fs/ocfs2/dlm/userdlm.c

   1 /* -*- mode: c; c-basic-offset: 8; -*-
   2  * vim: noexpandtab sw=8 ts=8 sts=0:
   3  *
   4  * userdlm.c
   5  *
   6  * Code which implements the kernel side of a minimal userspace
   7  * interface to our DLM.
   8  *
   9  * Many of the functions here are pared down versions of dlmglue.c
  10  * functions.
  11  *
  12  * Copyright (C) 2003, 2004 Oracle.  All rights reserved.
  13  *
  14  * This program is free software; you can redistribute it and/or
  15  * modify it under the terms of the GNU General Public
  16  * License as published by the Free Software Foundation; either
  17  * version 2 of the License, or (at your option) any later version.
  18  *
  19  * This program is distributed in the hope that it will be useful,
  20  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  21  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  22  * General Public License for more details.
  23  *
  24  * You should have received a copy of the GNU General Public
  25  * License along with this program; if not, write to the
  26  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  27  * Boston, MA 021110-1307, USA.
  28  */
  29
  30 #include <linux/signal.h>
  31
  32 #include <linux/module.h>
  33 #include <linux/fs.h>
  34 #include <linux/types.h>
  35 #include <linux/crc32.h>
  36
  37
  38 #include "cluster/nodemanager.h"
  39 #include "cluster/heartbeat.h"
  40 #include "cluster/tcp.h"
  41
  42 #include "dlmapi.h"
  43
  44 #include "userdlm.h"
  45
  46 #define MLOG_MASK_PREFIX ML_DLMFS
  47 #include "cluster/masklog.h"
  48
  49 static inline int user_check_wait_flag(struct user_lock_res *lockres,
  50                                        int flag)
  51 {
  52         int ret;
  53
  54         spin_lock(&lockres->l_lock);
  55         ret = lockres->l_flags & flag;
  56         spin_unlock(&lockres->l_lock);
  57
  58         return ret;
  59 }
  60
  61 static inline void user_wait_on_busy_lock(struct user_lock_res *lockres)
  62
  63 {
  64         wait_event(lockres->l_event,
  65                    !user_check_wait_flag(lockres, USER_LOCK_BUSY));
  66 }
  67
  68 static inline void user_wait_on_blocked_lock(struct user_lock_res *lockres)
  69
  70 {
  71         wait_event(lockres->l_event,
  72                    !user_check_wait_flag(lockres, USER_LOCK_BLOCKED));
  73 }
  74
  75 /* I heart container_of... */
  76 static inline struct dlm_ctxt *
  77 dlm_ctxt_from_user_lockres(struct user_lock_res *lockres)
  78 {
  79         struct dlmfs_inode_private *ip;
  80
  81         ip = container_of(lockres,
  82                           struct dlmfs_inode_private,
  83                           ip_lockres);
  84         return ip->ip_dlm;
  85 }
  86
  87 static struct inode *
  88 user_dlm_inode_from_user_lockres(struct user_lock_res *lockres)
  89 {
  90         struct dlmfs_inode_private *ip;
  91
  92         ip = container_of(lockres,
  93                           struct dlmfs_inode_private,
  94                           ip_lockres);
  95         return &ip->ip_vfs_inode;
  96 }
  97
  98 static inline void user_recover_from_dlm_error(struct user_lock_res *lockres)
  99 {
 100         spin_lock(&lockres->l_lock);
 101         lockres->l_flags &= ~USER_LOCK_BUSY;
 102         spin_unlock(&lockres->l_lock);
 103 }
 104
 105 #define user_log_dlm_error(_func, _stat, _lockres) do {         \
 106         mlog(ML_ERROR, "Dlm error \"%s\" while calling %s on "  \
 107                 "resource %s: %s\n", dlm_errname(_stat), _func, \
 108                 _lockres->l_name, dlm_errmsg(_stat));           \
 109 } while (0)
 110
 111 /* WARNING: This function lives in a world where the only three lock
 112  * levels are EX, PR, and NL. It *will* have to be adjusted when more
 113  * lock types are added. */
 114 static inline int user_highest_compat_lock_level(int level)
 115 {
 116         int new_level = LKM_EXMODE;
 117
 118         if (level == LKM_EXMODE)
 119                 new_level = LKM_NLMODE;
 120         else if (level == LKM_PRMODE)
 121                 new_level = LKM_PRMODE;
