Re: [PATCH v5 0/3] Initial NFS client support for RWF_DONTCACHE

[Trond Myklebust <trondmy@kernel.org>]

Hi Andrew,

On Tue, 2025-09-09 at 21:53 -0400, Trond Myklebust wrote:
> From: Trond Myklebust <trond.myklebust@hammerspace.com>
> 
> 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
> v4:
>  - Replace filemap_end_dropbehind_write() with folio_end_dropbehind()
>  - Add a helper to replace folio_end_writeback with an equivalent
> that
>    does not attempt to interpret the dropbehind flag
>  - Keep the folio dropbehind flag set until the NFS client is ready
> to
>    call folio_end_dropbehind.
>  - Don't try to do a read-modify-write in nfs_write_begin() if the
> folio
>    has the dropbehind flag set.
> v5:
>  - Change helper function export types to EXPORT_SYMBOL_GPL
> 
> Trond Myklebust (3):
>   filemap: Add a helper for filesystems implementing dropbehind
>   filemap: Add a version of folio_end_writeback that ignores
> dropbehind
>   NFS: Enable use of the RWF_DONTCACHE flag on the NFS client
> 
>  fs/nfs/file.c           |  9 +++++----
>  fs/nfs/nfs4file.c       |  1 +
>  fs/nfs/write.c          |  4 +++-
>  include/linux/pagemap.h |  2 ++
>  mm/filemap.c            | 34 ++++++++++++++++++++++++++--------
>  5 files changed, 37 insertions(+), 13 deletions(-)

Since the above series has already done the rounds in the linux-nfs and
linux-fsdevel mailing lists, could you please ask you to shepherd it in
to the 6.18 merge window? As you can see above the larger set of
changes are to mm/filemap.c rather than being NFS specific.

Cheers
 Trond

-- 
Trond Myklebust
Linux NFS client maintainer, Hammerspace
trondmy@kernel.org, trond.myklebust@hammerspace.com