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Subject: Re: [PATCH 0/3] Add a mount option to support eager writes
To:     trondmy@kernel.org, Anna Schumaker <anna.schumaker@netapp.com>
Cc:     linux-nfs@vger.kernel.org
References: <20210212214949.4408-1-trondmy@kernel.org>
From:   Steve Dickson <SteveD@RedHat.com>
Message-ID: <d6d6c503-cdae-db31-45d4-e05fe46f0a2a@RedHat.com>
Date:   Sat, 13 Feb 2021 09:19:05 -0500
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Hey!

On 2/12/21 4:49 PM, trondmy@kernel.org wrote:
> From: Trond Myklebust <trond.myklebust@hammerspace.com>
> 
> The following patch series sets up a new mount option
> 'writes=lazy/eager/wait'. The mount option basically controls how the
> write() system call works.
> - writes=lazy is the default, and keeps the current behaviour
> - writes=eager means we send off the write immediately as an unstable
>   write to the server.
> - writes=wait means we send off the write as an unstable write, and then
>   wait for the reply.
> 
> The main motivator for this behaviour is that some applications expect
> write() to return ENOSPC. Setting writes=wait should satisfy those
> applications without taking the full overhead of a synchronous write.
> 
> writes=eager, on the other hand, can be useful for applications such as
> re-exporting NFS, since it would allow knfsd on the proxying server to
> immediately forward the writes to the original server.
> 
> Trond Myklebust (3):
>   NFS: 'flags' field should be unsigned in struct nfs_server
>   NFS: Add support for eager writes
>   NFS: Add mount options supporting eager writes
> 
>  fs/nfs/file.c             | 19 +++++++++++++++++--
>  fs/nfs/fs_context.c       | 33 +++++++++++++++++++++++++++++++++
>  fs/nfs/write.c            | 17 ++++++++++++-----
>  include/linux/nfs_fs_sb.h |  4 +++-
>  4 files changed, 65 insertions(+), 8 deletions(-)
> 
Shouldn't something be added to the nfs(5) man page 
as well as blurb added to /etc/nfsmount.conf file?

steved.