lustre/osc/osc_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 Whamcloud, Inc.
  33  *
  34  */
  35 /*
  36  * This file is part of Lustre, http://www.lustre.org/
  37  * Lustre is a trademark of Sun Microsystems, Inc.
  38  *
  39  * Implementation of cl_lock for OSC layer.
  40  *
  41  *   Author: Nikita Danilov <nikita.danilov@sun.com>
  42  */
  43
  44 #define DEBUG_SUBSYSTEM S_OSC
  45
  46 #ifdef __KERNEL__
  47 # include <libcfs/libcfs.h>
  48 #else
  49 # include <liblustre.h>
  50 #endif
  51 /* fid_build_reg_res_name() */
  52 #include <lustre_fid.h>
  53
  54 #include "osc_cl_internal.h"
  55
  56 /** \addtogroup osc
  57  *  @{
  58  */
  59
  60 #define _PAGEREF_MAGIC  (-10000000)
  61
  62 /*****************************************************************************
  63  *
  64  * Type conversions.
  65  *
  66  */
  67
  68 static const struct cl_lock_operations osc_lock_ops;
  69 static const struct cl_lock_operations osc_lock_lockless_ops;
  70 static void osc_lock_to_lockless(const struct lu_env *env,
  71                                  struct osc_lock *ols, int force);
  72 static int osc_lock_has_pages(struct osc_lock *olck);
  73
  74 int osc_lock_is_lockless(const struct osc_lock *olck)
  75 {
  76         return (olck->ols_cl.cls_ops == &osc_lock_lockless_ops);
  77 }
  78
  79 /**
  80  * Returns a weak pointer to the ldlm lock identified by a handle. Returned
  81  * pointer cannot be dereferenced, as lock is not protected from concurrent
  82  * reclaim. This function is a helper for osc_lock_invariant().
  83  */
  84 static struct ldlm_lock *osc_handle_ptr(struct lustre_handle *handle)
  85 {
  86         struct ldlm_lock *lock;
  87
  88         lock = ldlm_handle2lock(handle);
  89         if (lock != NULL)
  90                 LDLM_LOCK_PUT(lock);
  91         return lock;
  92 }
  93
  94 /**
  95  * Invariant that has to be true all of the time.
  96  */
  97 static int osc_lock_invariant(struct osc_lock *ols)
  98 {
  99         struct ldlm_lock *lock        = osc_handle_ptr(&ols->ols_handle);
 100         struct ldlm_lock *olock       = ols->ols_lock;
 101         int               handle_used = lustre_handle_is_used(&ols->ols_handle);
 102
 103         return
 104                 ergo(osc_lock_is_lockless(ols),
 105                      ols->ols_locklessable && ols->ols_lock == NULL)  ||
 106                 (ergo(olock != NULL, handle_used) &&
 107                  ergo(olock != NULL,
 108                       olock->l_handle.h_cookie == ols->ols_handle.cookie) &&
 109                  /*
 110                   * Check that ->ols_handle and ->ols_lock are consistent, but
 111                   * take into account that they are set at the different time.
 112                   */
 113                  ergo(handle_used,
 114                       ergo(lock != NULL && olock != NULL, lock == olock) &&
 115                       ergo(lock == NULL, olock == NULL)) &&
 116                  ergo(ols->ols_state == OLS_CANCELLED,
 117                       olock == NULL && !handle_used) &&
 118                  /*
 119                   * DLM lock is destroyed only after we have seen cancellation
 120                   * ast.
 121                   */
 122                  ergo(olock != NULL && ols->ols_state < OLS_CANCELLED,
 123                       !olock->l_destroyed) &&
 124                  ergo(ols->ols_state == OLS_GRANTED,
 125                       olock != NULL &&
 126                       olock->l_req_mode == olock->l_granted_mode &&
 127                       ols->ols_hold));
 128 }
 129
 130 /*****************************************************************************
 131  *
 132  * Lock operations.
 133  *
 134  */
 135
 136 /**
 137  * Breaks a link between osc_lock and dlm_lock.
 138  */
 139 static void osc_lock_detach(const struct lu_env *env, struct osc_lock *olck)
 140 {
 141         struct ldlm_lock *dlmlock;
 142
 143         cfs_spin_lock(&osc_ast_guard);
 144         dlmlock = olck->ols_lock;
 145         if (dlmlock == NULL) {
 146                 cfs_spin_unlock(&osc_ast_guard);
 147                 return;
 148         }
 149
 150         olck->ols_lock = NULL;
 151         /* wb(); --- for all who checks (ols->ols_lock != NULL) before
 152          * call to osc_lock_detach() */
 153         dlmlock->l_ast_data = NULL;
 154         olck->ols_handle.cookie = 0ULL;
 155         cfs_spin_unlock(&osc_ast_guard);
 156
 157         lock_res_and_lock(dlmlock);
 158         if (dlmlock->l_granted_mode == dlmlock->l_req_mode) {
 159                 struct cl_object *obj = olck->ols_cl.cls_obj;
 160                 struct cl_attr *attr  = &osc_env_info(env)->oti_attr;
 161                 __u64 old_kms;
 162
 163                 cl_object_attr_lock(obj);
 164                 /* Must get the value under the lock to avoid possible races. */
 165                 old_kms = cl2osc(obj)->oo_oinfo->loi_kms;
 166                 /* Update the kms. Need to loop all granted locks.
 167                  * Not a problem for the client */
 168                 attr->cat_kms = ldlm_extent_shift_kms(dlmlock, old_kms);
 169
 170                 cl_object_attr_set(env, obj, attr, CAT_KMS);
 171                 cl_object_attr_unlock(obj);
 172         }
 173         unlock_res_and_lock(dlmlock);
 174
 175         /* release a reference taken in osc_lock_upcall0(). */
 176         LASSERT(olck->ols_has_ref);
 177         lu_ref_del(&dlmlock->l_reference, "osc_lock", olck);
 178         LDLM_LOCK_RELEASE(dlmlock);
 179         olck->ols_has_ref = 0;
 180 }
 181
 182 static int osc_lock_unhold(struct osc_lock *ols)
 183 {
 184         int result = 0;
 185
 186         if (ols->ols_hold) {
 187                 ols->ols_hold = 0;
 188                 result = osc_cancel_base(&ols->ols_handle,
 189                                          ols->ols_einfo.ei_mode);
 190         }
 191         return result;
 192 }
 193
 194 static int osc_lock_unuse(const struct lu_env *env,
 195                           const struct cl_lock_slice *slice)
 196 {
 197         struct osc_lock *ols = cl2osc_lock(slice);
 198
 199         LINVRNT(osc_lock_invariant(ols));
 200
 201         switch (ols->ols_state) {
 202         case OLS_NEW:
 203                 LASSERT(!ols->ols_hold);
 204                 LASSERT(ols->ols_agl);
 205                 return 0;
 206         case OLS_UPCALL_RECEIVED:
 207                 LASSERT(!ols->ols_hold);
 208                 ols->ols_state = OLS_NEW;
 209                 return 0;
 210         case OLS_GRANTED:
 211                 LASSERT(!ols->ols_glimpse);
 212                 LASSERT(ols->ols_hold);
 213                 /*
 214                  * Move lock into OLS_RELEASED state before calling
 215                  * osc_cancel_base() so that possible synchronous cancellation
 216                  * (that always happens e.g., for liblustre) sees that lock is
 217                  * released.
 218                  */
 219                 ols->ols_state = OLS_RELEASED;
 220                 return osc_lock_unhold(ols);
 221         default:
 222                 CERROR("Impossible state: %d\n", ols->ols_state);
 223                 LBUG();
 224         }
 225 }
 226
 227 static void osc_lock_fini(const struct lu_env *env,
 228                           struct cl_lock_slice *slice)
 229 {
 230         struct osc_lock  *ols = cl2osc_lock(slice);
 231
 232         LINVRNT(osc_lock_invariant(ols));
 233         /*
 234          * ->ols_hold can still be true at this point if, for example, a
 235          * thread that requested a lock was killed (and released a reference
 236          * to the lock), before reply from a server was received. In this case
 237          * lock is destroyed immediately after upcall.
 238          */
 239         osc_lock_unhold(ols);
 240         LASSERT(ols->ols_lock == NULL);
 241         LASSERT(cfs_atomic_read(&ols->ols_pageref) == 0 ||
 242                 cfs_atomic_read(&ols->ols_pageref) == _PAGEREF_MAGIC);
 243
 244         OBD_SLAB_FREE_PTR(ols, osc_lock_kmem);
 245 }
 246
 247 void osc_lock_build_res(const struct lu_env *env, const struct osc_object *obj,
 248                         struct ldlm_res_id *resname)
 249 {
 250         const struct lu_fid *fid = lu_object_fid(&obj->oo_cl.co_lu);
 251         if (0) {
 252                 /*
 253                  * In the perfect world of the future, where ost servers talk
 254                  * idif-fids...