 122         return new_level;
 123 }
 124
 125 static void user_ast(void *opaque)
 126 {
 127         struct user_lock_res *lockres = opaque;
 128         struct dlm_lockstatus *lksb;
 129
 130         mlog(0, "AST fired for lockres %s\n", lockres->l_name);
 131
 132         spin_lock(&lockres->l_lock);
 133
 134         lksb = &(lockres->l_lksb);
 135         if (lksb->status != DLM_NORMAL) {
 136                 mlog(ML_ERROR, "lksb status value of %u on lockres %s\n",
 137                      lksb->status, lockres->l_name);
 138                 spin_unlock(&lockres->l_lock);
 139                 return;
 140         }
 141
 142         /* we're downconverting. */
 143         if (lockres->l_requested < lockres->l_level) {
 144                 if (lockres->l_requested <=
 145                     user_highest_compat_lock_level(lockres->l_blocking)) {
 146                         lockres->l_blocking = LKM_NLMODE;
 147                         lockres->l_flags &= ~USER_LOCK_BLOCKED;
 148                 }
 149         }
 150
 151         lockres->l_level = lockres->l_requested;
 152         lockres->l_requested = LKM_IVMODE;
 153         lockres->l_flags |= USER_LOCK_ATTACHED;
 154         lockres->l_flags &= ~USER_LOCK_BUSY;
 155
 156         spin_unlock(&lockres->l_lock);
 157
 158         wake_up(&lockres->l_event);
 159 }
 160
 161 static inline void user_dlm_grab_inode_ref(struct user_lock_res *lockres)
 162 {
 163         struct inode *inode;
 164         inode = user_dlm_inode_from_user_lockres(lockres);
 165         if (!igrab(inode))
 166                 BUG();
 167 }
 168
 169 static void user_dlm_unblock_lock(void *opaque);
 170
 171 static void __user_dlm_queue_lockres(struct user_lock_res *lockres)
 172 {
 173         if (!(lockres->l_flags & USER_LOCK_QUEUED)) {
 174                 user_dlm_grab_inode_ref(lockres);
 175
 176                 INIT_WORK(&lockres->l_work, user_dlm_unblock_lock,
 177                           lockres);
 178
 179                 queue_work(user_dlm_worker, &lockres->l_work);
 180                 lockres->l_flags |= USER_LOCK_QUEUED;
 181         }
 182 }
 183
 184 static void __user_dlm_cond_queue_lockres(struct user_lock_res *lockres)
 185 {
 186         int queue = 0;
 187
 188         if (!(lockres->l_flags & USER_LOCK_BLOCKED))
 189                 return;
 190
 191         switch (lockres->l_blocking) {
 192         case LKM_EXMODE:
 193                 if (!lockres->l_ex_holders && !lockres->l_ro_holders)
 194                         queue = 1;
 195                 break;
 196         case LKM_PRMODE:
 197                 if (!lockres->l_ex_holders)
 198                         queue = 1;
 199                 break;
 200         default:
 201                 BUG();
 202         }
 203
 204         if (queue)
 205                 __user_dlm_queue_lockres(lockres);
 206 }
 207
 208 static void user_bast(void *opaque, int level)
 209 {
 210         struct user_lock_res *lockres = opaque;
 211
 212         mlog(0, "Blocking AST fired for lockres %s. Blocking level %d\n",
 213                 lockres->l_name, level);
 214
 215         spin_lock(&lockres->l_lock);
 216         lockres->l_flags |= USER_LOCK_BLOCKED;
 217         if (level > lockres->l_blocking)
 218                 lockres->l_blocking = level;
 219
 220         __user_dlm_queue_lockres(lockres);
 221         spin_unlock(&lockres->l_lock);
 222
 223         wake_up(&lockres->l_event);
 224 }
 225
 226 static void user_unlock_ast(void *opaque, enum dlm_status status)
 227 {
 228         struct user_lock_res *lockres = opaque;
 229
 230         mlog(0, "UNLOCK AST called on lock %s\n", lockres->l_name);
 231
 232         if (status != DLM_NORMAL)
 233                 mlog(ML_ERROR, "Dlm returns status %d\n", status);
 234
 235         spin_lock(&lockres->l_lock);
 236         if (lockres->l_flags & USER_LOCK_IN_TEARDOWN)
 237                 lockres->l_level = LKM_IVMODE;
 238         else {
 239                 lockres->l_requested = LKM_IVMODE; /* cancel an
 240                                                     * upconvert
