drivers/md/md-cluster.c

   1 /*
   2  * Copyright (C) 2015, SUSE
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2, or (at your option)
   7  * any later version.
   8  *
   9  */
  10
  11
  12 #include <linux/module.h>
  13 #include <linux/dlm.h>
  14 #include <linux/sched.h>
  15 #include <linux/raid/md_p.h>
  16 #include "md.h"
  17 #include "bitmap.h"
  18 #include "md-cluster.h"
  19
  20 #define LVB_SIZE        64
  21 #define NEW_DEV_TIMEOUT 5000
  22
  23 struct dlm_lock_resource {
  24         dlm_lockspace_t *ls;
  25         struct dlm_lksb lksb;
  26         char *name; /* lock name. */
  27         uint32_t flags; /* flags to pass to dlm_lock() */
  28         struct completion completion; /* completion for synchronized locking */
  29         void (*bast)(void *arg, int mode); /* blocking AST function pointer*/
  30         struct mddev *mddev; /* pointing back to mddev. */
  31         int mode;
  32 };
  33
  34 struct suspend_info {
  35         int slot;
  36         sector_t lo;
  37         sector_t hi;
  38         struct list_head list;
  39 };
  40
  41 struct resync_info {
  42         __le64 lo;
  43         __le64 hi;
  44 };
  45
  46 /* md_cluster_info flags */
  47 #define         MD_CLUSTER_WAITING_FOR_NEWDISK          1
  48 #define         MD_CLUSTER_SUSPEND_READ_BALANCING       2
  49 #define         MD_CLUSTER_BEGIN_JOIN_CLUSTER           3
  50
  51 /* Lock the send communication. This is done through
  52  * bit manipulation as opposed to a mutex in order to
  53  * accomodate lock and hold. See next comment.
  54  */
  55 #define         MD_CLUSTER_SEND_LOCK                    4
  56 /* If cluster operations (such as adding a disk) must lock the
  57  * communication channel, so as to perform extra operations
  58  * (update metadata) and no other operation is allowed on the
  59  * MD. Token needs to be locked and held until the operation
  60  * completes witha md_update_sb(), which would eventually release
  61  * the lock.
  62  */
  63 #define         MD_CLUSTER_SEND_LOCKED_ALREADY          5
  64
  65
  66 struct md_cluster_info {
  67         /* dlm lock space and resources for clustered raid. */
  68         dlm_lockspace_t *lockspace;
  69         int slot_number;
  70         struct completion completion;
  71         struct mutex recv_mutex;
  72         struct dlm_lock_resource *bitmap_lockres;
  73         struct dlm_lock_resource **other_bitmap_lockres;
  74         struct dlm_lock_resource *resync_lockres;
  75         struct list_head suspend_list;
  76         spinlock_t suspend_lock;
  77         struct md_thread *recovery_thread;
  78         unsigned long recovery_map;
  79         /* communication loc resources */
  80         struct dlm_lock_resource *ack_lockres;
  81         struct dlm_lock_resource *message_lockres;
  82         struct dlm_lock_resource *token_lockres;
  83         struct dlm_lock_resource *no_new_dev_lockres;
  84         struct md_thread *recv_thread;
  85         struct completion newdisk_completion;
  86         wait_queue_head_t wait;
  87         unsigned long state;
  88 };
  89
  90 enum msg_type {
  91         METADATA_UPDATED = 0,
  92         RESYNCING,
  93         NEWDISK,
  94         REMOVE,
  95         RE_ADD,
  96         BITMAP_NEEDS_SYNC,
  97 };
  98
  99 struct cluster_msg {
 100         __le32 type;
 101         __le32 slot;
 102         /* TODO: Unionize this for smaller footprint */
 103         __le64 low;
 104         __le64 high;
 105         char uuid[16];
 106         __le32 raid_slot;
 107 };
 108
 109 static void sync_ast(void *arg)
 110 {
 111         struct dlm_lock_resource *res;
 112
 113         res = arg;
 114         complete(&res->completion);
 115 }
 116
 117 static int dlm_lock_sync(struct dlm_lock_resource *res, int mode)
 118 {
 119         int ret = 0;
 120
 121         ret = dlm_lock(res->ls, mode, &res->lksb,
 122                         res->flags, res->name, strlen(res->name),
 123                         0, sync_ast, res, res->bast);
 124         if (ret)
 125                 return ret;
 126         wait_for_completion(&res->completion);
 127         if (res->lksb.sb_status == 0)
 128                 res->mode = mode;
 129         return res->lksb.sb_status;
 130 }
 131
 132 static int dlm_unlock_sync(struct dlm_lock_resource *res)
 133 {
 134         return dlm_lock_sync(res, DLM_LOCK_NL);
 135 }
 136
 137 static struct dlm_lock_resource *lockres_init(struct mddev *mddev,
 138                 char *name, void (*bastfn)(void *arg, int mode), int with_lvb)
 139 {
 140         struct dlm_lock_resource *res = NULL;
 141         int ret, namelen;
 142         struct md_cluster_info *cinfo = mddev->cluster_info;
 143
 144         res = kzalloc(sizeof(struct dlm_lock_resource), GFP_KERNEL);
 145         if (!res)
 146                 return NULL;
 147         init_completion(&res->completion);
 148         res->ls = cinfo->lockspace;
 149         res->mddev = mddev;
 150         res->mode = DLM_LOCK_IV;
 151         namelen = strlen(name);
 152         res->name = kzalloc(namelen + 1, GFP_KERNEL);
 153         if (!res->name) {
 154                 pr_err("md-cluster: Unable to allocate resource name for resource %s\n", name);
 155                 goto out_err;
 156         }
 157         strlcpy(res->name, name, namelen + 1);
 158         if (with_lvb) {
 159                 res->lksb.sb_lvbptr = kzalloc(LVB_SIZE, GFP_KERNEL);
 160                 if (!res->lksb.sb_lvbptr) {
 161                         pr_err("md-cluster: Unable to allocate LVB for resource %s\n", name);
 162                         goto out_err;
 163                 }
 164                 res->flags = DLM_LKF_VALBLK;
 165         }
 166
 167         if (bastfn)
 168                 res->bast = bastfn;
 169
 170         res->flags |= DLM_LKF_EXPEDITE;
 171
 172         ret = dlm_lock_sync(res, DLM_LOCK_NL);
 173         if (ret) {
 174                 pr_err("md-cluster: Unable to lock NL on new lock resource %s\n", name);
 175                 goto out_err;
 176         }
 177         res->flags &= ~DLM_LKF_EXPEDITE;
 178         res->flags |= DLM_LKF_CONVERT;
 179
 180         return res;
 181 out_err:
 182         kfree(res->lksb.sb_lvbptr);
 183         kfree(res->name);
 184         kfree(res);
 185         return NULL;
 186 }
 187
 188 static void lockres_free(struct dlm_lock_resource *res)
 189 {
 190         int ret;
 191
 192         if (!res)
 193                 return;
 194
 195         /* cancel a lock request or a conversion request that is blocked */
 196         res->flags |= DLM_LKF_CANCEL;
 197 retry:
 198         ret = dlm_unlock(res->ls, res->lksb.sb_lkid, 0, &res->lksb, res);
 199         if (unlikely(ret != 0)) {
 200                 pr_info("%s: failed to unlock %s return %d\n", __func__, res->name, ret);
 201
