From: Tycho Andersen <tycho@tycho.pizza>
To: Miklos Szeredi <miklos@szeredi.hu>,
Eric Biederman <ebiederm@xmission.com>
Cc: linux-kernel@vger.kernel.org, fuse-devel@lists.sourceforge.net,
"Serge E. Hallyn" <serge@hallyn.com>
Subject: Re: [PATCH] fuse: In fuse_flush only wait if someone wants the return code
Date: Mon, 19 Sep 2022 09:03:41 -0600 [thread overview]
Message-ID: <YyiEzbTDZ+g9iAas@tycho.pizza> (raw)
In-Reply-To: <20220901140647.1125079-1-tycho@tycho.pizza>
Hi Miklos,
On Thu, Sep 01, 2022 at 08:06:47AM -0600, Tycho Andersen wrote:
> From: "Eric W. Biederman" <ebiederm@xmission.com>
>
> In my very light testing this resolves a hang where a thread of the
> fuse server was accessing the fuse filesystem (the fuse server is
> serving up), when the fuse server is killed.
>
> The practical problem is that the fuse server file descriptor was
> being closed after the file descriptor into the fuse filesystem so
> that the fuse filesystem operations were being blocked for instead of
> being aborted. Simply skipping the unnecessary wait resolves this
> issue.
>
> This is just a proof of concept and someone should look to see if the
> fuse max_background limit could cause a problem with this approach.
>
> Additionally testing PF_EXITING is a very crude way to tell if someone
> wants the return code from the vfs flush operation. As such in the
> long run it probably makes sense to get some direct vfs support for
> knowing if flush needs to block until all of the flushing is complete
> and a status/return code can be returned.
>
> Unless I have missed something this is a generic optimization that can
> apply to many network filesystems.
>
> Al, vfs folks? (igrab/iput sorted so as not to be distractions).
>
> Perhaps a .flush_async method without a return code and a
> filp_close_async function without a return code to take advantage of
> this in the general sense.
>
> Waiting potentially indefinitely for user space in do_exit seems like a
> bad idea. Especially when all that the wait is for is to get a return
> code that will never be examined.
>
> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
> [tycho: small fixups for releasing fuse file + nocred flag]
> Signed-off-by: Tycho Andersen <tycho@tycho.pizza>
> Reported-by: Tycho Andersen <tycho@tycho.pizza>
> Tested-by: "Serge E. Hallyn" <serge@hallyn.com>
Any chance you're willing to take this patch? We're still seeing this
a lot and it would be great to get it fixed.
Thanks.
Tycho
next prev parent reply other threads:[~2022-09-19 15:04 UTC|newest]
Thread overview: 61+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-23 17:21 strange interaction between fuse + pidns Tycho Andersen
2022-06-23 21:55 ` Vivek Goyal
2022-06-23 23:41 ` Tycho Andersen
2022-06-24 17:36 ` Vivek Goyal
2022-07-11 10:35 ` Miklos Szeredi
2022-07-11 13:59 ` Miklos Szeredi
2022-07-11 20:25 ` Tycho Andersen
2022-07-11 21:37 ` Eric W. Biederman
2022-07-11 22:53 ` Tycho Andersen
2022-07-11 23:06 ` Eric W. Biederman
2022-07-12 13:43 ` Tycho Andersen
2022-07-12 14:34 ` Eric W. Biederman
2022-07-12 15:14 ` Tycho Andersen
2022-07-13 17:53 ` [PATCH] sched: __fatal_signal_pending() should also check PF_EXITING Tycho Andersen
2022-07-20 15:03 ` Serge E. Hallyn
2022-07-20 20:58 ` Tycho Andersen
2022-07-21 1:54 ` Serge E. Hallyn
2022-07-27 15:44 ` Tycho Andersen
2022-07-27 16:32 ` Eric W. Biederman
2022-07-27 17:55 ` Tycho Andersen
2022-07-28 18:48 ` Eric W. Biederman
2022-07-27 17:55 ` Oleg Nesterov
2022-07-27 18:18 ` Tycho Andersen
2022-07-27 19:19 ` Oleg Nesterov
2022-07-27 19:40 ` Tycho Andersen
2022-07-28 9:12 ` Oleg Nesterov
2022-07-28 21:20 ` Tycho Andersen
2022-07-29 5:04 ` Eric W. Biederman
2022-07-29 13:50 ` Tycho Andersen
2022-07-29 16:15 ` Eric W. Biederman
2022-07-29 16:48 ` Tycho Andersen
2022-07-29 17:40 ` [RFC][PATCH] fuse: In fuse_flush only wait if someone wants the return code Eric W. Biederman
2022-07-29 20:47 ` Oleg Nesterov
2022-07-30 0:15 ` Al Viro
2022-07-30 5:10 ` [RFC][PATCH v2] " Eric W. Biederman
2022-08-01 15:16 ` Tycho Andersen
2022-08-02 12:50 ` Miklos Szeredi
2022-08-15 13:59 ` Tycho Andersen
2022-08-15 17:55 ` Serge E. Hallyn
2022-09-01 14:06 ` [PATCH] " Tycho Andersen
2022-09-19 15:03 ` Tycho Andersen [this message]
2022-09-20 18:02 ` Serge E. Hallyn
2022-09-26 14:17 ` Tycho Andersen
2022-09-27 9:46 ` Miklos Szeredi
2022-09-29 14:05 ` [fuse-devel] " Stef Bon
2022-09-29 16:39 ` [PATCH v2] " Tycho Andersen
2022-09-30 13:35 ` Miklos Szeredi
2022-09-30 14:01 ` Tycho Andersen
2022-09-30 14:41 ` Miklos Szeredi
2022-09-30 16:09 ` Tycho Andersen
2022-10-26 9:01 ` Miklos Szeredi
2022-11-14 16:02 ` [PATCH v3] " Tycho Andersen
2022-11-28 15:00 ` Tycho Andersen
2022-12-08 14:26 ` Miklos Szeredi
2022-12-08 17:49 ` Tycho Andersen
2022-12-19 19:16 ` Tycho Andersen
2023-01-03 14:51 ` Tycho Andersen
2023-01-05 15:15 ` Serge E. Hallyn
2023-01-26 14:12 ` Miklos Szeredi
2022-09-30 19:47 ` [PATCH] " Serge E. Hallyn
2022-09-19 15:46 ` [RFC][PATCH v2] " Eric W. Biederman
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