quota: Allow to separately enable quota accounting and enforcing limits

Split DQUOT_USR_ENABLED (and DQUOT_GRP_ENABLED) into DQUOT_USR_USAGE_ENABLED
and DQUOT_USR_LIMITS_ENABLED. This way we are able to separately enable /
disable whether we should:
1) ignore quotas completely
2) just keep uptodate information about usage
3) actually enforce quota limits

This is going to be useful when quota is treated as filesystem metadata - we
then want to keep quota information uptodate all the time and just enable /
disable limits enforcement.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>

fs/quota.c

@@ -73,7 +73,7 @@ static int generic_quotactl_valid(struct super_block *sb, int type, int cmd, qid
 		case Q_SETQUOTA:
 		case Q_GETQUOTA:
 			/* This is just informative test so we are satisfied without a lock */
-			if (!sb_has_quota_enabled(sb, type))
+			if (!sb_has_quota_active(sb, type))
 				return -ESRCH;
 	}
 
@@ -175,7 +175,7 @@ static void quota_sync_sb(struct super_block *sb, int type)
 	for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
 		if (type != -1 && cnt != type)
 			continue;
-		if (!sb_has_quota_enabled(sb, cnt))
+		if (!sb_has_quota_active(sb, cnt))
 			continue;
 		mutex_lock_nested(&sb_dqopt(sb)->files[cnt]->i_mutex, I_MUTEX_QUOTA);
 		truncate_inode_pages(&sb_dqopt(sb)->files[cnt]->i_data, 0);
@@ -201,7 +201,7 @@ restart:
 		for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
 			if (type != -1 && type != cnt)
 				continue;
-			if (!sb_has_quota_enabled(sb, cnt))
+			if (!sb_has_quota_active(sb, cnt))
 				continue;
 			if (!info_dirty(&sb_dqopt(sb)->info[cnt]) &&
 			    list_empty(&sb_dqopt(sb)->info[cnt].dqi_dirty_list))
@@ -245,7 +245,7 @@ static int do_quotactl(struct super_block *sb, int type, int cmd, qid_t id, void
 			__u32 fmt;
 
 			down_read(&sb_dqopt(sb)->dqptr_sem);
-			if (!sb_has_quota_enabled(sb, type)) {
+			if (!sb_has_quota_active(sb, type)) {
 				up_read(&sb_dqopt(sb)->dqptr_sem);
 				return -ESRCH;
 			}

include/linux/quota.h

@@ -318,12 +318,34 @@ struct quota_format_type {
 	struct quota_format_type *qf_next;
 };
 
-#define DQUOT_USR_ENABLED	0x01		/* User diskquotas enabled */
-#define DQUOT_GRP_ENABLED	0x02		/* Group diskquotas enabled */
-#define DQUOT_USR_SUSPENDED	0x04		/* User diskquotas are off, but
+/* Quota state flags - they actually come in two flavors - for users and groups */
+enum {
+	_DQUOT_USAGE_ENABLED = 0,		/* Track disk usage for users */
+	_DQUOT_LIMITS_ENABLED,			/* Enforce quota limits for users */
+	_DQUOT_SUSPENDED,			/* User diskquotas are off, but
 						 * we have necessary info in
 						 * memory to turn them on */
-#define DQUOT_GRP_SUSPENDED	0x08		/* The same for group quotas */
+	_DQUOT_STATE_FLAGS
+};
+#define DQUOT_USAGE_ENABLED	(1 << _DQUOT_USAGE_ENABLED)
+#define DQUOT_LIMITS_ENABLED	(1 << _DQUOT_LIMITS_ENABLED)
+#define DQUOT_SUSPENDED		(1 << _DQUOT_SUSPENDED)
+#define DQUOT_STATE_FLAGS	(DQUOT_USAGE_ENABLED | DQUOT_LIMITS_ENABLED | \
+				 DQUOT_SUSPENDED)
+
+static inline unsigned int dquot_state_flag(unsigned int flags, int type)
+{
+	if (type == USRQUOTA)
+		return flags;
+	return flags << _DQUOT_STATE_FLAGS;
+}
+
+static inline unsigned int dquot_generic_flag(unsigned int flags, int type)
+{
+	if (type == USRQUOTA)
+		return flags;
+	return flags >> _DQUOT_STATE_FLAGS;
+}
 
