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arc: avoid possible deadlock in arc_read

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In l2arc_evict(), the config lock may be acquired in reverse order
(e.g., first the config lock (writer), then a hash lock) unlike in
arc_read() during scenarios like L2ARC device removal. To avoid
deadlocks, if the attempt to acquire the config lock (reader) fails
in arc_read(), release the hash lock, wait for the config lock, and
retry from the beginning.

Reviewed-by: Alexander Motin <mav@FreeBSD.org>
Signed-off-by: Ameer Hamza <ahamza@ixsystems.com>
Closes #17071
This commit is contained in:
Ameer Hamza
2025-02-26 00:32:12 +05:00
committed by GitHub
parent 701093c44f
commit ab3db6d15d
6 changed files with 40 additions and 16 deletions
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module/zfs/zio.c
+12 -7
View File
@@ -1164,7 +1164,7 @@ zfs_blkptr_verify_log(spa_t *spa, const blkptr_t *bp,
* 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
* If everything checks out 0 is returned. The zfs_blkptr_verify
* argument controls the behavior when an invalid field is detected.
*
* Values for blk_verify_flag:
@@ -1179,7 +1179,7 @@ zfs_blkptr_verify_log(spa_t *spa, const blkptr_t *bp,
* BLK_CONFIG_SKIP: skip checks which require SCL_VDEV, for better
* performance
*/
boolean_t
int
zfs_blkptr_verify(spa_t *spa, const blkptr_t *bp,
enum blk_config_flag blk_config, enum blk_verify_flag blk_verify)
{
@@ -1211,7 +1211,7 @@ zfs_blkptr_verify(spa_t *spa, const blkptr_t *bp,
"blkptr at %px has invalid PSIZE %llu",
bp, (longlong_t)BPE_GET_PSIZE(bp));
}
return (errors == 0);
return (errors ? ECKSUM : 0);
}
if (unlikely(BP_GET_CHECKSUM(bp) >= ZIO_CHECKSUM_FUNCTIONS)) {
errors += zfs_blkptr_verify_log(spa, bp, blk_verify,
@@ -1229,7 +1229,7 @@ zfs_blkptr_verify(spa_t *spa, const blkptr_t *bp,
* will be done once the zio is executed in vdev_mirror_map_alloc.
*/
if (unlikely(!spa->spa_trust_config))
return (errors == 0);
return (errors ? ECKSUM : 0);
switch (blk_config) {
case BLK_CONFIG_HELD:
@@ -1238,8 +1238,12 @@ zfs_blkptr_verify(spa_t *spa, const blkptr_t *bp,
case BLK_CONFIG_NEEDED:
spa_config_enter(spa, SCL_VDEV, bp, RW_READER);
break;
case BLK_CONFIG_NEEDED_TRY:
if (!spa_config_tryenter(spa, SCL_VDEV, bp, RW_READER))
return (EBUSY);
break;
case BLK_CONFIG_SKIP:
return (errors == 0);
return (errors ? ECKSUM : 0);
default:
panic("invalid blk_config %u", blk_config);
}
@@ -1294,10 +1298,11 @@ zfs_blkptr_verify(spa_t *spa, const blkptr_t *bp,
bp, i, (longlong_t)offset);
}
}
if (blk_config == BLK_CONFIG_NEEDED)
if (blk_config == BLK_CONFIG_NEEDED || blk_config ==
BLK_CONFIG_NEEDED_TRY)
spa_config_exit(spa, SCL_VDEV, bp);
return (errors == 0);
return (errors ? ECKSUM : 0);
}
boolean_t