glusterd: socketfile & pidfile related fixes for brick multiplexing feature

Problem: While brick-muliplexing is on after restarting glusterd, CLI is
         not showing pid of all brick processes in all volumes.

Solution: While brick-mux is on all local brick process communicated through one
          UNIX socket but as per current code (glusterd_brick_start) it is trying
          to communicate with separate UNIX socket for each volume which is populated
          based on brick-name and vol-name.Because of multiplexing design only one
          UNIX socket is opened so it is throwing poller error and not able to
          fetch correct status of brick process through cli process.
          To resolve the problem write a new function glusterd_set_socket_filepath_for_mux
          that will call by glusterd_brick_start to validate about the existence of socketpath.
          To avoid the continuous EPOLLERR erros in  logs update socket_connect code.

Test:     To reproduce the issue followed below steps
          1) Create two distributed volumes(dist1 and dist2)
          2) Set cluster.brick-multiplex is on
          3) kill glusterd
          4) run command gluster v status
          After apply the patch it shows correct pid for all volumes

> BUG: 1444596
> Change-Id: I5d10af69dea0d0ca19511f43870f34295a54a4d2
> Signed-off-by: Mohit Agrawal <moagrawa@redhat.com>
> Reviewed-on: https://review.gluster.org/17101
> Smoke: Gluster Build System <jenkins@build.gluster.org>
> Reviewed-by: Prashanth Pai <ppai@redhat.com>
> NetBSD-regression: NetBSD Build System <jenkins@build.gluster.org>
> CentOS-regression: Gluster Build System <jenkins@build.gluster.org>
> Reviewed-by: Atin Mukherjee <amukherj@redhat.com>
> (cherry picked from commit 21c7f7baccfaf644805e63682e5a7d2a9864a1e6)

Change-Id: I1892c80b9ffa93974f20c92d421660bcf93c4cda
BUG: 1449002
Signed-off-by: Mohit Agrawal <moagrawa@redhat.com>
Reviewed-on: https://review.gluster.org/17210
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: Atin Mukherjee <amukherj@redhat.com>
Reviewed-by: Prashanth Pai <ppai@redhat.com>

2 files changed, 21 insertions, 10 deletions

diff --git a/libglusterfs/src/common-utils.c b/libglusterfs/src/common-utils.c
index c0884de8a5e..f457c55df09 100644
--- a/libglusterfs/src/common-utils.c
+++ b/libglusterfs/src/common-utils.c
@@ -3634,6 +3634,24 @@ gf_skip_header_section (int fd, int header_len)
         return ret;
 }
 
+/* Below function is use to check at runtime if pid is running */
+
+gf_boolean_t
+gf_is_pid_running (int pid)
+{
+        char fname[32] = {0,};
+
+        snprintf(fname, sizeof(fname), "/proc/%d/cmdline", pid);
+
+        if (sys_access (fname , R_OK) != 0) {
+                return _gf_false;
+        }
+
+        return _gf_true;
+
+}
+
+
 gf_boolean_t
 gf_is_service_running (char *pidfile, int *pid)
 {
@@ -3662,15 +3680,7 @@ gf_is_service_running (char *pidfile, int *pid)
                 *pid = -1;
         }
 
-        if (!*pid) {
-                /*
-                 * PID 0 means we've started the process, but it hasn't gotten
-                 * far enough to put in a real PID yet.  More details are in
-                 * glusterd_brick_start.
-                 */
-                running = _gf_true;
-        }
-
+        running = gf_is_pid_running (*pid);
 out:
         if (file)
                 fclose (file);
diff --git a/libglusterfs/src/common-utils.h b/libglusterfs/src/common-utils.h
index 67baa852c45..6243732b522 100644
--- a/libglusterfs/src/common-utils.h
+++ b/libglusterfs/src/common-utils.h
@@ -821,7 +821,8 @@ int gf_thread_create (pthread_t *thread, const pthread_attr_t *attr,
                       void *(*start_routine)(void *), void *arg);
 int gf_thread_create_detached (pthread_t *thread,
                       void *(*start_routine)(void *), void *arg);
-
+gf_boolean_t
+gf_is_pid_running (int pid);
 gf_boolean_t
 gf_is_service_running (char *pidfile, int *pid);
 gf_boolean_t