Fix zdb -R with 'b' flag

zdb -R :b fails due to the indirect block being compressed,
and the 'b' and 'd' flag not working in tandem when specified.
Fix the flag parsing code and create a zfs test for zdb -R
block display.  Also fix the zio flags where the dotted notation
for the vdev portion of DVA (i.e. 0.0:offset:length) fails.

Reviewed-by: Ryan Moeller <[email protected]>
Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by: Paul Zuchowski <[email protected]>
Closes #9640
Closes #9729

7 files changed, 376 insertions, 117 deletions

diff --git a/cmd/zdb/zdb.c b/cmd/zdb/zdb.c
index f00df5d57..d6d8b91a9 100644
--- a/cmd/zdb/zdb.c
+++ b/cmd/zdb/zdb.c
@@ -6410,6 +6410,18 @@ dump_zpool(spa_t *spa)
 	}
 }
 
+#define	ZDB_FLAG_CHECKSUM	0x0001
+#define	ZDB_FLAG_DECOMPRESS	0x0002
+#define	ZDB_FLAG_BSWAP		0x0004
+#define	ZDB_FLAG_GBH		0x0008
+#define	ZDB_FLAG_INDIRECT	0x0010
+#define	ZDB_FLAG_RAW		0x0020
+#define	ZDB_FLAG_PRINT_BLKPTR	0x0040
+#define	ZDB_FLAG_VERBOSE	0x0080
+
+static int flagbits[256];
+static char flagbitstr[16];
+
 static void
 zdb_print_blkptr(blkptr_t *bp, int flags)
 {
@@ -6576,6 +6588,83 @@ zdb_parse_block_sizes(char *sizes, uint64_t *lsize, uint64_t *psize)
 
 #define	ZIO_COMPRESS_MASK(alg)	(1ULL << (ZIO_COMPRESS_##alg))
 
+static boolean_t
+zdb_decompress_block(abd_t *pabd, void *buf, void *lbuf, uint64_t lsize,
+    uint64_t psize, int flags)
+{
+	boolean_t exceeded = B_FALSE;
+	/*
+	 * We don't know how the data was compressed, so just try
+	 * every decompress function at every inflated blocksize.
+	 */
+	void *lbuf2 = umem_alloc(SPA_MAXBLOCKSIZE, UMEM_NOFAIL);
+	int cfuncs[ZIO_COMPRESS_FUNCTIONS] = { 0 };
+	int *cfuncp = cfuncs;
+	uint64_t maxlsize = SPA_MAXBLOCKSIZE;
+	uint64_t mask = ZIO_COMPRESS_MASK(ON) | ZIO_COMPRESS_MASK(OFF) |
+	    ZIO_COMPRESS_MASK(INHERIT) | ZIO_COMPRESS_MASK(EMPTY) |
+	    (getenv("ZDB_NO_ZLE") ? ZIO_COMPRESS_MASK(ZLE) : 0);
+	*cfuncp++ = ZIO_COMPRESS_LZ4;
+	*cfuncp++ = ZIO_COMPRESS_LZJB;
+	mask |= ZIO_COMPRESS_MASK(LZ4) | ZIO_COMPRESS_MASK(LZJB);
+	for (int c = 0; c < ZIO_COMPRESS_FUNCTIONS; c++)
+		if (((1ULL << c) & mask) == 0)
+			*cfuncp++ = c;
+
+	/*
+	 * On the one hand, with SPA_MAXBLOCKSIZE at 16MB, this
+	 * could take a while and we should let the user know
+	 * we are not stuck.  On the other hand, printing progress
+	 * info gets old after a while.  User can specify 'v' flag
+	 * to see the progression.
+	 */
+	if (lsize == psize)
+		lsize += SPA_MINBLOCKSIZE;
+	else
+		maxlsize = lsize;
+	for (; lsize <= maxlsize; lsize += SPA_MINBLOCKSIZE) {
+		for (cfuncp = cfuncs; *cfuncp; cfuncp++) {
+			if (flags & ZDB_FLAG_VERBOSE) {
+				(void) fprintf(stderr,
+				    "Trying %05llx -> %05llx (%s)\n",
+				    (u_longlong_t)psize,
+				    (u_longlong_t)lsize,
+				    zio_compress_table[*cfuncp].\
+				    ci_name);
+			}
+
+			/*
+			 * We randomize lbuf2, and decompress to both
+			 * lbuf and lbuf2. This way, we will know if
+			 * decompression fill exactly to lsize.
+			 */
+			VERIFY0(random_get_pseudo_bytes(lbuf2, lsize));
+
+			if (zio_decompress_data(*cfuncp, pabd,
+			    lbuf, psize, lsize) == 0 &&
+			    zio_decompress_data(*cfuncp, pabd,
+			    lbuf2, psize, lsize) == 0 &&
+			    bcmp(lbuf, lbuf2, lsize) == 0)
+				break;
+		}
+		if (*cfuncp != 0)
+			break;
+	}
+	umem_free(lbuf2, SPA_MAXBLOCKSIZE);
+
+	if (lsize > maxlsize) {
+		exceeded = B_TRUE;
+	}
+	buf = lbuf;
+	if (*cfuncp == ZIO_COMPRESS_ZLE) {
+		printf("\nZLE decompression was selected. If you "
+		    "suspect the results are wrong,\ntry avoiding ZLE "
+		    "by setting and exporting ZDB_NO_ZLE=\"true\"\n");
+	}
+
+	return (exceeded);
+}
+
 /*
  * Read a block from a pool and print it out.  The syntax of the
  * block descriptor is:
@@ -6610,7 +6699,7 @@ zdb_read_block(char *thing, spa_t *spa)
 	void *lbuf, *buf;
 	char *s, *p, *dup, *vdev, *flagstr, *sizes;
 	int i, error;
-	boolean_t borrowed = B_FALSE;
+	boolean_t borrowed = B_FALSE, found = B_FALSE;
 
