Hi,
  here is a revised version of my previous patch titled:
   [PATCH/RFC] core/nfsd: allow kernel threads to use task_work.

  There are now two patches - one that changes core code to allow nfsd
  to handle its own __dput calls, and one to make various changes to
  nfsd.
 
  It would probably make sense for the first patch to land through the
  VFS tree, and the second to follow through the NFSD tree, maybe after the relevant rc1 ??

  Details of the problem and explanation of the solution are in the individual patches.
  Thanks for all the review and suggestions.

NeilBrown

 [PATCH 1/2] Allow a kthread to declare that it calls task_work_run()
 [PATCH 2/2] nfsd: Don't leave work of closing files to a work queue.