diff options
| author | Olaf Faaland <[email protected]> | 2017-04-21 14:26:43 -0700 |
|---|---|---|
| committer | Brian Behlendorf <[email protected]> | 2017-04-21 14:26:43 -0700 |
| commit | 0091d66f4ebfeb83f70212ab92a4d5a8e4a9c4dc (patch) | |
| tree | 84e004a1c25257059e274057fd470c56dd304e6a /module | |
| parent | d6418de057ecb71fb4cdc1b0a89d5265d13d121a (diff) | |
Correct lock ASSERTs in vdev_label_read/write
The existing assertions in vdev_label_read() and vdev_label_write(),
testing which config locks are held, are incorrect. The assertions
test for locks which exceed what is required for safety.
Both vdev_label_{read,write}() are changed to assert SCL_STATE is held
as RW_READER or RW_WRITER. This is safe because:
Changes to the vdev tree occur under SCL_ALL as RW_WRITER, via
spa_vdev_enter() and spa_vdev_exit().
Changes to vdev state occur under SCL_STATE_ALL as RW_WRITER, via
spa_vdev_state_enter() and spa_vdev_state_exit().
Therefore, the new assertions guarantee that the vdev cannot change
out from under a zio, and I/O to a specified leaf vdev's label is
safe.
Furthermore, this is consistent with the SPA locking discussion in
spa_misc.c, "For any zio operation that takes an explicit vdev_t
argument ... zio_read_phys(), or zio_write_phys() ... SCL_STATE as
reader suffices."
Reviewed-by: Chunwei Chen <[email protected]>
Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by: Olaf Faaland <[email protected]>
Closes #5983
Diffstat (limited to 'module')
| -rw-r--r-- | module/zfs/vdev_label.c | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/module/zfs/vdev_label.c b/module/zfs/vdev_label.c index 54c54237b..b50a297bc 100644 --- a/module/zfs/vdev_label.c +++ b/module/zfs/vdev_label.c @@ -182,8 +182,9 @@ static void vdev_label_read(zio_t *zio, vdev_t *vd, int l, abd_t *buf, uint64_t offset, uint64_t size, zio_done_func_t *done, void *private, int flags) { - ASSERT(spa_config_held(zio->io_spa, SCL_STATE_ALL, RW_WRITER) == - SCL_STATE_ALL); + ASSERT( + spa_config_held(zio->io_spa, SCL_STATE, RW_READER) == SCL_STATE || + spa_config_held(zio->io_spa, SCL_STATE, RW_WRITER) == SCL_STATE); ASSERT(flags & ZIO_FLAG_CONFIG_WRITER); zio_nowait(zio_read_phys(zio, vd, @@ -196,10 +197,9 @@ static void vdev_label_write(zio_t *zio, vdev_t *vd, int l, abd_t *buf, uint64_t offset, uint64_t size, zio_done_func_t *done, void *private, int flags) { - ASSERT(spa_config_held(zio->io_spa, SCL_ALL, RW_WRITER) == SCL_ALL || - (spa_config_held(zio->io_spa, SCL_CONFIG | SCL_STATE, RW_READER) == - (SCL_CONFIG | SCL_STATE) && - dsl_pool_sync_context(spa_get_dsl(zio->io_spa)))); + ASSERT( + spa_config_held(zio->io_spa, SCL_STATE, RW_READER) == SCL_STATE || + spa_config_held(zio->io_spa, SCL_STATE, RW_WRITER) == SCL_STATE); ASSERT(flags & ZIO_FLAG_CONFIG_WRITER); zio_nowait(zio_write_phys(zio, vd, |