 241                                                     * request. */
 242                 lockres->l_flags &= ~USER_LOCK_IN_CANCEL;
 243                 /* we want the unblock thread to look at it again
 244                  * now. */
 245                 __user_dlm_queue_lockres(lockres);
 246         }
 247
 248         lockres->l_flags &= ~USER_LOCK_BUSY;
 249         spin_unlock(&lockres->l_lock);
 250
 251         wake_up(&lockres->l_event);
 252 }
 253
 254 static inline void user_dlm_drop_inode_ref(struct user_lock_res *lockres)
 255 {
 256         struct inode *inode;
 257         inode = user_dlm_inode_from_user_lockres(lockres);
 258         iput(inode);
 259 }
 260
 261 static void user_dlm_unblock_lock(void *opaque)
 262 {
 263         int new_level, status;
 264         struct user_lock_res *lockres = (struct user_lock_res *) opaque;
 265         struct dlm_ctxt *dlm = dlm_ctxt_from_user_lockres(lockres);
 266
 267         mlog(0, "processing lockres %s\n", lockres->l_name);
 268
 269         spin_lock(&lockres->l_lock);
 270
 271         mlog_bug_on_msg(!(lockres->l_flags & USER_LOCK_QUEUED),
 272                         "Lockres %s, flags 0x%x\n",
 273                         lockres->l_name, lockres->l_flags);
 274
 275         /* notice that we don't clear USER_LOCK_BLOCKED here. If it's
 276          * set, we want user_ast clear it. */
 277         lockres->l_flags &= ~USER_LOCK_QUEUED;
 278
 279         /* It's valid to get here and no longer be blocked - if we get
 280          * several basts in a row, we might be queued by the first
 281          * one, the unblock thread might run and clear the queued
 282          * flag, and finally we might get another bast which re-queues
 283          * us before our ast for the downconvert is called. */
 284         if (!(lockres->l_flags & USER_LOCK_BLOCKED)) {
 285                 mlog(0, "Lockres %s, flags 0x%x: queued but not blocking\n",
 286                         lockres->l_name, lockres->l_flags);
 287                 spin_unlock(&lockres->l_lock);
 288                 goto drop_ref;
 289         }
 290
 291         if (lockres->l_flags & USER_LOCK_IN_TEARDOWN) {
 292                 mlog(0, "lock is in teardown so we do nothing\n");
 293                 spin_unlock(&lockres->l_lock);
 294                 goto drop_ref;
 295         }
 296
 297         if (lockres->l_flags & USER_LOCK_BUSY) {
 298                 mlog(0, "BUSY flag detected...\n");
 299                 if (lockres->l_flags & USER_LOCK_IN_CANCEL) {
 300                         spin_unlock(&lockres->l_lock);
 301                         goto drop_ref;
 302                 }
 303
 304                 lockres->l_flags |= USER_LOCK_IN_CANCEL;
 305                 spin_unlock(&lockres->l_lock);
 306
 307                 status = dlmunlock(dlm,
 308                                    &lockres->l_lksb,
 309                                    LKM_CANCEL,
 310                                    user_unlock_ast,
 311                                    lockres);
 312                 if (status == DLM_CANCELGRANT) {
 313                         /* If we got this, then the ast was fired
 314                          * before we could cancel. We cleanup our
 315                          * state, and restart the function. */
 316                         spin_lock(&lockres->l_lock);
 317                         lockres->l_flags &= ~USER_LOCK_IN_CANCEL;
 318                         spin_unlock(&lockres->l_lock);
 319                 } else if (status != DLM_NORMAL)
 320                         user_log_dlm_error("dlmunlock", status, lockres);
 321                 goto drop_ref;
 322         }
 323
 324         /* If there are still incompat holders, we can exit safely
 325          * without worrying about re-queueing this lock as that will
 326          * happen on the last call to user_cluster_unlock. */
 327         if ((lockres->l_blocking == LKM_EXMODE)
 328             && (lockres->l_ex_holders || lockres->l_ro_holders)) {
 329                 spin_unlock(&lockres->l_lock);
 330                 mlog(0, "can't downconvert for ex: ro = %u, ex = %u\n",