 202                 /* if a lock conversion is cancelled, then the lock is put
 203                  * back to grant queue, need to ensure it is unlocked */
 204                 if (ret == -DLM_ECANCEL)
 205                         goto retry;
 206         }
 207         res->flags &= ~DLM_LKF_CANCEL;
 208         wait_for_completion(&res->completion);
 209
 210         kfree(res->name);
 211         kfree(res->lksb.sb_lvbptr);
 212         kfree(res);
 213 }
 214
 215 static void add_resync_info(struct dlm_lock_resource *lockres,
 216                             sector_t lo, sector_t hi)
 217 {
 218         struct resync_info *ri;
 219
 220         ri = (struct resync_info *)lockres->lksb.sb_lvbptr;
 221         ri->lo = cpu_to_le64(lo);
 222         ri->hi = cpu_to_le64(hi);
 223 }
 224
 225 static struct suspend_info *read_resync_info(struct mddev *mddev, struct dlm_lock_resource *lockres)
 226 {
 227         struct resync_info ri;
 228         struct suspend_info *s = NULL;
 229         sector_t hi = 0;
 230
 231         dlm_lock_sync(lockres, DLM_LOCK_CR);
 232         memcpy(&ri, lockres->lksb.sb_lvbptr, sizeof(struct resync_info));
 233         hi = le64_to_cpu(ri.hi);
 234         if (hi > 0) {
 235                 s = kzalloc(sizeof(struct suspend_info), GFP_KERNEL);
 236                 if (!s)
 237                         goto out;
 238                 s->hi = hi;
 239                 s->lo = le64_to_cpu(ri.lo);
 240         }
 241         dlm_unlock_sync(lockres);
 242 out:
 243         return s;
 244 }
 245
 246 static void recover_bitmaps(struct md_thread *thread)
 247 {
 248         struct mddev *mddev = thread->mddev;
 249         struct md_cluster_info *cinfo = mddev->cluster_info;
 250         struct dlm_lock_resource *bm_lockres;
 251         char str[64];
 252         int slot, ret;
 253         struct suspend_info *s, *tmp;
 254         sector_t lo, hi;
 255
 256         while (cinfo->recovery_map) {
 257                 slot = fls64((u64)cinfo->recovery_map) - 1;
 258
 259                 /* Clear suspend_area associated with the bitmap */
 260                 spin_lock_irq(&cinfo->suspend_lock);
 261                 list_for_each_entry_safe(s, tmp, &cinfo->suspend_list, list)
 262                         if (slot == s->slot) {
 263                                 list_del(&s->list);
 264                                 kfree(s);
 265                         }
 266                 spin_unlock_irq(&cinfo->suspend_lock);
 267
 268                 snprintf(str, 64, "bitmap%04d", slot);
 269                 bm_lockres = lockres_init(mddev, str, NULL, 1);
 270                 if (!bm_lockres) {
 271                         pr_err("md-cluster: Cannot initialize bitmaps\n");
 272                         goto clear_bit;
 273                 }
 274
 275                 ret = dlm_lock_sync(bm_lockres, DLM_LOCK_PW);
 276                 if (ret) {
 277                         pr_err("md-cluster: Could not DLM lock %s: %d\n",
 278                                         str, ret);
 279                         goto clear_bit;
 280                 }
 281                 ret = bitmap_copy_from_slot(mddev, slot, &lo, &hi, true);
 282                 if (ret) {
 283                         pr_err("md-cluster: Could not copy data from bitmap %d\n", slot);
 284                         goto dlm_unlock;
 285                 }
 286                 if (hi > 0) {
 287                         if (lo < mddev->recovery_cp)
 288                                 mddev->recovery_cp = lo;
 289                         /* wake up thread to continue resync in case resync
 290                          * is not finished */
 291                         if (mddev->recovery_cp != MaxSector) {
 292                             set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
 293                             md_wakeup_thread(mddev->thread);
 294                         }
 295                 }
 296 dlm_unlock:
 297                 dlm_unlock_sync(bm_lockres);
 298 clear_bit:
 299                 lockres_free(bm_lockres);
 300                 clear_bit(slot, &cinfo->recovery_map);
 301         }
 302 }
 303
 304 static void recover_prep(void *arg)
 305 {
 306         struct mddev *mddev = arg;
 307         struct md_cluster_info *cinfo = mddev->cluster_info;
 308         set_bit(MD_CLUSTER_SUSPEND_READ_BALANCING, &cinfo->state);
 309 }
 310
 311 static void __recover_slot(struct mddev *mddev, int slot)
 312 {
 313         struct md_cluster_info *cinfo = mddev->cluster_info;
 314
 315         set_bit(slot, &cinfo->recovery_map);
 316         if (!cinfo->recovery_thread) {
 317                 cinfo->recovery_thread = md_register_thread(recover_bitmaps,
 318                                 mddev, "recover");
 319                 if (!cinfo->recovery_thread) {
 320                         pr_warn("md-cluster: Could not create recovery thread\n");
 321                         return;
 322                 }
 323         }
 324         md_wakeup_thread(cinfo->recovery_thread);
 325 }
 326
 327 static void recover_slot(void *arg, struct dlm_slot *slot)
 328 {
 329         struct mddev *mddev = arg;
 330         struct md_cluster_info *cinfo = mddev->cluster_info;
 331
 332         pr_info("md-cluster: %s Node %d/%d down. My slot: %d. Initiating recovery.\n",
 333                         mddev->bitmap_info.cluster_name,
 334                         slot->nodeid, slot->slot,
 335                         cinfo->slot_number);
 336         /* deduct one since dlm slot starts from one while the num of
 337          * cluster-md begins with 0 */
 338         __recover_slot(mddev, slot->slot - 1);
 339 }
 340
 341 static void recover_done(void *arg, struct dlm_slot *slots,
 342                 int num_slots, int our_slot,
 343                 uint32_t generation)
 344 {
 345         struct mddev *mddev = arg;
 346         struct md_cluster_info *cinfo = mddev->cluster_info;
 347
 348         cinfo->slot_number = our_slot;
 349         /* completion is only need to be complete when node join cluster,
 350          * it doesn't need to run during another node's failure */
 351         if (test_bit(MD_CLUSTER_BEGIN_JOIN_CLUSTER, &cinfo->state)) {
 352                 complete(&cinfo->completion);
 353                 clear_bit(MD_CLUSTER_BEGIN_JOIN_CLUSTER, &cinfo->state);
 354         }
 355         clear_bit(MD_CLUSTER_SUSPEND_READ_BALANCING, &cinfo->state);
 356 }
 357
 358 /* the ops is called when node join the cluster, and do lock recovery
 359  * if node failure occurs */
 360 static const struct dlm_lockspace_ops md_ls_ops = {
 361         .recover_prep = recover_prep,
 362         .recover_slot = recover_slot,
 363         .recover_done = recover_done,
 364 };
 365
 366 /*
 367  * The BAST function for the ack lock resource
 368  * This function wakes up the receive thread in
 369  * order to receive and process the message.
