kernel/drivers/staging/lustre/lustre/lov/lov_lock.c

   1 /*
   2  * GPL HEADER START
   3  *
   4  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 only,
   8  * as published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful, but
  11  * WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * General Public License version 2 for more details (a copy is included
  14  * in the LICENSE file that accompanied this code).
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * version 2 along with this program; If not, see
  18  * http://www.sun.com/software/products/lustre/docs/GPLv2.pdf
  19  *
  20  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
  21  * CA 95054 USA or visit www.sun.com if you need additional information or
  22  * have any questions.
  23  *
  24  * GPL HEADER END
  25  */
  26 /*
  27  * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
  28  * Use is subject to license terms.
  29  *
  30  * Copyright (c) 2011, 2012, Intel Corporation.
  31  */
  32 /*
  33  * This file is part of Lustre, http://www.lustre.org/
  34  * Lustre is a trademark of Sun Microsystems, Inc.
  35  *
  36  * Implementation of cl_lock for LOV layer.
  37  *
  38  *   Author: Nikita Danilov <nikita.danilov@sun.com>
  39  */
  40
  41 #define DEBUG_SUBSYSTEM S_LOV
  42
  43 #include "lov_cl_internal.h"
  44
  45 /** \addtogroup lov
  46  *  @{
  47  */
  48
  49 static struct cl_lock_closure *lov_closure_get(const struct lu_env *env,
  50                                                struct cl_lock *parent);
  51
  52 static int lov_lock_unuse(const struct lu_env *env,
  53                           const struct cl_lock_slice *slice);
  54 /*****************************************************************************
  55  *
  56  * Lov lock operations.
  57  *
  58  */
  59
  60 static struct lov_sublock_env *lov_sublock_env_get(const struct lu_env *env,
  61                                                    struct cl_lock *parent,
  62                                                    struct lov_lock_sub *lls)
  63 {
  64         struct lov_sublock_env *subenv;
  65         struct lov_io     *lio    = lov_env_io(env);
  66         struct cl_io       *io     = lio->lis_cl.cis_io;
  67         struct lov_io_sub      *sub;
  68
  69         subenv = &lov_env_session(env)->ls_subenv;
  70
  71         /*
  72          * FIXME: We tend to use the subio's env & io to call the sublock
  73          * lock operations because osc lock sometimes stores some control
  74          * variables in thread's IO information(Now only lockless information).
  75          * However, if the lock's host(object) is different from the object
  76          * for current IO, we have no way to get the subenv and subio because
  77          * they are not initialized at all. As a temp fix, in this case,
  78          * we still borrow the parent's env to call sublock operations.
  79          */
  80         if (!io || !cl_object_same(io->ci_obj, parent->cll_descr.cld_obj)) {
  81                 subenv->lse_env = env;
  82                 subenv->lse_io  = io;
  83                 subenv->lse_sub = NULL;
  84         } else {
  85                 sub = lov_sub_get(env, lio, lls->sub_stripe);
  86                 if (!IS_ERR(sub)) {
  87                         subenv->lse_env = sub->sub_env;
  88                         subenv->lse_io  = sub->sub_io;
  89                         subenv->lse_sub = sub;
  90                 } else {
  91                         subenv = (void *)sub;
  92                 }
  93         }
  94         return subenv;
  95 }
  96
  97 static void lov_sublock_env_put(struct lov_sublock_env *subenv)
  98 {
  99         if (subenv && subenv->lse_sub)
 100                 lov_sub_put(subenv->lse_sub);
 101 }
 102
 103 static void lov_sublock_adopt(const struct lu_env *env, struct lov_lock *lck,
 104                               struct cl_lock *sublock, int idx,
 105                               struct lov_lock_link *link)
 106 {
 107         struct lovsub_lock *lsl;
 108         struct cl_lock     *parent = lck->lls_cl.cls_lock;
 109         int              rc;
 110
 111         LASSERT(cl_lock_is_mutexed(parent));
 112         LASSERT(cl_lock_is_mutexed(sublock));
 113
 114         lsl = cl2sub_lock(sublock);
 115         /*
 116          * check that sub-lock doesn't have lock link to this top-lock.
 117          */
 118         LASSERT(lov_lock_link_find(env, lck, lsl) == NULL);
 119         LASSERT(idx < lck->lls_nr);
 120
 121         lck->lls_sub[idx].sub_lock = lsl;
 122         lck->lls_nr_filled++;
 123         LASSERT(lck->lls_nr_filled <= lck->lls_nr);
 124         list_add_tail(&link->lll_list, &lsl->lss_parents);
 125         link->lll_idx = idx;
 126         link->lll_super = lck;
 127         cl_lock_get(parent);
 128         lu_ref_add(&parent->cll_reference, "lov-child", sublock);
 129         lck->lls_sub[idx].sub_flags |= LSF_HELD;
 130         cl_lock_user_add(env, sublock);
 131
 132         rc = lov_sublock_modify(env, lck, lsl, &sublock->cll_descr, idx);
 133         LASSERT(rc == 0); /* there is no way this can fail, currently */
 134 }
 135
 136 static struct cl_lock *lov_sublock_alloc(const struct lu_env *env,
 137                                          const struct cl_io *io,
 138                                          struct lov_lock *lck,
 139                                          int idx, struct lov_lock_link **out)
 140 {
 141         struct cl_lock       *sublock;
 142         struct cl_lock       *parent;
 143         struct lov_lock_link *link;
 144
 145         LASSERT(idx < lck->lls_nr);
 146
 147         OBD_SLAB_ALLOC_PTR_GFP(link, lov_lock_link_kmem, GFP_NOFS);
 148         if (link != NULL) {
 149                 struct lov_sublock_env *subenv;
 150                 struct lov_lock_sub  *lls;
 151                 struct cl_lock_descr *descr;
 152
 153                 parent = lck->lls_cl.cls_lock;
 154                 lls    = &lck->lls_sub[idx];
 155                 descr  = &lls->sub_got;
 156
 157                 subenv = lov_sublock_env_get(env, parent, lls);
 158                 if (!IS_ERR(subenv)) {
 159                         /* CAVEAT: Don't try to add a field in lov_lock_sub
 160                          * to remember the subio. This is because lock is able
 161                          * to be cached, but this is not true for IO. This
