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.sun.com/software/products/lustre/docs/GPLv2.pdf
  19  *
  20  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
  21  * CA 95054 USA or visit www.sun.com if you need additional information or
  22  * have any questions.
  23  *
  24  * GPL HEADER END
  25  */
  26 /*
  27  * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
  28  * Use is subject to license terms.
  29  *
  30  * Copyright (c) 2011, 2013, Intel Corporation.
  31  */
  32 /*
  33  * This file is part of Lustre, http://www.lustre.org/
  34  * Lustre is a trademark of Sun Microsystems, Inc.
  35  *
  36  * Client Lustre Page.
  37  *
  38  *   Author: Nikita Danilov <nikita.danilov@sun.com>
  39  *   Author: Jinshan Xiong <jinshan.xiong@intel.com>
  40  */
  41
  42 #define DEBUG_SUBSYSTEM S_CLASS
  43
  44 #include <libcfs/libcfs.h>
  45 #include <obd_class.h>
  46 #include <obd_support.h>
  47 #include <libcfs/list.h>
  48
  49 #include <cl_object.h>
  50 #include "cl_internal.h"
  51
  52 static void cl_page_delete0(const struct lu_env *env, struct cl_page *pg);
  53
  54 #ifdef LIBCFS_DEBUG
  55 # define PASSERT(env, page, expr)                                       \
  56   do {                                                                    \
  57           if (unlikely(!(expr))) {                                      \
  58                   CL_PAGE_DEBUG(D_ERROR, (env), (page), #expr "\n");    \
  59                   LASSERT(0);                                           \
  60           }                                                             \
  61   } while (0)
  62 #else /* !LIBCFS_DEBUG */
  63 # define PASSERT(env, page, exp) \
  64         ((void)sizeof(env), (void)sizeof(page), (void)sizeof !!(exp))
  65 #endif /* !LIBCFS_DEBUG */
  66
  67 #ifdef CONFIG_LUSTRE_DEBUG_EXPENSIVE_CHECK
  68 # define PINVRNT(env, page, expr)                                       \
  69   do {                                                                    \
  70           if (unlikely(!(expr))) {                                      \
  71                   CL_PAGE_DEBUG(D_ERROR, (env), (page), #expr "\n");    \
  72                   LINVRNT(0);                                           \
  73           }                                                             \
  74   } while (0)
  75 #else /* !CONFIG_LUSTRE_DEBUG_EXPENSIVE_CHECK */
  76 # define PINVRNT(env, page, exp) \
  77          ((void)sizeof(env), (void)sizeof(page), (void)sizeof !!(exp))
  78 #endif /* !CONFIG_LUSTRE_DEBUG_EXPENSIVE_CHECK */
  79
  80 /* Disable page statistic by default due to huge performance penalty. */
  81 #ifdef CONFIG_DEBUG_PAGESTATE_TRACKING
  82 #define CS_PAGE_INC(o, item) \
  83         cfs_atomic_inc(&cl_object_site(o)->cs_pages.cs_stats[CS_##item])
  84 #define CS_PAGE_DEC(o, item) \
  85         cfs_atomic_dec(&cl_object_site(o)->cs_pages.cs_stats[CS_##item])
  86 #define CS_PAGESTATE_INC(o, state) \
  87         cfs_atomic_inc(&cl_object_site(o)->cs_pages_state[state])
  88 #define CS_PAGESTATE_DEC(o, state) \
  89         cfs_atomic_dec(&cl_object_site(o)->cs_pages_state[state])
  90 #else
  91 #define CS_PAGE_INC(o, item)
  92 #define CS_PAGE_DEC(o, item)
  93 #define CS_PAGESTATE_INC(o, state)
  94 #define CS_PAGESTATE_DEC(o, state)
  95 #endif
  96
  97 /**
  98  * Internal version of cl_page_top, it should be called if the page is
  99  * known to be not freed, says with page referenced, or radix tree lock held,
 100  * or page owned.
 101  */
 102 static struct cl_page *cl_page_top_trusted(struct cl_page *page)
 103 {
 104         while (page->cp_parent != NULL)
 105                 page = page->cp_parent;
 106         return page;
 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(cfs_atomic_read(&page->cp_ref) > 0);
 122         cfs_atomic_inc(&page->cp_ref);
 123 }
 124
 125 /**
 126  * Returns a slice within a page, corresponding to the given layer in the
 127  * device stack.
 128  *
 129  * \see cl_lock_at()
 130  */
 131 static const struct cl_page_slice *
 132 cl_page_at_trusted(const struct cl_page *page,
 133                    const struct lu_device_type *dtype)
 134 {
 135         const struct cl_page_slice *slice;
 136         ENTRY;
 137
 138         page = cl_page_top_trusted((struct cl_page *)page);
 139         do {
 140                 cfs_list_for_each_entry(slice, &page->cp_layers, cpl_linkage) {
 141                         if (slice->cpl_obj->co_lu.lo_dev->ld_type == dtype)
 142                                 RETURN(slice);
 143                 }
 144                 page = page->cp_child;
 145         } while (page != NULL);
 146         RETURN(NULL);
 147 }
 148
 149 static void cl_page_free(const struct lu_env *env, struct cl_page *page)
 150 {
 151         struct cl_object *obj  = page->cp_obj;
 152         int pagesize = cl_object_header(obj)->coh_page_bufsize;
 153
 154         PASSERT(env, page, cfs_list_empty(&page->cp_batch));
 155         PASSERT(env, page, page->cp_owner == NULL);
 156         PASSERT(env, page, page->cp_req == NULL);
 157         PASSERT(env, page, page->cp_parent == NULL);
 158         PASSERT(env, page, page->cp_state == CPS_FREEING);
 159
 160         ENTRY;
 161         while (!cfs_list_empty(&page->cp_layers)) {
 162                 struct cl_page_slice *slice;
 163
 164                 slice = cfs_list_entry(page->cp_layers.next,
 165                                        struct cl_page_slice, cpl_linkage);
 166                 cfs_list_del_init(page->cp_layers.next);
 167                 slice->cpl_ops->cpo_fini(env, slice);
 168         }
 169         CS_PAGE_DEC(obj, total);
 170         CS_PAGESTATE_DEC(obj, page->cp_state);
 171         lu_object_ref_del_at(&obj->co_lu, &page->cp_obj_ref, "cl_page", page);
 172         cl_object_put(env, obj);
 173         lu_ref_fini(&page->cp_reference);
 174         OBD_FREE(page, pagesize);
 175         EXIT;
 176 }
 177
 178 /**
 179  * Helper function updating page state. This is the only place in the code
 180  * where cl_page::cp_state field is mutated.
