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, 2013, 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 infomation(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         ENTRY;
 114
 115         lsl = cl2sub_lock(sublock);
 116         /*
 117          * check that sub-lock doesn't have lock link to this top-lock.
 118          */
 119         LASSERT(lov_lock_link_find(env, lck, lsl) == NULL);
 120         LASSERT(idx < lck->lls_nr);
 121
 122         lck->lls_sub[idx].sub_lock = lsl;
 123         lck->lls_nr_filled++;
 124         LASSERT(lck->lls_nr_filled <= lck->lls_nr);
 125         cfs_list_add_tail(&link->lll_list, &lsl->lss_parents);
 126         link->lll_idx = idx;
 127         link->lll_super = lck;
 128         cl_lock_get(parent);
 129         lu_ref_add(&parent->cll_reference, "lov-child", sublock);
 130         lck->lls_sub[idx].sub_flags |= LSF_HELD;
 131         cl_lock_user_add(env, sublock);
 132
 133         rc = lov_sublock_modify(env, lck, lsl, &sublock->cll_descr, idx);
 134         LASSERT(rc == 0); /* there is no way this can fail, currently */
 135         EXIT;
 136 }
 137
 138 static struct cl_lock *lov_sublock_alloc(const struct lu_env *env,
 139                                          const struct cl_io *io,
 140                                          struct lov_lock *lck,
 141                                          int idx, struct lov_lock_link **out)
 142 {
 143         struct cl_lock       *sublock;
 144         struct cl_lock       *parent;
 145         struct lov_lock_link *link;
 146
 147         LASSERT(idx < lck->lls_nr);
 148         ENTRY;
 149
 150         OBD_SLAB_ALLOC_PTR_GFP(link, lov_lock_link_kmem, GFP_NOFS);
 151         if (link != NULL) {
 152                 struct lov_sublock_env *subenv;
 153                 struct lov_lock_sub  *lls;
 154                 struct cl_lock_descr *descr;
 155
 156                 parent = lck->lls_cl.cls_lock;
 157                 lls    = &lck->lls_sub[idx];
 158                 descr  = &lls->sub_got;
 159
 160                 subenv = lov_sublock_env_get(env, parent, lls);
 161                 if (!IS_ERR(subenv)) {
 162                         /* CAVEAT: Don't try to add a field in lov_lock_sub
 163                          * to remember the subio. This is because lock is able
 164                          * to be cached, but this is not true for IO. This
 165                          * further means a sublock might be referenced in
 166                          * different io context. -jay */
 167
 168                         sublock = cl_lock_hold(subenv->lse_env, subenv->lse_io,
 169                                                descr, "lov-parent", parent);
 170                         lov_sublock_env_put(subenv);
 171                 } else {
 172                         /* error occurs. */
 173                         sublock = (void *)subenv;
 174                 }
 175
 176                 if (!IS_ERR(sublock))
 177                         *out = link;
 178                 else
 179                         OBD_SLAB_FREE_PTR(link, lov_lock_link_kmem);
 180         } else
 181                 sublock = ERR_PTR(-ENOMEM);
 182         RETURN(sublock);
 183 }
 184
 185 static void lov_sublock_unlock(const struct lu_env *env,
 186                                struct lovsub_lock *lsl,
 187                                struct cl_lock_closure *closure,
 188                                struct lov_sublock_env *subenv)
 189 {
 190         ENTRY;
 191         lov_sublock_env_put(subenv);
 192         lsl->lss_active = NULL;
 193         cl_lock_disclosure(env, closure);
 194         EXIT;
 195 }
 196
 197 static int lov_sublock_lock(const struct lu_env *env,
 198                             struct lov_lock *lck,
 199                             struct lov_lock_sub *lls,
 200                             struct cl_lock_closure *closure,
 201                             struct lov_sublock_env **lsep)
 202 {
 203         struct lovsub_lock *sublock;
 204         struct cl_lock     *child;
 205         int                 result = 0;
 206         ENTRY;
 207
 208         LASSERT(cfs_list_empty(&closure->clc_list));
 209
 210         sublock = lls->sub_lock;
 211         child = sublock->lss_cl.cls_lock;
 212         result = cl_lock_closure_build(env, child, closure);
 213         if (result == 0) {
 214                 struct cl_lock *parent = closure->clc_origin;
 215
 216                 LASSERT(cl_lock_is_mutexed(child));
 217                 sublock->lss_active = parent;
 218
 219                 if (unlikely((child->cll_state == CLS_FREEING) ||
 220                              (child->cll_flags & CLF_CANCELLED))) {
 221                         struct lov_lock_link *link;
 222                         /*
 223                          * we could race with lock deletion which temporarily
 224                          * put the lock in freeing state, bug 19080.
 225                          */
 226                         LASSERT(!(lls->sub_flags & LSF_HELD));
 227
 228                         link = lov_lock_link_find(env, lck, sublock);
 229                         LASSERT(link != NULL);
 230                         lov_lock_unlink(env, link, sublock);
 231                         lov_sublock_unlock(env, sublock, closure, NULL);
 232                         lck->lls_cancel_race = 1;
 233                         result = CLO_REPEAT;
 234                 } else if (lsep) {
 235                         struct lov_sublock_env *subenv;
 236                         subenv = lov_sublock_env_get(env, parent, lls);
 237                         if (IS_ERR(subenv)) {
 238                                 lov_sublock_unlock(env, sublock,
 239                                                    closure, NULL);
 240                                 result = PTR_ERR(subenv);
 241                         } else {
 242                                 *lsep = subenv;
 243                         }
 244                 }
 245         }
 246         RETURN(result);
 247 }
 248
 249 /**
 250  * Updates the result of a top-lock operation from a result of sub-lock
 251  * sub-operations. Top-operations like lov_lock_{enqueue,use,unuse}() iterate
 252  * over sub-locks and lov_subresult() is used to calculate return value of a
 253  * top-operation. To this end, possible return values of sub-operations are
 254  * ordered as
 255  *
 256  *     - 0                  success
 257  *     - CLO_WAIT           wait for event
 258  *     - CLO_REPEAT         repeat top-operation
 259  *     - -ne                fundamental error
 260  *
 261  * Top-level return code can only go down through this list. CLO_REPEAT
 262  * overwrites CLO_WAIT, because lock mutex was released and sleeping condition
 263  * has to be rechecked by the upper layer.
