Message-ID: <4CA2BCBB.4000008@suse.de>
Date: Wed, 29 Sep 2010 09:42:43 +0530
From: Suresh Jayaraman <sjayaraman@suse.de>
To: steved@redhat.com
Cc: Linux NFS mailing list <linux-nfs@vger.kernel.org>
Subject: Re: [PATCH] nfs(5): document new local_lock option
References: <4C9BA266.1040102@suse.de>
In-Reply-To: <4C9BA266.1040102@suse.de>
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Sender: linux-nfs-owner@vger.kernel.org
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Steve,

I see this patch is missing in the recent release. Do you see any
problems with this? (For the record, the local_lock kernel patches are
already in Trond nfs-for-2.6.37 tree).

Thanks,

On 09/24/2010 12:24 AM, Suresh Jayaraman wrote:
> Kernel 2.6.37 would most likely add a new mount option: local_lock.
> Document the new option in the nfs(5) man page.
> 
> Signed-off-by: Suresh Jayaraman <sjayaraman@suse.de>
> ---
>  utils/mount/nfs.man |   44 ++++++++++++++++++++++++++++++++++++++++++++
>  1 files changed, 44 insertions(+), 0 deletions(-)
> 
> diff --git a/utils/mount/nfs.man b/utils/mount/nfs.man
> index 55d4b55..d2a4c5f 100644
> --- a/utils/mount/nfs.man
> +++ b/utils/mount/nfs.man
> @@ -717,6 +717,50 @@ If this option is not specified, the NFS client uses READDIRPLUS requests
>  on NFS version 3 mounts to read small directories.
>  Some applications perform better if the client uses only READDIR requests
>  for all directories.
> +.TP 1.5i
> +.BR local_lock= mechanism
> +Specifies whether to use local locking for any or both of the flock and the
> +POSIX locking mechanisms.
> +.I mechanism
> +can be one of
> +.BR all ,
> +.BR flock ,
> +.BR posix ,
> +or
> +.BR none .
> +This option is supported in kernels 2.6.37 and later.
> +.IP
> +The Linux NFS client provides a way to make locks local. This means, the
> +applications can lock files, but such locks provide exclusion only against
> +other applications running on the same client. Remote applications are not
> +affected by these locks.
> +.IP
> +If this option is not specified, or if
> +.B none
> +is specified, the client assumes that the locks are not local.
> +.IP
> +If
> +.BR all
> +is specified, the client assumes that both flock and POSIX locks are local.
> +.IP
> +If
> +.BR flock
> +is specified, the client assumes that only flock locks are local and uses
> +NLM sideband protocol to lock files when POSIX locks are used.
> +.IP
> +If
> +.BR posix
> +is specified, the client assumes that POSIX locks are local and uses NLM
> +sideband protocol to lock files when flock locks are used.
> +.IP
> +To support legacy flock behavior similar to that of NFS clients < 2.6.12, use
> +'local_lock=flock'. This option is required when exporting NFS mounts via
> +Samba as Samba maps Windows share mode locks as flock. Since NFS clients >
> +2.6.12 implement flock by emulating POSIX locks, this will result in
> +conflicting locks.
> +.IP
> +NOTE: When used together, the 'local_lock' mount option will be overridden
> +by 'nolock'/'lock' mount option.
>  .SS "Options for version 4 only"
>  Use these options, along with the options in the first subsection above,
>  for NFSv4 only. They will be ignored with older versions.
> --
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-- 
Suresh Jayaraman