 181  */
 182 static inline void cl_page_state_set_trust(struct cl_page *page,
 183                                            enum cl_page_state state)
 184 {
 185         /* bypass const. */
 186         *(enum cl_page_state *)&page->cp_state = state;
 187 }
 188
 189 struct cl_page *cl_page_alloc(const struct lu_env *env,
 190                 struct cl_object *o, pgoff_t ind, struct page *vmpage,
 191                 enum cl_page_type type)
 192 {
 193         struct cl_page          *page;
 194         struct lu_object_header *head;
 195
 196         ENTRY;
 197         OBD_ALLOC_GFP(page, cl_object_header(o)->coh_page_bufsize,
 198                         __GFP_IO);
 199         if (page != NULL) {
 200                 int result = 0;
 201                 cfs_atomic_set(&page->cp_ref, 1);
 202                 page->cp_obj = o;
 203                 cl_object_get(o);
 204                 lu_object_ref_add_at(&o->co_lu, &page->cp_obj_ref, "cl_page",
 205                                      page);
 206                 page->cp_index = ind;
 207                 cl_page_state_set_trust(page, CPS_CACHED);
 208                 page->cp_type = type;
 209                 CFS_INIT_LIST_HEAD(&page->cp_layers);
 210                 CFS_INIT_LIST_HEAD(&page->cp_batch);
 211                 CFS_INIT_LIST_HEAD(&page->cp_flight);
 212                 mutex_init(&page->cp_mutex);
 213                 lu_ref_init(&page->cp_reference);
 214                 head = o->co_lu.lo_header;
 215                 cfs_list_for_each_entry(o, &head->loh_layers,
 216                                         co_lu.lo_linkage) {
 217                         if (o->co_ops->coo_page_init != NULL) {
 218                                 result = o->co_ops->coo_page_init(env, o,
 219                                                                   page, vmpage);
 220                                 if (result != 0) {
 221                                         cl_page_delete0(env, page);
 222                                         cl_page_free(env, page);
 223                                         page = ERR_PTR(result);
 224                                         break;
 225                                 }
 226                         }
 227                 }
 228                 if (result == 0) {
 229                         CS_PAGE_INC(o, total);
 230                         CS_PAGE_INC(o, create);
 231                         CS_PAGESTATE_DEC(o, CPS_CACHED);
 232                 }
 233         } else {
 234                 page = ERR_PTR(-ENOMEM);
 235         }
 236         RETURN(page);
 237 }
 238 EXPORT_SYMBOL(cl_page_alloc);
 239
 240 /**
 241  * Returns a cl_page with index \a idx at the object \a o, and associated with
 242  * the VM page \a vmpage.
 243  *
 244  * This is the main entry point into the cl_page caching interface. First, a
 245  * cache (implemented as a per-object radix tree) is consulted. If page is
 246  * found there, it is returned immediately. Otherwise new page is allocated
 247  * and returned. In any case, additional reference to page is acquired.
 248  *
 249  * \see cl_object_find(), cl_lock_find()
 250  */
 251 struct cl_page *cl_page_find(const struct lu_env *env,
 252                              struct cl_object *o,
 253                              pgoff_t idx, struct page *vmpage,
 254                              enum cl_page_type type)
 255 {
 256         struct cl_page          *page = NULL;
 257         struct cl_object_header *hdr;
 258
 259         LASSERT(type == CPT_CACHEABLE || type == CPT_TRANSIENT);
 260         might_sleep();
 261
 262         ENTRY;
 263
 264         hdr = cl_object_header(o);
 265         CS_PAGE_INC(o, lookup);
 266
 267         CDEBUG(D_PAGE, "%lu@"DFID" %p %lx %d\n",
 268                idx, PFID(&hdr->coh_lu.loh_fid), vmpage, vmpage->private, type);
 269         /* fast path. */
 270         if (type == CPT_CACHEABLE) {
 271                 /* vmpage lock is used to protect the child/parent
 272                  * relationship */
 273                 KLASSERT(PageLocked(vmpage));
 274                 /*
 275                  * cl_vmpage_page() can be called here without any locks as
 276                  *
 277                  *     - "vmpage" is locked (which prevents ->private from
 278                  *       concurrent updates), and
 279                  *
 280                  *     - "o" cannot be destroyed while current thread holds a
 281                  *       reference on it.
 282                  */
 283                 page = cl_vmpage_page(vmpage, o);
 284                 if (page != NULL) {
 285                         CS_PAGE_INC(o, hit);
 286                         RETURN(page);
 287                 }
 288         }
 289
 290         /* allocate and initialize cl_page */
 291         page = cl_page_alloc(env, o, idx, vmpage, type);
 292         RETURN(page);
 293 }
 294 EXPORT_SYMBOL(cl_page_find);
 295
 296 static inline int cl_page_invariant(const struct cl_page *pg)
 297 {
 298         struct cl_page          *parent;
 299         struct cl_page          *child;
 300         struct cl_io            *owner;
 301
 302         /*
 303          * Page invariant is protected by a VM lock.
 304          */
 305         LINVRNT(cl_page_is_vmlocked(NULL, pg));
 306
 307         parent = pg->cp_parent;
 308         child  = pg->cp_child;
 309         owner  = pg->cp_owner;
 310
 311         return cl_page_in_use_noref(pg) &&
 312                 ergo(parent != NULL, parent->cp_child == pg) &&
 313                 ergo(child != NULL, child->cp_parent == pg) &&
 314                 ergo(child != NULL, pg->cp_obj != child->cp_obj) &&
 315                 ergo(parent != NULL, pg->cp_obj != parent->cp_obj) &&
 316                 ergo(owner != NULL && parent != NULL,
 317                      parent->cp_owner == pg->cp_owner->ci_parent) &&
 318                 ergo(owner != NULL && child != NULL,
 319                      child->cp_owner->ci_parent == owner);
 320 }
 321
 322 static void cl_page_state_set0(const struct lu_env *env,
 323                                struct cl_page *page, enum cl_page_state state)
 324 {
 325         enum cl_page_state old;
 326
 327         /*
 328          * Matrix of allowed state transitions [old][new], for sanity
 329          * checking.
