lustre/obdclass/cl_page.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) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
  24  * Use is subject to license terms.
  25  *
  26  * Copyright (c) 2011, 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  * Client Lustre Page.
  33  *
  34  *   Author: Nikita Danilov <nikita.danilov@sun.com>
  35  *   Author: Jinshan Xiong <jinshan.xiong@intel.com>
  36  */
  37
  38 #define DEBUG_SUBSYSTEM S_CLASS
  39
  40 #include <linux/list.h>
  41 #include <libcfs/libcfs.h>
  42 #include <obd_class.h>
  43 #include <obd_support.h>
  44
  45 #include <cl_object.h>
  46 #include "cl_internal.h"
  47
  48 static void cl_page_delete0(const struct lu_env *env, struct cl_page *pg);
  49 static DEFINE_MUTEX(cl_page_kmem_mutex);
  50
  51 #ifdef LIBCFS_DEBUG
  52 # define PASSERT(env, page, expr)                                       \
  53   do {                                                                    \
  54           if (unlikely(!(expr))) {                                      \
  55                   CL_PAGE_DEBUG(D_ERROR, (env), (page), #expr "\n");    \
  56                   LASSERT(0);                                           \
  57           }                                                             \
  58   } while (0)
  59 #else /* !LIBCFS_DEBUG */
  60 # define PASSERT(env, page, exp) \
  61         ((void)sizeof(env), (void)sizeof(page), (void)sizeof !!(exp))
  62 #endif /* !LIBCFS_DEBUG */
  63
  64 #ifdef CONFIG_LUSTRE_DEBUG_EXPENSIVE_CHECK
  65 # define PINVRNT(env, page, expr)                                       \
  66   do {                                                                    \
  67           if (unlikely(!(expr))) {                                      \
  68                   CL_PAGE_DEBUG(D_ERROR, (env), (page), #expr "\n");    \
  69                   LINVRNT(0);                                           \
  70           }                                                             \
  71   } while (0)
  72 #else /* !CONFIG_LUSTRE_DEBUG_EXPENSIVE_CHECK */
  73 # define PINVRNT(env, page, exp) \
  74          ((void)sizeof(env), (void)sizeof(page), (void)sizeof !!(exp))
  75 #endif /* !CONFIG_LUSTRE_DEBUG_EXPENSIVE_CHECK */
  76
  77 /* Disable page statistic by default due to huge performance penalty. */
  78 static void cs_page_inc(const struct cl_object *obj,
  79                         enum cache_stats_item item)
  80 {
  81 #ifdef CONFIG_DEBUG_PAGESTATE_TRACKING
  82         atomic_inc(&cl_object_site(obj)->cs_pages.cs_stats[item]);
  83 #endif
  84 }
  85
  86 static void cs_page_dec(const struct cl_object *obj,
  87                         enum cache_stats_item item)
  88 {
  89 #ifdef CONFIG_DEBUG_PAGESTATE_TRACKING
  90         atomic_dec(&cl_object_site(obj)->cs_pages.cs_stats[item]);
  91 #endif
  92 }
  93
  94 static void cs_pagestate_inc(const struct cl_object *obj,
  95                              enum cl_page_state state)
  96 {
  97 #ifdef CONFIG_DEBUG_PAGESTATE_TRACKING
  98         atomic_inc(&cl_object_site(obj)->cs_pages_state[state]);
  99 #endif
 100 }
 101
 102 static void cs_pagestate_dec(const struct cl_object *obj,
 103                               enum cl_page_state state)
 104 {
 105 #ifdef CONFIG_DEBUG_PAGESTATE_TRACKING
 106         atomic_dec(&cl_object_site(obj)->cs_pages_state[state]);
 107 #endif
 108 }
 109
 110 /**
 111  * Internal version of cl_page_get().
 112  *
 113  * This function can be used to obtain initial reference to previously
 114  * unreferenced cached object. It can be called only if concurrent page
 115  * reclamation is somehow prevented, e.g., by keeping a lock on a VM page,
 116  * associated with \a page.
 117  *
 118  * Use with care! Not exported.
 119  */
 120 static void cl_page_get_trust(struct cl_page *page)
 121 {
 122         LASSERT(atomic_read(&page->cp_ref) > 0);
 123         atomic_inc(&page->cp_ref);
 124 }
 125
 126 static struct cl_page_slice *
 127 cl_page_slice_get(const struct cl_page *cl_page, int index)
 128 {
 129         if (index < 0 || index >= cl_page->cp_layer_count)
 130                 return NULL;
 131
 132         /* To get the cp_layer_offset values fit under 256 bytes, we
 133          * use the offset beyond the end of struct cl_page.
 134          */
 135         return (struct cl_page_slice *)((char *)cl_page + sizeof(*cl_page) +
 136                                         cl_page->cp_layer_offset[index]);
 137 }
 138
 139 #define cl_page_slice_for_each(cl_page, slice, i)               \
 140         for (i = 0, slice = cl_page_slice_get(cl_page, 0);      \
 141              i < (cl_page)->cp_layer_count;                     \
 142              slice = cl_page_slice_get(cl_page, ++i))
 143
 144 #define cl_page_slice_for_each_reverse(cl_page, slice, i)       \
 145         for (i = (cl_page)->cp_layer_count - 1,                 \
 146              slice = cl_page_slice_get(cl_page, i); i >= 0;     \
 147              slice = cl_page_slice_get(cl_page, --i))
 148
 149 /**
 150  * Returns a slice within a cl_page, corresponding to the given layer in the
 151  * device stack.
