Pileus Git - ~andy/linux/blob - 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_IO);
 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         obd_off start;
 294         obd_off end;
 295         obd_off file_start;
 296         obd_off 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 (lov_stripe_intersects(loo->lo_lsm, i,
 312                                           file_start, file_end, &start, &end))
 313                         nr++;
 314         }
 315         LASSERT(nr > 0);
 316         OBD_ALLOC_LARGE(lck->lls_sub, nr * sizeof(lck->lls_sub[0]));
 317         if (lck->lls_sub == NULL)
 318                 return -ENOMEM;
 319
 320         lck->lls_nr = nr;
 321         /*
 322          * First, fill in sub-lock descriptions in
 323          * lck->lls_sub[].sub_descr. They are used by lov_sublock_alloc()
 324          * (called below in this function, and by lov_lock_enqueue()) to
 325          * create sub-locks. At this moment, no other thread can access
 326          * top-lock.
 327          */
 328         for (i = 0, nr = 0; i < r0->lo_nr; ++i) {
 329                 if (lov_stripe_intersects(loo->lo_lsm, i,
 330                                           file_start, file_end, &start, &end)) {
 331                         struct cl_lock_descr *descr;
 332
 333                         descr = &lck->lls_sub[nr].sub_descr;
 334
 335                         LASSERT(descr->cld_obj == NULL);
 336                         descr->cld_obj   = lovsub2cl(r0->lo_sub[i]);
 337                         descr->cld_start = cl_index(descr->cld_obj, start);
 338                         descr->cld_end   = cl_index(descr->cld_obj, end);
 339                         descr->cld_mode  = parent->cll_descr.cld_mode;
 340                         descr->cld_gid   = parent->cll_descr.cld_gid;
 341                         descr->cld_enq_flags   = parent->cll_descr.cld_enq_flags;
 342                         /* XXX has no effect */
 343                         lck->lls_sub[nr].sub_got = *descr;
 344                         lck->lls_sub[nr].sub_stripe = i;
 345                         nr++;
 346                 }
 347         }
 348         LASSERT(nr == lck->lls_nr);
 349         /*
 350          * Then, create sub-locks. Once at least one sub-lock was created,
 351          * top-lock can be reached by other threads.
 352          */
 353         for (i = 0; i < lck->lls_nr; ++i) {
 354                 struct cl_lock       *sublock;
 355                 struct lov_lock_link *link;
 356
 357                 if (lck->lls_sub[i].sub_lock == NULL) {
 358                         sublock = lov_sublock_alloc(env, io, lck, i, &link);
 359                         if (IS_ERR(sublock)) {
 360                                 result = PTR_ERR(sublock);
 361                                 break;
 362                         }
 363                         cl_lock_get_trust(sublock);
 364                         cl_lock_mutex_get(env, sublock);
 365                         cl_lock_mutex_get(env, parent);
 366                         /*
 367                          * recheck under mutex that sub-lock wasn't created
 368                          * concurrently, and that top-lock is still alive.
 369                          */
 370                         if (lck->lls_sub[i].sub_lock == NULL &&
 371                             parent->cll_state < CLS_FREEING) {
 372                                 lov_sublock_adopt(env, lck, sublock, i, link);
 373                                 cl_lock_mutex_put(env, parent);
 374                         } else {
 375                                 OBD_SLAB_FREE_PTR(link, lov_lock_link_kmem);
 376                                 cl_lock_mutex_put(env, parent);
 377                                 cl_lock_unhold(env, sublock,
 378                                                "lov-parent", parent);
 379                         }
 380                         cl_lock_mutex_put(env, sublock);
 381                         cl_lock_put(env, sublock);
 382                 }
 383         }
 384         /*
 385          * Some sub-locks can be missing at this point. This is not a problem,
 386          * because enqueue will create them anyway. Main duty of this function
 387          * is to fill in sub-lock descriptions in a race free manner.
 388          */
 389         return result;
 390 }
 391
 392 static int lov_sublock_release(const struct lu_env *env, struct lov_lock *lck,
 393                                int i, int deluser, int rc)
 394 {
 395         struct cl_lock *parent = lck->lls_cl.cls_lock;
 396
 397         LASSERT(cl_lock_is_mutexed(parent));
 398
 399         if (lck->lls_sub[i].sub_flags & LSF_HELD) {
 400                 struct cl_lock    *sublock;
 401                 int dying;
 402
 403                 LASSERT(lck->lls_sub[i].sub_lock != NULL);
 404                 sublock = lck->lls_sub[i].sub_lock->lss_cl.cls_lock;
 405                 LASSERT(cl_lock_is_mutexed(sublock));
 406
 407                 lck->lls_sub[i].sub_flags &= ~LSF_HELD;
 408                 if (deluser)
 409                         cl_lock_user_del(env, sublock);
 410                 /*
 411                  * If the last hold is released, and cancellation is pending
 412                  * for a sub-lock, release parent mutex, to avoid keeping it
 413                  * while sub-lock is being paged out.
 414                  */
 415                 dying = (sublock->cll_descr.cld_mode == CLM_PHANTOM ||
 416                          sublock->cll_descr.cld_mode == CLM_GROUP ||
 417                          (sublock->cll_flags & (CLF_CANCELPEND|CLF_DOOMED))) &&
 418                         sublock->cll_holds == 1;
 419                 if (dying)
 420                         cl_lock_mutex_put(env, parent);
 421                 cl_lock_unhold(env, sublock, "lov-parent", parent);
 422                 if (dying) {
 423                         cl_lock_mutex_get(env, parent);
 424                         rc = lov_subresult(rc, CLO_REPEAT);
 425                 }
 426                 /*
 427                  * From now on lck->lls_sub[i].sub_lock is a "weak" pointer,
 428                  * not backed by a reference on a
 429                  * sub-lock. lovsub_lock_delete() will clear
 430                  * lck->lls_sub[i].sub_lock under semaphores, just before
 431                  * sub-lock is destroyed.
 432                  */
 433         }
 434         return rc;
 435 }
 436
 437 static void lov_sublock_hold(const struct lu_env *env, struct lov_lock *lck,
 438                              int i)
 439 {
 440         struct cl_lock *parent = lck->lls_cl.cls_lock;
 441
 442         LASSERT(cl_lock_is_mutexed(parent));
 443
 444         if (!(lck->lls_sub[i].sub_flags & LSF_HELD)) {
 445                 struct cl_lock *sublock;
 446
 447                 LASSERT(lck->lls_sub[i].sub_lock != NULL);
 448                 sublock = lck->lls_sub[i].sub_lock->lss_cl.cls_lock;
 449                 LASSERT(cl_lock_is_mutexed(sublock));
 450                 LASSERT(sublock->cll_state != CLS_FREEING);
 451
 452                 lck->lls_sub[i].sub_flags |= LSF_HELD;
 453
 454                 cl_lock_get_trust(sublock);
 455                 cl_lock_hold_add(env, sublock, "lov-parent", parent);
 456                 cl_lock_user_add(env, sublock);
 457                 cl_lock_put(env, sublock);
 458         }
 459 }
 460
 461 static void lov_lock_fini(const struct lu_env *env,
 462                           struct cl_lock_slice *slice)
 463 {
 464         struct lov_lock *lck;
 465         int i;
 466
 467         lck = cl2lov_lock(slice);
 468         LASSERT(lck->lls_nr_filled == 0);
 469         if (lck->lls_sub != NULL) {
 470                 for (i = 0; i < lck->lls_nr; ++i)
 471                         /*
 472                          * No sub-locks exists at this point, as sub-lock has
 473                          * a reference on its parent.
