Merge tag 'md/4.0-rc7-fix' of git://neil.brown.name/md

Pull md fixes from Neil Brown:
 "Two regression fixes for md, one fairly recent and minor (diskstats
  has confusing data) and one older and more serious - RAID0 with
  non-power-of-2 chunksize corrupts data.

  I guess (almost) no-one uses non-power-of-2 chunks.

  Summary:

   - Revert recent change which broke IO accounting.

   - Fix bug with RAID0 arrays with non-power-of-2 chunk size"

* tag 'md/4.0-rc7-fix' of git://neil.brown.name/md:
  md/raid0: fix bug with chunksize not a power of 2.
  md: fix md io stats accounting broken

drivers/md/md.c

@@ -249,6 +249,7 @@ static void md_make_request(struct request_queue *q, struct bio *bio)
 	const int rw = bio_data_dir(bio);
 	struct mddev *mddev = q->queuedata;
 	unsigned int sectors;
+	int cpu;
 
 	if (mddev == NULL || mddev->pers == NULL
 	    || !mddev->ready) {
@@ -284,7 +285,10 @@ static void md_make_request(struct request_queue *q, struct bio *bio)
 	sectors = bio_sectors(bio);
 	mddev->pers->make_request(mddev, bio);
 
-	generic_start_io_acct(rw, sectors, &mddev->gendisk->part0);
+	cpu = part_stat_lock();
+	part_stat_inc(cpu, &mddev->gendisk->part0, ios[rw]);
+	part_stat_add(cpu, &mddev->gendisk->part0, sectors[rw], sectors);
+	part_stat_unlock();
 
 	if (atomic_dec_and_test(&mddev->active_io) && mddev->suspended)
 		wake_up(&mddev->sb_wait);

drivers/md/raid0.c

@@ -313,7 +313,7 @@ static struct strip_zone *find_zone(struct r0conf *conf,
 
 /*
  * remaps the bio to the target device. we separate two flows.
- * power 2 flow and a general flow for the sake of perfromance
+ * power 2 flow and a general flow for the sake of performance
 */
 static struct md_rdev *map_sector(struct mddev *mddev, struct strip_zone *zone,
 				sector_t sector, sector_t *sector_offset)
@@ -524,6 +524,7 @@ static void raid0_make_request(struct mddev *mddev, struct bio *bio)
 			split = bio;
 		}
 
+		sector = bio->bi_iter.bi_sector;
 		zone = find_zone(mddev->private, &sector);
 		tmp_dev = map_sector(mddev, zone, sector, &sector);
 		split->bi_bdev = tmp_dev->bdev;