writeback: do not lose wake-ups in bdi threads
Currently, bdi threads ('bdi_writeback_thread()') can lose wake-ups. For
example, if 'bdi_queue_work()' is executed after the bdi thread have had
finished 'wb_do_writeback()' but before it called
'schedule_timeout_interruptible()'.
To fix this issue, we have to check whether we have works to process after we
have changed the task state to 'TASK_INTERRUPTIBLE'.
This patch also clean-ups handling of the cases when 'dirty_writeback_interval'
is zero or non-zero.
Additionally, this patch also removes unneeded 'list_empty_careful()' call.
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 002be0f..05444ea 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -848,16 +848,17 @@
break;
}
+ set_current_state(TASK_INTERRUPTIBLE);
+ if (!list_empty(&bdi->work_list)) {
+ __set_current_state(TASK_RUNNING);
+ continue;
+ }
+
if (dirty_writeback_interval) {
wait_jiffies = msecs_to_jiffies(dirty_writeback_interval * 10);
- schedule_timeout_interruptible(wait_jiffies);
- } else {
- set_current_state(TASK_INTERRUPTIBLE);
- if (list_empty_careful(&wb->bdi->work_list) &&
- !kthread_should_stop())
- schedule();
- __set_current_state(TASK_RUNNING);
- }
+ schedule_timeout(wait_jiffies);
+ } else
+ schedule();
try_to_freeze();
}