lustre/ldlm/ldlm_extent.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.gnu.org/licenses/gpl-2.0.html
  19  *
  20  * GPL HEADER END
  21  */
  22 /*
  23  * Copyright (c) 2002, 2010, Oracle and/or its affiliates. All rights reserved.
  24  * Use is subject to license terms.
  25  *
  26  * Copyright (c) 2010, 2013, Intel Corporation.
  27  */
  28 /*
  29  * This file is part of Lustre, http://www.lustre.org/
  30  * Lustre is a trademark of Sun Microsystems, Inc.
  31  *
  32  * lustre/ldlm/ldlm_extent.c
  33  *
  34  * Author: Peter Braam <braam@clusterfs.com>
  35  * Author: Phil Schwan <phil@clusterfs.com>
  36  */
  37
  38 /**
  39  * This file contains implementation of EXTENT lock type
  40  *
  41  * EXTENT lock type is for locking a contiguous range of values, represented
  42  * by 64-bit starting and ending offsets (inclusive). There are several extent
  43  * lock modes, some of which may be mutually incompatible. Extent locks are
  44  * considered incompatible if their modes are incompatible and their extents
  45  * intersect.  See the lock mode compatibility matrix in lustre_dlm.h.
  46  */
  47
  48 #define DEBUG_SUBSYSTEM S_LDLM
  49
  50 #include <libcfs/libcfs.h>
  51 #include <lustre_dlm.h>
  52 #include <obd_support.h>
  53 #include <obd.h>
  54 #include <obd_class.h>
  55 #include <lustre_lib.h>
  56
  57 #include "ldlm_internal.h"
  58
  59 #ifdef HAVE_SERVER_SUPPORT
  60 # define LDLM_MAX_GROWN_EXTENT (32 * 1024 * 1024 - 1)
  61
  62 /**
  63  * Fix up the ldlm_extent after expanding it.
  64  *
  65  * After expansion has been done, we might still want to do certain adjusting
  66  * based on overall contention of the resource and the like to avoid granting
  67  * overly wide locks.
  68  */
  69 static void ldlm_extent_internal_policy_fixup(struct ldlm_lock *req,
  70                                               struct ldlm_extent *new_ex,
  71                                               int conflicting)
  72 {
  73         enum ldlm_mode req_mode = req->l_req_mode;
  74         __u64 req_start = req->l_req_extent.start;
  75         __u64 req_end = req->l_req_extent.end;
  76         __u64 req_align, mask;
  77
  78         if (conflicting > 32 && (req_mode == LCK_PW || req_mode == LCK_CW)) {
  79                 if (req_end < req_start + LDLM_MAX_GROWN_EXTENT)
  80                         new_ex->end = min(req_start + LDLM_MAX_GROWN_EXTENT,
  81                                           new_ex->end);
  82         }
  83
  84         if (new_ex->start == 0 && new_ex->end == OBD_OBJECT_EOF) {
  85                 EXIT;
  86                 return;
  87         }
  88
  89         /* we need to ensure that the lock extent is properly aligned to what
  90          * the client requested. Also we need to make sure it's also server
  91          * page size aligned otherwise a server page can be covered by two
  92          * write locks. */
  93         mask = PAGE_SIZE;
  94         req_align = (req_end + 1) | req_start;
  95         if (req_align != 0 && (req_align & (mask - 1)) == 0) {
  96                 while ((req_align & mask) == 0)
  97                         mask <<= 1;
  98         }
  99         mask -= 1;
 100         /* We can only shrink the lock, not grow it.
 101          * This should never cause lock to be smaller than requested,
 102          * since requested lock was already aligned on these boundaries. */
 103         new_ex->start = ((new_ex->start - 1) | mask) + 1;
 104         new_ex->end = ((new_ex->end + 1) & ~mask) - 1;
 105         LASSERTF(new_ex->start <= req_start,
 106                  "mask %#llx grant start %llu req start %llu\n",
 107                  mask, new_ex->start, req_start);
 108         LASSERTF(new_ex->end >= req_end,
 109                  "mask %#llx grant end %llu req end %llu\n",
 110                  mask, new_ex->end, req_end);
 111 }
 112
 113 /**
 114  * Return the maximum extent that:
 115  * - contains the requested extent
 116  * - does not overlap existing conflicting extents outside the requested one
 117  *
 118  * This allows clients to request a small required extent range, but if there
 119  * is no contention on the lock the full lock can be granted to the client.
 120  * This avoids the need for many smaller lock requests to be granted in the
 121  * common (uncontended) case.
 122  *
 123  * Use interval tree to expand the lock extent for granted lock.
