From nobody Wed Nov 5 14:57:45 2025 Delivered-To: importer@patchew.org Received-SPF: pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) client-ip=208.118.235.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zoho.com; spf=pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; Return-Path: Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) by mx.zohomail.com with SMTPS id 1497361147561268.4291954300378; Tue, 13 Jun 2017 06:39:07 -0700 (PDT) Received: from localhost ([::1]:43327 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dKm2C-0005zR-VA for importer@patchew.org; Tue, 13 Jun 2017 09:39:05 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:48359) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dKlxB-0001QP-NY for qemu-devel@nongnu.org; Tue, 13 Jun 2017 09:33:55 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dKlxA-0000Wr-B8 for qemu-devel@nongnu.org; Tue, 13 Jun 2017 09:33:53 -0400 Received: from mx1.redhat.com ([209.132.183.28]:36711) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1dKlxA-0000WW-19 for qemu-devel@nongnu.org; Tue, 13 Jun 2017 09:33:52 -0400 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 0BBB175EA1; Tue, 13 Jun 2017 13:33:51 +0000 (UTC) Received: from localhost (ovpn-117-200.ams2.redhat.com [10.36.117.200]) by smtp.corp.redhat.com (Postfix) with ESMTP id 339E1A3942; Tue, 13 Jun 2017 13:33:44 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 0BBB175EA1 Authentication-Results: ext-mx04.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx04.extmail.prod.ext.phx2.redhat.com; spf=pass smtp.mailfrom=stefanha@redhat.com DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.redhat.com 0BBB175EA1 From: Stefan Hajnoczi To: qemu-devel@nongnu.org Date: Tue, 13 Jun 2017 14:33:23 +0100 Message-Id: <20170613133329.23653-4-stefanha@redhat.com> In-Reply-To: <20170613133329.23653-1-stefanha@redhat.com> References: <20170613133329.23653-1-stefanha@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.28]); Tue, 13 Jun 2017 13:33:51 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PATCH v7 3/9] qcow2: extract preallocation calculation function 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 , John Snow , Nir Soffer , Maor Lipchuk , Stefan Hajnoczi , Alberto Garcia Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail: RSF_0 Z_629925259 SPT_0 Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Calculating the preallocated image size will be needed to implement .bdrv_measure(). Extract the code out into a separate function. Signed-off-by: Stefan Hajnoczi Reviewed-by: Alberto Garcia --- block/qcow2.c | 136 +++++++++++++++++++++++++++++++++---------------------= ---- 1 file changed, 77 insertions(+), 59 deletions(-) diff --git a/block/qcow2.c b/block/qcow2.c index b3ba5da..22b261a 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -2096,6 +2096,80 @@ static int preallocate(BlockDriverState *bs) return 0; } =20 +/** + * qcow2_calc_prealloc_size: + * @total_size: virtual disk size in bytes + * @cluster_size: cluster size in bytes + * @refcount_order: refcount bits power-of-2 exponent + * + * Returns: Total number of bytes required for the fully allocated image + * (including metadata). + */ +static int64_t qcow2_calc_prealloc_size(int64_t total_size, + size_t cluster_size, + int refcount_order) +{ + /* Note: The following calculation does not need to be exact; if it is= a + * bit off, either some bytes will be "leaked" (which is fine) or we + * will need to increase the file size by some bytes (which is fine, + * too, as long as the bulk is allocated here). Therefore, using + * floating point arithmetic is fine. */ + int64_t meta_size =3D 0; + uint64_t nreftablee, nrefblocke, nl1e, nl2e, refblock_count; + int64_t aligned_total_size =3D align_offset(total_size, cluster_size); + int cluster_bits =3D ctz32(cluster_size); + int refblock_bits, refblock_size; + /* refcount entry size in bytes */ + double rces =3D (1 << refcount_order) / 8.; + + /* see qcow2_open() */ + refblock_bits =3D cluster_bits - (refcount_order - 3); + refblock_size =3D 1 << refblock_bits; + + /* header: 1 cluster */ + meta_size +=3D cluster_size; + + /* total size of L2 tables */ + nl2e =3D aligned_total_size / cluster_size; + nl2e =3D align_offset(nl2e, cluster_size / sizeof(uint64_t)); + meta_size +=3D nl2e * sizeof(uint64_t); + + /* total size of L1 tables */ + nl1e =3D nl2e * sizeof(uint64_t) / cluster_size; + nl1e =3D align_offset(nl1e, cluster_size / sizeof(uint64_t)); + meta_size +=3D nl1e * sizeof(uint64_t); + + /* total size of refcount blocks + * + * note: every host cluster is reference-counted, including metadata + * (even refcount blocks are recursively included). + * Let: + * a =3D total_size (this is the guest disk size) + * m =3D meta size not including refcount blocks and refcount tables + * c =3D cluster size + * y1 =3D number of refcount blocks entries + * y2 =3D meta size including everything + * rces =3D refcount entry size in bytes + * then, + * y1 =3D (y2 + a)/c + * y2 =3D y1 * rces + y1 * rces * sizeof(u64) / c + m + * we can get y1: + * y1 =3D (a + m) / (c - rces - rces * sizeof(u64) / c) + */ + nrefblocke =3D (aligned_total_size + meta_size + cluster_size) + / (cluster_size - rces - rces * sizeof(uint64_t) + / cluster_size); + refblock_count =3D DIV_ROUND_UP(nrefblocke, refblock_size); + meta_size +=3D refblock_count * cluster_size; + + /* total size of refcount tables */ + nreftablee =3D align_offset(refblock_count, + cluster_size / sizeof(uint64_t)); + meta_size +=3D nreftablee * sizeof(uint64_t); + + return meta_size + aligned_total_size; +} + static int qcow2_create2(const char *filename, int64_t total_size, const char *backing_file, const char *backing_for= mat, int flags, size_t cluster_size, PreallocMode prea= lloc, @@ -2134,65 +2208,9 @@ static int qcow2_create2(const char *filename, int64= _t total_size, int ret; =20 if (prealloc =3D=3D PREALLOC_MODE_FULL || prealloc =3D=3D PREALLOC_MOD= E_FALLOC) { - /* Note: The following calculation does not need to be exact; if i= t is a - * bit off, either some bytes will be "leaked" (which is fine) or = we - * will need to increase the file size by some bytes (which is fin= e, - * too, as long as the bulk is allocated here). Therefore, using - * floating point arithmetic is fine. */ - int64_t meta_size =3D 0; - uint64_t nreftablee, nrefblocke, nl1e, nl2e, refblock_count; - int64_t aligned_total_size =3D align_offset(total_size, cluster_si= ze); - int refblock_bits, refblock_size; - /* refcount entry size in bytes */ - double rces =3D (1 << refcount_order) / 8.; - - /* see qcow2_open() */ - refblock_bits =3D cluster_bits - (refcount_order - 3); - refblock_size =3D 1 << refblock_bits; - - /* header: 1 cluster */ - meta_size +=3D cluster_size; - - /* total size of L2 tables */ - nl2e =3D aligned_total_size / cluster_size; - nl2e =3D align_offset(nl2e, cluster_size / sizeof(uint64_t)); - meta_size +=3D nl2e * sizeof(uint64_t); - - /* total size of L1 tables */ - nl1e =3D nl2e * sizeof(uint64_t) / cluster_size; - nl1e =3D align_offset(nl1e, cluster_size / sizeof(uint64_t)); - meta_size +=3D nl1e * sizeof(uint64_t); - - /* total size of refcount blocks - * - * note: every host cluster is reference-counted, including metada= ta - * (even refcount blocks are recursively included). - * Let: - * a =3D total_size (this is the guest disk size) - * m =3D meta size not including refcount blocks and refcount ta= bles - * c =3D cluster size - * y1 =3D number of refcount blocks entries - * y2 =3D meta size including everything - * rces =3D refcount entry size in bytes - * then, - * y1 =3D (y2 + a)/c - * y2 =3D y1 * rces + y1 * rces * sizeof(u64) / c + m - * we can get y1: - * y1 =3D (a + m) / (c - rces - rces * sizeof(u64) / c) - */ - nrefblocke =3D (aligned_total_size + meta_size + cluster_size) - / (cluster_size - rces - rces * sizeof(uint64_t) - / cluster_size); - refblock_count =3D DIV_ROUND_UP(nrefblocke, refblock_size); - meta_size +=3D refblock_count * cluster_size; - - /* total size of refcount tables */ - nreftablee =3D align_offset(refblock_count, - cluster_size / sizeof(uint64_t)); - meta_size +=3D nreftablee * sizeof(uint64_t); - - qemu_opt_set_number(opts, BLOCK_OPT_SIZE, - aligned_total_size + meta_size, &error_abort); + int64_t prealloc_size =3D + qcow2_calc_prealloc_size(total_size, cluster_size, refcount_or= der); + qemu_opt_set_number(opts, BLOCK_OPT_SIZE, prealloc_size, &error_ab= ort); qemu_opt_set(opts, BLOCK_OPT_PREALLOC, PreallocMode_lookup[preallo= c], &error_abort); } --=20 2.9.4