fs/ocfs2/dlmfs/userdlm.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * userdlm.c
   4  *
   5  * Code which implements the kernel side of a minimal userspace
   6  * interface to our DLM.
   7  *
   8  * Many of the functions here are pared down versions of dlmglue.c
   9  * functions.
  10  *
  11  * Copyright (C) 2003, 2004 Oracle.  All rights reserved.
  12  */
  13
  14 #include <linux/signal.h>
  15 #include <linux/sched/signal.h>
  16
  17 #include <linux/module.h>
  18 #include <linux/fs.h>
  19 #include <linux/types.h>
  20 #include <linux/crc32.h>
  21
  22 #include "../ocfs2_lockingver.h"
  23 #include "../stackglue.h"
  24 #include "userdlm.h"
  25
  26 #define MLOG_MASK_PREFIX ML_DLMFS
  27 #include "../cluster/masklog.h"
  28
  29
  30 static inline struct user_lock_res *user_lksb_to_lock_res(struct ocfs2_dlm_lksb *lksb)
  31 {
  32         return container_of(lksb, struct user_lock_res, l_lksb);
  33 }
  34
  35 static inline int user_check_wait_flag(struct user_lock_res *lockres,
  36                                        int flag)
  37 {
  38         int ret;
  39
  40         spin_lock(&lockres->l_lock);
  41         ret = lockres->l_flags & flag;
  42         spin_unlock(&lockres->l_lock);
  43
  44         return ret;
  45 }
  46
  47 static inline void user_wait_on_busy_lock(struct user_lock_res *lockres)
  48
  49 {
  50         wait_event(lockres->l_event,
  51                    !user_check_wait_flag(lockres, USER_LOCK_BUSY));
  52 }
  53
  54 static inline void user_wait_on_blocked_lock(struct user_lock_res *lockres)
  55
  56 {
  57         wait_event(lockres->l_event,
  58                    !user_check_wait_flag(lockres, USER_LOCK_BLOCKED));
  59 }
  60
  61 /* I heart container_of... */
  62 static inline struct ocfs2_cluster_connection *
  63 cluster_connection_from_user_lockres(struct user_lock_res *lockres)
  64 {
  65         struct dlmfs_inode_private *ip;
  66
  67         ip = container_of(lockres,
  68                           struct dlmfs_inode_private,
  69                           ip_lockres);
  70         return ip->ip_conn;
  71 }
  72
  73 static struct inode *
  74 user_dlm_inode_from_user_lockres(struct user_lock_res *lockres)
  75 {
  76         struct dlmfs_inode_private *ip;
  77
  78         ip = container_of(lockres,
  79                           struct dlmfs_inode_private,
  80                           ip_lockres);
  81         return &ip->ip_vfs_inode;
  82 }
  83
  84 static inline void user_recover_from_dlm_error(struct user_lock_res *lockres)
  85 {
  86         spin_lock(&lockres->l_lock);
  87         lockres->l_flags &= ~USER_LOCK_BUSY;
  88         spin_unlock(&lockres->l_lock);
  89 }
  90
  91 #define user_log_dlm_error(_func, _stat, _lockres) do {                 \
  92         mlog(ML_ERROR, "Dlm error %d while calling %s on "              \
  93                 "resource %.*s\n", _stat, _func,                        \
  94                 _lockres->l_namelen, _lockres->l_name);                 \
  95 } while (0)
  96
  97 /* WARNING: This function lives in a world where the only three lock
  98  * levels are EX, PR, and NL. It *will* have to be adjusted when more
  99  * lock types are added. */
 100 static inline int user_highest_compat_lock_level(int level)
 101 {
 102         int new_level = DLM_LOCK_EX;
 103
 104         if (level == DLM_LOCK_EX)
 105                 new_level = DLM_LOCK_NL;
 106         else if (level == DLM_LOCK_PR)
 107                 new_level = DLM_LOCK_PR;
 108         return new_level;
 109 }
 110
 111 static void user_ast(struct ocfs2_dlm_lksb *lksb)
 112 {
 113         struct user_lock_res *lockres = user_lksb_to_lock_res(lksb);
 114         int status;
 115
 116         mlog(ML_BASTS, "AST fired for lockres %.*s, level %d => %d\n",
 117              lockres->l_namelen, lockres->l_name, lockres->l_level,
