Pileus Git - ~andy/linux/blob - drivers/staging/zcache/ramster/heartbeat.c

   1 /* -*- mode: c; c-basic-offset: 8; -*-
   2  * vim: noexpandtab sw=8 ts=8 sts=0:
   3  *
   4  * Copyright (C) 2004, 2005, 2012 Oracle.  All rights reserved.
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2 of the License, or (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public
  17  * License along with this program; if not, write to the
  18  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  19  * Boston, MA 021110-1307, USA.
  20  */
  21
  22 #include <linux/kernel.h>
  23 #include <linux/module.h>
  24 #include <linux/configfs.h>
  25
  26 #include "heartbeat.h"
  27 #include "tcp.h"
  28 #include "nodemanager.h"
  29
  30 #include "masklog.h"
  31
  32 /*
  33  * The first heartbeat pass had one global thread that would serialize all hb
  34  * callback calls.  This global serializing sem should only be removed once
  35  * we've made sure that all callees can deal with being called concurrently
  36  * from multiple hb region threads.
  37  */
  38 static DECLARE_RWSEM(r2hb_callback_sem);
  39
  40 /*
  41  * multiple hb threads are watching multiple regions.  A node is live
  42  * whenever any of the threads sees activity from the node in its region.
  43  */
  44 static DEFINE_SPINLOCK(r2hb_live_lock);
  45 static unsigned long r2hb_live_node_bitmap[BITS_TO_LONGS(R2NM_MAX_NODES)];
  46
  47 static struct r2hb_callback {
  48         struct list_head list;
  49 } r2hb_callbacks[R2HB_NUM_CB];
  50
  51 enum r2hb_heartbeat_modes {
  52         R2HB_HEARTBEAT_LOCAL            = 0,
  53         R2HB_HEARTBEAT_GLOBAL,
  54         R2HB_HEARTBEAT_NUM_MODES,
  55 };
  56
  57 char *r2hb_heartbeat_mode_desc[R2HB_HEARTBEAT_NUM_MODES] = {
  58                 "local",        /* R2HB_HEARTBEAT_LOCAL */
  59                 "global",       /* R2HB_HEARTBEAT_GLOBAL */
  60 };
  61
  62 unsigned int r2hb_dead_threshold = R2HB_DEFAULT_DEAD_THRESHOLD;
  63 unsigned int r2hb_heartbeat_mode = R2HB_HEARTBEAT_LOCAL;
  64
  65 /* Only sets a new threshold if there are no active regions.
  66  *
  67  * No locking or otherwise interesting code is required for reading
  68  * r2hb_dead_threshold as it can't change once regions are active and
  69  * it's not interesting to anyone until then anyway. */
  70 static void r2hb_dead_threshold_set(unsigned int threshold)
  71 {
  72         if (threshold > R2HB_MIN_DEAD_THRESHOLD) {
  73                 spin_lock(&r2hb_live_lock);
  74                 r2hb_dead_threshold = threshold;
  75                 spin_unlock(&r2hb_live_lock);
  76         }
  77 }
  78
  79 static int r2hb_global_hearbeat_mode_set(unsigned int hb_mode)
  80 {
  81         int ret = -1;
  82
  83         if (hb_mode < R2HB_HEARTBEAT_NUM_MODES) {
  84                 spin_lock(&r2hb_live_lock);
  85                 r2hb_heartbeat_mode = hb_mode;
  86                 ret = 0;
  87                 spin_unlock(&r2hb_live_lock);
  88         }
  89
  90         return ret;
  91 }
  92
  93 void r2hb_exit(void)
  94 {
  95 }
  96
  97 int r2hb_init(void)
  98 {
  99         int i;
 100
 101         for (i = 0; i < ARRAY_SIZE(r2hb_callbacks); i++)
 102                 INIT_LIST_HEAD(&r2hb_callbacks[i].list);
 103
 104         memset(r2hb_live_node_bitmap, 0, sizeof(r2hb_live_node_bitmap));
 105
 106         return 0;
 107 }
 108
 109 /* if we're already in a callback then we're already serialized by the sem */
 110 static void r2hb_fill_node_map_from_callback(unsigned long *map,
 111                                              unsigned bytes)
 112 {
 113         BUG_ON(bytes < (BITS_TO_LONGS(R2NM_MAX_NODES) * sizeof(unsigned long)));
 114
 115         memcpy(map, &r2hb_live_node_bitmap, bytes);
 116 }
 117
 118 /*
 119  * get a map of all nodes that are heartbeating in any regions
 120  */
 121 void r2hb_fill_node_map(unsigned long *map, unsigned bytes)
 122 {
 123         /* callers want to serialize this map and callbacks so that they
 124          * can trust that they don't miss nodes coming to the party */
 125         down_read(&r2hb_callback_sem);
 126         spin_lock(&r2hb_live_lock);
 127         r2hb_fill_node_map_from_callback(map, bytes);
 128         spin_unlock(&r2hb_live_lock);
 129         up_read(&r2hb_callback_sem);
 130 }
 131 EXPORT_SYMBOL_GPL(r2hb_fill_node_map);
 132
 133 /*
 134  * heartbeat configfs bits.  The heartbeat set is a default set under
 135  * the cluster set in nodemanager.c.
 136  */
 137
 138 /* heartbeat set */
 139
 140 struct r2hb_hb_group {
 141         struct config_group hs_group;
 142         /* some stuff? */
 143 };
 144
 145 static struct r2hb_hb_group *to_r2hb_hb_group(struct config_group *group)
 146 {
 147         return group ?
 148                 container_of(group, struct r2hb_hb_group, hs_group)
 149                 : NULL;
 150 }
 151
 152 static struct config_item r2hb_config_item;
 153
 154 static struct config_item *r2hb_hb_group_make_item(struct config_group *group,
 155                                                           const char *name)
 156 {
 157         int ret;
 158
 159         if (strlen(name) > R2HB_MAX_REGION_NAME_LEN) {
 160                 ret = -ENAMETOOLONG;
 161                 goto free;
 162         }
 163
 164         config_item_put(&r2hb_config_item);
 165
 166         return &r2hb_config_item;
 167 free:
 168         return ERR_PTR(ret);
 169 }
 170
 171 static void r2hb_hb_group_drop_item(struct config_group *group,
 172                                            struct config_item *item)
 173 {
 174         if (r2hb_global_heartbeat_active()) {
 175                 pr_notice("ramster: Heartbeat %s on region %s (%s)\n",
 176                         "stopped/aborted", config_item_name(item),
 177                         "no region");
 178         }
 179
 180         config_item_put(item);
 181 }
 182
 183 struct r2hb_hb_group_attribute {
 184         struct configfs_attribute attr;
 185         ssize_t (*show)(struct r2hb_hb_group *, char *);
 186         ssize_t (*store)(struct r2hb_hb_group *, const char *, size_t);
 187 };
 188
 189 static ssize_t r2hb_hb_group_show(struct config_item *item,
 190                                          struct configfs_attribute *attr,
 191                                          char *page)
 192 {
 193         struct r2hb_hb_group *reg = to_r2hb_hb_group(to_config_group(item));
 194         struct r2hb_hb_group_attribute *r2hb_hb_group_attr =
 195                 container_of(attr, struct r2hb_hb_group_attribute, attr);
 196         ssize_t ret = 0;
 197
 198         if (r2hb_hb_group_attr->show)
 199                 ret = r2hb_hb_group_attr->show(reg, page);
 200         return ret;
 201 }
 202
 203 static ssize_t r2hb_hb_group_store(struct config_item *item,
 204                                           struct configfs_attribute *attr,
 205                                           const char *page, size_t count)
 206 {
 207         struct r2hb_hb_group *reg = to_r2hb_hb_group(to_config_group(item));
 208         struct r2hb_hb_group_attribute *r2hb_hb_group_attr =
 209                 container_of(attr, struct r2hb_hb_group_attribute, attr);
 210         ssize_t ret = -EINVAL;
 211
 212         if (r2hb_hb_group_attr->store)
 213                 ret = r2hb_hb_group_attr->store(reg, page, count);
 214         return ret;
 215 }
 216
 217 static ssize_t r2hb_hb_group_threshold_show(struct r2hb_hb_group *group,
 218                                                      char *page)
 219 {
 220         return sprintf(page, "%u\n", r2hb_dead_threshold);
 221 }
 222
 223 static ssize_t r2hb_hb_group_threshold_store(struct r2hb_hb_group *group,
 224                                                     const char *page,
 225                                                     size_t count)
 226 {
 227         unsigned long tmp;
 228         char *p = (char *)page;
 229         int err;
 230
 231         err = kstrtoul(p, 10, &tmp);
 232         if (err)
 233                 return err;
 234
 235         /* this will validate ranges for us. */
 236         r2hb_dead_threshold_set((unsigned int) tmp);
 237
 238         return count;
 239 }
 240
 241 static
 242 ssize_t r2hb_hb_group_mode_show(struct r2hb_hb_group *group,
