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Re: [PATCH 2/3] nbd: Add new qemu:allocation-depth metacontext
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From: |
Richard W.M. Jones |
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Subject: |
Re: [PATCH 2/3] nbd: Add new qemu:allocation-depth metacontext |
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Date: |
Sat, 26 Sep 2020 08:33:08 +0100 |
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User-agent: |
Mutt/1.5.21 (2010-09-15) |
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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