we post a
 * sysevent to notify the autoreplace code that the device has been removed.
 */
static void
spa_check_removed(vdev_t *vd)
{
	for (uint64_t c = 0; c < vd->vdev_children; c++)
		spa_check_removed(vd->vdev_child[c]);

	if (vd->vdev_ops->vdev_op_leaf && vdev_is_dead(vd) &&
	    vdev_is_concrete(vd)) {
		zfs_post_autoreplace(vd->vdev_spa, vd);
		spa_event_notify(vd->vdev_spa, vd, NULL, ESC_ZFS_VDEV_CHECK);
	}
}

static int
spa_check_for_missing_logs(spa_t *spa)
{
	vdev_t *rvd = spa->spa_root_vdev;

	/*
	 * If we're doing a normal import, then build up any additional
	 * diagnostic information about missing log devices.
	 * We'll pass this up to the user for further processing.
	 */
	if (!(spa->spa_import_flags & ZFS_IMPORT_MISSING_LOG)) {
		nvlist_t **child, *nv;
		uint64_t idx = 0;

		child = kmem_alloc(rvd->vdev_children * sizeof (nvlist_t *),
		    KM_SLEEP);
		VERIFY(nvlist_alloc(&nv, NV_UNIQUE_NAME, KM_SLEEP) == 0);

		for (uint64_t c = 0; c < rvd->vdev_children; c++) {
			vdev_t *tvd = rvd->vdev_child[c];

			/*
			 * We consider a device as missing only if it failed
			 * to open (i.e. offline or faulted is not considered
			 * as missing).
			 */
			if (tvd->vdev_islog &&
			    tvd->vdev_state == VDEV_STATE_CANT_OPEN) {
				child[idx++] = vdev_config_generate(spa, tvd,
				    B_FALSE, VDEV_CONFIG_MISSING);
			}
		}

		if (idx > 0) {
			fnvlist_add_nvlist_array(nv,
			    ZPOOL_CONFIG_CHILDREN, child, idx);
			fnvlist_add_nvlist(spa->spa_load_info,
			    ZPOOL_CONFIG_MISSING_DEVICES, nv);

			for (uint64_t i = 0; i < idx; i++)
				nvlist_free(child[i]);
		}
		nvlist_free(nv);
		kmem_free(child, rvd->vdev_children * sizeof (char **));

		if (idx > 0) {
			spa_load_failed(spa, "some log devices are missing");
			vdev_dbgmsg_print_tree(rvd, 2);
			return (SET_ERROR(ENXIO));
		}
	} else {
		for (uint64_t c = 0; c < rvd->vdev_children; c++) {
			vdev_t *tvd = rvd->vdev_child[c];

			if (tvd->vdev_islog &&
			    tvd->vdev_state == VDEV_STATE_CANT_OPEN) {
				spa_set_log_state(spa, SPA_LOG_CLEAR);
				spa_load_note(spa, "some log devices are "
				    "missing, ZIL is dropped.");
				vdev_dbgmsg_print_tree(rvd, 2);
				break;
			}
		}
	}

	return (0);
}

/*
 * Check for missing log devices
 */
static boolean_t
spa_check_logs(spa_t *spa)
{
	boolean_t rv = B_FALSE;
	dsl_pool_t *dp = spa_get_dsl(spa);

	switch (spa->spa_log_state) {
	default:
		break;
	case SPA_LOG_MISSING:
		/* need to recheck in case slog has been restored */
	case SPA_LOG_UNKNOWN:
		rv = (dmu_objset_find_dp(dp, dp->dp_root_dir_obj,
		    zil_check_log_chain, NULL, DS_FIND_CHILDREN) != 0);
		if (rv)
			spa_set_log_state(spa, SPA_LOG_MISSING);
		break;
	}
	return (rv);
}

static boolean_t
spa_passivate_log(spa_t *spa)
{
	vdev_t *rvd = spa->spa_root_vdev;
	boolean_t slog_found = B_FALSE;

	ASSERT(spa_config_held(spa, SCL_ALLOC, RW_WRITER));

	if (!spa_has_slogs(spa))
		return (B_FALSE);

	for (int c = 0; c < rvd->vdev_children; c++) {
		vdev_t *tvd = rvd->vdev_child[c];
		metaslab_group_t *mg = tvd->vdev_mg;

		if (tvd->vdev_islog) {
			metaslab_group_passivate(mg);
			slog_found = B_TRUE;
		}
	}

	return (slog_found);
}

static void
spa_activate_log(spa_t *spa)
{
	vdev_t *rvd = spa->spa_root_vdev;

	ASSERT(spa_config_held(spa, SCL_ALLOC, RW_WRITER));

	for (int c = 0; c < rvd->vdev_children; c++) {
		vdev_t *tvd = rvd->vdev_child[c];
		metaslab_group_t *mg = tvd->vdev_mg;

		if (tvd->vdev_islog)
			metaslab_group_activate(mg);
	}
}

int
spa_reset_logs(spa_t *spa)
{
	int error;

	error = dmu_objset_find(spa_name(spa), zil_reset,
	    NULL, DS_FIND_CHILDREN);
	if (error == 0) {
		/*
		 * We successfully offlined the log device, sync out the
		 * current txg so that the "stubby" block can be removed
		 * by zil_sync().
		 */
		txg_wait_synced(spa->spa_dsl_pool, 0);
	}
	return (error);
}

static void
spa_aux_check_removed(spa_aux_vdev_t *sav)
{
	for (int i = 0; i < sav->sav_count; i++)
		spa_check_removed(sav->sav_vdevs[i]);
}

void
spa_claim_notify(zio_t *zio)
{
	spa_t *spa = zio->io_spa;

	if (zio->io_error)
		return;

	mutex_enter(&spa->spa_props_lock);	/* any mutex will do */
	if (spa->spa_claim_max_txg < zio->io_bp->blk_birth)
		spa->spa_claim_max_txg = zio->io_bp->blk_birth;
	mutex_exit(&spa->spa_props_lock);
}

typedef struct spa_load_error {
	uint64_t	sle_meta_count;
	uint64_t	sle_data_count;
} spa_load_error_t;

static void
spa_load_verify_done(zio_t *zio)
{
	blkptr_t *bp = zio->io_bp;
	spa_load_error_t *sle = zio->io_private;
	dmu_object_type_t type = BP_GET_TYPE(bp);
	int error = zio->io_error;
	spa_t *spa = zio->io_spa;

	abd_free(zio->io_abd);
	if (error) {
		if ((BP_GET_LEVEL(bp) != 0 || DMU_OT_IS_METADATA(type)) &&
		    type != DMU_OT_INTENT_LOG)
			atomic_inc_64(&sle->sle_meta_count);
		else
			atomic_inc_64(&sle->sle_data_count);
	}

	mutex_enter(&spa->spa_scrub_lock);
	spa->spa_load_verify_ios--;
	cv_broadcast(&spa->spa_scrub_io_cv);
	mutex_exit(&spa->spa_scrub_lock);
}

/*
 * Maximum number of concurrent scrub i/os to create while verifying
 * a pool while importing it.
 */
int spa_load_verify_maxinflight = 10000;
int spa_load_verify_metadata = B_TRUE;
int spa_load_verify_data = B_TRUE;

/*ARGSUSED*/
static int
spa_load_verify_cb(spa_t *spa, zilog_t *zilog, const blkptr_t *bp,
    const zbookmark_phys_t *zb, const dnode_phys_t *dnp, void *arg)
{
	if (zb->zb_level == ZB_DNODE_LEVEL || BP_IS_HOLE(bp) ||
	    BP_IS_EMBEDDED(bp) || BP_IS_REDACTED(bp))
		return (0);
	/*
	 * Note: normally this routine will not be called if
	 * spa_load_verify_metadata is not set.  However, it may be useful
	 * to manually set the flag after the traversal has begun.
	 */
	if (!spa_load_verify_metadata)
		return (0);
	if (!BP_IS_METADATA(bp) && !spa_load_verify_data)
		return (0);

	zio_t *rio = arg;
	size_t size = BP_GET_PSIZE(bp);

	mutex_enter(&spa->spa_scrub_lock);
	while (spa->spa_load_verify_ios >= spa_load_verify_maxinflight)
		cv_wait(&spa->spa_scrub_io_cv, &spa->spa_scrub_lock);
	spa->spa_load_verify_ios++;
	mutex_exit(&spa->spa_scrub_lock);

	zio_nowait(zio_read(rio, spa, bp, abd_alloc_for_io(size, B_FALSE), size,
	    spa_load_verify_done, rio->io_private, ZIO_PRIORITY_SCRUB,
	    ZIO_FLAG_SPECULATIVE | ZIO_FLAG_CANFAIL |
	    ZIO_FLAG_SCRUB | ZIO_FLAG_RAW, zb));
	return (0);
}

/* ARGSUSED */
int
verify_dataset_name_len(dsl_pool_t *dp, dsl_dataset_t *ds, void *arg)
{
	if (dsl_dataset_namelen(ds) >= ZFS_MAX_DATASET_NAME_LEN)
		return (SET_ERROR(ENAMETOOLONG));

	return (0);
}

static int
spa_load_verify(spa_t *spa)
{
	zio_t *rio;
	spa_load_error_t sle = { 0 };
	zpool_load_policy_t policy;
	boolean_t verify_ok = B_FALSE;
	int error = 0;

	zpool_get_load_policy(spa->spa_config, &policy);

	if (policy.zlp_rewind & ZPOOL_NEVER_REWIND)
		return (0);

	dsl_pool_config_enter(spa->spa_dsl_pool, FTAG);
	error = dmu_objset_find_dp(spa->spa_dsl_pool,
	    spa->spa_dsl_pool->dp_root_dir_obj, verify_dataset_name_len, NULL,
	    DS_FIND_CHILDREN);
	dsl_pool_config_exit(spa->spa_dsl_pool, FTAG);
	if (error != 0)
		return (error);

	rio = zio_root(spa, NULL, &sle,
	    ZIO_FLAG_CANFAIL | ZIO_FLAG_SPECULATIVE);

	if (spa_load_verify_metadata) {
		if (spa->spa_extreme_rewind) {
			spa_load_note(spa, "performing a complete scan of the "
			    "pool since extreme rewind is on. This may take "
			    "a very long time.\n  (spa_load_verify_data=%u, "
			    "spa_load_verify_metadata=%u)",
			    spa_load_verify_data, spa_load_verify_metadata);
		}
		error = traverse_pool(spa, spa->spa_verify_min_txg,
		    TRAVERSE_PRE | TRAVERSE_PREFETCH_METADATA |
		    TRAVERSE_NO_DECRYPT, spa_load_verify_cb, rio);
	}

	(void) zio_wait(rio);

	spa->spa_load_meta_errors = sle.sle_meta_count;
	spa->spa_load_data_errors = sle.sle_data_count;

	if (sle.sle_meta_count != 0 || sle.sle_data_count != 0) {
		spa_load_note(spa, "spa_load_verify found %llu metadata errors "
		    "and %llu data errors", (u_longlong_t)sle.sle_meta_count,
		    (u_longlong_t)sle.sle_data_count);
	}

	if (spa_load_verify_dryrun ||
	    (!error && sle.sle_meta_count <= policy.zlp_maxmeta &&
	    sle.sle_data_count <= policy.zlp_maxdata)) {
		int64_t loss = 0;

		verify_ok = B_TRUE;
		spa->spa_load_txg = spa->spa_uberblock.ub_txg;
		spa->spa_load_txg_ts = spa->spa_uberblock.ub_timestamp;

		loss = spa->spa_last_ubsync_txg_ts - spa->spa_load_txg_ts;
		VERIFY(nvlist_add_uint64(spa->spa_load_info,
		    ZPOOL_CONFIG_LOAD_TIME, spa->spa_load_txg_ts) == 0);
		VERIFY(nvlist_add_int64(spa->spa_load_info,
		    ZPOOL_CONFIG_REWIND_TIME, loss) == 0);
		VERIFY(nvlist_add_uint64(spa->spa_load_info,
		    ZPOOL_CONFIG_LOAD_DATA_ERRORS, sle.sle_data_count) == 0);
	} else {
		spa->spa_load_max_txg = spa->spa_uberblock.ub_txg;
	}

	if (spa_load_verify_dryrun)
		return (0);

	if (error) {
		if (error != ENXIO && error != EIO)
			error = SET_ERROR(EIO);
		return (error);
	}

	return (verify_ok ? 0 : EIO);
}

/*
 * Find a value in the pool props object.
 */
static void
spa_prop_find(spa_t *spa, zpool_prop_t prop, uint64_t *val)
{
	(void) zap_lookup(spa->spa_meta_objset, spa->spa_pool_props_object,
	    zpool_prop_to_name(prop), sizeof (uint64_t), 1, val);
}

/*
 * Find a value in the pool directory object.
 */
static int
spa_dir_prop(spa_t *spa, const char *name, uint64_t *val, boolean_t log_enoent)
{
	int error = zap_lookup(spa->spa_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
	    name, sizeof (uint64_t), 1, val);

	if (error != 0 && (error != ENOENT || log_enoent)) {
		spa_load_failed(spa, "couldn't get '%s' value in MOS directory "
		    "[error=%d]", name, error);
	}

	return (error);
}

static int
spa_vdev_err(vdev_t *vdev, vdev_aux_t aux, int err)
{
	vdev_set_state(vdev, B_TRUE, VDEV_STATE_CANT_OPEN, aux);
	return (SET_ERROR(err));
}

static void
spa_spawn_aux_threads(spa_t *spa)
{
	ASSERT(spa_writeable(spa));

	ASSERT(MUTEX_HELD(&spa_namespace_lock));

	spa_start_indirect_condensing_thread(spa);

	ASSERT3P(spa->spa_checkpoint_discard_zthr, ==, NULL);
	spa->spa_checkpoint_discard_zthr =
	    zthr_create(spa_checkpoint_discard_thread_check,
	    spa_checkpoint_discard_thread, spa);
}

/*
 * Fix up config after a partly-completed split.  This is done with the
 * ZPOOL_CONFIG_SPLIT nvlist.  Both the splitting pool and the split-off
 * pool have that entry in their config, but only the splitting one contains
 * a list of all the guids of the vdevs that are being split off.
 *
 * This function determines what to do with that list: either rejoin
 * all the disks to the pool, or complete the splitting process.  To attempt
 * the rejoin, each disk that is offlined is marked online again, and
 * we do a reopen() call.  If the vdev label for every disk that was
 * marked online indicates it was successfully split off (VDEV_AUX_SPLIT_POOL)
 * then we call vdev_split() on each disk, and complete the split.
 *
 * Otherwise we leave the config alone, with all the vdevs in place in
 * the original pool.
 */
static void
spa_try_repair(spa_t *spa, nvlist_t *config)
{
	uint_t extracted;
	uint64_t *glist;
	uint_t i, gcount;
	nvlist_t *nvl;
	vdev_t **vd;
	boolean_t attempt_reopen;

	if (nvlist_lookup_nvlist(config, ZPOOL_CONFIG_SPLIT, &nvl) != 0)
		return;

	/* check that the config is complete */
	if (nvlist_lookup_uint64_array(nvl, ZPOOL_CONFIG_SPLIT_LIST,
	    &glist, &gcount) != 0)
		return;

	vd = kmem_zalloc(gcount * sizeof (vdev_t *), KM_SLEEP);

	/* attempt to online all the vdevs & validate */
	attempt_reopen = B_TRUE;
	for (i = 0; i < gcount; i++) {
		if (glist[i] == 0)	/* vdev is hole */
			continue;

		vd[i] = spa_lookup_by_guid(spa, glist[i], B_FALSE);
		if (vd[i] == NULL) {
			/*
			 * Don't bother attempting to reopen the disks;
			 * just do the split.
			 */
			attempt_reopen = B_FALSE;
		} else {
			/* attempt to re-online it */
			vd[i]->vdev_offline = B_FALSE;
		}
	}

	if (attempt_reopen) {
		vdev_reopen(spa->spa_root_vdev);

		/* check each device to see what state it's in */
		for (extracted = 0, i = 0; i < gcount; i++) {
			if (vd[i] != NULL &&
			    vd[i]->vdev_stat.vs_aux != VDEV_AUX_SPLIT_POOL)
				break;
			++extracted;
		}
	}

	/*
	 * If every disk has been moved to the new pool, or if we never
	 * even attempted to look at them, then we split them off for
	 * good.
	 */
	if (!attempt_reopen || gcount == extracted) {
		for (i = 0; i < gcount; i++)
			if (vd[i] != NULL)
				vdev_split(vd[i]);
		vdev_reopen(spa->spa_root_vdev);
	}

	kmem_free(vd, gcount * sizeof (vdev_t *));
}

static int
spa_load(spa_t *spa, spa_load_state_t state, spa_import_type_t type)
{
	char *ereport = FM_EREPORT_ZFS_POOL;
	int error;

	spa->spa_load_state = state;
	(void) spa_import_progress_set_state(spa_guid(spa),
	    spa_load_state(spa));

	gethrestime(&spa->spa_loaded_ts);
	error = spa_load_impl(spa, type, &ereport);

	/*
	 * Don't count references from objsets that are already closed
	 * and are making their way through the eviction process.
	 */
	spa_evicting_os_wait(spa);
	spa->spa_minref = zfs_refcount_count(&spa->spa_refcount);
	if (error) {
		if (error != EEXIST) {
			spa->spa_loaded_ts.tv_sec = 0;
			spa->spa_loaded_ts.tv_nsec = 0;
		}
		if (error != EBADF) {
			zfs_ereport_post(ereport, spa, NULL, NULL, NULL, 0, 0);
		}
	}
	spa->spa_load_state = error ? SPA_LOAD_ERROR : SPA_LOAD_NONE;
	spa->spa_ena = 0;

	(void) spa_import_progress_set_state(spa_guid(spa),
	    spa_load_state(spa));

	return (error);
}

#ifdef ZFS_DEBUG
/*
 * Count the number of per-vdev ZAPs associated with all of the vdevs in the
 * vdev tree rooted in the given vd, and ensure that each ZAP is present in the
 * spa's per-vdev ZAP list.
 */
static uint64_t
vdev_count_verify_zaps(vdev_t *vd)
{
	spa_t *spa = vd->vdev_spa;
	uint64_t total = 0;

	if (vd->vdev_top_zap != 0) {
		total++;
		ASSERT0(zap_lookup_int(spa->spa_meta_objset,
		    spa->spa_all_vdev_zaps, vd->vdev_top_zap));
	}
	if (vd->vdev_leaf_zap != 0) {
		total++;
		ASSERT0(zap_lookup_int(spa->spa_meta_objset,
		    spa->spa_all_vdev_zaps, vd->vdev_leaf_zap));
	}

	for (uint64_t i = 0; i < vd->vdev_children; i++) {
		total += vdev_count_verify_zaps(vd->vdev_child[i]);
	}

	return (total);
}
#endif

/*
 * Determine whether the activity check is required.
 */
static boolean_t
spa_activity_check_required(spa_t *spa, uberblock_t *ub, nvlist_t *label,
    nvlist_t *config)
{
	uint64_t state = 0;
	uint64_t hostid = 0;
	uint64_t tryconfig_txg = 0;
	uint64_t tryconfig_timestamp = 0;
	uint16_t tryconfig_mmp_seq = 0;
	nvlist_t *nvinfo;

	if (nvlist_exists(config, ZPOOL_CONFIG_LOAD_INFO)) {
		nvinfo = fnvlist_lookup_nvlist(config, ZPOOL_CONFIG_LOAD_INFO);
		(void) nvlist_lookup_uint64(nvinfo, ZPOOL_CONFIG_MMP_TXG,
		    &tryconfig_txg);
		(void) nvlist_lookup_uint64(config, ZPOOL_CONFIG_TIMESTAMP,
		    &tryconfig_timestamp);
		(void) nvlist_lookup_uint16(nvinfo, ZPOOL_CONFIG_MMP_SEQ,
		    &tryconfig_mmp_seq);
	}

	(void) nvlist_lookup_uint64(config, ZPOOL_CONFIG_POOL_STATE, &state);

	/*
	 * Disable the MMP activity check - This is used by zdb which
	 * is intended to be used on potentially active pools.
	 */
	if (spa->spa_import_flags & ZFS_IMPORT_SKIP_MMP)
		return (B_FALSE);

	/*
	 * Skip the activity check when the MMP feature is disabled.
	 */
	if (ub->ub_mmp_magic == MMP_MAGIC && ub->ub_mmp_delay == 0)
		return (B_FALSE);

	/*
	 * If the tryconfig_ values are nonzero, they are the results of an
	 * earlier tryimport.  If they all match the uberblock we just found,
	 * then the pool has not changed and we return false so we do not test
	 * a second time.
	 */
	if (tryconfig_txg && tryconfig_txg == ub->ub_txg &&
	    tryconfig_timestamp && tryconfig_timestamp == ub->ub_timestamp &&
	    tryconfig_mmp_seq && tryconfig_mmp_seq ==
	    (MMP_SEQ_VALID(ub) ? MMP_SEQ(ub) : 0))
		return (B_FALSE);

	/*
	 * Allow the activity check to be skipped when importing the pool
	 * on the same host which last imported it.  Since the hostid from
	 * configuration may be stale use the one read from the label.
	 */
	if (nvlist_exists(label, ZPOOL_CONFIG_HOSTID))
		hostid = fnvlist_lookup_uint64(label, ZPOOL_CONFIG_HOSTID);

	if (hostid == spa_get_hostid())
		return (B_FALSE);

	/*
	 * Skip the activity test when the pool was cleanly exported.
	 */
	if (state != POOL_STATE_ACTIVE)
		return (B_FALSE);

	return (B_TRUE);
}

/*
 * Nanoseconds the activity check must watch for changes on-disk.
 */
static uint64_t
spa_activity_check_duration(spa_t *spa, uberblock_t *ub)
{
	uint64_t import_intervals = MAX(zfs_multihost_import_intervals, 1);
	uint64_t multihost_interval = MSEC2NSEC(
	    MMP_INTERVAL_OK(zfs_multihost_interval));
	uint64_t import_delay = MAX(NANOSEC, import_intervals *
	    multihost_interval);

	/*
	 * Local tunables determine a minimum duration except for the case
	 * where we know when the remote host will suspend the pool if MMP
	 * writes do not land.
	 *
	 * See Big Theory comment at the top of mmp.c for the reasoning behind
	 * these cases and times.
	 */

	ASSERT(MMP_IMPORT_SAFETY_FACTOR >= 100);

	if (MMP_INTERVAL_VALID(ub) && MMP_FAIL_INT_VALID(ub) &&
	    MMP_FAIL_INT(ub) > 0) {

		/* MMP on remote host will suspend pool after failed writes */
		import_delay = MMP_FAIL_INT(ub) * MSEC2NSEC(MMP_INTERVAL(ub)) *
		    MMP_IMPORT_SAFETY_FACTOR / 100;

		zfs_dbgmsg("fail_intvals>0 import_delay=%llu ub_mmp "
		    "mmp_fails=%llu ub_mmp mmp_interval=%llu "
		    "import_intervals=%u", import_delay, MMP_FAIL_INT(ub),
		    MMP_INTERVAL(ub), import_intervals);

	} else if (MMP_INTERVAL_VALID(ub) && MMP_FAIL_INT_VALID(ub) &&
	    MMP_FAIL_INT(ub) == 0) {

		/* MMP on remote host will never suspend pool */
		import_delay = MAX(import_delay, (MSEC2NSEC(MMP_INTERVAL(ub)) +
		    ub->ub_mmp_delay) * import_intervals);

		zfs_dbgmsg("fail_intvals=0 import_delay=%llu ub_mmp "
		    "mmp_interval=%llu ub_mmp_delay=%llu "
		    "import_intervals=%u", import_delay, MMP_INTERVAL(ub),
		    ub->ub_mmp_delay, import_intervals);

	} else if (MMP_VALID(ub)) {
		/*
		 * zfs-0.7 compatability case
		 */

		import_delay = MAX(import_delay, (multihost_interval +
		    ub->ub_mmp_delay) * import_intervals);

		zfs_dbgmsg("import_delay=%llu ub_mmp_delay=%llu "
		    "import_intervals=%u leaves=%u", import_delay,
		    ub->ub_mmp_delay, import_intervals,
		    vdev_count_leaves(spa));
	} else {
		/* Using local tunings is the only reasonable option */
		zfs_dbgmsg("pool last imported on non-MMP aware "
		    "host using import_delay=%llu multihost_interval=%llu "
		    "import_intervals=%u", import_delay, multihost_interval,
		    import_intervals);
	}

	return (import_delay);
}

/*
 * Perform the import activity check.  If the user canceled the import or
 * we detected activity then fail.
 */
static int
spa_activity_check(spa_t *spa, uberblock_t *ub, nvlist_t *config)
{
	uint64_t txg = ub->ub_txg;
	uint64_t timestamp = ub->ub_timestamp;
	uint64_t mmp_config = ub->ub_mmp_config;
	uint16_t mmp_seq = MMP_SEQ_VALID(ub) ? MMP_SEQ(ub) : 0;
	uint64_t import_delay;
	hrtime_t import_expire;
	nvlist_t *mmp_label = NULL;
	vdev_t *rvd = spa->spa_root_vdev;
	kcondvar_t cv;
	kmutex_t mtx;
	int error = 0;

	cv_init(&cv, NULL, CV_DEFAULT, NULL);
	mutex_init(&mtx, NULL, MUTEX_DEFAULT, NULL);
	mutex_enter(&mtx);

	/*
	 * If ZPOOL_CONFIG_MMP_TXG is present an activity check was performed
	 * during the earlier tryimport.  If the txg recorded there is 0 then
	 * the pool is known to be active on another host.
	 *
	 * Otherwise, the pool might be in use on another host.  Check for
	 * changes in the uberblocks on disk if necessary.
	 */
	if (nvlist_exists(config, ZPOOL_CONFIG_LOAD_INFO)) {
		nvlist_t *nvinfo = fnvlist_lookup_nvlist(config,
		    ZPOOL_CONFIG_LOAD_INFO);

		if (nvlist_exists(nvinfo, ZPOOL_CONFIG_MMP_TXG) &&
		    fnvlist_lookup_uint64(nvinfo, ZPOOL_CONFIG_MMP_TXG) == 0) {
			vdev_uberblock_load(rvd, ub, &mmp_label);
			error = SET_ERROR(EREMOTEIO);
			goto out;
		}
	}

	import_delay = spa_activity_check_duration(spa, ub);

	/* Add a small random factor in case of simultaneous imports (0-25%) */
	import_delay += import_delay * spa_get_random(250) / 1000;

	import_expire = gethrtime() + import_delay;

	while (gethrtime() < import_expire) {
		(void) spa_import_progress_set_mmp_check(spa_guid(spa),
		    NSEC2SEC(import_expire - gethrtime()));

		vdev_uberblock_load(rvd, ub, &mmp_label);

		if (txg != ub->ub_txg || timestamp != ub->ub_timestamp ||
		    mmp_seq != (MMP_SEQ_VALID(ub) ? MMP_SEQ(ub) : 0)) {
			zfs_dbgmsg("multihost activity detected "
			    "txg %llu ub_txg  %llu "
			    "timestamp %llu ub_timestamp  %llu "
			    "mmp_config %#llx ub_mmp_config %#llx",
			    txg, ub->ub_txg, timestamp, ub->ub_timestamp,
			    mmp_config, ub->ub_mmp_config);

			error = SET_ERROR(EREMOTEIO);
			break;
		}

		if (mmp_label) {
			nvlist_free(mmp_label);
			mmp_label = NULL;
		}

		error = cv_timedwait_sig(&cv, &mtx, ddi_get_lbolt() + hz);
		if (error != -1) {
			error = SET_ERROR(EINTR);
			break;
		}
		error = 0;
	}

out:
	mutex_exit(&mtx);
	mutex_destroy(&mtx);
	cv_destroy(&cv);

	/*
	 * If the pool is determined to be active store the status in the
	 * spa->spa_load_info nvlist.  If the remote hostname or hostid are
	 * available from configuration read from disk store them as well.
	 * This allows 'zpool import' to generate a more useful message.
	 *
	 * ZPOOL_CONFIG_MMP_STATE    - observed pool status (mandatory)
	 * ZPOOL_CONFIG_MMP_HOSTNAME - hostname from the active pool
	 * ZPOOL_CONFIG_MMP_HOSTID   - hostid from the active pool
	 */
	if (error == EREMOTEIO) {
		char *hostname = "<unknown>";
		uint64_t hostid = 0;

		if (mmp_label) {
			if (nvlist_exists(mmp_label, ZPOOL_CONFIG_HOSTNAME)) {
				hostname = fnvlist_lookup_string(mmp_label,
				    ZPOOL_CONFIG_HOSTNAME);
				fnvlist_add_string(spa->spa_load_info,
				    ZPOOL_CONFIG_MMP_HOSTNAME, hostname);
			}

			if (nvlist_exists(mmp_label, ZPOOL_CONFIG_HOSTID)) {
				hostid = fnvlist_lookup_uint64(mmp_label,
				    ZPOOL_CONFIG_HOSTID);
				fnvlist_add_uint64(spa->spa_load_info,
				    ZPOOL_CONFIG_MMP_HOSTID, hostid);
			}
		}

		fnvlist_add_uint64(spa->spa_load_info,
		    ZPOOL_CONFIG_MMP_STATE, MMP_STATE_ACTIVE);
		fnvlist_add_uint64(spa->spa_load_info,
		    ZPOOL_CONFIG_MMP_TXG, 0);

		error = spa_vdev_err(rvd, VDEV_AUX_ACTIVE, EREMOTEIO);
	}

	if (mmp_label)
		nvlist_free(mmp_label);

	return (error);
}

static int
spa_verify_host(spa_t *spa, nvlist_t *mos_config)
{
	uint64_t hostid;
	char *hostname;
	uint64_t myhostid = 0;

	if (!spa_is_root(spa) && nvlist_lookup_uint64(mos_config,
	    ZPOOL_CONFIG_HOSTID, &hostid) == 0) {
		hostname = fnvlist_lookup_string(mos_config,
		    ZPOOL_CONFIG_HOSTNAME);

		myhostid = zone_get_hostid(NULL);

		if (hostid != 0 && myhostid != 0 && hostid != myhostid) {
			cmn_err(CE_WARN, "pool '%s' could not be "
			    "loaded as it was last accessed by "
			    "another system (host: %s hostid: 0x%llx). "
			    "See: http://illumos.org/msg/ZFS-8000-EY",
			    spa_name(spa), hostname, (u_longlong_t)hostid);
			spa_load_failed(spa, "hostid verification failed: pool "
			    "last accessed by host: %s (hostid: 0x%llx)",
			    hostname, (u_longlong_t)hostid);
			return (SET_ERROR(EBADF));
		}
	}

	return (0);
}

static int
spa_ld_parse_config(spa_t *spa, spa_import_type_t type)
{
	int error = 0;
	nvlist_t *nvtree, *nvl, *config = spa->spa_config;
	int parse;
	vdev_t *rvd;
	uint64_t pool_guid;
	char *comment;

	/*
	 * Versioning wasn't explicitly added to the label until later, so if
	 * it's not present treat it as the initial version.
	 */
	if (nvlist_lookup_uint64(config, ZPOOL_CONFIG_VERSION,
	    &spa->spa_ubsync.ub_version) != 0)
		spa->spa_ubsync.ub_version = SPA_VERSION_INITIAL;

	if (nvlist_lookup_uint64(config, ZPOOL_CONFIG_POOL_GUID, &pool_guid)) {
		spa_load_failed(spa, "invalid config provided: '%s' missing",
		    ZPOOL_CONFIG_POOL_GUID);
		return (SET_ERROR(EINVAL));
	}

