Re: [patch] bug fix in dio handling write error

[Badari Pulavarty]

On Tue, 2006-01-17 at 11:41 -0800, Chen, Kenneth W wrote:
> There is a bug in direct-io on propagating write error up to the
> higher I/O layer.  When performing an async ODIRECT write to a
> block device, if a device error occurred (like media error or disk
> is pulled), the error code is only propagated from device driver
> to the DIO layer.  The error code stops at finished_one_bio(). The
> aysnc write, however, is supposedly have a corresponding AIO event
> with appropriate return code (in this case -EIO).  Application
> which waits on the async write event, will hang forever since such
> AIO event is lost forever (if such app did not use the timeout
> option in io_getevents call. Regardless, an AIO event is lost).
> 
> The problem is that calls to aio_complete() is conditioned upon
> READ, but it should've handle WRITE error as well.
> 
> 
> Signed-off-by: Ken Chen <kenneth.w.chen@xxxxxxxxx>
> 
> 
> --- linux-2.6.15/fs/direct-io.c.orig	2006-01-17 11:54:17.010422462 -0800
> +++ linux-2.6.15/fs/direct-io.c	2006-01-17 12:08:00.444982688 -0800
> @@ -253,8 +253,7 @@ static void finished_one_bio(struct dio 
>  			dio_complete(dio, offset, transferred);
>  
>  			/* Complete AIO later if falling back to buffered i/o */
> -			if (dio->result == dio->size ||
> -				((dio->rw == READ) && dio->result)) {
> +			if (dio->result == dio->size || dio->result) {
>  				aio_complete(dio->iocb, transferred, 0);
>  				kfree(dio);
>  				return;
> 
> 

I vaguely remember adding the explicit "dio->rw == READ" check for a
reason (which escapes me right now). Suparna, do you remember ? Let me
think and get back to you.

Thanks,
Badari

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