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, 17 insertions, 1 deletions

diff --git a/xlators/mgmt/glusterd/src/glusterd-scrub-svc.c b/xlators/mgmt/glusterd/src/glusterd-scrub-svc.c
index 987acb60955..8d1133f9f55 100644
--- a/xlators/mgmt/glusterd/src/glusterd-scrub-svc.c
+++ b/xlators/mgmt/glusterd/src/glusterd-scrub-svc.c
@@ -88,7 +88,23 @@ out:
 int
 glusterd_scrubsvc_start (glusterd_svc_t *svc, int flags)
 {
-        return glusterd_svc_start (svc, flags, NULL);
+        int ret = -1;
+        dict_t *cmdict = NULL;
+
+        cmdict = dict_new ();
+        if (!cmdict)
+                goto error_return;
+
+        ret = dict_set_str (cmdict, "cmdarg0", "--global-timer-wheel");
+        if (ret)
+                goto dealloc_dict;
+
+        ret = glusterd_svc_start (svc, flags, cmdict);
+
+ dealloc_dict:
+        dict_unref (cmdict);
+ error_return:
+        return ret;
 }
 
 int