gNFS: RFE for NFS connection behavior

Implement reconfigure() for NFS xlator so that volume set/reset wont
restart the NFS server process. But few options can not be reconfigured
dynamically e.g. nfs.mem-factor, nfs.port etc which needs NFS to be
restarted.

Change-Id: Ic586fd55b7933c0a3175708d8c41ed0475d74a1c
BUG: 1027409
Signed-off-by: Santosh Kumar Pradhan <spradhan@redhat.com>
Reviewed-on: http://review.gluster.org/6236
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Rajesh Joseph <rjoseph@redhat.com>
Reviewed-by: Anand Avati <avati@redhat.com>

4 files changed, 148 insertions, 0 deletions

diff --git a/xlators/mgmt/glusterd/src/glusterd-utils.c b/xlators/mgmt/glusterd/src/glusterd-utils.c
index f0445cf0b72..515c23a8ca0 100644
--- a/xlators/mgmt/glusterd/src/glusterd-utils.c
+++ b/xlators/mgmt/glusterd/src/glusterd-utils.c
@@ -3834,6 +3834,11 @@ glusterd_reconfigure_nfs ()
         int             ret             = -1;
         gf_boolean_t    identical       = _gf_false;
 
+        /*
+         * Check both OLD and NEW volfiles, if they are SAME by size
+         * and cksum i.e. "character-by-character". If YES, then
+         * NOTHING has been changed, just return.
+         */
         ret = glusterd_check_nfs_volfile_identical (&identical);
         if (ret)
                 goto out;
@@ -3843,6 +3848,31 @@ glusterd_reconfigure_nfs ()
                 goto out;
         }
 
+        /*
+         * They are not identical. Find out if the topology is changed
+         * OR just the volume options. If just the options which got
+         * changed, then inform the xlator to reconfigure the options.
+         */
+        identical = _gf_false; /* RESET the FLAG */
+        ret = glusterd_check_nfs_topology_identical (&identical);
+        if (ret)
+                goto out;
+
+        /* Topology is not changed, but just the options. But write the
+         * options to NFS volfile, so that NFS will be reconfigured.
+         */
+        if (identical) {
+                ret = glusterd_create_nfs_volfile();
+                if (ret == 0) {/* Only if above PASSES */
+                        ret = glusterd_fetchspec_notify (THIS);
+                }
+                goto out;
+        }
+
+        /*
+         * NFS volfile's topology has been changed. NFS server needs
+         * to be RESTARTED to ACT on the changed volfile.
+         */
         ret = glusterd_check_generate_start_nfs ();
 
 out:
@@ -6365,6 +6395,68 @@ glusterd_defrag_volume_status_update (glusterd_volinfo_t *volinfo,
 }
 
