On Fri, Sep 25, 2020 at 03:32:48PM -0500, Eric Blake wrote:
> +The second is related to exposing the source of various extents within
> +the image, with a single context named:
> +
> +    qemu:allocation-depth
> +
> +In the allocation depth context, bits 0 and 1 form a tri-state value:
> +
> +    bits 0-1 clear: NBD_STATE_DEPTH_UNALLOC, means the extent is unallocated
> +    bit 0 set: NBD_STATE_DEPTH_LOCAL, the extent is allocated in this image
> +    bit 1 set: NBD_STATE_DEPTH_BACKING, the extent is inherited from a
> +               backing layer

>From the cover description I imagined it would show the actual depth, ie:

         top -> backing -> backing -> backing
 depth:   1        2         3   ....          (0 = unallocated)

I wonder if that is possible?  (Perhaps there's something I don't
understand here.)

Rich.

-- 
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