[PATCH 9/9] xfs: check xfs_buf_read_uncached returns correctly

[Christoph Hellwig]

On Fri, Aug 15, 2014 at 04:39:07PM +1000, Dave Chinner wrote:
> From: Dave Chinner <dchinner at redhat.com>
> 
> xfs_buf_read_uncached() has two failure modes. If can either return
> NULL or bp->b_error != 0 depending on the type of failure, and not
> all callers check for both. Fix it up.

I'd rather get rid of these annoying calling conventions.  Make it
return and errno, and the bp in a pointer argument, with the bp
never non-NULL in case of error.