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 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
  30 #include "stackglue.h"
  31
  32 static struct ocfs2_locking_protocol *lproto;
  33 static DEFINE_SPINLOCK(ocfs2_stack_lock);
  34 static LIST_HEAD(ocfs2_stack_list);
  35
  36 /*
  37  * The stack currently in use.  If not null, active_stack->sp_count > 0,
  38  * the module is pinned, and the locking protocol cannot be changed.
  39  */
  40 static struct ocfs2_stack_plugin *active_stack;
  41
  42 static struct ocfs2_stack_plugin *ocfs2_stack_lookup(const char *name)
  43 {
  44         struct ocfs2_stack_plugin *p;
  45
  46         assert_spin_locked(&ocfs2_stack_lock);
  47
  48         list_for_each_entry(p, &ocfs2_stack_list, sp_list) {
  49                 if (!strcmp(p->sp_name, name))
  50                         return p;
  51         }
  52
  53         return NULL;
  54 }
  55
  56 static int ocfs2_stack_driver_request(const char *name)
  57 {
  58         int rc;
  59         struct ocfs2_stack_plugin *p;
  60
  61         spin_lock(&ocfs2_stack_lock);
  62
  63         if (active_stack) {
  64                 /*
  65                  * If the active stack isn't the one we want, it cannot
  66                  * be selected right now.
  67                  */
  68                 if (!strcmp(active_stack->sp_name, name))
  69                         rc = 0;
  70                 else
  71                         rc = -EBUSY;
  72                 goto out;
  73         }
  74
  75         p = ocfs2_stack_lookup(name);
  76         if (!p || !try_module_get(p->sp_owner)) {
  77                 rc = -ENOENT;
  78                 goto out;
  79         }
  80
  81         /* Ok, the stack is pinned */
  82         p->sp_count++;
  83         active_stack = p;
  84
  85         rc = 0;
  86
  87 out:
  88         spin_unlock(&ocfs2_stack_lock);
  89         return rc;
  90 }
  91
  92 /*
  93  * This function looks up the appropriate stack and makes it active.  If
  94  * there is no stack, it tries to load it.  It will fail if the stack still
  95  * cannot be found.  It will also fail if a different stack is in use.
  96  */
  97 static int ocfs2_stack_driver_get(const char *name)
  98 {
  99         int rc;
 100
 101         rc = ocfs2_stack_driver_request(name);
 102         if (rc == -ENOENT) {
 103                 request_module("ocfs2_stack_%s", name);
 104                 rc = ocfs2_stack_driver_request(name);
 105         }
 106
 107         if (rc == -ENOENT) {
 108                 printk(KERN_ERR
 109                        "ocfs2: Cluster stack driver \"%s\" cannot be found\n",
 110                        name);
 111         } else if (rc == -EBUSY) {
 112                 printk(KERN_ERR
 113                        "ocfs2: A different cluster stack driver is in use\n");
 114         }
 115
 116         return rc;
 117 }
 118
 119 static void ocfs2_stack_driver_put(void)
 120 {
 121         spin_lock(&ocfs2_stack_lock);
 122         BUG_ON(active_stack == NULL);
 123         BUG_ON(active_stack->sp_count == 0);
 124
 125         active_stack->sp_count--;
 126         if (!active_stack->sp_count) {
 127                 module_put(active_stack->sp_owner);
 128                 active_stack = NULL;
 129         }
 130         spin_unlock(&ocfs2_stack_lock);
 131 }
 132
 133 int ocfs2_stack_glue_register(struct ocfs2_stack_plugin *plugin)
 134 {
 135         int rc;
 136
