From patchwork Mon Jun 20 23:39:28 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eric Blake X-Patchwork-Id: 9189039 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 1C1106075F for ; Mon, 20 Jun 2016 23:44:22 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 0A52C27CDF for ; Mon, 20 Jun 2016 23:44:22 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id F2D9727E66; Mon, 20 Jun 2016 23:44:21 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=2.0 tests=BAYES_00,DKIM_SIGNED, RCVD_IN_DNSWL_HI,T_DKIM_INVALID autolearn=ham version=3.3.1 Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 6887A27CDF for ; Mon, 20 Jun 2016 23:44:21 +0000 (UTC) Received: from localhost ([::1]:47104 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bF8rc-00041m-7E for patchwork-qemu-devel@patchwork.kernel.org; Mon, 20 Jun 2016 19:44:20 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:38449) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bF8o7-0007Ra-JA for qemu-devel@nongnu.org; Mon, 20 Jun 2016 19:40:45 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bF8o0-0002mz-Ub for qemu-devel@nongnu.org; Mon, 20 Jun 2016 19:40:43 -0400 Received: from resqmta-po-12v.sys.comcast.net ([96.114.154.171]:47132) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bF8o0-0002mX-I7 for qemu-devel@nongnu.org; Mon, 20 Jun 2016 19:40:36 -0400 Received: from resomta-po-10v.sys.comcast.net ([96.114.154.234]) by resqmta-po-12v.sys.comcast.net with SMTP id F8mUbcKy5GpVBF8n2bciaa; Mon, 20 Jun 2016 23:39:36 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=comcast.net; s=q20140121; t=1466465976; bh=4sg1gZKGYilcU+L6e/ePo5mmPokbqH1RH+hXNLGu0ys=; h=Received:Received:From:To:Subject:Date:Message-Id; b=n6SVJBI4flTKs1FtG0ig2M4n4QA/7j82EdP5DfQexCf345pUtRRVMLtAxlgZ3i3G4 vC/4ga7eebEBQjg2yxzL/FEbl1Wcanl77zLGfL/FgdJ1U6b6s4izAOJ58iomF/QkwG ONnXGIFTMVsk0w8UyG+8BaJ5YOSYtRgEw47lgyrCuSFjY+HFOJQ/iSWu8Vxa7gPFQv hBvgpsvzh9GkM9NlprJ/0QGScX2eYsxcrC+wyIHOjBDnDlrQ4LKo+D1e0zCNpysxO1 fgocjGs/Z96rK+l5Pcct9VV9oOm23YWo2BKzStoIbjDDnPzWmBdkzgfM/YG5k5LHTv 45m1k/xZK+WtQ== Received: from red.redhat.com ([24.10.254.122]) by resomta-po-10v.sys.comcast.net with comcast id 9BfW1t0022fD5rL01BfcaE; Mon, 20 Jun 2016 23:39:36 +0000 From: Eric Blake To: qemu-devel@nongnu.org Date: Mon, 20 Jun 2016 17:39:28 -0600 Message-Id: <1466465969-25315-5-git-send-email-eblake@redhat.com> X-Mailer: git-send-email 2.5.5 In-Reply-To: <1466465969-25315-1-git-send-email-eblake@redhat.com> References: <1466465969-25315-1-git-send-email-eblake@redhat.com> X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 96.114.154.171 Subject: [Qemu-devel] [PATCH 4/5] nbd: Rely on block layer to break up large requests X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kwolf@redhat.com, Paolo Bonzini , qemu-block@nongnu.org, Max Reitz Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" X-Virus-Scanned: ClamAV using ClamSMTP Now that the block layer will honor max_transfer, we can simplify our code to rely on that guarantee. The readv code can call directly into nbd-client, just as the writev code has done since commit 52a4650. Interestingly enough, while qemu-io 'w 0 40m' splits into a 32M and 8M transaction, 'w -z 0 40m' splits into two 16M and an 8M, because the block layer caps the bounce buffer for writing zeroes at 16M. When we later introduce support for NBD_CMD_WRITE_ZEROES, we can get a full 32M zero write (or larger, if the client and server negotiate that write zeroes can use a larger size than ordinary writes). Signed-off-by: Eric Blake --- block/nbd-client.c | 51 ++++++++------------------------------------------- block/nbd.c | 12 +++--------- 2 files changed, 11 insertions(+), 52 deletions(-) diff --git a/block/nbd-client.c b/block/nbd-client.c index 420bce8..9f023f8 100644 --- a/block/nbd-client.c +++ b/block/nbd-client.c @@ -217,15 +217,15 @@ static void nbd_coroutine_end(NbdClientSession *s, } } -static int nbd_co_readv_1(BlockDriverState *bs, int64_t sector_num, - int nb_sectors, QEMUIOVector *qiov, - int offset) +int nbd_client_co_readv(BlockDriverState *bs, int64_t