 152  *
 153  * \see cl_lock_at()
 154  */
 155 static const struct cl_page_slice *
 156 cl_page_at_trusted(const struct cl_page *cl_page,
 157                    const struct lu_device_type *dtype)
 158 {
 159         const struct cl_page_slice *slice;
 160         int i;
 161
 162         ENTRY;
 163
 164         cl_page_slice_for_each(cl_page, slice, i) {
 165                 if (slice->cpl_obj->co_lu.lo_dev->ld_type == dtype)
 166                         RETURN(slice);
 167         }
 168
 169         RETURN(NULL);
 170 }
 171
 172 static void __cl_page_free(struct cl_page *cl_page, unsigned short bufsize)
 173 {
 174         int index = cl_page->cp_kmem_index;
 175
 176         if (index >= 0) {
 177                 LASSERT(index < ARRAY_SIZE(cl_page_kmem_array));
 178                 LASSERT(cl_page_kmem_size_array[index] == bufsize);
 179                 OBD_SLAB_FREE(cl_page, cl_page_kmem_array[index], bufsize);
 180         } else {
 181                 OBD_FREE(cl_page, bufsize);
 182         }
 183 }
 184
 185 static void cl_page_free(const struct lu_env *env, struct cl_page *cl_page,
 186                          struct pagevec *pvec)
 187 {
 188         struct cl_object *obj  = cl_page->cp_obj;
 189         unsigned short bufsize = cl_object_header(obj)->coh_page_bufsize;
 190         struct cl_page_slice *slice;
 191         int i;
 192
 193         ENTRY;
 194         PASSERT(env, cl_page, list_empty(&cl_page->cp_batch));
 195         PASSERT(env, cl_page, cl_page->cp_owner == NULL);
 196         PASSERT(env, cl_page, cl_page->cp_state == CPS_FREEING);
 197
 198         cl_page_slice_for_each(cl_page, slice, i) {
 199                 if (unlikely(slice->cpl_ops->cpo_fini != NULL))
 200                         slice->cpl_ops->cpo_fini(env, slice, pvec);
 201         }
 202         cl_page->cp_layer_count = 0;
 203         cs_page_dec(obj, CS_total);
 204         cs_pagestate_dec(obj, cl_page->cp_state);
 205         lu_object_ref_del_at(&obj->co_lu, &cl_page->cp_obj_ref,
 206                              "cl_page", cl_page);
 207         cl_object_put(env, obj);
 208         lu_ref_fini(&cl_page->cp_reference);
 209         __cl_page_free(cl_page, bufsize);
 210         EXIT;
 211 }
 212
 213 static struct cl_page *__cl_page_alloc(struct cl_object *o)
 214 {
 215         int i = 0;
 216         struct cl_page *cl_page = NULL;
 217         unsigned short bufsize = cl_object_header(o)->coh_page_bufsize;
 218
 219 check:
 220         /* the number of entries in cl_page_kmem_array is expected to
 221          * only be 2-3 entries, so the lookup overhead should be low.
 222          */
 223         for ( ; i < ARRAY_SIZE(cl_page_kmem_array); i++) {
 224                 if (smp_load_acquire(&cl_page_kmem_size_array[i])
 225                     == bufsize) {
 226                         OBD_SLAB_ALLOC_GFP(cl_page, cl_page_kmem_array[i],
 227                                            bufsize, GFP_NOFS);
 228                         if (cl_page)
 229                                 cl_page->cp_kmem_index = i;
 230                         return cl_page;
 231                 }
 232                 if (cl_page_kmem_size_array[i] == 0)
 233                         break;
 234         }
 235
 236         if (i < ARRAY_SIZE(cl_page_kmem_array)) {
 237                 char cache_name[32];
 238
 239                 mutex_lock(&cl_page_kmem_mutex);
 240                 if (cl_page_kmem_size_array[i]) {
 241                         mutex_unlock(&cl_page_kmem_mutex);
 242                         goto check;
 243                 }
 244                 snprintf(cache_name, sizeof(cache_name),
 245                          "cl_page_kmem-%u", bufsize);
 246                 cl_page_kmem_array[i] =
 247                         kmem_cache_create(cache_name, bufsize,
 248                                           0, 0, NULL);
 249                 if (cl_page_kmem_array[i] == NULL) {
 250                         mutex_unlock(&cl_page_kmem_mutex);
 251                         return NULL;
 252                 }
 253                 smp_store_release(&cl_page_kmem_size_array[i],
 254                                   bufsize);
 255                 mutex_unlock(&cl_page_kmem_mutex);
 256                 goto check;
 257         } else {
 258                 OBD_ALLOC_GFP(cl_page, bufsize, GFP_NOFS);
 259                 if (cl_page)
 260                         cl_page->cp_kmem_index = -1;
 261         }
 262
 263         return cl_page;
 264 }
 265
 266 struct cl_page *cl_page_alloc(const struct lu_env *env, struct cl_object *o,
 267                               pgoff_t ind, struct page *vmpage,
 268                               enum cl_page_type type)
 269 {
 270         struct cl_page *cl_page;
 271         struct cl_object *head;
 272
 273         ENTRY;
 274
 275         cl_page = __cl_page_alloc(o);
 276         if (cl_page != NULL) {
 277                 int result = 0;
 278
 279                 /*
 280                  * Please fix cl_page:cp_state/type declaration if
 281                  * these assertions fail in the future.
 282                  */
 283                 BUILD_BUG_ON((1 << CP_STATE_BITS) < CPS_NR); /* cp_state */
 284                 BUILD_BUG_ON((1 << CP_TYPE_BITS) < CPT_NR); /* cp_type */
 285                 atomic_set(&cl_page->cp_ref, 1);
 286                 cl_page->cp_obj = o;
 287                 cl_object_get(o);
 288                 lu_object_ref_add_at(&o->co_lu, &cl_page->cp_obj_ref,
 289                                      "cl_page", cl_page);
 290                 cl_page->cp_vmpage = vmpage;
 291                 cl_page->cp_state = CPS_CACHED;
 292                 cl_page->cp_type = type;
 293                 cl_page->cp_inode = NULL;
 294                 INIT_LIST_HEAD(&cl_page->cp_batch);
 295                 lu_ref_init(&cl_page->cp_reference);
 296                 head = o;
 297                 cl_object_for_each(o, head) {
 298                         if (o->co_ops->coo_page_init != NULL) {
 299                                 result = o->co_ops->coo_page_init(env, o,
 300                                                         cl_page, ind);
 301                                 if (result != 0) {
 302                                         cl_page_delete0(env, cl_page);
 303                                         cl_page_free(env, cl_page, NULL);
 304                                         cl_page = ERR_PTR(result);
 305                                         break;
 306                                 }
 307                         }
 308                 }
 309                 if (result == 0) {
 310                         cs_page_inc(o, CS_total);
 311                         cs_page_inc(o, CS_create);
 312                         cs_pagestate_dec(o, CPS_CACHED);
 313                 }
 314         } else {
 315                 cl_page = ERR_PTR(-ENOMEM);
 316         }
 317         RETURN(cl_page);
 318 }
 319
 320 /**
 321  * Returns a cl_page with index \a idx at the object \a o, and associated with
 322  * the VM page \a vmpage.