	/*
	 * If we are doing an import, ensure that the pool is not already
	 * imported by checking if its pool guid already exists in the
	 * spa namespace.
	 *
	 * The only case that we allow an already imported pool to be
	 * imported again, is when the pool is checkpointed and we want to
	 * look at its checkpointed state from userland tools like zdb.
	 */
#ifdef _KERNEL
	if ((spa->spa_load_state == SPA_LOAD_IMPORT ||
	    spa->spa_load_state == SPA_LOAD_TRYIMPORT) &&
	    spa_guid_exists(pool_guid, 0)) {
#else
	if ((spa->spa_load_state == SPA_LOAD_IMPORT ||
	    spa->spa_load_state == SPA_LOAD_TRYIMPORT) &&
	    spa_guid_exists(pool_guid, 0) &&
	    !spa_importing_readonly_checkpoint(spa)) {
#endif
		spa_load_failed(spa, "a pool with guid %llu is already open",
		    (u_longlong_t)pool_guid);
		return (SET_ERROR(EEXIST));
	}

	spa->spa_config_guid = pool_guid;

	nvlist_free(spa->spa_load_info);
	spa->spa_load_info = fnvlist_alloc();

	ASSERT(spa->spa_comment == NULL);
	if (nvlist_lookup_string(config, ZPOOL_CONFIG_COMMENT, &comment) == 0)
		spa->spa_comment = spa_strdup(comment);

	(void) nvlist_lookup_uint64(config, ZPOOL_CONFIG_POOL_TXG,
	    &spa->spa_config_txg);

	if (nvlist_lookup_nvlist(config, ZPOOL_CONFIG_SPLIT, &nvl) == 0)
		spa->spa_config_splitting = fnvlist_dup(nvl);

	if (nvlist_lookup_nvlist(config, ZPOOL_CONFIG_VDEV_TREE, &nvtree)) {
		spa_load_failed(spa, "invalid config provided: '%s' missing",
		    ZPOOL_CONFIG_VDEV_TREE);
		return (SET_ERROR(EINVAL));
	}

	/*
	 * Create "The Godfather" zio to hold all async IOs
	 */
	spa->spa_async_zio_root = kmem_alloc(max_ncpus * sizeof (void *),
	    KM_SLEEP);
	for (int i = 0; i < max_ncpus; i++) {
		spa->spa_async_zio_root[i] = zio_root(spa, NULL, NULL,
		    ZIO_FLAG_CANFAIL | ZIO_FLAG_SPECULATIVE |
		    ZIO_FLAG_GODFATHER);
	}

	/*
	 * Parse the configuration into a vdev tree.  We explicitly set the
	 * value that will be returned by spa_version() since parsing the
	 * configuration requires knowing the version number.
	 */
	spa_config_enter(spa, SCL_ALL, FTAG, RW_WRITER);
	parse = (type == SPA_IMPORT_EXISTING ?
	    VDEV_ALLOC_LOAD : VDEV_ALLOC_SPLIT);
	error = spa_config_parse(spa, &rvd, nvtree, NULL, 0, parse);
	spa_config_exit(spa, SCL_ALL, FTAG);

	if (error != 0) {
		spa_load_failed(spa, "unable to parse config [error=%d]",
		    error);
		return (error);
	}

	ASSERT(spa->spa_root_vdev == rvd);
	ASSERT3U(spa->spa_min_ashift, >=, SPA_MINBLOCKSHIFT);
	ASSERT3U(spa->spa_max_ashift, <=, SPA_MAXBLOCKSHIFT);

	if (type != SPA_IMPORT_ASSEMBLE) {
		ASSERT(spa_guid(spa) == pool_guid);
	}

	return (0);
}

/*
 * Recursively open all vdevs in the vdev tree. This function is called twice:
 * first with the untrusted config, then with the trusted config.
 */
static int
spa_ld_open_vdevs(spa_t *spa)
{
	int error = 0;

	/*
	 * spa_missing_tvds_allowed defines how many top-level vdevs can be
	 * missing/unopenable for the root vdev to be still considered openable.
	 */
	if (spa->spa_trust_config) {
		spa->spa_missing_tvds_allowed = zfs_max_missing_tvds;
	} else if (spa->spa_config_source == SPA_CONFIG_SRC_CACHEFILE) {
		spa->spa_missing_tvds_allowed = zfs_max_missing_tvds_cachefile;
	} else if (spa->spa_config_source == SPA_CONFIG_SRC_SCAN) {
		spa->spa_missing_tvds_allowed = zfs_max_missing_tvds_scan;
	} else {
		spa->spa_missing_tvds_allowed = 0;
	}

	spa->spa_missing_tvds_allowed =
	    MAX(zfs_max_missing_tvds, spa->spa_missing_tvds_allowed);

	spa_config_enter(spa, SCL_ALL, FTAG, RW_WRITER);
	error = vdev_open(spa->spa_root_vdev);
	spa_config_exit(spa, SCL_ALL, FTAG);

	if (spa->spa_missing_tvds != 0) {
		spa_load_note(spa, "vdev tree has %lld missing top-level "
		    "vdevs.", (u_longlong_t)spa->spa_missing_tvds);
		if (spa->spa_trust_config && (spa->spa_mode & FWRITE)) {
			/*
			 * Although theoretically we could allow users to open
			 * incomplete pools in RW mode, we'd need to add a lot
			 * of extra logic (e.g. adjust pool space to account
			 * for missing vdevs).
			 * This limitation also prevents users from accidentally
			 * opening the pool in RW mode during data recovery and
			 * damaging it further.
			 */
			spa_load_note(spa, "pools with missing top-level "
			    "vdevs can only be opened in read-only mode.");
			error = SET_ERROR(ENXIO);
		} else {
			spa_load_note(spa, "current settings allow for maximum "
			    "%lld missing top-level vdevs at this stage.",
			    (u_longlong_t)spa->spa_missing_tvds_allowed);
		}
	}
	if (error != 0) {
		spa_load_failed(spa, "unable to open vdev tree [error=%d]",
		    error);
	}
	if (spa->spa_missing_tvds != 0 || error != 0)
		vdev_dbgmsg_print_tree(spa->spa_root_vdev, 2);

	return (error);
}

/*
 * We need to validate the vdev labels against the configuration that
 * we have in hand. This function is called twice: first with an untrusted
 * config, then with a trusted config. The validation is more strict when the
 * config is trusted.
 */
static int
spa_ld_validate_vdevs(spa_t *spa)
{
	int error = 0;
	vdev_t *rvd = spa->spa_root_vdev;

	spa_config_enter(spa, SCL_ALL, FTAG, RW_WRITER);
	error = vdev_validate(rvd);
	spa_config_exit(spa, SCL_ALL, FTAG);

	if (error != 0) {
		spa_load_failed(spa, "vdev_validate failed [error=%d]", error);
		return (error);
	}

	if (rvd->vdev_state <= VDEV_STATE_CANT_OPEN) {
		spa_load_failed(spa, "cannot open vdev tree after invalidating "
		    "some vdevs");
		vdev_dbgmsg_print_tree(rvd, 2);
		return (SET_ERROR(ENXIO));
	}

	return (0);
}

static void
spa_ld_select_uberblock_done(spa_t *spa, uberblock_t *ub)
{
	spa->spa_state = POOL_STATE_ACTIVE;
	spa->spa_ubsync = spa->spa_uberblock;
	spa->spa_verify_min_txg = spa->spa_extreme_rewind ?
	    TXG_INITIAL - 1 : spa_last_synced_txg(spa) - TXG_DEFER_SIZE - 1;
	spa->spa_first_txg = spa->spa_last_ubsync_txg ?
	    spa->spa_last_ubsync_txg : spa_last_synced_txg(spa) + 1;
	spa->spa_claim_max_txg = spa->spa_first_txg;
	spa->spa_prev_software_version = ub->ub_software_version;
}

static int
spa_ld_select_uberblock(spa_t *spa, spa_import_type_t type)
{
	vdev_t *rvd = spa->spa_root_vdev;
	nvlist_t *label;
	uberblock_t *ub = &spa->spa_uberblock;
	boolean_t activity_check = B_FALSE;

	/*
	 * If we are opening the checkpointed state of the pool by
	 * rewinding to it, at this point we will have written the
	 * checkpointed uberblock to the vdev labels, so searching
	 * the labels will find the right uberblock.  However, if
	 * we are opening the checkpointed state read-only, we have
	 * not modified the labels. Therefore, we must ignore the
	 * labels and continue using the spa_uberblock that was set
	 * by spa_ld_checkpoint_rewind.
	 *
	 * Note that it would be fine to ignore the labels when
	 * rewinding (opening writeable) as well. However, if we
	 * crash just after writing the labels, we will end up
	 * searching the labels. Doing so in the common case means
	 * that this code path gets exercised normally, rather than
	 * just in the edge case.
	 */
	if (ub->ub_checkpoint_txg != 0 &&
	    spa_importing_readonly_checkpoint(spa)) {
		spa_ld_select_uberblock_done(spa, ub);
		return (0);
	}

	/*
	 * Find the best uberblock.
	 */
	vdev_uberblock_load(rvd, ub, &label);

	/*
	 * If we weren't able to find a single valid uberblock, return failure.
	 */
	if (ub->ub_txg == 0) {
		nvlist_free(label);
		spa_load_failed(spa, "no valid uberblock found");
		return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, ENXIO));
	}

	if (spa->spa_load_max_txg != UINT64_MAX) {
		(void) spa_import_progress_set_max_txg(spa_guid(spa),
		    (u_longlong_t)spa->spa_load_max_txg);
	}
	spa_load_note(spa, "using uberblock with txg=%llu",
	    (u_longlong_t)ub->ub_txg);


	/*
	 * For pools which have the multihost property on determine if the
	 * pool is truly inactive and can be safely imported.  Prevent
	 * hosts which don't have a hostid set from importing the pool.
	 */
	activity_check = spa_activity_check_required(spa, ub, label,
	    spa->spa_config);
	if (activity_check) {
		if (ub->ub_mmp_magic == MMP_MAGIC && ub->ub_mmp_delay &&
		    spa_get_hostid() == 0) {
			nvlist_free(label);
			fnvlist_add_uint64(spa->spa_load_info,
			    ZPOOL_CONFIG_MMP_STATE, MMP_STATE_NO_HOSTID);
			return (spa_vdev_err(rvd, VDEV_AUX_ACTIVE, EREMOTEIO));
		}

		int error = spa_activity_check(spa, ub, spa->spa_config);
		if (error) {
			nvlist_free(label);
			return (error);
		}

		fnvlist_add_uint64(spa->spa_load_info,
		    ZPOOL_CONFIG_MMP_STATE, MMP_STATE_INACTIVE);
		fnvlist_add_uint64(spa->spa_load_info,
		    ZPOOL_CONFIG_MMP_TXG, ub->ub_txg);
		fnvlist_add_uint16(spa->spa_load_info,
		    ZPOOL_CONFIG_MMP_SEQ,
		    (MMP_SEQ_VALID(ub) ? MMP_SEQ(ub) : 0));
	}

	/*
	 * If the pool has an unsupported version we can't open it.
	 */
	if (!SPA_VERSION_IS_SUPPORTED(ub->ub_version)) {
		nvlist_free(label);
		spa_load_failed(spa, "version %llu is not supported",
		    (u_longlong_t)ub->ub_version);
		return (spa_vdev_err(rvd, VDEV_AUX_VERSION_NEWER, ENOTSUP));
	}

	if (ub->ub_version >= SPA_VERSION_FEATURES) {
		nvlist_t *features;

		/*
		 * If we weren't able to find what's necessary for reading the
		 * MOS in the label, return failure.
		 */
		if (label == NULL) {
			spa_load_failed(spa, "label config unavailable");
			return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA,
			    ENXIO));
		}

		if (nvlist_lookup_nvlist(label, ZPOOL_CONFIG_FEATURES_FOR_READ,
		    &features) != 0) {
			nvlist_free(label);
			spa_load_failed(spa, "invalid label: '%s' missing",
			    ZPOOL_CONFIG_FEATURES_FOR_READ);
			return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA,
			    ENXIO));
		}

		/*
		 * Update our in-core representation with the definitive values
		 * from the label.
		 */
		nvlist_free(spa->spa_label_features);
		VERIFY(nvlist_dup(features, &spa->spa_label_features, 0) == 0);
	}

	nvlist_free(label);

	/*
	 * Look through entries in the label nvlist's features_for_read. If
	 * there is a feature listed there which we don't understand then we
	 * cannot open a pool.
	 */
	if (ub->ub_version >= SPA_VERSION_FEATURES) {
		nvlist_t *unsup_feat;

		VERIFY(nvlist_alloc(&unsup_feat, NV_UNIQUE_NAME, KM_SLEEP) ==
		    0);

		for (nvpair_t *nvp = nvlist_next_nvpair(spa->spa_label_features,
		    NULL); nvp != NULL;
		    nvp = nvlist_next_nvpair(spa->spa_label_features, nvp)) {
			if (!zfeature_is_supported(nvpair_name(nvp))) {
				VERIFY(nvlist_add_string(unsup_feat,
				    nvpair_name(nvp), "") == 0);
			}
		}

		if (!nvlist_empty(unsup_feat)) {
			VERIFY(nvlist_add_nvlist(spa->spa_load_info,
			    ZPOOL_CONFIG_UNSUP_FEAT, unsup_feat) == 0);
			nvlist_free(unsup_feat);
			spa_load_failed(spa, "some features are unsupported");
			return (spa_vdev_err(rvd, VDEV_AUX_UNSUP_FEAT,
			    ENOTSUP));
		}

		nvlist_free(unsup_feat);
	}

	if (type != SPA_IMPORT_ASSEMBLE && spa->spa_config_splitting) {
		spa_config_enter(spa, SCL_ALL, FTAG, RW_WRITER);
		spa_try_repair(spa, spa->spa_config);
		spa_config_exit(spa, SCL_ALL, FTAG);
		nvlist_free(spa->spa_config_splitting);
		spa->spa_config_splitting = NULL;
	}

	/*
	 * Initialize internal SPA structures.
	 */
	spa_ld_select_uberblock_done(spa, ub);

	return (0);
}

static int
spa_ld_open_rootbp(spa_t *spa)
{
	int error = 0;
	vdev_t *rvd = spa->spa_root_vdev;

	error = dsl_pool_init(spa, spa->spa_first_txg, &spa->spa_dsl_pool);
	if (error != 0) {
		spa_load_failed(spa, "unable to open rootbp in dsl_pool_init "
		    "[error=%d]", error);
		return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));
	}
	spa->spa_meta_objset = spa->spa_dsl_pool->dp_meta_objset;

	return (0);
}

static int
spa_ld_trusted_config(spa_t *spa, spa_import_type_t type,
    boolean_t reloading)
{
	vdev_t *mrvd, *rvd = spa->spa_root_vdev;
	nvlist_t *nv, *mos_config, *policy;
	int error = 0, copy_error;
	uint64_t healthy_tvds, healthy_tvds_mos;
	uint64_t mos_config_txg;

	if (spa_dir_prop(spa, DMU_POOL_CONFIG, &spa->spa_config_object, B_TRUE)
	    != 0)
		return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));

	/*
	 * If we're assembling a pool from a split, the config provided is
	 * already trusted so there is nothing to do.
	 */
	if (type == SPA_IMPORT_ASSEMBLE)
		return (0);

	healthy_tvds = spa_healthy_core_tvds(spa);

	if (load_nvlist(spa, spa->spa_config_object, &mos_config)
	    != 0) {
		spa_load_failed(spa, "unable to retrieve MOS config");
		return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));
	}

	/*
	 * If we are doing an open, pool owner wasn't verified yet, thus do
	 * the verification here.
	 */
	if (spa->spa_load_state == SPA_LOAD_OPEN) {
		error = spa_verify_host(spa, mos_config);
		if (error != 0) {
			nvlist_free(mos_config);
			return (error);
		}
	}

	nv = fnvlist_lookup_nvlist(mos_config, ZPOOL_CONFIG_VDEV_TREE);

	spa_config_enter(spa, SCL_ALL, FTAG, RW_WRITER);

	/*
	 * Build a new vdev tree from the trusted config
	 */
	VERIFY(spa_config_parse(spa, &mrvd, nv, NULL, 0, VDEV_ALLOC_LOAD) == 0);

	/*
	 * Vdev paths in the MOS may be obsolete. If the untrusted config was
	 * obtained by scanning /dev/dsk, then it will have the right vdev
	 * paths. We update the trusted MOS config with this information.
	 * We first try to copy the paths with vdev_copy_path_strict, which
	 * succeeds only when both configs have exactly the same vdev tree.
	 * If that fails, we fall back to a more flexible method that has a
	 * best effort policy.
	 */
	copy_error = vdev_copy_path_strict(rvd, mrvd);
	if (copy_error != 0 || spa_load_print_vdev_tree) {
		spa_load_note(spa, "provided vdev tree:");
		vdev_dbgmsg_print_tree(rvd, 2);
		spa_load_note(spa, "MOS vdev tree:");
		vdev_dbgmsg_print_tree(mrvd, 2);
	}
	if (copy_error != 0) {
		spa_load_note(spa, "vdev_copy_path_strict failed, falling "
		    "back to vdev_copy_path_relaxed");
		vdev_copy_path_relaxed(rvd, mrvd);
	}

	vdev_close(rvd);
	vdev_free(rvd);
	spa->spa_root_vdev = mrvd;
	rvd = mrvd;
	spa_config_exit(spa, SCL_ALL, FTAG);

	/*
	 * We will use spa_config if we decide to reload the spa or if spa_load
	 * fails and we rewind. We must thus regenerate the config using the
	 * MOS information with the updated paths. ZPOOL_LOAD_POLICY is used to
	 * pass settings on how to load the pool and is not stored in the MOS.
	 * We copy it over to our new, trusted config.
	 */
	mos_config_txg = fnvlist_lookup_uint64(mos_config,
	    ZPOOL_CONFIG_POOL_TXG);
	nvlist_free(mos_config);
	mos_config = spa_config_generate(spa, NULL, mos_config_txg, B_FALSE);
	if (nvlist_lookup_nvlist(spa->spa_config, ZPOOL_LOAD_POLICY,
	    &policy) == 0)
		fnvlist_add_nvlist(mos_config, ZPOOL_LOAD_POLICY, policy);
	spa_config_set(spa, mos_config);
	spa->spa_config_source = SPA_CONFIG_SRC_MOS;

	/*
	 * Now that we got the config from the MOS, we should be more strict
	 * in checking blkptrs and can make assumptions about the consistency
	 * of the vdev tree. spa_trust_config must be set to true before opening
	 * vdevs in order for them to be writeable.
	 */
	spa->spa_trust_config = B_TRUE;

	/*
	 * Open and validate the new vdev tree
	 */
	error = spa_ld_open_vdevs(spa);
	if (error != 0)
		return (error);

	error = spa_ld_validate_vdevs(spa);
	if (error != 0)
		return (error);

	if (copy_error != 0 || spa_load_print_vdev_tree) {
		spa_load_note(spa, "final vdev tree:");
		vdev_dbgmsg_print_tree(rvd, 2);
	}

	if (spa->spa_load_state != SPA_LOAD_TRYIMPORT &&
	    !spa->spa_extreme_rewind && zfs_max_missing_tvds == 0) {
		/*
		 * Sanity check to make sure that we are indeed loading the
		 * latest uberblock. If we missed SPA_SYNC_MIN_VDEVS tvds
		 * in the config provided and they happened to be the only ones
		 * to have the latest uberblock, we could involuntarily perform
		 * an extreme rewind.
		 */
		healthy_tvds_mos = spa_healthy_core_tvds(spa);
		if (healthy_tvds_mos - healthy_tvds >=
		    SPA_SYNC_MIN_VDEVS) {
			spa_load_note(spa, "config provided misses too many "
			    "top-level vdevs compared to MOS (%lld vs %lld). ",
			    (u_longlong_t)healthy_tvds,
			    (u_longlong_t)healthy_tvds_mos);
			spa_load_note(spa, "vdev tree:");
			vdev_dbgmsg_print_tree(rvd, 2);
			if (reloading) {
				spa_load_failed(spa, "config was already "
				    "provided from MOS. Aborting.");
				return (spa_vdev_err(rvd,
				    VDEV_AUX_CORRUPT_DATA, EIO));
			}
			spa_load_note(spa, "spa must be reloaded using MOS "
			    "config");
			return (SET_ERROR(EAGAIN));
		}
	}

	error = spa_check_for_missing_logs(spa);
	if (error != 0)
		return (spa_vdev_err(rvd, VDEV_AUX_BAD_GUID_SUM, ENXIO));

	if (rvd->vdev_guid_sum != spa->spa_uberblock.ub_guid_sum) {
		spa_load_failed(spa, "uberblock guid sum doesn't match MOS "
		    "guid sum (%llu != %llu)",
		    (u_longlong_t)spa->spa_uberblock.ub_guid_sum,
		    (u_longlong_t)rvd->vdev_guid_sum);
		return (spa_vdev_err(rvd, VDEV_AUX_BAD_GUID_SUM,
		    ENXIO));
	}

	return (0);
}

static int
spa_ld_open_indirect_vdev_metadata(spa_t *spa)
{
	int error = 0;
	vdev_t *rvd = spa->spa_root_vdev;

	/*
	 * Everything that we read before spa_remove_init() must be stored
	 * on concreted vdevs.  Therefore we do this as early as possible.
	 */
	error = spa_remove_init(spa);
	if (error != 0) {
		spa_load_failed(spa, "spa_remove_init failed [error=%d]",
		    error);
		return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));
	}

	/*
	 * Retrieve information needed to condense indirect vdev mappings.
	 */
	error = spa_condense_init(spa);
	if (error != 0) {
		spa_load_failed(spa, "spa_condense_init failed [error=%d]",
		    error);
		return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, error));
	}

	return (0);
}

static int
spa_ld_check_features(spa_t *spa, boolean_t *missing_feat_writep)
{
	int error = 0;
	vdev_t *rvd = spa->spa_root_vdev;

	if (spa_version(spa) >= SPA_VERSION_FEATURES) {
		boolean_t missing_feat_read = B_FALSE;
		nvlist_t *unsup_feat, *enabled_feat;

		if (spa_dir_prop(spa, DMU_POOL_FEATURES_FOR_READ,
		    &spa->spa_feat_for_read_obj, B_TRUE) != 0) {
			return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));
		}

		if (spa_dir_prop(spa, DMU_POOL_FEATURES_FOR_WRITE,
		    &spa->spa_feat_for_write_obj, B_TRUE) != 0) {
			return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));
		}

		if (spa_dir_prop(spa, DMU_POOL_FEATURE_DESCRIPTIONS,
		    &spa->spa_feat_desc_obj, B_TRUE) != 0) {
			return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));
		}

		enabled_feat = fnvlist_alloc();
		unsup_feat = fnvlist_alloc();

		if (!spa_features_check(spa, B_FALSE,
		    unsup_feat, enabled_feat))
			missing_feat_read = B_TRUE;

		if (spa_writeable(spa) ||
		    spa->spa_load_state == SPA_LOAD_TRYIMPORT) {
			if (!spa_features_check(spa, B_TRUE,
			    unsup_feat, enabled_feat)) {
				*missing_feat_writep = B_TRUE;
			}
		}

		fnvlist_add_nvlist(spa->spa_load_info,
		    ZPOOL_CONFIG_ENABLED_FEAT, enabled_feat);

		if (!nvlist_empty(unsup_feat)) {
			fnvlist_add_nvlist(spa->spa_load_info,
			    ZPOOL_CONFIG_UNSUP_FEAT, unsup_feat);
		}

		fnvlist_free(enabled_feat);
		fnvlist_free(unsup_feat);

		if (!missing_feat_read) {
			fnvlist_add_boolean(spa->spa_load_info,
			    ZPOOL_CONFIG_CAN_RDONLY);
		}

		/*
		 * If the state is SPA_LOAD_TRYIMPORT, our objective is
		 * twofold: to determine whether the pool is available for
		 * import in read-write mode and (if it is not) whether the
		 * pool is available for import in read-only mode. If the pool
		 * is available for import in read-write mode, it is displayed
		 * as available in userland; if it is not available for import
		 * in read-only mode, it is displayed as unavailable in
		 * userland. If the pool is available for import in read-only
		 * mode but not read-write mode, it is displayed as unavailable
		 * in userland with a special note that the pool is actually
		 * available for open in read-only mode.
		 *
		 * As a result, if the state is SPA_LOAD_TRYIMPORT and we are
		 * missing a feature for write, we must first determine whether
		 * the pool can be opened read-only before returning to
		 * userland in order to know whether to display the
		 * abovementioned note.
		 */
		if (missing_feat_read || (*missing_feat_writep &&
		    spa_writeable(spa))) {
			spa_load_failed(spa, "pool uses unsupported features");
			return (spa_vdev_err(rvd, VDEV_AUX_UNSUP_FEAT,
			    ENOTSUP));
		}

		/*
		 * Load refcounts for ZFS features from disk into an in-memory
		 * cache during SPA initialization.
		 */
		for (spa_feature_t i = 0; i < SPA_FEATURES; i++) {
			uint64_t refcount;

			error = feature_get_refcount_from_disk(spa,
			    &spa_feature_table[i], &refcount);
			if (error == 0) {
				spa->spa_feat_refcount_cache[i] = refcount;
			} else if (error == ENOTSUP) {
				spa->spa_feat_refcount_cache[i] =
				    SPA_FEATURE_DISABLED;
			} else {
				spa_load_failed(spa, "error getting refcount "
				    "for feature %s [error=%d]",
				    spa_feature_table[i].fi_guid, error);
				return (spa_vdev_err(rvd,
				    VDEV_AUX_CORRUPT_DATA, EIO));
			}
		}
	}

	if (spa_feature_is_active(spa, SPA_FEATURE_ENABLED_TXG)) {
		if (spa_dir_prop(spa, DMU_POOL_FEATURE_ENABLED_TXG,
		    &spa->spa_feat_enabled_txg_obj, B_TRUE) != 0)
			return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));
	}

	/*
	 * Encryption was added before bookmark_v2, even though bookmark_v2
	 * is now a dependency. If this pool has encryption enabled without
	 * bookmark_v2, trigger an errata message.
	 */
	if (spa_feature_is_enabled(spa, SPA_FEATURE_ENCRYPTION) &&
	    !spa_feature_is_enabled(spa, SPA_FEATURE_BOOKMARK_V2)) {
		spa->spa_errata = ZPOOL_ERRATA_ZOL_8308_ENCRYPTION;
	}

	return (0);
}

static int
spa_ld_load_special_directories(spa_t *spa)
{
	int error = 0;
	vdev_t *rvd = spa->spa_root_vdev;

	spa->spa_is_initializing = B_TRUE;
	error = dsl_pool_open(spa->spa_dsl_pool);
	spa->spa_is_initializing = B_FALSE;
	if (error != 0) {
		spa_load_failed(spa, "dsl_pool_open failed [error=%d]", error);
		return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));
	}

	return (0);
}

static int
spa_ld_get_props(spa_t *spa)
{
	int error = 0;
	uint64_t obj;
	vdev_t *rvd = spa->spa_root_vdev;

	/* Grab the checksum salt from the MOS. */
	error = zap_lookup(spa->spa_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
	    DMU_POOL_CHECKSUM_SALT, 1,
	    sizeof (spa->spa_cksum_salt.zcs_bytes),
	    spa->spa_cksum_salt.zcs_bytes);
	if (error == ENOENT) {
		/* Generate a new salt for subsequent use */
		(void) random_get_pseudo_bytes(spa->spa_cksum_salt.zcs_bytes,
		    sizeof (spa->spa_cksum_salt.zcs_bytes));
	} else if (error != 0) {
		spa_load_failed(spa, "unable to retrieve checksum salt from "
		    "MOS [error=%d]", error);
		return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));
	}

	if (spa_dir_prop(spa, DMU_POOL_SYNC_BPOBJ, &obj, B_TRUE) != 0)
		return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));
	error = bpobj_open(&spa->spa_deferred_bpobj, spa->spa_meta_objset, obj);
	if (error != 0) {
		spa_load_failed(spa, "error opening deferred-frees bpobj "
		    "[error=%d]", error);
		return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));
	}

	/*
	 * Load the bit that tells us to use the new accounting function
	 * (raid-z deflation).  If we have an older pool, this will not
	 * be present.
	 */
	error = spa_dir_prop(spa, DMU_POOL_DEFLATE, &spa->spa_deflate, B_FALSE);
	if (error != 0 && error != ENOENT)
		return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));

	error = spa_dir_prop(spa, DMU_POOL_CREATION_VERSION,
	    &spa->spa_creation_version, B_FALSE);
	if (error != 0 && error != ENOENT)
		return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));

	/*
	 * Load the persistent error log.  If we have an older pool, this will
	 * not be present.
	 */
	error = spa_dir_prop(spa, DMU_POOL_ERRLOG_LAST, &spa->spa_errlog_last,
	    B_FALSE);
	if (error != 0 && error != ENOENT)
		return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));

	error = spa_dir_prop(spa, DMU_POOL_ERRLOG_SCRUB,
	    &spa->spa_errlog_scrub, B_FALSE);
	if (error != 0 && error != ENOENT)
		return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));

	/*
	 * Load the history object.  If we have an older pool, this
	 * will not be present.
	 */
	error = spa_dir_prop(spa, DMU_POOL_HISTORY, &spa->spa_history, B_FALSE);
	if (error != 0 && error != ENOENT)
		return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));

	/*
	 * Load the per-vdev ZAP map. If we have an older pool, this will not
	 * be present; in this case, defer its creation to a later time to
	 * avoid dirtying the MOS this early / out of sync context. See
	 * spa_sync_config_object.
	 */

	/* The sentinel is only available in the MOS config. */
	nvlist_t *mos_config;
	if (load_nvlist(spa, spa->spa_config_object, &mos_config) != 0) {
		spa_load_failed(spa, "unable to retrieve MOS config");
		return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));
	}

	error = spa_dir_prop(spa, DMU_POOL_VDEV_ZAP_MAP,
	    &spa->spa_all_vdev_zaps, B_FALSE);

	if (error == ENOENT) {
		VERIFY(!nvlist_exists(mos_config,
		    ZPOOL_CONFIG_HAS_PER_VDEV_ZAPS));
		spa->spa_avz_action = AVZ_ACTION_INITIALIZE;
		ASSERT0(vdev_count_verify_zaps(spa->spa_root_vdev));
	} else if (error != 0) {
		return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));
	} else if (!nvlist_exists(mos_config, ZPOOL_CONFIG_HAS_PER_VDEV_ZAPS)) {
		/*
		 * An older version of ZFS overwrote the sentinel value, so
		 * we have orphaned per-vdev ZAPs in the MOS. Defer their
		 * destruction to later; see spa_sync_config_object.
		 */
		spa->spa_avz_action = AVZ_ACTION_DESTROY;
		/*
		 * We're assuming that no vdevs have had their ZAPs created
		 * before this. Better be sure of it.
		 */
		ASSERT0(vdev_count_verify_zaps(spa->spa_root_vdev));
	}
	nvlist_free(mos_config);

	spa->spa_delegation = zpool_prop_default_numeric(ZPOOL_PROP_DELEGATION);

	error = spa_dir_prop(spa, DMU_POOL_PROPS, &spa->spa_pool_props_object,
	    B_FALSE);
	if (error && error != ENOENT)
		return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));

	if (error == 0) {
		uint64_t autoreplace;

		spa_prop_find(spa, ZPOOL_PROP_BOOTFS, &spa->spa_bootfs);
		spa_prop_find(spa, ZPOOL_PROP_AUTOREPLACE, &autoreplace);
		spa_prop_find(spa, ZPOOL_PROP_DELEGATION, &spa->spa_delegation);
		spa_prop_find(spa, ZPOOL_PROP_FAILUREMODE, &spa->spa_failmode);
		spa_prop_find(spa, ZPOOL_PROP_AUTOEXPAND, &spa->spa_autoexpand);
		spa_prop_find(spa, ZPOOL_PROP_MULTIHOST, &spa->spa_multihost);
		spa_prop_find(spa, ZPOOL_PROP_DEDUPDITTO,
		    &spa->spa_dedup_ditto);
		spa_prop_find(spa, ZPOOL_PROP_AUTOTRIM, &spa->spa_autotrim);
		spa->spa_autoreplace = (autoreplace != 0);
	}

