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  *
  31  * Client Lustre Page.
  32  *
  33  *   Author: Nikita Danilov <nikita.danilov@sun.com>
  34  *   Author: Jinshan Xiong <jinshan.xiong@intel.com>
  35  */
  36
  37 #define DEBUG_SUBSYSTEM S_CLASS
  38
  39 #include <linux/list.h>
  40 #include <libcfs/libcfs.h>
  41 #include <obd_class.h>
  42 #include <obd_support.h>
  43
  44 #include <cl_object.h>
  45 #include "cl_internal.h"
  46
  47 static void cl_page_delete0(const struct lu_env *env, struct cl_page *pg);
  48 static DEFINE_MUTEX(cl_page_kmem_mutex);
  49
  50 #ifdef LIBCFS_DEBUG
  51 # define PASSERT(env, page, expr)                                       \
  52   do {                                                                    \
  53           if (unlikely(!(expr))) {                                      \
  54                   CL_PAGE_DEBUG(D_ERROR, (env), (page), #expr "\n");    \
  55                   LASSERT(0);                                           \
  56           }                                                             \
  57   } while (0)
  58 #else /* !LIBCFS_DEBUG */
  59 # define PASSERT(env, page, exp) \
  60         ((void)sizeof(env), (void)sizeof(page), (void)sizeof !!(exp))
  61 #endif /* !LIBCFS_DEBUG */
  62
  63 #ifdef CONFIG_LUSTRE_DEBUG_EXPENSIVE_CHECK
  64 # define PINVRNT(env, page, expr)                                       \
  65   do {                                                                    \
  66           if (unlikely(!(expr))) {                                      \
  67                   CL_PAGE_DEBUG(D_ERROR, (env), (page), #expr "\n");    \
  68                   LINVRNT(0);                                           \
  69           }                                                             \
  70   } while (0)
  71 #else /* !CONFIG_LUSTRE_DEBUG_EXPENSIVE_CHECK */
  72 # define PINVRNT(env, page, exp) \
  73          ((void)sizeof(env), (void)sizeof(page), (void)sizeof !!(exp))
  74 #endif /* !CONFIG_LUSTRE_DEBUG_EXPENSIVE_CHECK */
  75
  76 /* Disable page statistic by default due to huge performance penalty. */
  77 static void cs_page_inc(const struct cl_object *obj,
  78                         enum cache_stats_item item)
  79 {
  80 #ifdef CONFIG_DEBUG_PAGESTATE_TRACKING
  81         atomic_inc(&cl_object_site(obj)->cs_pages.cs_stats[item]);
  82 #endif
  83 }
  84
  85 static void cs_page_dec(const struct cl_object *obj,
  86                         enum cache_stats_item item)
  87 {
  88 #ifdef CONFIG_DEBUG_PAGESTATE_TRACKING
  89         atomic_dec(&cl_object_site(obj)->cs_pages.cs_stats[item]);
  90 #endif
  91 }
  92
  93 static void cs_pagestate_inc(const struct cl_object *obj,
  94                              enum cl_page_state state)
  95 {
  96 #ifdef CONFIG_DEBUG_PAGESTATE_TRACKING
  97         atomic_inc(&cl_object_site(obj)->cs_pages_state[state]);
  98 #endif
  99 }
 100
 101 static void cs_pagestate_dec(const struct cl_object *obj,
 102                               enum cl_page_state state)
 103 {
 104 #ifdef CONFIG_DEBUG_PAGESTATE_TRACKING
 105         atomic_dec(&cl_object_site(obj)->cs_pages_state[state]);
 106 #endif
 107 }
 108
 109 /**
 110  * Internal version of cl_page_get().
 111  *
 112  * This function can be used to obtain initial reference to previously
 113  * unreferenced cached object. It can be called only if concurrent page
 114  * reclamation is somehow prevented, e.g., by keeping a lock on a VM page,
 115  * associated with \a page.
 116  *
 117  * Use with care! Not exported.
 118  */
 119 static void cl_page_get_trust(struct cl_page *page)
 120 {
 121         LASSERT(atomic_read(&page->cp_ref) > 0);
 122         atomic_inc(&page->cp_ref);
 123 }
 124
 125 static struct cl_page_slice *
 126 cl_page_slice_get(const struct cl_page *cl_page, int index)
 127 {
 128         if (index < 0 || index >= cl_page->cp_layer_count)
 129                 return NULL;
 130
 131         /* To get the cp_layer_offset values fit under 256 bytes, we
 132          * use the offset beyond the end of struct cl_page.
 133          */
 134         return (struct cl_page_slice *)((char *)cl_page + sizeof(*cl_page) +
 135                                         cl_page->cp_layer_offset[index]);
 136 }
 137
 138 #define cl_page_slice_for_each(cl_page, slice, i)               \
 139         for (i = 0, slice = cl_page_slice_get(cl_page, 0);      \
 140              i < (cl_page)->cp_layer_count;                     \
 141              slice = cl_page_slice_get(cl_page, ++i))
 142
 143 #define cl_page_slice_for_each_reverse(cl_page, slice, i)       \
 144         for (i = (cl_page)->cp_layer_count - 1,                 \
 145              slice = cl_page_slice_get(cl_page, i); i >= 0;     \
 146              slice = cl_page_slice_get(cl_page, --i))
 147
 148 /**
 149  * Returns a slice within a cl_page, corresponding to the given layer in the
 150  * device stack.