 255                  */
 256                 fid_build_reg_res_name(fid, resname);
 257         } else {
 258                 /*
 259                  * In reality, where ost server expects ->lsm_object_id and
 260                  * ->lsm_object_seq in rename.
 261                  */
 262                 osc_build_res_name(obj->oo_oinfo->loi_id, obj->oo_oinfo->loi_seq,
 263                                    resname);
 264         }
 265 }
 266
 267 static void osc_lock_build_policy(const struct lu_env *env,
 268                                   const struct cl_lock *lock,
 269                                   ldlm_policy_data_t *policy)
 270 {
 271         const struct cl_lock_descr *d = &lock->cll_descr;
 272
 273         osc_index2policy(policy, d->cld_obj, d->cld_start, d->cld_end);
 274         policy->l_extent.gid = d->cld_gid;
 275 }
 276
 277 static int osc_enq2ldlm_flags(__u32 enqflags)
 278 {
 279         int result = 0;
 280
 281         LASSERT((enqflags & ~CEF_MASK) == 0);
 282
 283         if (enqflags & CEF_NONBLOCK)
 284                 result |= LDLM_FL_BLOCK_NOWAIT;
 285         if (enqflags & CEF_ASYNC)
 286                 result |= LDLM_FL_HAS_INTENT;
 287         if (enqflags & CEF_DISCARD_DATA)
 288                 result |= LDLM_AST_DISCARD_DATA;
 289         return result;
 290 }
 291
 292 /**
 293  * Global spin-lock protecting consistency of ldlm_lock::l_ast_data
 294  * pointers. Initialized in osc_init().
 295  */
 296 cfs_spinlock_t osc_ast_guard;
 297
 298 static struct osc_lock *osc_ast_data_get(struct ldlm_lock *dlm_lock)
 299 {
 300         struct osc_lock *olck;
 301
 302         lock_res_and_lock(dlm_lock);
 303         cfs_spin_lock(&osc_ast_guard);
 304         olck = dlm_lock->l_ast_data;
 305         if (olck != NULL) {
 306                 struct cl_lock *lock = olck->ols_cl.cls_lock;
 307                 /*
 308                  * If osc_lock holds a reference on ldlm lock, return it even
 309                  * when cl_lock is in CLS_FREEING state. This way
 310                  *
 311                  *         osc_ast_data_get(dlmlock) == NULL
 312                  *
 313                  * guarantees that all osc references on dlmlock were
 314                  * released. osc_dlm_blocking_ast0() relies on that.
 315                  */
 316                 if (lock->cll_state < CLS_FREEING || olck->ols_has_ref) {
 317                         cl_lock_get_trust(lock);
 318                         lu_ref_add_atomic(&lock->cll_reference,
 319                                           "ast", cfs_current());
 320                 } else
 321                         olck = NULL;
 322         }
 323         cfs_spin_unlock(&osc_ast_guard);
 324         unlock_res_and_lock(dlm_lock);
 325         return olck;
 326 }
 327
 328 static void osc_ast_data_put(const struct lu_env *env, struct osc_lock *olck)
 329 {
 330         struct cl_lock *lock;
 331
 332         lock = olck->ols_cl.cls_lock;
 333         lu_ref_del(&lock->cll_reference, "ast", cfs_current());
 334         cl_lock_put(env, lock);
 335 }
 336
 337 /**
 338  * Updates object attributes from a lock value block (lvb) received together
 339  * with the DLM lock reply from the server. Copy of osc_update_enqueue()
 340  * logic.
 341  *
 342  * This can be optimized to not update attributes when lock is a result of a
 343  * local match.
 344  *
 345  * Called under lock and resource spin-locks.
 346  */
 347 static void osc_lock_lvb_update(const struct lu_env *env, struct osc_lock *olck,
 348                                 int rc)
 349 {
 350         struct ost_lvb    *lvb;
 351         struct cl_object  *obj;
 352         struct lov_oinfo  *oinfo;
 353         struct cl_attr    *attr;
 354         unsigned           valid;
 355
 356         ENTRY;
 357
 358         if (!(olck->ols_flags & LDLM_FL_LVB_READY))
 359                 RETURN_EXIT;
 360
 361         lvb   = &olck->ols_lvb;
 362         obj   = olck->ols_cl.cls_obj;
 363         oinfo = cl2osc(obj)->oo_oinfo;
 364         attr  = &osc_env_info(env)->oti_attr;
 365         valid = CAT_BLOCKS | CAT_ATIME | CAT_CTIME | CAT_MTIME | CAT_SIZE;
 366         cl_lvb2attr(attr, lvb);
 367
 368         cl_object_attr_lock(obj);
 369         if (rc == 0) {
 370                 struct ldlm_lock  *dlmlock;
 371                 __u64 size;
 372
 373                 dlmlock = olck->ols_lock;
 374                 LASSERT(dlmlock != NULL);
 375
 376                 /* re-grab LVB from a dlm lock under DLM spin-locks. */
 377                 *lvb = *(struct ost_lvb *)dlmlock->l_lvb_data;
 378                 size = lvb->lvb_size;
 379                 /* Extend KMS up to the end of this lock and no further
 380                  * A lock on [x,y] means a KMS of up to y + 1 bytes! */
 381                 if (size > dlmlock->l_policy_data.l_extent.end)
 382                         size = dlmlock->l_policy_data.l_extent.end + 1;
 383                 if (size >= oinfo->loi_kms) {
 384                         LDLM_DEBUG(dlmlock, "lock acquired, setting rss="LPU64
 385                                    ", kms="LPU64, lvb->lvb_size, size);
 386                         valid |= CAT_KMS;
 387                         attr->cat_kms = size;
 388                 } else {
 389                         LDLM_DEBUG(dlmlock, "lock acquired, setting rss="
 390                                    LPU64"; leaving kms="LPU64", end="LPU64,
 391                                    lvb->lvb_size, oinfo->loi_kms,
 392                                    dlmlock->l_policy_data.l_extent.end);
 393                 }
 394                 ldlm_lock_allow_match_locked(dlmlock);
 395         } else if (rc == -ENAVAIL && olck->ols_glimpse) {
 396                 CDEBUG(D_INODE, "glimpsed, setting rss="LPU64"; leaving"
 397                        " kms="LPU64"\n", lvb->lvb_size, oinfo->loi_kms);
 398         } else
 399                 valid = 0;
 400
 401         if (valid != 0)
 402                 cl_object_attr_set(env, obj, attr, valid);
 403
 404         cl_object_attr_unlock(obj);
 405
 406         EXIT;
 407 }
 408
 409 /**
 410  * Called when a lock is granted, from an upcall (when server returned a
 411  * granted lock), or from completion AST, when server returned a blocked lock.
 412  *
 413  * Called under lock and resource spin-locks, that are released temporarily
 414  * here.
 415  */
 416 static void osc_lock_granted(const struct lu_env *env, struct osc_lock *olck,
 417                              struct ldlm_lock *dlmlock, int rc)
 418 {
 419         struct ldlm_extent   *ext;
 420         struct cl_lock       *lock;
 421         struct cl_lock_descr *descr;
 422
 423         LASSERT(dlmlock->l_granted_mode == dlmlock->l_req_mode);
 424
 425         ENTRY;
 426         if (olck->ols_state < OLS_GRANTED) {
 427                 lock  = olck->ols_cl.cls_lock;
 428                 ext   = &dlmlock->l_policy_data.l_extent;
 429                 descr = &osc_env_info(env)->oti_descr;
 430                 descr->cld_obj = lock->cll_descr.cld_obj;
 431
 432                 /* XXX check that ->l_granted_mode is valid. */
 433                 descr->cld_mode  = osc_ldlm2cl_lock(dlmlock->l_granted_mode);
 434                 descr->cld_start = cl_index(descr->cld_obj, ext->start);
 435                 descr->cld_end   = cl_index(descr->cld_obj, ext->end);
 436                 descr->cld_gid   = ext->gid;
 437                 /*
 438                  * tell upper layers the extent of the lock that was actually
 439                  * granted
 440                  */
 441                 olck->ols_state = OLS_GRANTED;
 442                 osc_lock_lvb_update(env, olck, rc);
 443
 444                 /* release DLM spin-locks to allow cl_lock_{modify,signal}()
 445                  * to take a semaphore on a parent lock. This is safe, because
 446                  * spin-locks are needed to protect consistency of
 447                  * dlmlock->l_*_mode and LVB, and we have finished processing
 448                  * them. */
 449                 unlock_res_and_lock(dlmlock);
 450                 cl_lock_modify(env, lock, descr);
 451                 cl_lock_signal(env, lock);
 452                 LINVRNT(osc_lock_invariant(olck));
 453                 lock_res_and_lock(dlmlock);
 454         }
 455         EXIT;
 456 }
 457
 458 static void osc_lock_upcall0(const struct lu_env *env, struct osc_lock *olck)
 459
 460 {
 461         struct ldlm_lock *dlmlock;
 462
 463         ENTRY;
 464
 465         dlmlock = ldlm_handle2lock_long(&olck->ols_handle, 0);
 466         LASSERT(dlmlock != NULL);
 467
 468         lock_res_and_lock(dlmlock);
 469         cfs_spin_lock(&osc_ast_guard);
 470         LASSERT(dlmlock->l_ast_data == olck);
 471         LASSERT(olck->ols_lock == NULL);
 472         olck->ols_lock = dlmlock;
 473         cfs_spin_unlock(&osc_ast_guard);
 474
 475         /*
 476          * Lock might be not yet granted. In this case, completion ast
 477          * (osc_ldlm_completion_ast()) comes later and finishes lock
 478          * granting.
