Hi Jens, this series cleans up the various direct I/O and pass through routines by switching them over to common bio helpers. For the block device simple case this also fixes a page leak if we were using bvec iters. The last page just unconditionally applies the no page ref behavior for bvec iters. I looked at all the callers, and there is none that drops the pre-required references before completing the request. Probably not suitable for so late in the merge, but I wanted to get it out.
