Re: [PATCH 4/9] md: raid5 nowait support

[Shaohua Li <shli@kernel.org>]

On Wed, Jul 26, 2017 at 06:58:01PM -0500, Goldwyn Rodrigues wrote:
> From: Goldwyn Rodrigues <rgoldwyn@suse.com>
> 
> Return EAGAIN in case RAID5 would block because of waiting due to:
>  + Reshaping
>  + Suspension
>  + Stripe Expansion
> 
> Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
> ---
>  drivers/md/raid5.c | 20 ++++++++++++++++++++
>  1 file changed, 20 insertions(+)
> 
> diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
> index aeeb8d6854e2..d1b3bcf26d29 100644
> --- a/drivers/md/raid5.c
> +++ b/drivers/md/raid5.c
> @@ -5635,6 +5635,11 @@ static bool raid5_make_request(struct mddev *mddev, struct bio * bi)
>  				    ? logical_sector < conf->reshape_safe
>  				    : logical_sector >= conf->reshape_safe) {
>  					spin_unlock_irq(&conf->device_lock);
> +					if (bi->bi_opf & REQ_NOWAIT) {
> +						bio_wouldblock_error(bi);
> +						finish_wait(&conf->wait_for_overlap, &w);
> +						return true;
> +					}

A bio could use several stripes. If one stripe block, simpliy return bio here
doesn't really make the whole bio finish.

>  					schedule();
>  					do_prepare = true;
>  					goto retry;
> @@ -5672,6 +5677,11 @@ static bool raid5_make_request(struct mddev *mddev, struct bio * bi)
>  				spin_unlock_irq(&conf->device_lock);
>  				if (must_retry) {
>  					raid5_release_stripe(sh);
> +					if (bi->bi_opf & REQ_NOWAIT) {
> +						bio_wouldblock_error(bi);
> +						finish_wait(&conf->wait_for_overlap, &w);
> +						return true;
> +					}
>  					schedule();
>  					do_prepare = true;
>  					goto retry;
> @@ -5700,6 +5710,11 @@ static bool raid5_make_request(struct mddev *mddev, struct bio * bi)
>  					sigset_t full, old;
>  					sigfillset(&full);
>  					sigprocmask(SIG_BLOCK, &full, &old);
> +					if (bi->bi_opf & REQ_NOWAIT) {
> +						bio_wouldblock_error(bi);
> +						finish_wait(&conf->wait_for_overlap, &w);
> +						return true;
> +					}
>  					schedule();
>  					sigprocmask(SIG_SETMASK, &old, NULL);
>  					do_prepare = true;
> @@ -5715,6 +5730,11 @@ static bool raid5_make_request(struct mddev *mddev, struct bio * bi)
>  				 */
>  				md_wakeup_thread(mddev->thread);
>  				raid5_release_stripe(sh);
> +				if (bi->bi_opf & REQ_NOWAIT) {
> +					bio_wouldblock_error(bi);
> +					finish_wait(&conf->wait_for_overlap, &w);
> +					return true;
> +				}
>  				schedule();
>  				do_prepare = true;
>  				goto retry;
> -- 
> 2.12.3
> 
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