 479          */
 480         if (dlmlock->l_granted_mode == dlmlock->l_req_mode)
 481                 osc_lock_granted(env, olck, dlmlock, 0);
 482         unlock_res_and_lock(dlmlock);
 483
 484         /*
 485          * osc_enqueue_interpret() decrefs asynchronous locks, counter
 486          * this.
 487          */
 488         ldlm_lock_addref(&olck->ols_handle, olck->ols_einfo.ei_mode);
 489         olck->ols_hold = 1;
 490
 491         /* lock reference taken by ldlm_handle2lock_long() is owned by
 492          * osc_lock and released in osc_lock_detach() */
 493         lu_ref_add(&dlmlock->l_reference, "osc_lock", olck);
 494         olck->ols_has_ref = 1;
 495 }
 496
 497 /**
 498  * Lock upcall function that is executed either when a reply to ENQUEUE rpc is
 499  * received from a server, or after osc_enqueue_base() matched a local DLM
 500  * lock.
 501  */
 502 static int osc_lock_upcall(void *cookie, int errcode)
 503 {
 504         struct osc_lock         *olck  = cookie;
 505         struct cl_lock_slice    *slice = &olck->ols_cl;
 506         struct cl_lock          *lock  = slice->cls_lock;
 507         struct lu_env           *env;
 508         struct cl_env_nest       nest;
 509
 510         ENTRY;
 511         env = cl_env_nested_get(&nest);
 512         if (!IS_ERR(env)) {
 513                 int rc;
 514
 515                 cl_lock_mutex_get(env, lock);
 516
 517                 LASSERT(lock->cll_state >= CLS_QUEUING);
 518                 if (olck->ols_state == OLS_ENQUEUED) {
 519                         olck->ols_state = OLS_UPCALL_RECEIVED;
 520                         rc = ldlm_error2errno(errcode);
 521                 } else if (olck->ols_state == OLS_CANCELLED) {
 522                         rc = -EIO;
 523                 } else {
 524                         CERROR("Impossible state: %d\n", olck->ols_state);
 525                         LBUG();
 526                 }
 527                 if (rc) {
 528                         struct ldlm_lock *dlmlock;
 529
 530                         dlmlock = ldlm_handle2lock(&olck->ols_handle);
 531                         if (dlmlock != NULL) {
 532                                 lock_res_and_lock(dlmlock);
 533                                 cfs_spin_lock(&osc_ast_guard);
 534                                 LASSERT(olck->ols_lock == NULL);
 535                                 dlmlock->l_ast_data = NULL;
 536                                 olck->ols_handle.cookie = 0ULL;
 537                                 cfs_spin_unlock(&osc_ast_guard);
 538                                 ldlm_lock_fail_match_locked(dlmlock, rc);
 539                                 unlock_res_and_lock(dlmlock);
 540                                 LDLM_LOCK_PUT(dlmlock);
 541                         }
 542                 } else {
 543                         if (olck->ols_glimpse)
 544                                 olck->ols_glimpse = 0;
 545                         osc_lock_upcall0(env, olck);
 546                 }
 547
 548                 /* Error handling, some errors are tolerable. */
 549                 if (olck->ols_locklessable && rc == -EUSERS) {
 550                         /* This is a tolerable error, turn this lock into
 551                          * lockless lock.
 552                          */
 553                         osc_object_set_contended(cl2osc(slice->cls_obj));
 554                         LASSERT(slice->cls_ops == &osc_lock_ops);
 555
 556                         /* Change this lock to ldlmlock-less lock. */
 557                         osc_lock_to_lockless(env, olck, 1);
 558                         olck->ols_state = OLS_GRANTED;
 559                         rc = 0;
 560                 } else if (olck->ols_glimpse && rc == -ENAVAIL) {
 561                         osc_lock_lvb_update(env, olck, rc);
 562                         cl_lock_delete(env, lock);
 563                         /* Hide the error. */
 564                         rc = 0;
 565                 }
 566
 567                 if (rc == 0) {
 568                         cl_lock_signal(env, lock);
 569                         /* del user for lock upcall cookie */
 570                         cl_unuse_try(env, lock);
 571                 } else {
 572                         /* del user for lock upcall cookie */
 573                         cl_lock_user_del(env, lock);
 574                         cl_lock_error(env, lock, rc);
 575                 }
 576
 577                 cl_lock_mutex_put(env, lock);
 578
 579                 /* release cookie reference, acquired by osc_lock_enqueue() */
 580                 lu_ref_del(&lock->cll_reference, "upcall", lock);
 581                 cl_lock_put(env, lock);
 582
 583                 cl_env_nested_put(&nest, env);
 584         } else
 585                 /* should never happen, similar to osc_ldlm_blocking_ast(). */
 586                 LBUG();
 587         RETURN(errcode);
 588 }
 589
 590 /**
 591  * Core of osc_dlm_blocking_ast() logic.
 592  */
 593 static void osc_lock_blocking(const struct lu_env *env,
 594                               struct ldlm_lock *dlmlock,
 595                               struct osc_lock *olck, int blocking)
 596 {
 597         struct cl_lock *lock = olck->ols_cl.cls_lock;
 598
 599         LASSERT(olck->ols_lock == dlmlock);
 600         CLASSERT(OLS_BLOCKED < OLS_CANCELLED);
 601         LASSERT(!osc_lock_is_lockless(olck));
 602
 603         /*
 604          * Lock might be still addref-ed here, if e.g., blocking ast
 605          * is sent for a failed lock.
 606          */
 607         osc_lock_unhold(olck);
 608
 609         if (blocking && olck->ols_state < OLS_BLOCKED)
 610                 /*
 611                  * Move osc_lock into OLS_BLOCKED before canceling the lock,
 612                  * because it recursively re-enters osc_lock_blocking(), with
 613                  * the state set to OLS_CANCELLED.
 614                  */
 615                 olck->ols_state = OLS_BLOCKED;
 616         /*
 617          * cancel and destroy lock at least once no matter how blocking ast is
 618          * entered (see comment above osc_ldlm_blocking_ast() for use
 619          * cases). cl_lock_cancel() and cl_lock_delete() are idempotent.
 620          */
 621         cl_lock_cancel(env, lock);
 622         cl_lock_delete(env, lock);
 623 }
 624
 625 /**
 626  * Helper for osc_dlm_blocking_ast() handling discrepancies between cl_lock
 627  * and ldlm_lock caches.
 628  */
 629 static int osc_dlm_blocking_ast0(const struct lu_env *env,
 630                                  struct ldlm_lock *dlmlock,
 631                                  void *data, int flag)
 632 {
 633         struct osc_lock *olck;
 634         struct cl_lock  *lock;
 635         int result;
 636         int cancel;
 637
 638         LASSERT(flag == LDLM_CB_BLOCKING || flag == LDLM_CB_CANCELING);
 639
 640         cancel = 0;
 641         olck = osc_ast_data_get(dlmlock);
 642         if (olck != NULL) {
 643                 lock = olck->ols_cl.cls_lock;
 644                 cl_lock_mutex_get(env, lock);
 645                 LINVRNT(osc_lock_invariant(olck));
 646                 if (olck->ols_ast_wait) {
 647                         /* wake up osc_lock_use() */
 648                         cl_lock_signal(env, lock);
 649                         olck->ols_ast_wait = 0;
 650                 }
 651                 /*
 652                  * Lock might have been canceled while this thread was
 653                  * sleeping for lock mutex, but olck is pinned in memory.
 654                  */
 655                 if (olck == dlmlock->l_ast_data) {
 656                         /*
 657                          * NOTE: DLM sends blocking AST's for failed locks
 658                          *       (that are still in pre-OLS_GRANTED state)
 659                          *       too, and they have to be canceled otherwise
 660                          *       DLM lock is never destroyed and stuck in
 661                          *       the memory.
 662                          *
 663                          *       Alternatively, ldlm_cli_cancel() can be
 664                          *       called here directly for osc_locks with
 665                          *       ols_state < OLS_GRANTED to maintain an
 666                          *       invariant that ->clo_cancel() is only called
 667                          *       for locks that were granted.
