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, 2013, Intel Corporation.
  31  */
  32 /*
  33  * This file is part of Lustre, http://www.lustre.org/
  34  * Lustre is a trademark of Sun Microsystems, Inc.
  35  *
  36  * Implementation of cl_lock for OSC layer.
  37  *
  38  *   Author: Nikita Danilov <nikita.danilov@sun.com>
  39  *   Author: Jinshan Xiong <jinshan.xiong@intel.com>
  40  */
  41
  42 #define DEBUG_SUBSYSTEM S_OSC
  43
  44 #ifdef __KERNEL__
  45 # include <libcfs/libcfs.h>
  46 #else
  47 # include <liblustre.h>
  48 #endif
  49 /* fid_build_reg_res_name() */
  50 #include <lustre_fid.h>
  51
  52 #include "osc_cl_internal.h"
  53
  54 /** \addtogroup osc
  55  *  @{
  56  */
  57
  58 /*****************************************************************************
  59  *
  60  * Type conversions.
  61  *
  62  */
  63
  64 static const struct cl_lock_operations osc_lock_ops;
  65 static const struct cl_lock_operations osc_lock_lockless_ops;
  66 static void osc_lock_to_lockless(const struct lu_env *env,
  67                                  struct osc_lock *ols, int force);
  68 static bool osc_lock_has_pages(struct osc_lock *olck);
  69
  70 int osc_lock_is_lockless(const struct osc_lock *olck)
  71 {
  72         return (olck->ols_cl.cls_ops == &osc_lock_lockless_ops);
  73 }
  74
  75 /**
  76  * Returns a weak pointer to the ldlm lock identified by a handle. Returned
  77  * pointer cannot be dereferenced, as lock is not protected from concurrent
  78  * reclaim. This function is a helper for osc_lock_invariant().
  79  */
  80 static struct ldlm_lock *osc_handle_ptr(struct lustre_handle *handle)
  81 {
  82         struct ldlm_lock *lock;
  83
  84         lock = ldlm_handle2lock(handle);
  85         if (lock != NULL)
  86                 LDLM_LOCK_PUT(lock);
  87         return lock;
  88 }
  89
  90 /**
  91  * Invariant that has to be true all of the time.
  92  */
  93 static int osc_lock_invariant(struct osc_lock *ols)
  94 {
  95         struct ldlm_lock *lock        = osc_handle_ptr(&ols->ols_handle);
  96         struct ldlm_lock *olock       = ols->ols_lock;
  97         int               handle_used = lustre_handle_is_used(&ols->ols_handle);
  98
  99         if (ergo(osc_lock_is_lockless(ols),
 100                  ols->ols_locklessable && ols->ols_lock == NULL))
 101                 return 1;
 102
 103         /*
 104          * If all the following "ergo"s are true, return 1, otherwise 0
 105          */
 106         if (! ergo(olock != NULL, handle_used))
 107                 return 0;
 108
 109         if (! ergo(olock != NULL,
 110                    olock->l_handle.h_cookie == ols->ols_handle.cookie))
 111                 return 0;
 112
 113         if (! ergo(handle_used,
 114                    ergo(lock != NULL && olock != NULL, lock == olock) &&
 115                    ergo(lock == NULL, olock == NULL)))
 116                 return 0;
 117         /*
 118          * Check that ->ols_handle and ->ols_lock are consistent, but
 119          * take into account that they are set at the different time.
 120          */
 121         if (! ergo(ols->ols_state == OLS_CANCELLED,
 122                    olock == NULL && !handle_used))
 123                 return 0;
 124         /*
 125          * DLM lock is destroyed only after we have seen cancellation
 126          * ast.
 127          */
 128         if (! ergo(olock != NULL && ols->ols_state < OLS_CANCELLED,
 129                    !ldlm_is_destroyed(olock)))
 130                 return 0;
 131
 132         if (! ergo(ols->ols_state == OLS_GRANTED,
 133                    olock != NULL &&
 134                    olock->l_req_mode == olock->l_granted_mode &&
 135                    ols->ols_hold))
 136                 return 0;
 137         return 1;
 138 }
 139
 140 /*****************************************************************************
 141  *
 142  * Lock operations.
 143  *
 144  */
 145
 146 /**
 147  * Breaks a link between osc_lock and dlm_lock.
 148  */
 149 static void osc_lock_detach(const struct lu_env *env, struct osc_lock *olck)
 150 {
 151         struct ldlm_lock *dlmlock;
 152
 153         spin_lock(&osc_ast_guard);
 154         dlmlock = olck->ols_lock;
 155         if (dlmlock == NULL) {
 156                 spin_unlock(&osc_ast_guard);
 157                 return;
 158         }
 159
 160         olck->ols_lock = NULL;
 161         /* wb(); --- for all who checks (ols->ols_lock != NULL) before
 162          * call to osc_lock_detach() */
 163         dlmlock->l_ast_data = NULL;
 164         olck->ols_handle.cookie = 0ULL;
 165         spin_unlock(&osc_ast_guard);
 166
 167         lock_res_and_lock(dlmlock);
 168         if (dlmlock->l_granted_mode == dlmlock->l_req_mode) {
 169                 struct cl_object *obj = olck->ols_cl.cls_obj;
 170                 struct cl_attr *attr  = &osc_env_info(env)->oti_attr;
 171                 __u64 old_kms;
 172
 173                 cl_object_attr_lock(obj);
 174                 /* Must get the value under the lock to avoid possible races. */
 175                 old_kms = cl2osc(obj)->oo_oinfo->loi_kms;
 176                 /* Update the kms. Need to loop all granted locks.
 177                  * Not a problem for the client */
 178                 attr->cat_kms = ldlm_extent_shift_kms(dlmlock, old_kms);
 179
 180                 cl_object_attr_set(env, obj, attr, CAT_KMS);
 181                 cl_object_attr_unlock(obj);
 182         }
 183         unlock_res_and_lock(dlmlock);
 184
 185         /* release a reference taken in osc_lock_upcall0(). */
 186         LASSERT(olck->ols_has_ref);
 187         lu_ref_del(&dlmlock->l_reference, "osc_lock", olck);
 188         LDLM_LOCK_RELEASE(dlmlock);
 189         olck->ols_has_ref = 0;
 190 }
 191
 192 static int osc_lock_unhold(struct osc_lock *ols)
 193 {
 194         int result = 0;
 195
 196         if (ols->ols_hold) {
 197                 ols->ols_hold = 0;
 198                 result = osc_cancel_base(&ols->ols_handle,
 199                                          ols->ols_einfo.ei_mode);
 200         }
 201         return result;
 202 }
 203
 204 static int osc_lock_unuse(const struct lu_env *env,
 205                           const struct cl_lock_slice *slice)
 206 {
 207         struct osc_lock *ols = cl2osc_lock(slice);
 208
 209         LINVRNT(osc_lock_invariant(ols));
 210
 211         switch (ols->ols_state) {
 212         case OLS_NEW:
 213                 LASSERT(!ols->ols_hold);
 214                 LASSERT(ols->ols_agl);
 215                 return 0;
 216         case OLS_UPCALL_RECEIVED:
 217                 osc_lock_unhold(ols);
 218         case OLS_ENQUEUED:
 219                 LASSERT(!ols->ols_hold);
 220                 osc_lock_detach(env, ols);
 221                 ols->ols_state = OLS_NEW;
 222                 return 0;
 223         case OLS_GRANTED:
 224                 LASSERT(!ols->ols_glimpse);
 225                 LASSERT(ols->ols_hold);
 226                 /*
 227                  * Move lock into OLS_RELEASED state before calling
 228                  * osc_cancel_base() so that possible synchronous cancellation
 229                  * (that always happens e.g., for liblustre) sees that lock is
 230                  * released.
 231                  */
 232                 ols->ols_state = OLS_RELEASED;
 233                 return osc_lock_unhold(ols);
 234         default:
 235                 CERROR("Impossible state: %d\n", ols->ols_state);
 236                 LBUG();
 237         }
 238 }
 239
 240 static void osc_lock_fini(const struct lu_env *env,
 241                           struct cl_lock_slice *slice)
 242 {
 243         struct osc_lock  *ols = cl2osc_lock(slice);
 244
 245         LINVRNT(osc_lock_invariant(ols));
 246         /*
 247          * ->ols_hold can still be true at this point if, for example, a
 248          * thread that requested a lock was killed (and released a reference
 249          * to the lock), before reply from a server was received. In this case
 250          * lock is destroyed immediately after upcall.
