From nobody Sat Jul 25 22:02:26 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=quarantine dis=none) header.from=dupond.be ARC-Seal: i=1; a=rsa-sha256; t=1783930495; cv=none; d=zohomail.com; s=zohoarc; b=mrtwewhT99GKmOSj84UdZZW/NHd+AWRJuvPXE8ZrMvJyMVW+IRBWUxq45nH2z+9YsLI4CgWBqJTYzUMK+BWy7+KAEqbzhPTTMWR2wENTFS6buNNw9+0XJschmQCRgK80O5BRmYojixhbkwpPQ5H6m3ROqt7rzDTpmZasPorZ4O0= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1783930495; h=Content-Transfer-Encoding:Cc:Cc:Date:Date:From:From:In-Reply-To:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:MIME-Version:Message-ID:References:Sender:Subject:Subject:To:To:Message-Id:Reply-To; bh=oHvdZ4QXwg5tsTGPKn5aT8Ew9GbiFOg2iCrJuLWkoRw=; b=lEPMXPMNHgjJc5NIXhaOhSdaWYajs19/hPZ6TEXdxV61rcqxzvJhpPu4wDCsaJ/OottWRqqoZKC9nscV24m9WxB7o1IHbKDBb+m8R/Isq1ZOhrNSzcacQyeaMTL5EK5+rEzud9+0ZTHvUar/xgxU8eYrdMCwewCPtrCGDSGF9cU= ARC-Authentication-Results: i=1; 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 header.from= (p=quarantine dis=none) Return-Path: Received: from lists1p.gnu.org (lists1p.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1783930494927309.6126683464197; Mon, 13 Jul 2026 01:14:54 -0700 (PDT) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists1p.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1wjBnW-0006a6-Us; Mon, 13 Jul 2026 04:13:54 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists1p.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1wjBnM-0006QY-CK; Mon, 13 Jul 2026 04:13:50 -0400 Received: from apollo.dupie.be ([2001:bc8:3f2a:101::1]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1wjBnC-0006xG-Rb; Mon, 13 Jul 2026 04:13:44 -0400 Received: from lt-jeanlouis (unknown [IPv6:2a02:a03f:fafb:301:46c3:62e6:fe62:23a1]) by apollo.dupie.be (Postfix) with ESMTPSA id 51B161520F75; Mon, 13 Jul 2026 10:13:27 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=dupond.be; s=dkim; t=1783930407; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=oHvdZ4QXwg5tsTGPKn5aT8Ew9GbiFOg2iCrJuLWkoRw=; b=jmJaE0VVMKjmfgZKDQJt64JMtc8WE0Dz93S2lp0nkd5B7ML28zo3VjRmaysJWUWgiy6U3J Bsc+Y789QYOkm9L+95m2rAt+nPZf5FNKB/S6iU2XRV2+N1VsABZNwkOaLi3bu97yPH97nd ghzjCyyD8Pg3HC2QljFOvx+KSFdhU4en8j0s3nGHVg4rkN435Fc77VI0zadbos5/eCqeex ldhYiiE8f4xyuFBtY1DjgnvmHdlJ5lZrlphlccaUpVVrlbP5dTg8vo1OsQoCtxT7Yxz4TF AB0SXJaSpKOiSf65br3VDXX62UJ5hULHT388g9bE9JEqx+8MFYs4riITEgegoQ== From: Jean-Louis Dupond To: qemu-devel@nongnu.org Cc: Vladimir Sementsov-Ogievskiy , Hanna Reitz , Eric Blake , qemu-block@nongnu.org, John Snow , Kevin Wolf , Jean-Louis Dupond Subject: [PATCH v6 1/1] qcow2: add functionality to repair bitmaps Date: Mon, 13 Jul 2026 10:13:04 +0200 Message-ID: <20260713081304.84812-2-jean-louis@dupond.be> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260713081304.84812-1-jean-louis@dupond.be> References: <20260713081304.84812-1-jean-louis@dupond.be> 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=lists1p.gnu.org; Received-SPF: pass client-ip=2001:bc8:3f2a:101::1; envelope-from=jean-louis@dupond.be; helo=apollo.dupie.be 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 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: qemu development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @dupond.be) X-ZM-MESSAGEID: 1783930499309158500 