 151  *
 152  * \see cl_lock_at()
 153  */
 154 static const struct cl_page_slice *
 155 cl_page_at_trusted(const struct cl_page *cl_page,
 156                    const struct lu_device_type *dtype)
 157 {
 158         const struct cl_page_slice *slice;
 159         int i;
 160
 161         ENTRY;
 162
 163         cl_page_slice_for_each(cl_page, slice, i) {
 164                 if (slice->cpl_obj->co_lu.lo_dev->ld_type == dtype)
 165                         RETURN(slice);
 166         }
 167
 168         RETURN(NULL);
 169 }
 170
 171 static void __cl_page_free(struct cl_page *cl_page, unsigned short bufsize)
 172 {
 173         int index = cl_page->cp_kmem_index;
 174
 175         if (index >= 0) {
 176                 LASSERT(index < ARRAY_SIZE(cl_page_kmem_array));
 177                 LASSERT(cl_page_kmem_size_array[index] == bufsize);
 178                 OBD_SLAB_FREE(cl_page, cl_page_kmem_array[index], bufsize);
 179         } else {
 180                 OBD_FREE(cl_page, bufsize);
 181         }
 182 }
 183
 184 static void cl_page_free(const struct lu_env *env, struct cl_page *cl_page,
 185                          struct pagevec *pvec)
 186 {
 187         struct cl_object *obj  = cl_page->cp_obj;
 188         unsigned short bufsize = cl_object_header(obj)->coh_page_bufsize;
 189         struct cl_page_slice *slice;
 190         int i;
 191
 192         ENTRY;
 193         PASSERT(env, cl_page, list_empty(&cl_page->cp_batch));
 194         PASSERT(env, cl_page, cl_page->cp_owner == NULL);
 195         PASSERT(env, cl_page, cl_page->cp_state == CPS_FREEING);
 196
 197         cl_page_slice_for_each(cl_page, slice, i) {
 198                 if (unlikely(slice->cpl_ops->cpo_fini != NULL))
 199                         slice->cpl_ops->cpo_fini(env, slice, pvec);
 200         }
 201         cl_page->cp_layer_count = 0;
 202         cs_page_dec(obj, CS_total);
 203         cs_pagestate_dec(obj, cl_page->cp_state);
 204         lu_object_ref_del_at(&obj->co_lu, &cl_page->cp_obj_ref,
 205                              "cl_page", cl_page);
 206         if (cl_page->cp_type != CPT_TRANSIENT)
 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         if (OBD_FAIL_CHECK(OBD_FAIL_LLITE_PAGE_ALLOC))
 220                 return NULL;
 221
 222 check:
 223         /* the number of entries in cl_page_kmem_array is expected to
 224          * only be 2-3 entries, so the lookup overhead should be low.
 225          */
 226         for ( ; i < ARRAY_SIZE(cl_page_kmem_array); i++) {
 227                 if (smp_load_acquire(&cl_page_kmem_size_array[i])
 228                     == bufsize) {
 229                         OBD_SLAB_ALLOC_GFP(cl_page, cl_page_kmem_array[i],
 230                                            bufsize, GFP_NOFS);
 231                         if (cl_page)
 232                                 cl_page->cp_kmem_index = i;
 233                         return cl_page;
 234                 }
 235                 if (cl_page_kmem_size_array[i] == 0)
 236                         break;
 237         }
 238
 239         if (i < ARRAY_SIZE(cl_page_kmem_array)) {
 240                 char cache_name[32];
 241
 242                 mutex_lock(&cl_page_kmem_mutex);
 243                 if (cl_page_kmem_size_array[i]) {
 244                         mutex_unlock(&cl_page_kmem_mutex);
 245                         goto check;
 246                 }
 247                 snprintf(cache_name, sizeof(cache_name),
 248                          "cl_page_kmem-%u", bufsize);
 249                 cl_page_kmem_array[i] =
 250                         kmem_cache_create(cache_name, bufsize,
 251                                           0, 0, NULL);
 252                 if (cl_page_kmem_array[i] == NULL) {
 253                         mutex_unlock(&cl_page_kmem_mutex);
 254                         return NULL;
 255                 }
 256                 smp_store_release(&cl_page_kmem_size_array[i],
 257                                   bufsize);
 258                 mutex_unlock(&cl_page_kmem_mutex);
 259                 goto check;
 260         } else {
 261                 OBD_ALLOC_GFP(cl_page, bufsize, GFP_NOFS);
 262                 if (cl_page)
 263                         cl_page->cp_kmem_index = -1;
 264         }
 265
 266         return cl_page;
 267 }
 268
 269 struct cl_page *cl_page_alloc(const struct lu_env *env, struct cl_object *o,
 270                               pgoff_t ind, struct page *vmpage,
 271                               enum cl_page_type type)
 272 {
 273         struct cl_page *cl_page;
 274         struct cl_object *head;
 275
 276         ENTRY;
 277
 278         cl_page = __cl_page_alloc(o);
 279         if (cl_page != NULL) {
 280                 int result = 0;
 281
 282                 /*
 283                  * Please fix cl_page:cp_state/type declaration if
 284                  * these assertions fail in the future.
 285                  */
 286                 BUILD_BUG_ON((1 << CP_STATE_BITS) < CPS_NR); /* cp_state */
 287                 BUILD_BUG_ON((1 << CP_TYPE_BITS) < CPT_NR); /* cp_type */
 288                 atomic_set(&cl_page->cp_ref, 1);
 289                 cl_page->cp_obj = o;
 290                 if (type != CPT_TRANSIENT)
 291                         cl_object_get(o);
 292                 lu_object_ref_add_at(&o->co_lu, &cl_page->cp_obj_ref,
 293                                      "cl_page", cl_page);
 294                 cl_page->cp_vmpage = vmpage;
 295                 cl_page->cp_state = CPS_CACHED;
 296                 cl_page->cp_type = type;
 297                 cl_page->cp_inode = NULL;
 298                 INIT_LIST_HEAD(&cl_page->cp_batch);
 299                 lu_ref_init(&cl_page->cp_reference);
 300                 head = o;
 301                 cl_object_for_each(o, head) {
 302                         if (o->co_ops->coo_page_init != NULL) {
 303                                 result = o->co_ops->coo_page_init(env, o,
 304                                                         cl_page, ind);
 305                                 if (result != 0) {
 306                                         cl_page_delete0(env, cl_page);
 307                                         cl_page_free(env, cl_page, NULL);
 308                                         cl_page = ERR_PTR(result);
 309                                         break;
 310                                 }
 311                         }
 312                 }
 313                 if (result == 0) {
 314                         cs_page_inc(o, CS_total);
 315                         cs_page_inc(o, CS_create);
 316                         cs_pagestate_dec(o, CPS_CACHED);
 317                 }
 318         } else {
 319                 cl_page = ERR_PTR(-ENOMEM);
 320         }
 321         RETURN(cl_page);
 322 }
 323
 324 /**
 325  * Returns a cl_page with index \a idx at the object \a o, and associated with
 326  * the VM page \a vmpage.
