fs/ocfs2/stackglue.c

   1 /* -*- mode: c; c-basic-offset: 8; -*-
   2  * vim: noexpandtab sw=8 ts=8 sts=0:
   3  *
   4  * stackglue.c
   5  *
   6  * Code which implements an OCFS2 specific interface to underlying
   7  * cluster stacks.
   8  *
   9  * Copyright (C) 2007, 2009 Oracle.  All rights reserved.
  10  *
  11  * This program is free software; you can redistribute it and/or
  12  * modify it under the terms of the GNU General Public
  13  * License as published by the Free Software Foundation, version 2.
  14  *
  15  * This program is distributed in the hope that it will be useful,
  16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  18  * General Public License for more details.
  19  */
  20
  21 #include <linux/list.h>
  22 #include <linux/spinlock.h>
  23 #include <linux/module.h>
  24 #include <linux/slab.h>
  25 #include <linux/kmod.h>
  26 #include <linux/fs.h>
  27 #include <linux/kobject.h>
  28 #include <linux/sysfs.h>
  29 #include <linux/sysctl.h>
  30
  31 #include "ocfs2_fs.h"
  32
  33 #include "stackglue.h"
  34
  35 #define OCFS2_STACK_PLUGIN_O2CB         "o2cb"
  36 #define OCFS2_STACK_PLUGIN_USER         "user"
  37 #define OCFS2_MAX_HB_CTL_PATH           256
  38
  39 static struct ocfs2_protocol_version locking_max_version;
  40 static DEFINE_SPINLOCK(ocfs2_stack_lock);
  41 static LIST_HEAD(ocfs2_stack_list);
  42 static char cluster_stack_name[OCFS2_STACK_LABEL_LEN + 1];
  43 static char ocfs2_hb_ctl_path[OCFS2_MAX_HB_CTL_PATH] = "/sbin/ocfs2_hb_ctl";
  44
  45 /*
  46  * The stack currently in use.  If not null, active_stack->sp_count > 0,
  47  * the module is pinned, and the locking protocol cannot be changed.
  48  */
  49 static struct ocfs2_stack_plugin *active_stack;
  50
  51 static struct ocfs2_stack_plugin *ocfs2_stack_lookup(const char *name)
  52 {
  53         struct ocfs2_stack_plugin *p;
  54
  55         assert_spin_locked(&ocfs2_stack_lock);
  56
  57         list_for_each_entry(p, &ocfs2_stack_list, sp_list) {
  58                 if (!strcmp(p->sp_name, name))
  59                         return p;
  60         }
  61
  62         return NULL;
  63 }
  64
  65 static int ocfs2_stack_driver_request(const char *stack_name,
  66                                       const char *plugin_name)
  67 {
  68         int rc;
  69         struct ocfs2_stack_plugin *p;
  70
  71         spin_lock(&ocfs2_stack_lock);
  72
  73         /*
  74          * If the stack passed by the filesystem isn't the selected one,
  75          * we can't continue.
  76          */
  77         if (strcmp(stack_name, cluster_stack_name)) {
  78                 rc = -EBUSY;
  79                 goto out;
  80         }
  81
  82         if (active_stack) {
  83                 /*
  84                  * If the active stack isn't the one we want, it cannot
  85                  * be selected right now.
  86                  */
  87                 if (!strcmp(active_stack->sp_name, plugin_name))
  88                         rc = 0;
  89                 else
  90                         rc = -EBUSY;
  91                 goto out;
  92         }
  93
  94         p = ocfs2_stack_lookup(plugin_name);
  95         if (!p || !try_module_get(p->sp_owner)) {
  96                 rc = -ENOENT;
  97                 goto out;
  98         }
  99
 100         active_stack = p;
 101         rc = 0;
 102
 103 out:
 104         /* If we found it, pin it */
 105         if (!rc)
 106                 active_stack->sp_count++;
 107
 108         spin_unlock(&ocfs2_stack_lock);
 109         return rc;
 110 }
 111
 112 /*
 113  * This function looks up the appropriate stack and makes it active.  If
 114  * there is no stack, it tries to load it.  It will fail if the stack still
 115  * cannot be found.  It will also fail if a different stack is in use.