 264  */
 265 static int lov_subresult(int result, int rc)
 266 {
 267         int result_rank;
 268         int rc_rank;
 269
 270         ENTRY;
 271
 272         LASSERTF(result <= 0 || result == CLO_REPEAT || result == CLO_WAIT,
 273                  "result = %d", result);
 274         LASSERTF(rc <= 0 || rc == CLO_REPEAT || rc == CLO_WAIT,
 275                  "rc = %d\n", rc);
 276         CLASSERT(CLO_WAIT < CLO_REPEAT);
 277
 278         /* calculate ranks in the ordering above */
 279         result_rank = result < 0 ? 1 + CLO_REPEAT : result;
 280         rc_rank = rc < 0 ? 1 + CLO_REPEAT : rc;
 281
 282         if (result_rank < rc_rank)
 283                 result = rc;
 284         RETURN(result);
 285 }
 286
 287 /**
 288  * Creates sub-locks for a given lov_lock for the first time.
 289  *
 290  * Goes through all sub-objects of top-object, and creates sub-locks on every
 291  * sub-object intersecting with top-lock extent. This is complicated by the
 292  * fact that top-lock (that is being created) can be accessed concurrently
 293  * through already created sub-locks (possibly shared with other top-locks).
 294  */
 295 static int lov_lock_sub_init(const struct lu_env *env,
 296                              struct lov_lock *lck, const struct cl_io *io)
 297 {
 298         int result = 0;
 299         int i;
 300         int nr;
 301         obd_off start;
 302         obd_off end;
 303         obd_off file_start;
 304         obd_off file_end;
 305
 306         struct lov_object       *loo    = cl2lov(lck->lls_cl.cls_obj);
 307         struct lov_layout_raid0 *r0     = lov_r0(loo);
 308         struct cl_lock          *parent = lck->lls_cl.cls_lock;
 309
 310         ENTRY;
 311
 312         lck->lls_orig = parent->cll_descr;
 313         file_start = cl_offset(lov2cl(loo), parent->cll_descr.cld_start);
 314         file_end   = cl_offset(lov2cl(loo), parent->cll_descr.cld_end + 1) - 1;
 315
 316         for (i = 0, nr = 0; i < r0->lo_nr; i++) {
 317                 /*
 318                  * XXX for wide striping smarter algorithm is desirable,
 319                  * breaking out of the loop, early.
 320                  */
 321                 if (lov_stripe_intersects(loo->lo_lsm, i,
 322                                           file_start, file_end, &start, &end))
 323                         nr++;
 324         }
 325         LASSERT(nr > 0);
 326         OBD_ALLOC_LARGE(lck->lls_sub, nr * sizeof lck->lls_sub[0]);
 327         if (lck->lls_sub == NULL)
 328                 RETURN(-ENOMEM);
 329
 330         lck->lls_nr = nr;
 331         /*
 332          * First, fill in sub-lock descriptions in
 333          * lck->lls_sub[].sub_descr. They are used by lov_sublock_alloc()
 334          * (called below in this function, and by lov_lock_enqueue()) to
 335          * create sub-locks. At this moment, no other thread can access
 336          * top-lock.
 337          */
 338         for (i = 0, nr = 0; i < r0->lo_nr; ++i) {
 339                 if (lov_stripe_intersects(loo->lo_lsm, i,
 340                                           file_start, file_end, &start, &end)) {
 341                         struct cl_lock_descr *descr;
 342
 343                         descr = &lck->lls_sub[nr].sub_descr;
 344
 345                         LASSERT(descr->cld_obj == NULL);
 346                         descr->cld_obj   = lovsub2cl(r0->lo_sub[i]);
 347                         descr->cld_start = cl_index(descr->cld_obj, start);
 348                         descr->cld_end   = cl_index(descr->cld_obj, end);
 349                         descr->cld_mode  = parent->cll_descr.cld_mode;
 350                         descr->cld_gid   = parent->cll_descr.cld_gid;
 351                         descr->cld_enq_flags   = parent->cll_descr.cld_enq_flags;
 352                         /* XXX has no effect */
 353                         lck->lls_sub[nr].sub_got = *descr;
 354                         lck->lls_sub[nr].sub_stripe = i;
 355                         nr++;
 356                 }
 357         }
 358         LASSERT(nr == lck->lls_nr);
 359
 360         /*
 361          * Some sub-locks can be missing at this point. This is not a problem,
 362          * because enqueue will create them anyway. Main duty of this function
 363          * is to fill in sub-lock descriptions in a race free manner.
 364          */
 365         RETURN(result);
 366 }
 367
 368 static int lov_sublock_release(const struct lu_env *env, struct lov_lock *lck,
 369                                int i, int deluser, int rc)
 370 {
 371         struct cl_lock *parent = lck->lls_cl.cls_lock;
 372
 373         LASSERT(cl_lock_is_mutexed(parent));
 374         ENTRY;
 375
 376         if (lck->lls_sub[i].sub_flags & LSF_HELD) {
 377                 struct cl_lock    *sublock;
 378                 int dying;
 379
 380                 LASSERT(lck->lls_sub[i].sub_lock != NULL);
 381                 sublock = lck->lls_sub[i].sub_lock->lss_cl.cls_lock;
 382                 LASSERT(cl_lock_is_mutexed(sublock));
 383
 384                 lck->lls_sub[i].sub_flags &= ~LSF_HELD;
 385                 if (deluser)
 386                         cl_lock_user_del(env, sublock);
 387                 /*
 388                  * If the last hold is released, and cancellation is pending
 389                  * for a sub-lock, release parent mutex, to avoid keeping it
 390                  * while sub-lock is being paged out.