 327  *
 328  * This is the main entry point into the cl_page caching interface. First, a
 329  * cache (implemented as a per-object radix tree) is consulted. If page is
 330  * found there, it is returned immediately. Otherwise new page is allocated
 331  * and returned. In any case, additional reference to page is acquired.
 332  *
 333  * \see cl_object_find(), cl_lock_find()
 334  */
 335 struct cl_page *cl_page_find(const struct lu_env *env,
 336                              struct cl_object *o,
 337                              pgoff_t idx, struct page *vmpage,
 338                              enum cl_page_type type)
 339 {
 340         struct cl_page          *page = NULL;
 341         struct cl_object_header *hdr;
 342
 343         LASSERT(type == CPT_CACHEABLE || type == CPT_TRANSIENT);
 344         might_sleep();
 345
 346         ENTRY;
 347
 348         hdr = cl_object_header(o);
 349         cs_page_inc(o, CS_lookup);
 350
 351         CDEBUG(D_PAGE, "%lu@"DFID" %p %lx %d\n",
 352                idx, PFID(&hdr->coh_lu.loh_fid), vmpage, vmpage->private, type);
 353         /* fast path. */
 354         if (type == CPT_CACHEABLE) {
 355                 /* vmpage lock is used to protect the child/parent
 356                  * relationship */
 357                 LASSERT(PageLocked(vmpage));
 358                 /*
 359                  * cl_vmpage_page() can be called here without any locks as
 360                  *
 361                  *     - "vmpage" is locked (which prevents ->private from
 362                  *       concurrent updates), and
 363                  *
 364                  *     - "o" cannot be destroyed while current thread holds a
 365                  *       reference on it.
 366                  */
 367                 page = cl_vmpage_page(vmpage, o);
 368                 if (page != NULL) {
 369                         cs_page_inc(o, CS_hit);
 370                         RETURN(page);
 371                 }
 372         }
 373
 374         /* allocate and initialize cl_page */
 375         page = cl_page_alloc(env, o, idx, vmpage, type);
 376         RETURN(page);
 377 }
 378 EXPORT_SYMBOL(cl_page_find);
 379
 380 static inline int cl_page_invariant(const struct cl_page *pg)
 381 {
 382         return cl_page_in_use_noref(pg);
 383 }
 384
 385 static void cl_page_state_set0(const struct lu_env *env,
 386                                struct cl_page *cl_page,
 387                                enum cl_page_state state)
 388 {
 389         enum cl_page_state old;
 390
 391         /*
 392          * Matrix of allowed state transitions [old][new], for sanity
 393          * checking.
 394          */
 395         static const int allowed_transitions[CPS_NR][CPS_NR] = {
 396                 [CPS_CACHED] = {
 397                         [CPS_CACHED]  = 0,
 398                         [CPS_OWNED]   = 1, /* io finds existing cached page */
 399                         [CPS_PAGEIN]  = 0,
 400                         [CPS_PAGEOUT] = 1, /* write-out from the cache */
 401                         [CPS_FREEING] = 1, /* eviction on the memory pressure */
 402                 },
 403                 [CPS_OWNED] = {
 404                         [CPS_CACHED]  = 1, /* release to the cache */
 405                         [CPS_OWNED]   = 0,
 406                         [CPS_PAGEIN]  = 1, /* start read immediately */
 407                         [CPS_PAGEOUT] = 1, /* start write immediately */
 408                         [CPS_FREEING] = 1, /* lock invalidation or truncate */
 409                 },
 410                 [CPS_PAGEIN] = {
 411                         [CPS_CACHED]  = 1, /* io completion */
 412                         [CPS_OWNED]   = 0,
 413                         [CPS_PAGEIN]  = 0,
 414                         [CPS_PAGEOUT] = 0,
 415                         [CPS_FREEING] = 0,
 416                 },
 417                 [CPS_PAGEOUT] = {
 418                         [CPS_CACHED]  = 1, /* io completion */
 419                         [CPS_OWNED]   = 0,
 420                         [CPS_PAGEIN]  = 0,
 421                         [CPS_PAGEOUT] = 0,
 422                         [CPS_FREEING] = 0,
 423                 },
 424                 [CPS_FREEING] = {
 425                         [CPS_CACHED]  = 0,
 426                         [CPS_OWNED]   = 0,
 427                         [CPS_PAGEIN]  = 0,
 428                         [CPS_PAGEOUT] = 0,
 429                         [CPS_FREEING] = 0,
 430                 }
 431         };
 432
 433         ENTRY;
 434         old = cl_page->cp_state;
 435         PASSERT(env, cl_page, allowed_transitions[old][state]);
 436         CL_PAGE_HEADER(D_TRACE, env, cl_page, "%d -> %d\n", old, state);
 437         PASSERT(env, cl_page, cl_page->cp_state == old);
 438         PASSERT(env, cl_page, equi(state == CPS_OWNED,
 439                                    cl_page->cp_owner != NULL));
 440
 441         cs_pagestate_dec(cl_page->cp_obj, cl_page->cp_state);
 442         cs_pagestate_inc(cl_page->cp_obj, state);
 443         cl_page->cp_state = state;
 444         EXIT;
 445 }
 446
 447 static void cl_page_state_set(const struct lu_env *env,
 448                               struct cl_page *page, enum cl_page_state state)
 449 {
 450         cl_page_state_set0(env, page, state);
 451 }
 452
 453 /**
 454  * Acquires an additional reference to a page.
 455  *
 456  * This can be called only by caller already possessing a reference to \a
 457  * page.
 458  *
 459  * \see cl_object_get(), cl_lock_get().
 460  */
 461 void cl_page_get(struct cl_page *page)
 462 {
 463         ENTRY;
 464         cl_page_get_trust(page);
 465         EXIT;
 466 }
 467 EXPORT_SYMBOL(cl_page_get);
 468
 469 /**
 470  * Releases a reference to a page, use the pagevec to release the pages
 471  * in batch if provided.
 472  *
 473  * Users need to do a final pagevec_release() to release any trailing pages.
