lustre/lov/lov_lock.c

   1 /*
   2  * GPL HEADER START
   3  *
   4  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 only,
   8  * as published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful, but
  11  * WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * General Public License version 2 for more details (a copy is included
  14  * in the LICENSE file that accompanied this code).
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * version 2 along with this program; If not, see
  18  * http://www.sun.com/software/products/lustre/docs/GPLv2.pdf
  19  *
  20  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
  21  * CA 95054 USA or visit www.sun.com if you need additional information or
  22  * have any questions.
  23  *
  24  * GPL HEADER END
  25  */
  26 /*
  27  * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
  28  * Use is subject to license terms.
  29  *
  30  * Copyright (c) 2011, 2013, Intel Corporation.
  31  */
  32 /*
  33  * This file is part of Lustre, http://www.lustre.org/
  34  * Lustre is a trademark of Sun Microsystems, Inc.
  35  *
  36  * Implementation of cl_lock for LOV layer.
  37  *
  38  *   Author: Nikita Danilov <nikita.danilov@sun.com>
  39  */
  40
  41 #define DEBUG_SUBSYSTEM S_LOV
  42
  43 #include "lov_cl_internal.h"
  44
  45 /** \addtogroup lov
  46  *  @{
  47  */
  48
  49 static struct cl_lock_closure *lov_closure_get(const struct lu_env *env,
  50                                                struct cl_lock *parent);
  51
  52 static int lov_lock_unuse(const struct lu_env *env,
  53                           const struct cl_lock_slice *slice);
  54 /*****************************************************************************
  55  *
  56  * Lov lock operations.
  57  *
  58  */
  59
  60 static struct lov_sublock_env *lov_sublock_env_get(const struct lu_env *env,
  61                                                    struct cl_lock *parent,
  62                                                    struct lov_lock_sub *lls)
  63 {
  64         struct lov_sublock_env *subenv;
  65         struct lov_io          *lio    = lov_env_io(env);
  66         struct cl_io           *io     = lio->lis_cl.cis_io;
  67         struct lov_io_sub      *sub;
  68
  69         subenv = &lov_env_session(env)->ls_subenv;
  70
  71         /*
  72          * FIXME: We tend to use the subio's env & io to call the sublock
  73          * lock operations because osc lock sometimes stores some control
  74          * variables in thread's IO infomation(Now only lockless information).
  75          * However, if the lock's host(object) is different from the object
  76          * for current IO, we have no way to get the subenv and subio because
  77          * they are not initialized at all. As a temp fix, in this case,
  78          * we still borrow the parent's env to call sublock operations.
  79          */
  80         if (!io || !cl_object_same(io->ci_obj, parent->cll_descr.cld_obj)) {
  81                 subenv->lse_env = env;
  82                 subenv->lse_io  = io;
  83                 subenv->lse_sub = NULL;
  84         } else {
  85                 sub = lov_sub_get(env, lio, lls->sub_stripe);
  86                 if (!IS_ERR(sub)) {
  87                         subenv->lse_env = sub->sub_env;
  88                         subenv->lse_io  = sub->sub_io;
  89                         subenv->lse_sub = sub;
  90                 } else {
  91                         subenv = (void*)sub;
  92                 }
  93         }
  94         return subenv;
  95 }
  96
  97 static void lov_sublock_env_put(struct lov_sublock_env *subenv)
  98 {
  99         if (subenv && subenv->lse_sub)
 100                 lov_sub_put(subenv->lse_sub);
 101 }
 102
 103 static void lov_sublock_adopt(const struct lu_env *env, struct lov_lock *lck,
 104                               struct cl_lock *sublock, int idx,
 105                               struct lov_lock_link *link)
 106 {
 107         struct lovsub_lock *lsl;
 108         struct cl_lock     *parent = lck->lls_cl.cls_lock;
 109         int                 rc;
 110
 111         LASSERT(cl_lock_is_mutexed(parent));
 112         LASSERT(cl_lock_is_mutexed(sublock));
 113         ENTRY;
 114
 115         lsl = cl2sub_lock(sublock);
 116         /*
 117          * check that sub-lock doesn't have lock link to this top-lock.
 118          */
 119         LASSERT(lov_lock_link_find(env, lck, lsl) == NULL);
 120         LASSERT(idx < lck->lls_nr);
 121
 122         lck->lls_sub[idx].sub_lock = lsl;
 123         lck->lls_nr_filled++;
 124         LASSERT(lck->lls_nr_filled <= lck->lls_nr);
 125         list_add_tail(&link->lll_list, &lsl->lss_parents);
 126         link->lll_idx = idx;
 127         link->lll_super = lck;
 128         cl_lock_get(parent);
 129         lu_ref_add(&parent->cll_reference, "lov-child", sublock);
 130         lck->lls_sub[idx].sub_flags |= LSF_HELD;
 131         cl_lock_user_add(env, sublock);
 132
 133         rc = lov_sublock_modify(env, lck, lsl, &sublock->cll_descr, idx);
 134         LASSERT(rc == 0); /* there is no way this can fail, currently */
 135         EXIT;
 136 }
 137
 138 static struct cl_lock *lov_sublock_alloc(const struct lu_env *env,
 139                                          const struct cl_io *io,
 140                                          struct lov_lock *lck,
 141                                          int idx, struct lov_lock_link **out)
 142 {
 143         struct cl_lock       *sublock;
 144         struct cl_lock       *parent;
 145         struct lov_lock_link *link;
 146
 147         LASSERT(idx < lck->lls_nr);
 148         ENTRY;
 149
 150         OBD_SLAB_ALLOC_PTR_GFP(link, lov_lock_link_kmem, GFP_NOFS);
 151         if (link != NULL) {
 152                 struct lov_sublock_env *subenv;
 153                 struct lov_lock_sub  *lls;
 154                 struct cl_lock_descr *descr;
 155
 156                 parent = lck->lls_cl.cls_lock;
 157                 lls    = &lck->lls_sub[idx];
 158                 descr  = &lls->sub_got;
 159
 160                 subenv = lov_sublock_env_get(env, parent, lls);
 161                 if (!IS_ERR(subenv)) {
 162                         /* CAVEAT: Don't try to add a field in lov_lock_sub
 163                          * to remember the subio. This is because lock is able
 164                          * to be cached, but this is not true for IO. This
 165                          * further means a sublock might be referenced in
 166                          * different io context. -jay */
 167
 168                         sublock = cl_lock_hold(subenv->lse_env, subenv->lse_io,
 169                                                descr, "lov-parent", parent);
 170                         lov_sublock_env_put(subenv);
 171                 } else {
 172                         /* error occurs. */
 173                         sublock = (void *)subenv;
 174                 }
 175
 176                 if (!IS_ERR(sublock))
 177                         *out = link;
 178                 else
 179                         OBD_SLAB_FREE_PTR(link, lov_lock_link_kmem);
 180         } else
 181                 sublock = ERR_PTR(-ENOMEM);
 182         RETURN(sublock);
 183 }
 184
 185 static void lov_sublock_unlock(const struct lu_env *env,
 186                                struct lovsub_lock *lsl,
 187                                struct cl_lock_closure *closure,
 188                                struct lov_sublock_env *subenv)
 189 {
 190         ENTRY;
 191         lov_sublock_env_put(subenv);
 192         lsl->lss_active = NULL;
 193         cl_lock_disclosure(env, closure);
 194         EXIT;
 195 }
 196
 197 static int lov_sublock_lock(const struct lu_env *env,
 198                             struct lov_lock *lck,
 199                             struct lov_lock_sub *lls,
 200                             struct cl_lock_closure *closure,
 201                             struct lov_sublock_env **lsep)
 202 {
 203         struct lovsub_lock *sublock;
 204         struct cl_lock     *child;
 205         int                 result = 0;
 206         ENTRY;
 207
 208         LASSERT(list_empty(&closure->clc_list));
 209
 210         sublock = lls->sub_lock;
 211         child = sublock->lss_cl.cls_lock;
 212         result = cl_lock_closure_build(env, child, closure);
 213         if (result == 0) {
 214                 struct cl_lock *parent = closure->clc_origin;
 215
 216                 LASSERT(cl_lock_is_mutexed(child));
 217                 sublock->lss_active = parent;
 218
 219                 if (unlikely((child->cll_state == CLS_FREEING) ||
 220                              (child->cll_flags & CLF_CANCELLED))) {
 221                         struct lov_lock_link *link;
 222                         /*
 223                          * we could race with lock deletion which temporarily
 224                          * put the lock in freeing state, bug 19080.
 225                          */
 226                         LASSERT(!(lls->sub_flags & LSF_HELD));
 227
 228                         link = lov_lock_link_find(env, lck, sublock);
 229                         LASSERT(link != NULL);
 230                         lov_lock_unlink(env, link, sublock);
 231                         lov_sublock_unlock(env, sublock, closure, NULL);
 232                         lck->lls_cancel_race = 1;
 233                         result = CLO_REPEAT;
 234                 } else if (lsep) {
 235                         struct lov_sublock_env *subenv;
 236                         subenv = lov_sublock_env_get(env, parent, lls);
 237                         if (IS_ERR(subenv)) {
 238                                 lov_sublock_unlock(env, sublock,
 239                                                    closure, NULL);
 240                                 result = PTR_ERR(subenv);
 241                         } else {
 242                                 *lsep = subenv;
 243                         }
 244                 }
 245         }
 246         RETURN(result);
 247 }
 248
 249 /**
 250  * Updates the result of a top-lock operation from a result of sub-lock
 251  * sub-operations. Top-operations like lov_lock_{enqueue,use,unuse}() iterate
 252  * over sub-locks and lov_subresult() is used to calculate return value of a
 253  * top-operation. To this end, possible return values of sub-operations are
 254  * ordered as
 255  *
 256  *     - 0                  success
 257  *     - CLO_WAIT           wait for event
 258  *     - CLO_REPEAT         repeat top-operation
 259  *     - -ne                fundamental error
 260  *
 261  * Top-level return code can only go down through this list. CLO_REPEAT
 262  * overwrites CLO_WAIT, because lock mutex was released and sleeping condition
 263  * has to be rechecked by the upper layer.
 264  */
 265 static int lov_subresult(int result, int rc)
 266 {
 267         int result_rank;
 268         int rc_rank;
 269
 270         ENTRY;
 271
 272         LASSERTF(result <= 0 || result == CLO_REPEAT || result == CLO_WAIT,
 273                  "result = %d\n", result);
 274         LASSERTF(rc <= 0 || rc == CLO_REPEAT || rc == CLO_WAIT,
 275                  "rc = %d\n", rc);
 276         CLASSERT(CLO_WAIT < CLO_REPEAT);
 277
 278         /* calculate ranks in the ordering above */
 279         result_rank = result < 0 ? 1 + CLO_REPEAT : result;
 280         rc_rank = rc < 0 ? 1 + CLO_REPEAT : rc;
 281
 282         if (result_rank < rc_rank)
 283                 result = rc;
 284         RETURN(result);
 285 }
 286
 287 /**
 288  * Creates sub-locks for a given lov_lock for the first time.
 289  *
 290  * Goes through all sub-objects of top-object, and creates sub-locks on every
 291  * sub-object intersecting with top-lock extent. This is complicated by the
 292  * fact that top-lock (that is being created) can be accessed concurrently
 293  * through already created sub-locks (possibly shared with other top-locks).
 294  */
 295 static int lov_lock_sub_init(const struct lu_env *env,
 296                              struct lov_lock *lck, const struct cl_io *io)
 297 {
 298         int result = 0;
 299         int i;
 300         int nr;
 301         obd_off start;
 302         obd_off end;
 303         obd_off file_start;
 304         obd_off file_end;
 305
 306         struct lov_object       *loo    = cl2lov(lck->lls_cl.cls_obj);
 307         struct lov_layout_raid0 *r0     = lov_r0(loo);
 308         struct cl_lock          *parent = lck->lls_cl.cls_lock;
 309
 310         ENTRY;
 311
 312         lck->lls_orig = parent->cll_descr;
 313         file_start = cl_offset(lov2cl(loo), parent->cll_descr.cld_start);
 314         file_end   = cl_offset(lov2cl(loo), parent->cll_descr.cld_end + 1) - 1;
 315
 316         for (i = 0, nr = 0; i < r0->lo_nr; i++) {
 317                 /*
 318                  * XXX for wide striping smarter algorithm is desirable,
 319                  * breaking out of the loop, early.
