md: raid0: remove ->dev pointer from strip_zone structure

If we treat conf->devlist more like a 2 dimensional array,
we can get the devlist for a particular zone simply by indexing
that array, so we don't need to store the pointers to subarrays
in strip_zone.  This makes strip_zone smaller and so (hopefully)
searches faster.
Signed-of-by: NeilBrown <neilb@suse.de>

drivers/md/raid0.c

@@ -27,7 +27,7 @@ static void raid0_unplug(struct request_queue *q)
 {
 	mddev_t *mddev = q->queuedata;
 	raid0_conf_t *conf = mddev_to_conf(mddev);
-	mdk_rdev_t **devlist = conf->strip_zone[0].dev;
+	mdk_rdev_t **devlist = conf->devlist;
 	int i;
 
 	for (i=0; i<mddev->raid_disks; i++) {
@@ -41,7 +41,7 @@ static int raid0_congested(void *data, int bits)
 {
 	mddev_t *mddev = data;
 	raid0_conf_t *conf = mddev_to_conf(mddev);
-	mdk_rdev_t **devlist = conf->strip_zone[0].dev;
+	mdk_rdev_t **devlist = conf->devlist;
 	int i, ret = 0;
 
 	for (i = 0; i < mddev->raid_disks && !ret ; i++) {
@@ -56,7 +56,7 @@ static int create_strip_zones(mddev_t *mddev)
 {
 	int i, c, j, err;
 	sector_t curr_zone_end, sectors;
-	mdk_rdev_t *smallest, *rdev1, *rdev2, *rdev;
+	mdk_rdev_t *smallest, *rdev1, *rdev2, *rdev, **dev;
 	struct strip_zone *zone;
 	int cnt;
 	char b[BDEVNAME_SIZE];
@@ -115,7 +115,7 @@ static int create_strip_zones(mddev_t *mddev)
 	zone = &conf->strip_zone[0];
 	cnt = 0;
 	smallest = NULL;
-	zone->dev = conf->devlist;
+	dev = conf->devlist;
 	err = -EINVAL;
 	list_for_each_entry(rdev1, &mddev->disks, same_set) {
 		int j = rdev1->raid_disk;
@@ -125,12 +125,12 @@ static int create_strip_zones(mddev_t *mddev)
 				"aborting!\n", j);
 			goto abort;
 		}
-		if (zone->dev[j]) {
+		if (dev[j]) {
 			printk(KERN_ERR "raid0: multiple devices for %d - "
 				"aborting!\n", j);
 			goto abort;
 		}
-		zone->dev[j] = rdev1;
+		dev[j] = rdev1;
 
 		blk_queue_stack_limits(mddev->queue,
 				       rdev1->bdev->bd_disk->queue);
@@ -161,7 +161,7 @@ static int create_strip_zones(mddev_t *mddev)
 	for (i = 1; i < conf->nr_strip_zones; i++)
 	{
 		zone = conf->strip_zone + i;
-		zone->dev = conf->strip_zone[i-1].dev + mddev->raid_disks;
+		dev = conf->devlist + i * mddev->raid_disks;
 
 		printk(KERN_INFO "raid0: zone %d\n", i);
 		zone->dev_start = smallest->sectors;
@@ -170,7 +170,7 @@ static int create_strip_zones(mddev_t *mddev)
 
 		for (j=0; j<cnt; j++) {
 			char b[BDEVNAME_SIZE];
-			rdev = conf->strip_zone[0].dev[j];
+			rdev = conf->devlist[j];
 			printk(KERN_INFO "raid0: checking %s ...",
 				bdevname(rdev->bdev, b));
 			if (rdev->sectors <= zone->dev_start) {
@@ -178,7 +178,7 @@ static int create_strip_zones(mddev_t *mddev)
 				continue;
 			}
 			printk(KERN_INFO " contained as device %d\n", c);
-			zone->dev[c] = rdev;
+			dev[c] = rdev;
 			c++;
 			if (!smallest || rdev->sectors < smallest->sectors) {
 				smallest = rdev;
@@ -383,7 +383,8 @@ static int raid0_make_request (struct request_queue *q, struct bio *bio)
 		chunk = x;
 
 		x = sector >> chunksect_bits;
-		tmp_dev = zone->dev[sector_div(x, zone->nb_dev)];
+		tmp_dev = conf->devlist[(zone - conf->strip_zone)*mddev->raid_disks
+					+ sector_div(x, zone->nb_dev)];
 	}
 	rsect = (chunk << chunksect_bits) + zone->dev_start + sect_in_chunk;
  

drivers/md/raid0.h

@@ -6,7 +6,6 @@ struct strip_zone
 	sector_t zone_end;	/* Start of the next zone (in sectors) */
 	sector_t dev_start;	/* Zone offset in real dev (in sectors) */
 	int nb_dev;		/* # of devices attached to the zone */
-	mdk_rdev_t **dev;	/* Devices attached to the zone */
 };
 
 struct raid0_private_data