[PATCH v2 3/3] btrfs-progs: dir-item: Make btrfs_delete_one_dir_name more robust to handle corrupted name len

[Qu Wenruo <wqu@suse.com>]

Function btrfs_delete_one_dir_name() will check if the dir_item is the
last content of the item, and delete the whole item if needed.

However if @name_len of one dir_item/dir_index is corrupted and larger
than the item size, the function will still try to treat it as partly
remove, which will screw up the whole leaf.

This patch will enhance the item deletion check, to cover corrupted name
len, so in that case we just delete the whole item.

Signed-off-by: Qu Wenruo <wqu@suse.com>
---
 dir-item.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/dir-item.c b/dir-item.c
index e0a0ab4d7a5d..35e0615fb423 100644
--- a/dir-item.c
+++ b/dir-item.c
@@ -263,7 +263,6 @@ int btrfs_delete_one_dir_name(struct btrfs_trans_handle *trans,
 			      struct btrfs_path *path,
 			      struct btrfs_dir_item *di)
 {
-
 	struct extent_buffer *leaf;
 	u32 sub_item_len;
 	u32 item_len;
@@ -273,7 +272,15 @@ int btrfs_delete_one_dir_name(struct btrfs_trans_handle *trans,
 	sub_item_len = sizeof(*di) + btrfs_dir_name_len(leaf, di) +
 		btrfs_dir_data_len(leaf, di);
 	item_len = btrfs_item_size_nr(leaf, path->slots[0]);
-	if (sub_item_len == item_len) {
+
+	/*
+	 * If @sub_item_len is longer than @item_len, then it means the
+	 * name_len is just corrupted.
+	 * No good idea to know if there is anything we can recover from
+	 * the corrupted item.
+	 * Just delete the item.
+	 */
+	if (sub_item_len >= item_len) {
 		ret = btrfs_del_item(trans, root, path);
 	} else {
 		unsigned long ptr = (unsigned long)di;
-- 
2.15.1