 162                          * further means a sublock might be referenced in
 163                          * different io context. -jay */
 164
 165                         sublock = cl_lock_hold(subenv->lse_env, subenv->lse_io,
 166                                                descr, "lov-parent", parent);
 167                         lov_sublock_env_put(subenv);
 168                 } else {
 169                         /* error occurs. */
 170                         sublock = (void *)subenv;
 171                 }
 172
 173                 if (!IS_ERR(sublock))
 174                         *out = link;
 175                 else
 176                         OBD_SLAB_FREE_PTR(link, lov_lock_link_kmem);
 177         } else
 178                 sublock = ERR_PTR(-ENOMEM);
 179         return sublock;
 180 }
 181
 182 static void lov_sublock_unlock(const struct lu_env *env,
 183                                struct lovsub_lock *lsl,
 184                                struct cl_lock_closure *closure,
 185                                struct lov_sublock_env *subenv)
 186 {
 187         lov_sublock_env_put(subenv);
 188         lsl->lss_active = NULL;
 189         cl_lock_disclosure(env, closure);
 190 }
 191
 192 static int lov_sublock_lock(const struct lu_env *env,
 193                             struct lov_lock *lck,
 194                             struct lov_lock_sub *lls,
 195                             struct cl_lock_closure *closure,
 196                             struct lov_sublock_env **lsep)
 197 {
 198         struct lovsub_lock *sublock;
 199         struct cl_lock     *child;
 200         int              result = 0;
 201
 202         LASSERT(list_empty(&closure->clc_list));
 203
 204         sublock = lls->sub_lock;
 205         child = sublock->lss_cl.cls_lock;
 206         result = cl_lock_closure_build(env, child, closure);
 207         if (result == 0) {
 208                 struct cl_lock *parent = closure->clc_origin;
 209
 210                 LASSERT(cl_lock_is_mutexed(child));
 211                 sublock->lss_active = parent;
 212
 213                 if (unlikely((child->cll_state == CLS_FREEING) ||
 214                              (child->cll_flags & CLF_CANCELLED))) {
 215                         struct lov_lock_link *link;
 216                         /*
 217                          * we could race with lock deletion which temporarily
 218                          * put the lock in freeing state, bug 19080.
 219                          */
 220                         LASSERT(!(lls->sub_flags & LSF_HELD));
 221
 222                         link = lov_lock_link_find(env, lck, sublock);
 223                         LASSERT(link != NULL);
 224                         lov_lock_unlink(env, link, sublock);
 225                         lov_sublock_unlock(env, sublock, closure, NULL);
 226                         lck->lls_cancel_race = 1;
 227                         result = CLO_REPEAT;
 228                 } else if (lsep) {
 229                         struct lov_sublock_env *subenv;
 230                         subenv = lov_sublock_env_get(env, parent, lls);
 231                         if (IS_ERR(subenv)) {
 232                                 lov_sublock_unlock(env, sublock,
 233                                                    closure, NULL);
 234                                 result = PTR_ERR(subenv);
 235                         } else {
 236                                 *lsep = subenv;
 237                         }
 238                 }
 239         }
 240         return result;
 241 }
 242
 243 /**
 244  * Updates the result of a top-lock operation from a result of sub-lock
 245  * sub-operations. Top-operations like lov_lock_{enqueue,use,unuse}() iterate
 246  * over sub-locks and lov_subresult() is used to calculate return value of a
 247  * top-operation. To this end, possible return values of sub-operations are
 248  * ordered as
 249  *
 250  *     - 0                success
 251  *     - CLO_WAIT          wait for event
 252  *     - CLO_REPEAT      repeat top-operation
 253  *     - -ne            fundamental error
 254  *
 255  * Top-level return code can only go down through this list. CLO_REPEAT
 256  * overwrites CLO_WAIT, because lock mutex was released and sleeping condition
 257  * has to be rechecked by the upper layer.
 258  */
 259 static int lov_subresult(int result, int rc)
 260 {
 261         int result_rank;
 262         int rc_rank;
 263
 264         LASSERTF(result <= 0 || result == CLO_REPEAT || result == CLO_WAIT,
 265                  "result = %d", result);
 266         LASSERTF(rc <= 0 || rc == CLO_REPEAT || rc == CLO_WAIT,
 267                  "rc = %d\n", rc);
 268         CLASSERT(CLO_WAIT < CLO_REPEAT);
 269
 270         /* calculate ranks in the ordering above */
 271         result_rank = result < 0 ? 1 + CLO_REPEAT : result;
 272         rc_rank = rc < 0 ? 1 + CLO_REPEAT : rc;
 273
 274         if (result_rank < rc_rank)
 275                 result = rc;
 276         return result;
 277 }
 278
 279 /**
 280  * Creates sub-locks for a given lov_lock for the first time.
 281  *
 282  * Goes through all sub-objects of top-object, and creates sub-locks on every
 283  * sub-object intersecting with top-lock extent. This is complicated by the
 284  * fact that top-lock (that is being created) can be accessed concurrently
 285  * through already created sub-locks (possibly shared with other top-locks).
 286  */
 287 static int lov_lock_sub_init(const struct lu_env *env,
 288                              struct lov_lock *lck, const struct cl_io *io)
 289 {
 290         int result = 0;
 291         int i;
 292         int nr;
 293         u64 start;
 294         u64 end;
 295         u64 file_start;
 296         u64 file_end;
 297
 298         struct lov_object       *loo    = cl2lov(lck->lls_cl.cls_obj);
 299         struct lov_layout_raid0 *r0     = lov_r0(loo);
 300         struct cl_lock    *parent = lck->lls_cl.cls_lock;
 301
 302         lck->lls_orig = parent->cll_descr;
 303         file_start = cl_offset(lov2cl(loo), parent->cll_descr.cld_start);
 304         file_end   = cl_offset(lov2cl(loo), parent->cll_descr.cld_end + 1) - 1;
 305
 306         for (i = 0, nr = 0; i < r0->lo_nr; i++) {
 307                 /*
 308                  * XXX for wide striping smarter algorithm is desirable,
 309                  * breaking out of the loop, early.
