On Tue, Dec 14, 2021 at 10:09 PM Vishal Verma <vverma@xxxxxxxxxxxxxxxx> wrote:
>
> This adds nowait support to the RAID10 driver. Very similar to
> raid1 driver changes. It makes RAID10 driver return with EAGAIN
> for situations where it could wait for eg:
>
> - Waiting for the barrier,
> - Too many pending I/Os to be queued,
> - Reshape operation,
> - Discard operation.
>
> wait_barrier() fn is modified to return bool to support error for
> wait barriers. It returns true in case of wait or if wait is not
> required and returns false if wait was required but not performed
> to support nowait.
>
> Signed-off-by: Vishal Verma <vverma@xxxxxxxxxxxxxxxx>
> ---
> drivers/md/raid10.c | 57 +++++++++++++++++++++++++++++++++++----------
> 1 file changed, 45 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
> index dde98f65bd04..f6c73987e9ac 100644
> --- a/drivers/md/raid10.c
> +++ b/drivers/md/raid10.c
> @@ -952,11 +952,18 @@ static void lower_barrier(struct r10conf *conf)
> wake_up(&conf->wait_barrier);
> }
>
> -static void wait_barrier(struct r10conf *conf)
> +static bool wait_barrier(struct r10conf *conf, bool nowait)
> {
> spin_lock_irq(&conf->resync_lock);
> if (conf->barrier) {
> struct bio_list *bio_list = current->bio_list;
> +
> + /* Return false when nowait flag is set */
> + if (nowait) {
> + spin_unlock_irq(&conf->resync_lock);
> + return false;
> + }
> +
> conf->nr_waiting++;
> /* Wait for the barrier to drop.
> * However if there are already pending
> @@ -988,6 +995,7 @@ static void wait_barrier(struct r10conf *conf)
> }
> atomic_inc(&conf->nr_pending);
> spin_unlock_irq(&conf->resync_lock);
> + return true;
> }
>
> static void allow_barrier(struct r10conf *conf)
> @@ -1101,17 +1109,25 @@ static void raid10_unplug(struct blk_plug_cb *cb, bool from_schedule)
> static void regular_request_wait(struct mddev *mddev, struct r10conf *conf,
> struct bio *bio, sector_t sectors)
> {
> - wait_barrier(conf);
> + /* Bail out if REQ_NOWAIT is set for the bio */
> + if (!wait_barrier(conf, bio->bi_opf & REQ_NOWAIT)) {
> + bio_wouldblock_error(bio);
> + return;
> + }
I think we also need regular_request_wait to return bool and handle it properly.
Thanks,
Song
> while (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery) &&
> bio->bi_iter.bi_sector < conf->reshape_progress &&
> bio->bi_iter.bi_sector + sectors > conf->reshape_progress) {
> raid10_log(conf->mddev, "wait reshape");
> + if (bio->bi_opf & REQ_NOWAIT) {
> + bio_wouldblock_error(bio);
> + return;
> + }
> allow_barrier(conf);
> wait_event(conf->wait_barrier,
> conf->reshape_progress <= bio->bi_iter.bi_sector ||
> conf->reshape_progress >= bio->bi_iter.bi_sector +
> sectors);
> - wait_barrier(conf);
> + wait_barrier(conf, false);
> }
> }
>
> @@ -1179,7 +1195,7 @@ static void raid10_read_request(struct mddev *mddev, struct bio *bio,
> bio_chain(split, bio);
> allow_barrier(conf);
> submit_bio_noacct(bio);
> - wait_barrier(conf);
> + wait_barrier(conf, false);
> bio = split;
> r10_bio->master_bio = bio;
> r10_bio->sectors = max_sectors;
> @@ -1338,7 +1354,7 @@ static void wait_blocked_dev(struct mddev *mddev, struct r10bio *r10_bio)
> raid10_log(conf->mddev, "%s wait rdev %d blocked",
> __func__, blocked_rdev->raid_disk);
> md_wait_for_blocked_rdev(blocked_rdev, mddev);
> - wait_barrier(conf);
> + wait_barrier(conf, false);
> goto retry_wait;
> }
> }