 int
+glusterd_check_topology_identical (const char *filename1,
+                                   const char *filename2,
+                                   gf_boolean_t *identical)
+{
+        int                     ret = -1; /* FAILURE */
+        xlator_t                *this = NULL;
+        FILE                    *fp1 = NULL;
+        FILE                    *fp2 = NULL;
+        glusterfs_graph_t       *grph1 = NULL;
+        glusterfs_graph_t       *grph2 = NULL;
+
+        if ((!filename1) || (!filename2) || (!identical))
+                goto out;
+
+        this = THIS;
+
+        errno = 0; /* RESET the errno */
+
+        /* fopen() the volfile1 to create the graph */
+        fp1 = fopen (filename1, "r");
+        if (fp1 == NULL) {
+                gf_log (this->name, GF_LOG_ERROR, "fopen() on file: %s failed "
+                        "(%s)", filename1, strerror (errno));
+                goto out;
+        }
+
+        /* fopen() the volfile2 to create the graph */
+        fp2 = fopen (filename2, "r");
+        if (fp2 == NULL) {
+                gf_log (this->name, GF_LOG_ERROR, "fopen() on file: %s failed "
+                        "(%s)", filename2, strerror (errno));
+                goto out;
+        }
+
+        /* create the graph for filename1 */
+        grph1 = glusterfs_graph_construct(fp1);
+        if (grph1 == NULL)
+                goto out;
+
+        /* create the graph for filename2 */
+        grph2 = glusterfs_graph_construct(fp2);
+        if (grph2 == NULL)
+                goto out;
+
+        /* compare the graph topology */
+        *identical = is_graph_topology_equal(grph1, grph2);
+        ret = 0; /* SUCCESS */
+out:
+        if (fp1)
+                fclose(fp1);
+        if (fp2)
+                fclose(fp2);
+        if (grph1)
+                glusterfs_graph_destroy(grph1);
+        if (grph2)
+                glusterfs_graph_destroy(grph2);
+
+        gf_log (this->name, GF_LOG_DEBUG, "Returning with %d", ret);
+        return ret;
+}
+
+int
 glusterd_check_files_identical (char *filename1, char *filename2,
                                 gf_boolean_t *identical)
 {
diff --git a/xlators/mgmt/glusterd/src/glusterd-utils.h b/xlators/mgmt/glusterd/src/glusterd-utils.h
index 024675c7fbb..57120fe3942 100644
--- a/xlators/mgmt/glusterd/src/glusterd-utils.h
+++ b/xlators/mgmt/glusterd/src/glusterd-utils.h
@@ -456,6 +456,12 @@ glusterd_defrag_volume_status_update (glusterd_volinfo_t *volinfo,
 int
 glusterd_check_files_identical (char *filename1, char *filename2,
                                 gf_boolean_t *identical);
+
+int
+glusterd_check_topology_identical (const char *filename1,
+                                   const char *filename2,
+                                   gf_boolean_t *identical);
+
 void
 glusterd_volinfo_reset_defrag_stats (glusterd_volinfo_t *volinfo);
 int
diff --git a/xlators/mgmt/glusterd/src/glusterd-volgen.c b/xlators/mgmt/glusterd/src/glusterd-volgen.c
index 6af52abe286..0de71a49afe 100644
--- a/xlators/mgmt/glusterd/src/glusterd-volgen.c
+++ b/xlators/mgmt/glusterd/src/glusterd-volgen.c
@@ -3440,6 +3440,54 @@ out:
 }
 
 int
+glusterd_check_nfs_topology_identical (gf_boolean_t *identical)
+{
+        char            nfsvol[PATH_MAX]        = {0,};
+        char            tmpnfsvol[PATH_MAX]     = {0,};
+        glusterd_conf_t *conf                   = NULL;
+        xlator_t        *this                   = THIS;
+        int             ret                     = -1;
+        int             tmpclean                = 0;
+        int             tmpfd                   = -1;
+
+        if ((!identical) || (!this) || (!this->private))
+                goto out;
+
+        conf = (glusterd_conf_t *) this->private;
+
+        /* Fetch the original NFS volfile */
+        glusterd_get_nodesvc_volfile ("nfs", conf->workdir,
+                                      nfsvol, sizeof (nfsvol));
+
+        /* Create the temporary NFS volfile */
+        snprintf (tmpnfsvol, sizeof (tmpnfsvol), "/tmp/gnfs-XXXXXX");
+        tmpfd = mkstemp (tmpnfsvol);
+        if (tmpfd < 0) {
+                gf_log (this->name, GF_LOG_WARNING,
+                                    "Unable to create temp file %s: (%s)",
+                                    tmpnfsvol, strerror (errno));
+                goto out;
+        }
+
+        tmpclean = 1; /* SET the flag to unlink() tmpfile */
+
+        ret = glusterd_create_global_volfile (build_nfs_graph,
+                                              tmpnfsvol, NULL);
+        if (ret)
+                goto out;
+
+        /* Compare the topology of volfiles */
+        ret = glusterd_check_topology_identical (nfsvol, tmpnfsvol,
+                                                 identical);
+out:
+        if (tmpfd >= 0)
+                close (tmpfd);
+        if (tmpclean)
+                unlink (tmpnfsvol);
+        return ret;
+}
+
+int
 glusterd_check_nfs_volfile_identical (gf_boolean_t *identical)
 {
         char            nfsvol[PATH_MAX]        = {0,};
diff --git a/xlators/mgmt/glusterd/src/glusterd-volgen.h b/xlators/mgmt/glusterd/src/glusterd-volgen.h
index 31bfe980dee..2d31c4040a4 100644
--- a/xlators/mgmt/glusterd/src/glusterd-volgen.h
+++ b/xlators/mgmt/glusterd/src/glusterd-volgen.h
@@ -144,6 +144,8 @@ char*
 glusterd_get_trans_type_rb (gf_transport_type ttype);
 int
 glusterd_check_nfs_volfile_identical (gf_boolean_t *identical);
+int
+glusterd_check_nfs_topology_identical (gf_boolean_t *identical);
 
 uint32_t
 glusterd_get_op_version_for_key (char *key);