Re: [PATCH v6 6/6] libnvdimm, btt: rework error clearing

["Verma, Vishal L" <vishal.l.verma@intel.com>]

On Wed, 2017-08-23 at 17:23 +0000, Kani, Toshimitsu wrote:
> On Tue, 2017-08-22 at 16:19 -0600, Vishal Verma wrote:
>  :
> > +
> > +/* The block had a media error, and needs to be
> > cleared */
> > +if (btt_is_badblock(btt, arena, arena-
> > > freelist[lane].block)) {
> > 
> > +arena->freelist[lane].has_err = 1;
> > +nd_region_release_lane(btt->nd_region,
> > lane);
> > +
> > +arena_clear_freelist_error(arena, lane);
> > +/* OK to acquire a different lane/free block
> > */
> > +goto retry;
> 
> I hit an infinite clear loop when DSM Clear Uncorrectable Error
> function fails.  Haven't looked into the details, but I suspect this
> unconditional retry is the cause of this.

Thanks Toshi - that makes sense. I think the right thing to do would be
if the DSM fails, return an EIO yes? (Or should we ignore the fact that
there was an error, clear ->has_err, and let the write take its course
(possibly generate a CMCI)

It will still be in the badblock list, and for reads ->rw_bytes will
still check and fail them.

I'll send out a new series with a fix, but we really need to get a unit
test for BTT error clearing, and I'm working on implementing the new
error injection DSMs in libndctl and nfit_test to do that.

> 
> Thanks,
> -Toshi
> 
> 
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