block I/O accounting improvements

From: Christoph Hellwig
Date: Mon May 25 2020 - 07:30:25 EST

Hi Jens,

they series contains various improvement for block I/O accounting. The
first bunch of patches switch the bio based drivers to better accounting
helpers compared to the current mess. The end contains a fix and various
performanc improvements. Most of this comes from a series Konstantin
sent a few weeks ago, rebased on changes that landed in your tree since
and my change to always use the percpu version of the disk stats.