btrfs: deal with errors when adding inode reference during log replay

At __inode_add_ref(), we treating any error returned from
btrfs_lookup_dir_item() or from btrfs_lookup_dir_index_item() as meaning
that there is no existing directory entry in the fs/subvolume tree.
This is not correct since we can get errors such as, for example, -EIO
when reading extent buffers while searching the fs/subvolume's btree.

So fix that and return the error to the caller when it is not -ENOENT.

CC: stable@vger.kernel.org # 4.14+
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/tree-log.c

@@ -1190,7 +1190,10 @@ next:
 	/* look for a conflicting sequence number */
 	di = btrfs_lookup_dir_index_item(trans, root, path, btrfs_ino(dir),
 					 ref_index, name, namelen, 0);
-	if (di && !IS_ERR(di)) {
+	if (IS_ERR(di)) {
+		if (PTR_ERR(di) != -ENOENT)
+			return PTR_ERR(di);
+	} else if (di) {
 		ret = drop_one_dir_item(trans, root, path, dir, di);
 		if (ret)
 			return ret;
@@ -1200,7 +1203,9 @@ next:
 	/* look for a conflicting name */
 	di = btrfs_lookup_dir_item(trans, root, path, btrfs_ino(dir),
 				   name, namelen, 0);
-	if (di && !IS_ERR(di)) {
+	if (IS_ERR(di)) {
+		return PTR_ERR(di);
+	} else if (di) {
 		ret = drop_one_dir_item(trans, root, path, dir, di);
 		if (ret)
 			return ret;