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         mlog_bug_on_msg(lockres->l_requested == LKM_IVMODE,
 143                         "Lockres %s, requested ivmode. flags 0x%x\n",
 144                         lockres->l_name, lockres->l_flags);
 145
 146         /* we're downconverting. */
 147         if (lockres->l_requested < lockres->l_level) {
 148                 if (lockres->l_requested <=
 149                     user_highest_compat_lock_level(lockres->l_blocking)) {
 150                         lockres->l_blocking = LKM_NLMODE;
 151                         lockres->l_flags &= ~USER_LOCK_BLOCKED;
 152                 }
 153         }
 154
 155         lockres->l_level = lockres->l_requested;
 156         lockres->l_requested = LKM_IVMODE;
 157         lockres->l_flags |= USER_LOCK_ATTACHED;
 158         lockres->l_flags &= ~USER_LOCK_BUSY;
 159
 160         spin_unlock(&lockres->l_lock);
 161
 162         wake_up(&lockres->l_event);
 163 }
 164
 165 static inline void user_dlm_grab_inode_ref(struct user_lock_res *lockres)
 166 {
 167         struct inode *inode;
 168         inode = user_dlm_inode_from_user_lockres(lockres);
 169         if (!igrab(inode))
 170                 BUG();
 171 }
 172
 173 static void user_dlm_unblock_lock(void *opaque);
 174
 175 static void __user_dlm_queue_lockres(struct user_lock_res *lockres)
 176 {
 177         if (!(lockres->l_flags & USER_LOCK_QUEUED)) {
 178                 user_dlm_grab_inode_ref(lockres);
 179
 180                 INIT_WORK(&lockres->l_work, user_dlm_unblock_lock,
 181                           lockres);
 182
 183                 queue_work(user_dlm_worker, &lockres->l_work);
 184                 lockres->l_flags |= USER_LOCK_QUEUED;
 185         }
 186 }
 187
 188 static void __user_dlm_cond_queue_lockres(struct user_lock_res *lockres)
 189 {
 190         int queue = 0;
 191
 192         if (!(lockres->l_flags & USER_LOCK_BLOCKED))
 193                 return;
 194
 195         switch (lockres->l_blocking) {
 196         case LKM_EXMODE:
 197                 if (!lockres->l_ex_holders && !lockres->l_ro_holders)
 198                         queue = 1;
 199                 break;
 200         case LKM_PRMODE:
 201                 if (!lockres->l_ex_holders)
 202                         queue = 1;
 203                 break;
 204         default:
 205                 BUG();
 206         }
 207
 208         if (queue)
 209                 __user_dlm_queue_lockres(lockres);
 210 }
 211
 212 static void user_bast(void *opaque, int level)
 213 {
 214         struct user_lock_res *lockres = opaque;
 215
 216         mlog(0, "Blocking AST fired for lockres %s. Blocking level %d\n",
 217                 lockres->l_name, level);
 218
 219         spin_lock(&lockres->l_lock);
 220         lockres->l_flags |= USER_LOCK_BLOCKED;
 221         if (level > lockres->l_blocking)
 222                 lockres->l_blocking = level;
 223
 224         __user_dlm_queue_lockres(lockres);
 225         spin_unlock(&lockres->l_lock);
 226
 227         wake_up(&lockres->l_event);
 228 }
 229
 230 static void user_unlock_ast(void *opaque, enum dlm_status status)
 231 {
 232         struct user_lock_res *lockres = opaque;
 233
 234         mlog(0, "UNLOCK AST called on lock %s\n", lockres->l_name);
 235
 236         if (status != DLM_NORMAL && status != DLM_CANCELGRANT)
 237                 mlog(ML_ERROR, "Dlm returns status %d\n", status);
 238
 239         spin_lock(&lockres->l_lock);
 240         if (lockres->l_flags & USER_LOCK_IN_TEARDOWN)
 241                 lockres->l_level = LKM_IVMODE;
 242         else if (status == DLM_CANCELGRANT) {
 243                 mlog(0, "Lock %s, cancel fails, flags 0x%x\n",
 244                      lockres->l_name, lockres->l_flags);
 245                 /* We tried to cancel a convert request, but it was
 246                  * already granted. Don't clear the busy flag - the
 247                  * ast should've done this already. */
 248                 BUG_ON(!(lockres->l_flags & USER_LOCK_IN_CANCEL));
 249                 lockres->l_flags &= ~USER_LOCK_IN_CANCEL;
 250                 goto out_noclear;
