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From: Trond Myklebust <trondmy@hammerspace.com>
To: "linux-nfs@vger.kernel.org" <linux-nfs@vger.kernel.org>,
	"aglo@umich.edu" <aglo@umich.edu>
Subject: Re: client's caching of server-side capabilities
Date: Mon, 28 Jun 2021 22:06:18 +0000	[thread overview]
Message-ID: <81154dc28d528402bf5e090a81e6892c7abc431c.camel@hammerspace.com> (raw)
In-Reply-To: <CAN-5tyEuB5C9u+xZ5L47fSQ9cwZnsbhJuBs+gybU2A-jzAkfog@mail.gmail.com>

On Mon, 2021-06-28 at 16:23 -0400, Olga Kornievskaia wrote:
> Hi folks,
> 
> I have a general question of why the client doesn't throw away the
> cached server's capabilities on server reboot. Say a client mounted a
> server when the server didn't support security_labels, then the
> server
> was rebooted and support was enabled. Client re-establishes its
> clientid/session, recovers state, but assumes all the old
> capabilities
> apply. A remount is required to clear old/find new capabilities. The
> opposite is true that a capability could be removed (but I'm assuming
> that's a less practical example).
> 
> I'm curious what are the problems of clearing server capabilities and
> rediscovering them on reboot? Is it because a local filesystem could
> never have its attributes changed and thus a network file system
> can't
> either?
> 
> Thank you.

In my opinion, the client should aim for the absolute minimum overhead
on a server reboot. The goal should be to recover state and get I/O
started again as quickly as possible. Detection of new features, etc
can wait until the client needs to restart.

-- 
Trond Myklebust
Linux NFS client maintainer, Hammerspace
trond.myklebust@hammerspace.com



  reply	other threads:[~2021-06-28 22:06 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-28 20:23 client's caching of server-side capabilities Olga Kornievskaia
2021-06-28 22:06 ` Trond Myklebust [this message]
2021-06-29 12:58   ` Chuck Lever III
2021-06-29 13:48     ` Olga Kornievskaia
2021-06-29 13:51       ` Chuck Lever III
2021-06-30 15:22         ` J. Bruce Fields
2021-06-30 15:52           ` Trond Myklebust
2021-06-30 16:48           ` Olga Kornievskaia
2021-06-30 17:11             ` Trond Myklebust
2021-06-29 13:41   ` Olga Kornievskaia
2021-06-29 16:12     ` Olga Kornievskaia
2021-06-29 17:05       ` Trond Myklebust

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