btrfs: reset block group chunk force if we have to wait

[ Upstream commit 1314ca78b2c35d3e7d0f097268a2ee6dc0d369ef ]

If you try to force a chunk allocation, but you race with another chunk
allocation, you will end up waiting on the chunk allocation that just
occurred and then allocate another chunk.  If you have many threads all
doing this at once you can way over-allocate chunks.

Fix this by resetting force to NO_FORCE, that way if we think we need to
allocate we can, otherwise we don't force another chunk allocation if
one is already happening.

Reviewed-by: Filipe Manana <fdmanana@suse.com>
CC: stable@vger.kernel.org # 5.4+
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/fs/btrfs/block-group.c b/fs/btrfs/block-group.c
index 667b7025d5030ed34719325990a84994b7d14646..1deca5164c23cd561bbb0986d769a7d484ffd0ae 100644 (file)
--- a/fs/btrfs/block-group.c
+++ b/fs/btrfs/block-group.c
@@ -3724,6 +3724,7 @@ int btrfs_chunk_alloc(struct btrfs_trans_handle *trans, u64 flags,
                         * attempt.
                         */
                        wait_for_alloc = true;
+                       force = CHUNK_ALLOC_NO_FORCE;
                        spin_unlock(&space_info->lock);
                        mutex_lock(&fs_info->chunk_mutex);
                        mutex_unlock(&fs_info->chunk_mutex);