 251         } else {
 252                 BUG_ON(!(lockres->l_flags & USER_LOCK_IN_CANCEL));
 253                 /* Cancel succeeded, we want to re-queue */
 254                 mlog(0, "Lock %s, cancel succeeds, flags 0x%x\n",
 255                      lockres->l_name, lockres->l_flags);
 256                 lockres->l_requested = LKM_IVMODE; /* cancel an
 257                                                     * upconvert
 258                                                     * request. */
 259                 lockres->l_flags &= ~USER_LOCK_IN_CANCEL;
 260                 /* we want the unblock thread to look at it again
 261                  * now. */
 262                 if (lockres->l_flags & USER_LOCK_BLOCKED)
 263                         __user_dlm_queue_lockres(lockres);
 264         }
 265
 266         lockres->l_flags &= ~USER_LOCK_BUSY;
 267 out_noclear:
 268         spin_unlock(&lockres->l_lock);
 269
 270         wake_up(&lockres->l_event);
 271 }
 272
 273 static inline void user_dlm_drop_inode_ref(struct user_lock_res *lockres)
 274 {
 275         struct inode *inode;
 276         inode = user_dlm_inode_from_user_lockres(lockres);
 277         iput(inode);
 278 }
 279
 280 static void user_dlm_unblock_lock(void *opaque)
 281 {
 282         int new_level, status;
 283         struct user_lock_res *lockres = (struct user_lock_res *) opaque;
 284         struct dlm_ctxt *dlm = dlm_ctxt_from_user_lockres(lockres);
 285
 286         mlog(0, "processing lockres %s\n", lockres->l_name);
 287
 288         spin_lock(&lockres->l_lock);
 289
 290         mlog_bug_on_msg(!(lockres->l_flags & USER_LOCK_QUEUED),
 291                         "Lockres %s, flags 0x%x\n",
 292                         lockres->l_name, lockres->l_flags);
 293
 294         /* notice that we don't clear USER_LOCK_BLOCKED here. If it's
 295          * set, we want user_ast clear it. */
 296         lockres->l_flags &= ~USER_LOCK_QUEUED;
 297
 298         /* It's valid to get here and no longer be blocked - if we get
 299          * several basts in a row, we might be queued by the first
 300          * one, the unblock thread might run and clear the queued
 301          * flag, and finally we might get another bast which re-queues
 302          * us before our ast for the downconvert is called. */
 303         if (!(lockres->l_flags & USER_LOCK_BLOCKED)) {
 304                 mlog(0, "Lockres %s, flags 0x%x: queued but not blocking\n",
 305                         lockres->l_name, lockres->l_flags);
 306                 spin_unlock(&lockres->l_lock);
 307                 goto drop_ref;
 308         }
 309
 310         if (lockres->l_flags & USER_LOCK_IN_TEARDOWN) {
 311                 mlog(0, "lock is in teardown so we do nothing\n");
 312                 spin_unlock(&lockres->l_lock);
 313                 goto drop_ref;
 314         }
 315
 316         if (lockres->l_flags & USER_LOCK_BUSY) {
 317                 mlog(0, "Cancel lock %s, flags 0x%x\n",
 318                      lockres->l_name, lockres->l_flags);
 319
 320                 if (lockres->l_flags & USER_LOCK_IN_CANCEL) {
 321                         spin_unlock(&lockres->l_lock);
 322                         goto drop_ref;
 323                 }
 324
 325                 lockres->l_flags |= USER_LOCK_IN_CANCEL;
 326                 spin_unlock(&lockres->l_lock);
 327
 328                 status = dlmunlock(dlm,
 329                                    &lockres->l_lksb,
 330                                    LKM_CANCEL,
 331                                    user_unlock_ast,
 332                                    lockres);
 333                 if (status != DLM_NORMAL)
 334                         user_log_dlm_error("dlmunlock", status, lockres);
 335                 goto drop_ref;
 336         }
 337
 338         /* If there are still incompat holders, we can exit safely
 339          * without worrying about re-queueing this lock as that will
 340          * happen on the last call to user_cluster_unlock. */
 341         if ((lockres->l_blocking == LKM_EXMODE)
 342             && (lockres->l_ex_holders || lockres->l_ro_holders)) {