 116  */
 117 static int ocfs2_stack_driver_get(const char *stack_name)
 118 {
 119         int rc;
 120         char *plugin_name = OCFS2_STACK_PLUGIN_O2CB;
 121
 122         /*
 123          * Classic stack does not pass in a stack name.  This is
 124          * compatible with older tools as well.
 125          */
 126         if (!stack_name || !*stack_name)
 127                 stack_name = OCFS2_STACK_PLUGIN_O2CB;
 128
 129         if (strlen(stack_name) != OCFS2_STACK_LABEL_LEN) {
 130                 printk(KERN_ERR
 131                        "ocfs2 passed an invalid cluster stack label: \"%s\"\n",
 132                        stack_name);
 133                 return -EINVAL;
 134         }
 135
 136         /* Anything that isn't the classic stack is a user stack */
 137         if (strcmp(stack_name, OCFS2_STACK_PLUGIN_O2CB))
 138                 plugin_name = OCFS2_STACK_PLUGIN_USER;
 139
 140         rc = ocfs2_stack_driver_request(stack_name, plugin_name);
 141         if (rc == -ENOENT) {
 142                 request_module("ocfs2_stack_%s", plugin_name);
 143                 rc = ocfs2_stack_driver_request(stack_name, plugin_name);
 144         }
 145
 146         if (rc == -ENOENT) {
 147                 printk(KERN_ERR
 148                        "ocfs2: Cluster stack driver \"%s\" cannot be found\n",
 149                        plugin_name);
 150         } else if (rc == -EBUSY) {
 151                 printk(KERN_ERR
 152                        "ocfs2: A different cluster stack is in use\n");
 153         }
 154
 155         return rc;
 156 }
 157
 158 static void ocfs2_stack_driver_put(void)
 159 {
 160         spin_lock(&ocfs2_stack_lock);
 161         BUG_ON(active_stack == NULL);
 162         BUG_ON(active_stack->sp_count == 0);
 163
 164         active_stack->sp_count--;
 165         if (!active_stack->sp_count) {
 166                 module_put(active_stack->sp_owner);
 167                 active_stack = NULL;
 168         }
 169         spin_unlock(&ocfs2_stack_lock);
 170 }
 171
 172 int ocfs2_stack_glue_register(struct ocfs2_stack_plugin *plugin)
 173 {
 174         int rc;
 175
 176         spin_lock(&ocfs2_stack_lock);
 177         if (!ocfs2_stack_lookup(plugin->sp_name)) {
 178                 plugin->sp_count = 0;
 179                 plugin->sp_max_proto = locking_max_version;
 180                 list_add(&plugin->sp_list, &ocfs2_stack_list);
 181                 printk(KERN_INFO "ocfs2: Registered cluster interface %s\n",
 182                        plugin->sp_name);
 183                 rc = 0;
 184         } else {
 185                 printk(KERN_ERR "ocfs2: Stack \"%s\" already registered\n",
 186                        plugin->sp_name);
 187                 rc = -EEXIST;
 188         }
 189         spin_unlock(&ocfs2_stack_lock);
 190
 191         return rc;
 192 }
 193 EXPORT_SYMBOL_GPL(ocfs2_stack_glue_register);
 194
 195 void ocfs2_stack_glue_unregister(struct ocfs2_stack_plugin *plugin)
 196 {
 197         struct ocfs2_stack_plugin *p;
 198
 199         spin_lock(&ocfs2_stack_lock);
 200         p = ocfs2_stack_lookup(plugin->sp_name);
 201         if (p) {
 202                 BUG_ON(p != plugin);
 203                 BUG_ON(plugin == active_stack);
 204                 BUG_ON(plugin->sp_count != 0);
 205                 list_del_init(&plugin->sp_list);
 206                 printk(KERN_INFO "ocfs2: Unregistered cluster interface %s\n",
 207                        plugin->sp_name);
 208         } else {
 209                 printk(KERN_ERR "Stack \"%s\" is not registered\n",
 210                        plugin->sp_name);
 211         }
 212         spin_unlock(&ocfs2_stack_lock);
 213 }
 214 EXPORT_SYMBOL_GPL(ocfs2_stack_glue_unregister);
 215
 216 void ocfs2_stack_glue_set_max_proto_version(struct ocfs2_protocol_version *max_proto)
 217 {
