Re: [PATCH -V2 3/3] btrfs: fix panic caused by direct IO

[Miao Xie <miaox@cn.fujitsu.com>]

Hi, Chris

On Sun, 28 Nov 2010 20:55:28 -0500, Chris Mason wrote:
> Excerpts from Chris Mason's message of 2010-11-21 22:18:54 -0500:
>> Great, I'll test this and the others overnight.  Thanks!
>>
>> -chris
>>
>> Excerpts from Miao Xie's message of 2010-11-21 22:04:43 -0500:
>>> V1->V2 Changes:
>>> change the fix method. we split bios in btrfs_submit_direct() to fix this
>>> problem now.
>>>
>>> btrfs paniced when we write>64KB data by direct IO at one time.
>>>
>>> Reproduce steps:
>>>   # mkfs.btrfs /dev/sda5 /dev/sda6
>>>   # mount /dev/sda5 /mnt
>>>   # dd if=/dev/zero of=/mnt/tmpfile bs=100K count=1 oflag=direct
>
> Thanks again for coding this up, the implementation looks good to me.
>
> This easily passed the basic tests, but I ran into trouble when I tried
> using it to server my virtual machines.  The problem is that we create
> ordered extents in the DIO get_blocks call, but the generic DIO code
> may create a single bio to span more than one ordered extent by merging
> adjacent ranges.  I've fixed it here by walking forward through the
> ordered extents in the end_io processing.
>
> I've pushed these changes out to the next-rc branch of the btrfs
> unstable tree, and the last commit is here:
>
> Could you please take a look and verify it still works with your tests?
>
> http://git.kernel.org/?p=linux/kernel/git/mason/btrfs-unstable.git;a=commit;h=163cf09c2a0ee5cac6285f9347975bd1e97725da

I have tested it, and It works well.

Thanks
Miao

>
> -chris
>