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=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,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 59114C0650F for ; Tue, 30 Jul 2019 06:32:02 +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 2BC302054F for ; Tue, 30 Jul 2019 06:32:02 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2BC302054F 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]:58280 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hsLg1-0005KT-DH for qemu-devel@archiver.kernel.org; Tue, 30 Jul 2019 02:32:01 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:56881) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hsLfQ-0004Sc-Oi for qemu-devel@nongnu.org; Tue, 30 Jul 2019 02:31:25 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hsLfP-0002TY-N7 for qemu-devel@nongnu.org; Tue, 30 Jul 2019 02:31:24 -0400 Received: from mx1.redhat.com ([209.132.183.28]:44940) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hsLfK-0002Pe-I8; Tue, 30 Jul 2019 02:31:19 -0400 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 mx1.redhat.com (Postfix) with ESMTPS id 1EA3AA3B6B; Tue, 30 Jul 2019 06:31:14 +0000 (UTC) Received: from blackfin.pond.sub.org (ovpn-116-51.ams2.redhat.com [10.36.116.51]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 3A7AB1001B07; Tue, 30 Jul 2019 06:31:11 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id B131E1138619; Tue, 30 Jul 2019 08:31:09 +0200 (CEST) From: Markus Armbruster To: Kevin Wolf References: <20190729164234.11573-1-kwolf@redhat.com> Date: Tue, 30 Jul 2019 08:31:09 +0200 In-Reply-To: <20190729164234.11573-1-kwolf@redhat.com> (Kevin Wolf's message of "Mon, 29 Jul 2019 18:42:34 +0200") Message-ID: <874l34ghjm.fsf@dusky.pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.30]); Tue, 30 Jul 2019 06:31:14 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: Re: [Qemu-devel] [PATCH for-4.1] scsi-cd: Fix inserting read-only media in empty drive 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: qemu-devel@nongnu.org, qemu-block@nongnu.org, mreitz@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Kevin Wolf writes: > scsi-disks decides whether it has a read-only device by looking at > whether the BlockBackend specified as drive=... is read-only. In the > case of an anonymous BlockBackend (with a node name specified in > drive=...), this is the read-only flag of the attached node. In the case > of an empty anonymous BlockBackend, it's always read-write because > nothing prevented it from being read-write. > > This is a problem because scsi-cd would take write permissions on the > anonymous BlockBackend of an empty drive created without a drive=... > option. Using blockdev-insert-medium with a read-only node fails then > with the error message "Block node is read-only". > > Fix scsi_realize() so that scsi-cd devices always take read-only > permissions on their BlockBackend instead. > > Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1733920 > Signed-off-by: Kevin Wolf > --- > hw/scsi/scsi-disk.c | 10 ++++++++-- > 1 file changed, 8 insertions(+), 2 deletions(-) > > diff --git a/hw/scsi/scsi-disk.c b/hw/scsi/scsi-disk.c > index 8e95e3e38d..af3e622dc5 100644 > --- a/hw/scsi/scsi-disk.c > +++ b/hw/scsi/scsi-disk.c > @@ -2318,6 +2318,7 @@ static void scsi_disk_unit_attention_reported(SCSIDevice *dev) > static void scsi_realize(SCSIDevice *dev, Error **errp) > { > SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, dev); > + bool read_only; > > if (!s->qdev.conf.blk) { > error_setg(errp, "drive property not set"); > @@ -2351,8 +2352,13 @@ static void scsi_realize(SCSIDevice *dev, Error **errp) > return; > } > } > - if (!blkconf_apply_backend_options(&dev->conf, > - blk_is_read_only(s->qdev.conf.blk), > + > + read_only = blk_is_read_only(s->qdev.conf.blk); > + if (dev->type == TYPE_ROM) { > + read_only = true; > + } > + > + if (!blkconf_apply_backend_options(&dev->conf, read_only, > dev->type == TYPE_DISK, errp)) { > return; > } For what it's worth, we have code similar to the one after this patch in * ide_dev_initfn() * xen_block_realize() (I guess) We have code similar to the one before this patch in * floppy_drive_realize() I figure we avoid the problem by recomputing read-only on media change, in fd_change_cb(). Funny: looks like a medium's read-only-ness lingers after unload until the next medium is loaded. * nvme_realize() * virtio_blk_device_realize() * scsi_generic_realize() * usb_msd_storage_realize() Are these all okay? Should they work more like floppy? If not, what makes floppy special?