 343                 spin_unlock(&lockres->l_lock);
 344                 mlog(0, "can't downconvert for ex: ro = %u, ex = %u\n",
 345                         lockres->l_ro_holders, lockres->l_ex_holders);
 346                 goto drop_ref;
 347         }
 348
 349         if ((lockres->l_blocking == LKM_PRMODE)
 350             && lockres->l_ex_holders) {
 351                 spin_unlock(&lockres->l_lock);
 352                 mlog(0, "can't downconvert for pr: ex = %u\n",
 353                         lockres->l_ex_holders);
 354                 goto drop_ref;
 355         }
 356
 357         /* yay, we can downconvert now. */
 358         new_level = user_highest_compat_lock_level(lockres->l_blocking);
 359         lockres->l_requested = new_level;
 360         lockres->l_flags |= USER_LOCK_BUSY;
 361         mlog(0, "Downconvert lock from %d to %d\n",
 362                 lockres->l_level, new_level);
 363         spin_unlock(&lockres->l_lock);
 364
 365         /* need lock downconvert request now... */
 366         status = dlmlock(dlm,
 367                          new_level,
 368                          &lockres->l_lksb,
 369                          LKM_CONVERT|LKM_VALBLK,
 370                          lockres->l_name,
 371                          user_ast,
 372                          lockres,
 373                          user_bast);
 374         if (status != DLM_NORMAL) {
 375                 user_log_dlm_error("dlmlock", status, lockres);
 376                 user_recover_from_dlm_error(lockres);
 377         }
 378
 379 drop_ref:
 380         user_dlm_drop_inode_ref(lockres);
 381 }
 382
 383 static inline void user_dlm_inc_holders(struct user_lock_res *lockres,
 384                                         int level)
 385 {
 386         switch(level) {
 387         case LKM_EXMODE:
 388                 lockres->l_ex_holders++;
 389                 break;
 390         case LKM_PRMODE:
 391                 lockres->l_ro_holders++;
 392                 break;
 393         default:
 394                 BUG();
 395         }
 396 }
 397
 398 /* predict what lock level we'll be dropping down to on behalf
 399  * of another node, and return true if the currently wanted
 400  * level will be compatible with it. */
 401 static inline int
 402 user_may_continue_on_blocked_lock(struct user_lock_res *lockres,
 403                                   int wanted)
 404 {
 405         BUG_ON(!(lockres->l_flags & USER_LOCK_BLOCKED));
 406
 407         return wanted <= user_highest_compat_lock_level(lockres->l_blocking);
 408 }
 409
 410 int user_dlm_cluster_lock(struct user_lock_res *lockres,
 411                           int level,
 412                           int lkm_flags)
 413 {
 414         int status, local_flags;
 415         struct dlm_ctxt *dlm = dlm_ctxt_from_user_lockres(lockres);
 416
 417         if (level != LKM_EXMODE &&
 418             level != LKM_PRMODE) {
 419                 mlog(ML_ERROR, "lockres %s: invalid request!\n",
 420                      lockres->l_name);
 421                 status = -EINVAL;
 422                 goto bail;
 423         }
 424
 425         mlog(0, "lockres %s: asking for %s lock, passed flags = 0x%x\n",
 426                 lockres->l_name,
 427                 (level == LKM_EXMODE) ? "LKM_EXMODE" : "LKM_PRMODE",
 428                 lkm_flags);
 429
 430 again:
 431         if (signal_pending(current)) {
 432                 status = -ERESTARTSYS;
 433                 goto bail;
 434         }
 435
 436         spin_lock(&lockres->l_lock);
 437
 438         /* We only compare against the currently granted level
 439          * here. If the lock is blocked waiting on a downconvert,
 440          * we'll get caught below. */
 441         if ((lockres->l_flags & USER_LOCK_BUSY) &&
 442             (level > lockres->l_level)) {
 443                 /* is someone sitting in dlm_lock? If so, wait on
 444                  * them. */
 445                 spin_unlock(&lockres->l_lock);
 446
 447                 user_wait_on_busy_lock(lockres);
 448                 goto again;
 449         }
 450
 451         if ((lockres->l_flags & USER_LOCK_BLOCKED) &&
