zio_decompress_data always ASSERTs successful decompression

This interferes with zdb_read_block trying all the decompression
algorithms when the 'd' flag is specified, as some are
expected to fail.  Also control the output when guessing
algorithms, try the more common compression types first, allow
specifying lsize/psize, and fix an uninitialized variable.

Reviewed-by: Ryan Moeller <ryan@ixsystems.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Paul Zuchowski <pzuchowski@datto.com>
Closes openzfs#9612
Closes openzfs#9630

cmd/zdb/zdb.c

@@ -2409,7 +2409,7 @@ static const char *objset_types[DMU_OST_NUMTYPES] = {
 static void
 dump_dir(objset_t *os)
 {
-	dmu_objset_stats_t dds;
+	dmu_objset_stats_t dds = { 0 };
 	uint64_t object, object_count;
 	uint64_t refdbytes, usedobjs, scratch;
 	char numbuf[32];
@@ -5447,9 +5447,9 @@ dump_zpool(spa_t *spa)
 #define	ZDB_FLAG_BSWAP		0x0004
 #define	ZDB_FLAG_GBH		0x0008
 #define	ZDB_FLAG_INDIRECT	0x0010
-#define	ZDB_FLAG_PHYS		0x0020
-#define	ZDB_FLAG_RAW		0x0040
-#define	ZDB_FLAG_PRINT_BLKPTR	0x0080
+#define	ZDB_FLAG_RAW		0x0020
+#define	ZDB_FLAG_PRINT_BLKPTR	0x0040
+#define	ZDB_FLAG_VERBOSE	0x0080
 
 static int flagbits[256];
 
@@ -5580,11 +5580,30 @@ zdb_vdev_lookup(vdev_t *vdev, const char *path)
 	return (NULL);
 }
 
+static boolean_t
+zdb_parse_block_sizes(char *sizes, uint64_t *lsize, uint64_t *psize)
+{
+	char *s0, *s1;
+
+	if (sizes == NULL)
+		return (B_FALSE);
+
+	s0 = strtok(sizes, "/");
+	if (s0 == NULL)
+		return (B_FALSE);
+	s1 = strtok(NULL, "/");
+	*lsize = strtoull(s0, NULL, 16);
+	*psize = s1 ? strtoull(s1, NULL, 16) : *lsize;
+	return (*lsize >= *psize && *psize > 0);
+}
+
+#define	ZIO_COMPRESS_MASK(alg)	(1ULL << (ZIO_COMPRESS_##alg))
+
 /*
  * Read a block from a pool and print it out.  The syntax of the
  * block descriptor is:
  *
- *	pool:vdev_specifier:offset:size[:flags]
+ *	pool:vdev_specifier:offset:[lsize/]psize[:flags]
  *
  *	pool           - The name of the pool you wish to read from
  *	vdev_specifier - Which vdev (see comment for zdb_vdev_lookup)
@@ -5597,8 +5616,8 @@ zdb_vdev_lookup(vdev_t *vdev, const char *path)
  *		 e: Byteswap data before dumping
  *		 g: Display data as a gang block header
  *		 i: Display as an indirect block
- *		 p: Do I/O to physical offset
  *		 r: Dump raw data to stdout
+ *		 v: Verbose
  *
  */
 static void
@@ -5607,13 +5626,12 @@ zdb_read_block(char *thing, spa_t *spa)
 	blkptr_t blk, *bp = &blk;
 	dva_t *dva = bp->blk_dva;
 	int flags = 0;
-	uint64_t offset = 0, size = 0, psize = 0, lsize = 0, blkptr_offset = 0;
+	uint64_t offset = 0, psize = 0, lsize = 0, blkptr_offset = 0;
 	zio_t *zio;
 	vdev_t *vd;
 	abd_t *pabd;
 	void *lbuf, *buf;
-	const char *s, *vdev;
-	char *p, *dup, *flagstr;
+	char *s, *p, *dup, *vdev, *flagstr, *sizes;
 	int i, error;
 	boolean_t borrowed = B_FALSE;
 