	/*
	 * If we are importing a pool with missing top-level vdevs,
	 * we enforce that the pool doesn't panic or get suspended on
	 * error since the likelihood of missing data is extremely high.
	 */
	if (spa->spa_missing_tvds > 0 &&
	    spa->spa_failmode != ZIO_FAILURE_MODE_CONTINUE &&
	    spa->spa_load_state != SPA_LOAD_TRYIMPORT) {
		spa_load_note(spa, "forcing failmode to 'continue' "
		    "as some top level vdevs are missing");
		spa->spa_failmode = ZIO_FAILURE_MODE_CONTINUE;
	}

	return (0);
}

static int
spa_ld_open_aux_vdevs(spa_t *spa, spa_import_type_t type)
{
	int error = 0;
	vdev_t *rvd = spa->spa_root_vdev;

	/*
	 * If we're assembling the pool from the split-off vdevs of
	 * an existing pool, we don't want to attach the spares & cache
	 * devices.
	 */

	/*
	 * Load any hot spares for this pool.
	 */
	error = spa_dir_prop(spa, DMU_POOL_SPARES, &spa->spa_spares.sav_object,
	    B_FALSE);
	if (error != 0 && error != ENOENT)
		return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));
	if (error == 0 && type != SPA_IMPORT_ASSEMBLE) {
		ASSERT(spa_version(spa) >= SPA_VERSION_SPARES);
		if (load_nvlist(spa, spa->spa_spares.sav_object,
		    &spa->spa_spares.sav_config) != 0) {
			spa_load_failed(spa, "error loading spares nvlist");
			return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));
		}

		spa_config_enter(spa, SCL_ALL, FTAG, RW_WRITER);
		spa_load_spares(spa);
		spa_config_exit(spa, SCL_ALL, FTAG);
	} else if (error == 0) {
		spa->spa_spares.sav_sync = B_TRUE;
	}

	/*
	 * Load any level 2 ARC devices for this pool.
	 */
	error = spa_dir_prop(spa, DMU_POOL_L2CACHE,
	    &spa->spa_l2cache.sav_object, B_FALSE);
	if (error != 0 && error != ENOENT)
		return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));
	if (error == 0 && type != SPA_IMPORT_ASSEMBLE) {
		ASSERT(spa_version(spa) >= SPA_VERSION_L2CACHE);
		if (load_nvlist(spa, spa->spa_l2cache.sav_object,
		    &spa->spa_l2cache.sav_config) != 0) {
			spa_load_failed(spa, "error loading l2cache nvlist");
			return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));
		}

		spa_config_enter(spa, SCL_ALL, FTAG, RW_WRITER);
		spa_load_l2cache(spa);
		spa_config_exit(spa, SCL_ALL, FTAG);
	} else if (error == 0) {
		spa->spa_l2cache.sav_sync = B_TRUE;
	}

	return (0);
}

static int
spa_ld_load_vdev_metadata(spa_t *spa)
{
	int error = 0;
	vdev_t *rvd = spa->spa_root_vdev;

	/*
	 * If the 'multihost' property is set, then never allow a pool to
	 * be imported when the system hostid is zero.  The exception to
	 * this rule is zdb which is always allowed to access pools.
	 */
	if (spa_multihost(spa) && spa_get_hostid() == 0 &&
	    (spa->spa_import_flags & ZFS_IMPORT_SKIP_MMP) == 0) {
		fnvlist_add_uint64(spa->spa_load_info,
		    ZPOOL_CONFIG_MMP_STATE, MMP_STATE_NO_HOSTID);
		return (spa_vdev_err(rvd, VDEV_AUX_ACTIVE, EREMOTEIO));
	}

	/*
	 * If the 'autoreplace' property is set, then post a resource notifying
	 * the ZFS DE that it should not issue any faults for unopenable
	 * devices.  We also iterate over the vdevs, and post a sysevent for any
	 * unopenable vdevs so that the normal autoreplace handler can take
	 * over.
	 */
	if (spa->spa_autoreplace && spa->spa_load_state != SPA_LOAD_TRYIMPORT) {
		spa_check_removed(spa->spa_root_vdev);
		/*
		 * For the import case, this is done in spa_import(), because
		 * at this point we're using the spare definitions from
		 * the MOS config, not necessarily from the userland config.
		 */
		if (spa->spa_load_state != SPA_LOAD_IMPORT) {
			spa_aux_check_removed(&spa->spa_spares);
			spa_aux_check_removed(&spa->spa_l2cache);
		}
	}

	/*
	 * Load the vdev metadata such as metaslabs, DTLs, spacemap object, etc.
	 */
	error = vdev_load(rvd);
	if (error != 0) {
		spa_load_failed(spa, "vdev_load failed [error=%d]", error);
		return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, error));
	}

	/*
	 * Propagate the leaf DTLs we just loaded all the way up the vdev tree.
	 */
	spa_config_enter(spa, SCL_ALL, FTAG, RW_WRITER);
	vdev_dtl_reassess(rvd, 0, 0, B_FALSE);
	spa_config_exit(spa, SCL_ALL, FTAG);

	return (0);
}

static int
spa_ld_load_dedup_tables(spa_t *spa)
{
	int error = 0;
	vdev_t *rvd = spa->spa_root_vdev;

	error = ddt_load(spa);
	if (error != 0) {
		spa_load_failed(spa, "ddt_load failed [error=%d]", error);
		return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));
	}

	return (0);
}

static int
spa_ld_verify_logs(spa_t *spa, spa_import_type_t type, char **ereport)
{
	vdev_t *rvd = spa->spa_root_vdev;

	if (type != SPA_IMPORT_ASSEMBLE && spa_writeable(spa)) {
		boolean_t missing = spa_check_logs(spa);
		if (missing) {
			if (spa->spa_missing_tvds != 0) {
				spa_load_note(spa, "spa_check_logs failed "
				    "so dropping the logs");
			} else {
				*ereport = FM_EREPORT_ZFS_LOG_REPLAY;
				spa_load_failed(spa, "spa_check_logs failed");
				return (spa_vdev_err(rvd, VDEV_AUX_BAD_LOG,
				    ENXIO));
			}
		}
	}

	return (0);
}

static int
spa_ld_verify_pool_data(spa_t *spa)
{
	int error = 0;
	vdev_t *rvd = spa->spa_root_vdev;

	/*
	 * We've successfully opened the pool, verify that we're ready
	 * to start pushing transactions.
	 */
	if (spa->spa_load_state != SPA_LOAD_TRYIMPORT) {
		error = spa_load_verify(spa);
		if (error != 0) {
			spa_load_failed(spa, "spa_load_verify failed "
			    "[error=%d]", error);
			return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA,
			    error));
		}
	}

	return (0);
}

static void
spa_ld_claim_log_blocks(spa_t *spa)
{
	dmu_tx_t *tx;
	dsl_pool_t *dp = spa_get_dsl(spa);

	/*
	 * Claim log blocks that haven't been committed yet.
	 * This must all happen in a single txg.
	 * Note: spa_claim_max_txg is updated by spa_claim_notify(),
	 * invoked from zil_claim_log_block()'s i/o done callback.
	 * Price of rollback is that we abandon the log.
	 */
	spa->spa_claiming = B_TRUE;

	tx = dmu_tx_create_assigned(dp, spa_first_txg(spa));
	(void) dmu_objset_find_dp(dp, dp->dp_root_dir_obj,
	    zil_claim, tx, DS_FIND_CHILDREN);
	dmu_tx_commit(tx);

	spa->spa_claiming = B_FALSE;

	spa_set_log_state(spa, SPA_LOG_GOOD);
}

static void
spa_ld_check_for_config_update(spa_t *spa, uint64_t config_cache_txg,
    boolean_t update_config_cache)
{
	vdev_t *rvd = spa->spa_root_vdev;
	int need_update = B_FALSE;

	/*
	 * If the config cache is stale, or we have uninitialized
	 * metaslabs (see spa_vdev_add()), then update the config.
	 *
	 * If this is a verbatim import, trust the current
	 * in-core spa_config and update the disk labels.
	 */
	if (update_config_cache || config_cache_txg != spa->spa_config_txg ||
	    spa->spa_load_state == SPA_LOAD_IMPORT ||
	    spa->spa_load_state == SPA_LOAD_RECOVER ||
	    (spa->spa_import_flags & ZFS_IMPORT_VERBATIM))
		need_update = B_TRUE;

	for (int c = 0; c < rvd->vdev_children; c++)
		if (rvd->vdev_child[c]->vdev_ms_array == 0)
			need_update = B_TRUE;

	/*
	 * Update the config cache asychronously in case we're the
	 * root pool, in which case the config cache isn't writable yet.
	 */
	if (need_update)
		spa_async_request(spa, SPA_ASYNC_CONFIG_UPDATE);
}

static void
spa_ld_prepare_for_reload(spa_t *spa)
{
	int mode = spa->spa_mode;
	int async_suspended = spa->spa_async_suspended;

	spa_unload(spa);
	spa_deactivate(spa);
	spa_activate(spa, mode);

	/*
	 * We save the value of spa_async_suspended as it gets reset to 0 by
	 * spa_unload(). We want to restore it back to the original value before
	 * returning as we might be calling spa_async_resume() later.
	 */
	spa->spa_async_suspended = async_suspended;
}

static int
spa_ld_read_checkpoint_txg(spa_t *spa)
{
	uberblock_t checkpoint;
	int error = 0;

	ASSERT0(spa->spa_checkpoint_txg);
	ASSERT(MUTEX_HELD(&spa_namespace_lock));

	error = zap_lookup(spa->spa_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
	    DMU_POOL_ZPOOL_CHECKPOINT, sizeof (uint64_t),
	    sizeof (uberblock_t) / sizeof (uint64_t), &checkpoint);

	if (error == ENOENT)
		return (0);

	if (error != 0)
		return (error);

	ASSERT3U(checkpoint.ub_txg, !=, 0);
	ASSERT3U(checkpoint.ub_checkpoint_txg, !=, 0);
	ASSERT3U(checkpoint.ub_timestamp, !=, 0);
	spa->spa_checkpoint_txg = checkpoint.ub_txg;
	spa->spa_checkpoint_info.sci_timestamp = checkpoint.ub_timestamp;

	return (0);
}

static int
spa_ld_mos_init(spa_t *spa, spa_import_type_t type)
{
	int error = 0;

	ASSERT(MUTEX_HELD(&spa_namespace_lock));
	ASSERT(spa->spa_config_source != SPA_CONFIG_SRC_NONE);

	/*
	 * Never trust the config that is provided unless we are assembling
	 * a pool following a split.
	 * This means don't trust blkptrs and the vdev tree in general. This
	 * also effectively puts the spa in read-only mode since
	 * spa_writeable() checks for spa_trust_config to be true.
	 * We will later load a trusted config from the MOS.
	 */
	if (type != SPA_IMPORT_ASSEMBLE)
		spa->spa_trust_config = B_FALSE;

	/*
	 * Parse the config provided to create a vdev tree.
	 */
	error = spa_ld_parse_config(spa, type);
	if (error != 0)
		return (error);

	spa_import_progress_add(spa);

	/*
	 * Now that we have the vdev tree, try to open each vdev. This involves
	 * opening the underlying physical device, retrieving its geometry and
	 * probing the vdev with a dummy I/O. The state of each vdev will be set
	 * based on the success of those operations. After this we'll be ready
	 * to read from the vdevs.
	 */
	error = spa_ld_open_vdevs(spa);
	if (error != 0)
		return (error);

	/*
	 * Read the label of each vdev and make sure that the GUIDs stored
	 * there match the GUIDs in the config provided.
	 * If we're assembling a new pool that's been split off from an
	 * existing pool, the labels haven't yet been updated so we skip
	 * validation for now.
	 */
	if (type != SPA_IMPORT_ASSEMBLE) {
		error = spa_ld_validate_vdevs(spa);
		if (error != 0)
			return (error);
	}

	/*
	 * Read all vdev labels to find the best uberblock (i.e. latest,
	 * unless spa_load_max_txg is set) and store it in spa_uberblock. We
	 * get the list of features required to read blkptrs in the MOS from
	 * the vdev label with the best uberblock and verify that our version
	 * of zfs supports them all.
	 */
	error = spa_ld_select_uberblock(spa, type);
	if (error != 0)
		return (error);

	/*
	 * Pass that uberblock to the dsl_pool layer which will open the root
	 * blkptr. This blkptr points to the latest version of the MOS and will
	 * allow us to read its contents.
	 */
	error = spa_ld_open_rootbp(spa);
	if (error != 0)
		return (error);

	return (0);
}

static int
spa_ld_checkpoint_rewind(spa_t *spa)
{
	uberblock_t checkpoint;
	int error = 0;

	ASSERT(MUTEX_HELD(&spa_namespace_lock));
	ASSERT(spa->spa_import_flags & ZFS_IMPORT_CHECKPOINT);

	error = zap_lookup(spa->spa_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
	    DMU_POOL_ZPOOL_CHECKPOINT, sizeof (uint64_t),
	    sizeof (uberblock_t) / sizeof (uint64_t), &checkpoint);

	if (error != 0) {
		spa_load_failed(spa, "unable to retrieve checkpointed "
		    "uberblock from the MOS config [error=%d]", error);

		if (error == ENOENT)
			error = ZFS_ERR_NO_CHECKPOINT;

		return (error);
	}

	ASSERT3U(checkpoint.ub_txg, <, spa->spa_uberblock.ub_txg);
	ASSERT3U(checkpoint.ub_txg, ==, checkpoint.ub_checkpoint_txg);

	/*
	 * We need to update the txg and timestamp of the checkpointed
	 * uberblock to be higher than the latest one. This ensures that
	 * the checkpointed uberblock is selected if we were to close and
	 * reopen the pool right after we've written it in the vdev labels.
	 * (also see block comment in vdev_uberblock_compare)
	 */
	checkpoint.ub_txg = spa->spa_uberblock.ub_txg + 1;
	checkpoint.ub_timestamp = gethrestime_sec();

	/*
	 * Set current uberblock to be the checkpointed uberblock.
	 */
	spa->spa_uberblock = checkpoint;

	/*
	 * If we are doing a normal rewind, then the pool is open for
	 * writing and we sync the "updated" checkpointed uberblock to
	 * disk. Once this is done, we've basically rewound the whole
	 * pool and there is no way back.
	 *
	 * There are cases when we don't want to attempt and sync the
	 * checkpointed uberblock to disk because we are opening a
	 * pool as read-only. Specifically, verifying the checkpointed
	 * state with zdb, and importing the checkpointed state to get
	 * a "preview" of its content.
	 */
	if (spa_writeable(spa)) {
		vdev_t *rvd = spa->spa_root_vdev;

		spa_config_enter(spa, SCL_ALL, FTAG, RW_WRITER);
		vdev_t *svd[SPA_SYNC_MIN_VDEVS] = { NULL };
		int svdcount = 0;
		int children = rvd->vdev_children;
		int c0 = spa_get_random(children);

		for (int c = 0; c < children; c++) {
			vdev_t *vd = rvd->vdev_child[(c0 + c) % children];

			/* Stop when revisiting the first vdev */
			if (c > 0 && svd[0] == vd)
				break;

			if (vd->vdev_ms_array == 0 || vd->vdev_islog ||
			    !vdev_is_concrete(vd))
				continue;

			svd[svdcount++] = vd;
			if (svdcount == SPA_SYNC_MIN_VDEVS)
				break;
		}
		error = vdev_config_sync(svd, svdcount, spa->spa_first_txg);
		if (error == 0)
			spa->spa_last_synced_guid = rvd->vdev_guid;
		spa_config_exit(spa, SCL_ALL, FTAG);

		if (error != 0) {
			spa_load_failed(spa, "failed to write checkpointed "
			    "uberblock to the vdev labels [error=%d]", error);
			return (error);
		}
	}

	return (0);
}

static int
spa_ld_mos_with_trusted_config(spa_t *spa, spa_import_type_t type,
    boolean_t *update_config_cache)
{
	int error;

	/*
	 * Parse the config for pool, open and validate vdevs,
	 * select an uberblock, and use that uberblock to open
	 * the MOS.
	 */
	error = spa_ld_mos_init(spa, type);
	if (error != 0)
		return (error);

	/*
	 * Retrieve the trusted config stored in the MOS and use it to create
	 * a new, exact version of the vdev tree, then reopen all vdevs.
	 */
	error = spa_ld_trusted_config(spa, type, B_FALSE);
	if (error == EAGAIN) {
		if (update_config_cache != NULL)
			*update_config_cache = B_TRUE;

		/*
		 * Redo the loading process with the trusted config if it is
		 * too different from the untrusted config.
		 */
		spa_ld_prepare_for_reload(spa);
		spa_load_note(spa, "RELOADING");
		error = spa_ld_mos_init(spa, type);
		if (error != 0)
			return (error);

		error = spa_ld_trusted_config(spa, type, B_TRUE);
		if (error != 0)
			return (error);

	} else if (error != 0) {
		return (error);
	}

	return (0);
}

/*
 * Load an existing storage pool, using the config provided. This config
 * describes which vdevs are part of the pool and is later validated against
 * partial configs present in each vdev's label and an entire copy of the
 * config stored in the MOS.
 */
static int
spa_load_impl(spa_t *spa, spa_import_type_t type, char **ereport)
{
	int error = 0;
	boolean_t missing_feat_write = B_FALSE;
	boolean_t checkpoint_rewind =
	    (spa->spa_import_flags & ZFS_IMPORT_CHECKPOINT);
	boolean_t update_config_cache = B_FALSE;

	ASSERT(MUTEX_HELD(&spa_namespace_lock));
	ASSERT(spa->spa_config_source != SPA_CONFIG_SRC_NONE);

	spa_load_note(spa, "LOADING");

	error = spa_ld_mos_with_trusted_config(spa, type, &update_config_cache);
	if (error != 0)
		return (error);

	/*
	 * If we are rewinding to the checkpoint then we need to repeat
	 * everything we've done so far in this function but this time
	 * selecting the checkpointed uberblock and using that to open
	 * the MOS.
	 */
	if (checkpoint_rewind) {
		/*
		 * If we are rewinding to the checkpoint update config cache
		 * anyway.
		 */
		update_config_cache = B_TRUE;

		/*
		 * Extract the checkpointed uberblock from the current MOS
		 * and use this as the pool's uberblock from now on. If the
		 * pool is imported as writeable we also write the checkpoint
		 * uberblock to the labels, making the rewind permanent.
		 */
		error = spa_ld_checkpoint_rewind(spa);
		if (error != 0)
			return (error);

		/*
		 * Redo the loading process process again with the
		 * checkpointed uberblock.
		 */
		spa_ld_prepare_for_reload(spa);
		spa_load_note(spa, "LOADING checkpointed uberblock");
		error = spa_ld_mos_with_trusted_config(spa, type, NULL);
		if (error != 0)
			return (error);
	}

	/*
	 * Retrieve the checkpoint txg if the pool has a checkpoint.
	 */
	error = spa_ld_read_checkpoint_txg(spa);
	if (error != 0)
		return (error);

	/*
	 * Retrieve the mapping of indirect vdevs. Those vdevs were removed
	 * from the pool and their contents were re-mapped to other vdevs. Note
	 * that everything that we read before this step must have been
	 * rewritten on concrete vdevs after the last device removal was
	 * initiated. Otherwise we could be reading from indirect vdevs before
	 * we have loaded their mappings.
	 */
	error = spa_ld_open_indirect_vdev_metadata(spa);
	if (error != 0)
		return (error);

	/*
	 * Retrieve the full list of active features from the MOS and check if
	 * they are all supported.
	 */
	error = spa_ld_check_features(spa, &missing_feat_write);
	if (error != 0)
		return (error);

	/*
	 * Load several special directories from the MOS needed by the dsl_pool
	 * layer.
	 */
	error = spa_ld_load_special_directories(spa);
	if (error != 0)
		return (error);

	/*
	 * Retrieve pool properties from the MOS.
	 */
	error = spa_ld_get_props(spa);
	if (error != 0)
		return (error);

	/*
	 * Retrieve the list of auxiliary devices - cache devices and spares -
	 * and open them.
	 */
	error = spa_ld_open_aux_vdevs(spa, type);
	if (error != 0)
		return (error);

	/*
	 * Load the metadata for all vdevs. Also check if unopenable devices
	 * should be autoreplaced.
	 */
	error = spa_ld_load_vdev_metadata(spa);
	if (error != 0)
		return (error);

	error = spa_ld_load_dedup_tables(spa);
	if (error != 0)
		return (error);

	/*
	 * Verify the logs now to make sure we don't have any unexpected errors
	 * when we claim log blocks later.
	 */
	error = spa_ld_verify_logs(spa, type, ereport);
	if (error != 0)
		return (error);

	if (missing_feat_write) {
		ASSERT(spa->spa_load_state == SPA_LOAD_TRYIMPORT);

		/*
		 * At this point, we know that we can open the pool in
		 * read-only mode but not read-write mode. We now have enough
		 * information and can return to userland.
		 */
		return (spa_vdev_err(spa->spa_root_vdev, VDEV_AUX_UNSUP_FEAT,
		    ENOTSUP));
	}

	/*
	 * Traverse the last txgs to make sure the pool was left off in a safe
	 * state. When performing an extreme rewind, we verify the whole pool,
	 * which can take a very long time.
	 */
	error = spa_ld_verify_pool_data(spa);
	if (error != 0)
		return (error);

	/*
	 * Calculate the deflated space for the pool. This must be done before
	 * we write anything to the pool because we'd need to update the space
	 * accounting using the deflated sizes.
	 */
	spa_update_dspace(spa);

	/*
	 * We have now retrieved all the information we needed to open the
	 * pool. If we are importing the pool in read-write mode, a few
	 * additional steps must be performed to finish the import.
	 */
	if (spa_writeable(spa) && (spa->spa_load_state == SPA_LOAD_RECOVER ||
	    spa->spa_load_max_txg == UINT64_MAX)) {
		uint64_t config_cache_txg = spa->spa_config_txg;

		ASSERT(spa->spa_load_state != SPA_LOAD_TRYIMPORT);

		/*
		 * In case of a checkpoint rewind, log the original txg
		 * of the checkpointed uberblock.
		 */
		if (checkpoint_rewind) {
			spa_history_log_internal(spa, "checkpoint rewind",
			    NULL, "rewound state to txg=%llu",
			    (u_longlong_t)spa->spa_uberblock.ub_checkpoint_txg);
		}

		/*
		 * Traverse the ZIL and claim all blocks.
		 */
		spa_ld_claim_log_blocks(spa);

		/*
		 * Kick-off the syncing thread.
		 */
		spa->spa_sync_on = B_TRUE;
		txg_sync_start(spa->spa_dsl_pool);
		mmp_thread_start(spa);

		/*
		 * Wait for all claims to sync.  We sync up to the highest
		 * claimed log block birth time so that claimed log blocks
		 * don't appear to be from the future.  spa_claim_max_txg
		 * will have been set for us by ZIL traversal operations
		 * performed above.
		 */
		txg_wait_synced(spa->spa_dsl_pool, spa->spa_claim_max_txg);

		/*
		 * Check if we need to request an update of the config. On the
		 * next sync, we would update the config stored in vdev labels
		 * and the cachefile (by default /etc/zfs/zpool.cache).
		 */
		spa_ld_check_for_config_update(spa, config_cache_txg,
		    update_config_cache);

		/*
		 * Check all DTLs to see if anything needs resilvering.
		 */
		if (!dsl_scan_resilvering(spa->spa_dsl_pool) &&
		    vdev_resilver_needed(spa->spa_root_vdev, NULL, NULL))
			spa_async_request(spa, SPA_ASYNC_RESILVER);

		/*
		 * Log the fact that we booted up (so that we can detect if
		 * we rebooted in the middle of an operation).
		 */
		spa_history_log_version(spa, "open", NULL);

		spa_restart_removal(spa);
		spa_spawn_aux_threads(spa);

		/*
		 * Delete any inconsistent datasets.
		 *
		 * Note:
		 * Since we may be issuing deletes for clones here,
		 * we make sure to do so after we've spawned all the
		 * auxiliary threads above (from which the livelist
		 * deletion zthr is part of).
		 */
		(void) dmu_objset_find(spa_name(spa),
		    dsl_destroy_inconsistent, NULL, DS_FIND_CHILDREN);

		/*
		 * Clean up any stale temporary dataset userrefs.
		 */
		dsl_pool_clean_tmp_userrefs(spa->spa_dsl_pool);

		spa_config_enter(spa, SCL_CONFIG, FTAG, RW_READER);
		vdev_initialize_restart(spa->spa_root_vdev);
		vdev_trim_restart(spa->spa_root_vdev);
		vdev_autotrim_restart(spa);
		spa_config_exit(spa, SCL_CONFIG, FTAG);
	}

	spa_import_progress_remove(spa_guid(spa));
	spa_load_note(spa, "LOADED");

	return (0);
}

static int
spa_load_retry(spa_t *spa, spa_load_state_t state)
{
	int mode = spa->spa_mode;

	spa_unload(spa);
	spa_deactivate(spa);

	spa->spa_load_max_txg = spa->spa_uberblock.ub_txg - 1;

	spa_activate(spa, mode);
	spa_async_suspend(spa);

	spa_load_note(spa, "spa_load_retry: rewind, max txg: %llu",
	    (u_longlong_t)spa->spa_load_max_txg);

	return (spa_load(spa, state, SPA_IMPORT_EXISTING));
}

/*
 * If spa_load() fails this function will try loading prior txg's. If
 * 'state' is SPA_LOAD_RECOVER and one of these loads succeeds the pool
 * will be rewound to that txg. If 'state' is not SPA_LOAD_RECOVER this
 * function will not rewind the pool and will return the same error as
 * spa_load().
 */
static int
spa_load_best(spa_t *spa, spa_load_state_t state, uint64_t max_request,
    int rewind_flags)
{
	nvlist_t *loadinfo = NULL;
	nvlist_t *config = NULL;
	int load_error, rewind_error;
	uint64_t safe_rewind_txg;
	uint64_t min_txg;

	if (spa->spa_load_txg && state == SPA_LOAD_RECOVER) {
		spa->spa_load_max_txg = spa->spa_load_txg;
		spa_set_log_state(spa, SPA_LOG_CLEAR);
	} else {
		spa->spa_load_max_txg = max_request;
		if (max_request != UINT64_MAX)
			spa->spa_extreme_rewind = B_TRUE;
	}

	load_error = rewind_error = spa_load(spa, state, SPA_IMPORT_EXISTING);
	if (load_error == 0)
		return (0);
	if (load_error == ZFS_ERR_NO_CHECKPOINT) {
		/*
		 * When attempting checkpoint-rewind on a pool with no
		 * checkpoint, we should not attempt to load uberblocks
		 * from previous txgs when spa_load fails.
		 */
		ASSERT(spa->spa_import_flags & ZFS_IMPORT_CHECKPOINT);
		spa_import_progress_remove(spa_guid(spa));
		return (load_error);
	}

	if (spa->spa_root_vdev != NULL)
		config = spa_config_generate(spa, NULL, -1ULL, B_TRUE);

	spa->spa_last_ubsync_txg = spa->spa_uberblock.ub_txg;
	spa->spa_last_ubsync_txg_ts = spa->spa_uberblock.ub_timestamp;

	if (rewind_flags & ZPOOL_NEVER_REWIND) {
		nvlist_free(config);
		spa_import_progress_remove(spa_guid(spa));
		return (load_error);
	}

	if (state == SPA_LOAD_RECOVER) {
		/* Price of rolling back is discarding txgs, including log */
		spa_set_log_state(spa, SPA_LOG_CLEAR);
	} else {
		/*
		 * If we aren't rolling back save the load info from our first
		 * import attempt so that we can restore it after attempting
		 * to rewind.
		 */
		loadinfo = spa->spa_load_info;
		spa->spa_load_info = fnvlist_alloc();
	}

	spa->spa_load_max_txg = spa->spa_last_ubsync_txg;
	safe_rewind_txg = spa->spa_last_ubsync_txg - TXG_DEFER_SIZE;
	min_txg = (rewind_flags & ZPOOL_EXTREME_REWIND) ?
	    TXG_INITIAL : safe_rewind_txg;

	/*
	 * Continue as long as we're finding errors, we're still within
	 * the acceptable rewind range, and we're still finding uberblocks
	 */
	while (rewind_error && spa->spa_uberblock.ub_txg >= min_txg &&
	    spa->spa_uberblock.ub_txg <= spa->spa_load_max_txg) {
		if (spa->spa_load_max_txg < safe_rewind_txg)
			spa->spa_extreme_rewind = B_TRUE;
		rewind_error = spa_load_retry(spa, state);
	}

	spa->spa_extreme_rewind = B_FALSE;
	spa->spa_load_max_txg = UINT64_MAX;

	if (config && (rewind_error || state != SPA_LOAD_RECOVER))
		spa_config_set(spa, config);
	else
		nvlist_free(config);

	if (state == SPA_LOAD_RECOVER) {
		ASSERT3P(loadinfo, ==, NULL);
		spa_import_progress_remove(spa_guid(spa));
		return (rewind_error);
	} else {
		/* Store the rewind info as part of the initial load info */
		fnvlist_add_nvlist(loadinfo, ZPOOL_CONFIG_REWIND_INFO,
		    spa->spa_load_info);

		/* Restore the initial load info */
		fnvlist_free(spa->spa_load_info);
		spa->spa_load_info = loadinfo;

		spa_import_progress_remove(spa_guid(spa));
		return (load_error);
	}
}

/*
 * Pool Open/Import
 *
 * The import case is identical to an open except that the configuration is sent
 * down from userland, instead of grabbed from the configuration cache.  For the
 * case of an open, the pool configuration will exist in the
 * POOL_STATE_UNINITIALIZED state.
 *
 * The stats information (gen/count/ustats) is used to gather vdev statistics at
 * the same time open the pool, without having to keep around the spa_t in some
 * ambiguous state.
 */
static int
spa_open_common(const char *pool, spa_t **spapp, void *tag, nvlist_t *nvpolicy,
    nvlist_t **config)
{
	spa_t *spa;
	spa_load_state_t state = SPA_LOAD_OPEN;
	int error;
	int locked = B_FALSE;
	int firstopen = B_FALSE;

	*spapp = NULL;

