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 <david.chen@osnexus.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Olaf Faaland <faaland1@llnl.gov>
Closes #5983
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)
{
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,
ASSERT(flags & ZIO_FLAG_CONFIG_WRITER);
zio_nowait(zio_read_phys(zio, vd,
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)
{
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,
ASSERT(flags & ZIO_FLAG_CONFIG_WRITER);
zio_nowait(zio_write_phys(zio, vd,