pms: handle maximum size IO with any alignment

[rlibby]

Summary

Define the maximum numbers of segments to allow for non-page alignment
at the beginning and end of a maxphys size transfer. Also set
ccb_pathinq.maxio consistent with maxphys.

Sponsored by: Dell EMC Isilon

Test Plan

Here, just make buildkernel. Isilon has tested this downstream, but
has not yet caught up to making maxphys tunable.

[imp]

sys/dev/pms/freebsd/driver/ini/src/agtiapi.c

1836–1837

Shouldn't this be min(maxphys, 1024*1024)? Or is there no silicon limit?

[rlibby]

sys/dev/pms/freebsd/driver/ini/src/agtiapi.c

1836–1837

Thanks for the feedback. I'm looking into whether we have a spec. If we can't come up with a definitive answer, I'll go with your suggestion.

[imp]

sys/dev/pms/freebsd/driver/ini/src/agtiapi.c

1836–1837

Sounds good. Or whatever value you are able to test. I'm not super particular nor do I want to artificially limit something we know (or have good reason to believe) works.

[rlibby]

imp feedback: keep the limit