glusterd/shared_storage: Provide a volume set option to create and mount the shared storage

Introducing a global volume set option(cluster.enable-shared-storage)
which helps create and set-up the shared storage meta volume.

gluster volume set all cluster.enable-shared-storage enable

On enabling this option, the system analyzes the number of peers
in the cluster, which are currently connected, and chooses three
such peers(including the node the command is issued from). From these
peers a volume(gluster_shared_storage) is created. Depending on the
number of peers available the volume is either a replica 3
volume(if there are 3 connected peers),  or a replica 2 volume(if there
are 2 connected peers). "/var/run/gluster/ss_brick" serves as the
brick path on each node for the shared storage volume. We also mount
the shared storage at "/var/run/gluster/shared_storage" on all the nodes
in the cluster as part of enabling this option. If there is only one node
in the cluster,  or only one node is up then the command will fail

Once the volume is created, and mounted the maintainance of the
volume like adding-bricks, removing bricks etc., is expected to
be the onus of the user.

On disabling the option, we provide the user a warning, and on
affirmation from the user we stop the shared storage volume, and unmount
it from all the nodes in the cluster.

gluster volume set all cluster.enable-shared-storage disable

Change-Id: Idd92d67b93f444244f99ede9f634ef18d2945dbc
BUG: 1222013
Signed-off-by: Avra Sengupta <asengupt@redhat.com>
Reviewed-on: http://review.gluster.org/10793
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Tested-by: NetBSD Build System <jenkins@build.gluster.org>
Reviewed-by: Rajesh Joseph <rjoseph@redhat.com>
Reviewed-by: Krishnan Parthasarathi <kparthas@redhat.com>

1 files changed, 74 insertions, 33 deletions

diff --git a/xlators/mgmt/glusterd/src/glusterd.c b/xlators/mgmt/glusterd/src/glusterd.c
index 5bdeb753f4a..407089af493 100644
--- a/xlators/mgmt/glusterd/src/glusterd.c
+++ b/xlators/mgmt/glusterd/src/glusterd.c
@@ -62,7 +62,8 @@ extern struct rpcsvc_program gd_svc_cli_trusted_progs;
 extern struct rpc_clnt_program gd_brick_prog;
 extern struct rpcsvc_program glusterd_mgmt_hndsk_prog;
 
-extern char snap_mount_folder[PATH_MAX];
+extern char snap_mount_dir[PATH_MAX];
+char ss_brick_path[PATH_MAX];
 
 rpcsvc_cbk_program_t glusterd_cbk_prog = {
         .progname  = "Gluster Callback",
@@ -1115,18 +1116,18 @@ glusterd_stop_uds_listener (xlator_t *this)
 }
 
 static int
-glusterd_init_snap_folder (xlator_t *this)
+glusterd_find_correct_var_run_dir (xlator_t *this, char *var_run_dir)
 {
         int             ret = -1;
         struct stat     buf = {0,};
 
-        GF_ASSERT (this);
+        GF_VALIDATE_OR_GOTO ("glusterd", this, out);
+        GF_VALIDATE_OR_GOTO (this->name, var_run_dir, out);
 
-        /* Snapshot volumes are mounted under /var/run/gluster/snaps folder.
-         * But /var/run is normally a symbolic link to /run folder, which
+        /* /var/run is normally a symbolic link to /run dir, which
          * creates problems as the entry point in the mtab for the mount point
          * and glusterd maintained entry point will be different. Therefore
-         * identify the correct run folder and use it for snap volume mounting.
+         * identify the correct run dir and use it
          */
         ret = lstat (GLUSTERD_VAR_RUN_DIR, &buf);
         if (ret != 0) {
@@ -1136,20 +1137,38 @@ glusterd_init_snap_folder (xlator_t *this)
                 goto out;
         }
 
-        /* If /var/run is symlink then use /run folder */
+        /* If /var/run is symlink then use /run dir */
         if (S_ISLNK (buf.st_mode)) {
-                strcpy (snap_mount_folder, GLUSTERD_RUN_DIR);
+                strcpy (var_run_dir, GLUSTERD_RUN_DIR);
         } else {
-                strcpy (snap_mount_folder, GLUSTERD_VAR_RUN_DIR);
+                strcpy (var_run_dir, GLUSTERD_VAR_RUN_DIR);
         }
 
-        strcat (snap_mount_folder, GLUSTERD_DEFAULT_SNAPS_BRICK_DIR);
+        ret = 0;
+out:
+        return ret;
+}
+
+static int
+glusterd_init_var_run_dirs (xlator_t *this, char *var_run_dir,
+                            char *dir_to_be_created)
+{
+        int             ret                = -1;
+        struct stat     buf                = {0,};
+        char            abs_path[PATH_MAX] = {0, };
+
+        GF_VALIDATE_OR_GOTO ("glusterd", this, out);
+        GF_VALIDATE_OR_GOTO (this->name, var_run_dir, out);
+        GF_VALIDATE_OR_GOTO (this->name, dir_to_be_created, out);
+
+        snprintf (abs_path, sizeof(abs_path), "%s%s",
+                  var_run_dir, dir_to_be_created);
 