 218         struct ocfs2_stack_plugin *p;
 219
 220         spin_lock(&ocfs2_stack_lock);
 221         if (memcmp(max_proto, &locking_max_version,
 222                    sizeof(struct ocfs2_protocol_version))) {
 223                 BUG_ON(locking_max_version.pv_major != 0);
 224
 225                 locking_max_version = *max_proto;
 226                 list_for_each_entry(p, &ocfs2_stack_list, sp_list) {
 227                         p->sp_max_proto = locking_max_version;
 228                 }
 229         }
 230         spin_unlock(&ocfs2_stack_lock);
 231 }
 232 EXPORT_SYMBOL_GPL(ocfs2_stack_glue_set_max_proto_version);
 233
 234
 235 /*
 236  * The ocfs2_dlm_lock() and ocfs2_dlm_unlock() functions take no argument
 237  * for the ast and bast functions.  They will pass the lksb to the ast
 238  * and bast.  The caller can wrap the lksb with their own structure to
 239  * get more information.
 240  */
 241 int ocfs2_dlm_lock(struct ocfs2_cluster_connection *conn,
 242                    int mode,
 243                    struct ocfs2_dlm_lksb *lksb,
 244                    u32 flags,
 245                    void *name,
 246                    unsigned int namelen)
 247 {
 248         if (!lksb->lksb_conn)
 249                 lksb->lksb_conn = conn;
 250         else
 251                 BUG_ON(lksb->lksb_conn != conn);
 252         return active_stack->sp_ops->dlm_lock(conn, mode, lksb, flags,
 253                                               name, namelen);
 254 }
 255 EXPORT_SYMBOL_GPL(ocfs2_dlm_lock);
 256
 257 int ocfs2_dlm_unlock(struct ocfs2_cluster_connection *conn,
 258                      struct ocfs2_dlm_lksb *lksb,
 259                      u32 flags)
 260 {
 261         BUG_ON(lksb->lksb_conn == NULL);
 262
 263         return active_stack->sp_ops->dlm_unlock(conn, lksb, flags);
 264 }
 265 EXPORT_SYMBOL_GPL(ocfs2_dlm_unlock);
 266
 267 int ocfs2_dlm_lock_status(struct ocfs2_dlm_lksb *lksb)
 268 {
 269         return active_stack->sp_ops->lock_status(lksb);
 270 }
 271 EXPORT_SYMBOL_GPL(ocfs2_dlm_lock_status);
 272
 273 int ocfs2_dlm_lvb_valid(struct ocfs2_dlm_lksb *lksb)
 274 {
 275         return active_stack->sp_ops->lvb_valid(lksb);
 276 }
 277 EXPORT_SYMBOL_GPL(ocfs2_dlm_lvb_valid);
 278
 279 void *ocfs2_dlm_lvb(struct ocfs2_dlm_lksb *lksb)
 280 {
 281         return active_stack->sp_ops->lock_lvb(lksb);
 282 }
 283 EXPORT_SYMBOL_GPL(ocfs2_dlm_lvb);
 284
 285 void ocfs2_dlm_dump_lksb(struct ocfs2_dlm_lksb *lksb)
 286 {
 287         active_stack->sp_ops->dump_lksb(lksb);
 288 }
 289 EXPORT_SYMBOL_GPL(ocfs2_dlm_dump_lksb);
 290
 291 int ocfs2_stack_supports_plocks(void)
 292 {
 293         return active_stack && active_stack->sp_ops->plock;
 294 }
 295 EXPORT_SYMBOL_GPL(ocfs2_stack_supports_plocks);
 296
 297 /*
 298  * ocfs2_plock() can only be safely called if
 299  * ocfs2_stack_supports_plocks() returned true
 300  */
 301 int ocfs2_plock(struct ocfs2_cluster_connection *conn, u64 ino,
 302                 struct file *file, int cmd, struct file_lock *fl)
 303 {
 304         WARN_ON_ONCE(active_stack->sp_ops->plock == NULL);
 305         if (active_stack->sp_ops->plock)
 306                 return active_stack->sp_ops->plock(conn, ino, file, cmd, fl);
 307         return -EOPNOTSUPP;
 308 }
 309 EXPORT_SYMBOL_GPL(ocfs2_plock);
 310
 311 int ocfs2_cluster_connect(const char *stack_name,
 312                           const char *cluster_name,
 313                           int cluster_name_len,
 314                           const char *group,
 315                           int grouplen,
 316                           struct ocfs2_locking_protocol *lproto,
 317                           void (*recovery_handler)(int node_num,
 318                                                    void *recovery_data),
 319                           void *recovery_data,
