Re: [Qemu-devel] [PATCH v2] block/dirty-bitmap: Documentation and Comment fixups

[Eric Blake <eblake@redhat.com>]

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On 2/1/19 7:10 PM, John Snow wrote:
> The meaning of the states has changed subtly over time,
> this should bring the understanding more in-line with the
> current, actual usages.
> 
> Reported-by: Eric Blake <eblake@redhat.com>
> Signed-off-by: John Snow <jsnow@redhat.com>
> 
> ---
> V2: Amended some wordings, though this is a little chatty now.
>     Hopefully it's clearer, though.
> ---

>  /**
> - * A BdrvDirtyBitmap can be in three possible states:
> - * (1) successor is NULL and disabled is false: full r/w mode
> - * (2) successor is NULL and disabled is true: read only mode ("disabled")
> - * (3) successor is set: frozen mode.
> - *     A frozen bitmap cannot be renamed, deleted, anonymized, cleared, set,
> - *     or enabled. A frozen bitmap can only abdicate() or reclaim().
> + * A BdrvDirtyBitmap can be in four possible user-visible states:
> + * (1) Active:   successor is NULL, and disabled is false: full r/w mode
> + * (2) Disabled: successor is NULL, and disabled is true: qualified r/w mode,
> + *               guest writes are dropped, but monitor writes are possible,
> + *               through commands like merge and clear.
> + * (3) Frozen:   successor is not NULL.
> + *               A frozen bitmap cannot be renamed, deleted, cleared, set,
> + *               enabled, merged to, etc. A frozen bitmap can only abdicate()
> + *               or reclaim().
> + *               In this state, the anonymous successor bitmap may be either
> + *               Active and recording writes from the guest (e.g. backup jobs),
> + *               but it can be Disabled and not recording writes.

s/but/or/

> + * (4) Locked:   Whether Active or Disabled, the user cannot modify this bitmap
> + *               in any way from the monitor.

Worth a parenthetical comment mentioning NBD export as a possible reason
for Locked to be visible?

With the one word fix,
Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org


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