 251          */
 252         osc_lock_unhold(ols);
 253         LASSERT(ols->ols_lock == NULL);
 254         OBD_SLAB_FREE_PTR(ols, osc_lock_kmem);
 255 }
 256
 257 static void osc_lock_build_policy(const struct lu_env *env,
 258                                   const struct cl_lock *lock,
 259                                   ldlm_policy_data_t *policy)
 260 {
 261         const struct cl_lock_descr *d = &lock->cll_descr;
 262
 263         osc_index2policy(policy, d->cld_obj, d->cld_start, d->cld_end);
 264         policy->l_extent.gid = d->cld_gid;
 265 }
 266
 267 static __u64 osc_enq2ldlm_flags(__u32 enqflags)
 268 {
 269         __u64 result = 0;
 270
 271         LASSERT((enqflags & ~CEF_MASK) == 0);
 272
 273         if (enqflags & CEF_NONBLOCK)
 274                 result |= LDLM_FL_BLOCK_NOWAIT;
 275         if (enqflags & CEF_ASYNC)
 276                 result |= LDLM_FL_HAS_INTENT;
 277         if (enqflags & CEF_DISCARD_DATA)
 278                 result |= LDLM_FL_AST_DISCARD_DATA;
 279         return result;
 280 }
 281
 282 /**
 283  * Global spin-lock protecting consistency of ldlm_lock::l_ast_data
 284  * pointers. Initialized in osc_init().
 285  */
 286 spinlock_t osc_ast_guard;
 287
 288 static struct osc_lock *osc_ast_data_get(struct ldlm_lock *dlm_lock)
 289 {
 290         struct osc_lock *olck;
 291
 292         lock_res_and_lock(dlm_lock);
 293         spin_lock(&osc_ast_guard);
 294         olck = dlm_lock->l_ast_data;
 295         if (olck != NULL) {
 296                 struct cl_lock *lock = olck->ols_cl.cls_lock;
 297                 /*
 298                  * If osc_lock holds a reference on ldlm lock, return it even
 299                  * when cl_lock is in CLS_FREEING state. This way
 300                  *
 301                  *         osc_ast_data_get(dlmlock) == NULL
 302                  *
 303                  * guarantees that all osc references on dlmlock were
 304                  * released. osc_dlm_blocking_ast0() relies on that.
 305                  */
 306                 if (lock->cll_state < CLS_FREEING || olck->ols_has_ref) {
 307                         cl_lock_get_trust(lock);
 308                         lu_ref_add_atomic(&lock->cll_reference,
 309                                           "ast", current);
 310                 } else
 311                         olck = NULL;
 312         }
 313         spin_unlock(&osc_ast_guard);
 314         unlock_res_and_lock(dlm_lock);
 315         return olck;
 316 }
 317
 318 static void osc_ast_data_put(const struct lu_env *env, struct osc_lock *olck)
 319 {
 320         struct cl_lock *lock;
 321
 322         lock = olck->ols_cl.cls_lock;
 323         lu_ref_del(&lock->cll_reference, "ast", current);
 324         cl_lock_put(env, lock);
 325 }
 326
 327 /**
 328  * Updates object attributes from a lock value block (lvb) received together
 329  * with the DLM lock reply from the server. Copy of osc_update_enqueue()
 330  * logic.
 331  *
 332  * This can be optimized to not update attributes when lock is a result of a
 333  * local match.
 334  *
 335  * Called under lock and resource spin-locks.
 336  */
 337 static void osc_lock_lvb_update(const struct lu_env *env, struct osc_lock *olck,
 338                                 int rc)
 339 {
 340         struct ost_lvb    *lvb;
 341         struct cl_object  *obj;
 342         struct lov_oinfo  *oinfo;
 343         struct cl_attr    *attr;
 344         unsigned           valid;
 345
 346         ENTRY;
 347
 348         if (!(olck->ols_flags & LDLM_FL_LVB_READY))
 349                 RETURN_EXIT;
 350
 351         lvb   = &olck->ols_lvb;
 352         obj   = olck->ols_cl.cls_obj;
 353         oinfo = cl2osc(obj)->oo_oinfo;
 354         attr  = &osc_env_info(env)->oti_attr;
 355         valid = CAT_BLOCKS | CAT_ATIME | CAT_CTIME | CAT_MTIME | CAT_SIZE;
 356         cl_lvb2attr(attr, lvb);
 357
 358         cl_object_attr_lock(obj);
 359         if (rc == 0) {
 360                 struct ldlm_lock  *dlmlock;
 361                 __u64 size;
 362
 363                 dlmlock = olck->ols_lock;
 364                 LASSERT(dlmlock != NULL);
 365
 366                 /* re-grab LVB from a dlm lock under DLM spin-locks. */
 367                 *lvb = *(struct ost_lvb *)dlmlock->l_lvb_data;
 368                 size = lvb->lvb_size;
 369                 /* Extend KMS up to the end of this lock and no further
 370                  * A lock on [x,y] means a KMS of up to y + 1 bytes! */
 371                 if (size > dlmlock->l_policy_data.l_extent.end)
 372                         size = dlmlock->l_policy_data.l_extent.end + 1;
 373                 if (size >= oinfo->loi_kms) {
 374                         LDLM_DEBUG(dlmlock, "lock acquired, setting rss="LPU64
 375                                    ", kms="LPU64, lvb->lvb_size, size);
 376                         valid |= CAT_KMS;
 377                         attr->cat_kms = size;
 378                 } else {
 379                         LDLM_DEBUG(dlmlock, "lock acquired, setting rss="
 380                                    LPU64"; leaving kms="LPU64", end="LPU64,
 381                                    lvb->lvb_size, oinfo->loi_kms,
 382                                    dlmlock->l_policy_data.l_extent.end);
 383                 }
 384                 ldlm_lock_allow_match_locked(dlmlock);
 385         } else if (rc == -ENAVAIL && olck->ols_glimpse) {
 386                 CDEBUG(D_INODE, "glimpsed, setting rss="LPU64"; leaving"
 387                        " kms="LPU64"\n", lvb->lvb_size, oinfo->loi_kms);
 388         } else
 389                 valid = 0;
 390
 391         if (valid != 0)
 392                 cl_object_attr_set(env, obj, attr, valid);
 393
 394         cl_object_attr_unlock(obj);
 395
 396         EXIT;
 397 }
 398
 399 /**
 400  * Called when a lock is granted, from an upcall (when server returned a
 401  * granted lock), or from completion AST, when server returned a blocked lock.
 402  *
 403  * Called under lock and resource spin-locks, that are released temporarily
 404  * here.
 405  */
 406 static void osc_lock_granted(const struct lu_env *env, struct osc_lock *olck,
 407                              struct ldlm_lock *dlmlock, int rc)
 408 {
 409         struct ldlm_extent   *ext;
 410         struct cl_lock       *lock;
 411         struct cl_lock_descr *descr;
 412
 413         LASSERT(dlmlock->l_granted_mode == dlmlock->l_req_mode);
 414
 415         ENTRY;
 416         if (olck->ols_state < OLS_GRANTED) {
 417                 lock  = olck->ols_cl.cls_lock;
 418                 ext   = &dlmlock->l_policy_data.l_extent;
 419                 descr = &osc_env_info(env)->oti_descr;
 420                 descr->cld_obj = lock->cll_descr.cld_obj;
 421
 422                 /* XXX check that ->l_granted_mode is valid. */
 423                 descr->cld_mode  = osc_ldlm2cl_lock(dlmlock->l_granted_mode);
 424                 descr->cld_start = cl_index(descr->cld_obj, ext->start);
 425                 descr->cld_end   = cl_index(descr->cld_obj, ext->end);
 426                 descr->cld_gid   = ext->gid;
 427                 /*
 428                  * tell upper layers the extent of the lock that was actually
 429                  * granted
 430                  */
 431                 olck->ols_state = OLS_GRANTED;
 432                 osc_lock_lvb_update(env, olck, rc);
 433
 434                 /* release DLM spin-locks to allow cl_lock_{modify,signal}()
 435                  * to take a semaphore on a parent lock. This is safe, because
 436                  * spin-locks are needed to protect consistency of
 437                  * dlmlock->l_*_mode and LVB, and we have finished processing
 438                  * them. */
 439                 unlock_res_and_lock(dlmlock);
 440                 cl_lock_modify(env, lock, descr);
 441                 cl_lock_signal(env, lock);
 442                 LINVRNT(osc_lock_invariant(olck));
 443                 lock_res_and_lock(dlmlock);
 444         }
 445         EXIT;
 446 }
 447
 448 static void osc_lock_upcall0(const struct lu_env *env, struct osc_lock *olck)
 449
 450 {
 451         struct ldlm_lock *dlmlock;
 452
 453         ENTRY;
 454
 455         dlmlock = ldlm_handle2lock_long(&olck->ols_handle, 0);
 456         LASSERT(dlmlock != NULL);
 457
 458         lock_res_and_lock(dlmlock);
 459         spin_lock(&osc_ast_guard);
 460         LASSERT(dlmlock->l_ast_data == olck);
 461         LASSERT(olck->ols_lock == NULL);
 462         olck->ols_lock = dlmlock;
 463         spin_unlock(&osc_ast_guard);
 464
 465         /*
 466          * Lock might be not yet granted. In this case, completion ast
 467          * (osc_ldlm_completion_ast()) comes later and finishes lock
 468          * granting.
 469          */
 470         if (dlmlock->l_granted_mode == dlmlock->l_req_mode)
 471                 osc_lock_granted(env, olck, dlmlock, 0);
 472         unlock_res_and_lock(dlmlock);
 473
 474         /*
 475          * osc_enqueue_interpret() decrefs asynchronous locks, counter
 476          * this.
