[BLOCK] Unify the seperate read/write io stat fields into arrays

Instead of having ->read_sectors and ->write_sectors, combine the two
into ->sectors[2] and similar for the other fields. This saves a branch
several places in the io path, since we don't have to care for what the
actual io direction is. On my x86-64 box, that's 200 bytes less text in
just the core (not counting the various drivers).

Signed-off-by: Jens Axboe <axboe@suse.de>

1 files changed, 3 insertions, 7 deletions

diff --git a/drivers/md/multipath.c b/drivers/md/multipath.c
index 1151c3ed3006..c06f4474192b 100644
--- a/drivers/md/multipath.c
+++ b/drivers/md/multipath.c
@@ -168,6 +168,7 @@ static int multipath_make_request (request_queue_t *q, struct bio * bio)
         multipath_conf_t *conf = mddev_to_conf(mddev);
         struct multipath_bh * mp_bh;
         struct multipath_info *multipath;
+        const int rw = bio_data_dir(bio);
 
         if (unlikely(bio_barrier(bio))) {
                 bio_endio(bio, bio->bi_size, -EOPNOTSUPP);
@@ -179,13 +180,8 @@ static int multipath_make_request (request_queue_t *q, struct bio * bio)
         mp_bh->master_bio = bio;
         mp_bh->mddev = mddev;
 
-        if (bio_data_dir(bio)==WRITE) {
-                disk_stat_inc(mddev->gendisk, writes);
-                disk_stat_add(mddev->gendisk, write_sectors, bio_sectors(bio));
-        } else {
-                disk_stat_inc(mddev->gendisk, reads);
-                disk_stat_add(mddev->gendisk, read_sectors, bio_sectors(bio));
-        }
+        disk_stat_inc(mddev->gendisk, ios[rw]);
+        disk_stat_add(mddev->gendisk, sectors[rw], bio_sectors(bio));
 
         mp_bh->path = multipath_map(conf);
         if (mp_bh->path < 0) {