lustre/lov/lov_lock.c

   1 /* -*- mode: c; c-basic-offset: 8; indent-tabs-mode: nil; -*-
   2  * vim:expandtab:shiftwidth=8:tabstop=8:
   3  *
   4  * GPL HEADER START
   5  *
   6  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 only,
  10  * as published by the Free Software Foundation.
  11  *
  12  * This program is distributed in the hope that it will be useful, but
  13  * WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * General Public License version 2 for more details (a copy is included
  16  * in the LICENSE file that accompanied this code).
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * version 2 along with this program; If not, see
  20  * http://www.sun.com/software/products/lustre/docs/GPLv2.pdf
  21  *
  22  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
  23  * CA 95054 USA or visit www.sun.com if you need additional information or
  24  * have any questions.
  25  *
  26  * GPL HEADER END
  27  */
  28 /*
  29  * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
  30  * Use is subject to license terms.
  31  *
  32  * Copyright (c) 2011, 2012, Whamcloud, Inc.
  33  */
  34 /*
  35  * This file is part of Lustre, http://www.lustre.org/
  36  * Lustre is a trademark of Sun Microsystems, Inc.
  37  *
  38  * Implementation of cl_lock for LOV layer.
  39  *
  40  *   Author: Nikita Danilov <nikita.danilov@sun.com>
  41  */
  42
  43 #define DEBUG_SUBSYSTEM S_LOV
  44
  45 #include "lov_cl_internal.h"
  46
  47 /** \addtogroup lov
  48  *  @{
  49  */
  50
  51 static struct cl_lock_closure *lov_closure_get(const struct lu_env *env,
  52                                                struct cl_lock *parent);
  53
  54 static int lov_lock_unuse(const struct lu_env *env,
  55                           const struct cl_lock_slice *slice);
  56 /*****************************************************************************
  57  *
  58  * Lov lock operations.
  59  *
  60  */
  61
  62 static struct lov_sublock_env *lov_sublock_env_get(const struct lu_env *env,
  63                                                    struct cl_lock *parent,
  64                                                    struct lov_lock_sub *lls)
  65 {
  66         struct lov_sublock_env *subenv;
  67         struct lov_io          *lio    = lov_env_io(env);
  68         struct cl_io           *io     = lio->lis_cl.cis_io;
  69         struct lov_io_sub      *sub;
  70
  71         subenv = &lov_env_session(env)->ls_subenv;
  72
  73         /*
  74          * FIXME: We tend to use the subio's env & io to call the sublock
  75          * lock operations because osc lock sometimes stores some control
  76          * variables in thread's IO infomation(Now only lockless information).
  77          * However, if the lock's host(object) is different from the object
  78          * for current IO, we have no way to get the subenv and subio because
  79          * they are not initialized at all. As a temp fix, in this case,
  80          * we still borrow the parent's env to call sublock operations.
  81          */
  82         if (!io || !cl_object_same(io->ci_obj, parent->cll_descr.cld_obj)) {
  83                 subenv->lse_env = env;
  84                 subenv->lse_io  = io;
  85                 subenv->lse_sub = NULL;
  86         } else {
  87                 sub = lov_sub_get(env, lio, lls->sub_stripe);
  88                 if (!IS_ERR(sub)) {
  89                         subenv->lse_env = sub->sub_env;
  90                         subenv->lse_io  = sub->sub_io;
  91                         subenv->lse_sub = sub;
  92                 } else {
  93                         subenv = (void*)sub;
  94                 }
  95         }
  96         return subenv;
  97 }
  98
  99 static void lov_sublock_env_put(struct lov_sublock_env *subenv)
 100 {
 101         if (subenv && subenv->lse_sub)
 102                 lov_sub_put(subenv->lse_sub);
 103 }
 104
 105 static void lov_sublock_adopt(const struct lu_env *env, struct lov_lock *lck,
 106                               struct cl_lock *sublock, int idx,
 107                               struct lov_lock_link *link)
 108 {
 109         struct lovsub_lock *lsl;
 110         struct cl_lock     *parent = lck->lls_cl.cls_lock;
 111         int                 rc;
 112
 113         LASSERT(cl_lock_is_mutexed(parent));
 114         LASSERT(cl_lock_is_mutexed(sublock));
 115         ENTRY;
 116
 117         lsl = cl2sub_lock(sublock);
 118         /*
 119          * check that sub-lock doesn't have lock link to this top-lock.
 120          */
 121         LASSERT(lov_lock_link_find(env, lck, lsl) == NULL);
 122         LASSERT(idx < lck->lls_nr);
 123
 124         lck->lls_sub[idx].sub_lock = lsl;
 125         lck->lls_nr_filled++;
 126         LASSERT(lck->lls_nr_filled <= lck->lls_nr);
 127         cfs_list_add_tail(&link->lll_list, &lsl->lss_parents);
 128         link->lll_idx = idx;
 129         link->lll_super = lck;
 130         cl_lock_get(parent);
 131         lu_ref_add(&parent->cll_reference, "lov-child", sublock);
 132         lck->lls_sub[idx].sub_flags |= LSF_HELD;
 133         cl_lock_user_add(env, sublock);
 134
 135         rc = lov_sublock_modify(env, lck, lsl, &sublock->cll_descr, idx);
 136         LASSERT(rc == 0); /* there is no way this can fail, currently */
 137         EXIT;
 138 }
 139
 140 static struct cl_lock *lov_sublock_alloc(const struct lu_env *env,
 141                                          const struct cl_io *io,
 142                                          struct lov_lock *lck,
 143                                          int idx, struct lov_lock_link **out)
 144 {
 145         struct cl_lock       *sublock;
 146         struct cl_lock       *parent;
 147         struct lov_lock_link *link;
 148
 149         LASSERT(idx < lck->lls_nr);
 150         ENTRY;
 151
 152         OBD_SLAB_ALLOC_PTR_GFP(link, lov_lock_link_kmem, CFS_ALLOC_IO);
 153         if (link != NULL) {
 154                 struct lov_sublock_env *subenv;
 155                 struct lov_lock_sub  *lls;
 156                 struct cl_lock_descr *descr;
 157
 158                 parent = lck->lls_cl.cls_lock;
 159                 lls    = &lck->lls_sub[idx];
 160                 descr  = &lls->sub_descr;
 161
 162                 subenv = lov_sublock_env_get(env, parent, lls);
 163                 if (!IS_ERR(subenv)) {
 164                         /* CAVEAT: Don't try to add a field in lov_lock_sub
 165                          * to remember the subio. This is because lock is able
 166                          * to be cached, but this is not true for IO. This
 167                          * further means a sublock might be referenced in
 168                          * different io context. -jay */
 169
 170                         sublock = cl_lock_hold(subenv->lse_env, subenv->lse_io,
 171                                                descr, "lov-parent", parent);
 172                         lov_sublock_env_put(subenv);
 173                 } else {
 174                         /* error occurs. */
 175                         sublock = (void*)subenv;
 176                 }
 177
 178                 if (!IS_ERR(sublock))
 179                         *out = link;
 180                 else
 181                         OBD_SLAB_FREE_PTR(link, lov_lock_link_kmem);
 182         } else
 183                 sublock = ERR_PTR(-ENOMEM);
 184         RETURN(sublock);
 185 }
 186
 187 static void lov_sublock_unlock(const struct lu_env *env,
 188                                struct lovsub_lock *lsl,
 189                                struct cl_lock_closure *closure,
 190                                struct lov_sublock_env *subenv)
 191 {
 192         ENTRY;
 193         lov_sublock_env_put(subenv);
 194         lsl->lss_active = NULL;
 195         cl_lock_disclosure(env, closure);
 196         EXIT;
 197 }
 198
 199 static int lov_sublock_lock(const struct lu_env *env,
 200                             struct lov_lock *lck,
 201                             struct lov_lock_sub *lls,
 202                             struct cl_lock_closure *closure,
 203                             struct lov_sublock_env **lsep)
 204 {
 205         struct lovsub_lock *sublock;
 206         struct cl_lock     *child;
 207         int                 result = 0;
 208         ENTRY;
 209
 210         LASSERT(cfs_list_empty(&closure->clc_list));
 211
 212         sublock = lls->sub_lock;
 213         child = sublock->lss_cl.cls_lock;
 214         result = cl_lock_closure_build(env, child, closure);
 215         if (result == 0) {
 216                 struct cl_lock *parent = closure->clc_origin;
 217
 218                 LASSERT(cl_lock_is_mutexed(child));
 219                 sublock->lss_active = parent;
 220
 221                 if (unlikely((child->cll_state == CLS_FREEING) ||
 222                              (child->cll_flags & CLF_CANCELLED))) {
 223                         struct lov_lock_link *link;
 224                         /*
 225                          * we could race with lock deletion which temporarily
 226                          * put the lock in freeing state, bug 19080.
 227                          */
 228                         LASSERT(!(lls->sub_flags & LSF_HELD));
 229
 230                         link = lov_lock_link_find(env, lck, sublock);
 231                         LASSERT(link != NULL);
 232                         lov_lock_unlink(env, link, sublock);
 233                         lov_sublock_unlock(env, sublock, closure, NULL);
 234                         lck->lls_cancel_race = 1;
 235                         result = CLO_REPEAT;
 236                 } else if (lsep) {
 237                         struct lov_sublock_env *subenv;
 238                         subenv = lov_sublock_env_get(env, parent, lls);
 239                         if (IS_ERR(subenv)) {
 240                                 lov_sublock_unlock(env, sublock,
 241                                                    closure, NULL);
 242                                 result = PTR_ERR(subenv);
 243                         } else {
 244                                 *lsep = subenv;
 245                         }
 246                 }
 247         }
 248         RETURN(result);
 249 }
 250
 251 /**
 252  * Updates the result of a top-lock operation from a result of sub-lock
 253  * sub-operations. Top-operations like lov_lock_{enqueue,use,unuse}() iterate
 254  * over sub-locks and lov_subresult() is used to calculate return value of a
 255  * top-operation. To this end, possible return values of sub-operations are
 256  * ordered as
 257  *
 258  *     - 0                  success
 259  *     - CLO_WAIT           wait for event
 260  *     - CLO_REPEAT         repeat top-operation
 261  *     - -ne                fundamental error
 262  *
 263  * Top-level return code can only go down through this list. CLO_REPEAT
 264  * overwrites CLO_WAIT, because lock mutex was released and sleeping condition
 265  * has to be rechecked by the upper layer.
 266  */
 267 static int lov_subresult(int result, int rc)
 268 {
 269         int result_rank;
 270         int rc_rank;
 271
 272         ENTRY;
 273
 274         LASSERT(result <= 0 || result == CLO_REPEAT || result == CLO_WAIT);
 275         LASSERT(rc <= 0 || rc == CLO_REPEAT || rc == CLO_WAIT);
 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(r0->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(r0->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          * Then, create sub-locks. Once at least one sub-lock was created,
 361          * top-lock can be reached by other threads.
 362          */
 363         for (i = 0; i < lck->lls_nr; ++i) {
 364                 struct cl_lock       *sublock;
 365                 struct lov_lock_link *link;
 366
 367                 if (lck->lls_sub[i].sub_lock == NULL) {
 368                         sublock = lov_sublock_alloc(env, io, lck, i, &link);
 369                         if (IS_ERR(sublock)) {
 370                                 result = PTR_ERR(sublock);
 371                                 break;
 372                         }
 373                         cl_lock_get_trust(sublock);
 374                         cl_lock_mutex_get(env, sublock);
 375                         cl_lock_mutex_get(env, parent);
 376                         /*
 377                          * recheck under mutex that sub-lock wasn't created
 378                          * concurrently, and that top-lock is still alive.
 379                          */
 380                         if (lck->lls_sub[i].sub_lock == NULL &&
 381                             parent->cll_state < CLS_FREEING) {
 382                                 lov_sublock_adopt(env, lck, sublock, i, link);
 383                                 cl_lock_mutex_put(env, parent);
 384                         } else {
 385                                 OBD_SLAB_FREE_PTR(link, lov_lock_link_kmem);
 386                                 cl_lock_mutex_put(env, parent);
 387                                 cl_lock_unhold(env, sublock,
 388                                                "lov-parent", parent);
 389                         }
 390                         cl_lock_mutex_put(env, sublock);
 391                         cl_lock_put(env, sublock);
 392                 }
 393         }
 394         /*
 395          * Some sub-locks can be missing at this point. This is not a problem,
 396          * because enqueue will create them anyway. Main duty of this function
 397          * is to fill in sub-lock descriptions in a race free manner.
 398          */
 399         RETURN(result);
 400 }
 401
 402 static int lov_sublock_release(const struct lu_env *env, struct lov_lock *lck,
 403                                int i, int deluser, int rc)
 404 {
 405         struct cl_lock *parent = lck->lls_cl.cls_lock;
 406
 407         LASSERT(cl_lock_is_mutexed(parent));
 408         ENTRY;
 409
 410         if (lck->lls_sub[i].sub_flags & LSF_HELD) {
 411                 struct cl_lock    *sublock;
 412                 int dying;
 413
 414                 LASSERT(lck->lls_sub[i].sub_lock != NULL);
 415                 sublock = lck->lls_sub[i].sub_lock->lss_cl.cls_lock;
 416                 LASSERT(cl_lock_is_mutexed(sublock));
 417
 418                 lck->lls_sub[i].sub_flags &= ~LSF_HELD;
 419                 if (deluser)
 420                         cl_lock_user_del(env, sublock);
 421                 /*
 422                  * If the last hold is released, and cancellation is pending
 423                  * for a sub-lock, release parent mutex, to avoid keeping it
 424                  * while sub-lock is being paged out.
 425                  */
 426                 dying = (sublock->cll_descr.cld_mode == CLM_PHANTOM ||
 427                          sublock->cll_descr.cld_mode == CLM_GROUP ||
 428                          (sublock->cll_flags & (CLF_CANCELPEND|CLF_DOOMED))) &&
 429                         sublock->cll_holds == 1;
 430                 if (dying)
 431                         cl_lock_mutex_put(env, parent);
 432                 cl_lock_unhold(env, sublock, "lov-parent", parent);
 433                 if (dying) {
 434                         cl_lock_mutex_get(env, parent);
 435                         rc = lov_subresult(rc, CLO_REPEAT);
 436                 }
 437                 /*
 438                  * From now on lck->lls_sub[i].sub_lock is a "weak" pointer,
 439                  * not backed by a reference on a
 440                  * sub-lock. lovsub_lock_delete() will clear
 441                  * lck->lls_sub[i].sub_lock under semaphores, just before
 442                  * sub-lock is destroyed.
 443                  */
 444         }
 445         RETURN(rc);
 446 }
 447
 448 static void lov_sublock_hold(const struct lu_env *env, struct lov_lock *lck,
 449                              int i)
 450 {
 451         struct cl_lock *parent = lck->lls_cl.cls_lock;
 452
 453         LASSERT(cl_lock_is_mutexed(parent));
 454         ENTRY;
 455
 456         if (!(lck->lls_sub[i].sub_flags & LSF_HELD)) {
 457                 struct cl_lock *sublock;
 458
 459                 LASSERT(lck->lls_sub[i].sub_lock != NULL);
 460                 sublock = lck->lls_sub[i].sub_lock->lss_cl.cls_lock;
 461                 LASSERT(cl_lock_is_mutexed(sublock));
 462                 LASSERT(sublock->cll_state != CLS_FREEING);
 463
 464                 lck->lls_sub[i].sub_flags |= LSF_HELD;
 465
 466                 cl_lock_get_trust(sublock);
 467                 cl_lock_hold_add(env, sublock, "lov-parent", parent);
 468                 cl_lock_user_add(env, sublock);
 469                 cl_lock_put(env, sublock);
 470         }
 471         EXIT;
 472 }
 473
 474 static void lov_lock_fini(const struct lu_env *env,
 475                           struct cl_lock_slice *slice)
 476 {
 477         struct lov_lock *lck;
 478         int i;
 479
 480         ENTRY;
 481         lck = cl2lov_lock(slice);
 482         LASSERT(lck->lls_nr_filled == 0);
 483         if (lck->lls_sub != NULL) {
 484                 for (i = 0; i < lck->lls_nr; ++i)
 485                         /*
 486                          * No sub-locks exists at this point, as sub-lock has
 487                          * a reference on its parent.
 488                          */
 489                         LASSERT(lck->lls_sub[i].sub_lock == NULL);
 490                 OBD_FREE_LARGE(lck->lls_sub,
 491                                lck->lls_nr * sizeof lck->lls_sub[0]);
 492         }
 493         OBD_SLAB_FREE_PTR(lck, lov_lock_kmem);
 494         EXIT;
 495 }
 496
 497 static int lov_lock_enqueue_wait(const struct lu_env *env,
 498                                  struct lov_lock *lck,
 499                                  struct cl_lock *sublock)
 500 {
 501         struct cl_lock *lock = lck->lls_cl.cls_lock;
 502         int             result;
 503         ENTRY;
 504
 505         LASSERT(cl_lock_is_mutexed(lock));
 506
 507         cl_lock_mutex_put(env, lock);
 508         result = cl_lock_enqueue_wait(env, sublock, 0);
 509         cl_lock_mutex_get(env, lock);
 510         RETURN(result ?: CLO_REPEAT);
 511 }
 512
 513 /**
 514  * Tries to advance a state machine of a given sub-lock toward enqueuing of
 515  * the top-lock.
