Re: [patch] 4GB I/O, cut three

[Jens Axboe <axboe@kernel.org>]

On Wed, May 30 2001, Mark Hemment wrote:
> On Wed, 30 May 2001, Jens Axboe wrote:
> > On Wed, May 30 2001, Mark Hemment wrote:
> > >   This can lead to attempt_merge() releasing the embedded request
> > > structure (which, as an extract copy, has the ->q set, so to
> > > blkdev_release_request() it looks like a request which originated from
> > > the block layer).  This isn't too healthy.
> > > 
> > >   The fix here is to add a check in __scsi_merge_requests_fn() to check
> > > for ->special being non-NULL.
> > 
> > How about just adding 
> > 
> > 	if (req->cmd != next->cmd
> > 	    || req->rq_dev != next->rq_dev
> > 	    || req->nr_sectors + next->nr_sectors > q->max_sectors
> > 	    || next->sem || req->special)
> >                 return;
> > 
> > ie check for special too, that would make sense to me. Either way would
> > work, but I'd rather make this explicit in the block layer that 'not
> > normal' requests are left alone. That includes stuff with the sem set,
> > or special.
> 
> 
>   Yes, that is an equivalent fix.
> 
>   In the original patch I wanted to keep the change local (ie. in the SCSI
> layer).  Pushing the check up the generic block layer makes sense.

Ok, so we agree.

>   Are you going to push this change to Linus, or should I?
>   I'm assuming the other scsi-layer changes in Alan's tree will eventually
> be pushed.

I'll push it, I'll do the end_that_request_first thing too.

-- 
Jens Axboe