[dm-devel] dm: rename max_io_len to io_boundary

[Mike Snitzer]

On Thu, Mar 21 2019 at  6:57pm -0400,
John Dorminy <jdorminy at redhat.com> wrote:

> Perhaps this wording might be clearer?
> 
> /* If non-zero, I/O submitted to a target will be split so as to not
> straddle any multiple of this length (in bytes) */

.max_io_len is a pretty well-worn DM target attribute.

I'd prefer to just take a patch with the above updated comment and leave
max_io_len as is.  Not too interested in a flag day to rename it,
especially since it just becomes churn for every target, etc.