	/*
	 * As disgusting as this is, we need to support recursive calls to this
	 * function because dsl_dir_open() is called during spa_load(), and ends
	 * up calling spa_open() again.  The real fix is to figure out how to
	 * avoid dsl_dir_open() calling this in the first place.
	 */
	if (MUTEX_NOT_HELD(&spa_namespace_lock)) {
		mutex_enter(&spa_namespace_lock);
		locked = B_TRUE;
	}

	if ((spa = spa_lookup(pool)) == NULL) {
		if (locked)
			mutex_exit(&spa_namespace_lock);
		return (SET_ERROR(ENOENT));
	}

	if (spa->spa_state == POOL_STATE_UNINITIALIZED) {
		zpool_load_policy_t policy;

		firstopen = B_TRUE;

		zpool_get_load_policy(nvpolicy ? nvpolicy : spa->spa_config,
		    &policy);
		if (policy.zlp_rewind & ZPOOL_DO_REWIND)
			state = SPA_LOAD_RECOVER;

		spa_activate(spa, spa_mode_global);

		if (state != SPA_LOAD_RECOVER)
			spa->spa_last_ubsync_txg = spa->spa_load_txg = 0;
		spa->spa_config_source = SPA_CONFIG_SRC_CACHEFILE;

		zfs_dbgmsg("spa_open_common: opening %s", pool);
		error = spa_load_best(spa, state, policy.zlp_txg,
		    policy.zlp_rewind);

		if (error == EBADF) {
			/*
			 * If vdev_validate() returns failure (indicated by
			 * EBADF), it indicates that one of the vdevs indicates
			 * that the pool has been exported or destroyed.  If
			 * this is the case, the config cache is out of sync and
			 * we should remove the pool from the namespace.
			 */
			spa_unload(spa);
			spa_deactivate(spa);
			spa_write_cachefile(spa, B_TRUE, B_TRUE);
			spa_remove(spa);
			if (locked)
				mutex_exit(&spa_namespace_lock);
			return (SET_ERROR(ENOENT));
		}

		if (error) {
			/*
			 * We can't open the pool, but we still have useful
			 * information: the state of each vdev after the
			 * attempted vdev_open().  Return this to the user.
			 */
			if (config != NULL && spa->spa_config) {
				VERIFY(nvlist_dup(spa->spa_config, config,
				    KM_SLEEP) == 0);
				VERIFY(nvlist_add_nvlist(*config,
				    ZPOOL_CONFIG_LOAD_INFO,
				    spa->spa_load_info) == 0);
			}
			spa_unload(spa);
			spa_deactivate(spa);
			spa->spa_last_open_failed = error;
			if (locked)
				mutex_exit(&spa_namespace_lock);
			*spapp = NULL;
			return (error);
		}
	}

	spa_open_ref(spa, tag);

	if (config != NULL)
		*config = spa_config_generate(spa, NULL, -1ULL, B_TRUE);

	/*
	 * If we've recovered the pool, pass back any information we
	 * gathered while doing the load.
	 */
	if (state == SPA_LOAD_RECOVER) {
		VERIFY(nvlist_add_nvlist(*config, ZPOOL_CONFIG_LOAD_INFO,
		    spa->spa_load_info) == 0);
	}

	if (locked) {
		spa->spa_last_open_failed = 0;
		spa->spa_last_ubsync_txg = 0;
		spa->spa_load_txg = 0;
		mutex_exit(&spa_namespace_lock);
	}

	if (firstopen)
		zvol_create_minors(spa, spa_name(spa), B_TRUE);

	*spapp = spa;

	return (0);
}

int
spa_open_rewind(const char *name, spa_t **spapp, void *tag, nvlist_t *policy,
    nvlist_t **config)
{
	return (spa_open_common(name, spapp, tag, policy, config));
}

int
spa_open(const char *name, spa_t **spapp, void *tag)
{
	return (spa_open_common(name, spapp, tag, NULL, NULL));
}

/*
 * Lookup the given spa_t, incrementing the inject count in the process,
 * preventing it from being exported or destroyed.
 */
spa_t *
spa_inject_addref(char *name)
{
	spa_t *spa;

	mutex_enter(&spa_namespace_lock);
	if ((spa = spa_lookup(name)) == NULL) {
		mutex_exit(&spa_namespace_lock);
		return (NULL);
	}
	spa->spa_inject_ref++;
	mutex_exit(&spa_namespace_lock);

	return (spa);
}

void
spa_inject_delref(spa_t *spa)
{
	mutex_enter(&spa_namespace_lock);
	spa->spa_inject_ref--;
	mutex_exit(&spa_namespace_lock);
}

/*
 * Add spares device information to the nvlist.
 */
static void
spa_add_spares(spa_t *spa, nvlist_t *config)
{
	nvlist_t **spares;
	uint_t i, nspares;
	nvlist_t *nvroot;
	uint64_t guid;
	vdev_stat_t *vs;
	uint_t vsc;
	uint64_t pool;

	ASSERT(spa_config_held(spa, SCL_CONFIG, RW_READER));

	if (spa->spa_spares.sav_count == 0)
		return;

	VERIFY(nvlist_lookup_nvlist(config,
	    ZPOOL_CONFIG_VDEV_TREE, &nvroot) == 0);
	VERIFY(nvlist_lookup_nvlist_array(spa->spa_spares.sav_config,
	    ZPOOL_CONFIG_SPARES, &spares, &nspares) == 0);
	if (nspares != 0) {
		VERIFY(nvlist_add_nvlist_array(nvroot,
		    ZPOOL_CONFIG_SPARES, spares, nspares) == 0);
		VERIFY(nvlist_lookup_nvlist_array(nvroot,
		    ZPOOL_CONFIG_SPARES, &spares, &nspares) == 0);

		/*
		 * Go through and find any spares which have since been
		 * repurposed as an active spare.  If this is the case, update
		 * their status appropriately.
		 */
		for (i = 0; i < nspares; i++) {
			VERIFY(nvlist_lookup_uint64(spares[i],
			    ZPOOL_CONFIG_GUID, &guid) == 0);
			if (spa_spare_exists(guid, &pool, NULL) &&
			    pool != 0ULL) {
				VERIFY(nvlist_lookup_uint64_array(
				    spares[i], ZPOOL_CONFIG_VDEV_STATS,
				    (uint64_t **)&vs, &vsc) == 0);
				vs->vs_state = VDEV_STATE_CANT_OPEN;
				vs->vs_aux = VDEV_AUX_SPARED;
			}
		}
	}
}

/*
 * Add l2cache device information to the nvlist, including vdev stats.
 */
static void
spa_add_l2cache(spa_t *spa, nvlist_t *config)
{
	nvlist_t **l2cache;
	uint_t i, j, nl2cache;
	nvlist_t *nvroot;
	uint64_t guid;
	vdev_t *vd;
	vdev_stat_t *vs;
	uint_t vsc;

	ASSERT(spa_config_held(spa, SCL_CONFIG, RW_READER));

	if (spa->spa_l2cache.sav_count == 0)
		return;

	VERIFY(nvlist_lookup_nvlist(config,
	    ZPOOL_CONFIG_VDEV_TREE, &nvroot) == 0);
	VERIFY(nvlist_lookup_nvlist_array(spa->spa_l2cache.sav_config,
	    ZPOOL_CONFIG_L2CACHE, &l2cache, &nl2cache) == 0);
	if (nl2cache != 0) {
		VERIFY(nvlist_add_nvlist_array(nvroot,
		    ZPOOL_CONFIG_L2CACHE, l2cache, nl2cache) == 0);
		VERIFY(nvlist_lookup_nvlist_array(nvroot,
		    ZPOOL_CONFIG_L2CACHE, &l2cache, &nl2cache) == 0);

		/*
		 * Update level 2 cache device stats.
		 */

		for (i = 0; i < nl2cache; i++) {
			VERIFY(nvlist_lookup_uint64(l2cache[i],
			    ZPOOL_CONFIG_GUID, &guid) == 0);

			vd = NULL;
			for (j = 0; j < spa->spa_l2cache.sav_count; j++) {
				if (guid ==
				    spa->spa_l2cache.sav_vdevs[j]->vdev_guid) {
					vd = spa->spa_l2cache.sav_vdevs[j];
					break;
				}
			}
			ASSERT(vd != NULL);

			VERIFY(nvlist_lookup_uint64_array(l2cache[i],
			    ZPOOL_CONFIG_VDEV_STATS, (uint64_t **)&vs, &vsc)
			    == 0);
			vdev_get_stats(vd, vs);
			vdev_config_generate_stats(vd, l2cache[i]);

		}
	}
}

static void
spa_feature_stats_from_disk(spa_t *spa, nvlist_t *features)
{
	zap_cursor_t zc;
	zap_attribute_t za;

	if (spa->spa_feat_for_read_obj != 0) {
		for (zap_cursor_init(&zc, spa->spa_meta_objset,
		    spa->spa_feat_for_read_obj);
		    zap_cursor_retrieve(&zc, &za) == 0;
		    zap_cursor_advance(&zc)) {
			ASSERT(za.za_integer_length == sizeof (uint64_t) &&
			    za.za_num_integers == 1);
			VERIFY0(nvlist_add_uint64(features, za.za_name,
			    za.za_first_integer));
		}
		zap_cursor_fini(&zc);
	}

	if (spa->spa_feat_for_write_obj != 0) {
		for (zap_cursor_init(&zc, spa->spa_meta_objset,
		    spa->spa_feat_for_write_obj);
		    zap_cursor_retrieve(&zc, &za) == 0;
		    zap_cursor_advance(&zc)) {
			ASSERT(za.za_integer_length == sizeof (uint64_t) &&
			    za.za_num_integers == 1);
			VERIFY0(nvlist_add_uint64(features, za.za_name,
			    za.za_first_integer));
		}
		zap_cursor_fini(&zc);
	}
}

static void
spa_feature_stats_from_cache(spa_t *spa, nvlist_t *features)
{
	int i;

	for (i = 0; i < SPA_FEATURES; i++) {
		zfeature_info_t feature = spa_feature_table[i];
		uint64_t refcount;

		if (feature_get_refcount(spa, &feature, &refcount) != 0)
			continue;

		VERIFY0(nvlist_add_uint64(features, feature.fi_guid, refcount));
	}
}

/*
 * Store a list of pool features and their reference counts in the
 * config.
 *
 * The first time this is called on a spa, allocate a new nvlist, fetch
 * the pool features and reference counts from disk, then save the list
 * in the spa. In subsequent calls on the same spa use the saved nvlist
 * and refresh its values from the cached reference counts.  This
 * ensures we don't block here on I/O on a suspended pool so 'zpool
 * clear' can resume the pool.
 */
static void
spa_add_feature_stats(spa_t *spa, nvlist_t *config)
{
	nvlist_t *features;

	ASSERT(spa_config_held(spa, SCL_CONFIG, RW_READER));

	mutex_enter(&spa->spa_feat_stats_lock);
	features = spa->spa_feat_stats;

	if (features != NULL) {
		spa_feature_stats_from_cache(spa, features);
	} else {
		VERIFY0(nvlist_alloc(&features, NV_UNIQUE_NAME, KM_SLEEP));
		spa->spa_feat_stats = features;
		spa_feature_stats_from_disk(spa, features);
	}

	VERIFY0(nvlist_add_nvlist(config, ZPOOL_CONFIG_FEATURE_STATS,
	    features));

	mutex_exit(&spa->spa_feat_stats_lock);
}

int
spa_get_stats(const char *name, nvlist_t **config,
    char *altroot, size_t buflen)
{
	int error;
	spa_t *spa;

	*config = NULL;
	error = spa_open_common(name, &spa, FTAG, NULL, config);

	if (spa != NULL) {
		/*
		 * This still leaves a window of inconsistency where the spares
		 * or l2cache devices could change and the config would be
		 * self-inconsistent.
		 */
		spa_config_enter(spa, SCL_CONFIG, FTAG, RW_READER);

		if (*config != NULL) {
			uint64_t loadtimes[2];

			loadtimes[0] = spa->spa_loaded_ts.tv_sec;
			loadtimes[1] = spa->spa_loaded_ts.tv_nsec;
			VERIFY(nvlist_add_uint64_array(*config,
			    ZPOOL_CONFIG_LOADED_TIME, loadtimes, 2) == 0);

			VERIFY(nvlist_add_uint64(*config,
			    ZPOOL_CONFIG_ERRCOUNT,
			    spa_get_errlog_size(spa)) == 0);

			if (spa_suspended(spa)) {
				VERIFY(nvlist_add_uint64(*config,
				    ZPOOL_CONFIG_SUSPENDED,
				    spa->spa_failmode) == 0);
				VERIFY(nvlist_add_uint64(*config,
				    ZPOOL_CONFIG_SUSPENDED_REASON,
				    spa->spa_suspended) == 0);
			}

			spa_add_spares(spa, *config);
			spa_add_l2cache(spa, *config);
			spa_add_feature_stats(spa, *config);
		}
	}

	/*
	 * We want to get the alternate root even for faulted pools, so we cheat
	 * and call spa_lookup() directly.
	 */
	if (altroot) {
		if (spa == NULL) {
			mutex_enter(&spa_namespace_lock);
			spa = spa_lookup(name);
			if (spa)
				spa_altroot(spa, altroot, buflen);
			else
				altroot[0] = '\0';
			spa = NULL;
			mutex_exit(&spa_namespace_lock);
		} else {
			spa_altroot(spa, altroot, buflen);
		}
	}

	if (spa != NULL) {
		spa_config_exit(spa, SCL_CONFIG, FTAG);
		spa_close(spa, FTAG);
	}

	return (error);
}

/*
 * Validate that the auxiliary device array is well formed.  We must have an
 * array of nvlists, each which describes a valid leaf vdev.  If this is an
 * import (mode is VDEV_ALLOC_SPARE), then we allow corrupted spares to be
 * specified, as long as they are well-formed.
 */
static int
spa_validate_aux_devs(spa_t *spa, nvlist_t *nvroot, uint64_t crtxg, int mode,
    spa_aux_vdev_t *sav, const char *config, uint64_t version,
    vdev_labeltype_t label)
{
	nvlist_t **dev;
	uint_t i, ndev;
	vdev_t *vd;
	int error;

	ASSERT(spa_config_held(spa, SCL_ALL, RW_WRITER) == SCL_ALL);

	/*
	 * It's acceptable to have no devs specified.
	 */
	if (nvlist_lookup_nvlist_array(nvroot, config, &dev, &ndev) != 0)
		return (0);

	if (ndev == 0)
		return (SET_ERROR(EINVAL));

	/*
	 * Make sure the pool is formatted with a version that supports this
	 * device type.
	 */
	if (spa_version(spa) < version)
		return (SET_ERROR(ENOTSUP));

	/*
	 * Set the pending device list so we correctly handle device in-use
	 * checking.
	 */
	sav->sav_pending = dev;
	sav->sav_npending = ndev;

	for (i = 0; i < ndev; i++) {
		if ((error = spa_config_parse(spa, &vd, dev[i], NULL, 0,
		    mode)) != 0)
			goto out;

		if (!vd->vdev_ops->vdev_op_leaf) {
			vdev_free(vd);
			error = SET_ERROR(EINVAL);
			goto out;
		}

		vd->vdev_top = vd;

		if ((error = vdev_open(vd)) == 0 &&
		    (error = vdev_label_init(vd, crtxg, label)) == 0) {
			VERIFY(nvlist_add_uint64(dev[i], ZPOOL_CONFIG_GUID,
			    vd->vdev_guid) == 0);
		}

		vdev_free(vd);

		if (error &&
		    (mode != VDEV_ALLOC_SPARE && mode != VDEV_ALLOC_L2CACHE))
			goto out;
		else
			error = 0;
	}

out:
	sav->sav_pending = NULL;
	sav->sav_npending = 0;
	return (error);
}

static int
spa_validate_aux(spa_t *spa, nvlist_t *nvroot, uint64_t crtxg, int mode)
{
	int error;

	ASSERT(spa_config_held(spa, SCL_ALL, RW_WRITER) == SCL_ALL);

	if ((error = spa_validate_aux_devs(spa, nvroot, crtxg, mode,
	    &spa->spa_spares, ZPOOL_CONFIG_SPARES, SPA_VERSION_SPARES,
	    VDEV_LABEL_SPARE)) != 0) {
		return (error);
	}

	return (spa_validate_aux_devs(spa, nvroot, crtxg, mode,
	    &spa->spa_l2cache, ZPOOL_CONFIG_L2CACHE, SPA_VERSION_L2CACHE,
	    VDEV_LABEL_L2CACHE));
}

static void
spa_set_aux_vdevs(spa_aux_vdev_t *sav, nvlist_t **devs, int ndevs,
    const char *config)
{
	int i;

	if (sav->sav_config != NULL) {
		nvlist_t **olddevs;
		uint_t oldndevs;
		nvlist_t **newdevs;

		/*
		 * Generate new dev list by concatenating with the
		 * current dev list.
		 */
		VERIFY(nvlist_lookup_nvlist_array(sav->sav_config, config,
		    &olddevs, &oldndevs) == 0);

		newdevs = kmem_alloc(sizeof (void *) *
		    (ndevs + oldndevs), KM_SLEEP);
		for (i = 0; i < oldndevs; i++)
			VERIFY(nvlist_dup(olddevs[i], &newdevs[i],
			    KM_SLEEP) == 0);
		for (i = 0; i < ndevs; i++)
			VERIFY(nvlist_dup(devs[i], &newdevs[i + oldndevs],
			    KM_SLEEP) == 0);

		VERIFY(nvlist_remove(sav->sav_config, config,
		    DATA_TYPE_NVLIST_ARRAY) == 0);

		VERIFY(nvlist_add_nvlist_array(sav->sav_config,
		    config, newdevs, ndevs + oldndevs) == 0);
		for (i = 0; i < oldndevs + ndevs; i++)
			nvlist_free(newdevs[i]);
		kmem_free(newdevs, (oldndevs + ndevs) * sizeof (void *));
	} else {
		/*
		 * Generate a new dev list.
		 */
		VERIFY(nvlist_alloc(&sav->sav_config, NV_UNIQUE_NAME,
		    KM_SLEEP) == 0);
		VERIFY(nvlist_add_nvlist_array(sav->sav_config, config,
		    devs, ndevs) == 0);
	}
}

/*
 * Stop and drop level 2 ARC devices
 */
void
spa_l2cache_drop(spa_t *spa)
{
	vdev_t *vd;
	int i;
	spa_aux_vdev_t *sav = &spa->spa_l2cache;

	for (i = 0; i < sav->sav_count; i++) {
		uint64_t pool;

		vd = sav->sav_vdevs[i];
		ASSERT(vd != NULL);

		if (spa_l2cache_exists(vd->vdev_guid, &pool) &&
		    pool != 0ULL && l2arc_vdev_present(vd))
			l2arc_remove_vdev(vd);
	}
}

/*
 * Verify encryption parameters for spa creation. If we are encrypting, we must
 * have the encryption feature flag enabled.
 */
static int
spa_create_check_encryption_params(dsl_crypto_params_t *dcp,
    boolean_t has_encryption)
{
	if (dcp->cp_crypt != ZIO_CRYPT_OFF &&
	    dcp->cp_crypt != ZIO_CRYPT_INHERIT &&
	    !has_encryption)
		return (SET_ERROR(ENOTSUP));

	return (dmu_objset_create_crypt_check(NULL, dcp, NULL));
}

/*
 * Pool Creation
 */
int
spa_create(const char *pool, nvlist_t *nvroot, nvlist_t *props,
    nvlist_t *zplprops, dsl_crypto_params_t *dcp)
{
	spa_t *spa;
	char *altroot = NULL;
	vdev_t *rvd;
	dsl_pool_t *dp;
	dmu_tx_t *tx;
	int error = 0;
	uint64_t txg = TXG_INITIAL;
	nvlist_t **spares, **l2cache;
	uint_t nspares, nl2cache;
	uint64_t version, obj;
	boolean_t has_features;
	boolean_t has_encryption;
	spa_feature_t feat;
	char *feat_name;
	char *poolname;
	nvlist_t *nvl;

	if (props == NULL ||
	    nvlist_lookup_string(props, "tname", &poolname) != 0)
		poolname = (char *)pool;

	/*
	 * If this pool already exists, return failure.
	 */
	mutex_enter(&spa_namespace_lock);
	if (spa_lookup(poolname) != NULL) {
		mutex_exit(&spa_namespace_lock);
		return (SET_ERROR(EEXIST));
	}

	/*
	 * Allocate a new spa_t structure.
	 */
	nvl = fnvlist_alloc();
	fnvlist_add_string(nvl, ZPOOL_CONFIG_POOL_NAME, pool);
	(void) nvlist_lookup_string(props,
	    zpool_prop_to_name(ZPOOL_PROP_ALTROOT), &altroot);
	spa = spa_add(poolname, nvl, altroot);
	fnvlist_free(nvl);
	spa_activate(spa, spa_mode_global);

	if (props && (error = spa_prop_validate(spa, props))) {
		spa_deactivate(spa);
		spa_remove(spa);
		mutex_exit(&spa_namespace_lock);
		return (error);
	}

	/*
	 * Temporary pool names should never be written to disk.
	 */
	if (poolname != pool)
		spa->spa_import_flags |= ZFS_IMPORT_TEMP_NAME;

	has_features = B_FALSE;
	has_encryption = B_FALSE;
	for (nvpair_t *elem = nvlist_next_nvpair(props, NULL);
	    elem != NULL; elem = nvlist_next_nvpair(props, elem)) {
		if (zpool_prop_feature(nvpair_name(elem))) {
			has_features = B_TRUE;

			feat_name = strchr(nvpair_name(elem), '@') + 1;
			VERIFY0(zfeature_lookup_name(feat_name, &feat));
			if (feat == SPA_FEATURE_ENCRYPTION)
				has_encryption = B_TRUE;
		}
	}

	/* verify encryption params, if they were provided */
	if (dcp != NULL) {
		error = spa_create_check_encryption_params(dcp, has_encryption);
		if (error != 0) {
			spa_deactivate(spa);
			spa_remove(spa);
			mutex_exit(&spa_namespace_lock);
			return (error);
		}
	}

	if (has_features || nvlist_lookup_uint64(props,
	    zpool_prop_to_name(ZPOOL_PROP_VERSION), &version) != 0) {
		version = SPA_VERSION;
	}
	ASSERT(SPA_VERSION_IS_SUPPORTED(version));

	spa->spa_first_txg = txg;
	spa->spa_uberblock.ub_txg = txg - 1;
	spa->spa_uberblock.ub_version = version;
	spa->spa_ubsync = spa->spa_uberblock;
	spa->spa_load_state = SPA_LOAD_CREATE;
	spa->spa_removing_phys.sr_state = DSS_NONE;
	spa->spa_removing_phys.sr_removing_vdev = -1;
	spa->spa_removing_phys.sr_prev_indirect_vdev = -1;
	spa->spa_indirect_vdevs_loaded = B_TRUE;

	/*
	 * Create "The Godfather" zio to hold all async IOs
	 */
	spa->spa_async_zio_root = kmem_alloc(max_ncpus * sizeof (void *),
	    KM_SLEEP);
	for (int i = 0; i < max_ncpus; i++) {
		spa->spa_async_zio_root[i] = zio_root(spa, NULL, NULL,
		    ZIO_FLAG_CANFAIL | ZIO_FLAG_SPECULATIVE |
		    ZIO_FLAG_GODFATHER);
	}

	/*
	 * Create the root vdev.
	 */
	spa_config_enter(spa, SCL_ALL, FTAG, RW_WRITER);

	error = spa_config_parse(spa, &rvd, nvroot, NULL, 0, VDEV_ALLOC_ADD);

	ASSERT(error != 0 || rvd != NULL);
	ASSERT(error != 0 || spa->spa_root_vdev == rvd);

	if (error == 0 && !zfs_allocatable_devs(nvroot))
		error = SET_ERROR(EINVAL);

	if (error == 0 &&
	    (error = vdev_create(rvd, txg, B_FALSE)) == 0 &&
	    (error = spa_validate_aux(spa, nvroot, txg,
	    VDEV_ALLOC_ADD)) == 0) {
		/*
		 * instantiate the metaslab groups (this will dirty the vdevs)
		 * we can no longer error exit past this point
		 */
		for (int c = 0; error == 0 && c < rvd->vdev_children; c++) {
			vdev_t *vd = rvd->vdev_child[c];

			vdev_metaslab_set_size(vd);
			vdev_expand(vd, txg);
		}
	}

	spa_config_exit(spa, SCL_ALL, FTAG);

	if (error != 0) {
		spa_unload(spa);
		spa_deactivate(spa);
		spa_remove(spa);
		mutex_exit(&spa_namespace_lock);
		return (error);
	}

	/*
	 * Get the list of spares, if specified.
	 */
	if (nvlist_lookup_nvlist_array(nvroot, ZPOOL_CONFIG_SPARES,
	    &spares, &nspares) == 0) {
		VERIFY(nvlist_alloc(&spa->spa_spares.sav_config, NV_UNIQUE_NAME,
		    KM_SLEEP) == 0);
		VERIFY(nvlist_add_nvlist_array(spa->spa_spares.sav_config,
		    ZPOOL_CONFIG_SPARES, spares, nspares) == 0);
		spa_config_enter(spa, SCL_ALL, FTAG, RW_WRITER);
		spa_load_spares(spa);
		spa_config_exit(spa, SCL_ALL, FTAG);
		spa->spa_spares.sav_sync = B_TRUE;
	}

	/*
	 * Get the list of level 2 cache devices, if specified.
	 */
	if (nvlist_lookup_nvlist_array(nvroot, ZPOOL_CONFIG_L2CACHE,
	    &l2cache, &nl2cache) == 0) {
		VERIFY(nvlist_alloc(&spa->spa_l2cache.sav_config,
		    NV_UNIQUE_NAME, KM_SLEEP) == 0);
		VERIFY(nvlist_add_nvlist_array(spa->spa_l2cache.sav_config,
		    ZPOOL_CONFIG_L2CACHE, l2cache, nl2cache) == 0);
		spa_config_enter(spa, SCL_ALL, FTAG, RW_WRITER);
		spa_load_l2cache(spa);
		spa_config_exit(spa, SCL_ALL, FTAG);
		spa->spa_l2cache.sav_sync = B_TRUE;
	}

	spa->spa_is_initializing = B_TRUE;
	spa->spa_dsl_pool = dp = dsl_pool_create(spa, zplprops, dcp, txg);
	spa->spa_is_initializing = B_FALSE;

	/*
	 * Create DDTs (dedup tables).
	 */
	ddt_create(spa);

	spa_update_dspace(spa);

	tx = dmu_tx_create_assigned(dp, txg);

	/*
	 * Create the pool's history object.
	 */
	if (version >= SPA_VERSION_ZPOOL_HISTORY && !spa->spa_history)
		spa_history_create_obj(spa, tx);

	spa_event_notify(spa, NULL, NULL, ESC_ZFS_POOL_CREATE);
	spa_history_log_version(spa, "create", tx);

	/*
	 * Create the pool config object.
	 */
	spa->spa_config_object = dmu_object_alloc(spa->spa_meta_objset,
	    DMU_OT_PACKED_NVLIST, SPA_CONFIG_BLOCKSIZE,
	    DMU_OT_PACKED_NVLIST_SIZE, sizeof (uint64_t), tx);

	if (zap_add(spa->spa_meta_objset,
	    DMU_POOL_DIRECTORY_OBJECT, DMU_POOL_CONFIG,
	    sizeof (uint64_t), 1, &spa->spa_config_object, tx) != 0) {
		cmn_err(CE_PANIC, "failed to add pool config");
	}

	if (zap_add(spa->spa_meta_objset,
	    DMU_POOL_DIRECTORY_OBJECT, DMU_POOL_CREATION_VERSION,
	    sizeof (uint64_t), 1, &version, tx) != 0) {
		cmn_err(CE_PANIC, "failed to add pool version");
	}

	/* Newly created pools with the right version are always deflated. */
	if (version >= SPA_VERSION_RAIDZ_DEFLATE) {
		spa->spa_deflate = TRUE;
		if (zap_add(spa->spa_meta_objset,
		    DMU_POOL_DIRECTORY_OBJECT, DMU_POOL_DEFLATE,
		    sizeof (uint64_t), 1, &spa->spa_deflate, tx) != 0) {
			cmn_err(CE_PANIC, "failed to add deflate");
		}
	}

	/*
	 * Create the deferred-free bpobj.  Turn off compression
	 * because sync-to-convergence takes longer if the blocksize
	 * keeps changing.
	 */
	obj = bpobj_alloc(spa->spa_meta_objset, 1 << 14, tx);
	dmu_object_set_compress(spa->spa_meta_objset, obj,
	    ZIO_COMPRESS_OFF, tx);
	if (zap_add(spa->spa_meta_objset,
	    DMU_POOL_DIRECTORY_OBJECT, DMU_POOL_SYNC_BPOBJ,
	    sizeof (uint64_t), 1, &obj, tx) != 0) {
		cmn_err(CE_PANIC, "failed to add bpobj");
	}
	VERIFY3U(0, ==, bpobj_open(&spa->spa_deferred_bpobj,
	    spa->spa_meta_objset, obj));

	/*
	 * Generate some random noise for salted checksums to operate on.
	 */
	(void) random_get_pseudo_bytes(spa->spa_cksum_salt.zcs_bytes,
	    sizeof (spa->spa_cksum_salt.zcs_bytes));

	/*
	 * Set pool properties.
	 */
	spa->spa_bootfs = zpool_prop_default_numeric(ZPOOL_PROP_BOOTFS);
	spa->spa_delegation = zpool_prop_default_numeric(ZPOOL_PROP_DELEGATION);
	spa->spa_failmode = zpool_prop_default_numeric(ZPOOL_PROP_FAILUREMODE);
	spa->spa_autoexpand = zpool_prop_default_numeric(ZPOOL_PROP_AUTOEXPAND);
	spa->spa_multihost = zpool_prop_default_numeric(ZPOOL_PROP_MULTIHOST);
	spa->spa_autotrim = zpool_prop_default_numeric(ZPOOL_PROP_AUTOTRIM);

	if (props != NULL) {
		spa_configfile_set(spa, props, B_FALSE);
		spa_sync_props(props, tx);
	}

	dmu_tx_commit(tx);

	spa->spa_sync_on = B_TRUE;
	txg_sync_start(dp);
	mmp_thread_start(spa);
	txg_wait_synced(dp, txg);

	spa_spawn_aux_threads(spa);

	spa_write_cachefile(spa, B_FALSE, B_TRUE);

	/*
	 * Don't count references from objsets that are already closed
	 * and are making their way through the eviction process.
	 */
	spa_evicting_os_wait(spa);
	spa->spa_minref = zfs_refcount_count(&spa->spa_refcount);
	spa->spa_load_state = SPA_LOAD_NONE;

	mutex_exit(&spa_namespace_lock);

	return (0);
}

/*
 * Import a non-root pool into the system.
 */
int
spa_import(char *pool, nvlist_t *config, nvlist_t *props, uint64_t flags)
{
	spa_t *spa;
	char *altroot = NULL;
	spa_load_state_t state = SPA_LOAD_IMPORT;
	zpool_load_policy_t policy;
	uint64_t mode = spa_mode_global;
	uint64_t readonly = B_FALSE;
	int error;
	nvlist_t *nvroot;
	nvlist_t **spares, **l2cache;
	uint_t nspares, nl2cache;

	/*
	 * If a pool with this name exists, return failure.
	 */
	mutex_enter(&spa_namespace_lock);
	if (spa_lookup(pool) != NULL) {
		mutex_exit(&spa_namespace_lock);
		return (SET_ERROR(EEXIST));
	}

	/*
	 * Create and initialize the spa structure.
	 */
	(void) nvlist_lookup_string(props,
	    zpool_prop_to_name(ZPOOL_PROP_ALTROOT), &altroot);
	(void) nvlist_lookup_uint64(props,
	    zpool_prop_to_name(ZPOOL_PROP_READONLY), &readonly);
	if (readonly)
		mode = FREAD;
	spa = spa_add(pool, config, altroot);
	spa->spa_import_flags = flags;

