glusterd: log appropriate message when locking fails

PROBLEM:

When a transaction is already in progress, and the user tries to
execute another glusterd operation, the second operation fails as
glusterd fails to acquire lock. But to the user, a message like
"Operation failed" does not give ample information about why the
operation failed.

FIX:

Made glusterd_op_txn_begin use and initialise error string, which is
needed to capture failure in the "lock" phase.

Also made gd_sync_task_begin set error string appropriately when
locking fails.

In the process, I had to introduce error string in some glusterd_handle_*
functions. And because I introduced error string in these handlers, I
decided to also set them in places where these handlers could possibly
fail.

HOW I TESTED IT:

For want of a better idea, I "commented out" the call to
"glusterd_unlock", recompiled glusterd and ran two glusterd volume
operations, one after the other. The second operation fails with the
message "Another transaction is in progress. Please try again after
sometime." as expected.

The tests were performed on two volume ops : one of them
synctask'ized (volume start) and the other NOT (volume create).

Change-Id: Ia862972929872ae2f053707a544824d9cadc37be
BUG: 873549
Signed-off-by: Krutika Dhananjay <kdhananj@redhat.com>
Reviewed-on: http://review.gluster.org/4197
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Anand Avati <avati@redhat.com>

1 files changed, 113 insertions, 50 deletions

diff --git a/xlators/mgmt/glusterd/src/glusterd-handler.c b/xlators/mgmt/glusterd/src/glusterd-handler.c
index ff8fe3225..ff2c8e71c 100644
--- a/xlators/mgmt/glusterd/src/glusterd-handler.c
+++ b/xlators/mgmt/glusterd/src/glusterd-handler.c
@@ -445,7 +445,8 @@ out:
 }
 
 int32_t
-glusterd_op_txn_begin (rpcsvc_request_t *req, glusterd_op_t op, void *ctx)
+glusterd_op_txn_begin (rpcsvc_request_t *req, glusterd_op_t op, void *ctx,
+                       char *err_str, size_t err_len)
 {
         int32_t                  ret    = -1;
         xlator_t                *this   = NULL;
@@ -464,6 +465,8 @@ glusterd_op_txn_begin (rpcsvc_request_t *req, glusterd_op_t op, void *ctx)
         if (ret) {
                 gf_log (this->name, GF_LOG_ERROR,
                         "Unable to acquire local lock, ret: %d", ret);
+                snprintf (err_str, err_len, "Another transaction is in progress. "
+                          "Please try again after sometime.");
                 goto out;
         }
 
@@ -951,7 +954,7 @@ glusterd_handle_cli_bd_op (rpcsvc_request_t *req)
         gf_cli_req       cli_req    = { {0,} };
         dict_t           *dict      = NULL;
         char             *volname   = NULL;
-        char             *op_errstr = NULL;
+        char             op_errstr[2048] = {0,};
         glusterd_op_t    cli_op     = GD_OP_BD_OP;
 
         GF_ASSERT (req);
@@ -989,7 +992,8 @@ glusterd_handle_cli_bd_op (rpcsvc_request_t *req)
                 goto out;
         }
 
-        ret = glusterd_op_begin (req, GD_OP_BD_OP, dict);
+        ret = glusterd_op_begin (req, GD_OP_BD_OP, dict, op_errstr,
+                                 sizeof (op_errstr));
         gf_cmd_log ("bd op: %s", ((ret == 0) ? "SUCCESS": "FAILED"));
 out:
         if (ret && dict)
@@ -999,11 +1003,11 @@ out:
         glusterd_op_sm ();
 
         if (ret) {
-                if (!op_errstr)
-                        op_errstr = gf_strdup ("operation failed");
+                if (op_errstr[0] == '\0')
+                        snprintf (op_errstr, sizeof (op_errstr),
+                                  "Operation failed");
                 ret = glusterd_op_send_cli_response (cli_op, ret, 0,
                                 req, NULL, op_errstr);
-                GF_FREE (op_errstr);
         }
 
         return ret;
@@ -1171,11 +1175,12 @@ out:
 }
 
 int32_t
-glusterd_op_begin (rpcsvc_request_t *req, glusterd_op_t op, void *ctx)
+glusterd_op_begin (rpcsvc_request_t *req, glusterd_op_t op, void *ctx,
+                   char *err_str, size_t err_len)
 {
         int             ret = -1;
 