Content-Type: text/plain; charset="utf-8" In some cases, it might happen that bitmaps become corrupt. For example when adding/removing bitmaps on a live image. Of course this should not happen, but in case this happens, the image is corrupt and even cannot be opened anymore. You'll get something like the following: qemu-img: Could not open 'disk.qcow2': Bitmap '' doesn't satisfy the constr= aints So the image becomes useless, and cannot be repaired. This while in fact only (one) bitmap entry is corrupt, and the rest of the data is just intact. This commit adds a way to fix this corruption, by just replacing the bitmap list in the qcow2 image with the valid bitmaps, and dropping the bitmaps that are corrupt. $ qemu-img check disk.qcow2 qemu-img: Check failed: Invalid argument qemu-img: Lost persistent bitmaps during inactivation of node '#block147': = Bitmap '' doesn't satisfy the constraints $ qemu-img check -r all disk.qcow2 qcow2_free_clusters failed: Invalid argument Leaked cluster 3 refcount=3D1 reference=3D0 Leaked cluster 26 refcount=3D1 reference=3D0 ERROR cluster 983214 refcount=3D0 reference=3D1 Rebuilding refcount structure Repairing cluster 1 refcount=3D1 reference=3D0 Repairing cluster 2 refcount=3D1 reference=3D0 Repairing cluster 32768 refcount=3D1 reference=3D0 .... Repairing cluster 983214 refcount=3D1 reference=3D0 The following inconsistencies were found and repaired: 2 leaked clusters 3 corruptions Double checking the fixed image now... No errors were found on the image. 983056/1048576 =3D 93.75% allocated, 0.05% fragmented, 0.00% compressed clu= sters Image end offset: 64437878784 And the image is valid again! Worst case you lose all bitmaps, but at least the image and the data itself is useable again. Signed-off-by: Jean-Louis Dupond --- block/qcow2-bitmap.c | 42 +++++++++++++++++++++++++++++++++++++++--- block/qcow2-refcount.c | 3 ++- block/qcow2.c | 16 ++++++++++++---- block/qcow2.h | 3 ++- 4 files changed, 55 insertions(+), 9 deletions(-) diff --git a/block/qcow2-bitmap.c b/block/qcow2-bitmap.c index 256ec99878..91bd82a9f5 100644 --- a/block/qcow2-bitmap.c +++ b/block/qcow2-bitmap.c @@ -100,6 +100,9 @@ typedef enum BitmapType { BT_DIRTY_TRACKING_BITMAP =3D 1 } BitmapType; =20 +static int GRAPH_RDLOCK +update_ext_header_and_dir(BlockDriverState *bs, Qcow2BitmapList *bm_list); + static inline bool can_write(BlockDriverState *bs) { return !bdrv_is_read_only(bs) && !(bdrv_get_flags(bs) & BDRV_O_INACTIV= E); @@ -655,12 +658,14 @@ fail: int coroutine_fn qcow2_check_bitmaps_refcounts(BlockDriverState *bs, BdrvCheckResult *res, void **refcount_table, - int64_t *refcount_table_size) + int64_t *refcount_table_size, + BdrvCheckMode fix) { int ret; BDRVQcow2State *s =3D bs->opaque; Qcow2BitmapList *bm_list; - Qcow2Bitmap *bm; + Qcow2Bitmap *bm, *bm_next; + bool bitmap_modified =3D false; =20 if (s->nb_bitmaps =3D=3D 0) { return 0; @@ -677,12 +682,21 @@ qcow2_check_bitmaps_refcounts(BlockDriverState *bs, B= drvCheckResult *res, s->bitmap_directory_size, NULL); if (bm_list =3D=3D NULL) { res->corruptions++; + + if (fix & BDRV_FIX_ERRORS) { + ret =3D update_ext_header_and_dir(bs, NULL); + if (ret >=3D 0) { + res->corruptions_fixed++; + } + goto out; + } return -EINVAL; } =20 - QSIMPLEQ_FOREACH(bm, bm_list, entry) { + QSIMPLEQ_FOREACH_SAFE(bm, bm_list, entry, bm_next) { uint64_t *bitmap_table =3D NULL; int i; + bool bitmap_valid =3D true; =20 ret =3D qcow2_inc_refcounts_imrt(bs, res, refcount_table, refcount_table_size, @@ -695,6 +709,12 @@ qcow2_check_bitmaps_refcounts(BlockDriverState *bs, Bd= rvCheckResult *res, ret =3D bitmap_table_load(bs, &bm->table, &bitmap_table); if (ret < 0) { res->corruptions++; + if (fix & BDRV_FIX_ERRORS) { + QSIMPLEQ_REMOVE(bm_list, bm, Qcow2Bitmap, entry); + bitmap_free(bm); + bitmap_modified =3D true; + continue; + } goto out; } =20 @@ -704,6 +724,7 @@ qcow2_check_bitmaps_refcounts(BlockDriverState *bs, Bdr= vCheckResult *res, =20 if (check_table_entry(entry, s->cluster_size) < 0) { res->corruptions++; + bitmap_valid =3D false; continue; } =20 @@ -720,9 +741,24 @@ qcow2_check_bitmaps_refcounts(BlockDriverState *bs, Bd= rvCheckResult *res, } } =20 + if ((fix & BDRV_FIX_ERRORS) && !bitmap_valid) { + QSIMPLEQ_REMOVE(bm_list, bm, Qcow2Bitmap, entry); + bitmap_free(bm); + bitmap_modified =3D true; + } + g_free(bitmap_table); } =20 + /* If fixing, update the bitmap directory with the repaired list */ + if ((fix & BDRV_FIX_ERRORS) && bitmap_modified) { + uint32_t initial_bitmaps =3D s->nb_bitmaps; + ret =3D update_ext_header_and_dir(bs, bm_list); + if (ret >=3D 0) { + res->corruptions_fixed +=3D initial_bitmaps - s->nb_bitmaps; + } + } + out: bitmap_list_free(bm_list); =20 diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c index 6512cda407..df7f6d2f23 100644 --- a/block/qcow2-refcount.c +++ b/block/qcow2-refcount.c @@ -2305,7 +2305,8 @@ calculate_refcounts(BlockDriverState *bs, BdrvCheckRe= sult *res, } =20 /* bitmaps */ - ret =3D qcow2_check_bitmaps_refcounts(bs, res, refcount_table, nb_clus= ters); + ret =3D qcow2_check_bitmaps_refcounts(bs, res, refcount_table, + nb_clusters, fix); if (ret < 0) { return ret; } diff --git a/block/qcow2.c b/block/qcow2.c index 19271b10a4..d6aa1cd3a4 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -1927,11 +1927,19 @@ qcow2_do_open(BlockDriverState *bs, QDict *options,= int flags, if (!(bdrv_get_flags(bs) & BDRV_O_INACTIVE)) { /* It's case 1, 2 or 3.2. Or 3.1 which is BUG in management layer.= */ bool header_updated; - if (!qcow2_load_dirty_bitmaps(bs, &header_updated, errp)) { - ret =3D -EINVAL; - goto fail; + Error *local_err =3D NULL; + if (!qcow2_load_dirty_bitmaps(bs, &header_updated, &local_err)) { + /* + * Allow this to fail in check mode + * because otherwise we can't open the image at all. + */ + if (!(flags & BDRV_O_CHECK)) { + ret =3D -EINVAL; + error_propagate(errp, local_err); + goto fail; + } + error_free(local_err); } - update_header =3D update_header && !header_updated; } =20 diff --git a/block/qcow2.h b/block/qcow2.h index ce517040c4..ba9fe68130 100644 --- a/block/qcow2.h +++ b/block/qcow2.h @@ -1038,7 +1038,8 @@ void qcow2_cache_discard(Qcow2Cache *c, void *table); int coroutine_fn GRAPH_RDLOCK qcow2_check_bitmaps_refcounts(BlockDriverState *bs, BdrvCheckResult *res, void **refcount_table, - int64_t *refcount_table_size); + int64_t *refcount_table_size, + BdrvCheckMode fix); =20 bool coroutine_fn GRAPH_RDLOCK qcow2_load_dirty_bitmaps(BlockDriverState *bs, bool *header_updated, --=20 2.55.0