lustre/osc/osc_lock.c

   1 /*
   2  * GPL HEADER START
   3  *
   4  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 only,
   8  * as published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful, but
  11  * WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * General Public License version 2 for more details (a copy is included
  14  * in the LICENSE file that accompanied this code).
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * version 2 along with this program; If not, see
  18  * http://www.sun.com/software/products/lustre/docs/GPLv2.pdf
  19  *
  20  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
  21  * CA 95054 USA or visit www.sun.com if you need additional information or
  22  * have any questions.
  23  *
  24  * GPL HEADER END
  25  */
  26 /*
  27  * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
  28  * Use is subject to license terms.
  29  *
  30  * Copyright (c) 2011, 2012, Whamcloud, Inc.
  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 OSC layer.
  37  *
  38  *   Author: Nikita Danilov <nikita.danilov@sun.com>
  39  */
  40
  41 #define DEBUG_SUBSYSTEM S_OSC
  42
  43 #ifdef __KERNEL__
  44 # include <libcfs/libcfs.h>
  45 #else
  46 # include <liblustre.h>
  47 #endif
  48 /* fid_build_reg_res_name() */
  49 #include <lustre_fid.h>
  50
  51 #include "osc_cl_internal.h"
  52
  53 /** \addtogroup osc
  54  *  @{
  55  */
  56
  57 #define _PAGEREF_MAGIC  (-10000000)
  58
  59 /*****************************************************************************
  60  *
  61  * Type conversions.
  62  *
  63  */
  64
  65 static const struct cl_lock_operations osc_lock_ops;
  66 static const struct cl_lock_operations osc_lock_lockless_ops;
  67 static void osc_lock_to_lockless(const struct lu_env *env,
  68                                  struct osc_lock *ols, int force);
  69 static int osc_lock_has_pages(struct osc_lock *olck);
  70
  71 int osc_lock_is_lockless(const struct osc_lock *olck)
  72 {
  73         return (olck->ols_cl.cls_ops == &osc_lock_lockless_ops);
  74 }
  75
  76 /**
  77  * Returns a weak pointer to the ldlm lock identified by a handle. Returned
  78  * pointer cannot be dereferenced, as lock is not protected from concurrent
  79  * reclaim. This function is a helper for osc_lock_invariant().
  80  */
  81 static struct ldlm_lock *osc_handle_ptr(struct lustre_handle *handle)
  82 {
  83         struct ldlm_lock *lock;
  84
  85         lock = ldlm_handle2lock(handle);
  86         if (lock != NULL)
  87                 LDLM_LOCK_PUT(lock);
  88         return lock;
  89 }
  90
  91 /**
  92  * Invariant that has to be true all of the time.
  93  */
  94 static int osc_lock_invariant(struct osc_lock *ols)
  95 {
  96         struct ldlm_lock *lock        = osc_handle_ptr(&ols->ols_handle);
  97         struct ldlm_lock *olock       = ols->ols_lock;
  98         int               handle_used = lustre_handle_is_used(&ols->ols_handle);
  99
 100         return
 101                 ergo(osc_lock_is_lockless(ols),
 102                      ols->ols_locklessable && ols->ols_lock == NULL)  ||
 103                 (ergo(olock != NULL, handle_used) &&
 104                  ergo(olock != NULL,
 105                       olock->l_handle.h_cookie == ols->ols_handle.cookie) &&
 106                  /*
 107                   * Check that ->ols_handle and ->ols_lock are consistent, but
 108                   * take into account that they are set at the different time.
 109                   */
 110                  ergo(handle_used,
 111                       ergo(lock != NULL && olock != NULL, lock == olock) &&
 112                       ergo(lock == NULL, olock == NULL)) &&
 113                  ergo(ols->ols_state == OLS_CANCELLED,
 114                       olock == NULL && !handle_used) &&
 115                  /*
 116                   * DLM lock is destroyed only after we have seen cancellation
 117                   * ast.
 118                   */
 119                  ergo(olock != NULL && ols->ols_state < OLS_CANCELLED,
 120                       !olock->l_destroyed) &&
 121                  ergo(ols->ols_state == OLS_GRANTED,
 122                       olock != NULL &&
 123                       olock->l_req_mode == olock->l_granted_mode &&
 124                       ols->ols_hold));
 125 }
 126
 127 /*****************************************************************************
 128  *
 129  * Lock operations.
 130  *
 131  */
 132
 133 /**
 134  * Breaks a link between osc_lock and dlm_lock.
 135  */
 136 static void osc_lock_detach(const struct lu_env *env, struct osc_lock *olck)
 137 {
 138         struct ldlm_lock *dlmlock;
 139
 140         cfs_spin_lock(&osc_ast_guard);
 141         dlmlock = olck->ols_lock;
 142         if (dlmlock == NULL) {
 143                 cfs_spin_unlock(&osc_ast_guard);
 144                 return;
 145         }
 146
 147         olck->ols_lock = NULL;
 148         /* wb(); --- for all who checks (ols->ols_lock != NULL) before
 149          * call to osc_lock_detach() */
 150         dlmlock->l_ast_data = NULL;
 151         olck->ols_handle.cookie = 0ULL;
 152         cfs_spin_unlock(&osc_ast_guard);
 153
 154         lock_res_and_lock(dlmlock);
 155         if (dlmlock->l_granted_mode == dlmlock->l_req_mode) {
 156                 struct cl_object *obj = olck->ols_cl.cls_obj;
 157                 struct cl_attr *attr  = &osc_env_info(env)->oti_attr;
 158                 __u64 old_kms;
 159
 160                 cl_object_attr_lock(obj);
 161                 /* Must get the value under the lock to avoid possible races. */
 162                 old_kms = cl2osc(obj)->oo_oinfo->loi_kms;
 163                 /* Update the kms. Need to loop all granted locks.
 164                  * Not a problem for the client */
 165                 attr->cat_kms = ldlm_extent_shift_kms(dlmlock, old_kms);
 166
 167                 cl_object_attr_set(env, obj, attr, CAT_KMS);
 168                 cl_object_attr_unlock(obj);
 169         }
 170         unlock_res_and_lock(dlmlock);
 171
 172         /* release a reference taken in osc_lock_upcall0(). */
 173         LASSERT(olck->ols_has_ref);
 174         lu_ref_del(&dlmlock->l_reference, "osc_lock", olck);
 175         LDLM_LOCK_RELEASE(dlmlock);
 176         olck->ols_has_ref = 0;
 177 }
 178
 179 static int osc_lock_unhold(struct osc_lock *ols)
 180 {
 181         int result = 0;
 182
 183         if (ols->ols_hold) {
 184                 ols->ols_hold = 0;
 185                 result = osc_cancel_base(&ols->ols_handle,
 186                                          ols->ols_einfo.ei_mode);
 187         }
 188         return result;
 189 }
 190
 191 static int osc_lock_unuse(const struct lu_env *env,
 192                           const struct cl_lock_slice *slice)
 193 {
 194         struct osc_lock *ols = cl2osc_lock(slice);
 195
 196         LINVRNT(osc_lock_invariant(ols));
 197
 198         switch (ols->ols_state) {
 199         case OLS_NEW:
 200                 LASSERT(!ols->ols_hold);
 201                 LASSERT(ols->ols_agl);
 202                 return 0;
 203         case OLS_ENQUEUED:
 204         case OLS_UPCALL_RECEIVED:
 205                 LASSERT(!ols->ols_hold);
 206                 ols->ols_state = OLS_NEW;
 207                 return 0;
 208         case OLS_GRANTED:
 209                 LASSERT(!ols->ols_glimpse);
 210                 LASSERT(ols->ols_hold);
 211                 /*
 212                  * Move lock into OLS_RELEASED state before calling
 213                  * osc_cancel_base() so that possible synchronous cancellation
 214                  * (that always happens e.g., for liblustre) sees that lock is
 215                  * released.
 216                  */
 217                 ols->ols_state = OLS_RELEASED;
 218                 return osc_lock_unhold(ols);
 219         default:
 220                 CERROR("Impossible state: %d\n", ols->ols_state);
 221                 LBUG();
 222         }
 223 }
 224
 225 static void osc_lock_fini(const struct lu_env *env,
 226                           struct cl_lock_slice *slice)
 227 {
 228         struct osc_lock  *ols = cl2osc_lock(slice);
 229
 230         LINVRNT(osc_lock_invariant(ols));
 231         /*
 232          * ->ols_hold can still be true at this point if, for example, a
 233          * thread that requested a lock was killed (and released a reference
 234          * to the lock), before reply from a server was received. In this case
 235          * lock is destroyed immediately after upcall.
 236          */
 237         osc_lock_unhold(ols);
 238         LASSERT(ols->ols_lock == NULL);
 239         LASSERT(cfs_atomic_read(&ols->ols_pageref) == 0 ||
 240                 cfs_atomic_read(&ols->ols_pageref) == _PAGEREF_MAGIC);
 241
 242         OBD_SLAB_FREE_PTR(ols, osc_lock_kmem);
 243 }
 244
 245 void osc_lock_build_res(const struct lu_env *env, const struct osc_object *obj,
 246                         struct ldlm_res_id *resname)
 247 {
 248         const struct lu_fid *fid = lu_object_fid(&obj->oo_cl.co_lu);
 249         if (0) {
 250                 /*
 251                  * In the perfect world of the future, where ost servers talk
 252                  * idif-fids...
