MFC r297156,r297157,r297158,r297159,r297161,r297172,r297200,r297201,r297202,

MFC r297156,r297157,r297158,r297159,r297161,r297172,r297200,r297201,r297202,
    r297203,r297256:

  r297156:
    Track filemon usage via a proc.p_filemon pointer rather than its own lists.
  r297157:
    Stop tracking stat(2).
  r297158:
    Consolidate open(2) and openat(2) code.
  r297159:
    Use curthread for vn_fullpath.
  r297161:
    Attempt to use the namecache for openat(2) path resolution.
  r297172:
    Consolidate common link(2) logic.
  r297200:
    Follow-up r297156: Close the log in filemon_dtr rather than in the last
    reference.
  r297201:
    Return any log write failure encountered when closing the filemon fd.
  r297202:
    Remove unused done argument to copyinstr(9).
  r297203:
    Handle copyin failures.
  r297256:
    Remove unneeded return left from refactoring.

Relnotes:	yes (filemon stability/performance updates)
Sponsored by:	EMC / Isilon Storage Division

git-svn-id: svn://svn.freebsd.org/base/stable/10@302066 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f