 370  */
 371 static void ack_bast(void *arg, int mode)
 372 {
 373         struct dlm_lock_resource *res = arg;
 374         struct md_cluster_info *cinfo = res->mddev->cluster_info;
 375
 376         if (mode == DLM_LOCK_EX)
 377                 md_wakeup_thread(cinfo->recv_thread);
 378 }
 379
 380 static void __remove_suspend_info(struct md_cluster_info *cinfo, int slot)
 381 {
 382         struct suspend_info *s, *tmp;
 383
 384         list_for_each_entry_safe(s, tmp, &cinfo->suspend_list, list)
 385                 if (slot == s->slot) {
 386                         list_del(&s->list);
 387                         kfree(s);
 388                         break;
 389                 }
 390 }
 391
 392 static void remove_suspend_info(struct mddev *mddev, int slot)
 393 {
 394         struct md_cluster_info *cinfo = mddev->cluster_info;
 395         spin_lock_irq(&cinfo->suspend_lock);
 396         __remove_suspend_info(cinfo, slot);
 397         spin_unlock_irq(&cinfo->suspend_lock);
 398         mddev->pers->quiesce(mddev, 2);
 399 }
 400
 401
 402 static void process_suspend_info(struct mddev *mddev,
 403                 int slot, sector_t lo, sector_t hi)
 404 {
 405         struct md_cluster_info *cinfo = mddev->cluster_info;
 406         struct suspend_info *s;
 407
 408         if (!hi) {
 409                 remove_suspend_info(mddev, slot);
 410                 set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
 411                 md_wakeup_thread(mddev->thread);
 412                 return;
 413         }
 414         s = kzalloc(sizeof(struct suspend_info), GFP_KERNEL);
 415         if (!s)
 416                 return;
 417         s->slot = slot;
 418         s->lo = lo;
 419         s->hi = hi;
 420         mddev->pers->quiesce(mddev, 1);
 421         mddev->pers->quiesce(mddev, 0);
 422         spin_lock_irq(&cinfo->suspend_lock);
 423         /* Remove existing entry (if exists) before adding */
 424         __remove_suspend_info(cinfo, slot);
 425         list_add(&s->list, &cinfo->suspend_list);
 426         spin_unlock_irq(&cinfo->suspend_lock);
 427         mddev->pers->quiesce(mddev, 2);
 428 }
 429
 430 static void process_add_new_disk(struct mddev *mddev, struct cluster_msg *cmsg)
 431 {
 432         char disk_uuid[64];
 433         struct md_cluster_info *cinfo = mddev->cluster_info;
 434         char event_name[] = "EVENT=ADD_DEVICE";
 435         char raid_slot[16];
 436         char *envp[] = {event_name, disk_uuid, raid_slot, NULL};
 437         int len;
 438
 439         len = snprintf(disk_uuid, 64, "DEVICE_UUID=");
 440         sprintf(disk_uuid + len, "%pU", cmsg->uuid);
 441         snprintf(raid_slot, 16, "RAID_DISK=%d", le32_to_cpu(cmsg->raid_slot));
 442         pr_info("%s:%d Sending kobject change with %s and %s\n", __func__, __LINE__, disk_uuid, raid_slot);
 443         init_completion(&cinfo->newdisk_completion);
 444         set_bit(MD_CLUSTER_WAITING_FOR_NEWDISK, &cinfo->state);
 445         kobject_uevent_env(&disk_to_dev(mddev->gendisk)->kobj, KOBJ_CHANGE, envp);
 446         wait_for_completion_timeout(&cinfo->newdisk_completion,
 447                         NEW_DEV_TIMEOUT);
 448         clear_bit(MD_CLUSTER_WAITING_FOR_NEWDISK, &cinfo->state);
 449 }
 450
 451
 452 static void process_metadata_update(struct mddev *mddev, struct cluster_msg *msg)
 453 {
 454         struct md_cluster_info *cinfo = mddev->cluster_info;
 455         mddev->good_device_nr = le32_to_cpu(msg->raid_slot);
 456         set_bit(MD_RELOAD_SB, &mddev->flags);
 457         dlm_lock_sync(cinfo->no_new_dev_lockres, DLM_LOCK_CR);
 458         md_wakeup_thread(mddev->thread);
 459 }
 460
 461 static void process_remove_disk(struct mddev *mddev, struct cluster_msg *msg)
 462 {
 463         struct md_rdev *rdev = md_find_rdev_nr_rcu(mddev,
 464                                                    le32_to_cpu(msg->raid_slot));
 465
 466         if (rdev) {
 467                 set_bit(ClusterRemove, &rdev->flags);
 468                 set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
 469                 md_wakeup_thread(mddev->thread);
 470         }
 471         else
 472                 pr_warn("%s: %d Could not find disk(%d) to REMOVE\n",
 473                         __func__, __LINE__, le32_to_cpu(msg->raid_slot));
 474 }
 475
 476 static void process_readd_disk(struct mddev *mddev, struct cluster_msg *msg)
 477 {
 478         struct md_rdev *rdev = md_find_rdev_nr_rcu(mddev,
 479                                                    le32_to_cpu(msg->raid_slot));
 480
 481         if (rdev && test_bit(Faulty, &rdev->flags))
 482                 clear_bit(Faulty, &rdev->flags);
 483         else
 484                 pr_warn("%s: %d Could not find disk(%d) which is faulty",
 485                         __func__, __LINE__, le32_to_cpu(msg->raid_slot));
 486 }
 487
 488 static void process_recvd_msg(struct mddev *mddev, struct cluster_msg *msg)
 489 {
 490         if (WARN(mddev->cluster_info->slot_number - 1 == le32_to_cpu(msg->slot),
 491                 "node %d received it's own msg\n", le32_to_cpu(msg->slot)))
 492                 return;
 493         switch (le32_to_cpu(msg->type)) {
 494         case METADATA_UPDATED:
 495                 process_metadata_update(mddev, msg);
 496                 break;
 497         case RESYNCING:
 498                 process_suspend_info(mddev, le32_to_cpu(msg->slot),
 499                                      le64_to_cpu(msg->low),
 500                                      le64_to_cpu(msg->high));
 501                 break;
 502         case NEWDISK:
 503                 process_add_new_disk(mddev, msg);
 504                 break;
 505         case REMOVE:
 506                 process_remove_disk(mddev, msg);
 507                 break;
 508         case RE_ADD:
 509                 process_readd_disk(mddev, msg);
 510                 break;
 511         case BITMAP_NEEDS_SYNC:
 512                 __recover_slot(mddev, le32_to_cpu(msg->slot));
 513                 break;
 514         default:
 515                 pr_warn("%s:%d Received unknown message from %d\n",
 516                         __func__, __LINE__, msg->slot);
 517         }
 518 }
 519
 520 /*
 521  * thread for receiving message
 522  */
 523 static void recv_daemon(struct md_thread *thread)
 524 {
 525         struct md_cluster_info *cinfo = thread->mddev->cluster_info;
 526         struct dlm_lock_resource *ack_lockres = cinfo->ack_lockres;
 527         struct dlm_lock_resource *message_lockres = cinfo->message_lockres;
 528         struct cluster_msg msg;
 529         int ret;
 530
 531         mutex_lock(&cinfo->recv_mutex);
 532         /*get CR on Message*/
 533         if (dlm_lock_sync(message_lockres, DLM_LOCK_CR)) {
 534                 pr_err("md/raid1:failed to get CR on MESSAGE\n");
 535                 mutex_unlock(&cinfo->recv_mutex);
 536                 return;
 537         }
 538
 539         /* read lvb and wake up thread to process this message_lockres */
 540         memcpy(&msg, message_lockres->lksb.sb_lvbptr, sizeof(struct cluster_msg));
 541         process_recvd_msg(thread->mddev, &msg);
 542
 543         /*release CR on ack_lockres*/
 544         ret = dlm_unlock_sync(ack_lockres);
 545         if (unlikely(ret != 0))
 546                 pr_info("unlock ack failed return %d\n", ret);
 547         /*up-convert to PR on message_lockres*/
 548         ret = dlm_lock_sync(message_lockres, DLM_LOCK_PR);
 549         if (unlikely(ret != 0))
 550                 pr_info("lock PR on msg failed return %d\n", ret);
 551         /*get CR on ack_lockres again*/
 552         ret = dlm_lock_sync(ack_lockres, DLM_LOCK_CR);
 553         if (unlikely(ret != 0))
 554                 pr_info("lock CR on ack failed return %d\n", ret);
 555         /*release CR on message_lockres*/
 556         ret = dlm_unlock_sync(message_lockres);
 557         if (unlikely(ret != 0))
 558                 pr_info("unlock msg failed return %d\n", ret);
 559         mutex_unlock(&cinfo->recv_mutex);
 560 }
 561
 562 /* lock_token()
 563  * Takes the lock on the TOKEN lock resource so no other
 564  * node can communicate while the operation is underway.
 565  */
 566 static int lock_token(struct md_cluster_info *cinfo)
 567 {
 568         int error;
 569
 570         error = dlm_lock_sync(cinfo->token_lockres, DLM_LOCK_EX);
 571         if (error)
 572                 pr_err("md-cluster(%s:%d): failed to get EX on TOKEN (%d)\n",
 573                                 __func__, __LINE__, error);
 574
 575         /* Lock the receive sequence */
 576         mutex_lock(&cinfo->recv_mutex);
 577         return error;
 578 }
 579
 580 /* lock_comm()
 581  * Sets the MD_CLUSTER_SEND_LOCK bit to lock the send channel.
 582  */
 583 static int lock_comm(struct md_cluster_info *cinfo)
 584 {
 585         wait_event(cinfo->wait,
 586                    !test_and_set_bit(MD_CLUSTER_SEND_LOCK, &cinfo->state));
 587
 588         return lock_token(cinfo);
 589 }
 590
 591 static void unlock_comm(struct md_cluster_info *cinfo)
 592 {
 593         WARN_ON(cinfo->token_lockres->mode != DLM_LOCK_EX);
 594         mutex_unlock(&cinfo->recv_mutex);
 595         dlm_unlock_sync(cinfo->token_lockres);
 596         clear_bit(MD_CLUSTER_SEND_LOCK, &cinfo->state);
 597         wake_up(&cinfo->wait);
 598 }
 599
 600 /* __sendmsg()
 601  * This function performs the actual sending of the message. This function is
 602  * usually called after performing the encompassing operation
 603  * The function:
 604  * 1. Grabs the message lockresource in EX mode
 605  * 2. Copies the message to the message LVB
 606  * 3. Downconverts message lockresource to CW
 607  * 4. Upconverts ack lock resource from CR to EX. This forces the BAST on other nodes
 608  *    and the other nodes read the message. The thread will wait here until all other
 609  *    nodes have released ack lock resource.
