[dm-devel] new "multi-version snapshot target" [was: Re: [PATCH] vfs: calculate block-size correctly]

[McPacino]

On Wed, Sep 15, 2010 at 10:20 PM, Mike Snitzer <snitzer at redhat.com> wrote:
> On Wed, Sep 15, 2010 at 4:14 AM, McPacino <mcpacino at gmail.com> wrote:
>> On Tue, Sep 14, 2010 at 7:09 AM, Andrew Morton
>> <akpm at linux-foundation.org> wrote:
>>>
>>> On Wed, 8 Sep 2010 18:07:10 +0800
>>> Cong Meng <mcpacino at gmail.com> wrote:
>>>
>>> > I sent this patch half mount ago, but no response at all. If anything is
>>> > wrong, please tell me. Thanks a lots. This is my first time to send patch
>>> > to linux kernel.
>>> >
>>> > The invocation of __getblk(bdev, block, size) will cause kernel stall if
>>> > the @size parameter is not equal to the blockr-size of @bdev, which is saved
>>> > in bdev->bd_inode->i_blkbits.
>>> >
>>> > submit_bh() has the similar problem.
>>> >
>>> > This patch calculates the block-size using i_blkbits.
>>> > So that, for example, __getblk() can get a 4K buffer head while the
>>> > block-size of @bdev is 1K.
>>> >
>>>
>>> This comes up every couple of years and iirc we always decided that
>>> it's a bug in the calling code somewhere.  How did you hit it?
>>>
>>
>> I am working on a new multi-version snapshot target module for device-mapper
>> which is almost done.
>
> And you hope to have this code included upstream?  Do you intend to
> post your patches to dm-devel?
>

Of course, yes.
The code is almost finished and is being tested.
I will post it few weeks later if everything goes well.

> Thanks,
> Mike
>