 320                           struct ocfs2_cluster_connection **conn)
 321 {
 322         int rc = 0;
 323         struct ocfs2_cluster_connection *new_conn;
 324
 325         BUG_ON(group == NULL);
 326         BUG_ON(conn == NULL);
 327         BUG_ON(recovery_handler == NULL);
 328
 329         if (grouplen > GROUP_NAME_MAX) {
 330                 rc = -EINVAL;
 331                 goto out;
 332         }
 333
 334         if (memcmp(&lproto->lp_max_version, &locking_max_version,
 335                    sizeof(struct ocfs2_protocol_version))) {
 336                 rc = -EINVAL;
 337                 goto out;
 338         }
 339
 340         new_conn = kzalloc(sizeof(struct ocfs2_cluster_connection),
 341                            GFP_KERNEL);
 342         if (!new_conn) {
 343                 rc = -ENOMEM;
 344                 goto out;
 345         }
 346
 347         strlcpy(new_conn->cc_name, group, GROUP_NAME_MAX + 1);
 348         new_conn->cc_namelen = grouplen;
 349         if (cluster_name_len)
 350                 strlcpy(new_conn->cc_cluster_name, cluster_name,
 351                         CLUSTER_NAME_MAX + 1);
 352         new_conn->cc_cluster_name_len = cluster_name_len;
 353         new_conn->cc_recovery_handler = recovery_handler;
 354         new_conn->cc_recovery_data = recovery_data;
 355
 356         new_conn->cc_proto = lproto;
 357         /* Start the new connection at our maximum compatibility level */
 358         new_conn->cc_version = lproto->lp_max_version;
 359
 360         /* This will pin the stack driver if successful */
 361         rc = ocfs2_stack_driver_get(stack_name);
 362         if (rc)
 363                 goto out_free;
 364
 365         rc = active_stack->sp_ops->connect(new_conn);
 366         if (rc) {
 367                 ocfs2_stack_driver_put();
 368                 goto out_free;
 369         }
 370
 371         *conn = new_conn;
 372
 373 out_free:
 374         if (rc)
 375                 kfree(new_conn);
 376
 377 out:
 378         return rc;
 379 }
 380 EXPORT_SYMBOL_GPL(ocfs2_cluster_connect);
 381
 382 /* The caller will ensure all nodes have the same cluster stack */
 383 int ocfs2_cluster_connect_agnostic(const char *group,
 384                                    int grouplen,
 385                                    struct ocfs2_locking_protocol *lproto,
 386                                    void (*recovery_handler)(int node_num,
 387                                                             void *recovery_data),
 388                                    void *recovery_data,
 389                                    struct ocfs2_cluster_connection **conn)
 390 {
 391         char *stack_name = NULL;
 392
 393         if (cluster_stack_name[0])
 394                 stack_name = cluster_stack_name;
 395         return ocfs2_cluster_connect(stack_name, NULL, 0, group, grouplen,
 396                                      lproto, recovery_handler, recovery_data,
 397                                      conn);
 398 }
 399 EXPORT_SYMBOL_GPL(ocfs2_cluster_connect_agnostic);
 400
 401 /* If hangup_pending is 0, the stack driver will be dropped */
 402 int ocfs2_cluster_disconnect(struct ocfs2_cluster_connection *conn,
 403                              int hangup_pending)
 404 {
 405         int ret;
 406
 407         BUG_ON(conn == NULL);
 408
 409         ret = active_stack->sp_ops->disconnect(conn);
 410
 411         /* XXX Should we free it anyway? */
 412         if (!ret) {
 413                 kfree(conn);
 414                 if (!hangup_pending)
 415                         ocfs2_stack_driver_put();
 416         }
 417
 418         return ret;
 419 }
 420 EXPORT_SYMBOL_GPL(ocfs2_cluster_disconnect);
 421
 422 /*
 423  * Leave the group for this filesystem.  This is executed by a userspace
 424  * program (stored in ocfs2_hb_ctl_path).
