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=-15.1 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 6AA8BC433ED for ; Tue, 18 May 2021 12:38:47 +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 0BB0F61185 for ; Tue, 18 May 2021 12:38:47 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0BB0F61185 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]:57424 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1liyzm-0001Te-6l for qemu-devel@archiver.kernel.org; Tue, 18 May 2021 08:38:46 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:48188) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1liysR-0001F2-L9 for qemu-devel@nongnu.org; Tue, 18 May 2021 08:31:11 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:21451) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1liysP-00075B-QO for qemu-devel@nongnu.org; Tue, 18 May 2021 08:31:11 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1621341068; 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: in-reply-to:in-reply-to:references:references; bh=6qu5LCbrfgXwgK43LhTSJnjgO7E9nGgP7sZgNbzhpqk=; b=RArR1uFS4LD7JG0DhtNj5fFtpMFMoyvOmm9wZAbHcsLUhnKqTk5jv4pBt1t5V9IO3fBttr LEdbKvTWpbLW8Gk2GWvwSuR5JjQhbMLXu+dj9KP7+XBaR7U3UWvBsNn1RqK7nATrUdwhc8 MLOeX59WY6f7Mvao4a8C3VnVzOcqZD0= 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-343-JHeGaat9MYS0C9CtttIThg-1; Tue, 18 May 2021 08:31:06 -0400 X-MC-Unique: JHeGaat9MYS0C9CtttIThg-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 766596D249 for ; Tue, 18 May 2021 12:31:05 +0000 (UTC) Received: from work-vm (ovpn-115-45.ams2.redhat.com [10.36.115.45]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 89B005D9C0; Tue, 18 May 2021 12:31:04 +0000 (UTC) Date: Tue, 18 May 2021 13:31:02 +0100 From: "Dr. David Alan Gilbert" To: Vivek Goyal Subject: Re: [PATCH 6/7] virtiofsd: Check EOF before short read Message-ID: References: <20210511213736.281016-1-vgoyal@redhat.com> <20210511213736.281016-7-vgoyal@redhat.com> MIME-Version: 1.0 In-Reply-To: <20210511213736.281016-7-vgoyal@redhat.com> User-Agent: Mutt/2.0.7 (2021-05-04) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=dgilbert@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Received-SPF: pass client-ip=216.205.24.124; envelope-from=dgilbert@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -31 X-Spam_score: -3.2 X-Spam_bar: --- X-Spam_report: (-3.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.374, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action 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 Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" * Vivek Goyal (vgoyal@redhat.com) wrote: > In virtio_send_data_iov() we are checking first for short read and then > EOF condition. Change the order. Basically check for error and EOF first > and last remaining piece is short ready which will lead to retry > automatically at the end of while loop. > > Just that it is little simpler to read to the code. There is no need > to call "continue" and also one less call of "len-=ret". > > Signed-off-by: Vivek Goyal Reviewed-by: Dr. David Alan Gilbert > --- > tools/virtiofsd/fuse_virtio.c | 21 ++++++++++----------- > 1 file changed, 10 insertions(+), 11 deletions(-) > > diff --git a/tools/virtiofsd/fuse_virtio.c b/tools/virtiofsd/fuse_virtio.c > index 434fe401cf..aa53808ef9 100644 > --- a/tools/virtiofsd/fuse_virtio.c > +++ b/tools/virtiofsd/fuse_virtio.c > @@ -410,25 +410,24 @@ int virtio_send_data_iov(struct fuse_session *se, struct fuse_chan *ch, > __func__, len); > goto err; > } > - fuse_log(FUSE_LOG_DEBUG, "%s: preadv ret=%d len=%zd\n", __func__, > - ret, len); > - if (ret < len && ret) { > - fuse_log(FUSE_LOG_DEBUG, "%s: ret < len\n", __func__); > - /* Skip over this much next time around */ > - iov_discard_front(&in_sg_ptr, &in_sg_cpy_count, ret); > - buf->buf[0].pos += ret; > - len -= ret; > > - /* Lets do another read */ > - continue; > - } > if (!ret) { > /* EOF case? */ > fuse_log(FUSE_LOG_DEBUG, "%s: !ret len remaining=%zd\n", __func__, > len); > break; > } > + fuse_log(FUSE_LOG_DEBUG, "%s: preadv ret=%d len=%zd\n", __func__, > + ret, len); > + > len -= ret; > + /* Short read. Retry reading remaining bytes */ > + if (len) { > + fuse_log(FUSE_LOG_DEBUG, "%s: ret < len\n", __func__); > + /* Skip over this much next time around */ > + iov_discard_front(&in_sg_ptr, &in_sg_cpy_count, ret); > + buf->buf[0].pos += ret; > + } > } while (len); > > /* Need to fix out->len on EOF */ > -- > 2.25.4 > -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK