Clean up btrfs_get_parent() a little more, fix a free-after-free bug

Date: Tue, 19 Aug 2008 22:33:04 +0100
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

diff --git a/fs/btrfs/export.c b/fs/btrfs/export.c
index 36cbc68..292b0b2 100644 (file)
--- a/fs/btrfs/export.c
+++ b/fs/btrfs/export.c
@@ -165,23 +165,32 @@ static struct dentry *btrfs_get_parent(struct dentry *child)
        key.offset = (u64)-1;
 
        ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
+       if (ret < 0) {
+               /* Error */
+               btrfs_free_path(path);
+               return ERR_PTR(ret);
+       }
        leaf = path->nodes[0];
        slot = path->slots[0];
-       if (ret < 0 || slot == 0) {
-               btrfs_free_path(path);
-               goto out;
+       if (ret) {
+               /* btrfs_search_slot() returns the slot where we'd want to
+                  insert a backref for parent inode #0xFFFFFFFFFFFFFFFF.
+                  The _real_ backref, telling us what the parent inode
+                  _actually_ is, will be in the slot _before_ the one
+                  that btrfs_search_slot() returns. */
+               if (!slot) {
+                       /* Unless there is _no_ key in the tree before... */
+                       btrfs_free_path(path);
+                       return ERR_PTR(-EIO);
+               }
+               slot--;
        }
-       /* btrfs_search_slot() returns the slot where we'd want to insert
-          an INODE_REF_KEY for parent inode #0xFFFFFFFFFFFFFFFF. The _real_
-          one, telling us what the parent inode _actually_ is, will be in
-          the slot _before_ the one that btrfs_search_slot() returns. */
-       slot--;
 
        btrfs_item_key_to_cpu(leaf, &key, slot);
        btrfs_free_path(path);
 
        if (key.objectid != dir->i_ino || key.type != BTRFS_INODE_REF_KEY)
-               goto out;
+               return ERR_PTR(-EINVAL);
 
        objectid = key.offset;
 
@@ -201,10 +210,6 @@ static struct dentry *btrfs_get_parent(struct dentry *child)
                parent = ERR_PTR(-ENOMEM);
 
        return parent;
-
-out:
-       btrfs_free_path(path);
-       return ERR_PTR(-EINVAL);
 }
 
 const struct export_operations btrfs_export_ops = {