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Re: [Nbd] [Qemu-devel] [PATCH 2/2] NBD proto: add GET_LBA_STATUS extension



Am 24.03.2016 um 17:04 hat Eric Blake geschrieben:
> On 03/24/2016 09:53 AM, Wouter Verhelst wrote:
> > On Thu, Mar 24, 2016 at 04:33:42PM +0100, Paolo Bonzini wrote:
> >> On 24/03/2016 16:25, Eric Blake wrote:
> >>>> However, let's make these bits, so that
> >>>>
> >>>> NBD_STATE_ALLOCATED (0x1), LBA extent is present on the block device
> >>>> NBD_STATE_ZERO (0x2), LBA extent will read as zeroes
> >>>
> >>> Should we flip the sense and call this NBD_STATE_UNALLOCATED (0 means
> >>> allocated, 1 means not present), so that an overall status of 0 is a
> >>> safe default?
> >>
> >> Double negations are evil (and don't work the same in all languages), so
> >> I think it's a worse option.
> > 
> > I agree that a bit which says "unallocated" is confusing in that manner,
> > but that just means we need a better name (one that doesn't contain
> > "un-" or "not")
> > 
> > I like the idea of having zero be the "sensible" default, although I'm
> > quite unable to come up with a better name myself.
> 
> NBD_STATE_TRIM, perhaps? (0 for present, 1 for trimmed or unallocated);
> matches well that we have NBD_CMD_TRIM for requesting the creation of
> such a state.

How about NBD_STATE_HOLE?

Kevin

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