 391                  */
 392                 dying = (sublock->cll_descr.cld_mode == CLM_PHANTOM ||
 393                          sublock->cll_descr.cld_mode == CLM_GROUP ||
 394                          (sublock->cll_flags & (CLF_CANCELPEND|CLF_DOOMED))) &&
 395                         sublock->cll_holds == 1;
 396                 if (dying)
 397                         cl_lock_mutex_put(env, parent);
 398                 cl_lock_unhold(env, sublock, "lov-parent", parent);
 399                 if (dying) {
 400                         cl_lock_mutex_get(env, parent);
 401                         rc = lov_subresult(rc, CLO_REPEAT);
 402                 }
 403                 /*
 404                  * From now on lck->lls_sub[i].sub_lock is a "weak" pointer,
 405                  * not backed by a reference on a
 406                  * sub-lock. lovsub_lock_delete() will clear
 407                  * lck->lls_sub[i].sub_lock under semaphores, just before
 408                  * sub-lock is destroyed.
 409                  */
 410         }
 411         RETURN(rc);
 412 }
 413
 414 static void lov_sublock_hold(const struct lu_env *env, struct lov_lock *lck,
 415                              int i)
 416 {
 417         struct cl_lock *parent = lck->lls_cl.cls_lock;
 418
 419         LASSERT(cl_lock_is_mutexed(parent));
 420         ENTRY;
 421
 422         if (!(lck->lls_sub[i].sub_flags & LSF_HELD)) {
 423                 struct cl_lock *sublock;
 424
 425                 LASSERT(lck->lls_sub[i].sub_lock != NULL);
 426                 sublock = lck->lls_sub[i].sub_lock->lss_cl.cls_lock;
 427                 LASSERT(cl_lock_is_mutexed(sublock));
 428                 LASSERT(sublock->cll_state != CLS_FREEING);
 429
 430                 lck->lls_sub[i].sub_flags |= LSF_HELD;
 431
 432                 cl_lock_get_trust(sublock);
 433                 cl_lock_hold_add(env, sublock, "lov-parent", parent);
 434                 cl_lock_user_add(env, sublock);
 435                 cl_lock_put(env, sublock);
 436         }
 437         EXIT;
 438 }
 439
 440 static void lov_lock_fini(const struct lu_env *env,
 441                           struct cl_lock_slice *slice)
 442 {
 443         struct lov_lock *lck;
 444         int i;
 445
 446         ENTRY;
 447         lck = cl2lov_lock(slice);
 448         LASSERT(lck->lls_nr_filled == 0);
 449         if (lck->lls_sub != NULL) {
 450                 for (i = 0; i < lck->lls_nr; ++i)
 451                         /*
 452                          * No sub-locks exists at this point, as sub-lock has
 453                          * a reference on its parent.
 454                          */
 455                         LASSERT(lck->lls_sub[i].sub_lock == NULL);
 456                 OBD_FREE_LARGE(lck->lls_sub,
 457                                lck->lls_nr * sizeof lck->lls_sub[0]);
 458         }
 459         OBD_SLAB_FREE_PTR(lck, lov_lock_kmem);
 460         EXIT;
 461 }
 462
 463 static int lov_lock_enqueue_wait(const struct lu_env *env,
 464                                  struct lov_lock *lck,
 465                                  struct cl_lock *sublock)
 466 {
 467         struct cl_lock *lock = lck->lls_cl.cls_lock;
 468         int             result;
 469         ENTRY;
 470
 471         LASSERT(cl_lock_is_mutexed(lock));
 472
 473         cl_lock_mutex_put(env, lock);
 474         result = cl_lock_enqueue_wait(env, sublock, 0);
 475         cl_lock_mutex_get(env, lock);
 476         RETURN(result ?: CLO_REPEAT);
 477 }
 478
 479 /**
 480  * Tries to advance a state machine of a given sub-lock toward enqueuing of
 481  * the top-lock.
 482  *
 483  * \retval 0 if state-transition can proceed
 484  * \retval -ve otherwise.
 485  */
 486 static int lov_lock_enqueue_one(const struct lu_env *env, struct lov_lock *lck,
 487                                 struct cl_lock *sublock,
 488                                 struct cl_io *io, __u32 enqflags, int last)
 489 {
 490         int result;
 491         ENTRY;
 492
 493         /* first, try to enqueue a sub-lock ... */
 494         result = cl_enqueue_try(env, sublock, io, enqflags);
 495         if ((sublock->cll_state == CLS_ENQUEUED) && !(enqflags & CEF_AGL)) {
 496                 /* if it is enqueued, try to `wait' on it---maybe it's already
 497                  * granted */
 498                 result = cl_wait_try(env, sublock);
 499                 if (result == CLO_REENQUEUED)
 500                         result = CLO_WAIT;
 501         }
 502         /*
 503          * If CEF_ASYNC flag is set, then all sub-locks can be enqueued in
 504          * parallel, otherwise---enqueue has to wait until sub-lock is granted
 505          * before proceeding to the next one.
 506          */
 507         if ((result == CLO_WAIT) && (sublock->cll_state <= CLS_HELD) &&
 508             (enqflags & CEF_ASYNC) && (!last || (enqflags & CEF_AGL)))
 509                 result = 0;
 510         RETURN(result);
 511 }
 512
 513 /**
 514  * Helper function for lov_lock_enqueue() that creates missing sub-lock.
