On 04/04/2016 02:08 PM, Alex Bligh wrote: > > On 4 Apr 2016, at 21:04, Denis V. Lunev <den@...2317...> wrote: > >>> Sure, but given you can't report dirtiness without also reporting >>> allocation, if they are are at different blocksize I'd rather they >>> were in different commands, because otherwise the code to report >>> block size needs to work at two different granularities. >>> >> 'dirty' could come after the data was 'trimmed' from the region! >> thus we could have dirty unallocated data. > > Let me rephrase. > > Under the current proposal it is not possible to report whether or > not a region is dirty without also reporting whether or not it > is allocated. Huh? The current proposal _requires_ these to be separate queries. You cannot query dirtiness at the same time as allocation, because the value of NBD_CMD_FLAG_DIRTY is distinct between the two queries. > As these two concepts exist at potentially > different block sizes, the code to support reporting on allocation > must now be able to run both at the allocation blocksize and > the dirtiness blocksize, which is going to be a pain. No, the code for reporting allocation does NOT have to be run at the same time as when reporting dirtiness. > > If these were two different commands, they could each run at their > natural block size. Both modes of operation already can run at their natural block size. -- Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org
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