btrfs: handle invalid root reference found in btrfs_find_root()

The btrfs_find_root() looks up a root by a key, allowing to do an
inexact search when key->offset is -1.  It's never expected to find such
item, as it would break allowed the range of a root id.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/root-tree.c b/fs/btrfs/root-tree.c
index ce831660550bfd117c27ca6a4cf8f6a0695b6728..4bb538a372ce56404de84d6ddbca7fb951715949 100644 (file)
--- a/fs/btrfs/root-tree.c
+++ b/fs/btrfs/root-tree.c
@@ -81,7 +81,14 @@ int btrfs_find_root(struct btrfs_root *root, const struct btrfs_key *search_key,
                if (ret > 0)
                        goto out;
        } else {
-               BUG_ON(ret == 0);               /* Logical error */
+               /*
+                * Key with offset -1 found, there would have to exist a root
+                * with such id, but this is out of the valid range.
+                */
+               if (ret == 0) {
+                       ret = -EUCLEAN;
+                       goto out;
+               }
                if (path->slots[0] == 0)
                        goto out;
                path->slots[0]--;