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Improve zfs_blkptr_verify()

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- Skip config lock enter/exit for embedded blocks.  They have no
DVAs, so there is nothing to check under the lock.
 - Skip CHECKSUM check and properly check PSIZE for embedded blocks.
 - Add static branch predictions for unlikely conditions.
 - Do not verify DVAs for blocks already in ARC.  ARC hit already
"verified" the first (often the only) DVA, and it does not worth to
enter/exit config lock for nothing.

Some profiles show me up to 3% of CPU saving from this change.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Allan Jude <allan@klarasystems.com>
Signed-off-by: Alexander Motin <mav@FreeBSD.org>
Sponsored by:	iXsystems, Inc.
Closes #16387
This commit is contained in:
Alexander Motin
2024-08-08 18:25:10 -04:00
committed by GitHub
parent 24e6585e76
commit aef452f108
2 changed files with 51 additions and 33 deletions
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module/zfs/arc.c
+26 -13
View File
@@ -5576,19 +5576,6 @@ arc_read(zio_t *pio, spa_t *spa, const blkptr_t *bp,
*/
fstrans_cookie_t cookie = spl_fstrans_mark();
top:
/*
* Verify the block pointer contents are reasonable. This should
* always be the case since the blkptr is protected by a checksum.
* However, if there is damage it's desirable to detect this early
* and treat it as a checksum error. This allows an alternate blkptr
* to be tried when one is available (e.g. ditto blocks).
*/
if (!zfs_blkptr_verify(spa, bp, (zio_flags & ZIO_FLAG_CONFIG_WRITER) ?
BLK_CONFIG_HELD : BLK_CONFIG_NEEDED, BLK_VERIFY_LOG)) {
rc = SET_ERROR(ECKSUM);
goto done;
}
if (!embedded_bp) {
/*
* Embedded BP's have no DVA and require no I/O to "read".
@@ -5608,6 +5595,18 @@ top:
(hdr->b_l1hdr.b_pabd != NULL && !encrypted_read))) {
boolean_t is_data = !HDR_ISTYPE_METADATA(hdr);
/*
* Verify the block pointer contents are reasonable. This
* should always be the case since the blkptr is protected by
* a checksum.
*/
if (!zfs_blkptr_verify(spa, bp, BLK_CONFIG_SKIP,
BLK_VERIFY_LOG)) {
mutex_exit(hash_lock);
rc = SET_ERROR(ECKSUM);
goto done;
}
if (HDR_IO_IN_PROGRESS(hdr)) {
if (*arc_flags & ARC_FLAG_CACHED_ONLY) {
mutex_exit(hash_lock);
@@ -5761,6 +5760,20 @@ top:
goto done;
}
/*
* Verify the block pointer contents are reasonable. This
* should always be the case since the blkptr is protected by
* a checksum.
*/
if (!zfs_blkptr_verify(spa, bp,
(zio_flags & ZIO_FLAG_CONFIG_WRITER) ?
BLK_CONFIG_HELD : BLK_CONFIG_NEEDED, BLK_VERIFY_LOG)) {
if (hash_lock != NULL)
mutex_exit(hash_lock);
rc = SET_ERROR(ECKSUM);
goto done;
}
if (hdr == NULL) {
/*
* This block is not in the cache or it has