commit 0d74ac66ed0ec5af70296545e26044723a14657c
Author: Xiao Ni <xni@redhat.com>
Date:   Thu Dec 24 17:58:43 2020 +0800

    fix

diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index 3153183b7772..92182cf40d22 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -1604,6 +1604,7 @@ static int raid10_handle_discard(struct mddev *mddev, struct bio *bio)
 	sector_t chunk;
 	unsigned int stripe_size;
 	sector_t split_size;
+	sector_t chunk_size = 1 << geo->chunk_shift;
 
 	sector_t bio_start, bio_end;
 	sector_t first_stripe_index, last_stripe_index;
@@ -1624,7 +1625,8 @@ static int raid10_handle_discard(struct mddev *mddev, struct bio *bio)
 	if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
 		goto out;
 
-	stripe_size = geo->raid_disks << geo->chunk_shift;
+	stripe_size = geo->near_copies ? geo->near_copies << geo->chunk_shift:
+				geo->raid_disks << geo->chunk_shift;
 	bio_start = bio->bi_iter.bi_sector;
 	bio_end = bio_end_sector(bio);
 
@@ -1637,6 +1639,18 @@ static int raid10_handle_discard(struct mddev *mddev, struct bio *bio)
 	if (bio_sectors(bio) < stripe_size*2)
 		goto out;
 
+	/* Keep the discard start/end address aligned with chunk size */
+	if (bio_start & geo->chunk_mask) {
+		split_size = (chunk_size - (bio_start & geo->chunk_mask));
+		bio = raid10_split_bio(conf, bio, split_size, false);
+	}
+	if (bio_end & geo->chunk_mask) {
+		split_size = bio_end & geo->chunk_mask;
+		bio = raid10_split_bio(conf, bio, split_size, true);
+	}
+	bio_start = bio->bi_iter.bi_sector;
+	bio_end = bio_end_sector(bio);
+
 	/* For far and far offset layout, if bio is not aligned with stripe size,
 	 * it splits the part that is not aligned with strip size.
 	 */
@@ -1664,8 +1678,8 @@ static int raid10_handle_discard(struct mddev *mddev, struct bio *bio)
 	start_disk_index = sector_div(first_stripe_index, geo->raid_disks);
 	if (geo->far_offset)
 		first_stripe_index *= geo->far_copies;
-	start_disk_offset = (bio_start & geo->chunk_mask) +
-				(first_stripe_index << geo->chunk_shift);
+	/* Now the bio is aligned with chunk size */
+	start_disk_offset = first_stripe_index << geo->chunk_shift;
 
 	chunk = bio_end >> geo->chunk_shift;
 	chunk *= geo->near_copies;
@@ -1673,8 +1687,7 @@ static int raid10_handle_discard(struct mddev *mddev, struct bio *bio)
 	end_disk_index = sector_div(last_stripe_index, geo->raid_disks);
 	if (geo->far_offset)
 		last_stripe_index *= geo->far_copies;
-	end_disk_offset = (bio_end & geo->chunk_mask) +
-				(last_stripe_index << geo->chunk_shift);
+	end_disk_offset = last_stripe_index << geo->chunk_shift;
 
 retry_discard:
 	r10_bio = mempool_alloc(&conf->r10bio_pool, GFP_NOIO);