Re: dm core patches

[Jens Axboe]

On Fri, Feb 13 2004, James Bottomley wrote:
> > The mechanism is in place, but the SCSI stack still needs a few changes
> > to pass down the correct errors. The easiest would be to pass down
> > pseudo-sense keys (I'd rather just call them something else as not to
> > confuse things, io error hints or something) to
> > end_that_request_first(), changing uptodate from a bool to a hint.
> 
> Yes, I'm ready to do this in SCSI.  I think the uptodate field should
> include at least two (and possibly three) failure type indications:
> 
> - fatal: error cannot be retried
> - retryable: error may be retried
> 
> and possibly
> 
> - informational: This is dangerous, since it's giving information about
> a transaction that actually succeeded (i.e. we'd need to fix drivers to
> recognise it as being uptodate but with info, like sector remapped)
> 
> Then, we also have a error origin indication:
> 
> - device: The device is actually reporting the problem
> - transport: the error is a transport error
> - driver: the error comes from the device driver.
> 
> So dm would know that fatal transport or driver errors could be
> repathed, but fatal device errors probably couldn't.
> 
> Any that I've missed?

Nope, this looks pretty spot-on to me. I have to agree with Lars and
rather keep it simple and straight forward, than introduce shady
informational bits.

-- 
Jens Axboe

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