 320                  */
 321                 if (likely(r0->lo_sub[i] != NULL) &&
 322                     lov_stripe_intersects(loo->lo_lsm, i,
 323                                           file_start, file_end, &start, &end))
 324                         nr++;
 325         }
 326         LASSERT(nr > 0);
 327         OBD_ALLOC_LARGE(lck->lls_sub, nr * sizeof lck->lls_sub[0]);
 328         if (lck->lls_sub == NULL)
 329                 RETURN(-ENOMEM);
 330
 331         lck->lls_nr = nr;
 332         /*
 333          * First, fill in sub-lock descriptions in
 334          * lck->lls_sub[].sub_descr. They are used by lov_sublock_alloc()
 335          * (called below in this function, and by lov_lock_enqueue()) to
 336          * create sub-locks. At this moment, no other thread can access
 337          * top-lock.
 338          */
 339         for (i = 0, nr = 0; i < r0->lo_nr; ++i) {
 340                 if (likely(r0->lo_sub[i] != NULL) &&
 341                     lov_stripe_intersects(loo->lo_lsm, i,
 342                                           file_start, file_end, &start, &end)) {
 343                         struct cl_lock_descr *descr;
 344
 345                         descr = &lck->lls_sub[nr].sub_descr;
 346
 347                         LASSERT(descr->cld_obj == NULL);
 348                         descr->cld_obj   = lovsub2cl(r0->lo_sub[i]);
 349                         descr->cld_start = cl_index(descr->cld_obj, start);
 350                         descr->cld_end   = cl_index(descr->cld_obj, end);
 351                         descr->cld_mode  = parent->cll_descr.cld_mode;
 352                         descr->cld_gid   = parent->cll_descr.cld_gid;
 353                         descr->cld_enq_flags   = parent->cll_descr.cld_enq_flags;
 354                         /* XXX has no effect */
 355                         lck->lls_sub[nr].sub_got = *descr;
 356                         lck->lls_sub[nr].sub_stripe = i;
 357                         nr++;
 358                 }
 359         }
 360         LASSERT(nr == lck->lls_nr);
 361
 362         /*
 363          * Some sub-locks can be missing at this point. This is not a problem,
 364          * because enqueue will create them anyway. Main duty of this function
 365          * is to fill in sub-lock descriptions in a race free manner.
 366          */
 367         RETURN(result);
 368 }
 369
 370 static int lov_sublock_release(const struct lu_env *env, struct lov_lock *lck,
 371                                int i, int deluser, int rc)
 372 {
 373         struct cl_lock *parent = lck->lls_cl.cls_lock;
 374
 375         LASSERT(cl_lock_is_mutexed(parent));
 376         ENTRY;
 377
 378         if (lck->lls_sub[i].sub_flags & LSF_HELD) {
 379                 struct cl_lock    *sublock;
 380                 int dying;
 381
 382                 LASSERT(lck->lls_sub[i].sub_lock != NULL);
 383                 sublock = lck->lls_sub[i].sub_lock->lss_cl.cls_lock;
 384                 LASSERT(cl_lock_is_mutexed(sublock));
 385
 386                 lck->lls_sub[i].sub_flags &= ~LSF_HELD;
 387                 if (deluser)
 388                         cl_lock_user_del(env, sublock);
 389                 /*
 390                  * If the last hold is released, and cancellation is pending
 391                  * for a sub-lock, release parent mutex, to avoid keeping it
 392                  * while sub-lock is being paged out.
 393                  */
 394                 dying = (sublock->cll_descr.cld_mode == CLM_PHANTOM ||
 395                          sublock->cll_descr.cld_mode == CLM_GROUP ||
 396                          (sublock->cll_flags & (CLF_CANCELPEND|CLF_DOOMED))) &&
 397                         sublock->cll_holds == 1;
 398                 if (dying)
 399                         cl_lock_mutex_put(env, parent);
 400                 cl_lock_unhold(env, sublock, "lov-parent", parent);
 401                 if (dying) {
 402                         cl_lock_mutex_get(env, parent);
 403                         rc = lov_subresult(rc, CLO_REPEAT);
 404                 }
 405                 /*
 406                  * From now on lck->lls_sub[i].sub_lock is a "weak" pointer,
 407                  * not backed by a reference on a
 408                  * sub-lock. lovsub_lock_delete() will clear
 409                  * lck->lls_sub[i].sub_lock under semaphores, just before
 410                  * sub-lock is destroyed.
 411                  */
 412         }
 413         RETURN(rc);
 414 }
 415
 416 static void lov_sublock_hold(const struct lu_env *env, struct lov_lock *lck,
 417                              int i)
 418 {
 419         struct cl_lock *parent = lck->lls_cl.cls_lock;
 420
 421         LASSERT(cl_lock_is_mutexed(parent));
 422         ENTRY;
 423
 424         if (!(lck->lls_sub[i].sub_flags & LSF_HELD)) {
 425                 struct cl_lock *sublock;
 426
 427                 LASSERT(lck->lls_sub[i].sub_lock != NULL);
 428                 sublock = lck->lls_sub[i].sub_lock->lss_cl.cls_lock;
 429                 LASSERT(cl_lock_is_mutexed(sublock));
 430                 LASSERT(sublock->cll_state != CLS_FREEING);
 431
 432                 lck->lls_sub[i].sub_flags |= LSF_HELD;
 433
 434                 cl_lock_get_trust(sublock);
 435                 cl_lock_hold_add(env, sublock, "lov-parent", parent);
 436                 cl_lock_user_add(env, sublock);
 437                 cl_lock_put(env, sublock);
 438         }
 439         EXIT;
 440 }
 441
 442 static void lov_lock_fini(const struct lu_env *env,
 443                           struct cl_lock_slice *slice)
 444 {
 445         struct lov_lock *lck;
 446         int i;
 447
 448         ENTRY;
 449         lck = cl2lov_lock(slice);
 450         LASSERT(lck->lls_nr_filled == 0);
 451         if (lck->lls_sub != NULL) {
 452                 for (i = 0; i < lck->lls_nr; ++i)
 453                         /*
 454                          * No sub-locks exists at this point, as sub-lock has
 455                          * a reference on its parent.