-        ret = glusterd_op_txn_begin (req, op, ctx);
+        ret = glusterd_op_txn_begin (req, op, ctx, err_str, err_len);
 
         return ret;
 }
@@ -1188,8 +1193,11 @@ glusterd_handle_reset_volume (rpcsvc_request_t *req)
         dict_t                          *dict = NULL;
         glusterd_op_t                   cli_op = GD_OP_RESET_VOLUME;
         char                            *volname = NULL;
+        char                            err_str[2048] = {0,};
+        xlator_t                        *this = NULL;
 
         GF_ASSERT (req);
+        this = THIS;
 
         ret = xdr_to_generic (req->msg[0], &cli_req, (xdrproc_t)xdr_gf_cli_req);
         if (ret < 0) {
@@ -1206,8 +1214,10 @@ glusterd_handle_reset_volume (rpcsvc_request_t *req)
                                         cli_req.dict.dict_len,
                                         &dict);
                 if (ret < 0) {
-                        gf_log ("glusterd", GF_LOG_ERROR, "failed to "
+                        gf_log (this->name, GF_LOG_ERROR, "failed to "
                                     "unserialize req-buffer to dictionary");
+                        snprintf (err_str, sizeof (err_str), "Unable to decode "
+                                  "the command");
                         goto out;
                 } else {
                         dict->extra_stdfree = cli_req.dict.dict_val;
@@ -1216,18 +1226,24 @@ glusterd_handle_reset_volume (rpcsvc_request_t *req)
 
         ret = dict_get_str (dict, "volname", &volname);
         if (ret) {
-                gf_log (THIS->name, GF_LOG_ERROR, "failed to get volname");
+                snprintf (err_str, sizeof (err_str), "Failed to get volume "
+                          "name");
+                gf_log (this->name, GF_LOG_ERROR, "%s", err_str);
                 goto out;
         }
 
-        ret = glusterd_op_begin (req, GD_OP_RESET_VOLUME, dict);
+        ret = glusterd_op_begin (req, GD_OP_RESET_VOLUME, dict,
+                                 err_str, sizeof (err_str));
 
 out:
         glusterd_friend_sm ();
         glusterd_op_sm ();
         if (ret) {
+                if (err_str[0] == '\0')
+                        snprintf (err_str, sizeof (err_str),
+                                  "Operation failed");
                 ret = glusterd_op_send_cli_response (cli_op, ret, 0, req,
-                                                     dict, "operation failed");
+                                                     dict, err_str);
                 if (dict)
                         dict_unref (dict);
         }
@@ -1248,6 +1264,8 @@ glusterd_handle_set_volume (rpcsvc_request_t *req)
         char                            *volname = NULL;
         char                            *op_errstr = NULL;
         gf_boolean_t                    help = _gf_false;
+        char                            err_str[2048] = {0,};
+        xlator_t                        *this = NULL;
 
         GF_ASSERT (req);
 
@@ -1266,9 +1284,11 @@ glusterd_handle_set_volume (rpcsvc_request_t *req)
                                         cli_req.dict.dict_len,
                                         &dict);
                 if (ret < 0) {
-                        gf_log ("glusterd", GF_LOG_ERROR,
+                        gf_log (this->name, GF_LOG_ERROR,
                                 "failed to "
                                 "unserialize req-buffer to dictionary");
+                        snprintf (err_str, sizeof (err_str), "Unable to decode "
+                                  "the command");
                         goto out;
                 } else {
                         dict->extra_stdfree = cli_req.dict.dict_val;
@@ -1277,8 +1297,9 @@ glusterd_handle_set_volume (rpcsvc_request_t *req)
 
         ret = dict_get_str (dict, "volname", &volname);
         if (ret) {
-                gf_log ("", GF_LOG_WARNING, "Unable to get volume name, while"
-                        "handling volume set command");
+                snprintf (err_str, sizeof (err_str), "Failed to get volume "
+                          "name while handling volume set command");
+                gf_log (this->name, GF_LOG_ERROR, "%s", err_str);
                 goto out;
         }
 
