From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id B2249C25B76 for ; Mon, 3 Jun 2024 11:17:17 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1sE5gA-00039A-N8; Mon, 03 Jun 2024 07:16:42 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1sE5g9-00038P-7D for qemu-devel@nongnu.org; Mon, 03 Jun 2024 07:16:41 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1sE5g7-00067u-Cc for qemu-devel@nongnu.org; Mon, 03 Jun 2024 07:16:40 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1717413396; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=tZleCqpGh9AAHOxSQCX3G8XR+Y9SD8pRP1Phf4oGLbk=; b=MY89JXvaFXCiFZGO6OdHtSPgXV7m0G6FzMwZ7DCDnLdNVcl+7bJRLcJjBnGvAJS+qy1rBq AiQen/5yIcUo0Mgwq4XlC8omrjvnRyAOydm0LsuKDT76Hk8MkJnloV+c1Cx97Xol/hQPkA bcR8+LfNmxjev2HMNLz95fJleF4HM9w= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-610-0VBAzJTxNoahJl4mkkBUhA-1; Mon, 03 Jun 2024 07:16:32 -0400 X-MC-Unique: 0VBAzJTxNoahJl4mkkBUhA-1 Received: from smtp.corp.redhat.com (int-mx10.intmail.prod.int.rdu2.redhat.com [10.11.54.10]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 5427D85A58C; Mon, 3 Jun 2024 11:16:32 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.39.192.93]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 514874026B8; Mon, 3 Jun 2024 11:16:31 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 7258821E6757; Mon, 3 Jun 2024 13:16:30 +0200 (CEST) From: Markus Armbruster To: Fiona Ebner Cc: qemu-devel@nongnu.org, qemu-block@nongnu.org, eblake@redhat.com, hreitz@redhat.com, kwolf@redhat.com, vsementsov@yandex-team.ru, jsnow@redhat.com Subject: Re: [PATCH v2 1/2] copy-before-write: allow specifying minimum cluster size In-Reply-To: <20240528120114.344416-2-f.ebner@proxmox.com> (Fiona Ebner's message of "Tue, 28 May 2024 14:01:13 +0200") References: <20240528120114.344416-1-f.ebner@proxmox.com> <20240528120114.344416-2-f.ebner@proxmox.com> Date: Mon, 03 Jun 2024 13:16:30 +0200 Message-ID: <87h6eatgxd.fsf@pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.10 Received-SPF: pass client-ip=170.10.133.124; envelope-from=armbru@redhat.com; helo=us-smtp-delivery-124.mimecast.com 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, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=unavailable 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+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Fiona Ebner writes: > In the context of backup fleecing, discarding the source will not work > when the fleecing image has a larger granularity than the one used for > block-copy operations (can happen if the backup target has smaller > cluster size), because cbw_co_pdiscard_snapshot() will align down the > discard requests and thus effectively ignore then. > > To make @discard-source work in such a scenario, allow specifying the > minimum cluster size used for block-copy operations and thus in > particular also the granularity for discard requests to the source. > > The type 'size' (corresponding to uint64_t in C) is used in QAPI to > rule out negative inputs and for consistency with already existing > @cluster-size parameters. Since block_copy_calculate_cluster_size() > uses int64_t for its result, a check that the input is not too large > is added in block_copy_state_new() before calling it. The calculation > in block_copy_calculate_cluster_size() is done in the target int64_t > type. > > Suggested-by: Vladimir Sementsov-Ogievskiy > Signed-off-by: Fiona Ebner > --- > > Changes in v2: > * Use 'size' type in QAPI. > * Remove option in cbw_parse_options(), i.e. before parsing generic > blockdev options. > > block/block-copy.c | 22 ++++++++++++++++++---- > block/copy-before-write.c | 10 +++++++++- > include/block/block-copy.h | 1 + > qapi/block-core.json | 8 +++++++- > 4 files changed, 35 insertions(+), 6 deletions(-) > > diff --git a/block/block-copy.c b/block/block-copy.c > index 7e3b378528..36eaecaaf4 100644 > --- a/block/block-copy.c > +++ b/block/block-copy.c > @@ -310,6 +310,7 @@ void block_copy_set_copy_opts(BlockCopyState *s, bool use_copy_range, > } > > static int64_t block_copy_calculate_cluster_size(BlockDriverState *target, > + int64_t min_cluster_size, > Error **errp) > { > int ret; > @@ -335,7 +336,7 @@ static int64_t block_copy_calculate_cluster_size(BlockDriverState *target, > "used. If the actual block size of the target exceeds " > "this default, the backup may be unusable", > BLOCK_COPY_CLUSTER_SIZE_DEFAULT); > - return BLOCK_COPY_CLUSTER_SIZE_DEFAULT; > + return MAX(min_cluster_size, (int64_t)BLOCK_COPY_CLUSTER_SIZE_DEFAULT); BLOCK_COPY_CLUSTER_SIZE_DEFAULT gets promoted from int