glusterd/svc: update pid of mux volumes from the shd process

For a normal volume, we are updating the pid from a the
process while we do a daemonization or at the end of the
init if it is no-daemon mode. Along with updating the pid
we also lock the file, to make sure that the process is
running fine.

With brick mux, we were updating the pidfile from gluterd
after an attach/detach request.

There are two problems with this approach.
1) We are not holding a pidlock for any file other than parent
   process.
2) There is a chance for possible race conditions with attach/detach.
   For example, shd start and a volume stop could race. Let's say
   we are starting an shd and it is attached to a volume.
   While we trying to link the pid file to the running process,
   this would have deleted by the thread that doing a volume stop.

Backport of : https://review.gluster.org/#/c/glusterfs/+/22935/
>Change-Id: I29a00352102877ce09ea3f376ca52affceb5cf1a
>Updates: bz#1722541
>Signed-off-by: Mohammed Rafi KC <rkavunga@redhat.com>

Change-Id: I29a00352102877ce09ea3f376ca52affceb5cf1a
Updates: bz#1732668
Signed-off-by: Mohammed Rafi KC <rkavunga@redhat.com>

1 files changed, 37 insertions, 5 deletions

diff --git a/xlators/mgmt/glusterd/src/glusterd-handshake.c b/xlators/mgmt/glusterd/src/glusterd-handshake.c
index f27b60513b7..fc7448e7fa0 100644
--- a/xlators/mgmt/glusterd/src/glusterd-handshake.c
+++ b/xlators/mgmt/glusterd/src/glusterd-handshake.c
@@ -202,7 +202,7 @@ out:
 
 size_t
 build_volfile_path(char *volume_id, char *path, size_t path_len,
-                   char *trusted_str)
+                   char *trusted_str, dict_t *dict)
 {
     struct stat stbuf = {
         0,
@@ -319,11 +319,19 @@ build_volfile_path(char *volume_id, char *path, size_t path_len,
 
         ret = glusterd_volinfo_find(volid_ptr, &volinfo);
         if (ret == -1) {
-            gf_log(this->name, GF_LOG_ERROR, "Couldn't find volinfo");
+            gf_msg(this->name, GF_LOG_ERROR, 0, GD_MSG_VOLINFO_GET_FAIL,
+                   "Couldn't find volinfo for volid=%s", volid_ptr);
             goto out;
         }
 
         glusterd_svc_build_shd_volfile_path(volinfo, path, path_len);
+
+        ret = glusterd_svc_set_shd_pidfile(volinfo, dict);
+        if (ret == -1) {
+            gf_msg(this->name, GF_LOG_ERROR, 0, GD_MSG_DICT_SET_FAILED,
+                   "Couldn't set pidfile in dict for volid=%s", volid_ptr);
+            goto out;
+        }
         ret = 0;
         goto out;
     }
@@ -898,6 +906,7 @@ __server_getspec(rpcsvc_request_t *req)
     char addrstr[RPCSVC_PEER_STRLEN] = {0};
     peer_info_t *peerinfo = NULL;
     xlator_t *this = NULL;
+    dict_t *dict = NULL;
 
     this = THIS;
     GF_ASSERT(this);
@@ -955,6 +964,12 @@ __server_getspec(rpcsvc_request_t *req)
         goto fail;
     }
 
+    dict = dict_new();
+    if (!dict) {
+        ret = -ENOMEM;
+        goto fail;
+    }
+
     trans = req->trans;
     /* addrstr will be empty for cli socket connections */
     ret = rpcsvc_transport_peername(trans, (char *)&addrstr, sizeof(addrstr));
@@ -977,12 +992,26 @@ __server_getspec(rpcsvc_request_t *req)
      */
     if (strlen(addrstr) == 0 || gf_is_local_addr(addrstr)) {
         ret = build_volfile_path(volume, filename, sizeof(filename),
-                                 TRUSTED_PREFIX);
+                                 TRUSTED_PREFIX, dict);
     } else {
-        ret = build_volfile_path(volume, filename, sizeof(filename), NULL);
+        ret = build_volfile_path(volume, filename, sizeof(filename), NULL,
+                                 dict);
     }
 
     if (ret == 0) {
+        if (dict->count > 0) {
+            ret = dict_allocate_and_serialize(dict, &rsp.xdata.xdata_val,
+                                              &rsp.xdata.xdata_len);
+            if (ret) {
+                gf_msg(this->name, GF_LOG_ERROR, 0,
+                       GD_MSG_DICT_SERL_LENGTH_GET_FAIL,
+                       "Failed to serialize dict "
+                       "to request buffer");
+                goto fail;
+            }
+            dict->extra_free = rsp.xdata.xdata_val;
+        }
+
         /* to allocate the proper buffer to hold the file data */
         ret = sys_stat(filename, &stbuf);
         if (ret < 0) {
@@ -1024,7 +1053,6 @@ __server_getspec(rpcsvc_request_t *req)
             goto fail;
         }
     }
-
     /* convert to XDR */
 fail:
     if (spec_fd >= 0)
@@ -1047,6 +1075,10 @@ fail:
                           (xdrproc_t)xdr_gf_getspec_rsp);
     free(args.key);  // malloced by xdr
     free(rsp.spec);
+
+    if (dict)
+        dict_unref(dict);
+
     if (args.xdata.xdata_val)
         free(args.xdata.xdata_val);