 515  */
 516 static int lov_sublock_fill(const struct lu_env *env, struct cl_lock *parent,
 517                             struct cl_io *io, struct lov_lock *lck, int idx)
 518 {
 519         struct lov_lock_link *link = NULL;
 520         struct cl_lock       *sublock;
 521         int                   result;
 522
 523         LASSERT(parent->cll_depth == 1);
 524         cl_lock_mutex_put(env, parent);
 525         sublock = lov_sublock_alloc(env, io, lck, idx, &link);
 526         if (!IS_ERR(sublock))
 527                 cl_lock_mutex_get(env, sublock);
 528         cl_lock_mutex_get(env, parent);
 529
 530         if (!IS_ERR(sublock)) {
 531                 cl_lock_get_trust(sublock);
 532                 if (parent->cll_state == CLS_QUEUING &&
 533                     lck->lls_sub[idx].sub_lock == NULL) {
 534                         lov_sublock_adopt(env, lck, sublock, idx, link);
 535                 } else {
 536                         OBD_SLAB_FREE_PTR(link, lov_lock_link_kmem);
 537                         /* other thread allocated sub-lock, or enqueue is no
 538                          * longer going on */
 539                         cl_lock_mutex_put(env, parent);
 540                         cl_lock_unhold(env, sublock, "lov-parent", parent);
 541                         cl_lock_mutex_get(env, parent);
 542                 }
 543                 cl_lock_mutex_put(env, sublock);
 544                 cl_lock_put(env, sublock);
 545                 result = CLO_REPEAT;
 546         } else
 547                 result = PTR_ERR(sublock);
 548         return result;
 549 }
 550
 551 /**
 552  * Implementation of cl_lock_operations::clo_enqueue() for lov layer. This
 553  * function is rather subtle, as it enqueues top-lock (i.e., advances top-lock
 554  * state machine from CLS_QUEUING to CLS_ENQUEUED states) by juggling sub-lock
 555  * state machines in the face of sub-locks sharing (by multiple top-locks),
 556  * and concurrent sub-lock cancellations.
 557  */
 558 static int lov_lock_enqueue(const struct lu_env *env,
 559                             const struct cl_lock_slice *slice,
 560                             struct cl_io *io, __u32 enqflags)
 561 {
 562         struct cl_lock         *lock    = slice->cls_lock;
 563         struct lov_lock        *lck     = cl2lov_lock(slice);
 564         struct cl_lock_closure *closure = lov_closure_get(env, lock);
 565         int i;
 566         int result;
 567         enum cl_lock_state minstate;
 568
 569         ENTRY;
 570
 571         for (result = 0, minstate = CLS_FREEING, i = 0; i < lck->lls_nr; ++i) {
 572                 int rc;
 573                 struct lovsub_lock     *sub;
 574                 struct lov_lock_sub    *lls;
 575                 struct cl_lock         *sublock;
 576                 struct lov_sublock_env *subenv;
 577
 578                 if (lock->cll_state != CLS_QUEUING) {
 579                         /*
 580                          * Lock might have left QUEUING state if previous
 581                          * iteration released its mutex. Stop enqueing in this
 582                          * case and let the upper layer to decide what to do.
 583                          */
 584                         LASSERT(i > 0 && result != 0);
 585                         break;
 586                 }
 587
 588                 lls = &lck->lls_sub[i];
 589                 sub = lls->sub_lock;
 590                 /*
 591                  * Sub-lock might have been canceled, while top-lock was
 592                  * cached.
 593                  */
 594                 if (sub == NULL) {
 595                         result = lov_sublock_fill(env, lock, io, lck, i);
 596                         /* lov_sublock_fill() released @lock mutex,
 597                          * restart. */
 598                         break;
 599                 }
 600                 sublock = sub->lss_cl.cls_lock;
 601                 rc = lov_sublock_lock(env, lck, lls, closure, &subenv);
 602                 if (rc == 0) {
 603                         lov_sublock_hold(env, lck, i);
 604                         rc = lov_lock_enqueue_one(subenv->lse_env, lck, sublock,
 605                                                   subenv->lse_io, enqflags,
 606                                                   i == lck->lls_nr - 1);
 607                         minstate = min(minstate, sublock->cll_state);
 608                         if (rc == CLO_WAIT) {
 609                                 switch (sublock->cll_state) {
 610                                 case CLS_QUEUING:
 611                                         /* take recursive mutex, the lock is
 612                                          * released in lov_lock_enqueue_wait.
 613                                          */
 614                                         cl_lock_mutex_get(env, sublock);
 615                                         lov_sublock_unlock(env, sub, closure,
 616                                                            subenv);
 617                                         rc = lov_lock_enqueue_wait(env, lck,
 618                                                                    sublock);
 619                                         break;
 620                                 case CLS_CACHED:
 621                                         cl_lock_get(sublock);
 622                                         /* take recursive mutex of sublock */
 623                                         cl_lock_mutex_get(env, sublock);
 624                                         /* need to release all locks in closure
 625                                          * otherwise it may deadlock. LU-2683.*/
 626                                         lov_sublock_unlock(env, sub, closure,
 627                                                            subenv);
 628                                         /* sublock and parent are held. */
 629                                         rc = lov_sublock_release(env, lck, i,
 630                                                                  1, rc);
 631                                         cl_lock_mutex_put(env, sublock);
 632                                         cl_lock_put(env, sublock);
 633                                         break;
 634                                 default:
 635                                         lov_sublock_unlock(env, sub, closure,
 636                                                            subenv);
 637                                         break;
 638                                 }
 639                         } else {
 640                                 LASSERT(sublock->cll_conflict == NULL);
 641                                 lov_sublock_unlock(env, sub, closure, subenv);
 642                         }
 643                 }
 644                 result = lov_subresult(result, rc);
 645                 if (result != 0)
 646                         break;
 647         }
 648         cl_lock_closure_fini(closure);
 649         RETURN(result ?: minstate >= CLS_ENQUEUED ? 0 : CLO_WAIT);
 650 }
 651
 652 static int lov_lock_unuse(const struct lu_env *env,
 653                           const struct cl_lock_slice *slice)
 654 {
 655         struct lov_lock        *lck     = cl2lov_lock(slice);
 656         struct cl_lock_closure *closure = lov_closure_get(env, slice->cls_lock);
 657         int i;
 658         int result;
 659
 660         ENTRY;
 661
 662         for (result = 0, i = 0; i < lck->lls_nr; ++i) {
 663                 int rc;
 664                 struct lovsub_lock     *sub;
 665                 struct cl_lock         *sublock;