 474  */
 475 void cl_pagevec_put(const struct lu_env *env, struct cl_page *page,
 476                   struct pagevec *pvec)
 477 {
 478         ENTRY;
 479         CL_PAGE_HEADER(D_TRACE, env, page, "%d\n",
 480                        atomic_read(&page->cp_ref));
 481
 482         if (atomic_dec_and_test(&page->cp_ref)) {
 483                 LASSERT(page->cp_state == CPS_FREEING);
 484
 485                 LASSERT(atomic_read(&page->cp_ref) == 0);
 486                 PASSERT(env, page, page->cp_owner == NULL);
 487                 PASSERT(env, page, list_empty(&page->cp_batch));
 488                 /*
 489                  * Page is no longer reachable by other threads. Tear
 490                  * it down.
 491                  */
 492                 cl_page_free(env, page, pvec);
 493         }
 494
 495         EXIT;
 496 }
 497 EXPORT_SYMBOL(cl_pagevec_put);
 498
 499 /**
 500  * Releases a reference to a page, wrapper to cl_pagevec_put
 501  *
 502  * When last reference is released, page is returned to the cache, unless it
 503  * is in cl_page_state::CPS_FREEING state, in which case it is immediately
 504  * destroyed.
 505  *
 506  * \see cl_object_put(), cl_lock_put().
 507  */
 508 void cl_page_put(const struct lu_env *env, struct cl_page *page)
 509 {
 510         cl_pagevec_put(env, page, NULL);
 511 }
 512 EXPORT_SYMBOL(cl_page_put);
 513
 514 /**
 515  * Returns a cl_page associated with a VM page, and given cl_object.
 516  */
 517 struct cl_page *cl_vmpage_page(struct page *vmpage, struct cl_object *obj)
 518 {
 519         struct cl_page *page;
 520
 521         ENTRY;
 522         LASSERT(PageLocked(vmpage));
 523
 524         /*
 525          * NOTE: absence of races and liveness of data are guaranteed by page
 526          *       lock on a "vmpage". That works because object destruction has
 527          *       bottom-to-top pass.
 528          */
 529
 530         page = (struct cl_page *)vmpage->private;
 531         if (page != NULL) {
 532                 cl_page_get_trust(page);
 533                 LASSERT(page->cp_type == CPT_CACHEABLE);
 534         }
 535         RETURN(page);
 536 }
 537 EXPORT_SYMBOL(cl_vmpage_page);
 538
 539 const struct cl_page_slice *cl_page_at(const struct cl_page *page,
 540                                        const struct lu_device_type *dtype)
 541 {
 542         return cl_page_at_trusted(page, dtype);
 543 }
 544 EXPORT_SYMBOL(cl_page_at);
 545
 546 static void cl_page_owner_clear(struct cl_page *page)
 547 {
 548         ENTRY;
 549         if (page->cp_owner != NULL) {
 550                 LASSERT(page->cp_owner->ci_owned_nr > 0);
 551                 page->cp_owner->ci_owned_nr--;
 552                 page->cp_owner = NULL;
 553         }
 554         EXIT;
 555 }
 556
 557 static void cl_page_owner_set(struct cl_page *page)
 558 {
 559         ENTRY;
 560         LASSERT(page->cp_owner != NULL);
 561         page->cp_owner->ci_owned_nr++;
 562         EXIT;
 563 }
 564
 565 void cl_page_disown0(const struct lu_env *env,
 566                      struct cl_io *io, struct cl_page *cl_page)
 567 {
 568         const struct cl_page_slice *slice;
 569         enum cl_page_state state;
 570         int i;
 571
 572         ENTRY;
 573         state = cl_page->cp_state;
 574         PINVRNT(env, cl_page, state == CPS_OWNED ||
 575                 state == CPS_FREEING);
 576         PINVRNT(env, cl_page, cl_page_invariant(cl_page) ||
 577                 state == CPS_FREEING);
 578         cl_page_owner_clear(cl_page);
 579
 580         if (state == CPS_OWNED)
 581                 cl_page_state_set(env, cl_page, CPS_CACHED);
 582         /*
 583          * Completion call-backs are executed in the bottom-up order, so that
 584          * uppermost layer (llite), responsible for VFS/VM interaction runs
 585          * last and can release locks safely.
 586          */
 587         cl_page_slice_for_each_reverse(cl_page, slice, i) {
 588                 if (slice->cpl_ops->cpo_disown != NULL)
 589                         (*slice->cpl_ops->cpo_disown)(env, slice, io);
 590         }
 591
 592         EXIT;
 593 }
 594
 595 /**
 596  * returns true, iff page is owned by the given io.
 597  */
 598 int cl_page_is_owned(const struct cl_page *pg, const struct cl_io *io)
 599 {
 600         struct cl_io *top = cl_io_top((struct cl_io *)io);
 601         LINVRNT(cl_object_same(pg->cp_obj, io->ci_obj));
 602         ENTRY;
 603         RETURN(pg->cp_state == CPS_OWNED && pg->cp_owner == top);
 604 }
 605 EXPORT_SYMBOL(cl_page_is_owned);
 606
 607 /**
 608  * Try to own a page by IO.
 609  *
 610  * Waits until page is in cl_page_state::CPS_CACHED state, and then switch it
 611  * into cl_page_state::CPS_OWNED state.
 612  *
 613  * \pre  !cl_page_is_owned(cl_page, io)
 614  * \post result == 0 iff cl_page_is_owned(cl_page, io)
 615  *
 616  * \retval 0   success
 617  *
 618  * \retval -ve failure, e.g., cl_page was destroyed (and landed in
 619  *             cl_page_state::CPS_FREEING instead of cl_page_state::CPS_CACHED).
 620  *             or, page was owned by another thread, or in IO.