 610  * 5. Downconvert ack lockresource to CR
 611  */
 612 static int __sendmsg(struct md_cluster_info *cinfo, struct cluster_msg *cmsg)
 613 {
 614         int error;
 615         int slot = cinfo->slot_number - 1;
 616
 617         cmsg->slot = cpu_to_le32(slot);
 618         /*get EX on Message*/
 619         error = dlm_lock_sync(cinfo->message_lockres, DLM_LOCK_EX);
 620         if (error) {
 621                 pr_err("md-cluster: failed to get EX on MESSAGE (%d)\n", error);
 622                 goto failed_message;
 623         }
 624
 625         memcpy(cinfo->message_lockres->lksb.sb_lvbptr, (void *)cmsg,
 626                         sizeof(struct cluster_msg));
 627         /*down-convert EX to CW on Message*/
 628         error = dlm_lock_sync(cinfo->message_lockres, DLM_LOCK_CW);
 629         if (error) {
 630                 pr_err("md-cluster: failed to convert EX to CW on MESSAGE(%d)\n",
 631                                 error);
 632                 goto failed_ack;
 633         }
 634
 635         /*up-convert CR to EX on Ack*/
 636         error = dlm_lock_sync(cinfo->ack_lockres, DLM_LOCK_EX);
 637         if (error) {
 638                 pr_err("md-cluster: failed to convert CR to EX on ACK(%d)\n",
 639                                 error);
 640                 goto failed_ack;
 641         }
 642
 643         /*down-convert EX to CR on Ack*/
 644         error = dlm_lock_sync(cinfo->ack_lockres, DLM_LOCK_CR);
 645         if (error) {
 646                 pr_err("md-cluster: failed to convert EX to CR on ACK(%d)\n",
 647                                 error);
 648                 goto failed_ack;
 649         }
 650
 651 failed_ack:
 652         error = dlm_unlock_sync(cinfo->message_lockres);
 653         if (unlikely(error != 0)) {
 654                 pr_err("md-cluster: failed convert to NL on MESSAGE(%d)\n",
 655                         error);
 656                 /* in case the message can't be released due to some reason */
 657                 goto failed_ack;
 658         }
 659 failed_message:
 660         return error;
 661 }
 662
 663 static int sendmsg(struct md_cluster_info *cinfo, struct cluster_msg *cmsg)
 664 {
 665         int ret;
 666
 667         lock_comm(cinfo);
 668         ret = __sendmsg(cinfo, cmsg);
 669         unlock_comm(cinfo);
 670         return ret;
 671 }
 672
 673 static int gather_all_resync_info(struct mddev *mddev, int total_slots)
 674 {
 675         struct md_cluster_info *cinfo = mddev->cluster_info;
 676         int i, ret = 0;
 677         struct dlm_lock_resource *bm_lockres;
 678         struct suspend_info *s;
 679         char str[64];
 680         sector_t lo, hi;
 681
 682
 683         for (i = 0; i < total_slots; i++) {
 684                 memset(str, '\0', 64);
 685                 snprintf(str, 64, "bitmap%04d", i);
 686                 bm_lockres = lockres_init(mddev, str, NULL, 1);
 687                 if (!bm_lockres)
 688                         return -ENOMEM;
 689                 if (i == (cinfo->slot_number - 1)) {
 690                         lockres_free(bm_lockres);
 691                         continue;
 692                 }
 693
 694                 bm_lockres->flags |= DLM_LKF_NOQUEUE;
 695                 ret = dlm_lock_sync(bm_lockres, DLM_LOCK_PW);
 696                 if (ret == -EAGAIN) {
 697                         memset(bm_lockres->lksb.sb_lvbptr, '\0', LVB_SIZE);
 698                         s = read_resync_info(mddev, bm_lockres);
 699                         if (s) {
 700                                 pr_info("%s:%d Resync[%llu..%llu] in progress on %d\n",
 701                                                 __func__, __LINE__,
 702                                                 (unsigned long long) s->lo,
 703                                                 (unsigned long long) s->hi, i);
 704                                 spin_lock_irq(&cinfo->suspend_lock);
 705                                 s->slot = i;
 706                                 list_add(&s->list, &cinfo->suspend_list);
 707                                 spin_unlock_irq(&cinfo->suspend_lock);
 708                         }
 709                         ret = 0;
 710                         lockres_free(bm_lockres);
 711                         continue;
 712                 }
 713                 if (ret) {
 714                         lockres_free(bm_lockres);
 715                         goto out;
 716                 }
 717
 718                 /* Read the disk bitmap sb and check if it needs recovery */
 719                 ret = bitmap_copy_from_slot(mddev, i, &lo, &hi, false);
 720                 if (ret) {
 721                         pr_warn("md-cluster: Could not gather bitmaps from slot %d", i);
 722                         lockres_free(bm_lockres);
 723                         continue;
 724                 }
 725                 if ((hi > 0) && (lo < mddev->recovery_cp)) {
 726                         set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
 727                         mddev->recovery_cp = lo;
 728                         md_check_recovery(mddev);
 729                 }
 730
 731                 dlm_unlock_sync(bm_lockres);
 732                 lockres_free(bm_lockres);
 733         }
 734 out:
 735         return ret;
 736 }
 737
 738 static int join(struct mddev *mddev, int nodes)
 739 {
 740         struct md_cluster_info *cinfo;
 741         int ret, ops_rv;
 742         char str[64];
 743
 744         cinfo = kzalloc(sizeof(struct md_cluster_info), GFP_KERNEL);
 745         if (!cinfo)
 746                 return -ENOMEM;
 747
 748         INIT_LIST_HEAD(&cinfo->suspend_list);
 749         spin_lock_init(&cinfo->suspend_lock);
 750         init_completion(&cinfo->completion);
 751         set_bit(MD_CLUSTER_BEGIN_JOIN_CLUSTER, &cinfo->state);
 752         init_waitqueue_head(&cinfo->wait);
 753         mutex_init(&cinfo->recv_mutex);
 754
 755         mddev->cluster_info = cinfo;
 756
 757         memset(str, 0, 64);
 758         sprintf(str, "%pU", mddev->uuid);
 759         ret = dlm_new_lockspace(str, mddev->bitmap_info.cluster_name,
 760                                 DLM_LSFL_FS, LVB_SIZE,
 761                                 &md_ls_ops, mddev, &ops_rv, &cinfo->lockspace);
 762         if (ret)
 763                 goto err;