 253                  */
 254                 fid_build_reg_res_name(fid, resname);
 255         } else {
 256                 /*
 257                  * In reality, where ost server expects ->lsm_object_id and
 258                  * ->lsm_object_seq in rename.
 259                  */
 260                 osc_build_res_name(obj->oo_oinfo->loi_id, obj->oo_oinfo->loi_seq,
 261                                    resname);
 262         }
 263 }
 264
 265 static void osc_lock_build_policy(const struct lu_env *env,
 266                                   const struct cl_lock *lock,
 267                                   ldlm_policy_data_t *policy)
 268 {
 269         const struct cl_lock_descr *d = &lock->cll_descr;
 270
 271         osc_index2policy(policy, d->cld_obj, d->cld_start, d->cld_end);
 272         policy->l_extent.gid = d->cld_gid;
 273 }
 274
 275 static int osc_enq2ldlm_flags(__u32 enqflags)
 276 {
 277         int result = 0;
 278
 279         LASSERT((enqflags & ~CEF_MASK) == 0);
 280
 281         if (enqflags & CEF_NONBLOCK)
 282                 result |= LDLM_FL_BLOCK_NOWAIT;
 283         if (enqflags & CEF_ASYNC)
 284                 result |= LDLM_FL_HAS_INTENT;
 285         if (enqflags & CEF_DISCARD_DATA)
 286                 result |= LDLM_AST_DISCARD_DATA;
 287         return result;
 288 }
 289
 290 /**
 291  * Global spin-lock protecting consistency of ldlm_lock::l_ast_data
 292  * pointers. Initialized in osc_init().
 293  */
 294 cfs_spinlock_t osc_ast_guard;
 295
 296 static struct osc_lock *osc_ast_data_get(struct ldlm_lock *dlm_lock)
 297 {
 298         struct osc_lock *olck;
 299
 300         lock_res_and_lock(dlm_lock);
 301         cfs_spin_lock(&osc_ast_guard);
 302         olck = dlm_lock->l_ast_data;
 303         if (olck != NULL) {
 304                 struct cl_lock *lock = olck->ols_cl.cls_lock;
 305                 /*
 306                  * If osc_lock holds a reference on ldlm lock, return it even
 307                  * when cl_lock is in CLS_FREEING state. This way
 308                  *
 309                  *         osc_ast_data_get(dlmlock) == NULL
 310                  *
 311                  * guarantees that all osc references on dlmlock were
 312                  * released. osc_dlm_blocking_ast0() relies on that.
 313                  */
 314                 if (lock->cll_state < CLS_FREEING || olck->ols_has_ref) {
 315                         cl_lock_get_trust(lock);
 316                         lu_ref_add_atomic(&lock->cll_reference,
 317                                           "ast", cfs_current());
 318                 } else
 319                         olck = NULL;
 320         }
 321         cfs_spin_unlock(&osc_ast_guard);
 322         unlock_res_and_lock(dlm_lock);
 323         return olck;
 324 }
 325
 326 static void osc_ast_data_put(const struct lu_env *env, struct osc_lock *olck)
 327 {
 328         struct cl_lock *lock;
 329
 330         lock = olck->ols_cl.cls_lock;
 331         lu_ref_del(&lock->cll_reference, "ast", cfs_current());
 332         cl_lock_put(env, lock);
 333 }
 334
 335 /**
 336  * Updates object attributes from a lock value block (lvb) received together
 337  * with the DLM lock reply from the server. Copy of osc_update_enqueue()
 338  * logic.
 339  *
 340  * This can be optimized to not update attributes when lock is a result of a
 341  * local match.
 342  *
 343  * Called under lock and resource spin-locks.
 344  */
 345 static void osc_lock_lvb_update(const struct lu_env *env, struct osc_lock *olck,
 346                                 int rc)
 347 {
 348         struct ost_lvb    *lvb;
 349         struct cl_object  *obj;
 350         struct lov_oinfo  *oinfo;
 351         struct cl_attr    *attr;
 352         unsigned           valid;
 353
 354         ENTRY;
 355
 356         if (!(olck->ols_flags & LDLM_FL_LVB_READY))
 357                 RETURN_EXIT;
 358
 359         lvb   = &olck->ols_lvb;
 360         obj   = olck->ols_cl.cls_obj;
 361         oinfo = cl2osc(obj)->oo_oinfo;
 362         attr  = &osc_env_info(env)->oti_attr;
 363         valid = CAT_BLOCKS | CAT_ATIME | CAT_CTIME | CAT_MTIME | CAT_SIZE;
 364         cl_lvb2attr(attr, lvb);
 365
 366         cl_object_attr_lock(obj);
 367         if (rc == 0) {
 368                 struct ldlm_lock  *dlmlock;
 369                 __u64 size;
 370
 371                 dlmlock = olck->ols_lock;
 372                 LASSERT(dlmlock != NULL);
 373
 374                 /* re-grab LVB from a dlm lock under DLM spin-locks. */
 375                 *lvb = *(struct ost_lvb *)dlmlock->l_lvb_data;
 376                 size = lvb->lvb_size;
 377                 /* Extend KMS up to the end of this lock and no further
 378                  * A lock on [x,y] means a KMS of up to y + 1 bytes! */
 379                 if (size > dlmlock->l_policy_data.l_extent.end)
 380                         size = dlmlock->l_policy_data.l_extent.end + 1;
 381                 if (size >= oinfo->loi_kms) {
 382                         LDLM_DEBUG(dlmlock, "lock acquired, setting rss="LPU64
 383                                    ", kms="LPU64, lvb->lvb_size, size);
 384                         valid |= CAT_KMS;
 385                         attr->cat_kms = size;
 386                 } else {
 387                         LDLM_DEBUG(dlmlock, "lock acquired, setting rss="
 388                                    LPU64"; leaving kms="LPU64", end="LPU64,
 389                                    lvb->lvb_size, oinfo->loi_kms,
 390                                    dlmlock->l_policy_data.l_extent.end);
 391                 }
 392                 ldlm_lock_allow_match_locked(dlmlock);
 393         } else if (rc == -ENAVAIL && olck->ols_glimpse) {
 394                 CDEBUG(D_INODE, "glimpsed, setting rss="LPU64"; leaving"
 395                        " kms="LPU64"\n", lvb->lvb_size, oinfo->loi_kms);
 396         } else
 397                 valid = 0;
 398
 399         if (valid != 0)
 400                 cl_object_attr_set(env, obj, attr, valid);
 401
 402         cl_object_attr_unlock(obj);
 403
 404         EXIT;
 405 }
 406
 407 /**
 408  * Called when a lock is granted, from an upcall (when server returned a
 409  * granted lock), or from completion AST, when server returned a blocked lock.
 410  *
 411  * Called under lock and resource spin-locks, that are released temporarily
 412  * here.
 413  */
 414 static void osc_lock_granted(const struct lu_env *env, struct osc_lock *olck,
 415                              struct ldlm_lock *dlmlock, int rc)
 416 {
 417         struct ldlm_extent   *ext;
 418         struct cl_lock       *lock;
 419         struct cl_lock_descr *descr;
 420
 421         LASSERT(dlmlock->l_granted_mode == dlmlock->l_req_mode);
 422
 423         ENTRY;
 424         if (olck->ols_state < OLS_GRANTED) {
 425                 lock  = olck->ols_cl.cls_lock;
 426                 ext   = &dlmlock->l_policy_data.l_extent;
 427                 descr = &osc_env_info(env)->oti_descr;
 428                 descr->cld_obj = lock->cll_descr.cld_obj;
 429
 430                 /* XXX check that ->l_granted_mode is valid. */
 431                 descr->cld_mode  = osc_ldlm2cl_lock(dlmlock->l_granted_mode);
 432                 descr->cld_start = cl_index(descr->cld_obj, ext->start);
 433                 descr->cld_end   = cl_index(descr->cld_obj, ext->end);
 434                 descr->cld_gid   = ext->gid;
 435                 /*
 436                  * tell upper layers the extent of the lock that was actually
 437                  * granted
 438                  */
 439                 olck->ols_state = OLS_GRANTED;
 440                 osc_lock_lvb_update(env, olck, rc);
 441
 442                 /* release DLM spin-locks to allow cl_lock_{modify,signal}()
 443                  * to take a semaphore on a parent lock. This is safe, because
 444                  * spin-locks are needed to protect consistency of
 445                  * dlmlock->l_*_mode and LVB, and we have finished processing
 446                  * them. */
 447                 unlock_res_and_lock(dlmlock);
 448                 cl_lock_modify(env, lock, descr);
 449                 cl_lock_signal(env, lock);
 450                 LINVRNT(osc_lock_invariant(olck));
 451                 lock_res_and_lock(dlmlock);
 452         }
 453         EXIT;
 454 }
 455
 456 static void osc_lock_upcall0(const struct lu_env *env, struct osc_lock *olck)
 457
 458 {
 459         struct ldlm_lock *dlmlock;
 460
 461         ENTRY;
 462
 463         dlmlock = ldlm_handle2lock_long(&olck->ols_handle, 0);
 464         LASSERT(dlmlock != NULL);
 465
 466         lock_res_and_lock(dlmlock);
 467         cfs_spin_lock(&osc_ast_guard);
 468         LASSERT(dlmlock->l_ast_data == olck);
 469         LASSERT(olck->ols_lock == NULL);
 470         olck->ols_lock = dlmlock;
 471         cfs_spin_unlock(&osc_ast_guard);
 472
 473         /*
 474          * Lock might be not yet granted. In this case, completion ast
 475          * (osc_ldlm_completion_ast()) comes later and finishes lock
 476          * granting.
 477          */
 478         if (dlmlock->l_granted_mode == dlmlock->l_req_mode)
 479                 osc_lock_granted(env, olck, dlmlock, 0);
 480         unlock_res_and_lock(dlmlock);
 481
 482         /*
 483          * osc_enqueue_interpret() decrefs asynchronous locks, counter
 484          * this.
 485          */
 486         ldlm_lock_addref(&olck->ols_handle, olck->ols_einfo.ei_mode);
 487         olck->ols_hold = 1;
 488
 489         /* lock reference taken by ldlm_handle2lock_long() is owned by
 490          * osc_lock and released in osc_lock_detach() */
 491         lu_ref_add(&dlmlock->l_reference, "osc_lock", olck);
 492         olck->ols_has_ref = 1;
 493 }
 494
 495 /**
 496  * Lock upcall function that is executed either when a reply to ENQUEUE rpc is
 497  * received from a server, or after osc_enqueue_base() matched a local DLM
 498  * lock.
 499  */
 500 static int osc_lock_upcall(void *cookie, int errcode)
 501 {
 502         struct osc_lock         *olck  = cookie;
 503         struct cl_lock_slice    *slice = &olck->ols_cl;
 504         struct cl_lock          *lock  = slice->cls_lock;
 505         struct lu_env           *env;
 506         struct cl_env_nest       nest;
 507
 508         ENTRY;
 509         env = cl_env_nested_get(&nest);
 510         if (!IS_ERR(env)) {
 511                 int rc;
 512
 513                 cl_lock_mutex_get(env, lock);
 514
 515                 LASSERT(lock->cll_state >= CLS_QUEUING);
 516                 if (olck->ols_state == OLS_ENQUEUED) {
 517                         olck->ols_state = OLS_UPCALL_RECEIVED;
 518                         rc = ldlm_error2errno(errcode);
 519                 } else if (olck->ols_state == OLS_CANCELLED) {
 520                         rc = -EIO;
 521                 } else {
 522                         CERROR("Impossible state: %d\n", olck->ols_state);
 523                         LBUG();
 524                 }
 525                 if (rc) {
 526                         struct ldlm_lock *dlmlock;
 527
 528                         dlmlock = ldlm_handle2lock(&olck->ols_handle);
 529                         if (dlmlock != NULL) {
 530                                 lock_res_and_lock(dlmlock);
 531                                 cfs_spin_lock(&osc_ast_guard);
 532                                 LASSERT(olck->ols_lock == NULL);
 533                                 dlmlock->l_ast_data = NULL;
 534                                 olck->ols_handle.cookie = 0ULL;
 535                                 cfs_spin_unlock(&osc_ast_guard);
 536                                 ldlm_lock_fail_match_locked(dlmlock);
 537                                 unlock_res_and_lock(dlmlock);
 538                                 LDLM_LOCK_PUT(dlmlock);
 539                         }
 540                 } else {
 541                         if (olck->ols_glimpse)
 542                                 olck->ols_glimpse = 0;
 543                         osc_lock_upcall0(env, olck);
 544                 }
 545
 546                 /* Error handling, some errors are tolerable. */
 547                 if (olck->ols_locklessable && rc == -EUSERS) {
 548                         /* This is a tolerable error, turn this lock into
 549                          * lockless lock.
 550                          */
 551                         osc_object_set_contended(cl2osc(slice->cls_obj));
 552                         LASSERT(slice->cls_ops == &osc_lock_ops);
 553
 554                         /* Change this lock to ldlmlock-less lock. */
 555                         osc_lock_to_lockless(env, olck, 1);
 556                         olck->ols_state = OLS_GRANTED;
 557                         rc = 0;
 558                 } else if (olck->ols_glimpse && rc == -ENAVAIL) {
 559                         osc_lock_lvb_update(env, olck, rc);
 560                         cl_lock_delete(env, lock);
 561                         /* Hide the error. */
 562                         rc = 0;
 563                 }
 564
 565                 if (rc == 0) {
 566                         /* For AGL case, the RPC sponsor may exits the cl_lock
 567                         *  processing without wait() called before related OSC
 568                         *  lock upcall(). So update the lock status according
 569                         *  to the enqueue result inside AGL upcall(). */
 570                         if (olck->ols_agl) {
 571                                 lock->cll_flags |= CLF_FROM_UPCALL;
 572                                 cl_wait_try(env, lock);
 573                                 lock->cll_flags &= ~CLF_FROM_UPCALL;
 574                                 if (!olck->ols_glimpse)
 575                                         olck->ols_agl = 0;
 576                         }
 577                         cl_lock_signal(env, lock);
 578                         /* del user for lock upcall cookie */
 579                         cl_unuse_try(env, lock);
 580                 } else {
 581                         /* del user for lock upcall cookie */
 582                         cl_lock_user_del(env, lock);
 583                         cl_lock_error(env, lock, rc);
 584                 }
 585
 586                 cl_lock_mutex_put(env, lock);
 587
 588                 /* release cookie reference, acquired by osc_lock_enqueue() */
 589                 lu_ref_del(&lock->cll_reference, "upcall", lock);
 590                 cl_lock_put(env, lock);
 591
 592                 cl_env_nested_put(&nest, env);
 593         } else
 594                 /* should never happen, similar to osc_ldlm_blocking_ast(). */
 595                 LBUG();
 596         RETURN(errcode);
 597 }
 598
 599 /**
 600  * Core of osc_dlm_blocking_ast() logic.
 601  */
 602 static void osc_lock_blocking(const struct lu_env *env,
 603                               struct ldlm_lock *dlmlock,
 604                               struct osc_lock *olck, int blocking)
 605 {
 606         struct cl_lock *lock = olck->ols_cl.cls_lock;
 607
 608         LASSERT(olck->ols_lock == dlmlock);
 609         CLASSERT(OLS_BLOCKED < OLS_CANCELLED);
 610         LASSERT(!osc_lock_is_lockless(olck));
 611
 612         /*
 613          * Lock might be still addref-ed here, if e.g., blocking ast
 614          * is sent for a failed lock.
 615          */
 616         osc_lock_unhold(olck);
 617
 618         if (blocking && olck->ols_state < OLS_BLOCKED)
 619                 /*
 620                  * Move osc_lock into OLS_BLOCKED before canceling the lock,
 621                  * because it recursively re-enters osc_lock_blocking(), with
 622                  * the state set to OLS_CANCELLED.
 623                  */
 624                 olck->ols_state = OLS_BLOCKED;
 625         /*
 626          * cancel and destroy lock at least once no matter how blocking ast is
 627          * entered (see comment above osc_ldlm_blocking_ast() for use
 628          * cases). cl_lock_cancel() and cl_lock_delete() are idempotent.
 629          */
 630         cl_lock_cancel(env, lock);
 631         cl_lock_delete(env, lock);
 632 }
 633
 634 /**
 635  * Helper for osc_dlm_blocking_ast() handling discrepancies between cl_lock
 636  * and ldlm_lock caches.
 637  */
 638 static int osc_dlm_blocking_ast0(const struct lu_env *env,
 639                                  struct ldlm_lock *dlmlock,
 640                                  void *data, int flag)
 641 {
 642         struct osc_lock *olck;
 643         struct cl_lock  *lock;
 644         int result;
 645         int cancel;
 646
 647         LASSERT(flag == LDLM_CB_BLOCKING || flag == LDLM_CB_CANCELING);
 648
 649         cancel = 0;
 650         olck = osc_ast_data_get(dlmlock);
 651         if (olck != NULL) {
 652                 lock = olck->ols_cl.cls_lock;
 653                 cl_lock_mutex_get(env, lock);
 654                 LINVRNT(osc_lock_invariant(olck));
 655                 if (olck->ols_ast_wait) {
 656                         /* wake up osc_lock_use() */
 657                         cl_lock_signal(env, lock);
 658                         olck->ols_ast_wait = 0;
 659                 }
 660                 /*
 661                  * Lock might have been canceled while this thread was
 662                  * sleeping for lock mutex, but olck is pinned in memory.
 663                  */
 664                 if (olck == dlmlock->l_ast_data) {
 665                         /*
 666                          * NOTE: DLM sends blocking AST's for failed locks
 667                          *       (that are still in pre-OLS_GRANTED state)
 668                          *       too, and they have to be canceled otherwise
 669                          *       DLM lock is never destroyed and stuck in
 670                          *       the memory.
