gfapi: add API to trigger events for debugging and troubleshooting

Introduce glfs_sysrq() as a generic API for triggering debug and
troubleshoot events. This interface will be used by the feature to get
statedumps for applications using libgfapi.

The current events that can be requested through this API are:
 - 'h'elp: log a mesage with all supported events
 - 's'tatedump: trigger a statedump for the passed glfs_t

In future, this API can be used by a CLI to trigger statedumps from
storage servers. At the moment it is limited to take statedumps, but it
is extensible to set the log-level, clear caches, force reconnects and
much more.

BUG: 1169302
Change-Id: I18858359a3957870cea5139c79efe1365a15a992
Original-author: Poornima G <pgurusid@redhat.com>
Signed-off-by: Niels de Vos <ndevos@redhat.com>
Reviewed-on: http://review.gluster.org/16414
Reviewed-by: Prashanth Pai <ppai@redhat.com>
Smoke: Gluster Build System <jenkins@build.gluster.org>
NetBSD-regression: NetBSD Build System <jenkins@build.gluster.org>
CentOS-regression: Gluster Build System <jenkins@build.gluster.org>
Reviewed-by: Kaleb KEITHLEY <kkeithle@redhat.com>

5 files changed, 88 insertions, 5 deletions

diff --git a/api/src/gfapi-messages.h b/api/src/gfapi-messages.h
index 5deef15e3ae..6e131b5a295 100644
--- a/api/src/gfapi-messages.h
+++ b/api/src/gfapi-messages.h
@@ -40,7 +40,7 @@
  */
 
 #define GLFS_GFAPI_BASE             GLFS_MSGID_COMP_API
-#define GLFS_NUM_MESSAGES           48
+#define GLFS_NUM_MESSAGES           49
 #define GLFS_MSGID_END              (GLFS_GFAPI_BASE + GLFS_NUM_MESSAGES + 1)
 /* Messages with message IDs */
 #define glfs_msg_start_x GLFS_GFAPI_BASE, "Invalid: Start of messages"
@@ -94,6 +94,7 @@
 #define API_MSG_ALLOC_FAILED                    (GLFS_GFAPI_BASE + 46)
 #define API_MSG_CREATE_HANDLE_FAILED            (GLFS_GFAPI_BASE + 47)
 #define API_MSG_INODE_LINK_FAILED               (GLFS_GFAPI_BASE + 48)
+#define API_MSG_STATEDUMP_FAILED                (GLFS_GFAPI_BASE + 49)
 
 /*------------*/
 #define glfs_msg_end_x GLFS_MSGID_END, "Invalid: End of messages"
diff --git a/api/src/gfapi.aliases b/api/src/gfapi.aliases
index d2c4ba2f037..5acfebd83d9 100644
--- a/api/src/gfapi.aliases
+++ b/api/src/gfapi.aliases
@@ -156,4 +156,6 @@ _pub_glfs_upcall_inode_get_oldpobject _glfs_upcall_inode_get_oldpobject$GFAPI_3.
 _pub_glfs_upcall_inode_get_oldpstat _glfs_upcall_inode_get_oldpstat$GFAPI_3.7.16
 _pub_glfs_realpath _glfs_realpath$GFAPI_3.7.17
 
+_pub_glfs_sysrq _glfs_sysrq$GFAPI_3.10.0
+
 _pub_glfs_ipc _glfs_ipc$GFAPI_4.0.0
diff --git a/api/src/gfapi.map b/api/src/gfapi.map
index d022380497f..b6eb9a748e1 100644
--- a/api/src/gfapi.map
+++ b/api/src/gfapi.map
@@ -194,7 +194,12 @@ GFAPI_3.7.17 {
 		glfs_realpath;
 } GFAPI_3.7.16;
 
+GFAPI_3.10.0 {
+	global:
+		glfs_sysrq;
+} GFAPI_3.7.17;
+
 GFAPI_4.0.0 {
 	global:
 		glfs_ipc;
-} GFAPI_3.7.17;
+} GFAPI_3.10.0;
diff --git a/api/src/glfs.c b/api/src/glfs.c
index 4375774a853..94a12c0be31 100644
--- a/api/src/glfs.c
+++ b/api/src/glfs.c
@@ -40,12 +40,13 @@
 #include "common-utils.h"
 #include "syncop.h"
 #include "call-stub.h"
-#include "gfapi-messages.h"
+#include "hashfn.h"
+#include "rpc-clnt.h"
+#include "statedump.h"
 
