Commit ddfd08cb authored by Josef Bacik's avatar Josef Bacik Committed by David Sterba
Browse files

btrfs: do not block on deleted bgs mutex in the cleaner 



While running some stress tests I started getting hung task messages.
This is because the delete unused block groups code has to take the
delete_unused_bgs_mutex to do it's work, which is taken by balance to
make sure we don't delete block groups while we're balancing.

The problem is that balance can take a while, and so we were getting
hung task warnings.  We don't need to block and run these things, and
the cleaner is needed to do other work, so trylock on this mutex and
just bail if we can't acquire it right away.

Reviewed-by: default avatarNikolay Borisov <nborisov@suse.com>
Signed-off-by: default avatarJosef Bacik <josef@toxicpanda.com>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 867ed321

fs/btrfs/block-group.c

+8 −3
Original line number Diff line number Diff line
@@ -1262,6 +1262,13 @@ void btrfs_delete_unused_bgs(struct btrfs_fs_info *fs_info) 
	if (!test_bit(BTRFS_FS_OPEN, &fs_info->flags))

		return;



	/*

	 * Long running balances can keep us blocked here for eternity, so

	 * simply skip deletion if we're unable to get the mutex.

	 */

	if (!mutex_trylock(&fs_info->delete_unused_bgs_mutex))

		return;



	spin_lock(&fs_info->unused_bgs_lock);

	while (!list_empty(&fs_info->unused_bgs)) {

		int trimming;
@@ -1281,8 +1288,6 @@ void btrfs_delete_unused_bgs(struct btrfs_fs_info *fs_info) 


		btrfs_discard_cancel_work(&fs_info->discard_ctl, block_group);



		mutex_lock(&fs_info->delete_unused_bgs_mutex);



		/* Don't want to race with allocators so take the groups_sem */

		down_write(&space_info->groups_sem);
@@ -1426,11 +1431,11 @@ void btrfs_delete_unused_bgs(struct btrfs_fs_info *fs_info) 
end_trans:

		btrfs_end_transaction(trans);

next:

		mutex_unlock(&fs_info->delete_unused_bgs_mutex);

		btrfs_put_block_group(block_group);

		spin_lock(&fs_info->unused_bgs_lock);

	}

	spin_unlock(&fs_info->unused_bgs_lock);

	mutex_unlock(&fs_info->delete_unused_bgs_mutex);

	return;



flip_async: