On 2017/10/31 下午4:14, tang.junhui@xxxxxxxxxx wrote:
> From: Tang Junhui <tang.junhui@xxxxxxxxxx>
>
> Currently, when a cached device detaching from cache, writeback thread is not stopped,
> and writeback_rate_update work is not canceled. For example, after bellow command:
> echo 1 >/sys/block/sdb/bcache/detach
> you can still see the writeback thread. Then you attach the device to the cache again,
> bcache will create another writeback thread, for example, after bellow command:
> echo ba0fb5cd-658a-4533-9806-6ce166d883b9 > /sys/block/sdb/bcache/attach
> then you will see 2 writeback threads.
> This patch stops writeback thread and cancels writeback_rate_update work when cached
> device detaching from cache.
>
> Signed-off-by: Tang Junhui <tang.junhui@xxxxxxxxxx>
If the change can be inside bch_register_lock, it would (just) be more
comfortable. The code is correct, because attach/detach sysfs is created
after writeback_thread created and writeback_rate_update worker
initialized, even these resources are initialized within
bch_register_lock and released out of bch)register_lock in your patch,
there won't be any race. It's OK to me.
Reviewed-by: Coly Li <colyli@xxxxxxx>
Thanks.
Coly Li
> ---
> drivers/md/bcache/super.c | 6 ++++++
> 1 file changed, 6 insertions(+)
> mode change 100644 => 100755 drivers/md/bcache/super.c
>
> diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
> old mode 100644
> new mode 100755
> index 8352fad..bf79892
> --- a/drivers/md/bcache/super.c
> +++ b/drivers/md/bcache/super.c
> @@ -891,6 +891,12 @@ static void cached_dev_detach_finish(struct work_struct *w)
> BUG_ON(!test_bit(BCACHE_DEV_DETACHING, &dc->disk.flags));
> BUG_ON(atomic_read(&dc->count));
>
> + cancel_delayed_work_sync(&dc->writeback_rate_update);
> + if (!IS_ERR_OR_NULL(dc->writeback_thread)) {
> + kthread_stop(dc->writeback_thread);
> + dc->writeback_thread = NULL;
> + }
> +
> mutex_lock(&bch_register_lock);
>
> memset(&dc->sb.set_uuid, 0, 16);
>