 	dup = strdup(thing);
 	s = strtok(dup, ":");
@@ -6630,41 +6719,57 @@ zdb_read_block(char *thing, spa_t *spa)
 		s = "offset must be a multiple of sector size";
 	if (s) {
 		(void) printf("Invalid block specifier: %s  - %s\n", thing, s);
-		free(flagstr);
-		free(dup);
-		return;
+		goto done;
 	}
 
 	for (s = strtok(flagstr, ":"); s; s = strtok(NULL, ":")) {
-		for (i = 0; flagstr[i]; i++) {
+		for (i = 0; i < strlen(flagstr); i++) {
 			int bit = flagbits[(uchar_t)flagstr[i]];
 
 			if (bit == 0) {
-				(void) printf("***Invalid flag: %c\n",
-				    flagstr[i]);
+				(void) printf("***Ignoring flag: %c\n",
+				    (uchar_t)flagstr[i]);
 				continue;
 			}
+			found = B_TRUE;
 			flags |= bit;
 
-			/* If it's not something with an argument, keep going */
-			if ((bit & (ZDB_FLAG_CHECKSUM |
-			    ZDB_FLAG_PRINT_BLKPTR)) == 0)
-				continue;
-
 			p = &flagstr[i + 1];
-			if (bit == ZDB_FLAG_PRINT_BLKPTR) {
-				blkptr_offset = strtoull(p, &p, 16);
-				i = p - &flagstr[i + 1];
-			}
 			if (*p != ':' && *p != '\0') {
-				(void) printf("***Invalid flag arg: '%s'\n", s);
-				free(flagstr);
-				free(dup);
-				return;
+				int j = 0, nextbit = flagbits[(uchar_t)*p];
+				char *end, offstr[8] = { 0 };
+				if ((bit == ZDB_FLAG_PRINT_BLKPTR) &&
+				    (nextbit == 0)) {
+					/* look ahead to isolate the offset */
+					while (nextbit == 0 &&
+					    strchr(flagbitstr, *p) == NULL) {
+						offstr[j] = *p;
+						j++;
+						if (i + j > strlen(flagstr))
+							break;
+						p++;
+						nextbit = flagbits[(uchar_t)*p];
+					}
+					blkptr_offset = strtoull(offstr, &end,
+					    16);
+					i += j;
+				} else if (nextbit == 0) {
+					(void) printf("***Ignoring flag arg:"
+					    " '%c'\n", (uchar_t)*p);
+				}
 			}
 		}
 	}
-	free(flagstr);
+	if (blkptr_offset % sizeof (blkptr_t)) {
+		printf("Block pointer offset 0x%llx "
+		    "must be divisible by 0x%x\n",
+		    (longlong_t)blkptr_offset, (int)sizeof (blkptr_t));
+		goto done;
+	}
+	if (found == B_FALSE && strlen(flagstr) > 0) {
+		printf("Invalid flag arg: '%s'\n", flagstr);
+		goto done;
+	}
 