+#include "gfapi-messages.h"
 #include "glfs.h"
 #include "glfs-internal.h"
-#include "hashfn.h"
-#include "rpc-clnt.h"
 
 
 static gf_boolean_t
@@ -1462,3 +1463,60 @@ pub_glfs_upcall_inode_get_oldpstat (struct glfs_upcall_inode *arg)
         return &arg->oldp_buf;
 }
 GFAPI_SYMVER_PUBLIC_DEFAULT(glfs_upcall_inode_get_oldpstat, 3.7.16);
+
+
+/* definitions of the GLFS_SYSRQ_* chars are in glfs.h */
+static struct glfs_sysrq_help {
+        char  sysrq;
+        char *msg;
+} glfs_sysrq_help[] = {
+        { GLFS_SYSRQ_HELP,      "(H)elp" },
+        { GLFS_SYSRQ_STATEDUMP, "(S)tatedump" },
+        { 0,                    NULL }
+};
+
+int
+pub_glfs_sysrq (struct glfs *fs, char sysrq)
+{
+        glusterfs_ctx_t  *ctx = NULL;
+        int               ret = 0;
+
+        if (!fs || !fs->ctx) {
+                ret = -1;
+                errno = EINVAL;
+                goto out;
+        }
+
+        ctx = fs->ctx;
+
+        switch (sysrq) {
+        case GLFS_SYSRQ_HELP:
+        {
+                char msg[1024]; /* help text should not exceed 1024 chars */
+                struct glfs_sysrq_help *usage;
+
+                msg[0] = '\0';
+                for (usage = glfs_sysrq_help; usage->sysrq; usage++) {
+                        strncat (msg, usage->msg, 1024);
+                        strncat (msg, " ", 1024);
+                }
+
+                /* not really an 'error', but make sure it gets logged */
+                gf_log ("glfs", GF_LOG_ERROR, "available events: %s", msg);
+
+                break;
+        }
+        case GLFS_SYSRQ_STATEDUMP:
+                gf_proc_dump_info (SIGUSR1, ctx);
+                break;
+        default:
+                gf_msg ("glfs", GF_LOG_ERROR, ENOTSUP, API_MSG_INVALID_ENTRY,
+                        "'%c' is not a valid sysrq", sysrq);
+                errno = ENOTSUP;
+                ret = -1;
+        }
+out:
+        return ret;
+}
+
+GFAPI_SYMVER_PUBLIC_DEFAULT(glfs_sysrq, 3.10.0);
diff --git a/api/src/glfs.h b/api/src/glfs.h
index 903492a9466..f5a0e1a2a84 100644
--- a/api/src/glfs.h
+++ b/api/src/glfs.h
@@ -773,6 +773,23 @@ void glfs_free (void *ptr) __THROW
         GFAPI_PUBLIC(glfs_free, 3.7.16);
 
 /*
+ * glfs_sysrq: send a system request to the @fs instance
+ *
+ * Different commands for @sysrq are possible, the defines for these are listed
+ * below the function definition.
+ *
+ * This function always returns success if the @sysrq is recognized. The return
+ * value does not way anythin about the result of the @sysrq execution. Not all
+ * @sysrq command will be able to return a success/failure status.
+ */
+int glfs_sysrq (glfs_t *fs, char sysrq) __THROW
+        GFAPI_PUBLIC(glfs_sysrq, 3.10.0);
+
+#define GLFS_SYSRQ_HELP 'h' /* log a message with supported sysrq commands */
+#define GLFS_SYSRQ_STATEDUMP 's' /* create a statedump */
+
+
+/*
  * Nobody needs this call at all yet except for the test script.
  */
 int glfs_ipc (glfs_fd_t *fd, int cmd,  void *xd_in, void **xd_out) __THROW