[PATCH v3 2/6] btrfs: use an on-stack path in btrfs_del_orphan_item()

[Jeff Layton]

btrfs_del_orphan_item() allocated a btrfs_path with btrfs_alloc_path()
which returns -ENOMEM on failure. It is called from btrfs_orphan_del(),
and btrfs_link() turns any error from it into a transaction abort. So a
path allocation failure there (reachable via linkat() on an O_TMPFILE
under memory pressure) turns a recoverable error into an abort.

btrfs_path is only ~112 bytes, so allocate it on the stack instead.
Unlike the insert case there are multiple exit points after the search,
so release the path via a common out: label.

Assisted-by: LLM
Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
---
 fs/btrfs/orphan.c | 25 +++++++++++++------------
 1 file changed, 13 insertions(+), 12 deletions(-)

diff --git a/fs/btrfs/orphan.c b/fs/btrfs/orphan.c
index 72e1adec39d8..ae1685f26dec 100644
--- a/fs/btrfs/orphan.c
+++ b/fs/btrfs/orphan.c
@@ -25,23 +25,24 @@ int btrfs_insert_orphan_item(struct btrfs_trans_handle *trans,
 int btrfs_del_orphan_item(struct btrfs_trans_handle *trans,
 			  struct btrfs_root *root, u64 offset)
 {
-	BTRFS_PATH_AUTO_FREE(path);
+	struct btrfs_path path = { 0 };
 	struct btrfs_key key;
-	int ret = 0;
+	int ret;
 
 	key.objectid = BTRFS_ORPHAN_OBJECTID;
 	key.type = BTRFS_ORPHAN_ITEM_KEY;
 	key.offset = offset;
 
-	path = btrfs_alloc_path();
-	if (!path)
-		return -ENOMEM;
-
-	ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
+	ret = btrfs_search_slot(trans, root, &key, &path, -1, 1);
 	if (ret < 0)
-		return ret;
-	if (ret)
-		return -ENOENT;
-
-	return btrfs_del_item(trans, root, path);
+		goto out;
+	if (ret) {
+		ret = -ENOENT;
+		goto out;
+	}
+
+	ret = btrfs_del_item(trans, root, &path);
+out:
+	btrfs_release_path(&path);
+	return ret;
 }

-- 
2.55.0