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, 2017, 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 a 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         /* Because reprocess_queue zeroes flags and uses it to return
 290          * LDLM_FL_LOCK_CHANGED, we must check for the NO_EXPANSION flag
 291          * in the lock flags rather than the 'flags' argument */
 292         if (likely(!(lock->l_flags & LDLM_FL_NO_EXPANSION))) {
 293                 ldlm_extent_internal_policy_granted(lock, &new_ex);
 294                 ldlm_extent_internal_policy_waiting(lock, &new_ex);
 295         } else {
 296                 LDLM_DEBUG(lock, "Not expanding manually requested lock.\n");
 297                 new_ex.start = lock->l_policy_data.l_extent.start;
 298                 new_ex.end = lock->l_policy_data.l_extent.end;
 299                 /* In case the request is not on correct boundaries, we call
 300                  * fixup. (normally called in ldlm_extent_internal_policy_*) */
 301                 ldlm_extent_internal_policy_fixup(lock, &new_ex, 0);
 302         }
 303
 304         if (!ldlm_extent_equal(&new_ex, &lock->l_policy_data.l_extent)) {
 305                 *flags |= LDLM_FL_LOCK_CHANGED;
 306                 lock->l_policy_data.l_extent.start = new_ex.start;
 307                 lock->l_policy_data.l_extent.end = new_ex.end;
 308         }
 309 }
 310
 311 static int ldlm_check_contention(struct ldlm_lock *lock, int contended_locks)
 312 {
 313         struct ldlm_resource *res = lock->l_resource;
 314         time64_t now = ktime_get_seconds();
 315
 316         if (OBD_FAIL_CHECK(OBD_FAIL_LDLM_SET_CONTENTION))
 317                 return 1;
 318
 319         CDEBUG(D_DLMTRACE, "contended locks = %d\n", contended_locks);
 320         if (contended_locks > ldlm_res_to_ns(res)->ns_contended_locks)
 321                 res->lr_contention_time = now;
 322
 323         return now < res->lr_contention_time +
 324                      ldlm_res_to_ns(res)->ns_contention_time;
 325 }
 326
 327 struct ldlm_extent_compat_args {
 328         struct list_head *work_list;
 329         struct ldlm_lock *lock;
 330         enum ldlm_mode mode;
 331         int *locks;
 332         int *compat;
 333 };
 334
 335 static enum interval_iter ldlm_extent_compat_cb(struct interval_node *n,
 336                                                 void *data)
 337 {
 338         struct ldlm_extent_compat_args *priv = data;
 339         struct ldlm_interval *node = to_ldlm_interval(n);
 340         struct ldlm_extent *extent;
 341         struct list_head *work_list = priv->work_list;
 342         struct ldlm_lock *lock, *enq = priv->lock;
 343         enum ldlm_mode mode = priv->mode;
 344         int count = 0;
 345         ENTRY;
 346
 347         LASSERT(!list_empty(&node->li_group));
 348
 349         list_for_each_entry(lock, &node->li_group, l_sl_policy) {
 350                 /* interval tree is for granted lock */
 351                 LASSERTF(mode == lock->l_granted_mode,
 352                          "mode = %s, lock->l_granted_mode = %s\n",
 353                          ldlm_lockname[mode],
 354                          ldlm_lockname[lock->l_granted_mode]);
 355                 count++;
 356                 if (lock->l_blocking_ast &&
 357                     lock->l_granted_mode != LCK_GROUP)
 358                         ldlm_add_ast_work_item(lock, enq, work_list);
 359         }
 360
 361         /* don't count conflicting glimpse locks */
 362         extent = ldlm_interval_extent(node);
 363         if (!(mode == LCK_PR &&
 364             extent->start == 0 && extent->end == OBD_OBJECT_EOF))
 365                 *priv->locks += count;
 366
 367         if (priv->compat)
 368                 *priv->compat = 0;
 369
 370         RETURN(INTERVAL_ITER_CONT);
 371 }
 372
 373 /**
 374  * Determine if the lock is compatible with all locks on the queue.
 375  *
 376  * If \a work_list is provided, conflicting locks are linked there.
 377  * If \a work_list is not provided, we exit this function on first conflict.
