The patch below does not apply to the 4.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 75294442d896f2767be34f75aca7cc2b0d01301f Mon Sep 17 00:00:00 2001

From: Hou Tao houtao1@huawei.com Date: Thu, 2 Aug 2018 16:18:24 +0800 Subject: [PATCH] dm thin: stop no_space_timeout worker when switching to write-mode

Now both check_for_space() and do_no_space_timeout() will read & write pool->pf.error_if_no_space. If these functions run concurrently, as shown in the following case, the default setting of "queue_if_no_space" can get lost.

precondition: * error_if_no_space = false (aka "queue_if_no_space") * pool is in Out-of-Data-Space (OODS) mode * no_space_timeout worker has been queued

CPU 0: CPU 1: // delete a thin device process_delete_mesg() // check_for_space() invoked by commit() set_pool_mode(pool, PM_WRITE) pool->pf.error_if_no_space = \ pt->requested_pf.error_if_no_space

// timeout, pool is still in OODS mode do_no_space_timeout // "queue_if_no_space" config is lost pool->pf.error_if_no_space = true pool->pf.mode = new_mode

Fix it by stopping no_space_timeout worker when switching to write mode.

Fixes: bcc696fac11f ("dm thin: stay in out-of-data-space mode once no_space_timeout expires") Cc: stable@vger.kernel.org Signed-off-by: Hou Tao houtao1@huawei.com Signed-off-by: Mike Snitzer snitzer@redhat.com

diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c index 5997d6808b57..7bd60a150f8f 100644 --- a/drivers/md/dm-thin.c +++ b/drivers/md/dm-thin.c @@ -2503,6 +2503,8 @@ static void set_pool_mode(struct pool *pool, enum pool_mode new_mode) case PM_WRITE: if (old_mode != new_mode) notify_of_pool_mode_change(pool, "write"); + if (old_mode == PM_OUT_OF_DATA_SPACE) + cancel_delayed_work_sync(&pool->no_space_timeout); pool->out_of_data_space = false; pool->pf.error_if_no_space = pt->requested_pf.error_if_no_space; dm_pool_metadata_read_write(pool->pmd);