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/fs/block_dev.c b/fs/block_dev.c
index de0776cd7215..72e0a2887cb7 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -892,7 +892,7 @@ int check_disk_change(struct block_device *bdev)
 
         if (bdops->revalidate_disk)
                 bdops->revalidate_disk(bdev->bd_disk);
-        if (bdev->bd_disk->minors > 1)
+        if (disk_max_parts(bdev->bd_disk))
                 bdev->bd_invalidated = 1;
         return 1;
 }