 425  */
 426 static void ocfs2_leave_group(const char *group)
 427 {
 428         int ret;
 429         char *argv[5], *envp[3];
 430
 431         argv[0] = ocfs2_hb_ctl_path;
 432         argv[1] = "-K";
 433         argv[2] = "-u";
 434         argv[3] = (char *)group;
 435         argv[4] = NULL;
 436
 437         /* minimal command environment taken from cpu_run_sbin_hotplug */
 438         envp[0] = "HOME=/";
 439         envp[1] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
 440         envp[2] = NULL;
 441
 442         ret = call_usermodehelper(argv[0], argv, envp, UMH_WAIT_PROC);
 443         if (ret < 0) {
 444                 printk(KERN_ERR
 445                        "ocfs2: Error %d running user helper "
 446                        "\"%s %s %s %s\"\n",
 447                        ret, argv[0], argv[1], argv[2], argv[3]);
 448         }
 449 }
 450
 451 /*
 452  * Hangup is a required post-umount.  ocfs2-tools software expects the
 453  * filesystem to call "ocfs2_hb_ctl" during unmount.  This happens
 454  * regardless of whether the DLM got started, so we can't do it
 455  * in ocfs2_cluster_disconnect().  The ocfs2_leave_group() function does
 456  * the actual work.
 457  */
 458 void ocfs2_cluster_hangup(const char *group, int grouplen)
 459 {
 460         BUG_ON(group == NULL);
 461         BUG_ON(group[grouplen] != '\0');
 462
 463         ocfs2_leave_group(group);
 464
 465         /* cluster_disconnect() was called with hangup_pending==1 */
 466         ocfs2_stack_driver_put();
 467 }
 468 EXPORT_SYMBOL_GPL(ocfs2_cluster_hangup);
 469
 470 int ocfs2_cluster_this_node(struct ocfs2_cluster_connection *conn,
 471                             unsigned int *node)
 472 {
 473         return active_stack->sp_ops->this_node(conn, node);
 474 }
 475 EXPORT_SYMBOL_GPL(ocfs2_cluster_this_node);
 476
 477
 478 /*
 479  * Sysfs bits
 480  */
 481
 482 static ssize_t ocfs2_max_locking_protocol_show(struct kobject *kobj,
 483                                                struct kobj_attribute *attr,
 484                                                char *buf)
 485 {
 486         ssize_t ret = 0;
 487
 488         spin_lock(&ocfs2_stack_lock);
 489         if (locking_max_version.pv_major)
 490                 ret = snprintf(buf, PAGE_SIZE, "%u.%u\n",
 491                                locking_max_version.pv_major,
 492                                locking_max_version.pv_minor);
 493         spin_unlock(&ocfs2_stack_lock);
 494
 495         return ret;
 496 }
 497
 498 static struct kobj_attribute ocfs2_attr_max_locking_protocol =
 499         __ATTR(max_locking_protocol, S_IFREG | S_IRUGO,
 500                ocfs2_max_locking_protocol_show, NULL);
 501
 502 static ssize_t ocfs2_loaded_cluster_plugins_show(struct kobject *kobj,
 503                                                  struct kobj_attribute *attr,
 504                                                  char *buf)
 505 {
 506         ssize_t ret = 0, total = 0, remain = PAGE_SIZE;
 507         struct ocfs2_stack_plugin *p;
 508
 509         spin_lock(&ocfs2_stack_lock);
 510         list_for_each_entry(p, &ocfs2_stack_list, sp_list) {
 511                 ret = snprintf(buf, remain, "%s\n",
 512                                p->sp_name);
 513                 if (ret < 0) {
 514                         total = ret;
 515                         break;
 516                 }
 517                 if (ret == remain) {
 518                         /* snprintf() didn't fit */
 519                         total = -E2BIG;
 520                         break;
 521                 }
 522                 total += ret;
 523                 remain -= ret;
 524         }
 525         spin_unlock(&ocfs2_stack_lock);
 526
 527         return total;
 528 }
 529
 530 static struct kobj_attribute ocfs2_attr_loaded_cluster_plugins =