 456                          */
 457                         LASSERT(lck->lls_sub[i].sub_lock == NULL);
 458                 OBD_FREE_LARGE(lck->lls_sub,
 459                                lck->lls_nr * sizeof lck->lls_sub[0]);
 460         }
 461         OBD_SLAB_FREE_PTR(lck, lov_lock_kmem);
 462         EXIT;
 463 }
 464
 465 static int lov_lock_enqueue_wait(const struct lu_env *env,
 466                                  struct lov_lock *lck,
 467                                  struct cl_lock *sublock)
 468 {
 469         struct cl_lock *lock = lck->lls_cl.cls_lock;
 470         int             result;
 471         ENTRY;
 472
 473         LASSERT(cl_lock_is_mutexed(lock));
 474
 475         cl_lock_mutex_put(env, lock);
 476         result = cl_lock_enqueue_wait(env, sublock, 0);
 477         cl_lock_mutex_get(env, lock);
 478         RETURN(result ?: CLO_REPEAT);
 479 }
 480
 481 /**
 482  * Tries to advance a state machine of a given sub-lock toward enqueuing of
 483  * the top-lock.
 484  *
 485  * \retval 0 if state-transition can proceed
 486  * \retval -ve otherwise.
 487  */
 488 static int lov_lock_enqueue_one(const struct lu_env *env, struct lov_lock *lck,
 489                                 struct cl_lock *sublock,
 490                                 struct cl_io *io, __u32 enqflags, int last)
 491 {
 492         int result;
 493         ENTRY;
 494
 495         /* first, try to enqueue a sub-lock ... */
 496         result = cl_enqueue_try(env, sublock, io, enqflags);
 497         if ((sublock->cll_state == CLS_ENQUEUED) && !(enqflags & CEF_AGL)) {
 498                 /* if it is enqueued, try to `wait' on it---maybe it's already
 499                  * granted */
 500                 result = cl_wait_try(env, sublock);
 501                 if (result == CLO_REENQUEUED)
 502                         result = CLO_WAIT;
 503         }
 504         /*
 505          * If CEF_ASYNC flag is set, then all sub-locks can be enqueued in
 506          * parallel, otherwise---enqueue has to wait until sub-lock is granted
 507          * before proceeding to the next one.
 508          */
 509         if ((result == CLO_WAIT) && (sublock->cll_state <= CLS_HELD) &&
 510             (enqflags & CEF_ASYNC) && (!last || (enqflags & CEF_AGL)))
 511                 result = 0;
 512         RETURN(result);
 513 }
 514
 515 /**
 516  * Helper function for lov_lock_enqueue() that creates missing sub-lock.
 517  */
 518 static int lov_sublock_fill(const struct lu_env *env, struct cl_lock *parent,
 519                             struct cl_io *io, struct lov_lock *lck, int idx)
 520 {
 521         struct lov_lock_link *link = NULL;
 522         struct cl_lock       *sublock;
 523         int                   result;
 524
 525         LASSERT(parent->cll_depth == 1);
 526         cl_lock_mutex_put(env, parent);
 527         sublock = lov_sublock_alloc(env, io, lck, idx, &link);
 528         if (!IS_ERR(sublock))
 529                 cl_lock_mutex_get(env, sublock);
 530         cl_lock_mutex_get(env, parent);
 531
 532         if (!IS_ERR(sublock)) {
 533                 cl_lock_get_trust(sublock);
 534                 if (parent->cll_state == CLS_QUEUING &&
 535                     lck->lls_sub[idx].sub_lock == NULL) {
 536                         lov_sublock_adopt(env, lck, sublock, idx, link);
 537                 } else {
 538                         OBD_SLAB_FREE_PTR(link, lov_lock_link_kmem);
 539                         /* other thread allocated sub-lock, or enqueue is no
 540                          * longer going on */
 541                         cl_lock_mutex_put(env, parent);
 542                         cl_lock_unhold(env, sublock, "lov-parent", parent);
 543                         cl_lock_mutex_get(env, parent);
 544                 }
 545                 cl_lock_mutex_put(env, sublock);
 546                 cl_lock_put(env, sublock);
 547                 result = CLO_REPEAT;
 548         } else
 549                 result = PTR_ERR(sublock);
 550         return result;
 551 }
 552
 553 /**
 554  * Implementation of cl_lock_operations::clo_enqueue() for lov layer. This
 555  * function is rather subtle, as it enqueues top-lock (i.e., advances top-lock
 556  * state machine from CLS_QUEUING to CLS_ENQUEUED states) by juggling sub-lock
 557  * state machines in the face of sub-locks sharing (by multiple top-locks),
 558  * and concurrent sub-lock cancellations.
 559  */
 560 static int lov_lock_enqueue(const struct lu_env *env,
 561                             const struct cl_lock_slice *slice,
 562                             struct cl_io *io, __u32 enqflags)
 563 {
 564         struct cl_lock         *lock    = slice->cls_lock;
 565         struct lov_lock        *lck     = cl2lov_lock(slice);
 566         struct cl_lock_closure *closure = lov_closure_get(env, lock);
 567         int i;
 568         int result;
 569         enum cl_lock_state minstate;
 570
 571         ENTRY;
 572
 573         for (result = 0, minstate = CLS_FREEING, i = 0; i < lck->lls_nr; ++i) {
 574                 int rc;
 575                 struct lovsub_lock     *sub;
 576                 struct lov_lock_sub    *lls;
 577                 struct cl_lock         *sublock;
 578                 struct lov_sublock_env *subenv;
 579
 580                 if (lock->cll_state != CLS_QUEUING) {
 581                         /*
 582                          * Lock might have left QUEUING state if previous
 583                          * iteration released its mutex. Stop enqueing in this
 584                          * case and let the upper layer to decide what to do.
 585                          */
 586                         LASSERT(i > 0 && result != 0);
 587                         break;
 588                 }
 589
 590                 lls = &lck->lls_sub[i];
 591                 sub = lls->sub_lock;
 592                 /*
 593                  * Sub-lock might have been canceled, while top-lock was
 594                  * cached.
 595                  */
 596                 if (sub == NULL) {
 597                         result = lov_sublock_fill(env, lock, io, lck, i);
 598                         /* lov_sublock_fill() released @lock mutex,
 599                          * restart. */
 600                         break;
 601                 }
 602                 sublock = sub->lss_cl.cls_lock;
 603                 rc = lov_sublock_lock(env, lck, lls, closure, &subenv);
 604                 if (rc == 0) {
 605                         lov_sublock_hold(env, lck, i);
 606                         rc = lov_lock_enqueue_one(subenv->lse_env, lck, sublock,
 607                                                   subenv->lse_io, enqflags,
 608                                                   i == lck->lls_nr - 1);
 609                         minstate = min(minstate, sublock->cll_state);
 610                         if (rc == CLO_WAIT) {
 611                                 switch (sublock->cll_state) {
 612                                 case CLS_QUEUING:
 613                                         /* take recursive mutex, the lock is
 614                                          * released in lov_lock_enqueue_wait.
