On Fri, 30 Aug 2024 15:27:18 +0800
Yu Kuai <yukuai1@xxxxxxxxxxxxxxx> wrote:
> From: Yu Kuai <yukuai3@xxxxxxxxxx>
>
> Currently raid1 is preparing IO for underlying disks while checking if
> any disk is blocked, if so allocated resources must be released, then
> waiting for rdev to be unblocked and try to prepare IO again.
>
> Make code cleaner by checking blocked rdev first, it doesn't matter if
> rdev is blocked while issuing this IO.
>
> Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx>
> ---
> drivers/md/raid1.c | 84 ++++++++++++++++++++++++++--------------------
> 1 file changed, 48 insertions(+), 36 deletions(-)
>
> diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
> index f55c8e67d059..aa30c3240c85 100644
> --- a/drivers/md/raid1.c
> +++ b/drivers/md/raid1.c
> @@ -1406,6 +1406,49 @@ static void raid1_read_request(struct mddev *mddev,
> struct bio *bio, submit_bio_noacct(read_bio);
> }
>
> +static bool wait_blocked_rdev(struct mddev *mddev, struct bio *bio)
> +{
> + struct r1conf *conf = mddev->private;
> + int disks = conf->raid_disks * 2;
> + int i;
> +
> +retry:
> + for (i = 0; i < disks; i++) {
> + struct md_rdev *rdev = conf->mirrors[i].rdev;
> +
> + if (!rdev)
> + continue;
> +
> + if (test_bit(Blocked, &rdev->flags)) {
Don't we need unlikely here?
> + if (bio->bi_opf & REQ_NOWAIT)
> + return false;
> +
> + mddev_add_trace_msg(rdev->mddev, "raid1 wait rdev %d
> blocked",
> + rdev->raid_disk);
> + atomic_inc(&rdev->nr_pending);
retry moves us before for (ugh, ugly) and "theoretically" we can back here
with the same disk and increase nr_pending twice or more because rdve can become
block again from different thread.
This is what I suspect but it could be wrong.
Mariusz