 124  */
 125 static void ldlm_extent_internal_policy_granted(struct ldlm_lock *req,
 126                                                 struct ldlm_extent *new_ex)
 127 {
 128         struct ldlm_resource *res = req->l_resource;
 129         enum ldlm_mode req_mode = req->l_req_mode;
 130         __u64 req_start = req->l_req_extent.start;
 131         __u64 req_end = req->l_req_extent.end;
 132         struct ldlm_interval_tree *tree;
 133         struct interval_node_extent limiter = {
 134                 .start  = new_ex->start,
 135                 .end    = new_ex->end,
 136         };
 137         int conflicting = 0;
 138         int idx;
 139         ENTRY;
 140
 141         lockmode_verify(req_mode);
 142
 143         /* Using interval tree to handle the LDLM extent granted locks. */
 144         for (idx = 0; idx < LCK_MODE_NUM; idx++) {
 145                 struct interval_node_extent ext = {
 146                         .start  = req_start,
 147                         .end    = req_end,
 148                 };
 149
 150                 tree = &res->lr_itree[idx];
 151                 if (lockmode_compat(tree->lit_mode, req_mode))
 152                         continue;
 153
 154                 conflicting += tree->lit_size;
 155                 if (conflicting > 4)
 156                         limiter.start = req_start;
 157
 158                 if (interval_is_overlapped(tree->lit_root, &ext))
 159                         CDEBUG(D_INFO,
 160                                "req_mode = %d, tree->lit_mode = %d, "
 161                                "tree->lit_size = %d\n",
 162                                req_mode, tree->lit_mode, tree->lit_size);
 163                 interval_expand(tree->lit_root, &ext, &limiter);
 164                 limiter.start = max(limiter.start, ext.start);
 165                 limiter.end = min(limiter.end, ext.end);
 166                 if (limiter.start == req_start && limiter.end == req_end)
 167                         break;
 168         }
 169
 170         new_ex->start = limiter.start;
 171         new_ex->end = limiter.end;
 172         LASSERT(new_ex->start <= req_start);
 173         LASSERT(new_ex->end >= req_end);
 174
 175         ldlm_extent_internal_policy_fixup(req, new_ex, conflicting);
 176         EXIT;
 177 }
 178
 179 /* The purpose of this function is to return:
 180  * - the maximum extent
 181  * - containing the requested extent
 182  * - and not overlapping existing conflicting extents outside the requested one
 183  */
 184 static void
 185 ldlm_extent_internal_policy_waiting(struct ldlm_lock *req,
 186                                     struct ldlm_extent *new_ex)
 187 {
 188         struct ldlm_resource *res = req->l_resource;
 189         enum ldlm_mode req_mode = req->l_req_mode;
 190         __u64 req_start = req->l_req_extent.start;
 191         __u64 req_end = req->l_req_extent.end;
 192         struct ldlm_lock *lock;
 193         int conflicting = 0;
 194         ENTRY;
 195
 196         lockmode_verify(req_mode);
 197
 198         /* for waiting locks */
 199         list_for_each_entry(lock, &res->lr_waiting, l_res_link) {
 200                 struct ldlm_extent *l_extent = &lock->l_policy_data.l_extent;
 201
 202                 /* We already hit the minimum requested size, search no more */
 203                 if (new_ex->start == req_start && new_ex->end == req_end) {
 204                         EXIT;
 205                         return;
 206                 }
 207
 208                 /* Don't conflict with ourselves */
 209                 if (req == lock)
 210                         continue;
 211
 212                 /* Locks are compatible, overlap doesn't matter */
 213                 /* Until bug 20 is fixed, try to avoid granting overlapping
 214                  * locks on one client (they take a long time to cancel) */
 215                 if (lockmode_compat(lock->l_req_mode, req_mode) &&
 216                     lock->l_export != req->l_export)
 217                         continue;
 218
 219                 /* If this is a high-traffic lock, don't grow downwards at all
 220                  * or grow upwards too much */
 221                 ++conflicting;
 222                 if (conflicting > 4)
 223                         new_ex->start = req_start;
 224
 225                 /* If lock doesn't overlap new_ex, skip it. */
 226                 if (!ldlm_extent_overlap(l_extent, new_ex))
 227                         continue;
 228
 229                 /* Locks conflicting in requested extents and we can't satisfy
 230                  * both locks, so ignore it.  Either we will ping-pong this
 231                  * extent (we would regardless of what extent we granted) or
 232                  * lock is unused and it shouldn't limit our extent growth. */
 233                 if (ldlm_extent_overlap(&lock->l_req_extent,&req->l_req_extent))
 234                         continue;
 235
 236                 /* We grow extents downwards only as far as they don't overlap
 237                  * with already-granted locks, on the assumption that clients
 238                  * will be writing beyond the initial requested end and would
 239                  * then need to enqueue a new lock beyond previous request.
 240                  * l_req_extent->end strictly < req_start, checked above. */
 241                 if (l_extent->start < req_start && new_ex->start != req_start) {
 242                         if (l_extent->end >= req_start)
 243                                 new_ex->start = req_start;
 244                         else
 245                                 new_ex->start = min(l_extent->end+1, req_start);
 246                 }
 247
 248                 /* If we need to cancel this lock anyways because our request
 249                  * overlaps the granted lock, we grow up to its requested
 250                  * extent start instead of limiting this extent, assuming that
 251                  * clients are writing forwards and the lock had over grown
 252                  * its extent downwards before we enqueued our request. */
 253                 if (l_extent->end > req_end) {
 254                         if (l_extent->start <= req_end)
 255                                 new_ex->end = max(lock->l_req_extent.start - 1,
 256                                                   req_end);
 257                         else
 258                                 new_ex->end = max(l_extent->start - 1, req_end);
 259                 }
 260         }
 261
 262         ldlm_extent_internal_policy_fixup(req, new_ex, conflicting);
 263         EXIT;
 264 }
 265
 266
 267 /* In order to determine the largest possible extent we can grant, we need
 268  * to scan all of the queues. */
 269 static void ldlm_extent_policy(struct ldlm_resource *res,
 270                                struct ldlm_lock *lock, __u64 *flags)
 271 {
 272         struct ldlm_extent new_ex = { .start = 0, .end = OBD_OBJECT_EOF };
 273
 274         if (lock->l_export == NULL)
 275                 /*
 276                  * this is local lock taken by server (e.g., as a part of
 277                  * OST-side locking, or unlink handling). Expansion doesn't
 278                  * make a lot of sense for local locks, because they are
 279                  * dropped immediately on operation completion and would only
 280                  * conflict with other threads.