 323  *
 324  * This is the main entry point into the cl_page caching interface. First, a
 325  * cache (implemented as a per-object radix tree) is consulted. If page is
 326  * found there, it is returned immediately. Otherwise new page is allocated
 327  * and returned. In any case, additional reference to page is acquired.
 328  *
 329  * \see cl_object_find(), cl_lock_find()
 330  */
 331 struct cl_page *cl_page_find(const struct lu_env *env,
 332                              struct cl_object *o,
 333                              pgoff_t idx, struct page *vmpage,
 334                              enum cl_page_type type)
 335 {
 336         struct cl_page          *page = NULL;
 337         struct cl_object_header *hdr;
 338
 339         LASSERT(type == CPT_CACHEABLE || type == CPT_TRANSIENT);
 340         might_sleep();
 341
 342         ENTRY;
 343
 344         hdr = cl_object_header(o);
 345         cs_page_inc(o, CS_lookup);
 346
 347         CDEBUG(D_PAGE, "%lu@"DFID" %p %lx %d\n",
 348                idx, PFID(&hdr->coh_lu.loh_fid), vmpage, vmpage->private, type);
 349         /* fast path. */
 350         if (type == CPT_CACHEABLE) {
 351                 /* vmpage lock is used to protect the child/parent
 352                  * relationship */
 353                 LASSERT(PageLocked(vmpage));
 354                 /*
 355                  * cl_vmpage_page() can be called here without any locks as
 356                  *
 357                  *     - "vmpage" is locked (which prevents ->private from
 358                  *       concurrent updates), and
 359                  *
 360                  *     - "o" cannot be destroyed while current thread holds a
 361                  *       reference on it.
 362                  */
 363                 page = cl_vmpage_page(vmpage, o);
 364                 if (page != NULL) {
 365                         cs_page_inc(o, CS_hit);
 366                         RETURN(page);
 367                 }
 368         }
 369
 370         /* allocate and initialize cl_page */
 371         page = cl_page_alloc(env, o, idx, vmpage, type);
 372         RETURN(page);
 373 }
 374 EXPORT_SYMBOL(cl_page_find);
 375
 376 static inline int cl_page_invariant(const struct cl_page *pg)
 377 {
 378         return cl_page_in_use_noref(pg);
 379 }
 380
 381 static void cl_page_state_set0(const struct lu_env *env,
 382                                struct cl_page *cl_page,
 383                                enum cl_page_state state)
 384 {
 385         enum cl_page_state old;
 386
 387         /*
 388          * Matrix of allowed state transitions [old][new], for sanity
 389          * checking.
 390          */
 391         static const int allowed_transitions[CPS_NR][CPS_NR] = {
 392                 [CPS_CACHED] = {
 393                         [CPS_CACHED]  = 0,
 394                         [CPS_OWNED]   = 1, /* io finds existing cached page */
 395                         [CPS_PAGEIN]  = 0,
 396                         [CPS_PAGEOUT] = 1, /* write-out from the cache */
 397                         [CPS_FREEING] = 1, /* eviction on the memory pressure */
 398                 },
 399                 [CPS_OWNED] = {
 400                         [CPS_CACHED]  = 1, /* release to the cache */
 401                         [CPS_OWNED]   = 0,
 402                         [CPS_PAGEIN]  = 1, /* start read immediately */
 403                         [CPS_PAGEOUT] = 1, /* start write immediately */
 404                         [CPS_FREEING] = 1, /* lock invalidation or truncate */
 405                 },
 406                 [CPS_PAGEIN] = {
 407                         [CPS_CACHED]  = 1, /* io completion */
 408                         [CPS_OWNED]   = 0,
 409                         [CPS_PAGEIN]  = 0,
 410                         [CPS_PAGEOUT] = 0,
 411                         [CPS_FREEING] = 0,
 412                 },
 413                 [CPS_PAGEOUT] = {
 414                         [CPS_CACHED]  = 1, /* io completion */
 415                         [CPS_OWNED]   = 0,
 416                         [CPS_PAGEIN]  = 0,
 417                         [CPS_PAGEOUT] = 0,
 418                         [CPS_FREEING] = 0,
 419                 },
 420                 [CPS_FREEING] = {
 421                         [CPS_CACHED]  = 0,
 422                         [CPS_OWNED]   = 0,
 423                         [CPS_PAGEIN]  = 0,
 424                         [CPS_PAGEOUT] = 0,
 425                         [CPS_FREEING] = 0,
 426                 }
 427         };
 428
 429         ENTRY;
 430         old = cl_page->cp_state;
 431         PASSERT(env, cl_page, allowed_transitions[old][state]);
 432         CL_PAGE_HEADER(D_TRACE, env, cl_page, "%d -> %d\n", old, state);
 433         PASSERT(env, cl_page, cl_page->cp_state == old);
 434         PASSERT(env, cl_page, equi(state == CPS_OWNED,
 435                                    cl_page->cp_owner != NULL));
 436
 437         cs_pagestate_dec(cl_page->cp_obj, cl_page->cp_state);
 438         cs_pagestate_inc(cl_page->cp_obj, state);
 439         cl_page->cp_state = state;
 440         EXIT;
 441 }
 442
 443 static void cl_page_state_set(const struct lu_env *env,
 444                               struct cl_page *page, enum cl_page_state state)
 445 {
 446         cl_page_state_set0(env, page, state);
 447 }
 448
 449 /**
 450  * Acquires an additional reference to a page.
 451  *
 452  * This can be called only by caller already possessing a reference to \a
 453  * page.
 454  *
 455  * \see cl_object_get(), cl_lock_get().
 456  */
 457 void cl_page_get(struct cl_page *page)
 458 {
 459         ENTRY;
 460         cl_page_get_trust(page);
 461         EXIT;
 462 }
 463 EXPORT_SYMBOL(cl_page_get);
 464
 465 /**
 466  * Releases a reference to a page, use the pagevec to release the pages
 467  * in batch if provided.
 468  *
 469  * Users need to do a final pagevec_release() to release any trailing pages.