	/*
	 * Verbatim import - Take a pool and insert it into the namespace
	 * as if it had been loaded at boot.
	 */
	if (spa->spa_import_flags & ZFS_IMPORT_VERBATIM) {
		if (props != NULL)
			spa_configfile_set(spa, props, B_FALSE);

		spa_write_cachefile(spa, B_FALSE, B_TRUE);
		spa_event_notify(spa, NULL, NULL, ESC_ZFS_POOL_IMPORT);
		zfs_dbgmsg("spa_import: verbatim import of %s", pool);
		mutex_exit(&spa_namespace_lock);
		return (0);
	}

	spa_activate(spa, mode);

	/*
	 * Don't start async tasks until we know everything is healthy.
	 */
	spa_async_suspend(spa);

	zpool_get_load_policy(config, &policy);
	if (policy.zlp_rewind & ZPOOL_DO_REWIND)
		state = SPA_LOAD_RECOVER;

	spa->spa_config_source = SPA_CONFIG_SRC_TRYIMPORT;

	if (state != SPA_LOAD_RECOVER) {
		spa->spa_last_ubsync_txg = spa->spa_load_txg = 0;
		zfs_dbgmsg("spa_import: importing %s", pool);
	} else {
		zfs_dbgmsg("spa_import: importing %s, max_txg=%lld "
		    "(RECOVERY MODE)", pool, (longlong_t)policy.zlp_txg);
	}
	error = spa_load_best(spa, state, policy.zlp_txg, policy.zlp_rewind);

	/*
	 * Propagate anything learned while loading the pool and pass it
	 * back to caller (i.e. rewind info, missing devices, etc).
	 */
	VERIFY(nvlist_add_nvlist(config, ZPOOL_CONFIG_LOAD_INFO,
	    spa->spa_load_info) == 0);

	spa_config_enter(spa, SCL_ALL, FTAG, RW_WRITER);
	/*
	 * Toss any existing sparelist, as it doesn't have any validity
	 * anymore, and conflicts with spa_has_spare().
	 */
	if (spa->spa_spares.sav_config) {
		nvlist_free(spa->spa_spares.sav_config);
		spa->spa_spares.sav_config = NULL;
		spa_load_spares(spa);
	}
	if (spa->spa_l2cache.sav_config) {
		nvlist_free(spa->spa_l2cache.sav_config);
		spa->spa_l2cache.sav_config = NULL;
		spa_load_l2cache(spa);
	}

	VERIFY(nvlist_lookup_nvlist(config, ZPOOL_CONFIG_VDEV_TREE,
	    &nvroot) == 0);
	spa_config_exit(spa, SCL_ALL, FTAG);

	if (props != NULL)
		spa_configfile_set(spa, props, B_FALSE);

	if (error != 0 || (props && spa_writeable(spa) &&
	    (error = spa_prop_set(spa, props)))) {
		spa_unload(spa);
		spa_deactivate(spa);
		spa_remove(spa);
		mutex_exit(&spa_namespace_lock);
		return (error);
	}

	spa_async_resume(spa);

	/*
	 * Override any spares and level 2 cache devices as specified by
	 * the user, as these may have correct device names/devids, etc.
	 */
	if (nvlist_lookup_nvlist_array(nvroot, ZPOOL_CONFIG_SPARES,
	    &spares, &nspares) == 0) {
		if (spa->spa_spares.sav_config)
			VERIFY(nvlist_remove(spa->spa_spares.sav_config,
			    ZPOOL_CONFIG_SPARES, DATA_TYPE_NVLIST_ARRAY) == 0);
		else
			VERIFY(nvlist_alloc(&spa->spa_spares.sav_config,
			    NV_UNIQUE_NAME, KM_SLEEP) == 0);
		VERIFY(nvlist_add_nvlist_array(spa->spa_spares.sav_config,
		    ZPOOL_CONFIG_SPARES, spares, nspares) == 0);
		spa_config_enter(spa, SCL_ALL, FTAG, RW_WRITER);
		spa_load_spares(spa);
		spa_config_exit(spa, SCL_ALL, FTAG);
		spa->spa_spares.sav_sync = B_TRUE;
	}
	if (nvlist_lookup_nvlist_array(nvroot, ZPOOL_CONFIG_L2CACHE,
	    &l2cache, &nl2cache) == 0) {
		if (spa->spa_l2cache.sav_config)
			VERIFY(nvlist_remove(spa->spa_l2cache.sav_config,
			    ZPOOL_CONFIG_L2CACHE, DATA_TYPE_NVLIST_ARRAY) == 0);
		else
			VERIFY(nvlist_alloc(&spa->spa_l2cache.sav_config,
			    NV_UNIQUE_NAME, KM_SLEEP) == 0);
		VERIFY(nvlist_add_nvlist_array(spa->spa_l2cache.sav_config,
		    ZPOOL_CONFIG_L2CACHE, l2cache, nl2cache) == 0);
		spa_config_enter(spa, SCL_ALL, FTAG, RW_WRITER);
		spa_load_l2cache(spa);
		spa_config_exit(spa, SCL_ALL, FTAG);
		spa->spa_l2cache.sav_sync = B_TRUE;
	}

	/*
	 * Check for any removed devices.
	 */
	if (spa->spa_autoreplace) {
		spa_aux_check_removed(&spa->spa_spares);
		spa_aux_check_removed(&spa->spa_l2cache);
	}

	if (spa_writeable(spa)) {
		/*
		 * Update the config cache to include the newly-imported pool.
		 */
		spa_config_update(spa, SPA_CONFIG_UPDATE_POOL);
	}

	/*
	 * It's possible that the pool was expanded while it was exported.
	 * We kick off an async task to handle this for us.
	 */
	spa_async_request(spa, SPA_ASYNC_AUTOEXPAND);

	spa_history_log_version(spa, "import", NULL);

	spa_event_notify(spa, NULL, NULL, ESC_ZFS_POOL_IMPORT);

	zvol_create_minors(spa, pool, B_TRUE);

	mutex_exit(&spa_namespace_lock);

	return (0);
}

nvlist_t *
spa_tryimport(nvlist_t *tryconfig)
{
	nvlist_t *config = NULL;
	char *poolname, *cachefile;
	spa_t *spa;
	uint64_t state;
	int error;
	zpool_load_policy_t policy;

	if (nvlist_lookup_string(tryconfig, ZPOOL_CONFIG_POOL_NAME, &poolname))
		return (NULL);

	if (nvlist_lookup_uint64(tryconfig, ZPOOL_CONFIG_POOL_STATE, &state))
		return (NULL);

	/*
	 * Create and initialize the spa structure.
	 */
	mutex_enter(&spa_namespace_lock);
	spa = spa_add(TRYIMPORT_NAME, tryconfig, NULL);
	spa_activate(spa, FREAD);

	/*
	 * Rewind pool if a max txg was provided.
	 */
	zpool_get_load_policy(spa->spa_config, &policy);
	if (policy.zlp_txg != UINT64_MAX) {
		spa->spa_load_max_txg = policy.zlp_txg;
		spa->spa_extreme_rewind = B_TRUE;
		zfs_dbgmsg("spa_tryimport: importing %s, max_txg=%lld",
		    poolname, (longlong_t)policy.zlp_txg);
	} else {
		zfs_dbgmsg("spa_tryimport: importing %s", poolname);
	}

	if (nvlist_lookup_string(tryconfig, ZPOOL_CONFIG_CACHEFILE, &cachefile)
	    == 0) {
		zfs_dbgmsg("spa_tryimport: using cachefile '%s'", cachefile);
		spa->spa_config_source = SPA_CONFIG_SRC_CACHEFILE;
	} else {
		spa->spa_config_source = SPA_CONFIG_SRC_SCAN;
	}

	error = spa_load(spa, SPA_LOAD_TRYIMPORT, SPA_IMPORT_EXISTING);

	/*
	 * If 'tryconfig' was at least parsable, return the current config.
	 */
	if (spa->spa_root_vdev != NULL) {
		config = spa_config_generate(spa, NULL, -1ULL, B_TRUE);
		VERIFY(nvlist_add_string(config, ZPOOL_CONFIG_POOL_NAME,
		    poolname) == 0);
		VERIFY(nvlist_add_uint64(config, ZPOOL_CONFIG_POOL_STATE,
		    state) == 0);
		VERIFY(nvlist_add_uint64(config, ZPOOL_CONFIG_TIMESTAMP,
		    spa->spa_uberblock.ub_timestamp) == 0);
		VERIFY(nvlist_add_nvlist(config, ZPOOL_CONFIG_LOAD_INFO,
		    spa->spa_load_info) == 0);
		VERIFY(nvlist_add_uint64(config, ZPOOL_CONFIG_ERRATA,
		    spa->spa_errata) == 0);

		/*
		 * If the bootfs property exists on this pool then we
		 * copy it out so that external consumers can tell which
		 * pools are bootable.
		 */
		if ((!error || error == EEXIST) && spa->spa_bootfs) {
			char *tmpname = kmem_alloc(MAXPATHLEN, KM_SLEEP);

			/*
			 * We have to play games with the name since the
			 * pool was opened as TRYIMPORT_NAME.
			 */
			if (dsl_dsobj_to_dsname(spa_name(spa),
			    spa->spa_bootfs, tmpname) == 0) {
				char *cp;
				char *dsname;

				dsname = kmem_alloc(MAXPATHLEN, KM_SLEEP);

				cp = strchr(tmpname, '/');
				if (cp == NULL) {
					(void) strlcpy(dsname, tmpname,
					    MAXPATHLEN);
				} else {
					(void) snprintf(dsname, MAXPATHLEN,
					    "%s/%s", poolname, ++cp);
				}
				VERIFY(nvlist_add_string(config,
				    ZPOOL_CONFIG_BOOTFS, dsname) == 0);
				kmem_free(dsname, MAXPATHLEN);
			}
			kmem_free(tmpname, MAXPATHLEN);
		}

		/*
		 * Add the list of hot spares and level 2 cache devices.
		 */
		spa_config_enter(spa, SCL_CONFIG, FTAG, RW_READER);
		spa_add_spares(spa, config);
		spa_add_l2cache(spa, config);
		spa_config_exit(spa, SCL_CONFIG, FTAG);
	}

	spa_unload(spa);
	spa_deactivate(spa);
	spa_remove(spa);
	mutex_exit(&spa_namespace_lock);

	return (config);
}

/*
 * Pool export/destroy
 *
 * The act of destroying or exporting a pool is very simple.  We make sure there
 * is no more pending I/O and any references to the pool are gone.  Then, we
 * update the pool state and sync all the labels to disk, removing the
 * configuration from the cache afterwards. If the 'hardforce' flag is set, then
 * we don't sync the labels or remove the configuration cache.
 */
static int
spa_export_common(char *pool, int new_state, nvlist_t **oldconfig,
    boolean_t force, boolean_t hardforce)
{
	spa_t *spa;

	if (oldconfig)
		*oldconfig = NULL;

	if (!(spa_mode_global & FWRITE))
		return (SET_ERROR(EROFS));

	mutex_enter(&spa_namespace_lock);
	if ((spa = spa_lookup(pool)) == NULL) {
		mutex_exit(&spa_namespace_lock);
		return (SET_ERROR(ENOENT));
	}

	/*
	 * Put a hold on the pool, drop the namespace lock, stop async tasks,
	 * reacquire the namespace lock, and see if we can export.
	 */
	spa_open_ref(spa, FTAG);
	mutex_exit(&spa_namespace_lock);
	spa_async_suspend(spa);
	if (spa->spa_zvol_taskq) {
		zvol_remove_minors(spa, spa_name(spa), B_TRUE);
		taskq_wait(spa->spa_zvol_taskq);
	}
	mutex_enter(&spa_namespace_lock);
	spa_close(spa, FTAG);

	if (spa->spa_state == POOL_STATE_UNINITIALIZED)
		goto export_spa;
	/*
	 * The pool will be in core if it's openable, in which case we can
	 * modify its state.  Objsets may be open only because they're dirty,
	 * so we have to force it to sync before checking spa_refcnt.
	 */
	if (spa->spa_sync_on) {
		txg_wait_synced(spa->spa_dsl_pool, 0);
		spa_evicting_os_wait(spa);
	}

	/*
	 * A pool cannot be exported or destroyed if there are active
	 * references.  If we are resetting a pool, allow references by
	 * fault injection handlers.
	 */
	if (!spa_refcount_zero(spa) ||
	    (spa->spa_inject_ref != 0 &&
	    new_state != POOL_STATE_UNINITIALIZED)) {
		spa_async_resume(spa);
		mutex_exit(&spa_namespace_lock);
		return (SET_ERROR(EBUSY));
	}

	if (spa->spa_sync_on) {
		/*
		 * A pool cannot be exported if it has an active shared spare.
		 * This is to prevent other pools stealing the active spare
		 * from an exported pool. At user's own will, such pool can
		 * be forcedly exported.
		 */
		if (!force && new_state == POOL_STATE_EXPORTED &&
		    spa_has_active_shared_spare(spa)) {
			spa_async_resume(spa);
			mutex_exit(&spa_namespace_lock);
			return (SET_ERROR(EXDEV));
		}

		/*
		 * We're about to export or destroy this pool. Make sure
		 * we stop all initialization and trim activity here before
		 * we set the spa_final_txg. This will ensure that all
		 * dirty data resulting from the initialization is
		 * committed to disk before we unload the pool.
		 */
		if (spa->spa_root_vdev != NULL) {
			vdev_t *rvd = spa->spa_root_vdev;
			vdev_initialize_stop_all(rvd, VDEV_INITIALIZE_ACTIVE);
			vdev_trim_stop_all(rvd, VDEV_TRIM_ACTIVE);
			vdev_autotrim_stop_all(spa);
		}

		/*
		 * We want this to be reflected on every label,
		 * so mark them all dirty.  spa_unload() will do the
		 * final sync that pushes these changes out.
		 */
		if (new_state != POOL_STATE_UNINITIALIZED && !hardforce) {
			spa_config_enter(spa, SCL_ALL, FTAG, RW_WRITER);
			spa->spa_state = new_state;
			spa->spa_final_txg = spa_last_synced_txg(spa) +
			    TXG_DEFER_SIZE + 1;
			vdev_config_dirty(spa->spa_root_vdev);
			spa_config_exit(spa, SCL_ALL, FTAG);
		}
	}

export_spa:
	if (new_state == POOL_STATE_DESTROYED)
		spa_event_notify(spa, NULL, NULL, ESC_ZFS_POOL_DESTROY);
	else if (new_state == POOL_STATE_EXPORTED)
		spa_event_notify(spa, NULL, NULL, ESC_ZFS_POOL_EXPORT);

	if (spa->spa_state != POOL_STATE_UNINITIALIZED) {
		spa_unload(spa);
		spa_deactivate(spa);
	}

	if (oldconfig && spa->spa_config)
		VERIFY(nvlist_dup(spa->spa_config, oldconfig, 0) == 0);

	if (new_state != POOL_STATE_UNINITIALIZED) {
		if (!hardforce)
			spa_write_cachefile(spa, B_TRUE, B_TRUE);
		spa_remove(spa);
	}
	mutex_exit(&spa_namespace_lock);

	return (0);
}

/*
 * Destroy a storage pool.
 */
int
spa_destroy(char *pool)
{
	return (spa_export_common(pool, POOL_STATE_DESTROYED, NULL,
	    B_FALSE, B_FALSE));
}

/*
 * Export a storage pool.
 */
int
spa_export(char *pool, nvlist_t **oldconfig, boolean_t force,
    boolean_t hardforce)
{
	return (spa_export_common(pool, POOL_STATE_EXPORTED, oldconfig,
	    force, hardforce));
}

/*
 * Similar to spa_export(), this unloads the spa_t without actually removing it
 * from the namespace in any way.
 */
int
spa_reset(char *pool)
{
	return (spa_export_common(pool, POOL_STATE_UNINITIALIZED, NULL,
	    B_FALSE, B_FALSE));
}

/*
 * ==========================================================================
 * Device manipulation
 * ==========================================================================
 */

/*
 * Add a device to a storage pool.
 */
int
spa_vdev_add(spa_t *spa, nvlist_t *nvroot)
{
	uint64_t txg, id;
	int error;
	vdev_t *rvd = spa->spa_root_vdev;
	vdev_t *vd, *tvd;
	nvlist_t **spares, **l2cache;
	uint_t nspares, nl2cache;

	ASSERT(spa_writeable(spa));

	txg = spa_vdev_enter(spa);

	if ((error = spa_config_parse(spa, &vd, nvroot, NULL, 0,
	    VDEV_ALLOC_ADD)) != 0)
		return (spa_vdev_exit(spa, NULL, txg, error));

	spa->spa_pending_vdev = vd;	/* spa_vdev_exit() will clear this */

	if (nvlist_lookup_nvlist_array(nvroot, ZPOOL_CONFIG_SPARES, &spares,
	    &nspares) != 0)
		nspares = 0;

	if (nvlist_lookup_nvlist_array(nvroot, ZPOOL_CONFIG_L2CACHE, &l2cache,
	    &nl2cache) != 0)
		nl2cache = 0;

	if (vd->vdev_children == 0 && nspares == 0 && nl2cache == 0)
		return (spa_vdev_exit(spa, vd, txg, EINVAL));

	if (vd->vdev_children != 0 &&
	    (error = vdev_create(vd, txg, B_FALSE)) != 0)
		return (spa_vdev_exit(spa, vd, txg, error));

	/*
	 * We must validate the spares and l2cache devices after checking the
	 * children.  Otherwise, vdev_inuse() will blindly overwrite the spare.
	 */
	if ((error = spa_validate_aux(spa, nvroot, txg, VDEV_ALLOC_ADD)) != 0)
		return (spa_vdev_exit(spa, vd, txg, error));

	/*
	 * If we are in the middle of a device removal, we can only add
	 * devices which match the existing devices in the pool.
	 * If we are in the middle of a removal, or have some indirect
	 * vdevs, we can not add raidz toplevels.
	 */
	if (spa->spa_vdev_removal != NULL ||
	    spa->spa_removing_phys.sr_prev_indirect_vdev != -1) {
		for (int c = 0; c < vd->vdev_children; c++) {
			tvd = vd->vdev_child[c];
			if (spa->spa_vdev_removal != NULL &&
			    tvd->vdev_ashift != spa->spa_max_ashift) {
				return (spa_vdev_exit(spa, vd, txg, EINVAL));
			}
			/* Fail if top level vdev is raidz */
			if (tvd->vdev_ops == &vdev_raidz_ops) {
				return (spa_vdev_exit(spa, vd, txg, EINVAL));
			}
			/*
			 * Need the top level mirror to be
			 * a mirror of leaf vdevs only
			 */
			if (tvd->vdev_ops == &vdev_mirror_ops) {
				for (uint64_t cid = 0;
				    cid < tvd->vdev_children; cid++) {
					vdev_t *cvd = tvd->vdev_child[cid];
					if (!cvd->vdev_ops->vdev_op_leaf) {
						return (spa_vdev_exit(spa, vd,
						    txg, EINVAL));
					}
				}
			}
		}
	}

	for (int c = 0; c < vd->vdev_children; c++) {

		/*
		 * Set the vdev id to the first hole, if one exists.
		 */
		for (id = 0; id < rvd->vdev_children; id++) {
			if (rvd->vdev_child[id]->vdev_ishole) {
				vdev_free(rvd->vdev_child[id]);
				break;
			}
		}
		tvd = vd->vdev_child[c];
		vdev_remove_child(vd, tvd);
		tvd->vdev_id = id;
		vdev_add_child(rvd, tvd);
		vdev_config_dirty(tvd);
	}

	if (nspares != 0) {
		spa_set_aux_vdevs(&spa->spa_spares, spares, nspares,
		    ZPOOL_CONFIG_SPARES);
		spa_load_spares(spa);
		spa->spa_spares.sav_sync = B_TRUE;
	}

	if (nl2cache != 0) {
		spa_set_aux_vdevs(&spa->spa_l2cache, l2cache, nl2cache,
		    ZPOOL_CONFIG_L2CACHE);
		spa_load_l2cache(spa);
		spa->spa_l2cache.sav_sync = B_TRUE;
	}

	/*
	 * We have to be careful when adding new vdevs to an existing pool.
	 * If other threads start allocating from these vdevs before we
	 * sync the config cache, and we lose power, then upon reboot we may
	 * fail to open the pool because there are DVAs that the config cache
	 * can't translate.  Therefore, we first add the vdevs without
	 * initializing metaslabs; sync the config cache (via spa_vdev_exit());
	 * and then let spa_config_update() initialize the new metaslabs.
	 *
	 * spa_load() checks for added-but-not-initialized vdevs, so that
	 * if we lose power at any point in this sequence, the remaining
	 * steps will be completed the next time we load the pool.
	 */
	(void) spa_vdev_exit(spa, vd, txg, 0);

	mutex_enter(&spa_namespace_lock);
	spa_config_update(spa, SPA_CONFIG_UPDATE_POOL);
	spa_event_notify(spa, NULL, NULL, ESC_ZFS_VDEV_ADD);
	mutex_exit(&spa_namespace_lock);

	return (0);
}

/*
 * Attach a device to a mirror.  The arguments are the path to any device
 * in the mirror, and the nvroot for the new device.  If the path specifies
 * a device that is not mirrored, we automatically insert the mirror vdev.
 *
 * If 'replacing' is specified, the new device is intended to replace the
 * existing device; in this case the two devices are made into their own
 * mirror using the 'replacing' vdev, which is functionally identical to
 * the mirror vdev (it actually reuses all the same ops) but has a few
 * extra rules: you can't attach to it after it's been created, and upon
 * completion of resilvering, the first disk (the one being replaced)
 * is automatically detached.
 */
int
spa_vdev_attach(spa_t *spa, uint64_t guid, nvlist_t *nvroot, int replacing)
{
	uint64_t txg, dtl_max_txg;
	ASSERTV(vdev_t *rvd = spa->spa_root_vdev);
	vdev_t *oldvd, *newvd, *newrootvd, *pvd, *tvd;
	vdev_ops_t *pvops;
	char *oldvdpath, *newvdpath;
	int newvd_isspare;
	int error;

	ASSERT(spa_writeable(spa));

	txg = spa_vdev_enter(spa);

	oldvd = spa_lookup_by_guid(spa, guid, B_FALSE);

	ASSERT(MUTEX_HELD(&spa_namespace_lock));
	if (spa_feature_is_active(spa, SPA_FEATURE_POOL_CHECKPOINT)) {
		error = (spa_has_checkpoint(spa)) ?
		    ZFS_ERR_CHECKPOINT_EXISTS : ZFS_ERR_DISCARDING_CHECKPOINT;
		return (spa_vdev_exit(spa, NULL, txg, error));
	}

	if (spa->spa_vdev_removal != NULL)
		return (spa_vdev_exit(spa, NULL, txg, EBUSY));

	if (oldvd == NULL)
		return (spa_vdev_exit(spa, NULL, txg, ENODEV));

	if (!oldvd->vdev_ops->vdev_op_leaf)
		return (spa_vdev_exit(spa, NULL, txg, ENOTSUP));

	pvd = oldvd->vdev_parent;

	if ((error = spa_config_parse(spa, &newrootvd, nvroot, NULL, 0,
	    VDEV_ALLOC_ATTACH)) != 0)
		return (spa_vdev_exit(spa, NULL, txg, EINVAL));

	if (newrootvd->vdev_children != 1)
		return (spa_vdev_exit(spa, newrootvd, txg, EINVAL));

	newvd = newrootvd->vdev_child[0];

	if (!newvd->vdev_ops->vdev_op_leaf)
		return (spa_vdev_exit(spa, newrootvd, txg, EINVAL));

	if ((error = vdev_create(newrootvd, txg, replacing)) != 0)
		return (spa_vdev_exit(spa, newrootvd, txg, error));

	/*
	 * Spares can't replace logs
	 */
	if (oldvd->vdev_top->vdev_islog && newvd->vdev_isspare)
		return (spa_vdev_exit(spa, newrootvd, txg, ENOTSUP));

	if (!replacing) {
		/*
		 * For attach, the only allowable parent is a mirror or the root
		 * vdev.
		 */
		if (pvd->vdev_ops != &vdev_mirror_ops &&
		    pvd->vdev_ops != &vdev_root_ops)
			return (spa_vdev_exit(spa, newrootvd, txg, ENOTSUP));

		pvops = &vdev_mirror_ops;
	} else {
		/*
		 * Active hot spares can only be replaced by inactive hot
		 * spares.
		 */
		if (pvd->vdev_ops == &vdev_spare_ops &&
		    oldvd->vdev_isspare &&
		    !spa_has_spare(spa, newvd->vdev_guid))
			return (spa_vdev_exit(spa, newrootvd, txg, ENOTSUP));

		/*
		 * If the source is a hot spare, and the parent isn't already a
		 * spare, then we want to create a new hot spare.  Otherwise, we
		 * want to create a replacing vdev.  The user is not allowed to
		 * attach to a spared vdev child unless the 'isspare' state is
		 * the same (spare replaces spare, non-spare replaces
		 * non-spare).
		 */
		if (pvd->vdev_ops == &vdev_replacing_ops &&
		    spa_version(spa) < SPA_VERSION_MULTI_REPLACE) {
			return (spa_vdev_exit(spa, newrootvd, txg, ENOTSUP));
		} else if (pvd->vdev_ops == &vdev_spare_ops &&
		    newvd->vdev_isspare != oldvd->vdev_isspare) {
			return (spa_vdev_exit(spa, newrootvd, txg, ENOTSUP));
		}

		if (newvd->vdev_isspare)
			pvops = &vdev_spare_ops;
		else
			pvops = &vdev_replacing_ops;
	}

	/*
	 * Make sure the new device is big enough.
	 */
	if (newvd->vdev_asize < vdev_get_min_asize(oldvd))
		return (spa_vdev_exit(spa, newrootvd, txg, EOVERFLOW));

	/*
	 * The new device cannot have a higher alignment requirement
	 * than the top-level vdev.
	 */
	if (newvd->vdev_ashift > oldvd->vdev_top->vdev_ashift)
		return (spa_vdev_exit(spa, newrootvd, txg, EDOM));

	/*
	 * If this is an in-place replacement, update oldvd's path and devid
	 * to make it distinguishable from newvd, and unopenable from now on.
	 */
	if (strcmp(oldvd->vdev_path, newvd->vdev_path) == 0) {
		spa_strfree(oldvd->vdev_path);
		oldvd->vdev_path = kmem_alloc(strlen(newvd->vdev_path) + 5,
		    KM_SLEEP);
		(void) sprintf(oldvd->vdev_path, "%s/%s",
		    newvd->vdev_path, "old");
		if (oldvd->vdev_devid != NULL) {
			spa_strfree(oldvd->vdev_devid);
			oldvd->vdev_devid = NULL;
		}
	}

	/* mark the device being resilvered */
	newvd->vdev_resilver_txg = txg;

	/*
	 * If the parent is not a mirror, or if we're replacing, insert the new
	 * mirror/replacing/spare vdev above oldvd.
	 */
	if (pvd->vdev_ops != pvops)
		pvd = vdev_add_parent(oldvd, pvops);

	ASSERT(pvd->vdev_top->vdev_parent == rvd);
	ASSERT(pvd->vdev_ops == pvops);
	ASSERT(oldvd->vdev_parent == pvd);

	/*
	 * Extract the new device from its root and add it to pvd.
	 */
	vdev_remove_child(newrootvd, newvd);
	newvd->vdev_id = pvd->vdev_children;
	newvd->vdev_crtxg = oldvd->vdev_crtxg;
	vdev_add_child(pvd, newvd);

	/*
	 * Reevaluate the parent vdev state.
	 */
	vdev_propagate_state(pvd);

	tvd = newvd->vdev_top;
	ASSERT(pvd->vdev_top == tvd);
	ASSERT(tvd->vdev_parent == rvd);

	vdev_config_dirty(tvd);

	/*
	 * Set newvd's DTL to [TXG_INITIAL, dtl_max_txg) so that we account
	 * for any dmu_sync-ed blocks.  It will propagate upward when
	 * spa_vdev_exit() calls vdev_dtl_reassess().
	 */
	dtl_max_txg = txg + TXG_CONCURRENT_STATES;

	vdev_dtl_dirty(newvd, DTL_MISSING, TXG_INITIAL,
	    dtl_max_txg - TXG_INITIAL);

	if (newvd->vdev_isspare) {
		spa_spare_activate(newvd);
		spa_event_notify(spa, newvd, NULL, ESC_ZFS_VDEV_SPARE);
	}

	oldvdpath = spa_strdup(oldvd->vdev_path);
	newvdpath = spa_strdup(newvd->vdev_path);
	newvd_isspare = newvd->vdev_isspare;

	/*
	 * Mark newvd's DTL dirty in this txg.
	 */
	vdev_dirty(tvd, VDD_DTL, newvd, txg);

	/*
	 * Schedule the resilver to restart in the future. We do this to
	 * ensure that dmu_sync-ed blocks have been stitched into the
	 * respective datasets. We do not do this if resilvers have been
	 * deferred.
	 */
	if (dsl_scan_resilvering(spa_get_dsl(spa)) &&
	    spa_feature_is_enabled(spa, SPA_FEATURE_RESILVER_DEFER))
		vdev_set_deferred_resilver(spa, newvd);
	else
		dsl_resilver_restart(spa->spa_dsl_pool, dtl_max_txg);

	if (spa->spa_bootfs)
		spa_event_notify(spa, newvd, NULL, ESC_ZFS_BOOTFS_VDEV_ATTACH);

	spa_event_notify(spa, newvd, NULL, ESC_ZFS_VDEV_ATTACH);

	/*
	 * Commit the config
	 */
	(void) spa_vdev_exit(spa, newrootvd, dtl_max_txg, 0);

	spa_history_log_internal(spa, "vdev attach", NULL,
	    "%s vdev=%s %s vdev=%s",
	    replacing && newvd_isspare ? "spare in" :
	    replacing ? "replace" : "attach", newvdpath,
	    replacing ? "for" : "to", oldvdpath);

	spa_strfree(oldvdpath);
	spa_strfree(newvdpath);

	return (0);
}

/*
 * Detach a device from a mirror or replacing vdev.
 *
 * If 'replace_done' is specified, only detach if the parent
 * is a replacing vdev.
 */
int
spa_vdev_detach(spa_t *spa, uint64_t guid, uint64_t pguid, int replace_done)
{
	uint64_t txg;
	int error;
	ASSERTV(vdev_t *rvd = spa->spa_root_vdev);
	vdev_t *vd, *pvd, *cvd, *tvd;
	boolean_t unspare = B_FALSE;
	uint64_t unspare_guid = 0;
	char *vdpath;

	ASSERT(spa_writeable(spa));

	txg = spa_vdev_enter(spa);

	vd = spa_lookup_by_guid(spa, guid, B_FALSE);

	/*
	 * Besides being called directly from the userland through the
	 * ioctl interface, spa_vdev_detach() can be potentially called
	 * at the end of spa_vdev_resilver_done().
	 *
	 * In the regular case, when we have a checkpoint this shouldn't
	 * happen as we never empty the DTLs of a vdev during the scrub
	 * [see comment in dsl_scan_done()]. Thus spa_vdev_resilvering_done()
	 * should never get here when we have a checkpoint.
	 *
	 * That said, even in a case when we checkpoint the pool exactly
	 * as spa_vdev_resilver_done() calls this function everything
	 * should be fine as the resilver will return right away.
	 */
	ASSERT(MUTEX_HELD(&spa_namespace_lock));
	if (spa_feature_is_active(spa, SPA_FEATURE_POOL_CHECKPOINT)) {
		error = (spa_has_checkpoint(spa)) ?
		    ZFS_ERR_CHECKPOINT_EXISTS : ZFS_ERR_DISCARDING_CHECKPOINT;
		return (spa_vdev_exit(spa, NULL, txg, error));
	}

	if (vd == NULL)
		return (spa_vdev_exit(spa, NULL, txg, ENODEV));

	if (!vd->vdev_ops->vdev_op_leaf)
		return (spa_vdev_exit(spa, NULL, txg, ENOTSUP));

	pvd = vd->vdev_parent;

