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From: xiaowei <xiaowei.hu@oracle.com>
To: linux-lvm@redhat.com, zkabelac@redhat.com
Cc: Joe Jin <joe.jin@oracle.com>, Alasdair G Kergon <agk@redhat.com>
Subject: Re: [linux-lvm] Segmentation fault in LVM2 latest version.
Date: Fri, 11 Apr 2014 09:14:40 +0800	[thread overview]
Message-ID: <53474200.1040907@oracle.com> (raw)
In-Reply-To: <20140318040402.GE12820@agk-dp.fab.redhat.com>

Hi Alasdair,

May I ask if you have a patch to test for this now?

Thanks,
Xiaowei
On 03/18/2014 12:04 PM, Alasdair G Kergon wrote:
> On Fri, Mar 14, 2014 at 09:05:09AM +0800, xiaowei wrote:
>> That's great you reproduced this bug:)
>> So the fix could be easy?
> No.  Once you know what's wrong, you can find several more classes
> of lvextend that misbehave.
>
> I do have a prototype fix that deals with the case you hit, but it's not
> complete yet.
>
> There are two ways you can extend an LV:
>    1. By pairing up newly-allocated areas of disk with existing ones
>       as you go along.
>       (A simple example would be extending each existing stripe on the same
>       disk.)
>    2. By finding possible areas of disk to fit the required
>       number of areas then selecting the most appropriate ones.
>       (The general case.)
> You can also have a combination of the two, with some areas from 1
> and some from 2.
>
> The first is 'PREFERRED' in the code, and the second is 'USE_AREA'.
> The path through the code that you hit tried to use the first
> method when it should have used the second.
> (If the number of stripes is changing there's no trivial way to
> 'pair up' the new areas with the existing ones.)
> Minor structural changes are needed (code clean up) so that the
> cling policy can sometimes use the second method.
> The default 'allocation/maximise_cling' option fails.
>
> Alasdair
>

  reply	other threads:[~2014-04-11  1:14 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-03-11  8:34 [linux-lvm] Segmentation fault in LVM2 latest version xiaowei
2014-03-12 15:58 ` Alasdair G Kergon
2014-03-14  1:05   ` xiaowei
2014-03-18  4:04     ` Alasdair G Kergon
2014-04-11  1:14       ` xiaowei [this message]
2014-04-15 14:43         ` Alasdair G Kergon
2014-04-17  7:47           ` xiaowei

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