 310                  */
 311                 if (likely(r0->lo_sub[i] != NULL) &&
 312                     lov_stripe_intersects(loo->lo_lsm, i,
 313                                           file_start, file_end, &start, &end))
 314                         nr++;
 315         }
 316         LASSERT(nr > 0);
 317         OBD_ALLOC_LARGE(lck->lls_sub, nr * sizeof(lck->lls_sub[0]));
 318         if (lck->lls_sub == NULL)
 319                 return -ENOMEM;
 320
 321         lck->lls_nr = nr;
 322         /*
 323          * First, fill in sub-lock descriptions in
 324          * lck->lls_sub[].sub_descr. They are used by lov_sublock_alloc()
 325          * (called below in this function, and by lov_lock_enqueue()) to
 326          * create sub-locks. At this moment, no other thread can access
 327          * top-lock.
 328          */
 329         for (i = 0, nr = 0; i < r0->lo_nr; ++i) {
 330                 if (likely(r0->lo_sub[i] != NULL) &&
 331                     lov_stripe_intersects(loo->lo_lsm, i,
 332                                           file_start, file_end, &start, &end)) {
 333                         struct cl_lock_descr *descr;
 334
 335                         descr = &lck->lls_sub[nr].sub_descr;
 336
 337                         LASSERT(descr->cld_obj == NULL);
 338                         descr->cld_obj   = lovsub2cl(r0->lo_sub[i]);
 339                         descr->cld_start = cl_index(descr->cld_obj, start);
 340                         descr->cld_end   = cl_index(descr->cld_obj, end);
 341                         descr->cld_mode  = parent->cll_descr.cld_mode;
 342                         descr->cld_gid   = parent->cll_descr.cld_gid;
 343                         descr->cld_enq_flags   = parent->cll_descr.cld_enq_flags;
 344                         /* XXX has no effect */
 345                         lck->lls_sub[nr].sub_got = *descr;
 346                         lck->lls_sub[nr].sub_stripe = i;
 347                         nr++;
 348                 }
 349         }
 350         LASSERT(nr == lck->lls_nr);
 351
 352         /*
 353          * Some sub-locks can be missing at this point. This is not a problem,
 354          * because enqueue will create them anyway. Main duty of this function
 355          * is to fill in sub-lock descriptions in a race free manner.
 356          */
 357         return result;
 358 }
 359
 360 static int lov_sublock_release(const struct lu_env *env, struct lov_lock *lck,
 361                                int i, int deluser, int rc)
 362 {
 363         struct cl_lock *parent = lck->lls_cl.cls_lock;
 364
 365         LASSERT(cl_lock_is_mutexed(parent));
 366
 367         if (lck->lls_sub[i].sub_flags & LSF_HELD) {
 368                 struct cl_lock    *sublock;
 369                 int dying;
 370
 371                 LASSERT(lck->lls_sub[i].sub_lock != NULL);
 372                 sublock = lck->lls_sub[i].sub_lock->lss_cl.cls_lock;
 373                 LASSERT(cl_lock_is_mutexed(sublock));
 374
 375                 lck->lls_sub[i].sub_flags &= ~LSF_HELD;
 376                 if (deluser)
 377                         cl_lock_user_del(env, sublock);
 378                 /*
 379                  * If the last hold is released, and cancellation is pending
 380                  * for a sub-lock, release parent mutex, to avoid keeping it
 381                  * while sub-lock is being paged out.
 382                  */
 383                 dying = (sublock->cll_descr.cld_mode == CLM_PHANTOM ||
 384                          sublock->cll_descr.cld_mode == CLM_GROUP ||
 385                          (sublock->cll_flags & (CLF_CANCELPEND|CLF_DOOMED))) &&
 386                         sublock->cll_holds == 1;
 387                 if (dying)
 388                         cl_lock_mutex_put(env, parent);
 389                 cl_lock_unhold(env, sublock, "lov-parent", parent);
 390                 if (dying) {
 391                         cl_lock_mutex_get(env, parent);
 392                         rc = lov_subresult(rc, CLO_REPEAT);
 393                 }
 394                 /*
 395                  * From now on lck->lls_sub[i].sub_lock is a "weak" pointer,
 396                  * not backed by a reference on a
 397                  * sub-lock. lovsub_lock_delete() will clear
 398                  * lck->lls_sub[i].sub_lock under semaphores, just before
 399                  * sub-lock is destroyed.
 400                  */
 401         }
 402         return rc;
 403 }
 404
 405 static void lov_sublock_hold(const struct lu_env *env, struct lov_lock *lck,
 406                              int i)
 407 {
 408         struct cl_lock *parent = lck->lls_cl.cls_lock;
 409
 410         LASSERT(cl_lock_is_mutexed(parent));
 411
 412         if (!(lck->lls_sub[i].sub_flags & LSF_HELD)) {
 413                 struct cl_lock *sublock;
 414
 415                 LASSERT(lck->lls_sub[i].sub_lock != NULL);
 416                 sublock = lck->lls_sub[i].sub_lock->lss_cl.cls_lock;
 417                 LASSERT(cl_lock_is_mutexed(sublock));
 418                 LASSERT(sublock->cll_state != CLS_FREEING);
 419
 420                 lck->lls_sub[i].sub_flags |= LSF_HELD;
 421
 422                 cl_lock_get_trust(sublock);
 423                 cl_lock_hold_add(env, sublock, "lov-parent", parent);
 424                 cl_lock_user_add(env, sublock);
 425                 cl_lock_put(env, sublock);
 426         }
 427 }
 428
 429 static void lov_lock_fini(const struct lu_env *env,
 430                           struct cl_lock_slice *slice)
 431 {
 432         struct lov_lock *lck;
 433         int i;
 434
 435         lck = cl2lov_lock(slice);
 436         LASSERT(lck->lls_nr_filled == 0);
 437         if (lck->lls_sub != NULL) {
 438                 for (i = 0; i < lck->lls_nr; ++i)
 439                         /*
 440                          * No sub-locks exists at this point, as sub-lock has
 441                          * a reference on its parent.
 442                          */
 443                         LASSERT(lck->lls_sub[i].sub_lock == NULL);
 444                 OBD_FREE_LARGE(lck->lls_sub,
 445                                lck->lls_nr * sizeof(lck->lls_sub[0]));
 446         }
 447         OBD_SLAB_FREE_PTR(lck, lov_lock_kmem);
 448 }
 449
 450 static int lov_lock_enqueue_wait(const struct lu_env *env,
 451                                  struct lov_lock *lck,
 452                                  struct cl_lock *sublock)
 453 {
 454         struct cl_lock *lock = lck->lls_cl.cls_lock;
 455         int          result;
 456
 457         LASSERT(cl_lock_is_mutexed(lock));
 458
 459         cl_lock_mutex_put(env, lock);
 460         result = cl_lock_enqueue_wait(env, sublock, 0);
 461         cl_lock_mutex_get(env, lock);
 462         return result ?: CLO_REPEAT;
 463 }
 464
 465 /**
 466  * Tries to advance a state machine of a given sub-lock toward enqueuing of
 467  * the top-lock.
