Re: [PATCH] libata error handling fixes (ATAPI)

[Jens Axboe <axboe@suse.de>]

On Wed, Nov 16 2005, Bartlomiej Zolnierkiewicz wrote:
> On 11/16/05, Jens Axboe <axboe@suse.de> wrote:
> > On Wed, Nov 16 2005, Bartlomiej Zolnierkiewicz wrote:
> > > On 11/16/05, Jens Axboe <axboe@suse.de> wrote:
> > >
> > > > I updated that patch, and converted IDE and SCSI to use it. See the
> > > > results here:
> > > >
> > > > http://brick.kernel.dk/git/?p=linux-2.6-block.git;a=shortlog;h=blk-softirq
> > >
> > > I like it but:
> > >
> > > * "we know it's either an FS or PC request" assumption in
> > >   ide_softirq_done() is really wrong
> >
> > It used to be correct :-)
> 
> Sorry but it has been always like that,
> other requests also pass through ide_end_request()
> (which of course needs fixing).

You misunderstand, for calls to blk_complete_request() it wasn't true
initially since it always obyed rq_all_done() (which returns 0 for
non-fs and non-pc requests).

> > Irk it's nasty, since it basically means we have to hold ide_lock over
> > the entire functions looking at hwgroup->rq.
> >
> > It's ok for __ide_end_request() to be entered with the ide_lock held,
> > the costly affair is usually completing the request. Which now happens
> > outside of the lock.
> 
> We should get rid of ide_preempt later.
> 
> This will also allow us to remove ide_do_drive_cmd()
> and use blk_execute_rq() exclusively.

That would be very nice! Reminds me that there might still be a race
with head insertion and REQ_STARTED request in front in the block layer,
that needs inspection. But killing ide_do_drive_cmd() would be very
nice.

-- 
Jens Axboe