On Thu, Jan 16, 2020 at 05:38:03PM +0200, Maxim Levitsky wrote: > How about doing write zeros without discard only in this particular case > (convert to existing image) > Basically omitting the BDRV_REQ_MAY_UNMAP flag to blk_co_pwrite_zeroes. > It will be slow, but maybe for this particular case, it is acceptable?
I should probably say that we don't want to break the other case (which is likely more important) where we write a sparse source to a sparse target and want the target to contain only the union of the two sparse maps, not fully allocated :-) It would be fine, I think, to have a new "make this disk fully allocated" operation. qemu-img resize could almost do it with a request to add 0 extra bytes, but the --preallocation flag only applies to the new space. Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com virt-top is 'top' for virtual machines. Tiny program with many powerful monitoring features, net stats, disk stats, logging, etc. http://people.redhat.com/~rjones/virt-top