 243                                        char *page)
 244 {
 245         return sprintf(page, "%s\n",
 246                        r2hb_heartbeat_mode_desc[r2hb_heartbeat_mode]);
 247 }
 248
 249 static
 250 ssize_t r2hb_hb_group_mode_store(struct r2hb_hb_group *group,
 251                                         const char *page, size_t count)
 252 {
 253         unsigned int i;
 254         int ret;
 255         size_t len;
 256
 257         len = (page[count - 1] == '\n') ? count - 1 : count;
 258         if (!len)
 259                 return -EINVAL;
 260
 261         for (i = 0; i < R2HB_HEARTBEAT_NUM_MODES; ++i) {
 262                 if (strnicmp(page, r2hb_heartbeat_mode_desc[i], len))
 263                         continue;
 264
 265                 ret = r2hb_global_hearbeat_mode_set(i);
 266                 if (!ret)
 267                         pr_notice("ramster: Heartbeat mode set to %s\n",
 268                                r2hb_heartbeat_mode_desc[i]);
 269                 return count;
 270         }
 271
 272         return -EINVAL;
 273
 274 }
 275
 276 static struct r2hb_hb_group_attribute r2hb_hb_group_attr_threshold = {
 277         .attr   = { .ca_owner = THIS_MODULE,
 278                     .ca_name = "dead_threshold",
 279                     .ca_mode = S_IRUGO | S_IWUSR },
 280         .show   = r2hb_hb_group_threshold_show,
 281         .store  = r2hb_hb_group_threshold_store,
 282 };
 283
 284 static struct r2hb_hb_group_attribute r2hb_hb_group_attr_mode = {
 285         .attr   = { .ca_owner = THIS_MODULE,
 286                 .ca_name = "mode",
 287                 .ca_mode = S_IRUGO | S_IWUSR },
 288         .show   = r2hb_hb_group_mode_show,
 289         .store  = r2hb_hb_group_mode_store,
 290 };
 291
 292 static struct configfs_attribute *r2hb_hb_group_attrs[] = {
 293         &r2hb_hb_group_attr_threshold.attr,
 294         &r2hb_hb_group_attr_mode.attr,
 295         NULL,
 296 };
 297
 298 static struct configfs_item_operations r2hb_hearbeat_group_item_ops = {
 299         .show_attribute         = r2hb_hb_group_show,
 300         .store_attribute        = r2hb_hb_group_store,
 301 };
 302
 303 static struct configfs_group_operations r2hb_hb_group_group_ops = {
 304         .make_item      = r2hb_hb_group_make_item,
 305         .drop_item      = r2hb_hb_group_drop_item,
 306 };
 307
 308 static struct config_item_type r2hb_hb_group_type = {
 309         .ct_group_ops   = &r2hb_hb_group_group_ops,
 310         .ct_item_ops    = &r2hb_hearbeat_group_item_ops,
 311         .ct_attrs       = r2hb_hb_group_attrs,
 312         .ct_owner       = THIS_MODULE,
 313 };
 314
 315 /* this is just here to avoid touching group in heartbeat.h which the
 316  * entire damn world #includes */
 317 struct config_group *r2hb_alloc_hb_set(void)
 318 {
 319         struct r2hb_hb_group *hs = NULL;
 320         struct config_group *ret = NULL;
 321
 322         hs = kzalloc(sizeof(struct r2hb_hb_group), GFP_KERNEL);
 323         if (hs == NULL)
 324                 goto out;
 325
 326         config_group_init_type_name(&hs->hs_group, "heartbeat",
 327                                     &r2hb_hb_group_type);
 328
 329         ret = &hs->hs_group;
 330 out:
 331         if (ret == NULL)
 332                 kfree(hs);
 333         return ret;
 334 }
 335
 336 void r2hb_free_hb_set(struct config_group *group)
 337 {
 338         struct r2hb_hb_group *hs = to_r2hb_hb_group(group);
 339         kfree(hs);
 340 }
 341
 342 /* hb callback registration and issuing */
 343
 344 static struct r2hb_callback *hbcall_from_type(enum r2hb_callback_type type)
 345 {
 346         if (type == R2HB_NUM_CB)
 347                 return ERR_PTR(-EINVAL);
 348
 349         return &r2hb_callbacks[type];
 350 }
 351
 352 void r2hb_setup_callback(struct r2hb_callback_func *hc,
