From patchwork Fri Mar 18 18:21:23 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kevin Wolf X-Patchwork-Id: 8623031 Return-Path: X-Original-To: patchwork-qemu-devel@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 731ED9F6E1 for ; Fri, 18 Mar 2016 18:29:56 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id B42A820225 for ; Fri, 18 Mar 2016 18:29:55 +0000 (UTC) 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.kernel.org (Postfix) with ESMTPS id C9A3E201FE for ; Fri, 18 Mar 2016 18:29:54 +0000 (UTC) Received: from localhost ([::1]:45633 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1agz9m-00020s-5T for patchwork-qemu-devel@patchwork.kernel.org; Fri, 18 Mar 2016 14:29:54 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:36669) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1agz2C-0004Ij-13 for qemu-devel@nongnu.org; Fri, 18 Mar 2016 14:22:05 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1agz2A-0007Ca-M4 for qemu-devel@nongnu.org; Fri, 18 Mar 2016 14:22:03 -0400 Received: from mx1.redhat.com ([209.132.183.28]:36671) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1agz27-00079x-MR; Fri, 18 Mar 2016 14:21:59 -0400 Received: from int-mx10.intmail.prod.int.phx2.redhat.com (int-mx10.intmail.prod.int.phx2.redhat.com [10.5.11.23]) by mx1.redhat.com (Postfix) with ESMTPS id 6314980E42; Fri, 18 Mar 2016 18:21:59 +0000 (UTC) Received: from noname.redhat.com (ovpn-116-83.ams2.redhat.com [10.36.116.83]) by int-mx10.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id u2IILZO5021202; Fri, 18 Mar 2016 14:21:58 -0400 From: Kevin Wolf To: qemu-block@nongnu.org Date: Fri, 18 Mar 2016 19:21:23 +0100 Message-Id: <1458325289-17848-15-git-send-email-kwolf@redhat.com> In-Reply-To: <1458325289-17848-1-git-send-email-kwolf@redhat.com> References: <1458325289-17848-1-git-send-email-kwolf@redhat.com> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.23 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x X-Received-From: 209.132.183.28 Cc: kwolf@redhat.com, qemu-devel@nongnu.org, mreitz@redhat.com Subject: [Qemu-devel] [PATCH 14/20] nbd: Support BDRV_REQ_FUA X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP The NBD server already used to send a FUA flag when the writethrough mode was set. This code was a remnant from the times where protocol drivers actually had to implement writethrough modes. Since nowadays the block layer sends flushes in writethrough mode and non-root nodes are always writeback, this was mostly dead code - only mostly because if NBD was configured to be used without a format, we sent _both_ FUA and an explicit flush afterwards, which makes the code not technically dead, but useless overhead. This patch changes the code so that the block layer's FUA flag is recognised and translated into a NBD FUA flag. The additional flush is avoided now. Signed-off-by: Kevin Wolf --- block/nbd-client.c | 13 +++++++------ block/nbd-client.h | 2 +- block/nbd.c | 26 +++++++++++++++++++++----- 3 files changed, 29 insertions(+), 12 deletions(-) diff --git a/block/nbd-client.c b/block/nbd-client.c index 6a9b4c7..021a88b 100644 --- a/block/nbd-client.c +++ b/block/nbd-client.c @@ -243,15 +243,15 @@ static int nbd_co_readv_1(BlockDriverState *bs, int64_t sector_num, static int nbd_co_writev_1(BlockDriverState *bs, int64_t sector_num, int nb_sectors, QEMUIOVector *qiov, - int offset) + int offset, int *flags) { NbdClientSession *client = nbd_get_client_session(bs); struct