 764         wait_for_completion(&cinfo->completion);
 765         if (nodes < cinfo->slot_number) {
 766                 pr_err("md-cluster: Slot allotted(%d) is greater than available slots(%d).",
 767                         cinfo->slot_number, nodes);
 768                 ret = -ERANGE;
 769                 goto err;
 770         }
 771         /* Initiate the communication resources */
 772         ret = -ENOMEM;
 773         cinfo->recv_thread = md_register_thread(recv_daemon, mddev, "cluster_recv");
 774         if (!cinfo->recv_thread) {
 775                 pr_err("md-cluster: cannot allocate memory for recv_thread!\n");
 776                 goto err;
 777         }
 778         cinfo->message_lockres = lockres_init(mddev, "message", NULL, 1);
 779         if (!cinfo->message_lockres)
 780                 goto err;
 781         cinfo->token_lockres = lockres_init(mddev, "token", NULL, 0);
 782         if (!cinfo->token_lockres)
 783                 goto err;
 784         cinfo->ack_lockres = lockres_init(mddev, "ack", ack_bast, 0);
 785         if (!cinfo->ack_lockres)
 786                 goto err;
 787         cinfo->no_new_dev_lockres = lockres_init(mddev, "no-new-dev", NULL, 0);
 788         if (!cinfo->no_new_dev_lockres)
 789                 goto err;
 790
 791         /* get sync CR lock on ACK. */
 792         if (dlm_lock_sync(cinfo->ack_lockres, DLM_LOCK_CR))
 793                 pr_err("md-cluster: failed to get a sync CR lock on ACK!(%d)\n",
 794                                 ret);
 795         /* get sync CR lock on no-new-dev. */
 796         if (dlm_lock_sync(cinfo->no_new_dev_lockres, DLM_LOCK_CR))
 797                 pr_err("md-cluster: failed to get a sync CR lock on no-new-dev!(%d)\n", ret);
 798
 799
 800         pr_info("md-cluster: Joined cluster %s slot %d\n", str, cinfo->slot_number);
 801         snprintf(str, 64, "bitmap%04d", cinfo->slot_number - 1);
 802         cinfo->bitmap_lockres = lockres_init(mddev, str, NULL, 1);
 803         if (!cinfo->bitmap_lockres)
 804                 goto err;
 805         if (dlm_lock_sync(cinfo->bitmap_lockres, DLM_LOCK_PW)) {
 806                 pr_err("Failed to get bitmap lock\n");
 807                 ret = -EINVAL;
 808                 goto err;
 809         }
 810
 811         cinfo->resync_lockres = lockres_init(mddev, "resync", NULL, 0);
 812         if (!cinfo->resync_lockres)
 813                 goto err;
 814
 815         ret = gather_all_resync_info(mddev, nodes);
 816         if (ret)
 817                 goto err;
 818
 819         return 0;
 820 err:
 821         md_unregister_thread(&cinfo->recovery_thread);
 822         md_unregister_thread(&cinfo->recv_thread);
 823         lockres_free(cinfo->message_lockres);
 824         lockres_free(cinfo->token_lockres);
 825         lockres_free(cinfo->ack_lockres);
 826         lockres_free(cinfo->no_new_dev_lockres);
 827         lockres_free(cinfo->resync_lockres);
 828         lockres_free(cinfo->bitmap_lockres);
 829         if (cinfo->lockspace)
 830                 dlm_release_lockspace(cinfo->lockspace, 2);
 831         mddev->cluster_info = NULL;
 832         kfree(cinfo);
 833         return ret;
 834 }
 835
 836 static void resync_bitmap(struct mddev *mddev)
 837 {
 838         struct md_cluster_info *cinfo = mddev->cluster_info;
 839         struct cluster_msg cmsg = {0};
 840         int err;
 841
 842         cmsg.type = cpu_to_le32(BITMAP_NEEDS_SYNC);
 843         err = sendmsg(cinfo, &cmsg);
 844         if (err)
 845                 pr_err("%s:%d: failed to send BITMAP_NEEDS_SYNC message (%d)\n",
 846                         __func__, __LINE__, err);
 847 }
 848
 849 static void unlock_all_bitmaps(struct mddev *mddev);
 850 static int leave(struct mddev *mddev)
 851 {
 852         struct md_cluster_info *cinfo = mddev->cluster_info;
 853
 854         if (!cinfo)
 855                 return 0;
 856
 857         /* BITMAP_NEEDS_SYNC message should be sent when node
 858          * is leaving the cluster with dirty bitmap, also we
 859          * can only deliver it when dlm connection is available */
 860         if (cinfo->slot_number > 0 && mddev->recovery_cp != MaxSector)
 861                 resync_bitmap(mddev);
 862
 863         md_unregister_thread(&cinfo->recovery_thread);
 864         md_unregister_thread(&cinfo->recv_thread);
 865         lockres_free(cinfo->message_lockres);
 866         lockres_free(cinfo->token_lockres);
 867         lockres_free(cinfo->ack_lockres);
 868         lockres_free(cinfo->no_new_dev_lockres);
 869         lockres_free(cinfo->resync_lockres);
 870         lockres_free(cinfo->bitmap_lockres);
 871         unlock_all_bitmaps(mddev);
 872         dlm_release_lockspace(cinfo->lockspace, 2);
 873         return 0;
 874 }
 875
 876 /* slot_number(): Returns the MD slot number to use
 877  * DLM starts the slot numbers from 1, wheras cluster-md
 878  * wants the number to be from zero, so we deduct one
 879  */
 880 static int slot_number(struct mddev *mddev)
 881 {
 882         struct md_cluster_info *cinfo = mddev->cluster_info;
 883
 884         return cinfo->slot_number - 1;
 885 }
 886
 887 /*
 888  * Check if the communication is already locked, else lock the communication
 889  * channel.
 890  * If it is already locked, token is in EX mode, and hence lock_token()
 891  * should not be called.
 892  */
 893 static int metadata_update_start(struct mddev *mddev)
 894 {
 895         struct md_cluster_info *cinfo = mddev->cluster_info;
 896
 897         wait_event(cinfo->wait,
 898                    !test_and_set_bit(MD_CLUSTER_SEND_LOCK, &cinfo->state) ||
 899                    test_and_clear_bit(MD_CLUSTER_SEND_LOCKED_ALREADY, &cinfo->state));
 900
 901         /* If token is already locked, return 0 */
 902         if (cinfo->token_lockres->mode == DLM_LOCK_EX)
 903                 return 0;
 904
 905         return lock_token(cinfo);
 906 }
 907
 908 static int metadata_update_finish(struct mddev *mddev)
 909 {
 910         struct md_cluster_info *cinfo = mddev->cluster_info;
 911         struct cluster_msg cmsg;
 912         struct md_rdev *rdev;
 913         int ret = 0;
 914         int raid_slot = -1;
 915
 916         memset(&cmsg, 0, sizeof(cmsg));
 917         cmsg.type = cpu_to_le32(METADATA_UPDATED);
 918         /* Pick up a good active device number to send.
 919          */
 920         rdev_for_each(rdev, mddev)
 921                 if (rdev->raid_disk > -1 && !test_bit(Faulty, &rdev->flags)) {
 922                         raid_slot = rdev->desc_nr;
 923                         break;
 924                 }
 925         if (raid_slot >= 0) {
 926                 cmsg.raid_slot = cpu_to_le32(raid_slot);
 927                 ret = __sendmsg(cinfo, &cmsg);
 928         } else
 929                 pr_warn("md-cluster: No good device id found to send\n");
 930         clear_bit(MD_CLUSTER_SEND_LOCKED_ALREADY, &cinfo->state);
 931         unlock_comm(cinfo);
 932         return ret;
 933 }
 934
 935 static void metadata_update_cancel(struct mddev *mddev)
 936 {
 937         struct md_cluster_info *cinfo = mddev->cluster_info;
 938         clear_bit(MD_CLUSTER_SEND_LOCKED_ALREADY, &cinfo->state);
 939         unlock_comm(cinfo);
 940 }
 941
 942 static int resync_start(struct mddev *mddev)
 943 {
 944         struct md_cluster_info *cinfo = mddev->cluster_info;
 945         return dlm_lock_sync(cinfo->resync_lockres, DLM_LOCK_EX);
 946 }
 947
 948 static int resync_info_update(struct mddev *mddev, sector_t lo, sector_t hi)
 949 {
 950         struct md_cluster_info *cinfo = mddev->cluster_info;
 951         struct resync_info ri;
 952         struct cluster_msg cmsg = {0};
 953
 954         /* do not send zero again, if we have sent before */
 955         if (hi == 0) {
 956                 memcpy(&ri, cinfo->bitmap_lockres->lksb.sb_lvbptr, sizeof(struct resync_info));
 957                 if (le64_to_cpu(ri.hi) == 0)
 958                         return 0;
 959         }
 960
 961         add_resync_info(cinfo->bitmap_lockres, lo, hi);
 962         /* Re-acquire the lock to refresh LVB */
 963         dlm_lock_sync(cinfo->bitmap_lockres, DLM_LOCK_PW);
 964         cmsg.type = cpu_to_le32(RESYNCING);
 965         cmsg.low = cpu_to_le64(lo);
 966         cmsg.high = cpu_to_le64(hi);
 967
 968         return sendmsg(cinfo, &cmsg);
 969 }
 970
 971 static int resync_finish(struct mddev *mddev)
 972 {
 973         struct md_cluster_info *cinfo = mddev->cluster_info;
 974         dlm_unlock_sync(cinfo->resync_lockres);
 975         return resync_info_update(mddev, 0, 0);
 976 }
 977
 978 static int area_resyncing(struct mddev *mddev, int direction,
 979                 sector_t lo, sector_t hi)
 980 {
 981         struct md_cluster_info *cinfo = mddev->cluster_info;
 982         int ret = 0;
 983         struct suspend_info *s;
 984
 985         if ((direction == READ) &&
 986                 test_bit(MD_CLUSTER_SUSPEND_READ_BALANCING, &cinfo->state))
 987                 return 1;
 988
 989         spin_lock_irq(&cinfo->suspend_lock);
 990         if (list_empty(&cinfo->suspend_list))
 991                 goto out;
 992         list_for_each_entry(s, &cinfo->suspend_list, list)
 993                 if (hi > s->lo && lo < s->hi) {
 994                         ret = 1;
 995                         break;
 996                 }
 997 out:
 998         spin_unlock_irq(&cinfo->suspend_lock);
 999         return ret;
1000 }
1001
1002 /* add_new_disk() - initiates a disk add
1003  * However, if this fails before writing md_update_sb(),
1004  * add_new_disk_cancel() must be called to release token lock
1005  */
1006 static int add_new_disk(struct mddev *mddev, struct md_rdev *rdev)
1007 {
1008         struct md_cluster_info *cinfo = mddev->cluster_info;
1009         struct cluster_msg cmsg;
1010         int ret = 0;
1011         struct mdp_superblock_1 *sb = page_address(rdev->sb_page);
1012         char *uuid = sb->device_uuid;
1013
1014         memset(&cmsg, 0, sizeof(cmsg));
1015         cmsg.type = cpu_to_le32(NEWDISK);
1016         memcpy(cmsg.uuid, uuid, 16);
1017         cmsg.raid_slot = cpu_to_le32(rdev->desc_nr);
1018         lock_comm(cinfo);
1019         ret = __sendmsg(cinfo, &cmsg);
1020         if (ret)
1021                 return ret;
1022         cinfo->no_new_dev_lockres->flags |= DLM_LKF_NOQUEUE;
1023         ret = dlm_lock_sync(cinfo->no_new_dev_lockres, DLM_LOCK_EX);
1024         cinfo->no_new_dev_lockres->flags &= ~DLM_LKF_NOQUEUE;
1025         /* Some node does not "see" the device */
1026         if (ret == -EAGAIN)
1027                 ret = -ENOENT;
1028         if (ret)
1029                 unlock_comm(cinfo);
1030         else {
1031                 dlm_lock_sync(cinfo->no_new_dev_lockres, DLM_LOCK_CR);
1032                 /* Since MD_CHANGE_DEVS will be set in add_bound_rdev which
1033                  * will run soon after add_new_disk, the below path will be
1034                  * invoked:
1035                  *   md_wakeup_thread(mddev->thread)
1036                  *      -> conf->thread (raid1d)
1037                  *      -> md_check_recovery -> md_update_sb
1038                  *      -> metadata_update_start/finish
1039                  * MD_CLUSTER_SEND_LOCKED_ALREADY will be cleared eventually.
1040                  *
1041                  * For other failure cases, metadata_update_cancel and
1042                  * add_new_disk_cancel also clear below bit as well.