 353                          enum r2hb_callback_type type,
 354                          r2hb_cb_func *func,
 355                          void *data,
 356                          int priority)
 357 {
 358         INIT_LIST_HEAD(&hc->hc_item);
 359         hc->hc_func = func;
 360         hc->hc_data = data;
 361         hc->hc_priority = priority;
 362         hc->hc_type = type;
 363         hc->hc_magic = R2HB_CB_MAGIC;
 364 }
 365 EXPORT_SYMBOL_GPL(r2hb_setup_callback);
 366
 367 int r2hb_register_callback(const char *region_uuid,
 368                            struct r2hb_callback_func *hc)
 369 {
 370         struct r2hb_callback_func *tmp;
 371         struct list_head *iter;
 372         struct r2hb_callback *hbcall;
 373         int ret;
 374
 375         BUG_ON(hc->hc_magic != R2HB_CB_MAGIC);
 376         BUG_ON(!list_empty(&hc->hc_item));
 377
 378         hbcall = hbcall_from_type(hc->hc_type);
 379         if (IS_ERR(hbcall)) {
 380                 ret = PTR_ERR(hbcall);
 381                 goto out;
 382         }
 383
 384         down_write(&r2hb_callback_sem);
 385
 386         list_for_each(iter, &hbcall->list) {
 387                 tmp = list_entry(iter, struct r2hb_callback_func, hc_item);
 388                 if (hc->hc_priority < tmp->hc_priority) {
 389                         list_add_tail(&hc->hc_item, iter);
 390                         break;
 391                 }
 392         }
 393         if (list_empty(&hc->hc_item))
 394                 list_add_tail(&hc->hc_item, &hbcall->list);
 395
 396         up_write(&r2hb_callback_sem);
 397         ret = 0;
 398 out:
 399         mlog(ML_CLUSTER, "returning %d on behalf of %p for funcs %p\n",
 400              ret, __builtin_return_address(0), hc);
 401         return ret;
 402 }
 403 EXPORT_SYMBOL_GPL(r2hb_register_callback);
 404
 405 void r2hb_unregister_callback(const char *region_uuid,
 406                               struct r2hb_callback_func *hc)
 407 {
 408         BUG_ON(hc->hc_magic != R2HB_CB_MAGIC);
 409
 410         mlog(ML_CLUSTER, "on behalf of %p for funcs %p\n",
 411              __builtin_return_address(0), hc);
 412
 413         /* XXX Can this happen _with_ a region reference? */
 414         if (list_empty(&hc->hc_item))
 415                 return;
 416
 417         down_write(&r2hb_callback_sem);
 418
 419         list_del_init(&hc->hc_item);
 420
 421         up_write(&r2hb_callback_sem);
 422 }
 423 EXPORT_SYMBOL_GPL(r2hb_unregister_callback);
 424
 425 int r2hb_check_node_heartbeating_from_callback(u8 node_num)
 426 {
 427         unsigned long testing_map[BITS_TO_LONGS(R2NM_MAX_NODES)];
 428
 429         r2hb_fill_node_map_from_callback(testing_map, sizeof(testing_map));
 430         if (!test_bit(node_num, testing_map)) {
 431                 mlog(ML_HEARTBEAT,
 432                      "node (%u) does not have heartbeating enabled.\n",
 433                      node_num);
 434                 return 0;
 435         }
 436
 437         return 1;
 438 }
 439 EXPORT_SYMBOL_GPL(r2hb_check_node_heartbeating_from_callback);
 440
 441 void r2hb_stop_all_regions(void)
 442 {
 443 }
 444 EXPORT_SYMBOL_GPL(r2hb_stop_all_regions);
 445
 446 /*
 447  * this is just a hack until we get the plumbing which flips file systems
 448  * read only and drops the hb ref instead of killing the node dead.
 449  */
 450 int r2hb_global_heartbeat_active(void)
 451 {
 452         return (r2hb_heartbeat_mode == R2HB_HEARTBEAT_GLOBAL);
 453 }
 454 EXPORT_SYMBOL(r2hb_global_heartbeat_active);
 455
 456 /* added for RAMster */
 457 void r2hb_manual_set_node_heartbeating(int node_num)
 458 {
 459         if (node_num < R2NM_MAX_NODES)
 460                 set_bit(node_num, r2hb_live_node_bitmap);
 461 }
 462 EXPORT_SYMBOL(r2hb_manual_set_node_heartbeating);