glusterd: add defence mechanism to avoid brick port clashes

Intro:
Currently glusterd maintain the portmap registry which contains ports that
are free to use between 49152 - 65535, this registry is initialized
once, and updated accordingly as an then when glusterd sees they are been
used.

Glusterd first checks for a port within the portmap registry and gets a FREE
port marked in it, then checks if that port is currently free using a connect()
function then passes it to brick process which have to bind on it.

Problem:
We see that there is a time gap between glusterd checking the port with
connect() and brick process actually binding on it. In this time gap it could
be so possible that any process would have occupied this port because of which
brick will fail to bind and exit.

Case 1:
To avoid the gluster client process occupying the port supplied by glusterd :

we have separated the client port map range with brick port map range more @
http://review.gluster.org/#/c/13998/

Case 2: (Handled by this patch)
To avoid the other foreign process occupying the port supplied by glusterd :

To handle above situation this patch implements a mechanism to return EADDRINUSE
error code to glusterd, upon which a new port is allocated and try to restart
the brick process with the newly allocated port.

Note: Incase of glusterd restarts i.e. runner_run_nowait() there is no way to
handle Case 2, becuase runner_run_nowait() will not wait to get the return/exit
code of the executed command (brick process). Hence as of now in such case,
we cannot know with what error the brick has failed to connect.

This patch also fix the runner_end() to perform some cleanup w.r.t
return values.

Backport of:
> Change-Id: Iec52e7f5d87ce938d173f8ef16aa77fd573f2c5e
> BUG: 1322805
> Signed-off-by: Prasanna Kumar Kalever <prasanna.kalever@redhat.com>
> Reviewed-on: http://review.gluster.org/14043
> Tested-by: Prasanna Kumar Kalever <pkalever@redhat.com>
> Reviewed-by: Atin Mukherjee <amukherj@redhat.com>
> Smoke: Gluster Build System <jenkins@build.gluster.com>
> NetBSD-regression: NetBSD Build System <jenkins@build.gluster.org>
> CentOS-regression: Gluster Build System <jenkins@build.gluster.com>
> Reviewed-by: Raghavendra G <rgowdapp@redhat.com>

Change-Id: Id7d8351a0082b44310177e714edc0571ad0f7195
BUG: 1333711
Signed-off-by: Prasanna Kumar Kalever <prasanna.kalever@redhat.com>
Reviewed-on: http://review.gluster.org/14235
Tested-by: Prasanna Kumar Kalever <pkalever@redhat.com>
Smoke: Gluster Build System <jenkins@build.gluster.com>
NetBSD-regression: NetBSD Build System <jenkins@build.gluster.org>
CentOS-regression: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Atin Mukherjee <amukherj@redhat.com>

2 files changed, 32 insertions, 1 deletions

diff --git a/xlators/mgmt/glusterd/src/glusterd-messages.h b/xlators/mgmt/glusterd/src/glusterd-messages.h
index b49d87da1bf..61ba7bd3179 100644
--- a/xlators/mgmt/glusterd/src/glusterd-messages.h
+++ b/xlators/mgmt/glusterd/src/glusterd-messages.h
@@ -41,7 +41,7 @@
 
 #define GLUSTERD_COMP_BASE      GLFS_MSGID_GLUSTERD
 
-#define GLFS_NUM_MESSAGES       573
+#define GLFS_NUM_MESSAGES       575
 
 #define GLFS_MSGID_END          (GLUSTERD_COMP_BASE + GLFS_NUM_MESSAGES + 1)
 /* Messaged with message IDs */
@@ -4641,6 +4641,15 @@
  */
 #define GD_MSG_FILE_NOT_FOUND                       (GLUSTERD_COMP_BASE + 574)
 
+/*!
+ * @messageid 106575
+ * @diagnosis  Brick failed to start with given port, hence it gets a fresh port
+ *             on its own and try to restart the brick with a new port
+ * @recommendedaction  Ensure the new port is not blocked by firewall
+ */
+
+#define GD_MSG_RETRY_WITH_NEW_PORT                   (GLUSTERD_COMP_BASE + 575)
+
 /*------------*/
 #define glfs_msg_end_x GLFS_MSGID_END, "Invalid: End of messages"
 #endif /* !_GLUSTERD_MESSAGES_H_ */
diff --git a/xlators/mgmt/glusterd/src/glusterd-utils.c b/xlators/mgmt/glusterd/src/glusterd-utils.c
index 68208312acb..5c28ec942ca 100644
--- a/xlators/mgmt/glusterd/src/glusterd-utils.c
+++ b/xlators/mgmt/glusterd/src/glusterd-utils.c
@@ -1808,6 +1808,8 @@ glusterd_volume_start_glusterfs (glusterd_volinfo_t  *volinfo,
            writing the valgrind log to the same file.
         */
         GLUSTERD_REMOVE_SLASH_FROM_PATH (brickinfo->path, exp_path);
+
+retry:
         runinit (&runner);
 
         if (priv->valgrind) {
@@ -1899,6 +1901,26 @@ glusterd_volume_start_glusterfs (glusterd_volinfo_t  *volinfo,
                 ret = runner_run (&runner);
                 synclock_lock (&priv->big_lock);
 
+                if (ret == -EADDRINUSE) {
+                        /* retry after getting a new port */
+                        gf_msg (this->name, GF_LOG_WARNING, -ret,
+                                GD_MSG_SRC_BRICK_PORT_UNAVAIL,
+                                "Port %d is used by other process", port);
+
+                        port = pmap_registry_alloc (this);
+                        if (!port) {
+                                gf_msg (this->name, GF_LOG_CRITICAL, 0,
+                                        GD_MSG_NO_FREE_PORTS,
+                                        "Couldn't allocate a port");
+                                ret = -1;
+                                goto out;
+                        }
+                        gf_msg (this->name, GF_LOG_NOTICE, 0,
+                                GD_MSG_RETRY_WITH_NEW_PORT,
+                                "Retrying to start brick %s with new port %d",
+                                brickinfo->path, port);
+                        goto retry;
+                }
         } else {
                 ret = runner_run_nowait (&runner);
         }