git.oblomov.eu Git - linux-2.6/blob - 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         /* The teardown flag gets set early during the unlock process,
 241          * so test the cancel flag to make sure that this ast isn't
 242          * for a concurrent cancel. */
 243         if (lockres->l_flags & USER_LOCK_IN_TEARDOWN
 244             && !(lockres->l_flags & USER_LOCK_IN_CANCEL)) {
 245                 lockres->l_level = LKM_IVMODE;
 246         } else if (status == DLM_CANCELGRANT) {
 247                 mlog(0, "Lock %s, cancel fails, flags 0x%x\n",
 248                      lockres->l_name, lockres->l_flags);
 249                 /* We tried to cancel a convert request, but it was
 250                  * already granted. Don't clear the busy flag - the
 251                  * ast should've done this already. */
 252                 BUG_ON(!(lockres->l_flags & USER_LOCK_IN_CANCEL));
 253                 lockres->l_flags &= ~USER_LOCK_IN_CANCEL;
 254                 goto out_noclear;
 255         } else {
 256                 BUG_ON(!(lockres->l_flags & USER_LOCK_IN_CANCEL));
 257                 /* Cancel succeeded, we want to re-queue */
 258                 mlog(0, "Lock %s, cancel succeeds, flags 0x%x\n",
 259                      lockres->l_name, lockres->l_flags);
 260                 lockres->l_requested = LKM_IVMODE; /* cancel an
 261                                                     * upconvert
 262                                                     * request. */
 263                 lockres->l_flags &= ~USER_LOCK_IN_CANCEL;
 264                 /* we want the unblock thread to look at it again
 265                  * now. */
 266                 if (lockres->l_flags & USER_LOCK_BLOCKED)
 267                         __user_dlm_queue_lockres(lockres);
 268         }
 269
 270         lockres->l_flags &= ~USER_LOCK_BUSY;
 271 out_noclear:
 272         spin_unlock(&lockres->l_lock);
 273
 274         wake_up(&lockres->l_event);
 275 }
 276
 277 static inline void user_dlm_drop_inode_ref(struct user_lock_res *lockres)
 278 {
 279         struct inode *inode;
 280         inode = user_dlm_inode_from_user_lockres(lockres);
 281         iput(inode);
 282 }
 283
 284 static void user_dlm_unblock_lock(void *opaque)
 285 {
 286         int new_level, status;
 287         struct user_lock_res *lockres = (struct user_lock_res *) opaque;
 288         struct dlm_ctxt *dlm = dlm_ctxt_from_user_lockres(lockres);
 289
 290         mlog(0, "processing lockres %s\n", lockres->l_name);
 291
 292         spin_lock(&lockres->l_lock);
 293
 294         mlog_bug_on_msg(!(lockres->l_flags & USER_LOCK_QUEUED),
 295                         "Lockres %s, flags 0x%x\n",
 296                         lockres->l_name, lockres->l_flags);
 297
 298         /* notice that we don't clear USER_LOCK_BLOCKED here. If it's
 299          * set, we want user_ast clear it. */
 300         lockres->l_flags &= ~USER_LOCK_QUEUED;
 301
 302         /* It's valid to get here and no longer be blocked - if we get
 303          * several basts in a row, we might be queued by the first
 304          * one, the unblock thread might run and clear the queued
 305          * flag, and finally we might get another bast which re-queues
 306          * us before our ast for the downconvert is called. */
 307         if (!(lockres->l_flags & USER_LOCK_BLOCKED)) {
 308                 mlog(0, "Lockres %s, flags 0x%x: queued but not blocking\n",
 309                         lockres->l_name, lockres->l_flags);
 310                 spin_unlock(&lockres->l_lock);
 311                 goto drop_ref;
 312         }
 313
 314         if (lockres->l_flags & USER_LOCK_IN_TEARDOWN) {
 315                 mlog(0, "lock is in teardown so we do nothing\n");
 316                 spin_unlock(&lockres->l_lock);
 317                 goto drop_ref;
 318         }
 319
 320         if (lockres->l_flags & USER_LOCK_BUSY) {
 321                 mlog(0, "Cancel lock %s, flags 0x%x\n",
 322                      lockres->l_name, lockres->l_flags);
 323
 324                 if (lockres->l_flags & USER_LOCK_IN_CANCEL) {
 325                         spin_unlock(&lockres->l_lock);
 326                         goto drop_ref;
 327                 }
 328
 329                 lockres->l_flags |= USER_LOCK_IN_CANCEL;
 330                 spin_unlock(&lockres->l_lock);
 331
 332                 status = dlmunlock(dlm,
 333                                    &lockres->l_lksb,