 474                          */
 475                         LASSERT(lck->lls_sub[i].sub_lock == NULL);
 476                 OBD_FREE_LARGE(lck->lls_sub,
 477                                lck->lls_nr * sizeof(lck->lls_sub[0]));
 478         }
 479         OBD_SLAB_FREE_PTR(lck, lov_lock_kmem);
 480 }
 481
 482 static int lov_lock_enqueue_wait(const struct lu_env *env,
 483                                  struct lov_lock *lck,
 484                                  struct cl_lock *sublock)
 485 {
 486         struct cl_lock *lock = lck->lls_cl.cls_lock;
 487         int          result;
 488
 489         LASSERT(cl_lock_is_mutexed(lock));
 490
 491         cl_lock_mutex_put(env, lock);
 492         result = cl_lock_enqueue_wait(env, sublock, 0);
 493         cl_lock_mutex_get(env, lock);
 494         return result ?: CLO_REPEAT;
 495 }
 496
 497 /**
 498  * Tries to advance a state machine of a given sub-lock toward enqueuing of
 499  * the top-lock.
 500  *
 501  * \retval 0 if state-transition can proceed
 502  * \retval -ve otherwise.
 503  */
 504 static int lov_lock_enqueue_one(const struct lu_env *env, struct lov_lock *lck,
 505                                 struct cl_lock *sublock,
 506                                 struct cl_io *io, __u32 enqflags, int last)
 507 {
 508         int result;
 509
 510         /* first, try to enqueue a sub-lock ... */
 511         result = cl_enqueue_try(env, sublock, io, enqflags);
 512         if ((sublock->cll_state == CLS_ENQUEUED) && !(enqflags & CEF_AGL)) {
 513                 /* if it is enqueued, try to `wait' on it---maybe it's already
 514                  * granted */
 515                 result = cl_wait_try(env, sublock);
 516                 if (result == CLO_REENQUEUED)
 517                         result = CLO_WAIT;
 518         }
 519         /*
 520          * If CEF_ASYNC flag is set, then all sub-locks can be enqueued in
 521          * parallel, otherwise---enqueue has to wait until sub-lock is granted
 522          * before proceeding to the next one.
 523          */
 524         if ((result == CLO_WAIT) && (sublock->cll_state <= CLS_HELD) &&
 525             (enqflags & CEF_ASYNC) && (!last || (enqflags & CEF_AGL)))
 526                 result = 0;
 527         return result;
 528 }
 529
 530 /**
 531  * Helper function for lov_lock_enqueue() that creates missing sub-lock.
 532  */
 533 static int lov_sublock_fill(const struct lu_env *env, struct cl_lock *parent,
 534                             struct cl_io *io, struct lov_lock *lck, int idx)
 535 {
 536         struct lov_lock_link *link;
 537         struct cl_lock       *sublock;
 538         int                result;
 539
 540         LASSERT(parent->cll_depth == 1);
 541         cl_lock_mutex_put(env, parent);
 542         sublock = lov_sublock_alloc(env, io, lck, idx, &link);
 543         if (!IS_ERR(sublock))
 544                 cl_lock_mutex_get(env, sublock);
 545         cl_lock_mutex_get(env, parent);
 546
 547         if (!IS_ERR(sublock)) {
 548                 cl_lock_get_trust(sublock);
 549                 if (parent->cll_state == CLS_QUEUING &&
 550                     lck->lls_sub[idx].sub_lock == NULL) {
 551                         lov_sublock_adopt(env, lck, sublock, idx, link);
 552                 } else {
 553                         OBD_SLAB_FREE_PTR(link, lov_lock_link_kmem);
 554                         /* other thread allocated sub-lock, or enqueue is no
 555                          * longer going on */
 556                         cl_lock_mutex_put(env, parent);
 557                         cl_lock_unhold(env, sublock, "lov-parent", parent);
 558                         cl_lock_mutex_get(env, parent);
 559                 }
 560                 cl_lock_mutex_put(env, sublock);
 561                 cl_lock_put(env, sublock);
 562                 result = CLO_REPEAT;
 563         } else
 564                 result = PTR_ERR(sublock);
 565         return result;
 566 }
 567
 568 /**
 569  * Implementation of cl_lock_operations::clo_enqueue() for lov layer. This
 570  * function is rather subtle, as it enqueues top-lock (i.e., advances top-lock
 571  * state machine from CLS_QUEUING to CLS_ENQUEUED states) by juggling sub-lock
 572  * state machines in the face of sub-locks sharing (by multiple top-locks),
 573  * and concurrent sub-lock cancellations.