 477          */
 478         ldlm_lock_addref(&olck->ols_handle, olck->ols_einfo.ei_mode);
 479         olck->ols_hold = 1;
 480
 481         /* lock reference taken by ldlm_handle2lock_long() is owned by
 482          * osc_lock and released in osc_lock_detach() */
 483         lu_ref_add(&dlmlock->l_reference, "osc_lock", olck);
 484         olck->ols_has_ref = 1;
 485 }
 486
 487 /**
 488  * Lock upcall function that is executed either when a reply to ENQUEUE rpc is
 489  * received from a server, or after osc_enqueue_base() matched a local DLM
 490  * lock.
 491  */
 492 static int osc_lock_upcall(void *cookie, int errcode)
 493 {
 494         struct osc_lock         *olck  = cookie;
 495         struct cl_lock_slice    *slice = &olck->ols_cl;
 496         struct cl_lock          *lock  = slice->cls_lock;
 497         struct lu_env           *env;
 498         struct cl_env_nest       nest;
 499
 500         ENTRY;
 501         env = cl_env_nested_get(&nest);
 502         if (!IS_ERR(env)) {
 503                 int rc;
 504
 505                 cl_lock_mutex_get(env, lock);
 506
 507                 LASSERT(lock->cll_state >= CLS_QUEUING);
 508                 if (olck->ols_state == OLS_ENQUEUED) {
 509                         olck->ols_state = OLS_UPCALL_RECEIVED;
 510                         rc = ldlm_error2errno(errcode);
 511                 } else if (olck->ols_state == OLS_CANCELLED) {
 512                         rc = -EIO;
 513                 } else {
 514                         CERROR("Impossible state: %d\n", olck->ols_state);
 515                         LBUG();
 516                 }
 517                 if (rc) {
 518                         struct ldlm_lock *dlmlock;
 519
 520                         dlmlock = ldlm_handle2lock(&olck->ols_handle);
 521                         if (dlmlock != NULL) {
 522                                 lock_res_and_lock(dlmlock);
 523                                 spin_lock(&osc_ast_guard);
 524                                 LASSERT(olck->ols_lock == NULL);
 525                                 dlmlock->l_ast_data = NULL;
 526                                 olck->ols_handle.cookie = 0ULL;
 527                                 spin_unlock(&osc_ast_guard);
 528                                 ldlm_lock_fail_match_locked(dlmlock);
 529                                 unlock_res_and_lock(dlmlock);
 530                                 LDLM_LOCK_PUT(dlmlock);
 531                         }
 532                 } else {
 533                         if (olck->ols_glimpse)
 534                                 olck->ols_glimpse = 0;
 535                         osc_lock_upcall0(env, olck);
 536                 }
 537
 538                 /* Error handling, some errors are tolerable. */
 539                 if (olck->ols_locklessable && rc == -EUSERS) {
 540                         /* This is a tolerable error, turn this lock into
 541                          * lockless lock.
 542                          */
 543                         osc_object_set_contended(cl2osc(slice->cls_obj));
 544                         LASSERT(slice->cls_ops == &osc_lock_ops);
 545
 546                         /* Change this lock to ldlmlock-less lock. */
 547                         osc_lock_to_lockless(env, olck, 1);
 548                         olck->ols_state = OLS_GRANTED;
 549                         rc = 0;
 550                 } else if (olck->ols_glimpse && rc == -ENAVAIL) {
 551                         osc_lock_lvb_update(env, olck, rc);
 552                         cl_lock_delete(env, lock);
 553                         /* Hide the error. */
 554                         rc = 0;
 555                 }
 556
 557                 if (rc == 0) {
 558                         /* For AGL case, the RPC sponsor may exits the cl_lock
 559                         *  processing without wait() called before related OSC
 560                         *  lock upcall(). So update the lock status according
 561                         *  to the enqueue result inside AGL upcall(). */
 562                         if (olck->ols_agl) {
 563                                 lock->cll_flags |= CLF_FROM_UPCALL;
 564                                 cl_wait_try(env, lock);
 565                                 lock->cll_flags &= ~CLF_FROM_UPCALL;
 566                         }
 567                         cl_lock_signal(env, lock);
 568                         /* del user for lock upcall cookie */
 569                         if (olck->ols_agl) {
 570                                 if (!olck->ols_glimpse)
 571                                         olck->ols_agl = 0;
 572                                 cl_unuse_try(env, lock);
 573                         }
 574                 } else {
 575                         /* del user for lock upcall cookie */
 576                         if (olck->ols_agl)
 577                                 cl_lock_user_del(env, lock);
 578                         cl_lock_error(env, lock, rc);
 579                 }
 580
 581                 /* release cookie reference, acquired by osc_lock_enqueue() */
 582                 cl_lock_hold_release(env, lock, "upcall", lock);
 583                 cl_lock_mutex_put(env, lock);
 584
 585                 lu_ref_del(&lock->cll_reference, "upcall", lock);
 586                 /* This maybe the last reference, so must be called after
 587                  * cl_lock_mutex_put(). */
 588                 cl_lock_put(env, lock);
 589
 590                 cl_env_nested_put(&nest, env);
 591         } else {
 592                 /* should never happen, similar to osc_ldlm_blocking_ast(). */
 593                 LBUG();
 594         }
 595         RETURN(errcode);
 596 }
 597
 598 /**
 599  * Core of osc_dlm_blocking_ast() logic.
 600  */
 601 static void osc_lock_blocking(const struct lu_env *env,
 602                               struct ldlm_lock *dlmlock,
 603                               struct osc_lock *olck, int blocking)
 604 {
 605         struct cl_lock *lock = olck->ols_cl.cls_lock;
 606
 607         LASSERT(olck->ols_lock == dlmlock);
 608         CLASSERT(OLS_BLOCKED < OLS_CANCELLED);
 609         LASSERT(!osc_lock_is_lockless(olck));
 610
 611         /*
 612          * Lock might be still addref-ed here, if e.g., blocking ast
 613          * is sent for a failed lock.
 614          */
 615         osc_lock_unhold(olck);
 616
 617         if (blocking && olck->ols_state < OLS_BLOCKED)
 618                 /*
 619                  * Move osc_lock into OLS_BLOCKED before canceling the lock,
 620                  * because it recursively re-enters osc_lock_blocking(), with
 621                  * the state set to OLS_CANCELLED.
 622                  */
 623                 olck->ols_state = OLS_BLOCKED;
 624         /*
 625          * cancel and destroy lock at least once no matter how blocking ast is
 626          * entered (see comment above osc_ldlm_blocking_ast() for use
 627          * cases). cl_lock_cancel() and cl_lock_delete() are idempotent.
 628          */
 629         cl_lock_cancel(env, lock);
 630         cl_lock_delete(env, lock);
 631 }
 632
 633 /**
 634  * Helper for osc_dlm_blocking_ast() handling discrepancies between cl_lock
 635  * and ldlm_lock caches.
 636  */
 637 static int osc_dlm_blocking_ast0(const struct lu_env *env,
 638                                  struct ldlm_lock *dlmlock,
 639                                  void *data, int flag)
 640 {
 641         struct osc_lock *olck;
 642         struct cl_lock  *lock;
 643         int result;
 644         int cancel;
 645
 646         LASSERT(flag == LDLM_CB_BLOCKING || flag == LDLM_CB_CANCELING);
 647
 648         cancel = 0;
 649         olck = osc_ast_data_get(dlmlock);
 650         if (olck != NULL) {
 651                 lock = olck->ols_cl.cls_lock;
 652                 cl_lock_mutex_get(env, lock);
 653                 LINVRNT(osc_lock_invariant(olck));
 654                 if (olck->ols_ast_wait) {
 655                         /* wake up osc_lock_use() */
 656                         cl_lock_signal(env, lock);
 657                         olck->ols_ast_wait = 0;
 658                 }
 659                 /*
 660                  * Lock might have been canceled while this thread was
 661                  * sleeping for lock mutex, but olck is pinned in memory.
 662                  */
 663                 if (olck == dlmlock->l_ast_data) {
 664                         /*
 665                          * NOTE: DLM sends blocking AST's for failed locks
 666                          *       (that are still in pre-OLS_GRANTED state)
 667                          *       too, and they have to be canceled otherwise
 668                          *       DLM lock is never destroyed and stuck in
 669                          *       the memory.
 670                          *
 671                          *       Alternatively, ldlm_cli_cancel() can be
 672                          *       called here directly for osc_locks with
 673                          *       ols_state < OLS_GRANTED to maintain an
 674                          *       invariant that ->clo_cancel() is only called
 675                          *       for locks that were granted.
 676                          */
 677                         LASSERT(data == olck);
 678                         osc_lock_blocking(env, dlmlock,
 679                                           olck, flag == LDLM_CB_BLOCKING);
 680                 } else
 681                         cancel = 1;
 682                 cl_lock_mutex_put(env, lock);
 683                 osc_ast_data_put(env, olck);
 684         } else
 685                 /*
 686                  * DLM lock exists, but there is no cl_lock attached to it.
 687                  * This is a `normal' race. cl_object and its cl_lock's can be
 688                  * removed by memory pressure, together with all pages.