> @@ -1357,6 +1373,11 @@ static void raid10_write_request(struct mddev *mddev, struct bio *bio,
> bio_end_sector(bio)))) {
> DEFINE_WAIT(w);
> for (;;) {
> + /* Bail out if REQ_NOWAIT is set for the bio */
> + if (bio->bi_opf & REQ_NOWAIT) {
> + bio_wouldblock_error(bio);
> + return;
> + }
> prepare_to_wait(&conf->wait_barrier,
> &w, TASK_IDLE);
> if (!md_cluster_ops->area_resyncing(mddev, WRITE,
> @@ -1381,6 +1402,10 @@ static void raid10_write_request(struct mddev *mddev, struct bio *bio,
> BIT(MD_SB_CHANGE_DEVS) | BIT(MD_SB_CHANGE_PENDING));
> md_wakeup_thread(mddev->thread);
> raid10_log(conf->mddev, "wait reshape metadata");
> + if (bio->bi_opf & REQ_NOWAIT) {
> + bio_wouldblock_error(bio);
> + return;
> + }
> wait_event(mddev->sb_wait,
> !test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags));
>
> @@ -1390,6 +1415,10 @@ static void raid10_write_request(struct mddev *mddev, struct bio *bio,
> if (conf->pending_count >= max_queued_requests) {
> md_wakeup_thread(mddev->thread);
> raid10_log(mddev, "wait queued");
> + if (bio->bi_opf & REQ_NOWAIT) {
> + bio_wouldblock_error(bio);
> + return;
> + }
> wait_event(conf->wait_barrier,
> conf->pending_count < max_queued_requests);
> }
> @@ -1482,7 +1511,7 @@ static void raid10_write_request(struct mddev *mddev, struct bio *bio,
> bio_chain(split, bio);
> allow_barrier(conf);
> submit_bio_noacct(bio);
> - wait_barrier(conf);
> + wait_barrier(conf, false);
> bio = split;
> r10_bio->master_bio = bio;
> }
> @@ -1607,7 +1636,11 @@ static int raid10_handle_discard(struct mddev *mddev, struct bio *bio)
> if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
> return -EAGAIN;
>
> - wait_barrier(conf);
> + if (bio->bi_opf & REQ_NOWAIT) {
> + bio_wouldblock_error(bio);
> + return 0;
> + }
> + wait_barrier(conf, false);
>
> /*
> * Check reshape again to avoid reshape happens after checking
> @@ -1649,7 +1682,7 @@ static int raid10_handle_discard(struct mddev *mddev, struct bio *bio)
> allow_barrier(conf);
> /* Resend the fist split part */
> submit_bio_noacct(split);
> - wait_barrier(conf);
> + wait_barrier(conf, false);
> }
> div_u64_rem(bio_end, stripe_size, &remainder);
> if (remainder) {
> @@ -1660,7 +1693,7 @@ static int raid10_handle_discard(struct mddev *mddev, struct bio *bio)
> /* Resend the second split part */
> submit_bio_noacct(bio);
> bio = split;
> - wait_barrier(conf);
> + wait_barrier(conf, false);
> }
>
> bio_start = bio->bi_iter.bi_sector;
> @@ -1816,7 +1849,7 @@ static int raid10_handle_discard(struct mddev *mddev, struct bio *bio)
> end_disk_offset += geo->stride;
> atomic_inc(&first_r10bio->remaining);
> raid_end_discard_bio(r10_bio);
> - wait_barrier(conf);
> + wait_barrier(conf, false);
> goto retry_discard;
> }
>
> @@ -2011,7 +2044,7 @@ static void print_conf(struct r10conf *conf)
>
> static void close_sync(struct r10conf *conf)
> {
> - wait_barrier(conf);
> + wait_barrier(conf, false);
> allow_barrier(conf);
>
> mempool_exit(&conf->r10buf_pool);
> @@ -4819,7 +4852,7 @@ static sector_t reshape_request(struct mddev *mddev, sector_t sector_nr,
> if (need_flush ||
> time_after(jiffies, conf->reshape_checkpoint + 10*HZ)) {
> /* Need to update reshape_position in metadata */
> - wait_barrier(conf);
> + wait_barrier(conf, false);
> mddev->reshape_position = conf->reshape_progress;
> if (mddev->reshape_backwards)
> mddev->curr_resync_completed = raid10_size(mddev, 0, 0)
> --
> 2.17.1
>