 331                         lockres->l_ro_holders, lockres->l_ex_holders);
 332                 goto drop_ref;
 333         }
 334
 335         if ((lockres->l_blocking == LKM_PRMODE)
 336             && lockres->l_ex_holders) {
 337                 spin_unlock(&lockres->l_lock);
 338                 mlog(0, "can't downconvert for pr: ex = %u\n",
 339                         lockres->l_ex_holders);
 340                 goto drop_ref;
 341         }
 342
 343         /* yay, we can downconvert now. */
 344         new_level = user_highest_compat_lock_level(lockres->l_blocking);
 345         lockres->l_requested = new_level;
 346         lockres->l_flags |= USER_LOCK_BUSY;
 347         mlog(0, "Downconvert lock from %d to %d\n",
 348                 lockres->l_level, new_level);
 349         spin_unlock(&lockres->l_lock);
 350
 351         /* need lock downconvert request now... */
 352         status = dlmlock(dlm,
 353                          new_level,
 354                          &lockres->l_lksb,
 355                          LKM_CONVERT|LKM_VALBLK,
 356                          lockres->l_name,
 357                          user_ast,
 358                          lockres,
 359                          user_bast);
 360         if (status != DLM_NORMAL) {
 361                 user_log_dlm_error("dlmlock", status, lockres);
 362                 user_recover_from_dlm_error(lockres);
 363         }
 364
 365 drop_ref:
 366         user_dlm_drop_inode_ref(lockres);
 367 }
 368
 369 static inline void user_dlm_inc_holders(struct user_lock_res *lockres,
 370                                         int level)
 371 {
 372         switch(level) {
 373         case LKM_EXMODE:
 374                 lockres->l_ex_holders++;
 375                 break;
 376         case LKM_PRMODE:
 377                 lockres->l_ro_holders++;
 378                 break;
 379         default:
 380                 BUG();
 381         }
 382 }
 383
 384 /* predict what lock level we'll be dropping down to on behalf
 385  * of another node, and return true if the currently wanted
 386  * level will be compatible with it. */
 387 static inline int
 388 user_may_continue_on_blocked_lock(struct user_lock_res *lockres,
 389                                   int wanted)
 390 {
 391         BUG_ON(!(lockres->l_flags & USER_LOCK_BLOCKED));
 392
 393         return wanted <= user_highest_compat_lock_level(lockres->l_blocking);
 394 }
 395
 396 int user_dlm_cluster_lock(struct user_lock_res *lockres,
 397                           int level,
 398                           int lkm_flags)
 399 {
 400         int status, local_flags;
 401         struct dlm_ctxt *dlm = dlm_ctxt_from_user_lockres(lockres);
 402
 403         if (level != LKM_EXMODE &&
 404             level != LKM_PRMODE) {
 405                 mlog(ML_ERROR, "lockres %s: invalid request!\n",
 406                      lockres->l_name);
 407                 status = -EINVAL;
 408                 goto bail;
 409         }
 410
 411         mlog(0, "lockres %s: asking for %s lock, passed flags = 0x%x\n",
 412                 lockres->l_name,
 413                 (level == LKM_EXMODE) ? "LKM_EXMODE" : "LKM_PRMODE",
 414                 lkm_flags);
 415
 416 again:
 417         if (signal_pending(current)) {
 418                 status = -ERESTARTSYS;
 419                 goto bail;
 420         }
 421
 422         spin_lock(&lockres->l_lock);
 423
 424         /* We only compare against the currently granted level
 425          * here. If the lock is blocked waiting on a downconvert,
 426          * we'll get caught below. */
 427         if ((lockres->l_flags & USER_LOCK_BUSY) &&
 428             (level > lockres->l_level)) {
 429                 /* is someone sitting in dlm_lock? If so, wait on
 430                  * them. */
 431                 spin_unlock(&lockres->l_lock);
 432
 433                 user_wait_on_busy_lock(lockres);
 434                 goto again;
 435         }
 436
 437         if ((lockres->l_flags & USER_LOCK_BLOCKED) &&
 438             (!user_may_continue_on_blocked_lock(lockres, level))) {
