Re: [Qemu-devel] [PATCH] block: Update image size in bdrv_invalidate_cache()

[Juan Quintela <quintela@redhat.com>]

Kevin Wolf <kwolf@redhat.com> wrote:
> After migration has completed, we call bdrv_invalidate_cache() so that
> drivers which cache some data drop their stale copy of the data and
> reread it from the image file to get a new version of data that the
> source modified while the migration was running.
>
> Reloading metadata from the image file is useless, though, if the size
> of the image file stays stale (this is a value that is cached for all
> image formats in block.c). Reads from (meta)data after the old EOF
> return only zeroes, causing image corruption.
>
> We need to update bs->total_sectors in all layers that could potentially
> have changed their size (i.e. backing files are not a concern - if they
> are changed, we're in bigger trouble)
>
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>

Reviewed-by: Juan Quintela <quintela@redhat.com>
Tested-by: Juan Quintela <quintela@redhat.com>

I had problems with migration with qcow2 files, and this fixes it.