From patchwork Fri Oct 11 21:25:45 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: John Snow X-Patchwork-Id: 11186425 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id DA6AF15AB for ; Fri, 11 Oct 2019 21:49:24 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id B775B2084C for ; Fri, 11 Oct 2019 21:49:24 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B775B2084C Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Received: from localhost ([::1]:57368 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iJ2mp-0008E7-AW for patchwork-qemu-devel@patchwork.kernel.org; Fri, 11 Oct 2019 17:49:23 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:55395) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iJ2Ri-0003hu-Uw for qemu-devel@nongnu.org; Fri, 11 Oct 2019 17:27:36 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1iJ2Rh-0001PY-Cw for qemu-devel@nongnu.org; Fri, 11 Oct 2019 17:27:34 -0400 Received: from mx1.redhat.com ([209.132.183.28]:48880) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1iJ2Rb-0001Nx-PR; Fri, 11 Oct 2019 17:27:27 -0400 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 0480118CB906; Fri, 11 Oct 2019 21:27:27 +0000 (UTC) Received: from probe.bos.redhat.com (dhcp-17-173.bos.redhat.com [10.18.17.173]) by smtp.corp.redhat.com (Postfix) with ESMTP id A11631EC; Fri, 11 Oct 2019 21:27:25 +0000 (UTC) From: John Snow To: Peter Maydell , qemu-devel@nongnu.org Subject: [PULL 14/19] block/qcow2-bitmap: do not remove bitmaps on reopen-ro Date: Fri, 11 Oct 2019 17:25:45 -0400 Message-Id: <20191011212550.27269-15-jsnow@redhat.com> In-Reply-To: <20191011212550.27269-1-jsnow@redhat.com> References: <20191011212550.27269-1-jsnow@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.6.2 (mx1.redhat.com [10.5.110.63]); Fri, 11 Oct 2019 21:27:27 +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 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 , qemu-block@nongnu.org, Juan Quintela , libvir-list@redhat.com, John Snow , "Dr. David Alan Gilbert" , Max Reitz , Stefan Hajnoczi , Markus Armbruster Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" From: Vladimir Sementsov-Ogievskiy qcow2_reopen_bitmaps_ro wants to store bitmaps and then mark them all readonly. But the latter don't work, as qcow2_store_persistent_dirty_bitmaps removes bitmaps after storing. It's OK for inactivation but bad idea for reopen-ro. And this leads to the following bug: Assume we have persistent bitmap 'bitmap0'. Create external snapshot bitmap0 is stored and therefore removed Commit snapshot now we have no bitmaps Do some writes from guest (*) they are not marked in bitmap Shutdown Start bitmap0 is loaded as valid, but it is actually broken! It misses writes (*) Incremental backup it will be inconsistent So, let's stop removing bitmaps on reopen-ro. But don't rejoice: reopening bitmaps to rw is broken too, so the whole scenario will not work after this patch and we can't enable corresponding test cases in 260 iotests still. Reopening bitmaps rw will be fixed in the following patches. Signed-off-by: Vladimir Sementsov-Ogievskiy Reviewed-by: John Snow Message-id: 20190927122355.7344-7-vsementsov@virtuozzo.com Signed-off-by: John Snow --- block/qcow2.h | 3 ++- block/qcow2-bitmap.c | 49 ++++++++++++++++++++++++++++++-------------- block/qcow2.c | 2 +- 3 files changed, 37 insertions(+), 17 deletions(-) diff --git a/block/qcow2.h b/block/qcow2.h index b3398a13c20..8d293f2b64e 100644 --- a/block/qcow2.h +++ b/block/qcow2.h @@ -739,7 +739,8 @@ Qcow2BitmapInfoList *qcow2_get_bitmap_info_list(BlockDriverState *bs, Error **errp); int qcow2_reopen_bitmaps_rw(BlockDriverState *bs, Error **errp); int qcow2_truncate_bitmaps_check(BlockDriverState *bs, Error **errp); -void qcow2_store_persistent_dirty_bitmaps(BlockDriverState *bs, Error **errp); +void qcow2_store_persistent_dirty_bitmaps(BlockDriverState *bs, + bool release_stored, Error **errp); int qcow2_reopen_bitmaps_ro(BlockDriverState *bs, Error **errp); bool qcow2_co_can_store_new_dirty_bitmap(BlockDriverState *bs, const char *name, diff --git a/block/qcow2-bitmap.c b/block/qcow2-bitmap.c index ebc1afccd3d..f7dfb40256e 100644 --- a/block/qcow2-bitmap.c +++ b/block/qcow2-bitmap.c @@ -1440,7 +1440,32 @@ out: return ret; } -void qcow2_store_persistent_dirty_bitmaps(BlockDriverState *bs, Error **errp) +/* + * qcow2_store_persistent_dirty_bitmaps + * + * Stores persistent BdrvDirtyBitmap objects. + * + * @release_stored: if true, release BdrvDirtyBitmap's after storing to the + * image. This is used in two cases, both via qcow2_inactivate: + * 1. bdrv_close: It's correct to remove bitmaps on close. + * 2. migration: If bitmaps are migrated through migration channel via + * 'dirty-bitmaps' migration capability they are not handled by this code. + * Otherwise, it's OK to drop BdrvDirtyBitmap's and reload them on + * invalidation. + * + * Anyway, it's correct to remove BdrvDirtyBitmap's on inactivation, as + * inactivation means that we lose control on disk, and therefore on bitmaps, + * we should sync them and do not touch more. + * + * Contrariwise, we don't want to release any bitmaps on just reopen-to-ro, + * when we need to store them, as image is still under our control, and it's + * good to keep all the bitmaps in read-only mode. Moreover, keeping them + * read-only is correct because this is what would happen if we opened the node + * readonly to begin with, and whether we opened directly or reopened to that + * state shouldn't matter for the state we get afterward. + */ +void qcow2_store_persistent_dirty_bitmaps(BlockDriverState *bs, + bool release_stored, Error **errp) { BdrvDirtyBitmap *bitmap; BDRVQcow2State *s = bs->opaque; @@ -1551,20 +1576,14 @@ void qcow2_store_persistent_dirty_bitmaps(BlockDriverState *bs, Error **errp) g_free(tb); } - QSIMPLEQ_FOREACH(bm, bm_list, entry) { - /* For safety, we remove bitmap after storing. - * We may be here in two cases: - * 1. bdrv_close. It's ok to drop bitmap. - * 2. inactivation. It means migration without 'dirty-bitmaps' - * capability, so bitmaps are not marked with - * BdrvDirtyBitmap.migration flags. It's not bad to drop them too, - * and reload on invalidation. - */ - if (bm->dirty_bitmap == NULL) { - continue; - } + if (release_stored) { + QSIMPLEQ_FOREACH(bm, bm_list, entry) { + if (bm->dirty_bitmap == NULL) { + continue; + } - bdrv_release_dirty_bitmap(bm->dirty_bitmap); + bdrv_release_dirty_bitmap(bm->dirty_bitmap); + } } success: @@ -1592,7 +1611,7 @@ int qcow2_reopen_bitmaps_ro(BlockDriverState *bs, Error **errp) BdrvDirtyBitmap *bitmap; Error *local_err = NULL; - qcow2_store_persistent_dirty_bitmaps(bs, &local_err); + qcow2_store_persistent_dirty_bitmaps(bs, false, &local_err); if (local_err != NULL) { error_propagate(errp, local_err); return -EINVAL; diff --git a/block/qcow2.c b/block/qcow2.c index 43a6cc423de..7ab1aad9779 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -2359,7 +2359,7 @@ static int qcow2_inactivate(BlockDriverState *bs) int ret, result = 0; Error *local_err = NULL; - qcow2_store_persistent_dirty_bitmaps(bs, &local_err); + qcow2_store_persistent_dirty_bitmaps(bs, true, &local_err); if (local_err != NULL) { result = -EINVAL; error_reportf_err(local_err, "Lost persistent bitmaps during "