On 06/29/2012 05:22 PM, Joel Becker wrote:
> On Thu, Jun 28, 2012 at 03:39:56PM -0700, Andrew Morton wrote:
>> On Wed, 27 Jun 2012 17:09:54 +0800
>> Junxiao Bi <[email protected]> wrote:
>>
>>> Ocfs2 uses kiocb.*private as a flag of unsigned long size. In
>>> commit a11f7e6 ocfs2: serialize unaligned aio, the unaligned
>>> io flag is involved in it to serialize the unaligned aio. As
>>> *private is not initialized in init_sync_kiocb() of do_sync_write(),
>>> this unaligned io flag may be unexpectly set in an aligned dio.
>>> And this will cause OCFS2_I(inode)->ip_unaligned_aio decreased
>>> to -1 in ocfs2_dio_end_io(), thus the following unaligned dio
>>> will hang forever at ocfs2_aiodio_wait() in ocfs2_file_aio_write().
>>>
>>> Signed-off-by: Junxiao Bi <[email protected]>
>>> Cc: [email protected]
>>> Acked-by: Jeff Moyer <[email protected]>
>>> Acked-by: Joel Becker <[email protected]>
>>> ---
>>>  include/linux/aio.h |    1 +
>>>  1 file changed, 1 insertion(+)
>>>
>>> diff --git a/include/linux/aio.h b/include/linux/aio.h
>>> index 2314ad8..b1a520e 100644
>>> --- a/include/linux/aio.h
>>> +++ b/include/linux/aio.h
>>> @@ -140,6 +140,7 @@ struct kiocb {
>>>             (x)->ki_dtor = NULL;                    \
>>>             (x)->ki_obj.tsk = tsk;                  \
>>>             (x)->ki_user_data = 0;                  \
>>> +           (x)->private = NULL;                    \
>>>     } while (0)
>>>  
>>>  #define AIO_RING_MAGIC                     0xa10a10a1
>> hm, that code is rather cruddy.  Pointless macromania.
> Agreed.
>
>> If we do this:
>>
>> static inline void init_sync_kiocb(struct kiocb *kiocb, struct file *filp)
>> {
>>      *kiocb = (struct kiocb) {
>>                      .ki_users = 1,
>>                      .ki_key = KIOCB_SYNC_KEY,
>>                      .ki_filp = filp,
>>                      .ki_obj.tsk = current,
>>              };
>> }
>>
>> then fs/read_write.o's .text is shrunk from 9857 bytes to 9714, which
>> is rather a lot.
>>
>> But that's all rather irrelevant to your bugfix.
>       I like your solution.  Junxiao, if you send me that version, I'd
> be happy to take it.
Hi Joel,

Andrew had merged this patch to his tree. Do you like the second patch "
ocfs2: clear unaligned io flag when dio fails"?
> Joel
>

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