 668                          */
 669                         LASSERT(data == olck);
 670                         osc_lock_blocking(env, dlmlock,
 671                                           olck, flag == LDLM_CB_BLOCKING);
 672                 } else
 673                         cancel = 1;
 674                 cl_lock_mutex_put(env, lock);
 675                 osc_ast_data_put(env, olck);
 676         } else
 677                 /*
 678                  * DLM lock exists, but there is no cl_lock attached to it.
 679                  * This is a `normal' race. cl_object and its cl_lock's can be
 680                  * removed by memory pressure, together with all pages.
 681                  */
 682                 cancel = (flag == LDLM_CB_BLOCKING);
 683
 684         if (cancel) {
 685                 struct lustre_handle *lockh;
 686
 687                 lockh = &osc_env_info(env)->oti_handle;
 688                 ldlm_lock2handle(dlmlock, lockh);
 689                 result = ldlm_cli_cancel(lockh);
 690         } else
 691                 result = 0;
 692         return result;
 693 }
 694
 695 /**
 696  * Blocking ast invoked by ldlm when dlm lock is either blocking progress of
 697  * some other lock, or is canceled. This function is installed as a
 698  * ldlm_lock::l_blocking_ast() for client extent locks.
 699  *
 700  * Control flow is tricky, because ldlm uses the same call-back
 701  * (ldlm_lock::l_blocking_ast()) for both blocking and cancellation ast's.
 702  *
 703  * \param dlmlock lock for which ast occurred.
 704  *
 705  * \param new description of a conflicting lock in case of blocking ast.
 706  *
 707  * \param data value of dlmlock->l_ast_data
 708  *
 709  * \param flag LDLM_CB_BLOCKING or LDLM_CB_CANCELING. Used to distinguish
 710  *             cancellation and blocking ast's.
 711  *
 712  * Possible use cases:
 713  *
 714  *     - ldlm calls dlmlock->l_blocking_ast(..., LDLM_CB_CANCELING) to cancel
 715  *       lock due to lock lru pressure, or explicit user request to purge
 716  *       locks.
 717  *
 718  *     - ldlm calls dlmlock->l_blocking_ast(..., LDLM_CB_BLOCKING) to notify
 719  *       us that dlmlock conflicts with another lock that some client is
 720  *       enqueing. Lock is canceled.
 721  *
 722  *           - cl_lock_cancel() is called. osc_lock_cancel() calls
 723  *             ldlm_cli_cancel() that calls
 724  *
 725  *                  dlmlock->l_blocking_ast(..., LDLM_CB_CANCELING)
 726  *
 727  *             recursively entering osc_ldlm_blocking_ast().
 728  *
 729  *     - client cancels lock voluntary (e.g., as a part of early cancellation):
 730  *
 731  *           cl_lock_cancel()->
 732  *             osc_lock_cancel()->
 733  *               ldlm_cli_cancel()->
 734  *                 dlmlock->l_blocking_ast(..., LDLM_CB_CANCELING)
 735  *
 736  */
 737 static int osc_ldlm_blocking_ast(struct ldlm_lock *dlmlock,
 738                                  struct ldlm_lock_desc *new, void *data,
 739                                  int flag)
 740 {
 741         struct lu_env     *env;
 742         struct cl_env_nest nest;
 743         int                result;
 744
 745         /*
 746          * This can be called in the context of outer IO, e.g.,
 747          *
 748          *     cl_enqueue()->...
 749          *       ->osc_enqueue_base()->...
 750          *         ->ldlm_prep_elc_req()->...
 751          *           ->ldlm_cancel_callback()->...
 752          *             ->osc_ldlm_blocking_ast()
 753          *
 754          * new environment has to be created to not corrupt outer context.
 755          */
 756         env = cl_env_nested_get(&nest);
 757         if (!IS_ERR(env)) {
 758                 result = osc_dlm_blocking_ast0(env, dlmlock, data, flag);
 759                 cl_env_nested_put(&nest, env);
 760         } else {
 761                 result = PTR_ERR(env);
 762                 /*
 763                  * XXX This should never happen, as cl_lock is
 764                  * stuck. Pre-allocated environment a la vvp_inode_fini_env
 765                  * should be used.
 766                  */
 767                 LBUG();
 768         }
 769         if (result != 0) {
 770                 if (result == -ENODATA)
 771                         result = 0;
 772                 else
 773                         CERROR("BAST failed: %d\n", result);
 774         }
 775         return result;
 776 }
 777
 778 static int osc_ldlm_completion_ast(struct ldlm_lock *dlmlock,
 779                                    int flags, void *data)
 780 {
 781         struct cl_env_nest nest;
 782         struct lu_env     *env;
 783         struct osc_lock   *olck;
 784         struct cl_lock    *lock;
 785         int result;
 786         int dlmrc;
 787
 788         /* first, do dlm part of the work */
 789         dlmrc = ldlm_completion_ast_async(dlmlock, flags, data);
 790         /* then, notify cl_lock */
 791         env = cl_env_nested_get(&nest);
 792         if (!IS_ERR(env)) {
 793                 olck = osc_ast_data_get(dlmlock);
 794                 if (olck != NULL) {
 795                         lock = olck->ols_cl.cls_lock;
 796                         cl_lock_mutex_get(env, lock);
 797                         /*
 798                          * ldlm_handle_cp_callback() copied LVB from request
 799                          * to lock->l_lvb_data, store it in osc_lock.
 800                          */
 801                         LASSERT(dlmlock->l_lvb_data != NULL);
 802                         lock_res_and_lock(dlmlock);
 803                         olck->ols_lvb = *(struct ost_lvb *)dlmlock->l_lvb_data;
 804                         if (olck->ols_lock == NULL) {
 805                                 /*
 806                                  * upcall (osc_lock_upcall()) hasn't yet been
 807                                  * called. Do nothing now, upcall will bind
 808                                  * olck to dlmlock and signal the waiters.
 809                                  *
 810                                  * This maintains an invariant that osc_lock
 811                                  * and ldlm_lock are always bound when
 812                                  * osc_lock is in OLS_GRANTED state.
 813                                  */
 814                         } else if (dlmlock->l_granted_mode ==
 815                                    dlmlock->l_req_mode) {
 816                                 osc_lock_granted(env, olck, dlmlock, dlmrc);
 817                         }
 818                         unlock_res_and_lock(dlmlock);
 819
 820                         if (dlmrc != 0) {
 821                                 CL_LOCK_DEBUG(D_ERROR, env, lock,
 822                                               "dlmlock returned %d\n", dlmrc);
 823                                 cl_lock_error(env, lock, dlmrc);
 824                         }
 825                         cl_lock_mutex_put(env, lock);
 826                         osc_ast_data_put(env, olck);
 827                         result = 0;
 828                 } else
 829                         result = -ELDLM_NO_LOCK_DATA;
 830                 cl_env_nested_put(&nest, env);
 831         } else
 832                 result = PTR_ERR(env);
 833         return dlmrc ?: result;
 834 }
 835
 836 static int osc_ldlm_glimpse_ast(struct ldlm_lock *dlmlock, void *data)
 837 {
 838         struct ptlrpc_request  *req  = data;
 839         struct osc_lock        *olck;
 840         struct cl_lock         *lock;
 841         struct cl_object       *obj;
 842         struct cl_env_nest      nest;
 843         struct lu_env          *env;
 844         struct ost_lvb         *lvb;
 845         struct req_capsule     *cap;
 846         int                     result;
 847
 848         LASSERT(lustre_msg_get_opc(req->rq_reqmsg) == LDLM_GL_CALLBACK);
 849
 850         env = cl_env_nested_get(&nest);
 851         if (!IS_ERR(env)) {
 852                 /*
 853                  * osc_ast_data_get() has to go after environment is
 854                  * allocated, because osc_ast_data() acquires a
 855                  * reference to a lock, and it can only be released in
 856                  * environment.
 857                  */
 858                 olck = osc_ast_data_get(dlmlock);
 859                 if (olck != NULL) {
 860                         lock = olck->ols_cl.cls_lock;
 861                         cl_lock_mutex_get(env, lock);
 862                         cap = &req->rq_pill;
 863                         req_capsule_extend(cap, &RQF_LDLM_GL_CALLBACK);
 864                         req_capsule_set_size(cap, &RMF_DLM_LVB, RCL_SERVER,
 865                                              sizeof *lvb);
 866                         result = req_capsule_server_pack(cap);
 867                         if (result == 0) {
 868                                 lvb = req_capsule_server_get(cap, &RMF_DLM_LVB);
 869                                 obj = lock->cll_descr.cld_obj;
 870                                 result = cl_object_glimpse(env, obj, lvb);
 871                         }
 872                         cl_lock_mutex_put(env, lock);
 873                         osc_ast_data_put(env, olck);
 874                 } else {
 875                         /*
 876                          * These errors are normal races, so we don't want to
 877                          * fill the console with messages by calling
 878                          * ptlrpc_error()
 879                          */
 880                         lustre_pack_reply(req, 1, NULL, NULL);
 881                         result = -ELDLM_NO_LOCK_DATA;
 882                 }
 883                 cl_env_nested_put(&nest, env);
 884         } else
 885                 result = PTR_ERR(env);
 886         req->rq_status = result;
 887         return result;
 888 }
 889
 890 static unsigned long osc_lock_weigh(const struct lu_env *env,
 891                                     const struct cl_lock_slice *slice)
 892 {
 893         /*
 894          * don't need to grab coh_page_guard since we don't care the exact #
 895          * of pages..
