From: Naohiro Aota naohiro.aota@wdc.com
commit 1ada69f61c88abb75a1038ee457633325658a183 upstream.
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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/btrfs/extent-tree.c | 20 ++++++++++++++++---- 1 file changed, 16 insertions(+), 4 deletions(-)
--- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -3790,23 +3790,35 @@ static int do_allocation_zoned(struct bt 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);