 281                  */
 282                 return;
 283
 284         if (lock->l_policy_data.l_extent.start == 0 &&
 285             lock->l_policy_data.l_extent.end == OBD_OBJECT_EOF)
 286                 /* fast-path whole file locks */
 287                 return;
 288
 289         ldlm_extent_internal_policy_granted(lock, &new_ex);
 290         ldlm_extent_internal_policy_waiting(lock, &new_ex);
 291
 292         if (new_ex.start != lock->l_policy_data.l_extent.start ||
 293             new_ex.end != lock->l_policy_data.l_extent.end) {
 294                 *flags |= LDLM_FL_LOCK_CHANGED;
 295                 lock->l_policy_data.l_extent.start = new_ex.start;
 296                 lock->l_policy_data.l_extent.end = new_ex.end;
 297         }
 298 }
 299
 300 static int ldlm_check_contention(struct ldlm_lock *lock, int contended_locks)
 301 {
 302         struct ldlm_resource *res = lock->l_resource;
 303         cfs_time_t now = cfs_time_current();
 304
 305         if (OBD_FAIL_CHECK(OBD_FAIL_LDLM_SET_CONTENTION))
 306                 return 1;
 307
 308         CDEBUG(D_DLMTRACE, "contended locks = %d\n", contended_locks);
 309         if (contended_locks > ldlm_res_to_ns(res)->ns_contended_locks)
 310                 res->lr_contention_time = now;
 311         return cfs_time_before(now, cfs_time_add(res->lr_contention_time,
 312                 cfs_time_seconds(ldlm_res_to_ns(res)->ns_contention_time)));
 313 }
 314
 315 struct ldlm_extent_compat_args {
 316         struct list_head *work_list;
 317         struct ldlm_lock *lock;
 318         enum ldlm_mode mode;
 319         int *locks;
 320         int *compat;
 321 };
 322
 323 static enum interval_iter ldlm_extent_compat_cb(struct interval_node *n,
 324                                                 void *data)
 325 {
 326         struct ldlm_extent_compat_args *priv = data;
 327         struct ldlm_interval *node = to_ldlm_interval(n);
 328         struct ldlm_extent *extent;
 329         struct list_head *work_list = priv->work_list;
 330         struct ldlm_lock *lock, *enq = priv->lock;
 331         enum ldlm_mode mode = priv->mode;
 332         int count = 0;
 333         ENTRY;
 334
 335         LASSERT(!list_empty(&node->li_group));
 336
 337         list_for_each_entry(lock, &node->li_group, l_sl_policy) {
 338                 /* interval tree is for granted lock */
 339                 LASSERTF(mode == lock->l_granted_mode,
 340                          "mode = %s, lock->l_granted_mode = %s\n",
 341                          ldlm_lockname[mode],
 342                          ldlm_lockname[lock->l_granted_mode]);
 343                 count++;
 344                 if (lock->l_blocking_ast &&
 345                     lock->l_granted_mode != LCK_GROUP)
 346                         ldlm_add_ast_work_item(lock, enq, work_list);
 347         }
 348
 349         /* don't count conflicting glimpse locks */
 350         extent = ldlm_interval_extent(node);
 351         if (!(mode == LCK_PR &&
 352             extent->start == 0 && extent->end == OBD_OBJECT_EOF))
 353                 *priv->locks += count;
 354
 355         if (priv->compat)
 356                 *priv->compat = 0;
 357
 358         RETURN(INTERVAL_ITER_CONT);
 359 }
 360
 361 /**
 362  * Determine if the lock is compatible with all locks on the queue.
 363  *
 364  * If \a work_list is provided, conflicting locks are linked there.
 365  * If \a work_list is not provided, we exit this function on first conflict.
 366  *
 367  * \retval 0 if the lock is not compatible
 368  * \retval 1 if the lock is compatible
 369  * \retval 2 if \a req is a group lock and it is compatible and requires
 370  *           no further checking
 371  * \retval negative error, such as EWOULDBLOCK for group locks
 372  */
 373 static int
 374 ldlm_extent_compat_queue(struct list_head *queue, struct ldlm_lock *req,
 375                          __u64 *flags, enum ldlm_error *err,
 376                          struct list_head *work_list, int *contended_locks)
 377 {
 378         struct ldlm_resource *res = req->l_resource;
 379         enum ldlm_mode req_mode = req->l_req_mode;
 380         __u64 req_start = req->l_req_extent.start;
 381         __u64 req_end = req->l_req_extent.end;
 382         struct ldlm_lock *lock;
 383         int check_contention;
 384         int compat = 1;
 385         int scan = 0;
 386         ENTRY;
 387
 388         lockmode_verify(req_mode);
 389
 390         /* Using interval tree for granted lock */
 391         if (queue == &res->lr_granted) {
 392                 struct ldlm_interval_tree *tree;
 393                 struct ldlm_extent_compat_args data = {.work_list = work_list,
 394                                                .lock = req,
 395                                                .locks = contended_locks,
 396                                                .compat = &compat };
 397                 struct interval_node_extent ex = { .start = req_start,
 398                                                    .end = req_end };
 399                 int idx, rc;
 400
 401                 for (idx = 0; idx < LCK_MODE_NUM; idx++) {
 402                         tree = &res->lr_itree[idx];
 403                         if (tree->lit_root == NULL) /* empty tree, skipped */
 404                                 continue;
 405
 406                         data.mode = tree->lit_mode;
 407                         if (lockmode_compat(req_mode, tree->lit_mode)) {
 408                                 struct ldlm_interval *node;
 409                                 struct ldlm_extent *extent;
 410
 411                                 if (req_mode != LCK_GROUP)
 412                                         continue;
 413
 414                                 /* group lock, grant it immediately if
 415                                  * compatible */
 416                                 node = to_ldlm_interval(tree->lit_root);
 417                                 extent = ldlm_interval_extent(node);
 418                                 if (req->l_policy_data.l_extent.gid ==
 419                                     extent->gid)
 420                                         RETURN(2);
 421                         }
 422
 423                         if (tree->lit_mode == LCK_GROUP) {
 424                                 if (*flags & LDLM_FL_BLOCK_NOWAIT) {
 425                                         compat = -EWOULDBLOCK;
 426                                         goto destroylock;
 427                                 }
 428
 429                                 *flags |= LDLM_FL_NO_TIMEOUT;
 430                                 if (!work_list)
 431                                         RETURN(0);
 432
 433                                 /* if work list is not NULL,add all
 434                                    locks in the tree to work list */
 435                                 compat = 0;
 436                                 interval_iterate(tree->lit_root,
 437                                                  ldlm_extent_compat_cb, &data);
 438                                 continue;
 439                         }
 440
 441                         if (!work_list) {
 442                                 rc = interval_is_overlapped(tree->lit_root,&ex);
 443                                 if (rc)
 444                                         RETURN(0);
 445                         } else {