 137         spin_lock(&ocfs2_stack_lock);
 138         if (!ocfs2_stack_lookup(plugin->sp_name)) {
 139                 plugin->sp_count = 0;
 140                 plugin->sp_proto = lproto;
 141                 list_add(&plugin->sp_list, &ocfs2_stack_list);
 142                 printk(KERN_INFO "ocfs2: Registered cluster interface %s\n",
 143                        plugin->sp_name);
 144                 rc = 0;
 145         } else {
 146                 printk(KERN_ERR "ocfs2: Stack \"%s\" already registered\n",
 147                        plugin->sp_name);
 148                 rc = -EEXIST;
 149         }
 150         spin_unlock(&ocfs2_stack_lock);
 151
 152         return rc;
 153 }
 154 EXPORT_SYMBOL_GPL(ocfs2_stack_glue_register);
 155
 156 void ocfs2_stack_glue_unregister(struct ocfs2_stack_plugin *plugin)
 157 {
 158         struct ocfs2_stack_plugin *p;
 159
 160         spin_lock(&ocfs2_stack_lock);
 161         p = ocfs2_stack_lookup(plugin->sp_name);
 162         if (p) {
 163                 BUG_ON(p != plugin);
 164                 BUG_ON(plugin == active_stack);
 165                 BUG_ON(plugin->sp_count != 0);
 166                 list_del_init(&plugin->sp_list);
 167                 printk(KERN_INFO "ocfs2: Unregistered cluster interface %s\n",
 168                        plugin->sp_name);
 169         } else {
 170                 printk(KERN_ERR "Stack \"%s\" is not registered\n",
 171                        plugin->sp_name);
 172         }
 173         spin_unlock(&ocfs2_stack_lock);
 174 }
 175 EXPORT_SYMBOL_GPL(ocfs2_stack_glue_unregister);
 176
 177 void ocfs2_stack_glue_set_locking_protocol(struct ocfs2_locking_protocol *proto)
 178 {
 179         struct ocfs2_stack_plugin *p;
 180
 181         BUG_ON(proto == NULL);
 182
 183         spin_lock(&ocfs2_stack_lock);
 184         BUG_ON(active_stack != NULL);
 185
 186         lproto = proto;
 187         list_for_each_entry(p, &ocfs2_stack_list, sp_list) {
 188                 p->sp_proto = lproto;
 189         }
 190
 191         spin_unlock(&ocfs2_stack_lock);
 192 }
 193 EXPORT_SYMBOL_GPL(ocfs2_stack_glue_set_locking_protocol);
 194
 195
 196 int ocfs2_dlm_lock(struct ocfs2_cluster_connection *conn,
 197                    int mode,
 198                    union ocfs2_dlm_lksb *lksb,
 199                    u32 flags,
 200                    void *name,
 201                    unsigned int namelen,
 202                    void *astarg)
 203 {
 204         BUG_ON(lproto == NULL);
 205
 206         return active_stack->sp_ops->dlm_lock(conn, mode, lksb, flags,
 207                                               name, namelen, astarg);
 208 }
 209 EXPORT_SYMBOL_GPL(ocfs2_dlm_lock);
 210
 211 int ocfs2_dlm_unlock(struct ocfs2_cluster_connection *conn,
 212                      union ocfs2_dlm_lksb *lksb,
 213                      u32 flags,
 214                      void *astarg)
 215 {
 216         BUG_ON(lproto == NULL);
 217
 218         return active_stack->sp_ops->dlm_unlock(conn, lksb, flags, astarg);
 219 }
 220 EXPORT_SYMBOL_GPL(ocfs2_dlm_unlock);
 221
 222 int ocfs2_dlm_lock_status(union ocfs2_dlm_lksb *lksb)
 223 {
 224         return active_stack->sp_ops->lock_status(lksb);
 225 }
 226 EXPORT_SYMBOL_GPL(ocfs2_dlm_lock_status);
 227
 228 /*
 229  * Why don't we cast to ocfs2_meta_lvb?  The "clean" answer is that we
 230  * don't cast at the glue level.  The real answer is that the header
 231  * ordering is nigh impossible.
