trivial writeback fixes

Hi Linus,

Please pull 3 trivial writeback fixes.

Thanks,
Fengguang
---

The following changes since commit fea7a08acb13524b47711625eebea40a0ede69a0:

Linux 3.6-rc3 (2012-08-22 13:29:06 -0700)

are available in the git repository at:

git://git.kernel.org/pub/scm/linux/kernel/git/wfg/linux.git writeback-for-next

for you to fetch changes up to 2f60d628ffd042e65e0b1d3431fb3e38d6f7c1be:

CPU hotplug, writeback: Don't call writeback_set_ratelimit() too often during hotplug (2012-09-28 20:27:49 +0800)

----------------------------------------------------------------
Namjae Jeon (1):
backing-dev: use kstrto* in preference to simple_strtoul

Srivatsa S. Bhat (1):
CPU hotplug, writeback: Don't call writeback_set_ratelimit() too often during hotplug

Wang Sheng-Hui (1):
writeback: correct comment for move_expired_inodes()

 fs/fs-writeback.c   |    2 +-
 mm/backing-dev.c    |   50 ++++++++++++++++++++++++++------------------------
 mm/page-writeback.c |   14 +++++++++++---
 3 files changed, 38 insertions(+), 28 deletions(-)

index be3efc4..fd255c0 100644
@@ -248,7 +248,7 @@ static bool inode_dirtied_after(struct inode *inode, unsigned long t)
 }
 
 /*
- * Move expired (dirtied after work->older_than_this) dirty inodes from
+ * Move expired (dirtied before work->older_than_this) dirty inodes from
  * @delaying_queue to @dispatch_queue.
  */
 static int move_expired_inodes(struct list_head *delaying_queue,

index 5ad5ce2..830893b 100644
@@ -1602,10 +1602,18 @@ void writeback_set_ratelimit(void)
 }
 
 static int __cpuinit
-ratelimit_handler(struct notifier_block *self, unsigned long u, void *v)
+ratelimit_handler(struct notifier_block *self, unsigned long action,
+		  void *hcpu)
 {
-	writeback_set_ratelimit();
-	return NOTIFY_DONE;
+
+	switch (action & ~CPU_TASKS_FROZEN) {
+	case CPU_ONLINE:
+	case CPU_DEAD:
+		writeback_set_ratelimit();
+		return NOTIFY_OK;
+	default:
+		return NOTIFY_DONE;
+	}
 }
 
 static struct notifier_block __cpuinitdata ratelimit_nb = {