 615                                          */
 616                                         cl_lock_mutex_get(env, sublock);
 617                                         lov_sublock_unlock(env, sub, closure,
 618                                                            subenv);
 619                                         rc = lov_lock_enqueue_wait(env, lck,
 620                                                                    sublock);
 621                                         break;
 622                                 case CLS_CACHED:
 623                                         cl_lock_get(sublock);
 624                                         /* take recursive mutex of sublock */
 625                                         cl_lock_mutex_get(env, sublock);
 626                                         /* need to release all locks in closure
 627                                          * otherwise it may deadlock. LU-2683.*/
 628                                         lov_sublock_unlock(env, sub, closure,
 629                                                            subenv);
 630                                         /* sublock and parent are held. */
 631                                         rc = lov_sublock_release(env, lck, i,
 632                                                                  1, rc);
 633                                         cl_lock_mutex_put(env, sublock);
 634                                         cl_lock_put(env, sublock);
 635                                         break;
 636                                 default:
 637                                         lov_sublock_unlock(env, sub, closure,
 638                                                            subenv);
 639                                         break;
 640                                 }
 641                         } else {
 642                                 LASSERT(sublock->cll_conflict == NULL);
 643                                 lov_sublock_unlock(env, sub, closure, subenv);
 644                         }
 645                 }
 646                 result = lov_subresult(result, rc);
 647                 if (result != 0)
 648                         break;
 649         }
 650         cl_lock_closure_fini(closure);
 651         RETURN(result ?: minstate >= CLS_ENQUEUED ? 0 : CLO_WAIT);
 652 }
 653
 654 static int lov_lock_unuse(const struct lu_env *env,
 655                           const struct cl_lock_slice *slice)
 656 {
 657         struct lov_lock        *lck     = cl2lov_lock(slice);
 658         struct cl_lock_closure *closure = lov_closure_get(env, slice->cls_lock);
 659         int i;
 660         int result;
 661
 662         ENTRY;
 663
 664         for (result = 0, i = 0; i < lck->lls_nr; ++i) {
 665                 int rc;
 666                 struct lovsub_lock     *sub;
 667                 struct cl_lock         *sublock;
 668                 struct lov_lock_sub    *lls;
 669                 struct lov_sublock_env *subenv;
 670
 671                 /* top-lock state cannot change concurrently, because single
 672                  * thread (one that released the last hold) carries unlocking
 673                  * to the completion. */
 674                 LASSERT(slice->cls_lock->cll_state == CLS_INTRANSIT);
 675                 lls = &lck->lls_sub[i];
 676                 sub = lls->sub_lock;
 677                 if (sub == NULL)
 678                         continue;
 679
 680                 sublock = sub->lss_cl.cls_lock;
 681                 rc = lov_sublock_lock(env, lck, lls, closure, &subenv);
 682                 if (rc == 0) {
 683                         if (!(lls->sub_flags & LSF_HELD)) {
 684                                 lov_sublock_unlock(env, sub, closure, subenv);
 685                                 continue;
 686                         }
 687
 688                         switch(sublock->cll_state) {
 689                         case CLS_HELD:
 690                                 rc = cl_unuse_try(subenv->lse_env, sublock);
 691                                 lov_sublock_release(env, lck, i, 0, 0);
 692                                 break;
 693                         default:
 694                                 cl_lock_cancel(subenv->lse_env, sublock);
 695                                 lov_sublock_release(env, lck, i, 1, 0);
 696                                 break;
 697                         }
 698                         lov_sublock_unlock(env, sub, closure, subenv);
 699                 }
 700                 result = lov_subresult(result, rc);
 701         }
 702
 703         if (result == 0 && lck->lls_cancel_race) {
 704                 lck->lls_cancel_race = 0;
 705                 result = -ESTALE;
 706         }
 707         cl_lock_closure_fini(closure);
 708         RETURN(result);
 709 }
 710
 711
 712 static void lov_lock_cancel(const struct lu_env *env,
 713                            const struct cl_lock_slice *slice)
 714 {
 715         struct lov_lock        *lck     = cl2lov_lock(slice);
 716         struct cl_lock_closure *closure = lov_closure_get(env, slice->cls_lock);
 717         int i;
 718         int result;
 719
 720         ENTRY;
 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                                 cl_lock_cancel(subenv->lse_env, sublock);
 752                                 lov_sublock_release(env, lck, i, 1, 0);
 753                                 break;
 754                         }
 755                         lov_sublock_unlock(env, sub, closure, subenv);
 756                 }
 757
 758                 if (rc == CLO_REPEAT) {
 759                         --i;
 760                         continue;
 761                 }
 762
 763                 result = lov_subresult(result, rc);
 764         }
 765
 766         if (result)
 767                 CL_LOCK_DEBUG(D_ERROR, env, slice->cls_lock,
 768                               "lov_lock_cancel fails with %d.\n", result);
 769
 770         cl_lock_closure_fini(closure);
 771 }
 772
 773 static int lov_lock_wait(const struct lu_env *env,
 774                          const struct cl_lock_slice *slice)
 775 {
 776         struct lov_lock        *lck     = cl2lov_lock(slice);
 777         struct cl_lock_closure *closure = lov_closure_get(env, slice->cls_lock);
 778         enum cl_lock_state      minstate;
 779         int                     reenqueued;
 780         int                     result;
 781         int                     i;
 782
 783         ENTRY;
 784
 785 again:
 786         for (result = 0, minstate = CLS_FREEING, i = 0, reenqueued = 0;
 787              i < lck->lls_nr; ++i) {
 788                 int rc;
 789                 struct lovsub_lock     *sub;
 790                 struct cl_lock         *sublock;
 791                 struct lov_lock_sub    *lls;
 792                 struct lov_sublock_env *subenv;
 793
 794                 lls = &lck->lls_sub[i];