 452             (!user_may_continue_on_blocked_lock(lockres, level))) {
 453                 /* is the lock is currently blocked on behalf of
 454                  * another node */
 455                 spin_unlock(&lockres->l_lock);
 456
 457                 user_wait_on_blocked_lock(lockres);
 458                 goto again;
 459         }
 460
 461         if (level > lockres->l_level) {
 462                 local_flags = lkm_flags | LKM_VALBLK;
 463                 if (lockres->l_level != LKM_IVMODE)
 464                         local_flags |= LKM_CONVERT;
 465
 466                 lockres->l_requested = level;
 467                 lockres->l_flags |= USER_LOCK_BUSY;
 468                 spin_unlock(&lockres->l_lock);
 469
 470                 BUG_ON(level == LKM_IVMODE);
 471                 BUG_ON(level == LKM_NLMODE);
 472
 473                 mlog(0, "lock %s, get lock from %d to level = %d\n",
 474                         lockres->l_name, lockres->l_level, level);
 475
 476                 /* call dlm_lock to upgrade lock now */
 477                 status = dlmlock(dlm,
 478                                  level,
 479                                  &lockres->l_lksb,
 480                                  local_flags,
 481                                  lockres->l_name,
 482                                  user_ast,
 483                                  lockres,
 484                                  user_bast);
 485                 if (status != DLM_NORMAL) {
 486                         if ((lkm_flags & LKM_NOQUEUE) &&
 487                             (status == DLM_NOTQUEUED))
 488                                 status = -EAGAIN;
 489                         else {
 490                                 user_log_dlm_error("dlmlock", status, lockres);
 491                                 status = -EINVAL;
 492                         }
 493                         user_recover_from_dlm_error(lockres);
 494                         goto bail;
 495                 }
 496
 497                 mlog(0, "lock %s, successfull return from dlmlock\n",
 498                         lockres->l_name);
 499
 500                 user_wait_on_busy_lock(lockres);
 501                 goto again;
 502         }
 503
 504         user_dlm_inc_holders(lockres, level);
 505         spin_unlock(&lockres->l_lock);
 506
 507         mlog(0, "lockres %s: Got %s lock!\n", lockres->l_name,
 508                 (level == LKM_EXMODE) ? "LKM_EXMODE" : "LKM_PRMODE");
 509
 510         status = 0;
 511 bail:
 512         return status;
 513 }
 514
 515 static inline void user_dlm_dec_holders(struct user_lock_res *lockres,
 516                                         int level)
 517 {
 518         switch(level) {
 519         case LKM_EXMODE:
 520                 BUG_ON(!lockres->l_ex_holders);
 521                 lockres->l_ex_holders--;
 522                 break;
 523         case LKM_PRMODE:
 524                 BUG_ON(!lockres->l_ro_holders);
 525                 lockres->l_ro_holders--;
 526                 break;
 527         default:
 528                 BUG();
 529         }
 530 }
 531
 532 void user_dlm_cluster_unlock(struct user_lock_res *lockres,
 533                              int level)
 534 {
 535         if (level != LKM_EXMODE &&
 536             level != LKM_PRMODE) {
 537                 mlog(ML_ERROR, "lockres %s: invalid request!\n", lockres->l_name);
 538                 return;
 539         }
 540
 541         mlog(0, "lockres %s: dropping %s lock\n", lockres->l_name,
 542                 (level == LKM_EXMODE) ? "LKM_EXMODE" : "LKM_PRMODE");
 543
 544         spin_lock(&lockres->l_lock);
 545         user_dlm_dec_holders(lockres, level);
 546         __user_dlm_cond_queue_lockres(lockres);
 547         spin_unlock(&lockres->l_lock);
 548 }
 549
 550 void user_dlm_write_lvb(struct inode *inode,
 551                         const char *val,
 552                         unsigned int len)
 553 {
 554         struct user_lock_res *lockres = &DLMFS_I(inode)->ip_lockres;
 555         char *lvb = lockres->l_lksb.lvb;
 556
 557         BUG_ON(len > DLM_LVB_LEN);
 558