 574  */
 575 static int lov_lock_enqueue(const struct lu_env *env,
 576                             const struct cl_lock_slice *slice,
 577                             struct cl_io *io, __u32 enqflags)
 578 {
 579         struct cl_lock   *lock    = slice->cls_lock;
 580         struct lov_lock *lck     = cl2lov_lock(slice);
 581         struct cl_lock_closure *closure = lov_closure_get(env, lock);
 582         int i;
 583         int result;
 584         enum cl_lock_state minstate;
 585
 586         for (result = 0, minstate = CLS_FREEING, i = 0; i < lck->lls_nr; ++i) {
 587                 int rc;
 588                 struct lovsub_lock     *sub;
 589                 struct lov_lock_sub    *lls;
 590                 struct cl_lock   *sublock;
 591                 struct lov_sublock_env *subenv;
 592
 593                 if (lock->cll_state != CLS_QUEUING) {
 594                         /*
 595                          * Lock might have left QUEUING state if previous
 596                          * iteration released its mutex. Stop enqueing in this
 597                          * case and let the upper layer to decide what to do.
 598                          */
 599                         LASSERT(i > 0 && result != 0);
 600                         break;
 601                 }
 602
 603                 lls = &lck->lls_sub[i];
 604                 sub = lls->sub_lock;
 605                 /*
 606                  * Sub-lock might have been canceled, while top-lock was
 607                  * cached.
 608                  */
 609                 if (sub == NULL) {
 610                         result = lov_sublock_fill(env, lock, io, lck, i);
 611                         /* lov_sublock_fill() released @lock mutex,
 612                          * restart. */
 613                         break;
 614                 }
 615                 sublock = sub->lss_cl.cls_lock;
 616                 rc = lov_sublock_lock(env, lck, lls, closure, &subenv);
 617                 if (rc == 0) {
 618                         lov_sublock_hold(env, lck, i);
 619                         rc = lov_lock_enqueue_one(subenv->lse_env, lck, sublock,
 620                                                   subenv->lse_io, enqflags,
 621                                                   i == lck->lls_nr - 1);
 622                         minstate = min(minstate, sublock->cll_state);
 623                         if (rc == CLO_WAIT) {
 624                                 switch (sublock->cll_state) {
 625                                 case CLS_QUEUING:
 626                                         /* take recursive mutex, the lock is
 627                                          * released in lov_lock_enqueue_wait.
 628                                          */
 629                                         cl_lock_mutex_get(env, sublock);
 630                                         lov_sublock_unlock(env, sub, closure,
 631                                                            subenv);
 632                                         rc = lov_lock_enqueue_wait(env, lck,
 633                                                                    sublock);
 634                                         break;
 635                                 case CLS_CACHED:
 636                                         cl_lock_get(sublock);
 637                                         /* take recursive mutex of sublock */
 638                                         cl_lock_mutex_get(env, sublock);
 639                                         /* need to release all locks in closure
 640                                          * otherwise it may deadlock. LU-2683.*/
 641                                         lov_sublock_unlock(env, sub, closure,
 642                                                            subenv);
 643                                         /* sublock and parent are held. */
 644                                         rc = lov_sublock_release(env, lck, i,
 645                                                                  1, rc);
 646                                         cl_lock_mutex_put(env, sublock);
 647                                         cl_lock_put(env, sublock);
 648                                         break;
 649                                 default:
 650                                         lov_sublock_unlock(env, sub, closure,
 651                                                            subenv);
 652                                         break;
 653                                 }
 654                         } else {