 671                          *
 672                          *       Alternatively, ldlm_cli_cancel() can be
 673                          *       called here directly for osc_locks with
 674                          *       ols_state < OLS_GRANTED to maintain an
 675                          *       invariant that ->clo_cancel() is only called
 676                          *       for locks that were granted.
 677                          */
 678                         LASSERT(data == olck);
 679                         osc_lock_blocking(env, dlmlock,
 680                                           olck, flag == LDLM_CB_BLOCKING);
 681                 } else
 682                         cancel = 1;
 683                 cl_lock_mutex_put(env, lock);
 684                 osc_ast_data_put(env, olck);
 685         } else
 686                 /*
 687                  * DLM lock exists, but there is no cl_lock attached to it.
 688                  * This is a `normal' race. cl_object and its cl_lock's can be
 689                  * removed by memory pressure, together with all pages.
 690                  */
 691                 cancel = (flag == LDLM_CB_BLOCKING);
 692
 693         if (cancel) {
 694                 struct lustre_handle *lockh;
 695
 696                 lockh = &osc_env_info(env)->oti_handle;
 697                 ldlm_lock2handle(dlmlock, lockh);
 698                 result = ldlm_cli_cancel(lockh);
 699         } else
 700                 result = 0;
 701         return result;
 702 }
 703
 704 /**
 705  * Blocking ast invoked by ldlm when dlm lock is either blocking progress of
 706  * some other lock, or is canceled. This function is installed as a
 707  * ldlm_lock::l_blocking_ast() for client extent locks.
 708  *
 709  * Control flow is tricky, because ldlm uses the same call-back
 710  * (ldlm_lock::l_blocking_ast()) for both blocking and cancellation ast's.
 711  *
 712  * \param dlmlock lock for which ast occurred.
 713  *
 714  * \param new description of a conflicting lock in case of blocking ast.
 715  *
 716  * \param data value of dlmlock->l_ast_data
 717  *
 718  * \param flag LDLM_CB_BLOCKING or LDLM_CB_CANCELING. Used to distinguish
 719  *             cancellation and blocking ast's.
 720  *
 721  * Possible use cases:
 722  *
 723  *     - ldlm calls dlmlock->l_blocking_ast(..., LDLM_CB_CANCELING) to cancel
 724  *       lock due to lock lru pressure, or explicit user request to purge
 725  *       locks.
 726  *
 727  *     - ldlm calls dlmlock->l_blocking_ast(..., LDLM_CB_BLOCKING) to notify
 728  *       us that dlmlock conflicts with another lock that some client is
 729  *       enqueing. Lock is canceled.
 730  *
 731  *           - cl_lock_cancel() is called. osc_lock_cancel() calls
 732  *             ldlm_cli_cancel() that calls
 733  *
 734  *                  dlmlock->l_blocking_ast(..., LDLM_CB_CANCELING)
 735  *
 736  *             recursively entering osc_ldlm_blocking_ast().
 737  *
 738  *     - client cancels lock voluntary (e.g., as a part of early cancellation):
 739  *
 740  *           cl_lock_cancel()->
 741  *             osc_lock_cancel()->
 742  *               ldlm_cli_cancel()->
 743  *                 dlmlock->l_blocking_ast(..., LDLM_CB_CANCELING)
 744  *
 745  */
 746 static int osc_ldlm_blocking_ast(struct ldlm_lock *dlmlock,
 747                                  struct ldlm_lock_desc *new, void *data,
 748                                  int flag)
 749 {
 750         struct lu_env     *env;
 751         struct cl_env_nest nest;
 752         int                result;
 753
 754         /*
 755          * This can be called in the context of outer IO, e.g.,
 756          *
 757          *     cl_enqueue()->...
 758          *       ->osc_enqueue_base()->...
 759          *         ->ldlm_prep_elc_req()->...
 760          *           ->ldlm_cancel_callback()->...
 761          *             ->osc_ldlm_blocking_ast()
 762          *
 763          * new environment has to be created to not corrupt outer context.
 764          */
 765         env = cl_env_nested_get(&nest);
 766         if (!IS_ERR(env)) {
 767                 result = osc_dlm_blocking_ast0(env, dlmlock, data, flag);
 768                 cl_env_nested_put(&nest, env);
 769         } else {
 770                 result = PTR_ERR(env);
 771                 /*
 772                  * XXX This should never happen, as cl_lock is
 773                  * stuck. Pre-allocated environment a la vvp_inode_fini_env
 774                  * should be used.
 775                  */
 776                 LBUG();
 777         }
 778         if (result != 0) {
 779                 if (result == -ENODATA)
 780                         result = 0;
 781                 else
 782                         CERROR("BAST failed: %d\n", result);
 783         }
 784         return result;
 785 }
 786
 787 static int osc_ldlm_completion_ast(struct ldlm_lock *dlmlock,
 788                                    int flags, void *data)
 789 {
 790         struct cl_env_nest nest;
 791         struct lu_env     *env;
 792         struct osc_lock   *olck;
 793         struct cl_lock    *lock;
 794         int result;
 795         int dlmrc;
 796
 797         /* first, do dlm part of the work */
 798         dlmrc = ldlm_completion_ast_async(dlmlock, flags, data);
 799         /* then, notify cl_lock */
 800         env = cl_env_nested_get(&nest);
 801         if (!IS_ERR(env)) {
 802                 olck = osc_ast_data_get(dlmlock);
 803                 if (olck != NULL) {
 804                         lock = olck->ols_cl.cls_lock;
 805                         cl_lock_mutex_get(env, lock);
 806                         /*
 807                          * ldlm_handle_cp_callback() copied LVB from request
 808                          * to lock->l_lvb_data, store it in osc_lock.
 809                          */
 810                         LASSERT(dlmlock->l_lvb_data != NULL);
 811                         lock_res_and_lock(dlmlock);
 812                         olck->ols_lvb = *(struct ost_lvb *)dlmlock->l_lvb_data;
 813                         if (olck->ols_lock == NULL) {
 814                                 /*
 815                                  * upcall (osc_lock_upcall()) hasn't yet been
 816                                  * called. Do nothing now, upcall will bind
 817                                  * olck to dlmlock and signal the waiters.
 818                                  *
 819                                  * This maintains an invariant that osc_lock
 820                                  * and ldlm_lock are always bound when
 821                                  * osc_lock is in OLS_GRANTED state.
 822                                  */
 823                         } else if (dlmlock->l_granted_mode ==
 824                                    dlmlock->l_req_mode) {
 825                                 osc_lock_granted(env, olck, dlmlock, dlmrc);
 826                         }
 827                         unlock_res_and_lock(dlmlock);
 828
 829                         if (dlmrc != 0) {
 830                                 CL_LOCK_DEBUG(D_ERROR, env, lock,
 831                                               "dlmlock returned %d\n", dlmrc);
 832                                 cl_lock_error(env, lock, dlmrc);
 833                         }
 834                         cl_lock_mutex_put(env, lock);
 835                         osc_ast_data_put(env, olck);
 836                         result = 0;
 837                 } else
 838                         result = -ELDLM_NO_LOCK_DATA;
 839                 cl_env_nested_put(&nest, env);
 840         } else
 841                 result = PTR_ERR(env);
 842         return dlmrc ?: result;
 843 }
 844
 845 static int osc_ldlm_glimpse_ast(struct ldlm_lock *dlmlock, void *data)
 846 {
 847         struct ptlrpc_request  *req  = data;
 848         struct osc_lock        *olck;
 849         struct cl_lock         *lock;
 850         struct cl_object       *obj;
 851         struct cl_env_nest      nest;
 852         struct lu_env          *env;
 853         struct ost_lvb         *lvb;
 854         struct req_capsule     *cap;
 855         int                     result;
 856
 857         LASSERT(lustre_msg_get_opc(req->rq_reqmsg) == LDLM_GL_CALLBACK);
 858
 859         env = cl_env_nested_get(&nest);
 860         if (!IS_ERR(env)) {
 861                 /* osc_ast_data_get() has to go after environment is
 862                  * allocated, because osc_ast_data() acquires a
 863                  * reference to a lock, and it can only be released in
 864                  * environment.
 865                  */
 866                 olck = osc_ast_data_get(dlmlock);
 867                 if (olck != NULL) {
 868                         lock = olck->ols_cl.cls_lock;
 869                         /* Do not grab the mutex of cl_lock for glimpse.
 870                          * See LU-1274 for details.
 871                          * BTW, it's okay for cl_lock to be cancelled during
 872                          * this period because server can handle this race.
 873                          * See ldlm_server_glimpse_ast() for details.
 874                          * cl_lock_mutex_get(env, lock); */
 875                         cap = &req->rq_pill;
 876                         req_capsule_extend(cap, &RQF_LDLM_GL_CALLBACK);
 877                         req_capsule_set_size(cap, &RMF_DLM_LVB, RCL_SERVER,
 878                                              sizeof *lvb);
 879                         result = req_capsule_server_pack(cap);
 880                         if (result == 0) {
 881                                 lvb = req_capsule_server_get(cap, &RMF_DLM_LVB);
 882                                 obj = lock->cll_descr.cld_obj;
 883                                 result = cl_object_glimpse(env, obj, lvb);
 884                         }
 885                         osc_ast_data_put(env, olck);
 886                 } else {
 887                         /*
 888                          * These errors are normal races, so we don't want to
 889                          * fill the console with messages by calling
 890                          * ptlrpc_error()
 891                          */
 892                         lustre_pack_reply(req, 1, NULL, NULL);
 893                         result = -ELDLM_NO_LOCK_DATA;
 894                 }
 895                 cl_env_nested_put(&nest, env);
 896         } else
 897                 result = PTR_ERR(env);
 898         req->rq_status = result;
 899         return result;
 900 }
 901
 902 static unsigned long osc_lock_weigh(const struct lu_env *env,
 903                                     const struct cl_lock_slice *slice)
 904 {
 905         /*
 906          * don't need to grab coh_page_guard since we don't care the exact #
 907          * of pages..
 908          */
 909         return cl_object_header(slice->cls_obj)->coh_pages;
 910 }
 911
 912 /**
 913  * Get the weight of dlm lock for early cancellation.
 914  *
 915  * XXX: it should return the pages covered by this \a dlmlock.
 916  */
 917 static unsigned long osc_ldlm_weigh_ast(struct ldlm_lock *dlmlock)
 918 {
 919         struct cl_env_nest       nest;
 920         struct lu_env           *env;
 921         struct osc_lock         *lock;
 922         struct cl_lock          *cll;
 923         unsigned long            weight;
 924         ENTRY;
 925
 926         cfs_might_sleep();
 927         /*
 928          * osc_ldlm_weigh_ast has a complex context since it might be called
 929          * because of lock canceling, or from user's input. We have to make
 930          * a new environment for it. Probably it is implementation safe to use
 931          * the upper context because cl_lock_put don't modify environment
 932          * variables. But in case of ..
 933          */
 934         env = cl_env_nested_get(&nest);
 935         if (IS_ERR(env))
 936                 /* Mostly because lack of memory, tend to eliminate this lock*/
 937                 RETURN(0);
 938
 939         LASSERT(dlmlock->l_resource->lr_type == LDLM_EXTENT);
 940         lock = osc_ast_data_get(dlmlock);
 941         if (lock == NULL) {
 942                 /* cl_lock was destroyed because of memory pressure.
 943                  * It is much reasonable to assign this type of lock
 944                  * a lower cost.
 945                  */
 946                 GOTO(out, weight = 0);
 947         }
 948
 949         cll = lock->ols_cl.cls_lock;
 950         cl_lock_mutex_get(env, cll);
 951         weight = cl_lock_weigh(env, cll);
 952         cl_lock_mutex_put(env, cll);
 953         osc_ast_data_put(env, lock);
 954         EXIT;
 955
 956 out:
 957         cl_env_nested_put(&nest, env);
 958         return weight;
 959 }
 960
 961 static void osc_lock_build_einfo(const struct lu_env *env,
 962                                  const struct cl_lock *clock,
 963                                  struct osc_lock *lock,
 964                                  struct ldlm_enqueue_info *einfo)
 965 {
 966         enum cl_lock_mode mode;
 967
 968         mode = clock->cll_descr.cld_mode;
 969         if (mode == CLM_PHANTOM)
 970                 /*
 971                  * For now, enqueue all glimpse locks in read mode. In the
 972                  * future, client might choose to enqueue LCK_PW lock for
 973                  * glimpse on a file opened for write.
 974                  */
 975                 mode = CLM_READ;
 976
 977         einfo->ei_type   = LDLM_EXTENT;
 978         einfo->ei_mode   = osc_cl_lock2ldlm(mode);
 979         einfo->ei_cb_bl  = osc_ldlm_blocking_ast;
 980         einfo->ei_cb_cp  = osc_ldlm_completion_ast;
 981         einfo->ei_cb_gl  = osc_ldlm_glimpse_ast;
 982         einfo->ei_cb_wg  = osc_ldlm_weigh_ast;
 983         einfo->ei_cbdata = lock; /* value to be put into ->l_ast_data */
 984 }
 985
 986 /**
 987  * Determine if the lock should be converted into a lockless lock.
 988  *
 989  * Steps to check:
 990  * - if the lock has an explicite requirment for a non-lockless lock;
 991  * - if the io lock request type ci_lockreq;
 992  * - send the enqueue rpc to ost to make the further decision;
 993  * - special treat to truncate lockless lock
 994  *
 995  *  Additional policy can be implemented here, e.g., never do lockless-io
 996  *  for large extents.
 997  */
 998 static void osc_lock_to_lockless(const struct lu_env *env,
 999                                  struct osc_lock *ols, int force)
1000 {
1001         struct cl_lock_slice *slice = &ols->ols_cl;
1002         struct cl_lock *lock        = slice->cls_lock;
1003
1004         LASSERT(ols->ols_state == OLS_NEW ||
1005                 ols->ols_state == OLS_UPCALL_RECEIVED);
1006
1007         if (force) {
1008                 ols->ols_locklessable = 1;
1009                 LASSERT(cl_lock_is_mutexed(lock));
1010                 slice->cls_ops = &osc_lock_lockless_ops;
1011         } else {
1012                 struct osc_io *oio     = osc_env_io(env);
1013                 struct cl_io  *io      = oio->oi_cl.cis_io;
1014                 struct cl_object *obj  = slice->cls_obj;
1015                 struct osc_object *oob = cl2osc(obj);
1016                 const struct osc_device *osd = lu2osc_dev(obj->co_lu.lo_dev);
1017                 struct obd_connect_data *ocd;
1018
1019                 LASSERT(io->ci_lockreq == CILR_MANDATORY ||
1020                         io->ci_lockreq == CILR_MAYBE ||
1021                         io->ci_lockreq == CILR_NEVER);
1022
1023                 ocd = &class_exp2cliimp(osc_export(oob))->imp_connect_data;
1024                 ols->ols_locklessable = (io->ci_type != CIT_SETATTR) &&
1025                                 (io->ci_lockreq == CILR_MAYBE) &&
1026                                 (ocd->ocd_connect_flags & OBD_CONNECT_SRVLOCK);
1027                 if (io->ci_lockreq == CILR_NEVER ||
1028                         /* lockless IO */
1029                     (ols->ols_locklessable && osc_object_is_contended(oob)) ||
1030                         /* lockless truncate */
1031                     (cl_io_is_trunc(io) &&
1032                      (ocd->ocd_connect_flags & OBD_CONNECT_TRUNCLOCK) &&
1033                       osd->od_lockless_truncate)) {
1034                         ols->ols_locklessable = 1;
1035                         slice->cls_ops = &osc_lock_lockless_ops;
1036                 }
1037         }
1038         LASSERT(ergo(ols->ols_glimpse, !osc_lock_is_lockless(ols)));
1039 }
1040
1041 static int osc_lock_compatible(const struct osc_lock *qing,
1042                                const struct osc_lock *qed)
1043 {
1044         enum cl_lock_mode qing_mode;
1045         enum cl_lock_mode qed_mode;
1046
1047         qing_mode = qing->ols_cl.cls_lock->cll_descr.cld_mode;
1048         if (qed->ols_glimpse &&
1049             (qed->ols_state >= OLS_UPCALL_RECEIVED || qing_mode == CLM_READ))
1050                 return 1;
1051
1052         qed_mode = qed->ols_cl.cls_lock->cll_descr.cld_mode;
1053         return ((qing_mode == CLM_READ) && (qed_mode == CLM_READ));
1054 }
1055
1056 /**
1057  * Cancel all conflicting locks and wait for them to be destroyed.
1058  *
1059  * This function is used for two purposes:
1060  *
1061  *     - early cancel all conflicting locks before starting IO, and
1062  *
1063  *     - guarantee that pages added to the page cache by lockless IO are never
1064  *       covered by locks other than lockless IO lock, and, hence, are not
1065  *       visible to other threads.