 516  *
 517  * \retval 0 if state-transition can proceed
 518  * \retval -ve otherwise.
 519  */
 520 static int lov_lock_enqueue_one(const struct lu_env *env, struct lov_lock *lck,
 521                                 struct cl_lock *sublock,
 522                                 struct cl_io *io, __u32 enqflags, int last)
 523 {
 524         int result;
 525         ENTRY;
 526
 527         /* first, try to enqueue a sub-lock ... */
 528         result = cl_enqueue_try(env, sublock, io, enqflags);
 529         if ((sublock->cll_state == CLS_ENQUEUED) && !(enqflags & CEF_AGL))
 530                 /* if it is enqueued, try to `wait' on it---maybe it's already
 531                  * granted */
 532                 result = cl_wait_try(env, sublock);
 533         /*
 534          * If CEF_ASYNC flag is set, then all sub-locks can be enqueued in
 535          * parallel, otherwise---enqueue has to wait until sub-lock is granted
 536          * before proceeding to the next one.
 537          */
 538         if ((result == CLO_WAIT) && (sublock->cll_state <= CLS_HELD) &&
 539             (enqflags & CEF_ASYNC) && (!last || (enqflags & CEF_AGL)))
 540                 result = 0;
 541         RETURN(result);
 542 }
 543
 544 /**
 545  * Helper function for lov_lock_enqueue() that creates missing sub-lock.
 546  */
 547 static int lov_sublock_fill(const struct lu_env *env, struct cl_lock *parent,
 548                             struct cl_io *io, struct lov_lock *lck, int idx)
 549 {
 550         struct lov_lock_link *link;
 551         struct cl_lock       *sublock;
 552         int                   result;
 553
 554         LASSERT(parent->cll_depth == 1);
 555         cl_lock_mutex_put(env, parent);
 556         sublock = lov_sublock_alloc(env, io, lck, idx, &link);
 557         if (!IS_ERR(sublock))
 558                 cl_lock_mutex_get(env, sublock);
 559         cl_lock_mutex_get(env, parent);
 560
 561         if (!IS_ERR(sublock)) {
 562                 cl_lock_get_trust(sublock);
 563                 if (parent->cll_state == CLS_QUEUING &&
 564                     lck->lls_sub[idx].sub_lock == NULL) {
 565                         lov_sublock_adopt(env, lck, sublock, idx, link);
 566                 } else {
 567                         OBD_SLAB_FREE_PTR(link, lov_lock_link_kmem);
 568                         /* other thread allocated sub-lock, or enqueue is no
 569                          * longer going on */
 570                         cl_lock_mutex_put(env, parent);
 571                         cl_lock_unhold(env, sublock, "lov-parent", parent);
 572                         cl_lock_mutex_get(env, parent);
 573                 }
 574                 cl_lock_mutex_put(env, sublock);
 575                 cl_lock_put(env, sublock);
 576                 result = CLO_REPEAT;
 577         } else
 578                 result = PTR_ERR(sublock);
 579         return result;
 580 }
 581
 582 /**
 583  * Implementation of cl_lock_operations::clo_enqueue() for lov layer. This
 584  * function is rather subtle, as it enqueues top-lock (i.e., advances top-lock
 585  * state machine from CLS_QUEUING to CLS_ENQUEUED states) by juggling sub-lock
 586  * state machines in the face of sub-locks sharing (by multiple top-locks),
 587  * and concurrent sub-lock cancellations.
 588  */
 589 static int lov_lock_enqueue(const struct lu_env *env,
 590                             const struct cl_lock_slice *slice,
 591                             struct cl_io *io, __u32 enqflags)
 592 {
 593         struct cl_lock         *lock    = slice->cls_lock;
 594         struct lov_lock        *lck     = cl2lov_lock(slice);
 595         struct cl_lock_closure *closure = lov_closure_get(env, lock);
 596         int i;
 597         int result;
 598         enum cl_lock_state minstate;
 599
 600         ENTRY;
 601
 602         for (result = 0, minstate = CLS_FREEING, i = 0; i < lck->lls_nr; ++i) {
 603                 int rc;
 604                 struct lovsub_lock     *sub;
 605                 struct lov_lock_sub    *lls;
 606                 struct cl_lock         *sublock;
 607                 struct lov_sublock_env *subenv;
 608
 609                 if (lock->cll_state != CLS_QUEUING) {
 610                         /*
 611                          * Lock might have left QUEUING state if previous
 612                          * iteration released its mutex. Stop enqueing in this
 613                          * case and let the upper layer to decide what to do.
 614                          */
 615                         LASSERT(i > 0 && result != 0);
 616                         break;
 617                 }
 618
 619                 lls = &lck->lls_sub[i];
 620                 sub = lls->sub_lock;
 621                 /*
 622                  * Sub-lock might have been canceled, while top-lock was
 623                  * cached.
 624                  */
 625                 if (sub == NULL) {
 626                         result = lov_sublock_fill(env, lock, io, lck, i);
 627                         /* lov_sublock_fill() released @lock mutex,
 628                          * restart. */
 629                         break;
 630                 }
 631                 sublock = sub->lss_cl.cls_lock;
 632                 rc = lov_sublock_lock(env, lck, lls, closure, &subenv);
 633                 if (rc == 0) {
 634                         lov_sublock_hold(env, lck, i);
 635                         rc = lov_lock_enqueue_one(subenv->lse_env, lck, sublock,
 636                                                   subenv->lse_io, enqflags,
 637                                                   i == lck->lls_nr - 1);
 638                         minstate = min(minstate, sublock->cll_state);
 639                         if (rc == CLO_WAIT) {
 640                                 switch (sublock->cll_state) {
 641                                 case CLS_QUEUING:
 642                                         /* take recursive mutex, the lock is
 643                                          * released in lov_lock_enqueue_wait.
 644                                          */
 645                                         cl_lock_mutex_get(env, sublock);
 646                                         lov_sublock_unlock(env, sub, closure,
 647                                                            subenv);
 648                                         rc = lov_lock_enqueue_wait(env, lck,
 649                                                                    sublock);
 650                                         break;
 651                                 case CLS_CACHED:
 652                                         rc = lov_sublock_release(env, lck, i,
 653                                                                  1, rc);
 654                                 default:
 655                                         lov_sublock_unlock(env, sub, closure,
 656                                                            subenv);
 657                                         break;
 658                                 }
 659                         } else {
 660                                 LASSERT(sublock->cll_conflict == NULL);
 661                                 lov_sublock_unlock(env, sub, closure, subenv);
 662                         }
 663                 }
 664                 result = lov_subresult(result, rc);
 665                 if (result != 0)
 666                         break;
 667         }
 668         cl_lock_closure_fini(closure);
 669         RETURN(result ?: minstate >= CLS_ENQUEUED ? 0 : CLO_WAIT);
 670 }
 671
 672 static int lov_lock_unuse(const struct lu_env *env,
 673                           const struct cl_lock_slice *slice)
 674 {
 675         struct lov_lock        *lck     = cl2lov_lock(slice);
 676         struct cl_lock_closure *closure = lov_closure_get(env, slice->cls_lock);
 677         int i;
 678         int result;
 679
 680         ENTRY;
 681
 682         for (result = 0, i = 0; i < lck->lls_nr; ++i) {
 683                 int rc;
 684                 struct lovsub_lock     *sub;
 685                 struct cl_lock         *sublock;
 686                 struct lov_lock_sub    *lls;
 687                 struct lov_sublock_env *subenv;
 688
 689                 /* top-lock state cannot change concurrently, because single
 690                  * thread (one that released the last hold) carries unlocking
 691                  * to the completion. */
 692                 LASSERT(slice->cls_lock->cll_state == CLS_INTRANSIT);
 693                 lls = &lck->lls_sub[i];
 694                 sub = lls->sub_lock;
 695                 if (sub == NULL)
 696                         continue;
 697
 698                 sublock = sub->lss_cl.cls_lock;
 699                 rc = lov_sublock_lock(env, lck, lls, closure, &subenv);
 700                 if (rc == 0) {
 701                         if (lls->sub_flags & LSF_HELD) {
 702                                 LASSERT(sublock->cll_state == CLS_HELD ||
 703                                         sublock->cll_state == CLS_ENQUEUED);
 704                                 rc = cl_unuse_try(subenv->lse_env, sublock);
 705                                 rc = lov_sublock_release(env, lck, i, 0, rc);
 706                         }
 707                         lov_sublock_unlock(env, sub, closure, subenv);
 708                 }
 709                 result = lov_subresult(result, rc);
 710         }
 711
 712         if (result == 0 && lck->lls_cancel_race) {
 713                 lck->lls_cancel_race = 0;
 714                 result = -ESTALE;
 715         }
 716         cl_lock_closure_fini(closure);
 717         RETURN(result);
 718 }
 719
 720
 721 static void lov_lock_cancel(const struct lu_env *env,
 722                            const struct cl_lock_slice *slice)
 723 {
 724         struct lov_lock        *lck     = cl2lov_lock(slice);
 725         struct cl_lock_closure *closure = lov_closure_get(env, slice->cls_lock);
 726         int i;
 727         int result;
 728
 729         ENTRY;
 730
 731         for (result = 0, i = 0; i < lck->lls_nr; ++i) {
 732                 int rc;
 733                 struct lovsub_lock     *sub;
 734                 struct cl_lock         *sublock;
 735                 struct lov_lock_sub    *lls;
 736                 struct lov_sublock_env *subenv;
 737
 738                 /* top-lock state cannot change concurrently, because single
 739                  * thread (one that released the last hold) carries unlocking
 740                  * to the completion. */
 741                 lls = &lck->lls_sub[i];
 742                 sub = lls->sub_lock;
 743                 if (sub == NULL)
 744                         continue;
 745
 746                 sublock = sub->lss_cl.cls_lock;
 747                 rc = lov_sublock_lock(env, lck, lls, closure, &subenv);
 748                 if (rc == 0) {
 749                         if (!(lls->sub_flags & LSF_HELD)) {
 750                                 lov_sublock_unlock(env, sub, closure, subenv);
 751                                 continue;
 752                         }
 753
 754                         switch(sublock->cll_state) {
 755                         case CLS_HELD:
 756                                 rc = cl_unuse_try(subenv->lse_env,
 757                                                   sublock);
 758                                 lov_sublock_release(env, lck, i, 0, 0);
 759                                 break;
 760                         case CLS_ENQUEUED:
 761                                 /* TODO: it's not a good idea to cancel this
 762                                  * lock because it's innocent. But it's
 763                                  * acceptable. The better way would be to
 764                                  * define a new lock method to unhold the
 765                                  * dlm lock. */
 766                                 cl_lock_cancel(env, sublock);
 767                         default:
 768                                 lov_sublock_release(env, lck, i, 1, 0);
 769                                 break;
 770                         }
 771                         lov_sublock_unlock(env, sub, closure, subenv);
 772                 }
 773
 774                 if (rc == CLO_REPEAT) {
 775                         --i;
 776                         continue;
 777                 }
 778
 779                 result = lov_subresult(result, rc);
 780         }
 781
 782         if (result)
 783                 CL_LOCK_DEBUG(D_ERROR, env, slice->cls_lock,
 784                               "lov_lock_cancel fails with %d.\n", result);
 785
 786         cl_lock_closure_fini(closure);
 787 }
 788
 789 static int lov_lock_wait(const struct lu_env *env,
 790                          const struct cl_lock_slice *slice)
 791 {
 792         struct lov_lock        *lck     = cl2lov_lock(slice);
