[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>
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index b5479b1..1e69f29 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -3352,8 +3352,9 @@
 		jbd2_journal_unlock_updates(EXT4_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