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Date: Fri, 26 Apr 2013 16:34:18 +0200
From: Stefan Hajnoczi <stefanha@gmail.com>
Message-ID: <20130426143418.GA7648@stefanha-thinkpad.redhat.com>
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Subject: Re: [Qemu-devel] [PATCH 4/7] block: distinguish id and name in
 bdrv_find_snapshot()
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To: Wenchao Xia <xiawenc@linux.vnet.ibm.com>
Cc: kwolf@redhat.com, phrdina@redhat.com, armbru@redhat.com, qemu-devel@nongnu.org, lcapitulino@redhat.com, pbonzini@redhat.com

On Fri, Apr 26, 2013 at 05:31:12PM +0800, Wenchao Xia wrote:
> To make it clear about id and name in searching, the API is changed
> a bit to distinguish them, and caller can choose to search by id or name.
> If not found, *errp will be set to tip why.
> 
> Note that the caller logic is changed a bit:
> 1) In del_existing_snapshots() called by do_savevm(), it travers twice

s/travers/traverse/

Also in comments in the code.

> to find the snapshot, instead once, so matching sequence may change
> if there are unwisely chosen, mixed id and names.
> 2) In do_savevm(), same with del_existing_snapshot(), when it tries to
> find the snapshot to overwrite, matching sequence may change for same
> reason.
> 3) In load_vmstate(), first when it tries to find the snapshot to be loaded,
> sequence may change for the same reason of above. Later in validation, the
> logic is changed to be more strict to require both id and name matching.
> 4) In do_info_snapshot(), in validation, the logic is changed to be more
> strict to require both id and name matching.

It's easy to avoid changing semantics: keep the old name or id behavior
around.  Use the new name-and-id behavior for #3 and #4.

Please include a justification for breaking the search order.