	/*
	 * If the parent/child relationship is not as expected, don't do it.
	 * Consider M(A,R(B,C)) -- that is, a mirror of A with a replacing
	 * vdev that's replacing B with C.  The user's intent in replacing
	 * is to go from M(A,B) to M(A,C).  If the user decides to cancel
	 * the replace by detaching C, the expected behavior is to end up
	 * M(A,B).  But suppose that right after deciding to detach C,
	 * the replacement of B completes.  We would have M(A,C), and then
	 * ask to detach C, which would leave us with just A -- not what
	 * the user wanted.  To prevent this, we make sure that the
	 * parent/child relationship hasn't changed -- in this example,
	 * that C's parent is still the replacing vdev R.
	 */
	if (pvd->vdev_guid != pguid && pguid != 0)
		return (spa_vdev_exit(spa, NULL, txg, EBUSY));

	/*
	 * Only 'replacing' or 'spare' vdevs can be replaced.
	 */
	if (replace_done && pvd->vdev_ops != &vdev_replacing_ops &&
	    pvd->vdev_ops != &vdev_spare_ops)
		return (spa_vdev_exit(spa, NULL, txg, ENOTSUP));

	ASSERT(pvd->vdev_ops != &vdev_spare_ops ||
	    spa_version(spa) >= SPA_VERSION_SPARES);

	/*
	 * Only mirror, replacing, and spare vdevs support detach.
	 */
	if (pvd->vdev_ops != &vdev_replacing_ops &&
	    pvd->vdev_ops != &vdev_mirror_ops &&
	    pvd->vdev_ops != &vdev_spare_ops)
		return (spa_vdev_exit(spa, NULL, txg, ENOTSUP));

	/*
	 * If this device has the only valid copy of some data,
	 * we cannot safely detach it.
	 */
	if (vdev_dtl_required(vd))
		return (spa_vdev_exit(spa, NULL, txg, EBUSY));

	ASSERT(pvd->vdev_children >= 2);

	/*
	 * If we are detaching the second disk from a replacing vdev, then
	 * check to see if we changed the original vdev's path to have "/old"
	 * at the end in spa_vdev_attach().  If so, undo that change now.
	 */
	if (pvd->vdev_ops == &vdev_replacing_ops && vd->vdev_id > 0 &&
	    vd->vdev_path != NULL) {
		size_t len = strlen(vd->vdev_path);

		for (int c = 0; c < pvd->vdev_children; c++) {
			cvd = pvd->vdev_child[c];

			if (cvd == vd || cvd->vdev_path == NULL)
				continue;

			if (strncmp(cvd->vdev_path, vd->vdev_path, len) == 0 &&
			    strcmp(cvd->vdev_path + len, "/old") == 0) {
				spa_strfree(cvd->vdev_path);
				cvd->vdev_path = spa_strdup(vd->vdev_path);
				break;
			}
		}
	}

	/*
	 * If we are detaching the original disk from a spare, then it implies
	 * that the spare should become a real disk, and be removed from the
	 * active spare list for the pool.
	 */
	if (pvd->vdev_ops == &vdev_spare_ops &&
	    vd->vdev_id == 0 &&
	    pvd->vdev_child[pvd->vdev_children - 1]->vdev_isspare)
		unspare = B_TRUE;

	/*
	 * Erase the disk labels so the disk can be used for other things.
	 * This must be done after all other error cases are handled,
	 * but before we disembowel vd (so we can still do I/O to it).
	 * But if we can't do it, don't treat the error as fatal --
	 * it may be that the unwritability of the disk is the reason
	 * it's being detached!
	 */
	error = vdev_label_init(vd, 0, VDEV_LABEL_REMOVE);

	/*
	 * Remove vd from its parent and compact the parent's children.
	 */
	vdev_remove_child(pvd, vd);
	vdev_compact_children(pvd);

	/*
	 * Remember one of the remaining children so we can get tvd below.
	 */
	cvd = pvd->vdev_child[pvd->vdev_children - 1];

	/*
	 * If we need to remove the remaining child from the list of hot spares,
	 * do it now, marking the vdev as no longer a spare in the process.
	 * We must do this before vdev_remove_parent(), because that can
	 * change the GUID if it creates a new toplevel GUID.  For a similar
	 * reason, we must remove the spare now, in the same txg as the detach;
	 * otherwise someone could attach a new sibling, change the GUID, and
	 * the subsequent attempt to spa_vdev_remove(unspare_guid) would fail.
	 */
	if (unspare) {
		ASSERT(cvd->vdev_isspare);
		spa_spare_remove(cvd);
		unspare_guid = cvd->vdev_guid;
		(void) spa_vdev_remove(spa, unspare_guid, B_TRUE);
		cvd->vdev_unspare = B_TRUE;
	}

	/*
	 * If the parent mirror/replacing vdev only has one child,
	 * the parent is no longer needed.  Remove it from the tree.
	 */
	if (pvd->vdev_children == 1) {
		if (pvd->vdev_ops == &vdev_spare_ops)
			cvd->vdev_unspare = B_FALSE;
		vdev_remove_parent(cvd);
	}

	/*
	 * We don't set tvd until now because the parent we just removed
	 * may have been the previous top-level vdev.
	 */
	tvd = cvd->vdev_top;
	ASSERT(tvd->vdev_parent == rvd);

	/*
	 * Reevaluate the parent vdev state.
	 */
	vdev_propagate_state(cvd);

	/*
	 * If the 'autoexpand' property is set on the pool then automatically
	 * try to expand the size of the pool. For example if the device we
	 * just detached was smaller than the others, it may be possible to
	 * add metaslabs (i.e. grow the pool). We need to reopen the vdev
	 * first so that we can obtain the updated sizes of the leaf vdevs.
	 */
	if (spa->spa_autoexpand) {
		vdev_reopen(tvd);
		vdev_expand(tvd, txg);
	}

	vdev_config_dirty(tvd);

	/*
	 * Mark vd's DTL as dirty in this txg.  vdev_dtl_sync() will see that
	 * vd->vdev_detached is set and free vd's DTL object in syncing context.
	 * But first make sure we're not on any *other* txg's DTL list, to
	 * prevent vd from being accessed after it's freed.
	 */
	vdpath = spa_strdup(vd->vdev_path ? vd->vdev_path : "none");
	for (int t = 0; t < TXG_SIZE; t++)
		(void) txg_list_remove_this(&tvd->vdev_dtl_list, vd, t);
	vd->vdev_detached = B_TRUE;
	vdev_dirty(tvd, VDD_DTL, vd, txg);

	spa_event_notify(spa, vd, NULL, ESC_ZFS_VDEV_REMOVE);

	/* hang on to the spa before we release the lock */
	spa_open_ref(spa, FTAG);

	error = spa_vdev_exit(spa, vd, txg, 0);

	spa_history_log_internal(spa, "detach", NULL,
	    "vdev=%s", vdpath);
	spa_strfree(vdpath);

	/*
	 * If this was the removal of the original device in a hot spare vdev,
	 * then we want to go through and remove the device from the hot spare
	 * list of every other pool.
	 */
	if (unspare) {
		spa_t *altspa = NULL;

		mutex_enter(&spa_namespace_lock);
		while ((altspa = spa_next(altspa)) != NULL) {
			if (altspa->spa_state != POOL_STATE_ACTIVE ||
			    altspa == spa)
				continue;

			spa_open_ref(altspa, FTAG);
			mutex_exit(&spa_namespace_lock);
			(void) spa_vdev_remove(altspa, unspare_guid, B_TRUE);
			mutex_enter(&spa_namespace_lock);
			spa_close(altspa, FTAG);
		}
		mutex_exit(&spa_namespace_lock);

		/* search the rest of the vdevs for spares to remove */
		spa_vdev_resilver_done(spa);
	}

	/* all done with the spa; OK to release */
	mutex_enter(&spa_namespace_lock);
	spa_close(spa, FTAG);
	mutex_exit(&spa_namespace_lock);

	return (error);
}

static int
spa_vdev_initialize_impl(spa_t *spa, uint64_t guid, uint64_t cmd_type,
    list_t *vd_list)
{
	ASSERT(MUTEX_HELD(&spa_namespace_lock));

	spa_config_enter(spa, SCL_CONFIG | SCL_STATE, FTAG, RW_READER);

	/* Look up vdev and ensure it's a leaf. */
	vdev_t *vd = spa_lookup_by_guid(spa, guid, B_FALSE);
	if (vd == NULL || vd->vdev_detached) {
		spa_config_exit(spa, SCL_CONFIG | SCL_STATE, FTAG);
		return (SET_ERROR(ENODEV));
	} else if (!vd->vdev_ops->vdev_op_leaf || !vdev_is_concrete(vd)) {
		spa_config_exit(spa, SCL_CONFIG | SCL_STATE, FTAG);
		return (SET_ERROR(EINVAL));
	} else if (!vdev_writeable(vd)) {
		spa_config_exit(spa, SCL_CONFIG | SCL_STATE, FTAG);
		return (SET_ERROR(EROFS));
	}
	mutex_enter(&vd->vdev_initialize_lock);
	spa_config_exit(spa, SCL_CONFIG | SCL_STATE, FTAG);

	/*
	 * When we activate an initialize action we check to see
	 * if the vdev_initialize_thread is NULL. We do this instead
	 * of using the vdev_initialize_state since there might be
	 * a previous initialization process which has completed but
	 * the thread is not exited.
	 */
	if (cmd_type == POOL_INITIALIZE_START &&
	    (vd->vdev_initialize_thread != NULL ||
	    vd->vdev_top->vdev_removing)) {
		mutex_exit(&vd->vdev_initialize_lock);
		return (SET_ERROR(EBUSY));
	} else if (cmd_type == POOL_INITIALIZE_CANCEL &&
	    (vd->vdev_initialize_state != VDEV_INITIALIZE_ACTIVE &&
	    vd->vdev_initialize_state != VDEV_INITIALIZE_SUSPENDED)) {
		mutex_exit(&vd->vdev_initialize_lock);
		return (SET_ERROR(ESRCH));
	} else if (cmd_type == POOL_INITIALIZE_SUSPEND &&
	    vd->vdev_initialize_state != VDEV_INITIALIZE_ACTIVE) {
		mutex_exit(&vd->vdev_initialize_lock);
		return (SET_ERROR(ESRCH));
	}

	switch (cmd_type) {
	case POOL_INITIALIZE_START:
		vdev_initialize(vd);
		break;
	case POOL_INITIALIZE_CANCEL:
		vdev_initialize_stop(vd, VDEV_INITIALIZE_CANCELED, vd_list);
		break;
	case POOL_INITIALIZE_SUSPEND:
		vdev_initialize_stop(vd, VDEV_INITIALIZE_SUSPENDED, vd_list);
		break;
	default:
		panic("invalid cmd_type %llu", (unsigned long long)cmd_type);
	}
	mutex_exit(&vd->vdev_initialize_lock);

	return (0);
}

int
spa_vdev_initialize(spa_t *spa, nvlist_t *nv, uint64_t cmd_type,
    nvlist_t *vdev_errlist)
{
	int total_errors = 0;
	list_t vd_list;

	list_create(&vd_list, sizeof (vdev_t),
	    offsetof(vdev_t, vdev_initialize_node));

	/*
	 * We hold the namespace lock through the whole function
	 * to prevent any changes to the pool while we're starting or
	 * stopping initialization. The config and state locks are held so that
	 * we can properly assess the vdev state before we commit to
	 * the initializing operation.
	 */
	mutex_enter(&spa_namespace_lock);

	for (nvpair_t *pair = nvlist_next_nvpair(nv, NULL);
	    pair != NULL; pair = nvlist_next_nvpair(nv, pair)) {
		uint64_t vdev_guid = fnvpair_value_uint64(pair);

		int error = spa_vdev_initialize_impl(spa, vdev_guid, cmd_type,
		    &vd_list);
		if (error != 0) {
			char guid_as_str[MAXNAMELEN];

			(void) snprintf(guid_as_str, sizeof (guid_as_str),
			    "%llu", (unsigned long long)vdev_guid);
			fnvlist_add_int64(vdev_errlist, guid_as_str, error);
			total_errors++;
		}
	}

	/* Wait for all initialize threads to stop. */
	vdev_initialize_stop_wait(spa, &vd_list);

	/* Sync out the initializing state */
	txg_wait_synced(spa->spa_dsl_pool, 0);
	mutex_exit(&spa_namespace_lock);

	list_destroy(&vd_list);

	return (total_errors);
}

static int
spa_vdev_trim_impl(spa_t *spa, uint64_t guid, uint64_t cmd_type,
    uint64_t rate, boolean_t partial, boolean_t secure, list_t *vd_list)
{
	ASSERT(MUTEX_HELD(&spa_namespace_lock));

	spa_config_enter(spa, SCL_CONFIG | SCL_STATE, FTAG, RW_READER);

	/* Look up vdev and ensure it's a leaf. */
	vdev_t *vd = spa_lookup_by_guid(spa, guid, B_FALSE);
	if (vd == NULL || vd->vdev_detached) {
		spa_config_exit(spa, SCL_CONFIG | SCL_STATE, FTAG);
		return (SET_ERROR(ENODEV));
	} else if (!vd->vdev_ops->vdev_op_leaf || !vdev_is_concrete(vd)) {
		spa_config_exit(spa, SCL_CONFIG | SCL_STATE, FTAG);
		return (SET_ERROR(EINVAL));
	} else if (!vdev_writeable(vd)) {
		spa_config_exit(spa, SCL_CONFIG | SCL_STATE, FTAG);
		return (SET_ERROR(EROFS));
	} else if (!vd->vdev_has_trim) {
		spa_config_exit(spa, SCL_CONFIG | SCL_STATE, FTAG);
		return (SET_ERROR(EOPNOTSUPP));
	} else if (secure && !vd->vdev_has_securetrim) {
		spa_config_exit(spa, SCL_CONFIG | SCL_STATE, FTAG);
		return (SET_ERROR(EOPNOTSUPP));
	}
	mutex_enter(&vd->vdev_trim_lock);
	spa_config_exit(spa, SCL_CONFIG | SCL_STATE, FTAG);

	/*
	 * When we activate a TRIM action we check to see if the
	 * vdev_trim_thread is NULL. We do this instead of using the
	 * vdev_trim_state since there might be a previous TRIM process
	 * which has completed but the thread is not exited.
	 */
	if (cmd_type == POOL_TRIM_START &&
	    (vd->vdev_trim_thread != NULL || vd->vdev_top->vdev_removing)) {
		mutex_exit(&vd->vdev_trim_lock);
		return (SET_ERROR(EBUSY));
	} else if (cmd_type == POOL_TRIM_CANCEL &&
	    (vd->vdev_trim_state != VDEV_TRIM_ACTIVE &&
	    vd->vdev_trim_state != VDEV_TRIM_SUSPENDED)) {
		mutex_exit(&vd->vdev_trim_lock);
		return (SET_ERROR(ESRCH));
	} else if (cmd_type == POOL_TRIM_SUSPEND &&
	    vd->vdev_trim_state != VDEV_TRIM_ACTIVE) {
		mutex_exit(&vd->vdev_trim_lock);
		return (SET_ERROR(ESRCH));
	}

	switch (cmd_type) {
	case POOL_TRIM_START:
		vdev_trim(vd, rate, partial, secure);
		break;
	case POOL_TRIM_CANCEL:
		vdev_trim_stop(vd, VDEV_TRIM_CANCELED, vd_list);
		break;
	case POOL_TRIM_SUSPEND:
		vdev_trim_stop(vd, VDEV_TRIM_SUSPENDED, vd_list);
		break;
	default:
		panic("invalid cmd_type %llu", (unsigned long long)cmd_type);
	}
	mutex_exit(&vd->vdev_trim_lock);

	return (0);
}

/*
 * Initiates a manual TRIM for the requested vdevs. This kicks off individual
 * TRIM threads for each child vdev.  These threads pass over all of the free
 * space in the vdev's metaslabs and issues TRIM commands for that space.
 */
int
spa_vdev_trim(spa_t *spa, nvlist_t *nv, uint64_t cmd_type, uint64_t rate,
    boolean_t partial, boolean_t secure, nvlist_t *vdev_errlist)
{
	int total_errors = 0;
	list_t vd_list;

	list_create(&vd_list, sizeof (vdev_t),
	    offsetof(vdev_t, vdev_trim_node));

	/*
	 * We hold the namespace lock through the whole function
	 * to prevent any changes to the pool while we're starting or
	 * stopping TRIM. The config and state locks are held so that
	 * we can properly assess the vdev state before we commit to
	 * the TRIM operation.
	 */
	mutex_enter(&spa_namespace_lock);

	for (nvpair_t *pair = nvlist_next_nvpair(nv, NULL);
	    pair != NULL; pair = nvlist_next_nvpair(nv, pair)) {
		uint64_t vdev_guid = fnvpair_value_uint64(pair);

		int error = spa_vdev_trim_impl(spa, vdev_guid, cmd_type,
		    rate, partial, secure, &vd_list);
		if (error != 0) {
			char guid_as_str[MAXNAMELEN];

			(void) snprintf(guid_as_str, sizeof (guid_as_str),
			    "%llu", (unsigned long long)vdev_guid);
			fnvlist_add_int64(vdev_errlist, guid_as_str, error);
			total_errors++;
		}
	}

	/* Wait for all TRIM threads to stop. */
	vdev_trim_stop_wait(spa, &vd_list);

	/* Sync out the TRIM state */
	txg_wait_synced(spa->spa_dsl_pool, 0);
	mutex_exit(&spa_namespace_lock);

	list_destroy(&vd_list);

	return (total_errors);
}

/*
 * Split a set of devices from their mirrors, and create a new pool from them.
 */
int
spa_vdev_split_mirror(spa_t *spa, char *newname, nvlist_t *config,
    nvlist_t *props, boolean_t exp)
{
	int error = 0;
	uint64_t txg, *glist;
	spa_t *newspa;
	uint_t c, children, lastlog;
	nvlist_t **child, *nvl, *tmp;
	dmu_tx_t *tx;
	char *altroot = NULL;
	vdev_t *rvd, **vml = NULL;			/* vdev modify list */
	boolean_t activate_slog;

	ASSERT(spa_writeable(spa));

	txg = spa_vdev_enter(spa);

	ASSERT(MUTEX_HELD(&spa_namespace_lock));
	if (spa_feature_is_active(spa, SPA_FEATURE_POOL_CHECKPOINT)) {
		error = (spa_has_checkpoint(spa)) ?
		    ZFS_ERR_CHECKPOINT_EXISTS : ZFS_ERR_DISCARDING_CHECKPOINT;
		return (spa_vdev_exit(spa, NULL, txg, error));
	}

	/* clear the log and flush everything up to now */
	activate_slog = spa_passivate_log(spa);
	(void) spa_vdev_config_exit(spa, NULL, txg, 0, FTAG);
	error = spa_reset_logs(spa);
	txg = spa_vdev_config_enter(spa);

	if (activate_slog)
		spa_activate_log(spa);

	if (error != 0)
		return (spa_vdev_exit(spa, NULL, txg, error));

	/* check new spa name before going any further */
	if (spa_lookup(newname) != NULL)
		return (spa_vdev_exit(spa, NULL, txg, EEXIST));

	/*
	 * scan through all the children to ensure they're all mirrors
	 */
	if (nvlist_lookup_nvlist(config, ZPOOL_CONFIG_VDEV_TREE, &nvl) != 0 ||
	    nvlist_lookup_nvlist_array(nvl, ZPOOL_CONFIG_CHILDREN, &child,
	    &children) != 0)
		return (spa_vdev_exit(spa, NULL, txg, EINVAL));

	/* first, check to ensure we've got the right child count */
	rvd = spa->spa_root_vdev;
	lastlog = 0;
	for (c = 0; c < rvd->vdev_children; c++) {
		vdev_t *vd = rvd->vdev_child[c];

		/* don't count the holes & logs as children */
		if (vd->vdev_islog || !vdev_is_concrete(vd)) {
			if (lastlog == 0)
				lastlog = c;
			continue;
		}

		lastlog = 0;
	}
	if (children != (lastlog != 0 ? lastlog : rvd->vdev_children))
		return (spa_vdev_exit(spa, NULL, txg, EINVAL));

	/* next, ensure no spare or cache devices are part of the split */
	if (nvlist_lookup_nvlist(nvl, ZPOOL_CONFIG_SPARES, &tmp) == 0 ||
	    nvlist_lookup_nvlist(nvl, ZPOOL_CONFIG_L2CACHE, &tmp) == 0)
		return (spa_vdev_exit(spa, NULL, txg, EINVAL));

	vml = kmem_zalloc(children * sizeof (vdev_t *), KM_SLEEP);
	glist = kmem_zalloc(children * sizeof (uint64_t), KM_SLEEP);

	/* then, loop over each vdev and validate it */
	for (c = 0; c < children; c++) {
		uint64_t is_hole = 0;

		(void) nvlist_lookup_uint64(child[c], ZPOOL_CONFIG_IS_HOLE,
		    &is_hole);

		if (is_hole != 0) {
			if (spa->spa_root_vdev->vdev_child[c]->vdev_ishole ||
			    spa->spa_root_vdev->vdev_child[c]->vdev_islog) {
				continue;
			} else {
				error = SET_ERROR(EINVAL);
				break;
			}
		}

		/* which disk is going to be split? */
		if (nvlist_lookup_uint64(child[c], ZPOOL_CONFIG_GUID,
		    &glist[c]) != 0) {
			error = SET_ERROR(EINVAL);
			break;
		}

		/* look it up in the spa */
		vml[c] = spa_lookup_by_guid(spa, glist[c], B_FALSE);
		if (vml[c] == NULL) {
			error = SET_ERROR(ENODEV);
			break;
		}

		/* make sure there's nothing stopping the split */
		if (vml[c]->vdev_parent->vdev_ops != &vdev_mirror_ops ||
		    vml[c]->vdev_islog ||
		    !vdev_is_concrete(vml[c]) ||
		    vml[c]->vdev_isspare ||
		    vml[c]->vdev_isl2cache ||
		    !vdev_writeable(vml[c]) ||
		    vml[c]->vdev_children != 0 ||
		    vml[c]->vdev_state != VDEV_STATE_HEALTHY ||
		    c != spa->spa_root_vdev->vdev_child[c]->vdev_id) {
			error = SET_ERROR(EINVAL);
			break;
		}

		if (vdev_dtl_required(vml[c]) ||
		    vdev_resilver_needed(vml[c], NULL, NULL)) {
			error = SET_ERROR(EBUSY);
			break;
		}

		/* we need certain info from the top level */
		VERIFY(nvlist_add_uint64(child[c], ZPOOL_CONFIG_METASLAB_ARRAY,
		    vml[c]->vdev_top->vdev_ms_array) == 0);
		VERIFY(nvlist_add_uint64(child[c], ZPOOL_CONFIG_METASLAB_SHIFT,
		    vml[c]->vdev_top->vdev_ms_shift) == 0);
		VERIFY(nvlist_add_uint64(child[c], ZPOOL_CONFIG_ASIZE,
		    vml[c]->vdev_top->vdev_asize) == 0);
		VERIFY(nvlist_add_uint64(child[c], ZPOOL_CONFIG_ASHIFT,
		    vml[c]->vdev_top->vdev_ashift) == 0);

		/* transfer per-vdev ZAPs */
		ASSERT3U(vml[c]->vdev_leaf_zap, !=, 0);
		VERIFY0(nvlist_add_uint64(child[c],
		    ZPOOL_CONFIG_VDEV_LEAF_ZAP, vml[c]->vdev_leaf_zap));

		ASSERT3U(vml[c]->vdev_top->vdev_top_zap, !=, 0);
		VERIFY0(nvlist_add_uint64(child[c],
		    ZPOOL_CONFIG_VDEV_TOP_ZAP,
		    vml[c]->vdev_parent->vdev_top_zap));
	}

	if (error != 0) {
		kmem_free(vml, children * sizeof (vdev_t *));
		kmem_free(glist, children * sizeof (uint64_t));
		return (spa_vdev_exit(spa, NULL, txg, error));
	}

	/* stop writers from using the disks */
	for (c = 0; c < children; c++) {
		if (vml[c] != NULL)
			vml[c]->vdev_offline = B_TRUE;
	}
	vdev_reopen(spa->spa_root_vdev);

	/*
	 * Temporarily record the splitting vdevs in the spa config.  This
	 * will disappear once the config is regenerated.
	 */
	VERIFY(nvlist_alloc(&nvl, NV_UNIQUE_NAME, KM_SLEEP) == 0);
	VERIFY(nvlist_add_uint64_array(nvl, ZPOOL_CONFIG_SPLIT_LIST,
	    glist, children) == 0);
	kmem_free(glist, children * sizeof (uint64_t));

	mutex_enter(&spa->spa_props_lock);
	VERIFY(nvlist_add_nvlist(spa->spa_config, ZPOOL_CONFIG_SPLIT,
	    nvl) == 0);
	mutex_exit(&spa->spa_props_lock);
	spa->spa_config_splitting = nvl;
	vdev_config_dirty(spa->spa_root_vdev);

	/* configure and create the new pool */
	VERIFY(nvlist_add_string(config, ZPOOL_CONFIG_POOL_NAME, newname) == 0);
	VERIFY(nvlist_add_uint64(config, ZPOOL_CONFIG_POOL_STATE,
	    exp ? POOL_STATE_EXPORTED : POOL_STATE_ACTIVE) == 0);
	VERIFY(nvlist_add_uint64(config, ZPOOL_CONFIG_VERSION,
	    spa_version(spa)) == 0);
	VERIFY(nvlist_add_uint64(config, ZPOOL_CONFIG_POOL_TXG,
	    spa->spa_config_txg) == 0);
	VERIFY(nvlist_add_uint64(config, ZPOOL_CONFIG_POOL_GUID,
	    spa_generate_guid(NULL)) == 0);
	VERIFY0(nvlist_add_boolean(config, ZPOOL_CONFIG_HAS_PER_VDEV_ZAPS));
	(void) nvlist_lookup_string(props,
	    zpool_prop_to_name(ZPOOL_PROP_ALTROOT), &altroot);

	/* add the new pool to the namespace */
	newspa = spa_add(newname, config, altroot);
	newspa->spa_avz_action = AVZ_ACTION_REBUILD;
	newspa->spa_config_txg = spa->spa_config_txg;
	spa_set_log_state(newspa, SPA_LOG_CLEAR);

	/* release the spa config lock, retaining the namespace lock */
	spa_vdev_config_exit(spa, NULL, txg, 0, FTAG);

	if (zio_injection_enabled)
		zio_handle_panic_injection(spa, FTAG, 1);

	spa_activate(newspa, spa_mode_global);
	spa_async_suspend(newspa);

	/*
	 * Temporarily stop the initializing and TRIM activity.  We set the
	 * state to ACTIVE so that we know to resume initializing or TRIM
	 * once the split has completed.
	 */
	list_t vd_initialize_list;
	list_create(&vd_initialize_list, sizeof (vdev_t),
	    offsetof(vdev_t, vdev_initialize_node));

	list_t vd_trim_list;
	list_create(&vd_trim_list, sizeof (vdev_t),
	    offsetof(vdev_t, vdev_trim_node));

	for (c = 0; c < children; c++) {
		if (vml[c] != NULL) {
			mutex_enter(&vml[c]->vdev_initialize_lock);
			vdev_initialize_stop(vml[c],
			    VDEV_INITIALIZE_ACTIVE, &vd_initialize_list);
			mutex_exit(&vml[c]->vdev_initialize_lock);

			mutex_enter(&vml[c]->vdev_trim_lock);
			vdev_trim_stop(vml[c], VDEV_TRIM_ACTIVE, &vd_trim_list);
			mutex_exit(&vml[c]->vdev_trim_lock);
		}
	}

	vdev_initialize_stop_wait(spa, &vd_initialize_list);
	vdev_trim_stop_wait(spa, &vd_trim_list);

	list_destroy(&vd_initialize_list);
	list_destroy(&vd_trim_list);

	newspa->spa_config_source = SPA_CONFIG_SRC_SPLIT;

	/* create the new pool from the disks of the original pool */
	error = spa_load(newspa, SPA_LOAD_IMPORT, SPA_IMPORT_ASSEMBLE);
	if (error)
		goto out;

	/* if that worked, generate a real config for the new pool */
	if (newspa->spa_root_vdev != NULL) {
		VERIFY(nvlist_alloc(&newspa->spa_config_splitting,
		    NV_UNIQUE_NAME, KM_SLEEP) == 0);
		VERIFY(nvlist_add_uint64(newspa->spa_config_splitting,
		    ZPOOL_CONFIG_SPLIT_GUID, spa_guid(spa)) == 0);
		spa_config_set(newspa, spa_config_generate(newspa, NULL, -1ULL,
		    B_TRUE));
	}

	/* set the props */
	if (props != NULL) {
		spa_configfile_set(newspa, props, B_FALSE);
		error = spa_prop_set(newspa, props);
		if (error)
			goto out;
	}

	/* flush everything */
	txg = spa_vdev_config_enter(newspa);
	vdev_config_dirty(newspa->spa_root_vdev);
	(void) spa_vdev_config_exit(newspa, NULL, txg, 0, FTAG);

	if (zio_injection_enabled)
		zio_handle_panic_injection(spa, FTAG, 2);

	spa_async_resume(newspa);

	/* finally, update the original pool's config */
	txg = spa_vdev_config_enter(spa);
	tx = dmu_tx_create_dd(spa_get_dsl(spa)->dp_mos_dir);
	error = dmu_tx_assign(tx, TXG_WAIT);
	if (error != 0)
		dmu_tx_abort(tx);
	for (c = 0; c < children; c++) {
		if (vml[c] != NULL) {
			vdev_t *tvd = vml[c]->vdev_top;

			/*
			 * Need to be sure the detachable VDEV is not
			 * on any *other* txg's DTL list to prevent it
			 * from being accessed after it's freed.
			 */
			for (int t = 0; t < TXG_SIZE; t++) {
				(void) txg_list_remove_this(
				    &tvd->vdev_dtl_list, vml[c], t);
			}

			vdev_split(vml[c]);
			if (error == 0)
				spa_history_log_internal(spa, "detach", tx,
				    "vdev=%s", vml[c]->vdev_path);

			vdev_free(vml[c]);
		}
	}
	spa->spa_avz_action = AVZ_ACTION_REBUILD;
	vdev_config_dirty(spa->spa_root_vdev);
	spa->spa_config_splitting = NULL;
	nvlist_free(nvl);
	if (error == 0)
		dmu_tx_commit(tx);
	(void) spa_vdev_exit(spa, NULL, txg, 0);

	if (zio_injection_enabled)
		zio_handle_panic_injection(spa, FTAG, 3);

	/* split is complete; log a history record */
	spa_history_log_internal(newspa, "split", NULL,
	    "from pool %s", spa_name(spa));

	kmem_free(vml, children * sizeof (vdev_t *));

