[PATCH v3 0/2] Initial NFS client support for RWF_DONTCACHE

[Trond Myklebust <trondmy@kernel.org>]

From: Trond Myklebust <trond.myklebust@hammerspace.com>

The following patch set attempts to add support for the RWF_DONTCACHE
flag in preadv2() and pwritev2() on NFS filesystems.

The main issue is allowing support on 2 stage writes (i.e. unstable
WRITE followed by a COMMIT) since those don't follow the current
assumption that the 'dropbehind' flag can be fulfilled as soon as the
writeback lock is dropped.

v2:
 - Make use of the new iocb parameter for nfs_write_begin()
v3:
 - Set/clear PG_DROPBEHIND on the head of the nfs_page group
 - Simplify helper folio_end_dropbehind

Trond Myklebust (2):
  filemap: Add a helper for filesystems implementing dropbehind
  NFS: Enable the RWF_DONTCACHE flag for the NFS client

 fs/nfs/file.c            |  6 ++----
 fs/nfs/nfs4file.c        |  1 +
 fs/nfs/write.c           | 20 +++++++++++++++++---
 include/linux/nfs_page.h |  1 +
 include/linux/pagemap.h  |  1 +
 mm/filemap.c             | 11 +++++++++++
 6 files changed, 33 insertions(+), 7 deletions(-)

-- 
2.50.1