 621  *
 622  * \see cl_page_disown()
 623  * \see cl_page_operations::cpo_own()
 624  * \see cl_page_own_try()
 625  * \see cl_page_own
 626  */
 627 static int cl_page_own0(const struct lu_env *env, struct cl_io *io,
 628                         struct cl_page *cl_page, int nonblock)
 629 {
 630         const struct cl_page_slice *slice;
 631         int result = 0;
 632         int i;
 633
 634         ENTRY;
 635         PINVRNT(env, cl_page, !cl_page_is_owned(cl_page, io));
 636         io = cl_io_top(io);
 637
 638         if (cl_page->cp_state == CPS_FREEING) {
 639                 result = -ENOENT;
 640                 goto out;
 641         }
 642
 643         cl_page_slice_for_each(cl_page, slice, i) {
 644                 if (slice->cpl_ops->cpo_own)
 645                         result = (*slice->cpl_ops->cpo_own)(env, slice,
 646                                                             io, nonblock);
 647                 if (result != 0)
 648                         break;
 649         }
 650         if (result > 0)
 651                 result = 0;
 652
 653         if (result == 0) {
 654                 PASSERT(env, cl_page, cl_page->cp_owner == NULL);
 655                 cl_page->cp_owner = cl_io_top(io);
 656                 cl_page_owner_set(cl_page);
 657                 if (cl_page->cp_state != CPS_FREEING) {
 658                         cl_page_state_set(env, cl_page, CPS_OWNED);
 659                 } else {
 660                         cl_page_disown0(env, io, cl_page);
 661                         result = -ENOENT;
 662                 }
 663         }
 664
 665 out:
 666         PINVRNT(env, cl_page, ergo(result == 0,
 667                 cl_page_invariant(cl_page)));
 668         RETURN(result);
 669 }
 670
 671 /**
 672  * Own a page, might be blocked.
 673  *
 674  * \see cl_page_own0()
 675  */
 676 int cl_page_own(const struct lu_env *env, struct cl_io *io, struct cl_page *pg)
 677 {
 678         return cl_page_own0(env, io, pg, 0);
 679 }
 680 EXPORT_SYMBOL(cl_page_own);
 681
 682 /**
 683  * Nonblock version of cl_page_own().
 684  *
 685  * \see cl_page_own0()
 686  */
 687 int cl_page_own_try(const struct lu_env *env, struct cl_io *io,
 688                     struct cl_page *pg)
 689 {
 690         return cl_page_own0(env, io, pg, 1);
 691 }
 692 EXPORT_SYMBOL(cl_page_own_try);
 693
 694
 695 /**
 696  * Assume page ownership.
 697  *
 698  * Called when page is already locked by the hosting VM.
 699  *
 700  * \pre !cl_page_is_owned(cl_page, io)
 701  * \post cl_page_is_owned(cl_page, io)
 702  *
 703  * \see cl_page_operations::cpo_assume()
 704  */
 705 void cl_page_assume(const struct lu_env *env,
 706                     struct cl_io *io, struct cl_page *cl_page)
 707 {
 708         const struct cl_page_slice *slice;
 709         int i;
 710
 711         ENTRY;
 712
 713         PINVRNT(env, cl_page,
 714                 cl_object_same(cl_page->cp_obj, io->ci_obj));
 715         io = cl_io_top(io);
 716
 717         cl_page_slice_for_each(cl_page, slice, i) {
 718                 if (slice->cpl_ops->cpo_assume != NULL)
 719                         (*slice->cpl_ops->cpo_assume)(env, slice, io);
 720         }
 721
 722         PASSERT(env, cl_page, cl_page->cp_owner == NULL);
 723         cl_page->cp_owner = cl_io_top(io);
 724         cl_page_owner_set(cl_page);
 725         cl_page_state_set(env, cl_page, CPS_OWNED);
 726         EXIT;
 727 }
 728 EXPORT_SYMBOL(cl_page_assume);
 729
 730 /**
 731  * Releases page ownership without unlocking the page.
 732  *
 733  * Moves cl_page into cl_page_state::CPS_CACHED without releasing a lock
 734  * on the underlying VM page (as VM is supposed to do this itself).
 735  *
 736  * \pre   cl_page_is_owned(cl_page, io)
 737  * \post !cl_page_is_owned(cl_page, io)
 738  *
 739  * \see cl_page_assume()
 740  */
 741 void cl_page_unassume(const struct lu_env *env,
 742                       struct cl_io *io, struct cl_page *cl_page)
 743 {
 744         const struct cl_page_slice *slice;
 745         int i;
 746
 747         ENTRY;
 748         PINVRNT(env, cl_page, cl_page_is_owned(cl_page, io));
 749         PINVRNT(env, cl_page, cl_page_invariant(cl_page));
 750
 751         io = cl_io_top(io);
 752         cl_page_owner_clear(cl_page);
 753         cl_page_state_set(env, cl_page, CPS_CACHED);
 754
 755         cl_page_slice_for_each_reverse(cl_page, slice, i) {
 756                 if (slice->cpl_ops->cpo_unassume != NULL)
 757                         (*slice->cpl_ops->cpo_unassume)(env, slice, io);
 758         }
 759
 760         EXIT;
 761 }
 762 EXPORT_SYMBOL(cl_page_unassume);
 763
 764 /**
 765  * Releases page ownership.
 766  *
 767  * Moves page into cl_page_state::CPS_CACHED.
 768  *
 769  * \pre   cl_page_is_owned(pg, io)
 770  * \post !cl_page_is_owned(pg, io)
 771  *
 772  * \see cl_page_own()
 773  * \see cl_page_operations::cpo_disown()
 774  */
 775 void cl_page_disown(const struct lu_env *env,
 776                     struct cl_io *io, struct cl_page *pg)
 777 {
 778         PINVRNT(env, pg, cl_page_is_owned(pg, io) ||
 779                 pg->cp_state == CPS_FREEING);
 780
 781         ENTRY;
 782         io = cl_io_top(io);
 783         cl_page_disown0(env, io, pg);
 784         EXIT;
 785 }
 786 EXPORT_SYMBOL(cl_page_disown);
 787
 788 /**
 789  * Called when cl_page is to be removed from the object, e.g.,
 790  * as a result of truncate.
 791  *
 792  * Calls cl_page_operations::cpo_discard() top-to-bottom.
 793  *
 794  * \pre cl_page_is_owned(cl_page, io)
 795  *
 796  * \see cl_page_operations::cpo_discard()
 797  */
 798 void cl_page_discard(const struct lu_env *env,
 799                      struct cl_io *io, struct cl_page *cl_page)
 800 {
 801         const struct cl_page_slice *slice;
 802         int i;
 803
 804         PINVRNT(env, cl_page, cl_page_is_owned(cl_page, io));
 805         PINVRNT(env, cl_page, cl_page_invariant(cl_page));
 806
 807         cl_page_slice_for_each(cl_page, slice, i) {
 808                 if (slice->cpl_ops->cpo_discard != NULL)
 809                         (*slice->cpl_ops->cpo_discard)(env, slice, io);
 810         }
 811 }
 812 EXPORT_SYMBOL(cl_page_discard);
 813
 814 /**
 815  * Version of cl_page_delete() that can be called for not fully constructed
 816  * cl_pages, e.g. in an error handling cl_page_find()->cl_page_delete0()
 817  * path. Doesn't check cl_page invariant.