 666                 struct lov_lock_sub    *lls;
 667                 struct lov_sublock_env *subenv;
 668
 669                 /* top-lock state cannot change concurrently, because single
 670                  * thread (one that released the last hold) carries unlocking
 671                  * to the completion. */
 672                 LASSERT(slice->cls_lock->cll_state == CLS_INTRANSIT);
 673                 lls = &lck->lls_sub[i];
 674                 sub = lls->sub_lock;
 675                 if (sub == NULL)
 676                         continue;
 677
 678                 sublock = sub->lss_cl.cls_lock;
 679                 rc = lov_sublock_lock(env, lck, lls, closure, &subenv);
 680                 if (rc == 0) {
 681                         if (!(lls->sub_flags & LSF_HELD)) {
 682                                 lov_sublock_unlock(env, sub, closure, subenv);
 683                                 continue;
 684                         }
 685
 686                         switch(sublock->cll_state) {
 687                         case CLS_HELD:
 688                                 rc = cl_unuse_try(subenv->lse_env, sublock);
 689                                 lov_sublock_release(env, lck, i, 0, 0);
 690                                 break;
 691                         default:
 692                                 lov_sublock_release(env, lck, i, 1, 0);
 693                                 break;
 694                         }
 695                         lov_sublock_unlock(env, sub, closure, subenv);
 696                 }
 697                 result = lov_subresult(result, rc);
 698         }
 699
 700         if (result == 0 && lck->lls_cancel_race) {
 701                 lck->lls_cancel_race = 0;
 702                 result = -ESTALE;
 703         }
 704         cl_lock_closure_fini(closure);
 705         RETURN(result);
 706 }
 707
 708
 709 static void lov_lock_cancel(const struct lu_env *env,
 710                            const struct cl_lock_slice *slice)
 711 {
 712         struct lov_lock        *lck     = cl2lov_lock(slice);
 713         struct cl_lock_closure *closure = lov_closure_get(env, slice->cls_lock);
 714         int i;
 715         int result;
 716
 717         ENTRY;
 718
 719         for (result = 0, i = 0; i < lck->lls_nr; ++i) {
 720                 int rc;
 721                 struct lovsub_lock     *sub;
 722                 struct cl_lock         *sublock;
 723                 struct lov_lock_sub    *lls;
 724                 struct lov_sublock_env *subenv;
 725
 726                 /* top-lock state cannot change concurrently, because single
 727                  * thread (one that released the last hold) carries unlocking
 728                  * to the completion. */
 729                 lls = &lck->lls_sub[i];
 730                 sub = lls->sub_lock;
 731                 if (sub == NULL)
 732                         continue;
 733
 734                 sublock = sub->lss_cl.cls_lock;
 735                 rc = lov_sublock_lock(env, lck, lls, closure, &subenv);
 736                 if (rc == 0) {
 737                         if (!(lls->sub_flags & LSF_HELD)) {
 738                                 lov_sublock_unlock(env, sub, closure, subenv);
 739                                 continue;
 740                         }
 741
 742                         switch(sublock->cll_state) {
 743                         case CLS_HELD:
 744                                 rc = cl_unuse_try(subenv->lse_env, sublock);
 745                                 lov_sublock_release(env, lck, i, 0, 0);
 746                                 break;
 747                         default:
 748                                 lov_sublock_release(env, lck, i, 1, 0);
 749                                 break;
 750                         }
 751                         lov_sublock_unlock(env, sub, closure, subenv);
 752                 }
 753
 754                 if (rc == CLO_REPEAT) {
 755                         --i;
 756                         continue;
 757                 }
 758
 759                 result = lov_subresult(result, rc);
 760         }
 761
 762         if (result)
 763                 CL_LOCK_DEBUG(D_ERROR, env, slice->cls_lock,
 764                               "lov_lock_cancel fails with %d.\n", result);
 765
 766         cl_lock_closure_fini(closure);
 767 }
 768
 769 static int lov_lock_wait(const struct lu_env *env,
 770                          const struct cl_lock_slice *slice)
 771 {
 772         struct lov_lock        *lck     = cl2lov_lock(slice);
 773         struct cl_lock_closure *closure = lov_closure_get(env, slice->cls_lock);
 774         enum cl_lock_state      minstate;
 775         int                     reenqueued;
 776         int                     result;
 777         int                     i;
 778
 779         ENTRY;
 780
 781 again:
 782         for (result = 0, minstate = CLS_FREEING, i = 0, reenqueued = 0;
 783              i < lck->lls_nr; ++i) {
 784                 int rc;
 785                 struct lovsub_lock     *sub;
 786                 struct cl_lock         *sublock;
 787                 struct lov_lock_sub    *lls;
 788                 struct lov_sublock_env *subenv;
 789
 790                 lls = &lck->lls_sub[i];
 791                 sub = lls->sub_lock;
 792                 LASSERT(sub != NULL);
 793                 sublock = sub->lss_cl.cls_lock;
 794                 rc = lov_sublock_lock(env, lck, lls, closure, &subenv);
 795                 if (rc == 0) {
 796                         LASSERT(sublock->cll_state >= CLS_ENQUEUED);
 797                         if (sublock->cll_state < CLS_HELD)
 798                                 rc = cl_wait_try(env, sublock);
 799
 800                         minstate = min(minstate, sublock->cll_state);
 801                         lov_sublock_unlock(env, sub, closure, subenv);
 802                 }
 803                 if (rc == CLO_REENQUEUED) {
 804                         reenqueued++;
 805                         rc = 0;
 806                 }
 807                 result = lov_subresult(result, rc);
 808                 if (result != 0)
 809                         break;
 810         }
 811         /* Each sublock only can be reenqueued once, so will not loop for
 812          * ever. */
 813         if (result == 0 && reenqueued != 0)
 814                 goto again;
 815         cl_lock_closure_fini(closure);
 816         RETURN(result ?: minstate >= CLS_HELD ? 0 : CLO_WAIT);
 817 }
 818
 819 static int lov_lock_use(const struct lu_env *env,
 820                         const struct cl_lock_slice *slice)
 821 {
 822         struct lov_lock        *lck     = cl2lov_lock(slice);
 823         struct cl_lock_closure *closure = lov_closure_get(env, slice->cls_lock);
 824         int                     result;
 825         int                     i;
 826
 827         LASSERT(slice->cls_lock->cll_state == CLS_INTRANSIT);
 828         ENTRY;
 829
 830         for (result = 0, i = 0; i < lck->lls_nr; ++i) {
 831                 int rc;
 832                 struct lovsub_lock     *sub;
 833                 struct cl_lock         *sublock;
 834                 struct lov_lock_sub    *lls;
 835                 struct lov_sublock_env *subenv;
 836
 837                 LASSERT(slice->cls_lock->cll_state == CLS_INTRANSIT);
 838
 839                 lls = &lck->lls_sub[i];
 840                 sub = lls->sub_lock;
 841                 if (sub == NULL) {
 842                         /*
 843                          * Sub-lock might have been canceled, while top-lock was
 844                          * cached.