 378  *
 379  * \retval 0 if the lock is not compatible
 380  * \retval 1 if the lock is compatible
 381  * \retval 2 if \a req is a group lock and it is compatible and requires
 382  *           no further checking
 383  * \retval negative error, such as EWOULDBLOCK for group locks
 384  */
 385 static int
 386 ldlm_extent_compat_queue(struct list_head *queue, struct ldlm_lock *req,
 387                          __u64 *flags, enum ldlm_error *err,
 388                          struct list_head *work_list, int *contended_locks)
 389 {
 390         struct ldlm_resource *res = req->l_resource;
 391         enum ldlm_mode req_mode = req->l_req_mode;
 392         __u64 req_start = req->l_req_extent.start;
 393         __u64 req_end = req->l_req_extent.end;
 394         struct ldlm_lock *lock;
 395         int check_contention;
 396         int compat = 1;
 397         int scan = 0;
 398         ENTRY;
 399
 400         lockmode_verify(req_mode);
 401
 402         /* Using interval tree for granted lock */
 403         if (queue == &res->lr_granted) {
 404                 struct ldlm_interval_tree *tree;
 405                 struct ldlm_extent_compat_args data = {.work_list = work_list,
 406                                                .lock = req,
 407                                                .locks = contended_locks,
 408                                                .compat = &compat };
 409                 struct interval_node_extent ex = { .start = req_start,
 410                                                    .end = req_end };
 411                 int idx, rc;
 412
 413                 for (idx = 0; idx < LCK_MODE_NUM; idx++) {
 414                         tree = &res->lr_itree[idx];
 415                         if (tree->lit_root == NULL) /* empty tree, skipped */
 416                                 continue;
 417
 418                         data.mode = tree->lit_mode;
 419                         if (lockmode_compat(req_mode, tree->lit_mode)) {
 420                                 struct ldlm_interval *node;
 421                                 struct ldlm_extent *extent;
 422
 423                                 if (req_mode != LCK_GROUP)
 424                                         continue;
 425
 426                                 /* group lock, grant it immediately if
 427                                  * compatible */
 428                                 node = to_ldlm_interval(tree->lit_root);
 429                                 extent = ldlm_interval_extent(node);
 430                                 if (req->l_policy_data.l_extent.gid ==
 431                                     extent->gid)
 432                                         RETURN(2);
 433                         }
 434
 435                         if (tree->lit_mode == LCK_GROUP) {
 436                                 if (*flags & (LDLM_FL_BLOCK_NOWAIT |
 437                                               LDLM_FL_SPECULATIVE)) {
 438                                         compat = -EWOULDBLOCK;
 439                                         goto destroylock;
 440                                 }
 441
 442                                 *flags |= LDLM_FL_NO_TIMEOUT;
 443                                 if (!work_list)
 444                                         RETURN(0);
 445
 446                                 /* if work list is not NULL,add all
 447                                    locks in the tree to work list */
 448                                 compat = 0;
 449                                 interval_iterate(tree->lit_root,
 450                                                  ldlm_extent_compat_cb, &data);
 451                                 continue;
 452                         }
 453
 454                         /* We've found a potentially blocking lock, check
 455                          * compatibility.  This handles locks other than GROUP
 456                          * locks, which are handled separately above.
 457                          *
 458                          * Locks with FL_SPECULATIVE are asynchronous requests
 459                          * which must never wait behind another lock, so they
 460                          * fail if any conflicting lock is found. */
 461                         if (!work_list || (*flags & LDLM_FL_SPECULATIVE)) {
 462                                 rc = interval_is_overlapped(tree->lit_root,
 463                                                             &ex);
 464                                 if (rc) {
 465                                         if (!work_list) {
 466                                                 RETURN(0);
 467                                         } else {
 468                                                 compat = -EWOULDBLOCK;
 469                                                 goto destroylock;
 470                                         }
 471                                 }
 472                         } else {
 473                                 interval_search(tree->lit_root, &ex,
 474                                                 ldlm_extent_compat_cb, &data);
 475                                 if (!list_empty(work_list) && compat)
 476                                         compat = 0;
 477                         }
 478                 }
 479         } else { /* for waiting queue */
 480                 list_for_each_entry(lock, queue, l_res_link) {
 481                         check_contention = 1;
 482
 483                         /* We stop walking the queue if we hit ourselves so
 484                          * we don't take conflicting locks enqueued after us
 485                          * into account, or we'd wait forever. */
 486                         if (req == lock)
 487                                 break;
 488
 489                         if (unlikely(scan)) {
 490                                 /* We only get here if we are queuing GROUP lock
 491                                    and met some incompatible one. The main idea of this
 492                                    code is to insert GROUP lock past compatible GROUP
 493                                    lock in the waiting queue or if there is not any,