 330          */
 331         static const int allowed_transitions[CPS_NR][CPS_NR] = {
 332                 [CPS_CACHED] = {
 333                         [CPS_CACHED]  = 0,
 334                         [CPS_OWNED]   = 1, /* io finds existing cached page */
 335                         [CPS_PAGEIN]  = 0,
 336                         [CPS_PAGEOUT] = 1, /* write-out from the cache */
 337                         [CPS_FREEING] = 1, /* eviction on the memory pressure */
 338                 },
 339                 [CPS_OWNED] = {
 340                         [CPS_CACHED]  = 1, /* release to the cache */
 341                         [CPS_OWNED]   = 0,
 342                         [CPS_PAGEIN]  = 1, /* start read immediately */
 343                         [CPS_PAGEOUT] = 1, /* start write immediately */
 344                         [CPS_FREEING] = 1, /* lock invalidation or truncate */
 345                 },
 346                 [CPS_PAGEIN] = {
 347                         [CPS_CACHED]  = 1, /* io completion */
 348                         [CPS_OWNED]   = 0,
 349                         [CPS_PAGEIN]  = 0,
 350                         [CPS_PAGEOUT] = 0,
 351                         [CPS_FREEING] = 0,
 352                 },
 353                 [CPS_PAGEOUT] = {
 354                         [CPS_CACHED]  = 1, /* io completion */
 355                         [CPS_OWNED]   = 0,
 356                         [CPS_PAGEIN]  = 0,
 357                         [CPS_PAGEOUT] = 0,
 358                         [CPS_FREEING] = 0,
 359                 },
 360                 [CPS_FREEING] = {
 361                         [CPS_CACHED]  = 0,
 362                         [CPS_OWNED]   = 0,
 363                         [CPS_PAGEIN]  = 0,
 364                         [CPS_PAGEOUT] = 0,
 365                         [CPS_FREEING] = 0,
 366                 }
 367         };
 368
 369         ENTRY;
 370         old = page->cp_state;
 371         PASSERT(env, page, allowed_transitions[old][state]);
 372         CL_PAGE_HEADER(D_TRACE, env, page, "%d -> %d\n", old, state);
 373         for (; page != NULL; page = page->cp_child) {
 374                 PASSERT(env, page, page->cp_state == old);
 375                 PASSERT(env, page,
 376                         equi(state == CPS_OWNED, page->cp_owner != NULL));
 377
 378                 CS_PAGESTATE_DEC(page->cp_obj, page->cp_state);
 379                 CS_PAGESTATE_INC(page->cp_obj, state);
 380                 cl_page_state_set_trust(page, state);
 381         }
 382         EXIT;
 383 }
 384
 385 static void cl_page_state_set(const struct lu_env *env,
 386                               struct cl_page *page, enum cl_page_state state)
 387 {
 388         cl_page_state_set0(env, page, state);
 389 }
 390
 391 /**
 392  * Acquires an additional reference to a page.
 393  *
 394  * This can be called only by caller already possessing a reference to \a
 395  * page.
 396  *
 397  * \see cl_object_get(), cl_lock_get().
 398  */
 399 void cl_page_get(struct cl_page *page)
 400 {
 401         ENTRY;
 402         cl_page_get_trust(page);
 403         EXIT;
 404 }
 405 EXPORT_SYMBOL(cl_page_get);
 406
 407 /**
 408  * Releases a reference to a page.
 409  *
 410  * When last reference is released, page is returned to the cache, unless it
 411  * is in cl_page_state::CPS_FREEING state, in which case it is immediately
 412  * destroyed.
 413  *
 414  * \see cl_object_put(), cl_lock_put().
 415  */
 416 void cl_page_put(const struct lu_env *env, struct cl_page *page)
 417 {
 418         PASSERT(env, page, cfs_atomic_read(&page->cp_ref) > !!page->cp_parent);
 419
 420         ENTRY;
 421         CL_PAGE_HEADER(D_TRACE, env, page, "%d\n",
 422                        cfs_atomic_read(&page->cp_ref));
 423
 424         if (cfs_atomic_dec_and_test(&page->cp_ref)) {
 425                 LASSERT(page->cp_state == CPS_FREEING);
 426
 427                 LASSERT(cfs_atomic_read(&page->cp_ref) == 0);
 428                 PASSERT(env, page, page->cp_owner == NULL);
 429                 PASSERT(env, page, cfs_list_empty(&page->cp_batch));
 430                 /*
 431                  * Page is no longer reachable by other threads. Tear
 432                  * it down.
 433                  */
 434                 cl_page_free(env, page);
 435         }
 436
 437         EXIT;
 438 }
 439 EXPORT_SYMBOL(cl_page_put);
 440
 441 /**
 442  * Returns a VM page associated with a given cl_page.
 443  */
 444 struct page *cl_page_vmpage(const struct lu_env *env, struct cl_page *page)
 445 {
 446         const struct cl_page_slice *slice;
 447
 448         /*
 449          * Find uppermost layer with ->cpo_vmpage() method, and return its
 450          * result.
 451          */
 452         page = cl_page_top(page);
 453         do {
 454                 cfs_list_for_each_entry(slice, &page->cp_layers, cpl_linkage) {
 455                         if (slice->cpl_ops->cpo_vmpage != NULL)
 456                                 RETURN(slice->cpl_ops->cpo_vmpage(env, slice));
 457                 }
 458                 page = page->cp_child;
 459         } while (page != NULL);
 460         LBUG(); /* ->cpo_vmpage() has to be defined somewhere in the stack */
 461 }
 462 EXPORT_SYMBOL(cl_page_vmpage);
 463
 464 /**
 465  * Returns a cl_page associated with a VM page, and given cl_object.
 466  */
 467 struct cl_page *cl_vmpage_page(struct page *vmpage, struct cl_object *obj)
 468 {
 469         struct cl_page *top;
 470         struct cl_page *page;
 471
 472         ENTRY;
 473         KLASSERT(PageLocked(vmpage));
 474
 475         /*
 476          * NOTE: absence of races and liveness of data are guaranteed by page
 477          *       lock on a "vmpage". That works because object destruction has
 478          *       bottom-to-top pass.
 479          */
 480
 481         /*
 482          * This loop assumes that ->private points to the top-most page. This
 483          * can be rectified easily.