 896          */
 897         return cl_object_header(slice->cls_obj)->coh_pages;
 898 }
 899
 900 /**
 901  * Get the weight of dlm lock for early cancellation.
 902  *
 903  * XXX: it should return the pages covered by this \a dlmlock.
 904  */
 905 static unsigned long osc_ldlm_weigh_ast(struct ldlm_lock *dlmlock)
 906 {
 907         struct cl_env_nest       nest;
 908         struct lu_env           *env;
 909         struct osc_lock         *lock;
 910         struct cl_lock          *cll;
 911         unsigned long            weight;
 912         ENTRY;
 913
 914         cfs_might_sleep();
 915         /*
 916          * osc_ldlm_weigh_ast has a complex context since it might be called
 917          * because of lock canceling, or from user's input. We have to make
 918          * a new environment for it. Probably it is implementation safe to use
 919          * the upper context because cl_lock_put don't modify environment
 920          * variables. But in case of ..
 921          */
 922         env = cl_env_nested_get(&nest);
 923         if (IS_ERR(env))
 924                 /* Mostly because lack of memory, tend to eliminate this lock*/
 925                 RETURN(0);
 926
 927         LASSERT(dlmlock->l_resource->lr_type == LDLM_EXTENT);
 928         lock = osc_ast_data_get(dlmlock);
 929         if (lock == NULL) {
 930                 /* cl_lock was destroyed because of memory pressure.
 931                  * It is much reasonable to assign this type of lock
 932                  * a lower cost.
 933                  */
 934                 GOTO(out, weight = 0);
 935         }
 936
 937         cll = lock->ols_cl.cls_lock;
 938         cl_lock_mutex_get(env, cll);
 939         weight = cl_lock_weigh(env, cll);
 940         cl_lock_mutex_put(env, cll);
 941         osc_ast_data_put(env, lock);
 942         EXIT;
 943
 944 out:
 945         cl_env_nested_put(&nest, env);
 946         return weight;
 947 }
 948
 949 static void osc_lock_build_einfo(const struct lu_env *env,
 950                                  const struct cl_lock *clock,
 951                                  struct osc_lock *lock,
 952                                  struct ldlm_enqueue_info *einfo)
 953 {
 954         enum cl_lock_mode mode;
 955
 956         mode = clock->cll_descr.cld_mode;
 957         if (mode == CLM_PHANTOM)
 958                 /*
 959                  * For now, enqueue all glimpse locks in read mode. In the
 960                  * future, client might choose to enqueue LCK_PW lock for
 961                  * glimpse on a file opened for write.
 962                  */
 963                 mode = CLM_READ;
 964
 965         einfo->ei_type   = LDLM_EXTENT;
 966         einfo->ei_mode   = osc_cl_lock2ldlm(mode);
 967         einfo->ei_cb_bl  = osc_ldlm_blocking_ast;
 968         einfo->ei_cb_cp  = osc_ldlm_completion_ast;
 969         einfo->ei_cb_gl  = osc_ldlm_glimpse_ast;
 970         einfo->ei_cb_wg  = osc_ldlm_weigh_ast;
 971         einfo->ei_cbdata = lock; /* value to be put into ->l_ast_data */
 972 }
 973
 974 /**
 975  * Determine if the lock should be converted into a lockless lock.
 976  *
 977  * Steps to check:
 978  * - if the lock has an explicite requirment for a non-lockless lock;
 979  * - if the io lock request type ci_lockreq;
 980  * - send the enqueue rpc to ost to make the further decision;
 981  * - special treat to truncate lockless lock
 982  *
 983  *  Additional policy can be implemented here, e.g., never do lockless-io
 984  *  for large extents.
 985  */
 986 static void osc_lock_to_lockless(const struct lu_env *env,
 987                                  struct osc_lock *ols, int force)
 988 {
 989         struct cl_lock_slice *slice = &ols->ols_cl;
 990         struct cl_lock *lock        = slice->cls_lock;
 991
 992         LASSERT(ols->ols_state == OLS_NEW ||
 993                 ols->ols_state == OLS_UPCALL_RECEIVED);
 994
 995         if (force) {
 996                 ols->ols_locklessable = 1;
 997                 LASSERT(cl_lock_is_mutexed(lock));
 998                 slice->cls_ops = &osc_lock_lockless_ops;
 999         } else {
1000                 struct osc_io *oio     = osc_env_io(env);
1001                 struct cl_io  *io      = oio->oi_cl.cis_io;
1002                 struct cl_object *obj  = slice->cls_obj;
1003                 struct osc_object *oob = cl2osc(obj);
1004                 const struct osc_device *osd = lu2osc_dev(obj->co_lu.lo_dev);
1005                 struct obd_connect_data *ocd;
1006
1007                 LASSERT(io->ci_lockreq == CILR_MANDATORY ||
1008                         io->ci_lockreq == CILR_MAYBE ||
1009                         io->ci_lockreq == CILR_NEVER);
1010
1011                 ocd = &class_exp2cliimp(osc_export(oob))->imp_connect_data;
1012                 ols->ols_locklessable = (io->ci_type != CIT_SETATTR) &&
1013                                 (io->ci_lockreq == CILR_MAYBE) &&
1014                                 (ocd->ocd_connect_flags & OBD_CONNECT_SRVLOCK);
1015                 if (io->ci_lockreq == CILR_NEVER ||
1016                         /* lockless IO */
1017                     (ols->ols_locklessable && osc_object_is_contended(oob)) ||
1018                         /* lockless truncate */
1019                     (cl_io_is_trunc(io) &&
1020                      (ocd->ocd_connect_flags & OBD_CONNECT_TRUNCLOCK) &&
1021                       osd->od_lockless_truncate)) {
1022                         ols->ols_locklessable = 1;
1023                         slice->cls_ops = &osc_lock_lockless_ops;
1024                 }
1025         }
1026         LASSERT(ergo(ols->ols_glimpse, !osc_lock_is_lockless(ols)));
1027 }
1028
1029 static int osc_lock_compatible(const struct osc_lock *qing,
1030                                const struct osc_lock *qed)
1031 {
1032         enum cl_lock_mode qing_mode;
1033         enum cl_lock_mode qed_mode;
1034
1035         qing_mode = qing->ols_cl.cls_lock->cll_descr.cld_mode;
1036         if (qed->ols_glimpse &&
1037             (qed->ols_state >= OLS_UPCALL_RECEIVED || qing_mode == CLM_READ))
1038                 return 1;
1039
1040         qed_mode = qed->ols_cl.cls_lock->cll_descr.cld_mode;
1041         return ((qing_mode == CLM_READ) && (qed_mode == CLM_READ));
1042 }
1043
1044 /**
1045  * Cancel all conflicting locks and wait for them to be destroyed.
1046  *
1047  * This function is used for two purposes:
1048  *
1049  *     - early cancel all conflicting locks before starting IO, and
1050  *
1051  *     - guarantee that pages added to the page cache by lockless IO are never
1052  *       covered by locks other than lockless IO lock, and, hence, are not
1053  *       visible to other threads.