 118              lockres->l_requested);
 119
 120         spin_lock(&lockres->l_lock);
 121
 122         status = ocfs2_dlm_lock_status(&lockres->l_lksb);
 123         if (status) {
 124                 mlog(ML_ERROR, "lksb status value of %u on lockres %.*s\n",
 125                      status, lockres->l_namelen, lockres->l_name);
 126                 spin_unlock(&lockres->l_lock);
 127                 return;
 128         }
 129
 130         mlog_bug_on_msg(lockres->l_requested == DLM_LOCK_IV,
 131                         "Lockres %.*s, requested ivmode. flags 0x%x\n",
 132                         lockres->l_namelen, lockres->l_name, lockres->l_flags);
 133
 134         /* we're downconverting. */
 135         if (lockres->l_requested < lockres->l_level) {
 136                 if (lockres->l_requested <=
 137                     user_highest_compat_lock_level(lockres->l_blocking)) {
 138                         lockres->l_blocking = DLM_LOCK_NL;
 139                         lockres->l_flags &= ~USER_LOCK_BLOCKED;
 140                 }
 141         }
 142
 143         lockres->l_level = lockres->l_requested;
 144         lockres->l_requested = DLM_LOCK_IV;
 145         lockres->l_flags |= USER_LOCK_ATTACHED;
 146         lockres->l_flags &= ~USER_LOCK_BUSY;
 147
 148         spin_unlock(&lockres->l_lock);
 149
 150         wake_up(&lockres->l_event);
 151 }
 152
 153 static inline void user_dlm_grab_inode_ref(struct user_lock_res *lockres)
 154 {
 155         struct inode *inode;
 156         inode = user_dlm_inode_from_user_lockres(lockres);
 157         if (!igrab(inode))
 158                 BUG();
 159 }
 160
 161 static void user_dlm_unblock_lock(struct work_struct *work);
 162
 163 static void __user_dlm_queue_lockres(struct user_lock_res *lockres)
 164 {
 165         if (!(lockres->l_flags & USER_LOCK_QUEUED)) {
 166                 user_dlm_grab_inode_ref(lockres);
 167
 168                 INIT_WORK(&lockres->l_work, user_dlm_unblock_lock);
 169
 170                 queue_work(user_dlm_worker, &lockres->l_work);
 171                 lockres->l_flags |= USER_LOCK_QUEUED;
 172         }
 173 }
 174
 175 static void __user_dlm_cond_queue_lockres(struct user_lock_res *lockres)
 176 {
 177         int queue = 0;
 178
 179         if (!(lockres->l_flags & USER_LOCK_BLOCKED))
 180                 return;
 181
 182         switch (lockres->l_blocking) {
 183         case DLM_LOCK_EX:
 184                 if (!lockres->l_ex_holders && !lockres->l_ro_holders)
 185                         queue = 1;
 186                 break;
 187         case DLM_LOCK_PR:
 188                 if (!lockres->l_ex_holders)
 189                         queue = 1;
 190                 break;
 191         default:
 192                 BUG();
 193         }
 194
 195         if (queue)
 196                 __user_dlm_queue_lockres(lockres);
 197 }
 198
 199 static void user_bast(struct ocfs2_dlm_lksb *lksb, int level)
 200 {
 201         struct user_lock_res *lockres = user_lksb_to_lock_res(lksb);
 202
 203         mlog(ML_BASTS, "BAST fired for lockres %.*s, blocking %d, level %d\n",
 204              lockres->l_namelen, lockres->l_name, level, lockres->l_level);
 205
 206         spin_lock(&lockres->l_lock);
 207         lockres->l_flags |= USER_LOCK_BLOCKED;
 208         if (level > lockres->l_blocking)
 209                 lockres->l_blocking = level;
 210
 211         __user_dlm_queue_lockres(lockres);
 212         spin_unlock(&lockres->l_lock);
 213
 214         wake_up(&lockres->l_event);
 215 }
 216
 217 static void user_unlock_ast(struct ocfs2_dlm_lksb *lksb, int status)
 218 {
 219         struct user_lock_res *lockres = user_lksb_to_lock_res(lksb);
 220
 221         mlog(ML_BASTS, "UNLOCK AST fired for lockres %.*s, flags 0x%x\n",
 222              lockres->l_namelen, lockres->l_name, lockres->l_flags);
 223
 224         if (status)
