On Mon, Jun 20, 2022 at 8:11 PM Guoqing Jiang <guoqing.jiang@xxxxxxxxx> wrote:
>
> Since the bug which commit 8b48ec23cc51a ("md: don't unregister sync_thread
> with reconfig_mutex held") fixed is related with action_store path, other
> callers which reap sync_thread didn't need to be changed.
>
> Let's pull md_unregister_thread from md_reap_sync_thread, then fix previous
> bug with belows.
>
> 1. unlock mddev before md_reap_sync_thread in action_store.
> 2. save reshape_position before unlock, then restore it to ensure position
> not changed accidentally by others.
>
> Signed-off-by: Guoqing Jiang <guoqing.jiang@xxxxxxxxx>
> ---
> V2 changes:
> 1. add set_bit(MD_RECOVERY_INTR, &mddev->recovery) before unregister sync thread
>
> And I didn't find regression with this version after run mdadm tests.
>
> drivers/md/dm-raid.c | 1 +
> drivers/md/md.c | 19 +++++++++++++++++--
> 2 files changed, 18 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/md/dm-raid.c b/drivers/md/dm-raid.c
> index 9526ccbedafb..d43b8075c055 100644
> --- a/drivers/md/dm-raid.c
> +++ b/drivers/md/dm-raid.c
> @@ -3725,6 +3725,7 @@ static int raid_message(struct dm_target *ti, unsigned int argc, char **argv,
> if (!strcasecmp(argv[0], "idle") || !strcasecmp(argv[0], "frozen")) {
> if (mddev->sync_thread) {
> set_bit(MD_RECOVERY_INTR, &mddev->recovery);
> + md_unregister_thread(&mddev->sync_thread);
> md_reap_sync_thread(mddev);
> }
> } else if (decipher_sync_action(mddev, mddev->recovery) != st_idle)
> diff --git a/drivers/md/md.c b/drivers/md/md.c
> index c7ecb0bffda0..04bab0511312 100644
> --- a/drivers/md/md.c
> +++ b/drivers/md/md.c
> @@ -4830,6 +4830,19 @@ action_store(struct mddev *mddev, const char *page, size_t len)
> if (work_pending(&mddev->del_work))
> flush_workqueue(md_misc_wq);
> if (mddev->sync_thread) {
> + sector_t save_rp = mddev->reshape_position;
> +
> + mddev_unlock(mddev);
> + set_bit(MD_RECOVERY_INTR, &mddev->recovery);
> + md_unregister_thread(&mddev->sync_thread);
> + mddev_lock_nointr(mddev);
> + /*
> + * set RECOVERY_INTR again and restore reshape
> + * position in case others changed them after
> + * got lock, eg, reshape_position_store and
> + * md_check_recovery.
> + */
Hmm.. do we really need to handle reshape_position changed case? What would
break if we don't?
Thanks,
Song
> + mddev->reshape_position = save_rp;
> set_bit(MD_RECOVERY_INTR, &mddev->recovery);
> md_reap_sync_thread(mddev);
> }
> @@ -6197,6 +6210,7 @@ static void __md_stop_writes(struct mddev *mddev)
> flush_workqueue(md_misc_wq);
> if (mddev->sync_thread) {
> set_bit(MD_RECOVERY_INTR, &mddev->recovery);
> + md_unregister_thread(&mddev->sync_thread);
> md_reap_sync_thread(mddev);
> }
>
> @@ -9303,6 +9317,7 @@ void md_check_recovery(struct mddev *mddev)
> * ->spare_active and clear saved_raid_disk
> */
> set_bit(MD_RECOVERY_INTR, &mddev->recovery);
> + md_unregister_thread(&mddev->sync_thread);
> md_reap_sync_thread(mddev);
> clear_bit(MD_RECOVERY_RECOVER, &mddev->recovery);
> clear_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
> @@ -9338,6 +9353,7 @@ void md_check_recovery(struct mddev *mddev)
> goto unlock;
> }
> if (mddev->sync_thread) {
> + md_unregister_thread(&mddev->sync_thread);
> md_reap_sync_thread(mddev);
> goto unlock;
> }
> @@ -9417,8 +9433,7 @@ void md_reap_sync_thread(struct mddev *mddev)
> sector_t old_dev_sectors = mddev->dev_sectors;
> bool is_reshaped = false;
>
> - /* resync has finished, collect result */
> - md_unregister_thread(&mddev->sync_thread);
> + /* sync_thread should be unregistered, collect result */
> if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery) &&
> !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery) &&
> mddev->degraded != mddev->raid_disks) {
> --
> 2.31.1
>
