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Avoid deadlock when removing L2ARC devices under I/O 

In case we have I/O and try to remove an L2ARC device a deadlock might
occur. arc_read()->zio_read()->zfs_blkptr_verify() waits for SCL_VDEV
to be dropped while holding the hash_lock. However, spa_l2cache_load()
holds SCL_ALL and waits for the hash_lock in l2arc_evict().

Fix this by moving zfs_blkptr_verify() to the top top arc_read() before
the hash_lock is taken. Verify the block pointer and return a checksum
error if damaged rather than halting the system, by using
BLK_VERIFY_LOG instead of BLK_VERIFY_HALT.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Mark Maybee <mark.maybee@delphix.com>
Signed-off-by: George Amanakis <gamanakis@gmail.com>
Closes #12054
This commit is contained in:
George Amanakis 2021-06-17 03:17:42 +03:00 committed by GitHub
parent ff31750405
commit 9ffcaa370a
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GPG Key ID: 4AEE18F83AFDEB23
2 changed files with 6 additions and 14 deletions
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17
module/zfs/arc.c
View File

@ -5944,6 +5944,12 @@ top:
* Embedded BP's have no DVA and require no I/O to "read".
* Create an anonymous arc buf to back it.
*/
if (!zfs_blkptr_verify(spa, bp, zio_flags &
ZIO_FLAG_CONFIG_WRITER, BLK_VERIFY_LOG)) {
rc = SET_ERROR(ECKSUM);
goto out;
}
hdr = buf_hash_find(guid, bp, &hash_lock);
}
@ -6115,17 +6121,6 @@ top:
goto out;
}
/*
* Gracefully handle a damaged logical block size as a
* checksum error.
*/
if (lsize > spa_maxblocksize(spa)) {
rc = SET_ERROR(ECKSUM);
if (hash_lock != NULL)
mutex_exit(hash_lock);
goto out;
}
if (hdr == NULL) {
/*
* This block is not in the cache or it has

3
module/zfs/zio.c
View File

@ -1107,9 +1107,6 @@ zio_read(zio_t *pio, spa_t *spa, const blkptr_t *bp,
{
zio_t *zio;
(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,
ZIO_TYPE_READ, priority, flags, NULL, 0, zb,