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From: Max Reitz <mreitz@redhat.com>
To: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>,
	qemu-block@nongnu.org
Cc: kwolf@redhat.com, qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [PATCH] block: fix permission update in bdrv_replace_node
Date: Mon, 26 Aug 2019 13:21:55 +0200	[thread overview]
Message-ID: <01661ed8-9bf5-4d1e-5637-2669d4df23a3@redhat.com> (raw)
In-Reply-To: <20190824100740.61635-1-vsementsov@virtuozzo.com>


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On 24.08.19 12:07, Vladimir Sementsov-Ogievskiy wrote:
> It's wrong to OR shared permissions. It may lead to crash on further
> permission updates.
> Also, no needs to consider previously calculated permissions, as at
> this point we already bind all new parents and bdrv_get_cumulative_perm
> result is enough. So fix the bug by just set permissions by
> bdrv_get_cumulative_perm result.
> 
> Bug was introduced in long ago 234ac1a9025, in 2.9.
> 
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
> ---
> 
> Hi all!
> 
> I found this bug during my work around backup-top filter. It happens that
> on filter removing, bdrv_replace_node() breaks permissions in graph which
> lead to bdrv_set_backing_hd(new backing: NULL) on
> assert(tighten_restrictions == false).
> 
>  block.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)

Thanks, that makes sense.

Applied to my block branch:

https://git.xanclic.moe/XanClic/qemu/commits/branch/block

Max


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      reply	other threads:[~2019-08-26 11:23 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-24 10:07 [Qemu-devel] [PATCH] block: fix permission update in bdrv_replace_node Vladimir Sementsov-Ogievskiy
2019-08-26 11:21 ` Max Reitz [this message]

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