Hi,
在 2024/02/18 13:56, Xiao Ni 写道:
On Thu, Feb 1, 2024 at 5:30 PM Yu Kuai <yukuai1@xxxxxxxxxxxxxxx> wrote:
From: Yu Kuai <yukuai3@xxxxxxxxxx>
stop_sync_thread() will interrupt md_do_sync(), and md_do_sync() must
set MD_RECOVERY_DONE, so that follow up md_check_recovery() will
unregister sync_thread, clear MD_RECOVERY_RUNNING and wake up
stop_sync_thread().
If MD_RECOVERY_WAIT is set or the array is read-only, md_do_sync() will
return without setting MD_RECOVERY_DONE, and after commit f52f5c71f3d4
("md: fix stopping sync thread"), dm-raid switch from
md_reap_sync_thread() to stop_sync_thread() to unregister sync_thread
from md_stop() and md_stop_writes(), causing the test
shell/lvconvert-raid-reshape.sh hang.
We shouldn't switch back to md_reap_sync_thread() because it's
problematic in the first place. Fix the problem by making sure
md_do_sync() will set MD_RECOVERY_DONE.
Reported-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>
Closes: https://lore.kernel.org/all/ece2b06f-d647-6613-a534-ff4c9bec1142@xxxxxxxxxx/
Fixes: d5d885fd514f ("md: introduce new personality funciton start()")
Fixes: 5fd6c1dce06e ("[PATCH] md: allow checkpoint of recovery with version-1 superblock")
Fixes: f52f5c71f3d4 ("md: fix stopping sync thread")
Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx>
---
drivers/md/md.c | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 6906d023f1d6..c65dfd156090 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -8788,12 +8788,16 @@ void md_do_sync(struct md_thread *thread)
int ret;
/* just incase thread restarts... */
- if (test_bit(MD_RECOVERY_DONE, &mddev->recovery) ||
- test_bit(MD_RECOVERY_WAIT, &mddev->recovery))
+ if (test_bit(MD_RECOVERY_DONE, &mddev->recovery))
return;
- if (!md_is_rdwr(mddev)) {/* never try to sync a read-only array */
+
+ if (test_bit(MD_RECOVERY_INTR, &mddev->recovery))
+ goto skip;
+
+ if (test_bit(MD_RECOVERY_WAIT, &mddev->recovery) ||
+ !md_is_rdwr(mddev)) {/* never try to sync a read-only array */
set_bit(MD_RECOVERY_INTR, &mddev->recovery);
- return;
+ goto skip;
}
Hi all
I have a question here. The codes above means if MD_RECOVERY_WAIT is
set, it sets MD_RECOVERY_INTR. If so, the sync thread can't happen.
But from the codes in md_start function:
set_bit(MD_RECOVERY_WAIT, &mddev->recovery);
md_wakeup_thread(mddev->thread);
ret = mddev->pers->start(mddev);
clear_bit(MD_RECOVERY_WAIT, &mddev->recovery);
md_wakeup_thread(mddev->sync_thread);
MD_RECOVERY_WAIT means "it'll run sync thread later not interrupt it".
I guess this patch can introduce a new bug for raid5 journal?
I'm not sure what kind of problem you're talking about. After patch 4,
md_start_sync() should be the only place to register sync_thread, hence
md_start() should not see registered sync_thread. Perhaps
MD_RECOVERY_WAIT and md_wakeup_thread(mddev->sync_thread) can be removed
after patch 4?
And to resolve this deadlock, we can use this patch:
--- a/drivers/md/dm-raid.c
+++ b/drivers/md/dm-raid.c
@@ -3796,8 +3796,10 @@ static void raid_postsuspend(struct dm_target *ti)
struct raid_set *rs = ti->private;
if (!test_and_set_bit(RT_FLAG_RS_SUSPENDED, &rs->runtime_flags)) {
+ if (test_bit(MD_RECOVERY_WAIT, &rs->md.recovery))
+ clear_bit(MD_RECOVERY_WAIT, &rs->md.recovery);
You must make sure md_do_sync() is called after this if sync_thread is
already registered, and I don't understand yet how this is guranteed. :(
Thanks,
Kuai
Regards
Xiao
if (mddev_is_clustered(mddev)) {
--
2.39.2
.
