Re: [Qemu-devel] [PATCH v15 13/25] qcow2: add .bdrv_store_persistent_dirty_bitmaps()

[Vladimir Sementsov-Ogievskiy]

16.02.2017 17:08, Kevin Wolf wrote:
> Am 15.02.2017 um 11:10 hat Vladimir Sementsov-Ogievskiy geschrieben:
> > Realize block bitmap storing interface, to allow qcow2 images store
> > persistent bitmaps.
> >
> > Signed-off-by: Vladimir Sementsov-Ogievskiy <address@hidden>
> > Reviewed-by: Max Reitz <address@hidden>
> > Reviewed-by: John Snow <address@hidden>
> Similary to autoload, I think this must be called as part of
> qcow2_inactivate() rather than just in bdrv_close().
>
> Kevin

I prefer to store bitmaps once, on the final close of bds, and remove 
corresponding BdrvDirtyBitmap in the same point. bdrv_close is simpler 
point, I don't want to think about loading/saving bitmap on each 
invalidate/inactivate. I don't want to make dependencies between qcow2 
bitmap loading/storing and migration, etc.

So, my approach was just load bitmap on bdrv_open and store on 
bdrv_close, and between these two calls BdrvDirtyBitmap lives its normal 
life. For me it looks simpler. I'm not sure about what new corner cases 
will come if we change this.


--
Best regards,
Vladimir