Illumos 5960, 5925

5960 zfs recv should prefetch indirect blocks
5925 zfs receive -o origin=
Reviewed by: Prakash Surya <[email protected]>
Reviewed by: Matthew Ahrens <[email protected]>

References:
  https://www.illumos.org/issues/5960
  https://www.illumos.org/issues/5925
  https://github.com/illumos/illumos-gate/commit/a2cdcdd

Porting notes:
- [lib/libzfs/libzfs_sendrecv.c]
  - b8864a2 Fix gcc cast warnings
  - 325f023 Add linux kernel device support
  - 5c3f61e Increase Linux pipe buffer size on 'zfs receive'
- [module/zfs/zfs_vnops.c]
  - 3558fd7 Prototype/structure update for Linux
  - c12e3a5 Restructure zfs_readdir() to fix regressions
- [module/zfs/zvol.c]
  - Function @zvol_map_block() isn't needed in ZoL
  - 9965059 Prefetch start and end of volumes
- [module/zfs/dmu.c]
  - Fixed ISO C90 - mixed declarations and code
  - Function dmu_prefetch() 'int i' is initialized before
    the following code block (c90 vs. c99)
- [module/zfs/dbuf.c]
  - fc5bb51 Fix stack dbuf_hold_impl()
  - 9b67f60 Illumos 4757, 4913
  - 34229a2 Reduce stack usage for recursive traverse_visitbp()
- [module/zfs/dmu_send.c]
  - Fixed ISO C90 - mixed declarations and code
  - b58986e Use large stacks when available
  - 241b541 Illumos 5959 - clean up per-dataset feature count code
  - 77aef6f Use vmem_alloc() for nvlists
  - 00b4602 Add linux kernel memory support

Ported-by: kernelOfTruth [email protected]
Signed-off-by: Brian Behlendorf <[email protected]>

1 files changed, 25 insertions, 19 deletions

diff --git a/module/zfs/dmu.c b/module/zfs/dmu.c
index f4027af9c..b4133f0e4 100644
--- a/module/zfs/dmu.c
+++ b/module/zfs/dmu.c
@@ -138,7 +138,7 @@ dmu_buf_hold_noread(objset_t *os, uint64_t object, uint64_t offset,
 	err = dnode_hold(os, object, FTAG, &dn);
 	if (err)
 		return (err);
-	blkid = dbuf_whichblock(dn, offset);
+	blkid = dbuf_whichblock(dn, 0, offset);
 	rw_enter(&dn->dn_struct_rwlock, RW_READER);
 	db = dbuf_hold(dn, blkid, tag);
 	rw_exit(&dn->dn_struct_rwlock);
@@ -421,7 +421,7 @@ dmu_buf_hold_array_by_dnode(dnode_t *dn, uint64_t offset, uint64_t length,
 	dbp = kmem_zalloc(sizeof (dmu_buf_t *) * nblks, KM_SLEEP);
 
 	zio = zio_root(dn->dn_objset->os_spa, NULL, NULL, ZIO_FLAG_CANFAIL);
-	blkid = dbuf_whichblock(dn, offset);
+	blkid = dbuf_whichblock(dn, 0, offset);
 	for (i = 0; i < nblks; i++) {
 		dmu_buf_impl_t *db = dbuf_hold(dn, blkid+i, tag);
 		if (db == NULL) {
@@ -522,17 +522,16 @@ dmu_buf_rele_array(dmu_buf_t **dbp_fake, int numbufs, void *tag)
 }
 
 /*
- * Issue prefetch i/os for the given blocks.
+ * Issue prefetch i/os for the given blocks.  If level is greater than 0, the
+ * indirect blocks prefeteched will be those that point to the blocks containing
+ * the data starting at offset, and continuing to offset + len.
  *
- * Note: The assumption is that we *know* these blocks will be needed
- * almost immediately.  Therefore, the prefetch i/os will be issued at
- * ZIO_PRIORITY_SYNC_READ
- *
- * Note: indirect blocks and other metadata will be read synchronously,
- * causing this function to block if they are not already cached.
+ * Note that if the indirect blocks above the blocks being prefetched are not in
+ * cache, they will be asychronously read in.
  */
 void
-dmu_prefetch(objset_t *os, uint64_t object, uint64_t offset, uint64_t len)
+dmu_prefetch(objset_t *os, uint64_t object, int64_t level, uint64_t offset,
+    uint64_t len, zio_priority_t pri)
 {
 	dnode_t *dn;
 	uint64_t blkid;
@@ -548,8 +547,9 @@ dmu_prefetch(objset_t *os, uint64_t object, uint64_t offset, uint64_t len)
 			return;
 
 		rw_enter(&dn->dn_struct_rwlock, RW_READER);
-		blkid = dbuf_whichblock(dn, object * sizeof (dnode_phys_t));
-		dbuf_prefetch(dn, blkid, ZIO_PRIORITY_SYNC_READ);
+		blkid = dbuf_whichblock(dn, level,
+		    object * sizeof (dnode_phys_t));
+		dbuf_prefetch(dn, level, blkid, pri, 0);
 		rw_exit(&dn->dn_struct_rwlock);
 		return;
 	}
@@ -564,10 +564,16 @@ dmu_prefetch(objset_t *os, uint64_t object, uint64_t offset, uint64_t len)
 		return;
 
 	rw_enter(&dn->dn_struct_rwlock, RW_READER);
-	if (dn->dn_datablkshift) {
-		int blkshift = dn->dn_datablkshift;
-		nblks = (P2ROUNDUP(offset + len, 1 << blkshift) -
-		    P2ALIGN(offset, 1 << blkshift)) >> blkshift;
+	/*
+	 * offset + len - 1 is the last byte we want to prefetch for, and offset
+	 * is the first.  Then dbuf_whichblk(dn, level, off + len - 1) is the
+	 * last block we want to prefetch, and dbuf_whichblock(dn, level,
+	 * offset)  is the first.  Then the number we need to prefetch is the
+	 * last - first + 1.
+	 */
+	if (level > 0 || dn->dn_datablkshift != 0) {
+		nblks = dbuf_whichblock(dn, level, offset + len - 1) -
+		    dbuf_whichblock(dn, level, offset) + 1;
 	} else {
 		nblks = (offset < dn->dn_datablksz);
 	}
@@ -575,9 +581,9 @@ dmu_prefetch(objset_t *os, uint64_t object, uint64_t offset, uint64_t len)
 	if (nblks != 0) {
 		int i;
 
-		blkid = dbuf_whichblock(dn, offset);
+		blkid = dbuf_whichblock(dn, level, offset);
 		for (i = 0; i < nblks; i++)
-			dbuf_prefetch(dn, blkid + i, ZIO_PRIORITY_SYNC_READ);
+			dbuf_prefetch(dn, level, blkid + i, pri, 0);
 	}
 
 	rw_exit(&dn->dn_struct_rwlock);
@@ -1293,7 +1299,7 @@ dmu_assign_arcbuf(dmu_buf_t *handle, uint64_t offset, arc_buf_t *buf,
 	DB_DNODE_ENTER(dbuf);
 	dn = DB_DNODE(dbuf);
 	rw_enter(&dn->dn_struct_rwlock, RW_READER);
-	blkid = dbuf_whichblock(dn, offset);
+	blkid = dbuf_whichblock(dn, 0, offset);
 	VERIFY((db = dbuf_hold(dn, blkid, FTAG)) != NULL);
 	rw_exit(&dn->dn_struct_rwlock);
 	DB_DNODE_EXIT(dbuf);