 689                  */
 690                 cancel = (flag == LDLM_CB_BLOCKING);
 691
 692         if (cancel) {
 693                 struct lustre_handle *lockh;
 694
 695                 lockh = &osc_env_info(env)->oti_handle;
 696                 ldlm_lock2handle(dlmlock, lockh);
 697                 result = ldlm_cli_cancel(lockh, LCF_ASYNC);
 698         } else
 699                 result = 0;
 700         return result;
 701 }
 702
 703 /**
 704  * Blocking ast invoked by ldlm when dlm lock is either blocking progress of
 705  * some other lock, or is canceled. This function is installed as a
 706  * ldlm_lock::l_blocking_ast() for client extent locks.
 707  *
 708  * Control flow is tricky, because ldlm uses the same call-back
 709  * (ldlm_lock::l_blocking_ast()) for both blocking and cancellation ast's.
 710  *
 711  * \param dlmlock lock for which ast occurred.
 712  *
 713  * \param new description of a conflicting lock in case of blocking ast.
 714  *
 715  * \param data value of dlmlock->l_ast_data
 716  *
 717  * \param flag LDLM_CB_BLOCKING or LDLM_CB_CANCELING. Used to distinguish
 718  *             cancellation and blocking ast's.
 719  *
 720  * Possible use cases:
 721  *
 722  *     - ldlm calls dlmlock->l_blocking_ast(..., LDLM_CB_CANCELING) to cancel
 723  *       lock due to lock lru pressure, or explicit user request to purge
 724  *       locks.
 725  *
 726  *     - ldlm calls dlmlock->l_blocking_ast(..., LDLM_CB_BLOCKING) to notify
 727  *       us that dlmlock conflicts with another lock that some client is
 728  *       enqueing. Lock is canceled.
 729  *
 730  *           - cl_lock_cancel() is called. osc_lock_cancel() calls
 731  *             ldlm_cli_cancel() that calls
 732  *
 733  *                  dlmlock->l_blocking_ast(..., LDLM_CB_CANCELING)
 734  *
 735  *             recursively entering osc_ldlm_blocking_ast().
 736  *
 737  *     - client cancels lock voluntary (e.g., as a part of early cancellation):
 738  *
 739  *           cl_lock_cancel()->
 740  *             osc_lock_cancel()->
 741  *               ldlm_cli_cancel()->
 742  *                 dlmlock->l_blocking_ast(..., LDLM_CB_CANCELING)
 743  *
 744  */
 745 static int osc_ldlm_blocking_ast(struct ldlm_lock *dlmlock,
 746                                  struct ldlm_lock_desc *new, void *data,
 747                                  int flag)
 748 {
 749         struct lu_env     *env;
 750         struct cl_env_nest nest;
 751         int                result;
 752
 753         /*
 754          * This can be called in the context of outer IO, e.g.,
 755          *
 756          *     cl_enqueue()->...
 757          *       ->osc_enqueue_base()->...
 758          *         ->ldlm_prep_elc_req()->...
 759          *           ->ldlm_cancel_callback()->...
 760          *             ->osc_ldlm_blocking_ast()
 761          *
 762          * new environment has to be created to not corrupt outer context.
 763          */
 764         env = cl_env_nested_get(&nest);
 765         if (!IS_ERR(env)) {
 766                 result = osc_dlm_blocking_ast0(env, dlmlock, data, flag);
 767                 cl_env_nested_put(&nest, env);
 768         } else {
 769                 result = PTR_ERR(env);
 770                 /*
 771                  * XXX This should never happen, as cl_lock is
 772                  * stuck. Pre-allocated environment a la vvp_inode_fini_env
 773                  * should be used.
 774                  */
 775                 LBUG();
 776         }
 777         if (result != 0) {
 778                 if (result == -ENODATA)
 779                         result = 0;
 780                 else
 781                         CERROR("BAST failed: %d\n", result);
 782         }
 783         return result;
 784 }
 785
 786 static int osc_ldlm_completion_ast(struct ldlm_lock *dlmlock,
 787                                    __u64 flags, void *data)
 788 {
 789         struct cl_env_nest nest;
 790         struct lu_env     *env;
 791         struct osc_lock   *olck;
 792         struct cl_lock    *lock;
 793         int result;
 794         int dlmrc;
 795
 796         /* first, do dlm part of the work */
 797         dlmrc = ldlm_completion_ast_async(dlmlock, flags, data);
 798         /* then, notify cl_lock */
 799         env = cl_env_nested_get(&nest);
 800         if (!IS_ERR(env)) {
 801                 olck = osc_ast_data_get(dlmlock);
 802                 if (olck != NULL) {
 803                         lock = olck->ols_cl.cls_lock;
 804                         cl_lock_mutex_get(env, lock);
 805                         /*
 806                          * ldlm_handle_cp_callback() copied LVB from request
 807                          * to lock->l_lvb_data, store it in osc_lock.
 808                          */
 809                         LASSERT(dlmlock->l_lvb_data != NULL);
 810                         lock_res_and_lock(dlmlock);
 811                         olck->ols_lvb = *(struct ost_lvb *)dlmlock->l_lvb_data;
 812                         if (olck->ols_lock == NULL) {
 813                                 /*
 814                                  * upcall (osc_lock_upcall()) hasn't yet been
 815                                  * called. Do nothing now, upcall will bind
 816                                  * olck to dlmlock and signal the waiters.
 817                                  *
 818                                  * This maintains an invariant that osc_lock
 819                                  * and ldlm_lock are always bound when
 820                                  * osc_lock is in OLS_GRANTED state.
 821                                  */
 822                         } else if (dlmlock->l_granted_mode ==
 823                                    dlmlock->l_req_mode) {
 824                                 osc_lock_granted(env, olck, dlmlock, dlmrc);
 825                         }
 826                         unlock_res_and_lock(dlmlock);
 827
 828                         if (dlmrc != 0) {
 829                                 CL_LOCK_DEBUG(D_ERROR, env, lock,
 830                                               "dlmlock returned %d\n", dlmrc);
 831                                 cl_lock_error(env, lock, dlmrc);
 832                         }
 833                         cl_lock_mutex_put(env, lock);
 834                         osc_ast_data_put(env, olck);
 835                         result = 0;
 836                 } else
 837                         result = -ELDLM_NO_LOCK_DATA;
 838                 cl_env_nested_put(&nest, env);
 839         } else
 840                 result = PTR_ERR(env);
 841         return dlmrc ?: result;
 842 }
 843
 844 static int osc_ldlm_glimpse_ast(struct ldlm_lock *dlmlock, void *data)
 845 {
 846         struct ptlrpc_request  *req  = data;
 847         struct osc_lock        *olck;
 848         struct cl_lock         *lock;
 849         struct cl_object       *obj;
 850         struct cl_env_nest      nest;
 851         struct lu_env          *env;
 852         struct ost_lvb         *lvb;
 853         struct req_capsule     *cap;
 854         int                     result;
 855
 856         LASSERT(lustre_msg_get_opc(req->rq_reqmsg) == LDLM_GL_CALLBACK);
 857
 858         env = cl_env_nested_get(&nest);
 859         if (!IS_ERR(env)) {
 860                 /* osc_ast_data_get() has to go after environment is
 861                  * allocated, because osc_ast_data() acquires a
 862                  * reference to a lock, and it can only be released in
 863                  * environment.
 864                  */
 865                 olck = osc_ast_data_get(dlmlock);
 866                 if (olck != NULL) {
 867                         lock = olck->ols_cl.cls_lock;
 868                         /* Do not grab the mutex of cl_lock for glimpse.
 869                          * See LU-1274 for details.
 870                          * BTW, it's okay for cl_lock to be cancelled during
 871                          * this period because server can handle this race.
 872                          * See ldlm_server_glimpse_ast() for details.