 494                                    then in front of first non-GROUP lock */
 495                                 if (lock->l_req_mode != LCK_GROUP) {
 496                                         /* Ok, we hit non-GROUP lock, there should
 497                                          * be no more GROUP locks later on, queue in
 498                                          * front of first non-GROUP lock */
 499
 500                                         ldlm_resource_insert_lock_after(lock, req);
 501                                         list_del_init(&lock->l_res_link);
 502                                         ldlm_resource_insert_lock_after(req, lock);
 503                                         compat = 0;
 504                                         break;
 505                                 }
 506                                 if (req->l_policy_data.l_extent.gid ==
 507                                     lock->l_policy_data.l_extent.gid) {
 508                                         /* found it */
 509                                         ldlm_resource_insert_lock_after(lock, req);
 510                                         compat = 0;
 511                                         break;
 512                                 }
 513                                 continue;
 514                         }
 515
 516                         /* locks are compatible, overlap doesn't matter */
 517                         if (lockmode_compat(lock->l_req_mode, req_mode)) {
 518                                 if (req_mode == LCK_PR &&
 519                                     ((lock->l_policy_data.l_extent.start <=
 520                                       req->l_policy_data.l_extent.start) &&
 521                                      (lock->l_policy_data.l_extent.end >=
 522                                       req->l_policy_data.l_extent.end))) {
 523                                         /* If we met a PR lock just like us or
 524                                            wider, and nobody down the list
 525                                            conflicted with it, that means we
 526                                            can skip processing of the rest of
 527                                            the list and safely place ourselves
 528                                            at the end of the list, or grant
 529                                            (dependent if we met an conflicting
 530                                            locks before in the list).  In case
 531                                            of 1st enqueue only we continue
 532                                            traversing if there is something
 533                                            conflicting down the list because
 534                                            we need to make sure that something
 535                                            is marked as AST_SENT as well, in
 536                                            cse of empy worklist we would exit
 537                                            on first conflict met. */
 538                                         /* There IS a case where such flag is
 539                                            not set for a lock, yet it blocks
 540                                            something. Luckily for us this is
 541                                            only during destroy, so lock is
 542                                            exclusive. So here we are safe */
 543                                         if (!ldlm_is_ast_sent(lock))
 544                                                 RETURN(compat);
 545                                 }
 546
 547                                 /* non-group locks are compatible, overlap doesn't
 548                                    matter */
 549                                 if (likely(req_mode != LCK_GROUP))
 550                                         continue;
 551
 552                                 /* If we are trying to get a GROUP lock and there is
 553                                    another one of this kind, we need to compare gid */
 554                                 if (req->l_policy_data.l_extent.gid ==
 555                                     lock->l_policy_data.l_extent.gid) {
 556                                         /* If existing lock with matched gid is granted,
 557                                            we grant new one too. */
 558                                         if (lock->l_req_mode == lock->l_granted_mode)
 559                                                 RETURN(2);
 560
 561                                         /* Otherwise we are scanning queue of waiting
 562                                          * locks and it means current request would
 563                                          * block along with existing lock (that is
 564                                          * already blocked.
 565                                          * If we are in nonblocking mode - return
 566                                          * immediately */
 567                                         if (*flags & (LDLM_FL_BLOCK_NOWAIT
 568                                                       | LDLM_FL_SPECULATIVE)) {
 569                                                 compat = -EWOULDBLOCK;
 570                                                 goto destroylock;
 571                                         }
 572                                         /* If this group lock is compatible with another
 573                                          * group lock on the waiting list, they must be
 574                                          * together in the list, so they can be granted
 575                                          * at the same time.  Otherwise the later lock
 576                                          * can get stuck behind another, incompatible,
 577                                          * lock. */
 578                                         ldlm_resource_insert_lock_after(lock, req);
 579                                         /* Because 'lock' is not granted, we can stop
 580                                          * processing this queue and return immediately.
