orangefs: miscellaneous improvements and feature negotiation

  miscellaneous improvements

    - clean up debugfs globals
    - remove dead code in sysfs
    - reorganize duplicated sysfs attribute structs
    - consolidate sysfs show and store functions
    - remove duplicated sysfs_ops structures
    - describe organization of sysfs
    - make devreq_mutex static
    - g_orangefs_stats -> orangefs_stats for consistency
    - rename most remaining global variables

  feature negotiation

    enable Orangefs userspace and kernel module to negotiate mutually
    supported features.
Revert "orangefs: bump minimum userspace version"

The features op did make it into OrangeFS 2.9.6 after all.

This reverts commit 0c95ad76361f1d75a1ffdf82deafbcec44d19c42.
1 file changed