 559         spin_lock(&lockres->l_lock);
 560
 561         BUG_ON(lockres->l_level < LKM_EXMODE);
 562         memcpy(lvb, val, len);
 563
 564         spin_unlock(&lockres->l_lock);
 565 }
 566
 567 void user_dlm_read_lvb(struct inode *inode,
 568                        char *val,
 569                        unsigned int len)
 570 {
 571         struct user_lock_res *lockres = &DLMFS_I(inode)->ip_lockres;
 572         char *lvb = lockres->l_lksb.lvb;
 573
 574         BUG_ON(len > DLM_LVB_LEN);
 575
 576         spin_lock(&lockres->l_lock);
 577
 578         BUG_ON(lockres->l_level < LKM_PRMODE);
 579         memcpy(val, lvb, len);
 580
 581         spin_unlock(&lockres->l_lock);
 582 }
 583
 584 void user_dlm_lock_res_init(struct user_lock_res *lockres,
 585                             struct dentry *dentry)
 586 {
 587         memset(lockres, 0, sizeof(*lockres));
 588
 589         spin_lock_init(&lockres->l_lock);
 590         init_waitqueue_head(&lockres->l_event);
 591         lockres->l_level = LKM_IVMODE;
 592         lockres->l_requested = LKM_IVMODE;
 593         lockres->l_blocking = LKM_IVMODE;
 594
 595         /* should have been checked before getting here. */
 596         BUG_ON(dentry->d_name.len >= USER_DLM_LOCK_ID_MAX_LEN);
 597
 598         memcpy(lockres->l_name,
 599                dentry->d_name.name,
 600                dentry->d_name.len);
 601 }
 602
 603 int user_dlm_destroy_lock(struct user_lock_res *lockres)
 604 {
 605         int status = -EBUSY;
 606         struct dlm_ctxt *dlm = dlm_ctxt_from_user_lockres(lockres);
 607
 608         mlog(0, "asked to destroy %s\n", lockres->l_name);
 609
 610         spin_lock(&lockres->l_lock);
 611         while (lockres->l_flags & USER_LOCK_BUSY) {
 612                 spin_unlock(&lockres->l_lock);
 613
 614                 mlog(0, "lock %s is busy\n", lockres->l_name);
 615
 616                 user_wait_on_busy_lock(lockres);
 617
 618                 spin_lock(&lockres->l_lock);
 619         }
 620
 621         if (lockres->l_ro_holders || lockres->l_ex_holders) {
 622                 spin_unlock(&lockres->l_lock);
 623                 mlog(0, "lock %s has holders\n", lockres->l_name);
 624                 goto bail;
 625         }
 626
 627         status = 0;
 628         if (!(lockres->l_flags & USER_LOCK_ATTACHED)) {
 629                 spin_unlock(&lockres->l_lock);
 630                 mlog(0, "lock %s is not attached\n", lockres->l_name);
 631                 goto bail;
 632         }
 633
 634         lockres->l_flags &= ~USER_LOCK_ATTACHED;
 635         lockres->l_flags |= USER_LOCK_BUSY;
 636         lockres->l_flags |= USER_LOCK_IN_TEARDOWN;
 637         spin_unlock(&lockres->l_lock);
 638
 639         mlog(0, "unlocking lockres %s\n", lockres->l_name);
 640         status = dlmunlock(dlm,
 641                            &lockres->l_lksb,
 642                            LKM_VALBLK,
 643                            user_unlock_ast,
 644                            lockres);
 645         if (status != DLM_NORMAL) {
 646                 user_log_dlm_error("dlmunlock", status, lockres);
 647                 status = -EINVAL;
 648                 goto bail;
 649         }
 650
 651         user_wait_on_busy_lock(lockres);
 652
 653         status = 0;
 654 bail:
 655         return status;
 656 }
 657
 658 struct dlm_ctxt *user_dlm_register_context(struct qstr *name)
 659 {
 660         struct dlm_ctxt *dlm;
 661         u32 dlm_key;
 662         char *domain;
 663
 664         domain = kmalloc(name->len + 1, GFP_KERNEL);
 665         if (!domain) {
 666                 mlog_errno(-ENOMEM);
 667                 return ERR_PTR(-ENOMEM);
 668         }
 669
 670         dlm_key = crc32_le(0, name->name, name->len);
 671
 672         snprintf(domain, name->len + 1, "%.*s", name->len, name->name);
 673
 674         dlm = dlm_register_domain(domain, dlm_key);
 675         if (IS_ERR(dlm))
 676                 mlog_errno(PTR_ERR(dlm));
 677
 678         kfree(domain);
 679         return dlm;
 680 }
 681
 682 void user_dlm_unregister_context(struct dlm_ctxt *dlm)
 683 {
 684         dlm_unregister_domain(dlm);
 685 }