 	vd = zdb_vdev_lookup(spa->spa_root_vdev, vdev);
 	if (vd == NULL) {
@@ -6717,10 +6822,9 @@ zdb_read_block(char *thing, spa_t *spa)
 		 */
 		zio_nowait(zio_vdev_child_io(zio, bp, vd, offset, pabd,
 		    psize, ZIO_TYPE_READ, ZIO_PRIORITY_SYNC_READ,
-		    ZIO_FLAG_DONT_CACHE | ZIO_FLAG_DONT_QUEUE |
-		    ZIO_FLAG_DONT_PROPAGATE | ZIO_FLAG_DONT_RETRY |
-		    ZIO_FLAG_CANFAIL | ZIO_FLAG_RAW | ZIO_FLAG_OPTIONAL,
-		    NULL, NULL));
+		    ZIO_FLAG_DONT_CACHE | ZIO_FLAG_DONT_PROPAGATE |
+		    ZIO_FLAG_DONT_RETRY | ZIO_FLAG_CANFAIL | ZIO_FLAG_RAW |
+		    ZIO_FLAG_OPTIONAL, NULL, NULL));
 	}
 
 	error = zio_wait(zio);
@@ -6731,80 +6835,43 @@ zdb_read_block(char *thing, spa_t *spa)
 		goto out;
 	}
 
+	uint64_t orig_lsize = lsize;
+	buf = lbuf;
 	if (flags & ZDB_FLAG_DECOMPRESS) {
-		/*
-		 * We don't know how the data was compressed, so just try
-		 * every decompress function at every inflated blocksize.
-		 */
-		void *lbuf2 = umem_alloc(SPA_MAXBLOCKSIZE, UMEM_NOFAIL);
-		int cfuncs[ZIO_COMPRESS_FUNCTIONS] = { 0 };
-		int *cfuncp = cfuncs;
-		uint64_t maxlsize = SPA_MAXBLOCKSIZE;
-		uint64_t mask = ZIO_COMPRESS_MASK(ON) | ZIO_COMPRESS_MASK(OFF) |
-		    ZIO_COMPRESS_MASK(INHERIT) | ZIO_COMPRESS_MASK(EMPTY) |
-		    (getenv("ZDB_NO_ZLE") ? ZIO_COMPRESS_MASK(ZLE) : 0);
-		*cfuncp++ = ZIO_COMPRESS_LZ4;
-		*cfuncp++ = ZIO_COMPRESS_LZJB;
-		mask |= ZIO_COMPRESS_MASK(LZ4) | ZIO_COMPRESS_MASK(LZJB);
-		for (int c = 0; c < ZIO_COMPRESS_FUNCTIONS; c++)
-			if (((1ULL << c) & mask) == 0)
-				*cfuncp++ = c;
-
-		/*
-		 * On the one hand, with SPA_MAXBLOCKSIZE at 16MB, this
-		 * could take a while and we should let the user know
-		 * we are not stuck.  On the other hand, printing progress
-		 * info gets old after a while.  User can specify 'v' flag
-		 * to see the progression.
-		 */
-		if (lsize == psize)
-			lsize += SPA_MINBLOCKSIZE;
-		else
-			maxlsize = lsize;
-		for (; lsize <= maxlsize; lsize += SPA_MINBLOCKSIZE) {
-			for (cfuncp = cfuncs; *cfuncp; cfuncp++) {
-				if (flags & ZDB_FLAG_VERBOSE) {
-					(void) fprintf(stderr,
-					    "Trying %05llx -> %05llx (%s)\n",
-					    (u_longlong_t)psize,
-					    (u_longlong_t)lsize,
-					    zio_compress_table[*cfuncp].\
-					    ci_name);
-				}
-
-				/*
-				 * We randomize lbuf2, and decompress to both
-				 * lbuf and lbuf2. This way, we will know if
-				 * decompression fill exactly to lsize.
-				 */
-				VERIFY0(random_get_pseudo_bytes(lbuf2, lsize));
-
-				if (zio_decompress_data(*cfuncp, pabd,
-				    lbuf, psize, lsize) == 0 &&
-				    zio_decompress_data(*cfuncp, pabd,
-				    lbuf2, psize, lsize) == 0 &&
-				    bcmp(lbuf, lbuf2, lsize) == 0)
-					break;
-			}
-			if (*cfuncp != 0)
-				break;
-		}
-		umem_free(lbuf2, SPA_MAXBLOCKSIZE);
-
-		if (lsize > maxlsize) {
+		boolean_t failed = zdb_decompress_block(pabd, buf, lbuf,
+		    lsize, psize, flags);
+		if (failed) {
 			(void) printf("Decompress of %s failed\n", thing);
 			goto out;
 		}
-		buf = lbuf;
-		if (*cfuncp == ZIO_COMPRESS_ZLE) {
-			printf("\nZLE decompression was selected. If you "
-			    "suspect the results are wrong,\ntry avoiding ZLE "
-			    "by setting and exporting ZDB_NO_ZLE=\"true\"\n");
-		}
 	} else {
 		buf = abd_borrow_buf_copy(pabd, lsize);
 		borrowed = B_TRUE;
 	}
+	/*
+	 * Try to detect invalid block pointer.  If invalid, try
+	 * decompressing.
+	 */
+	if ((flags & ZDB_FLAG_PRINT_BLKPTR || flags & ZDB_FLAG_INDIRECT) &&
+	    !(flags & ZDB_FLAG_DECOMPRESS)) {
+		const blkptr_t *b = (const blkptr_t *)(void *)
+		    ((uintptr_t)buf + (uintptr_t)blkptr_offset);
+		if (zfs_blkptr_verify(spa, b, B_FALSE, BLK_VERIFY_ONLY) ==
+		    B_FALSE) {
+			abd_return_buf_copy(pabd, buf, lsize);
+			borrowed = B_FALSE;
+			buf = lbuf;
+			boolean_t failed = zdb_decompress_block(pabd, buf,
+			    lbuf, lsize, psize, flags);
+			b = (const blkptr_t *)(void *)
+			    ((uintptr_t)buf + (uintptr_t)blkptr_offset);
+			if (failed || zfs_blkptr_verify(spa, b, B_FALSE,
+			    BLK_VERIFY_LOG) == B_FALSE) {
+				printf("invalid block pointer at this DVA\n");
+				goto out;
+			}
+		}
+	}
 
