Btrfs: fix the inode ref searches done by btrfs_search_path_in_tree

This is used by the inode lookup ioctl to follow all the backrefs up
to the subvol root.  But the search being done would sometimes land one
past the last item in the leaf instead of finding the backref.

This changes the search to look for the highest possible backref and hop
back one item.  It also fixes a leaked path on failure to find the root.

Signed-off-by: Chris Mason <chris.mason@oracle.com>

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 1e462de6556e21ea37802fab6588f2e65177bfa5..2845c6ceecd247f78adcd2b049ea220bbe764ff4 100644 (file)
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -1147,12 +1147,13 @@ static noinline int btrfs_search_path_in_tree(struct btrfs_fs_info *info,
        root = btrfs_read_fs_root_no_name(info, &key);
        if (IS_ERR(root)) {
                printk(KERN_ERR "could not find root %llu\n", tree_id);
-               return -ENOENT;
+               ret = -ENOENT;
+               goto out;
        }
 
        key.objectid = dirid;
        key.type = BTRFS_INODE_REF_KEY;
-       key.offset = 0;
+       key.offset = (u64)-1;
 
        while(1) {
                ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
@@ -1161,6 +1162,8 @@ static noinline int btrfs_search_path_in_tree(struct btrfs_fs_info *info,
 
                l = path->nodes[0];
                slot = path->slots[0];
+               if (ret > 0 && slot > 0)
+                       slot--;
                btrfs_item_key_to_cpu(l, &key, slot);
 
                if (ret > 0 && (key.objectid != dirid ||
@@ -1184,7 +1187,7 @@ static noinline int btrfs_search_path_in_tree(struct btrfs_fs_info *info,
 
                btrfs_release_path(root, path);
                key.objectid = key.offset;
-               key.offset = 0;
+               key.offset = (u64)-1;
                dirid = key.objectid;
 
        }