 818  */
 819 static void cl_page_delete0(const struct lu_env *env,
 820                             struct cl_page *cl_page)
 821 {
 822         const struct cl_page_slice *slice;
 823         int i;
 824
 825         ENTRY;
 826
 827         PASSERT(env, cl_page, cl_page->cp_state != CPS_FREEING);
 828
 829         /*
 830          * Severe all ways to obtain new pointers to @pg.
 831          */
 832         cl_page_owner_clear(cl_page);
 833         cl_page_state_set0(env, cl_page, CPS_FREEING);
 834
 835         cl_page_slice_for_each_reverse(cl_page, slice, i) {
 836                 if (slice->cpl_ops->cpo_delete != NULL)
 837                         (*slice->cpl_ops->cpo_delete)(env, slice);
 838         }
 839
 840         EXIT;
 841 }
 842
 843 /**
 844  * Called when a decision is made to throw page out of memory.
 845  *
 846  * Notifies all layers about page destruction by calling
 847  * cl_page_operations::cpo_delete() method top-to-bottom.
 848  *
 849  * Moves page into cl_page_state::CPS_FREEING state (this is the only place
 850  * where transition to this state happens).
 851  *
 852  * Eliminates all venues through which new references to the page can be
 853  * obtained:
 854  *
 855  *     - removes page from the radix trees,
 856  *
 857  *     - breaks linkage from VM page to cl_page.
 858  *
 859  * Once page reaches cl_page_state::CPS_FREEING, all remaining references will
 860  * drain after some time, at which point page will be recycled.
 861  *
 862  * \pre  VM page is locked
 863  * \post pg->cp_state == CPS_FREEING
 864  *
 865  * \see cl_page_operations::cpo_delete()
 866  */
 867 void cl_page_delete(const struct lu_env *env, struct cl_page *pg)
 868 {
 869         PINVRNT(env, pg, cl_page_invariant(pg));
 870         ENTRY;
 871         cl_page_delete0(env, pg);
 872         EXIT;
 873 }
 874 EXPORT_SYMBOL(cl_page_delete);
 875
 876 /**
 877  * Marks page up-to-date.
 878  *
 879  * Call cl_page_operations::cpo_export() through all layers top-to-bottom. The
 880  * layer responsible for VM interaction has to mark/clear page as up-to-date
 881  * by the \a uptodate argument.
 882  *
 883  * \see cl_page_operations::cpo_export()
 884  */
 885 void cl_page_export(const struct lu_env *env, struct cl_page *cl_page,
 886                     int uptodate)
 887 {
 888         const struct cl_page_slice *slice;
 889         int i;
 890
 891         PINVRNT(env, cl_page, cl_page_invariant(cl_page));
 892
 893         cl_page_slice_for_each(cl_page, slice, i) {
 894                 if (slice->cpl_ops->cpo_export != NULL)
 895                         (*slice->cpl_ops->cpo_export)(env, slice, uptodate);
 896         }
 897 }
 898 EXPORT_SYMBOL(cl_page_export);
 899
 900 /**
 901  * Returns true, if \a page is VM locked in a suitable sense by the calling
 902  * thread.
 903  */
 904 int cl_page_is_vmlocked(const struct lu_env *env,
 905                         const struct cl_page *cl_page)
 906 {
 907         const struct cl_page_slice *slice;
 908         int result;
 909
 910         ENTRY;
 911         slice = cl_page_slice_get(cl_page, 0);
 912         PASSERT(env, cl_page, slice->cpl_ops->cpo_is_vmlocked != NULL);
 913         /*
 914          * Call ->cpo_is_vmlocked() directly instead of going through
 915          * CL_PAGE_INVOKE(), because cl_page_is_vmlocked() is used by
 916          * cl_page_invariant().
 917          */
 918         result = slice->cpl_ops->cpo_is_vmlocked(env, slice);
 919         PASSERT(env, cl_page, result == -EBUSY || result == -ENODATA);
 920
 921         RETURN(result == -EBUSY);
 922 }
 923 EXPORT_SYMBOL(cl_page_is_vmlocked);
 924
 925 void cl_page_touch(const struct lu_env *env,
 926                    const struct cl_page *cl_page, size_t to)
 927 {
 928         const struct cl_page_slice *slice;
 929         int i;
 930
 931         ENTRY;
 932
 933         cl_page_slice_for_each(cl_page, slice, i) {
 934                 if (slice->cpl_ops->cpo_page_touch != NULL)
 935                         (*slice->cpl_ops->cpo_page_touch)(env, slice, to);
 936         }
 937
 938         EXIT;
 939 }
 940 EXPORT_SYMBOL(cl_page_touch);
 941
 942 static enum cl_page_state cl_req_type_state(enum cl_req_type crt)
 943 {
 944         ENTRY;
 945         RETURN(crt == CRT_WRITE ? CPS_PAGEOUT : CPS_PAGEIN);
 946 }
 947
 948 static void cl_page_io_start(const struct lu_env *env,
 949                              struct cl_page *pg, enum cl_req_type crt)
 950 {
 951         /*
 952          * Page is queued for IO, change its state.
 953          */
 954         ENTRY;
 955         cl_page_owner_clear(pg);
 956         cl_page_state_set(env, pg, cl_req_type_state(crt));
 957         EXIT;
 958 }
 959
 960 /**
 961  * Prepares page for immediate transfer. cl_page_operations::cpo_prep() is
 962  * called top-to-bottom. Every layer either agrees to submit this page (by
 963  * returning 0), or requests to omit this page (by returning -EALREADY). Layer
 964  * handling interactions with the VM also has to inform VM that page is under
 965  * transfer now.
 966  */
 967 int cl_page_prep(const struct lu_env *env, struct cl_io *io,
 968                  struct cl_page *cl_page, enum cl_req_type crt)
 969 {
 970         const struct cl_page_slice *slice;
 971         int result = 0;
 972         int i;
 973
 974         PINVRNT(env, cl_page, cl_page_is_owned(cl_page, io));
 975         PINVRNT(env, cl_page, cl_page_invariant(cl_page));
 976         PINVRNT(env, cl_page, crt < CRT_NR);
 977
 978         /*
 979          * this has to be called bottom-to-top, so that llite can set up
 980          * PG_writeback without risking other layers deciding to skip this
 981          * page.
