Re: [Qemu-block] [PATCH 23/24] qcow2: add .bdrv_remove_persistent_dirty_bitmap

[Vladimir Sementsov-Ogievskiy]

01.02.2017 16:57, Vladimir Sementsov-Ogievskiy wrote:
> 01.02.2017 02:20, Max Reitz wrote:
> > On 23.01.2017 13:10, Vladimir Sementsov-Ogievskiy wrote:
> > > Realize .bdrv_remove_persistent_dirty_bitmap interface.
> > >
> > > Signed-off-by: Vladimir Sementsov-Ogievskiy <address@hidden>
> > > ---
> > >   block/qcow2-bitmap.c | 40 ++++++++++++++++++++++++++++++++++++++++
> > >   block/qcow2.c        |  1 +
> > >   block/qcow2.h        |  3 +++
> > >   3 files changed, 44 insertions(+)
> > >
> > > diff --git a/block/qcow2-bitmap.c b/block/qcow2-bitmap.c
> > > index 2687a3acd5..be026fc80e 100644
> > > --- a/block/qcow2-bitmap.c
> > > +++ b/block/qcow2-bitmap.c
> > > @@ -1064,6 +1064,46 @@ static Qcow2Bitmap 
> > > *find_bitmap_by_name(Qcow2BitmapList *bm_list,
> > >       return NULL;
> > >   }
> > >   +void qcow2_remove_persistent_dirty_bitmap(BlockDriverState *bs,
> > > +                                          const char *name,
> > > +                                          Error **errp)
> > > +{
> > > +    int ret;
> > > +    BDRVQcow2State *s = bs->opaque;
> > > +    Qcow2Bitmap *bm;
> > > +    Qcow2BitmapList *bm_list;
> > > +
> > > +    if (s->nb_bitmaps == 0) {
> > > +        /* No bitmaps - nothing to do */
> > Shouldn't it be an error? I.e. "bitmap not found"?
> >
> > > +        return;
> > > +    }
> > > +
> > > +    bm_list = bitmap_list_load(bs, s->bitmap_directory_offset,
> > > +                               s->bitmap_directory_size, errp);
> > > +    if (bm_list == NULL) {
> > > +        return;
> > > +    }
> > > +
> > > +    bm = find_bitmap_by_name(bm_list, name);
> > > +    if (bm == NULL) {
> > > +        goto fail;
> > What about setting errp? Or do you not consider this an error?
> >
> > I think it should be an error.
>
> Hmm. The following scenery should not be an error:
> 1. qmp create dirty bitmap with persistent = true (bitmap not exists 
> and not created  in the storage, it will be saved only on storage close)
> 2. qmp remove dirty bitmap. persistent = true, so we will try to 
> remove it from storage..
>
> So, I see following variants:
> 1. as is, just add comment "remove if exists"
> 2. add return value to this function, return ENOENT if bitmap not 
> found and ignore this ENOENT in qmp_remove_bitmap
> 3. add additional bool field 'exist_in_storage' to BdrvDirtyBitmap.

Also, I can call remove_persistent...() from 
bdrv_dirty_bitmap_set_persistance( ..., false), and use this function in 
qmp block-remove-dirty-bitmap

> > > +    }
> > > +
> > > +    QSIMPLEQ_REMOVE(bm_list, bm, Qcow2Bitmap, entry);
> > bm->name is leaked here.
> >
> > Max
> >
> > > +
> > > +    ret = update_ext_header_and_dir(bs, bm_list);
> > > +    if (ret < 0) {
> > > +        error_setg_errno(errp, -ret, "Failed to update bitmap 
> > > extension");
> > > +        goto fail;
> > > +    }
> > > +
> > > +    free_bitmap_clusters(bs, &bm->table);
> > > +
> > > +fail:
> > > +    bitmap_free(bm);
> > > +    bitmap_list_free(bm_list);
> > > +}
> > > +
> > >   void qcow2_store_persistent_dirty_bitmaps(BlockDriverState *bs, 
> > > Error **errp)
> > >   {
> > >       BdrvDirtyBitmap *bitmap;
> > > diff --git a/block/qcow2.c b/block/qcow2.c
> > > index 76a6a2ba28..f6bac38e51 100644
> > > --- a/block/qcow2.c
> > > +++ b/block/qcow2.c
> > > @@ -3544,6 +3544,7 @@ BlockDriver bdrv_qcow2 = {
> > >       .bdrv_load_autoloading_dirty_bitmaps = 
> > > qcow2_load_autoloading_dirty_bitmaps,
> > >       .bdrv_store_persistent_dirty_bitmaps = 
> > > qcow2_store_persistent_dirty_bitmaps,
> > >       .bdrv_can_store_new_dirty_bitmap = 
> > > qcow2_can_store_new_dirty_bitmap,
> > > +    .bdrv_remove_persistent_dirty_bitmap = 
> > > qcow2_remove_persistent_dirty_bitmap,
> > >   };
> > >     static void bdrv_qcow2_init(void)
> > > diff --git a/block/qcow2.h b/block/qcow2.h
> > > index eaad34a527..a009827f60 100644
> > > --- a/block/qcow2.h
> > > +++ b/block/qcow2.h
> > > @@ -627,5 +627,8 @@ bool 
> > > qcow2_can_store_new_dirty_bitmap(BlockDriverState *bs,
> > >   int qcow2_check_bitmaps_refcounts(BlockDriverState *bs, 
> > > BdrvCheckResult *res,
> > >                                     void **refcount_table,
> > >                                     int64_t *refcount_table_size);
> > > +void qcow2_remove_persistent_dirty_bitmap(BlockDriverState *bs,
> > > +                                          const char *name,
> > > +                                          Error **errp);
> > >     #endif


--
Best regards,
Vladimir