Re: [PATCH v2 5/5] dax: handle media errors in dax_do_io

[Christoph Hellwig <hch@xxxxxxxxxxxxx>]

On Fri, Apr 15, 2016 at 12:11:36PM -0400, Jeff Moyer wrote:
> > +   if (IS_DAX(inode)) {
> > +           ret = dax_do_io(iocb, inode, iter, offset, blkdev_get_block,
> >                             NULL, DIO_SKIP_DIO_COUNT);
> > +           if (ret == -EIO && (iov_iter_rw(iter) == WRITE))
> > +                   ret_saved = ret;
> > +           else
> > +                   return ret;
> > +   }
> > +
> > +   ret = __blockdev_direct_IO(iocb, inode, I_BDEV(inode), iter, offset,
> >                                 blkdev_get_block, NULL, NULL,
> >                                 DIO_SKIP_DIO_COUNT);
> > +   if (ret < 0 && ret_saved)
> > +           return ret_saved;
> > +
> 
> Hmm, did you just break async DIO?  I think you did!  :)
> __blockdev_direct_IO can return -EIOCBQUEUED, and you've now turned that
> into -EIO.  Really, I don't see a reason to save that first -EIO.  The
> same applies to all instances in this patch.

Yes, there is no point in saving the earlier error - just return the
second error all the time.

E.g.

        ret = dax_io();
        if (dax_need_dio_retry(ret))
                ret = direct_IO();