md/raid1: fix the comparing region of interval tree

Interval tree uses [start, end] as a region which stores in the tree.
In raid1, it uses the wrong end value. For example:
bio(A,B) is too big and needs to be split to bio1(A,C-1), bio2(C,B).
The region of bio1 is [A,C] and the region of bio2 is [C,B]. So bio1 and
bio2 overlap which is not right.

Fix this problem by using right end value of the region.

Fixes: d0d2d8b ("md/raid1: introduce wait_for_serialization")
Signed-off-by: Xiao Ni <xni@redhat.com>
Link: https://lore.kernel.org/linux-raid/20260305011839.5118-2-xni@redhat.com/
Signed-off-by: Yu Kuai <yukuai3@huawei.com>

Author: XiaoNi87

drivers/md/raid1.c

@@ -62,7 +62,7 @@ static int check_and_add_serial(struct md_rdev *rdev, struct r1bio *r1_bio,
 	unsigned long flags;
 	int ret = 0;
 	sector_t lo = r1_bio->sector;
-	sector_t hi = lo + r1_bio->sectors;
+	sector_t hi = lo + r1_bio->sectors - 1;
 	struct serial_in_rdev *serial = &rdev->serial[idx];
 
 	spin_lock_irqsave(&serial->serial_lock, flags);
@@ -452,7 +452,7 @@ static void raid1_end_write_request(struct bio *bio)
 	int mirror = find_bio_disk(r1_bio, bio);
 	struct md_rdev *rdev = conf->mirrors[mirror].rdev;
 	sector_t lo = r1_bio->sector;
-	sector_t hi = r1_bio->sector + r1_bio->sectors;
+	sector_t hi = r1_bio->sector + r1_bio->sectors - 1;
 	bool ignore_error = !raid1_should_handle_error(bio) ||
 		(bio->bi_status && bio_op(bio) == REQ_OP_DISCARD);