 225                 mlog(ML_ERROR, "dlm returns status %d\n", status);
 226
 227         spin_lock(&lockres->l_lock);
 228         /* The teardown flag gets set early during the unlock process,
 229          * so test the cancel flag to make sure that this ast isn't
 230          * for a concurrent cancel. */
 231         if (lockres->l_flags & USER_LOCK_IN_TEARDOWN
 232             && !(lockres->l_flags & USER_LOCK_IN_CANCEL)) {
 233                 lockres->l_level = DLM_LOCK_IV;
 234         } else if (status == DLM_CANCELGRANT) {
 235                 /* We tried to cancel a convert request, but it was
 236                  * already granted. Don't clear the busy flag - the
 237                  * ast should've done this already. */
 238                 BUG_ON(!(lockres->l_flags & USER_LOCK_IN_CANCEL));
 239                 lockres->l_flags &= ~USER_LOCK_IN_CANCEL;
 240                 goto out_noclear;
 241         } else {
 242                 BUG_ON(!(lockres->l_flags & USER_LOCK_IN_CANCEL));
 243                 /* Cancel succeeded, we want to re-queue */
 244                 lockres->l_requested = DLM_LOCK_IV; /* cancel an
 245                                                     * upconvert
 246                                                     * request. */
 247                 lockres->l_flags &= ~USER_LOCK_IN_CANCEL;
 248                 /* we want the unblock thread to look at it again
 249                  * now. */
 250                 if (lockres->l_flags & USER_LOCK_BLOCKED)
 251                         __user_dlm_queue_lockres(lockres);
 252         }
 253
 254         lockres->l_flags &= ~USER_LOCK_BUSY;
 255 out_noclear:
 256         spin_unlock(&lockres->l_lock);
 257
 258         wake_up(&lockres->l_event);
 259 }
 260
 261 /*
 262  * This is the userdlmfs locking protocol version.
 263  *
 264  * See fs/ocfs2/dlmglue.c for more details on locking versions.
 265  */
 266 static struct ocfs2_locking_protocol user_dlm_lproto = {
 267         .lp_max_version = {
 268                 .pv_major = OCFS2_LOCKING_PROTOCOL_MAJOR,
 269                 .pv_minor = OCFS2_LOCKING_PROTOCOL_MINOR,
 270         },
 271         .lp_lock_ast            = user_ast,
 272         .lp_blocking_ast        = user_bast,
 273         .lp_unlock_ast          = user_unlock_ast,
 274 };
 275
 276 static inline void user_dlm_drop_inode_ref(struct user_lock_res *lockres)
 277 {
 278         struct inode *inode;
 279         inode = user_dlm_inode_from_user_lockres(lockres);
 280         iput(inode);
 281 }
 282
 283 static void user_dlm_unblock_lock(struct work_struct *work)
 284 {
 285         int new_level, status;
 286         struct user_lock_res *lockres =
 287                 container_of(work, struct user_lock_res, l_work);
 288         struct ocfs2_cluster_connection *conn =
 289                 cluster_connection_from_user_lockres(lockres);
 290
 291         mlog(0, "lockres %.*s\n", lockres->l_namelen, lockres->l_name);
 292
 293         spin_lock(&lockres->l_lock);
 294
 295         mlog_bug_on_msg(!(lockres->l_flags & USER_LOCK_QUEUED),
 296                         "Lockres %.*s, flags 0x%x\n",
 297                         lockres->l_namelen, lockres->l_name, lockres->l_flags);
 298
 299         /* notice that we don't clear USER_LOCK_BLOCKED here. If it's
 300          * set, we want user_ast clear it. */
 301         lockres->l_flags &= ~USER_LOCK_QUEUED;
 302
 303         /* It's valid to get here and no longer be blocked - if we get
 304          * several basts in a row, we might be queued by the first
 305          * one, the unblock thread might run and clear the queued
 306          * flag, and finally we might get another bast which re-queues
 307          * us before our ast for the downconvert is called. */
 308         if (!(lockres->l_flags & USER_LOCK_BLOCKED)) {
 309                 mlog(ML_BASTS, "lockres %.*s USER_LOCK_BLOCKED\n",
