btrfs: don't mess with i_nlink of unlocked inode in rename()

old_inode is not locked; it's not safe to play with its link
count.  Instead of bumping it and calling btrfs_unlink_inode(),
add a variant of the latter that does not do btrfs_drop_nlink()/
btrfs_update_inode(), call it instead of btrfs_inc_nlink()/
btrfs_unlink_inode() and do btrfs_update_inode() ourselves.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 25 insertions, 11 deletions

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 04e9fffee8c..4822b313278 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -2664,10 +2664,10 @@ failed:
  * recovery code.  It remove a link in a directory with a given name, and
  * also drops the back refs in the inode to the directory
  */
-int btrfs_unlink_inode(struct btrfs_trans_handle *trans,
-                       struct btrfs_root *root,
-                       struct inode *dir, struct inode *inode,
-                       const char *name, int name_len)
+static int __btrfs_unlink_inode(struct btrfs_trans_handle *trans,
+                                struct btrfs_root *root,
+                                struct inode *dir, struct inode *inode,
+                                const char *name, int name_len)
 {
         struct btrfs_path *path;
         int ret = 0;
@@ -2739,12 +2739,25 @@ err:
         btrfs_i_size_write(dir, dir->i_size - name_len * 2);
         inode->i_ctime = dir->i_mtime = dir->i_ctime = CURRENT_TIME;
         btrfs_update_inode(trans, root, dir);
-        btrfs_drop_nlink(inode);
-        ret = btrfs_update_inode(trans, root, inode);
 out:
         return ret;
 }
 
+int btrfs_unlink_inode(struct btrfs_trans_handle *trans,
+                       struct btrfs_root *root,
+                       struct inode *dir, struct inode *inode,
+                       const char *name, int name_len)
+{
+        int ret;
+        ret = __btrfs_unlink_inode(trans, root, dir, inode, name, name_len);
+        if (!ret) {
+                btrfs_drop_nlink(inode);
+                ret = btrfs_update_inode(trans, root, inode);
+        }
+        return ret;
+}
+                
+
 /* helper to check if there is any shared block in the path */
 static int check_path_shared(struct btrfs_root *root,
                              struct btrfs_path *path)
@@ -6999,11 +7012,12 @@ static int btrfs_rename(struct inode *old_dir, struct dentry *old_dentry,
                                         old_dentry->d_name.name,
                                         old_dentry->d_name.len);
         } else {
-                btrfs_inc_nlink(old_dentry->d_inode);
-                ret = btrfs_unlink_inode(trans, root, old_dir,
-                                         old_dentry->d_inode,
-                                         old_dentry->d_name.name,
-                                         old_dentry->d_name.len);
+                ret = __btrfs_unlink_inode(trans, root, old_dir,
+                                        old_dentry->d_inode,
+                                        old_dentry->d_name.name,
+                                        old_dentry->d_name.len);
+                if (!ret)
+                        ret = btrfs_update_inode(trans, root, old_inode);
         }
         BUG_ON(ret);