@@ -5622,18 +5640,14 @@ zdb_read_block(char *thing, spa_t *spa)
 	vdev = s ? s : "";
 	s = strtok(NULL, ":");
 	offset = strtoull(s ? s : "", NULL, 16);
+	sizes = strtok(NULL, ":");
 	s = strtok(NULL, ":");
-	size = strtoull(s ? s : "", NULL, 16);
-	s = strtok(NULL, ":");
-	if (s)
-		flagstr = strdup(s);
-	else
-		flagstr = strdup("");
+	flagstr = strdup(s ? s : "");
 
 	s = NULL;
-	if (size == 0)
-		s = "size must not be zero";
-	if (!IS_P2ALIGNED(size, DEV_BSIZE))
+	if (!zdb_parse_block_sizes(sizes, &lsize, &psize))
+		s = "invalid size(s)";
+	if (!IS_P2ALIGNED(psize, DEV_BSIZE) || !IS_P2ALIGNED(lsize, DEV_BSIZE))
 		s = "size must be a multiple of sector size";
 	if (!IS_P2ALIGNED(offset, DEV_BSIZE))
 		s = "offset must be a multiple of sector size";
@@ -5689,9 +5703,6 @@ zdb_read_block(char *thing, spa_t *spa)
 			    vd->vdev_ops->vdev_op_type);
 	}
 
-	psize = size;
-	lsize = size;
-
 	pabd = abd_alloc_for_io(SPA_MAXBLOCKSIZE, B_FALSE);
 	lbuf = umem_alloc(SPA_MAXBLOCKSIZE, UMEM_NOFAIL);
 
@@ -5748,30 +5759,41 @@ zdb_read_block(char *thing, spa_t *spa)
 		 * We don't know how the data was compressed, so just try
 		 * every decompress function at every inflated blocksize.
 		 */
-		enum zio_compress c;
 		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;
 
 		/*
-		 * XXX - On the one hand, with SPA_MAXBLOCKSIZE at 16MB,
-		 * this could take a while and we should let the user know
+		 * 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.  What to do?
+		 * info gets old after a while.  User can specify 'v' flag
+		 * to see the progression.
 		 */
-		for (lsize = psize + SPA_MINBLOCKSIZE;
-		    lsize <= SPA_MAXBLOCKSIZE; lsize += SPA_MINBLOCKSIZE) {
-			for (c = 0; c < ZIO_COMPRESS_FUNCTIONS; c++) {
-				/*
-				 * ZLE can easily decompress non zle stream.
-				 * So have an option to disable it.
-				 */
-				if (c == ZIO_COMPRESS_ZLE &&
-				    getenv("ZDB_NO_ZLE"))
-					continue;
-
-				(void) fprintf(stderr,
-				    "Trying %05llx -> %05llx (%s)\n",
-				    (u_longlong_t)psize, (u_longlong_t)lsize,
-				    zio_compress_table[c].ci_name);
+		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
@@ -5780,42 +5802,45 @@ zdb_read_block(char *thing, spa_t *spa)
 				 */
 				VERIFY0(random_get_pseudo_bytes(lbuf2, lsize));
 
-				if (zio_decompress_data(c, pabd,
+				if (zio_decompress_data(*cfuncp, pabd,
 				    lbuf, psize, lsize) == 0 &&
-				    zio_decompress_data(c, pabd,
+				    zio_decompress_data(*cfuncp, pabd,
 				    lbuf2, psize, lsize) == 0 &&
 				    bcmp(lbuf, lbuf2, lsize) == 0)
 					break;
 			}
-			if (c != ZIO_COMPRESS_FUNCTIONS)
+			if (*cfuncp != 0)
 				break;
 		}
 		umem_free(lbuf2, SPA_MAXBLOCKSIZE);
 
-		if (lsize > SPA_MAXBLOCKSIZE) {
+		if (lsize > maxlsize) {
 			(void) printf("Decompress of %s failed\n", thing);
 			goto out;
 		}
 		buf = lbuf;
-		size = lsize;
+		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 {
-		size = psize;
-		buf = abd_borrow_buf_copy(pabd, size);
+		buf = abd_borrow_buf_copy(pabd, lsize);
 		borrowed = B_TRUE;
 	}
 
 	if (flags & ZDB_FLAG_PRINT_BLKPTR)
 		zdb_print_blkptr((blkptr_t *)(void *)
 		    ((uintptr_t)buf + (uintptr_t)blkptr_offset), flags);
 	else if (flags & ZDB_FLAG_RAW)
-		zdb_dump_block_raw(buf, size, flags);
+		zdb_dump_block_raw(buf, lsize, flags);
 	else if (flags & ZDB_FLAG_INDIRECT)
-		zdb_dump_indirect((blkptr_t *)buf, size / sizeof (blkptr_t),
+		zdb_dump_indirect((blkptr_t *)buf, lsize / sizeof (blkptr_t),
 		    flags);
 	else if (flags & ZDB_FLAG_GBH)
 		zdb_dump_gbh(buf, flags);
 	else
-		zdb_dump_block(thing, buf, size, flags);
+		zdb_dump_block(thing, buf, lsize, flags);
 