 310                      lockres->l_namelen, lockres->l_name);
 311                 spin_unlock(&lockres->l_lock);
 312                 goto drop_ref;
 313         }
 314
 315         if (lockres->l_flags & USER_LOCK_IN_TEARDOWN) {
 316                 mlog(ML_BASTS, "lockres %.*s USER_LOCK_IN_TEARDOWN\n",
 317                      lockres->l_namelen, lockres->l_name);
 318                 spin_unlock(&lockres->l_lock);
 319                 goto drop_ref;
 320         }
 321
 322         if (lockres->l_flags & USER_LOCK_BUSY) {
 323                 if (lockres->l_flags & USER_LOCK_IN_CANCEL) {
 324                         mlog(ML_BASTS, "lockres %.*s USER_LOCK_IN_CANCEL\n",
 325                              lockres->l_namelen, lockres->l_name);
 326                         spin_unlock(&lockres->l_lock);
 327                         goto drop_ref;
 328                 }
 329
 330                 lockres->l_flags |= USER_LOCK_IN_CANCEL;
 331                 spin_unlock(&lockres->l_lock);
 332
 333                 status = ocfs2_dlm_unlock(conn, &lockres->l_lksb,
 334                                           DLM_LKF_CANCEL);
 335                 if (status)
 336                         user_log_dlm_error("ocfs2_dlm_unlock", status, lockres);
 337                 goto drop_ref;
 338         }
 339
 340         /* If there are still incompat holders, we can exit safely
 341          * without worrying about re-queueing this lock as that will
 342          * happen on the last call to user_cluster_unlock. */
 343         if ((lockres->l_blocking == DLM_LOCK_EX)
 344             && (lockres->l_ex_holders || lockres->l_ro_holders)) {
 345                 spin_unlock(&lockres->l_lock);
 346                 mlog(ML_BASTS, "lockres %.*s, EX/PR Holders %u,%u\n",
 347                      lockres->l_namelen, lockres->l_name,
 348                      lockres->l_ex_holders, lockres->l_ro_holders);
 349                 goto drop_ref;
 350         }
 351
 352         if ((lockres->l_blocking == DLM_LOCK_PR)
 353             && lockres->l_ex_holders) {
 354                 spin_unlock(&lockres->l_lock);
 355                 mlog(ML_BASTS, "lockres %.*s, EX Holders %u\n",
 356                      lockres->l_namelen, lockres->l_name,
 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(ML_BASTS, "lockres %.*s, downconvert %d => %d\n",
 366              lockres->l_namelen, lockres->l_name, lockres->l_level, new_level);
 367         spin_unlock(&lockres->l_lock);
 368
 369         /* need lock downconvert request now... */
 370         status = ocfs2_dlm_lock(conn, new_level, &lockres->l_lksb,
 371                                 DLM_LKF_CONVERT|DLM_LKF_VALBLK,
 372                                 lockres->l_name,
 373                                 lockres->l_namelen);
 374         if (status) {
 375                 user_log_dlm_error("ocfs2_dlm_lock", 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 DLM_LOCK_EX:
 388                 lockres->l_ex_holders++;
 389                 break;
 390         case DLM_LOCK_PR:
 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 ocfs2_cluster_connection *conn =
 416                 cluster_connection_from_user_lockres(lockres);
 417
 418         if (level != DLM_LOCK_EX &&
 419             level != DLM_LOCK_PR) {
 420                 mlog(ML_ERROR, "lockres %.*s: invalid request!\n",
 421                      lockres->l_namelen, lockres->l_name);
 422                 status = -EINVAL;
 423                 goto bail;
 424         }
 425
 426         mlog(ML_BASTS, "lockres %.*s, level %d, flags = 0x%x\n",
 427              lockres->l_namelen, lockres->l_name, level, lkm_flags);
 428
 429 again:
 430         if (signal_pending(current)) {
 431                 status = -ERESTARTSYS;
 432                 goto bail;
 433         }
 434
 435         spin_lock(&lockres->l_lock);