 845                          */
 846                         result = -ESTALE;
 847                         break;
 848                 }
 849
 850                 sublock = sub->lss_cl.cls_lock;
 851                 rc = lov_sublock_lock(env, lck, lls, closure, &subenv);
 852                 if (rc == 0) {
 853                         LASSERT(sublock->cll_state != CLS_FREEING);
 854                         lov_sublock_hold(env, lck, i);
 855                         if (sublock->cll_state == CLS_CACHED) {
 856                                 rc = cl_use_try(subenv->lse_env, sublock, 0);
 857                                 if (rc != 0)
 858                                         rc = lov_sublock_release(env, lck,
 859                                                                  i, 1, rc);
 860                         } else if (sublock->cll_state == CLS_NEW) {
 861                                 /* Sub-lock might have been canceled, while
 862                                  * top-lock was cached. */
 863                                 result = -ESTALE;
 864                                 lov_sublock_release(env, lck, i, 1, result);
 865                         }
 866                         lov_sublock_unlock(env, sub, closure, subenv);
 867                 }
 868                 result = lov_subresult(result, rc);
 869                 if (result != 0)
 870                         break;
 871         }
 872
 873         if (lck->lls_cancel_race) {
 874                 /*
 875                  * If there is unlocking happened at the same time, then
 876                  * sublock_lock state should be FREEING, and lov_sublock_lock
 877                  * should return CLO_REPEAT. In this case, it should return
 878                  * ESTALE, and up layer should reset the lock state to be NEW.
 879                  */
 880                 lck->lls_cancel_race = 0;
 881                 LASSERT(result != 0);
 882                 result = -ESTALE;
 883         }
 884         cl_lock_closure_fini(closure);
 885         RETURN(result);
 886 }
 887
 888 #if 0
 889 static int lock_lock_multi_match()
 890 {
 891         struct cl_lock          *lock    = slice->cls_lock;
 892         struct cl_lock_descr    *subneed = &lov_env_info(env)->lti_ldescr;
 893         struct lov_object       *loo     = cl2lov(lov->lls_cl.cls_obj);
 894         struct lov_layout_raid0 *r0      = lov_r0(loo);
 895         struct lov_lock_sub     *sub;
 896         struct cl_object        *subobj;
 897         obd_off  fstart;
 898         obd_off  fend;
 899         obd_off  start;
 900         obd_off  end;
 901         int i;
 902
 903         fstart = cl_offset(need->cld_obj, need->cld_start);
 904         fend   = cl_offset(need->cld_obj, need->cld_end + 1) - 1;
 905         subneed->cld_mode = need->cld_mode;
 906         cl_lock_mutex_get(env, lock);
 907         for (i = 0; i < lov->lls_nr; ++i) {
 908                 sub = &lov->lls_sub[i];
 909                 if (sub->sub_lock == NULL)
 910                         continue;
 911                 subobj = sub->sub_descr.cld_obj;
 912                 if (!lov_stripe_intersects(loo->lo_lsm, sub->sub_stripe,
 913                                            fstart, fend, &start, &end))
 914                         continue;
 915                 subneed->cld_start = cl_index(subobj, start);
 916                 subneed->cld_end   = cl_index(subobj, end);
 917                 subneed->cld_obj   = subobj;
 918                 if (!cl_lock_ext_match(&sub->sub_got, subneed)) {
 919                         result = 0;
 920                         break;
 921                 }
 922         }
 923         cl_lock_mutex_put(env, lock);
 924 }
 925 #endif
 926
 927 /**
 928  * Check if the extent region \a descr is covered by \a child against the
 929  * specific \a stripe.
 930  */
 931 static int lov_lock_stripe_is_matching(const struct lu_env *env,
 932                                        struct lov_object *lov, int stripe,
 933                                        const struct cl_lock_descr *child,
 934                                        const struct cl_lock_descr *descr)
 935 {
 936         struct lov_stripe_md *lsm = lov->lo_lsm;
 937         obd_off start;
 938         obd_off end;
 939         int result;
 940
 941         if (lov_r0(lov)->lo_nr == 1)
 942                 return cl_lock_ext_match(child, descr);
 943
 944         /*
 945          * For a multi-stripes object:
 946          * - make sure the descr only covers child's stripe, and
 947          * - check if extent is matching.