 470  */
 471 void cl_pagevec_put(const struct lu_env *env, struct cl_page *page,
 472                   struct pagevec *pvec)
 473 {
 474         ENTRY;
 475         CL_PAGE_HEADER(D_TRACE, env, page, "%d\n",
 476                        atomic_read(&page->cp_ref));
 477
 478         if (atomic_dec_and_test(&page->cp_ref)) {
 479                 LASSERT(page->cp_state == CPS_FREEING);
 480
 481                 LASSERT(atomic_read(&page->cp_ref) == 0);
 482                 PASSERT(env, page, page->cp_owner == NULL);
 483                 PASSERT(env, page, list_empty(&page->cp_batch));
 484                 /*
 485                  * Page is no longer reachable by other threads. Tear
 486                  * it down.
 487                  */
 488                 cl_page_free(env, page, pvec);
 489         }
 490
 491         EXIT;
 492 }
 493 EXPORT_SYMBOL(cl_pagevec_put);
 494
 495 /**
 496  * Releases a reference to a page, wrapper to cl_pagevec_put
 497  *
 498  * When last reference is released, page is returned to the cache, unless it
 499  * is in cl_page_state::CPS_FREEING state, in which case it is immediately
 500  * destroyed.
 501  *
 502  * \see cl_object_put(), cl_lock_put().
 503  */
 504 void cl_page_put(const struct lu_env *env, struct cl_page *page)
 505 {
 506         cl_pagevec_put(env, page, NULL);
 507 }
 508 EXPORT_SYMBOL(cl_page_put);
 509
 510 /**
 511  * Returns a cl_page associated with a VM page, and given cl_object.
 512  */
 513 struct cl_page *cl_vmpage_page(struct page *vmpage, struct cl_object *obj)
 514 {
 515         struct cl_page *page;
 516
 517         ENTRY;
 518         LASSERT(PageLocked(vmpage));
 519
 520         /*
 521          * NOTE: absence of races and liveness of data are guaranteed by page
 522          *       lock on a "vmpage". That works because object destruction has
 523          *       bottom-to-top pass.
 524          */
 525
 526         page = (struct cl_page *)vmpage->private;
 527         if (page != NULL) {
 528                 cl_page_get_trust(page);
 529                 LASSERT(page->cp_type == CPT_CACHEABLE);
 530         }
 531         RETURN(page);
 532 }
 533 EXPORT_SYMBOL(cl_vmpage_page);
 534
 535 const struct cl_page_slice *cl_page_at(const struct cl_page *page,
 536                                        const struct lu_device_type *dtype)
 537 {
 538         return cl_page_at_trusted(page, dtype);
 539 }
 540 EXPORT_SYMBOL(cl_page_at);
 541
 542 static void cl_page_owner_clear(struct cl_page *page)
 543 {
 544         ENTRY;
 545         if (page->cp_owner != NULL) {
 546                 LASSERT(page->cp_owner->ci_owned_nr > 0);
 547                 page->cp_owner->ci_owned_nr--;
 548                 page->cp_owner = NULL;
 549         }
 550         EXIT;
 551 }
 552
 553 static void cl_page_owner_set(struct cl_page *page)
 554 {
 555         ENTRY;
 556         LASSERT(page->cp_owner != NULL);
 557         page->cp_owner->ci_owned_nr++;
 558         EXIT;
 559 }
 560
 561 void cl_page_disown0(const struct lu_env *env,
 562                      struct cl_io *io, struct cl_page *cl_page)
 563 {
 564         const struct cl_page_slice *slice;
 565         enum cl_page_state state;
 566         int i;
 567
 568         ENTRY;
 569         state = cl_page->cp_state;
 570         PINVRNT(env, cl_page, state == CPS_OWNED ||
 571                 state == CPS_FREEING);
 572         PINVRNT(env, cl_page, cl_page_invariant(cl_page) ||
 573                 state == CPS_FREEING);
 574         cl_page_owner_clear(cl_page);
 575
 576         if (state == CPS_OWNED)
 577                 cl_page_state_set(env, cl_page, CPS_CACHED);
 578         /*
 579          * Completion call-backs are executed in the bottom-up order, so that
 580          * uppermost layer (llite), responsible for VFS/VM interaction runs
 581          * last and can release locks safely.
 582          */
 583         cl_page_slice_for_each_reverse(cl_page, slice, i) {
 584                 if (slice->cpl_ops->cpo_disown != NULL)
 585                         (*slice->cpl_ops->cpo_disown)(env, slice, io);
 586         }
 587
 588         EXIT;
 589 }
 590
 591 /**
 592  * returns true, iff page is owned by the given io.
 593  */
 594 int cl_page_is_owned(const struct cl_page *pg, const struct cl_io *io)
 595 {
 596         struct cl_io *top = cl_io_top((struct cl_io *)io);
 597         LINVRNT(cl_object_same(pg->cp_obj, io->ci_obj));
 598         ENTRY;
 599         RETURN(pg->cp_state == CPS_OWNED && pg->cp_owner == top);
 600 }
 601 EXPORT_SYMBOL(cl_page_is_owned);
 602
 603 /**
 604  * Try to own a page by IO.
 605  *
 606  * Waits until page is in cl_page_state::CPS_CACHED state, and then switch it
 607  * into cl_page_state::CPS_OWNED state.
 608  *
 609  * \pre  !cl_page_is_owned(cl_page, io)
 610  * \post result == 0 iff cl_page_is_owned(cl_page, io)
 611  *
 612  * \retval 0   success
 613  *
 614  * \retval -ve failure, e.g., cl_page was destroyed (and landed in
 615  *             cl_page_state::CPS_FREEING instead of cl_page_state::CPS_CACHED).
 616  *             or, page was owned by another thread, or in IO.
