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, 1 insertions, 1 deletions

diff --git a/drivers/scsi/sr.c b/drivers/scsi/sr.c
index 27f5bfd1def3..8dbe3798d5fd 100644
--- a/drivers/scsi/sr.c
+++ b/drivers/scsi/sr.c
@@ -878,7 +878,7 @@ static void sr_kref_release(struct kref *kref)
         struct gendisk *disk = cd->disk;
 
         spin_lock(&sr_index_lock);
-        clear_bit(disk->first_minor, sr_index_bits);
+        clear_bit(MINOR(disk_devt(disk)), sr_index_bits);
         spin_unlock(&sr_index_lock);
 
         unregister_cdrom(&cd->cdi);