 948          */
 949         start = cl_offset(&lov->lo_cl, descr->cld_start);
 950         end   = cl_offset(&lov->lo_cl, descr->cld_end + 1) - 1;
 951         result = end - start <= lsm->lsm_stripe_size &&
 952                  stripe == lov_stripe_number(lsm, start) &&
 953                  stripe == lov_stripe_number(lsm, end);
 954         if (result) {
 955                 struct cl_lock_descr *subd = &lov_env_info(env)->lti_ldescr;
 956                 obd_off sub_start;
 957                 obd_off sub_end;
 958
 959                 subd->cld_obj  = NULL;   /* don't need sub object at all */
 960                 subd->cld_mode = descr->cld_mode;
 961                 subd->cld_gid  = descr->cld_gid;
 962                 result = lov_stripe_intersects(lsm, stripe, start, end,
 963                                                &sub_start, &sub_end);
 964                 LASSERT(result);
 965                 subd->cld_start = cl_index(child->cld_obj, sub_start);
 966                 subd->cld_end   = cl_index(child->cld_obj, sub_end);
 967                 result = cl_lock_ext_match(child, subd);
 968         }
 969         return result;
 970 }
 971
 972 /**
 973  * An implementation of cl_lock_operations::clo_fits_into() method.
 974  *
 975  * Checks whether a lock (given by \a slice) is suitable for \a
 976  * io. Multi-stripe locks can be used only for "quick" io, like truncate, or
 977  * O_APPEND write.
 978  *
 979  * \see ccc_lock_fits_into().
 980  */
 981 static int lov_lock_fits_into(const struct lu_env *env,
 982                               const struct cl_lock_slice *slice,
 983                               const struct cl_lock_descr *need,
 984                               const struct cl_io *io)
 985 {
 986         struct lov_lock   *lov = cl2lov_lock(slice);
 987         struct lov_object *obj = cl2lov(slice->cls_obj);
 988         int result;
 989
 990         LASSERT(cl_object_same(need->cld_obj, slice->cls_obj));
 991         LASSERT(lov->lls_nr > 0);
 992
 993         ENTRY;
 994
 995         /* for top lock, it's necessary to match enq flags otherwise it will
 996          * run into problem if a sublock is missing and reenqueue. */
 997         if (need->cld_enq_flags != lov->lls_orig.cld_enq_flags)
 998                 return 0;
 999
1000         if (lov->lls_ever_canceled)
1001                 return 0;
1002
1003         if (need->cld_mode == CLM_GROUP)
1004                 /*
1005                  * always allow to match group lock.
1006                  */
1007                 result = cl_lock_ext_match(&lov->lls_orig, need);
1008         else if (lov->lls_nr == 1) {
1009                 struct cl_lock_descr *got = &lov->lls_sub[0].sub_got;
1010                 result = lov_lock_stripe_is_matching(env,
1011                                                      cl2lov(slice->cls_obj),
1012                                                      lov->lls_sub[0].sub_stripe,
1013                                                      got, need);
1014         } else if (io->ci_type != CIT_SETATTR && io->ci_type != CIT_MISC &&
1015                    !cl_io_is_append(io) && need->cld_mode != CLM_PHANTOM)
1016                 /*
1017                  * Multi-stripe locks are only suitable for `quick' IO and for
1018                  * glimpse.
1019                  */
1020                 result = 0;
1021         else
1022                 /*
1023                  * Most general case: multi-stripe existing lock, and
1024                  * (potentially) multi-stripe @need lock. Check that @need is
1025                  * covered by @lov's sub-locks.
1026                  *
1027                  * For now, ignore lock expansions made by the server, and
1028                  * match against original lock extent.
1029                  */
1030                 result = cl_lock_ext_match(&lov->lls_orig, need);
1031         CDEBUG(D_DLMTRACE, DDESCR"/"DDESCR" %d %d/%d: %d\n",
1032                PDESCR(&lov->lls_orig), PDESCR(&lov->lls_sub[0].sub_got),
1033                lov->lls_sub[0].sub_stripe, lov->lls_nr, lov_r0(obj)->lo_nr,
1034                result);
1035         RETURN(result);
1036 }
1037
1038 void lov_lock_unlink(const struct lu_env *env,
1039                      struct lov_lock_link *link, struct lovsub_lock *sub)
1040 {
1041         struct lov_lock *lck    = link->lll_super;
1042         struct cl_lock  *parent = lck->lls_cl.cls_lock;
1043
1044         LASSERT(cl_lock_is_mutexed(parent));
1045         LASSERT(cl_lock_is_mutexed(sub->lss_cl.cls_lock));
1046         ENTRY;
1047
1048         cfs_list_del_init(&link->lll_list);
1049         LASSERT(lck->lls_sub[link->lll_idx].sub_lock == sub);
1050         /* yank this sub-lock from parent's array */
1051         lck->lls_sub[link->lll_idx].sub_lock = NULL;
1052         LASSERT(lck->lls_nr_filled > 0);
1053         lck->lls_nr_filled--;
1054         lu_ref_del(&parent->cll_reference, "lov-child", sub->lss_cl.cls_lock);
1055         cl_lock_put(env, parent);
1056         OBD_SLAB_FREE_PTR(link, lov_lock_link_kmem);
1057         EXIT;
1058 }
1059
1060 struct lov_lock_link *lov_lock_link_find(const struct lu_env *env,
1061                                          struct lov_lock *lck,
1062                                          struct lovsub_lock *sub)
1063 {
1064         struct lov_lock_link *scan;
1065
1066         LASSERT(cl_lock_is_mutexed(sub->lss_cl.cls_lock));
1067         ENTRY;
1068
1069         cfs_list_for_each_entry(scan, &sub->lss_parents, lll_list) {
1070                 if (scan->lll_super == lck)
1071                         RETURN(scan);
1072         }
1073         RETURN(NULL);
1074 }
1075
1076 /**
1077  * An implementation of cl_lock_operations::clo_delete() method. This is
1078  * invoked for "top-to-bottom" delete, when lock destruction starts from the
1079  * top-lock, e.g., as a result of inode destruction.
1080  *
1081  * Unlinks top-lock from all its sub-locks. Sub-locks are not deleted there:
1082  * this is done separately elsewhere:
1083  *
1084  *     - for inode destruction, lov_object_delete() calls cl_object_kill() for
1085  *       each sub-object, purging its locks;
1086  *
1087  *     - in other cases (e.g., a fatal error with a top-lock) sub-locks are
1088  *       left in the cache.
