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>

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 04e9fff..4822b31 100644 (file)
--- 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);