 795                 sub = lls->sub_lock;
 796                 LASSERT(sub != NULL);
 797                 sublock = sub->lss_cl.cls_lock;
 798                 rc = lov_sublock_lock(env, lck, lls, closure, &subenv);
 799                 if (rc == 0) {
 800                         LASSERT(sublock->cll_state >= CLS_ENQUEUED);
 801                         if (sublock->cll_state < CLS_HELD)
 802                                 rc = cl_wait_try(env, sublock);
 803
 804                         minstate = min(minstate, sublock->cll_state);
 805                         lov_sublock_unlock(env, sub, closure, subenv);
 806                 }
 807                 if (rc == CLO_REENQUEUED) {
 808                         reenqueued++;
 809                         rc = 0;
 810                 }
 811                 result = lov_subresult(result, rc);
 812                 if (result != 0)
 813                         break;
 814         }
 815         /* Each sublock only can be reenqueued once, so will not loop for
 816          * ever. */
 817         if (result == 0 && reenqueued != 0)
 818                 goto again;
 819         cl_lock_closure_fini(closure);
 820         RETURN(result ?: minstate >= CLS_HELD ? 0 : CLO_WAIT);
 821 }
 822
 823 static int lov_lock_use(const struct lu_env *env,
 824                         const struct cl_lock_slice *slice)
 825 {
 826         struct lov_lock        *lck     = cl2lov_lock(slice);
 827         struct cl_lock_closure *closure = lov_closure_get(env, slice->cls_lock);
 828         int                     result;
 829         int                     i;
 830
 831         LASSERT(slice->cls_lock->cll_state == CLS_INTRANSIT);
 832         ENTRY;
 833
 834         for (result = 0, i = 0; i < lck->lls_nr; ++i) {
 835                 int rc;
 836                 struct lovsub_lock     *sub;
 837                 struct cl_lock         *sublock;
 838                 struct lov_lock_sub    *lls;
 839                 struct lov_sublock_env *subenv;
 840
 841                 LASSERT(slice->cls_lock->cll_state == CLS_INTRANSIT);
 842
 843                 lls = &lck->lls_sub[i];
 844                 sub = lls->sub_lock;
 845                 if (sub == NULL) {
 846                         /*
 847                          * Sub-lock might have been canceled, while top-lock was
 848                          * cached.
 849                          */
 850                         result = -ESTALE;
 851                         break;
 852                 }
 853
 854                 sublock = sub->lss_cl.cls_lock;
 855                 rc = lov_sublock_lock(env, lck, lls, closure, &subenv);
 856                 if (rc == 0) {
 857                         LASSERT(sublock->cll_state != CLS_FREEING);
 858                         lov_sublock_hold(env, lck, i);
 859                         if (sublock->cll_state == CLS_CACHED) {
 860                                 rc = cl_use_try(subenv->lse_env, sublock, 0);
 861                                 if (rc != 0)
 862                                         rc = lov_sublock_release(env, lck,
 863                                                                  i, 1, rc);
 864                         } else if (sublock->cll_state == CLS_NEW) {
 865                                 /* Sub-lock might have been canceled, while
 866                                  * top-lock was cached. */
 867                                 result = -ESTALE;
 868                                 lov_sublock_release(env, lck, i, 1, result);
 869                         }
 870                         lov_sublock_unlock(env, sub, closure, subenv);
 871                 }
 872                 result = lov_subresult(result, rc);
 873                 if (result != 0)
 874                         break;
 875         }
 876
 877         if (lck->lls_cancel_race) {
 878                 /*
 879                  * If there is unlocking happened at the same time, then
 880                  * sublock_lock state should be FREEING, and lov_sublock_lock
 881                  * should return CLO_REPEAT. In this case, it should return
 882                  * ESTALE, and up layer should reset the lock state to be NEW.
 883                  */
 884                 lck->lls_cancel_race = 0;
 885                 LASSERT(result != 0);
 886                 result = -ESTALE;
 887         }
 888         cl_lock_closure_fini(closure);
 889         RETURN(result);
 890 }
 891
 892 #if 0
 893 static int lock_lock_multi_match()
 894 {
 895         struct cl_lock          *lock    = slice->cls_lock;
 896         struct cl_lock_descr    *subneed = &lov_env_info(env)->lti_ldescr;
 897         struct lov_object       *loo     = cl2lov(lov->lls_cl.cls_obj);
 898         struct lov_layout_raid0 *r0      = lov_r0(loo);
 899         struct lov_lock_sub     *sub;
 900         struct cl_object        *subobj;
 901         obd_off  fstart;
 902         obd_off  fend;
 903         obd_off  start;
 904         obd_off  end;
 905         int i;
 906
 907         fstart = cl_offset(need->cld_obj, need->cld_start);
 908         fend   = cl_offset(need->cld_obj, need->cld_end + 1) - 1;
 909         subneed->cld_mode = need->cld_mode;
 910         cl_lock_mutex_get(env, lock);
 911         for (i = 0; i < lov->lls_nr; ++i) {
 912                 sub = &lov->lls_sub[i];
 913                 if (sub->sub_lock == NULL)
 914                         continue;
 915                 subobj = sub->sub_descr.cld_obj;
 916                 if (!lov_stripe_intersects(loo->lo_lsm, sub->sub_stripe,
 917                                            fstart, fend, &start, &end))
 918                         continue;
 919                 subneed->cld_start = cl_index(subobj, start);
 920                 subneed->cld_end   = cl_index(subobj, end);
 921                 subneed->cld_obj   = subobj;
 922                 if (!cl_lock_ext_match(&sub->sub_got, subneed)) {
 923                         result = 0;
 924                         break;
 925                 }
 926         }
 927         cl_lock_mutex_put(env, lock);
 928 }
 929 #endif
 930
 931 /**
 932  * Check if the extent region \a descr is covered by \a child against the
 933  * specific \a stripe.
 934  */
 935 static int lov_lock_stripe_is_matching(const struct lu_env *env,
 936                                        struct lov_object *lov, int stripe,
 937                                        const struct cl_lock_descr *child,
 938                                        const struct cl_lock_descr *descr)
 939 {
 940         struct lov_stripe_md *lsm = lov->lo_lsm;
 941         obd_off start;
 942         obd_off end;
 943         int result;
 944
 945         if (lov_r0(lov)->lo_nr == 1)
 946                 return cl_lock_ext_match(child, descr);
 947
 948         /*
 949          * For a multi-stripes object:
 950          * - make sure the descr only covers child's stripe, and
 951          * - check if extent is matching.