 446                                 interval_search(tree->lit_root, &ex,
 447                                                 ldlm_extent_compat_cb, &data);
 448                                 if (!list_empty(work_list) && compat)
 449                                         compat = 0;
 450                         }
 451                 }
 452         } else { /* for waiting queue */
 453                 list_for_each_entry(lock, queue, l_res_link) {
 454                         check_contention = 1;
 455
 456                         /* We stop walking the queue if we hit ourselves so
 457                          * we don't take conflicting locks enqueued after us
 458                          * into account, or we'd wait forever. */
 459                         if (req == lock)
 460                                 break;
 461
 462                         if (unlikely(scan)) {
 463                                 /* We only get here if we are queuing GROUP lock
 464                                    and met some incompatible one. The main idea of this
 465                                    code is to insert GROUP lock past compatible GROUP
 466                                    lock in the waiting queue or if there is not any,
 467                                    then in front of first non-GROUP lock */
 468                                 if (lock->l_req_mode != LCK_GROUP) {
 469                                         /* Ok, we hit non-GROUP lock, there should
 470                                          * be no more GROUP locks later on, queue in
 471                                          * front of first non-GROUP lock */
 472
 473                                         ldlm_resource_insert_lock_after(lock, req);
 474                                         list_del_init(&lock->l_res_link);
 475                                         ldlm_resource_insert_lock_after(req, lock);
 476                                         compat = 0;
 477                                         break;
 478                                 }
 479                                 if (req->l_policy_data.l_extent.gid ==
 480                                     lock->l_policy_data.l_extent.gid) {
 481                                         /* found it */
 482                                         ldlm_resource_insert_lock_after(lock, req);
 483                                         compat = 0;
 484                                         break;
 485                                 }
 486                                 continue;
 487                         }
 488
 489                         /* locks are compatible, overlap doesn't matter */
 490                         if (lockmode_compat(lock->l_req_mode, req_mode)) {
 491                                 if (req_mode == LCK_PR &&
 492                                     ((lock->l_policy_data.l_extent.start <=
 493                                       req->l_policy_data.l_extent.start) &&
 494                                      (lock->l_policy_data.l_extent.end >=
 495                                       req->l_policy_data.l_extent.end))) {
 496                                         /* If we met a PR lock just like us or
 497                                            wider, and nobody down the list
 498                                            conflicted with it, that means we
 499                                            can skip processing of the rest of
 500                                            the list and safely place ourselves
 501                                            at the end of the list, or grant
 502                                            (dependent if we met an conflicting
 503                                            locks before in the list).  In case
 504                                            of 1st enqueue only we continue
 505                                            traversing if there is something
 506                                            conflicting down the list because
 507                                            we need to make sure that something
 508                                            is marked as AST_SENT as well, in
 509                                            cse of empy worklist we would exit
 510                                            on first conflict met. */
 511                                         /* There IS a case where such flag is
 512                                            not set for a lock, yet it blocks
 513                                            something. Luckily for us this is
 514                                            only during destroy, so lock is
 515                                            exclusive. So here we are safe */
 516                                         if (!ldlm_is_ast_sent(lock))
 517                                                 RETURN(compat);
 518                                 }
 519
 520                                 /* non-group locks are compatible, overlap doesn't
 521                                    matter */
 522                                 if (likely(req_mode != LCK_GROUP))
 523                                         continue;
 524
 525                                 /* If we are trying to get a GROUP lock and there is
 526                                    another one of this kind, we need to compare gid */
 527                                 if (req->l_policy_data.l_extent.gid ==
 528                                     lock->l_policy_data.l_extent.gid) {
 529                                         /* If existing lock with matched gid is granted,
 530                                            we grant new one too. */
 531                                         if (lock->l_req_mode == lock->l_granted_mode)
 532                                                 RETURN(2);
 533
 534                                         /* Otherwise we are scanning queue of waiting
 535                                          * locks and it means current request would
 536                                          * block along with existing lock (that is
 537                                          * already blocked.
 538                                          * If we are in nonblocking mode - return
 539                                          * immediately */
 540                                         if (*flags & LDLM_FL_BLOCK_NOWAIT) {
 541                                                 compat = -EWOULDBLOCK;
 542                                                 goto destroylock;
 543                                         }
 544                                         /* If this group lock is compatible with another
 545                                          * group lock on the waiting list, they must be
 546                                          * together in the list, so they can be granted
 547                                          * at the same time.  Otherwise the later lock
 548                                          * can get stuck behind another, incompatible,
 549                                          * lock. */
 550                                         ldlm_resource_insert_lock_after(lock, req);
 551                                         /* Because 'lock' is not granted, we can stop
 552                                          * processing this queue and return immediately.