	/* if we're not going to mount the filesystems in userland, export */
	if (exp)
		error = spa_export_common(newname, POOL_STATE_EXPORTED, NULL,
		    B_FALSE, B_FALSE);

	return (error);

out:
	spa_unload(newspa);
	spa_deactivate(newspa);
	spa_remove(newspa);

	txg = spa_vdev_config_enter(spa);

	/* re-online all offlined disks */
	for (c = 0; c < children; c++) {
		if (vml[c] != NULL)
			vml[c]->vdev_offline = B_FALSE;
	}

	/* restart initializing or trimming disks as necessary */
	spa_async_request(spa, SPA_ASYNC_INITIALIZE_RESTART);
	spa_async_request(spa, SPA_ASYNC_TRIM_RESTART);
	spa_async_request(spa, SPA_ASYNC_AUTOTRIM_RESTART);

	vdev_reopen(spa->spa_root_vdev);

	nvlist_free(spa->spa_config_splitting);
	spa->spa_config_splitting = NULL;
	(void) spa_vdev_exit(spa, NULL, txg, error);

	kmem_free(vml, children * sizeof (vdev_t *));
	return (error);
}

/*
 * Find any device that's done replacing, or a vdev marked 'unspare' that's
 * currently spared, so we can detach it.
 */
static vdev_t *
spa_vdev_resilver_done_hunt(vdev_t *vd)
{
	vdev_t *newvd, *oldvd;

	for (int c = 0; c < vd->vdev_children; c++) {
		oldvd = spa_vdev_resilver_done_hunt(vd->vdev_child[c]);
		if (oldvd != NULL)
			return (oldvd);
	}

	/*
	 * Check for a completed replacement.  We always consider the first
	 * vdev in the list to be the oldest vdev, and the last one to be
	 * the newest (see spa_vdev_attach() for how that works).  In
	 * the case where the newest vdev is faulted, we will not automatically
	 * remove it after a resilver completes.  This is OK as it will require
	 * user intervention to determine which disk the admin wishes to keep.
	 */
	if (vd->vdev_ops == &vdev_replacing_ops) {
		ASSERT(vd->vdev_children > 1);

		newvd = vd->vdev_child[vd->vdev_children - 1];
		oldvd = vd->vdev_child[0];

		if (vdev_dtl_empty(newvd, DTL_MISSING) &&
		    vdev_dtl_empty(newvd, DTL_OUTAGE) &&
		    !vdev_dtl_required(oldvd))
			return (oldvd);
	}

	/*
	 * Check for a completed resilver with the 'unspare' flag set.
	 * Also potentially update faulted state.
	 */
	if (vd->vdev_ops == &vdev_spare_ops) {
		vdev_t *first = vd->vdev_child[0];
		vdev_t *last = vd->vdev_child[vd->vdev_children - 1];

		if (last->vdev_unspare) {
			oldvd = first;
			newvd = last;
		} else if (first->vdev_unspare) {
			oldvd = last;
			newvd = first;
		} else {
			oldvd = NULL;
		}

		if (oldvd != NULL &&
		    vdev_dtl_empty(newvd, DTL_MISSING) &&
		    vdev_dtl_empty(newvd, DTL_OUTAGE) &&
		    !vdev_dtl_required(oldvd))
			return (oldvd);

		vdev_propagate_state(vd);

		/*
		 * If there are more than two spares attached to a disk,
		 * and those spares are not required, then we want to
		 * attempt to free them up now so that they can be used
		 * by other pools.  Once we're back down to a single
		 * disk+spare, we stop removing them.
		 */
		if (vd->vdev_children > 2) {
			newvd = vd->vdev_child[1];

			if (newvd->vdev_isspare && last->vdev_isspare &&
			    vdev_dtl_empty(last, DTL_MISSING) &&
			    vdev_dtl_empty(last, DTL_OUTAGE) &&
			    !vdev_dtl_required(newvd))
				return (newvd);
		}
	}

	return (NULL);
}

static void
spa_vdev_resilver_done(spa_t *spa)
{
	vdev_t *vd, *pvd, *ppvd;
	uint64_t guid, sguid, pguid, ppguid;

	spa_config_enter(spa, SCL_ALL, FTAG, RW_WRITER);

	while ((vd = spa_vdev_resilver_done_hunt(spa->spa_root_vdev)) != NULL) {
		pvd = vd->vdev_parent;
		ppvd = pvd->vdev_parent;
		guid = vd->vdev_guid;
		pguid = pvd->vdev_guid;
		ppguid = ppvd->vdev_guid;
		sguid = 0;
		/*
		 * If we have just finished replacing a hot spared device, then
		 * we need to detach the parent's first child (the original hot
		 * spare) as well.
		 */
		if (ppvd->vdev_ops == &vdev_spare_ops && pvd->vdev_id == 0 &&
		    ppvd->vdev_children == 2) {
			ASSERT(pvd->vdev_ops == &vdev_replacing_ops);
			sguid = ppvd->vdev_child[1]->vdev_guid;
		}
		ASSERT(vd->vdev_resilver_txg == 0 || !vdev_dtl_required(vd));

		spa_config_exit(spa, SCL_ALL, FTAG);
		if (spa_vdev_detach(spa, guid, pguid, B_TRUE) != 0)
			return;
		if (sguid && spa_vdev_detach(spa, sguid, ppguid, B_TRUE) != 0)
			return;
		spa_config_enter(spa, SCL_ALL, FTAG, RW_WRITER);
	}

	spa_config_exit(spa, SCL_ALL, FTAG);
}

/*
 * Update the stored path or FRU for this vdev.
 */
int
spa_vdev_set_common(spa_t *spa, uint64_t guid, const char *value,
    boolean_t ispath)
{
	vdev_t *vd;
	boolean_t sync = B_FALSE;

	ASSERT(spa_writeable(spa));

	spa_vdev_state_enter(spa, SCL_ALL);

	if ((vd = spa_lookup_by_guid(spa, guid, B_TRUE)) == NULL)
		return (spa_vdev_state_exit(spa, NULL, ENOENT));

	if (!vd->vdev_ops->vdev_op_leaf)
		return (spa_vdev_state_exit(spa, NULL, ENOTSUP));

	if (ispath) {
		if (strcmp(value, vd->vdev_path) != 0) {
			spa_strfree(vd->vdev_path);
			vd->vdev_path = spa_strdup(value);
			sync = B_TRUE;
		}
	} else {
		if (vd->vdev_fru == NULL) {
			vd->vdev_fru = spa_strdup(value);
			sync = B_TRUE;
		} else if (strcmp(value, vd->vdev_fru) != 0) {
			spa_strfree(vd->vdev_fru);
			vd->vdev_fru = spa_strdup(value);
			sync = B_TRUE;
		}
	}

	return (spa_vdev_state_exit(spa, sync ? vd : NULL, 0));
}

int
spa_vdev_setpath(spa_t *spa, uint64_t guid, const char *newpath)
{
	return (spa_vdev_set_common(spa, guid, newpath, B_TRUE));
}

int
spa_vdev_setfru(spa_t *spa, uint64_t guid, const char *newfru)
{
	return (spa_vdev_set_common(spa, guid, newfru, B_FALSE));
}

/*
 * ==========================================================================
 * SPA Scanning
 * ==========================================================================
 */
int
spa_scrub_pause_resume(spa_t *spa, pool_scrub_cmd_t cmd)
{
	ASSERT(spa_config_held(spa, SCL_ALL, RW_WRITER) == 0);

	if (dsl_scan_resilvering(spa->spa_dsl_pool))
		return (SET_ERROR(EBUSY));

	return (dsl_scrub_set_pause_resume(spa->spa_dsl_pool, cmd));
}

int
spa_scan_stop(spa_t *spa)
{
	ASSERT(spa_config_held(spa, SCL_ALL, RW_WRITER) == 0);
	if (dsl_scan_resilvering(spa->spa_dsl_pool))
		return (SET_ERROR(EBUSY));
	return (dsl_scan_cancel(spa->spa_dsl_pool));
}

int
spa_scan(spa_t *spa, pool_scan_func_t func)
{
	ASSERT(spa_config_held(spa, SCL_ALL, RW_WRITER) == 0);

	if (func >= POOL_SCAN_FUNCS || func == POOL_SCAN_NONE)
		return (SET_ERROR(ENOTSUP));

	if (func == POOL_SCAN_RESILVER &&
	    !spa_feature_is_enabled(spa, SPA_FEATURE_RESILVER_DEFER))
		return (SET_ERROR(ENOTSUP));

	/*
	 * If a resilver was requested, but there is no DTL on a
	 * writeable leaf device, we have nothing to do.
	 */
	if (func == POOL_SCAN_RESILVER &&
	    !vdev_resilver_needed(spa->spa_root_vdev, NULL, NULL)) {
		spa_async_request(spa, SPA_ASYNC_RESILVER_DONE);
		return (0);
	}

	return (dsl_scan(spa->spa_dsl_pool, func));
}

/*
 * ==========================================================================
 * SPA async task processing
 * ==========================================================================
 */

static void
spa_async_remove(spa_t *spa, vdev_t *vd)
{
	if (vd->vdev_remove_wanted) {
		vd->vdev_remove_wanted = B_FALSE;
		vd->vdev_delayed_close = B_FALSE;
		vdev_set_state(vd, B_FALSE, VDEV_STATE_REMOVED, VDEV_AUX_NONE);

		/*
		 * We want to clear the stats, but we don't want to do a full
		 * vdev_clear() as that will cause us to throw away
		 * degraded/faulted state as well as attempt to reopen the
		 * device, all of which is a waste.
		 */
		vd->vdev_stat.vs_read_errors = 0;
		vd->vdev_stat.vs_write_errors = 0;
		vd->vdev_stat.vs_checksum_errors = 0;

		vdev_state_dirty(vd->vdev_top);
	}

	for (int c = 0; c < vd->vdev_children; c++)
		spa_async_remove(spa, vd->vdev_child[c]);
}

static void
spa_async_probe(spa_t *spa, vdev_t *vd)
{
	if (vd->vdev_probe_wanted) {
		vd->vdev_probe_wanted = B_FALSE;
		vdev_reopen(vd);	/* vdev_open() does the actual probe */
	}

	for (int c = 0; c < vd->vdev_children; c++)
		spa_async_probe(spa, vd->vdev_child[c]);
}

static void
spa_async_autoexpand(spa_t *spa, vdev_t *vd)
{
	if (!spa->spa_autoexpand)
		return;

	for (int c = 0; c < vd->vdev_children; c++) {
		vdev_t *cvd = vd->vdev_child[c];
		spa_async_autoexpand(spa, cvd);
	}

	if (!vd->vdev_ops->vdev_op_leaf || vd->vdev_physpath == NULL)
		return;

	spa_event_notify(vd->vdev_spa, vd, NULL, ESC_ZFS_VDEV_AUTOEXPAND);
}

static void
spa_async_thread(void *arg)
{
	spa_t *spa = (spa_t *)arg;
	dsl_pool_t *dp = spa->spa_dsl_pool;
	int tasks;

	ASSERT(spa->spa_sync_on);

	mutex_enter(&spa->spa_async_lock);
	tasks = spa->spa_async_tasks;
	spa->spa_async_tasks = 0;
	mutex_exit(&spa->spa_async_lock);

	/*
	 * See if the config needs to be updated.
	 */
	if (tasks & SPA_ASYNC_CONFIG_UPDATE) {
		uint64_t old_space, new_space;

		mutex_enter(&spa_namespace_lock);
		old_space = metaslab_class_get_space(spa_normal_class(spa));
		old_space += metaslab_class_get_space(spa_special_class(spa));
		old_space += metaslab_class_get_space(spa_dedup_class(spa));

		spa_config_update(spa, SPA_CONFIG_UPDATE_POOL);

		new_space = metaslab_class_get_space(spa_normal_class(spa));
		new_space += metaslab_class_get_space(spa_special_class(spa));
		new_space += metaslab_class_get_space(spa_dedup_class(spa));
		mutex_exit(&spa_namespace_lock);

		/*
		 * If the pool grew as a result of the config update,
		 * then log an internal history event.
		 */
		if (new_space != old_space) {
			spa_history_log_internal(spa, "vdev online", NULL,
			    "pool '%s' size: %llu(+%llu)",
			    spa_name(spa), new_space, new_space - old_space);
		}
	}

	/*
	 * See if any devices need to be marked REMOVED.
	 */
	if (tasks & SPA_ASYNC_REMOVE) {
		spa_vdev_state_enter(spa, SCL_NONE);
		spa_async_remove(spa, spa->spa_root_vdev);
		for (int i = 0; i < spa->spa_l2cache.sav_count; i++)
			spa_async_remove(spa, spa->spa_l2cache.sav_vdevs[i]);
		for (int i = 0; i < spa->spa_spares.sav_count; i++)
			spa_async_remove(spa, spa->spa_spares.sav_vdevs[i]);
		(void) spa_vdev_state_exit(spa, NULL, 0);
	}

	if ((tasks & SPA_ASYNC_AUTOEXPAND) && !spa_suspended(spa)) {
		spa_config_enter(spa, SCL_CONFIG, FTAG, RW_READER);
		spa_async_autoexpand(spa, spa->spa_root_vdev);
		spa_config_exit(spa, SCL_CONFIG, FTAG);
	}

	/*
	 * See if any devices need to be probed.
	 */
	if (tasks & SPA_ASYNC_PROBE) {
		spa_vdev_state_enter(spa, SCL_NONE);
		spa_async_probe(spa, spa->spa_root_vdev);
		(void) spa_vdev_state_exit(spa, NULL, 0);
	}

	/*
	 * If any devices are done replacing, detach them.
	 */
	if (tasks & SPA_ASYNC_RESILVER_DONE)
		spa_vdev_resilver_done(spa);

	/*
	 * Kick off a resilver.
	 */
	if (tasks & SPA_ASYNC_RESILVER &&
	    (!dsl_scan_resilvering(dp) ||
	    !spa_feature_is_enabled(dp->dp_spa, SPA_FEATURE_RESILVER_DEFER)))
		dsl_resilver_restart(dp, 0);

	if (tasks & SPA_ASYNC_INITIALIZE_RESTART) {
		mutex_enter(&spa_namespace_lock);
		spa_config_enter(spa, SCL_CONFIG, FTAG, RW_READER);
		vdev_initialize_restart(spa->spa_root_vdev);
		spa_config_exit(spa, SCL_CONFIG, FTAG);
		mutex_exit(&spa_namespace_lock);
	}

	if (tasks & SPA_ASYNC_TRIM_RESTART) {
		mutex_enter(&spa_namespace_lock);
		spa_config_enter(spa, SCL_CONFIG, FTAG, RW_READER);
		vdev_trim_restart(spa->spa_root_vdev);
		spa_config_exit(spa, SCL_CONFIG, FTAG);
		mutex_exit(&spa_namespace_lock);
	}

	if (tasks & SPA_ASYNC_AUTOTRIM_RESTART) {
		mutex_enter(&spa_namespace_lock);
		spa_config_enter(spa, SCL_CONFIG, FTAG, RW_READER);
		vdev_autotrim_restart(spa);
		spa_config_exit(spa, SCL_CONFIG, FTAG);
		mutex_exit(&spa_namespace_lock);
	}

	/*
	 * Let the world know that we're done.
	 */
	mutex_enter(&spa->spa_async_lock);
	spa->spa_async_thread = NULL;
	cv_broadcast(&spa->spa_async_cv);
	mutex_exit(&spa->spa_async_lock);
	thread_exit();
}

void
spa_async_suspend(spa_t *spa)
{
	mutex_enter(&spa->spa_async_lock);
	spa->spa_async_suspended++;
	while (spa->spa_async_thread != NULL)
		cv_wait(&spa->spa_async_cv, &spa->spa_async_lock);
	mutex_exit(&spa->spa_async_lock);

	spa_vdev_remove_suspend(spa);

	zthr_t *condense_thread = spa->spa_condense_zthr;
	if (condense_thread != NULL)
		zthr_cancel(condense_thread);

	zthr_t *discard_thread = spa->spa_checkpoint_discard_zthr;
	if (discard_thread != NULL)
		zthr_cancel(discard_thread);
}

void
spa_async_resume(spa_t *spa)
{
	mutex_enter(&spa->spa_async_lock);
	ASSERT(spa->spa_async_suspended != 0);
	spa->spa_async_suspended--;
	mutex_exit(&spa->spa_async_lock);
	spa_restart_removal(spa);

	zthr_t *condense_thread = spa->spa_condense_zthr;
	if (condense_thread != NULL)
		zthr_resume(condense_thread);

	zthr_t *discard_thread = spa->spa_checkpoint_discard_zthr;
	if (discard_thread != NULL)
		zthr_resume(discard_thread);
}

static boolean_t
spa_async_tasks_pending(spa_t *spa)
{
	uint_t non_config_tasks;
	uint_t config_task;
	boolean_t config_task_suspended;

	non_config_tasks = spa->spa_async_tasks & ~SPA_ASYNC_CONFIG_UPDATE;
	config_task = spa->spa_async_tasks & SPA_ASYNC_CONFIG_UPDATE;
	if (spa->spa_ccw_fail_time == 0) {
		config_task_suspended = B_FALSE;
	} else {
		config_task_suspended =
		    (gethrtime() - spa->spa_ccw_fail_time) <
		    ((hrtime_t)zfs_ccw_retry_interval * NANOSEC);
	}

	return (non_config_tasks || (config_task && !config_task_suspended));
}

static void
spa_async_dispatch(spa_t *spa)
{
	mutex_enter(&spa->spa_async_lock);
	if (spa_async_tasks_pending(spa) &&
	    !spa->spa_async_suspended &&
	    spa->spa_async_thread == NULL &&
	    rootdir != NULL)
		spa->spa_async_thread = thread_create(NULL, 0,
		    spa_async_thread, spa, 0, &p0, TS_RUN, maxclsyspri);
	mutex_exit(&spa->spa_async_lock);
}

void
spa_async_request(spa_t *spa, int task)
{
	zfs_dbgmsg("spa=%s async request task=%u", spa->spa_name, task);
	mutex_enter(&spa->spa_async_lock);
	spa->spa_async_tasks |= task;
	mutex_exit(&spa->spa_async_lock);
}

/*
 * ==========================================================================
 * SPA syncing routines
 * ==========================================================================
 */

static int
bpobj_enqueue_cb(void *arg, const blkptr_t *bp, dmu_tx_t *tx)
{
	bpobj_t *bpo = arg;
	bpobj_enqueue(bpo, bp, tx);
	return (0);
}

static int
spa_free_sync_cb(void *arg, const blkptr_t *bp, dmu_tx_t *tx)
{
	zio_t *zio = arg;

	zio_nowait(zio_free_sync(zio, zio->io_spa, dmu_tx_get_txg(tx), bp,
	    zio->io_flags));
	return (0);
}

/*
 * Note: this simple function is not inlined to make it easier to dtrace the
 * amount of time spent syncing frees.
 */
static void
spa_sync_frees(spa_t *spa, bplist_t *bpl, dmu_tx_t *tx)
{
	zio_t *zio = zio_root(spa, NULL, NULL, 0);
	bplist_iterate(bpl, spa_free_sync_cb, zio, tx);
	VERIFY(zio_wait(zio) == 0);
}

/*
 * Note: this simple function is not inlined to make it easier to dtrace the
 * amount of time spent syncing deferred frees.
 */
static void
spa_sync_deferred_frees(spa_t *spa, dmu_tx_t *tx)
{
	if (spa_sync_pass(spa) != 1)
		return;

	zio_t *zio = zio_root(spa, NULL, NULL, 0);
	VERIFY3U(bpobj_iterate(&spa->spa_deferred_bpobj,
	    spa_free_sync_cb, zio, tx), ==, 0);
	VERIFY0(zio_wait(zio));
}

static void
spa_sync_nvlist(spa_t *spa, uint64_t obj, nvlist_t *nv, dmu_tx_t *tx)
{
	char *packed = NULL;
	size_t bufsize;
	size_t nvsize = 0;
	dmu_buf_t *db;

	VERIFY(nvlist_size(nv, &nvsize, NV_ENCODE_XDR) == 0);

	/*
	 * Write full (SPA_CONFIG_BLOCKSIZE) blocks of configuration
	 * information.  This avoids the dmu_buf_will_dirty() path and
	 * saves us a pre-read to get data we don't actually care about.
	 */
	bufsize = P2ROUNDUP((uint64_t)nvsize, SPA_CONFIG_BLOCKSIZE);
	packed = vmem_alloc(bufsize, KM_SLEEP);

	VERIFY(nvlist_pack(nv, &packed, &nvsize, NV_ENCODE_XDR,
	    KM_SLEEP) == 0);
	bzero(packed + nvsize, bufsize - nvsize);

	dmu_write(spa->spa_meta_objset, obj, 0, bufsize, packed, tx);

	vmem_free(packed, bufsize);

	VERIFY(0 == dmu_bonus_hold(spa->spa_meta_objset, obj, FTAG, &db));
	dmu_buf_will_dirty(db, tx);
	*(uint64_t *)db->db_data = nvsize;
	dmu_buf_rele(db, FTAG);
}

static void
spa_sync_aux_dev(spa_t *spa, spa_aux_vdev_t *sav, dmu_tx_t *tx,
    const char *config, const char *entry)
{
	nvlist_t *nvroot;
	nvlist_t **list;
	int i;

	if (!sav->sav_sync)
		return;

	/*
	 * Update the MOS nvlist describing the list of available devices.
	 * spa_validate_aux() will have already made sure this nvlist is
	 * valid and the vdevs are labeled appropriately.
	 */
	if (sav->sav_object == 0) {
		sav->sav_object = dmu_object_alloc(spa->spa_meta_objset,
		    DMU_OT_PACKED_NVLIST, 1 << 14, DMU_OT_PACKED_NVLIST_SIZE,
		    sizeof (uint64_t), tx);
		VERIFY(zap_update(spa->spa_meta_objset,
		    DMU_POOL_DIRECTORY_OBJECT, entry, sizeof (uint64_t), 1,
		    &sav->sav_object, tx) == 0);
	}

	VERIFY(nvlist_alloc(&nvroot, NV_UNIQUE_NAME, KM_SLEEP) == 0);
	if (sav->sav_count == 0) {
		VERIFY(nvlist_add_nvlist_array(nvroot, config, NULL, 0) == 0);
	} else {
		list = kmem_alloc(sav->sav_count*sizeof (void *), KM_SLEEP);
		for (i = 0; i < sav->sav_count; i++)
			list[i] = vdev_config_generate(spa, sav->sav_vdevs[i],
			    B_FALSE, VDEV_CONFIG_L2CACHE);
		VERIFY(nvlist_add_nvlist_array(nvroot, config, list,
		    sav->sav_count) == 0);
		for (i = 0; i < sav->sav_count; i++)
			nvlist_free(list[i]);
		kmem_free(list, sav->sav_count * sizeof (void *));
	}

	spa_sync_nvlist(spa, sav->sav_object, nvroot, tx);
	nvlist_free(nvroot);

	sav->sav_sync = B_FALSE;
}

/*
 * Rebuild spa's all-vdev ZAP from the vdev ZAPs indicated in each vdev_t.
 * The all-vdev ZAP must be empty.
 */
static void
spa_avz_build(vdev_t *vd, uint64_t avz, dmu_tx_t *tx)
{
	spa_t *spa = vd->vdev_spa;

	if (vd->vdev_top_zap != 0) {
		VERIFY0(zap_add_int(spa->spa_meta_objset, avz,
		    vd->vdev_top_zap, tx));
	}
	if (vd->vdev_leaf_zap != 0) {
		VERIFY0(zap_add_int(spa->spa_meta_objset, avz,
		    vd->vdev_leaf_zap, tx));
	}
	for (uint64_t i = 0; i < vd->vdev_children; i++) {
		spa_avz_build(vd->vdev_child[i], avz, tx);
	}
}

static void
spa_sync_config_object(spa_t *spa, dmu_tx_t *tx)
{
	nvlist_t *config;

	/*
	 * If the pool is being imported from a pre-per-vdev-ZAP version of ZFS,
	 * its config may not be dirty but we still need to build per-vdev ZAPs.
	 * Similarly, if the pool is being assembled (e.g. after a split), we
	 * need to rebuild the AVZ although the config may not be dirty.
	 */
	if (list_is_empty(&spa->spa_config_dirty_list) &&
	    spa->spa_avz_action == AVZ_ACTION_NONE)
		return;

	spa_config_enter(spa, SCL_STATE, FTAG, RW_READER);

	ASSERT(spa->spa_avz_action == AVZ_ACTION_NONE ||
	    spa->spa_avz_action == AVZ_ACTION_INITIALIZE ||
	    spa->spa_all_vdev_zaps != 0);

	if (spa->spa_avz_action == AVZ_ACTION_REBUILD) {
		/* Make and build the new AVZ */
		uint64_t new_avz = zap_create(spa->spa_meta_objset,
		    DMU_OTN_ZAP_METADATA, DMU_OT_NONE, 0, tx);
		spa_avz_build(spa->spa_root_vdev, new_avz, tx);

		/* Diff old AVZ with new one */
		zap_cursor_t zc;
		zap_attribute_t za;

		for (zap_cursor_init(&zc, spa->spa_meta_objset,
		    spa->spa_all_vdev_zaps);
		    zap_cursor_retrieve(&zc, &za) == 0;
		    zap_cursor_advance(&zc)) {
			uint64_t vdzap = za.za_first_integer;
			if (zap_lookup_int(spa->spa_meta_objset, new_avz,
			    vdzap) == ENOENT) {
				/*
				 * ZAP is listed in old AVZ but not in new one;
				 * destroy it
				 */
				VERIFY0(zap_destroy(spa->spa_meta_objset, vdzap,
				    tx));
			}
		}

		zap_cursor_fini(&zc);

		/* Destroy the old AVZ */
		VERIFY0(zap_destroy(spa->spa_meta_objset,
		    spa->spa_all_vdev_zaps, tx));

		/* Replace the old AVZ in the dir obj with the new one */
		VERIFY0(zap_update(spa->spa_meta_objset,
		    DMU_POOL_DIRECTORY_OBJECT, DMU_POOL_VDEV_ZAP_MAP,
		    sizeof (new_avz), 1, &new_avz, tx));

		spa->spa_all_vdev_zaps = new_avz;
	} else if (spa->spa_avz_action == AVZ_ACTION_DESTROY) {
		zap_cursor_t zc;
		zap_attribute_t za;

		/* Walk through the AVZ and destroy all listed ZAPs */
		for (zap_cursor_init(&zc, spa->spa_meta_objset,
		    spa->spa_all_vdev_zaps);
		    zap_cursor_retrieve(&zc, &za) == 0;
		    zap_cursor_advance(&zc)) {
			uint64_t zap = za.za_first_integer;
			VERIFY0(zap_destroy(spa->spa_meta_objset, zap, tx));
		}

		zap_cursor_fini(&zc);

		/* Destroy and unlink the AVZ itself */
		VERIFY0(zap_destroy(spa->spa_meta_objset,
		    spa->spa_all_vdev_zaps, tx));
		VERIFY0(zap_remove(spa->spa_meta_objset,
		    DMU_POOL_DIRECTORY_OBJECT, DMU_POOL_VDEV_ZAP_MAP, tx));
		spa->spa_all_vdev_zaps = 0;
	}

	if (spa->spa_all_vdev_zaps == 0) {
		spa->spa_all_vdev_zaps = zap_create_link(spa->spa_meta_objset,
		    DMU_OTN_ZAP_METADATA, DMU_POOL_DIRECTORY_OBJECT,
		    DMU_POOL_VDEV_ZAP_MAP, tx);
	}
	spa->spa_avz_action = AVZ_ACTION_NONE;

	/* Create ZAPs for vdevs that don't have them. */
	vdev_construct_zaps(spa->spa_root_vdev, tx);

	config = spa_config_generate(spa, spa->spa_root_vdev,
	    dmu_tx_get_txg(tx), B_FALSE);

	/*
	 * If we're upgrading the spa version then make sure that
	 * the config object gets updated with the correct version.
	 */
	if (spa->spa_ubsync.ub_version < spa->spa_uberblock.ub_version)
		fnvlist_add_uint64(config, ZPOOL_CONFIG_VERSION,
		    spa->spa_uberblock.ub_version);

	spa_config_exit(spa, SCL_STATE, FTAG);

	nvlist_free(spa->spa_config_syncing);
	spa->spa_config_syncing = config;

	spa_sync_nvlist(spa, spa->spa_config_object, config, tx);
}

static void
spa_sync_version(void *arg, dmu_tx_t *tx)
{
	uint64_t *versionp = arg;
	uint64_t version = *versionp;
	spa_t *spa = dmu_tx_pool(tx)->dp_spa;

	/*
	 * Setting the version is special cased when first creating the pool.
	 */
	ASSERT(tx->tx_txg != TXG_INITIAL);

	ASSERT(SPA_VERSION_IS_SUPPORTED(version));
	ASSERT(version >= spa_version(spa));

	spa->spa_uberblock.ub_version = version;
	vdev_config_dirty(spa->spa_root_vdev);
	spa_history_log_internal(spa, "set", tx, "version=%lld", version);
}

/*
 * Set zpool properties.
 */
static void
spa_sync_props(void *arg, dmu_tx_t *tx)
{
	nvlist_t *nvp = arg;
	spa_t *spa = dmu_tx_pool(tx)->dp_spa;
	objset_t *mos = spa->spa_meta_objset;
	nvpair_t *elem = NULL;

	mutex_enter(&spa->spa_props_lock);

	while ((elem = nvlist_next_nvpair(nvp, elem))) {
		uint64_t intval;
		char *strval, *fname;
		zpool_prop_t prop;
		const char *propname;
		zprop_type_t proptype;
		spa_feature_t fid;

		switch (prop = zpool_name_to_prop(nvpair_name(elem))) {
		case ZPOOL_PROP_INVAL:
			/*
			 * We checked this earlier in spa_prop_validate().
			 */
			ASSERT(zpool_prop_feature(nvpair_name(elem)));

			fname = strchr(nvpair_name(elem), '@') + 1;
			VERIFY0(zfeature_lookup_name(fname, &fid));

			spa_feature_enable(spa, fid, tx);
			spa_history_log_internal(spa, "set", tx,
			    "%s=enabled", nvpair_name(elem));
			break;

		case ZPOOL_PROP_VERSION:
			intval = fnvpair_value_uint64(elem);
			/*
			 * The version is synced separately before other
			 * properties and should be correct by now.
			 */
			ASSERT3U(spa_version(spa), >=, intval);
			break;

		case ZPOOL_PROP_ALTROOT:
			/*
			 * 'altroot' is a non-persistent property. It should
			 * have been set temporarily at creation or import time.
			 */
			ASSERT(spa->spa_root != NULL);
			break;

		case ZPOOL_PROP_READONLY:
		case ZPOOL_PROP_CACHEFILE:
			/*
			 * 'readonly' and 'cachefile' are also non-persisitent
			 * properties.
			 */
			break;
		case ZPOOL_PROP_COMMENT:
			strval = fnvpair_value_string(elem);
			if (spa->spa_comment != NULL)
				spa_strfree(spa->spa_comment);
			spa->spa_comment = spa_strdup(strval);
			/*
			 * We need to dirty the configuration on all the vdevs
			 * so that their labels get updated.  It's unnecessary
			 * to do this for pool creation since the vdev's
			 * configuration has already been dirtied.
			 */
			if (tx->tx_txg != TXG_INITIAL)
				vdev_config_dirty(spa->spa_root_vdev);
			spa_history_log_internal(spa, "set", tx,
			    "%s=%s", nvpair_name(elem), strval);
			break;
		default:
			/*
			 * Set pool property values in the poolprops mos object.
			 */
			if (spa->spa_pool_props_object == 0) {
				spa->spa_pool_props_object =
				    zap_create_link(mos, DMU_OT_POOL_PROPS,
				    DMU_POOL_DIRECTORY_OBJECT, DMU_POOL_PROPS,
				    tx);
			}