 793         struct cl_lock_closure *closure = lov_closure_get(env, slice->cls_lock);
 794         enum cl_lock_state      minstate;
 795         int                     reenqueued;
 796         int                     result;
 797         int                     i;
 798
 799         ENTRY;
 800
 801 again:
 802         for (result = 0, minstate = CLS_FREEING, i = 0, reenqueued = 0;
 803              i < lck->lls_nr; ++i) {
 804                 int rc;
 805                 struct lovsub_lock     *sub;
 806                 struct cl_lock         *sublock;
 807                 struct lov_lock_sub    *lls;
 808                 struct lov_sublock_env *subenv;
 809
 810                 lls = &lck->lls_sub[i];
 811                 sub = lls->sub_lock;
 812                 LASSERT(sub != NULL);
 813                 sublock = sub->lss_cl.cls_lock;
 814                 rc = lov_sublock_lock(env, lck, lls, closure, &subenv);
 815                 if (rc == 0) {
 816                         LASSERT(sublock->cll_state >= CLS_ENQUEUED);
 817                         if (sublock->cll_state < CLS_HELD)
 818                                 rc = cl_wait_try(env, sublock);
 819
 820                         minstate = min(minstate, sublock->cll_state);
 821                         lov_sublock_unlock(env, sub, closure, subenv);
 822                 }
 823                 if (rc == CLO_REENQUEUED) {
 824                         reenqueued++;
 825                         rc = 0;
 826                 }
 827                 result = lov_subresult(result, rc);
 828                 if (result != 0)
 829                         break;
 830         }
 831         /* Each sublock only can be reenqueued once, so will not loop for
 832          * ever. */
 833         if (result == 0 && reenqueued != 0)
 834                 goto again;
 835         cl_lock_closure_fini(closure);
 836         RETURN(result ?: minstate >= CLS_HELD ? 0 : CLO_WAIT);
 837 }
 838
 839 static int lov_lock_use(const struct lu_env *env,
 840                         const struct cl_lock_slice *slice)
 841 {
 842         struct lov_lock        *lck     = cl2lov_lock(slice);
 843         struct cl_lock_closure *closure = lov_closure_get(env, slice->cls_lock);
 844         int                     result;
 845         int                     i;
 846
 847         LASSERT(slice->cls_lock->cll_state == CLS_INTRANSIT);
 848         ENTRY;
 849
 850         for (result = 0, i = 0; i < lck->lls_nr; ++i) {
 851                 int rc;
 852                 struct lovsub_lock     *sub;
 853                 struct cl_lock         *sublock;
 854                 struct lov_lock_sub    *lls;
 855                 struct lov_sublock_env *subenv;
 856
 857                 LASSERT(slice->cls_lock->cll_state == CLS_INTRANSIT);
 858
 859                 lls = &lck->lls_sub[i];
 860                 sub = lls->sub_lock;
 861                 if (sub == NULL) {
 862                         /*
 863                          * Sub-lock might have been canceled, while top-lock was
 864                          * cached.
 865                          */
 866                         result = -ESTALE;
 867                         break;
 868                 }
 869
 870                 sublock = sub->lss_cl.cls_lock;
 871                 rc = lov_sublock_lock(env, lck, lls, closure, &subenv);
 872                 if (rc == 0) {
 873                         LASSERT(sublock->cll_state != CLS_FREEING);
 874                         lov_sublock_hold(env, lck, i);
 875                         if (sublock->cll_state == CLS_CACHED) {
 876                                 rc = cl_use_try(subenv->lse_env, sublock, 0);
 877                                 if (rc != 0)
 878                                         rc = lov_sublock_release(env, lck,
 879                                                                  i, 1, rc);
 880                         } else if (sublock->cll_state == CLS_NEW) {
 881                                 /* Sub-lock might have been canceled, while
 882                                  * top-lock was cached. */
 883                                 result = -ESTALE;
 884                                 lov_sublock_release(env, lck, i, 1, result);
 885                         }
 886                         lov_sublock_unlock(env, sub, closure, subenv);
 887                 }
 888                 result = lov_subresult(result, rc);
 889                 if (result != 0)
 890                         break;
 891         }
 892
 893         if (lck->lls_cancel_race) {
 894                 /*
 895                  * If there is unlocking happened at the same time, then
 896                  * sublock_lock state should be FREEING, and lov_sublock_lock
 897                  * should return CLO_REPEAT. In this case, it should return
 898                  * ESTALE, and up layer should reset the lock state to be NEW.
 899                  */
 900                 lck->lls_cancel_race = 0;
 901                 LASSERT(result != 0);
 902                 result = -ESTALE;
 903         }
 904         cl_lock_closure_fini(closure);
 905         RETURN(result);
 906 }
 907
 908 #if 0
 909 static int lock_lock_multi_match()
 910 {
 911         struct cl_lock          *lock    = slice->cls_lock;
 912         struct cl_lock_descr    *subneed = &lov_env_info(env)->lti_ldescr;
 913         struct lov_object       *loo     = cl2lov(lov->lls_cl.cls_obj);
 914         struct lov_layout_raid0 *r0      = lov_r0(loo);
 915         struct lov_lock_sub     *sub;
 916         struct cl_object        *subobj;
 917         obd_off  fstart;
 918         obd_off  fend;
 919         obd_off  start;
 920         obd_off  end;
 921         int i;
 922
 923         fstart = cl_offset(need->cld_obj, need->cld_start);
 924         fend   = cl_offset(need->cld_obj, need->cld_end + 1) - 1;
 925         subneed->cld_mode = need->cld_mode;
 926         cl_lock_mutex_get(env, lock);
 927         for (i = 0; i < lov->lls_nr; ++i) {
 928                 sub = &lov->lls_sub[i];
 929                 if (sub->sub_lock == NULL)
 930                         continue;
 931                 subobj = sub->sub_descr.cld_obj;
 932                 if (!lov_stripe_intersects(r0->lo_lsm, sub->sub_stripe,
 933                                            fstart, fend, &start, &end))
 934                         continue;
 935                 subneed->cld_start = cl_index(subobj, start);
 936                 subneed->cld_end   = cl_index(subobj, end);
 937                 subneed->cld_obj   = subobj;
 938                 if (!cl_lock_ext_match(&sub->sub_got, subneed)) {
 939                         result = 0;
 940                         break;
 941                 }
 942         }
 943         cl_lock_mutex_put(env, lock);
 944 }
 945 #endif
 946
 947 /**
 948  * Check if the extent region \a descr is covered by \a child against the
 949  * specific \a stripe.