 484          */
 485         top = (struct cl_page *)vmpage->private;
 486         if (top == NULL)
 487                 RETURN(NULL);
 488
 489         for (page = top; page != NULL; page = page->cp_child) {
 490                 if (cl_object_same(page->cp_obj, obj)) {
 491                         cl_page_get_trust(page);
 492                         break;
 493                 }
 494         }
 495         LASSERT(ergo(page, page->cp_type == CPT_CACHEABLE));
 496         RETURN(page);
 497 }
 498 EXPORT_SYMBOL(cl_vmpage_page);
 499
 500 /**
 501  * Returns the top-page for a given page.
 502  *
 503  * \see cl_object_top(), cl_io_top()
 504  */
 505 struct cl_page *cl_page_top(struct cl_page *page)
 506 {
 507         return cl_page_top_trusted(page);
 508 }
 509 EXPORT_SYMBOL(cl_page_top);
 510
 511 const struct cl_page_slice *cl_page_at(const struct cl_page *page,
 512                                        const struct lu_device_type *dtype)
 513 {
 514         return cl_page_at_trusted(page, dtype);
 515 }
 516 EXPORT_SYMBOL(cl_page_at);
 517
 518 #define CL_PAGE_OP(opname) offsetof(struct cl_page_operations, opname)
 519
 520 #define CL_PAGE_INVOKE(_env, _page, _op, _proto, ...)                   \
 521 ({                                                                      \
 522         const struct lu_env        *__env  = (_env);                    \
 523         struct cl_page             *__page = (_page);                   \
 524         const struct cl_page_slice *__scan;                             \
 525         int                         __result;                           \
 526         ptrdiff_t                   __op   = (_op);                     \
 527         int                       (*__method)_proto;                    \
 528                                                                         \
 529         __result = 0;                                                   \
 530         __page = cl_page_top(__page);                                   \
 531         do {                                                            \
 532                 cfs_list_for_each_entry(__scan, &__page->cp_layers,     \
 533                                         cpl_linkage) {                  \
 534                         __method = *(void **)((char *)__scan->cpl_ops + \
 535                                               __op);                    \
 536                         if (__method != NULL) {                         \
 537                                 __result = (*__method)(__env, __scan,   \
 538                                                        ## __VA_ARGS__); \
 539                                 if (__result != 0)                      \
 540                                         break;                          \
 541                         }                                               \
 542                 }                                                       \
 543                 __page = __page->cp_child;                              \
 544         } while (__page != NULL && __result == 0);                      \
 545         if (__result > 0)                                               \
 546                 __result = 0;                                           \
 547         __result;                                                       \
 548 })
 549
 550 #define CL_PAGE_INVOID(_env, _page, _op, _proto, ...)                   \
 551 do {                                                                    \
 552         const struct lu_env        *__env  = (_env);                    \
 553         struct cl_page             *__page = (_page);                   \
 554         const struct cl_page_slice *__scan;                             \
 555         ptrdiff_t                   __op   = (_op);                     \
 556         void                      (*__method)_proto;                    \
 557                                                                         \
 558         __page = cl_page_top(__page);                                   \
 559         do {                                                            \
 560                 cfs_list_for_each_entry(__scan, &__page->cp_layers,     \
 561                                         cpl_linkage) {                  \
 562                         __method = *(void **)((char *)__scan->cpl_ops + \
 563                                               __op);                    \
 564                         if (__method != NULL)                           \
 565                                 (*__method)(__env, __scan,              \
 566                                             ## __VA_ARGS__);            \
 567                 }                                                       \
 568                 __page = __page->cp_child;                              \
 569         } while (__page != NULL);                                       \
 570 } while (0)
 571
 572 #define CL_PAGE_INVOID_REVERSE(_env, _page, _op, _proto, ...)               \
 573 do {                                                                        \
 574         const struct lu_env        *__env  = (_env);                        \
 575         struct cl_page             *__page = (_page);                       \
 576         const struct cl_page_slice *__scan;                                 \
 577         ptrdiff_t                   __op   = (_op);                         \
 578         void                      (*__method)_proto;                        \
 579                                                                             \
 580         /* get to the bottom page. */                                       \
 581         while (__page->cp_child != NULL)                                    \
 582                 __page = __page->cp_child;                                  \
 583         do {                                                                \
 584                 cfs_list_for_each_entry_reverse(__scan, &__page->cp_layers, \
 585                                                 cpl_linkage) {              \
 586                         __method = *(void **)((char *)__scan->cpl_ops +     \
 587                                               __op);                        \
 588                         if (__method != NULL)                               \
 589                                 (*__method)(__env, __scan,                  \
 590                                             ## __VA_ARGS__);                \
 591                 }                                                           \
 592                 __page = __page->cp_parent;                                 \
 593         } while (__page != NULL);                                           \
 594 } while (0)
 595
 596 static int cl_page_invoke(const struct lu_env *env,
 597                           struct cl_io *io, struct cl_page *page, ptrdiff_t op)
 598
 599 {
 600         PINVRNT(env, page, cl_object_same(page->cp_obj, io->ci_obj));
 601         ENTRY;
 602         RETURN(CL_PAGE_INVOKE(env, page, op,
 603                               (const struct lu_env *,
 604                                const struct cl_page_slice *, struct cl_io *),
 605                               io));
 606 }
 607
 608 static void cl_page_invoid(const struct lu_env *env,
 609                            struct cl_io *io, struct cl_page *page, ptrdiff_t op)
 610
 611 {
 612         PINVRNT(env, page, cl_object_same(page->cp_obj, io->ci_obj));
 613         ENTRY;
 614         CL_PAGE_INVOID(env, page, op,
 615                        (const struct lu_env *,
 616                         const struct cl_page_slice *, struct cl_io *), io);
 617         EXIT;
 618 }
 619
 620 static void cl_page_owner_clear(struct cl_page *page)
 621 {
 622         ENTRY;
 623         for (page = cl_page_top(page); page != NULL; page = page->cp_child) {
 624                 if (page->cp_owner != NULL) {
 625                         LASSERT(page->cp_owner->ci_owned_nr > 0);
 626                         page->cp_owner->ci_owned_nr--;
 627                         page->cp_owner = NULL;
 628                         page->cp_task = NULL;
 629                 }
 630         }
 631         EXIT;
 632 }
 633
 634 static void cl_page_owner_set(struct cl_page *page)
 635 {
 636         ENTRY;
 637         for (page = cl_page_top(page); page != NULL; page = page->cp_child) {
 638                 LASSERT(page->cp_owner != NULL);
 639                 page->cp_owner->ci_owned_nr++;
 640         }
 641         EXIT;
 642 }
 643
 644 void cl_page_disown0(const struct lu_env *env,
 645                      struct cl_io *io, struct cl_page *pg)
 646 {
 647         enum cl_page_state state;
 648
 649         ENTRY;
 650         state = pg->cp_state;
 651         PINVRNT(env, pg, state == CPS_OWNED || state == CPS_FREEING);
 652         PINVRNT(env, pg, cl_page_invariant(pg) || state == CPS_FREEING);
 653         cl_page_owner_clear(pg);
 654
 655         if (state == CPS_OWNED)
 656                 cl_page_state_set(env, pg, CPS_CACHED);
 657         /*
 658          * Completion call-backs are executed in the bottom-up order, so that
 659          * uppermost layer (llite), responsible for VFS/VM interaction runs
 660          * last and can release locks safely.
