This is a note to let you know that I've just added the patch titled

bcache: stop writeback thread after detaching

to the 4.15-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: bcache-stop-writeback-thread-after-detaching.patch and it can be found in the queue-4.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From foo@baz Mon Apr 9 10:16:32 CEST 2018

From: Tang Junhui tang.junhui@zte.com.cn Date: Mon, 8 Jan 2018 12:21:19 -0800 Subject: bcache: stop writeback thread after detaching

From: Tang Junhui tang.junhui@zte.com.cn

[ Upstream commit 8d29c4426b9f8afaccf28de414fde8a722b35fdf ]

Currently, when a cached device detaching from cache, writeback thread is not stopped, and writeback_rate_update work is not canceled. For example, after the following 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 below 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.

Compare with patch v1, this v2 patch moves code down into the register lock for safety in case of any future changes as Coly and Mike suggested.

[edit by mlyle: commit log spelling/formatting]

Signed-off-by: Tang Junhui tang.junhui@zte.com.cn Reviewed-by: Michael Lyle mlyle@lyle.org Signed-off-by: Michael Lyle mlyle@lyle.org Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/md/bcache/super.c | 6 ++++++ 1 file changed, 6 insertions(+)

--- a/drivers/md/bcache/super.c +++ b/drivers/md/bcache/super.c @@ -906,6 +906,12 @@ static void cached_dev_detach_finish(str

mutex_lock(&bch_register_lock);

+ 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; + } + memset(&dc->sb.set_uuid, 0, 16); SET_BDEV_STATE(&dc->sb, BDEV_STATE_NONE);

Patches currently in stable-queue which might be from tang.junhui@zte.com.cn are

queue-4.15/bcache-segregate-flash-only-volume-write-streams.patch queue-4.15/bcache-stop-writeback-thread-after-detaching.patch