 655                                 LASSERT(sublock->cll_conflict == NULL);
 656                                 lov_sublock_unlock(env, sub, closure, subenv);
 657                         }
 658                 }
 659                 result = lov_subresult(result, rc);
 660                 if (result != 0)
 661                         break;
 662         }
 663         cl_lock_closure_fini(closure);
 664         return result ?: minstate >= CLS_ENQUEUED ? 0 : CLO_WAIT;
 665 }
 666
 667 static int lov_lock_unuse(const struct lu_env *env,
 668                           const struct cl_lock_slice *slice)
 669 {
 670         struct lov_lock *lck     = cl2lov_lock(slice);
 671         struct cl_lock_closure *closure = lov_closure_get(env, slice->cls_lock);
 672         int i;
 673         int result;
 674
 675         for (result = 0, i = 0; i < lck->lls_nr; ++i) {
 676                 int rc;
 677                 struct lovsub_lock     *sub;
 678                 struct cl_lock   *sublock;
 679                 struct lov_lock_sub    *lls;
 680                 struct lov_sublock_env *subenv;
 681
 682                 /* top-lock state cannot change concurrently, because single
 683                  * thread (one that released the last hold) carries unlocking
 684                  * to the completion. */
 685                 LASSERT(slice->cls_lock->cll_state == CLS_INTRANSIT);
 686                 lls = &lck->lls_sub[i];
 687                 sub = lls->sub_lock;
 688                 if (sub == NULL)
 689                         continue;
 690
 691                 sublock = sub->lss_cl.cls_lock;
 692                 rc = lov_sublock_lock(env, lck, lls, closure, &subenv);
 693                 if (rc == 0) {
 694                         if (lls->sub_flags & LSF_HELD) {
 695                                 LASSERT(sublock->cll_state == CLS_HELD ||
 696                                         sublock->cll_state == CLS_ENQUEUED);
 697                                 rc = cl_unuse_try(subenv->lse_env, sublock);
 698                                 rc = lov_sublock_release(env, lck, i, 0, rc);
 699                         }
 700                         lov_sublock_unlock(env, sub, closure, subenv);
 701                 }
 702                 result = lov_subresult(result, rc);
 703         }
 704
 705         if (result == 0 && lck->lls_cancel_race) {
 706                 lck->lls_cancel_race = 0;
 707                 result = -ESTALE;
 708         }
 709         cl_lock_closure_fini(closure);
 710         return result;
 711 }
 712
 713
 714 static void lov_lock_cancel(const struct lu_env *env,
 715                            const struct cl_lock_slice *slice)
 716 {
 717         struct lov_lock *lck     = cl2lov_lock(slice);
 718         struct cl_lock_closure *closure = lov_closure_get(env, slice->cls_lock);
 719         int i;
 720         int result;
 721
 722         for (result = 0, i = 0; i < lck->lls_nr; ++i) {
 723                 int rc;
 724                 struct lovsub_lock     *sub;
 725                 struct cl_lock   *sublock;
 726                 struct lov_lock_sub    *lls;
 727                 struct lov_sublock_env *subenv;
 728
 729                 /* top-lock state cannot change concurrently, because single
 730                  * thread (one that released the last hold) carries unlocking
 731                  * to the completion. */
 732                 lls = &lck->lls_sub[i];
 733                 sub = lls->sub_lock;
 734                 if (sub == NULL)
 735                         continue;
 736
 737                 sublock = sub->lss_cl.cls_lock;
 738                 rc = lov_sublock_lock(env, lck, lls, closure, &subenv);
 739                 if (rc == 0) {
 740                         if (!(lls->sub_flags & LSF_HELD)) {
 741                                 lov_sublock_unlock(env, sub, closure, subenv);
 742                                 continue;
 743                         }
 744
 745                         switch (sublock->cll_state) {
 746                         case CLS_HELD:
 747                                 rc = cl_unuse_try(subenv->lse_env, sublock);
 748                                 lov_sublock_release(env, lck, i, 0, 0);
 749                                 break;
 750                         default:
 751                                 lov_sublock_release(env, lck, i, 1, 0);
 752                                 break;
 753                         }
 754                         lov_sublock_unlock(env, sub, closure, subenv);
 755                 }
 756
 757                 if (rc == CLO_REPEAT) {
 758                         --i;
