quota: Wire up ->quota_{enable,disable} callbacks into Q_QUOTA{ON,OFF}

Make Q_QUOTAON / Q_QUOTAOFF quotactl call ->quota_enable /
->quota_disable callback when provided. To match current behavior of
ocfs2 & ext4 we make these quotactls turn on / off quota enforcement for
appropriate quota type.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>

fs/quota/quota.c

@@ -66,18 +66,43 @@ static int quota_sync_all(int type)
 	return ret;
 }
 
+unsigned int qtype_enforce_flag(int type)
+{
+	switch (type) {
+	case USRQUOTA:
+		return FS_QUOTA_UDQ_ENFD;
+	case GRPQUOTA:
+		return FS_QUOTA_GDQ_ENFD;
+	case PRJQUOTA:
+		return FS_QUOTA_PDQ_ENFD;
+	}
+	return 0;
+}
+
 static int quota_quotaon(struct super_block *sb, int type, int cmd, qid_t id,
 		         struct path *path)
 {
-	if (!sb->s_qcop->quota_on && !sb->s_qcop->quota_on_meta)
+	if (!sb->s_qcop->quota_on && !sb->s_qcop->quota_on_meta &&
+	    !sb->s_qcop->quota_enable)
 		return -ENOSYS;
 	if (sb->s_qcop->quota_on_meta)
 		return sb->s_qcop->quota_on_meta(sb, type, id);
+	if (sb->s_qcop->quota_enable)
+		return sb->s_qcop->quota_enable(sb, qtype_enforce_flag(type));
 	if (IS_ERR(path))
 		return PTR_ERR(path);
 	return sb->s_qcop->quota_on(sb, type, id, path);
 }
 
+static int quota_quotaoff(struct super_block *sb, int type)
+{
+	if (!sb->s_qcop->quota_off && !sb->s_qcop->quota_disable)
+		return -ENOSYS;
+	if (sb->s_qcop->quota_disable)
+		return sb->s_qcop->quota_disable(sb, qtype_enforce_flag(type));
+	return sb->s_qcop->quota_off(sb, type);
+}
+
 static int quota_getfmt(struct super_block *sb, int type, void __user *addr)
 {
 	__u32 fmt;
@@ -440,9 +465,7 @@ static int do_quotactl(struct super_block *sb, int type, int cmd, qid_t id,
 	case Q_QUOTAON:
 		return quota_quotaon(sb, type, cmd, id, path);
 	case Q_QUOTAOFF:
-		if (!sb->s_qcop->quota_off)
-			return -ENOSYS;
-		return sb->s_qcop->quota_off(sb, type);
+		return quota_quotaoff(sb, type);
 	case Q_GETFMT:
 		return quota_getfmt(sb, type, addr);
 	case Q_GETINFO:

include/linux/quotaops.h

@@ -386,4 +386,6 @@ static inline void dquot_release_reservation_block(struct inode *inode,
 	__dquot_free_space(inode, nr << inode->i_blkbits, DQUOT_SPACE_RESERVE);
 }
 
+unsigned int qtype_enforce_flag(int type);
+
 #endif /* _LINUX_QUOTAOPS_ */