RE: [patch] direct-io: bug fix in dio handling write error

[Badari Pulavarty <pbadari@us.ibm.com>]

On Tue, 2006-03-21 at 11:03 -0800, Chen, Kenneth W wrote:
> Badari Pulavarty wrote on Tuesday, March 21, 2006 8:57 AM
> > I hate to do this you - but your patch breaks error handling on
> > synchronous DIO requests.
> > 
> > Since you are using "dio->io_error" instead of "dio->result" to
> > represent an error - you need to make sure to check that (also ?)
> > instead of dio->result in direct_io_worker() before calling 
> > dio_complete().
> > 
> > Isn't it ? Am I missing something ?
> 
> 
> That's the other part of the maze.  AFAICS, in the synchronous path,
> dio_bio_complete already implicitly checks -EIO error:
> 
> static int dio_bio_complete(struct dio *dio, struct bio *bio)
> { ...
>     return uptodate ? 0 : -EIO;
> }
> 
> And such error code bubbles up to direct_io_worker's sync path:
> 
> direct_io_worker {
>     ...
>     if (dio->is_async) {
>     ...
>     } else {
>         ret2 = dio_await_completion(dio);
>         if (ret == 0)
>             ret = ret2;
> 
> I've also explicitly ran test case for synchronous write and found no
> regression there.  I admit my test coverage may not be very comprehensive.
> But I've done the best I can.
> 
> It's entirely possible there are more corner cases.  But let's get some
> coverage here with -mm and then add fixes as we go.

I know that is not your fault - but does this mean that we can't
return success for partial IO ? 

If some one asks to do IO for 128K and if we get -EIO after say, 64K 
- we fail the whole IO  with -EIO ?

Thanks,
Badari

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