 	if (flags & ZDB_FLAG_PRINT_BLKPTR)
 		zdb_print_blkptr((blkptr_t *)(void *)
@@ -6812,8 +6879,8 @@ zdb_read_block(char *thing, spa_t *spa)
 	else if (flags & ZDB_FLAG_RAW)
 		zdb_dump_block_raw(buf, lsize, flags);
 	else if (flags & ZDB_FLAG_INDIRECT)
-		zdb_dump_indirect((blkptr_t *)buf, lsize / sizeof (blkptr_t),
-		    flags);
+		zdb_dump_indirect((blkptr_t *)buf,
+		    orig_lsize / sizeof (blkptr_t), flags);
 	else if (flags & ZDB_FLAG_GBH)
 		zdb_dump_gbh(buf, flags);
 	else
@@ -6886,6 +6953,8 @@ zdb_read_block(char *thing, spa_t *spa)
 out:
 	abd_free(pabd);
 	umem_free(lbuf, SPA_MAXBLOCKSIZE);
+done:
+	free(flagstr);
 	free(dup);
 }
 
diff --git a/include/sys/zio.h b/include/sys/zio.h
index f78b02fd5..368d8c149 100644
--- a/include/sys/zio.h
+++ b/include/sys/zio.h
@@ -516,6 +516,12 @@ struct zio {
 	taskq_ent_t	io_tqent;
 };
 
+enum blk_verify_flag {
+	BLK_VERIFY_ONLY,
+	BLK_VERIFY_LOG,
+	BLK_VERIFY_HALT
+};
+
 extern int zio_bookmark_compare(const void *, const void *);
 
 extern zio_t *zio_null(zio_t *pio, spa_t *spa, vdev_t *vd,
@@ -626,6 +632,9 @@ extern void zio_suspend(spa_t *spa, zio_t *zio, zio_suspend_reason_t);
 extern int zio_resume(spa_t *spa);
 extern void zio_resume_wait(spa_t *spa);
 
