[Libguestfs] [libnbd PATCH v2 2/5] states: Wire in a read callback

[Richard W.M. Jones]

On Thu, Jun 20, 2019 at 08:45:05PM -0500, Eric Blake wrote:
> If any callback fails, and if no prior error was set, then the
> callback's failure becomes the failure reason for the overall
> read. (Note that this is different from the block status callback,
> which for now quits using the callback on subsequent chunks if an
> earlier chunk failed - we may decide to change one or the other for
> consistency before the API is stable.)
> 
> Nothing actually passes a callback function yet, so for now this is no
> functional change; but this will make it possible for the next patch
> to add an 'nbd_aio_pread_structred' API.

I don't think non-C callbacks will be able to reliably set errno, but
that's something we can solve in future.  Therefore ACK.

Rich.

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