From nobody Tue Feb 10 07:42:43 2026 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass(p=none dis=none) header.from=yandex-team.ru Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1656490810401104.18925515667206; Wed, 29 Jun 2022 01:20:10 -0700 (PDT) Received: from localhost ([::1]:34808 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1o6Svg-0003k9-J0 for importer@patchew.org; Wed, 29 Jun 2022 04:20:08 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:47724) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1o6Srb-0001C4-3v; Wed, 29 Jun 2022 04:15:55 -0400 Received: from forwardcorp1p.mail.yandex.net ([2a02:6b8:0:1472:2741:0:8b6:217]:41386) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1o6SrX-0006d9-4b; Wed, 29 Jun 2022 04:15:54 -0400 Received: from myt6-79704c0e15e4.qloud-c.yandex.net (myt6-79704c0e15e4.qloud-c.yandex.net [IPv6:2a02:6b8:c12:239b:0:640:7970:4c0e]) by forwardcorp1p.mail.yandex.net (Yandex) with ESMTP id F1DF42E0DA5; Wed, 29 Jun 2022 11:15:40 +0300 (MSK) Received: from myt6-81d8ab6a9f9d.qloud-c.yandex.net (myt6-81d8ab6a9f9d.qloud-c.yandex.net [2a02:6b8:c12:520a:0:640:81d8:ab6a]) by myt6-79704c0e15e4.qloud-c.yandex.net (mxbackcorp/Yandex) with ESMTP id VnUiuymng2-FeJCMXKj; Wed, 29 Jun 2022 11:15:40 +0300 Received: from vsementsov-win.yandex-team.ru (unknown [2a02:6b8:b081:232::1:2a]) by myt6-81d8ab6a9f9d.qloud-c.yandex.net (smtpcorp/Yandex) with ESMTPSA id 2dQcHHKpZi-FeMq3Olw; Wed, 29 Jun 2022 11:15:40 +0300 (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)) (Client certificate not present) X-Yandex-Fwd: 2 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yandex-team.ru; s=default; t=1656490540; bh=oqbbi5UHF2ABntWZBFnCzysXMTTmy6MfBtaQHnufEFc=; h=Message-Id:References:Date:Subject:In-Reply-To:Cc:To:From; b=mxhQwTZRIYjo5SAyEBojmlfSrWAqtbxWHPYpZODlVH/frjzlDFRvV9arCTFn5qudI kibzGDKFEHHp0I4zYjXexOHrcaUD7MNUp/VH2Xnm14AhpXX7cs5HGAq6rO7h+WNBfo J8Om0eX0qV3M1zoPX7r8ujmw1yTWsVzw7G2a9QH0= Authentication-Results: myt6-79704c0e15e4.qloud-c.yandex.net; dkim=pass header.i=@yandex-team.ru From: Vladimir Sementsov-Ogievskiy To: qemu-block@nongnu.org Cc: qemu-devel@nongnu.org, hreitz@redhat.com, vsementsov@yandex-team.ru, peter.maydell@linaro.org, Vladimir Sementsov-Ogievskiy Subject: [PULL v2 6/9] block/copy-before-write: implement cbw-timeout option Date: Wed, 29 Jun 2022 11:15:17 +0300 Message-Id: <20220629081517.446432-3-vsementsov@yandex-team.ru> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220629081517.446432-1-vsementsov@yandex-team.ru> References: <20220629081517.446432-1-vsementsov@yandex-team.ru> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.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; Received-SPF: pass client-ip=2a02:6b8:0:1472:2741:0:8b6:217; envelope-from=vsementsov@yandex-team.ru; helo=forwardcorp1p.mail.yandex.net X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: pass (identity @yandex-team.ru) X-ZM-MESSAGEID: 1656490812675100003 Content-Type: text/plain; charset="utf-8" From: Vladimir Sementsov-Ogievskiy In some scenarios, when copy-before-write operations lasts too long time, it's better to cancel it. Most useful would be to use the new option together with on-cbw-error=3Dbreak-snapshot: this way if cbw operation takes too long time we'll just cancel backup process but do not disturb the guest too much. Note the tricky point of realization: we keep additional point in bs->in_flight during block_copy operation even if it's timed-out. Background "cancelled" block_copy operations will finish at some point and will want to access state. We should care to not free the state in .bdrv_close() earlier. Signed-off-by: Vladimir Sementsov-Ogievskiy Reviewed-by: Hanna Reitz [vsementsov: use bdrv_inc_in_flight()/bdrv_dec_in_flight() instead of direct manipulation on bs->in_flight] Signed-off-by: Vladimir Sementsov-Ogievskiy --- block/copy-before-write.c | 22 +++++++++++++++++++++- qapi/block-core.json | 8 +++++++- 2 files changed, 28 insertions(+), 2 deletions(-) diff --git a/block/copy-before-write.c b/block/copy-before-write.c index fc13c7cd44..c24b8dd117 100644 --- a/block/copy-before-write.c +++ b/block/copy-before-write.c @@ -42,6 +42,7 @@ typedef struct BDRVCopyBeforeWriteState { BlockCopyState *bcs; BdrvChild *target; OnCbwError on_cbw_error; + uint32_t cbw_timeout_ns; =20 /* * @lock: protects access to @access_bitmap, @done_bitmap and @@ -83,6 +84,13 @@ static coroutine_fn int cbw_co_preadv( return bdrv_co_preadv(bs->file, offset, bytes, qiov, flags); } =20 +static void block_copy_cb(void *opaque) +{ + BlockDriverState *bs =3D opaque; + + bdrv_dec_in_flight(bs); +} + /* * Do copy-before-write operation. * @@ -111,7 +119,16 @@ static coroutine_fn int cbw_do_copy_before_write(Block= DriverState *bs, off =3D QEMU_ALIGN_DOWN(offset, cluster_size); end =3D QEMU_ALIGN_UP(offset + bytes, cluster_size); =20 - ret =3D block_copy(s->bcs, off, end - off, true, 0, NULL, NULL); + /* + * Increase in_flight, so that in case of timed-out block-copy, the + * remaining background block_copy() request (which can't be immediate= ly + * cancelled by timeout) is presented in bs->in_flight. This way we are + * sure that on bs close() we'll previously wait for all timed-out but= yet + * running block_copy calls. + */ + bdrv_inc_in_flight(bs); + ret =3D block_copy(s->bcs, off, end - off, true, s->cbw_timeout_ns, + block_copy_cb, bs); if (ret < 0 && s->on_cbw_error =3D=3D ON_CBW_ERROR_BREAK_GUEST_WRITE) { return ret; } @@ -377,6 +394,7 @@ static BlockdevOptions *cbw_parse_options(QDict *option= s, Error **errp) */ qdict_extract_subqdict(options, NULL, "bitmap"); qdict_del(options, "on-cbw-error"); + qdict_del(options, "cbw-timeout"); =20 out: visit_free(v); @@ -423,6 +441,8 @@ static int cbw_open(BlockDriverState *bs, QDict *option= s, int flags, } s->on_cbw_error =3D opts->has_on_cbw_error ? opts->on_cbw_error : ON_CBW_ERROR_BREAK_GUEST_WRITE; + s->cbw_timeout_ns =3D opts->has_cbw_timeout ? + opts->cbw_timeout * NANOSECONDS_PER_SECOND : 0; =20 bs->total_sectors =3D bs->file->bs->total_sectors; bs->supported_write_flags =3D BDRV_REQ_WRITE_UNCHANGED | diff --git a/qapi/block-core.json b/qapi/block-core.json index 3e8456a94a..2173e7734a 100644 --- a/qapi/block-core.json +++ b/qapi/block-core.json @@ -4227,12 +4227,18 @@ # @on-cbw-error: Behavior on failure of copy-before-write operation. # Default is @break-guest-write. (Since 7.1) # +# @cbw-timeout: Zero means no limit. Non-zero sets the timeout in seconds +# for copy-before-write operation. When a timeout occurs, +# the respective copy-before-write operation will fail, and +# the @on-cbw-error parameter will decide how this failure +# is handled. Default 0. (Since 7.1) +# # Since: 6.2 ## { 'struct': 'BlockdevOptionsCbw', 'base': 'BlockdevOptionsGenericFormat', 'data': { 'target': 'BlockdevRef', '*bitmap': 'BlockDirtyBitmap', - '*on-cbw-error': 'OnCbwError' } } + '*on-cbw-error': 'OnCbwError', '*cbw-timeout': 'uint32' } } =20 ## # @BlockdevOptions: --=20 2.25.1