@@ -1291,19 +1312,22 @@ glusterd_handle_set_volume (rpcsvc_request_t *req)
 
         ret = dict_get_str (dict, "key1", &key);
         if (ret) {
-                gf_log ("", GF_LOG_WARNING, "Unable to get key, while "
-                        "handling volume set for %s",volname);
+                snprintf (err_str, sizeof (err_str), "Failed to get key while"
+                          " handling volume set for %s", volname);
+                gf_log (this->name, GF_LOG_ERROR, "%s", err_str);
                 goto out;
         }
 
         ret = dict_get_str (dict, "value1", &value);
         if (ret) {
-                gf_log ("", GF_LOG_WARNING, "Unable to get value, while"
-                        "handling volume set for %s",volname);
+                snprintf (err_str, sizeof (err_str), "Failed to get value while"
+                          " handling volume set for %s", volname);
+                gf_log (this->name, GF_LOG_ERROR, "%s", err_str);
                 goto out;
         }
 
-        ret = glusterd_op_begin (req, GD_OP_SET_VOLUME, dict);
+        ret = glusterd_op_begin (req, GD_OP_SET_VOLUME, dict,
+                                 err_str, sizeof (err_str));
 
 out:
         glusterd_friend_sm ();
@@ -1312,9 +1336,13 @@ out:
         if (help)
                 ret = glusterd_op_send_cli_response (cli_op, ret, 0, req, dict,
                                                      (op_errstr)? op_errstr:"");
-        else if (ret)
+        else if (ret) {
+                if (err_str[0] == '\0')
+                        snprintf (err_str, sizeof (err_str),
+                                  "Operation failed");
                 ret = glusterd_op_send_cli_response (cli_op, ret, 0, req,
-                                                     dict, "operation failed");
+                                                     dict, err_str);
+        }
         if (op_errstr)
                 GF_FREE (op_errstr);
 
@@ -1332,8 +1360,10 @@ glusterd_handle_sync_volume (rpcsvc_request_t *req)
         char                             *volname = NULL;
         gf1_cli_sync_volume              flags = 0;
         char                             *hostname = NULL;
+        xlator_t                         *this = NULL;
 
         GF_ASSERT (req);
+        this = THIS;
 
         ret = xdr_to_generic (req->msg[0], &cli_req, (xdrproc_t)xdr_gf_cli_req);
         if (ret < 0) {
@@ -1350,9 +1380,11 @@ glusterd_handle_sync_volume (rpcsvc_request_t *req)
                                         cli_req.dict.dict_len,
                                         &dict);
                 if (ret < 0) {
-                        gf_log ("glusterd", GF_LOG_ERROR,
+                        gf_log (this->name, GF_LOG_ERROR,
                                 "failed to "
                                 "unserialize req-buffer to dictionary");
+                        snprintf (msg, sizeof (msg), "Unable to decode the "
+                                  "command");
                         goto out;
                 } else {
                         dict->extra_stdfree = cli_req.dict.dict_val;
@@ -1361,7 +1393,8 @@ glusterd_handle_sync_volume (rpcsvc_request_t *req)
 
         ret = dict_get_str (dict, "hostname", &hostname);
         if (ret) {
-                gf_log (THIS->name, GF_LOG_ERROR, "failed to get hostname");
+                snprintf (msg, sizeof (msg), "Failed to get hostname");
+                gf_log (this->name, GF_LOG_ERROR, "%s", msg);
                 goto out;
         }
 
@@ -1369,24 +1402,26 @@ glusterd_handle_sync_volume (rpcsvc_request_t *req)
         if (ret) {
                 ret = dict_get_int32 (dict, "flags", (int32_t*)&flags);
                 if (ret) {
-                        gf_log (THIS->name, GF_LOG_ERROR, "Unable to get volume"
-                                "name, or flags");
+                        snprintf (msg, sizeof (msg), "Failed to get volume name"
+                                  " or flags");
+                        gf_log (this->name, GF_LOG_ERROR, "%s", msg);
                         goto out;
                 }
         }
 
