writeback: fixups for !dirty_writeback_centisecs
Commit 69b62d01 fixed up most of the places where we would enter
busy schedule() spins when disabling the periodic background
writeback. This fixes up the sb timer so that it doesn't get
hammered on with the delay disabled, and ensures that it gets
rearmed if needed when /proc/sys/vm/dirty_writeback_centisecs
gets modified.
bdi_forker_task() also needs to check for !dirty_writeback_centisecs
and use schedule() appropriately, fix that up too.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index 707d0dc6..660a87a 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -48,7 +48,6 @@
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 @@
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 @@
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 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 @@
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;
}