ext4: fix quota inconsistency during orphan cleanup for read-only mounts

Quota does not get enabled for read-only mounts if filesystem
has quota feature, so that quotas cannot updated during orphan
cleanup, which will lead to quota inconsistency.

This patch turn on quotas during orphan cleanup for this case,
make sure quotas can be updated correctly.
Reported-by: NJan Kara <jack@suse.cz>
Signed-off-by: Nzhangyi (F) <yi.zhang@huawei.com>
Signed-off-by: NTheodore Ts'o <tytso@mit.edu>
Reviewed-by: NJan Kara <jack@suse.cz>
Cc: stable@vger.kernel.org # 3.18+

fs/ext4/super.c

@@ -2404,6 +2404,7 @@ static void ext4_orphan_cleanup(struct super_block *sb,
 	unsigned int s_flags = sb->s_flags;
 	int ret, nr_orphans = 0, nr_truncates = 0;
 #ifdef CONFIG_QUOTA
+	int quota_update = 0;
 	int i;
 #endif
 	if (!es->s_last_orphan) {
@@ -2442,14 +2443,32 @@ 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 journaled quotas so that they are updated correctly */
+
+	/*
+	 * Turn on quotas which were not enabled for read-only mounts if
+	 * filesystem has quota feature, so that they are updated correctly.
+	 */
+	if (ext4_has_feature_quota(sb) && (s_flags & MS_RDONLY)) {
+		int ret = ext4_enable_quotas(sb);
+
+		if (!ret)
+			quota_update = 1;
+		else
+			ext4_msg(sb, KERN_ERR,
+				"Cannot turn on quotas: error %d", ret);
+	}
+
+	/* Turn on journaled quotas used for old sytle */
 	for (i = 0; i < EXT4_MAXQUOTAS; i++) {
 		if (EXT4_SB(sb)->s_qf_names[i]) {
 			int ret = ext4_quota_on_mount(sb, i);
-			if (ret < 0)
+
+			if (!ret)
+				quota_update = 1;
+			else
 				ext4_msg(sb, KERN_ERR,
 					"Cannot turn on journaled "
-					"quota: error %d", ret);
+					"quota: type %d: error %d", i, ret);
 		}
 	}
 #endif
@@ -2510,10 +2529,12 @@ 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 off journaled quotas if they were enabled for orphan cleanup */
-	for (i = 0; i < EXT4_MAXQUOTAS; i++) {
-		if (EXT4_SB(sb)->s_qf_names[i] && sb_dqopt(sb)->files[i])
-			dquot_quota_off(sb, i);
+	/* Turn off quotas if they were enabled for orphan cleanup */
+	if (quota_update) {
+		for (i = 0; i < EXT4_MAXQUOTAS; i++) {
+			if (sb_dqopt(sb)->files[i])
+				dquot_quota_off(sb, i);
+		}
 	}
 #endif
 	sb->s_flags = s_flags; /* Restore MS_RDONLY status */
@@ -5512,6 +5533,9 @@ static int ext4_enable_quotas(struct super_block *sb)
 				DQUOT_USAGE_ENABLED |
 				(quota_mopt[type] ? DQUOT_LIMITS_ENABLED : 0));
 			if (err) {
+				for (type--; type >= 0; type--)
+					dquot_quota_off(sb, type);
+
 				ext4_warning(sb,
 					"Failed to enable quota tracking "
 					"(type=%d, err=%d). Please run "