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btrfs: zoned: unset dedicated block group on allocation failure

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Allocating an extent from a block group can fail for various reasons.
When an allocation from a dedicated block group (for tree-log or
relocation data) fails, we need to unregister it as a dedicated one so
that we can allocate a new block group for the dedicated one.

However, we are returning early when the block group in case it is
read-only, fully used, or not be able to activate the zone. As a result,
we keep the non-usable block group as a dedicated one, leading to
further allocation failure. With many block groups, the allocator will
iterate hopeless loop to find a free extent, results in a hung task.

Fix the issue by delaying the return and doing the proper cleanups.

CC: stable@vger.kernel.org # 5.16
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Naohiro Aota 2021-12-08 00:35:47 +09:00 committed by David Sterba
parent 7367271000
commit 1ada69f61c
1 changed files with 16 additions and 4 deletions
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20
fs/btrfs/extent-tree.c
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@ -3805,23 +3805,35 @@ static int do_allocation_zoned(struct btrfs_block_group *block_group,
spin_unlock(&fs_info->relocation_bg_lock);
if (skip)
return 1;
/* Check RO and no space case before trying to activate it */
spin_lock(&block_group->lock);
if (block_group->ro ||
block_group->alloc_offset == block_group->zone_capacity) {
spin_unlock(&block_group->lock);
return 1;
ret = 1;
/*
* May need to clear fs_info->{treelog,data_reloc}_bg.
* Return the error after taking the locks.
*/
}
spin_unlock(&block_group->lock);
if (!btrfs_zone_activate(block_group))
return 1;
if (!ret && !btrfs_zone_activate(block_group)) {
ret = 1;
/*
* May need to clear fs_info->{treelog,data_reloc}_bg.
* Return the error after taking the locks.
*/
}
spin_lock(&space_info->lock);
spin_lock(&block_group->lock);
spin_lock(&fs_info->treelog_bg_lock);
spin_lock(&fs_info->relocation_bg_lock);
if (ret)
goto out;
ASSERT(!ffe_ctl->for_treelog ||
block_group->start == fs_info->treelog_bg ||
fs_info->treelog_bg == 0);