 661          */
 662         CL_PAGE_INVOID_REVERSE(env, pg, CL_PAGE_OP(cpo_disown),
 663                                (const struct lu_env *,
 664                                 const struct cl_page_slice *, struct cl_io *),
 665                                io);
 666         EXIT;
 667 }
 668
 669 /**
 670  * returns true, iff page is owned by the given io.
 671  */
 672 int cl_page_is_owned(const struct cl_page *pg, const struct cl_io *io)
 673 {
 674         LINVRNT(cl_object_same(pg->cp_obj, io->ci_obj));
 675         ENTRY;
 676         RETURN(pg->cp_state == CPS_OWNED && pg->cp_owner == io);
 677 }
 678 EXPORT_SYMBOL(cl_page_is_owned);
 679
 680 /**
 681  * Try to own a page by IO.
 682  *
 683  * Waits until page is in cl_page_state::CPS_CACHED state, and then switch it
 684  * into cl_page_state::CPS_OWNED state.
 685  *
 686  * \pre  !cl_page_is_owned(pg, io)
 687  * \post result == 0 iff cl_page_is_owned(pg, io)
 688  *
 689  * \retval 0   success
 690  *
 691  * \retval -ve failure, e.g., page was destroyed (and landed in
 692  *             cl_page_state::CPS_FREEING instead of cl_page_state::CPS_CACHED).
 693  *             or, page was owned by another thread, or in IO.
 694  *
 695  * \see cl_page_disown()
 696  * \see cl_page_operations::cpo_own()
 697  * \see cl_page_own_try()
 698  * \see cl_page_own
 699  */
 700 static int cl_page_own0(const struct lu_env *env, struct cl_io *io,
 701                         struct cl_page *pg, int nonblock)
 702 {
 703         int result;
 704
 705         PINVRNT(env, pg, !cl_page_is_owned(pg, io));
 706
 707         ENTRY;
 708         pg = cl_page_top(pg);
 709         io = cl_io_top(io);
 710
 711         if (pg->cp_state == CPS_FREEING) {
 712                 result = -ENOENT;
 713         } else {
 714                 result = CL_PAGE_INVOKE(env, pg, CL_PAGE_OP(cpo_own),
 715                                         (const struct lu_env *,
 716                                          const struct cl_page_slice *,
 717                                          struct cl_io *, int),
 718                                         io, nonblock);
 719                 if (result == 0) {
 720                         PASSERT(env, pg, pg->cp_owner == NULL);
 721                         PASSERT(env, pg, pg->cp_req == NULL);
 722                         pg->cp_owner = io;
 723                         pg->cp_task  = current;
 724                         cl_page_owner_set(pg);
 725                         if (pg->cp_state != CPS_FREEING) {
 726                                 cl_page_state_set(env, pg, CPS_OWNED);
 727                         } else {
 728                                 cl_page_disown0(env, io, pg);
 729                                 result = -ENOENT;
 730                         }
 731                 }
 732         }
 733         PINVRNT(env, pg, ergo(result == 0, cl_page_invariant(pg)));
 734         RETURN(result);
 735 }
 736
 737 /**
 738  * Own a page, might be blocked.
 739  *
 740  * \see cl_page_own0()
 741  */
 742 int cl_page_own(const struct lu_env *env, struct cl_io *io, struct cl_page *pg)
 743 {
 744         return cl_page_own0(env, io, pg, 0);
 745 }
 746 EXPORT_SYMBOL(cl_page_own);
 747
 748 /**
 749  * Nonblock version of cl_page_own().
 750  *
 751  * \see cl_page_own0()
 752  */
 753 int cl_page_own_try(const struct lu_env *env, struct cl_io *io,
 754                     struct cl_page *pg)
 755 {
 756         return cl_page_own0(env, io, pg, 1);
 757 }
 758 EXPORT_SYMBOL(cl_page_own_try);
 759
 760
 761 /**
 762  * Assume page ownership.
 763  *
 764  * Called when page is already locked by the hosting VM.
 765  *
 766  * \pre !cl_page_is_owned(pg, io)
 767  * \post cl_page_is_owned(pg, io)
 768  *
 769  * \see cl_page_operations::cpo_assume()
 770  */
 771 void cl_page_assume(const struct lu_env *env,
 772                     struct cl_io *io, struct cl_page *pg)
 773 {
 774         PINVRNT(env, pg, cl_object_same(pg->cp_obj, io->ci_obj));
 775
 776         ENTRY;
 777         pg = cl_page_top(pg);
 778         io = cl_io_top(io);
 779
 780         cl_page_invoid(env, io, pg, CL_PAGE_OP(cpo_assume));
 781         PASSERT(env, pg, pg->cp_owner == NULL);
 782         pg->cp_owner = io;
 783         pg->cp_task = current;
 784         cl_page_owner_set(pg);
 785         cl_page_state_set(env, pg, CPS_OWNED);
 786         EXIT;
 787 }
 788 EXPORT_SYMBOL(cl_page_assume);
 789
 790 /**
 791  * Releases page ownership without unlocking the page.
 792  *
 793  * Moves page into cl_page_state::CPS_CACHED without releasing a lock on the
 794  * underlying VM page (as VM is supposed to do this itself).
