Re: [PATCH] aio: fix kernel bug when page is temporally busy

[Zach Brown <zach.brown@oracle.com>]

On Feb 15, 2007, at 11:11 AM, Ananiev, Leonid I wrote:

>> It returns -EIOCBRETRY without guaranteeing that kick_iocb() will be
>> called.  This can lead to operations hanging
>
> If EIOCBRETRY then generic_file_aio_write() will be recalled for the
> same iocb.

Only if kick_iocb() is called.  It won't be called if i_i_p2_r() was  
the only thing to return -EIOCBRETRY.

>
>> It overwrites -EIOCBQUEUED, leading to an aio_complete() while a
>> retry is happening.
>
> EIOCBQUEUED or EIOCBRETRY does not lead to aio_complete() call:

Not by fs/aio.c, but *by the place that originated -EIOCBQUEUED*.   
Later.  After IO has completed.  see fs/direct-io.c:dio_bio_end_aio().

This is what -EIOCBQUEUED means!  It's a promise to call aio_complete 
() in the future.

Have you read the giant comment over the definition of struct kiocb  
in include/linux/aio.h?

>> This can lead to reference count confusion.
> But just reference count confusion was deleted by patch. Isn't it?

Sorry, I don't understand what you're trying to ask here.

- z