btrfs: don't ignore inode missing when replaying log tree

During log replay, at add_inode_ref(), we return -ENOENT if our current
inode isn't found on the subvolume tree or if a parent directory isn't
found. The error comes from btrfs_iget_logging() <- btrfs_iget() <-
btrfs_read_locked_inode().

The single caller of add_inode_ref(), replay_one_buffer(), ignores an
-ENOENT error because it expects that error to mean only that a parent
directory wasn't found and that is ok.

Before commit 5f61b96 ("btrfs: fix inode lookup error handling during
log replay") we were converting any error when getting a parent directory
to -ENOENT and any error when getting the current inode to -EIO, so our
caller would fail log replay in case we can't find the current inode.
After that commit however in case the current inode is not found we return
-ENOENT to the caller and therefore it ignores the critical fact that the
current inode was not found in the subvolume tree.

Fix this by converting -ENOENT to 0 when we don't find a parent directory,
returning -ENOENT when we don't find the current inode and making the
caller, replay_one_buffer(), not ignore -ENOENT anymore.

Fixes: 5f61b96 ("btrfs: fix inode lookup error handling during log replay")
Reviewed-by: Boris Burkov <[email protected]>
Signed-off-by: Filipe Manana <[email protected]>
Signed-off-by: David Sterba <[email protected]>

Author: fdmanana

fs/btrfs/tree-log.c

@@ -1416,6 +1416,8 @@ static noinline int add_inode_ref(struct btrfs_trans_handle *trans,
 	dir = btrfs_iget_logging(parent_objectid, root);
 	if (IS_ERR(dir)) {
 		ret = PTR_ERR(dir);
+		if (ret == -ENOENT)
+			ret = 0;
 		dir = NULL;
 		goto out;
 	}
@@ -1440,6 +1442,15 @@ static noinline int add_inode_ref(struct btrfs_trans_handle *trans,
 				if (IS_ERR(dir)) {
 					ret = PTR_ERR(dir);
 					dir = NULL;
+					/*
+					 * A new parent dir may have not been
+					 * logged and not exist in the subvolume
+					 * tree, see the comment above before
+					 * the loop when getting the first
+					 * parent dir.
+					 */
+					if (ret == -ENOENT)
+						ret = 0;
 					goto out;
 				}
 			}
@@ -2551,9 +2562,8 @@ static int replay_one_buffer(struct btrfs_root *log, struct extent_buffer *eb,
 			   key.type == BTRFS_INODE_EXTREF_KEY) {
 			ret = add_inode_ref(wc->trans, root, log, path,
 					    eb, i, &key);
-			if (ret && ret != -ENOENT)
+			if (ret)
 				break;
-			ret = 0;
 		} else if (key.type == BTRFS_EXTENT_DATA_KEY) {
 			ret = replay_one_extent(wc->trans, root, path,
 						eb, i, &key);