[PATCH] fix races and leaks in vfs_quota_on() users

* new helper: vfs_quota_on_path(); equivalent of vfs_quota_on() sans the
  pathname resolution.
* callers of vfs_quota_on() that do their own pathname resolution and
  checks based on it are switched to vfs_quota_on_path(); that way we
  avoid the races.
* reiserfs leaked dentry/vfsmount references on several failure exits.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/ext3/super.c

@@ -2810,8 +2810,9 @@ static int ext3_quota_on(struct super_block *sb, int type, int format_id,
 		journal_unlock_updates(EXT3_SB(sb)->s_journal);
 	}
 
+	err = vfs_quota_on_path(sb, type, format_id, &nd.path);
 	path_put(&nd.path);
-	return vfs_quota_on(sb, type, format_id, path, remount);
+	return err;
 }
 
 /* Read data from quotafile - avoid pagecache and such because we cannot afford