 553                                          * There is no need to check the rest of the
 554                                          * list. */
 555                                         RETURN(0);
 556                                 }
 557                         }
 558
 559                         if (unlikely(req_mode == LCK_GROUP &&
 560                                      (lock->l_req_mode != lock->l_granted_mode))) {
 561                                 scan = 1;
 562                                 compat = 0;
 563                                 if (lock->l_req_mode != LCK_GROUP) {
 564                                         /* Ok, we hit non-GROUP lock, there should be no
 565                                            more GROUP locks later on, queue in front of
 566                                            first non-GROUP lock */
 567
 568                                         ldlm_resource_insert_lock_after(lock, req);
 569                                         list_del_init(&lock->l_res_link);
 570                                         ldlm_resource_insert_lock_after(req, lock);
 571                                         break;
 572                                 }
 573                                 if (req->l_policy_data.l_extent.gid ==
 574                                     lock->l_policy_data.l_extent.gid) {
 575                                         /* found it */
 576                                         ldlm_resource_insert_lock_after(lock, req);
 577                                         break;
 578                                 }
 579                                 continue;
 580                         }
 581
 582                         if (unlikely(lock->l_req_mode == LCK_GROUP)) {
 583                                 /* If compared lock is GROUP, then requested is PR/PW/
 584                                  * so this is not compatible; extent range does not
 585                                  * matter */
 586                                 if (*flags & LDLM_FL_BLOCK_NOWAIT) {
 587                                         compat = -EWOULDBLOCK;
 588                                         goto destroylock;
 589                                 } else {
 590                                         *flags |= LDLM_FL_NO_TIMEOUT;
 591                                 }
 592                         } else if (lock->l_policy_data.l_extent.end < req_start ||
 593                                    lock->l_policy_data.l_extent.start > req_end) {
 594                                 /* if a non group lock doesn't overlap skip it */
 595                                 continue;
 596                         } else if (lock->l_req_extent.end < req_start ||
 597                                    lock->l_req_extent.start > req_end) {
 598                                 /* false contention, the requests doesn't really overlap */
 599                                 check_contention = 0;
 600                         }
 601
 602                         if (!work_list)
 603                                 RETURN(0);
 604
 605                         /* don't count conflicting glimpse locks */
 606                         if (lock->l_req_mode == LCK_PR &&
 607                             lock->l_policy_data.l_extent.start == 0 &&
 608                             lock->l_policy_data.l_extent.end == OBD_OBJECT_EOF)
 609                                 check_contention = 0;
 610
 611                         *contended_locks += check_contention;
 612
 613                         compat = 0;
 614                         if (lock->l_blocking_ast &&
 615                             lock->l_req_mode != LCK_GROUP)
 616                                 ldlm_add_ast_work_item(lock, req, work_list);
 617                 }
 618         }
 619
 620         if (ldlm_check_contention(req, *contended_locks) &&
 621             compat == 0 &&
 622             (*flags & LDLM_FL_DENY_ON_CONTENTION) &&
 623             req->l_req_mode != LCK_GROUP &&
 624             req_end - req_start <=
 625             ldlm_res_to_ns(req->l_resource)->ns_max_nolock_size)
 626                 GOTO(destroylock, compat = -EUSERS);
 627
 628         RETURN(compat);
 629 destroylock:
 630         list_del_init(&req->l_res_link);
 631         ldlm_lock_destroy_nolock(req);
 632         *err = compat;
 633         RETURN(compat);
 634 }
 635
 636 /**
 637  * This function refresh eviction timer for cancelled lock.
 638  * \param[in] lock              ldlm lock for refresh
 639  * \param[in] arg               ldlm prolong arguments, timeout, export, extent
 640  *                              and counter are used
 641  */
 642 void ldlm_lock_prolong_one(struct ldlm_lock *lock,
 643                            struct ldlm_prolong_args *arg)
 644 {
 645         int timeout;
 646
 647         if (arg->lpa_export != lock->l_export ||
 648             lock->l_flags & LDLM_FL_DESTROYED)
 649                 /* ignore unrelated locks */
 650                 return;
 651
 652         arg->lpa_locks_cnt++;
 653
 654         if (!(lock->l_flags & LDLM_FL_AST_SENT))
 655                 /* ignore locks not being cancelled */
 656                 return;
 657
 658         /* We are in the middle of the process - BL AST is sent, CANCEL
 659          * is ahead. Take half of BL AT + IO AT process time.
 660          */
 661         timeout = arg->lpa_timeout + (ldlm_bl_timeout(lock) >> 1);
 662
 663         LDLM_DEBUG(lock, "refreshed to %ds.\n", timeout);
 664
 665         arg->lpa_blocks_cnt++;
 666
 667         /* OK. this is a possible lock the user holds doing I/O
 668          * let's refresh eviction timer for it.
 669          */
 670         ldlm_refresh_waiting_lock(lock, timeout);
 671 }
 672 EXPORT_SYMBOL(ldlm_lock_prolong_one);
 673
 674 static enum interval_iter ldlm_resource_prolong_cb(struct interval_node *n,
 675                                                    void *data)
 676 {
 677         struct ldlm_prolong_args *arg = data;
 678         struct ldlm_interval *node = to_ldlm_interval(n);
 679         struct ldlm_lock *lock;
 680
 681         ENTRY;
 682
 683         LASSERT(!list_empty(&node->li_group));
 684
 685         list_for_each_entry(lock, &node->li_group, l_sl_policy) {
 686                 ldlm_lock_prolong_one(lock, arg);
 687         }
 688
 689         RETURN(INTERVAL_ITER_CONT);
 690 }
 691
 692 /**
 693  * Walk through granted tree and prolong locks if they overlaps extent.