 struct quota_info {
 	unsigned int flags;			/* Flags for diskquotas on this device */

include/linux/quotaops.h

@@ -40,11 +40,14 @@ int dquot_mark_dquot_dirty(struct dquot *dquot);
 
 int vfs_quota_on(struct super_block *sb, int type, int format_id,
  	char *path, int remount);
+int vfs_quota_enable(struct inode *inode, int type, int format_id,
+	unsigned int flags);
 int vfs_quota_on_path(struct super_block *sb, int type, int format_id,
  	struct path *path);
 int vfs_quota_on_mount(struct super_block *sb, char *qf_name,
  	int format_id, int type);
 int vfs_quota_off(struct super_block *sb, int type, int remount);
+int vfs_quota_disable(struct super_block *sb, int type, unsigned int flags);
 int vfs_quota_sync(struct super_block *sb, int type);
 int vfs_get_dqinfo(struct super_block *sb, int type, struct if_dqinfo *ii);
 int vfs_set_dqinfo(struct super_block *sb, int type, struct if_dqinfo *ii);
@@ -64,26 +67,22 @@ static inline struct mem_dqinfo *sb_dqinfo(struct super_block *sb, int type)
  * Functions for checking status of quota
  */
 
-static inline int sb_has_quota_enabled(struct super_block *sb, int type)
+static inline int sb_has_quota_usage_enabled(struct super_block *sb, int type)
 {
-	if (type == USRQUOTA)
-		return (sb_dqopt(sb)->flags & DQUOT_USR_ENABLED)
-			&& !(sb_dqopt(sb)->flags & DQUOT_USR_SUSPENDED);
-	return (sb_dqopt(sb)->flags & DQUOT_GRP_ENABLED)
-		&& !(sb_dqopt(sb)->flags & DQUOT_GROUP_SUSPENDED);
+	return sb_dqopt(sb)->flags &
+				dquot_state_flag(DQUOT_USAGE_ENABLED, type);
 }
 
-static inline int sb_any_quota_enabled(struct super_block *sb)
+static inline int sb_has_quota_limits_enabled(struct super_block *sb, int type)
 {
-	return sb_has_quota_enabled(sb, USRQUOTA) ||
-		sb_has_quota_enabled(sb, GRPQUOTA);
+	return sb_dqopt(sb)->flags &
+				dquot_state_flag(DQUOT_LIMITS_ENABLED, type);
 }
 
 static inline int sb_has_quota_suspended(struct super_block *sb, int type)
 {
-	if (type == USRQUOTA)
-		return sb_dqopt(sb)->flags & DQUOT_USR_SUSPENDED;
-	return sb_dqopt(sb)->flags & DQUOT_GRP_SUSPENDED;
+	return sb_dqopt(sb)->flags &
+				dquot_state_flag(DQUOT_SUSPENDED, type);
 }
 
 static inline int sb_any_quota_suspended(struct super_block *sb)
@@ -92,6 +91,34 @@ static inline int sb_any_quota_suspended(struct super_block *sb)
 		sb_has_quota_suspended(sb, GRPQUOTA);
 }
 
+/* Does kernel know about any quota information for given sb + type? */
+static inline int sb_has_quota_loaded(struct super_block *sb, int type)
+{
+	/* Currently if anything is on, then quota usage is on as well */
+	return sb_has_quota_usage_enabled(sb, type);
+}
+
+static inline int sb_any_quota_loaded(struct super_block *sb)
+{
+	return sb_has_quota_loaded(sb, USRQUOTA) ||
+		sb_has_quota_loaded(sb, GRPQUOTA);
+}
+
+static inline int sb_has_quota_active(struct super_block *sb, int type)
+{
+	return sb_has_quota_loaded(sb, type) &&
+	       !sb_has_quota_suspended(sb, type);
+}
+
+static inline int sb_any_quota_active(struct super_block *sb)
+{
+	return sb_has_quota_active(sb, USRQUOTA) ||
+	       sb_has_quota_active(sb, GRPQUOTA);
+}
+
+/* For backward compatibility until we remove all users */
+#define sb_any_quota_enabled(sb) sb_any_quota_active(sb)
+
 /*
  * Operations supported for diskquotas.
  */
@@ -106,7 +133,7 @@ extern struct quotactl_ops vfs_quotactl_ops;
 static inline void vfs_dq_init(struct inode *inode)
 {
 	BUG_ON(!inode->i_sb);
-	if (sb_any_quota_enabled(inode->i_sb) && !IS_NOQUOTA(inode))
+	if (sb_any_quota_active(inode->i_sb) && !IS_NOQUOTA(inode))
 		inode->i_sb->dq_op->initialize(inode, -1);
 }
 
