block: Add bio_end_sector()

Just a little convenience macro - main reason to add it now is preparing
for immutable bio vecs, it'll reduce the size of the patch that puts
bi_sector/bi_size/bi_idx into a struct bvec_iter.

Signed-off-by: Kent Overstreet <koverstreet@google.com>
CC: Jens Axboe <axboe@kernel.dk>
CC: Lars Ellenberg <drbd-dev@lists.linbit.com>
CC: Jiri Kosina <jkosina@suse.cz>
CC: Alasdair Kergon <agk@redhat.com>
CC: dm-devel@redhat.com
CC: Neil Brown <neilb@suse.de>
CC: Martin Schwidefsky <schwidefsky@de.ibm.com>
CC: Heiko Carstens <heiko.carstens@de.ibm.com>
CC: linux-s390@vger.kernel.org
CC: Chris Mason <chris.mason@fusionio.com>
CC: Steven Whitehouse <swhiteho@redhat.com>
Acked-by: Steven Whitehouse <swhiteho@redhat.com>
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 3ee2912..6870697 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -2384,11 +2384,11 @@
 	} else
 		bip = &sh->dev[dd_idx].toread;
 	while (*bip && (*bip)->bi_sector < bi->bi_sector) {
-		if ((*bip)->bi_sector + ((*bip)->bi_size >> 9) > bi->bi_sector)
+		if (bio_end_sector(*bip) > bi->bi_sector)
 			goto overlap;
 		bip = & (*bip)->bi_next;
 	}
-	if (*bip && (*bip)->bi_sector < bi->bi_sector + ((bi->bi_size)>>9))
+	if (*bip && (*bip)->bi_sector < bio_end_sector(bi))
 		goto overlap;
 
 	BUG_ON(*bip && bi->bi_next && (*bip) != bi->bi_next);
@@ -2404,8 +2404,8 @@
 		     sector < sh->dev[dd_idx].sector + STRIPE_SECTORS &&
 			     bi && bi->bi_sector <= sector;
 		     bi = r5_next_bio(bi, sh->dev[dd_idx].sector)) {
-			if (bi->bi_sector + (bi->bi_size>>9) >= sector)
-				sector = bi->bi_sector + (bi->bi_size>>9);
+			if (bio_end_sector(bi) >= sector)
+				sector = bio_end_sector(bi);
 		}
 		if (sector >= sh->dev[dd_idx].sector + STRIPE_SECTORS)
 			set_bit(R5_OVERWRITE, &sh->dev[dd_idx].flags);
@@ -3941,7 +3941,7 @@
 						    0,
 						    &dd_idx, NULL);
 
-	end_sector = align_bi->bi_sector + (align_bi->bi_size >> 9);
+	end_sector = bio_end_sector(align_bi);
 	rcu_read_lock();
 	rdev = rcu_dereference(conf->disks[dd_idx].replacement);
 	if (!rdev || test_bit(Faulty, &rdev->flags) ||
@@ -4216,7 +4216,7 @@
 	}
 
 	logical_sector = bi->bi_sector & ~((sector_t)STRIPE_SECTORS-1);
-	last_sector = bi->bi_sector + (bi->bi_size>>9);
+	last_sector = bio_end_sector(bi);
 	bi->bi_next = NULL;
 	bi->bi_phys_segments = 1;	/* over-loaded to count active stripes */
 
@@ -4679,7 +4679,7 @@
 	logical_sector = raid_bio->bi_sector & ~((sector_t)STRIPE_SECTORS-1);
 	sector = raid5_compute_sector(conf, logical_sector,
 				      0, &dd_idx, NULL);
-	last_sector = raid_bio->bi_sector + (raid_bio->bi_size>>9);
+	last_sector = bio_end_sector(raid_bio);
 
 	for (; logical_sector < last_sector;
 	     logical_sector += STRIPE_SECTORS,