 581                                          * There is no need to check the rest of the
 582                                          * list. */
 583                                         RETURN(0);
 584                                 }
 585                         }
 586
 587                         if (unlikely(req_mode == LCK_GROUP &&
 588                                      (lock->l_req_mode != lock->l_granted_mode))) {
 589                                 scan = 1;
 590                                 compat = 0;
 591                                 if (lock->l_req_mode != LCK_GROUP) {
 592                                         /* Ok, we hit non-GROUP lock, there should be no
 593                                            more GROUP locks later on, queue in front of
 594                                            first non-GROUP lock */
 595
 596                                         ldlm_resource_insert_lock_after(lock, req);
 597                                         list_del_init(&lock->l_res_link);
 598                                         ldlm_resource_insert_lock_after(req, lock);
 599                                         break;
 600                                 }
 601                                 if (req->l_policy_data.l_extent.gid ==
 602                                     lock->l_policy_data.l_extent.gid) {
 603                                         /* found it */
 604                                         ldlm_resource_insert_lock_after(lock, req);
 605                                         break;
 606                                 }
 607                                 continue;
 608                         }
 609
 610                         if (unlikely(lock->l_req_mode == LCK_GROUP)) {
 611                                 /* If compared lock is GROUP, then requested is
 612                                  * PR/PW so this is not compatible; extent
 613                                  * range does not matter */
 614                                 if (*flags & (LDLM_FL_BLOCK_NOWAIT
 615                                               | LDLM_FL_SPECULATIVE)) {
 616                                         compat = -EWOULDBLOCK;
 617                                         goto destroylock;
 618                                 } else {
 619                                         *flags |= LDLM_FL_NO_TIMEOUT;
 620                                 }
 621                         } else if (lock->l_policy_data.l_extent.end < req_start ||
 622                                    lock->l_policy_data.l_extent.start > req_end) {
 623                                 /* if a non group lock doesn't overlap skip it */
 624                                 continue;
 625                         } else if (lock->l_req_extent.end < req_start ||
 626                                    lock->l_req_extent.start > req_end) {
 627                                 /* false contention, the requests doesn't really overlap */
 628                                 check_contention = 0;
 629                         }
 630
 631                         if (!work_list)
 632                                 RETURN(0);
 633
 634                         if (*flags & LDLM_FL_SPECULATIVE) {
 635                                 compat = -EWOULDBLOCK;
 636                                 goto destroylock;
 637                         }
 638
 639                         /* don't count conflicting glimpse locks */
 640                         if (lock->l_req_mode == LCK_PR &&
 641                             lock->l_policy_data.l_extent.start == 0 &&
 642                             lock->l_policy_data.l_extent.end == OBD_OBJECT_EOF)
 643                                 check_contention = 0;
 644
 645                         *contended_locks += check_contention;
 646
 647                         compat = 0;
 648                         if (lock->l_blocking_ast &&
 649                             lock->l_req_mode != LCK_GROUP)
 650                                 ldlm_add_ast_work_item(lock, req, work_list);
 651                 }
 652         }
 653
 654         if (ldlm_check_contention(req, *contended_locks) &&
 655             compat == 0 &&
 656             (*flags & LDLM_FL_DENY_ON_CONTENTION) &&
 657             req->l_req_mode != LCK_GROUP &&
 658             req_end - req_start <=
 659             ldlm_res_to_ns(req->l_resource)->ns_max_nolock_size)
 660                 GOTO(destroylock, compat = -EUSERS);
 661
 662         RETURN(compat);
 663 destroylock:
 664         list_del_init(&req->l_res_link);
 665         ldlm_lock_destroy_nolock(req);
 666         *err = compat;
 667         RETURN(compat);
 668 }
 669
 670 /**
 671  * This function refresh eviction timer for cancelled lock.
 672  * \param[in] lock              ldlm lock for refresh
 673  * \param[in] arg               ldlm prolong arguments, timeout, export, extent
 674  *                              and counter are used
 675  */
 676 void ldlm_lock_prolong_one(struct ldlm_lock *lock,
 677                            struct ldlm_prolong_args *arg)
 678 {
 679         time64_t timeout;
 680
 681         OBD_FAIL_TIMEOUT(OBD_FAIL_LDLM_PROLONG_PAUSE, 3);
 682
 683         if (arg->lpa_export != lock->l_export ||
 684             lock->l_flags & LDLM_FL_DESTROYED)
 685                 /* ignore unrelated locks */
 686                 return;
 687
 688         arg->lpa_locks_cnt++;
 689
 690         if (!(lock->l_flags & LDLM_FL_AST_SENT))
 691                 /* ignore locks not being cancelled */
 692                 return;
 693
 694         /* We are in the middle of the process - BL AST is sent, CANCEL
 695          * is ahead. Take half of BL AT + IO AT process time.
 696          */
 697         timeout = arg->lpa_timeout + (ldlm_bl_timeout(lock) >> 1);
 698
 699         LDLM_DEBUG(lock, "refreshed to %llds.\n", timeout);
 700
 701         arg->lpa_blocks_cnt++;
 702
 703         /* OK. this is a possible lock the user holds doing I/O
 704          * let's refresh eviction timer for it.
