features/bitrot: reimplement scrubbing frequency

This patch reimplments existing scrub-frequency mechanism used
to schedule scrubber runs. Existing mechanism uses periodic
sleeps (waking up periodically on minimum granularity) and
performing a number of tracking checks based on counters and
sleep times. This patch does away with all the nifty counters
and uses timer-wheel to schedule scrub runs.

Scheduling changes are peformed by merely calculating the new
expiry time and calling mod_timer() [mod_timer_pending() in
some cases] making the code more debuggable and easier to
follow. This also introduces "hourly" scrubbing tunable as an
aid for testing scrubbing during development/testing cycle.

One could also implement on-demand scrubbing with ease: by
invoking mod_timer() with an expiry of one (1) second, thereby
scheduling a scrub run the very next second.

Change-Id: I6c7c5f0c6c9f886bf574d88c04cde14b76e60a8b
BUG: 1224596
Signed-off-by: Venky Shankar <vshankar@redhat.com>
Reviewed-on: http://review.gluster.org/10893
Reviewed-by: Gaurav Kumar Garg <ggarg@redhat.com>
Tested-by: NetBSD Build System
Reviewed-by: Vijay Bellur <vbellur@redhat.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/xlators/features/bit-rot/src/stub/bit-rot-stub-mem-types.h b/xlators/features/bit-rot/src/stub/bit-rot-stub-mem-types.h
index 9f6da89032f..504b8ab3635 100644
--- a/xlators/features/bit-rot/src/stub/bit-rot-stub-mem-types.h
+++ b/xlators/features/bit-rot/src/stub/bit-rot-stub-mem-types.h
@@ -29,6 +29,7 @@ enum br_mem_types {
         gf_br_mt_br_scrubber_t,
         gf_br_mt_br_fsscan_entry_t,
         gf_br_stub_mt_br_stub_fd_t,
+        gf_br_stub_mt_br_scanner_freq_t,
         gf_br_stub_mt_end,
 };