 436         if (lockres->l_flags & USER_LOCK_IN_TEARDOWN) {
 437                 spin_unlock(&lockres->l_lock);
 438                 status = -EAGAIN;
 439                 goto bail;
 440         }
 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 | DLM_LKF_VALBLK;
 467                 if (lockres->l_level != DLM_LOCK_IV)
 468                         local_flags |= DLM_LKF_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 == DLM_LOCK_IV);
 475                 BUG_ON(level == DLM_LOCK_NL);
 476
 477                 /* call dlm_lock to upgrade lock now */
 478                 status = ocfs2_dlm_lock(conn, level, &lockres->l_lksb,
 479                                         local_flags, lockres->l_name,
 480                                         lockres->l_namelen);
 481                 if (status) {
 482                         if ((lkm_flags & DLM_LKF_NOQUEUE) &&
 483                             (status != -EAGAIN))
 484                                 user_log_dlm_error("ocfs2_dlm_lock",
 485                                                    status, lockres);
 486                         user_recover_from_dlm_error(lockres);
 487                         goto bail;
 488                 }
 489
 490                 user_wait_on_busy_lock(lockres);
 491                 goto again;
 492         }
 493
 494         user_dlm_inc_holders(lockres, level);
 495         spin_unlock(&lockres->l_lock);
 496
 497         status = 0;
 498 bail:
 499         return status;
 500 }
 501
 502 static inline void user_dlm_dec_holders(struct user_lock_res *lockres,
 503                                         int level)
 504 {
 505         switch(level) {
 506         case DLM_LOCK_EX:
 507                 BUG_ON(!lockres->l_ex_holders);
 508                 lockres->l_ex_holders--;
 509                 break;
 510         case DLM_LOCK_PR:
 511                 BUG_ON(!lockres->l_ro_holders);
 512                 lockres->l_ro_holders--;
 513                 break;
 514         default:
 515                 BUG();
 516         }
 517 }
 518
 519 void user_dlm_cluster_unlock(struct user_lock_res *lockres,
 520                              int level)
 521 {
 522         if (level != DLM_LOCK_EX &&
 523             level != DLM_LOCK_PR) {
 524                 mlog(ML_ERROR, "lockres %.*s: invalid request!\n",
 525                      lockres->l_namelen, lockres->l_name);
 526                 return;
 527         }
 528
 529         spin_lock(&lockres->l_lock);
 530         user_dlm_dec_holders(lockres, level);
 531         __user_dlm_cond_queue_lockres(lockres);
 532         spin_unlock(&lockres->l_lock);
 533 }
 534
 535 void user_dlm_write_lvb(struct inode *inode,
 536                         const char *val,
 537                         unsigned int len)
 538 {
 539         struct user_lock_res *lockres = &DLMFS_I(inode)->ip_lockres;
 540         char *lvb;
 541
 542         BUG_ON(len > DLM_LVB_LEN);
 543
 544         spin_lock(&lockres->l_lock);
 545
 546         BUG_ON(lockres->l_level < DLM_LOCK_EX);
 547         lvb = ocfs2_dlm_lvb(&lockres->l_lksb);
 548         memcpy(lvb, val, len);
 549
 550         spin_unlock(&lockres->l_lock);
 551 }
 552
 553 bool user_dlm_read_lvb(struct inode *inode, char *val)
 554 {
 555         struct user_lock_res *lockres = &DLMFS_I(inode)->ip_lockres;
 556         char *lvb;
 557         bool ret = true;
 558
 559         spin_lock(&lockres->l_lock);
 560
 561         BUG_ON(lockres->l_level < DLM_LOCK_PR);
 562         if (ocfs2_dlm_lvb_valid(&lockres->l_lksb)) {
 563                 lvb = ocfs2_dlm_lvb(&lockres->l_lksb);
 564                 memcpy(val, lvb, DLM_LVB_LEN);
 565         } else
 566                 ret = false;
 567
 568         spin_unlock(&lockres->l_lock);
 569         return ret;
 570 }
 571
 572 void user_dlm_lock_res_init(struct user_lock_res *lockres,
