Re: [patch] only update dcache after write succeeds

[Doug Evans <dje@google.com>]

On Mon, Sep 14, 2009 at 12:26 PM, Michael Snyder <msnyder@vmware.com> wrote:
> Doug Evans wrote:
>>
>> Hi.
>>
>> Marc, Greg: Can you see if this patch fixes things for you?
>
> Hey Doug,

Hey Michael, :-)

> I tested this change, and it does indeed seem to fix the problem
> with target record -- but.   ;-)
>
> Part of the reason that it works is that record_xfer_partial
> calls error() instead of returning -1.  If I change it so that
> it returns -1, things get more complicated.
>
> The do-while loop that used to follow and now preceeds this code
> calls target-beneath, which in our case results in several different
> target methods being called, one of which eventually returns > 0.
>
> That just means that in the present case, calling error is correct.
> But I worry about some of the other cases where the target method
> returns -1, and whether badness might occur in some other cases.

How does one reconcile  "eventually returns > 0" with "badness"?

IOW, if some target method does return > 0, then the write succeeded, right?
Are there different kinds of "success" in effect here?