From 1a85856febf70ea1e64afc818fd0d12106d6b92a Mon Sep 17 00:00:00 2001
From: Jens Axboe <jens.axboe@oracle.com>
Date: Fri, 21 May 2010 20:00:35 +0200
Subject: [PATCH] --- yaml --- r: 196870 b: refs/heads/master c:
 6423104b6a1e6f0c18be60e8c33f02d263331d5e h: refs/heads/master v: v3

---
 [refs]                            |  2 +-
 trunk/include/linux/backing-dev.h |  1 +
 trunk/mm/backing-dev.c            | 15 ++++++++++-----
 trunk/mm/page-writeback.c         |  1 +
 4 files changed, 13 insertions(+), 6 deletions(-)

diff --git a/[refs] b/[refs]
index 2bd6dc89cd1d..b8c25484de09 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: f9eadbbd424c083b8005c7b738f644611b9ef489
+refs/heads/master: 6423104b6a1e6f0c18be60e8c33f02d263331d5e
diff --git a/trunk/include/linux/backing-dev.h b/trunk/include/linux/backing-dev.h
index ff8bac63213f..e6e0cb5437e6 100644
--- a/trunk/include/linux/backing-dev.h
+++ b/trunk/include/linux/backing-dev.h
@@ -109,6 +109,7 @@ void bdi_start_writeback(struct backing_dev_info *bdi, struct super_block *sb,
 				long nr_pages, int sb_locked);
 int bdi_writeback_task(struct bdi_writeback *wb);
 int bdi_has_dirty_io(struct backing_dev_info *bdi);
+void bdi_arm_supers_timer(void);
 
 extern spinlock_t bdi_lock;
 extern struct list_head bdi_list;
diff --git a/trunk/mm/backing-dev.c b/trunk/mm/backing-dev.c
index 707d0dc6da0f..660a87a22511 100644
--- a/trunk/mm/backing-dev.c
+++ b/trunk/mm/backing-dev.c
@@ -48,7 +48,6 @@ static struct timer_list sync_supers_timer;
 
 static int bdi_sync_supers(void *);
 static void sync_supers_timer_fn(unsigned long);
-static void arm_supers_timer(void);
 
 static void bdi_add_default_flusher_task(struct backing_dev_info *bdi);
 
@@ -252,7 +251,7 @@ static int __init default_bdi_init(void)
 
 	init_timer(&sync_supers_timer);
 	setup_timer(&sync_supers_timer, sync_supers_timer_fn, 0);
-	arm_supers_timer();
+	bdi_arm_supers_timer();
 
 	err = bdi_init(&default_backing_dev_info);
 	if (!err)
@@ -374,10 +373,13 @@ static int bdi_sync_supers(void *unused)
 	return 0;
 }
 
-static void arm_supers_timer(void)
+void bdi_arm_supers_timer(void)
 {
 	unsigned long next;
 
+	if (!dirty_writeback_interval)
+		return;
+
 	next = msecs_to_jiffies(dirty_writeback_interval * 10) + jiffies;
 	mod_timer(&sync_supers_timer, round_jiffies_up(next));
 }
@@ -385,7 +387,7 @@ static void arm_supers_timer(void)
 static void sync_supers_timer_fn(unsigned long unused)
 {
 	wake_up_process(sync_supers_tsk);
-	arm_supers_timer();
+	bdi_arm_supers_timer();
 }
 
 static int bdi_forker_task(void *ptr)
@@ -428,7 +430,10 @@ static int bdi_forker_task(void *ptr)
 
 			spin_unlock_bh(&bdi_lock);
 			wait = msecs_to_jiffies(dirty_writeback_interval * 10);
-			schedule_timeout(wait);
+			if (wait)
+				schedule_timeout(wait);
+			else
+				schedule();
 			try_to_freeze();
 			continue;
 		}
diff --git a/trunk/mm/page-writeback.c b/trunk/mm/page-writeback.c
index 53b2fcf2d283..0d7bbe859550 100644
--- a/trunk/mm/page-writeback.c
+++ b/trunk/mm/page-writeback.c
@@ -690,6 +690,7 @@ int dirty_writeback_centisecs_handler(ctl_table *table, int write,
 	void __user *buffer, size_t *length, loff_t *ppos)
 {
 	proc_dointvec(table, write, buffer, length, ppos);
+	bdi_arm_supers_timer();
 	return 0;
 }