 334                                    LKM_CANCEL,
 335                                    user_unlock_ast,
 336                                    lockres);
 337                 if (status != DLM_NORMAL)
 338                         user_log_dlm_error("dlmunlock", status, lockres);
 339                 goto drop_ref;
 340         }
 341
 342         /* If there are still incompat holders, we can exit safely
 343          * without worrying about re-queueing this lock as that will
 344          * happen on the last call to user_cluster_unlock. */
 345         if ((lockres->l_blocking == LKM_EXMODE)
 346             && (lockres->l_ex_holders || lockres->l_ro_holders)) {
 347                 spin_unlock(&lockres->l_lock);
 348                 mlog(0, "can't downconvert for ex: ro = %u, ex = %u\n",
 349                         lockres->l_ro_holders, lockres->l_ex_holders);
 350                 goto drop_ref;
 351         }
 352
 353         if ((lockres->l_blocking == LKM_PRMODE)
 354             && lockres->l_ex_holders) {
 355                 spin_unlock(&lockres->l_lock);
 356                 mlog(0, "can't downconvert for pr: ex = %u\n",
 357                         lockres->l_ex_holders);
 358                 goto drop_ref;
 359         }
 360
 361         /* yay, we can downconvert now. */
 362         new_level = user_highest_compat_lock_level(lockres->l_blocking);
 363         lockres->l_requested = new_level;
 364         lockres->l_flags |= USER_LOCK_BUSY;
 365         mlog(0, "Downconvert lock from %d to %d\n",
 366                 lockres->l_level, new_level);
 367         spin_unlock(&lockres->l_lock);
 368
 369         /* need lock downconvert request now... */
 370         status = dlmlock(dlm,
 371                          new_level,
 372                          &lockres->l_lksb,
 373                          LKM_CONVERT|LKM_VALBLK,
 374                          lockres->l_name,
 375                          user_ast,
 376                          lockres,
 377                          user_bast);
 378         if (status != DLM_NORMAL) {
 379                 user_log_dlm_error("dlmlock", status, lockres);
 380                 user_recover_from_dlm_error(lockres);
 381         }
 382
 383 drop_ref:
 384         user_dlm_drop_inode_ref(lockres);
 385 }
 386
 387 static inline void user_dlm_inc_holders(struct user_lock_res *lockres,
 388                                         int level)
 389 {
 390         switch(level) {
 391         case LKM_EXMODE:
 392                 lockres->l_ex_holders++;
 393                 break;
 394         case LKM_PRMODE:
 395                 lockres->l_ro_holders++;
 396                 break;
 397         default:
 398                 BUG();
 399         }
 400 }
 401
 402 /* predict what lock level we'll be dropping down to on behalf
 403  * of another node, and return true if the currently wanted
 404  * level will be compatible with it. */
 405 static inline int
 406 user_may_continue_on_blocked_lock(struct user_lock_res *lockres,
 407                                   int wanted)
 408 {
 409         BUG_ON(!(lockres->l_flags & USER_LOCK_BLOCKED));
 410
 411         return wanted <= user_highest_compat_lock_level(lockres->l_blocking);
 412 }
 413
 414 int user_dlm_cluster_lock(struct user_lock_res *lockres,
 415                           int level,
 416                           int lkm_flags)
 417 {
 418         int status, local_flags;
 419         struct dlm_ctxt *dlm = dlm_ctxt_from_user_lockres(lockres);
 420
 421         if (level != LKM_EXMODE &&
 422             level != LKM_PRMODE) {
 423                 mlog(ML_ERROR, "lockres %s: invalid request!\n",
 424                      lockres->l_name);
 425                 status = -EINVAL;
 426                 goto bail;
 427         }
 428
 429         mlog(0, "lockres %s: asking for %s lock, passed flags = 0x%x\n",
 430                 lockres->l_name,
 431                 (level == LKM_EXMODE) ? "LKM_EXMODE" : "LKM_PRMODE",
 432                 lkm_flags);
 433
 434 again:
 435         if (signal_pending(current)) {
 436                 status = -ERESTARTSYS;
 437                 goto bail;
 438         }
 439
 440         spin_lock(&lockres->l_lock);
 441
 442         /* We only compare against the currently granted level
 443          * here. If the lock is blocked waiting on a downconvert,
 444          * we'll get caught below. */