			/* normalize the property name */
			propname = zpool_prop_to_name(prop);
			proptype = zpool_prop_get_type(prop);

			if (nvpair_type(elem) == DATA_TYPE_STRING) {
				ASSERT(proptype == PROP_TYPE_STRING);
				strval = fnvpair_value_string(elem);
				VERIFY0(zap_update(mos,
				    spa->spa_pool_props_object, propname,
				    1, strlen(strval) + 1, strval, tx));
				spa_history_log_internal(spa, "set", tx,
				    "%s=%s", nvpair_name(elem), strval);
			} else if (nvpair_type(elem) == DATA_TYPE_UINT64) {
				intval = fnvpair_value_uint64(elem);

				if (proptype == PROP_TYPE_INDEX) {
					const char *unused;
					VERIFY0(zpool_prop_index_to_string(
					    prop, intval, &unused));
				}
				VERIFY0(zap_update(mos,
				    spa->spa_pool_props_object, propname,
				    8, 1, &intval, tx));
				spa_history_log_internal(spa, "set", tx,
				    "%s=%lld", nvpair_name(elem), intval);
			} else {
				ASSERT(0); /* not allowed */
			}

			switch (prop) {
			case ZPOOL_PROP_DELEGATION:
				spa->spa_delegation = intval;
				break;
			case ZPOOL_PROP_BOOTFS:
				spa->spa_bootfs = intval;
				break;
			case ZPOOL_PROP_FAILUREMODE:
				spa->spa_failmode = intval;
				break;
			case ZPOOL_PROP_AUTOTRIM:
				spa->spa_autotrim = intval;
				spa_async_request(spa,
				    SPA_ASYNC_AUTOTRIM_RESTART);
				break;
			case ZPOOL_PROP_AUTOEXPAND:
				spa->spa_autoexpand = intval;
				if (tx->tx_txg != TXG_INITIAL)
					spa_async_request(spa,
					    SPA_ASYNC_AUTOEXPAND);
				break;
			case ZPOOL_PROP_MULTIHOST:
				spa->spa_multihost = intval;
				break;
			case ZPOOL_PROP_DEDUPDITTO:
				spa->spa_dedup_ditto = intval;
				break;
			default:
				break;
			}
		}

	}

	mutex_exit(&spa->spa_props_lock);
}

/*
 * Perform one-time upgrade on-disk changes.  spa_version() does not
 * reflect the new version this txg, so there must be no changes this
 * txg to anything that the upgrade code depends on after it executes.
 * Therefore this must be called after dsl_pool_sync() does the sync
 * tasks.
 */
static void
spa_sync_upgrades(spa_t *spa, dmu_tx_t *tx)
{
	if (spa_sync_pass(spa) != 1)
		return;

	dsl_pool_t *dp = spa->spa_dsl_pool;
	rrw_enter(&dp->dp_config_rwlock, RW_WRITER, FTAG);

	if (spa->spa_ubsync.ub_version < SPA_VERSION_ORIGIN &&
	    spa->spa_uberblock.ub_version >= SPA_VERSION_ORIGIN) {
		dsl_pool_create_origin(dp, tx);

		/* Keeping the origin open increases spa_minref */
		spa->spa_minref += 3;
	}

	if (spa->spa_ubsync.ub_version < SPA_VERSION_NEXT_CLONES &&
	    spa->spa_uberblock.ub_version >= SPA_VERSION_NEXT_CLONES) {
		dsl_pool_upgrade_clones(dp, tx);
	}

	if (spa->spa_ubsync.ub_version < SPA_VERSION_DIR_CLONES &&
	    spa->spa_uberblock.ub_version >= SPA_VERSION_DIR_CLONES) {
		dsl_pool_upgrade_dir_clones(dp, tx);

		/* Keeping the freedir open increases spa_minref */
		spa->spa_minref += 3;
	}

	if (spa->spa_ubsync.ub_version < SPA_VERSION_FEATURES &&
	    spa->spa_uberblock.ub_version >= SPA_VERSION_FEATURES) {
		spa_feature_create_zap_objects(spa, tx);
	}

	/*
	 * LZ4_COMPRESS feature's behaviour was changed to activate_on_enable
	 * when possibility to use lz4 compression for metadata was added
	 * Old pools that have this feature enabled must be upgraded to have
	 * this feature active
	 */
	if (spa->spa_uberblock.ub_version >= SPA_VERSION_FEATURES) {
		boolean_t lz4_en = spa_feature_is_enabled(spa,
		    SPA_FEATURE_LZ4_COMPRESS);
		boolean_t lz4_ac = spa_feature_is_active(spa,
		    SPA_FEATURE_LZ4_COMPRESS);

		if (lz4_en && !lz4_ac)
			spa_feature_incr(spa, SPA_FEATURE_LZ4_COMPRESS, tx);
	}

	/*
	 * If we haven't written the salt, do so now.  Note that the
	 * feature may not be activated yet, but that's fine since
	 * the presence of this ZAP entry is backwards compatible.
	 */
	if (zap_contains(spa->spa_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
	    DMU_POOL_CHECKSUM_SALT) == ENOENT) {
		VERIFY0(zap_add(spa->spa_meta_objset,
		    DMU_POOL_DIRECTORY_OBJECT, DMU_POOL_CHECKSUM_SALT, 1,
		    sizeof (spa->spa_cksum_salt.zcs_bytes),
		    spa->spa_cksum_salt.zcs_bytes, tx));
	}

	rrw_exit(&dp->dp_config_rwlock, FTAG);
}

static void
vdev_indirect_state_sync_verify(vdev_t *vd)
{
	ASSERTV(vdev_indirect_mapping_t *vim = vd->vdev_indirect_mapping);
	ASSERTV(vdev_indirect_births_t *vib = vd->vdev_indirect_births);

	if (vd->vdev_ops == &vdev_indirect_ops) {
		ASSERT(vim != NULL);
		ASSERT(vib != NULL);
	}

	uint64_t obsolete_sm_object = 0;
	ASSERT0(vdev_obsolete_sm_object(vd, &obsolete_sm_object));
	if (obsolete_sm_object != 0) {
		ASSERT(vd->vdev_obsolete_sm != NULL);
		ASSERT(vd->vdev_removing ||
		    vd->vdev_ops == &vdev_indirect_ops);
		ASSERT(vdev_indirect_mapping_num_entries(vim) > 0);
		ASSERT(vdev_indirect_mapping_bytes_mapped(vim) > 0);
		ASSERT3U(obsolete_sm_object, ==,
		    space_map_object(vd->vdev_obsolete_sm));
		ASSERT3U(vdev_indirect_mapping_bytes_mapped(vim), >=,
		    space_map_allocated(vd->vdev_obsolete_sm));
	}
	ASSERT(vd->vdev_obsolete_segments != NULL);

	/*
	 * Since frees / remaps to an indirect vdev can only
	 * happen in syncing context, the obsolete segments
	 * tree must be empty when we start syncing.
	 */
	ASSERT0(range_tree_space(vd->vdev_obsolete_segments));
}

/*
 * Set the top-level vdev's max queue depth. Evaluate each top-level's
 * async write queue depth in case it changed. The max queue depth will
 * not change in the middle of syncing out this txg.
 */
static void
spa_sync_adjust_vdev_max_queue_depth(spa_t *spa)
{
	ASSERT(spa_writeable(spa));

	vdev_t *rvd = spa->spa_root_vdev;
	uint32_t max_queue_depth = zfs_vdev_async_write_max_active *
	    zfs_vdev_queue_depth_pct / 100;
	metaslab_class_t *normal = spa_normal_class(spa);
	metaslab_class_t *special = spa_special_class(spa);
	metaslab_class_t *dedup = spa_dedup_class(spa);

	uint64_t slots_per_allocator = 0;
	for (int c = 0; c < rvd->vdev_children; c++) {
		vdev_t *tvd = rvd->vdev_child[c];

		metaslab_group_t *mg = tvd->vdev_mg;
		if (mg == NULL || !metaslab_group_initialized(mg))
			continue;

		metaslab_class_t *mc = mg->mg_class;
		if (mc != normal && mc != special && mc != dedup)
			continue;

		/*
		 * It is safe to do a lock-free check here because only async
		 * allocations look at mg_max_alloc_queue_depth, and async
		 * allocations all happen from spa_sync().
		 */
		for (int i = 0; i < spa->spa_alloc_count; i++)
			ASSERT0(zfs_refcount_count(
			    &(mg->mg_alloc_queue_depth[i])));
		mg->mg_max_alloc_queue_depth = max_queue_depth;

		for (int i = 0; i < spa->spa_alloc_count; i++) {
			mg->mg_cur_max_alloc_queue_depth[i] =
			    zfs_vdev_def_queue_depth;
		}
		slots_per_allocator += zfs_vdev_def_queue_depth;
	}

	for (int i = 0; i < spa->spa_alloc_count; i++) {
		ASSERT0(zfs_refcount_count(&normal->mc_alloc_slots[i]));
		ASSERT0(zfs_refcount_count(&special->mc_alloc_slots[i]));
		ASSERT0(zfs_refcount_count(&dedup->mc_alloc_slots[i]));
		normal->mc_alloc_max_slots[i] = slots_per_allocator;
		special->mc_alloc_max_slots[i] = slots_per_allocator;
		dedup->mc_alloc_max_slots[i] = slots_per_allocator;
	}
	normal->mc_alloc_throttle_enabled = zio_dva_throttle_enabled;
	special->mc_alloc_throttle_enabled = zio_dva_throttle_enabled;
	dedup->mc_alloc_throttle_enabled = zio_dva_throttle_enabled;
}

static void
spa_sync_condense_indirect(spa_t *spa, dmu_tx_t *tx)
{
	ASSERT(spa_writeable(spa));

	vdev_t *rvd = spa->spa_root_vdev;
	for (int c = 0; c < rvd->vdev_children; c++) {
		vdev_t *vd = rvd->vdev_child[c];
		vdev_indirect_state_sync_verify(vd);

		if (vdev_indirect_should_condense(vd)) {
			spa_condense_indirect_start_sync(vd, tx);
			break;
		}
	}
}

static void
spa_sync_iterate_to_convergence(spa_t *spa, dmu_tx_t *tx)
{
	objset_t *mos = spa->spa_meta_objset;
	dsl_pool_t *dp = spa->spa_dsl_pool;
	uint64_t txg = tx->tx_txg;
	bplist_t *free_bpl = &spa->spa_free_bplist[txg & TXG_MASK];

	do {
		int pass = ++spa->spa_sync_pass;

		spa_sync_config_object(spa, tx);
		spa_sync_aux_dev(spa, &spa->spa_spares, tx,
		    ZPOOL_CONFIG_SPARES, DMU_POOL_SPARES);
		spa_sync_aux_dev(spa, &spa->spa_l2cache, tx,
		    ZPOOL_CONFIG_L2CACHE, DMU_POOL_L2CACHE);
		spa_errlog_sync(spa, txg);
		dsl_pool_sync(dp, txg);

		if (pass < zfs_sync_pass_deferred_free) {
			spa_sync_frees(spa, free_bpl, tx);
		} else {
			/*
			 * We can not defer frees in pass 1, because
			 * we sync the deferred frees later in pass 1.
			 */
			ASSERT3U(pass, >, 1);
			bplist_iterate(free_bpl, bpobj_enqueue_cb,
			    &spa->spa_deferred_bpobj, tx);
		}

		ddt_sync(spa, txg);
		dsl_scan_sync(dp, tx);
		svr_sync(spa, tx);
		spa_sync_upgrades(spa, tx);

		vdev_t *vd = NULL;
		while ((vd = txg_list_remove(&spa->spa_vdev_txg_list, txg))
		    != NULL)
			vdev_sync(vd, txg);

		/*
		 * Note: We need to check if the MOS is dirty because we could
		 * have marked the MOS dirty without updating the uberblock
		 * (e.g. if we have sync tasks but no dirty user data). We need
		 * to check the uberblock's rootbp because it is updated if we
		 * have synced out dirty data (though in this case the MOS will
		 * most likely also be dirty due to second order effects, we
		 * don't want to rely on that here).
		 */
		if (pass == 1 &&
		    spa->spa_uberblock.ub_rootbp.blk_birth < txg &&
		    !dmu_objset_is_dirty(mos, txg)) {
			/*
			 * Nothing changed on the first pass, therefore this
			 * TXG is a no-op. Avoid syncing deferred frees, so
			 * that we can keep this TXG as a no-op.
			 */
			ASSERT(txg_list_empty(&dp->dp_dirty_datasets, txg));
			ASSERT(txg_list_empty(&dp->dp_dirty_dirs, txg));
			ASSERT(txg_list_empty(&dp->dp_sync_tasks, txg));
			ASSERT(txg_list_empty(&dp->dp_early_sync_tasks, txg));
			break;
		}

		spa_sync_deferred_frees(spa, tx);
	} while (dmu_objset_is_dirty(mos, txg));
}

/*
 * Rewrite the vdev configuration (which includes the uberblock) to
 * commit the transaction group.
 *
 * If there are no dirty vdevs, we sync the uberblock to a few random
 * top-level vdevs that are known to be visible in the config cache
 * (see spa_vdev_add() for a complete description). If there *are* dirty
 * vdevs, sync the uberblock to all vdevs.
 */
static void
spa_sync_rewrite_vdev_config(spa_t *spa, dmu_tx_t *tx)
{
	vdev_t *rvd = spa->spa_root_vdev;
	uint64_t txg = tx->tx_txg;

	for (;;) {
		int error = 0;

		/*
		 * We hold SCL_STATE to prevent vdev open/close/etc.
		 * while we're attempting to write the vdev labels.
		 */
		spa_config_enter(spa, SCL_STATE, FTAG, RW_READER);

		if (list_is_empty(&spa->spa_config_dirty_list)) {
			vdev_t *svd[SPA_SYNC_MIN_VDEVS] = { NULL };
			int svdcount = 0;
			int children = rvd->vdev_children;
			int c0 = spa_get_random(children);

			for (int c = 0; c < children; c++) {
				vdev_t *vd =
				    rvd->vdev_child[(c0 + c) % children];

				/* Stop when revisiting the first vdev */
				if (c > 0 && svd[0] == vd)
					break;

				if (vd->vdev_ms_array == 0 ||
				    vd->vdev_islog ||
				    !vdev_is_concrete(vd))
					continue;

				svd[svdcount++] = vd;
				if (svdcount == SPA_SYNC_MIN_VDEVS)
					break;
			}
			error = vdev_config_sync(svd, svdcount, txg);
		} else {
			error = vdev_config_sync(rvd->vdev_child,
			    rvd->vdev_children, txg);
		}

		if (error == 0)
			spa->spa_last_synced_guid = rvd->vdev_guid;

		spa_config_exit(spa, SCL_STATE, FTAG);

		if (error == 0)
			break;
		zio_suspend(spa, NULL, ZIO_SUSPEND_IOERR);
		zio_resume_wait(spa);
	}
}

/*
 * Sync the specified transaction group.  New blocks may be dirtied as
 * part of the process, so we iterate until it converges.
 */
void
spa_sync(spa_t *spa, uint64_t txg)
{
	vdev_t *vd = NULL;

	VERIFY(spa_writeable(spa));

	/*
	 * Wait for i/os issued in open context that need to complete
	 * before this txg syncs.
	 */
	(void) zio_wait(spa->spa_txg_zio[txg & TXG_MASK]);
	spa->spa_txg_zio[txg & TXG_MASK] = zio_root(spa, NULL, NULL,
	    ZIO_FLAG_CANFAIL);

	/*
	 * Lock out configuration changes.
	 */
	spa_config_enter(spa, SCL_CONFIG, FTAG, RW_READER);

	spa->spa_syncing_txg = txg;
	spa->spa_sync_pass = 0;

	for (int i = 0; i < spa->spa_alloc_count; i++) {
		mutex_enter(&spa->spa_alloc_locks[i]);
		VERIFY0(avl_numnodes(&spa->spa_alloc_trees[i]));
		mutex_exit(&spa->spa_alloc_locks[i]);
	}

	/*
	 * If there are any pending vdev state changes, convert them
	 * into config changes that go out with this transaction group.
	 */
	spa_config_enter(spa, SCL_STATE, FTAG, RW_READER);
	while (list_head(&spa->spa_state_dirty_list) != NULL) {
		/*
		 * We need the write lock here because, for aux vdevs,
		 * calling vdev_config_dirty() modifies sav_config.
		 * This is ugly and will become unnecessary when we
		 * eliminate the aux vdev wart by integrating all vdevs
		 * into the root vdev tree.
		 */
		spa_config_exit(spa, SCL_CONFIG | SCL_STATE, FTAG);
		spa_config_enter(spa, SCL_CONFIG | SCL_STATE, FTAG, RW_WRITER);
		while ((vd = list_head(&spa->spa_state_dirty_list)) != NULL) {
			vdev_state_clean(vd);
			vdev_config_dirty(vd);
		}
		spa_config_exit(spa, SCL_CONFIG | SCL_STATE, FTAG);
		spa_config_enter(spa, SCL_CONFIG | SCL_STATE, FTAG, RW_READER);
	}
	spa_config_exit(spa, SCL_STATE, FTAG);

	dsl_pool_t *dp = spa->spa_dsl_pool;
	dmu_tx_t *tx = dmu_tx_create_assigned(dp, txg);

	spa->spa_sync_starttime = gethrtime();
	taskq_cancel_id(system_delay_taskq, spa->spa_deadman_tqid);
	spa->spa_deadman_tqid = taskq_dispatch_delay(system_delay_taskq,
	    spa_deadman, spa, TQ_SLEEP, ddi_get_lbolt() +
	    NSEC_TO_TICK(spa->spa_deadman_synctime));

	/*
	 * If we are upgrading to SPA_VERSION_RAIDZ_DEFLATE this txg,
	 * set spa_deflate if we have no raid-z vdevs.
	 */
	if (spa->spa_ubsync.ub_version < SPA_VERSION_RAIDZ_DEFLATE &&
	    spa->spa_uberblock.ub_version >= SPA_VERSION_RAIDZ_DEFLATE) {
		vdev_t *rvd = spa->spa_root_vdev;

		int i;
		for (i = 0; i < rvd->vdev_children; i++) {
			vd = rvd->vdev_child[i];
			if (vd->vdev_deflate_ratio != SPA_MINBLOCKSIZE)
				break;
		}
		if (i == rvd->vdev_children) {
			spa->spa_deflate = TRUE;
			VERIFY0(zap_add(spa->spa_meta_objset,
			    DMU_POOL_DIRECTORY_OBJECT, DMU_POOL_DEFLATE,
			    sizeof (uint64_t), 1, &spa->spa_deflate, tx));
		}
	}

	spa_sync_adjust_vdev_max_queue_depth(spa);

	spa_sync_condense_indirect(spa, tx);

	spa_sync_iterate_to_convergence(spa, tx);

#ifdef ZFS_DEBUG
	if (!list_is_empty(&spa->spa_config_dirty_list)) {
	/*
	 * Make sure that the number of ZAPs for all the vdevs matches
	 * the number of ZAPs in the per-vdev ZAP list. This only gets
	 * called if the config is dirty; otherwise there may be
	 * outstanding AVZ operations that weren't completed in
	 * spa_sync_config_object.
	 */
		uint64_t all_vdev_zap_entry_count;
		ASSERT0(zap_count(spa->spa_meta_objset,
		    spa->spa_all_vdev_zaps, &all_vdev_zap_entry_count));
		ASSERT3U(vdev_count_verify_zaps(spa->spa_root_vdev), ==,
		    all_vdev_zap_entry_count);
	}
#endif

	if (spa->spa_vdev_removal != NULL) {
		ASSERT0(spa->spa_vdev_removal->svr_bytes_done[txg & TXG_MASK]);
	}

	spa_sync_rewrite_vdev_config(spa, tx);
	dmu_tx_commit(tx);

	taskq_cancel_id(system_delay_taskq, spa->spa_deadman_tqid);
	spa->spa_deadman_tqid = 0;

	/*
	 * Clear the dirty config list.
	 */
	while ((vd = list_head(&spa->spa_config_dirty_list)) != NULL)
		vdev_config_clean(vd);

	/*
	 * Now that the new config has synced transactionally,
	 * let it become visible to the config cache.
	 */
	if (spa->spa_config_syncing != NULL) {
		spa_config_set(spa, spa->spa_config_syncing);
		spa->spa_config_txg = txg;
		spa->spa_config_syncing = NULL;
	}

	dsl_pool_sync_done(dp, txg);

	for (int i = 0; i < spa->spa_alloc_count; i++) {
		mutex_enter(&spa->spa_alloc_locks[i]);
		VERIFY0(avl_numnodes(&spa->spa_alloc_trees[i]));
		mutex_exit(&spa->spa_alloc_locks[i]);
	}

	/*
	 * Update usable space statistics.
	 */
	while ((vd = txg_list_remove(&spa->spa_vdev_txg_list, TXG_CLEAN(txg)))
	    != NULL)
		vdev_sync_done(vd, txg);

	spa_update_dspace(spa);

	/*
	 * It had better be the case that we didn't dirty anything
	 * since vdev_config_sync().
	 */
	ASSERT(txg_list_empty(&dp->dp_dirty_datasets, txg));
	ASSERT(txg_list_empty(&dp->dp_dirty_dirs, txg));
	ASSERT(txg_list_empty(&spa->spa_vdev_txg_list, txg));

	while (zfs_pause_spa_sync)
		delay(1);

	spa->spa_sync_pass = 0;

	/*
	 * Update the last synced uberblock here. We want to do this at
	 * the end of spa_sync() so that consumers of spa_last_synced_txg()
	 * will be guaranteed that all the processing associated with
	 * that txg has been completed.
	 */
	spa->spa_ubsync = spa->spa_uberblock;
	spa_config_exit(spa, SCL_CONFIG, FTAG);

	spa_handle_ignored_writes(spa);

	/*
	 * If any async tasks have been requested, kick them off.
	 */
	spa_async_dispatch(spa);
}

/*
 * Sync all pools.  We don't want to hold the namespace lock across these
 * operations, so we take a reference on the spa_t and drop the lock during the
 * sync.
 */
void
spa_sync_allpools(void)
{
	spa_t *spa = NULL;
	mutex_enter(&spa_namespace_lock);
	while ((spa = spa_next(spa)) != NULL) {
		if (spa_state(spa) != POOL_STATE_ACTIVE ||
		    !spa_writeable(spa) || spa_suspended(spa))
			continue;
		spa_open_ref(spa, FTAG);
		mutex_exit(&spa_namespace_lock);
		txg_wait_synced(spa_get_dsl(spa), 0);
		mutex_enter(&spa_namespace_lock);
		spa_close(spa, FTAG);
	}
	mutex_exit(&spa_namespace_lock);
}

/*
 * ==========================================================================
 * Miscellaneous routines
 * ==========================================================================
 */

/*
 * Remove all pools in the system.
 */
void
spa_evict_all(void)
{
	spa_t *spa;

	/*
	 * Remove all cached state.  All pools should be closed now,
	 * so every spa in the AVL tree should be unreferenced.
	 */
	mutex_enter(&spa_namespace_lock);
	while ((spa = spa_next(NULL)) != NULL) {
		/*
		 * Stop async tasks.  The async thread may need to detach
		 * a device that's been replaced, which requires grabbing
		 * spa_namespace_lock, so we must drop it here.
		 */
		spa_open_ref(spa, FTAG);
		mutex_exit(&spa_namespace_lock);
		spa_async_suspend(spa);
		mutex_enter(&spa_namespace_lock);
		spa_close(spa, FTAG);

		if (spa->spa_state != POOL_STATE_UNINITIALIZED) {
			spa_unload(spa);
			spa_deactivate(spa);
		}
		spa_remove(spa);
	}
	mutex_exit(&spa_namespace_lock);
}

vdev_t *
spa_lookup_by_guid(spa_t *spa, uint64_t guid, boolean_t aux)
{
	vdev_t *vd;
	int i;

	if ((vd = vdev_lookup_by_guid(spa->spa_root_vdev, guid)) != NULL)
		return (vd);

	if (aux) {
		for (i = 0; i < spa->spa_l2cache.sav_count; i++) {
			vd = spa->spa_l2cache.sav_vdevs[i];
			if (vd->vdev_guid == guid)
				return (vd);
		}

		for (i = 0; i < spa->spa_spares.sav_count; i++) {
			vd = spa->spa_spares.sav_vdevs[i];
			if (vd->vdev_guid == guid)
				return (vd);
		}
	}

	return (NULL);
}

void
spa_upgrade(spa_t *spa, uint64_t version)
{
	ASSERT(spa_writeable(spa));

	spa_config_enter(spa, SCL_ALL, FTAG, RW_WRITER);

	/*
	 * This should only be called for a non-faulted pool, and since a
	 * future version would result in an unopenable pool, this shouldn't be
	 * possible.
	 */
	ASSERT(SPA_VERSION_IS_SUPPORTED(spa->spa_uberblock.ub_version));
	ASSERT3U(version, >=, spa->spa_uberblock.ub_version);

	spa->spa_uberblock.ub_version = version;
	vdev_config_dirty(spa->spa_root_vdev);

	spa_config_exit(spa, SCL_ALL, FTAG);

	txg_wait_synced(spa_get_dsl(spa), 0);
}

boolean_t
spa_has_spare(spa_t *spa, uint64_t guid)
{
	int i;
	uint64_t spareguid;
	spa_aux_vdev_t *sav = &spa->spa_spares;

	for (i = 0; i < sav->sav_count; i++)
		if (sav->sav_vdevs[i]->vdev_guid == guid)
			return (B_TRUE);

	for (i = 0; i < sav->sav_npending; i++) {
		if (nvlist_lookup_uint64(sav->sav_pending[i], ZPOOL_CONFIG_GUID,
		    &spareguid) == 0 && spareguid == guid)
			return (B_TRUE);
	}

	return (B_FALSE);
}

/*
 * Check if a pool has an active shared spare device.
 * Note: reference count of an active spare is 2, as a spare and as a replace
 */
static boolean_t
spa_has_active_shared_spare(spa_t *spa)
{
	int i, refcnt;
	uint64_t pool;
	spa_aux_vdev_t *sav = &spa->spa_spares;

	for (i = 0; i < sav->sav_count; i++) {
		if (spa_spare_exists(sav->sav_vdevs[i]->vdev_guid, &pool,
		    &refcnt) && pool != 0ULL && pool == spa_guid(spa) &&
		    refcnt > 2)
			return (B_TRUE);
	}

	return (B_FALSE);
}

sysevent_t *
spa_event_create(spa_t *spa, vdev_t *vd, nvlist_t *hist_nvl, const char *name)
{
	sysevent_t *ev = NULL;
#ifdef _KERNEL
	nvlist_t *resource;

	resource = zfs_event_create(spa, vd, FM_SYSEVENT_CLASS, name, hist_nvl);
	if (resource) {
		ev = kmem_alloc(sizeof (sysevent_t), KM_SLEEP);
		ev->resource = resource;
	}
#endif
	return (ev);
}

void
spa_event_post(sysevent_t *ev)
{
#ifdef _KERNEL
	if (ev) {
		zfs_zevent_post(ev->resource, NULL, zfs_zevent_post_cb);
		kmem_free(ev, sizeof (*ev));
	}
#endif
}

/*
 * Post a zevent corresponding to the given sysevent.   The 'name' must be one
 * of the event definitions in sys/sysevent/eventdefs.h.  The payload will be
 * filled in from the spa and (optionally) the vdev.  This doesn't do anything
 * in the userland libzpool, as we don't want consumers to misinterpret ztest
 * or zdb as real changes.
 */
void
spa_event_notify(spa_t *spa, vdev_t *vd, nvlist_t *hist_nvl, const char *name)
{
	spa_event_post(spa_event_create(spa, vd, hist_nvl, name));
}

#if defined(_KERNEL)
/* state manipulation functions */
EXPORT_SYMBOL(spa_open);
EXPORT_SYMBOL(spa_open_rewind);
EXPORT_SYMBOL(spa_get_stats);
EXPORT_SYMBOL(spa_create);
EXPORT_SYMBOL(spa_import);
EXPORT_SYMBOL(spa_tryimport);
EXPORT_SYMBOL(spa_destroy);
EXPORT_SYMBOL(spa_export);
EXPORT_SYMBOL(spa_reset);
EXPORT_SYMBOL(spa_async_request);
EXPORT_SYMBOL(spa_async_suspend);
EXPORT_SYMBOL(spa_async_resume);
EXPORT_SYMBOL(spa_inject_addref);
EXPORT_SYMBOL(spa_inject_delref);
EXPORT_SYMBOL(spa_scan_stat_init);
EXPORT_SYMBOL(spa_scan_get_stats);

/* device maniion */
EXPORT_SYMBOL(spa_vdev_add);
EXPORT_SYMBOL(spa_vdev_attach);
EXPORT_SYMBOL(spa_vdev_detach);
EXPORT_SYMBOL(spa_vdev_setpath);
EXPORT_SYMBOL(spa_vdev_setfru);
EXPORT_SYMBOL(spa_vdev_split_mirror);

/* spare statech is global across all pools) */
EXPORT_SYMBOL(spa_spare_add);
EXPORT_SYMBOL(spa_spare_remove);
EXPORT_SYMBOL(spa_spare_exists);
EXPORT_SYMBOL(spa_spare_activate);

/* L2ARC statech is global across all pools) */
EXPORT_SYMBOL(spa_l2cache_add);
EXPORT_SYMBOL(spa_l2cache_remove);
EXPORT_SYMBOL(spa_l2cache_exists);
EXPORT_SYMBOL(spa_l2cache_activate);
EXPORT_SYMBOL(spa_l2cache_drop);

/* scanning */
EXPORT_SYMBOL(spa_scan);
EXPORT_SYMBOL(spa_scan_stop);

/* spa syncing */
EXPORT_SYMBOL(spa_sync); /* only for DMU use */
EXPORT_SYMBOL(spa_sync_allpools);

/* properties */
EXPORT_SYMBOL(spa_prop_set);
EXPORT_SYMBOL(spa_prop_get);
EXPORT_SYMBOL(spa_prop_clear_bootfs);

/* asynchronous event notification */
EXPORT_SYMBOL(spa_event_notify);
#endif

#if defined(_KERNEL)
module_param(spa_load_verify_maxinflight, int, 0644);
MODULE_PARM_DESC(spa_load_verify_maxinflight,
	"Max concurrent traversal I/Os while verifying pool during import -X");

module_param(spa_load_verify_metadata, int, 0644);
MODULE_PARM_DESC(spa_load_verify_metadata,
	"Set to traverse metadata on pool import");

module_param(spa_load_verify_data, int, 0644);
MODULE_PARM_DESC(spa_load_verify_data,
	"Set to traverse data on pool import");

module_param(spa_load_print_vdev_tree, int, 0644);
MODULE_PARM_DESC(spa_load_print_vdev_tree,
	"Print vdev tree to zfs_dbgmsg during pool import");

/* CSTYLED */
module_param(zio_taskq_batch_pct, uint, 0444);
MODULE_PARM_DESC(zio_taskq_batch_pct,
	"Percentage of CPUs to run an IO worker thread");

/* BEGIN CSTYLED */
module_param(zfs_max_missing_tvds, ulong, 0644);
MODULE_PARM_DESC(zfs_max_missing_tvds,
	"Allow importing pool with up to this number of missing top-level vdevs"
	" (in read-only mode)");
/* END CSTYLED */

#endif