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Make zdb -R a little more sane.

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zdb -R has a minor flaw in which it will not always print the full
output of a decompressed block. Oops.

While I was in there, I also reworked the logic so it won't try
ZLE unless everything else fails, which will hopefully avoid the
problem ZDB_NO_ZLE was intended to mitigate of reporting a lot of
false positives of ZLE compressed blocks...

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Rich Ercolani <rincebrain@gmail.com>
Closes #15723
This commit is contained in:
Rich Ercolani 2024-01-16 16:16:08 -05:00 committed by GitHub
parent 995734ed12
commit 1f5bf96001
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GPG key ID: B5690EEEBB952194
1 changed files with 57 additions and 34 deletions
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91
cmd/zdb/zdb.c
View file

@ -8488,11 +8488,45 @@ zdb_parse_block_sizes(char *sizes, uint64_t *lsize, uint64_t *psize)
#define ZIO_COMPRESS_MASK(alg) (1ULL << (ZIO_COMPRESS_##alg))
static boolean_t
try_decompress_block(abd_t *pabd, uint64_t lsize, uint64_t psize,
int flags, int cfunc, void *lbuf, void *lbuf2)
{
if (flags & ZDB_FLAG_VERBOSE) {
(void) fprintf(stderr,
"Trying %05llx -> %05llx (%s)\n",
(u_longlong_t)psize,
(u_longlong_t)lsize,
zio_compress_table[cfunc].ci_name);
}
/*
* We set lbuf to all zeros and lbuf2 to all
* ones, then decompress to both buffers and
* compare their contents. This way we can
* know if decompression filled exactly to
* lsize or if it left some bytes unwritten.
*/
memset(lbuf, 0x00, lsize);
memset(lbuf2, 0xff, lsize);
if (zio_decompress_data(cfunc, pabd,
lbuf, psize, lsize, NULL) == 0 &&
zio_decompress_data(cfunc, pabd,
lbuf2, psize, lsize, NULL) == 0 &&
memcmp(lbuf, lbuf2, lsize) == 0)
return (B_TRUE);
return (B_FALSE);
}
static uint64_t
zdb_decompress_block(abd_t *pabd, void *buf, void *lbuf, uint64_t lsize,
uint64_t psize, int flags)
{
(void) buf;
boolean_t exceeded = B_FALSE;
uint64_t orig_lsize = lsize;
boolean_t tryzle = ((getenv("ZDB_NO_ZLE") == NULL));
boolean_t found = B_FALSE;
/*
* We don't know how the data was compressed, so just try
* every decompress function at every inflated blocksize.
@ -8503,7 +8537,7 @@ zdb_decompress_block(abd_t *pabd, void *buf, void *lbuf, uint64_t lsize,
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);
ZIO_COMPRESS_MASK(ZLE);
*cfuncp++ = ZIO_COMPRESS_LZ4;
*cfuncp++ = ZIO_COMPRESS_LZJB;
mask |= ZIO_COMPRESS_MASK(LZ4) | ZIO_COMPRESS_MASK(LZJB);
@ -8530,49 +8564,38 @@ zdb_decompress_block(abd_t *pabd, void *buf, void *lbuf, uint64_t lsize,
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 set lbuf to all zeros and lbuf2 to all
* ones, then decompress to both buffers and
* compare their contents. This way we can
* know if decompression filled exactly to
* lsize or if it left some bytes unwritten.
*/
memset(lbuf, 0x00, lsize);
memset(lbuf2, 0xff, lsize);
if (zio_decompress_data(*cfuncp, pabd,
lbuf, psize, lsize, NULL) == 0 &&
zio_decompress_data(*cfuncp, pabd,
lbuf2, psize, lsize, NULL) == 0 &&
memcmp(lbuf, lbuf2, lsize) == 0)
if (try_decompress_block(pabd, lsize, psize, flags,
*cfuncp, lbuf, lbuf2)) {
found = B_TRUE;
break;
}
}
if (*cfuncp != 0)
break;
}
if (!found && tryzle) {
for (lsize = orig_lsize; lsize <= maxlsize;
lsize += SPA_MINBLOCKSIZE) {
if (try_decompress_block(pabd, lsize, psize, flags,
ZIO_COMPRESS_ZLE, lbuf, lbuf2)) {
*cfuncp = ZIO_COMPRESS_ZLE;
found = B_TRUE;
break;
}
}
}
umem_free(lbuf2, SPA_MAXBLOCKSIZE);
if (lsize > maxlsize) {
exceeded = B_TRUE;
}
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);
return (lsize > maxlsize ? -1 : lsize);
}
/*
@ -8751,9 +8774,9 @@ zdb_read_block(char *thing, spa_t *spa)
uint64_t orig_lsize = lsize;
buf = lbuf;
if (flags & ZDB_FLAG_DECOMPRESS) {
boolean_t failed = zdb_decompress_block(pabd, buf, lbuf,
lsize = zdb_decompress_block(pabd, buf, lbuf,
lsize, psize, flags);
if (failed) {
if (lsize == -1) {
(void) printf("Decompress of %s failed\n", thing);
goto out;
}
@ -8774,11 +8797,11 @@ zdb_read_block(char *thing, spa_t *spa)
abd_return_buf_copy(pabd, buf, lsize);
borrowed = B_FALSE;
buf = lbuf;
boolean_t failed = zdb_decompress_block(pabd, buf,
lsize = 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,
if (lsize == -1 || zfs_blkptr_verify(spa, b,
BLK_CONFIG_NEEDED, BLK_VERIFY_LOG) == B_FALSE) {
printf("invalid block pointer at this DVA\n");
goto out;