 759                         continue;
 760                 }
 761
 762                 result = lov_subresult(result, rc);
 763         }
 764
 765         if (result)
 766                 CL_LOCK_DEBUG(D_ERROR, env, slice->cls_lock,
 767                               "lov_lock_cancel fails with %d.\n", result);
 768
 769         cl_lock_closure_fini(closure);
 770 }
 771
 772 static int lov_lock_wait(const struct lu_env *env,
 773                          const struct cl_lock_slice *slice)
 774 {
 775         struct lov_lock *lck     = cl2lov_lock(slice);
 776         struct cl_lock_closure *closure = lov_closure_get(env, slice->cls_lock);
 777         enum cl_lock_state      minstate;
 778         int                  reenqueued;
 779         int                  result;
 780         int                  i;
 781
 782 again:
 783         for (result = 0, minstate = CLS_FREEING, i = 0, reenqueued = 0;
 784              i < lck->lls_nr; ++i) {
 785                 int rc;
 786                 struct lovsub_lock     *sub;
 787                 struct cl_lock   *sublock;
 788                 struct lov_lock_sub    *lls;
 789                 struct lov_sublock_env *subenv;
 790
 791                 lls = &lck->lls_sub[i];
 792                 sub = lls->sub_lock;
 793                 LASSERT(sub != NULL);
 794                 sublock = sub->lss_cl.cls_lock;
 795                 rc = lov_sublock_lock(env, lck, lls, closure, &subenv);
 796                 if (rc == 0) {
 797                         LASSERT(sublock->cll_state >= CLS_ENQUEUED);
 798                         if (sublock->cll_state < CLS_HELD)
 799                                 rc = cl_wait_try(env, sublock);
 800
 801                         minstate = min(minstate, sublock->cll_state);
 802                         lov_sublock_unlock(env, sub, closure, subenv);
 803                 }
 804                 if (rc == CLO_REENQUEUED) {
 805                         reenqueued++;
 806                         rc = 0;
 807                 }
 808                 result = lov_subresult(result, rc);
 809                 if (result != 0)
 810                         break;
 811         }
 812         /* Each sublock only can be reenqueued once, so will not loop for
 813          * ever. */
 814         if (result == 0 && reenqueued != 0)
 815                 goto again;
 816         cl_lock_closure_fini(closure);
 817         return result ?: minstate >= CLS_HELD ? 0 : CLO_WAIT;
 818 }
 819
 820 static int lov_lock_use(const struct lu_env *env,
 821                         const struct cl_lock_slice *slice)
 822 {
 823         struct lov_lock *lck     = cl2lov_lock(slice);
 824         struct cl_lock_closure *closure = lov_closure_get(env, slice->cls_lock);
 825         int                  result;
 826         int                  i;
 827
 828         LASSERT(slice->cls_lock->cll_state == CLS_INTRANSIT);
 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         /* for top lock, it's necessary to match enq flags otherwise it will
 994          * run into problem if a sublock is missing and reenqueue. */
 995         if (need->cld_enq_flags != lov->lls_orig.cld_enq_flags)
 996                 return 0;
 997
 998         if (need->cld_mode == CLM_GROUP)
 999                 /*
1000                  * always allow to match group lock.
1001                  */
1002                 result = cl_lock_ext_match(&lov->lls_orig, need);
1003         else if (lov->lls_nr == 1) {
1004                 struct cl_lock_descr *got = &lov->lls_sub[0].sub_got;
1005                 result = lov_lock_stripe_is_matching(env,
1006                                                      cl2lov(slice->cls_obj),
1007                                                      lov->lls_sub[0].sub_stripe,
1008                                                      got, need);
1009         } else if (io->ci_type != CIT_SETATTR && io->ci_type != CIT_MISC &&
1010                    !cl_io_is_append(io) && need->cld_mode != CLM_PHANTOM)
1011                 /*
1012                  * Multi-stripe locks are only suitable for `quick' IO and for
1013                  * glimpse.
1014                  */
1015                 result = 0;
1016         else
1017                 /*
1018                  * Most general case: multi-stripe existing lock, and
1019                  * (potentially) multi-stripe @need lock. Check that @need is
1020                  * covered by @lov's sub-locks.
1021                  *
1022                  * For now, ignore lock expansions made by the server, and
1023                  * match against original lock extent.