to min_cluster_size's type int64_t even without the cast. The cast makes it explicit. Matter of taste, and I'm not the maintainer here :) > } else if (ret < 0 && !target_does_cow) { > error_setg_errno(errp, -ret, > "Couldn't determine the cluster size of the target image, " > @@ -345,16 +346,18 @@ static int64_t block_copy_calculate_cluster_size(BlockDriverState *target, > return ret; > } else if (ret < 0 && target_does_cow) { > /* Not fatal; just trudge on ahead. */ > - return BLOCK_COPY_CLUSTER_SIZE_DEFAULT; > + return MAX(min_cluster_size, (int64_t)BLOCK_COPY_CLUSTER_SIZE_DEFAULT); Likewise. > } > > - return MAX(BLOCK_COPY_CLUSTER_SIZE_DEFAULT, bdi.cluster_size); > + return MAX(min_cluster_size, > + (int64_t)MAX(BLOCK_COPY_CLUSTER_SIZE_DEFAULT, bdi.cluster_size)); Likewise. > } > > BlockCopyState *block_copy_state_new(BdrvChild *source, BdrvChild *target, > BlockDriverState *copy_bitmap_bs, > const BdrvDirtyBitmap *bitmap, > bool discard_source, > + uint64_t min_cluster_size, > Error **errp) > { > ERRP_GUARD(); > @@ -365,7 +368,18 @@ BlockCopyState *block_copy_state_new(BdrvChild *source, BdrvChild *target, > > GLOBAL_STATE_CODE(); > > - cluster_size = block_copy_calculate_cluster_size(target->bs, errp); > + if (min_cluster_size > INT64_MAX) { > + error_setg(errp, "min-cluster-size too large: %lu > %ld", > + min_cluster_size, INT64_MAX); > + return NULL; > + } else if (min_cluster_size && !is_power_of_2(min_cluster_size)) { > + error_setg(errp, "min-cluster-size needs to be a power of 2"); > + return NULL; > + } > + > + cluster_size = block_copy_calculate_cluster_size(target->bs, > + (int64_t)min_cluster_size, > + errp); This is now more obviously safe. Thanks! > if (cluster_size < 0) { > return NULL; > } > diff --git a/block/copy-before-write.c b/block/copy-before-write.c > index cd65524e26..ef0bc4dcfe 100644 > --- a/block/copy-before-write.c > +++ b/block/copy-before-write.c > @@ -417,6 +417,7 @@ static BlockdevOptions *cbw_parse_options(QDict *options, Error **errp) > qdict_extract_subqdict(options, NULL, "bitmap"); > qdict_del(options, "on-cbw-error"); > qdict_del(options, "cbw-timeout"); > + qdict_del(options, "min-cluster-size"); > > out: > visit_free(v); > @@ -432,6 +433,7 @@ static int cbw_open(BlockDriverState *bs, QDict *options, int flags, > BDRVCopyBeforeWriteState *s = bs->opaque; > BdrvDirtyBitmap *bitmap = NULL; > int64_t cluster_size; > + uint64_t min_cluster_size = 0; > g_autoptr(BlockdevOptions) full_opts = NULL; > BlockdevOptionsCbw *opts; > int ret; > @@ -476,8 +478,14 @@ static int cbw_open(BlockDriverState *bs, QDict *options, int flags, > bs->file->bs->supported_zero_flags); > > s->discard_source = flags & BDRV_O_CBW_DISCARD_SOURCE; > + > + if (opts->has_min_cluster_size) { > + min_cluster_size = opts->min_cluster_size; > + } > + > s->bcs = block_copy_state_new(bs->file, s->target, bs, bitmap, > - flags & BDRV_O_CBW_DISCARD_SOURCE, errp); > + flags & BDRV_O_CBW_DISCARD_SOURCE, > + min_cluster_size, errp); > if (!s->bcs) { > error_prepend(errp, "Cannot create block-copy-state: "); > return -EINVAL; You can pass opts->min_cluster_size directly, as in v1. When !opts->has_min_cluster_size, then opts->min_cluster_size is zero. > diff --git a/include/block/block-copy.h b/include/block/block-copy.h > index bdc703bacd..dd5cc82f3b 100644 > --- a/include/block/block-copy.h > +++ b/include/block/block-copy.h > @@ -28,6 +28,7 @@ BlockCopyState *block_copy_state_new(BdrvChild *source, BdrvChild *target, > BlockDriverState *copy_bitmap_bs, > const BdrvDirtyBitmap *bitmap, > bool discard_source, > + uint64_t min_cluster_size, > Error **errp); > > /* Function should be called prior any actual copy request */ > diff --git a/qapi/block-core.json b/qapi/block-core.json > index df5e07debd..8fc0a4b234 100644 > --- a/qapi/block-core.json > +++ b/qapi/block-core.json > @@ -4642,12 +4642,18 @@ > # @on-cbw-error parameter will decide how this failure is handled. > # Default 0. (Since 7.1) > # > +# @min-cluster-size: Minimum size of blocks used by copy-before-write > +# operations. Has to be a power of 2. No effect if smaller than > +# the maximum of the target's cluster size and 64 KiB. Default 0. > +# (Since 9.1) > +# > # Since: 6.2 > ## > { 'struct': 'BlockdevOptionsCbw', > 'base': 'BlockdevOptionsGenericFormat', > 'data': { 'target': 'BlockdevRef', '*bitmap': 'BlockDirtyBitmap', > - '*on-cbw-error': 'OnCbwError', '*cbw-timeout': 'uint32' } } > + '*on-cbw-error': 'OnCbwError', '*cbw-timeout': 'uint32', > + '*min-cluster-size': 'size' } } > > ## > # @BlockdevOptions: QAPI schema Acked-by: Markus Armbruster