1054  */
1055 static int osc_lock_enqueue_wait(const struct lu_env *env,
1056                                  const struct osc_lock *olck)
1057 {
1058         struct cl_lock          *lock    = olck->ols_cl.cls_lock;
1059         struct cl_lock_descr    *descr   = &lock->cll_descr;
1060         struct cl_object_header *hdr     = cl_object_header(descr->cld_obj);
1061         struct cl_lock          *scan;
1062         struct cl_lock          *conflict= NULL;
1063         int lockless                     = osc_lock_is_lockless(olck);
1064         int rc                           = 0;
1065         ENTRY;
1066
1067         LASSERT(cl_lock_is_mutexed(lock));
1068
1069         /* make it enqueue anyway for glimpse lock, because we actually
1070          * don't need to cancel any conflicting locks. */
1071         if (olck->ols_glimpse)
1072                 return 0;
1073
1074         cfs_spin_lock(&hdr->coh_lock_guard);
1075         cfs_list_for_each_entry(scan, &hdr->coh_locks, cll_linkage) {
1076                 struct cl_lock_descr *cld = &scan->cll_descr;
1077                 const struct osc_lock *scan_ols;
1078
1079                 if (scan == lock)
1080                         break;
1081
1082                 if (scan->cll_state < CLS_QUEUING ||
1083                     scan->cll_state == CLS_FREEING ||
1084                     cld->cld_start > descr->cld_end ||
1085                     cld->cld_end < descr->cld_start)
1086                         continue;
1087
1088                 /* overlapped and living locks. */
1089
1090                 /* We're not supposed to give up group lock. */
1091                 if (scan->cll_descr.cld_mode == CLM_GROUP) {
1092                         LASSERT(descr->cld_mode != CLM_GROUP ||
1093                                 descr->cld_gid != scan->cll_descr.cld_gid);
1094                         continue;
1095                 }
1096
1097                 scan_ols = osc_lock_at(scan);
1098
1099                 /* We need to cancel the compatible locks if we're enqueuing
1100                  * a lockless lock, for example:
1101                  * imagine that client has PR lock on [0, 1000], and thread T0
1102                  * is doing lockless IO in [500, 1500] region. Concurrent
1103                  * thread T1 can see lockless data in [500, 1000], which is
1104                  * wrong, because these data are possibly stale. */
1105                 if (!lockless && osc_lock_compatible(olck, scan_ols))
1106                         continue;
1107
1108                 /* Now @scan is conflicting with @lock, this means current
1109                  * thread have to sleep for @scan being destroyed. */
1110                 if (scan_ols->ols_owner == osc_env_io(env)) {
1111                         CERROR("DEADLOCK POSSIBLE!\n");
1112                         CL_LOCK_DEBUG(D_ERROR, env, scan, "queued.\n");
1113                         CL_LOCK_DEBUG(D_ERROR, env, lock, "queuing.\n");
1114                         libcfs_debug_dumpstack(NULL);
1115                 }
1116                 cl_lock_get_trust(scan);
1117                 conflict = scan;
1118                 break;
1119         }
1120         cfs_spin_unlock(&hdr->coh_lock_guard);
1121
1122         if (conflict) {
1123                 if (lock->cll_descr.cld_mode == CLM_GROUP) {
1124                         /* we want a group lock but a previous lock request
1125                          * conflicts, we do not wait but return 0 so the
1126                          * request is send to the server
1127                          */
1128                         CDEBUG(D_DLMTRACE, "group lock %p is conflicted "
1129                                            "with %p, no wait, send to server\n",
1130                                lock, conflict);
1131                         cl_lock_put(env, conflict);
1132                         rc = 0;
1133                 } else {
1134                         CDEBUG(D_DLMTRACE, "lock %p is conflicted with %p, "
1135                                            "will wait\n",
1136                                lock, conflict);
1137                         LASSERT(lock->cll_conflict == NULL);
1138                         lu_ref_add(&conflict->cll_reference, "cancel-wait",
1139                                    lock);
1140                         lock->cll_conflict = conflict;
1141                         rc = CLO_WAIT;
1142                 }
1143         }
1144         RETURN(rc);
1145 }
1146
1147 /**
1148  * Implementation of cl_lock_operations::clo_enqueue() method for osc
1149  * layer. This initiates ldlm enqueue:
1150  *
1151  *     - cancels conflicting locks early (osc_lock_enqueue_wait());
1152  *
1153  *     - calls osc_enqueue_base() to do actual enqueue.
1154  *
1155  * osc_enqueue_base() is supplied with an upcall function that is executed
1156  * when lock is received either after a local cached ldlm lock is matched, or
1157  * when a reply from the server is received.
1158  *
1159  * This function does not wait for the network communication to complete.
1160  */
1161 static int osc_lock_enqueue(const struct lu_env *env,
1162                             const struct cl_lock_slice *slice,
1163                             struct cl_io *unused, __u32 enqflags)
1164 {
1165         struct osc_lock          *ols     = cl2osc_lock(slice);
1166         struct cl_lock           *lock    = ols->ols_cl.cls_lock;
1167         int result;
1168         ENTRY;
1169
1170         LASSERT(cl_lock_is_mutexed(lock));
1171         LASSERTF(ols->ols_state == OLS_NEW,
1172                  "Impossible state: %d\n", ols->ols_state);
1173
1174         ols->ols_flags = osc_enq2ldlm_flags(enqflags);
1175         if (enqflags & CEF_AGL) {
1176                 ols->ols_flags |= LDLM_FL_BLOCK_NOWAIT;
1177                 ols->ols_agl = 1;
1178         }
1179         if (ols->ols_flags & LDLM_FL_HAS_INTENT)
1180                 ols->ols_glimpse = 1;
1181         if (!osc_lock_is_lockless(ols) && !(enqflags & CEF_MUST))
1182                 /* try to convert this lock to a lockless lock */
1183                 osc_lock_to_lockless(env, ols, (enqflags & CEF_NEVER));
1184
1185         result = osc_lock_enqueue_wait(env, ols);
1186         if (result == 0) {
1187                 if (!osc_lock_is_lockless(ols)) {
1188                         struct osc_object        *obj = cl2osc(slice->cls_obj);
1189                         struct osc_thread_info   *info = osc_env_info(env);
1190                         struct ldlm_res_id       *resname = &info->oti_resname;
1191                         ldlm_policy_data_t       *policy = &info->oti_policy;
1192                         struct ldlm_enqueue_info *einfo = &ols->ols_einfo;
1193
1194                         if (ols->ols_locklessable)
1195                                 ols->ols_flags |= LDLM_FL_DENY_ON_CONTENTION;
1196
1197                         /* a reference for lock, passed as an upcall cookie */
1198                         cl_lock_get(lock);
1199                         lu_ref_add(&lock->cll_reference, "upcall", lock);
1200                         /* a user for lock also */
1201                         cl_lock_user_add(env, lock);
1202                         ols->ols_state = OLS_ENQUEUED;
1203
1204                         /*
1205                          * XXX: this is possible blocking point as
1206                          * ldlm_lock_match(LDLM_FL_LVB_READY) waits for
1207                          * LDLM_CP_CALLBACK.
1208                          */
1209                         osc_lock_build_res(env, obj, resname);
1210                         osc_lock_build_policy(env, lock, policy);
1211                         result = osc_enqueue_base(osc_export(obj), resname,
1212                                           &ols->ols_flags, policy,
1213                                           &ols->ols_lvb,
1214                                           obj->oo_oinfo->loi_kms_valid,
1215                                           osc_lock_upcall,
1216                                           ols, einfo, &ols->ols_handle,
1217                                           PTLRPCD_SET, 1, ols->ols_agl);
1218                         if (result != 0) {
1219                                 cl_lock_user_del(env, lock);
1220                                 lu_ref_del(&lock->cll_reference,
1221                                            "upcall", lock);
1222                                 cl_lock_put(env, lock);
1223                                 if (unlikely(result == -ECANCELED)) {
1224                                         ols->ols_state = OLS_NEW;
1225                                         result = 0;
1226                                 }
1227                         }
1228                 } else {
1229                         ols->ols_state = OLS_GRANTED;
1230                         ols->ols_owner = osc_env_io(env);
1231                 }
1232         }
1233         LASSERT(ergo(ols->ols_glimpse, !osc_lock_is_lockless(ols)));
1234         RETURN(result);
1235 }
1236
1237 static int osc_lock_wait(const struct lu_env *env,
1238                          const struct cl_lock_slice *slice)
1239 {
1240         struct osc_lock *olck = cl2osc_lock(slice);
1241         struct cl_lock  *lock = olck->ols_cl.cls_lock;
1242
1243         LINVRNT(osc_lock_invariant(olck));
1244
1245         if (olck->ols_glimpse && olck->ols_state >= OLS_UPCALL_RECEIVED) {
1246                 if (olck->ols_flags & LDLM_FL_LVB_READY) {
1247                         return 0;
1248                 } else if (olck->ols_agl) {
1249                         olck->ols_state = OLS_NEW;
1250                 } else {
1251                         LASSERT(lock->cll_error);
1252                         return lock->cll_error;
1253                 }
1254         }
1255
1256         if (olck->ols_state == OLS_NEW) {
1257                 if (lock->cll_descr.cld_enq_flags & CEF_NO_REENQUEUE) {
1258                         return -ENAVAIL;
1259                 } else {
1260                         int rc;
1261
1262                         LASSERT(olck->ols_agl);
1263
1264                         rc = osc_lock_enqueue(env, slice, NULL, CEF_ASYNC |
1265                                                                 CEF_MUST);
1266                         if (rc != 0)
1267                                 return rc;
1268                         else
1269                                 return CLO_REENQUEUED;
1270                 }
1271         }
1272
1273         LASSERT(equi(olck->ols_state >= OLS_UPCALL_RECEIVED &&
1274                      lock->cll_error == 0, olck->ols_lock != NULL));
1275
1276         return lock->cll_error ?: olck->ols_state >= OLS_GRANTED ? 0 : CLO_WAIT;
1277 }
1278
1279 /**
1280  * An implementation of cl_lock_operations::clo_use() method that pins cached
1281  * lock.