 439                 /* is the lock is currently blocked on behalf of
 440                  * another node */
 441                 spin_unlock(&lockres->l_lock);
 442
 443                 user_wait_on_blocked_lock(lockres);
 444                 goto again;
 445         }
 446
 447         if (level > lockres->l_level) {
 448                 local_flags = lkm_flags | LKM_VALBLK;
 449                 if (lockres->l_level != LKM_IVMODE)
 450                         local_flags |= LKM_CONVERT;
 451
 452                 lockres->l_requested = level;
 453                 lockres->l_flags |= USER_LOCK_BUSY;
 454                 spin_unlock(&lockres->l_lock);
 455
 456                 BUG_ON(level == LKM_IVMODE);
 457                 BUG_ON(level == LKM_NLMODE);
 458
 459                 mlog(0, "lock %s, get lock from %d to level = %d\n",
 460                         lockres->l_name, lockres->l_level, level);
 461
 462                 /* call dlm_lock to upgrade lock now */
 463                 status = dlmlock(dlm,
 464                                  level,
 465                                  &lockres->l_lksb,
 466                                  local_flags,
 467                                  lockres->l_name,
 468                                  user_ast,
 469                                  lockres,
 470                                  user_bast);
 471                 if (status != DLM_NORMAL) {
 472                         if ((lkm_flags & LKM_NOQUEUE) &&
 473                             (status == DLM_NOTQUEUED))
 474                                 status = -EAGAIN;
 475                         else {
 476                                 user_log_dlm_error("dlmlock", status, lockres);
 477                                 status = -EINVAL;
 478                         }
 479                         user_recover_from_dlm_error(lockres);
 480                         goto bail;
 481                 }
 482
 483                 mlog(0, "lock %s, successfull return from dlmlock\n",
 484                         lockres->l_name);
 485
 486                 user_wait_on_busy_lock(lockres);
 487                 goto again;
 488         }
 489
 490         user_dlm_inc_holders(lockres, level);
 491         spin_unlock(&lockres->l_lock);
 492
 493         mlog(0, "lockres %s: Got %s lock!\n", lockres->l_name,
 494                 (level == LKM_EXMODE) ? "LKM_EXMODE" : "LKM_PRMODE");
 495
 496         status = 0;
 497 bail:
 498         return status;
 499 }
 500
 501 static inline void user_dlm_dec_holders(struct user_lock_res *lockres,
 502                                         int level)
 503 {
 504         switch(level) {
 505         case LKM_EXMODE:
 506                 BUG_ON(!lockres->l_ex_holders);
 507                 lockres->l_ex_holders--;
 508                 break;
 509         case LKM_PRMODE:
 510                 BUG_ON(!lockres->l_ro_holders);
 511                 lockres->l_ro_holders--;
 512                 break;
 513         default:
 514                 BUG();
 515         }
 516 }
 517
 518 void user_dlm_cluster_unlock(struct user_lock_res *lockres,
 519                              int level)
 520 {
 521         if (level != LKM_EXMODE &&
 522             level != LKM_PRMODE) {
 523                 mlog(ML_ERROR, "lockres %s: invalid request!\n", lockres->l_name);
 524                 return;
 525         }
 526
 527         mlog(0, "lockres %s: dropping %s lock\n", lockres->l_name,
 528                 (level == LKM_EXMODE) ? "LKM_EXMODE" : "LKM_PRMODE");
 529
 530         spin_lock(&lockres->l_lock);
 531         user_dlm_dec_holders(lockres, level);
 532         __user_dlm_cond_queue_lockres(lockres);
 533         spin_unlock(&lockres->l_lock);
 534 }
 535
 536 void user_dlm_write_lvb(struct inode *inode,
 537                         const char *val,
 538                         unsigned int len)
 539 {
 540         struct user_lock_res *lockres = &DLMFS_I(inode)->ip_lockres;
 541         char *lvb = lockres->l_lksb.lvb;
 542
 543         BUG_ON(len > DLM_LVB_LEN);
 544
 545         spin_lock(&lockres->l_lock);
 546
 547         BUG_ON(lockres->l_level < LKM_EXMODE);
 548         memcpy(lvb, val, len);
 549
 550         spin_unlock(&lockres->l_lock);
 551 }
 552
 553 void user_dlm_read_lvb(struct inode *inode,
 554                        char *val,
 555                        unsigned int len)
 556 {
 557         struct user_lock_res *lockres = &DLMFS_I(inode)->ip_lockres;
 558         char *lvb = lockres->l_lksb.lvb;
 559
 560         BUG_ON(len > DLM_LVB_LEN);
 561
 562         spin_lock(&lockres->l_lock);
 563
 564         BUG_ON(lockres->l_level < LKM_PRMODE);
 565         memcpy(val, lvb, len);
 566
 567         spin_unlock(&lockres->l_lock);
 568 }
 569
 570 void user_dlm_lock_res_init(struct user_lock_res *lockres,
 571                             struct dentry *dentry)
 572 {
 573         memset(lockres, 0, sizeof(*lockres));
 574
 575         spin_lock_init(&lockres->l_lock);
 576         init_waitqueue_head(&lockres->l_event);
 577         lockres->l_level = LKM_IVMODE;
 578         lockres->l_requested = LKM_IVMODE;
 579         lockres->l_blocking = LKM_IVMODE;
 580
 581         /* should have been checked before getting here. */
 582         BUG_ON(dentry->d_name.len >= USER_DLM_LOCK_ID_MAX_LEN);
 583
 584         memcpy(lockres->l_name,
 585                dentry->d_name.name,
 586                dentry->d_name.len);
 587 }
 588
 589 int user_dlm_destroy_lock(struct user_lock_res *lockres)
 590 {
 591         int status = -EBUSY;
 592         struct dlm_ctxt *dlm = dlm_ctxt_from_user_lockres(lockres);
 593
 594         mlog(0, "asked to destroy %s\n", lockres->l_name);
 595
 596         spin_lock(&lockres->l_lock);
 597         while (lockres->l_flags & USER_LOCK_BUSY) {
 598                 spin_unlock(&lockres->l_lock);
 599
 600                 mlog(0, "lock %s is busy\n", lockres->l_name);
 601
 602                 user_wait_on_busy_lock(lockres);
 603
 604                 spin_lock(&lockres->l_lock);
 605         }
 606
 607         if (lockres->l_ro_holders || lockres->l_ex_holders) {
 608                 spin_unlock(&lockres->l_lock);
 609                 mlog(0, "lock %s has holders\n", lockres->l_name);
 610                 goto bail;
 611         }
 612
 613         status = 0;
 614         if (!(lockres->l_flags & USER_LOCK_ATTACHED)) {
 615                 spin_unlock(&lockres->l_lock);
 616                 mlog(0, "lock %s is not attached\n", lockres->l_name);
 617                 goto bail;
 618         }
 619
 620         lockres->l_flags &= ~USER_LOCK_ATTACHED;
 621         lockres->l_flags |= USER_LOCK_BUSY;
 622         lockres->l_flags |= USER_LOCK_IN_TEARDOWN;
 623         spin_unlock(&lockres->l_lock);
 624
 625         mlog(0, "unlocking lockres %s\n", lockres->l_name);
 626         status = dlmunlock(dlm,
 627                            &lockres->l_lksb,
 628                            LKM_VALBLK,
 629                            user_unlock_ast,
 630                            lockres);
 631         if (status != DLM_NORMAL) {
 632                 user_log_dlm_error("dlmunlock", status, lockres);
 633                 status = -EINVAL;
 634                 goto bail;
 635         }
 636
 637         user_wait_on_busy_lock(lockres);
 638
 639         status = 0;
 640 bail:
 641         return status;
 642 }
 643
 644 struct dlm_ctxt *user_dlm_register_context(struct qstr *name)
 645 {
 646         struct dlm_ctxt *dlm;
 647         u32 dlm_key;
 648         char *domain;
 649
 650         domain = kmalloc(name->len + 1, GFP_KERNEL);
 651         if (!domain) {
 652                 mlog_errno(-ENOMEM);
 653                 return ERR_PTR(-ENOMEM);
 654         }
 655
 656         dlm_key = crc32_le(0, name->name, name->len);
 657
 658         snprintf(domain, name->len + 1, "%.*s", name->len, name->name);
 659
 660         dlm = dlm_register_domain(domain, dlm_key);
 661         if (IS_ERR(dlm))
 662                 mlog_errno(PTR_ERR(dlm));
 663
 664         kfree(domain);
 665         return dlm;
 666 }
 667
 668 void user_dlm_unregister_context(struct dlm_ctxt *dlm)
 669 {
 670         dlm_unregister_domain(dlm);
 671 }