[PATCH] quota: manage reserved space even when quota is not active

[Dmitry Monakhov <dmonakhov@openvz.org>]

Hi, Jan.
I've prepared additional patch for quota reserved space management.
Initially I've overlooked case when quota is not active, but in fact
it seems reasonable to generalize reservation to that case as we do
for i_block/i_bytes reservation.
Possibly it should be folded in to c35fc5af93955aa22efc6568e5ae5b2cadbc086f

CHANGE_LOG:
quota: manage reserved space even when quota is not active
Since we implemented generic reserved space management interface,
then it is possible to account reserved space even quota when quota
is not active (similar to i_blocks/i_bytes).

Without this patch following testcase result in massive comlain from
WARN_ON in dquot_claim_space()

test_case:
mount /dev/sdb /mnt -oquota
dd if=/dev/zero of=/mnt/test bs=1M count=1
# fs_reserved_spave == 1Mb
# quota_reserved_space == 0 because quota is off here
quotaon /mnt
dd if=/dev/zero of=/mnt/test seek=1 bs=1M count=1
# fs_reserved_spave == 2Mb
# quota_reserved_space == 1Mb
sync  # ->dquot_claim_space() -> WARN_ON

Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
---
 fs/quota/dquot.c         |    9 ++++-----
 include/linux/quotaops.h |   12 ++++++++++--
 2 files changed, 14 insertions(+), 7 deletions(-)

diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c
index dea86ab..de7e7de 100644
--- a/fs/quota/dquot.c
+++ b/fs/quota/dquot.c
@@ -1351,15 +1351,14 @@ static qsize_t *inode_reserved_space(struct inode * inode)
 	return inode->i_sb->dq_op->get_reserved_space(inode);
 }
 
-static void inode_add_rsv_space(struct inode *inode, qsize_t number)
+void inode_add_rsv_space(struct inode *inode, qsize_t number)
 {
 	spin_lock(&inode->i_lock);
 	*inode_reserved_space(inode) += number;
 	spin_unlock(&inode->i_lock);
 }
 
-
-static void inode_claim_rsv_space(struct inode *inode, qsize_t number)
+void inode_claim_rsv_space(struct inode *inode, qsize_t number)
 {
 	spin_lock(&inode->i_lock);
 	*inode_reserved_space(inode) -= number;
@@ -1367,14 +1366,14 @@ static void inode_claim_rsv_space(struct inode *inode, qsize_t number)
 	spin_unlock(&inode->i_lock);
 }
 
-static void inode_sub_rsv_space(struct inode *inode, qsize_t number)
+void inode_sub_rsv_space(struct inode *inode, qsize_t number)
 {
 	spin_lock(&inode->i_lock);
 	*inode_reserved_space(inode) -= number;
 	spin_unlock(&inode->i_lock);
 }
 
-static qsize_t inode_get_rsv_space(struct inode *inode)
+qsize_t inode_get_rsv_space(struct inode *inode)
 {
 	qsize_t ret;
 	spin_lock(&inode->i_lock);
diff --git a/include/linux/quotaops.h b/include/linux/quotaops.h
index 3ebb231..ae7ef25 100644
--- a/include/linux/quotaops.h
+++ b/include/linux/quotaops.h
@@ -26,6 +26,11 @@ static inline void writeout_quota_sb(struct super_block *sb, int type)
 		sb->s_qcop->quota_sync(sb, type);
 }
 
+void inode_add_rsv_space(struct inode *inode, qsize_t number);
+void inode_claim_rsv_space(struct inode *inode, qsize_t number);
+void inode_sub_rsv_space(struct inode *inode, qsize_t number);
+qsize_t inode_get_rsv_space(struct inode *inode);
+
 int dquot_initialize(struct inode *inode, int type);
 int dquot_drop(struct inode *inode);
 struct dquot *dqget(struct super_block *sb, unsigned int id, int type);
@@ -42,7 +47,6 @@ int dquot_alloc_inode(const struct inode *inode, qsize_t number);
 int dquot_reserve_space(struct inode *inode, qsize_t number, int prealloc);
 int dquot_claim_space(struct inode *inode, qsize_t number);
 void dquot_release_reserved_space(struct inode *inode, qsize_t number);
-qsize_t dquot_get_reserved_space(struct inode *inode);
 
 int dquot_free_space(struct inode *inode, qsize_t number);
 int dquot_free_inode(const struct inode *inode, qsize_t number);
@@ -199,6 +203,8 @@ static inline int vfs_dq_reserve_space(struct inode *inode, qsize_t nr)
 		if (inode->i_sb->dq_op->reserve_space(inode, nr, 0) == NO_QUOTA)
 			return 1;
 	}
+	else
+		inode_add_rsv_space(inode, nr);
 	return 0;
 }
 
@@ -221,7 +227,7 @@ static inline int vfs_dq_claim_space(struct inode *inode, qsize_t nr)
 		if (inode->i_sb->dq_op->claim_space(inode, nr) == NO_QUOTA)
 			return 1;
 	} else
-		inode_add_bytes(inode, nr);
+		inode_claim_rsv_space(inode, nr);
 
 	mark_inode_dirty(inode);
 	return 0;
@@ -235,6 +241,8 @@ void vfs_dq_release_reservation_space(struct inode *inode, qsize_t nr)
 {
 	if (sb_any_quota_active(inode->i_sb))
 		inode->i_sb->dq_op->release_rsv(inode, nr);
+	else
+		inode_sub_rsv_space(inode, nr);
 }
 
 static inline void vfs_dq_free_space_nodirty(struct inode *inode, qsize_t nr)
-- 
1.6.0.4