nbd_request request = { .type = NBD_CMD_WRITE }; struct nbd_reply reply; ssize_t ret; - if (!bdrv_enable_write_cache(bs) && - (client->nbdflags & NBD_FLAG_SEND_FUA)) { + if ((*flags & BDRV_REQ_FUA) && (client->nbdflags & NBD_FLAG_SEND_FUA)) { + *flags &= ~BDRV_REQ_FUA; request.type |= NBD_CMD_FLAG_FUA; } @@ -291,12 +291,13 @@ int nbd_client_co_readv(BlockDriverState *bs, int64_t sector_num, } int nbd_client_co_writev(BlockDriverState *bs, int64_t sector_num, - int nb_sectors, QEMUIOVector *qiov) + 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); + ret = nbd_co_writev_1(bs, sector_num, NBD_MAX_SECTORS, qiov, offset, + flags); if (ret < 0) { return ret; } @@ -304,7 +305,7 @@ int nbd_client_co_writev(BlockDriverState *bs, int64_t sector_num, sector_num += NBD_MAX_SECTORS; nb_sectors -= NBD_MAX_SECTORS; } - return nbd_co_writev_1(bs, sector_num, nb_sectors, qiov, offset); + return nbd_co_writev_1(bs, sector_num, nb_sectors, qiov, offset, flags); } int nbd_client_co_flush(BlockDriverState *bs) diff --git a/block/nbd-client.h b/block/nbd-client.h index 53f116d..bc7aec0 100644 --- a/block/nbd-client.h +++ b/block/nbd-client.h @@ -48,7 +48,7 @@ int nbd_client_co_discard(BlockDriverState *bs, int64_t sector_num, int nb_sectors); int nbd_client_co_flush(BlockDriverState *bs); int nbd_client_co_writev(BlockDriverState *bs, int64_t sector_num, - int nb_sectors, QEMUIOVector *qiov); + int nb_sectors, QEMUIOVector *qiov, int *flags); int nbd_client_co_readv(BlockDriverState *bs, int64_t sector_num, int nb_sectors, QEMUIOVector *qiov); diff --git a/block/nbd.c b/block/nbd.c index 9f333c9..87887c4 100644 --- a/block/nbd.c +++ b/block/nbd.c @@ -355,9 +355,22 @@ static int nbd_co_readv(BlockDriverState *bs, int64_t sector_num, } static int nbd_co_writev(BlockDriverState *bs, int64_t sector_num, - int nb_sectors, QEMUIOVector *qiov) + int nb_sectors, QEMUIOVector *qiov, int flags) { - return nbd_client_co_writev(bs, sector_num, nb_sectors, qiov); + int ret; + + ret = nbd_client_co_writev(bs, sector_num, nb_sectors, qiov, &flags); + if (ret < 0) { + return ret; + } + + /* The flag wasn't sent to the server, so we need to emulate it with an + * explicit flush */ + if (flags & BDRV_REQ_FUA) { + ret = nbd_client_co_flush(bs); + } + + return ret; } static int nbd_co_flush(BlockDriverState *bs) @@ -456,7 +469,8 @@ static BlockDriver bdrv_nbd = { .bdrv_parse_filename = nbd_parse_filename, .bdrv_file_open = nbd_open, .bdrv_co_readv = nbd_co_readv, - .bdrv_co_writev = nbd_co_writev, + .bdrv_co_writev_flags = nbd_co_writev, + .supported_write_flags = BDRV_REQ_FUA, .bdrv_close = nbd_close, .bdrv_co_flush_to_os = nbd_co_flush, .bdrv_co_discard = nbd_co_discard, @@ -474,7 +488,8 @@ static BlockDriver bdrv_nbd_tcp = { .bdrv_parse_filename = nbd_parse_filename, .bdrv_file_open = nbd_open, .bdrv_co_readv = nbd_co_readv, - .bdrv_co_writev = nbd_co_writev, + .bdrv_co_writev_flags = nbd_co_writev, + .supported_write_flags = BDRV_REQ_FUA, .bdrv_close = nbd_close, .bdrv_co_flush_to_os = nbd_co_flush, .bdrv_co_discard = nbd_co_discard, @@ -492,7 +507,8 @@ static BlockDriver bdrv_nbd_unix = { .bdrv_parse_filename = nbd_parse_filename, .bdrv_file_open = nbd_open, .bdrv_co_readv = nbd_co_readv, - .bdrv_co_writev = nbd_co_writev, + .bdrv_co_writev_flags = nbd_co_writev, + .supported_write_flags = BDRV_REQ_FUA, .bdrv_close = nbd_close, .bdrv_co_flush_to_os = nbd_co_flush, .bdrv_co_discard = nbd_co_discard,