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=1565894324; cv=none; d=zoho.com; s=zohoarc; b=Ez/+1hayZeztLPhtJwagaXX07efgu2e1BAauES17ThDJ4sj8uH8Z5QGu7GHX1h5kp3mbYG9rKlIFOQcR7fYky3dXFj4G9o7GN6z9w2njEJl5k3+L3RY+ja8xc4sOCtv1DjZmkXv1wk92POMcUYRIEGIZky7mxdIqSNs9jaiSh84= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zoho.com; s=zohoarc; t=1565894324; 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=faIlNUqR7zIzCordVtQTr5pf6hC295KkPLnm5WkUMdI=; b=lwgJ7t9uxDrOvfvwmsntwYqc0bOg9p5L3xfWvrdA7l6B2gxvJ1zh14yXAmbO2gKijTR4y0O4l9tGwaxqSL9Nhvll0DJykaYVE+QBkM2+nf1YnZnC7UNdPKV3noLozhzbwztrUHg/Ry5xb+PDYFB1veEHbOvISRd5liErpn7xHpc= 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 (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1565894324161144.09418217679377; Thu, 15 Aug 2019 11:38:44 -0700 (PDT) Received: from localhost ([::1]:46132 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1hyKe2-0000pC-TH for importer@patchew.org; Thu, 15 Aug 2019 14:38:42 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:37566) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1hyKXC-00030o-HO for qemu-devel@nongnu.org; Thu, 15 Aug 2019 14:31:41 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hyKX6-0001s3-9t for qemu-devel@nongnu.org; Thu, 15 Aug 2019 14:31:38 -0400 Received: from mx1.redhat.com ([209.132.183.28]:35732) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hyKWz-0001db-Cp; 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 9497DC0BAA0D; Thu, 15 Aug 2019 18:31:21 +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 8CF5E8388F; Thu, 15 Aug 2019 18:30:53 +0000 (UTC) From: Eric Blake To: qemu-devel@nongnu.org Date: Thu, 15 Aug 2019 13:30:32 -0500 Message-Id: <20190815183039.4264-3-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 [10.5.110.31]); Thu, 15 Aug 2019 18:31:21 +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 2/9] block: implement 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: Fam Zheng , Kevin Wolf , Vladimir Sementsov-Ogievskiy , "open list:Block I/O path" , Max Reitz , 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 Do effective copy-on-read request when we don't need data actually. It will be used for block-stream and NBD_CMD_CACHE. Signed-off-by: Vladimir Sementsov-Ogievskiy Message-Id: <20190725100550.33801-2-vsementsov@virtuozzo.com> Reviewed-by: Stefan Hajnoczi [eblake: comment grammar fix] Signed-off-by: Eric Blake --- include/block/block.h | 8 +++++++- block/io.c | 18 ++++++++++++------ 2 files changed, 19 insertions(+), 7 deletions(-) diff --git a/include/block/block.h b/include/block/block.h index 50a07c1c3385..a9df34ff94b6 100644 --- a/include/block/block.h +++ b/include/block/block.h @@ -88,8 +88,14 @@ typedef enum { * fallback. */ BDRV_REQ_NO_FALLBACK =3D 0x100, + /* + * BDRV_REQ_PREFETCH may be used only together with BDRV_REQ_COPY_ON_R= EAD + * on read request and means that caller doesn't really need data to be + * written to qiov parameter which may be NULL. + */ + BDRV_REQ_PREFETCH =3D 0x200, /* Mask of valid flags */ - BDRV_REQ_MASK =3D 0x1ff, + BDRV_REQ_MASK =3D 0x3ff, } BdrvRequestFlags; typedef struct BlockSizes { diff --git a/block/io.c b/block/io.c index 06305c6ea62e..9d99858b554b 100644 --- a/block/io.c +++ b/block/io.c @@ -1167,7 +1167,8 @@ bdrv_driver_pwritev_compressed(BlockDriverState *bs, = uint64_t offset, } static int coroutine_fn bdrv_co_do_copy_on_readv(BdrvChild *child, - int64_t offset, unsigned int bytes, QEMUIOVector *qiov) + int64_t offset, unsigned int bytes, QEMUIOVector *qiov, + int flags) { BlockDriverState *bs =3D child->bs; @@ -1278,9 +1279,11 @@ static int coroutine_fn bdrv_co_do_copy_on_readv(Bdr= vChild *child, goto err; } - qemu_iovec_from_buf(qiov, progress, bounce_buffer + skip_bytes, - pnum - skip_bytes); - } else { + if (!(flags & BDRV_REQ_PREFETCH)) { + qemu_iovec_from_buf(qiov, progress, bounce_buffer + skip_b= ytes, + pnum - skip_bytes); + } + } else if (!(flags & BDRV_REQ_PREFETCH)) { /* Read directly into the destination */ qemu_iovec_init(&local_qiov, qiov->niov); qemu_iovec_concat(&local_qiov, qiov, progress, pnum - skip_byt= es); @@ -1331,7 +1334,8 @@ static int coroutine_fn bdrv_aligned_preadv(BdrvChild= *child, * potential fallback support, if we ever implement any read flags * to pass through to drivers. For now, there aren't any * passthrough flags. */ - assert(!(flags & ~(BDRV_REQ_NO_SERIALISING | BDRV_REQ_COPY_ON_READ))); + assert(!(flags & ~(BDRV_REQ_NO_SERIALISING | BDRV_REQ_COPY_ON_READ | + BDRV_REQ_PREFETCH))); /* Handle Copy on Read and associated serialisation */ if (flags & BDRV_REQ_COPY_ON_READ) { @@ -1359,7 +1363,9 @@ static int coroutine_fn bdrv_aligned_preadv(BdrvChild= *child, } if (!ret || pnum !=3D bytes) { - ret =3D bdrv_co_do_copy_on_readv(child, offset, bytes, qiov); + ret =3D bdrv_co_do_copy_on_readv(child, offset, bytes, qiov, f= lags); + goto out; + } else if (flags & BDRV_REQ_PREFETCH) { goto out; } } --=20 2.20.1