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Re: [Qemu-devel] [PATCH 2/3] block: Add 'blockdev-del' QMP command
From: |
Alberto Garcia |
Subject: |
Re: [Qemu-devel] [PATCH 2/3] block: Add 'blockdev-del' QMP command |
Date: |
Mon, 19 Oct 2015 16:20:13 +0200 |
User-agent: |
Notmuch/0.13.2 (http://notmuchmail.org) Emacs/23.2.1 (i486-pc-linux-gnu) |
On Sat 17 Oct 2015 08:06:19 PM CEST, Max Reitz wrote:
>> + if (blk_get_refcnt(blk) > 1 ||
>> + (bs && (bs->refcnt > 1 || !QLIST_EMPTY(&bs->parents)))) {
>> + error_setg(errp, "Block device %s is being used", device);
>> + goto out;
>> + }
>
> I can't think of a way off the top of my head that a BB with a refcount
> of one or a BDS with a refcount of one without any parents would not be
> monitor-owned, but I don't quite like assuming it just from the refcount
> and the parent list anyway.
I agree, I would also like to have a clearer way to do it.
I'll try to go over all possible ways to create a BDS and see other
cases that I might have missed. At the very list I would like to extend
the iotest and make it as comprehensive as possible.
> The two patches which are significant for this patch are:
> - "blockdev: Keep track of monitor-owned BDS" from the first series
> - "blockdev: Add list of monitor-owned BlockBackends" from the second
>
> Explaining what they do and why they are relevant to this patch doesn't
> really seem necessary, but anyway: They add one list for the
> monitor-owned BDSs and one for the monitor-owned BBs.
Yeah, those would be handy indeed.
> It's up to you. It probably works just how you implemented it, and
> considering the pace of the "BB and media" series (and other series of
> mine in the past year), getting those two series merged may be a
> matter of decades. So it's probably best to do it like this for now
> and I'll fix it up then...
I think I'll first try to go over all possible cases and see what I
find.
Thanks,
Berto