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From:   "Benjamin Coddington" <bcodding@redhat.com>
To:     "Dan Aloni" <dan@kernelim.com>
Cc:     "Anna Schumaker" <schumaker.anna@gmail.com>,
        "Chuck Lever" <chuck.lever@oracle.com>,
        "Linux NFS Mailing List" <linux-nfs@vger.kernel.org>
Subject: Re: [PATCH v2 0/5] SUNRPC: Create sysfs files for changing IP
Date:   Tue, 02 Feb 2021 14:49:38 -0500
Message-ID: <8A686173-B3FF-4122-990C-6E8795D35161@redhat.com>
In-Reply-To: <20210202192417.ug32gmuc2uciik54@gmail.com>
References: <20210202184244.288898-1-Anna.Schumaker@Netapp.com>
 <75F3F315-84AA-41A0-A43A-C531042A9C47@oracle.com>
 <CAFX2JfktYGe4vDtXogFHurdyz4TJx5APj9pb-J5HmsDGC99kaA@mail.gmail.com>
 <20210202192417.ug32gmuc2uciik54@gmail.com>
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On 2 Feb 2021, at 14:24, Dan Aloni wrote:

> On Tue, Feb 02, 2021 at 01:52:10PM -0500, Anna Schumaker wrote:
>> You're welcome! I'll try to remember to CC him on future versions
>> On Tue, Feb 2, 2021 at 1:51 PM Chuck Lever <chuck.lever@oracle.com> wrote:
>>>
>>> I want to ensure Dan is aware of this work. Thanks for posting, Anna!
>
> Thanks Anna and Chuck. I'm accessing and monitoring the mailing list via
> NNTP and I'm also on #linux-nfs for chatting (da-x).
>
> I see srcaddr was already discussed, so the patches I'm planning to send
> next will be based on the latest version of your patchset and concern
> multipath.
>
> What I'm going for is the following:
>
> - Expose transports that are reachable from xprtmultipath. Each in its
>   own sub-directory, with an interface and status representation similar
>   to the top directory.
> - A way to add/remove transports.
> - Inspiration for coding this is various other things in the kernel that
>   use configfs, perhaps it can be used here too.
>
> Also, what do you think would be a straightforward way for a userspace
> program to find what sunrpc client id serves a mountpoint? If we add an
> ioctl for the mountdir AFAIK it would be the first one that the NFS
> client supports, so I wonder if there's a better interface that can work
> for that.

I'm a fan of adding an ioctl interface for userspace, but I think we'd
better avoid using NFS itself because it would be nice to someday implement
an NFS "shutdown" for non-responsive servers, but sending any ioctl to the
mountpoint could revalidate it, and we'd hang on the GETATTR.

Maybe we can figure out a way to expose the superblock via sysfs for each
mount.

Ben