Pull DAX updates part two from Darrick Wong:
 "This time around, we're hoisting the DONTCACHE flag from XFS into the
  VFS so that we can make the incore DAX mode changes become effective
  sooner.

  We can't change the file data access mode on a live inode because we
  don't have a safe way to change the file ops pointers. The incore
  state change becomes effective at inode loading time, which can happen
  if the inode is evicted. Therefore, we're making it so that
  filesystems can ask the VFS to evict the inode as soon as the last
  holder drops.

  The per-fs changes to make this call this will be in subsequent pull
  requests from Ted and myself.

  Summary:

   - Introduce DONTCACHE flags for dentries and inodes. This hint will
     cause the VFS to drop the associated objects immediately after the
     last put, so that we can change the file access mode (DAX or page
     cache) on the fly"

* tag 'vfs-5.8-merge-2' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux:
  fs: Introduce DCACHE_DONTCACHE
  fs: Lift XFS_IDONTCACHE to the VFS layer