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Re: [Qemu-block] [Qemu-devel] [PATCH v2 18/32] qcow2: Update qcow2_get_c
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From: |
Alberto Garcia |
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Subject: |
Re: [Qemu-block] [Qemu-devel] [PATCH v2 18/32] qcow2: Update qcow2_get_cluster_offset() to support L2 slices |
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Date: |
Fri, 19 Jan 2018 14:28:32 +0100 |
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User-agent: |
Notmuch/0.18.2 (http://notmuchmail.org) Emacs/24.4.1 (i586-pc-linux-gnu) |
On Tue 16 Jan 2018 11:42:45 PM CET, Eric Blake wrote:
> Callers like 'qemu-img map' will potentially have to iterate in more
> steps over an entire image; but that's not a severe limitation. The
> block_status() functions already document that as long as drivers make
> progress, callers must be prepared for back-to-back calls that return
> the same status, so you are not breaking semantics with a shorter
> clamping limit.
>
> Maybe some of that is worth mentioning in the commit message. Either
> way,
Yes indeed, for 4KB slices and 64KB clusters each slice can only map
32MB. Then again I don't think that it makes sense to change the slice
size for qemu-img map, or in general for anything that does pure
sequential I/O.
But it's probably worth mentioning in the commit message.
Berto