On Wed, Jul 26, 2017 at 06:58:02PM -0500, Goldwyn Rodrigues wrote:
> From: Goldwyn Rodrigues <rgold...@suse.com>
> 
> Bail and status to EAGAIN if raid10 is going to wait for:
>  + barriers
>  + reshape operation
>  + Too many queued requests
> 
> Signed-off-by: Goldwyn Rodrigues <rgold...@suse.com>
> ---
>  drivers/md/raid10.c | 62 
> ++++++++++++++++++++++++++++++++++++++++-------------
>  1 file changed, 47 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
> index 5026e7ad51d3..6d80438c5040 100644
> --- a/drivers/md/raid10.c
> +++ b/drivers/md/raid10.c
> @@ -978,8 +978,9 @@ 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)
>  {
> +     bool ret = true;
>       spin_lock_irq(&conf->resync_lock);
>       if (conf->barrier) {
>               conf->nr_waiting++;
> @@ -993,19 +994,23 @@ static void wait_barrier(struct r10conf *conf)
>                * count down.
>                */
>               raid10_log(conf->mddev, "wait barrier");
> -             wait_event_lock_irq(conf->wait_barrier,
> -                                 !conf->barrier ||
> -                                 (atomic_read(&conf->nr_pending) &&
> -                                  current->bio_list &&
> -                                  (!bio_list_empty(&current->bio_list[0]) ||
> -                                   !bio_list_empty(&current->bio_list[1]))),
> -                                 conf->resync_lock);
> +             if (!nowait)
> +                     wait_event_lock_irq(conf->wait_barrier,
> +                                         !conf->barrier ||
> +                                         (atomic_read(&conf->nr_pending) &&
> +                                          current->bio_list &&
> +                                          
> (!bio_list_empty(&current->bio_list[0]) ||
> +                                           
> !bio_list_empty(&current->bio_list[1]))),
> +                                         conf->resync_lock);
> +             else
> +                     ret = false;
same here, nr_pending shouldn't be increased

>               conf->nr_waiting--;
>               if (!conf->nr_waiting)
>                       wake_up(&conf->wait_barrier);
>       }
>       atomic_inc(&conf->nr_pending);
>       spin_unlock_irq(&conf->resync_lock);
> +     return ret;
>  }
>  
>  static void allow_barrier(struct r10conf *conf)
> @@ -1158,7 +1163,10 @@ static void raid10_read_request(struct mddev *mddev, 
> struct bio *bio,
>        * thread has put up a bar for new requests.
>        * Continue immediately if no resync is active currently.
>        */
> -     wait_barrier(conf);
> +     if (!wait_barrier(conf, bio->bi_opf & REQ_NOWAIT)) {
> +             bio_wouldblock_error(bio);
> +             return;
> +     }
>  
>       sectors = r10_bio->sectors;
>       while (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery) &&
> @@ -1169,12 +1177,16 @@ static void raid10_read_request(struct mddev *mddev, 
> struct bio *bio,
>                * pass
>                */
>               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);
>       }
>  
>       rdev = read_balance(conf, r10_bio, &max_sectors);
> @@ -1308,7 +1320,10 @@ static void raid10_write_request(struct mddev *mddev, 
> struct bio *bio,
>        * thread has put up a bar for new requests.
>        * Continue immediately if no resync is active currently.
>        */
> -     wait_barrier(conf);
> +     if (!wait_barrier(conf, bio->bi_opf & REQ_NOWAIT)) {
> +             bio_wouldblock_error(bio);
> +             return;
> +     }
>  
>       sectors = r10_bio->sectors;
>       while (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery) &&
> @@ -1319,12 +1334,16 @@ static void raid10_write_request(struct mddev *mddev, 
> struct bio *bio,
>                * pass
>                */
>               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);
>       }
>  
>       if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery) &&
> @@ -1339,6 +1358,10 @@ 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));
>  
> @@ -1348,6 +1371,10 @@ 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);
>       }
> @@ -1454,6 +1481,11 @@ static void raid10_write_request(struct mddev *mddev, 
> struct bio *bio,
>               int j;
>               int d;
>  
> +             if (bio->bi_opf & REQ_NOWAIT) {
> +                     bio_wouldblock_error(bio);
> +                     return;
> +             }
> +
>               for (j = 0; j < i; j++) {
>                       if (r10_bio->devs[j].bio) {
>                               d = r10_bio->devs[j].devnum;
> @@ -1474,7 +1506,7 @@ static void raid10_write_request(struct mddev *mddev, 
> struct bio *bio,
>               allow_barrier(conf);
>               raid10_log(conf->mddev, "wait rdev %d blocked", 
> blocked_rdev->raid_disk);
>               md_wait_for_blocked_rdev(blocked_rdev, mddev);
> -             wait_barrier(conf);
> +             wait_barrier(conf, false);
>               goto retry_write;
>       }
>  
> @@ -1703,7 +1735,7 @@ 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_destroy(conf->r10buf_pool);
> @@ -4347,7 +4379,7 @@ 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)
> -- 
> 2.12.3
> 
> --
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