 982          */
 983         if (crt >= CRT_NR)
 984                 return -EINVAL;
 985
 986         cl_page_slice_for_each(cl_page, slice, i) {
 987                 if (slice->cpl_ops->cpo_own)
 988                         result = (*slice->cpl_ops->io[crt].cpo_prep)(env,
 989                                                                      slice,
 990                                                                      io);
 991                 if (result != 0)
 992                         break;
 993         }
 994
 995         if (result >= 0) {
 996                 result = 0;
 997                 cl_page_io_start(env, cl_page, crt);
 998         }
 999
1000         CL_PAGE_HEADER(D_TRACE, env, cl_page, "%d %d\n", crt, result);
1001         return result;
1002 }
1003 EXPORT_SYMBOL(cl_page_prep);
1004
1005 /**
1006  * Notify layers about transfer completion.
1007  *
1008  * Invoked by transfer sub-system (which is a part of osc) to notify layers
1009  * that a transfer, of which this page is a part of has completed.
1010  *
1011  * Completion call-backs are executed in the bottom-up order, so that
1012  * uppermost layer (llite), responsible for the VFS/VM interaction runs last
1013  * and can release locks safely.
1014  *
1015  * \pre  cl_page->cp_state == CPS_PAGEIN || cl_page->cp_state == CPS_PAGEOUT
1016  * \post cl_page->cl_page_state == CPS_CACHED
1017  *
1018  * \see cl_page_operations::cpo_completion()
1019  */
1020 void cl_page_completion(const struct lu_env *env,
1021                         struct cl_page *cl_page, enum cl_req_type crt,
1022                         int ioret)
1023 {
1024         const struct cl_page_slice *slice;
1025         struct cl_sync_io *anchor = cl_page->cp_sync_io;
1026         int i;
1027
1028         ENTRY;
1029         PASSERT(env, cl_page, crt < CRT_NR);
1030         PASSERT(env, cl_page, cl_page->cp_state == cl_req_type_state(crt));
1031
1032         CL_PAGE_HEADER(D_TRACE, env, cl_page, "%d %d\n", crt, ioret);
1033         cl_page_state_set(env, cl_page, CPS_CACHED);
1034         if (crt >= CRT_NR)
1035                 return;
1036
1037         cl_page_slice_for_each_reverse(cl_page, slice, i) {
1038                 if (slice->cpl_ops->io[crt].cpo_completion != NULL)
1039                         (*slice->cpl_ops->io[crt].cpo_completion)(env, slice,
1040                                                                   ioret);
1041         }
1042
1043         if (anchor != NULL) {
1044                 LASSERT(cl_page->cp_sync_io == anchor);
1045                 cl_page->cp_sync_io = NULL;
1046                 cl_sync_io_note(env, anchor, ioret);
1047         }
1048         EXIT;
1049 }
1050 EXPORT_SYMBOL(cl_page_completion);
1051
1052 /**
1053  * Notify layers that transfer formation engine decided to yank this page from
1054  * the cache and to make it a part of a transfer.
1055  *
1056  * \pre  cl_page->cp_state == CPS_CACHED
1057  * \post cl_page->cp_state == CPS_PAGEIN || cl_page->cp_state == CPS_PAGEOUT
1058  *
1059  * \see cl_page_operations::cpo_make_ready()
1060  */
1061 int cl_page_make_ready(const struct lu_env *env, struct cl_page *cl_page,
1062                        enum cl_req_type crt)
1063 {
1064         const struct cl_page_slice *slice;
1065         int result = 0;
1066         int i;
1067
1068         ENTRY;
1069         PINVRNT(env, cl_page, crt < CRT_NR);
1070         if (crt >= CRT_NR)
1071                 RETURN(-EINVAL);
1072
1073         cl_page_slice_for_each(cl_page, slice, i) {
1074                 if (slice->cpl_ops->io[crt].cpo_make_ready != NULL)
1075                         result = (*slice->cpl_ops->io[crt].cpo_make_ready)(env, slice);
1076                 if (result != 0)
1077                         break;
1078         }
1079
1080         if (result >= 0) {
1081                 result = 0;
1082                 PASSERT(env, cl_page, cl_page->cp_state == CPS_CACHED);
1083                 cl_page_io_start(env, cl_page, crt);
1084         }
1085         CL_PAGE_HEADER(D_TRACE, env, cl_page, "%d %d\n", crt, result);
1086
1087         RETURN(result);
1088 }
1089 EXPORT_SYMBOL(cl_page_make_ready);
1090
1091 /**
1092  * Called if a page is being written back by kernel's intention.
1093  *
1094  * \pre  cl_page_is_owned(cl_page, io)
1095  * \post ergo(result == 0, cl_page->cp_state == CPS_PAGEOUT)
1096  *
1097  * \see cl_page_operations::cpo_flush()
1098  */
1099 int cl_page_flush(const struct lu_env *env, struct cl_io *io,
1100                   struct cl_page *cl_page)
1101 {
1102         const struct cl_page_slice *slice;
1103         int result = 0;
1104         int i;
1105
1106         ENTRY;
1107         PINVRNT(env, cl_page, cl_page_is_owned(cl_page, io));
1108         PINVRNT(env, cl_page, cl_page_invariant(cl_page));
1109
1110         cl_page_slice_for_each(cl_page, slice, i) {
1111                 if (slice->cpl_ops->cpo_flush != NULL)
1112                         result = (*slice->cpl_ops->cpo_flush)(env, slice, io);
1113                 if (result != 0)
1114                         break;
1115         }
1116         if (result > 0)
1117                 result = 0;
1118
1119         CL_PAGE_HEADER(D_TRACE, env, cl_page, "%d\n", result);
1120         RETURN(result);
1121 }
1122 EXPORT_SYMBOL(cl_page_flush);
1123
1124 /**
1125  * Tells transfer engine that only part of a page is to be transmitted.