+extern boolean_t zfs_blkptr_verify(spa_t *spa, const blkptr_t *bp,
+    boolean_t config_held, enum blk_verify_flag blk_verify);
+
 /*
  * Initial setup and teardown.
  */
diff --git a/man/man8/zdb.8 b/man/man8/zdb.8
index a7ab6b8ba..8506d5478 100644
--- a/man/man8/zdb.8
+++ b/man/man8/zdb.8
@@ -286,7 +286,7 @@ of the block to read and, optionally,
 .Pp
 .Bl -tag -compact -width "b offset"
 .It Sy b Ar offset
-Print block pointer
+Print block pointer at hex offset
 .It Sy c
 Calculate and display checksums
 .It Sy d
diff --git a/module/zfs/zio.c b/module/zfs/zio.c
index ebd7098d6..9dc3c830a 100644
--- a/module/zfs/zio.c
+++ b/module/zfs/zio.c
@@ -890,35 +890,82 @@ zio_root(spa_t *spa, zio_done_func_t *done, void *private, enum zio_flag flags)
 	return (zio_null(NULL, spa, NULL, done, private, flags));
 }
 
-static void
-zfs_blkptr_verify(spa_t *spa, const blkptr_t *bp, boolean_t config_held)
+static int
+zfs_blkptr_verify_log(spa_t *spa, const blkptr_t *bp,
+    enum blk_verify_flag blk_verify, const char *fmt, ...)
+{
+	va_list adx;
+	char buf[256];
+
+	va_start(adx, fmt);
+	(void) vsnprintf(buf, sizeof (buf), fmt, adx);
+	va_end(adx);
+
+	switch (blk_verify) {
+	case BLK_VERIFY_HALT:
+		zfs_panic_recover("%s: %s", spa_name(spa), buf);
+		break;
+	case BLK_VERIFY_LOG:
+		zfs_dbgmsg("%s: %s", spa_name(spa), buf);
+		break;
+	case BLK_VERIFY_ONLY:
+		break;
+	}
+
+	return (1);
+}
+
+/*
+ * Verify the block pointer fields contain reasonable values.  This means
+ * it only contains known object types, checksum/compression identifiers,
+ * block sizes within the maximum allowed limits, valid DVAs, etc.
+ *
+ * If everything checks out B_TRUE is returned.  The zfs_blkptr_verify
+ * argument controls the behavior when an invalid field is detected.
+ *
+ * Modes for zfs_blkptr_verify:
+ *   1) BLK_VERIFY_ONLY (evaluate the block)
+ *   2) BLK_VERIFY_LOG (evaluate the block and log problems)
+ *   3) BLK_VERIFY_HALT (call zfs_panic_recover on error)
+ */
+boolean_t
+zfs_blkptr_verify(spa_t *spa, const blkptr_t *bp, boolean_t config_held,
+    enum blk_verify_flag blk_verify)
 {
+	int errors = 0;
+
 	if (!DMU_OT_IS_VALID(BP_GET_TYPE(bp))) {
-		zfs_panic_recover("blkptr at %p has invalid TYPE %llu",
+		errors += zfs_blkptr_verify_log(spa, bp, blk_verify,
+		    "blkptr at %p has invalid TYPE %llu",
 		    bp, (longlong_t)BP_GET_TYPE(bp));
 	}
 	if (BP_GET_CHECKSUM(bp) >= ZIO_CHECKSUM_FUNCTIONS ||
 	    BP_GET_CHECKSUM(bp) <= ZIO_CHECKSUM_ON) {
-		zfs_panic_recover("blkptr at %p has invalid CHECKSUM %llu",
+		errors += zfs_blkptr_verify_log(spa, bp, blk_verify,
+		    "blkptr at %p has invalid CHECKSUM %llu",
 		    bp, (longlong_t)BP_GET_CHECKSUM(bp));
 	}
 	if (BP_GET_COMPRESS(bp) >= ZIO_COMPRESS_FUNCTIONS ||
 	    BP_GET_COMPRESS(bp) <= ZIO_COMPRESS_ON) {
-		zfs_panic_recover("blkptr at %p has invalid COMPRESS %llu",
+		errors += zfs_blkptr_verify_log(spa, bp, blk_verify,
+		    "blkptr at %p has invalid COMPRESS %llu",
 		    bp, (longlong_t)BP_GET_COMPRESS(bp));
 	}
 	if (BP_GET_LSIZE(bp) > SPA_MAXBLOCKSIZE) {
-		zfs_panic_recover("blkptr at %p has invalid LSIZE %llu",
+		errors += zfs_blkptr_verify_log(spa, bp, blk_verify,
+		    "blkptr at %p has invalid LSIZE %llu",
 		    bp, (longlong_t)BP_GET_LSIZE(bp));
 	}
 	if (BP_GET_PSIZE(bp) > SPA_MAXBLOCKSIZE) {
-		zfs_panic_recover("blkptr at %p has invalid PSIZE %llu",
+		errors += zfs_blkptr_verify_log(spa, bp, blk_verify,
+		    "blkptr at %p has invalid PSIZE %llu",
 		    bp, (longlong_t)BP_GET_PSIZE(bp));
 	}
 