1066  */
1067 static int osc_lock_enqueue_wait(const struct lu_env *env,
1068                                  const struct osc_lock *olck)
1069 {
1070         struct cl_lock          *lock    = olck->ols_cl.cls_lock;
1071         struct cl_lock_descr    *descr   = &lock->cll_descr;
1072         struct cl_object_header *hdr     = cl_object_header(descr->cld_obj);
1073         struct cl_lock          *scan;
1074         struct cl_lock          *conflict= NULL;
1075         int lockless                     = osc_lock_is_lockless(olck);
1076         int rc                           = 0;
1077         ENTRY;
1078
1079         LASSERT(cl_lock_is_mutexed(lock));
1080
1081         /* make it enqueue anyway for glimpse lock, because we actually
1082          * don't need to cancel any conflicting locks. */
1083         if (olck->ols_glimpse)
1084                 return 0;
1085
1086         cfs_spin_lock(&hdr->coh_lock_guard);
1087         cfs_list_for_each_entry(scan, &hdr->coh_locks, cll_linkage) {
1088                 struct cl_lock_descr *cld = &scan->cll_descr;
1089                 const struct osc_lock *scan_ols;
1090
1091                 if (scan == lock)
1092                         break;
1093
1094                 if (scan->cll_state < CLS_QUEUING ||
1095                     scan->cll_state == CLS_FREEING ||
1096                     cld->cld_start > descr->cld_end ||
1097                     cld->cld_end < descr->cld_start)
1098                         continue;
1099
1100                 /* overlapped and living locks. */
1101
1102                 /* We're not supposed to give up group lock. */
1103                 if (scan->cll_descr.cld_mode == CLM_GROUP) {
1104                         LASSERT(descr->cld_mode != CLM_GROUP ||
1105                                 descr->cld_gid != scan->cll_descr.cld_gid);
1106                         continue;
1107                 }
1108
1109                 scan_ols = osc_lock_at(scan);
1110
1111                 /* We need to cancel the compatible locks if we're enqueuing
1112                  * a lockless lock, for example:
1113                  * imagine that client has PR lock on [0, 1000], and thread T0
1114                  * is doing lockless IO in [500, 1500] region. Concurrent
1115                  * thread T1 can see lockless data in [500, 1000], which is
1116                  * wrong, because these data are possibly stale. */
1117                 if (!lockless && osc_lock_compatible(olck, scan_ols))
1118                         continue;
1119
1120                 /* Now @scan is conflicting with @lock, this means current
1121                  * thread have to sleep for @scan being destroyed. */
1122                 if (scan_ols->ols_owner == osc_env_io(env)) {
1123                         CERROR("DEADLOCK POSSIBLE!\n");
1124                         CL_LOCK_DEBUG(D_ERROR, env, scan, "queued.\n");
1125                         CL_LOCK_DEBUG(D_ERROR, env, lock, "queuing.\n");
1126                         libcfs_debug_dumpstack(NULL);
1127                 }
1128                 cl_lock_get_trust(scan);
1129                 conflict = scan;
1130                 break;
1131         }
1132         cfs_spin_unlock(&hdr->coh_lock_guard);
1133
1134         if (conflict) {
1135                 if (lock->cll_descr.cld_mode == CLM_GROUP) {
1136                         /* we want a group lock but a previous lock request
1137                          * conflicts, we do not wait but return 0 so the
1138                          * request is send to the server
1139                          */
1140                         CDEBUG(D_DLMTRACE, "group lock %p is conflicted "
1141                                            "with %p, no wait, send to server\n",
1142                                lock, conflict);
1143                         cl_lock_put(env, conflict);
1144                         rc = 0;
1145                 } else {
1146                         CDEBUG(D_DLMTRACE, "lock %p is conflicted with %p, "
1147                                            "will wait\n",
1148                                lock, conflict);
1149                         LASSERT(lock->cll_conflict == NULL);
1150                         lu_ref_add(&conflict->cll_reference, "cancel-wait",
1151                                    lock);
1152                         lock->cll_conflict = conflict;
1153                         rc = CLO_WAIT;
1154                 }
1155         }
1156         RETURN(rc);
1157 }
1158
1159 /**
1160  * Implementation of cl_lock_operations::clo_enqueue() method for osc
1161  * layer. This initiates ldlm enqueue:
1162  *
1163  *     - cancels conflicting locks early (osc_lock_enqueue_wait());
1164  *
1165  *     - calls osc_enqueue_base() to do actual enqueue.
1166  *
1167  * osc_enqueue_base() is supplied with an upcall function that is executed
1168  * when lock is received either after a local cached ldlm lock is matched, or
1169  * when a reply from the server is received.
1170  *
1171  * This function does not wait for the network communication to complete.
1172  */
1173 static int osc_lock_enqueue(const struct lu_env *env,
1174                             const struct cl_lock_slice *slice,
1175                             struct cl_io *unused, __u32 enqflags)
1176 {
1177         struct osc_lock          *ols     = cl2osc_lock(slice);
1178         struct cl_lock           *lock    = ols->ols_cl.cls_lock;
1179         int result;
1180         ENTRY;
1181
1182         LASSERT(cl_lock_is_mutexed(lock));
1183         LASSERTF(ols->ols_state == OLS_NEW,
1184                  "Impossible state: %d\n", ols->ols_state);
1185
1186         ols->ols_flags = osc_enq2ldlm_flags(enqflags);
1187         if (enqflags & CEF_AGL) {
1188                 ols->ols_flags |= LDLM_FL_BLOCK_NOWAIT;
1189                 ols->ols_agl = 1;
1190         }
1191         if (ols->ols_flags & LDLM_FL_HAS_INTENT)
1192                 ols->ols_glimpse = 1;
1193         if (!osc_lock_is_lockless(ols) && !(enqflags & CEF_MUST))
1194                 /* try to convert this lock to a lockless lock */
1195                 osc_lock_to_lockless(env, ols, (enqflags & CEF_NEVER));
1196
1197         result = osc_lock_enqueue_wait(env, ols);
1198         if (result == 0) {
1199                 if (!osc_lock_is_lockless(ols)) {
1200                         struct osc_object        *obj = cl2osc(slice->cls_obj);
1201                         struct osc_thread_info   *info = osc_env_info(env);
1202                         struct ldlm_res_id       *resname = &info->oti_resname;
1203                         ldlm_policy_data_t       *policy = &info->oti_policy;
1204                         struct ldlm_enqueue_info *einfo = &ols->ols_einfo;
1205
1206                         if (ols->ols_locklessable)
1207                                 ols->ols_flags |= LDLM_FL_DENY_ON_CONTENTION;
1208
1209                         /* a reference for lock, passed as an upcall cookie */
1210                         cl_lock_get(lock);
1211                         lu_ref_add(&lock->cll_reference, "upcall", lock);
1212                         /* a user for lock also */
1213                         cl_lock_user_add(env, lock);
1214                         ols->ols_state = OLS_ENQUEUED;
1215
1216                         /*
1217                          * XXX: this is possible blocking point as
1218                          * ldlm_lock_match(LDLM_FL_LVB_READY) waits for
1219                          * LDLM_CP_CALLBACK.
1220                          */
1221                         osc_lock_build_res(env, obj, resname);
1222                         osc_lock_build_policy(env, lock, policy);
1223                         result = osc_enqueue_base(osc_export(obj), resname,
1224                                           &ols->ols_flags, policy,
1225                                           &ols->ols_lvb,
1226                                           obj->oo_oinfo->loi_kms_valid,
1227                                           osc_lock_upcall,
1228                                           ols, einfo, &ols->ols_handle,
1229                                           PTLRPCD_SET, 1, ols->ols_agl);
1230                         if (result != 0) {
1231                                 cl_lock_user_del(env, lock);
1232                                 lu_ref_del(&lock->cll_reference,
1233                                            "upcall", lock);
1234                                 cl_lock_put(env, lock);
1235                                 if (unlikely(result == -ECANCELED)) {
1236                                         ols->ols_state = OLS_NEW;
1237                                         result = 0;
1238                                 }
1239                         }
1240                 } else {
1241                         ols->ols_state = OLS_GRANTED;
1242                         ols->ols_owner = osc_env_io(env);
1243                 }
1244         }
1245         LASSERT(ergo(ols->ols_glimpse, !osc_lock_is_lockless(ols)));
1246         RETURN(result);
1247 }
1248
1249 static int osc_lock_wait(const struct lu_env *env,
1250                          const struct cl_lock_slice *slice)
1251 {
1252         struct osc_lock *olck = cl2osc_lock(slice);
1253         struct cl_lock  *lock = olck->ols_cl.cls_lock;
1254
1255         LINVRNT(osc_lock_invariant(olck));
1256
1257         if (olck->ols_glimpse && olck->ols_state >= OLS_UPCALL_RECEIVED) {
1258                 if (olck->ols_flags & LDLM_FL_LVB_READY) {
1259                         return 0;
1260                 } else if (olck->ols_agl) {
1261                         if (lock->cll_flags & CLF_FROM_UPCALL)
1262                                 /* It is from enqueue RPC reply upcall for
1263                                  * updating state. Do not re-enqueue. */
1264                                 return -ENAVAIL;
1265                         else
1266                                 olck->ols_state = OLS_NEW;
1267                 } else {
1268                         LASSERT(lock->cll_error);
1269                         return lock->cll_error;
1270                 }
1271         }
1272
1273         if (olck->ols_state == OLS_NEW) {
1274                 int rc;
1275
1276                 LASSERT(olck->ols_agl);
1277
1278                 rc = osc_lock_enqueue(env, slice, NULL, CEF_ASYNC | CEF_MUST);
1279                 if (rc != 0)
1280                         return rc;
1281                 else
1282                         return CLO_REENQUEUED;
1283         }
1284
1285         LASSERT(equi(olck->ols_state >= OLS_UPCALL_RECEIVED &&
1286                      lock->cll_error == 0, olck->ols_lock != NULL));
1287
1288         return lock->cll_error ?: olck->ols_state >= OLS_GRANTED ? 0 : CLO_WAIT;
1289 }
1290
1291 /**
1292  * An implementation of cl_lock_operations::clo_use() method that pins cached
1293  * lock.
