From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:39525) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fSrVu-00058q-BK for qemu-devel@nongnu.org; Tue, 12 Jun 2018 18:11:43 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fSrVt-0003Mo-CT for qemu-devel@nongnu.org; Tue, 12 Jun 2018 18:11:42 -0400 References: <20180612172614.60107-1-vsementsov@virtuozzo.com> From: John Snow Message-ID: Date: Tue, 12 Jun 2018 18:11:35 -0400 MIME-Version: 1.0 In-Reply-To: <20180612172614.60107-1-vsementsov@virtuozzo.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [Qemu-block] [PATCH] block/qcow2: fix logic around dirty_bitmaps_loaded List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Vladimir Sementsov-Ogievskiy , qemu-devel@nongnu.org, qemu-block@nongnu.org Cc: kwolf@redhat.com, den@openvz.org, mreitz@redhat.com On 06/12/2018 01:26 PM, Vladimir Sementsov-Ogievskiy wrote: > First: this variable was introduced to handle reopens. We need it on > following qcow2_do_open, to don't try loading bitmaps again. So, we are > fixing qcow2_invalidate_cache(). > > However, if we fix only qcow2_invalidate_cache, iotest 169 fails on > case test__persistent__not_migbitmap__online_shared, because on first > target open, source is not yet closed, and is not yet stored bitmaps, > so, we are load nothing. And on second open, dirty_bitmaps_loaded is > already true, but we have no bitmaps to reopen with > qcow2_reopen_bitmaps_rw_hint(). So, we are fixing qcow2_do_open() too. > > Signed-off-by: Vladimir Sementsov-Ogievskiy > --- > block/qcow2.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/block/qcow2.c b/block/qcow2.c > index 6fa5e1d71a..b4216a5830 100644 > --- a/block/qcow2.c > +++ b/block/qcow2.c > @@ -1499,7 +1499,7 @@ static int coroutine_fn qcow2_do_open(BlockDriverState *bs, QDict *options, > { > qcow2_reopen_bitmaps_rw_hint(bs, &header_updated, &local_err); > } > - } else { > + } else if (s->nb_bitmaps > 0) { > header_updated = qcow2_load_dirty_bitmaps(bs, &local_err); > s->dirty_bitmaps_loaded = true; > } > @@ -2178,6 +2178,7 @@ static void coroutine_fn qcow2_co_invalidate_cache(BlockDriverState *bs, > QDict *options; > Error *local_err = NULL; > int ret; > + bool dirty_bitmaps_loaded = s->dirty_bitmaps_loaded; > > /* > * Backing files are read-only which makes all of their metadata immutable, > @@ -2190,6 +2191,7 @@ static void coroutine_fn qcow2_co_invalidate_cache(BlockDriverState *bs, > qcow2_close(bs); > > memset(s, 0, sizeof(BDRVQcow2State)); > + s->dirty_bitmaps_loaded = dirty_bitmaps_loaded; > options = qdict_clone_shallow(bs->options); > > flags &= ~BDRV_O_INACTIVE; > Ah, tch... I didn't realize that invalidate completely wipes the qcow2 metadata. I guess the other three fields, nb_bitmaps, bitmap_directory_size and bitmap_directory_offset get initialized again on re-open. (I suppose this means I need to rethink caching bm_list more carefully, too...) I think this looks correct mechanically.