Re: [Qemu-block] [Qemu-devel] [PATCH 3/6] bloc/qcow2: drop dirty_bitmaps_loaded state variable

[Vladimir Sementsov-Ogievskiy]

10.07.2018 02:25, John Snow wrote:
> On 06/26/2018 09:50 AM, Vladimir Sementsov-Ogievskiy wrote:
> > This variable doesn't work as it should, because it is actually cleared
> > in qcow2_co_invalidate_cache() by memset(). Drop it, as the following
> > patch will introduce new behavior.
> >
> > Signed-off-by: Vladimir Sementsov-Ogievskiy <address@hidden>
> > ---
> >   block/qcow2.h |  1 -
> >   block/qcow2.c | 19 ++-----------------
> >   2 files changed, 2 insertions(+), 18 deletions(-)
> >
> > diff --git a/block/qcow2.h b/block/qcow2.h
> > index 01b5250415..c9df19b6e6 100644
> > --- a/block/qcow2.h
> > +++ b/block/qcow2.h
> > @@ -294,7 +294,6 @@ typedef struct BDRVQcow2State {
> >       uint32_t nb_bitmaps;
> >       uint64_t bitmap_directory_size;
> >       uint64_t bitmap_directory_offset;
> > -    bool dirty_bitmaps_loaded;
> >   
> >       int flags;
> >       int qcow_version;
> > diff --git a/block/qcow2.c b/block/qcow2.c
> > index 46194a33ca..0044ff58e7 100644
> > --- a/block/qcow2.c
> > +++ b/block/qcow2.c
> > @@ -1149,7 +1149,6 @@ static int coroutine_fn qcow2_do_open(BlockDriverState 
> > *bs, QDict *options,
> >       uint64_t ext_end;
> >       uint64_t l1_vm_state_index;
> >       bool update_header = false;
> > -    bool header_updated = false;
> >   
> >       ret = bdrv_pread(bs->file, 0, &header, sizeof(header));
> >       if (ret < 0) {
> > @@ -1488,23 +1487,9 @@ static int coroutine_fn qcow2_do_open(BlockDriverState 
> > *bs, QDict *options,
> >           s->autoclear_features &= QCOW2_AUTOCLEAR_MASK;
> >       }
> >   
> > -    if (s->dirty_bitmaps_loaded) {
> > -        /* It's some kind of reopen. There are no known cases where we need to
> > -         * reload bitmaps in such a situation, so it's safer to skip them.
> > -         *
> > -         * Moreover, if we have some readonly bitmaps and we are reopening for
> > -         * rw we should reopen bitmaps correspondingly.
> > -         */
> > -        if (bdrv_has_readonly_bitmaps(bs) &&
> > -            !bdrv_is_read_only(bs) && !(bdrv_get_flags(bs) & BDRV_O_INACTIVE))
> > -        {
> > -            qcow2_reopen_bitmaps_rw_hint(bs, &header_updated, &local_err);
> > -        }
> > -    } else {
> > -        header_updated = qcow2_load_dirty_bitmaps(bs, &local_err);
> > -        s->dirty_bitmaps_loaded = true;
> > +    if (qcow2_load_dirty_bitmaps(bs, &local_err)) {
> > +        update_header = false;
> >       }
> > -    update_header = update_header && !header_updated;
> >       if (local_err != NULL) {
> >           error_propagate(errp, local_err);
> >           ret = -EINVAL;
> Usually I'd like to see the new behavior introduced before removing the
> old, imperfect solution... (it doesn't make any tests fail!? ...)
>
> At this point in the series I just have to trust that you will fix it to
> be better :)

As I understand, this field is actually always false, so it's safe to 
drop it.

> --js


--
Best regards,
Vladimir