 795  *
 796  * \pre   cl_page_is_owned(pg, io)
 797  * \post !cl_page_is_owned(pg, io)
 798  *
 799  * \see cl_page_assume()
 800  */
 801 void cl_page_unassume(const struct lu_env *env,
 802                       struct cl_io *io, struct cl_page *pg)
 803 {
 804         PINVRNT(env, pg, cl_page_is_owned(pg, io));
 805         PINVRNT(env, pg, cl_page_invariant(pg));
 806
 807         ENTRY;
 808         pg = cl_page_top(pg);
 809         io = cl_io_top(io);
 810         cl_page_owner_clear(pg);
 811         cl_page_state_set(env, pg, CPS_CACHED);
 812         CL_PAGE_INVOID_REVERSE(env, pg, CL_PAGE_OP(cpo_unassume),
 813                                (const struct lu_env *,
 814                                 const struct cl_page_slice *, struct cl_io *),
 815                                io);
 816         EXIT;
 817 }
 818 EXPORT_SYMBOL(cl_page_unassume);
 819
 820 /**
 821  * Releases page ownership.
 822  *
 823  * Moves page into cl_page_state::CPS_CACHED.
 824  *
 825  * \pre   cl_page_is_owned(pg, io)
 826  * \post !cl_page_is_owned(pg, io)
 827  *
 828  * \see cl_page_own()
 829  * \see cl_page_operations::cpo_disown()
 830  */
 831 void cl_page_disown(const struct lu_env *env,
 832                     struct cl_io *io, struct cl_page *pg)
 833 {
 834         PINVRNT(env, pg, cl_page_is_owned(pg, io) ||
 835                          pg->cp_state == CPS_FREEING);
 836
 837         ENTRY;
 838         pg = cl_page_top(pg);
 839         io = cl_io_top(io);
 840         cl_page_disown0(env, io, pg);
 841         EXIT;
 842 }
 843 EXPORT_SYMBOL(cl_page_disown);
 844
 845 /**
 846  * Called when page is to be removed from the object, e.g., as a result of
 847  * truncate.
 848  *
 849  * Calls cl_page_operations::cpo_discard() top-to-bottom.
 850  *
 851  * \pre cl_page_is_owned(pg, io)
 852  *
 853  * \see cl_page_operations::cpo_discard()
 854  */
 855 void cl_page_discard(const struct lu_env *env,
 856                      struct cl_io *io, struct cl_page *pg)
 857 {
 858         PINVRNT(env, pg, cl_page_is_owned(pg, io));
 859         PINVRNT(env, pg, cl_page_invariant(pg));
 860
 861         cl_page_invoid(env, io, pg, CL_PAGE_OP(cpo_discard));
 862 }
 863 EXPORT_SYMBOL(cl_page_discard);
 864
 865 /**
 866  * Version of cl_page_delete() that can be called for not fully constructed
 867  * pages, e.g,. in a error handling cl_page_find()->cl_page_delete0()
 868  * path. Doesn't check page invariant.
 869  */
 870 static void cl_page_delete0(const struct lu_env *env, struct cl_page *pg)
 871 {
 872         ENTRY;
 873
 874         PASSERT(env, pg, pg == cl_page_top(pg));
 875         PASSERT(env, pg, pg->cp_state != CPS_FREEING);
 876
 877         /*
 878          * Severe all ways to obtain new pointers to @pg.
 879          */
 880         cl_page_owner_clear(pg);
 881
 882         cl_page_state_set0(env, pg, CPS_FREEING);
 883
 884         CL_PAGE_INVOID_REVERSE(env, pg, CL_PAGE_OP(cpo_delete),
 885                        (const struct lu_env *, const struct cl_page_slice *));
 886
 887         EXIT;
 888 }
 889
 890 /**
 891  * Called when a decision is made to throw page out of memory.
 892  *
 893  * Notifies all layers about page destruction by calling
 894  * cl_page_operations::cpo_delete() method top-to-bottom.
 895  *
 896  * Moves page into cl_page_state::CPS_FREEING state (this is the only place
 897  * where transition to this state happens).
 898  *
 899  * Eliminates all venues through which new references to the page can be
 900  * obtained:
 901  *
 902  *     - removes page from the radix trees,
 903  *
 904  *     - breaks linkage from VM page to cl_page.
 905  *
 906  * Once page reaches cl_page_state::CPS_FREEING, all remaining references will
 907  * drain after some time, at which point page will be recycled.
 908  *
 909  * \pre  pg == cl_page_top(pg)
 910  * \pre  VM page is locked
 911  * \post pg->cp_state == CPS_FREEING
 912  *
 913  * \see cl_page_operations::cpo_delete()
 914  */
 915 void cl_page_delete(const struct lu_env *env, struct cl_page *pg)
 916 {
 917         PINVRNT(env, pg, cl_page_invariant(pg));
 918         ENTRY;
 919         cl_page_delete0(env, pg);
 920         EXIT;
 921 }
 922 EXPORT_SYMBOL(cl_page_delete);
 923
 924 /**
 925  * Marks page up-to-date.
 926  *
 927  * Call cl_page_operations::cpo_export() through all layers top-to-bottom. The
 928  * layer responsible for VM interaction has to mark/clear page as up-to-date
 929  * by the \a uptodate argument.
 930  *
 931  * \see cl_page_operations::cpo_export()
 932  */
 933 void cl_page_export(const struct lu_env *env, struct cl_page *pg, int uptodate)
 934 {
 935         PINVRNT(env, pg, cl_page_invariant(pg));
 936         CL_PAGE_INVOID(env, pg, CL_PAGE_OP(cpo_export),
 937                        (const struct lu_env *,
 938                         const struct cl_page_slice *, int), uptodate);
 939 }
 940 EXPORT_SYMBOL(cl_page_export);
 941
 942 /**
 943  * Returns true, iff \a pg is VM locked in a suitable sense by the calling
 944  * thread.
 945  */
 946 int cl_page_is_vmlocked(const struct lu_env *env, const struct cl_page *pg)
 947 {
 948         int result;
 949         const struct cl_page_slice *slice;
 950
 951         ENTRY;
 952         pg = cl_page_top_trusted((struct cl_page *)pg);
 953         slice = container_of(pg->cp_layers.next,
 954                              const struct cl_page_slice, cpl_linkage);
 955         PASSERT(env, pg, slice->cpl_ops->cpo_is_vmlocked != NULL);
 956         /*
 957          * Call ->cpo_is_vmlocked() directly instead of going through
 958          * CL_PAGE_INVOKE(), because cl_page_is_vmlocked() is used by
 959          * cl_page_invariant().