 950  */
 951 static int lov_lock_stripe_is_matching(const struct lu_env *env,
 952                                        struct lov_object *lov, int stripe,
 953                                        const struct cl_lock_descr *child,
 954                                        const struct cl_lock_descr *descr)
 955 {
 956         struct lov_stripe_md *lsm = lov_r0(lov)->lo_lsm;
 957         obd_off start;
 958         obd_off end;
 959         int result;
 960
 961         if (lov_r0(lov)->lo_nr == 1)
 962                 return cl_lock_ext_match(child, descr);
 963
 964         /*
 965          * For a multi-stripes object:
 966          * - make sure the descr only covers child's stripe, and
 967          * - check if extent is matching.
 968          */
 969         start = cl_offset(&lov->lo_cl, descr->cld_start);
 970         end   = cl_offset(&lov->lo_cl, descr->cld_end + 1) - 1;
 971         result = end - start <= lsm->lsm_stripe_size &&
 972                  stripe == lov_stripe_number(lsm, start) &&
 973                  stripe == lov_stripe_number(lsm, end);
 974         if (result) {
 975                 struct cl_lock_descr *subd = &lov_env_info(env)->lti_ldescr;
 976                 obd_off sub_start;
 977                 obd_off sub_end;
 978
 979                 subd->cld_obj  = NULL;   /* don't need sub object at all */
 980                 subd->cld_mode = descr->cld_mode;
 981                 subd->cld_gid  = descr->cld_gid;
 982                 result = lov_stripe_intersects(lsm, stripe, start, end,
 983                                                &sub_start, &sub_end);
 984                 LASSERT(result);
 985                 subd->cld_start = cl_index(child->cld_obj, sub_start);
 986                 subd->cld_end   = cl_index(child->cld_obj, sub_end);
 987                 result = cl_lock_ext_match(child, subd);
 988         }
 989         return result;
 990 }
 991
 992 /**
 993  * An implementation of cl_lock_operations::clo_fits_into() method.
 994  *
 995  * Checks whether a lock (given by \a slice) is suitable for \a
 996  * io. Multi-stripe locks can be used only for "quick" io, like truncate, or
 997  * O_APPEND write.
 998  *
 999  * \see ccc_lock_fits_into().
1000  */
1001 static int lov_lock_fits_into(const struct lu_env *env,
1002                               const struct cl_lock_slice *slice,
1003                               const struct cl_lock_descr *need,
1004                               const struct cl_io *io)
1005 {
1006         struct lov_lock   *lov = cl2lov_lock(slice);
1007         struct lov_object *obj = cl2lov(slice->cls_obj);
1008         int result;
1009
1010         LASSERT(cl_object_same(need->cld_obj, slice->cls_obj));
1011         LASSERT(lov->lls_nr > 0);
1012
1013         ENTRY;
1014
1015         if (need->cld_mode == CLM_GROUP)
1016                 /*
1017                  * always allow to match group lock.
1018                  */
1019                 result = cl_lock_ext_match(&lov->lls_orig, need);
1020         else if (lov->lls_nr == 1) {
1021                 struct cl_lock_descr *got = &lov->lls_sub[0].sub_got;
1022                 result = lov_lock_stripe_is_matching(env,
1023                                                      cl2lov(slice->cls_obj),
1024                                                      lov->lls_sub[0].sub_stripe,
1025                                                      got, need);
1026         } else if (io->ci_type != CIT_SETATTR && io->ci_type != CIT_MISC &&
1027                    !cl_io_is_append(io) && need->cld_mode != CLM_PHANTOM)
1028                 /*
1029                  * Multi-stripe locks are only suitable for `quick' IO and for
1030                  * glimpse.
1031                  */
1032                 result = 0;
1033         else
1034                 /*
1035                  * Most general case: multi-stripe existing lock, and
1036                  * (potentially) multi-stripe @need lock. Check that @need is
1037                  * covered by @lov's sub-locks.
1038                  *
1039                  * For now, ignore lock expansions made by the server, and
1040                  * match against original lock extent.
1041                  */
1042                 result = cl_lock_ext_match(&lov->lls_orig, need);
1043         CDEBUG(D_DLMTRACE, DDESCR"/"DDESCR" %d %d/%d: %d\n",
1044                PDESCR(&lov->lls_orig), PDESCR(&lov->lls_sub[0].sub_got),
1045                lov->lls_sub[0].sub_stripe, lov->lls_nr, lov_r0(obj)->lo_nr,
1046                result);
1047         RETURN(result);
1048 }
1049
1050 void lov_lock_unlink(const struct lu_env *env,
1051                      struct lov_lock_link *link, struct lovsub_lock *sub)
1052 {
1053         struct lov_lock *lck    = link->lll_super;
1054         struct cl_lock  *parent = lck->lls_cl.cls_lock;
1055
1056         LASSERT(cl_lock_is_mutexed(parent));
1057         LASSERT(cl_lock_is_mutexed(sub->lss_cl.cls_lock));
1058         ENTRY;
1059
1060         cfs_list_del_init(&link->lll_list);
1061         LASSERT(lck->lls_sub[link->lll_idx].sub_lock == sub);
1062         /* yank this sub-lock from parent's array */
1063         lck->lls_sub[link->lll_idx].sub_lock = NULL;
1064         LASSERT(lck->lls_nr_filled > 0);
1065         lck->lls_nr_filled--;
1066         lu_ref_del(&parent->cll_reference, "lov-child", sub->lss_cl.cls_lock);
1067         cl_lock_put(env, parent);
1068         OBD_SLAB_FREE_PTR(link, lov_lock_link_kmem);
1069         EXIT;
1070 }
1071
1072 struct lov_lock_link *lov_lock_link_find(const struct lu_env *env,
1073                                          struct lov_lock *lck,
1074                                          struct lovsub_lock *sub)
1075 {
1076         struct lov_lock_link *scan;
1077
1078         LASSERT(cl_lock_is_mutexed(sub->lss_cl.cls_lock));
1079         ENTRY;
1080
1081         cfs_list_for_each_entry(scan, &sub->lss_parents, lll_list) {
1082                 if (scan->lll_super == lck)
1083                         RETURN(scan);
1084         }
1085         RETURN(NULL);
1086 }
1087
1088 /**
1089  * An implementation of cl_lock_operations::clo_delete() method. This is
1090  * invoked for "top-to-bottom" delete, when lock destruction starts from the
1091  * top-lock, e.g., as a result of inode destruction.
