fix pdflush races and enhancement v2

Update of pdflush series, changes since last post:

o Change upper bound patch to include update of last_empty_jifs to throttle 
thread creation to one per second.

o Change new sysctls to use CTL_UNNUMBERED per Andrew Morton

o Use proc_dointvec_minmax and tie bounds of min and max threads to 
the current min/max.  Otherwise the possible combinations of actual
threads makes my head hurt.

o Update Documentation/sysctl/vm.txt with the new entries


Peter W Morreale (2):
      Add /proc controls for pdflush threads
      Fix pdflush thread creation upper bound.


 Documentation/sysctl/vm.txt |   28 ++++++++++++++++++++++++++
 include/linux/writeback.h   |    2 ++
 kernel/sysctl.c             |   25 +++++++++++++++++++++--
 mm/pdflush.c                |   47 ++++++++++++++++++++++++++++++++++---------
 4 files changed, 90 insertions(+), 12 deletions(-)


Best,
-PWM