md: Removing num_sector and replacing start_sector with end_sector

Remove num_sectors from dev_info and replace start_sector with
end_sector.  This makes a lot of comparisons much simpler.

Signed-off-by: Sandeep K Sinha <sandeepksinha@gmail.com>
Signed-off-by: NeilBrown <neilb@suse.de>

2 files changed, 19 insertions, 21 deletions

diff --git a/drivers/md/linear.c b/drivers/md/linear.c
index 92bcd3dd52cc..529a3d37e3fe 100644
--- a/drivers/md/linear.c
+++ b/drivers/md/linear.c
@@ -32,7 +32,7 @@ static inline dev_info_t *which_dev(mddev_t *mddev, sector_t sector)
 
         hash = conf->disks;
 
-        while (sector >= hash->num_sectors + hash->start_sector)
+        while (sector >= hash->end_sector)
                 hash++;
         return hash;
 }
@@ -55,7 +55,7 @@ static int linear_mergeable_bvec(struct request_queue *q,
         sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev);
 
         dev0 = which_dev(mddev, sector);
-        maxsectors = dev0->num_sectors - (sector - dev0->start_sector);
+        maxsectors = dev0->end_sector - sector;
 
         if (maxsectors < bio_sectors)
                 maxsectors = 0;
@@ -141,10 +141,9 @@ static linear_conf_t *linear_conf(mddev_t *mddev, int raid_disks)
                     queue_max_sectors(mddev->queue) > (PAGE_SIZE>>9))
                         blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9);
 
-                disk->num_sectors = rdev->sectors;
                 conf->array_sectors += rdev->sectors;
-
                 cnt++;
+
         }
         if (cnt != raid_disks) {
                 printk("linear: not enough drives present. Aborting!\n");
@@ -154,11 +153,12 @@ static linear_conf_t *linear_conf(mddev_t *mddev, int raid_disks)
         /*
          * Here we calculate the device offsets.
          */
-        conf->disks[0].start_sector = 0;
+        conf->disks[0].end_sector = conf->disks[0].rdev->sectors;
+
         for (i = 1; i < raid_disks; i++)
-                conf->disks[i].start_sector =
-                        conf->disks[i-1].start_sector +
-                        conf->disks[i-1].num_sectors;
+                conf->disks[i].end_sector =
+                        conf->disks[i-1].end_sector +
+                        conf->disks[i].rdev->sectors;
 
         return conf;
 
@@ -235,6 +235,7 @@ static int linear_make_request (struct request_queue *q, struct bio *bio)
         const int rw = bio_data_dir(bio);
         mddev_t *mddev = q->queuedata;
         dev_info_t *tmp_dev;
+        sector_t start_sector;
         int cpu;
 
         if (unlikely(bio_barrier(bio))) {
@@ -249,32 +250,30 @@ static int linear_make_request (struct request_queue *q, struct bio *bio)
         part_stat_unlock();
 
         tmp_dev = which_dev(mddev, bio->bi_sector);
-    
-        if (unlikely(bio->bi_sector >= (tmp_dev->num_sectors +
-                                        tmp_dev->start_sector)
-                     || (bio->bi_sector <
-                         tmp_dev->start_sector))) {
+        start_sector = tmp_dev->end_sector - tmp_dev->rdev->sectors;
+
+        if (unlikely(bio->bi_sector >= (tmp_dev->end_sector)
+                     || (bio->bi_sector < start_sector))) {
                 char b[BDEVNAME_SIZE];
 
                 printk("linear_make_request: Sector %llu out of bounds on "
                         "dev %s: %llu sectors, offset %llu\n",
                         (unsigned long long)bio->bi_sector,
                         bdevname(tmp_dev->rdev->bdev, b),
-                        (unsigned long long)tmp_dev->num_sectors,
-                        (unsigned long long)tmp_dev->start_sector);
+                        (unsigned long long)tmp_dev->rdev->sectors,
+                        (unsigned long long)start_sector);
                 bio_io_error(bio);
                 return 0;
         }
         if (unlikely(bio->bi_sector + (bio->bi_size >> 9) >
-                     tmp_dev->start_sector + tmp_dev->num_sectors)) {
+                     tmp_dev->end_sector)) {
                 /* This bio crosses a device boundary, so we have to
                  * split it.
                  */
                 struct bio_pair *bp;
 
                 bp = bio_split(bio,
-                               tmp_dev->start_sector + tmp_dev->num_sectors
-                               - bio->bi_sector);
+                               tmp_dev->end_sector - bio->bi_sector);
 
                 if (linear_make_request(q, &bp->bio1))
                         generic_make_request(&bp->bio1);
@@ -285,7 +284,7 @@ static int linear_make_request (struct request_queue *q, struct bio *bio)
         }
                     
         bio->bi_bdev = tmp_dev->rdev->bdev;
-        bio->bi_sector = bio->bi_sector - tmp_dev->start_sector
+        bio->bi_sector = bio->bi_sector - start_sector
                 + tmp_dev->rdev->data_offset;
 
         return 1;
diff --git a/drivers/md/linear.h b/drivers/md/linear.h
index 721a878403d1..599e5c1bbb01 100644
--- a/drivers/md/linear.h
+++ b/drivers/md/linear.h
@@ -3,8 +3,7 @@
 
 struct dev_info {
         mdk_rdev_t      *rdev;
-        sector_t        num_sectors;
-        sector_t        start_sector;
+        sector_t        end_sector;
 };
 
 typedef struct dev_info dev_info_t;