On 1/9/19 1:21 PM, Eric Blake wrote: > Revisiting an older thread: > > On 6/9/18 10:17 AM, Vladimir Sementsov-Ogievskiy wrote: >> Handle new NBD meta namespace: "qemu", and corresponding queries: >> "qemu:dirty-bitmap:<export bitmap name>". >> >> With new metadata context negotiated, BLOCK_STATUS query will reply >> with dirty-bitmap data, converted to extents. New public function >> nbd_export_bitmap selects bitmap to export. For now, only one bitmap >> may be exported. >>
>> + if (bdrv_dirty_bitmap_enabled(bm)) {
>> + error_setg(errp, "Bitmap '%s' is enabled", bitmap);
>> + return;
>> + }
>
> Why are we restricting things to only export disabled bitmaps?
>
> I can understand the argument that if the image being exported is
> read-only, then an enabled bitmap _that can be changed_ is probably a
> bad idea (it goes against the notion of the export being read only).
> But if we were to allow a writable access to an image, wouldn't we
> expect that writes be reflected into the bitmap, which means permitting
> an enabled bitmap?
I've now addressed this in my v2 Promote x-nbd-server-add-bitmap to
stable series.
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3226
Virtualization: qemu.org | libvirt.org
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