On Thu, Aug 02 2018 at 4:18am -0400,
Hou Tao <houtao1@xxxxxxxxxx> wrote:
> Now both check_for_space() and do_no_space_timeout() will read & write
> error_if_no_space in pool->pf. If these functions run concurrently as
> shown in the following case, the error_if_no_space feature requested
> by user may get lost.
>
> precondition:
> * error_if_no_space = 0
> * Out-of-Data-Space occurs
> * no_space_timeout worker has been queued
>
> CPU 0: CPU 1:
> // delete a thin device
> process_delete_mesg()
> // inovked by commit()
> set_pool_mode(pool, PM_WRITE)
> pool->pf.error_if_no_space = \
> pt->requested_pf.error_if_no_space
>
> // timeout
> do_no_space_timeout
> // the user configuration is lost
> pool->pf.error_if_no_space = true
> pool->pf.mode = new_mode
>
> Fix it by stopping no_space_timeout worker before switching to write mode.
>
> Signed-off-by: Hou Tao <houtao1@xxxxxxxxxx>
> ---
> drivers/md/dm-thin.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
> index b900723bbd0f..c6da4afc16cf 100644
> --- a/drivers/md/dm-thin.c
> +++ b/drivers/md/dm-thin.c
> @@ -1401,6 +1401,7 @@ static void check_for_space(struct pool *pool)
> return;
>
> if (nr_free) {
> + cancel_delayed_work_sync(&pool->no_space_timeout);
> set_pool_mode(pool, PM_WRITE);
> requeue_bios(pool);
> }
> --
> 2.16.2.dirty
>
Thanks for the patch, I tweaked the header a bit and also moved the
cancel_delayed_work_sync() to set_pool_mode(), please see:
https://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm.git/commit/?h=dm-4.19&id=eff8f4c73dd13f7d53015fc911d66f6671dd82b8
Please let me know if you have any issues with this, otherwise it is
staged for 4.19 inclussion.
Thanks,
Mike
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