 952          */
 953         start = cl_offset(&lov->lo_cl, descr->cld_start);
 954         end   = cl_offset(&lov->lo_cl, descr->cld_end + 1) - 1;
 955
 956         result = 0;
 957         /* glimpse should work on the object with LOV EA hole. */
 958         if ((end - start <= lsm->lsm_stripe_size) ||
 959             (descr->cld_end == CL_PAGE_EOF &&
 960              unlikely(lov->lo_lsm->lsm_pattern & LOV_PATTERN_F_HOLE))) {
 961                 int idx;
 962
 963                 idx = lov_stripe_number(lsm, start);
 964                 if (idx == stripe ||
 965                     unlikely(lov_r0(lov)->lo_sub[idx] == NULL)) {
 966                         idx = lov_stripe_number(lsm, end);
 967                         if (idx == stripe ||
 968                             unlikely(lov_r0(lov)->lo_sub[idx] == NULL))
 969                                 result = 1;
 970                 }
 971         }
 972
 973         if (result != 0) {
 974                 struct cl_lock_descr *subd = &lov_env_info(env)->lti_ldescr;
 975                 obd_off sub_start;
 976                 obd_off sub_end;
 977
 978                 subd->cld_obj  = NULL;   /* don't need sub object at all */
 979                 subd->cld_mode = descr->cld_mode;
 980                 subd->cld_gid  = descr->cld_gid;
 981                 result = lov_stripe_intersects(lsm, stripe, start, end,
 982                                                &sub_start, &sub_end);
 983                 LASSERT(result);
 984                 subd->cld_start = cl_index(child->cld_obj, sub_start);
 985                 subd->cld_end   = cl_index(child->cld_obj, sub_end);
 986                 result = cl_lock_ext_match(child, subd);
 987         }
 988         return result;
 989 }
 990
 991 /**
 992  * An implementation of cl_lock_operations::clo_fits_into() method.
 993  *
 994  * Checks whether a lock (given by \a slice) is suitable for \a
 995  * io. Multi-stripe locks can be used only for "quick" io, like truncate, or
 996  * O_APPEND write.
 997  *
 998  * \see ccc_lock_fits_into().
 999  */
1000 static int lov_lock_fits_into(const struct lu_env *env,
1001                               const struct cl_lock_slice *slice,
1002                               const struct cl_lock_descr *need,
1003                               const struct cl_io *io)
1004 {
1005         struct lov_lock   *lov = cl2lov_lock(slice);
1006         struct lov_object *obj = cl2lov(slice->cls_obj);
1007         int result;
1008
1009         LASSERT(cl_object_same(need->cld_obj, slice->cls_obj));
1010         LASSERT(lov->lls_nr > 0);
1011
1012         ENTRY;
1013
1014         /* for top lock, it's necessary to match enq flags otherwise it will
1015          * run into problem if a sublock is missing and reenqueue. */
1016         if (need->cld_enq_flags != lov->lls_orig.cld_enq_flags)
1017                 return 0;
1018
1019         if (lov->lls_ever_canceled)
1020                 return 0;
1021
1022         if (need->cld_mode == CLM_GROUP)
1023                 /*
1024                  * always allow to match group lock.
1025                  */
1026                 result = cl_lock_ext_match(&lov->lls_orig, need);
1027         else if (lov->lls_nr == 1) {
1028                 struct cl_lock_descr *got = &lov->lls_sub[0].sub_got;
1029                 result = lov_lock_stripe_is_matching(env,
1030                                                      cl2lov(slice->cls_obj),
1031                                                      lov->lls_sub[0].sub_stripe,
1032                                                      got, need);
1033         } else if (io->ci_type != CIT_SETATTR && io->ci_type != CIT_MISC &&
1034                    !cl_io_is_append(io) && need->cld_mode != CLM_PHANTOM)
1035                 /*
1036                  * Multi-stripe locks are only suitable for `quick' IO and for
1037                  * glimpse.
1038                  */
1039                 result = 0;
1040         else
1041                 /*
1042                  * Most general case: multi-stripe existing lock, and
1043                  * (potentially) multi-stripe @need lock. Check that @need is
1044                  * covered by @lov's sub-locks.
1045                  *
1046                  * For now, ignore lock expansions made by the server, and
1047                  * match against original lock extent.
1048                  */
1049                 result = cl_lock_ext_match(&lov->lls_orig, need);
1050         CDEBUG(D_DLMTRACE, DDESCR"/"DDESCR" %d %d/%d: %d\n",
1051                PDESCR(&lov->lls_orig), PDESCR(&lov->lls_sub[0].sub_got),
1052                lov->lls_sub[0].sub_stripe, lov->lls_nr, lov_r0(obj)->lo_nr,
1053                result);
1054         RETURN(result);
1055 }
1056
1057 void lov_lock_unlink(const struct lu_env *env,
1058                      struct lov_lock_link *link, struct lovsub_lock *sub)
1059 {
1060         struct lov_lock *lck    = link->lll_super;
1061         struct cl_lock  *parent = lck->lls_cl.cls_lock;
1062
1063         LASSERT(cl_lock_is_mutexed(parent));
1064         LASSERT(cl_lock_is_mutexed(sub->lss_cl.cls_lock));
1065         ENTRY;
1066
1067         list_del_init(&link->lll_list);
1068         LASSERT(lck->lls_sub[link->lll_idx].sub_lock == sub);
1069         /* yank this sub-lock from parent's array */
1070         lck->lls_sub[link->lll_idx].sub_lock = NULL;
1071         LASSERT(lck->lls_nr_filled > 0);
1072         lck->lls_nr_filled--;
1073         lu_ref_del(&parent->cll_reference, "lov-child", sub->lss_cl.cls_lock);
1074         cl_lock_put(env, parent);
1075         OBD_SLAB_FREE_PTR(link, lov_lock_link_kmem);
1076         EXIT;
1077 }
1078
1079 struct lov_lock_link *lov_lock_link_find(const struct lu_env *env,
1080                                          struct lov_lock *lck,
1081                                          struct lovsub_lock *sub)
1082 {
1083         struct lov_lock_link *scan;
1084
1085         LASSERT(cl_lock_is_mutexed(sub->lss_cl.cls_lock));
1086         ENTRY;
1087
1088         list_for_each_entry(scan, &sub->lss_parents, lll_list) {
1089                 if (scan->lll_super == lck)
1090                         RETURN(scan);
1091         }
1092         RETURN(NULL);
1093 }
1094
1095 /**
1096  * An implementation of cl_lock_operations::clo_delete() method. This is
1097  * invoked for "top-to-bottom" delete, when lock destruction starts from the
1098  * top-lock, e.g., as a result of inode destruction.