 705          */
 706         ldlm_refresh_waiting_lock(lock, timeout);
 707 }
 708 EXPORT_SYMBOL(ldlm_lock_prolong_one);
 709
 710 static enum interval_iter ldlm_resource_prolong_cb(struct interval_node *n,
 711                                                    void *data)
 712 {
 713         struct ldlm_prolong_args *arg = data;
 714         struct ldlm_interval *node = to_ldlm_interval(n);
 715         struct ldlm_lock *lock;
 716
 717         ENTRY;
 718
 719         LASSERT(!list_empty(&node->li_group));
 720
 721         list_for_each_entry(lock, &node->li_group, l_sl_policy) {
 722                 ldlm_lock_prolong_one(lock, arg);
 723         }
 724
 725         RETURN(INTERVAL_ITER_CONT);
 726 }
 727
 728 /**
 729  * Walk through granted tree and prolong locks if they overlaps extent.
 730  *
 731  * \param[in] arg               prolong args
 732  */
 733 void ldlm_resource_prolong(struct ldlm_prolong_args *arg)
 734 {
 735         struct ldlm_interval_tree *tree;
 736         struct ldlm_resource *res;
 737         struct interval_node_extent ex = { .start = arg->lpa_extent.start,
 738                                            .end = arg->lpa_extent.end };
 739         int idx;
 740
 741         ENTRY;
 742
 743         res = ldlm_resource_get(arg->lpa_export->exp_obd->obd_namespace, NULL,
 744                                 &arg->lpa_resid, LDLM_EXTENT, 0);
 745         if (IS_ERR(res)) {
 746                 CDEBUG(D_DLMTRACE, "Failed to get resource for resid %llu/%llu\n",
 747                        arg->lpa_resid.name[0], arg->lpa_resid.name[1]);
 748                 RETURN_EXIT;
 749         }
 750
 751         lock_res(res);
 752         for (idx = 0; idx < LCK_MODE_NUM; idx++) {
 753                 tree = &res->lr_itree[idx];
 754                 if (tree->lit_root == NULL) /* empty tree, skipped */
 755                         continue;
 756
 757                 /* There is no possibility to check for the groupID
 758                  * so all the group locks are considered as valid
 759                  * here, especially because the client is supposed
 760                  * to check it has such a lock before sending an RPC.
 761                  */
 762                 if (!(tree->lit_mode & arg->lpa_mode))
 763                         continue;
 764
 765                 interval_search(tree->lit_root, &ex,
 766                                 ldlm_resource_prolong_cb, arg);
 767         }
 768
 769         unlock_res(res);
 770         ldlm_resource_putref(res);
 771
 772         EXIT;
 773 }
 774 EXPORT_SYMBOL(ldlm_resource_prolong);
 775
 776 /**
 777  * Process a granting attempt for extent lock.
 778  * Must be called with ns lock held.
 779  *
 780  * This function looks for any conflicts for \a lock in the granted or
 781  * waiting queues. The lock is granted if no conflicts are found in
 782  * either queue.
 783  */
 784 int ldlm_process_extent_lock(struct ldlm_lock *lock, __u64 *flags,
 785                              enum ldlm_process_intention intention,
 786                              enum ldlm_error *err, struct list_head *work_list)
 787 {
 788         struct ldlm_resource *res = lock->l_resource;
 789         int rc, rc2;
 790         int contended_locks = 0;
 791         struct list_head *grant_work = intention == LDLM_PROCESS_ENQUEUE ?