1024                  */
1025                 result = cl_lock_ext_match(&lov->lls_orig, need);
1026         CDEBUG(D_DLMTRACE, DDESCR"/"DDESCR" %d %d/%d: %d\n",
1027                PDESCR(&lov->lls_orig), PDESCR(&lov->lls_sub[0].sub_got),
1028                lov->lls_sub[0].sub_stripe, lov->lls_nr, lov_r0(obj)->lo_nr,
1029                result);
1030         return result;
1031 }
1032
1033 void lov_lock_unlink(const struct lu_env *env,
1034                      struct lov_lock_link *link, struct lovsub_lock *sub)
1035 {
1036         struct lov_lock *lck    = link->lll_super;
1037         struct cl_lock  *parent = lck->lls_cl.cls_lock;
1038
1039         LASSERT(cl_lock_is_mutexed(parent));
1040         LASSERT(cl_lock_is_mutexed(sub->lss_cl.cls_lock));
1041
1042         list_del_init(&link->lll_list);
1043         LASSERT(lck->lls_sub[link->lll_idx].sub_lock == sub);
1044         /* yank this sub-lock from parent's array */
1045         lck->lls_sub[link->lll_idx].sub_lock = NULL;
1046         LASSERT(lck->lls_nr_filled > 0);
1047         lck->lls_nr_filled--;
1048         lu_ref_del(&parent->cll_reference, "lov-child", sub->lss_cl.cls_lock);
1049         cl_lock_put(env, parent);
1050         OBD_SLAB_FREE_PTR(link, lov_lock_link_kmem);
1051 }
1052
1053 struct lov_lock_link *lov_lock_link_find(const struct lu_env *env,
1054                                          struct lov_lock *lck,
1055                                          struct lovsub_lock *sub)
1056 {
1057         struct lov_lock_link *scan;
1058
1059         LASSERT(cl_lock_is_mutexed(sub->lss_cl.cls_lock));
1060
1061         list_for_each_entry(scan, &sub->lss_parents, lll_list) {
1062                 if (scan->lll_super == lck)
1063                         return scan;
1064         }
1065         return NULL;
1066 }
1067
1068 /**
1069  * An implementation of cl_lock_operations::clo_delete() method. This is
1070  * invoked for "top-to-bottom" delete, when lock destruction starts from the
1071  * top-lock, e.g., as a result of inode destruction.
1072  *
1073  * Unlinks top-lock from all its sub-locks. Sub-locks are not deleted there:
1074  * this is done separately elsewhere:
1075  *
1076  *     - for inode destruction, lov_object_delete() calls cl_object_kill() for
1077  *       each sub-object, purging its locks;
1078  *
1079  *     - in other cases (e.g., a fatal error with a top-lock) sub-locks are
1080  *       left in the cache.
1081  */
1082 static void lov_lock_delete(const struct lu_env *env,
1083                             const struct cl_lock_slice *slice)
1084 {
1085         struct lov_lock *lck     = cl2lov_lock(slice);
1086         struct cl_lock_closure *closure = lov_closure_get(env, slice->cls_lock);
1087         struct lov_lock_link   *link;
1088         int                  rc;
1089         int                  i;
1090
1091         LASSERT(slice->cls_lock->cll_state == CLS_FREEING);
1092
1093         for (i = 0; i < lck->lls_nr; ++i) {
1094                 struct lov_lock_sub *lls = &lck->lls_sub[i];
1095                 struct lovsub_lock  *lsl = lls->sub_lock;
1096
1097                 if (lsl == NULL) /* already removed */
1098                         continue;
1099
1100                 rc = lov_sublock_lock(env, lck, lls, closure, NULL);
1101                 if (rc == CLO_REPEAT) {
1102                         --i;
1103                         continue;
1104                 }
1105
1106                 LASSERT(rc == 0);
1107                 LASSERT(lsl->lss_cl.cls_lock->cll_state < CLS_FREEING);
1108
1109                 if (lls->sub_flags & LSF_HELD)
1110                         lov_sublock_release(env, lck, i, 1, 0);
1111
1112                 link = lov_lock_link_find(env, lck, lsl);
1113                 LASSERT(link != NULL);
1114                 lov_lock_unlink(env, link, lsl);
