From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id EC0F0C43603 for ; Mon, 9 Dec 2019 11:07:32 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id B66E02077B for ; Mon, 9 Dec 2019 11:07:31 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="ETcqZLsv" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B66E02077B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:38552 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1ieGt0-0005rd-TE for qemu-devel@archiver.kernel.org; Mon, 09 Dec 2019 06:07:30 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:40868) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1ieGs2-0005QP-Tr for qemu-devel@nongnu.org; Mon, 09 Dec 2019 06:06:32 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ieGs1-0003QI-9n for qemu-devel@nongnu.org; Mon, 09 Dec 2019 06:06:30 -0500 Received: from us-smtp-1.mimecast.com ([205.139.110.61]:51347 helo=us-smtp-delivery-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1ieGs1-0003Pp-29 for qemu-devel@nongnu.org; Mon, 09 Dec 2019 06:06:29 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1575889588; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=DzsCG7XOU7Z5xoj8yg3xIM/eZU+HB/jzKirzk7RSnBA=; b=ETcqZLsvCIM//b6rFsO8mcICymPjS5NtxiFe2b2euyLrpV6M7qi+CvW0EU69nm5T6MePwb 8MDEnZXwL8pgtHvjFhDXdAJ0gk/KPoqMZi07UmGEPSZkgFGqJfAMB48L9ouUPNhkrv+NNB jeXU/iOMgWdXatBi9fIPKrCL9MWhbmk= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-168-hoWKANAdNw-9zpfZrwAGNQ-1; Mon, 09 Dec 2019 06:06:25 -0500 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 04233107ACCD; Mon, 9 Dec 2019 11:06:24 +0000 (UTC) Received: from work-vm (ovpn-116-253.ams2.redhat.com [10.36.116.253]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 7BF2460BE1; Mon, 9 Dec 2019 11:06:20 +0000 (UTC) Date: Mon, 9 Dec 2019 11:06:17 +0000 From: "Dr. David Alan Gilbert" To: Vivek Goyal Subject: Re: [Virtio-fs] [PATCH 4/4] virtiofsd: Implement blocking posix locks Message-ID: <20191209110617.GE3403@work-vm> References: <20191115205543.1816-1-vgoyal@redhat.com> <20191115205543.1816-5-vgoyal@redhat.com> <20191122174732.GL2785@work-vm> <20191125154414.GC13247@redhat.com> <20191126130229.GG2928@work-vm> <20191127190808.GA18507@redhat.com> MIME-Version: 1.0 In-Reply-To: <20191127190808.GA18507@redhat.com> User-Agent: Mutt/1.12.1 (2019-06-15) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-MC-Unique: hoWKANAdNw-9zpfZrwAGNQ-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: quoted-printable Content-Disposition: inline X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 205.139.110.61 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: virtio-fs@redhat.com, qemu-devel@nongnu.org, miklos@szeredi.hu Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" * Vivek Goyal (vgoyal@redhat.com) wrote: > On Tue, Nov 26, 2019 at 01:02:29PM +0000, Dr. David Alan Gilbert wrote: >=20 > [..] > > > > > @@ -1950,21 +1948,54 @@ static void lo_setlk(fuse_req_t req, fuse= _ino_t ino, > > > > > =20 > > > > > =09if (!plock) { > > > > > =09=09saverr =3D ret; > > > > > +=09=09pthread_mutex_unlock(&inode->plock_mutex); > > > > > =09=09goto out; > > > > > =09} > > > > > =20 > > > > > +=09/* > > > > > +=09 * plock is now released when inode is going away. We already= have > > > > > +=09 * a reference on inode, so it is guaranteed that plock->fd i= s > > > > > +=09 * still around even after dropping inode->plock_mutex lock > > > > > +=09 */ > > > > > +=09ofd =3D plock->fd; > > > > > +=09pthread_mutex_unlock(&inode->plock_mutex); > > > > > + > > > > > +=09/* > > > > > +=09 * If this lock request can block, request caller to wait for > > > > > +=09 * notification. Do not access req after this. Once lock is > > > > > +=09 * available, send a notification instead. > > > > > +=09 */ > > > > > +=09if (sleep && lock->l_type !=3D F_UNLCK) { > > > > > +=09=09/* > > > > > +=09=09 * If notification queue is not enabled, can't support asy= nc > > > > > +=09=09 * locks. > > > > > +=09=09 */ > > > > > +=09=09if (!se->notify_enabled) { > > > > > +=09=09=09saverr =3D EOPNOTSUPP; > > > > > +=09=09=09goto out; > > > > > +=09=09} > > > > > +=09=09async_lock =3D true; > > > > > +=09=09unique =3D req->unique; > > > > > +=09=09fuse_reply_wait(req); > > > > > +=09} > > > > > =09/* TODO: Is it alright to modify flock? */ > > > > > =09lock->l_pid =3D 0; > > > > > -=09ret =3D fcntl(plock->fd, F_OFD_SETLK, lock); > > > > > +=09if (async_lock) > > > > > +=09=09ret =3D fcntl(ofd, F_OFD_SETLKW, lock); > > > > > +=09else > > > > > +=09=09ret =3D fcntl(ofd, F_OFD_SETLK, lock); > > > >=20 > > > > What happens if the guest is rebooted after it's asked > > > > for, but not been granted a lock? > > >=20 > > > I think a regular reboot can't be done till a request is pending, bec= ause > > > virtio-fs can't be unmounted and unmount will wait for all pending > > > requests to finish. > > >=20 > > > Destroying qemu will destroy deamon too. > > >=20 > > > Are there any other reboot paths I have missed. > >=20 > > Yes, there are a few other ways the guest can reboot: > > a) A echo b > /proc/sysrq-trigger >=20 > I tried it. Both qemu and virtiofsd hang. virtiofsd wants to stop a=20 > queue. And that tries to stop thrad pool. But one of the threads in > thread pool is blocked on setlkw. So g_thread_pool_free() hangs. >=20 > I am not seeing any option in glib thread pool API to stop or send > signal to threads which are blocked. Is there a way to setup pthread_cancel ? The upstream libfuse code has somec ases where it enables cancellation very carefully around something that might block, does it, then disables cancellation. Dave > Thanks > Vivek -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK