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=-13.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham 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 A96CFC433ED for ; Thu, 20 May 2021 15:47:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8E76C6108D for ; Thu, 20 May 2021 15:47:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239066AbhETPsr convert rfc822-to-8bit (ORCPT ); Thu, 20 May 2021 11:48:47 -0400 Received: from us-smtp-delivery-44.mimecast.com ([207.211.30.44]:21655 "EHLO us-smtp-delivery-44.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233137AbhETPsl (ORCPT ); Thu, 20 May 2021 11:48:41 -0400 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-331-J5b6BXnVM5CEOh3kl5xPKw-1; Thu, 20 May 2021 11:47:15 -0400 X-MC-Unique: J5b6BXnVM5CEOh3kl5xPKw-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id B97B21854E21; Thu, 20 May 2021 15:47:13 +0000 (UTC) Received: from bahia.redhat.com (ovpn-112-99.ams2.redhat.com [10.36.112.99]) by smtp.corp.redhat.com (Postfix) with ESMTP id EEE8110013C1; Thu, 20 May 2021 15:47:11 +0000 (UTC) From: Greg Kurz To: Miklos Szeredi Cc: virtualization@lists.linux-foundation.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, virtio-fs@redhat.com, Stefan Hajnoczi , Max Reitz , Vivek Goyal , Greg Kurz Subject: [PATCH v4 4/5] virtiofs: Skip submounts in sget_fc() Date: Thu, 20 May 2021 17:46:53 +0200 Message-Id: <20210520154654.1791183-5-groug@kaod.org> In-Reply-To: <20210520154654.1791183-1-groug@kaod.org> References: <20210520154654.1791183-1-groug@kaod.org> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=groug@kaod.org X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: kaod.org Content-Transfer-Encoding: 8BIT Content-Type: text/plain; charset=WINDOWS-1252 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org All submounts share the same virtio-fs device instance as the root mount. If the same virtiofs filesystem is mounted again, sget_fc() is likely to pick up any of these submounts and reuse it instead of the root mount. On the server side: # mkdir ${some_dir} # mkdir ${some_dir}/mnt1 # mount -t tmpfs none ${some_dir}/mnt1 # touch ${some_dir}/mnt1/THIS_IS_MNT1 # mkdir ${some_dir}/mnt2 # mount -t tmpfs none ${some_dir}/mnt2 # touch ${some_dir}/mnt2/THIS_IS_MNT2 On the client side: # mkdir /mnt/virtiofs1 # mount -t virtiofs myfs /mnt/virtiofs1 # ls /mnt/virtiofs1 mnt1 mnt2 # grep virtiofs /proc/mounts myfs /mnt/virtiofs1 virtiofs rw,seclabel,relatime 0 0 none on /mnt/mnt1 type virtiofs (rw,relatime,seclabel) none on /mnt/mnt2 type virtiofs (rw,relatime,seclabel) And now remount it again: # mount -t virtiofs myfs /mnt/virtiofs2 # grep virtiofs /proc/mounts myfs /mnt/virtiofs1 virtiofs rw,seclabel,relatime 0 0 none on /mnt/mnt1 type virtiofs (rw,relatime,seclabel) none on /mnt/mnt2 type virtiofs (rw,relatime,seclabel) myfs /mnt/virtiofs2 virtiofs rw,seclabel,relatime 0 0 # ls /mnt/virtiofs2 THIS_IS_MNT2 Submount mnt2 was picked-up instead of the root mount. Just skip submounts in virtio_fs_test_super(). Signed-off-by: Greg Kurz --- fs/fuse/virtio_fs.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/fs/fuse/virtio_fs.c b/fs/fuse/virtio_fs.c index e12e5190352c..8962cd033016 100644 --- a/fs/fuse/virtio_fs.c +++ b/fs/fuse/virtio_fs.c @@ -1408,6 +1408,11 @@ static int virtio_fs_test_super(struct super_block *sb, struct fuse_mount *fsc_fm = fsc->s_fs_info; struct fuse_mount *sb_fm = get_fuse_mount_super(sb); + + /* Skip submounts */ + if (!list_is_first(&sb_fm->fc_entry, &sb_fm->fc->mounts)) + return 0; + return fsc_fm->fc->iq.priv == sb_fm->fc->iq.priv; } -- 2.26.3