 468  *
 469  * \retval 0 if state-transition can proceed
 470  * \retval -ve otherwise.
 471  */
 472 static int lov_lock_enqueue_one(const struct lu_env *env, struct lov_lock *lck,
 473                                 struct cl_lock *sublock,
 474                                 struct cl_io *io, __u32 enqflags, int last)
 475 {
 476         int result;
 477
 478         /* first, try to enqueue a sub-lock ... */
 479         result = cl_enqueue_try(env, sublock, io, enqflags);
 480         if ((sublock->cll_state == CLS_ENQUEUED) && !(enqflags & CEF_AGL)) {
 481                 /* if it is enqueued, try to `wait' on it---maybe it's already
 482                  * granted */
 483                 result = cl_wait_try(env, sublock);
 484                 if (result == CLO_REENQUEUED)
 485                         result = CLO_WAIT;
 486         }
 487         /*
 488          * If CEF_ASYNC flag is set, then all sub-locks can be enqueued in
 489          * parallel, otherwise---enqueue has to wait until sub-lock is granted
 490          * before proceeding to the next one.
 491          */
 492         if ((result == CLO_WAIT) && (sublock->cll_state <= CLS_HELD) &&
 493             (enqflags & CEF_ASYNC) && (!last || (enqflags & CEF_AGL)))
 494                 result = 0;
 495         return result;
 496 }
 497
 498 /**
 499  * Helper function for lov_lock_enqueue() that creates missing sub-lock.
 500  */
 501 static int lov_sublock_fill(const struct lu_env *env, struct cl_lock *parent,
 502                             struct cl_io *io, struct lov_lock *lck, int idx)
 503 {
 504         struct lov_lock_link *link = NULL;
 505         struct cl_lock       *sublock;
 506         int                result;
 507
 508         LASSERT(parent->cll_depth == 1);
 509         cl_lock_mutex_put(env, parent);
 510         sublock = lov_sublock_alloc(env, io, lck, idx, &link);
 511         if (!IS_ERR(sublock))
 512                 cl_lock_mutex_get(env, sublock);
 513         cl_lock_mutex_get(env, parent);
 514
 515         if (!IS_ERR(sublock)) {
 516                 cl_lock_get_trust(sublock);
 517                 if (parent->cll_state == CLS_QUEUING &&
 518                     lck->lls_sub[idx].sub_lock == NULL) {
 519                         lov_sublock_adopt(env, lck, sublock, idx, link);
 520                 } else {
 521                         OBD_SLAB_FREE_PTR(link, lov_lock_link_kmem);
 522                         /* other thread allocated sub-lock, or enqueue is no
 523                          * longer going on */
 524                         cl_lock_mutex_put(env, parent);
 525                         cl_lock_unhold(env, sublock, "lov-parent", parent);
 526                         cl_lock_mutex_get(env, parent);
 527                 }
 528                 cl_lock_mutex_put(env, sublock);
 529                 cl_lock_put(env, sublock);
 530                 result = CLO_REPEAT;
 531         } else
 532                 result = PTR_ERR(sublock);
 533         return result;
 534 }
 535
 536 /**
 537  * Implementation of cl_lock_operations::clo_enqueue() for lov layer. This
 538  * function is rather subtle, as it enqueues top-lock (i.e., advances top-lock
 539  * state machine from CLS_QUEUING to CLS_ENQUEUED states) by juggling sub-lock
 540  * state machines in the face of sub-locks sharing (by multiple top-locks),
 541  * and concurrent sub-lock cancellations.
 542  */
 543 static int lov_lock_enqueue(const struct lu_env *env,
 544                             const struct cl_lock_slice *slice,
 545                             struct cl_io *io, __u32 enqflags)
 546 {
 547         struct cl_lock   *lock    = slice->cls_lock;
 548         struct lov_lock *lck     = cl2lov_lock(slice);
 549         struct cl_lock_closure *closure = lov_closure_get(env, lock);
 550         int i;
 551         int result;
 552         enum cl_lock_state minstate;
 553
 554         for (result = 0, minstate = CLS_FREEING, i = 0; i < lck->lls_nr; ++i) {
 555                 int rc;
 556                 struct lovsub_lock     *sub;
 557                 struct lov_lock_sub    *lls;
 558                 struct cl_lock   *sublock;
 559                 struct lov_sublock_env *subenv;
 560
 561                 if (lock->cll_state != CLS_QUEUING) {
 562                         /*
 563                          * Lock might have left QUEUING state if previous
 564                          * iteration released its mutex. Stop enqueing in this
 565                          * case and let the upper layer to decide what to do.
 566                          */
 567                         LASSERT(i > 0 && result != 0);
 568                         break;
 569                 }
 570
 571                 lls = &lck->lls_sub[i];
 572                 sub = lls->sub_lock;
 573                 /*
 574                  * Sub-lock might have been canceled, while top-lock was
 575                  * cached.
 576                  */
 577                 if (sub == NULL) {
 578                         result = lov_sublock_fill(env, lock, io, lck, i);
 579                         /* lov_sublock_fill() released @lock mutex,
 580                          * restart. */
 581                         break;
 582                 }
 583                 sublock = sub->lss_cl.cls_lock;
 584                 rc = lov_sublock_lock(env, lck, lls, closure, &subenv);
 585                 if (rc == 0) {
 586                         lov_sublock_hold(env, lck, i);
 587                         rc = lov_lock_enqueue_one(subenv->lse_env, lck, sublock,
 588                                                   subenv->lse_io, enqflags,
 589                                                   i == lck->lls_nr - 1);
 590                         minstate = min(minstate, sublock->cll_state);
 591                         if (rc == CLO_WAIT) {
 592                                 switch (sublock->cll_state) {
 593                                 case CLS_QUEUING:
 594                                         /* take recursive mutex, the lock is
 595                                          * released in lov_lock_enqueue_wait.
