Re: [PATCH V3 0/5] dm-rq: improve sequential I/O performance

[Mike Snitzer <snitzer@redhat.com>]

On Fri, Jan 12 2018 at  6:42pm -0500,
Bart Van Assche <Bart.VanAssche@wdc.com> wrote:

> On Fri, 2018-01-12 at 18:17 -0500, Mike Snitzer wrote:
> > @@ -1570,7 +1570,10 @@ static int multipath_end_io(struct dm_target *ti, struct request *clone,
> >  	if (error && blk_path_error(error)) {
> >  		struct multipath *m = ti->private;
> >  
> > -		r = DM_ENDIO_REQUEUE;
> > +		if (r == BLK_STS_RESOURCE)
> > +			r = DM_ENDIO_DELAY_REQUEUE;
> > +		else
> > +			r = DM_ENDIO_REQUEUE;
> 
> Did you perhaps intend "error == BLK_STS_RESOURCE"?

Yes, it was a quick patch to get your thoughts.

> 
> > diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
> > index 9ba8453..da83f64 100644
> > --- a/include/linux/device-mapper.h
> > +++ b/include/linux/device-mapper.h
> > @@ -550,6 +550,7 @@ struct dm_table *dm_swap_table(struct mapped_device *md,
> >  #define DM_ENDIO_DONE		0
> >  #define DM_ENDIO_INCOMPLETE	1
> >  #define DM_ENDIO_REQUEUE	2
> > +#define DM_ENDIO_DELAY_REQUEUE	3
> >  
> >  /*
> >   * Definitions of return values from target map function.
> > @@ -557,7 +558,7 @@ struct dm_table *dm_swap_table(struct mapped_device *md,
> >  #define DM_MAPIO_SUBMITTED	0
> >  #define DM_MAPIO_REMAPPED	1
> >  #define DM_MAPIO_REQUEUE	DM_ENDIO_REQUEUE
> > -#define DM_MAPIO_DELAY_REQUEUE	3
> > +#define DM_MAPIO_DELAY_REQUEUE	DM_ENDIO_DELAY_REQUEUE
> >  #define DM_MAPIO_KILL		4
> >  
> >  #define dm_sector_div64(x, y)( \
> 
> Please consider to introduce enumeration types for the DM_ENDIO_* and the
> DM_MAPIO_* constants such that the compiler can catch what I reported above.

OK, point taken.

> Otherwise this patch looks fine to me.

Cool, thanks.

Mike