 792                                                         NULL : work_list;
 793         ENTRY;
 794
 795         LASSERT(lock->l_granted_mode != lock->l_req_mode);
 796         LASSERT(!(*flags & LDLM_FL_DENY_ON_CONTENTION) ||
 797                 !ldlm_is_ast_discard_data(lock));
 798         check_res_locked(res);
 799         *err = ELDLM_OK;
 800
 801         if (intention == LDLM_PROCESS_RESCAN) {
 802                 /* Careful observers will note that we don't handle -EWOULDBLOCK
 803                  * here, but it's ok for a non-obvious reason -- compat_queue
 804                  * can only return -EWOULDBLOCK if (flags & BLOCK_NOWAIT |
 805                  * SPECULATIVE). flags should always be zero here, and if that
 806                  * ever stops being true, we want to find out. */
 807                 LASSERT(*flags == 0);
 808                 rc = ldlm_extent_compat_queue(&res->lr_granted, lock, flags,
 809                                               err, NULL, &contended_locks);
 810                 if (rc == 1) {
 811                         rc = ldlm_extent_compat_queue(&res->lr_waiting, lock,
 812                                                       flags, err, NULL,
 813                                                       &contended_locks);
 814                 }
 815                 if (rc == 0)
 816                         RETURN(LDLM_ITER_STOP);
 817
 818                 ldlm_resource_unlink_lock(lock);
 819
 820                 if (!OBD_FAIL_CHECK(OBD_FAIL_LDLM_CANCEL_EVICT_RACE))
 821                         ldlm_extent_policy(res, lock, flags);
 822                 ldlm_grant_lock(lock, grant_work);
 823                 RETURN(LDLM_ITER_CONTINUE);
 824         }
 825
 826         contended_locks = 0;
 827         rc = ldlm_extent_compat_queue(&res->lr_granted, lock, flags, err,
 828                                       work_list, &contended_locks);
 829         if (rc < 0)
 830                 GOTO(out_rpc_list, rc);
 831
 832         rc2 = 0;
 833         if (rc != 2) {
 834                 rc2 = ldlm_extent_compat_queue(&res->lr_waiting, lock,
 835                                                flags, err, work_list,
 836                                                &contended_locks);
 837                 if (rc2 < 0)
 838                         GOTO(out_rpc_list, rc = rc2);
 839         }
 840
 841         if (rc + rc2 == 2) {
 842                 ldlm_extent_policy(res, lock, flags);
 843                 ldlm_resource_unlink_lock(lock);
 844                 ldlm_grant_lock(lock, grant_work);
 845         } else {
 846                 /* Adding LDLM_FL_NO_TIMEOUT flag to granted lock to
 847                  * force client to wait for the lock endlessly once
 848                  * the lock is enqueued -bzzz */
 849                 *flags |= LDLM_FL_NO_TIMEOUT;
 850         }
 851         rc = LDLM_ITER_CONTINUE;
 852
 853 out_rpc_list:
 854         RETURN(rc);
 855 }
 856 #endif /* HAVE_SERVER_SUPPORT */
 857
 858 struct ldlm_kms_shift_args {
 859         __u64   old_kms;
 860         __u64   kms;
 861         bool    complete;
 862 };
 863
 864 /* Callback for interval_iterate functions, used by ldlm_extent_shift_Kms */
 865 static enum interval_iter ldlm_kms_shift_cb(struct interval_node *n,
 866                                             void *args)
 867 {
 868         struct ldlm_kms_shift_args *arg = args;
 869         struct ldlm_interval *node = to_ldlm_interval(n);
 870         struct ldlm_lock *tmplock;
 871         struct ldlm_lock *lock = NULL;
 872
 873         ENTRY;
 874
 875         /* Since all locks in an interval have the same extent, we can just
 876          * use the first lock without kms_ignore set. */
 877         list_for_each_entry(tmplock, &node->li_group, l_sl_policy) {
 878                 if (ldlm_is_kms_ignore(tmplock))
 879                         continue;
 880
 881                 lock = tmplock;
 882
 883                 break;
 884         }
 885
 886         /* No locks in this interval without kms_ignore set */
 887         if (!lock)
 888                 RETURN(INTERVAL_ITER_CONT);
 889
 890         /* If we find a lock with a greater or equal kms, we are not the
 891          * highest lock (or we share that distinction with another lock), and
 892          * don't need to update KMS.  Return old_kms and stop looking. */
 893         if (lock->l_policy_data.l_extent.end >= arg->old_kms) {
 894                 arg->kms = arg->old_kms;
 895                 arg->complete = true;
 896                 RETURN(INTERVAL_ITER_STOP);
 897         }
 898
 899         if (lock->l_policy_data.l_extent.end + 1 > arg->kms)
 900                 arg->kms = lock->l_policy_data.l_extent.end + 1;
 901
 902         /* Since interval_iterate_reverse starts with the highest lock and
 903          * works down, for PW locks, we only need to check if we should update
 904          * the kms, then stop walking the tree.  PR locks are not exclusive, so
 905          * the highest start does not imply the highest end and we must
 906          * continue. (Only one group lock is allowed per resource, so this is
 907          * irrelevant for group locks.)*/
 908         if (lock->l_granted_mode == LCK_PW)
 909                 RETURN(INTERVAL_ITER_STOP);
 910         else
 911                 RETURN(INTERVAL_ITER_CONT);
 912 }
 913
 914 /* When a lock is cancelled by a client, the KMS may undergo change if this
 915  * is the "highest lock".  This function returns the new KMS value, updating
 916  * it only if we were the highest lock.