 617  *
 618  * \see cl_page_disown()
 619  * \see cl_page_operations::cpo_own()
 620  * \see cl_page_own_try()
 621  * \see cl_page_own
 622  */
 623 static int cl_page_own0(const struct lu_env *env, struct cl_io *io,
 624                         struct cl_page *cl_page, int nonblock)
 625 {
 626         const struct cl_page_slice *slice;
 627         int result = 0;
 628         int i;
 629
 630         ENTRY;
 631         PINVRNT(env, cl_page, !cl_page_is_owned(cl_page, io));
 632         io = cl_io_top(io);
 633
 634         if (cl_page->cp_state == CPS_FREEING) {
 635                 result = -ENOENT;
 636                 goto out;
 637         }
 638
 639         cl_page_slice_for_each(cl_page, slice, i) {
 640                 if (slice->cpl_ops->cpo_own)
 641                         result = (*slice->cpl_ops->cpo_own)(env, slice,
 642                                                             io, nonblock);
 643                 if (result != 0)
 644                         break;
 645         }
 646         if (result > 0)
 647                 result = 0;
 648
 649         if (result == 0) {
 650                 PASSERT(env, cl_page, cl_page->cp_owner == NULL);
 651                 cl_page->cp_owner = cl_io_top(io);
 652                 cl_page_owner_set(cl_page);
 653                 if (cl_page->cp_state != CPS_FREEING) {
 654                         cl_page_state_set(env, cl_page, CPS_OWNED);
 655                 } else {
 656                         cl_page_disown0(env, io, cl_page);
 657                         result = -ENOENT;
 658                 }
 659         }
 660
 661 out:
 662         PINVRNT(env, cl_page, ergo(result == 0,
 663                 cl_page_invariant(cl_page)));
 664         RETURN(result);
 665 }
 666
 667 /**
 668  * Own a page, might be blocked.
 669  *
 670  * \see cl_page_own0()
 671  */
 672 int cl_page_own(const struct lu_env *env, struct cl_io *io, struct cl_page *pg)
 673 {
 674         return cl_page_own0(env, io, pg, 0);
 675 }
 676 EXPORT_SYMBOL(cl_page_own);
 677
 678 /**
 679  * Nonblock version of cl_page_own().
 680  *
 681  * \see cl_page_own0()
 682  */
 683 int cl_page_own_try(const struct lu_env *env, struct cl_io *io,
 684                     struct cl_page *pg)
 685 {
 686         return cl_page_own0(env, io, pg, 1);
 687 }
 688 EXPORT_SYMBOL(cl_page_own_try);
 689
 690
 691 /**
 692  * Assume page ownership.
 693  *
 694  * Called when page is already locked by the hosting VM.
 695  *
 696  * \pre !cl_page_is_owned(cl_page, io)
 697  * \post cl_page_is_owned(cl_page, io)
 698  *
 699  * \see cl_page_operations::cpo_assume()
 700  */
 701 void cl_page_assume(const struct lu_env *env,
 702                     struct cl_io *io, struct cl_page *cl_page)
 703 {
 704         const struct cl_page_slice *slice;
 705         int i;
 706
 707         ENTRY;
 708
 709         PINVRNT(env, cl_page,
 710                 cl_object_same(cl_page->cp_obj, io->ci_obj));
 711         io = cl_io_top(io);
 712
 713         cl_page_slice_for_each(cl_page, slice, i) {
 714                 if (slice->cpl_ops->cpo_assume != NULL)
 715                         (*slice->cpl_ops->cpo_assume)(env, slice, io);
 716         }
 717
 718         PASSERT(env, cl_page, cl_page->cp_owner == NULL);
 719         cl_page->cp_owner = cl_io_top(io);
 720         cl_page_owner_set(cl_page);
 721         cl_page_state_set(env, cl_page, CPS_OWNED);
 722         EXIT;
 723 }
 724 EXPORT_SYMBOL(cl_page_assume);
 725
 726 /**
 727  * Releases page ownership without unlocking the page.
 728  *
 729  * Moves cl_page into cl_page_state::CPS_CACHED without releasing a lock
 730  * on the underlying VM page (as VM is supposed to do this itself).
 731  *
 732  * \pre   cl_page_is_owned(cl_page, io)
 733  * \post !cl_page_is_owned(cl_page, io)
 734  *
 735  * \see cl_page_assume()
 736  */
 737 void cl_page_unassume(const struct lu_env *env,
 738                       struct cl_io *io, struct cl_page *cl_page)
 739 {
 740         const struct cl_page_slice *slice;
 741         int i;
 742
 743         ENTRY;
 744         PINVRNT(env, cl_page, cl_page_is_owned(cl_page, io));
 745         PINVRNT(env, cl_page, cl_page_invariant(cl_page));
 746
 747         io = cl_io_top(io);
 748         cl_page_owner_clear(cl_page);
 749         cl_page_state_set(env, cl_page, CPS_CACHED);
 750
 751         cl_page_slice_for_each_reverse(cl_page, slice, i) {
 752                 if (slice->cpl_ops->cpo_unassume != NULL)
 753                         (*slice->cpl_ops->cpo_unassume)(env, slice, io);
 754         }
 755
 756         EXIT;
 757 }
 758 EXPORT_SYMBOL(cl_page_unassume);
 759
 760 /**
 761  * Releases page ownership.
 762  *
 763  * Moves page into cl_page_state::CPS_CACHED.
 764  *
 765  * \pre   cl_page_is_owned(pg, io)
 766  * \post !cl_page_is_owned(pg, io)
 767  *
 768  * \see cl_page_own()
 769  * \see cl_page_operations::cpo_disown()
 770  */
 771 void cl_page_disown(const struct lu_env *env,
 772                     struct cl_io *io, struct cl_page *pg)
 773 {
 774         PINVRNT(env, pg, cl_page_is_owned(pg, io) ||
 775                 pg->cp_state == CPS_FREEING);
 776
 777         ENTRY;
 778         io = cl_io_top(io);
 779         cl_page_disown0(env, io, pg);
 780         EXIT;
 781 }
 782 EXPORT_SYMBOL(cl_page_disown);
 783
 784 /**
 785  * Called when cl_page is to be removed from the object, e.g.,
 786  * as a result of truncate.
 787  *
 788  * Calls cl_page_operations::cpo_discard() top-to-bottom.
 789  *
 790  * \pre cl_page_is_owned(cl_page, io)
 791  *
 792  * \see cl_page_operations::cpo_discard()
 793  */
 794 void cl_page_discard(const struct lu_env *env,
 795                      struct cl_io *io, struct cl_page *cl_page)
 796 {
 797         const struct cl_page_slice *slice;
 798         int i;
 799
 800         PINVRNT(env, cl_page, cl_page_is_owned(cl_page, io));
 801         PINVRNT(env, cl_page, cl_page_invariant(cl_page));
 802
 803         cl_page_slice_for_each(cl_page, slice, i) {
 804                 if (slice->cpl_ops->cpo_discard != NULL)
 805                         (*slice->cpl_ops->cpo_discard)(env, slice, io);
 806         }
 807 }
 808 EXPORT_SYMBOL(cl_page_discard);
 809
 810 /**
 811  * Version of cl_page_delete() that can be called for not fully constructed
 812  * cl_pages, e.g. in an error handling cl_page_find()->cl_page_delete0()
 813  * path. Doesn't check cl_page invariant.