 596                                          */
 597                                         cl_lock_mutex_get(env, sublock);
 598                                         lov_sublock_unlock(env, sub, closure,
 599                                                            subenv);
 600                                         rc = lov_lock_enqueue_wait(env, lck,
 601                                                                    sublock);
 602                                         break;
 603                                 case CLS_CACHED:
 604                                         cl_lock_get(sublock);
 605                                         /* take recursive mutex of sublock */
 606                                         cl_lock_mutex_get(env, sublock);
 607                                         /* need to release all locks in closure
 608                                          * otherwise it may deadlock. LU-2683.*/
 609                                         lov_sublock_unlock(env, sub, closure,
 610                                                            subenv);
 611                                         /* sublock and parent are held. */
 612                                         rc = lov_sublock_release(env, lck, i,
 613                                                                  1, rc);
 614                                         cl_lock_mutex_put(env, sublock);
 615                                         cl_lock_put(env, sublock);
 616                                         break;
 617                                 default:
 618                                         lov_sublock_unlock(env, sub, closure,
 619                                                            subenv);
 620                                         break;
 621                                 }
 622                         } else {
 623                                 LASSERT(sublock->cll_conflict == NULL);
 624                                 lov_sublock_unlock(env, sub, closure, subenv);
 625                         }
 626                 }
 627                 result = lov_subresult(result, rc);
 628                 if (result != 0)
 629                         break;
 630         }
 631         cl_lock_closure_fini(closure);
 632         return result ?: minstate >= CLS_ENQUEUED ? 0 : CLO_WAIT;
 633 }
 634
 635 static int lov_lock_unuse(const struct lu_env *env,
 636                           const struct cl_lock_slice *slice)
 637 {
 638         struct lov_lock *lck     = cl2lov_lock(slice);
 639         struct cl_lock_closure *closure = lov_closure_get(env, slice->cls_lock);
 640         int i;
 641         int result;
 642
 643         for (result = 0, i = 0; i < lck->lls_nr; ++i) {
 644                 int rc;
 645                 struct lovsub_lock     *sub;
 646                 struct cl_lock   *sublock;
 647                 struct lov_lock_sub    *lls;
 648                 struct lov_sublock_env *subenv;
 649
 650                 /* top-lock state cannot change concurrently, because single
 651                  * thread (one that released the last hold) carries unlocking
 652                  * to the completion. */
 653                 LASSERT(slice->cls_lock->cll_state == CLS_INTRANSIT);
 654                 lls = &lck->lls_sub[i];
 655                 sub = lls->sub_lock;
 656                 if (sub == NULL)
 657                         continue;
 658
 659                 sublock = sub->lss_cl.cls_lock;
 660                 rc = lov_sublock_lock(env, lck, lls, closure, &subenv);
 661                 if (rc == 0) {
 662                         if (lls->sub_flags & LSF_HELD) {
 663                                 LASSERT(sublock->cll_state == CLS_HELD ||
 664                                         sublock->cll_state == CLS_ENQUEUED);
 665                                 rc = cl_unuse_try(subenv->lse_env, sublock);
 666                                 rc = lov_sublock_release(env, lck, i, 0, rc);
 667                         }
 668                         lov_sublock_unlock(env, sub, closure, subenv);
 669                 }
 670                 result = lov_subresult(result, rc);
 671         }
 672
 673         if (result == 0 && lck->lls_cancel_race) {
 674                 lck->lls_cancel_race = 0;
 675                 result = -ESTALE;
 676         }
 677         cl_lock_closure_fini(closure);
 678         return result;
 679 }
 680
 681
 682 static void lov_lock_cancel(const struct lu_env *env,
 683                            const struct cl_lock_slice *slice)
 684 {
 685         struct lov_lock *lck     = cl2lov_lock(slice);
 686         struct cl_lock_closure *closure = lov_closure_get(env, slice->cls_lock);
 687         int i;
 688         int result;
 689
 690         for (result = 0, i = 0; i < lck->lls_nr; ++i) {
 691                 int rc;
 692                 struct lovsub_lock     *sub;
 693                 struct cl_lock   *sublock;
 694                 struct lov_lock_sub    *lls;
 695                 struct lov_sublock_env *subenv;
 696
 697                 /* top-lock state cannot change concurrently, because single
 698                  * thread (one that released the last hold) carries unlocking
 699                  * to the completion. */
 700                 lls = &lck->lls_sub[i];
 701                 sub = lls->sub_lock;
 702                 if (sub == NULL)
 703                         continue;
 704
 705                 sublock = sub->lss_cl.cls_lock;
 706                 rc = lov_sublock_lock(env, lck, lls, closure, &subenv);
 707                 if (rc == 0) {
 708                         if (!(lls->sub_flags & LSF_HELD)) {
 709                                 lov_sublock_unlock(env, sub, closure, subenv);
 710                                 continue;
 711                         }
 712
 713                         switch (sublock->cll_state) {
 714                         case CLS_HELD:
 715                                 rc = cl_unuse_try(subenv->lse_env, sublock);
 716                                 lov_sublock_release(env, lck, i, 0, 0);
 717                                 break;
 718                         default:
 719                                 lov_sublock_release(env, lck, i, 1, 0);
 720                                 break;
 721                         }
 722                         lov_sublock_unlock(env, sub, closure, subenv);
 723                 }
 724
 725                 if (rc == CLO_REPEAT) {
 726                         --i;
 727                         continue;
 728                 }
 729
 730                 result = lov_subresult(result, rc);
 731         }
 732
 733         if (result)
 734                 CL_LOCK_DEBUG(D_ERROR, env, slice->cls_lock,
 735                               "lov_lock_cancel fails with %d.\n", result);
 736
 737         cl_lock_closure_fini(closure);
 738 }
 739
 740 static int lov_lock_wait(const struct lu_env *env,
 741                          const struct cl_lock_slice *slice)
 742 {
 743         struct lov_lock *lck     = cl2lov_lock(slice);
 744         struct cl_lock_closure *closure = lov_closure_get(env, slice->cls_lock);
 745         enum cl_lock_state      minstate;
 746         int                  reenqueued;
 747         int                  result;
 748         int                  i;