 917  *
 918  * Caller must hold lr_lock already.
 919  *
 920  * NB: A lock on [x,y] protects a KMS of up to y + 1 bytes! */
 921 __u64 ldlm_extent_shift_kms(struct ldlm_lock *lock, __u64 old_kms)
 922 {
 923         struct ldlm_resource *res = lock->l_resource;
 924         struct ldlm_interval_tree *tree;
 925         struct ldlm_kms_shift_args args;
 926         int idx = 0;
 927
 928         ENTRY;
 929
 930         args.old_kms = old_kms;
 931         args.kms = 0;
 932         args.complete = false;
 933
 934         /* don't let another thread in ldlm_extent_shift_kms race in
 935          * just after we finish and take our lock into account in its
 936          * calculation of the kms */
 937         ldlm_set_kms_ignore(lock);
 938
 939         /* We iterate over the lock trees, looking for the largest kms smaller
 940          * than the current one. */
 941         for (idx = 0; idx < LCK_MODE_NUM; idx++) {
 942                 tree = &res->lr_itree[idx];
 943
 944                 /* If our already known kms is >= than the highest 'end' in
 945                  * this tree, we don't need to check this tree, because
 946                  * the kms from a tree can be lower than in_max_high (due to
 947                  * kms_ignore), but it can never be higher. */
 948                 if (!tree->lit_root || args.kms >= tree->lit_root->in_max_high)
 949                         continue;
 950
 951                 interval_iterate_reverse(tree->lit_root, ldlm_kms_shift_cb,
 952                                          &args);
 953
 954                 /* this tells us we're not the highest lock, so we don't need
 955                  * to check the remaining trees */
 956                 if (args.complete)
 957                         break;
 958         }
 959
 960         LASSERTF(args.kms <= args.old_kms, "kms %llu old_kms %llu\n", args.kms,
 961                  args.old_kms);
 962
 963         RETURN(args.kms);
 964 }
 965 EXPORT_SYMBOL(ldlm_extent_shift_kms);
 966
 967 struct kmem_cache *ldlm_interval_slab;
 968 struct ldlm_interval *ldlm_interval_alloc(struct ldlm_lock *lock)
 969 {
 970         struct ldlm_interval *node;
 971         ENTRY;
 972
 973         LASSERT(lock->l_resource->lr_type == LDLM_EXTENT);
 974         OBD_SLAB_ALLOC_PTR_GFP(node, ldlm_interval_slab, GFP_NOFS);
 975         if (node == NULL)
 976                 RETURN(NULL);
 977
 978         INIT_LIST_HEAD(&node->li_group);
 979         ldlm_interval_attach(node, lock);
 980         RETURN(node);
 981 }
 982
 983 void ldlm_interval_free(struct ldlm_interval *node)
 984 {
 985         if (node) {
 986                 LASSERT(list_empty(&node->li_group));
 987                 LASSERT(!interval_is_intree(&node->li_node));
 988                 OBD_SLAB_FREE(node, ldlm_interval_slab, sizeof(*node));
 989         }
 990 }
 991
 992 /* interval tree, for LDLM_EXTENT. */
 993 void ldlm_interval_attach(struct ldlm_interval *n,
 994                           struct ldlm_lock *l)
 995 {
 996         LASSERT(l->l_tree_node == NULL);
 997         LASSERT(l->l_resource->lr_type == LDLM_EXTENT);
 998
 999         list_add_tail(&l->l_sl_policy, &n->li_group);
1000         l->l_tree_node = n;
1001 }
1002
1003 struct ldlm_interval *ldlm_interval_detach(struct ldlm_lock *l)
1004 {
1005         struct ldlm_interval *n = l->l_tree_node;
1006
1007         if (n == NULL)
1008                 return NULL;
1009
1010         LASSERT(!list_empty(&n->li_group));
1011         l->l_tree_node = NULL;
1012         list_del_init(&l->l_sl_policy);
1013
1014         return list_empty(&n->li_group) ? n : NULL;
1015 }
1016
1017 static inline int ldlm_mode_to_index(enum ldlm_mode mode)
1018 {
1019         int index;
1020
1021         LASSERT(mode != 0);
1022         LASSERT(is_power_of_2(mode));
1023         for (index = -1; mode != 0; index++, mode >>= 1)
1024                 /* do nothing */;
1025         LASSERT(index < LCK_MODE_NUM);
1026         return index;
1027 }
1028
1029 /** Add newly granted lock into interval tree for the resource. */
1030 void ldlm_extent_add_lock(struct ldlm_resource *res,
1031                           struct ldlm_lock *lock)
1032 {