 445         if ((lockres->l_flags & USER_LOCK_BUSY) &&
 446             (level > lockres->l_level)) {
 447                 /* is someone sitting in dlm_lock? If so, wait on
 448                  * them. */
 449                 spin_unlock(&lockres->l_lock);
 450
 451                 user_wait_on_busy_lock(lockres);
 452                 goto again;
 453         }
 454
 455         if ((lockres->l_flags & USER_LOCK_BLOCKED) &&
 456             (!user_may_continue_on_blocked_lock(lockres, level))) {
 457                 /* is the lock is currently blocked on behalf of
 458                  * another node */
 459                 spin_unlock(&lockres->l_lock);
 460
 461                 user_wait_on_blocked_lock(lockres);
 462                 goto again;
 463         }
 464
 465         if (level > lockres->l_level) {
 466                 local_flags = lkm_flags | LKM_VALBLK;
 467                 if (lockres->l_level != LKM_IVMODE)
 468                         local_flags |= LKM_CONVERT;
 469
 470                 lockres->l_requested = level;
 471                 lockres->l_flags |= USER_LOCK_BUSY;
 472                 spin_unlock(&lockres->l_lock);
 473
 474                 BUG_ON(level == LKM_IVMODE);
 475                 BUG_ON(level == LKM_NLMODE);
 476
 477                 mlog(0, "lock %s, get lock from %d to level = %d\n",
 478                         lockres->l_name, lockres->l_level, level);
 479
 480                 /* call dlm_lock to upgrade lock now */
 481                 status = dlmlock(dlm,
 482                                  level,
 483                                  &lockres->l_lksb,
 484                                  local_flags,
 485                                  lockres->l_name,
 486                                  user_ast,
 487                                  lockres,
 488                                  user_bast);
 489                 if (status != DLM_NORMAL) {
 490                         if ((lkm_flags & LKM_NOQUEUE) &&
 491                             (status == DLM_NOTQUEUED))
 492                                 status = -EAGAIN;
 493                         else {
 494                                 user_log_dlm_error("dlmlock", status, lockres);
 495                                 status = -EINVAL;
 496                         }
 497                         user_recover_from_dlm_error(lockres);
 498                         goto bail;
 499                 }
 500
 501                 mlog(0, "lock %s, successfull return from dlmlock\n",
 502                         lockres->l_name);
 503
 504                 user_wait_on_busy_lock(lockres);
 505                 goto again;
 506         }
 507
 508         user_dlm_inc_holders(lockres, level);
 509         spin_unlock(&lockres->l_lock);
 510
 511         mlog(0, "lockres %s: Got %s lock!\n", lockres->l_name,
 512                 (level == LKM_EXMODE) ? "LKM_EXMODE" : "LKM_PRMODE");
 513
 514         status = 0;
 515 bail:
 516         return status;
 517 }
 518
 519 static inline void user_dlm_dec_holders(struct user_lock_res *lockres,
 520                                         int level)
 521 {
 522         switch(level) {
 523         case LKM_EXMODE:
 524                 BUG_ON(!lockres->l_ex_holders);
 525                 lockres->l_ex_holders--;
 526                 break;
 527         case LKM_PRMODE:
 528                 BUG_ON(!lockres->l_ro_holders);
 529                 lockres->l_ro_holders--;
 530                 break;
 531         default:
 532                 BUG();
 533         }
 534 }
 535
 536 void user_dlm_cluster_unlock(struct user_lock_res *lockres,
 537                              int level)
 538 {
 539         if (level != LKM_EXMODE &&
 540             level != LKM_PRMODE) {
 541                 mlog(ML_ERROR, "lockres %s: invalid request!\n", lockres->l_name);
 542                 return;
 543         }
 544
 545         mlog(0, "lockres %s: dropping %s lock\n", lockres->l_name,
 546                 (level == LKM_EXMODE) ? "LKM_EXMODE" : "LKM_PRMODE");
 547
 548         spin_lock(&lockres->l_lock);
 549         user_dlm_dec_holders(lockres, level);
 550         __user_dlm_cond_queue_lockres(lockres);
 551         spin_unlock(&lockres->l_lock);
 552 }
 553
 554 void user_dlm_write_lvb(struct inode *inode,
 555                         const char *val,
 556                         unsigned int len)
 557 {
 558         struct user_lock_res *lockres = &DLMFS_I(inode)->ip_lockres;