 814  */
 815 static void cl_page_delete0(const struct lu_env *env,
 816                             struct cl_page *cl_page)
 817 {
 818         const struct cl_page_slice *slice;
 819         int i;
 820
 821         ENTRY;
 822
 823         PASSERT(env, cl_page, cl_page->cp_state != CPS_FREEING);
 824
 825         /*
 826          * Severe all ways to obtain new pointers to @pg.
 827          */
 828         cl_page_owner_clear(cl_page);
 829         cl_page_state_set0(env, cl_page, CPS_FREEING);
 830
 831         cl_page_slice_for_each_reverse(cl_page, slice, i) {
 832                 if (slice->cpl_ops->cpo_delete != NULL)
 833                         (*slice->cpl_ops->cpo_delete)(env, slice);
 834         }
 835
 836         EXIT;
 837 }
 838
 839 /**
 840  * Called when a decision is made to throw page out of memory.
 841  *
 842  * Notifies all layers about page destruction by calling
 843  * cl_page_operations::cpo_delete() method top-to-bottom.
 844  *
 845  * Moves page into cl_page_state::CPS_FREEING state (this is the only place
 846  * where transition to this state happens).
 847  *
 848  * Eliminates all venues through which new references to the page can be
 849  * obtained:
 850  *
 851  *     - removes page from the radix trees,
 852  *
 853  *     - breaks linkage from VM page to cl_page.
 854  *
 855  * Once page reaches cl_page_state::CPS_FREEING, all remaining references will
 856  * drain after some time, at which point page will be recycled.
 857  *
 858  * \pre  VM page is locked
 859  * \post pg->cp_state == CPS_FREEING
 860  *
 861  * \see cl_page_operations::cpo_delete()
 862  */
 863 void cl_page_delete(const struct lu_env *env, struct cl_page *pg)
 864 {
 865         PINVRNT(env, pg, cl_page_invariant(pg));
 866         ENTRY;
 867         cl_page_delete0(env, pg);
 868         EXIT;
 869 }
 870 EXPORT_SYMBOL(cl_page_delete);
 871
 872 /**
 873  * Marks page up-to-date.
 874  *
 875  * Call cl_page_operations::cpo_export() through all layers top-to-bottom. The
 876  * layer responsible for VM interaction has to mark/clear page as up-to-date
 877  * by the \a uptodate argument.
 878  *
 879  * \see cl_page_operations::cpo_export()
 880  */
 881 void cl_page_export(const struct lu_env *env, struct cl_page *cl_page,
 882                     int uptodate)
 883 {
 884         const struct cl_page_slice *slice;
 885         int i;
 886
 887         PINVRNT(env, cl_page, cl_page_invariant(cl_page));
 888
 889         cl_page_slice_for_each(cl_page, slice, i) {
 890                 if (slice->cpl_ops->cpo_export != NULL)
 891                         (*slice->cpl_ops->cpo_export)(env, slice, uptodate);
 892         }
 893 }
 894 EXPORT_SYMBOL(cl_page_export);
 895
 896 /**
 897  * Returns true, if \a page is VM locked in a suitable sense by the calling
 898  * thread.
 899  */
 900 int cl_page_is_vmlocked(const struct lu_env *env,
 901                         const struct cl_page *cl_page)
 902 {
 903         const struct cl_page_slice *slice;
 904         int result;
 905
 906         ENTRY;
 907         slice = cl_page_slice_get(cl_page, 0);
 908         PASSERT(env, cl_page, slice->cpl_ops->cpo_is_vmlocked != NULL);
 909         /*
 910          * Call ->cpo_is_vmlocked() directly instead of going through
 911          * CL_PAGE_INVOKE(), because cl_page_is_vmlocked() is used by
 912          * cl_page_invariant().
 913          */
 914         result = slice->cpl_ops->cpo_is_vmlocked(env, slice);
 915         PASSERT(env, cl_page, result == -EBUSY || result == -ENODATA);
 916
 917         RETURN(result == -EBUSY);
 918 }
 919 EXPORT_SYMBOL(cl_page_is_vmlocked);
 920
 921 void cl_page_touch(const struct lu_env *env,
 922                    const struct cl_page *cl_page, size_t to)
 923 {
 924         const struct cl_page_slice *slice;
 925         int i;
 926
 927         ENTRY;
 928
 929         cl_page_slice_for_each(cl_page, slice, i) {
 930                 if (slice->cpl_ops->cpo_page_touch != NULL)
 931                         (*slice->cpl_ops->cpo_page_touch)(env, slice, to);
 932         }
 933
 934         EXIT;
 935 }
 936 EXPORT_SYMBOL(cl_page_touch);
 937
 938 static enum cl_page_state cl_req_type_state(enum cl_req_type crt)
 939 {
 940         ENTRY;
 941         RETURN(crt == CRT_WRITE ? CPS_PAGEOUT : CPS_PAGEIN);
 942 }
 943
 944 static void cl_page_io_start(const struct lu_env *env,
 945                              struct cl_page *pg, enum cl_req_type crt)
 946 {
 947         /*
 948          * Page is queued for IO, change its state.
 949          */
 950         ENTRY;
 951         cl_page_owner_clear(pg);
 952         cl_page_state_set(env, pg, cl_req_type_state(crt));
 953         EXIT;
 954 }
 955
 956 /**
 957  * Prepares page for immediate transfer. cl_page_operations::cpo_prep() is
 958  * called top-to-bottom. Every layer either agrees to submit this page (by
 959  * returning 0), or requests to omit this page (by returning -EALREADY). Layer
 960  * handling interactions with the VM also has to inform VM that page is under
 961  * transfer now.