1282  */
1283 static int osc_lock_use(const struct lu_env *env,
1284                         const struct cl_lock_slice *slice)
1285 {
1286         struct osc_lock *olck = cl2osc_lock(slice);
1287         int rc;
1288
1289         LASSERT(!olck->ols_hold);
1290
1291         /*
1292          * Atomically check for LDLM_FL_CBPENDING and addref a lock if this
1293          * flag is not set. This protects us from a concurrent blocking ast.
1294          */
1295         rc = ldlm_lock_addref_try(&olck->ols_handle, olck->ols_einfo.ei_mode);
1296         if (rc == 0) {
1297                 olck->ols_hold = 1;
1298                 olck->ols_state = OLS_GRANTED;
1299         } else {
1300                 struct cl_lock *lock;
1301
1302                 /*
1303                  * Lock is being cancelled somewhere within
1304                  * ldlm_handle_bl_callback(): LDLM_FL_CBPENDING is already
1305                  * set, but osc_ldlm_blocking_ast() hasn't yet acquired
1306                  * cl_lock mutex.
1307                  */
1308                 lock = slice->cls_lock;
1309                 LASSERT(lock->cll_state == CLS_INTRANSIT);
1310                 LASSERT(lock->cll_users > 0);
1311                 /* set a flag for osc_dlm_blocking_ast0() to signal the
1312                  * lock.*/
1313                 olck->ols_ast_wait = 1;
1314                 rc = CLO_WAIT;
1315         }
1316         return rc;
1317 }
1318
1319 static int osc_lock_flush(struct osc_lock *ols, int discard)
1320 {
1321         struct cl_lock       *lock  = ols->ols_cl.cls_lock;
1322         struct cl_env_nest    nest;
1323         struct lu_env        *env;
1324         int result = 0;
1325
1326         env = cl_env_nested_get(&nest);
1327         if (!IS_ERR(env)) {
1328                 result = cl_lock_page_out(env, lock, discard);
1329                 cl_env_nested_put(&nest, env);
1330         } else
1331                 result = PTR_ERR(env);
1332         if (result == 0) {
1333                 ols->ols_flush = 1;
1334                 LINVRNT(!osc_lock_has_pages(ols));
1335         }
1336         return result;
1337 }
1338
1339 /**
1340  * Implements cl_lock_operations::clo_cancel() method for osc layer. This is
1341  * called (as part of cl_lock_cancel()) when lock is canceled either voluntary
1342  * (LRU pressure, early cancellation, umount, etc.) or due to the conflict
1343  * with some other lock some where in the cluster. This function does the
1344  * following:
1345  *
1346  *     - invalidates all pages protected by this lock (after sending dirty
1347  *       ones to the server, as necessary);
1348  *
1349  *     - decref's underlying ldlm lock;
1350  *
1351  *     - cancels ldlm lock (ldlm_cli_cancel()).
1352  */
1353 static void osc_lock_cancel(const struct lu_env *env,
1354                             const struct cl_lock_slice *slice)
1355 {
1356         struct cl_lock   *lock    = slice->cls_lock;
1357         struct osc_lock  *olck    = cl2osc_lock(slice);
1358         struct ldlm_lock *dlmlock = olck->ols_lock;
1359         int               result  = 0;
1360         int               discard;
1361
1362         LASSERT(cl_lock_is_mutexed(lock));
1363         LINVRNT(osc_lock_invariant(olck));
1364
1365         if (dlmlock != NULL) {
1366                 int do_cancel;
1367
1368                 discard = !!(dlmlock->l_flags & LDLM_FL_DISCARD_DATA);
1369                 result = osc_lock_flush(olck, discard);
1370                 osc_lock_unhold(olck);
1371
1372                 lock_res_and_lock(dlmlock);
1373                 /* Now that we're the only user of dlm read/write reference,
1374                  * mostly the ->l_readers + ->l_writers should be zero.
1375                  * However, there is a corner case.
1376                  * See bug 18829 for details.*/
1377                 do_cancel = (dlmlock->l_readers == 0 &&
1378                              dlmlock->l_writers == 0);
1379                 dlmlock->l_flags |= LDLM_FL_CBPENDING;
1380                 unlock_res_and_lock(dlmlock);
1381                 if (do_cancel)
1382                         result = ldlm_cli_cancel(&olck->ols_handle);
1383                 if (result < 0)
1384                         CL_LOCK_DEBUG(D_ERROR, env, lock,
1385                                       "lock %p cancel failure with error(%d)\n",
1386                                       lock, result);
1387         }
1388         olck->ols_state = OLS_CANCELLED;
1389         olck->ols_flags &= ~LDLM_FL_LVB_READY;
1390         osc_lock_detach(env, olck);
1391 }
1392
1393 #ifdef INVARIANT_CHECK
1394 static int check_cb(const struct lu_env *env, struct cl_io *io,
1395                     struct cl_page *page, void *cbdata)
1396 {
1397         struct cl_lock *lock = cbdata;
1398
1399         if (lock->cll_descr.cld_mode == CLM_READ) {
1400                 struct cl_lock *tmp;
1401                 tmp = cl_lock_at_page(env, lock->cll_descr.cld_obj,
1402                                      page, lock, 1, 0);
1403                 if (tmp != NULL) {
1404                         cl_lock_put(env, tmp);
1405                         return CLP_GANG_OKAY;
1406                 }
1407         }
1408
1409         CL_LOCK_DEBUG(D_ERROR, env, lock, "still has pages\n");
1410         CL_PAGE_DEBUG(D_ERROR, env, page, "\n");
1411         return CLP_GANG_ABORT;
1412 }
1413
1414 /**
1415  * Returns true iff there are pages under \a olck not protected by other
1416  * locks.
1417  */
1418 static int osc_lock_has_pages(struct osc_lock *olck)
1419 {
1420         struct cl_lock       *lock;
1421         struct cl_lock_descr *descr;
1422         struct cl_object     *obj;
1423         struct osc_object    *oob;
1424         struct cl_env_nest    nest;
1425         struct cl_io         *io;
1426         struct lu_env        *env;
1427         int                   result;
1428
1429         env = cl_env_nested_get(&nest);
1430         if (IS_ERR(env))
1431                 return 0;
1432
1433         obj   = olck->ols_cl.cls_obj;
1434         oob   = cl2osc(obj);
1435         io    = &oob->oo_debug_io;
1436         lock  = olck->ols_cl.cls_lock;
1437         descr = &lock->cll_descr;
1438
1439         cfs_mutex_lock(&oob->oo_debug_mutex);
1440
1441         io->ci_obj = cl_object_top(obj);
1442         cl_io_init(env, io, CIT_MISC, io->ci_obj);
1443         do {
1444                 result = cl_page_gang_lookup(env, obj, io,
1445                                              descr->cld_start, descr->cld_end,
1446                                              check_cb, (void *)lock);
1447                 if (result == CLP_GANG_ABORT)
1448                         break;
1449                 if (result == CLP_GANG_RESCHED)
1450                         cfs_cond_resched();
1451         } while (result != CLP_GANG_OKAY);
1452         cl_io_fini(env, io);
1453         cfs_mutex_unlock(&oob->oo_debug_mutex);
1454         cl_env_nested_put(&nest, env);
1455
1456         return (result == CLP_GANG_ABORT);
1457 }
1458 #else
1459 static int osc_lock_has_pages(struct osc_lock *olck)
1460 {
1461         return 0;
1462 }
1463 #endif /* INVARIANT_CHECK */
1464
1465 static void osc_lock_delete(const struct lu_env *env,
1466                             const struct cl_lock_slice *slice)
1467 {
1468         struct osc_lock *olck;
1469
1470         olck = cl2osc_lock(slice);
1471         if (olck->ols_glimpse) {
1472                 LASSERT(!olck->ols_hold);
1473                 LASSERT(!olck->ols_lock);
1474                 return;
1475         }
1476
1477         LINVRNT(osc_lock_invariant(olck));
1478         LINVRNT(!osc_lock_has_pages(olck));
1479
1480         osc_lock_unhold(olck);
1481         osc_lock_detach(env, olck);
1482 }
1483
1484 /**
1485  * Implements cl_lock_operations::clo_state() method for osc layer.
1486  *
1487  * Maintains osc_lock::ols_owner field.
1488  *
1489  * This assumes that lock always enters CLS_HELD (from some other state) in
1490  * the same IO context as one that requested the lock. This should not be a
1491  * problem, because context is by definition shared by all activity pertaining
1492  * to the same high-level IO.
1493  */
1494 static void osc_lock_state(const struct lu_env *env,
1495                            const struct cl_lock_slice *slice,
1496                            enum cl_lock_state state)
1497 {
1498         struct osc_lock *lock = cl2osc_lock(slice);
1499
1500         /*
1501          * XXX multiple io contexts can use the lock at the same time.
