Re: [dm-devel] Re: [PATCH] Always pass result and sense on request completion

[Mike Christie <michaelc cs wisc edu>]

James Bottomley wrote:
> On Thu, 2009-12-10 at 10:49 +0100, Hannes Reinecke wrote:
> > Hi James,
> >
> > would you mind commenting on this patch?
> > We really need this if we ever want to be able to do proper error code
> > handling from multipath.
>
> OK, not keen on the way you're setting req->errors.
>
> Our big problem with FS requests is deferred or corrected errors
> (basically we never want the FS to think we had a problem with them).  I
> think it's currently OK because block tends to believe the returned
> error code rather than req->errors ... I'd just hate it if that changed
> and suddenly lots of stuff broke.
>
> I think you're just looking for the sense data, so could you look at
> that and not set req->errors?

For the specific bug Hannes is fixing we only need the sense code, so 
that would work. If you also pass info like the host_byte bits then we 
can do something like fail a path right away for a DID_TRANSPORT* or 
DID_NO_CONNECT failure, but then for other errors do something else. 
RAID could also not fail the drive on transport errors, and do something 
different too.