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

[Ananiev, Leonid I]

-----Original Message-----
From: Zach Brown [mailto:zach.brown@xxxxxxxxxx] 
Sent: Thursday, February 15, 2007 10:23 PM
To: Ananiev, Leonid I
Cc: Ken Chen; suparna@xxxxxxxxxx; Andrew Morton;
linux-kernel@xxxxxxxxxxxxxxx; linux-aio; Chris Mason
Subject: Re: [PATCH] aio: fix kernel bug when page is temporally busy


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
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/