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

[ Upstream commit b458761ba924e524f93716713eae84498044e340 ]

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 c6c5a22ff6e86a4a0fcddafd8160ee0b860558fe..4b2282aa274e47d51ebf89d8486f851385435cb6 100644 (file)
--- a/fs/btrfs/block-group.c
+++ b/fs/btrfs/block-group.c
@@ -3632,6 +3632,7 @@ 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);