 749
 750 again:
 751         for (result = 0, minstate = CLS_FREEING, i = 0, reenqueued = 0;
 752              i < lck->lls_nr; ++i) {
 753                 int rc;
 754                 struct lovsub_lock     *sub;
 755                 struct cl_lock   *sublock;
 756                 struct lov_lock_sub    *lls;
 757                 struct lov_sublock_env *subenv;
 758
 759                 lls = &lck->lls_sub[i];
 760                 sub = lls->sub_lock;
 761                 LASSERT(sub != NULL);
 762                 sublock = sub->lss_cl.cls_lock;
 763                 rc = lov_sublock_lock(env, lck, lls, closure, &subenv);
 764                 if (rc == 0) {
 765                         LASSERT(sublock->cll_state >= CLS_ENQUEUED);
 766                         if (sublock->cll_state < CLS_HELD)
 767                                 rc = cl_wait_try(env, sublock);
 768
 769                         minstate = min(minstate, sublock->cll_state);
 770                         lov_sublock_unlock(env, sub, closure, subenv);
 771                 }
 772                 if (rc == CLO_REENQUEUED) {
 773                         reenqueued++;
 774                         rc = 0;
 775                 }
 776                 result = lov_subresult(result, rc);
 777                 if (result != 0)
 778                         break;
 779         }
 780         /* Each sublock only can be reenqueued once, so will not loop for
 781          * ever. */
 782         if (result == 0 && reenqueued != 0)
 783                 goto again;
 784         cl_lock_closure_fini(closure);
 785         return result ?: minstate >= CLS_HELD ? 0 : CLO_WAIT;
 786 }
 787
 788 static int lov_lock_use(const struct lu_env *env,
 789                         const struct cl_lock_slice *slice)
 790 {
 791         struct lov_lock *lck     = cl2lov_lock(slice);
 792         struct cl_lock_closure *closure = lov_closure_get(env, slice->cls_lock);
 793         int                  result;
 794         int                  i;
 795
 796         LASSERT(slice->cls_lock->cll_state == CLS_INTRANSIT);
 797
 798         for (result = 0, i = 0; i < lck->lls_nr; ++i) {
 799                 int rc;
 800                 struct lovsub_lock     *sub;
 801                 struct cl_lock   *sublock;
 802                 struct lov_lock_sub    *lls;
 803                 struct lov_sublock_env *subenv;
 804
 805                 LASSERT(slice->cls_lock->cll_state == CLS_INTRANSIT);
 806
 807                 lls = &lck->lls_sub[i];
 808                 sub = lls->sub_lock;
 809                 if (sub == NULL) {
 810                         /*
 811                          * Sub-lock might have been canceled, while top-lock was
 812                          * cached.
 813                          */
 814                         result = -ESTALE;
 815                         break;
 816                 }
 817
 818                 sublock = sub->lss_cl.cls_lock;
 819                 rc = lov_sublock_lock(env, lck, lls, closure, &subenv);
 820                 if (rc == 0) {
 821                         LASSERT(sublock->cll_state != CLS_FREEING);
 822                         lov_sublock_hold(env, lck, i);
 823                         if (sublock->cll_state == CLS_CACHED) {
 824                                 rc = cl_use_try(subenv->lse_env, sublock, 0);
 825                                 if (rc != 0)
 826                                         rc = lov_sublock_release(env, lck,
 827                                                                  i, 1, rc);
 828                         } else if (sublock->cll_state == CLS_NEW) {
 829                                 /* Sub-lock might have been canceled, while
 830                                  * top-lock was cached. */
 831                                 result = -ESTALE;
 832                                 lov_sublock_release(env, lck, i, 1, result);
 833                         }
 834                         lov_sublock_unlock(env, sub, closure, subenv);
 835                 }
 836                 result = lov_subresult(result, rc);
 837                 if (result != 0)
 838                         break;
 839         }
 840
 841         if (lck->lls_cancel_race) {
 842                 /*
 843                  * If there is unlocking happened at the same time, then
 844                  * sublock_lock state should be FREEING, and lov_sublock_lock
 845                  * should return CLO_REPEAT. In this case, it should return
 846                  * ESTALE, and up layer should reset the lock state to be NEW.
 847                  */
 848                 lck->lls_cancel_race = 0;
 849                 LASSERT(result != 0);
 850                 result = -ESTALE;
 851         }
 852         cl_lock_closure_fini(closure);
 853         return result;
 854 }
 855
 856 #if 0
 857 static int lock_lock_multi_match()
 858 {
 859         struct cl_lock    *lock    = slice->cls_lock;
 860         struct cl_lock_descr    *subneed = &lov_env_info(env)->lti_ldescr;
 861         struct lov_object       *loo     = cl2lov(lov->lls_cl.cls_obj);
 862         struct lov_layout_raid0 *r0      = lov_r0(loo);
 863         struct lov_lock_sub     *sub;
 864         struct cl_object        *subobj;
 865         u64  fstart;
 866         u64  fend;
 867         u64  start;
 868         u64  end;
 869         int i;
 870
 871         fstart = cl_offset(need->cld_obj, need->cld_start);
 872         fend   = cl_offset(need->cld_obj, need->cld_end + 1) - 1;
 873         subneed->cld_mode = need->cld_mode;
 874         cl_lock_mutex_get(env, lock);
 875         for (i = 0; i < lov->lls_nr; ++i) {
 876                 sub = &lov->lls_sub[i];
 877                 if (sub->sub_lock == NULL)
 878                         continue;
 879                 subobj = sub->sub_descr.cld_obj;
 880                 if (!lov_stripe_intersects(loo->lo_lsm, sub->sub_stripe,
 881                                            fstart, fend, &start, &end))
 882                         continue;
 883                 subneed->cld_start = cl_index(subobj, start);
 884                 subneed->cld_end   = cl_index(subobj, end);
 885                 subneed->cld_obj   = subobj;
 886                 if (!cl_lock_ext_match(&sub->sub_got, subneed)) {
 887                         result = 0;
 888                         break;
 889                 }
 890         }
 891         cl_lock_mutex_put(env, lock);
 892 }
 893 #endif
 894
 895 /**
 896  * Check if the extent region \a descr is covered by \a child against the
 897  * specific \a stripe.
 898  */
 899 static int lov_lock_stripe_is_matching(const struct lu_env *env,
 900                                        struct lov_object *lov, int stripe,
 901                                        const struct cl_lock_descr *child,
 902                                        const struct cl_lock_descr *descr)
 903 {
 904         struct lov_stripe_md *lsm = lov->lo_lsm;
 905         u64 start;
 906         u64 end;
 907         int result;
 908
 909         if (lov_r0(lov)->lo_nr == 1)
 910                 return cl_lock_ext_match(child, descr);
 911
 912         /*
 913          * For a multi-stripes object:
 914          * - make sure the descr only covers child's stripe, and
 915          * - check if extent is matching.