1294  */
1295 static int osc_lock_use(const struct lu_env *env,
1296                         const struct cl_lock_slice *slice)
1297 {
1298         struct osc_lock *olck = cl2osc_lock(slice);
1299         int rc;
1300
1301         LASSERT(!olck->ols_hold);
1302
1303         /*
1304          * Atomically check for LDLM_FL_CBPENDING and addref a lock if this
1305          * flag is not set. This protects us from a concurrent blocking ast.
1306          */
1307         rc = ldlm_lock_addref_try(&olck->ols_handle, olck->ols_einfo.ei_mode);
1308         if (rc == 0) {
1309                 olck->ols_hold = 1;
1310                 olck->ols_state = OLS_GRANTED;
1311         } else {
1312                 struct cl_lock *lock;
1313
1314                 /*
1315                  * Lock is being cancelled somewhere within
1316                  * ldlm_handle_bl_callback(): LDLM_FL_CBPENDING is already
1317                  * set, but osc_ldlm_blocking_ast() hasn't yet acquired
1318                  * cl_lock mutex.
1319                  */
1320                 lock = slice->cls_lock;
1321                 LASSERT(lock->cll_state == CLS_INTRANSIT);
1322                 LASSERT(lock->cll_users > 0);
1323                 /* set a flag for osc_dlm_blocking_ast0() to signal the
1324                  * lock.*/
1325                 olck->ols_ast_wait = 1;
1326                 rc = CLO_WAIT;
1327         }
1328         return rc;
1329 }
1330
1331 static int osc_lock_flush(struct osc_lock *ols, int discard)
1332 {
1333         struct cl_lock       *lock  = ols->ols_cl.cls_lock;
1334         struct cl_env_nest    nest;
1335         struct lu_env        *env;
1336         int result = 0;
1337         ENTRY;
1338
1339         env = cl_env_nested_get(&nest);
1340         if (!IS_ERR(env)) {
1341                 struct osc_object    *obj   = cl2osc(ols->ols_cl.cls_obj);
1342                 struct cl_lock_descr *descr = &lock->cll_descr;
1343                 int rc = 0;
1344
1345                 if (descr->cld_mode >= CLM_WRITE) {
1346                         result = osc_cache_writeback_range(env, obj,
1347                                         descr->cld_start, descr->cld_end,
1348                                         1, discard);
1349                         CDEBUG(D_DLMTRACE, "write out %d pages for lock %p.\n",
1350                                result, lock);
1351                         if (result > 0)
1352                                 result = 0;
1353                 }
1354
1355                 rc = cl_lock_discard_pages(env, lock);
1356                 if (result == 0 && rc < 0)
1357                         result = rc;
1358
1359                 cl_env_nested_put(&nest, env);
1360         } else
1361                 result = PTR_ERR(env);
1362         if (result == 0) {
1363                 ols->ols_flush = 1;
1364                 LINVRNT(!osc_lock_has_pages(ols));
1365         }
1366         RETURN(result);
1367 }
1368
1369 /**
1370  * Implements cl_lock_operations::clo_cancel() method for osc layer. This is
1371  * called (as part of cl_lock_cancel()) when lock is canceled either voluntary
1372  * (LRU pressure, early cancellation, umount, etc.) or due to the conflict
1373  * with some other lock some where in the cluster. This function does the
1374  * following:
1375  *
1376  *     - invalidates all pages protected by this lock (after sending dirty
1377  *       ones to the server, as necessary);
1378  *
1379  *     - decref's underlying ldlm lock;
1380  *
1381  *     - cancels ldlm lock (ldlm_cli_cancel()).
1382  */
1383 static void osc_lock_cancel(const struct lu_env *env,
1384                             const struct cl_lock_slice *slice)
1385 {
1386         struct cl_lock   *lock    = slice->cls_lock;
1387         struct osc_lock  *olck    = cl2osc_lock(slice);
1388         struct ldlm_lock *dlmlock = olck->ols_lock;
1389         int               result  = 0;
1390         int               discard;
1391
1392         LASSERT(cl_lock_is_mutexed(lock));
1393         LINVRNT(osc_lock_invariant(olck));
1394
1395         if (dlmlock != NULL) {
1396                 int do_cancel;
1397
1398                 discard = !!(dlmlock->l_flags & LDLM_FL_DISCARD_DATA);
1399                 result = osc_lock_flush(olck, discard);
1400                 osc_lock_unhold(olck);
1401
1402                 lock_res_and_lock(dlmlock);
1403                 /* Now that we're the only user of dlm read/write reference,
1404                  * mostly the ->l_readers + ->l_writers should be zero.
1405                  * However, there is a corner case.
1406                  * See bug 18829 for details.*/
1407                 do_cancel = (dlmlock->l_readers == 0 &&
1408                              dlmlock->l_writers == 0);
1409                 dlmlock->l_flags |= LDLM_FL_CBPENDING;
1410                 unlock_res_and_lock(dlmlock);
1411                 if (do_cancel)
1412                         result = ldlm_cli_cancel(&olck->ols_handle);
1413                 if (result < 0)
1414                         CL_LOCK_DEBUG(D_ERROR, env, lock,
1415                                       "lock %p cancel failure with error(%d)\n",
1416                                       lock, result);
1417         }
1418         olck->ols_state = OLS_CANCELLED;
1419         olck->ols_flags &= ~LDLM_FL_LVB_READY;
1420         osc_lock_detach(env, olck);
1421 }
1422
1423 #ifdef INVARIANT_CHECK
1424 static int check_cb(const struct lu_env *env, struct cl_io *io,
1425                     struct cl_page *page, void *cbdata)
1426 {
1427         struct cl_lock *lock = cbdata;
1428
1429         if (lock->cll_descr.cld_mode == CLM_READ) {
1430                 struct cl_lock *tmp;
1431                 tmp = cl_lock_at_page(env, lock->cll_descr.cld_obj,
1432                                      page, lock, 1, 0);
1433                 if (tmp != NULL) {
1434                         cl_lock_put(env, tmp);
1435                         return CLP_GANG_OKAY;
1436                 }
1437         }
1438
1439         CL_LOCK_DEBUG(D_ERROR, env, lock, "still has pages\n");
1440         CL_PAGE_DEBUG(D_ERROR, env, page, "\n");
1441         return CLP_GANG_ABORT;
1442 }
1443
1444 /**
1445  * Returns true iff there are pages under \a olck not protected by other
1446  * locks.
1447  */
1448 static int osc_lock_has_pages(struct osc_lock *olck)
1449 {
1450         struct cl_lock       *lock;
1451         struct cl_lock_descr *descr;
1452         struct cl_object     *obj;
1453         struct osc_object    *oob;
1454         struct cl_env_nest    nest;
1455         struct cl_io         *io;
1456         struct lu_env        *env;
1457         int                   result;
1458
1459         env = cl_env_nested_get(&nest);
1460         if (IS_ERR(env))
1461                 return 0;
1462
1463         obj   = olck->ols_cl.cls_obj;
1464         oob   = cl2osc(obj);
1465         io    = &oob->oo_debug_io;
1466         lock  = olck->ols_cl.cls_lock;
1467         descr = &lock->cll_descr;
1468
1469         cfs_mutex_lock(&oob->oo_debug_mutex);
1470
1471         io->ci_obj = cl_object_top(obj);
1472         io->ci_ignore_layout = 1;
1473         cl_io_init(env, io, CIT_MISC, io->ci_obj);
1474         do {
1475                 result = cl_page_gang_lookup(env, obj, io,
1476                                              descr->cld_start, descr->cld_end,
1477                                              check_cb, (void *)lock);
1478                 if (result == CLP_GANG_ABORT)
1479                         break;
1480                 if (result == CLP_GANG_RESCHED)
1481                         cfs_cond_resched();
1482         } while (result != CLP_GANG_OKAY);
1483         cl_io_fini(env, io);
1484         cfs_mutex_unlock(&oob->oo_debug_mutex);
1485         cl_env_nested_put(&nest, env);
1486
1487         return (result == CLP_GANG_ABORT);
1488 }
1489 #else
1490 static int osc_lock_has_pages(struct osc_lock *olck)
1491 {
1492         return 0;
1493 }
1494 #endif /* INVARIANT_CHECK */
1495
1496 static void osc_lock_delete(const struct lu_env *env,
1497                             const struct cl_lock_slice *slice)
1498 {
1499         struct osc_lock *olck;
1500
1501         olck = cl2osc_lock(slice);
1502         if (olck->ols_glimpse) {
1503                 LASSERT(!olck->ols_hold);
1504                 LASSERT(!olck->ols_lock);
1505                 return;
1506         }
1507
1508         LINVRNT(osc_lock_invariant(olck));
1509         LINVRNT(!osc_lock_has_pages(olck));
1510
1511         osc_lock_unhold(olck);
1512         osc_lock_detach(env, olck);
1513 }
1514
1515 /**
1516  * Implements cl_lock_operations::clo_state() method for osc layer.
1517  *
1518  * Maintains osc_lock::ols_owner field.
1519  *
1520  * This assumes that lock always enters CLS_HELD (from some other state) in
1521  * the same IO context as one that requested the lock. This should not be a
1522  * problem, because context is by definition shared by all activity pertaining
1523  * to the same high-level IO.