 873                          * cl_lock_mutex_get(env, lock); */
 874                         cap = &req->rq_pill;
 875                         req_capsule_extend(cap, &RQF_LDLM_GL_CALLBACK);
 876                         req_capsule_set_size(cap, &RMF_DLM_LVB, RCL_SERVER,
 877                                              sizeof *lvb);
 878                         result = req_capsule_server_pack(cap);
 879                         if (result == 0) {
 880                                 lvb = req_capsule_server_get(cap, &RMF_DLM_LVB);
 881                                 obj = lock->cll_descr.cld_obj;
 882                                 result = cl_object_glimpse(env, obj, lvb);
 883                         }
 884                         if (!exp_connect_lvb_type(req->rq_export))
 885                                 req_capsule_shrink(&req->rq_pill,
 886                                                    &RMF_DLM_LVB,
 887                                                    sizeof(struct ost_lvb_v1),
 888                                                    RCL_SERVER);
 889                         osc_ast_data_put(env, olck);
 890                 } else {
 891                         /*
 892                          * These errors are normal races, so we don't want to
 893                          * fill the console with messages by calling
 894                          * ptlrpc_error()
 895                          */
 896                         lustre_pack_reply(req, 1, NULL, NULL);
 897                         result = -ELDLM_NO_LOCK_DATA;
 898                 }
 899                 cl_env_nested_put(&nest, env);
 900         } else
 901                 result = PTR_ERR(env);
 902         req->rq_status = result;
 903         return result;
 904 }
 905
 906 static int weigh_cb(const struct lu_env *env, struct cl_io *io,
 907                     struct osc_page *ops, void *cbdata)
 908 {
 909         struct cl_page *page = ops->ops_cl.cpl_page;
 910
 911         if (cl_page_is_vmlocked(env, page)
 912 #if defined(__KERNEL__)
 913             || PageDirty(page->cp_vmpage) || PageWriteback(page->cp_vmpage)
 914 #endif
 915            ) {
 916                 (*(unsigned long *)cbdata)++;
 917                 return CLP_GANG_ABORT;
 918         }
 919
 920         return CLP_GANG_OKAY;
 921 }
 922
 923 static unsigned long osc_lock_weight(const struct lu_env *env,
 924                                      const struct osc_lock *ols)
 925 {
 926         struct cl_io *io = &osc_env_info(env)->oti_io;
 927         struct cl_lock_descr *descr = &ols->ols_cl.cls_lock->cll_descr;
 928         struct cl_object *obj = ols->ols_cl.cls_obj;
 929         unsigned long npages = 0;
 930         int result;
 931         ENTRY;
 932
 933         io->ci_obj = cl_object_top(obj);
 934         io->ci_ignore_layout = 1;
 935         result = cl_io_init(env, io, CIT_MISC, io->ci_obj);
 936         if (result != 0)
 937                 RETURN(result);
 938
 939         do {
 940                 result = osc_page_gang_lookup(env, io, cl2osc(obj),
 941                                               descr->cld_start, descr->cld_end,
 942                                               weigh_cb, (void *)&npages);
 943                 if (result == CLP_GANG_ABORT)
 944                         break;
 945                 if (result == CLP_GANG_RESCHED)
 946                         cond_resched();
 947         } while (result != CLP_GANG_OKAY);
 948         cl_io_fini(env, io);
 949
 950         return npages;
 951 }
 952
 953 /**
 954  * Get the weight of dlm lock for early cancellation.
 955  */
 956 unsigned long osc_ldlm_weigh_ast(struct ldlm_lock *dlmlock)
 957 {
 958         struct cl_env_nest       nest;
 959         struct lu_env           *env;
 960         struct osc_lock         *lock;
 961         unsigned long            weight;
 962         ENTRY;
 963
 964         might_sleep();
 965         /*
 966          * osc_ldlm_weigh_ast has a complex context since it might be called
 967          * because of lock canceling, or from user's input. We have to make
 968          * a new environment for it. Probably it is implementation safe to use
 969          * the upper context because cl_lock_put don't modify environment
 970          * variables. But just in case ..
 971          */
 972         env = cl_env_nested_get(&nest);
 973         if (IS_ERR(env))
 974                 /* Mostly because lack of memory, do not eliminate this lock */
 975                 RETURN(1);
 976
 977         LASSERT(dlmlock->l_resource->lr_type == LDLM_EXTENT);
 978         lock = osc_ast_data_get(dlmlock);
 979         if (lock == NULL) {
 980                 /* cl_lock was destroyed because of memory pressure.
 981                  * It is much reasonable to assign this type of lock
 982                  * a lower cost.
 983                  */
 984                 GOTO(out, weight = 0);
 985         }
 986
 987         weight = osc_lock_weight(env, lock);
 988         osc_ast_data_put(env, lock);
 989         EXIT;
 990
 991 out:
 992         cl_env_nested_put(&nest, env);
 993         return weight;
 994 }
 995
 996 static void osc_lock_build_einfo(const struct lu_env *env,
 997                                  const struct cl_lock *clock,
 998                                  struct osc_lock *lock,
 999                                  struct ldlm_enqueue_info *einfo)
1000 {
1001         enum cl_lock_mode mode;
1002
1003         mode = clock->cll_descr.cld_mode;
1004         if (mode == CLM_PHANTOM)
1005                 /*
1006                  * For now, enqueue all glimpse locks in read mode. In the
1007                  * future, client might choose to enqueue LCK_PW lock for
1008                  * glimpse on a file opened for write.
1009                  */
1010                 mode = CLM_READ;
1011
1012         einfo->ei_type   = LDLM_EXTENT;
1013         einfo->ei_mode   = osc_cl_lock2ldlm(mode);
1014         einfo->ei_cb_bl  = osc_ldlm_blocking_ast;
1015         einfo->ei_cb_cp  = osc_ldlm_completion_ast;
1016         einfo->ei_cb_gl  = osc_ldlm_glimpse_ast;
1017         einfo->ei_cbdata = lock; /* value to be put into ->l_ast_data */
1018 }
1019
1020 /**
1021  * Determine if the lock should be converted into a lockless lock.
1022  *
1023  * Steps to check:
1024  * - if the lock has an explicite requirment for a non-lockless lock;
1025  * - if the io lock request type ci_lockreq;
1026  * - send the enqueue rpc to ost to make the further decision;
1027  * - special treat to truncate lockless lock
1028  *
1029  *  Additional policy can be implemented here, e.g., never do lockless-io
1030  *  for large extents.
1031  */
1032 static void osc_lock_to_lockless(const struct lu_env *env,
1033                                  struct osc_lock *ols, int force)
1034 {
1035         struct cl_lock_slice *slice = &ols->ols_cl;
1036
1037         LASSERT(ols->ols_state == OLS_NEW ||
1038                 ols->ols_state == OLS_UPCALL_RECEIVED);
1039
1040         if (force) {
1041                 ols->ols_locklessable = 1;
1042                 slice->cls_ops = &osc_lock_lockless_ops;
1043         } else {
1044                 struct osc_io *oio     = osc_env_io(env);
1045                 struct cl_io  *io      = oio->oi_cl.cis_io;
1046                 struct cl_object *obj  = slice->cls_obj;
1047                 struct osc_object *oob = cl2osc(obj);
1048                 const struct osc_device *osd = lu2osc_dev(obj->co_lu.lo_dev);
1049                 struct obd_connect_data *ocd;
1050
1051                 LASSERT(io->ci_lockreq == CILR_MANDATORY ||
1052                         io->ci_lockreq == CILR_MAYBE ||
1053                         io->ci_lockreq == CILR_NEVER);
1054
1055                 ocd = &class_exp2cliimp(osc_export(oob))->imp_connect_data;
1056                 ols->ols_locklessable = (io->ci_type != CIT_SETATTR) &&
1057                                 (io->ci_lockreq == CILR_MAYBE) &&
1058                                 (ocd->ocd_connect_flags & OBD_CONNECT_SRVLOCK);
1059                 if (io->ci_lockreq == CILR_NEVER ||
1060                         /* lockless IO */
1061                     (ols->ols_locklessable && osc_object_is_contended(oob)) ||
1062                         /* lockless truncate */
1063                     (cl_io_is_trunc(io) &&
1064                      (ocd->ocd_connect_flags & OBD_CONNECT_TRUNCLOCK) &&
1065                       osd->od_lockless_truncate)) {
1066                         ols->ols_locklessable = 1;
1067                         slice->cls_ops = &osc_lock_lockless_ops;
1068                 }
1069         }
1070         LASSERT(ergo(ols->ols_glimpse, !osc_lock_is_lockless(ols)));
1071 }
1072
1073 static int osc_lock_compatible(const struct osc_lock *qing,
1074                                const struct osc_lock *qed)
1075 {
1076         enum cl_lock_mode qing_mode;
1077         enum cl_lock_mode qed_mode;
1078
1079         qing_mode = qing->ols_cl.cls_lock->cll_descr.cld_mode;
1080         if (qed->ols_glimpse &&
1081             (qed->ols_state >= OLS_UPCALL_RECEIVED || qing_mode == CLM_READ))
1082                 return 1;
1083
1084         qed_mode = qed->ols_cl.cls_lock->cll_descr.cld_mode;
1085         return ((qing_mode == CLM_READ) && (qed_mode == CLM_READ));
1086 }
1087
1088 /**
1089  * Cancel all conflicting locks and wait for them to be destroyed.
1090  *
1091  * This function is used for two purposes:
1092  *
1093  *     - early cancel all conflicting locks before starting IO, and
1094  *
1095  *     - guarantee that pages added to the page cache by lockless IO are never
1096  *       covered by locks other than lockless IO lock, and, hence, are not
1097  *       visible to other threads.
