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Fix deadlock on I/O errors during device removal

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spa_vdev_remove_thread() should not hold svr_lock while loading a
metaslab.  It may block ZIO threads, required to handle metaslab
loading, at least in case of read errors causing recovery writes.

Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Reviewed-by: Rob Norris <robn@despairlabs.com>
Signed-off-by:	Alexander Motin <mav@FreeBSD.org>
Sponsored by:	iXsystems, Inc.
Closes #17145
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Alexander Motin 2025-03-19 14:48:47 -04:00 committed by GitHub
parent 83fa051ceb
commit 676b7ef104
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GPG Key ID: B5690EEEBB952194
1 changed files with 39 additions and 19 deletions
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58
module/zfs/vdev_removal.c
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@ -1621,6 +1621,9 @@ spa_vdev_remove_thread(void *arg)
vca.vca_read_error_bytes = 0;
vca.vca_write_error_bytes = 0;
zfs_range_tree_t *segs = zfs_range_tree_create(NULL, ZFS_RANGE_SEG64,
NULL, 0, 0);
mutex_enter(&svr->svr_lock);
/*
@ -1633,7 +1636,9 @@ spa_vdev_remove_thread(void *arg)
metaslab_t *msp = vd->vdev_ms[msi];
ASSERT3U(msi, <=, vd->vdev_ms_count);
again:
ASSERT0(zfs_range_tree_space(svr->svr_allocd_segs));
mutex_exit(&svr->svr_lock);
mutex_enter(&msp->ms_sync_lock);
mutex_enter(&msp->ms_lock);
@ -1646,36 +1651,49 @@ spa_vdev_remove_thread(void *arg)
}
/*
* If the metaslab has ever been allocated from (ms_sm!=NULL),
* If the metaslab has ever been synced (ms_sm != NULL),
* read the allocated segments from the space map object
* into svr_allocd_segs. Since we do this while holding
* svr_lock and ms_sync_lock, concurrent frees (which
* ms_lock and ms_sync_lock, concurrent frees (which
* would have modified the space map) will wait for us
* to finish loading the spacemap, and then take the
* appropriate action (see free_from_removing_vdev()).
*/
if (msp->ms_sm != NULL) {
VERIFY0(space_map_load(msp->ms_sm,
svr->svr_allocd_segs, SM_ALLOC));
if (msp->ms_sm != NULL)
VERIFY0(space_map_load(msp->ms_sm, segs, SM_ALLOC));
zfs_range_tree_walk(msp->ms_unflushed_allocs,
zfs_range_tree_add, svr->svr_allocd_segs);
zfs_range_tree_walk(msp->ms_unflushed_frees,
zfs_range_tree_remove, svr->svr_allocd_segs);
zfs_range_tree_walk(msp->ms_freeing,
zfs_range_tree_remove, svr->svr_allocd_segs);
/*
* When we are resuming from a paused removal (i.e.
* when importing a pool with a removal in progress),
* discard any state that we have already processed.
*/
zfs_range_tree_clear(svr->svr_allocd_segs, 0,
start_offset);
/*
* We could not hold svr_lock while loading space map, or we
* could hit deadlock in a ZIO pipeline, having to wait for
* it. But we can not block for it here under metaslab locks,
* or it would be a lock ordering violation.
*/
if (!mutex_tryenter(&svr->svr_lock)) {
mutex_exit(&msp->ms_lock);
mutex_exit(&msp->ms_sync_lock);
zfs_range_tree_vacate(segs, NULL, NULL);
mutex_enter(&svr->svr_lock);
goto again;
}
zfs_range_tree_swap(&segs, &svr->svr_allocd_segs);
zfs_range_tree_walk(msp->ms_unflushed_allocs,
zfs_range_tree_add, svr->svr_allocd_segs);
zfs_range_tree_walk(msp->ms_unflushed_frees,
zfs_range_tree_remove, svr->svr_allocd_segs);
zfs_range_tree_walk(msp->ms_freeing,
zfs_range_tree_remove, svr->svr_allocd_segs);
mutex_exit(&msp->ms_lock);
mutex_exit(&msp->ms_sync_lock);
/*
* When we are resuming from a paused removal (i.e.
* when importing a pool with a removal in progress),
* discard any state that we have already processed.
*/
zfs_range_tree_clear(svr->svr_allocd_segs, 0, start_offset);
vca.vca_msp = msp;
zfs_dbgmsg("copying %llu segments for metaslab %llu",
(u_longlong_t)zfs_btree_numnodes(
@ -1751,6 +1769,8 @@ spa_vdev_remove_thread(void *arg)
spa_config_exit(spa, SCL_CONFIG, FTAG);
zfs_range_tree_destroy(segs);
/*
* Wait for all copies to finish before cleaning up the vca.
*/