-        gf_log ("glusterd", GF_LOG_INFO, "Received volume sync req "
-                "for volume %s",
-                (flags & GF_CLI_SYNC_ALL) ? "all" : volname);
+        gf_log (this->name, GF_LOG_INFO, "Received volume sync req "
+                "for volume %s", (flags & GF_CLI_SYNC_ALL) ? "all" : volname);
 
         if (!glusterd_is_local_addr (hostname)) {
                 ret = -1;
                 snprintf (msg, sizeof (msg), "sync from localhost"
                           " not allowed");
+                gf_log (this->name, GF_LOG_ERROR, "%s", msg);
                 goto out;
         }
 
-        ret = glusterd_op_begin (req, GD_OP_SYNC_VOLUME, dict);
+        ret = glusterd_op_begin (req, GD_OP_SYNC_VOLUME, dict,
+                                 msg, sizeof (msg));
 
 out:
         if (ret) {
@@ -2017,8 +2052,11 @@ glusterd_handle_cli_profile_volume (rpcsvc_request_t *req)
         glusterd_op_t                   cli_op = GD_OP_PROFILE_VOLUME;
         char                            *volname = NULL;
         int32_t                         op = 0;
+        char                            err_str[2048] = {0,};
+        xlator_t                        *this = NULL;
 
         GF_ASSERT (req);
+        this = THIS;
 
         ret = xdr_to_generic (req->msg[0], &cli_req, (xdrproc_t)xdr_gf_cli_req);
         if (ret < 0) {
@@ -2037,19 +2075,22 @@ glusterd_handle_cli_profile_volume (rpcsvc_request_t *req)
 
         ret = dict_get_str (dict, "volname", &volname);
         if (ret) {
-                gf_log (THIS->name, GF_LOG_ERROR, "failed to get volname");
+                snprintf (err_str, sizeof (err_str), "Unable to get volume "
+                          "name");
+                gf_log (this->name, GF_LOG_ERROR, "%s", err_str);
                 goto out;
         }
 
-        gf_log (THIS->name, GF_LOG_INFO, "Received volume profile req "
+        gf_log (this->name, GF_LOG_INFO, "Received volume profile req "
                 "for volume %s", volname);
         ret = dict_get_int32 (dict, "op", &op);
         if (ret) {
-                gf_log (THIS->name, GF_LOG_ERROR, "failed to get op");
+                snprintf (err_str, sizeof (err_str), "Unable to get operation");
+                gf_log (this->name, GF_LOG_ERROR, "%s", err_str);
                 goto out;
         }
 
-        ret = glusterd_op_begin (req, cli_op, dict);
+        ret = glusterd_op_begin (req, cli_op, dict, err_str, sizeof (err_str));
 
 out:
         glusterd_friend_sm ();
@@ -2057,13 +2098,16 @@ out:
 
         free (cli_req.dict.dict_val);
         if (ret) {
+                if (err_str[0] == '\0')
+                        snprintf (err_str, sizeof (err_str),
+                                  "Operation failed");
                 ret = glusterd_op_send_cli_response (cli_op, ret, 0, req,
-                                                     dict, "operation failed");
+                                                     dict, err_str);
                 if (dict)
                         dict_unref (dict);
         }
 
-        gf_log (THIS->name, GF_LOG_DEBUG, "Returning %d", ret);
+        gf_log (this->name, GF_LOG_DEBUG, "Returning %d", ret);
         return ret;
 }
 
@@ -2845,8 +2889,11 @@ glusterd_handle_status_volume (rpcsvc_request_t *req)
         char                           *volname = 0;
         gf_cli_req                      cli_req = {{0,}};
         glusterd_op_t                   cli_op  = GD_OP_STATUS_VOLUME;
+        char                            err_str[2048] = {0,};
+        xlator_t                       *this = NULL;
 
         GF_ASSERT (req);
+        this = THIS;
 
         ret = xdr_to_generic (req->msg[0], &cli_req, (xdrproc_t)xdr_gf_cli_req);
         if (ret < 0) {
@@ -2862,8 +2909,10 @@ glusterd_handle_status_volume (rpcsvc_request_t *req)
                 ret = dict_unserialize (cli_req.dict.dict_val,
                                         cli_req.dict.dict_len, &dict);
                 if (ret < 0) {
-                        gf_log (THIS->name, GF_LOG_ERROR, "failed to "
+                        gf_log (this->name, GF_LOG_ERROR, "failed to "
                                 "unserialize buffer");
+                        snprintf (err_str, sizeof (err_str), "Unable to decode "
+                                  "the command");
                         goto out;
                 }
 