 531         __ATTR(loaded_cluster_plugins, S_IFREG | S_IRUGO,
 532                ocfs2_loaded_cluster_plugins_show, NULL);
 533
 534 static ssize_t ocfs2_active_cluster_plugin_show(struct kobject *kobj,
 535                                                 struct kobj_attribute *attr,
 536                                                 char *buf)
 537 {
 538         ssize_t ret = 0;
 539
 540         spin_lock(&ocfs2_stack_lock);
 541         if (active_stack) {
 542                 ret = snprintf(buf, PAGE_SIZE, "%s\n",
 543                                active_stack->sp_name);
 544                 if (ret == PAGE_SIZE)
 545                         ret = -E2BIG;
 546         }
 547         spin_unlock(&ocfs2_stack_lock);
 548
 549         return ret;
 550 }
 551
 552 static struct kobj_attribute ocfs2_attr_active_cluster_plugin =
 553         __ATTR(active_cluster_plugin, S_IFREG | S_IRUGO,
 554                ocfs2_active_cluster_plugin_show, NULL);
 555
 556 static ssize_t ocfs2_cluster_stack_show(struct kobject *kobj,
 557                                         struct kobj_attribute *attr,
 558                                         char *buf)
 559 {
 560         ssize_t ret;
 561         spin_lock(&ocfs2_stack_lock);
 562         ret = snprintf(buf, PAGE_SIZE, "%s\n", cluster_stack_name);
 563         spin_unlock(&ocfs2_stack_lock);
 564
 565         return ret;
 566 }
 567
 568 static ssize_t ocfs2_cluster_stack_store(struct kobject *kobj,
 569                                          struct kobj_attribute *attr,
 570                                          const char *buf, size_t count)
 571 {
 572         size_t len = count;
 573         ssize_t ret;
 574
 575         if (len == 0)
 576                 return len;
 577
 578         if (buf[len - 1] == '\n')
 579                 len--;
 580
 581         if ((len != OCFS2_STACK_LABEL_LEN) ||
 582             (strnlen(buf, len) != len))
 583                 return -EINVAL;
 584
 585         spin_lock(&ocfs2_stack_lock);
 586         if (active_stack) {
 587                 if (!strncmp(buf, cluster_stack_name, len))
 588                         ret = count;
 589                 else
 590                         ret = -EBUSY;
 591         } else {
 592                 memcpy(cluster_stack_name, buf, len);
 593                 ret = count;
 594         }
 595         spin_unlock(&ocfs2_stack_lock);
 596
 597         return ret;
 598 }
 599
 600
 601 static struct kobj_attribute ocfs2_attr_cluster_stack =
 602         __ATTR(cluster_stack, S_IFREG | S_IRUGO | S_IWUSR,
 603                ocfs2_cluster_stack_show,
 604                ocfs2_cluster_stack_store);
 605
 606 static struct attribute *ocfs2_attrs[] = {
 607         &ocfs2_attr_max_locking_protocol.attr,
 608         &ocfs2_attr_loaded_cluster_plugins.attr,
 609         &ocfs2_attr_active_cluster_plugin.attr,
 610         &ocfs2_attr_cluster_stack.attr,
 611         NULL,
 612 };
 613
 614 static struct attribute_group ocfs2_attr_group = {
 615         .attrs = ocfs2_attrs,
 616 };
 617
 618 static struct kset *ocfs2_kset;
 619
 620 static void ocfs2_sysfs_exit(void)
 621 {
 622         kset_unregister(ocfs2_kset);
 623 }
 624
 625 static int ocfs2_sysfs_init(void)
 626 {
 627         int ret;
 628
 629         ocfs2_kset = kset_create_and_add("ocfs2", NULL, fs_kobj);
 630         if (!ocfs2_kset)
 631                 return -ENOMEM;
 632
 633         ret = sysfs_create_group(&ocfs2_kset->kobj, &ocfs2_attr_group);
 634         if (ret)
 635                 goto error;
 636
 637         return 0;
 638
 639 error:
 640         kset_unregister(ocfs2_kset);
 641         return ret;
 642 }
 643
 644 /*
 645  * Sysctl bits
 646  *
 647  * The sysctl lives at /proc/sys/fs/ocfs2/nm/hb_ctl_path.  The 'nm' doesn't
 648  * make as much sense in a multiple cluster stack world, but it's safer
 649  * and easier to preserve the name.