 694  *
 695  * \param[in] arg               prolong args
 696  */
 697 void ldlm_resource_prolong(struct ldlm_prolong_args *arg)
 698 {
 699         struct ldlm_interval_tree *tree;
 700         struct ldlm_resource *res;
 701         struct interval_node_extent ex = { .start = arg->lpa_extent.start,
 702                                            .end = arg->lpa_extent.end };
 703         int idx;
 704
 705         ENTRY;
 706
 707         res = ldlm_resource_get(arg->lpa_export->exp_obd->obd_namespace, NULL,
 708                                 &arg->lpa_resid, LDLM_EXTENT, 0);
 709         if (IS_ERR(res)) {
 710                 CDEBUG(D_DLMTRACE, "Failed to get resource for resid %llu/%llu\n",
 711                        arg->lpa_resid.name[0], arg->lpa_resid.name[1]);
 712                 RETURN_EXIT;
 713         }
 714
 715         lock_res(res);
 716         for (idx = 0; idx < LCK_MODE_NUM; idx++) {
 717                 tree = &res->lr_itree[idx];
 718                 if (tree->lit_root == NULL) /* empty tree, skipped */
 719                         continue;
 720
 721                 /* There is no possibility to check for the groupID
 722                  * so all the group locks are considered as valid
 723                  * here, especially because the client is supposed
 724                  * to check it has such a lock before sending an RPC.
 725                  */
 726                 if (!(tree->lit_mode & arg->lpa_mode))
 727                         continue;
 728
 729                 interval_search(tree->lit_root, &ex,
 730                                 ldlm_resource_prolong_cb, arg);
 731         }
 732
 733         unlock_res(res);
 734         ldlm_resource_putref(res);
 735
 736         EXIT;
 737 }
 738 EXPORT_SYMBOL(ldlm_resource_prolong);
 739
 740 /**
 741  * Process a granting attempt for extent lock.
 742  * Must be called with ns lock held.
 743  *
 744  * This function looks for any conflicts for \a lock in the granted or
 745  * waiting queues. The lock is granted if no conflicts are found in
 746  * either queue.
 747  */
 748 int ldlm_process_extent_lock(struct ldlm_lock *lock, __u64 *flags,
 749                              enum ldlm_process_intention intention,
 750                              enum ldlm_error *err, struct list_head *work_list)
 751 {
 752         struct ldlm_resource *res = lock->l_resource;
 753         struct list_head rpc_list;
 754         int rc, rc2;
 755         int contended_locks = 0;
 756         ENTRY;
 757
 758         LASSERT(lock->l_granted_mode != lock->l_req_mode);
 759         LASSERT(list_empty(&res->lr_converting));
 760         LASSERT(!(*flags & LDLM_FL_DENY_ON_CONTENTION) ||
 761                 !ldlm_is_ast_discard_data(lock));
 762         INIT_LIST_HEAD(&rpc_list);
 763         check_res_locked(res);
 764         *err = ELDLM_OK;
 765
 766         if (intention == LDLM_PROCESS_RESCAN) {
 767                 /* Careful observers will note that we don't handle -EWOULDBLOCK
 768                  * here, but it's ok for a non-obvious reason -- compat_queue
 769                  * can only return -EWOULDBLOCK if (flags & BLOCK_NOWAIT).
 770                  * flags should always be zero here, and if that ever stops
 771                  * being true, we want to find out. */
 772                 LASSERT(*flags == 0);
 773                 rc = ldlm_extent_compat_queue(&res->lr_granted, lock, flags,
 774                                               err, NULL, &contended_locks);
 775                 if (rc == 1) {
 776                         rc = ldlm_extent_compat_queue(&res->lr_waiting, lock,
 777                                                       flags, err, NULL,
 778                                                       &contended_locks);
 779                 }
 780                 if (rc == 0)
 781                         RETURN(LDLM_ITER_STOP);
 782
 783                 ldlm_resource_unlink_lock(lock);
 784
 785                 if (!OBD_FAIL_CHECK(OBD_FAIL_LDLM_CANCEL_EVICT_RACE))
 786                         ldlm_extent_policy(res, lock, flags);
 787                 ldlm_grant_lock(lock, work_list);
 788                 RETURN(LDLM_ITER_CONTINUE);
 789         }
 790
 791         LASSERT((intention == LDLM_PROCESS_ENQUEUE && work_list == NULL) ||
 792                 (intention == LDLM_PROCESS_RECOVERY && work_list != NULL));
 793  restart:
 794         contended_locks = 0;
 795         rc = ldlm_extent_compat_queue(&res->lr_granted, lock, flags, err,
 796                                       &rpc_list, &contended_locks);
 797         if (rc < 0)
 798                 GOTO(out_rpc_list, rc);
 799
 800         rc2 = 0;
 801         if (rc != 2) {
 802                 rc2 = ldlm_extent_compat_queue(&res->lr_waiting, lock,
 803                                                flags, err, &rpc_list,
 804                                                &contended_locks);
 805                 if (rc2 < 0)
 806                         GOTO(out_rpc_list, rc = rc2);
 807         }
 808
 809         if (rc + rc2 != 2) {
 810                 /* Adding LDLM_FL_NO_TIMEOUT flag to granted lock to force
 811                  * client to wait for the lock endlessly once the lock is
 812                  * enqueued -bzzz */
 813                 rc = ldlm_handle_conflict_lock(lock, flags, &rpc_list,
 814                                                LDLM_FL_NO_TIMEOUT);
 815                 if (rc == -ERESTART)
 816                         GOTO(restart, rc);
 817                 *err = rc;
 818         } else {
 819                 ldlm_extent_policy(res, lock, flags);
 820                 ldlm_resource_unlink_lock(lock);