 	if (BP_IS_EMBEDDED(bp)) {
 		if (BPE_GET_ETYPE(bp) >= NUM_BP_EMBEDDED_TYPES) {
-			zfs_panic_recover("blkptr at %p has invalid ETYPE %llu",
+			errors += zfs_blkptr_verify_log(spa, bp, blk_verify,
+			    "blkptr at %p has invalid ETYPE %llu",
 			    bp, (longlong_t)BPE_GET_ETYPE(bp));
 		}
 	}
@@ -928,7 +975,7 @@ zfs_blkptr_verify(spa_t *spa, const blkptr_t *bp, boolean_t config_held)
 	 * will be done once the zio is executed in vdev_mirror_map_alloc.
 	 */
 	if (!spa->spa_trust_config)
-		return;
+		return (B_TRUE);
 
 	if (!config_held)
 		spa_config_enter(spa, SCL_VDEV, bp, RW_READER);
@@ -946,21 +993,21 @@ zfs_blkptr_verify(spa_t *spa, const blkptr_t *bp, boolean_t config_held)
 		uint64_t vdevid = DVA_GET_VDEV(&bp->blk_dva[i]);
 
 		if (vdevid >= spa->spa_root_vdev->vdev_children) {
-			zfs_panic_recover("blkptr at %p DVA %u has invalid "
-			    "VDEV %llu",
+			errors += zfs_blkptr_verify_log(spa, bp, blk_verify,
+			    "blkptr at %p DVA %u has invalid VDEV %llu",
 			    bp, i, (longlong_t)vdevid);
 			continue;
 		}
 		vdev_t *vd = spa->spa_root_vdev->vdev_child[vdevid];
 		if (vd == NULL) {
-			zfs_panic_recover("blkptr at %p DVA %u has invalid "
-			    "VDEV %llu",
+			errors += zfs_blkptr_verify_log(spa, bp, blk_verify,
+			    "blkptr at %p DVA %u has invalid VDEV %llu",
 			    bp, i, (longlong_t)vdevid);
 			continue;
 		}
 		if (vd->vdev_ops == &vdev_hole_ops) {
-			zfs_panic_recover("blkptr at %p DVA %u has hole "
-			    "VDEV %llu",
+			errors += zfs_blkptr_verify_log(spa, bp, blk_verify,
+			    "blkptr at %p DVA %u has hole VDEV %llu",
 			    bp, i, (longlong_t)vdevid);
 			continue;
 		}
@@ -977,13 +1024,15 @@ zfs_blkptr_verify(spa_t *spa, const blkptr_t *bp, boolean_t config_held)
 		if (BP_IS_GANG(bp))
 			asize = vdev_psize_to_asize(vd, SPA_GANGBLOCKSIZE);
 		if (offset + asize > vd->vdev_asize) {
-			zfs_panic_recover("blkptr at %p DVA %u has invalid "
-			    "OFFSET %llu",
+			errors += zfs_blkptr_verify_log(spa, bp, blk_verify,
+			    "blkptr at %p DVA %u has invalid OFFSET %llu",
 			    bp, i, (longlong_t)offset);
 		}
 	}
 	if (!config_held)
 		spa_config_exit(spa, SCL_VDEV, bp);
+
+	return (errors == 0);
 }
 
 boolean_t
@@ -1023,7 +1072,8 @@ zio_read(zio_t *pio, spa_t *spa, const blkptr_t *bp,
 {
 	zio_t *zio;
 
-	zfs_blkptr_verify(spa, bp, flags & ZIO_FLAG_CONFIG_WRITER);
+	(void) zfs_blkptr_verify(spa, bp, flags & ZIO_FLAG_CONFIG_WRITER,
+	    BLK_VERIFY_HALT);
 
 	zio = zio_create(pio, spa, BP_PHYSICAL_BIRTH(bp), bp,
 	    data, size, size, done, private,
@@ -1116,7 +1166,7 @@ void
 zio_free(spa_t *spa, uint64_t txg, const blkptr_t *bp)
 {
 