1115                 LASSERT(lck->lls_sub[i].sub_lock == NULL);
1116
1117                 lov_sublock_unlock(env, lsl, closure, NULL);
1118         }
1119
1120         cl_lock_closure_fini(closure);
1121 }
1122
1123 static int lov_lock_print(const struct lu_env *env, void *cookie,
1124                           lu_printer_t p, const struct cl_lock_slice *slice)
1125 {
1126         struct lov_lock *lck = cl2lov_lock(slice);
1127         int           i;
1128
1129         (*p)(env, cookie, "%d\n", lck->lls_nr);
1130         for (i = 0; i < lck->lls_nr; ++i) {
1131                 struct lov_lock_sub *sub;
1132
1133                 sub = &lck->lls_sub[i];
1134                 (*p)(env, cookie, "    %d %x: ", i, sub->sub_flags);
1135                 if (sub->sub_lock != NULL)
1136                         cl_lock_print(env, cookie, p,
1137                                       sub->sub_lock->lss_cl.cls_lock);
1138                 else
1139                         (*p)(env, cookie, "---\n");
1140         }
1141         return 0;
1142 }
1143
1144 static const struct cl_lock_operations lov_lock_ops = {
1145         .clo_fini      = lov_lock_fini,
1146         .clo_enqueue   = lov_lock_enqueue,
1147         .clo_wait      = lov_lock_wait,
1148         .clo_use       = lov_lock_use,
1149         .clo_unuse     = lov_lock_unuse,
1150         .clo_cancel    = lov_lock_cancel,
1151         .clo_fits_into = lov_lock_fits_into,
1152         .clo_delete    = lov_lock_delete,
1153         .clo_print     = lov_lock_print
1154 };
1155
1156 int lov_lock_init_raid0(const struct lu_env *env, struct cl_object *obj,
1157                         struct cl_lock *lock, const struct cl_io *io)
1158 {
1159         struct lov_lock *lck;
1160         int result;
1161
1162         OBD_SLAB_ALLOC_PTR_GFP(lck, lov_lock_kmem, __GFP_IO);
1163         if (lck != NULL) {
1164                 cl_lock_slice_add(lock, &lck->lls_cl, obj, &lov_lock_ops);
1165                 result = lov_lock_sub_init(env, lck, io);
1166         } else
1167                 result = -ENOMEM;
1168         return result;
1169 }
1170
1171 static void lov_empty_lock_fini(const struct lu_env *env,
1172                                 struct cl_lock_slice *slice)
1173 {
1174         struct lov_lock *lck = cl2lov_lock(slice);
1175         OBD_SLAB_FREE_PTR(lck, lov_lock_kmem);
1176 }
1177
1178 static int lov_empty_lock_print(const struct lu_env *env, void *cookie,
1179                         lu_printer_t p, const struct cl_lock_slice *slice)
1180 {
1181         (*p)(env, cookie, "empty\n");
1182         return 0;
1183 }
1184
1185 /* XXX: more methods will be added later. */
1186 static const struct cl_lock_operations lov_empty_lock_ops = {
1187         .clo_fini  = lov_empty_lock_fini,
1188         .clo_print = lov_empty_lock_print
1189 };
1190
1191 int lov_lock_init_empty(const struct lu_env *env, struct cl_object *obj,
1192                 struct cl_lock *lock, const struct cl_io *io)
1193 {
1194         struct lov_lock *lck;
1195         int result = -ENOMEM;
1196
1197         OBD_SLAB_ALLOC_PTR_GFP(lck, lov_lock_kmem, __GFP_IO);
1198         if (lck != NULL) {
1199                 cl_lock_slice_add(lock, &lck->lls_cl, obj, &lov_empty_lock_ops);
1200                 lck->lls_orig = lock->cll_descr;
1201                 result = 0;
1202         }
1203         return result;
1204 }
1205
1206 static struct cl_lock_closure *lov_closure_get(const struct lu_env *env,
1207                                                struct cl_lock *parent)
1208 {
1209         struct cl_lock_closure *closure;
1210
1211         closure = &lov_env_info(env)->lti_closure;
1212         LASSERT(list_empty(&closure->clc_list));
1213         cl_lock_closure_init(env, closure, parent, 1);
1214         return closure;
1215 }
1216
1217
1218 /** @} lov */