 916          */
 917         start = cl_offset(&lov->lo_cl, descr->cld_start);
 918         end   = cl_offset(&lov->lo_cl, descr->cld_end + 1) - 1;
 919         result = 0;
 920         /* glimpse should work on the object with LOV EA hole. */
 921         if (end - start <= lsm->lsm_stripe_size) {
 922                 int idx;
 923
 924                 idx = lov_stripe_number(lsm, start);
 925                 if (idx == stripe ||
 926                     unlikely(lov_r0(lov)->lo_sub[idx] == NULL)) {
 927                         idx = lov_stripe_number(lsm, end);
 928                         if (idx == stripe ||
 929                             unlikely(lov_r0(lov)->lo_sub[idx] == NULL))
 930                                 result = 1;
 931                 }
 932         }
 933
 934         if (result != 0) {
 935                 struct cl_lock_descr *subd = &lov_env_info(env)->lti_ldescr;
 936                 u64 sub_start;
 937                 u64 sub_end;
 938
 939                 subd->cld_obj  = NULL;   /* don't need sub object at all */
 940                 subd->cld_mode = descr->cld_mode;
 941                 subd->cld_gid  = descr->cld_gid;
 942                 result = lov_stripe_intersects(lsm, stripe, start, end,
 943                                                &sub_start, &sub_end);
 944                 LASSERT(result);
 945                 subd->cld_start = cl_index(child->cld_obj, sub_start);
 946                 subd->cld_end   = cl_index(child->cld_obj, sub_end);
 947                 result = cl_lock_ext_match(child, subd);
 948         }
 949         return result;
 950 }
 951
 952 /**
 953  * An implementation of cl_lock_operations::clo_fits_into() method.
 954  *
 955  * Checks whether a lock (given by \a slice) is suitable for \a
 956  * io. Multi-stripe locks can be used only for "quick" io, like truncate, or
 957  * O_APPEND write.
 958  *
 959  * \see ccc_lock_fits_into().
 960  */
 961 static int lov_lock_fits_into(const struct lu_env *env,
 962                               const struct cl_lock_slice *slice,
 963                               const struct cl_lock_descr *need,
 964                               const struct cl_io *io)
 965 {
 966         struct lov_lock   *lov = cl2lov_lock(slice);
 967         struct lov_object *obj = cl2lov(slice->cls_obj);
 968         int result;
 969
 970         LASSERT(cl_object_same(need->cld_obj, slice->cls_obj));
 971         LASSERT(lov->lls_nr > 0);
 972
 973         /* for top lock, it's necessary to match enq flags otherwise it will
 974          * run into problem if a sublock is missing and reenqueue. */
 975         if (need->cld_enq_flags != lov->lls_orig.cld_enq_flags)
 976                 return 0;
 977
 978         if (need->cld_mode == CLM_GROUP)
 979                 /*
 980                  * always allow to match group lock.
 981                  */
 982                 result = cl_lock_ext_match(&lov->lls_orig, need);
 983         else if (lov->lls_nr == 1) {
 984                 struct cl_lock_descr *got = &lov->lls_sub[0].sub_got;
 985                 result = lov_lock_stripe_is_matching(env,
 986                                                      cl2lov(slice->cls_obj),
 987                                                      lov->lls_sub[0].sub_stripe,
 988                                                      got, need);
 989         } else if (io->ci_type != CIT_SETATTR && io->ci_type != CIT_MISC &&
 990                    !cl_io_is_append(io) && need->cld_mode != CLM_PHANTOM)
 991                 /*
 992                  * Multi-stripe locks are only suitable for `quick' IO and for
 993                  * glimpse.
 994                  */
 995                 result = 0;
 996         else
 997                 /*
 998                  * Most general case: multi-stripe existing lock, and
 999                  * (potentially) multi-stripe @need lock. Check that @need is
1000                  * covered by @lov's sub-locks.
1001                  *
1002                  * For now, ignore lock expansions made by the server, and
1003                  * match against original lock extent.
1004                  */
1005                 result = cl_lock_ext_match(&lov->lls_orig, need);
1006         CDEBUG(D_DLMTRACE, DDESCR"/"DDESCR" %d %d/%d: %d\n",
1007                PDESCR(&lov->lls_orig), PDESCR(&lov->lls_sub[0].sub_got),
1008                lov->lls_sub[0].sub_stripe, lov->lls_nr, lov_r0(obj)->lo_nr,
1009                result);
1010         return result;
1011 }
1012
1013 void lov_lock_unlink(const struct lu_env *env,
1014                      struct lov_lock_link *link, struct lovsub_lock *sub)
1015 {
1016         struct lov_lock *lck    = link->lll_super;
1017         struct cl_lock  *parent = lck->lls_cl.cls_lock;
1018
1019         LASSERT(cl_lock_is_mutexed(parent));
1020         LASSERT(cl_lock_is_mutexed(sub->lss_cl.cls_lock));
1021
1022         list_del_init(&link->lll_list);
1023         LASSERT(lck->lls_sub[link->lll_idx].sub_lock == sub);
1024         /* yank this sub-lock from parent's array */
1025         lck->lls_sub[link->lll_idx].sub_lock = NULL;
1026         LASSERT(lck->lls_nr_filled > 0);
1027         lck->lls_nr_filled--;
1028         lu_ref_del(&parent->cll_reference, "lov-child", sub->lss_cl.cls_lock);
1029         cl_lock_put(env, parent);
1030         OBD_SLAB_FREE_PTR(link, lov_lock_link_kmem);
1031 }
1032
1033 struct lov_lock_link *lov_lock_link_find(const struct lu_env *env,
1034                                          struct lov_lock *lck,
1035                                          struct lovsub_lock *sub)
1036 {
1037         struct lov_lock_link *scan;
1038
1039         LASSERT(cl_lock_is_mutexed(sub->lss_cl.cls_lock));
1040
1041         list_for_each_entry(scan, &sub->lss_parents, lll_list) {
1042                 if (scan->lll_super == lck)
1043                         return scan;
1044         }
1045         return NULL;
1046 }
1047
1048 /**
1049  * An implementation of cl_lock_operations::clo_delete() method. This is
1050  * invoked for "top-to-bottom" delete, when lock destruction starts from the
1051  * top-lock, e.g., as a result of inode destruction.
