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

[Mike Snitzer]

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?

Thanks,
Mike