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Date:      Mon, 11 Sep 2017 11:20:50 +0100
From:      Nikolaus Rath <Nikolaus@rath.org>
To:        freebsd-fs@freebsd.org
Subject:   Re: umount() taking minutes for FUSE filesystems
Message-ID:  <87a821a64d.fsf@vostro.rath.org>
In-Reply-To: <87lglp6zj8.fsf@vostro.rath.org> (Nikolaus Rath's message of "Fri, 08 Sep 2017 15:22:19 %2B0100")
References:  <87bmn44ruu.fsf@vostro.rath.org> <87o9qyrbs8.fsf@vostro.rath.org> <CAG6CVpWX1TPtR65dXkC4A_-hiSrh0L524mcPtcQM=K28RM7vWw@mail.gmail.com> <2FAD66DE-031B-4B36-9E85-C7BC6B52B5E6@gmail.com> <29de6425-9f92-3bd8-f446-1c9dded33b15@freebsd.org> <87k21dzdrp.fsf@thinkpad.rath.org> <201709051811.v85IBmbO005440@higson.cam.lispworks.com> <87ingugw2v.fsf@thinkpad.rath.org> <201709081143.v88BhEOn001626@higson.cam.lispworks.com> <87lglp6zj8.fsf@vostro.rath.org>

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On Sep 08 2017, Nikolaus Rath <Nikolaus@rath.org> wrote:
> On Sep 08 2017, Martin Simmons <martin@lispworks.com> wrote:
>>>>>>> On Thu, 07 Sep 2017 21:14:32 +0200, Nikolaus Rath said:
>>>=20
>>> On Sep 05 2017, Martin Simmons <martin@lispworks.com> wrote:
>>> >> Probably the crucial difference is that the test that takes long exi=
ts
>>> >> its main loop on its own and then informs the FUSE kernel module abo=
ut
>>> >> that, while the other tests terminate the main loop because the kern=
el
>>> >> module tells them to do so.
>>> >
>>> > What does "informs the FUSE kernel module about that" do to inform it?
>>>=20
>>> It calls unmount.
>>> https://github.com/libfuse/libfuse/blob/master/lib/mount_bsd.c#L127
>>
>> It seems to me that the following occurs:
>>
>> 1. The user program exits the main loop.
>> 2. The user program sends unmount to the kernel.
>> 3. The kernel sends FUSE_DESTROY to the user program.
>> 4. The kernel waits for the user program to respond to FUSE_DESTROY.
>> 5. The user program does not respond because it has exited the main loop.
>> 6. The kernel wait times out after 60 seconds.
>>
>> Perhaps the solution is to close the fd before calling unmount(), like t=
he
>> Linux code in https://github.com/libfuse/libfuse/blob/master/lib/mount.c=
#L275
>> does?
>
> That sounds reasonable, will give it a shot.

This indeed fixed the problem. Thanks!

Best,
-Nikolaus

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