linux-kernel - Re: [PATCH v3 17/23] docs: fs: locks.rst: update comment about mandatory file locking

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Date:   Tue, 19 Oct 2021 06:47:41 -0400
From:   Jeff Layton <jlayton@...nel.org>
To:     Mauro Carvalho Chehab <mchehab+huawei@...nel.org>,
        Linux Doc Mailing List <linux-doc@...r.kernel.org>,
        Jonathan Corbet <corbet@....net>
Cc:     linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 17/23] docs: fs: locks.rst: update comment about
 mandatory file locking

On Tue, 2021-10-19 at 09:04 +0100, Mauro Carvalho Chehab wrote:
> The mandatory file locking got removed due to its problems, but
> the fs locks documentation still points to it.
> 
> Update the text there, informing that it was removed on Kernel
> 5.14.
> 
> Fixes: f7e33bdbd6d1 ("fs: remove mandatory file locking support")
> Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
> ---
> 
> To mailbombing on a large number of people, only mailing lists were C/C on the cover.
> See [PATCH v3 00/23] at: https://lore.kernel.org/all/cover.1634630485.git.mchehab+huawei@kernel.org/
> 
>  Documentation/filesystems/locks.rst | 17 +++++------------
>  1 file changed, 5 insertions(+), 12 deletions(-)
> 
> diff --git a/Documentation/filesystems/locks.rst b/Documentation/filesystems/locks.rst
> index c5ae858b1aac..26429317dbbc 100644
> --- a/Documentation/filesystems/locks.rst
> +++ b/Documentation/filesystems/locks.rst
> @@ -57,16 +57,9 @@ fcntl(), with all the problems that implies.
>  1.3 Mandatory Locking As A Mount Option
>  ---------------------------------------
>  
> -Mandatory locking, as described in
> -'Documentation/filesystems/mandatory-locking.rst' was prior to this release a
> -general configuration option that was valid for all mounted filesystems.  This
> -had a number of inherent dangers, not the least of which was the ability to
> -freeze an NFS server by asking it to read a file for which a mandatory lock
> -existed.
> -
> -From this release of the kernel, mandatory locking can be turned on and off
> -on a per-filesystem basis, using the mount options 'mand' and 'nomand'.
> -The default is to disallow mandatory locking. The intention is that
> -mandatory locking only be enabled on a local filesystem as the specific need
> -arises.
> +Mandatory locking was prior to this release a general configuration option
> +that was valid for all mounted filesystems.  This had a number of inherent
> +dangers, not the least of which was the ability to freeze an NFS server by
> +asking it to read a file for which a mandatory lock existed.
>  
> +Such option was dropped in Kernel v5.14.

Looks good. I'll plan to pick this up and (add a Reported-by for Jon,
who noted this a few days ago).

-- 
Jeff Layton <jlayton@...nel.org>