[PATCH 04/19] quota: Convert dq_state_lock to per-sb dq_state_lock

[Dmitry Monakhov <dmonakhov@openvz.org>]

From: Dmitry Monakhov <dmonakhov@gmail.com>

Currently dq_state_lock is global, which is bad for scalability.
In fact different super_blocks have no shared quota data.
So we may simply convert the global lock to per-sb locks.

Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
---
 fs/quota/dquot.c      |   30 +++++++++++++++---------------
 include/linux/quota.h |    1 +
 2 files changed, 16 insertions(+), 15 deletions(-)

diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c
index b87435d..5dfbf9c 100644
--- a/fs/quota/dquot.c
+++ b/fs/quota/dquot.c
@@ -128,7 +128,6 @@
  */
 
 static __cacheline_aligned_in_smp DEFINE_SPINLOCK(dq_list_lock);
-static __cacheline_aligned_in_smp DEFINE_SPINLOCK(dq_state_lock);
 __cacheline_aligned_in_smp DEFINE_SPINLOCK(dq_data_lock);
 EXPORT_SYMBOL(dq_data_lock);
 
@@ -821,13 +820,13 @@ struct dquot *dqget(struct super_block *sb, unsigned int id, int type)
 		return NULL;
 we_slept:
 	spin_lock(&dq_list_lock);
-	spin_lock(&dq_state_lock);
+	spin_lock(&dqopts(sb)->dq_state_lock);
 	if (!sb_has_quota_active(sb, type)) {
-		spin_unlock(&dq_state_lock);
+		spin_unlock(&dqopts(sb)->dq_state_lock);
 		spin_unlock(&dq_list_lock);
 		goto out;
 	}
-	spin_unlock(&dq_state_lock);
+	spin_unlock(&dqopts(sb)->dq_state_lock);
 
 	dquot = find_dquot(hashent, sb, id, type);
 	if (!dquot) {
@@ -1903,6 +1902,7 @@ static int alloc_quota_info(struct quota_ctl_info *dqctl) {
 		return err;
 
 	mutex_init(&dqopt->dqio_mutex);
+	spin_lock_init(&dqopt->dq_state_lock);
 	dqctl->dq_opt = dqopt;
 	return 0;
 }
@@ -1952,24 +1952,24 @@ int dquot_disable(struct super_block *sb, int type, unsigned int flags)
 			continue;
 
 		if (flags & DQUOT_SUSPENDED) {
-			spin_lock(&dq_state_lock);
+			spin_lock(&dqopt->dq_state_lock);
 			qctl->flags |=
 				dquot_state_flag(DQUOT_SUSPENDED, cnt);
-			spin_unlock(&dq_state_lock);
+			spin_unlock(&dqopt->dq_state_lock);
 		} else {
-			spin_lock(&dq_state_lock);
+			spin_lock(&dqopt->dq_state_lock);
 			qctl->flags &= ~dquot_state_flag(flags, cnt);
 			/* Turning off suspended quotas? */
 			if (!sb_has_quota_loaded(sb, cnt) &&
 			    sb_has_quota_suspended(sb, cnt)) {
 				qctl->flags &=	~dquot_state_flag(
 							DQUOT_SUSPENDED, cnt);
-				spin_unlock(&dq_state_lock);
+				spin_unlock(&dqopt->dq_state_lock);
 				iput(dqopt->files[cnt]);
 				dqopt->files[cnt] = NULL;
 				continue;
 			}
-			spin_unlock(&dq_state_lock);
+			spin_unlock(&dqopt->dq_state_lock);
 		}
 
 		/* We still have to keep quota loaded? */
@@ -2152,9 +2152,9 @@ static int vfs_load_quota_inode(struct inode *inode, int type, int format_id,
 		goto out_file_init;
 	}
 	mutex_unlock(&dqopt->dqio_mutex);
-	spin_lock(&dq_state_lock);
+	spin_lock(&dqopt->dq_state_lock);
 	dqctl(sb)->flags |= dquot_state_flag(flags, type);
-	spin_unlock(&dq_state_lock);
+	spin_unlock(&dqopt->dq_state_lock);
 
 	add_dquot_ref(sb, type);
 	mutex_unlock(&dqctl(sb)->dqonoff_mutex);
@@ -2199,12 +2199,12 @@ int dquot_resume(struct super_block *sb, int type)
 		}
 		inode = qctl->dq_opt->files[cnt];
 		qctl->dq_opt->files[cnt] = NULL;
-		spin_lock(&dq_state_lock);
+		spin_lock(&dqopts(sb)->dq_state_lock);
 		flags = qctl->flags & dquot_state_flag(DQUOT_USAGE_ENABLED |
 							DQUOT_LIMITS_ENABLED,
 							cnt);
 		qctl->flags &= ~dquot_state_flag(DQUOT_STATE_FLAGS, cnt);
-		spin_unlock(&dq_state_lock);
+		spin_unlock(&dqopts(sb)->dq_state_lock);
 		mutex_unlock(&qctl->dqonoff_mutex);
 
 		flags = dquot_generic_flag(flags, cnt);
@@ -2283,9 +2283,9 @@ int dquot_enable(struct inode *inode, int type, int format_id,
 			ret = -EBUSY;
 			goto out_lock;
 		}
-		spin_lock(&dq_state_lock);
+		spin_lock(&dqopts(sb)->dq_state_lock);
 		qctl->flags |= dquot_state_flag(flags, type);
-		spin_unlock(&dq_state_lock);
+		spin_unlock(&dqopts(sb)->dq_state_lock);
 out_lock:
 		mutex_unlock(&qctl->dqonoff_mutex);
 		return ret;
diff --git a/include/linux/quota.h b/include/linux/quota.h
index 6803834..3fca71f 100644
--- a/include/linux/quota.h
+++ b/include/linux/quota.h
@@ -404,6 +404,7 @@ struct quota_ctl_info {
 struct quota_info {
 	struct mutex dqio_mutex;		/* lock device while I/O in progress */
 	struct mem_dqinfo info[MAXQUOTAS];	/* Information for each quota type */
+	spinlock_t dq_state_lock;	/* serialize quota state changes*/
 	struct inode *files[MAXQUOTAS];	/* inodes of quotafiles */
 	const struct quota_format_ops *fmt_ops[MAXQUOTAS];	/* Operations for each type */
 };
-- 
1.6.5.2