-        ret = stat (snap_mount_folder, &buf);
+        ret = stat (abs_path, &buf);
         if ((ret != 0) && (ENOENT != errno)) {
                 gf_log (this->name, GF_LOG_ERROR,
                         "stat fails on %s, exiting. (errno = %d)",
-                        snap_mount_folder, errno);
+                        abs_path, errno);
                 ret = -1;
                 goto out;
         }
@@ -1157,19 +1176,19 @@ glusterd_init_snap_folder (xlator_t *this)
         if ((!ret) && (!S_ISDIR(buf.st_mode))) {
                 gf_log (this->name, GF_LOG_CRITICAL,
                         "Provided snap path %s is not a directory,"
-                        "exiting", snap_mount_folder);
+                        "exiting", abs_path);
                 ret = -1;
                 goto out;
         }
 
         if ((-1 == ret) && (ENOENT == errno)) {
-                /* Create missing folders */
-                ret = mkdir_p (snap_mount_folder, 0777, _gf_true);
+                /* Create missing dirs */
+                ret = mkdir_p (abs_path, 0777, _gf_true);
 
                 if (-1 == ret) {
                         gf_log (this->name, GF_LOG_CRITICAL,
                                 "Unable to create directory %s"
-                                " ,errno = %d", snap_mount_folder, errno);
+                                " ,errno = %d", abs_path, errno);
                         goto out;
                 }
         }
@@ -1246,21 +1265,22 @@ out:
 int
 init (xlator_t *this)
 {
-        int32_t            ret               = -1;
-        rpcsvc_t          *rpc               = NULL;
-        rpcsvc_t          *uds_rpc           = NULL;
-        glusterd_conf_t   *conf              = NULL;
-        data_t            *dir_data          = NULL;
-        struct stat        buf               = {0,};
-        char               storedir [PATH_MAX] = {0,};
-        char               workdir [PATH_MAX] = {0,};
-        char               cmd_log_filename [PATH_MAX] = {0,};
-        int                first_time        = 0;
-        char              *mountbroker_root  = NULL;
-        int                i                 = 0;
-        int                total_transport   = 0;
-        char              *valgrind_str      = NULL;
-        char              *transport_type    = NULL;
+        int32_t            ret                        = -1;
+        rpcsvc_t          *rpc                        = NULL;
+        rpcsvc_t          *uds_rpc                    = NULL;
+        glusterd_conf_t   *conf                       = NULL;
+        data_t            *dir_data                   = NULL;
+        struct stat        buf                        = {0,};
+        char               storedir[PATH_MAX]         = {0,};
+        char               workdir[PATH_MAX]          = {0,};
+        char               cmd_log_filename[PATH_MAX] = {0,};
+        int                first_time                 = 0;
+        char              *mountbroker_root           = NULL;
+        int                i                          = 0;
+        int                total_transport            = 0;
+        char              *valgrind_str               = NULL;
+        char              *transport_type             = NULL;
+        char               var_run_dir[PATH_MAX]      = {0,};
 
 #ifndef GF_DARWIN_HOST_OS
         {
@@ -1322,14 +1342,35 @@ init (xlator_t *this)
         gf_log (this->name, GF_LOG_INFO, "Using %s as working directory",
                 workdir);
 
-        ret = glusterd_init_snap_folder (this);
+        ret = glusterd_find_correct_var_run_dir (this, var_run_dir);
+        if (ret) {
+                gf_log (this->name, GF_LOG_CRITICAL, "Unable to find "
+                        "the correct var run dir");
+                exit (1);
+        }
+
+        ret = glusterd_init_var_run_dirs (this, var_run_dir,
+                                      GLUSTERD_DEFAULT_SNAPS_BRICK_DIR);
+        if (ret) {
+                gf_log (this->name, GF_LOG_CRITICAL, "Unable to create "
+                        "snap backend dir");
+                exit (1);
+        }
 
+        snprintf (snap_mount_dir, sizeof(snap_mount_dir), "%s%s",
+                  var_run_dir, GLUSTERD_DEFAULT_SNAPS_BRICK_DIR);
+
+        ret = glusterd_init_var_run_dirs (this, var_run_dir,
+                                      GLUSTER_SHARED_STORAGE_BRICK_DIR);
         if (ret) {
                 gf_log (this->name, GF_LOG_CRITICAL, "Unable to create "
-                        "snap backend folder");
+                        "shared storage brick");
                 exit (1);
         }
 
+        snprintf (ss_brick_path, sizeof(ss_brick_path), "%s%s",
+                  var_run_dir, GLUSTER_SHARED_STORAGE_BRICK_DIR);
+
         snprintf (cmd_log_filename, PATH_MAX, "%s/cmd_history.log",
                   DEFAULT_LOG_FILE_DIRECTORY);
         ret = gf_cmd_log_init (cmd_log_filename);