block: don't depend on consecutive minor space

* Implement disk_devt() and part_devt() and use them to directly
  access devt instead of computing it from ->major and ->first_minor.

  Note that all references to ->major and ->first_minor outside of
  block layer is used to determine devt of the disk (the part0) and as
  ->major and ->first_minor will continue to represent devt for the
  disk, converting these users aren't strictly necessary.  However,
  convert them for consistency.

* Implement disk_max_parts() to avoid directly deferencing
  genhd->minors.

* Update bdget_disk() such that it doesn't assume consecutive minor
  space.

* Move devt computation from register_disk() to add_disk() and make it
  the only one (all other usages use the initially determined value).

These changes clean up the code and will help disk->part dereference
fix and extended block device numbers.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/drivers/md/dm-stripe.c b/drivers/md/dm-stripe.c
index 4de90ab3968b..b745d8ac625b 100644
--- a/drivers/md/dm-stripe.c
+++ b/drivers/md/dm-stripe.c
@@ -284,8 +284,8 @@ static int stripe_end_io(struct dm_target *ti, struct bio *bio,
 
         memset(major_minor, 0, sizeof(major_minor));
         sprintf(major_minor, "%d:%d",
-                bio->bi_bdev->bd_disk->major,
-                bio->bi_bdev->bd_disk->first_minor);
+                MAJOR(disk_devt(bio->bi_bdev->bd_disk)),
+                MINOR(disk_devt(bio->bi_bdev->bd_disk)));
 
         /*
          * Test to see which stripe drive triggered the event