-	zfs_blkptr_verify(spa, bp, B_FALSE);
+	(void) zfs_blkptr_verify(spa, bp, B_FALSE, BLK_VERIFY_HALT);
 
 	/*
 	 * The check for EMBEDDED is a performance optimization.  We
@@ -1186,7 +1236,8 @@ zio_claim(zio_t *pio, spa_t *spa, uint64_t txg, const blkptr_t *bp,
 {
 	zio_t *zio;
 
-	zfs_blkptr_verify(spa, bp, flags & ZIO_FLAG_CONFIG_WRITER);
+	(void) zfs_blkptr_verify(spa, bp, flags & ZIO_FLAG_CONFIG_WRITER,
+	    BLK_VERIFY_HALT);
 
 	if (BP_IS_EMBEDDED(bp))
 		return (zio_null(pio, spa, NULL, NULL, NULL, 0));
diff --git a/tests/runfiles/common.run b/tests/runfiles/common.run
index 72745bfa7..81cca7eed 100644
--- a/tests/runfiles/common.run
+++ b/tests/runfiles/common.run
@@ -101,7 +101,8 @@ tags = ['functional', 'clean_mirror']
 [tests/functional/cli_root/zdb]
 tests = ['zdb_001_neg', 'zdb_002_pos', 'zdb_003_pos', 'zdb_004_pos',
     'zdb_005_pos', 'zdb_006_pos', 'zdb_checksum', 'zdb_decompress',
-    'zdb_object_range_neg', 'zdb_object_range_pos', 'zdb_objset_id']
+    'zdb_object_range_neg', 'zdb_object_range_pos', 'zdb_display_block',
+    'zdb_objset_id']
 pre =
 post =
 tags = ['functional', 'cli_root', 'zdb']
diff --git a/tests/zfs-tests/tests/functional/cli_root/zdb/Makefile.am b/tests/zfs-tests/tests/functional/cli_root/zdb/Makefile.am
index e4679ae9f..71fe68436 100644
--- a/tests/zfs-tests/tests/functional/cli_root/zdb/Makefile.am
+++ b/tests/zfs-tests/tests/functional/cli_root/zdb/Makefile.am
@@ -8,6 +8,7 @@ dist_pkgdata_SCRIPTS = \
 	zdb_006_pos.ksh \
 	zdb_checksum.ksh \
 	zdb_decompress.ksh \
-	zdb_objset_id.ksh \
 	zdb_object_range_neg.ksh \
-	zdb_object_range_pos.ksh
+	zdb_object_range_pos.ksh \
+	zdb_display_block.ksh \
+	zdb_objset_id.ksh
diff --git a/tests/zfs-tests/tests/functional/cli_root/zdb/zdb_display_block.ksh b/tests/zfs-tests/tests/functional/cli_root/zdb/zdb_display_block.ksh
new file mode 100755
index 000000000..c8a52def4
--- /dev/null
+++ b/tests/zfs-tests/tests/functional/cli_root/zdb/zdb_display_block.ksh
@@ -0,0 +1,128 @@
+#!/bin/ksh
+
+#
+# This file and its contents are supplied under the terms of the
+# Common Development and Distribution License ("CDDL"), version 1.0.
+# You may only use this file in accordance with the terms of version
+# 1.0 of the CDDL.
+#
+# A full copy of the text of the CDDL should have accompanied this
+# source.  A copy of the CDDL is also available via the Internet at
+# http://www.illumos.org/license/CDDL.
+#
+
+#
+# Copyright (c) 2019 by Datto, Inc. All rights reserved.
+#
+
+. $STF_SUITE/include/libtest.shlib
+
+#
+# Description:
+# zdb -R pool <DVA>:b will display the block
+#
+# Strategy:
+# 1. Create a pool, set compression to lzjb
+# 2. Write some identifiable data to a file
+# 3. Run zdb -ddddddbbbbbb against the file
+# 4. Record the DVA of the first L1 block;
+#    record the first L0 block display; and
+#    record the 2nd L0 block display.
+# 5. Run zdb -R with :bd displays first L0
+# 6. Run zdb -R with :b80d displays 2nd L0
+# 7. Run zdb -R with :db80 displays 2nd L0
+# 8. Run zdb -R with :id flag displays indirect block