 	/*
 	 * If :c was specified, iterate through the checksum table to
@@ -5879,7 +5904,7 @@ zdb_read_block(char *thing, spa_t *spa)
 	}
 
 	if (borrowed)
-		abd_return_buf_copy(pabd, buf, size);
+		abd_return_buf_copy(pabd, buf, lsize);
 
 out:
 	abd_free(pabd);
@@ -6294,8 +6319,8 @@ main(int argc, char **argv)
 		flagbits['e'] = ZDB_FLAG_BSWAP;
 		flagbits['g'] = ZDB_FLAG_GBH;
 		flagbits['i'] = ZDB_FLAG_INDIRECT;
-		flagbits['p'] = ZDB_FLAG_PHYS;
 		flagbits['r'] = ZDB_FLAG_RAW;
+		flagbits['v'] = ZDB_FLAG_VERBOSE;
 
 		for (int i = 0; i < argc; i++)
 			zdb_read_block(argv[i], spa);

man/man8/zdb.8

@@ -63,7 +63,7 @@
 .Op Fl A
 .Op Fl e Oo Fl V Oc Op Fl p Ar path ...
 .Op Fl U Ar cache
-.Ar poolname vdev Ns \&: Ns Ar offset Ns \&: Ns Ar size Ns Op : Ns Ar flags
+.Ar poolname vdev Ns \&: Ns Ar offset Ns \&: Ns Ar [<lsize>/]<psize> Ns Op : Ns Ar flags
 .Nm
 .Fl S
 .Op Fl AP
@@ -227,7 +227,7 @@ This option can be combined with
 .Fl v
 for increasing verbosity.
 .It Xo
-.Fl R Ar poolname vdev Ns \&: Ns Ar offset Ns \&: Ns Ar size Ns Op : Ns Ar flags
+.Fl R Ar poolname vdev Ns \&: Ns Ar offset Ns \&: Ns Ar [<lsize>/]<psize> Ns Op : Ns Ar flags
 .Xc
 Read and display a block from the specified device.
 By default the block is displayed as a hex dump, but see the description of the
@@ -240,8 +240,8 @@ The block is specified in terms of a colon-separated tuple
 .Ar offset
 .Pq the offset within the vdev
 .Ar size
-.Pq the size of the block to read
-and, optionally,
+.Pq the physical size, or logical size / physical size
+of the block to read and, optionally,
 .Ar flags
 .Pq a set of flags, described below .
 .Pp
@@ -262,6 +262,8 @@ Dump gang block header
 Dump indirect block
 .It Sy r
 Dump raw uninterpreted block data
+.It Sy v
+Verbose output for guessing compression algorithm
 .El
 .It Fl s
 Report statistics on

module/zfs/zio_compress.c

@@ -159,7 +159,6 @@ zio_decompress_data(enum zio_compress c, abd_t *src, void *dst,
 	 * the checksum.  However, for extra protection (e.g. against bitflips
 	 * in non-ECC RAM), we handle this error (and test it).
 	 */
-	ASSERT0(ret);
 	if (zio_decompress_fail_fraction != 0 &&
 	    spa_get_random(zio_decompress_fail_fraction) == 0)
 		ret = SET_ERROR(EINVAL);

tests/runfiles/linux.run

@@ -106,7 +106,7 @@ 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_005_pos', 'zdb_006_pos', 'zdb_checksum', 'zdb_decompress']
 pre =
 post =
 tags = ['functional', 'cli_root', 'zdb']

tests/zfs-tests/tests/functional/cli_root/zdb/Makefile.am

@@ -6,4 +6,5 @@ dist_pkgdata_SCRIPTS = \
 	zdb_004_pos.ksh \
 	zdb_005_pos.ksh \
 	zdb_006_pos.ksh \
-	zdb_checksum.ksh
+	zdb_checksum.ksh \
+	zdb_decompress.ksh