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 <vsement...@virtuozzo.com>
> ---
> 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.