 232  */
 233 void *ocfs2_dlm_lvb(union ocfs2_dlm_lksb *lksb)
 234 {
 235         return active_stack->sp_ops->lock_lvb(lksb);
 236 }
 237 EXPORT_SYMBOL_GPL(ocfs2_dlm_lvb);
 238
 239 void ocfs2_dlm_dump_lksb(union ocfs2_dlm_lksb *lksb)
 240 {
 241         active_stack->sp_ops->dump_lksb(lksb);
 242 }
 243 EXPORT_SYMBOL_GPL(ocfs2_dlm_dump_lksb);
 244
 245 int ocfs2_cluster_connect(const char *group,
 246                           int grouplen,
 247                           void (*recovery_handler)(int node_num,
 248                                                    void *recovery_data),
 249                           void *recovery_data,
 250                           struct ocfs2_cluster_connection **conn)
 251 {
 252         int rc = 0;
 253         struct ocfs2_cluster_connection *new_conn;
 254
 255         BUG_ON(group == NULL);
 256         BUG_ON(conn == NULL);
 257         BUG_ON(recovery_handler == NULL);
 258
 259         if (grouplen > GROUP_NAME_MAX) {
 260                 rc = -EINVAL;
 261                 goto out;
 262         }
 263
 264         new_conn = kzalloc(sizeof(struct ocfs2_cluster_connection),
 265                            GFP_KERNEL);
 266         if (!new_conn) {
 267                 rc = -ENOMEM;
 268                 goto out;
 269         }
 270
 271         memcpy(new_conn->cc_name, group, grouplen);
 272         new_conn->cc_namelen = grouplen;
 273         new_conn->cc_recovery_handler = recovery_handler;
 274         new_conn->cc_recovery_data = recovery_data;
 275
 276         /* Start the new connection at our maximum compatibility level */
 277         new_conn->cc_version = lproto->lp_max_version;
 278
 279         /* This will pin the stack driver if successful */
 280         rc = ocfs2_stack_driver_get("o2cb");
 281         if (rc)
 282                 goto out_free;
 283
 284         rc = active_stack->sp_ops->connect(new_conn);
 285         if (rc) {
 286                 ocfs2_stack_driver_put();
 287                 goto out_free;
 288         }
 289
 290         *conn = new_conn;
 291
 292 out_free:
 293         if (rc)
 294                 kfree(new_conn);
 295
 296 out:
 297         return rc;
 298 }
 299 EXPORT_SYMBOL_GPL(ocfs2_cluster_connect);
 300
 301 /* If hangup_pending is 0, the stack driver will be dropped */
 302 int ocfs2_cluster_disconnect(struct ocfs2_cluster_connection *conn,
 303                              int hangup_pending)
 304 {
 305         int ret;
 306
 307         BUG_ON(conn == NULL);
 308
 309         ret = active_stack->sp_ops->disconnect(conn, hangup_pending);
 310
 311         /* XXX Should we free it anyway? */
 312         if (!ret) {
 313                 kfree(conn);
 314                 if (!hangup_pending)
 315                         ocfs2_stack_driver_put();
 316         }
 317
 318         return ret;
 319 }
 320 EXPORT_SYMBOL_GPL(ocfs2_cluster_disconnect);
 321
 322 void ocfs2_cluster_hangup(const char *group, int grouplen)
 323 {
 324         BUG_ON(group == NULL);
 325         BUG_ON(group[grouplen] != '\0');
 326
 327         active_stack->sp_ops->hangup(group, grouplen);
 328
 329         /* cluster_disconnect() was called with hangup_pending==1 */
 330         ocfs2_stack_driver_put();
 331 }
 332 EXPORT_SYMBOL_GPL(ocfs2_cluster_hangup);
 333
 334 int ocfs2_cluster_this_node(unsigned int *node)
 335 {
 336         return active_stack->sp_ops->this_node(node);
 337 }
 338 EXPORT_SYMBOL_GPL(ocfs2_cluster_this_node);
 339
 340
 341 /*
 342  * Sysfs bits
 343  */
 344
 345 static ssize_t ocfs2_max_locking_protocol_show(struct kobject *kobj,
 346                                                struct kobj_attribute *attr,
 347                                                char *buf)
 348 {
 349         ssize_t ret = 0;
 350
 351         spin_lock(&ocfs2_stack_lock);
 352         if (lproto)
 353                 ret = snprintf(buf, PAGE_SIZE, "%u.%u\n",
