[PATCH v5 16/18] btrfs: use correct name hash for nokey names

[Sweet Tea Dorminy <sweettea-kernel@dorminy.me>]

For encrypted or unencrypted names, we calculate the offset for the dir
item by hashing the name for the dir item. However, this doesn't work
for a long nokey name, where we do not have the complete ciphertext.
Instead, fscrypt stores the filesystem-provided hash in the nokey name,
and we can extract it from the fscrypt_name structure in such a case.

Signed-off-by: Sweet Tea Dorminy <sweettea-kernel@dorminy.me>
---
 fs/btrfs/dir-item.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/fs/btrfs/dir-item.c b/fs/btrfs/dir-item.c
index ce046cdabbe9..70cba4003efa 100644
--- a/fs/btrfs/dir-item.c
+++ b/fs/btrfs/dir-item.c
@@ -257,8 +257,12 @@ struct btrfs_dir_item *btrfs_lookup_dir_item_fname(struct btrfs_trans_handle *tr
 
 	key.objectid = dir;
 	key.type = BTRFS_DIR_ITEM_KEY;
-	key.offset = btrfs_name_hash(name->disk_name.name, name->disk_name.len);
-	/* XXX get the right hash for no-key names */
+
+	if (!name->disk_name.name)
+		key.offset = name->hash | ((u64)name->minor_hash << 32);
+	else
+		key.offset = btrfs_name_hash(name->disk_name.name,
+					     name->disk_name.len);
 
 	ret = btrfs_search_slot(trans, root, &key, path, mod, -mod);
 	if (ret == 0)
-- 
2.37.3