From: Artem Bityutskiy <Artem.Bityutskiy@xxxxxxxxx>
The bdi threads ('bdi_writeback_thread()') can lose wake-ups if,
for example, 'bdi_queue_work()' is executed while after the bdi
thread finished 'wb_do_writeback()' but before it has called
'schedule_timeout_interruptible()'.
To fix this issue, we have to check whether we have works to
process after we change the task state to 'TASK_INTERRUPTIBLE'.
Also, 'bdi_writeback_thread()' inconsistently handles the cases
when 'dirty_writeback_interval' is zero and non-zero. But there is
no fundamental difference between these cases, so they have to be
handled the same way, which this patch also does.
This patch also removes strange 'list_empty_careful()' call.
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@xxxxxxxxx>
---
fs/fs-writeback.c | 17 +++++++++--------
1 files changed, 9 insertions(+), 8 deletions(-)
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 3fc5194..f045450 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -848,17 +848,18 @@ int bdi_writeback_thread(void *data)
break;
}
- 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_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(wait_jiffies);
+ } else
+ schedule();
+
try_to_freeze();
}
--
1.7.1.1
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