1098  */
1099 static int osc_lock_enqueue_wait(const struct lu_env *env,
1100                                  const struct osc_lock *olck)
1101 {
1102         struct cl_lock          *lock    = olck->ols_cl.cls_lock;
1103         struct cl_lock_descr    *descr   = &lock->cll_descr;
1104         struct cl_object_header *hdr     = cl_object_header(descr->cld_obj);
1105         struct cl_lock          *scan;
1106         struct cl_lock          *conflict= NULL;
1107         int lockless                     = osc_lock_is_lockless(olck);
1108         int rc                           = 0;
1109         ENTRY;
1110
1111         LASSERT(cl_lock_is_mutexed(lock));
1112
1113         /* make it enqueue anyway for glimpse lock, because we actually
1114          * don't need to cancel any conflicting locks. */
1115         if (olck->ols_glimpse)
1116                 return 0;
1117
1118         spin_lock(&hdr->coh_lock_guard);
1119         list_for_each_entry(scan, &hdr->coh_locks, cll_linkage) {
1120                 struct cl_lock_descr *cld = &scan->cll_descr;
1121                 const struct osc_lock *scan_ols;
1122
1123                 if (scan == lock)
1124                         break;
1125
1126                 if (scan->cll_state < CLS_QUEUING ||
1127                     scan->cll_state == CLS_FREEING ||
1128                     cld->cld_start > descr->cld_end ||
1129                     cld->cld_end < descr->cld_start)
1130                         continue;
1131
1132                 /* overlapped and living locks. */
1133
1134                 /* We're not supposed to give up group lock. */
1135                 if (scan->cll_descr.cld_mode == CLM_GROUP) {
1136                         LASSERT(descr->cld_mode != CLM_GROUP ||
1137                                 descr->cld_gid != scan->cll_descr.cld_gid);
1138                         continue;
1139                 }
1140
1141                 scan_ols = osc_lock_at(scan);
1142
1143                 /* We need to cancel the compatible locks if we're enqueuing
1144                  * a lockless lock, for example:
1145                  * imagine that client has PR lock on [0, 1000], and thread T0
1146                  * is doing lockless IO in [500, 1500] region. Concurrent
1147                  * thread T1 can see lockless data in [500, 1000], which is
1148                  * wrong, because these data are possibly stale. */
1149                 if (!lockless && osc_lock_compatible(olck, scan_ols))
1150                         continue;
1151
1152                 cl_lock_get_trust(scan);
1153                 conflict = scan;
1154                 break;
1155         }
1156         spin_unlock(&hdr->coh_lock_guard);
1157
1158         if (conflict) {
1159                 if (lock->cll_descr.cld_mode == CLM_GROUP) {
1160                         /* we want a group lock but a previous lock request
1161                          * conflicts, we do not wait but return 0 so the
1162                          * request is send to the server
1163                          */
1164                         CDEBUG(D_DLMTRACE, "group lock %p is conflicted "
1165                                            "with %p, no wait, send to server\n",
1166                                lock, conflict);
1167                         cl_lock_put(env, conflict);
1168                         rc = 0;
1169                 } else {
1170                         CDEBUG(D_DLMTRACE, "lock %p is conflicted with %p, "
1171                                            "will wait\n",
1172                                lock, conflict);
1173                         LASSERT(lock->cll_conflict == NULL);
1174                         lu_ref_add(&conflict->cll_reference, "cancel-wait",
1175                                    lock);
1176                         lock->cll_conflict = conflict;
1177                         rc = CLO_WAIT;
1178                 }
1179         }
1180         RETURN(rc);
1181 }
1182
1183 /**
1184  * Implementation of cl_lock_operations::clo_enqueue() method for osc
1185  * layer. This initiates ldlm enqueue:
1186  *
1187  *     - cancels conflicting locks early (osc_lock_enqueue_wait());
1188  *
1189  *     - calls osc_enqueue_base() to do actual enqueue.
1190  *
1191  * osc_enqueue_base() is supplied with an upcall function that is executed
1192  * when lock is received either after a local cached ldlm lock is matched, or
1193  * when a reply from the server is received.
1194  *
1195  * This function does not wait for the network communication to complete.
1196  */
1197 static int osc_lock_enqueue(const struct lu_env *env,
1198                             const struct cl_lock_slice *slice,
1199                             struct cl_io *unused, __u32 enqflags)
1200 {
1201         struct osc_lock          *ols     = cl2osc_lock(slice);
1202         struct cl_lock           *lock    = ols->ols_cl.cls_lock;
1203         int result;
1204         ENTRY;
1205
1206         LASSERT(cl_lock_is_mutexed(lock));
1207         LASSERTF(ols->ols_state == OLS_NEW,
1208                  "Impossible state: %d\n", ols->ols_state);
1209
1210         LASSERTF(ergo(ols->ols_glimpse, lock->cll_descr.cld_mode <= CLM_READ),
1211                 "lock = %p, ols = %p\n", lock, ols);
1212
1213         result = osc_lock_enqueue_wait(env, ols);
1214         if (result == 0) {
1215                 if (!osc_lock_is_lockless(ols)) {
1216                         struct osc_object        *obj = cl2osc(slice->cls_obj);
1217                         struct osc_thread_info   *info = osc_env_info(env);
1218                         struct ldlm_res_id       *resname = &info->oti_resname;
1219                         ldlm_policy_data_t       *policy = &info->oti_policy;
1220                         struct ldlm_enqueue_info *einfo = &ols->ols_einfo;
1221
1222                         /* lock will be passed as upcall cookie,
1223                          * hold ref to prevent to be released. */
1224                         cl_lock_hold_add(env, lock, "upcall", lock);
1225                         /* a user for agl lock also */
1226                         if (ols->ols_agl)
1227                                 cl_lock_user_add(env, lock);
1228                         ols->ols_state = OLS_ENQUEUED;
1229
1230                         /*
1231                          * XXX: this is possible blocking point as
1232                          * ldlm_lock_match(LDLM_FL_LVB_READY) waits for
1233                          * LDLM_CP_CALLBACK.
1234                          */
1235                         ostid_build_res_name(&obj->oo_oinfo->loi_oi, resname);
1236                         osc_lock_build_policy(env, lock, policy);
1237                         result = osc_enqueue_base(osc_export(obj), resname,
1238                                           &ols->ols_flags, policy,
1239                                           &ols->ols_lvb,
1240                                           obj->oo_oinfo->loi_kms_valid,
1241                                           osc_lock_upcall,
1242                                           ols, einfo, &ols->ols_handle,
1243                                           PTLRPCD_SET, 1, ols->ols_agl);
1244                         if (result != 0) {
1245                                 if (ols->ols_agl)
1246                                         cl_lock_user_del(env, lock);
1247                                 cl_lock_unhold(env, lock, "upcall", lock);
1248                                 if (unlikely(result == -ECANCELED)) {
1249                                         ols->ols_state = OLS_NEW;
1250                                         result = 0;
1251                                 }
1252                         }
1253                 } else {
1254                         ols->ols_state = OLS_GRANTED;
1255                         ols->ols_owner = osc_env_io(env);
1256                 }
1257         }
1258         LASSERT(ergo(ols->ols_glimpse, !osc_lock_is_lockless(ols)));
1259         RETURN(result);
1260 }
1261
1262 static int osc_lock_wait(const struct lu_env *env,
1263                          const struct cl_lock_slice *slice)
1264 {
1265         struct osc_lock *olck = cl2osc_lock(slice);
1266         struct cl_lock  *lock = olck->ols_cl.cls_lock;
1267
1268         LINVRNT(osc_lock_invariant(olck));
1269
1270         if (olck->ols_glimpse && olck->ols_state >= OLS_UPCALL_RECEIVED) {
1271                 if (olck->ols_flags & LDLM_FL_LVB_READY) {
1272                         return 0;
1273                 } else if (olck->ols_agl) {
1274                         if (lock->cll_flags & CLF_FROM_UPCALL)
1275                                 /* It is from enqueue RPC reply upcall for
1276                                  * updating state. Do not re-enqueue. */
1277                                 return -ENAVAIL;
1278                         else
1279                                 olck->ols_state = OLS_NEW;
1280                 } else {
1281                         LASSERT(lock->cll_error);
1282                         return lock->cll_error;
1283                 }
1284         }
1285
1286         if (olck->ols_state == OLS_NEW) {
1287                 int rc;
1288
1289                 LASSERT(olck->ols_agl);
1290                 olck->ols_agl = 0;
1291                 olck->ols_flags &= ~LDLM_FL_BLOCK_NOWAIT;
1292                 rc = osc_lock_enqueue(env, slice, NULL, CEF_ASYNC | CEF_MUST);
1293                 if (rc != 0)
1294                         return rc;
1295                 else
1296                         return CLO_REENQUEUED;
1297         }
1298
1299         LASSERT(equi(olck->ols_state >= OLS_UPCALL_RECEIVED &&
1300                      lock->cll_error == 0, olck->ols_lock != NULL));
1301
1302         return lock->cll_error ?: olck->ols_state >= OLS_GRANTED ? 0 : CLO_WAIT;
1303 }
1304
1305 /**
1306  * An implementation of cl_lock_operations::clo_use() method that pins cached
1307  * lock.
1308  */
1309 static int osc_lock_use(const struct lu_env *env,
1310                         const struct cl_lock_slice *slice)
1311 {
1312         struct osc_lock *olck = cl2osc_lock(slice);
1313         int rc;
1314
1315         LASSERT(!olck->ols_hold);
1316
1317         /*
1318          * Atomically check for LDLM_FL_CBPENDING and addref a lock if this
1319          * flag is not set. This protects us from a concurrent blocking ast.