+#     (similar to zdb -ddddddbbbbbb output)
+# 9. Run zdb -R with :id flag and .0 vdev
+#
+
+
+function cleanup
+{
+	datasetexists $TESTPOOL && destroy_pool $TESTPOOL
+}
+
+log_assert "Verify zdb -R :b flag (block display) works as expected"
+log_onexit cleanup
+init_data=$TESTDIR/file1
+write_count=256
+blksize=4096
+
+# only read 256 128 byte block pointers in L1 (:i flag)
+# 256 x 128 = 32k / 0x8000
+l1_read_size="8000"
+
+verify_runnable "global"
+verify_disk_count "$DISKS" 2
+
+default_mirror_setup_noexit $DISKS
+log_must zfs set recordsize=$blksize $TESTPOOL/$TESTFS
+log_must zfs set compression=lzjb $TESTPOOL/$TESTFS
+
+file_write -d R -o create -w -f $init_data -b $blksize -c $write_count
+sync_pool $TESTPOOL true
+
+# get object number of file
+listing=$(ls -i $init_data)
+set -A array $listing
+obj=${array[0]}
+log_note "file $init_data has object number $obj"
+
+output=$(zdb -ddddddbbbbbb $TESTPOOL/$TESTFS $obj 2> /dev/null \
+    |grep -m 1 "L1  DVA" |head -n1)
+dva=$(sed -Ene 's/^.+DVA\[0\]=<([^>]+)>.*/\1/p' <<< "$output")
+log_note "first L1 block $init_data has a DVA of $dva"
+output=$(zdb -ddddddbbbbbb $TESTPOOL/$TESTFS $obj 2> /dev/null \
+    |grep -m 1 "L0 DVA" |head -n1)
+blk_out0=${output##*>}
+blk_out0=${blk_out0##+([[:space:]])}
+
+output=$(zdb -ddddddbbbbbb $TESTPOOL/$TESTFS $obj 2> /dev/null \
+    |grep -m 1 "1000  L0 DVA" |head -n1)
+blk_out1=${output##*>}
+blk_out1=${blk_out1##+([[:space:]])}
+
+output=$(export ZDB_NO_ZLE=\"true\"; zdb -R $TESTPOOL $dva:bd\
+    2> /dev/null)
+output=${output##*>}
+output=${output##+([[:space:]])}
+if [ "$output" != "$blk_out0" ]; then
+	log_fail "zdb -R :bd (block 0 display/decompress) failed"
+fi
+
+output=$(export ZDB_NO_ZLE=\"true\"; zdb -R $TESTPOOL $dva:db80\
+    2> /dev/null)
+output=${output##*>}
+output=${output##+([[:space:]])}
+if [ "$output" != "$blk_out1" ]; then
+	log_fail "zdb -R :db80 (block 1 display/decompress) failed"
+fi
+
+output=$(export ZDB_NO_ZLE=\"true\"; zdb -R $TESTPOOL $dva:b80d\
+    2> /dev/null)
+output=${output##*>}
+output=${output##+([[:space:]])}
+if [ "$output" != "$blk_out1" ]; then
+	log_fail "zdb -R :b80d (block 1 display/decompress) failed"
+fi
+
+vdev=$(echo "$dva" |awk '{split($0,array,":")} END{print array[1]}')
+offset=$(echo "$dva" |awk '{split($0,array,":")} END{print array[2]}')
+output=$(export ZDB_NO_ZLE=\"true\";\
+    zdb -R $TESTPOOL $vdev:$offset:$l1_read_size:id 2> /dev/null)
+block_cnt=$(echo "$output" | grep 'L0' | wc -l)
+if [ "$block_cnt" != "$write_count" ]; then
+	log_fail "zdb -R :id (indirect block display) failed"
+fi
+
+# read from specific half of mirror
+vdev="$vdev.0"
+log_note "Reading from DVA $vdev:$offset:$l1_read_size"
+output=$(export ZDB_NO_ZLE=\"true\";\
+    zdb -R $TESTPOOL $vdev:$offset:$l1_read_size:id 2> /dev/null)
+block_cnt=$(echo "$output" | grep 'L0' | wc -l)
+if [ "$block_cnt" != "$write_count" ]; then
+        log_fail "zdb -R 0.0:offset:length:id (indirect block display) failed"
+fi
+
+log_pass "zdb -R :b flag (block display) works as expected"