 821                 ldlm_grant_lock(lock, work_list);
 822                 rc = 0;
 823         }
 824
 825 out_rpc_list:
 826         if (!list_empty(&rpc_list)) {
 827                 LASSERT(!ldlm_is_ast_discard_data(lock));
 828                 ldlm_discard_bl_list(&rpc_list);
 829         }
 830         RETURN(rc);
 831 }
 832 #endif /* HAVE_SERVER_SUPPORT */
 833
 834 struct ldlm_kms_shift_args {
 835         __u64   old_kms;
 836         __u64   kms;
 837         bool    complete;
 838 };
 839
 840 /* Callback for interval_iterate functions, used by ldlm_extent_shift_Kms */
 841 static enum interval_iter ldlm_kms_shift_cb(struct interval_node *n,
 842                                             void *args)
 843 {
 844         struct ldlm_kms_shift_args *arg = args;
 845         struct ldlm_interval *node = to_ldlm_interval(n);
 846         struct ldlm_lock *tmplock;
 847         struct ldlm_lock *lock = NULL;
 848
 849         ENTRY;
 850
 851         /* Since all locks in an interval have the same extent, we can just
 852          * use the first lock without kms_ignore set. */
 853         list_for_each_entry(tmplock, &node->li_group, l_sl_policy) {
 854                 if (ldlm_is_kms_ignore(tmplock))
 855                         continue;
 856
 857                 lock = tmplock;
 858
 859                 break;
 860         }
 861
 862         /* No locks in this interval without kms_ignore set */
 863         if (!lock)
 864                 RETURN(INTERVAL_ITER_CONT);
 865
 866         /* If we find a lock with a greater or equal kms, we are not the
 867          * highest lock (or we share that distinction with another lock), and
 868          * don't need to update KMS.  Return old_kms and stop looking. */
 869         if (lock->l_policy_data.l_extent.end >= arg->old_kms) {
 870                 arg->kms = arg->old_kms;
 871                 arg->complete = true;
 872                 RETURN(INTERVAL_ITER_STOP);
 873         }
 874
 875         if (lock->l_policy_data.l_extent.end + 1 > arg->kms)
 876                 arg->kms = lock->l_policy_data.l_extent.end + 1;
 877
 878         /* Since interval_iterate_reverse starts with the highest lock and
 879          * works down, for PW locks, we only need to check if we should update
 880          * the kms, then stop walking the tree.  PR locks are not exclusive, so
 881          * the highest start does not imply the highest end and we must
 882          * continue. (Only one group lock is allowed per resource, so this is
 883          * irrelevant for group locks.)*/
 884         if (lock->l_granted_mode == LCK_PW)
 885                 RETURN(INTERVAL_ITER_STOP);
 886         else
 887                 RETURN(INTERVAL_ITER_CONT);
 888 }
 889
 890 /* When a lock is cancelled by a client, the KMS may undergo change if this
 891  * is the "highest lock".  This function returns the new KMS value, updating
 892  * it only if we were the highest lock.
 893  *
 894  * Caller must hold lr_lock already.
 895  *
 896  * NB: A lock on [x,y] protects a KMS of up to y + 1 bytes! */
 897 __u64 ldlm_extent_shift_kms(struct ldlm_lock *lock, __u64 old_kms)
 898 {
 899         struct ldlm_resource *res = lock->l_resource;
 900         struct ldlm_interval_tree *tree;
 901         struct ldlm_kms_shift_args args;
 902         int idx = 0;
 903
 904         ENTRY;
 905
 906         args.old_kms = old_kms;
 907         args.kms = 0;
 908         args.complete = false;
 909
 910         /* don't let another thread in ldlm_extent_shift_kms race in
 911          * just after we finish and take our lock into account in its
 912          * calculation of the kms */
 913         ldlm_set_kms_ignore(lock);
 914
 915         /* We iterate over the lock trees, looking for the largest kms smaller
 916          * than the current one. */
 917         for (idx = 0; idx < LCK_MODE_NUM; idx++) {
 918                 tree = &res->lr_itree[idx];
 919
 920                 /* If our already known kms is >= than the highest 'end' in
 921                  * this tree, we don't need to check this tree, because
 922                  * the kms from a tree can be lower than in_max_high (due to
 923                  * kms_ignore), but it can never be higher. */
 924                 if (!tree->lit_root || args.kms >= tree->lit_root->in_max_high)
 925                         continue;
 926
 927                 interval_iterate_reverse(tree->lit_root, ldlm_kms_shift_cb,
 928                                          &args);
 929
 930                 /* this tells us we're not the highest lock, so we don't need
 931                  * to check the remaining trees */
 932                 if (args.complete)
 933                         break;
 934         }
 935
 936         LASSERTF(args.kms <= args.old_kms, "kms %llu old_kms %llu\n", args.kms,
 937                  args.old_kms);
 938
 939         RETURN(args.kms);
 940 }
 941 EXPORT_SYMBOL(ldlm_extent_shift_kms);
 942
 943 struct kmem_cache *ldlm_interval_slab;
 944 struct ldlm_interval *ldlm_interval_alloc(struct ldlm_lock *lock)
 945 {
 946         struct ldlm_interval *node;
 947         ENTRY;
 948
 949         LASSERT(lock->l_resource->lr_type == LDLM_EXTENT);
 950         OBD_SLAB_ALLOC_PTR_GFP(node, ldlm_interval_slab, GFP_NOFS);
 951         if (node == NULL)
 952                 RETURN(NULL);
 953
 954         INIT_LIST_HEAD(&node->li_group);
 955         ldlm_interval_attach(node, lock);
 956         RETURN(node);
 957 }
 958
 959 void ldlm_interval_free(struct ldlm_interval *node)
 960 {
 961         if (node) {
 962                 LASSERT(list_empty(&node->li_group));
 963                 LASSERT(!interval_is_intree(&node->li_node));
