From patchwork Sat Jun 25 22:15:53 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eric Blake X-Patchwork-Id: 640594 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [IPv6:2001:4830:134:3::11]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 3rcVNF4yKJz9t0d for ; Sun, 26 Jun 2016 08:33:33 +1000 (AEST) Received: from localhost ([::1]:51744 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bGw8p-0006Gv-Ej for incoming@patchwork.ozlabs.org; Sat, 25 Jun 2016 18:33:31 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:53798) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bGvs2-0003t6-4s for qemu-devel@nongnu.org; Sat, 25 Jun 2016 18:16:14 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bGvrz-0000wf-H4 for qemu-devel@nongnu.org; Sat, 25 Jun 2016 18:16:09 -0400 Received: from mx1.redhat.com ([209.132.183.28]:59307) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bGvrv-0000tS-21; Sat, 25 Jun 2016 18:16:03 -0400 Received: from int-mx13.intmail.prod.int.phx2.redhat.com (int-mx13.intmail.prod.int.phx2.redhat.com [10.5.11.26]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id B54093B728; Sat, 25 Jun 2016 22:16:02 +0000 (UTC) Received: from red.redhat.com (ovpn-116-42.phx2.redhat.com [10.3.116.42]) by int-mx13.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id u5PMFuWh016210; Sat, 25 Jun 2016 18:16:02 -0400 From: Eric Blake To: qemu-devel@nongnu.org Date: Sat, 25 Jun 2016 16:15:53 -0600 Message-Id: <1466892954-8684-14-git-send-email-eblake@redhat.com> In-Reply-To: <1466892954-8684-1-git-send-email-eblake@redhat.com> References: <1466892954-8684-1-git-send-email-eblake@redhat.com> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.26 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.30]); Sat, 25 Jun 2016 22:16:02 +0000 (UTC) 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] [PATCH v4 13/14] nbd: Implement NBD_CMD_WRITE_ZEROES on server 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: Kevin Wolf , pbonzini@redhat.com, qemu-block@nongnu.org, Max Reitz Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" Upstream NBD protocol recently added the ability to efficiently write zeroes without having to send the zeroes over the wire, along with a flag to control whether the client wants a hole. Signed-off-by: Eric Blake --- v4: rebase, fix value for constant v3: abandon NBD_CMD_CLOSE extension, rebase to use blk_pwrite_zeroes --- include/block/nbd.h | 8 ++++++-- nbd/server.c | 42 ++++++++++++++++++++++++++++++++++++++++-- 2 files changed, 46 insertions(+), 4 deletions(-) diff --git a/include/block/nbd.h b/include/block/nbd.h index fc4426c..e23ef73 100644 --- a/include/block/nbd.h +++ b/include/block/nbd.h @@ -69,6 +69,7 @@ struct nbd_reply { #define NBD_FLAG_SEND_FUA (1 << 3) /* Send FUA (Force Unit Access) */ #define NBD_FLAG_ROTATIONAL (1 << 4) /* Use elevator algorithm - rotational media */ #define NBD_FLAG_SEND_TRIM (1 << 5) /* Send TRIM (discard) */ +#define NBD_FLAG_SEND_WRITE_ZEROES (1 << 6) /* Send WRITE_ZEROES */ /* New-style handshake (global) flags, sent from server to client, and control what will happen during handshake phase. */ @@ -94,7 +95,8 @@ struct nbd_reply { #define NBD_REP_ERR_SHUTDOWN NBD_REP_ERR(7) /* Server shutting down */ /* Request flags, sent from client to server during transmission phase */ -#define NBD_CMD_FLAG_FUA (1 << 0) +#define NBD_CMD_FLAG_FUA (1 << 0) /* 'force unit access' during write */ +#define NBD_CMD_FLAG_NO_HOLE (1 << 1) /* don't punch hole on zero run */ /* Supported request types */ enum { @@ -102,7 +104,9 @@ enum { NBD_CMD_WRITE = 1, NBD_CMD_DISC = 2, NBD_CMD_FLUSH = 3, - NBD_CMD_TRIM = 4 + NBD_CMD_TRIM = 4, + /* 5 reserved for failed experiment NBD_CMD_CACHE */ + NBD_CMD_WRITE_ZEROES = 6, }; #define NBD_DEFAULT_PORT 10809 diff --git a/nbd/server.c b/nbd/server.c index ee99e19..58100b3 100644 --- a/nbd/server.c +++ b/nbd/server.c @@ -606,7 +606,8 @@ static coroutine_fn int nbd_negotiate(NBDClientNewData *data) char buf[8 + 8 + 8 + 128]; int rc; const uint16_t myflags = (NBD_FLAG_HAS_FLAGS | NBD_FLAG_SEND_TRIM | - NBD_FLAG_SEND_FLUSH | NBD_FLAG_SEND_FUA); + NBD_FLAG_SEND_FLUSH | NBD_FLAG_SEND_FUA | + NBD_FLAG_SEND_WRITE_ZEROES); bool oldStyle; size_t len; @@ -1122,11 +1123,17 @@ static ssize_t nbd_co_receive_request(NBDRequest *req, rc = request->type == NBD_CMD_WRITE ? -ENOSPC : -EINVAL; goto out; } - if (request->flags & ~NBD_CMD_FLAG_FUA) { + if (request->flags & ~(NBD_CMD_FLAG_FUA | NBD_CMD_FLAG_NO_HOLE)) { LOG("unsupported flags (got 0x%x)", request->flags); rc = -EINVAL; goto out; } + if (request->type != NBD_CMD_WRITE_ZEROES && + (request->flags & NBD_CMD_FLAG_NO_HOLE)) { + LOG("unexpected flags (got 0x%x)", request->flags); + rc = -EINVAL; + goto out; + } rc = 0; @@ -1231,6 +1238,37 @@ static void nbd_trip(void *opaque) } break; + case NBD_CMD_WRITE_ZEROES: + TRACE("Request type is WRITE_ZEROES"); + + if (exp->nbdflags & NBD_FLAG_READ_ONLY) { + TRACE("Server is read-only, return error"); + reply.error = EROFS; + goto error_reply; + } + + TRACE("Writing to device"); + + flags = 0; + if (request.flags & NBD_CMD_FLAG_FUA) { + flags |= BDRV_REQ_FUA; + } + if (!(request.flags & NBD_CMD_FLAG_NO_HOLE)) { + flags |= BDRV_REQ_MAY_UNMAP; + } + ret = blk_pwrite_zeroes(exp->blk, request.from + exp->dev_offset, + request.len, flags); + if (ret < 0) { + LOG("writing to file failed"); + reply.error = -ret; + goto error_reply; + } + + if (nbd_co_send_reply(req, &reply, 0) < 0) { + goto out; + } + break; + case NBD_CMD_DISC: /* unreachable, thanks to special case in nbd_co_receive_request() */ abort();