block: allow disk to have extended device number

Now that disk and partition handlings are mostly unified, it's easy to
allow disk to have extended device number.  This patch makes
add_disk() use extended device number if disk->minors is zero.  Both
sd and ide-disk are updated to use this.

* sd_format_disk_name() is implemented which can generically determine
  the drive name.  This removes disk number restriction stemming from
  limited device names.

* If sd index goes over SD_MAX_DISKS (which can be increased now BTW),
  sd simply doesn't initialize minors letting block layer choose
  extended device number.

* If CONFIG_DEBUG_EXT_DEVT is set, both sd and ide-disk always set
  minors to 0 and use extended device numbers.

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

1 files changed, 1 insertions, 0 deletions

diff --git a/fs/partitions/check.c b/fs/partitions/check.c
index 772b2ed8d239..0e411603fdf5 100644
--- a/fs/partitions/check.c
+++ b/fs/partitions/check.c
@@ -593,6 +593,7 @@ void del_gendisk(struct gendisk *disk)
         disk_part_iter_exit(&piter);
 
         invalidate_partition(disk, 0);
+        blk_free_devt(disk_to_dev(disk)->devt);
         set_capacity(disk, 0);
         disk->flags &= ~GENHD_FL_UP;
         unlink_gendisk(disk);