 354                                lproto->lp_max_version.pv_major,
 355                                lproto->lp_max_version.pv_minor);
 356         spin_unlock(&ocfs2_stack_lock);
 357
 358         return ret;
 359 }
 360
 361 static struct kobj_attribute ocfs2_attr_max_locking_protocol =
 362         __ATTR(max_locking_protocol, S_IFREG | S_IRUGO,
 363                ocfs2_max_locking_protocol_show, NULL);
 364
 365 static ssize_t ocfs2_loaded_cluster_plugins_show(struct kobject *kobj,
 366                                                  struct kobj_attribute *attr,
 367                                                  char *buf)
 368 {
 369         ssize_t ret = 0, total = 0, remain = PAGE_SIZE;
 370         struct ocfs2_stack_plugin *p;
 371
 372         spin_lock(&ocfs2_stack_lock);
 373         list_for_each_entry(p, &ocfs2_stack_list, sp_list) {
 374                 ret = snprintf(buf, remain, "%s\n",
 375                                p->sp_name);
 376                 if (ret < 0) {
 377                         total = ret;
 378                         break;
 379                 }
 380                 if (ret == remain) {
 381                         /* snprintf() didn't fit */
 382                         total = -E2BIG;
 383                         break;
 384                 }
 385                 total += ret;
 386                 remain -= ret;
 387         }
 388         spin_unlock(&ocfs2_stack_lock);
 389
 390         return total;
 391 }
 392
 393 static struct kobj_attribute ocfs2_attr_loaded_cluster_plugins =
 394         __ATTR(loaded_cluster_plugins, S_IFREG | S_IRUGO,
 395                ocfs2_loaded_cluster_plugins_show, NULL);
 396
 397 static ssize_t ocfs2_active_cluster_plugin_show(struct kobject *kobj,
 398                                                 struct kobj_attribute *attr,
 399                                                 char *buf)
 400 {
 401         ssize_t ret = 0;
 402
 403         spin_lock(&ocfs2_stack_lock);
 404         if (active_stack) {
 405                 ret = snprintf(buf, PAGE_SIZE, "%s\n",
 406                                active_stack->sp_name);
 407                 if (ret == PAGE_SIZE)
 408                         ret = -E2BIG;
 409         }
 410         spin_unlock(&ocfs2_stack_lock);
 411
 412         return ret;
 413 }
 414
 415 static struct kobj_attribute ocfs2_attr_active_cluster_plugin =
 416         __ATTR(active_cluster_plugin, S_IFREG | S_IRUGO,
 417                ocfs2_active_cluster_plugin_show, NULL);
 418
 419 static struct attribute *ocfs2_attrs[] = {
 420         &ocfs2_attr_max_locking_protocol.attr,
 421         &ocfs2_attr_loaded_cluster_plugins.attr,
 422         &ocfs2_attr_active_cluster_plugin.attr,
 423         NULL,
 424 };
 425
 426 static struct attribute_group ocfs2_attr_group = {
 427         .attrs = ocfs2_attrs,
 428 };
 429
 430 static struct kset *ocfs2_kset;
 431
 432 static void ocfs2_sysfs_exit(void)
 433 {
 434         kset_unregister(ocfs2_kset);
 435 }
 436
 437 static int ocfs2_sysfs_init(void)
 438 {
 439         int ret;
 440
 441         ocfs2_kset = kset_create_and_add("ocfs2", NULL, fs_kobj);
 442         if (!ocfs2_kset)
 443                 return -ENOMEM;
 444
 445         ret = sysfs_create_group(&ocfs2_kset->kobj, &ocfs2_attr_group);
 446         if (ret)
 447                 goto error;
 448
 449         return 0;
 450
 451 error:
 452         kset_unregister(ocfs2_kset);
 453         return ret;
 454 }
 455
 456 static int __init ocfs2_stack_glue_init(void)
 457 {
 458         return ocfs2_sysfs_init();
 459 }
 460
 461 static void __exit ocfs2_stack_glue_exit(void)
 462 {
 463         lproto = NULL;
 464         ocfs2_sysfs_exit();
 465 }
 466
 467 MODULE_AUTHOR("Oracle");
 468 MODULE_DESCRIPTION("ocfs2 cluter stack glue layer");
 469 MODULE_LICENSE("GPL");
 470 module_init(ocfs2_stack_glue_init);
 471 module_exit(ocfs2_stack_glue_exit);