 962  */
 963 int cl_page_prep(const struct lu_env *env, struct cl_io *io,
 964                  struct cl_page *cl_page, enum cl_req_type crt)
 965 {
 966         const struct cl_page_slice *slice;
 967         int result = 0;
 968         int i;
 969
 970         PINVRNT(env, cl_page, cl_page_is_owned(cl_page, io));
 971         PINVRNT(env, cl_page, cl_page_invariant(cl_page));
 972         PINVRNT(env, cl_page, crt < CRT_NR);
 973
 974         /*
 975          * this has to be called bottom-to-top, so that llite can set up
 976          * PG_writeback without risking other layers deciding to skip this
 977          * page.
 978          */
 979         if (crt >= CRT_NR)
 980                 return -EINVAL;
 981
 982         cl_page_slice_for_each(cl_page, slice, i) {
 983                 if (slice->cpl_ops->cpo_own)
 984                         result = (*slice->cpl_ops->io[crt].cpo_prep)(env,
 985                                                                      slice,
 986                                                                      io);
 987                 if (result != 0)
 988                         break;
 989         }
 990
 991         if (result >= 0) {
 992                 result = 0;
 993                 cl_page_io_start(env, cl_page, crt);
 994         }
 995
 996         CL_PAGE_HEADER(D_TRACE, env, cl_page, "%d %d\n", crt, result);
 997         return result;
 998 }
 999 EXPORT_SYMBOL(cl_page_prep);
1000
1001 /**
1002  * Notify layers about transfer completion.
1003  *
1004  * Invoked by transfer sub-system (which is a part of osc) to notify layers
1005  * that a transfer, of which this page is a part of has completed.
1006  *
1007  * Completion call-backs are executed in the bottom-up order, so that
1008  * uppermost layer (llite), responsible for the VFS/VM interaction runs last
1009  * and can release locks safely.
1010  *
1011  * \pre  cl_page->cp_state == CPS_PAGEIN || cl_page->cp_state == CPS_PAGEOUT
1012  * \post cl_page->cl_page_state == CPS_CACHED
1013  *
1014  * \see cl_page_operations::cpo_completion()
1015  */
1016 void cl_page_completion(const struct lu_env *env,
1017                         struct cl_page *cl_page, enum cl_req_type crt,
1018                         int ioret)
1019 {
1020         const struct cl_page_slice *slice;
1021         struct cl_sync_io *anchor = cl_page->cp_sync_io;
1022         int i;
1023
1024         ENTRY;
1025         PASSERT(env, cl_page, crt < CRT_NR);
1026         PASSERT(env, cl_page, cl_page->cp_state == cl_req_type_state(crt));
1027
1028         CL_PAGE_HEADER(D_TRACE, env, cl_page, "%d %d\n", crt, ioret);
1029         cl_page_state_set(env, cl_page, CPS_CACHED);
1030         if (crt >= CRT_NR)
1031                 return;
1032
1033         cl_page_slice_for_each_reverse(cl_page, slice, i) {
1034                 if (slice->cpl_ops->io[crt].cpo_completion != NULL)
1035                         (*slice->cpl_ops->io[crt].cpo_completion)(env, slice,
1036                                                                   ioret);
1037         }
1038
1039         if (anchor != NULL) {
1040                 LASSERT(cl_page->cp_sync_io == anchor);
1041                 cl_page->cp_sync_io = NULL;
1042                 cl_sync_io_note(env, anchor, ioret);
1043         }
1044         EXIT;
1045 }
1046 EXPORT_SYMBOL(cl_page_completion);
1047
1048 /**
1049  * Notify layers that transfer formation engine decided to yank this page from
1050  * the cache and to make it a part of a transfer.
1051  *
1052  * \pre  cl_page->cp_state == CPS_CACHED
1053  * \post cl_page->cp_state == CPS_PAGEIN || cl_page->cp_state == CPS_PAGEOUT
1054  *
1055  * \see cl_page_operations::cpo_make_ready()
1056  */
1057 int cl_page_make_ready(const struct lu_env *env, struct cl_page *cl_page,
1058                        enum cl_req_type crt)
1059 {
1060         const struct cl_page_slice *slice;
1061         int result = 0;
1062         int i;
1063
1064         ENTRY;
1065         PINVRNT(env, cl_page, crt < CRT_NR);
1066         if (crt >= CRT_NR)
1067                 RETURN(-EINVAL);
1068
1069         cl_page_slice_for_each(cl_page, slice, i) {
1070                 if (slice->cpl_ops->io[crt].cpo_make_ready != NULL)
1071                         result = (*slice->cpl_ops->io[crt].cpo_make_ready)(env, slice);
1072                 if (result != 0)
1073                         break;
1074         }
1075
1076         if (result >= 0) {
1077                 result = 0;
1078                 PASSERT(env, cl_page, cl_page->cp_state == CPS_CACHED);
1079                 cl_page_io_start(env, cl_page, crt);
1080         }
1081         CL_PAGE_HEADER(D_TRACE, env, cl_page, "%d %d\n", crt, result);
1082
1083         RETURN(result);
1084 }
1085 EXPORT_SYMBOL(cl_page_make_ready);
1086
1087 /**
1088  * Called if a page is being written back by kernel's intention.
1089  *
1090  * \pre  cl_page_is_owned(cl_page, io)
1091  * \post ergo(result == 0, cl_page->cp_state == CPS_PAGEOUT)
1092  *
1093  * \see cl_page_operations::cpo_flush()
1094  */
1095 int cl_page_flush(const struct lu_env *env, struct cl_io *io,
1096                   struct cl_page *cl_page)
1097 {
1098         const struct cl_page_slice *slice;
1099         int result = 0;
1100         int i;
1101
1102         ENTRY;
1103         PINVRNT(env, cl_page, cl_page_is_owned(cl_page, io));
1104         PINVRNT(env, cl_page, cl_page_invariant(cl_page));
1105
1106         cl_page_slice_for_each(cl_page, slice, i) {
1107                 if (slice->cpl_ops->cpo_flush != NULL)
1108                         result = (*slice->cpl_ops->cpo_flush)(env, slice, io);
1109                 if (result != 0)
1110                         break;
1111         }
1112         if (result > 0)
1113                 result = 0;
1114
1115         CL_PAGE_HEADER(D_TRACE, env, cl_page, "%d\n", result);
1116         RETURN(result);
1117 }
1118 EXPORT_SYMBOL(cl_page_flush);
1119
1120 /**
1121  * Tells transfer engine that only part of a page is to be transmitted.
