vfs: prefer ->dentry->d_sb to ->mnt->mnt_sb

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

fs/reiserfs/super.c

@@ -2058,7 +2058,7 @@ static int reiserfs_quota_on(struct super_block *sb, int type, int format_id,
 		return -EINVAL;
 
 	/* Quotafile not on the same filesystem? */
-	if (path->mnt->mnt_sb != sb) {
+	if (path->dentry->d_sb != sb) {
 		err = -EXDEV;
 		goto out;
 	}