From patchwork Wed Nov 30 01:18:29 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Max Reitz X-Patchwork-Id: 700804 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 3tT2lv47V2z9t0t for ; Wed, 30 Nov 2016 12:25:15 +1100 (AEDT) Received: from localhost ([::1]:40166 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cBte5-0004Mg-EJ for incoming@patchwork.ozlabs.org; Tue, 29 Nov 2016 20:25:13 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:54179) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cBtYB-0007ZN-2s for qemu-devel@nongnu.org; Tue, 29 Nov 2016 20:19:08 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cBtYA-000640-1P for qemu-devel@nongnu.org; Tue, 29 Nov 2016 20:19:07 -0500 Received: from mx1.redhat.com ([209.132.183.28]:52398) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1cBtY7-00062K-7Y; Tue, 29 Nov 2016 20:19:03 -0500 Received: from int-mx13.intmail.prod.int.phx2.redhat.com (int-mx13.intmail.prod.int.phx2.redhat.com [10.5.11.26]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 6739EC05678F; Wed, 30 Nov 2016 01:19:02 +0000 (UTC) Received: from localhost (ovpn-116-36.phx2.redhat.com [10.3.116.36]) by int-mx13.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id uAU1J0mv019445 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO); Tue, 29 Nov 2016 20:19:01 -0500 From: Max Reitz To: qemu-block@nongnu.org Date: Wed, 30 Nov 2016 02:18:29 +0100 Message-Id: <20161130011851.24696-4-mreitz@redhat.com> In-Reply-To: <20161130011851.24696-1-mreitz@redhat.com> References: <20161130011851.24696-1-mreitz@redhat.com> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.26 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.32]); Wed, 30 Nov 2016 01:19:02 +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 v3 03/25] block: Add BDS.backing_overridden 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 , Alberto Garcia , qemu-devel@nongnu.org, Max Reitz Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" If the backing file is overridden, this most probably does change the guest-visible data of a BDS. Therefore, we will need to consider this in bdrv_refresh_filename(). Adding a new field to the BDS is not nice, but it is very simple and exactly keeps track of whether the backing file has been overridden. This commit adds a FIXME which will be remedied by a follow-up commit. Until then, the respective piece of code will not result in any behavior that is worse than what we currently have. Signed-off-by: Max Reitz Reviewed-by: Eric Blake --- block.c | 13 +++++++++++++ block/mirror.c | 4 ++++ blockdev.c | 16 ++++++++++++++++ include/block/block_int.h | 1 + 4 files changed, 34 insertions(+) diff --git a/block.c b/block.c index 1615f5d..438201d 100644 --- a/block.c +++ b/block.c @@ -1495,6 +1495,11 @@ int bdrv_open_backing_file(BlockDriverState *bs, QDict *parent_options, reference = qdict_get_try_str(parent_options, bdref_key); if (reference || qdict_haskey(options, "file.filename")) { backing_filename[0] = '\0'; + + /* FIXME: Should also be set to true if @options contains other runtime + * options which control the data that is read from the backing + * BDS */ + bs->backing_overridden = true; } else if (bs->backing_file[0] == '\0' && qdict_size(options) == 0) { QDECREF(options); goto free_exit; @@ -1659,6 +1664,9 @@ static BlockDriverState *bdrv_append_temp_snapshot(BlockDriverState *bs, bdrv_ref(bs_snapshot); bdrv_append(bs_snapshot, bs); + bs_snapshot->backing_overridden = true; + bdrv_refresh_filename(bs_snapshot); + g_free(tmp_filename); return bs_snapshot; @@ -1786,6 +1794,7 @@ static BlockDriverState *bdrv_open_inherit(const char *filename, backing = qdict_get_try_str(options, "backing"); if (backing && *backing == '\0') { flags |= BDRV_O_NO_BACKING; + bs->backing_overridden = true; qdict_del(options, "backing"); } @@ -3959,6 +3968,10 @@ void bdrv_refresh_filename(BlockDriverState *bs) * refresh those first */ QLIST_FOREACH(child, &bs->children, next) { bdrv_refresh_filename(child->bs); + + if (child->role == &child_backing && child->bs->backing_overridden) { + bs->backing_overridden = true; + } } if (drv->bdrv_refresh_filename) { diff --git a/block/mirror.c b/block/mirror.c index 4ece624..6cb6cbd 100644 --- a/block/mirror.c +++ b/block/mirror.c @@ -891,6 +891,10 @@ static void mirror_complete(BlockJob *job, Error **errp) assert(!target->backing); bdrv_set_backing_hd(target, backing); + + /* The target image's file already has been created with the backing + * file we just set, so there is no need to set backing_overridden or + * call bdrv_refresh_filename(). */ } s->should_complete = true; diff --git a/blockdev.c b/blockdev.c index 245e1e1..7889bab 100644 --- a/blockdev.c +++ b/blockdev.c @@ -1771,6 +1771,8 @@ static void external_snapshot_commit(BlkActionState *common) { ExternalSnapshotState *state = DO_UPCAST(ExternalSnapshotState, common, common); + TransactionAction *action = common->action; + bool image_was_existing = false; bdrv_set_aio_context(state->new_bs, state->aio_context); @@ -1783,6 +1785,20 @@ static void external_snapshot_commit(BlkActionState *common) bdrv_reopen(state->old_bs, state->old_bs->open_flags & ~BDRV_O_RDWR, NULL); } + + if (action->type == TRANSACTION_ACTION_KIND_BLOCKDEV_SNAPSHOT_SYNC) { + BlockdevSnapshotSync *s = action->u.blockdev_snapshot_sync.data; + if (s->has_mode && s->mode == NEW_IMAGE_MODE_EXISTING) { + image_was_existing = true; + } + } else { + image_was_existing = true; + } + + if (image_was_existing) { + state->new_bs->backing_overridden = true; + bdrv_refresh_filename(state->new_bs); + } } static void external_snapshot_abort(BlkActionState *common) diff --git a/include/block/block_int.h b/include/block/block_int.h index 83a423c..555f3c2 100644 --- a/include/block/block_int.h +++ b/include/block/block_int.h @@ -461,6 +461,7 @@ struct BlockDriverState { char backing_file[PATH_MAX]; /* if non zero, the image is a diff of this file image */ char backing_format[16]; /* if non-zero and backing_file exists */ + bool backing_overridden; /* backing file has been specified by the user */ QDict *full_open_options; char exact_filename[PATH_MAX];