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

On Fri, Mar 25, 2016 at 1:59 PM, Verma, Vishal L <vishal.l.verma(a)intel.com&gt; wrote: > > On Fri, 2016-03-25 at 03:45 -0700, Christoph Hellwig wrote: > > > > On Thu, Mar 24, 2016 at 05:17:30PM -0600, Vishal Verma wrote: > > > > > > > > > dax_do_io (called for read() or write() for a dax file system) > > > may > > > fail > > > in the presence of bad blocks or media errors. Since we expect > > > that > > > a > > > write should clear media errors on nvdimms, make dax_do_io fall > > > back to > > > the direct_IO path, which will send down a bio to the driver, > > > which > > > can > > > then attempt to clear the error. > > Leave the fallback on -EIO to the callers please.  They generally > > call > > __blockdev_direct_IO anyway, so it should actually become simpler > > that > > way. > I thought of this, but made the retrying happen in the wrapper so > that > it can be centralized. If the callers were to become responsible > for > the retry, then any new callers of dax_do_io might not realize they > are > responsible for retrying, and hit problems. That's their prerogative otherwise you are precluding an alternate handling of a dax_do_io() failure.  Maybe a fs or upper layer can recover in a different manner than re-submit the I/O to the __blockdev_direct_IO path.