1122  *
1123  * \see cl_page_operations::cpo_clip()
1124  */
1125 void cl_page_clip(const struct lu_env *env, struct cl_page *cl_page,
1126                   int from, int to)
1127 {
1128         const struct cl_page_slice *slice;
1129         int i;
1130
1131         PINVRNT(env, cl_page, cl_page_invariant(cl_page));
1132
1133         CL_PAGE_HEADER(D_TRACE, env, cl_page, "%d %d\n", from, to);
1134         cl_page_slice_for_each(cl_page, slice, i) {
1135                 if (slice->cpl_ops->cpo_clip != NULL)
1136                         (*slice->cpl_ops->cpo_clip)(env, slice, from, to);
1137         }
1138 }
1139 EXPORT_SYMBOL(cl_page_clip);
1140
1141 /**
1142  * Prints human readable representation of \a pg to the \a f.
1143  */
1144 void cl_page_header_print(const struct lu_env *env, void *cookie,
1145                           lu_printer_t printer, const struct cl_page *pg)
1146 {
1147         (*printer)(env, cookie,
1148                    "page@%p[%d %p %d %d %p]\n",
1149                    pg, atomic_read(&pg->cp_ref), pg->cp_obj,
1150                    pg->cp_state, pg->cp_type,
1151                    pg->cp_owner);
1152 }
1153 EXPORT_SYMBOL(cl_page_header_print);
1154
1155 /**
1156  * Prints human readable representation of \a cl_page to the \a f.
1157  */
1158 void cl_page_print(const struct lu_env *env, void *cookie,
1159                    lu_printer_t printer, const struct cl_page *cl_page)
1160 {
1161         const struct cl_page_slice *slice;
1162         int result = 0;
1163         int i;
1164
1165         cl_page_header_print(env, cookie, printer, cl_page);
1166         cl_page_slice_for_each(cl_page, slice, i) {
1167                 if (slice->cpl_ops->cpo_print != NULL)
1168                         result = (*slice->cpl_ops->cpo_print)(env, slice,
1169                                                              cookie, printer);
1170                 if (result != 0)
1171                         break;
1172         }
1173         (*printer)(env, cookie, "end page@%p\n", cl_page);
1174 }
1175 EXPORT_SYMBOL(cl_page_print);
1176
1177 /**
1178  * Converts a byte offset within object \a obj into a page index.
1179  */
1180 loff_t cl_offset(const struct cl_object *obj, pgoff_t idx)
1181 {
1182         return (loff_t)idx << PAGE_SHIFT;
1183 }
1184 EXPORT_SYMBOL(cl_offset);
1185
1186 /**
1187  * Converts a page index into a byte offset within object \a obj.
1188  */
1189 pgoff_t cl_index(const struct cl_object *obj, loff_t offset)
1190 {
1191         return offset >> PAGE_SHIFT;
1192 }
1193 EXPORT_SYMBOL(cl_index);
1194
1195 size_t cl_page_size(const struct cl_object *obj)
1196 {
1197         return 1UL << PAGE_SHIFT;
1198 }
1199 EXPORT_SYMBOL(cl_page_size);
1200
1201 /**
1202  * Adds page slice to the compound page.
1203  *
1204  * This is called by cl_object_operations::coo_page_init() methods to add a
1205  * per-layer state to the page. New state is added at the end of
1206  * cl_page::cp_layers list, that is, it is at the bottom of the stack.
1207  *
1208  * \see cl_lock_slice_add(), cl_req_slice_add(), cl_io_slice_add()
1209  */
1210 void cl_page_slice_add(struct cl_page *cl_page, struct cl_page_slice *slice,
1211                        struct cl_object *obj,
1212                        const struct cl_page_operations *ops)
1213 {
1214         unsigned int offset = (char *)slice -
1215                         ((char *)cl_page + sizeof(*cl_page));
1216
1217         ENTRY;
1218         LASSERT(cl_page->cp_layer_count < CP_MAX_LAYER);
1219         LASSERT(offset < (1 << sizeof(cl_page->cp_layer_offset[0]) * 8));
1220         cl_page->cp_layer_offset[cl_page->cp_layer_count++] = offset;
1221         slice->cpl_obj  = obj;
1222         slice->cpl_ops  = ops;
1223         slice->cpl_page = cl_page;
1224
1225         EXIT;
1226 }
1227 EXPORT_SYMBOL(cl_page_slice_add);
1228
1229 /**
1230  * Allocate and initialize cl_cache, called by ll_init_sbi().
1231  */
1232 struct cl_client_cache *cl_cache_init(unsigned long lru_page_max)
1233 {
1234         struct cl_client_cache  *cache = NULL;
1235
1236         ENTRY;
1237         OBD_ALLOC(cache, sizeof(*cache));
1238         if (cache == NULL)
1239                 RETURN(NULL);
1240
1241         /* Initialize cache data */
1242         atomic_set(&cache->ccc_users, 1);
1243         cache->ccc_lru_max = lru_page_max;
1244         atomic_long_set(&cache->ccc_lru_left, lru_page_max);
1245         spin_lock_init(&cache->ccc_lru_lock);
1246         INIT_LIST_HEAD(&cache->ccc_lru);
1247
1248         /* turn unstable check off by default as it impacts performance */
1249         cache->ccc_unstable_check = 0;
1250         atomic_long_set(&cache->ccc_unstable_nr, 0);
1251         init_waitqueue_head(&cache->ccc_unstable_waitq);
1252         mutex_init(&cache->ccc_max_cache_mb_lock);
1253
1254         RETURN(cache);
1255 }
1256 EXPORT_SYMBOL(cl_cache_init);
1257
1258 /**
1259  * Increase cl_cache refcount
1260  */
1261 void cl_cache_incref(struct cl_client_cache *cache)
1262 {
1263         atomic_inc(&cache->ccc_users);
1264 }
1265 EXPORT_SYMBOL(cl_cache_incref);
1266
1267 /**
1268  * Decrease cl_cache refcount and free the cache if refcount=0.
1269  * Since llite, lov and osc all hold cl_cache refcount,
1270  * the free will not cause race. (LU-6173)
1271  */
1272 void cl_cache_decref(struct cl_client_cache *cache)
1273 {
1274         if (atomic_dec_and_test(&cache->ccc_users))
1275                 OBD_FREE(cache, sizeof(*cache));
1276 }
1277 EXPORT_SYMBOL(cl_cache_decref);