 960          */
 961         result = slice->cpl_ops->cpo_is_vmlocked(env, slice);
 962         PASSERT(env, pg, result == -EBUSY || result == -ENODATA);
 963         RETURN(result == -EBUSY);
 964 }
 965 EXPORT_SYMBOL(cl_page_is_vmlocked);
 966
 967 static enum cl_page_state cl_req_type_state(enum cl_req_type crt)
 968 {
 969         ENTRY;
 970         RETURN(crt == CRT_WRITE ? CPS_PAGEOUT : CPS_PAGEIN);
 971 }
 972
 973 static void cl_page_io_start(const struct lu_env *env,
 974                              struct cl_page *pg, enum cl_req_type crt)
 975 {
 976         /*
 977          * Page is queued for IO, change its state.
 978          */
 979         ENTRY;
 980         cl_page_owner_clear(pg);
 981         cl_page_state_set(env, pg, cl_req_type_state(crt));
 982         EXIT;
 983 }
 984
 985 /**
 986  * Prepares page for immediate transfer. cl_page_operations::cpo_prep() is
 987  * called top-to-bottom. Every layer either agrees to submit this page (by
 988  * returning 0), or requests to omit this page (by returning -EALREADY). Layer
 989  * handling interactions with the VM also has to inform VM that page is under
 990  * transfer now.
 991  */
 992 int cl_page_prep(const struct lu_env *env, struct cl_io *io,
 993                  struct cl_page *pg, enum cl_req_type crt)
 994 {
 995         int result;
 996
 997         PINVRNT(env, pg, cl_page_is_owned(pg, io));
 998         PINVRNT(env, pg, cl_page_invariant(pg));
 999         PINVRNT(env, pg, crt < CRT_NR);
1000
1001         /*
1002          * XXX this has to be called bottom-to-top, so that llite can set up
1003          * PG_writeback without risking other layers deciding to skip this
1004          * page.
1005          */
1006         if (crt >= CRT_NR)
1007                 return -EINVAL;
1008         result = cl_page_invoke(env, io, pg, CL_PAGE_OP(io[crt].cpo_prep));
1009         if (result == 0)
1010                 cl_page_io_start(env, pg, crt);
1011
1012         KLASSERT(ergo(crt == CRT_WRITE && pg->cp_type == CPT_CACHEABLE,
1013                       equi(result == 0,
1014                            PageWriteback(cl_page_vmpage(env, pg)))));
1015         CL_PAGE_HEADER(D_TRACE, env, pg, "%d %d\n", crt, result);
1016         return result;
1017 }
1018 EXPORT_SYMBOL(cl_page_prep);
1019
1020 /**
1021  * Notify layers about transfer completion.
1022  *
1023  * Invoked by transfer sub-system (which is a part of osc) to notify layers
1024  * that a transfer, of which this page is a part of has completed.
1025  *
1026  * Completion call-backs are executed in the bottom-up order, so that
1027  * uppermost layer (llite), responsible for the VFS/VM interaction runs last
1028  * and can release locks safely.
1029  *
1030  * \pre  pg->cp_state == CPS_PAGEIN || pg->cp_state == CPS_PAGEOUT
1031  * \post pg->cp_state == CPS_CACHED
1032  *
1033  * \see cl_page_operations::cpo_completion()
1034  */
1035 void cl_page_completion(const struct lu_env *env,
1036                         struct cl_page *pg, enum cl_req_type crt, int ioret)
1037 {
1038         struct cl_sync_io *anchor = pg->cp_sync_io;
1039
1040         PASSERT(env, pg, crt < CRT_NR);
1041         /* cl_page::cp_req already cleared by the caller (osc_completion()) */
1042         PASSERT(env, pg, pg->cp_req == NULL);
1043         PASSERT(env, pg, pg->cp_state == cl_req_type_state(crt));
1044
1045         ENTRY;
1046         CL_PAGE_HEADER(D_TRACE, env, pg, "%d %d\n", crt, ioret);
1047         if (crt == CRT_READ && ioret == 0) {
1048                 PASSERT(env, pg, !(pg->cp_flags & CPF_READ_COMPLETED));
1049                 pg->cp_flags |= CPF_READ_COMPLETED;
1050         }
1051
1052         cl_page_state_set(env, pg, CPS_CACHED);
1053         if (crt >= CRT_NR)
1054                 return;
1055         CL_PAGE_INVOID_REVERSE(env, pg, CL_PAGE_OP(io[crt].cpo_completion),
1056                                (const struct lu_env *,
1057                                 const struct cl_page_slice *, int), ioret);
1058         if (anchor) {
1059                 LASSERT(cl_page_is_vmlocked(env, pg));
1060                 LASSERT(pg->cp_sync_io == anchor);
1061                 pg->cp_sync_io = NULL;
1062         }
1063         /*
1064          * As page->cp_obj is pinned by a reference from page->cp_req, it is
1065          * safe to call cl_page_put() without risking object destruction in a
1066          * non-blocking context.
1067          */
1068         cl_page_put(env, pg);
1069
1070         if (anchor)
1071                 cl_sync_io_note(anchor, ioret);
1072
1073         EXIT;
1074 }
1075 EXPORT_SYMBOL(cl_page_completion);
1076
1077 /**
1078  * Notify layers that transfer formation engine decided to yank this page from
1079  * the cache and to make it a part of a transfer.
1080  *
1081  * \pre  pg->cp_state == CPS_CACHED
1082  * \post pg->cp_state == CPS_PAGEIN || pg->cp_state == CPS_PAGEOUT
1083  *
1084  * \see cl_page_operations::cpo_make_ready()
1085  */
1086 int cl_page_make_ready(const struct lu_env *env, struct cl_page *pg,
1087                        enum cl_req_type crt)
1088 {
1089         int result;
1090
1091         PINVRNT(env, pg, crt < CRT_NR);
1092
1093         ENTRY;
1094         if (crt >= CRT_NR)
1095                 RETURN(-EINVAL);
1096         result = CL_PAGE_INVOKE(env, pg, CL_PAGE_OP(io[crt].cpo_make_ready),
1097                                 (const struct lu_env *,
1098                                  const struct cl_page_slice *));
1099         if (result == 0) {
1100                 PASSERT(env, pg, pg->cp_state == CPS_CACHED);
1101                 cl_page_io_start(env, pg, crt);
1102         }
1103         CL_PAGE_HEADER(D_TRACE, env, pg, "%d %d\n", crt, result);
1104         RETURN(result);
1105 }
1106 EXPORT_SYMBOL(cl_page_make_ready);
1107
1108 /**
1109  * Notify layers that high level io decided to place this page into a cache
1110  * for future transfer.