1502          */
1503         LINVRNT(osc_lock_invariant(lock));
1504         if (state == CLS_HELD && slice->cls_lock->cll_state != CLS_HELD) {
1505                 struct osc_io *oio = osc_env_io(env);
1506
1507                 LASSERT(lock->ols_owner == NULL);
1508                 lock->ols_owner = oio;
1509         } else if (state != CLS_HELD)
1510                 lock->ols_owner = NULL;
1511 }
1512
1513 static int osc_lock_print(const struct lu_env *env, void *cookie,
1514                           lu_printer_t p, const struct cl_lock_slice *slice)
1515 {
1516         struct osc_lock *lock = cl2osc_lock(slice);
1517
1518         /*
1519          * XXX print ldlm lock and einfo properly.
1520          */
1521         (*p)(env, cookie, "%p %08x "LPX64" %d %p ",
1522              lock->ols_lock, lock->ols_flags, lock->ols_handle.cookie,
1523              lock->ols_state, lock->ols_owner);
1524         osc_lvb_print(env, cookie, p, &lock->ols_lvb);
1525         return 0;
1526 }
1527
1528 static int osc_lock_fits_into(const struct lu_env *env,
1529                               const struct cl_lock_slice *slice,
1530                               const struct cl_lock_descr *need,
1531                               const struct cl_io *io)
1532 {
1533         struct osc_lock *ols = cl2osc_lock(slice);
1534
1535         if (need->cld_enq_flags & CEF_NEVER)
1536                 return 0;
1537
1538         if (need->cld_mode == CLM_PHANTOM) {
1539                 if (ols->ols_agl)
1540                         return !(ols->ols_state > OLS_RELEASED);
1541
1542                 /*
1543                  * Note: the QUEUED lock can't be matched here, otherwise
1544                  * it might cause the deadlocks.
1545                  * In read_process,
1546                  * P1: enqueued read lock, create sublock1
1547                  * P2: enqueued write lock, create sublock2(conflicted
1548                  *     with sublock1).
1549                  * P1: Grant read lock.
1550                  * P1: enqueued glimpse lock(with holding sublock1_read),
1551                  *     matched with sublock2, waiting sublock2 to be granted.
1552                  *     But sublock2 can not be granted, because P1
1553                  *     will not release sublock1. Bang!
1554                  */
1555                 if (ols->ols_state < OLS_GRANTED ||
1556                     ols->ols_state > OLS_RELEASED)
1557                         return 0;
1558         } else if (need->cld_enq_flags & CEF_MUST) {
1559                 /*
1560                  * If the lock hasn't ever enqueued, it can't be matched
1561                  * because enqueue process brings in many information
1562                  * which can be used to determine things such as lockless,
1563                  * CEF_MUST, etc.
1564                  */
1565                 if (ols->ols_state < OLS_UPCALL_RECEIVED &&
1566                     ols->ols_locklessable)
1567                         return 0;
1568         }
1569         return 1;
1570 }
1571
1572 static const struct cl_lock_operations osc_lock_ops = {
1573         .clo_fini    = osc_lock_fini,
1574         .clo_enqueue = osc_lock_enqueue,
1575         .clo_wait    = osc_lock_wait,
1576         .clo_unuse   = osc_lock_unuse,
1577         .clo_use     = osc_lock_use,
1578         .clo_delete  = osc_lock_delete,
1579         .clo_state   = osc_lock_state,
1580         .clo_cancel  = osc_lock_cancel,
1581         .clo_weigh   = osc_lock_weigh,
1582         .clo_print   = osc_lock_print,
1583         .clo_fits_into = osc_lock_fits_into,
1584 };
1585
1586 static int osc_lock_lockless_unuse(const struct lu_env *env,
1587                                    const struct cl_lock_slice *slice)
1588 {
1589         struct osc_lock *ols = cl2osc_lock(slice);
1590         struct cl_lock *lock = slice->cls_lock;
1591
1592         LASSERT(ols->ols_state == OLS_GRANTED);
1593         LINVRNT(osc_lock_invariant(ols));
1594
1595         cl_lock_cancel(env, lock);
1596         cl_lock_delete(env, lock);
1597         return 0;
1598 }
1599
1600 static void osc_lock_lockless_cancel(const struct lu_env *env,
1601                                      const struct cl_lock_slice *slice)
1602 {
1603         struct osc_lock   *ols  = cl2osc_lock(slice);
1604         int result;
1605
1606         result = osc_lock_flush(ols, 0);
1607         if (result)
1608                 CERROR("Pages for lockless lock %p were not purged(%d)\n",
1609                        ols, result);
1610         ols->ols_state = OLS_CANCELLED;
1611 }
1612
1613 static int osc_lock_lockless_wait(const struct lu_env *env,
1614                                   const struct cl_lock_slice *slice)
1615 {
1616         struct osc_lock *olck = cl2osc_lock(slice);
1617         struct cl_lock  *lock = olck->ols_cl.cls_lock;
1618
1619         LINVRNT(osc_lock_invariant(olck));
1620         LASSERT(olck->ols_state >= OLS_UPCALL_RECEIVED);
1621
1622         return lock->cll_error;
1623 }
1624
1625 static void osc_lock_lockless_state(const struct lu_env *env,
1626                                     const struct cl_lock_slice *slice,
1627                                     enum cl_lock_state state)
1628 {
1629         struct osc_lock *lock = cl2osc_lock(slice);
1630
1631         LINVRNT(osc_lock_invariant(lock));
1632         if (state == CLS_HELD) {
1633                 struct osc_io *oio  = osc_env_io(env);
1634
1635                 LASSERT(ergo(lock->ols_owner, lock->ols_owner == oio));
1636                 lock->ols_owner = oio;
1637
1638                 /* set the io to be lockless if this lock is for io's
1639                  * host object */
1640                 if (cl_object_same(oio->oi_cl.cis_obj, slice->cls_obj))
1641                         oio->oi_lockless = 1;
1642         }
1643 }
1644
1645 static int osc_lock_lockless_fits_into(const struct lu_env *env,
1646                                        const struct cl_lock_slice *slice,
1647                                        const struct cl_lock_descr *need,
1648                                        const struct cl_io *io)
1649 {
1650         struct osc_lock *lock = cl2osc_lock(slice);
1651
1652         if (!(need->cld_enq_flags & CEF_NEVER))
1653                 return 0;
1654
1655         /* lockless lock should only be used by its owning io. b22147 */
1656         return (lock->ols_owner == osc_env_io(env));
1657 }
1658
1659 static const struct cl_lock_operations osc_lock_lockless_ops = {
1660         .clo_fini      = osc_lock_fini,
1661         .clo_enqueue   = osc_lock_enqueue,
1662         .clo_wait      = osc_lock_lockless_wait,
1663         .clo_unuse     = osc_lock_lockless_unuse,
1664         .clo_state     = osc_lock_lockless_state,
1665         .clo_fits_into = osc_lock_lockless_fits_into,
1666         .clo_cancel    = osc_lock_lockless_cancel,
1667         .clo_print     = osc_lock_print
1668 };
1669
1670 int osc_lock_init(const struct lu_env *env,
1671                   struct cl_object *obj, struct cl_lock *lock,
1672                   const struct cl_io *unused)
1673 {
1674         struct osc_lock *clk;
1675         int result;
1676
1677         OBD_SLAB_ALLOC_PTR_GFP(clk, osc_lock_kmem, CFS_ALLOC_IO);
1678         if (clk != NULL) {
1679                 osc_lock_build_einfo(env, lock, clk, &clk->ols_einfo);
1680                 cfs_atomic_set(&clk->ols_pageref, 0);
1681                 clk->ols_state = OLS_NEW;
1682                 cl_lock_slice_add(lock, &clk->ols_cl, obj, &osc_lock_ops);
1683                 result = 0;
1684         } else
1685                 result = -ENOMEM;
1686         return result;
1687 }
1688
1689 int osc_dlm_lock_pageref(struct ldlm_lock *dlm)
1690 {
1691         struct osc_lock *olock;
1692         int              rc = 0;
1693
1694         cfs_spin_lock(&osc_ast_guard);
1695         olock = dlm->l_ast_data;
1696         /*
1697          * there's a very rare race with osc_page_addref_lock(), but that
1698          * doesn't matter because in the worst case we don't cancel a lock
1699          * which we actually can, that's no harm.
1700          */
1701         if (olock != NULL &&
1702             cfs_atomic_add_return(_PAGEREF_MAGIC,
1703                                   &olock->ols_pageref) != _PAGEREF_MAGIC) {
1704                 cfs_atomic_sub(_PAGEREF_MAGIC, &olock->ols_pageref);
1705                 rc = 1;
1706         }
1707         cfs_spin_unlock(&osc_ast_guard);
1708         return rc;
1709 }
1710
1711 /** @} osc */