1320          */
1321         rc = ldlm_lock_addref_try(&olck->ols_handle, olck->ols_einfo.ei_mode);
1322         if (rc == 0) {
1323                 olck->ols_hold = 1;
1324                 olck->ols_state = OLS_GRANTED;
1325         } else {
1326                 struct cl_lock *lock;
1327
1328                 /*
1329                  * Lock is being cancelled somewhere within
1330                  * ldlm_handle_bl_callback(): LDLM_FL_CBPENDING is already
1331                  * set, but osc_ldlm_blocking_ast() hasn't yet acquired
1332                  * cl_lock mutex.
1333                  */
1334                 lock = slice->cls_lock;
1335                 LASSERT(lock->cll_state == CLS_INTRANSIT);
1336                 LASSERT(lock->cll_users > 0);
1337                 /* set a flag for osc_dlm_blocking_ast0() to signal the
1338                  * lock.*/
1339                 olck->ols_ast_wait = 1;
1340                 rc = CLO_WAIT;
1341         }
1342         return rc;
1343 }
1344
1345 static int osc_lock_flush(struct osc_lock *ols, int discard)
1346 {
1347         struct cl_lock       *lock  = ols->ols_cl.cls_lock;
1348         struct cl_env_nest    nest;
1349         struct lu_env        *env;
1350         int result = 0;
1351         ENTRY;
1352
1353         env = cl_env_nested_get(&nest);
1354         if (!IS_ERR(env)) {
1355                 struct osc_object    *obj   = cl2osc(ols->ols_cl.cls_obj);
1356                 struct cl_lock_descr *descr = &lock->cll_descr;
1357                 int rc = 0;
1358
1359                 if (descr->cld_mode >= CLM_WRITE) {
1360                         result = osc_cache_writeback_range(env, obj,
1361                                         descr->cld_start, descr->cld_end,
1362                                         1, discard);
1363                         LDLM_DEBUG(ols->ols_lock,
1364                                 "lock %p: %d pages were %s.\n", lock, result,
1365                                 discard ? "discarded" : "written");
1366                         if (result > 0)
1367                                 result = 0;
1368                 }
1369
1370                 rc = osc_lock_discard_pages(env, ols);
1371                 if (result == 0 && rc < 0)
1372                         result = rc;
1373
1374                 cl_env_nested_put(&nest, env);
1375         } else
1376                 result = PTR_ERR(env);
1377         if (result == 0) {
1378                 ols->ols_flush = 1;
1379                 LINVRNT(!osc_lock_has_pages(ols));
1380         }
1381         RETURN(result);
1382 }
1383
1384 /**
1385  * Implements cl_lock_operations::clo_cancel() method for osc layer. This is
1386  * called (as part of cl_lock_cancel()) when lock is canceled either voluntary
1387  * (LRU pressure, early cancellation, umount, etc.) or due to the conflict
1388  * with some other lock some where in the cluster. This function does the
1389  * following:
1390  *
1391  *     - invalidates all pages protected by this lock (after sending dirty
1392  *       ones to the server, as necessary);
1393  *
1394  *     - decref's underlying ldlm lock;
1395  *
1396  *     - cancels ldlm lock (ldlm_cli_cancel()).
1397  */
1398 static void osc_lock_cancel(const struct lu_env *env,
1399                             const struct cl_lock_slice *slice)
1400 {
1401         struct cl_lock   *lock    = slice->cls_lock;
1402         struct osc_lock  *olck    = cl2osc_lock(slice);
1403         struct ldlm_lock *dlmlock = olck->ols_lock;
1404
1405         LASSERT(cl_lock_is_mutexed(lock));
1406         LINVRNT(osc_lock_invariant(olck));
1407
1408         if (dlmlock != NULL) {
1409                 bool do_cancel;
1410                 int  result = 0;
1411
1412                 if (olck->ols_state >= OLS_GRANTED)
1413                         result = osc_lock_flush(olck,
1414                                 ldlm_is_discard_data(dlmlock));
1415                 osc_lock_unhold(olck);
1416
1417                 lock_res_and_lock(dlmlock);
1418                 /* Now that we're the only user of dlm read/write reference,
1419                  * mostly the ->l_readers + ->l_writers should be zero.
1420                  * However, there is a corner case.
1421                  * See b=18829 for details.*/
1422                 do_cancel = (dlmlock->l_readers == 0 &&
1423                              dlmlock->l_writers == 0);
1424                 ldlm_set_cbpending(dlmlock);
1425                 unlock_res_and_lock(dlmlock);
1426                 if (do_cancel)
1427                         result = ldlm_cli_cancel(&olck->ols_handle, LCF_ASYNC);
1428                 if (result < 0)
1429                         CL_LOCK_DEBUG(D_ERROR, env, lock,
1430                                       "lock %p cancel failure with error(%d)\n",
1431                                       lock, result);
1432         }
1433         olck->ols_state = OLS_CANCELLED;
1434         olck->ols_flags &= ~LDLM_FL_LVB_READY;
1435         osc_lock_detach(env, olck);
1436 }
1437
1438 #ifdef CONFIG_LUSTRE_DEBUG_EXPENSIVE_CHECK
1439 static int check_cb(const struct lu_env *env, struct cl_io *io,
1440                     struct osc_page *ops, void *cbdata)
1441 {
1442         struct cl_lock *lock = cbdata;
1443
1444         if (lock->cll_descr.cld_mode == CLM_READ) {
1445                 struct cl_lock *tmp;
1446                 tmp = cl_lock_at_pgoff(env, lock->cll_descr.cld_obj,
1447                                        osc_index(ops), lock, 1, 0);
1448                 if (tmp != NULL) {
1449                         cl_lock_put(env, tmp);
1450                         return CLP_GANG_OKAY;
1451                 }
1452         }
1453
1454         CL_LOCK_DEBUG(D_ERROR, env, lock, "still has pages\n");
1455         CL_PAGE_DEBUG(D_ERROR, env, ops->ops_cl.cpl_page, "\n");
1456         return CLP_GANG_ABORT;
1457 }
1458
1459 /**
1460  * Returns true iff there are pages under \a olck not protected by other
1461  * locks.
1462  */
1463 static bool osc_lock_has_pages(struct osc_lock *olck)
1464 {
1465         struct cl_lock       *lock;
1466         struct cl_lock_descr *descr;
1467         struct cl_object     *obj;
1468         struct osc_object    *oob;
1469         struct cl_env_nest    nest;
1470         struct cl_io         *io;
1471         struct lu_env        *env;
1472         bool                     has_pages;
1473         int                      rc;
1474
1475         env = cl_env_nested_get(&nest);
1476         if (IS_ERR(env))
1477                 return false;
1478
1479         obj   = olck->ols_cl.cls_obj;
1480         oob   = cl2osc(obj);
1481         io    = &oob->oo_debug_io;
1482         lock  = olck->ols_cl.cls_lock;
1483         descr = &lock->cll_descr;
1484
1485         mutex_lock(&oob->oo_debug_mutex);
1486         io->ci_obj = cl_object_top(obj);
1487         io->ci_ignore_layout = 1;
1488         rc = cl_io_init(env, io, CIT_MISC, io->ci_obj);
1489         if (rc != 0)
1490                 GOTO(out, has_pages = false);
1491
1492         do {
1493                 rc = osc_page_gang_lookup(env, io, oob,
1494                                           descr->cld_start, descr->cld_end,
1495                                           check_cb, (void *)lock);
1496                 if (rc == CLP_GANG_ABORT)
1497                         break;
1498                 if (rc == CLP_GANG_RESCHED)
1499                         cond_resched();
1500         } while (rc != CLP_GANG_OKAY);
1501         has_pages = (rc == CLP_GANG_ABORT);
1502 out:
1503         cl_io_fini(env, io);
1504         mutex_unlock(&oob->oo_debug_mutex);
1505         cl_env_nested_put(&nest, env);
1506
1507         return has_pages;
1508 }
1509 #else
1510 static bool osc_lock_has_pages(struct osc_lock *olck)
1511 {
1512         return false;
1513 }
1514 #endif /* CONFIG_LUSTRE_DEBUG_EXPENSIVE_CHECK */
1515
1516 static void osc_lock_delete(const struct lu_env *env,
1517                             const struct cl_lock_slice *slice)
1518 {
1519         struct osc_lock *olck;
1520
1521         olck = cl2osc_lock(slice);
1522         if (olck->ols_glimpse) {
1523                 LASSERT(!olck->ols_hold);
1524                 LASSERT(!olck->ols_lock);
1525                 return;
1526         }
1527
1528         LINVRNT(osc_lock_invariant(olck));
1529         LINVRNT(!osc_lock_has_pages(olck));
1530
1531         osc_lock_unhold(olck);
1532         osc_lock_detach(env, olck);
1533 }
1534
1535 /**
1536  * Implements cl_lock_operations::clo_state() method for osc layer.
1537  *
1538  * Maintains osc_lock::ols_owner field.
1539  *
1540  * This assumes that lock always enters CLS_HELD (from some other state) in
1541  * the same IO context as one that requested the lock. This should not be a
1542  * problem, because context is by definition shared by all activity pertaining
1543  * to the same high-level IO.
