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From:   "Benjamin Coddington" <bcodding@redhat.com>
To:     "Olga Kornievskaia" <olga.kornievskaia@gmail.com>
Cc:     "Dan Aloni" <dan@kernelim.com>,
        "Trond Myklebust" <trond.myklebust@hammerspace.com>,
        "Anna Schumaker" <anna.schumaker@netapp.com>,
        linux-nfs <linux-nfs@vger.kernel.org>
Subject: Re: [PATCH v3 09/13] sunrpc: add a symlink from rpc-client directory
 to the xprt_switch
Date:   Fri, 14 May 2021 11:58:22 -0400
Message-ID: <3E3B831C-BCC3-462D-84D7-6D09E8EEDFDF@redhat.com>
In-Reply-To: <CAN-5tyF_x+6vtyEtfkUNTj1-MWqTg0RoRJvofh5nbRq-miot8g@mail.gmail.com>
References: <20210426171947.99233-1-olga.kornievskaia@gmail.com>
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 <CAN-5tyGe32FEeK0+bnMU16zu5Y6RkVqEey4G3VocEtx8vSQwiw@mail.gmail.com>
 <E841CE1C-041E-4E9A-B14F-925CC0A08581@redhat.com>
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On 14 May 2021, at 10:16, Olga Kornievskaia wrote:
> On Fri, May 14, 2021 at 6:17 AM Benjamin Coddington 
> <bcodding@redhat.com> wrote:
>> The information isn't lost, as the symlink points to the specific 
>> switch.
>> Not using a number in the symlink name informs that there will only 
>> be one
>> switch for each client and makes it more deterministic for users and
>> software to navigate.
>
> What will be lost is that when you look at the xprt_switches directory
> and see switch-1... switch-10 subdirectory, there is no way to tell
> which rpc client uses which switch. Because each client-1 directory
> will only have an entry saying "switch".
>
> Anyway, I submitted the new version but I think it's not as good as
> the original.

Hmm, ok - will we ever need to traverse objects in that direction 
though?
I'm thinking that operations on xprts/rpcs will always start from a 
mount
perspective from the admin, but really the root object is struct 
nfs_server,
or bdi.  I'm thinking of something like:

     /sys/fs/nfs/<bdi>/rpc_clnt -> ../../net/sunrpc/clnt-0
     /sys/fs/nfs/<bdi>/volumes
     ...

I suppose though you could have something monitoring the xprts, and upon
finding a particular state would want to navigate back up to see what 
client
is affected.  At that point you'd have to read all the symlinks for all 
the
rpc_clients.

Ben