1099  *
1100  * Unlinks top-lock from all its sub-locks. Sub-locks are not deleted there:
1101  * this is done separately elsewhere:
1102  *
1103  *     - for inode destruction, lov_object_delete() calls cl_object_kill() for
1104  *       each sub-object, purging its locks;
1105  *
1106  *     - in other cases (e.g., a fatal error with a top-lock) sub-locks are
1107  *       left in the cache.
1108  */
1109 static void lov_lock_delete(const struct lu_env *env,
1110                             const struct cl_lock_slice *slice)
1111 {
1112         struct lov_lock        *lck     = cl2lov_lock(slice);
1113         struct cl_lock_closure *closure = lov_closure_get(env, slice->cls_lock);
1114         struct lov_lock_link   *link;
1115         int                     rc;
1116         int                     i;
1117
1118         LASSERT(slice->cls_lock->cll_state == CLS_FREEING);
1119         ENTRY;
1120
1121         for (i = 0; i < lck->lls_nr; ++i) {
1122                 struct lov_lock_sub *lls = &lck->lls_sub[i];
1123                 struct lovsub_lock  *lsl = lls->sub_lock;
1124
1125                 if (lsl == NULL) /* already removed */
1126                         continue;
1127
1128                 rc = lov_sublock_lock(env, lck, lls, closure, NULL);
1129                 if (rc == CLO_REPEAT) {
1130                         --i;
1131                         continue;
1132                 }
1133
1134                 LASSERT(rc == 0);
1135                 LASSERT(lsl->lss_cl.cls_lock->cll_state < CLS_FREEING);
1136
1137                 if (lls->sub_flags & LSF_HELD)
1138                         lov_sublock_release(env, lck, i, 1, 0);
1139
1140                 link = lov_lock_link_find(env, lck, lsl);
1141                 LASSERT(link != NULL);
1142                 lov_lock_unlink(env, link, lsl);
1143                 LASSERT(lck->lls_sub[i].sub_lock == NULL);
1144
1145                 lov_sublock_unlock(env, lsl, closure, NULL);
1146         }
1147
1148         cl_lock_closure_fini(closure);
1149         EXIT;
1150 }
1151
1152 static int lov_lock_print(const struct lu_env *env, void *cookie,
1153                           lu_printer_t p, const struct cl_lock_slice *slice)
1154 {
1155         struct lov_lock *lck = cl2lov_lock(slice);
1156         int              i;
1157
1158         (*p)(env, cookie, "%d\n", lck->lls_nr);
1159         for (i = 0; i < lck->lls_nr; ++i) {
1160                 struct lov_lock_sub *sub;
1161
1162                 sub = &lck->lls_sub[i];
1163                 (*p)(env, cookie, "    %d %x: ", i, sub->sub_flags);
1164                 if (sub->sub_lock != NULL)
1165                         cl_lock_print(env, cookie, p,
1166                                       sub->sub_lock->lss_cl.cls_lock);
1167                 else
1168                         (*p)(env, cookie, "---\n");
1169         }
1170         return 0;
1171 }
1172
1173 static const struct cl_lock_operations lov_lock_ops = {
1174         .clo_fini      = lov_lock_fini,
1175         .clo_enqueue   = lov_lock_enqueue,
1176         .clo_wait      = lov_lock_wait,
1177         .clo_use       = lov_lock_use,
1178         .clo_unuse     = lov_lock_unuse,
1179         .clo_cancel    = lov_lock_cancel,
1180         .clo_fits_into = lov_lock_fits_into,
1181         .clo_delete    = lov_lock_delete,
1182         .clo_print     = lov_lock_print
1183 };
1184
1185 int lov_lock_init_raid0(const struct lu_env *env, struct cl_object *obj,
1186                         struct cl_lock *lock, const struct cl_io *io)
1187 {
1188         struct lov_lock *lck;
1189         int result;
1190
1191         ENTRY;
1192         OBD_SLAB_ALLOC_PTR_GFP(lck, lov_lock_kmem, GFP_NOFS);
1193         if (lck != NULL) {
1194                 cl_lock_slice_add(lock, &lck->lls_cl, obj, &lov_lock_ops);
1195                 result = lov_lock_sub_init(env, lck, io);
1196         } else
1197                 result = -ENOMEM;
1198         RETURN(result);
1199 }
1200
1201 static void lov_empty_lock_fini(const struct lu_env *env,
1202                                 struct cl_lock_slice *slice)
1203 {
1204         struct lov_lock *lck = cl2lov_lock(slice);
1205         OBD_SLAB_FREE_PTR(lck, lov_lock_kmem);
1206 }
1207
1208 static int lov_empty_lock_print(const struct lu_env *env, void *cookie,
1209                         lu_printer_t p, const struct cl_lock_slice *slice)
1210 {
1211         (*p)(env, cookie, "empty\n");
1212         return 0;
1213 }
1214
1215 /* XXX: more methods will be added later. */
1216 static const struct cl_lock_operations lov_empty_lock_ops = {
1217         .clo_fini  = lov_empty_lock_fini,
1218         .clo_print = lov_empty_lock_print
1219 };
1220
1221 int lov_lock_init_empty(const struct lu_env *env, struct cl_object *obj,
1222                         struct cl_lock *lock, const struct cl_io *io)
1223 {
1224         struct lov_lock *lck;
1225         int result = -ENOMEM;
1226
1227         ENTRY;
1228         OBD_SLAB_ALLOC_PTR_GFP(lck, lov_lock_kmem, GFP_NOFS);
1229         if (lck != NULL) {
1230                 cl_lock_slice_add(lock, &lck->lls_cl, obj, &lov_empty_lock_ops);
1231                 lck->lls_orig = lock->cll_descr;
1232                 result = 0;
1233         }
1234         RETURN(result);
1235 }
1236
1237 static struct cl_lock_closure *lov_closure_get(const struct lu_env *env,
1238                                                struct cl_lock *parent)
1239 {
1240         struct cl_lock_closure *closure;
1241
1242         closure = &lov_env_info(env)->lti_closure;
1243         LASSERT(list_empty(&closure->clc_list));
1244         cl_lock_closure_init(env, closure, parent, 1);
1245         return closure;
1246 }
1247
1248
1249 /** @} lov */