md: raid456 add nowait support

Returns EAGAIN in case the raid456 driver would block waiting for reshape.

Reviewed-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Vishal Verma <vverma@digitalocean.com>
Signed-off-by: Song Liu <song@kernel.org>

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 1240a5c16af8aec5ad84eda7c5a89811c9486863..beb544be9058442bbfb40db503c92780de9129a8 100644 (file)
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -5686,6 +5686,10 @@ static void make_discard_request(struct mddev *mddev, struct bio *bi)
        struct stripe_head *sh;
        int stripe_sectors;
 
+       /* We need to handle this when io_uring supports discard/trim */
+       if (WARN_ON_ONCE(bi->bi_opf & REQ_NOWAIT))
+               return;
+
        if (mddev->reshape_position != MaxSector)
                /* Skip discard while reshape is happening */
                return;
@@ -5819,6 +5823,17 @@ static bool raid5_make_request(struct mddev *mddev, struct bio * bi)
        last_sector = bio_end_sector(bi);
        bi->bi_next = NULL;
 
+       /* Bail out if conflicts with reshape and REQ_NOWAIT is set */
+       if ((bi->bi_opf & REQ_NOWAIT) &&
+           (conf->reshape_progress != MaxSector) &&
+           (mddev->reshape_backwards
+           ? (logical_sector > conf->reshape_progress && logical_sector <= conf->reshape_safe)
+           : (logical_sector >= conf->reshape_safe && logical_sector < conf->reshape_progress))) {
+               bio_wouldblock_error(bi);
+               if (rw == WRITE)
+                       md_write_end(mddev);
+               return true;
+       }
        md_account_bio(mddev, &bi);
        prepare_to_wait(&conf->wait_for_overlap, &w, TASK_UNINTERRUPTIBLE);
        for (; logical_sector < last_sector; logical_sector += RAID5_STRIPE_SECTORS(conf)) {