@@ -114,7 +141,7 @@ static inline void vfs_dq_init(struct inode *inode)
  * a transaction (deadlocks possible otherwise) */
 static inline int vfs_dq_prealloc_space_nodirty(struct inode *inode, qsize_t nr)
 {
-	if (sb_any_quota_enabled(inode->i_sb)) {
+	if (sb_any_quota_active(inode->i_sb)) {
 		/* Used space is updated in alloc_space() */
 		if (inode->i_sb->dq_op->alloc_space(inode, nr, 1) == NO_QUOTA)
 			return 1;
@@ -134,7 +161,7 @@ static inline int vfs_dq_prealloc_space(struct inode *inode, qsize_t nr)
 
 static inline int vfs_dq_alloc_space_nodirty(struct inode *inode, qsize_t nr)
 {
-	if (sb_any_quota_enabled(inode->i_sb)) {
+	if (sb_any_quota_active(inode->i_sb)) {
 		/* Used space is updated in alloc_space() */
 		if (inode->i_sb->dq_op->alloc_space(inode, nr, 0) == NO_QUOTA)
 			return 1;
@@ -154,7 +181,7 @@ static inline int vfs_dq_alloc_space(struct inode *inode, qsize_t nr)
 
 static inline int vfs_dq_alloc_inode(struct inode *inode)
 {
-	if (sb_any_quota_enabled(inode->i_sb)) {
+	if (sb_any_quota_active(inode->i_sb)) {
 		vfs_dq_init(inode);
 		if (inode->i_sb->dq_op->alloc_inode(inode, 1) == NO_QUOTA)
 			return 1;
@@ -164,7 +191,7 @@ static inline int vfs_dq_alloc_inode(struct inode *inode)
 
 static inline void vfs_dq_free_space_nodirty(struct inode *inode, qsize_t nr)
 {
-	if (sb_any_quota_enabled(inode->i_sb))
+	if (sb_any_quota_active(inode->i_sb))
 		inode->i_sb->dq_op->free_space(inode, nr);
 	else
 		inode_sub_bytes(inode, nr);
@@ -178,7 +205,7 @@ static inline void vfs_dq_free_space(struct inode *inode, qsize_t nr)
 
 static inline void vfs_dq_free_inode(struct inode *inode)
 {
-	if (sb_any_quota_enabled(inode->i_sb))
+	if (sb_any_quota_active(inode->i_sb))
 		inode->i_sb->dq_op->free_inode(inode, 1);
 }
 
@@ -199,12 +226,12 @@ static inline int vfs_dq_off(struct super_block *sb, int remount)
 
 #else
 
-static inline int sb_has_quota_enabled(struct super_block *sb, int type)
+static inline int sb_has_quota_usage_enabled(struct super_block *sb, int type)
 {
 	return 0;
 }
 
-static inline int sb_any_quota_enabled(struct super_block *sb)
+static inline int sb_has_quota_limits_enabled(struct super_block *sb, int type)
 {
 	return 0;
 }
@@ -219,6 +246,30 @@ static inline int sb_any_quota_suspended(struct super_block *sb)
 	return 0;
 }
 
+/* Does kernel know about any quota information for given sb + type? */
+static inline int sb_has_quota_loaded(struct super_block *sb, int type)
+{
+	return 0;
+}
+
+static inline int sb_any_quota_loaded(struct super_block *sb)
+{
+	return 0;
+}
+
+static inline int sb_has_quota_active(struct super_block *sb, int type)
+{
+	return 0;
+}
+
+static inline int sb_any_quota_active(struct super_block *sb)
+{
+	return 0;
+}
+
+/* For backward compatibility until we remove all users */
+#define sb_any_quota_enabled(sb) sb_any_quota_active(sb)
+
 /*
  * NO-OP when quota not configured.
  */