Merge branch 'for-4.1/drivers' of git://git.kernel.dk/linux-block

Pull block driver updates from Jens Axboe:
 "This is the block driver pull request for 4.1.  As with the core bits,
  this is a relatively slow round.  This pull request contains:

   - Various fixes and cleanups for NVMe, from Alexey Khoroshilov, Chong
     Yuan, myself, Keith Busch, and Murali Iyer.

   - Documentation and code cleanups for nbd from Markus Pargmann.

   - Change of brd maintainer to me, from Ross Zwisler.  At least the
     email doesn't bounce anymore then.

   - Two xen-blkback fixes from Tao Chen"

* 'for-4.1/drivers' of git://git.kernel.dk/linux-block: (23 commits)
  NVMe: Meta data handling through submit io ioctl
  NVMe: Add translation for block limits
  NVMe: Remove check for null
  NVMe: Fix error handling of class_create("nvme")
  xen-blkback: define pr_fmt macro to avoid the duplication of DRV_PFX
  xen-blkback: enlarge the array size of blkback name
  nbd: Return error pointer directly
  nbd: Return error code...