features/bitrot: Scrubber pause/resume

With logical scan/scrub split, pausing filesystem scrubber is an
override to the thread throttling mechanism, which effectively
throttles "down" number of scrubber threads to zero. This causes
scanner to wait until threads are spawned again (when resumed)
thereby continuing where it left off (since the file tree walk
stack is effectively preserved when the main scanner thread
is waiting for scrubbers to consume scanned entries).

The only catch is when scrubber daemon restarts: file tree walk
stack is lost and scrubbing initiates from root. This is probably
OK for now (can be changed later to persist parent directory
information before entering pause state).

Change-Id: I5109a749b7fccd0f5367765078f46e6522dd32a1
BUG: 1208131
Signed-off-by: Venky Shankar <vshankar@redhat.com>
Reviewed-on: http://review.gluster.org/10521
Reviewed-by: Vijay Bellur <vbellur@redhat.com>
Tested-by: Vijay Bellur <vbellur@redhat.com>

0 files changed, 0 insertions, 0 deletions