 573                             struct dentry *dentry)
 574 {
 575         memset(lockres, 0, sizeof(*lockres));
 576
 577         spin_lock_init(&lockres->l_lock);
 578         init_waitqueue_head(&lockres->l_event);
 579         lockres->l_level = DLM_LOCK_IV;
 580         lockres->l_requested = DLM_LOCK_IV;
 581         lockres->l_blocking = DLM_LOCK_IV;
 582
 583         /* should have been checked before getting here. */
 584         BUG_ON(dentry->d_name.len >= USER_DLM_LOCK_ID_MAX_LEN);
 585
 586         memcpy(lockres->l_name,
 587                dentry->d_name.name,
 588                dentry->d_name.len);
 589         lockres->l_namelen = dentry->d_name.len;
 590 }
 591
 592 int user_dlm_destroy_lock(struct user_lock_res *lockres)
 593 {
 594         int status = -EBUSY;
 595         struct ocfs2_cluster_connection *conn =
 596                 cluster_connection_from_user_lockres(lockres);
 597
 598         mlog(ML_BASTS, "lockres %.*s\n", lockres->l_namelen, lockres->l_name);
 599
 600         spin_lock(&lockres->l_lock);
 601         if (lockres->l_flags & USER_LOCK_IN_TEARDOWN) {
 602                 spin_unlock(&lockres->l_lock);
 603                 goto bail;
 604         }
 605
 606         lockres->l_flags |= USER_LOCK_IN_TEARDOWN;
 607
 608         while (lockres->l_flags & USER_LOCK_BUSY) {
 609                 spin_unlock(&lockres->l_lock);
 610
 611                 user_wait_on_busy_lock(lockres);
 612
 613                 spin_lock(&lockres->l_lock);
 614         }
 615
 616         if (lockres->l_ro_holders || lockres->l_ex_holders) {
 617                 lockres->l_flags &= ~USER_LOCK_IN_TEARDOWN;
 618                 spin_unlock(&lockres->l_lock);
 619                 goto bail;
 620         }
 621
 622         status = 0;
 623         if (!(lockres->l_flags & USER_LOCK_ATTACHED)) {
 624                 /*
 625                  * lock is never requested, leave USER_LOCK_IN_TEARDOWN set
 626                  * to avoid new lock request coming in.
 627                  */
 628                 spin_unlock(&lockres->l_lock);
 629                 goto bail;
 630         }
 631
 632         lockres->l_flags |= USER_LOCK_BUSY;
 633         spin_unlock(&lockres->l_lock);
 634
 635         status = ocfs2_dlm_unlock(conn, &lockres->l_lksb, DLM_LKF_VALBLK);
 636         if (status) {
 637                 spin_lock(&lockres->l_lock);
 638                 lockres->l_flags &= ~USER_LOCK_IN_TEARDOWN;
 639                 lockres->l_flags &= ~USER_LOCK_BUSY;
 640                 spin_unlock(&lockres->l_lock);
 641                 user_log_dlm_error("ocfs2_dlm_unlock", status, lockres);
 642                 goto bail;
 643         }
 644
 645         user_wait_on_busy_lock(lockres);
 646
 647         status = 0;
 648 bail:
 649         return status;
 650 }
 651
 652 static void user_dlm_recovery_handler_noop(int node_num,
 653                                            void *recovery_data)
 654 {
 655         /* We ignore recovery events */
 656         return;
 657 }
 658
 659 void user_dlm_set_locking_protocol(void)
 660 {
 661         ocfs2_stack_glue_set_max_proto_version(&user_dlm_lproto.lp_max_version);
 662 }
 663
 664 struct ocfs2_cluster_connection *user_dlm_register(const struct qstr *name)
 665 {
 666         int rc;
 667         struct ocfs2_cluster_connection *conn;
 668
 669         rc = ocfs2_cluster_connect_agnostic(name->name, name->len,
 670                                             &user_dlm_lproto,
 671                                             user_dlm_recovery_handler_noop,
 672                                             NULL, &conn);
 673         if (rc)
 674                 mlog_errno(rc);
 675
 676         return rc ? ERR_PTR(rc) : conn;
 677 }
 678
 679 void user_dlm_unregister(struct ocfs2_cluster_connection *conn)
 680 {
 681         ocfs2_cluster_disconnect(conn, 0);
 682 }