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Date:   Mon, 15 Mar 2021 15:18:39 -0400
From:   "J. Bruce Fields" <bfields@redhat.com>
To:     Trond Myklebust <trondmy@hammerspace.com>
Cc:     "trondmy@kernel.org" <trondmy@kernel.org>,
        "linux-nfs@vger.kernel.org" <linux-nfs@vger.kernel.org>,
        "chuck.lever@oracle.com" <chuck.lever@oracle.com>
Subject: Re: [PATCH] nfsd: Ensure knfsd shuts down when the "nfsd" pseudofs
 is unmounted
Message-ID: <YE+zD9bM6/ki0XgS@pick.fieldses.org>
References: <20210313210847.569041-1-trondmy@kernel.org>
 <YE9zQQhyfHmLLVVJ@pick.fieldses.org>
 <51c84f27cf5c950c63ef2be570fd647d93d80036.camel@hammerspace.com>
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On Mon, Mar 15, 2021 at 04:04:05PM +0000, Trond Myklebust wrote:
> On Mon, 2021-03-15 at 10:46 -0400, J. Bruce Fields wrote:
> > On Sat, Mar 13, 2021 at 04:08:47PM -0500, trondmy@kernel.org?wrote:
> > > From: Trond Myklebust <trond.myklebust@hammerspace.com>
> > > 
> > > In order to ensure that knfsd threads don't linger once the nfsd
> > > pseudofs is unmounted (e.g. when the container is killed) we let
> > > nfsd_umount() shut down those threads and wait for them to exit.
> > > 
> > > This also should ensure that we don't need to do a kernel mount of
> > > the pseudofs, since the thread lifetime is now limited by the
> > > lifetime of the filesystem.
> > 
> > The nfsd filesystem is per-container, and threads are global, so I
> > don't
> > understand how this works.
> > 
> 
> The knfsd threads are not global.
> 
> They are assigned at creation time to a struct svc_serv, which is a
> per-container object. As you say above, all the control structures in
> the nfsd filesystem are per-container.

(Looks.)  And it's been that way from the start.  I don't know why I
thought otherwise.  Thanks!

> Without this failsafe that shuts down those threads when the container
> is killed, then you end up with orphaned threads. This is a real
> problem when docker crashes and gets restarted (or if you do a 'kill -
> 9' on the knfsd container's init process).

Makes sense, thanks again!

--b.