On 2022-09-13 19:49, Yu Kuai wrote:
> From: Yu Kuai <yukuai3@xxxxxxxxxx>
>
> Currently the nasty condition is wait_barrier() is hard to read. This
> patch factor out the condition into a function.
>
> There are no functional changes.
>
> Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx>
> ---
> drivers/md/raid10.c | 56 ++++++++++++++++++++++++++-------------------
> 1 file changed, 32 insertions(+), 24 deletions(-)
>
> diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
> index 64d6e4cd8a3a..56458a53043d 100644
> --- a/drivers/md/raid10.c
> +++ b/drivers/md/raid10.c
> @@ -957,44 +957,52 @@ static void lower_barrier(struct r10conf *conf)
> wake_up(&conf->wait_barrier);
> }
>
> +static bool stop_waiting_barrier(struct r10conf *conf)
> +{
> + /* barrier is dropped */
> + if (!conf->barrier)
> + return true;
> +
> + /*
> + * If there are already pending requests (preventing the barrier from
> + * rising completely), and the pre-process bio queue isn't empty, then
> + * don't wait, as we need to empty that queue to get the nr_pending
> + * count down.
> + */
> + if (atomic_read(&conf->nr_pending)) {
> + struct bio_list *bio_list = current->bio_list;
I'd probably just put the bio_list declaration at the top of this
function, then the nested if statements are not necessary. The compiler
should be able to optimize the access just fine.
> if (conf->barrier) {
> - struct bio_list *bio_list = current->bio_list;
> - conf->nr_waiting++;
> - /* Wait for the barrier to drop.
> - * However if there are already pending
> - * requests (preventing the barrier from
> - * rising completely), and the
> - * pre-process bio queue isn't empty,
> - * then don't wait, as we need to empty
> - * that queue to get the nr_pending
> - * count down.
> - */
> /* Return false when nowait flag is set */
> if (nowait) {
> ret = false;
> } else {
> + conf->nr_waiting++;
Technically speaking, I think moving nr_waiting counts as a functional
change. As best as I can see it is correct, but it should probably be at
least mentioned in the commit message, or maybe done as a separate
commit with it's own justification. That way if it causes problems down
the road, a bisect will make the issue clearer.
Thanks,
Logan