1524  */
1525 static void osc_lock_state(const struct lu_env *env,
1526                            const struct cl_lock_slice *slice,
1527                            enum cl_lock_state state)
1528 {
1529         struct osc_lock *lock = cl2osc_lock(slice);
1530
1531         /*
1532          * XXX multiple io contexts can use the lock at the same time.
1533          */
1534         LINVRNT(osc_lock_invariant(lock));
1535         if (state == CLS_HELD && slice->cls_lock->cll_state != CLS_HELD) {
1536                 struct osc_io *oio = osc_env_io(env);
1537
1538                 LASSERT(lock->ols_owner == NULL);
1539                 lock->ols_owner = oio;
1540         } else if (state != CLS_HELD)
1541                 lock->ols_owner = NULL;
1542 }
1543
1544 static int osc_lock_print(const struct lu_env *env, void *cookie,
1545                           lu_printer_t p, const struct cl_lock_slice *slice)
1546 {
1547         struct osc_lock *lock = cl2osc_lock(slice);
1548
1549         /*
1550          * XXX print ldlm lock and einfo properly.
1551          */
1552         (*p)(env, cookie, "%p %08x "LPX64" %d %p ",
1553              lock->ols_lock, lock->ols_flags, lock->ols_handle.cookie,
1554              lock->ols_state, lock->ols_owner);
1555         osc_lvb_print(env, cookie, p, &lock->ols_lvb);
1556         return 0;
1557 }
1558
1559 static int osc_lock_fits_into(const struct lu_env *env,
1560                               const struct cl_lock_slice *slice,
1561                               const struct cl_lock_descr *need,
1562                               const struct cl_io *io)
1563 {
1564         struct osc_lock *ols = cl2osc_lock(slice);
1565
1566         if (need->cld_enq_flags & CEF_NEVER)
1567                 return 0;
1568
1569         if (ols->ols_state >= OLS_CANCELLED)
1570                 return 0;
1571
1572         if (need->cld_mode == CLM_PHANTOM) {
1573                 if (ols->ols_agl)
1574                         return !(ols->ols_state > OLS_RELEASED);
1575
1576                 /*
1577                  * Note: the QUEUED lock can't be matched here, otherwise
1578                  * it might cause the deadlocks.
1579                  * In read_process,
1580                  * P1: enqueued read lock, create sublock1
1581                  * P2: enqueued write lock, create sublock2(conflicted
1582                  *     with sublock1).
1583                  * P1: Grant read lock.
1584                  * P1: enqueued glimpse lock(with holding sublock1_read),
1585                  *     matched with sublock2, waiting sublock2 to be granted.
1586                  *     But sublock2 can not be granted, because P1
1587                  *     will not release sublock1. Bang!
1588                  */
1589                 if (ols->ols_state < OLS_GRANTED ||
1590                     ols->ols_state > OLS_RELEASED)
1591                         return 0;
1592         } else if (need->cld_enq_flags & CEF_MUST) {
1593                 /*
1594                  * If the lock hasn't ever enqueued, it can't be matched
1595                  * because enqueue process brings in many information
1596                  * which can be used to determine things such as lockless,
1597                  * CEF_MUST, etc.
1598                  */
1599                 if (ols->ols_state < OLS_UPCALL_RECEIVED &&
1600                     ols->ols_locklessable)
1601                         return 0;
1602         }
1603         return 1;
1604 }
1605
1606 static const struct cl_lock_operations osc_lock_ops = {
1607         .clo_fini    = osc_lock_fini,
1608         .clo_enqueue = osc_lock_enqueue,
1609         .clo_wait    = osc_lock_wait,
1610         .clo_unuse   = osc_lock_unuse,
1611         .clo_use     = osc_lock_use,
1612         .clo_delete  = osc_lock_delete,
1613         .clo_state   = osc_lock_state,
1614         .clo_cancel  = osc_lock_cancel,
1615         .clo_weigh   = osc_lock_weigh,
1616         .clo_print   = osc_lock_print,
1617         .clo_fits_into = osc_lock_fits_into,
1618 };
1619
1620 static int osc_lock_lockless_unuse(const struct lu_env *env,
1621                                    const struct cl_lock_slice *slice)
1622 {
1623         struct osc_lock *ols = cl2osc_lock(slice);
1624         struct cl_lock *lock = slice->cls_lock;
1625
1626         LASSERT(ols->ols_state == OLS_GRANTED);
1627         LINVRNT(osc_lock_invariant(ols));
1628
1629         cl_lock_cancel(env, lock);
1630         cl_lock_delete(env, lock);
1631         return 0;
1632 }
1633
1634 static void osc_lock_lockless_cancel(const struct lu_env *env,
1635                                      const struct cl_lock_slice *slice)
1636 {
1637         struct osc_lock   *ols  = cl2osc_lock(slice);
1638         int result;
1639
1640         result = osc_lock_flush(ols, 0);
1641         if (result)
1642                 CERROR("Pages for lockless lock %p were not purged(%d)\n",
1643                        ols, result);
1644         ols->ols_state = OLS_CANCELLED;
1645 }
1646
1647 static int osc_lock_lockless_wait(const struct lu_env *env,
1648                                   const struct cl_lock_slice *slice)
1649 {
1650         struct osc_lock *olck = cl2osc_lock(slice);
1651         struct cl_lock  *lock = olck->ols_cl.cls_lock;
1652
1653         LINVRNT(osc_lock_invariant(olck));
1654         LASSERT(olck->ols_state >= OLS_UPCALL_RECEIVED);
1655
1656         return lock->cll_error;
1657 }
1658
1659 static void osc_lock_lockless_state(const struct lu_env *env,
1660                                     const struct cl_lock_slice *slice,
1661                                     enum cl_lock_state state)
1662 {
1663         struct osc_lock *lock = cl2osc_lock(slice);
1664
1665         LINVRNT(osc_lock_invariant(lock));
1666         if (state == CLS_HELD) {
1667                 struct osc_io *oio  = osc_env_io(env);
1668
1669                 LASSERT(ergo(lock->ols_owner, lock->ols_owner == oio));
1670                 lock->ols_owner = oio;
1671
1672                 /* set the io to be lockless if this lock is for io's
1673                  * host object */
1674                 if (cl_object_same(oio->oi_cl.cis_obj, slice->cls_obj))
1675                         oio->oi_lockless = 1;
1676         }
1677 }
1678
1679 static int osc_lock_lockless_fits_into(const struct lu_env *env,
1680                                        const struct cl_lock_slice *slice,
1681                                        const struct cl_lock_descr *need,
1682                                        const struct cl_io *io)
1683 {
1684         struct osc_lock *lock = cl2osc_lock(slice);
1685
1686         if (!(need->cld_enq_flags & CEF_NEVER))
1687                 return 0;
1688
1689         /* lockless lock should only be used by its owning io. b22147 */
1690         return (lock->ols_owner == osc_env_io(env));
1691 }
1692
1693 static const struct cl_lock_operations osc_lock_lockless_ops = {
1694         .clo_fini      = osc_lock_fini,
1695         .clo_enqueue   = osc_lock_enqueue,
1696         .clo_wait      = osc_lock_lockless_wait,
1697         .clo_unuse     = osc_lock_lockless_unuse,
1698         .clo_state     = osc_lock_lockless_state,
1699         .clo_fits_into = osc_lock_lockless_fits_into,
1700         .clo_cancel    = osc_lock_lockless_cancel,
1701         .clo_print     = osc_lock_print
1702 };
1703
1704 int osc_lock_init(const struct lu_env *env,
1705                   struct cl_object *obj, struct cl_lock *lock,
1706                   const struct cl_io *unused)
1707 {
1708         struct osc_lock *clk;
1709         int result;
1710
1711         OBD_SLAB_ALLOC_PTR_GFP(clk, osc_lock_kmem, CFS_ALLOC_IO);
1712         if (clk != NULL) {
1713                 osc_lock_build_einfo(env, lock, clk, &clk->ols_einfo);
1714                 cfs_atomic_set(&clk->ols_pageref, 0);
1715                 clk->ols_state = OLS_NEW;
1716                 cl_lock_slice_add(lock, &clk->ols_cl, obj, &osc_lock_ops);
1717                 result = 0;
1718         } else
1719                 result = -ENOMEM;
1720         return result;
1721 }
1722
1723 int osc_dlm_lock_pageref(struct ldlm_lock *dlm)
1724 {
1725         struct osc_lock *olock;
1726         int              rc = 0;
1727
1728         cfs_spin_lock(&osc_ast_guard);
1729         olock = dlm->l_ast_data;
1730         /*
1731          * there's a very rare race with osc_page_addref_lock(), but that
1732          * doesn't matter because in the worst case we don't cancel a lock
1733          * which we actually can, that's no harm.
1734          */
1735         if (olock != NULL &&
1736             cfs_atomic_add_return(_PAGEREF_MAGIC,
1737                                   &olock->ols_pageref) != _PAGEREF_MAGIC) {
1738                 cfs_atomic_sub(_PAGEREF_MAGIC, &olock->ols_pageref);
1739                 rc = 1;
1740         }
1741         cfs_spin_unlock(&osc_ast_guard);
1742         return rc;
1743 }
1744
1745 /** @} osc */