 650  */
 651
 652 #define FS_OCFS2_NM             1
 653
 654 static struct ctl_table ocfs2_nm_table[] = {
 655         {
 656                 .procname       = "hb_ctl_path",
 657                 .data           = ocfs2_hb_ctl_path,
 658                 .maxlen         = OCFS2_MAX_HB_CTL_PATH,
 659                 .mode           = 0644,
 660                 .proc_handler   = proc_dostring,
 661         },
 662         { }
 663 };
 664
 665 static struct ctl_table ocfs2_mod_table[] = {
 666         {
 667                 .procname       = "nm",
 668                 .data           = NULL,
 669                 .maxlen         = 0,
 670                 .mode           = 0555,
 671                 .child          = ocfs2_nm_table
 672         },
 673         { }
 674 };
 675
 676 static struct ctl_table ocfs2_kern_table[] = {
 677         {
 678                 .procname       = "ocfs2",
 679                 .data           = NULL,
 680                 .maxlen         = 0,
 681                 .mode           = 0555,
 682                 .child          = ocfs2_mod_table
 683         },
 684         { }
 685 };
 686
 687 static struct ctl_table ocfs2_root_table[] = {
 688         {
 689                 .procname       = "fs",
 690                 .data           = NULL,
 691                 .maxlen         = 0,
 692                 .mode           = 0555,
 693                 .child          = ocfs2_kern_table
 694         },
 695         { }
 696 };
 697
 698 static struct ctl_table_header *ocfs2_table_header = NULL;
 699
 700
 701 /*
 702  * Initialization
 703  */
 704
 705 static int __init ocfs2_stack_glue_init(void)
 706 {
 707         strcpy(cluster_stack_name, OCFS2_STACK_PLUGIN_O2CB);
 708
 709         ocfs2_table_header = register_sysctl_table(ocfs2_root_table);
 710         if (!ocfs2_table_header) {
 711                 printk(KERN_ERR
 712                        "ocfs2 stack glue: unable to register sysctl\n");
 713                 return -ENOMEM; /* or something. */
 714         }
 715
 716         return ocfs2_sysfs_init();
 717 }
 718
 719 static void __exit ocfs2_stack_glue_exit(void)
 720 {
 721         memset(&locking_max_version, 0,
 722                sizeof(struct ocfs2_protocol_version));
 723         locking_max_version.pv_major = 0;
 724         locking_max_version.pv_minor = 0;
 725         ocfs2_sysfs_exit();
 726         if (ocfs2_table_header)
 727                 unregister_sysctl_table(ocfs2_table_header);
 728 }
 729
 730 MODULE_AUTHOR("Oracle");
 731 MODULE_DESCRIPTION("ocfs2 cluter stack glue layer");
 732 MODULE_LICENSE("GPL");
 733 module_init(ocfs2_stack_glue_init);
 734 module_exit(ocfs2_stack_glue_exit);