On 6/6/22 4:39 PM, Xiao Ni wrote:
On Mon, Jun 6, 2022 at 11:08 AM Guoqing Jiang <guoqing.jiang@xxxxxxxxx> wrote:
+ }
Maybe instead of the ugly boolean argument we could pull
md_unregister_thread() into all the callers and explicitly unlock in the
single call site that needs it?
Sounds good, let me revert previous commit then pull it.
Hi all
Now md_reap_sync_thread is called by __md_stop_writes, action_store
and md_check_recovery.
If we move md_unregister_thread out of md_reap_sync_thread and unlock
reconfig_mutex before
calling md_unregister_thread, it means we break the atomic action for
these three functions mentioned
above.
No, only action_store need to be changed, other callers keep the original
behavior.
Not sure if it can introduce other problems, especially for the
change of md_check_recovery.
How about suspend I/O when changing the sync action? It should not
hurt the performance, because
it only interrupts the sync action and flush the in memory stripes.
For this way, it needs to revert
7e6ba434cc60 (md: don't unregister sync_thread with reconfig_mutex
held) and changes like this:
diff --git a/drivers/md/md.c b/drivers/md/md.c
index ce9d2845d3ac..af28cdeaf7e1 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -4827,12 +4827,14 @@ action_store(struct mddev *mddev, const char
*page, size_t len)
clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery) &&
mddev_lock(mddev) == 0) {
+ mddev_suspend(mddev);
if (work_pending(&mddev->del_work))
flush_workqueue(md_misc_wq);
if (mddev->sync_thread) {
set_bit(MD_RECOVERY_INTR, &mddev->recovery);
md_reap_sync_thread(mddev);
}
+ mddev_resume(mddev);
mddev_unlock(mddev);
}
} else if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
The action actually means sync action which are for internal IO instead
of external IO, I suppose the semantic is different with above change.
And there are lots of sync/locking actions in suspend path, I am not
sure it will cause other locking issues, you may need to investigate it.
Thanks,
Guoqing
