Merging upstream version 4.19.304.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 16 insertions, 3 deletions

diff --git a/fs/btrfs/delayed-inode.c b/fs/btrfs/delayed-inode.c
index 1fbe2dee1..469a90b07 100644
--- a/fs/btrfs/delayed-inode.c
+++ b/fs/btrfs/delayed-inode.c
@@ -1171,20 +1171,33 @@ static int __btrfs_run_delayed_items(struct btrfs_trans_handle *trans, int nr)
 		ret = __btrfs_commit_inode_delayed_items(trans, path,
 							 curr_node);
 		if (ret) {
-			btrfs_release_delayed_node(curr_node);
-			curr_node = NULL;
 			btrfs_abort_transaction(trans, ret);
 			break;
 		}
 
 		prev_node = curr_node;
 		curr_node = btrfs_next_delayed_node(curr_node);
+		/*
+		 * See the comment below about releasing path before releasing
+		 * node. If the commit of delayed items was successful the path
+		 * should always be released, but in case of an error, it may
+		 * point to locked extent buffers (a leaf at the very least).
+		 */
+		ASSERT(path->nodes[0] == NULL);
 		btrfs_release_delayed_node(prev_node);
 	}
 
+	/*
+	 * Release the path to avoid a potential deadlock and lockdep splat when
+	 * releasing the delayed node, as that requires taking the delayed node's
+	 * mutex. If another task starts running delayed items before we take
+	 * the mutex, it will first lock the mutex and then it may try to lock
+	 * the same btree path (leaf).
+	 */
+	btrfs_free_path(path);
+
 	if (curr_node)
 		btrfs_release_delayed_node(curr_node);
-	btrfs_free_path(path);
 	trans->block_rsv = block_rsv;
 
 	return ret;