 964                 OBD_SLAB_FREE(node, ldlm_interval_slab, sizeof(*node));
 965         }
 966 }
 967
 968 /* interval tree, for LDLM_EXTENT. */
 969 void ldlm_interval_attach(struct ldlm_interval *n,
 970                           struct ldlm_lock *l)
 971 {
 972         LASSERT(l->l_tree_node == NULL);
 973         LASSERT(l->l_resource->lr_type == LDLM_EXTENT);
 974
 975         list_add_tail(&l->l_sl_policy, &n->li_group);
 976         l->l_tree_node = n;
 977 }
 978
 979 struct ldlm_interval *ldlm_interval_detach(struct ldlm_lock *l)
 980 {
 981         struct ldlm_interval *n = l->l_tree_node;
 982
 983         if (n == NULL)
 984                 return NULL;
 985
 986         LASSERT(!list_empty(&n->li_group));
 987         l->l_tree_node = NULL;
 988         list_del_init(&l->l_sl_policy);
 989
 990         return list_empty(&n->li_group) ? n : NULL;
 991 }
 992
 993 static inline int ldlm_mode_to_index(enum ldlm_mode mode)
 994 {
 995         int index;
 996
 997         LASSERT(mode != 0);
 998         LASSERT(is_power_of_2(mode));
 999         for (index = -1; mode != 0; index++, mode >>= 1)
1000                 /* do nothing */;
1001         LASSERT(index < LCK_MODE_NUM);
1002         return index;
1003 }
1004
1005 /** Add newly granted lock into interval tree for the resource. */
1006 void ldlm_extent_add_lock(struct ldlm_resource *res,
1007                           struct ldlm_lock *lock)
1008 {
1009         struct interval_node *found, **root;
1010         struct ldlm_interval *node;
1011         struct ldlm_extent *extent;
1012         int idx, rc;
1013
1014         LASSERT(lock->l_granted_mode == lock->l_req_mode);
1015
1016         node = lock->l_tree_node;
1017         LASSERT(node != NULL);
1018         LASSERT(!interval_is_intree(&node->li_node));
1019
1020         idx = ldlm_mode_to_index(lock->l_granted_mode);
1021         LASSERT(lock->l_granted_mode == 1 << idx);
1022         LASSERT(lock->l_granted_mode == res->lr_itree[idx].lit_mode);
1023
1024         /* node extent initialize */
1025         extent = &lock->l_policy_data.l_extent;
1026
1027         rc = interval_set(&node->li_node, extent->start, extent->end);
1028         LASSERT(!rc);
1029
1030         root = &res->lr_itree[idx].lit_root;
1031         found = interval_insert(&node->li_node, root);
1032         if (found) { /* The policy group found. */
1033                 struct ldlm_interval *tmp = ldlm_interval_detach(lock);
1034                 LASSERT(tmp != NULL);
1035                 ldlm_interval_free(tmp);
1036                 ldlm_interval_attach(to_ldlm_interval(found), lock);
1037         }
1038         res->lr_itree[idx].lit_size++;
1039
1040         /* even though we use interval tree to manage the extent lock, we also
1041          * add the locks into grant list, for debug purpose, .. */
1042         ldlm_resource_add_lock(res, &res->lr_granted, lock);
1043
1044         if (OBD_FAIL_CHECK(OBD_FAIL_LDLM_GRANT_CHECK)) {
1045                 struct ldlm_lock *lck;
1046
1047                 list_for_each_entry_reverse(lck, &res->lr_granted,
1048                                             l_res_link) {
1049                         if (lck == lock)
1050                                 continue;
1051                         if (lockmode_compat(lck->l_granted_mode,
1052                                             lock->l_granted_mode))
1053                                 continue;
1054                         if (ldlm_extent_overlap(&lck->l_req_extent,
1055                                                 &lock->l_req_extent)) {
1056                                 CDEBUG(D_ERROR, "granting conflicting lock %p "
1057                                                 "%p\n", lck, lock);
1058                                 ldlm_resource_dump(D_ERROR, res);
1059                                 LBUG();
1060                         }
1061                 }
1062         }
1063 }
1064
1065 /** Remove cancelled lock from resource interval tree. */
1066 void ldlm_extent_unlink_lock(struct ldlm_lock *lock)
1067 {
1068         struct ldlm_resource *res = lock->l_resource;
1069         struct ldlm_interval *node = lock->l_tree_node;
1070         struct ldlm_interval_tree *tree;
1071         int idx;
1072
1073         if (!node || !interval_is_intree(&node->li_node)) /* duplicate unlink */
1074                 return;
1075
1076         idx = ldlm_mode_to_index(lock->l_granted_mode);
1077         LASSERT(lock->l_granted_mode == 1 << idx);
1078         tree = &res->lr_itree[idx];
1079
1080         LASSERT(tree->lit_root != NULL); /* assure the tree is not null */
1081
1082         tree->lit_size--;
1083         node = ldlm_interval_detach(lock);
1084         if (node) {
1085                 interval_erase(&node->li_node, &tree->lit_root);
1086                 ldlm_interval_free(node);
1087         }
1088 }
1089
1090 void ldlm_extent_policy_wire_to_local(const union ldlm_wire_policy_data *wpolicy,
1091                                       union ldlm_policy_data *lpolicy)
1092 {
1093         lpolicy->l_extent.start = wpolicy->l_extent.start;
1094         lpolicy->l_extent.end = wpolicy->l_extent.end;
1095         lpolicy->l_extent.gid = wpolicy->l_extent.gid;
1096 }
1097
1098 void ldlm_extent_policy_local_to_wire(const union ldlm_policy_data *lpolicy,
1099                                       union ldlm_wire_policy_data *wpolicy)
1100 {
1101         memset(wpolicy, 0, sizeof(*wpolicy));
1102         wpolicy->l_extent.start = lpolicy->l_extent.start;
1103         wpolicy->l_extent.end = lpolicy->l_extent.end;
1104         wpolicy->l_extent.gid = lpolicy->l_extent.gid;
1105 }
1106