Merge tag 'pull-set_blocksize' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull vfs blocksize updates from Al Viro:
 "This gets rid of bogus set_blocksize() uses, switches it over
  to be based on a 'struct file *' and verifies that the caller
  has the device opened exclusively"

* tag 'pull-set_blocksize' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  make set_blocksize() fail unless block device is opened exclusive
  set_blocksize(): switch to passing struct file *
  btrfs_get_bdev_and_sb(): call set_blocksize() only for exclusive opens
  swsusp: don't bother with setting block size
  zram: don't bother with reopening - just use O_EXCL for open
  swapon(2): open swap with O_EXCL
  swapon(2)/swapoff(2): don't bother with block size
  pktcdvd: sort set_blocksize() calls out
  bcache_register(): don't bother with set_blocksize()

diff --cc Documentation/filesystems/porting.rst
Simple merge

diff --cc block/bdev.c
Simple merge

diff --cc block/ioctl.c
Simple merge

diff --cc drivers/block/zram/zram_drv.c
Simple merge

diff --cc drivers/md/bcache/super.c
Simple merge

diff --cc fs/btrfs/volumes.c
Simple merge

diff --cc fs/ext4/super.c
Simple merge

diff --cc fs/xfs/xfs_buf.c
Simple merge

diff --cc include/linux/blkdev.h
Simple merge

diff --cc include/linux/swap.h
Simple merge

diff --cc mm/swapfile.c
Simple merge