1033         struct interval_node *found, **root;
1034         struct ldlm_interval *node;
1035         struct ldlm_extent *extent;
1036         int idx, rc;
1037
1038         LASSERT(lock->l_granted_mode == lock->l_req_mode);
1039
1040         node = lock->l_tree_node;
1041         LASSERT(node != NULL);
1042         LASSERT(!interval_is_intree(&node->li_node));
1043
1044         idx = ldlm_mode_to_index(lock->l_granted_mode);
1045         LASSERT(lock->l_granted_mode == 1 << idx);
1046         LASSERT(lock->l_granted_mode == res->lr_itree[idx].lit_mode);
1047
1048         /* node extent initialize */
1049         extent = &lock->l_policy_data.l_extent;
1050
1051         rc = interval_set(&node->li_node, extent->start, extent->end);
1052         LASSERT(!rc);
1053
1054         root = &res->lr_itree[idx].lit_root;
1055         found = interval_insert(&node->li_node, root);
1056         if (found) { /* The policy group found. */
1057                 struct ldlm_interval *tmp = ldlm_interval_detach(lock);
1058                 LASSERT(tmp != NULL);
1059                 ldlm_interval_free(tmp);
1060                 ldlm_interval_attach(to_ldlm_interval(found), lock);
1061         }
1062         res->lr_itree[idx].lit_size++;
1063
1064         /* even though we use interval tree to manage the extent lock, we also
1065          * add the locks into grant list, for debug purpose, .. */
1066         ldlm_resource_add_lock(res, &res->lr_granted, lock);
1067
1068         if (OBD_FAIL_CHECK(OBD_FAIL_LDLM_GRANT_CHECK)) {
1069                 struct ldlm_lock *lck;
1070
1071                 list_for_each_entry_reverse(lck, &res->lr_granted,
1072                                             l_res_link) {
1073                         if (lck == lock)
1074                                 continue;
1075                         if (lockmode_compat(lck->l_granted_mode,
1076                                             lock->l_granted_mode))
1077                                 continue;
1078                         if (ldlm_extent_overlap(&lck->l_req_extent,
1079                                                 &lock->l_req_extent)) {
1080                                 CDEBUG(D_ERROR, "granting conflicting lock %p "
1081                                                 "%p\n", lck, lock);
1082                                 ldlm_resource_dump(D_ERROR, res);
1083                                 LBUG();
1084                         }
1085                 }
1086         }
1087 }
1088
1089 /** Remove cancelled lock from resource interval tree. */
1090 void ldlm_extent_unlink_lock(struct ldlm_lock *lock)
1091 {
1092         struct ldlm_resource *res = lock->l_resource;
1093         struct ldlm_interval *node = lock->l_tree_node;
1094         struct ldlm_interval_tree *tree;
1095         int idx;
1096
1097         if (!node || !interval_is_intree(&node->li_node)) /* duplicate unlink */
1098                 return;
1099
1100         idx = ldlm_mode_to_index(lock->l_granted_mode);
1101         LASSERT(lock->l_granted_mode == 1 << idx);
1102         tree = &res->lr_itree[idx];
1103
1104         LASSERT(tree->lit_root != NULL); /* assure the tree is not null */
1105
1106         tree->lit_size--;
1107         node = ldlm_interval_detach(lock);
1108         if (node) {
1109                 interval_erase(&node->li_node, &tree->lit_root);
1110                 ldlm_interval_free(node);
1111         }
1112 }
1113
1114 void ldlm_extent_policy_wire_to_local(const union ldlm_wire_policy_data *wpolicy,
1115                                       union ldlm_policy_data *lpolicy)
1116 {
1117         lpolicy->l_extent.start = wpolicy->l_extent.start;
1118         lpolicy->l_extent.end = wpolicy->l_extent.end;
1119         lpolicy->l_extent.gid = wpolicy->l_extent.gid;
1120 }
1121
1122 void ldlm_extent_policy_local_to_wire(const union ldlm_policy_data *lpolicy,
1123                                       union ldlm_wire_policy_data *wpolicy)
1124 {
1125         memset(wpolicy, 0, sizeof(*wpolicy));
1126         wpolicy->l_extent.start = lpolicy->l_extent.start;
1127         wpolicy->l_extent.end = lpolicy->l_extent.end;
1128         wpolicy->l_extent.gid = lpolicy->l_extent.gid;
1129 }
1130