1089  */
1090 static void lov_lock_delete(const struct lu_env *env,
1091                             const struct cl_lock_slice *slice)
1092 {
1093         struct lov_lock        *lck     = cl2lov_lock(slice);
1094         struct cl_lock_closure *closure = lov_closure_get(env, slice->cls_lock);
1095         struct lov_lock_link   *link;
1096         int                     rc;
1097         int                     i;
1098
1099         LASSERT(slice->cls_lock->cll_state == CLS_FREEING);
1100         ENTRY;
1101
1102         for (i = 0; i < lck->lls_nr; ++i) {
1103                 struct lov_lock_sub *lls = &lck->lls_sub[i];
1104                 struct lovsub_lock  *lsl = lls->sub_lock;
1105
1106                 if (lsl == NULL) /* already removed */
1107                         continue;
1108
1109                 rc = lov_sublock_lock(env, lck, lls, closure, NULL);
1110                 if (rc == CLO_REPEAT) {
1111                         --i;
1112                         continue;
1113                 }
1114
1115                 LASSERT(rc == 0);
1116                 LASSERT(lsl->lss_cl.cls_lock->cll_state < CLS_FREEING);
1117
1118                 if (lls->sub_flags & LSF_HELD)
1119                         lov_sublock_release(env, lck, i, 1, 0);
1120
1121                 link = lov_lock_link_find(env, lck, lsl);
1122                 LASSERT(link != NULL);
1123                 lov_lock_unlink(env, link, lsl);
1124                 LASSERT(lck->lls_sub[i].sub_lock == NULL);
1125
1126                 lov_sublock_unlock(env, lsl, closure, NULL);
1127         }
1128
1129         cl_lock_closure_fini(closure);
1130         EXIT;
1131 }
1132
1133 static int lov_lock_print(const struct lu_env *env, void *cookie,
1134                           lu_printer_t p, const struct cl_lock_slice *slice)
1135 {
1136         struct lov_lock *lck = cl2lov_lock(slice);
1137         int              i;
1138
1139         (*p)(env, cookie, "%d\n", lck->lls_nr);
1140         for (i = 0; i < lck->lls_nr; ++i) {
1141                 struct lov_lock_sub *sub;
1142
1143                 sub = &lck->lls_sub[i];
1144                 (*p)(env, cookie, "    %d %x: ", i, sub->sub_flags);
1145                 if (sub->sub_lock != NULL)
1146                         cl_lock_print(env, cookie, p,
1147                                       sub->sub_lock->lss_cl.cls_lock);
1148                 else
1149                         (*p)(env, cookie, "---\n");
1150         }
1151         return 0;
1152 }
1153
1154 static const struct cl_lock_operations lov_lock_ops = {
1155         .clo_fini      = lov_lock_fini,
1156         .clo_enqueue   = lov_lock_enqueue,
1157         .clo_wait      = lov_lock_wait,
1158         .clo_use       = lov_lock_use,
1159         .clo_unuse     = lov_lock_unuse,
1160         .clo_cancel    = lov_lock_cancel,
1161         .clo_fits_into = lov_lock_fits_into,
1162         .clo_delete    = lov_lock_delete,
1163         .clo_print     = lov_lock_print
1164 };
1165
1166 int lov_lock_init_raid0(const struct lu_env *env, struct cl_object *obj,
1167                         struct cl_lock *lock, const struct cl_io *io)
1168 {
1169         struct lov_lock *lck;
1170         int result;
1171
1172         ENTRY;
1173         OBD_SLAB_ALLOC_PTR_GFP(lck, lov_lock_kmem, GFP_NOFS);
1174         if (lck != NULL) {
1175                 cl_lock_slice_add(lock, &lck->lls_cl, obj, &lov_lock_ops);
1176                 result = lov_lock_sub_init(env, lck, io);
1177         } else
1178                 result = -ENOMEM;
1179         RETURN(result);
1180 }
1181
1182 static void lov_empty_lock_fini(const struct lu_env *env,
1183                                 struct cl_lock_slice *slice)
1184 {
1185         struct lov_lock *lck = cl2lov_lock(slice);
1186         OBD_SLAB_FREE_PTR(lck, lov_lock_kmem);
1187 }
1188
1189 static int lov_empty_lock_print(const struct lu_env *env, void *cookie,
1190                         lu_printer_t p, const struct cl_lock_slice *slice)
1191 {
1192         (*p)(env, cookie, "empty\n");
1193         return 0;
1194 }
1195
1196 /* XXX: more methods will be added later. */
1197 static const struct cl_lock_operations lov_empty_lock_ops = {
1198         .clo_fini  = lov_empty_lock_fini,
1199         .clo_print = lov_empty_lock_print
1200 };
1201
1202 int lov_lock_init_empty(const struct lu_env *env, struct cl_object *obj,
1203                         struct cl_lock *lock, const struct cl_io *io)
1204 {
1205         struct lov_lock *lck;
1206         int result = -ENOMEM;
1207
1208         ENTRY;
1209         OBD_SLAB_ALLOC_PTR_GFP(lck, lov_lock_kmem, GFP_NOFS);
1210         if (lck != NULL) {
1211                 cl_lock_slice_add(lock, &lck->lls_cl, obj, &lov_empty_lock_ops);
1212                 lck->lls_orig = lock->cll_descr;
1213                 result = 0;
1214         }
1215         RETURN(result);
1216 }
1217
1218 static struct cl_lock_closure *lov_closure_get(const struct lu_env *env,
1219                                                struct cl_lock *parent)
1220 {
1221         struct cl_lock_closure *closure;
1222
1223         closure = &lov_env_info(env)->lti_closure;
1224         LASSERT(cfs_list_empty(&closure->clc_list));
1225         cl_lock_closure_init(env, closure, parent, 1);
1226         return closure;
1227 }
1228
1229
1230 /** @} lov */