1126  *
1127  * \see cl_page_operations::cpo_clip()
1128  */
1129 void cl_page_clip(const struct lu_env *env, struct cl_page *cl_page,
1130                   int from, int to)
1131 {
1132         const struct cl_page_slice *slice;
1133         int i;
1134
1135         PINVRNT(env, cl_page, cl_page_invariant(cl_page));
1136
1137         CL_PAGE_HEADER(D_TRACE, env, cl_page, "%d %d\n", from, to);
1138         cl_page_slice_for_each(cl_page, slice, i) {
1139                 if (slice->cpl_ops->cpo_clip != NULL)
1140                         (*slice->cpl_ops->cpo_clip)(env, slice, from, to);
1141         }
1142 }
1143 EXPORT_SYMBOL(cl_page_clip);
1144
1145 /**
1146  * Prints human readable representation of \a pg to the \a f.
1147  */
1148 void cl_page_header_print(const struct lu_env *env, void *cookie,
1149                           lu_printer_t printer, const struct cl_page *pg)
1150 {
1151         (*printer)(env, cookie,
1152                    "page@%p[%d %p %d %d %p]\n",
1153                    pg, atomic_read(&pg->cp_ref), pg->cp_obj,
1154                    pg->cp_state, pg->cp_type,
1155                    pg->cp_owner);
1156 }
1157 EXPORT_SYMBOL(cl_page_header_print);
1158
1159 /**
1160  * Prints human readable representation of \a cl_page to the \a f.
1161  */
1162 void cl_page_print(const struct lu_env *env, void *cookie,
1163                    lu_printer_t printer, const struct cl_page *cl_page)
1164 {
1165         const struct cl_page_slice *slice;
1166         int result = 0;
1167         int i;
1168
1169         cl_page_header_print(env, cookie, printer, cl_page);
1170         cl_page_slice_for_each(cl_page, slice, i) {
1171                 if (slice->cpl_ops->cpo_print != NULL)
1172                         result = (*slice->cpl_ops->cpo_print)(env, slice,
1173                                                              cookie, printer);
1174                 if (result != 0)
1175                         break;
1176         }
1177         (*printer)(env, cookie, "end page@%p\n", cl_page);
1178 }
1179 EXPORT_SYMBOL(cl_page_print);
1180
1181 /**
1182  * Converts a byte offset within object \a obj into a page index.
1183  */
1184 loff_t cl_offset(const struct cl_object *obj, pgoff_t idx)
1185 {
1186         return (loff_t)idx << PAGE_SHIFT;
1187 }
1188 EXPORT_SYMBOL(cl_offset);
1189
1190 /**
1191  * Converts a page index into a byte offset within object \a obj.
1192  */
1193 pgoff_t cl_index(const struct cl_object *obj, loff_t offset)
1194 {
1195         return offset >> PAGE_SHIFT;
1196 }
1197 EXPORT_SYMBOL(cl_index);
1198
1199 size_t cl_page_size(const struct cl_object *obj)
1200 {
1201         return 1UL << PAGE_SHIFT;
1202 }
1203 EXPORT_SYMBOL(cl_page_size);
1204
1205 /**
1206  * Adds page slice to the compound page.
1207  *
1208  * This is called by cl_object_operations::coo_page_init() methods to add a
1209  * per-layer state to the page. New state is added at the end of
1210  * cl_page::cp_layers list, that is, it is at the bottom of the stack.
1211  *
1212  * \see cl_lock_slice_add(), cl_req_slice_add(), cl_io_slice_add()
1213  */
1214 void cl_page_slice_add(struct cl_page *cl_page, struct cl_page_slice *slice,
1215                        struct cl_object *obj,
1216                        const struct cl_page_operations *ops)
1217 {
1218         unsigned int offset = (char *)slice -
1219                         ((char *)cl_page + sizeof(*cl_page));
1220
1221         ENTRY;
1222         LASSERT(cl_page->cp_layer_count < CP_MAX_LAYER);
1223         LASSERT(offset < (1 << sizeof(cl_page->cp_layer_offset[0]) * 8));
1224         cl_page->cp_layer_offset[cl_page->cp_layer_count++] = offset;
1225         slice->cpl_obj  = obj;
1226         slice->cpl_ops  = ops;
1227         slice->cpl_page = cl_page;
1228
1229         EXIT;
1230 }
1231 EXPORT_SYMBOL(cl_page_slice_add);
1232
1233 /**
1234  * Allocate and initialize cl_cache, called by ll_init_sbi().
1235  */
1236 struct cl_client_cache *cl_cache_init(unsigned long lru_page_max)
1237 {
1238         struct cl_client_cache  *cache = NULL;
1239
1240         ENTRY;
1241         OBD_ALLOC(cache, sizeof(*cache));
1242         if (cache == NULL)
1243                 RETURN(NULL);
1244
1245         /* Initialize cache data */
1246         atomic_set(&cache->ccc_users, 1);
1247         cache->ccc_lru_max = lru_page_max;
1248         atomic_long_set(&cache->ccc_lru_left, lru_page_max);
1249         spin_lock_init(&cache->ccc_lru_lock);
1250         INIT_LIST_HEAD(&cache->ccc_lru);
1251
1252         /* turn unstable check off by default as it impacts performance */
1253         cache->ccc_unstable_check = 0;
1254         atomic_long_set(&cache->ccc_unstable_nr, 0);
1255         init_waitqueue_head(&cache->ccc_unstable_waitq);
1256         mutex_init(&cache->ccc_max_cache_mb_lock);
1257
1258         RETURN(cache);
1259 }
1260 EXPORT_SYMBOL(cl_cache_init);
1261
1262 /**
1263  * Increase cl_cache refcount
1264  */
1265 void cl_cache_incref(struct cl_client_cache *cache)
1266 {
1267         atomic_inc(&cache->ccc_users);
1268 }
1269 EXPORT_SYMBOL(cl_cache_incref);
1270
1271 /**
1272  * Decrease cl_cache refcount and free the cache if refcount=0.
1273  * Since llite, lov and osc all hold cl_cache refcount,
1274  * the free will not cause race. (LU-6173)
1275  */
1276 void cl_cache_decref(struct cl_client_cache *cache)
1277 {
1278         if (atomic_dec_and_test(&cache->ccc_users))
1279                 OBD_FREE(cache, sizeof(*cache));
1280 }
1281 EXPORT_SYMBOL(cl_cache_decref);