sector_num, + int nb_sectors, QEMUIOVector *qiov) { NbdClientSession *client = nbd_get_client_session(bs); struct nbd_request request = { .type = NBD_CMD_READ }; struct nbd_reply reply; ssize_t ret; + assert(nb_sectors <= NBD_MAX_SECTORS); request.from = sector_num * 512; request.len = nb_sectors * 512; @@ -234,16 +234,15 @@ static int nbd_co_readv_1(BlockDriverState *bs, int64_t sector_num, if (ret < 0) { reply.error = -ret; } else { - nbd_co_receive_reply(client, &request, &reply, qiov, offset); + nbd_co_receive_reply(client, &request, &reply, qiov, 0); } nbd_coroutine_end(client, &request); return -reply.error; } -static int nbd_co_writev_1(BlockDriverState *bs, int64_t sector_num, - int nb_sectors, QEMUIOVector *qiov, - int offset, int flags) +int nbd_client_co_writev(BlockDriverState *bs, int64_t sector_num, + int nb_sectors, QEMUIOVector *qiov, int flags) { NbdClientSession *client = nbd_get_client_session(bs); struct nbd_request request = { .type = NBD_CMD_WRITE }; @@ -255,11 +254,12 @@ static int nbd_co_writev_1(BlockDriverState *bs, int64_t sector_num, request.type |= NBD_CMD_FLAG_FUA; } + assert(nb_sectors <= NBD_MAX_SECTORS); request.from = sector_num * 512; request.len = nb_sectors * 512; nbd_coroutine_start(client, &request); - ret = nbd_co_send_request(bs, &request, qiov, offset); + ret = nbd_co_send_request(bs, &request, qiov, 0); if (ret < 0) { reply.error = -ret; } else { @@ -269,41 +269,6 @@ static int nbd_co_writev_1(BlockDriverState *bs, int64_t sector_num, return -reply.error; } -int nbd_client_co_readv(BlockDriverState *bs, int64_t sector_num, - int nb_sectors, QEMUIOVector *qiov) -{ - int offset = 0; - int ret; - while (nb_sectors > NBD_MAX_SECTORS) { - ret = nbd_co_readv_1(bs, sector_num, NBD_MAX_SECTORS, qiov, offset); - if (ret < 0) { - return ret; - } - offset += NBD_MAX_SECTORS * 512; - sector_num += NBD_MAX_SECTORS; - nb_sectors -= NBD_MAX_SECTORS; - } - return nbd_co_readv_1(bs, sector_num, nb_sectors, qiov, offset); -} - -int nbd_client_co_writev(BlockDriverState *bs, int64_t sector_num, - int nb_sectors, QEMUIOVector *qiov, int flags) -{ - int offset = 0; - int ret; - while (nb_sectors > NBD_MAX_SECTORS) { - ret = nbd_co_writev_1(bs, sector_num, NBD_MAX_SECTORS, qiov, offset, - flags); - if (ret < 0) { - return ret; - } - offset += NBD_MAX_SECTORS * 512; - sector_num += NBD_MAX_SECTORS; - nb_sectors -= NBD_MAX_SECTORS; - } - return nbd_co_writev_1(bs, sector_num, nb_sectors, qiov, offset, flags); -} - int nbd_client_co_flush(BlockDriverState *bs) { NbdClientSession *client = nbd_get_client_session(bs); diff --git a/block/nbd.c b/block/nbd.c index 08e5b67..8a13078 100644 --- a/block/nbd.c +++ b/block/nbd.c @@ -349,12 +349,6 @@ static int nbd_open(BlockDriverState *bs, QDict *options, int flags, return ret; } -static int nbd_co_readv(BlockDriverState *bs, int64_t sector_num, - int nb_sectors, QEMUIOVector *qiov) -{ - return nbd_client_co_readv(bs, sector_num, nb_sectors, qiov); -} - static int nbd_co_flush(BlockDriverState *bs) { return nbd_client_co_flush(bs); @@ -450,7 +444,7 @@ static BlockDriver bdrv_nbd = { .instance_size = sizeof(BDRVNBDState), .bdrv_parse_filename = nbd_parse_filename, .bdrv_file_open = nbd_open, - .bdrv_co_readv = nbd_co_readv, + .bdrv_co_readv = nbd_client_co_readv, .bdrv_co_writev_flags = nbd_client_co_writev, .bdrv_close = nbd_close, .bdrv_co_flush_to_os = nbd_co_flush, @@ -468,7 +462,7 @@ static BlockDriver bdrv_nbd_tcp = { .instance_size = sizeof(BDRVNBDState), .bdrv_parse_filename = nbd_parse_filename, .bdrv_file_open = nbd_open, - .bdrv_co_readv = nbd_co_readv, + .bdrv_co_readv = nbd_client_co_readv, .bdrv_co_writev_flags = nbd_client_co_writev, .bdrv_close = nbd_close, .bdrv_co_flush_to_os = nbd_co_flush, @@ -486,7 +480,7 @@ static BlockDriver bdrv_nbd_unix = { .instance_size = sizeof(BDRVNBDState), .bdrv_parse_filename = nbd_parse_filename, .bdrv_file_open = nbd_open, - .bdrv_co_readv = nbd_co_readv, + .bdrv_co_readv = nbd_client_co_readv, .bdrv_co_writev_flags = nbd_client_co_writev, .bdrv_close = nbd_close, .bdrv_co_flush_to_os = nbd_co_flush,