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>

2 files changed, 97 insertions, 24 deletions

diff --git a/include/linux/quota.h b/include/linux/quota.h
index 9ea468363f9f..93717abcd35b 100644
--- a/include/linux/quota.h
+++ b/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 */
diff --git a/include/linux/quotaops.h b/include/linux/quotaops.h
index ffd97071cd1e..3b3346fa657c 100644
--- a/include/linux/quotaops.h
+++ b/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.
  */