 559         char *lvb = lockres->l_lksb.lvb;
 560
 561         BUG_ON(len > DLM_LVB_LEN);
 562
 563         spin_lock(&lockres->l_lock);
 564
 565         BUG_ON(lockres->l_level < LKM_EXMODE);
 566         memcpy(lvb, val, len);
 567
 568         spin_unlock(&lockres->l_lock);
 569 }
 570
 571 void user_dlm_read_lvb(struct inode *inode,
 572                        char *val,
 573                        unsigned int len)
 574 {
 575         struct user_lock_res *lockres = &DLMFS_I(inode)->ip_lockres;
 576         char *lvb = lockres->l_lksb.lvb;
 577
 578         BUG_ON(len > DLM_LVB_LEN);
 579
 580         spin_lock(&lockres->l_lock);
 581
 582         BUG_ON(lockres->l_level < LKM_PRMODE);
 583         memcpy(val, lvb, len);
 584
 585         spin_unlock(&lockres->l_lock);
 586 }
 587
 588 void user_dlm_lock_res_init(struct user_lock_res *lockres,
 589                             struct dentry *dentry)
 590 {
 591         memset(lockres, 0, sizeof(*lockres));
 592
 593         spin_lock_init(&lockres->l_lock);
 594         init_waitqueue_head(&lockres->l_event);
 595         lockres->l_level = LKM_IVMODE;
 596         lockres->l_requested = LKM_IVMODE;
 597         lockres->l_blocking = LKM_IVMODE;
 598
 599         /* should have been checked before getting here. */
 600         BUG_ON(dentry->d_name.len >= USER_DLM_LOCK_ID_MAX_LEN);
 601
 602         memcpy(lockres->l_name,
 603                dentry->d_name.name,
 604                dentry->d_name.len);
 605 }
 606
 607 int user_dlm_destroy_lock(struct user_lock_res *lockres)
 608 {
 609         int status = -EBUSY;
 610         struct dlm_ctxt *dlm = dlm_ctxt_from_user_lockres(lockres);
 611
 612         mlog(0, "asked to destroy %s\n", lockres->l_name);
 613
 614         spin_lock(&lockres->l_lock);
 615         if (lockres->l_flags & USER_LOCK_IN_TEARDOWN) {
 616                 mlog(0, "Lock is already torn down\n");
 617                 spin_unlock(&lockres->l_lock);
 618                 return 0;
 619         }
 620
 621         lockres->l_flags |= USER_LOCK_IN_TEARDOWN;
 622
 623         while (lockres->l_flags & USER_LOCK_BUSY) {
 624                 spin_unlock(&lockres->l_lock);
 625
 626                 mlog(0, "lock %s is busy\n", lockres->l_name);
 627
 628                 user_wait_on_busy_lock(lockres);
 629
 630                 spin_lock(&lockres->l_lock);
 631         }
 632
 633         if (lockres->l_ro_holders || lockres->l_ex_holders) {
 634                 spin_unlock(&lockres->l_lock);
 635                 mlog(0, "lock %s has holders\n", lockres->l_name);
 636                 goto bail;
 637         }
 638
 639         status = 0;
 640         if (!(lockres->l_flags & USER_LOCK_ATTACHED)) {
 641                 spin_unlock(&lockres->l_lock);
 642                 mlog(0, "lock %s is not attached\n", lockres->l_name);
 643                 goto bail;
 644         }
 645
 646         lockres->l_flags &= ~USER_LOCK_ATTACHED;
 647         lockres->l_flags |= USER_LOCK_BUSY;
 648         spin_unlock(&lockres->l_lock);
 649
 650         mlog(0, "unlocking lockres %s\n", lockres->l_name);
 651         status = dlmunlock(dlm,
 652                            &lockres->l_lksb,
 653                            LKM_VALBLK,
 654                            user_unlock_ast,
 655                            lockres);
 656         if (status != DLM_NORMAL) {
 657                 user_log_dlm_error("dlmunlock", status, lockres);
 658                 status = -EINVAL;
 659                 goto bail;
 660         }
 661
 662         user_wait_on_busy_lock(lockres);
 663
 664         status = 0;
 665 bail:
 666         return status;
 667 }
 668
 669 struct dlm_ctxt *user_dlm_register_context(struct qstr *name)
 670 {
 671         struct dlm_ctxt *dlm;
 672         u32 dlm_key;
 673         char *domain;
 674
 675         domain = kmalloc(name->len + 1, GFP_NOFS);
 676         if (!domain) {
 677                 mlog_errno(-ENOMEM);
 678                 return ERR_PTR(-ENOMEM);
 679         }
 680
 681         dlm_key = crc32_le(0, name->name, name->len);
 682
 683         snprintf(domain, name->len + 1, "%.*s", name->len, name->name);
 684
 685         dlm = dlm_register_domain(domain, dlm_key);
 686         if (IS_ERR(dlm))
 687                 mlog_errno(PTR_ERR(dlm));
 688
 689         kfree(domain);
 690         return dlm;
 691 }
 692
 693 void user_dlm_unregister_context(struct dlm_ctxt *dlm)
 694 {
 695         dlm_unregister_domain(dlm);
 696 }