1544  */
1545 static void osc_lock_state(const struct lu_env *env,
1546                            const struct cl_lock_slice *slice,
1547                            enum cl_lock_state state)
1548 {
1549         struct osc_lock *lock = cl2osc_lock(slice);
1550
1551         /*
1552          * XXX multiple io contexts can use the lock at the same time.
1553          */
1554         LINVRNT(osc_lock_invariant(lock));
1555         if (state == CLS_HELD && slice->cls_lock->cll_state != CLS_HELD) {
1556                 struct osc_io *oio = osc_env_io(env);
1557
1558                 LASSERT(lock->ols_owner == NULL);
1559                 lock->ols_owner = oio;
1560         } else if (state != CLS_HELD)
1561                 lock->ols_owner = NULL;
1562 }
1563
1564 static int osc_lock_print(const struct lu_env *env, void *cookie,
1565                           lu_printer_t p, const struct cl_lock_slice *slice)
1566 {
1567         struct osc_lock *lock = cl2osc_lock(slice);
1568
1569         /*
1570          * XXX print ldlm lock and einfo properly.
1571          */
1572         (*p)(env, cookie, "%p "LPX64" "LPX64" %d %p ",
1573              lock->ols_lock, lock->ols_flags, lock->ols_handle.cookie,
1574              lock->ols_state, lock->ols_owner);
1575         osc_lvb_print(env, cookie, p, &lock->ols_lvb);
1576         return 0;
1577 }
1578
1579 static int osc_lock_fits_into(const struct lu_env *env,
1580                               const struct cl_lock_slice *slice,
1581                               const struct cl_lock_descr *need,
1582                               const struct cl_io *io)
1583 {
1584         struct osc_lock *ols = cl2osc_lock(slice);
1585
1586         if (need->cld_enq_flags & CEF_NEVER)
1587                 return 0;
1588
1589         if (ols->ols_state >= OLS_CANCELLED)
1590                 return 0;
1591
1592         if (need->cld_mode == CLM_PHANTOM) {
1593                 if (ols->ols_agl)
1594                         return !(ols->ols_state > OLS_RELEASED);
1595
1596                 /*
1597                  * Note: the QUEUED lock can't be matched here, otherwise
1598                  * it might cause the deadlocks.
1599                  * In read_process,
1600                  * P1: enqueued read lock, create sublock1
1601                  * P2: enqueued write lock, create sublock2(conflicted
1602                  *     with sublock1).
1603                  * P1: Grant read lock.
1604                  * P1: enqueued glimpse lock(with holding sublock1_read),
1605                  *     matched with sublock2, waiting sublock2 to be granted.
1606                  *     But sublock2 can not be granted, because P1
1607                  *     will not release sublock1. Bang!
1608                  */
1609                 if (ols->ols_state < OLS_GRANTED ||
1610                     ols->ols_state > OLS_RELEASED)
1611                         return 0;
1612         } else if (need->cld_enq_flags & CEF_MUST) {
1613                 /*
1614                  * If the lock hasn't ever enqueued, it can't be matched
1615                  * because enqueue process brings in many information
1616                  * which can be used to determine things such as lockless,
1617                  * CEF_MUST, etc.
1618                  */
1619                 if (ols->ols_state < OLS_UPCALL_RECEIVED &&
1620                     ols->ols_locklessable)
1621                         return 0;
1622         }
1623         return 1;
1624 }
1625
1626 static const struct cl_lock_operations osc_lock_ops = {
1627         .clo_fini    = osc_lock_fini,
1628         .clo_enqueue = osc_lock_enqueue,
1629         .clo_wait    = osc_lock_wait,
1630         .clo_unuse   = osc_lock_unuse,
1631         .clo_use     = osc_lock_use,
1632         .clo_delete  = osc_lock_delete,
1633         .clo_state   = osc_lock_state,
1634         .clo_cancel  = osc_lock_cancel,
1635         .clo_print   = osc_lock_print,
1636         .clo_fits_into = osc_lock_fits_into,
1637 };
1638
1639 static int osc_lock_lockless_unuse(const struct lu_env *env,
1640                                    const struct cl_lock_slice *slice)
1641 {
1642         struct osc_lock *ols = cl2osc_lock(slice);
1643         struct cl_lock *lock = slice->cls_lock;
1644
1645         LASSERT(ols->ols_state == OLS_GRANTED);
1646         LINVRNT(osc_lock_invariant(ols));
1647
1648         cl_lock_cancel(env, lock);
1649         cl_lock_delete(env, lock);
1650         return 0;
1651 }
1652
1653 static void osc_lock_lockless_cancel(const struct lu_env *env,
1654                                      const struct cl_lock_slice *slice)
1655 {
1656         struct osc_lock   *ols  = cl2osc_lock(slice);
1657         int result;
1658
1659         result = osc_lock_flush(ols, 0);
1660         if (result)
1661                 CERROR("Pages for lockless lock %p were not purged(%d)\n",
1662                        ols, result);
1663         ols->ols_state = OLS_CANCELLED;
1664 }
1665
1666 static int osc_lock_lockless_wait(const struct lu_env *env,
1667                                   const struct cl_lock_slice *slice)
1668 {
1669         struct osc_lock *olck = cl2osc_lock(slice);
1670         struct cl_lock  *lock = olck->ols_cl.cls_lock;
1671
1672         LINVRNT(osc_lock_invariant(olck));
1673         LASSERT(olck->ols_state >= OLS_UPCALL_RECEIVED);
1674
1675         return lock->cll_error;
1676 }
1677
1678 static void osc_lock_lockless_state(const struct lu_env *env,
1679                                     const struct cl_lock_slice *slice,
1680                                     enum cl_lock_state state)
1681 {
1682         struct osc_lock *lock = cl2osc_lock(slice);
1683
1684         LINVRNT(osc_lock_invariant(lock));
1685         if (state == CLS_HELD) {
1686                 struct osc_io *oio  = osc_env_io(env);
1687
1688                 LASSERT(ergo(lock->ols_owner, lock->ols_owner == oio));
1689                 lock->ols_owner = oio;
1690
1691                 /* set the io to be lockless if this lock is for io's
1692                  * host object */
1693                 if (cl_object_same(oio->oi_cl.cis_obj, slice->cls_obj))
1694                         oio->oi_lockless = 1;
1695         }
1696 }
1697
1698 static int osc_lock_lockless_fits_into(const struct lu_env *env,
1699                                        const struct cl_lock_slice *slice,
1700                                        const struct cl_lock_descr *need,
1701                                        const struct cl_io *io)
1702 {
1703         struct osc_lock *lock = cl2osc_lock(slice);
1704
1705         if (!(need->cld_enq_flags & CEF_NEVER))
1706                 return 0;
1707
1708         /* lockless lock should only be used by its owning io. b22147 */
1709         return (lock->ols_owner == osc_env_io(env));
1710 }
1711
1712 static const struct cl_lock_operations osc_lock_lockless_ops = {
1713         .clo_fini      = osc_lock_fini,
1714         .clo_enqueue   = osc_lock_enqueue,
1715         .clo_wait      = osc_lock_lockless_wait,
1716         .clo_unuse     = osc_lock_lockless_unuse,
1717         .clo_state     = osc_lock_lockless_state,
1718         .clo_fits_into = osc_lock_lockless_fits_into,
1719         .clo_cancel    = osc_lock_lockless_cancel,
1720         .clo_print     = osc_lock_print
1721 };
1722
1723 int osc_lock_init(const struct lu_env *env,
1724                   struct cl_object *obj, struct cl_lock *lock,
1725                   const struct cl_io *unused)
1726 {
1727         struct osc_lock *clk;
1728         int result;
1729
1730         OBD_SLAB_ALLOC_PTR_GFP(clk, osc_lock_kmem, GFP_NOFS);
1731         if (clk != NULL) {
1732                 __u32 enqflags = lock->cll_descr.cld_enq_flags;
1733
1734                 osc_lock_build_einfo(env, lock, clk, &clk->ols_einfo);
1735                 clk->ols_state = OLS_NEW;
1736
1737                 clk->ols_flags = osc_enq2ldlm_flags(enqflags);
1738                 clk->ols_agl = !!(enqflags & CEF_AGL);
1739                 if (clk->ols_agl)
1740                         clk->ols_flags |= LDLM_FL_BLOCK_NOWAIT;
1741                 if (clk->ols_flags & LDLM_FL_HAS_INTENT)
1742                         clk->ols_glimpse = 1;
1743
1744                 cl_lock_slice_add(lock, &clk->ols_cl, obj, &osc_lock_ops);
1745
1746                 if (!(enqflags & CEF_MUST))
1747                         /* try to convert this lock to a lockless lock */
1748                         osc_lock_to_lockless(env, clk, (enqflags & CEF_NEVER));
1749                 if (clk->ols_locklessable && !(enqflags & CEF_DISCARD_DATA))
1750                         clk->ols_flags |= LDLM_FL_DENY_ON_CONTENTION;
1751
1752                 LDLM_DEBUG_NOLOCK("lock %p, osc lock %p, flags "LPX64"\n",
1753                                 lock, clk, clk->ols_flags);
1754
1755                 result = 0;
1756         } else
1757                 result = -ENOMEM;
1758         return result;
1759 }
1760
1761 /** @} osc */