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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 1B0E8C43334 for ; Thu, 16 Jun 2022 11:51:22 +0000 (UTC) Received: from localhost ([::1]:35078 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1o1o1w-0003b7-T2 for qemu-devel@archiver.kernel.org; Thu, 16 Jun 2022 07:51:20 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:51936) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1o1nYC-000428-84 for qemu-devel@nongnu.org; Thu, 16 Jun 2022 07:20:36 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:27188) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1o1nY9-0008OV-Pf for qemu-devel@nongnu.org; Thu, 16 Jun 2022 07:20:35 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1655378431; h=from:from:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:in-reply-to:in-reply-to: references:references; bh=KVZKHuUfk6deVE+IaVKCq943aUp4wh+GMfKLlEQlCoI=; b=h4ys762qFQHHOrOTRemppgjjUpWtYoMvBwU6SmGSk/Q8m4Jc3ml564uQGKDYSllcVhHB04 td6nMcmsHtoQuCrVInEXRhXtq0eyzKEKA79PMs+gu0SXpvje0w5YPs6W5HT/zpv4udpmbs M/Q7zPgCc0LvzE0LV5Rju63rg6LSbSc= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-196-FoUtY2TuME29jfiaiSpLXg-1; Thu, 16 Jun 2022 07:20:28 -0400 X-MC-Unique: FoUtY2TuME29jfiaiSpLXg-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.rdu2.redhat.com [10.11.54.2]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 5A44B380452C; Thu, 16 Jun 2022 11:20:28 +0000 (UTC) Received: from redhat.com (unknown [10.33.36.111]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 43BE140885A1; Thu, 16 Jun 2022 11:20:27 +0000 (UTC) Date: Thu, 16 Jun 2022 12:20:24 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: nikita.lapshin@openvz.org Cc: qemu-devel@nongnu.org, den@virtuozzo.com, andrey.drobyshev@virtuozzo.com, quintela@redhat.com, dgilbert@redhat.com Subject: Re: [PATCH v3 11/17] migration/qemu-file: Fix qemu_ftell() for non-writable file Message-ID: References: <20220616102811.219007-1-nikita.lapshin@openvz.org> <20220616102811.219007-12-nikita.lapshin@openvz.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20220616102811.219007-12-nikita.lapshin@openvz.org> User-Agent: Mutt/2.2.1 (2022-02-19) X-Scanned-By: MIMEDefang 2.84 on 10.11.54.2 Received-SPF: pass client-ip=170.10.133.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -28 X-Spam_score: -2.9 X-Spam_bar: -- X-Spam_report: (-2.9 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.082, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Thu, Jun 16, 2022 at 01:28:05PM +0300, nikita.lapshin@openvz.org wrote: > From: Nikita Lapshin > > qemu_ftell() will return wrong value for non-writable QEMUFile. > This happens due to call qemu_fflush() inside qemu_ftell(), this > function won't flush if file is readable. Well the return value isn't necessarily wrong today - it really depends what semantics each callers desires. Can you say what particular caller needs these semantics changed and the impact on them from current behaviour ? > Signed-off-by: Nikita Lapshin > --- > migration/qemu-file.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/migration/qemu-file.c b/migration/qemu-file.c > index 1479cddad9..53ccef80ac 100644 > --- a/migration/qemu-file.c > +++ b/migration/qemu-file.c > @@ -663,7 +663,8 @@ int64_t qemu_ftell_fast(QEMUFile *f) > int64_t qemu_ftell(QEMUFile *f) > { > qemu_fflush(f); > - return f->pos; > + /* Consider that qemu_fflush() won't work if file is non-writable */ > + return f->pos + f->buf_index; > } IIUC, this is more or less trying to make 'qemu_ftell' be equivalent to 'qemu_ftell_fast' semantics in the non-writable case. But that makes me wonder if whichever calls has problems, shouldn't be just changed to use qemu_ftell_fast instead ? With regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|