1092  *
1093  * Unlinks top-lock from all its sub-locks. Sub-locks are not deleted there:
1094  * this is done separately elsewhere:
1095  *
1096  *     - for inode destruction, lov_object_delete() calls cl_object_kill() for
1097  *       each sub-object, purging its locks;
1098  *
1099  *     - in other cases (e.g., a fatal error with a top-lock) sub-locks are
1100  *       left in the cache.
1101  */
1102 static void lov_lock_delete(const struct lu_env *env,
1103                             const struct cl_lock_slice *slice)
1104 {
1105         struct lov_lock        *lck     = cl2lov_lock(slice);
1106         struct cl_lock_closure *closure = lov_closure_get(env, slice->cls_lock);
1107         struct lov_lock_link   *link;
1108         int                     rc;
1109         int                     i;
1110
1111         LASSERT(slice->cls_lock->cll_state == CLS_FREEING);
1112         ENTRY;
1113
1114         for (i = 0; i < lck->lls_nr; ++i) {
1115                 struct lov_lock_sub *lls = &lck->lls_sub[i];
1116                 struct lovsub_lock  *lsl = lls->sub_lock;
1117
1118                 if (lsl == NULL) /* already removed */
1119                         continue;
1120
1121                 rc = lov_sublock_lock(env, lck, lls, closure, NULL);
1122                 if (rc == CLO_REPEAT) {
1123                         --i;
1124                         continue;
1125                 }
1126
1127                 LASSERT(rc == 0);
1128                 LASSERT(lsl->lss_cl.cls_lock->cll_state < CLS_FREEING);
1129
1130                 if (lls->sub_flags & LSF_HELD)
1131                         lov_sublock_release(env, lck, i, 1, 0);
1132
1133                 link = lov_lock_link_find(env, lck, lsl);
1134                 LASSERT(link != NULL);
1135                 lov_lock_unlink(env, link, lsl);
1136                 LASSERT(lck->lls_sub[i].sub_lock == NULL);
1137
1138                 lov_sublock_unlock(env, lsl, closure, NULL);
1139         }
1140
1141         cl_lock_closure_fini(closure);
1142         EXIT;
1143 }
1144
1145 static int lov_lock_print(const struct lu_env *env, void *cookie,
1146                           lu_printer_t p, const struct cl_lock_slice *slice)
1147 {
1148         struct lov_lock *lck = cl2lov_lock(slice);
1149         int              i;
1150
1151         (*p)(env, cookie, "%d\n", lck->lls_nr);
1152         for (i = 0; i < lck->lls_nr; ++i) {
1153                 struct lov_lock_sub *sub;
1154
1155                 sub = &lck->lls_sub[i];
1156                 (*p)(env, cookie, "    %d %x: ", i, sub->sub_flags);
1157                 if (sub->sub_lock != NULL)
1158                         cl_lock_print(env, cookie, p,
1159                                       sub->sub_lock->lss_cl.cls_lock);
1160                 else
1161                         (*p)(env, cookie, "---\n");
1162         }
1163         return 0;
1164 }
1165
1166 static const struct cl_lock_operations lov_lock_ops = {
1167         .clo_fini      = lov_lock_fini,
1168         .clo_enqueue   = lov_lock_enqueue,
1169         .clo_wait      = lov_lock_wait,
1170         .clo_use       = lov_lock_use,
1171         .clo_unuse     = lov_lock_unuse,
1172         .clo_cancel    = lov_lock_cancel,
1173         .clo_fits_into = lov_lock_fits_into,
1174         .clo_delete    = lov_lock_delete,
1175         .clo_print     = lov_lock_print
1176 };
1177
1178 int lov_lock_init_raid0(const struct lu_env *env, struct cl_object *obj,
1179                         struct cl_lock *lock, const struct cl_io *io)
1180 {
1181         struct lov_lock *lck;
1182         int result;
1183
1184         ENTRY;
1185         OBD_SLAB_ALLOC_PTR_GFP(lck, lov_lock_kmem, CFS_ALLOC_IO);
1186         if (lck != NULL) {
1187                 cl_lock_slice_add(lock, &lck->lls_cl, obj, &lov_lock_ops);
1188                 result = lov_lock_sub_init(env, lck, io);
1189         } else
1190                 result = -ENOMEM;
1191         RETURN(result);
1192 }
1193
1194 static struct cl_lock_closure *lov_closure_get(const struct lu_env *env,
1195                                                struct cl_lock *parent)
1196 {
1197         struct cl_lock_closure *closure;
1198
1199         closure = &lov_env_info(env)->lti_closure;
1200         LASSERT(cfs_list_empty(&closure->clc_list));
1201         cl_lock_closure_init(env, closure, parent, 1);
1202         return closure;
1203 }
1204
1205
1206 /** @} lov */