1043                  * */
1044                 set_bit(MD_CLUSTER_SEND_LOCKED_ALREADY, &cinfo->state);
1045                 wake_up(&cinfo->wait);
1046         }
1047         return ret;
1048 }
1049
1050 static void add_new_disk_cancel(struct mddev *mddev)
1051 {
1052         struct md_cluster_info *cinfo = mddev->cluster_info;
1053         clear_bit(MD_CLUSTER_SEND_LOCKED_ALREADY, &cinfo->state);
1054         unlock_comm(cinfo);
1055 }
1056
1057 static int new_disk_ack(struct mddev *mddev, bool ack)
1058 {
1059         struct md_cluster_info *cinfo = mddev->cluster_info;
1060
1061         if (!test_bit(MD_CLUSTER_WAITING_FOR_NEWDISK, &cinfo->state)) {
1062                 pr_warn("md-cluster(%s): Spurious cluster confirmation\n", mdname(mddev));
1063                 return -EINVAL;
1064         }
1065
1066         if (ack)
1067                 dlm_unlock_sync(cinfo->no_new_dev_lockres);
1068         complete(&cinfo->newdisk_completion);
1069         return 0;
1070 }
1071
1072 static int remove_disk(struct mddev *mddev, struct md_rdev *rdev)
1073 {
1074         struct cluster_msg cmsg = {0};
1075         struct md_cluster_info *cinfo = mddev->cluster_info;
1076         cmsg.type = cpu_to_le32(REMOVE);
1077         cmsg.raid_slot = cpu_to_le32(rdev->desc_nr);
1078         return sendmsg(cinfo, &cmsg);
1079 }
1080
1081 static int lock_all_bitmaps(struct mddev *mddev)
1082 {
1083         int slot, my_slot, ret, held = 1, i = 0;
1084         char str[64];
1085         struct md_cluster_info *cinfo = mddev->cluster_info;
1086
1087         cinfo->other_bitmap_lockres = kzalloc((mddev->bitmap_info.nodes - 1) *
1088                                              sizeof(struct dlm_lock_resource *),
1089                                              GFP_KERNEL);
1090         if (!cinfo->other_bitmap_lockres) {
1091                 pr_err("md: can't alloc mem for other bitmap locks\n");
1092                 return 0;
1093         }
1094
1095         my_slot = slot_number(mddev);
1096         for (slot = 0; slot < mddev->bitmap_info.nodes; slot++) {
1097                 if (slot == my_slot)
1098                         continue;
1099
1100                 memset(str, '\0', 64);
1101                 snprintf(str, 64, "bitmap%04d", slot);
1102                 cinfo->other_bitmap_lockres[i] = lockres_init(mddev, str, NULL, 1);
1103                 if (!cinfo->other_bitmap_lockres[i])
1104                         return -ENOMEM;
1105
1106                 cinfo->other_bitmap_lockres[i]->flags |= DLM_LKF_NOQUEUE;
1107                 ret = dlm_lock_sync(cinfo->other_bitmap_lockres[i], DLM_LOCK_PW);
1108                 if (ret)
1109                         held = -1;
1110                 i++;
1111         }
1112
1113         return held;
1114 }
1115
1116 static void unlock_all_bitmaps(struct mddev *mddev)
1117 {
1118         struct md_cluster_info *cinfo = mddev->cluster_info;
1119         int i;
1120
1121         /* release other node's bitmap lock if they are existed */
1122         if (cinfo->other_bitmap_lockres) {
1123                 for (i = 0; i < mddev->bitmap_info.nodes - 1; i++) {
1124                         if (cinfo->other_bitmap_lockres[i]) {
1125                                 dlm_unlock_sync(cinfo->other_bitmap_lockres[i]);
1126                                 lockres_free(cinfo->other_bitmap_lockres[i]);
1127                         }
1128                 }
1129                 kfree(cinfo->other_bitmap_lockres);
1130         }
1131 }
1132
1133 static int gather_bitmaps(struct md_rdev *rdev)
1134 {
1135         int sn, err;
1136         sector_t lo, hi;
1137         struct cluster_msg cmsg = {0};
1138         struct mddev *mddev = rdev->mddev;
1139         struct md_cluster_info *cinfo = mddev->cluster_info;
1140
1141         cmsg.type = cpu_to_le32(RE_ADD);
1142         cmsg.raid_slot = cpu_to_le32(rdev->desc_nr);
1143         err = sendmsg(cinfo, &cmsg);
1144         if (err)
1145                 goto out;
1146
1147         for (sn = 0; sn < mddev->bitmap_info.nodes; sn++) {
1148                 if (sn == (cinfo->slot_number - 1))
1149                         continue;
1150                 err = bitmap_copy_from_slot(mddev, sn, &lo, &hi, false);
1151                 if (err) {
1152                         pr_warn("md-cluster: Could not gather bitmaps from slot %d", sn);
1153                         goto out;
1154                 }
1155                 if ((hi > 0) && (lo < mddev->recovery_cp))
1156                         mddev->recovery_cp = lo;
1157         }
1158 out:
1159         return err;
1160 }
1161
1162 static struct md_cluster_operations cluster_ops = {
1163         .join   = join,
1164         .leave  = leave,
1165         .slot_number = slot_number,
1166         .resync_start = resync_start,
1167         .resync_finish = resync_finish,
1168         .resync_info_update = resync_info_update,
1169         .metadata_update_start = metadata_update_start,
1170         .metadata_update_finish = metadata_update_finish,
1171         .metadata_update_cancel = metadata_update_cancel,
1172         .area_resyncing = area_resyncing,
1173         .add_new_disk = add_new_disk,
1174         .add_new_disk_cancel = add_new_disk_cancel,
1175         .new_disk_ack = new_disk_ack,
1176         .remove_disk = remove_disk,
1177         .gather_bitmaps = gather_bitmaps,
1178         .lock_all_bitmaps = lock_all_bitmaps,
1179         .unlock_all_bitmaps = unlock_all_bitmaps,
1180 };
1181
1182 static int __init cluster_init(void)
1183 {
1184         pr_warn("md-cluster: EXPERIMENTAL. Use with caution\n");
1185         pr_info("Registering Cluster MD functions\n");
1186         register_md_cluster_operations(&cluster_ops, THIS_MODULE);
1187         return 0;
1188 }
1189
1190 static void cluster_exit(void)
1191 {
1192         unregister_md_cluster_operations();
1193 }
1194
1195 module_init(cluster_init);
1196 module_exit(cluster_exit);
1197 MODULE_AUTHOR("SUSE");
1198 MODULE_LICENSE("GPL");
1199 MODULE_DESCRIPTION("Clustering support for MD");