ext4: fix incorrect quotaoff if the quota feature is enabled

Current ext4 quota should always "usage enabled" if the
quota feautre is enabled. But in ext4_orphan_cleanup(), it
turn quotas off directly (used for the older journaled
quota), so we cannot turn it on again via "quotaon" unless
umount and remount ext4.

Simple reproduce:

  mkfs.ext4 -O project,quota /dev/vdb1
  mount -o prjquota /dev/vdb1 /mnt
  chattr -p 123 /mnt
  chattr +P /mnt
  touch /mnt/aa /mnt/bb
  exec 100<>/mnt/aa
  rm -f /mnt/aa
  sync
  echo c > /proc/sysrq-trigger

  #reboot and mount
  mount -o prjquota /dev/vdb1 /mnt
  #query status
  quotaon -Ppv /dev/vdb1
  #output
  quotaon: Cannot find mountpoint for device /dev/vdb1
  quotaon: No correct mountpoint specified.

This patch add check for journaled quotas to avoid incorrect
quotaoff when ext4 has quota feautre.

Signed-off-by: zhangyi (F) <yi.zhang@huawei.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: stable@vger.kernel.org # 3.18

fs/ext4/super.c

@@ -2442,7 +2442,7 @@ static void ext4_orphan_cleanup(struct super_block *sb,
 #ifdef CONFIG_QUOTA
 	/* Needed for iput() to work correctly and not trash data */
 	sb->s_flags |= MS_ACTIVE;
-	/* Turn on quotas so that they are updated correctly */
+	/* Turn on journaled quotas so that they are updated correctly */
 	for (i = 0; i < EXT4_MAXQUOTAS; i++) {
 		if (EXT4_SB(sb)->s_qf_names[i]) {
 			int ret = ext4_quota_on_mount(sb, i);
@@ -2510,9 +2510,9 @@ static void ext4_orphan_cleanup(struct super_block *sb,
 		ext4_msg(sb, KERN_INFO, "%d truncate%s cleaned up",
 		       PLURAL(nr_truncates));
 #ifdef CONFIG_QUOTA
-	/* Turn quotas off */
+	/* Turn off journaled quotas if they were enabled for orphan cleanup */
 	for (i = 0; i < EXT4_MAXQUOTAS; i++) {
-		if (sb_dqopt(sb)->files[i])
+		if (EXT4_SB(sb)->s_qf_names[i] && sb_dqopt(sb)->files[i])
 			dquot_quota_off(sb, i);
 	}
 #endif