@@ -2876,25 +2925,29 @@ glusterd_handle_status_volume (rpcsvc_request_t *req)
         if (!(cmd & GF_CLI_STATUS_ALL)) {
                 ret = dict_get_str (dict, "volname", &volname);
                 if (ret) {
-                        gf_log (THIS->name, GF_LOG_ERROR,
-                                "failed to get volname");
+                        snprintf (err_str, sizeof (err_str), "Unable to get "
+                                  "volume name");
+                        gf_log (this->name, GF_LOG_ERROR, "%s", err_str);
                         goto out;
                 }
-                gf_log (THIS->name, GF_LOG_INFO,
-                        "Received status volume req "
-                        "for volume %s", volname);
+                gf_log (this->name, GF_LOG_INFO,
+                        "Received status volume req for volume %s", volname);
 
         }
 
-        ret = glusterd_op_begin (req, GD_OP_STATUS_VOLUME, dict);
+        ret = glusterd_op_begin (req, GD_OP_STATUS_VOLUME, dict,
+                                 err_str, sizeof (err_str));
 
 out:
         glusterd_friend_sm ();
         glusterd_op_sm ();
 
         if (ret) {
+                if (err_str[0] == '\0')
+                        snprintf (err_str, sizeof (err_str),
+                                  "Operation failed");
                 ret = glusterd_op_send_cli_response (cli_op, ret, 0, req,
-                                                     dict, "operation failed");
+                                                     dict, err_str);
                 if (dict)
                         dict_unref (dict);
         }
@@ -2911,8 +2964,11 @@ glusterd_handle_cli_clearlocks_volume (rpcsvc_request_t *req)
         glusterd_op_t                   cli_op = GD_OP_CLEARLOCKS_VOLUME;
         char                            *volname = NULL;
         dict_t                          *dict = NULL;
+        char                            err_str[2048] = {0,};
+        xlator_t                        *this = NULL;
 
         GF_ASSERT (req);
+        this = THIS;
 
         ret = -1;
         ret = xdr_to_generic (req->msg[0], &cli_req, (xdrproc_t)xdr_gf_cli_req);
@@ -2928,36 +2984,43 @@ glusterd_handle_cli_clearlocks_volume (rpcsvc_request_t *req)
                                         cli_req.dict.dict_len,
                                         &dict);
                 if (ret < 0) {
-                        gf_log (THIS->name, GF_LOG_ERROR,
+                        gf_log (this->name, GF_LOG_ERROR,
                                 "failed to unserialize req-buffer to"
                                 " dictionary");
+                        snprintf (err_str, sizeof (err_str), "unable to decode "
+                                  "the command");
                         goto out;
                 }
 
         } else {
                 ret = -1;
-                gf_log (THIS->name, GF_LOG_ERROR, "Empty cli request.");
+                gf_log (this->name, GF_LOG_ERROR, "Empty cli request.");
                 goto out;
         }
 
         ret = dict_get_str (dict, "volname", &volname);
         if (ret) {
-                gf_log (THIS->name, GF_LOG_ERROR, "failed to get volname");
+                snprintf (err_str, sizeof (err_str), "Unable to get volume "
+                          "name");
+                gf_log (this->name, GF_LOG_ERROR, "%s", err_str);
                 goto out;
         }
 
-        gf_log (THIS->name, GF_LOG_INFO, "Received clear-locks volume req "
+        gf_log (this->name, GF_LOG_INFO, "Received clear-locks volume req "
                 "for volume %s", volname);
 
-        ret = glusterd_op_begin (req, cli_op, dict);
+        ret = glusterd_op_begin (req, cli_op, dict, err_str, sizeof (err_str));
 
 out:
         glusterd_friend_sm ();
         glusterd_op_sm ();
 
         if (ret) {
+                if (err_str[0] == '\0')
+                        snprintf (err_str, sizeof (err_str),
+                                  "Operation failed");
                 ret = glusterd_op_send_cli_response (cli_op, ret, 0, req,
-                                                     dict, "operation failed");
+                                                     dict, err_str);
                 if (dict)
                         dict_unref (dict);
         }