syncop: fix conditional wait bug in parallel dir scan

Problem:
The issue as seen by the user is detailed in the BZ but what is
happening is if the no. of items in the wait queue == max-qlen,
syncop_mt_dir_scan() does a pthread_cond_wait until the launched
synctask workers dequeue the queue. But if for some reason the worker
fails, the queue is never emptied due to which further invocations of
syncop_mt_dir_scan() are blocked forever.

Fix: Made some changes to _dir_scan_job_fn

- If a worker encounters error while processing an entry, notify the
  readdir loop in syncop_mt_dir_scan() of the error but continue to process
  other entries in the queue, decrementing the qlen as and when we dequeue
  elements, and ending only when the queue is empty.

- If the readdir loop in syncop_mt_dir_scan() gets an error form the
  worker, stop the readdir+queueing of further entries.

> Reviewed-on: http://review.gluster.org/16073
> Smoke: Gluster Build System <jenkins@build.gluster.org>
> NetBSD-regression: NetBSD Build System <jenkins@build.gluster.org>
> CentOS-regression: Gluster Build System <jenkins@build.gluster.org>
> Reviewed-by: Pranith Kumar Karampuri <pkarampu@redhat.com>
(cherry picked from commit 2d012c4558046afd6adb3992ff88f937c5f835e4)

Change-Id: I39ce073e01a68c7ff18a0e9227389245a6f75b88
BUG: 1403192
Signed-off-by: Ravishankar N <ravishankar@redhat.com>
Reviewed-on: http://review.gluster.org/16096
Smoke: Gluster Build System <jenkins@build.gluster.org>
NetBSD-regression: NetBSD Build System <jenkins@build.gluster.org>
CentOS-regression: Gluster Build System <jenkins@build.gluster.org>
Reviewed-by: Pranith Kumar Karampuri <pkarampu@redhat.com>

0 files changed, 0 insertions, 0 deletions