1052  *
1053  * Unlinks top-lock from all its sub-locks. Sub-locks are not deleted there:
1054  * this is done separately elsewhere:
1055  *
1056  *     - for inode destruction, lov_object_delete() calls cl_object_kill() for
1057  *       each sub-object, purging its locks;
1058  *
1059  *     - in other cases (e.g., a fatal error with a top-lock) sub-locks are
1060  *       left in the cache.
1061  */
1062 static void lov_lock_delete(const struct lu_env *env,
1063                             const struct cl_lock_slice *slice)
1064 {
1065         struct lov_lock *lck     = cl2lov_lock(slice);
1066         struct cl_lock_closure *closure = lov_closure_get(env, slice->cls_lock);
1067         struct lov_lock_link   *link;
1068         int                  rc;
1069         int                  i;
1070
1071         LASSERT(slice->cls_lock->cll_state == CLS_FREEING);
1072
1073         for (i = 0; i < lck->lls_nr; ++i) {
1074                 struct lov_lock_sub *lls = &lck->lls_sub[i];
1075                 struct lovsub_lock  *lsl = lls->sub_lock;
1076
1077                 if (lsl == NULL) /* already removed */
1078                         continue;
1079
1080                 rc = lov_sublock_lock(env, lck, lls, closure, NULL);
1081                 if (rc == CLO_REPEAT) {
1082                         --i;
1083                         continue;
1084                 }
1085
1086                 LASSERT(rc == 0);
1087                 LASSERT(lsl->lss_cl.cls_lock->cll_state < CLS_FREEING);
1088
1089                 if (lls->sub_flags & LSF_HELD)
1090                         lov_sublock_release(env, lck, i, 1, 0);
1091
1092                 link = lov_lock_link_find(env, lck, lsl);
1093                 LASSERT(link != NULL);
1094                 lov_lock_unlink(env, link, lsl);
1095                 LASSERT(lck->lls_sub[i].sub_lock == NULL);
1096
1097                 lov_sublock_unlock(env, lsl, closure, NULL);
1098         }
1099
1100         cl_lock_closure_fini(closure);
1101 }
1102
1103 static int lov_lock_print(const struct lu_env *env, void *cookie,
1104                           lu_printer_t p, const struct cl_lock_slice *slice)
1105 {
1106         struct lov_lock *lck = cl2lov_lock(slice);
1107         int           i;
1108
1109         (*p)(env, cookie, "%d\n", lck->lls_nr);
1110         for (i = 0; i < lck->lls_nr; ++i) {
1111                 struct lov_lock_sub *sub;
1112
1113                 sub = &lck->lls_sub[i];
1114                 (*p)(env, cookie, "    %d %x: ", i, sub->sub_flags);
1115                 if (sub->sub_lock != NULL)
1116                         cl_lock_print(env, cookie, p,
1117                                       sub->sub_lock->lss_cl.cls_lock);
1118                 else
1119                         (*p)(env, cookie, "---\n");
1120         }
1121         return 0;
1122 }
1123
1124 static const struct cl_lock_operations lov_lock_ops = {
1125         .clo_fini      = lov_lock_fini,
1126         .clo_enqueue   = lov_lock_enqueue,
1127         .clo_wait      = lov_lock_wait,
1128         .clo_use       = lov_lock_use,
1129         .clo_unuse     = lov_lock_unuse,
1130         .clo_cancel    = lov_lock_cancel,
1131         .clo_fits_into = lov_lock_fits_into,
1132         .clo_delete    = lov_lock_delete,
1133         .clo_print     = lov_lock_print
1134 };
1135
1136 int lov_lock_init_raid0(const struct lu_env *env, struct cl_object *obj,
1137                         struct cl_lock *lock, const struct cl_io *io)
1138 {
1139         struct lov_lock *lck;
1140         int result;
1141
1142         OBD_SLAB_ALLOC_PTR_GFP(lck, lov_lock_kmem, GFP_NOFS);
1143         if (lck != NULL) {
1144                 cl_lock_slice_add(lock, &lck->lls_cl, obj, &lov_lock_ops);
1145                 result = lov_lock_sub_init(env, lck, io);
1146         } else
1147                 result = -ENOMEM;
1148         return result;
1149 }
1150
1151 static void lov_empty_lock_fini(const struct lu_env *env,
1152                                 struct cl_lock_slice *slice)
1153 {
1154         struct lov_lock *lck = cl2lov_lock(slice);
1155         OBD_SLAB_FREE_PTR(lck, lov_lock_kmem);
1156 }
1157
1158 static int lov_empty_lock_print(const struct lu_env *env, void *cookie,
1159                         lu_printer_t p, const struct cl_lock_slice *slice)
1160 {
1161         (*p)(env, cookie, "empty\n");
1162         return 0;
1163 }
1164
1165 /* XXX: more methods will be added later. */
1166 static const struct cl_lock_operations lov_empty_lock_ops = {
1167         .clo_fini  = lov_empty_lock_fini,
1168         .clo_print = lov_empty_lock_print
1169 };
1170
1171 int lov_lock_init_empty(const struct lu_env *env, struct cl_object *obj,
1172                 struct cl_lock *lock, const struct cl_io *io)
1173 {
1174         struct lov_lock *lck;
1175         int result = -ENOMEM;
1176
1177         OBD_SLAB_ALLOC_PTR_GFP(lck, lov_lock_kmem, GFP_NOFS);
1178         if (lck != NULL) {
1179                 cl_lock_slice_add(lock, &lck->lls_cl, obj, &lov_empty_lock_ops);
1180                 lck->lls_orig = lock->cll_descr;
1181                 result = 0;
1182         }
1183         return result;
1184 }
1185
1186 static struct cl_lock_closure *lov_closure_get(const struct lu_env *env,
1187                                                struct cl_lock *parent)
1188 {
1189         struct cl_lock_closure *closure;
1190
1191         closure = &lov_env_info(env)->lti_closure;
1192         LASSERT(list_empty(&closure->clc_list));
1193         cl_lock_closure_init(env, closure, parent, 1);
1194         return closure;
1195 }
1196
1197
1198 /** @} lov */