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Prevent race in blkptr_verify against device removal

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When we check the vdev of the blkptr in zfs_blkptr_verify, we can run 
into a race condition where that vdev is temporarily unavailable. This 
happens when a device removal operation and the old vdev_t has been 
removed from the array, but the new indirect vdev has not yet been 
inserted.

We hold the spa_config_lock while doing our sensitive verification. 
To ensure that we don't deadlock, we only grab the lock if we don't 
have config_writer held. In addition, I had to const the tags of the 
refcounts and the spa_config_lock arguments.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Serapheim Dimitropoulos <serapheim@delphix.com>
Signed-off-by: Paul Dagnelie <pcd@delphix.com>
Closes #9112
This commit is contained in:
Paul Dagnelie
2019-08-13 20:24:43 -07:00
committed by Brian Behlendorf
parent 8e556c5ebc
commit dc04a8c757
5 changed files with 35 additions and 28 deletions
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module/zfs/zio.c
+11 -5
View File
@@ -881,8 +881,8 @@ zio_root(spa_t *spa, zio_done_func_t *done, void *private, enum zio_flag flags)
return (zio_null(NULL, spa, NULL, done, private, flags));
}
void
zfs_blkptr_verify(spa_t *spa, const blkptr_t *bp)
static void
zfs_blkptr_verify(spa_t *spa, const blkptr_t *bp, boolean_t config_held)
{
if (!DMU_OT_IS_VALID(BP_GET_TYPE(bp))) {
zfs_panic_recover("blkptr at %p has invalid TYPE %llu",
@@ -921,6 +921,10 @@ zfs_blkptr_verify(spa_t *spa, const blkptr_t *bp)
if (!spa->spa_trust_config)
return;
if (!config_held)
spa_config_enter(spa, SCL_VDEV, bp, RW_READER);
else
ASSERT(spa_config_held(spa, SCL_VDEV, RW_WRITER));
/*
* Pool-specific checks.
*
@@ -969,6 +973,8 @@ zfs_blkptr_verify(spa_t *spa, const blkptr_t *bp)
bp, i, (longlong_t)offset);
}
}
if (!config_held)
spa_config_exit(spa, SCL_VDEV, bp);
}
boolean_t
@@ -1008,7 +1014,7 @@ zio_read(zio_t *pio, spa_t *spa, const blkptr_t *bp,
{
zio_t *zio;
zfs_blkptr_verify(spa, bp);
zfs_blkptr_verify(spa, bp, flags & ZIO_FLAG_CONFIG_WRITER);
zio = zio_create(pio, spa, BP_PHYSICAL_BIRTH(bp), bp,
data, size, size, done, private,
@@ -1101,7 +1107,7 @@ void
zio_free(spa_t *spa, uint64_t txg, const blkptr_t *bp)
{
zfs_blkptr_verify(spa, bp);
zfs_blkptr_verify(spa, bp, B_FALSE);
/*
* The check for EMBEDDED is a performance optimization. We
@@ -1171,7 +1177,7 @@ zio_claim(zio_t *pio, spa_t *spa, uint64_t txg, const blkptr_t *bp,
{
zio_t *zio;
zfs_blkptr_verify(spa, bp);
zfs_blkptr_verify(spa, bp, flags & ZIO_FLAG_CONFIG_WRITER);
if (BP_IS_EMBEDDED(bp))
return (zio_null(pio, spa, NULL, NULL, NULL, 0));