Re: [Qemu-devel] [PATCH v5 0/8] Add metadata overlap checks

[Eric Blake <eblake@redhat.com>]

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On 09/13/2013 08:29 AM, Max Reitz wrote:
> Another idea: Instead of providing an integer for "shorthand"
> manipulations, what do you think of a string parameter (such as -o
> cache=foo right now, although I do know -o cache isn't even document
> anymore and provided only for compatibility reasons, it seems to me)
> which will automatically be translated to the right settings? I'm
> thinking of:
>  - overlap-check=none (no checks at all)
>  - overlap-check=constant (only checks who can be performed in constant
> time, i.e., main header, active L1, refcount table and snapshot table)
>  - overlap-check=cached (only checks which don't require disk access,
> i.e. the current (and as I'd propose, future) default)
>  - overlap-check=all (all checks, including those requiring disk access
> (i.e., overlaps on inactive L2 tables))

Definitely a nice idea - saves the user from having to figure out which
checks have which impact, by categorizing the types of checks and only
exposing the categories.

> 
> These would then provide templates which can be further refined through
> the booleans (as is the case with -o cache right now).

Probably don't need that much fine-tuning; your categories look pretty
nice (although we may think of more categories if we do add additional
checks with different levels of execution time).

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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