From nobody Sun Oct 5 21:10:02 2025 Delivered-To: importer@patchew.org Received-SPF: pass (zoho.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zohomail.com; spf=pass (zoho.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail(p=none dis=none) header.from=redhat.com ARC-Seal: i=1; a=rsa-sha256; t=1565894116; cv=none; d=zoho.com; s=zohoarc; b=ZylC/EEMERlILv3fYRaPQzQ640Doi+p2+PbVPBld4yJNCtRTyfmQCfEKf9zcEYLaJ5+OsET4KHsBDceFg4GBV6vPaSNLwzmhpI1iPW/3NNY9O6MBfqI9BhITP3yzIH60iQzxojWuUYxqLL2EoGdBEEcMFn4mnQZ59RQOjpt5Bts= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zoho.com; s=zohoarc; t=1565894116; h=Content-Transfer-Encoding:Cc:Date:From:In-Reply-To:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:MIME-Version:Message-ID:References:Sender:Subject:To:ARC-Authentication-Results; bh=L7xVmzXTeMJcwfsl9JCKG5xijiSTdJkCSTWzFjFvfY0=; b=W/9JaMzHV2JA/UJ7lt1YESYV8wd5c1NB+pCdIDtlhuskbootuG3bqyPg5p9uQ+4n8s+aMXvTOfHWbjbITYmJv9Uk98KqtNLensj0WTGOKpMDErBgCsRnr6PQz0Lkc1WABlnI6cdFj7eWNnHNFHuV/uifsndvpMdGl7wave5eZG0= ARC-Authentication-Results: i=1; mx.zoho.com; spf=pass (zoho.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail header.from= (p=none dis=none) header.from= Return-Path: Received: from lists.gnu.org (209.51.188.17 [209.51.188.17]) by mx.zohomail.com with SMTPS id 1565894116678534.0392102045563; Thu, 15 Aug 2019 11:35:16 -0700 (PDT) Received: from localhost ([::1]:46070 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1hyKaf-0005IL-36 for importer@patchew.org; Thu, 15 Aug 2019 14:35:13 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:37535) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1hyKXA-0002zr-DJ for qemu-devel@nongnu.org; Thu, 15 Aug 2019 14:31:39 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hyKX7-0001wy-Td for qemu-devel@nongnu.org; Thu, 15 Aug 2019 14:31:36 -0400 Received: from mx1.redhat.com ([209.132.183.28]:38626) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hyKWz-0001ey-C6; Thu, 15 Aug 2019 14:31:26 -0400 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 297F230BB8E8; Thu, 15 Aug 2019 18:31:23 +0000 (UTC) Received: from blue.redhat.com (ovpn-117-22.phx2.redhat.com [10.3.117.22]) by smtp.corp.redhat.com (Postfix) with ESMTP id A359F84BBA; Thu, 15 Aug 2019 18:31:22 +0000 (UTC) From: Eric Blake To: qemu-devel@nongnu.org Date: Thu, 15 Aug 2019 13:30:34 -0500 Message-Id: <20190815183039.4264-5-eblake@redhat.com> In-Reply-To: <20190815183039.4264-1-eblake@redhat.com> References: <20190815183039.4264-1-eblake@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.42]); Thu, 15 Aug 2019 18:31:23 +0000 (UTC) Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PULL 4/9] nbd: improve CMD_CACHE: use BDRV_REQ_PREFETCH 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: Vladimir Sementsov-Ogievskiy , "open list:Network Block Dev..." , Stefan Hajnoczi Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" Content-Type: text/plain; charset="utf-8" From: Vladimir Sementsov-Ogievskiy This helps to avoid extra io, allocations and memory copying. We assume here that CMD_CACHE is always used with copy-on-read, as otherwise it's a noop. Signed-off-by: Vladimir Sementsov-Ogievskiy Message-Id: <20190725100550.33801-4-vsementsov@virtuozzo.com> Reviewed-by: Eric Blake Reviewed-by: Stefan Hajnoczi Signed-off-by: Eric Blake --- nbd/server.c | 43 +++++++++++++++++++++++++++++++++++-------- 1 file changed, 35 insertions(+), 8 deletions(-) diff --git a/nbd/server.c b/nbd/server.c index 10faedcfc55d..a2cf085f7635 100644 --- a/nbd/server.c +++ b/nbd/server.c @@ -2104,12 +2104,15 @@ static int nbd_co_receive_request(NBDRequestData *r= eq, NBDRequest *request, return -EINVAL; } - req->data =3D blk_try_blockalign(client->exp->blk, request->len); - if (req->data =3D=3D NULL) { - error_setg(errp, "No memory"); - return -ENOMEM; + if (request->type !=3D NBD_CMD_CACHE) { + req->data =3D blk_try_blockalign(client->exp->blk, request->le= n); + if (req->data =3D=3D NULL) { + error_setg(errp, "No memory"); + return -ENOMEM; + } } } + if (request->type =3D=3D NBD_CMD_WRITE) { if (nbd_read(client->ioc, req->data, request->len, "CMD_WRITE data= ", errp) < 0) @@ -2194,7 +2197,7 @@ static coroutine_fn int nbd_do_cmd_read(NBDClient *cl= ient, NBDRequest *request, int ret; NBDExport *exp =3D client->exp; - assert(request->type =3D=3D NBD_CMD_READ || request->type =3D=3D NBD_C= MD_CACHE); + assert(request->type =3D=3D NBD_CMD_READ); /* XXX: NBD Protocol only documents use of FUA with WRITE */ if (request->flags & NBD_CMD_FLAG_FUA) { @@ -2206,7 +2209,7 @@ static coroutine_fn int nbd_do_cmd_read(NBDClient *cl= ient, NBDRequest *request, } if (client->structured_reply && !(request->flags & NBD_CMD_FLAG_DF) && - request->len && request->type !=3D NBD_CMD_CACHE) + request->len) { return nbd_co_send_sparse_read(client, request->handle, request->f= rom, data, request->len, errp); @@ -2214,7 +2217,7 @@ static coroutine_fn int nbd_do_cmd_read(NBDClient *cl= ient, NBDRequest *request, ret =3D blk_pread(exp->blk, request->from + exp->dev_offset, data, request->len); - if (ret < 0 || request->type =3D=3D NBD_CMD_CACHE) { + if (ret < 0) { return nbd_send_generic_reply(client, request->handle, ret, "reading from file failed", errp); } @@ -2233,6 +2236,28 @@ static coroutine_fn int nbd_do_cmd_read(NBDClient *c= lient, NBDRequest *request, } } +/* + * nbd_do_cmd_cache + * + * Handle NBD_CMD_CACHE request. + * Return -errno if sending fails. Other errors are reported directly to t= he + * client as an error reply. + */ +static coroutine_fn int nbd_do_cmd_cache(NBDClient *client, NBDRequest *re= quest, + Error **errp) +{ + int ret; + NBDExport *exp =3D client->exp; + + assert(request->type =3D=3D NBD_CMD_CACHE); + + ret =3D blk_co_preadv(exp->blk, request->from + exp->dev_offset, reque= st->len, + NULL, BDRV_REQ_COPY_ON_READ | BDRV_REQ_PREFETCH); + + return nbd_send_generic_reply(client, request->handle, ret, + "caching data failed", errp); +} + /* Handle NBD request. * Return -errno if sending fails. Other errors are reported directly to t= he * client as an error reply. */ @@ -2246,8 +2271,10 @@ static coroutine_fn int nbd_handle_request(NBDClient= *client, char *msg; switch (request->type) { - case NBD_CMD_READ: case NBD_CMD_CACHE: + return nbd_do_cmd_cache(client, request, errp); + + case NBD_CMD_READ: return nbd_do_cmd_read(client, request, data, errp); case NBD_CMD_WRITE: --=20 2.20.1