1111  *
1112  * The layer implementing transfer engine (osc) has to register this page in
1113  * its queues.
1114  *
1115  * \pre  cl_page_is_owned(pg, io)
1116  * \post cl_page_is_owned(pg, io)
1117  *
1118  * \see cl_page_operations::cpo_cache_add()
1119  */
1120 int cl_page_cache_add(const struct lu_env *env, struct cl_io *io,
1121                       struct cl_page *pg, enum cl_req_type crt)
1122 {
1123         const struct cl_page_slice *scan;
1124         int result = 0;
1125
1126         PINVRNT(env, pg, crt < CRT_NR);
1127         PINVRNT(env, pg, cl_page_is_owned(pg, io));
1128         PINVRNT(env, pg, cl_page_invariant(pg));
1129
1130         ENTRY;
1131
1132         if (crt >= CRT_NR)
1133                 RETURN(-EINVAL);
1134
1135         cfs_list_for_each_entry(scan, &pg->cp_layers, cpl_linkage) {
1136                 if (scan->cpl_ops->io[crt].cpo_cache_add == NULL)
1137                         continue;
1138
1139                 result = scan->cpl_ops->io[crt].cpo_cache_add(env, scan, io);
1140                 if (result != 0)
1141                         break;
1142         }
1143         CL_PAGE_HEADER(D_TRACE, env, pg, "%d %d\n", crt, result);
1144         RETURN(result);
1145 }
1146 EXPORT_SYMBOL(cl_page_cache_add);
1147
1148 /**
1149  * Called if a pge is being written back by kernel's intention.
1150  *
1151  * \pre  cl_page_is_owned(pg, io)
1152  * \post ergo(result == 0, pg->cp_state == CPS_PAGEOUT)
1153  *
1154  * \see cl_page_operations::cpo_flush()
1155  */
1156 int cl_page_flush(const struct lu_env *env, struct cl_io *io,
1157                   struct cl_page *pg)
1158 {
1159         int result;
1160
1161         PINVRNT(env, pg, cl_page_is_owned(pg, io));
1162         PINVRNT(env, pg, cl_page_invariant(pg));
1163
1164         ENTRY;
1165
1166         result = cl_page_invoke(env, io, pg, CL_PAGE_OP(cpo_flush));
1167
1168         CL_PAGE_HEADER(D_TRACE, env, pg, "%d\n", result);
1169         RETURN(result);
1170 }
1171 EXPORT_SYMBOL(cl_page_flush);
1172
1173 /**
1174  * Checks whether page is protected by any extent lock is at least required
1175  * mode.
1176  *
1177  * \return the same as in cl_page_operations::cpo_is_under_lock() method.
1178  * \see cl_page_operations::cpo_is_under_lock()
1179  */
1180 int cl_page_is_under_lock(const struct lu_env *env, struct cl_io *io,
1181                           struct cl_page *page)
1182 {
1183         int rc;
1184
1185         PINVRNT(env, page, cl_page_invariant(page));
1186
1187         ENTRY;
1188         rc = CL_PAGE_INVOKE(env, page, CL_PAGE_OP(cpo_is_under_lock),
1189                             (const struct lu_env *,
1190                              const struct cl_page_slice *, struct cl_io *),
1191                             io);
1192         PASSERT(env, page, rc != 0);
1193         RETURN(rc);
1194 }
1195 EXPORT_SYMBOL(cl_page_is_under_lock);
1196
1197 /**
1198  * Tells transfer engine that only part of a page is to be transmitted.
1199  *
1200  * \see cl_page_operations::cpo_clip()
1201  */
1202 void cl_page_clip(const struct lu_env *env, struct cl_page *pg,
1203                   int from, int to)
1204 {
1205         PINVRNT(env, pg, cl_page_invariant(pg));
1206
1207         CL_PAGE_HEADER(D_TRACE, env, pg, "%d %d\n", from, to);
1208         CL_PAGE_INVOID(env, pg, CL_PAGE_OP(cpo_clip),
1209                        (const struct lu_env *,
1210                         const struct cl_page_slice *,int, int),
1211                        from, to);
1212 }
1213 EXPORT_SYMBOL(cl_page_clip);
1214
1215 /**
1216  * Prints human readable representation of \a pg to the \a f.
1217  */
1218 void cl_page_header_print(const struct lu_env *env, void *cookie,
1219                           lu_printer_t printer, const struct cl_page *pg)
1220 {
1221         (*printer)(env, cookie,
1222                    "page@%p[%d %p:%lu ^%p_%p %d %d %d %p %p %#x]\n",
1223                    pg, cfs_atomic_read(&pg->cp_ref), pg->cp_obj,
1224                    pg->cp_index, pg->cp_parent, pg->cp_child,
1225                    pg->cp_state, pg->cp_error, pg->cp_type,
1226                    pg->cp_owner, pg->cp_req, pg->cp_flags);
1227 }
1228 EXPORT_SYMBOL(cl_page_header_print);
1229
1230 /**
1231  * Prints human readable representation of \a pg to the \a f.
1232  */
1233 void cl_page_print(const struct lu_env *env, void *cookie,
1234                    lu_printer_t printer, const struct cl_page *pg)
1235 {
1236         struct cl_page *scan;
1237
1238         for (scan = cl_page_top((struct cl_page *)pg);
1239              scan != NULL; scan = scan->cp_child)
1240                 cl_page_header_print(env, cookie, printer, scan);
1241         CL_PAGE_INVOKE(env, (struct cl_page *)pg, CL_PAGE_OP(cpo_print),
1242                        (const struct lu_env *env,
1243                         const struct cl_page_slice *slice,
1244                         void *cookie, lu_printer_t p), cookie, printer);
1245         (*printer)(env, cookie, "end page@%p\n", pg);
1246 }
1247 EXPORT_SYMBOL(cl_page_print);
1248
1249 /**
1250  * Cancel a page which is still in a transfer.
1251  */
1252 int cl_page_cancel(const struct lu_env *env, struct cl_page *page)
1253 {
1254         return CL_PAGE_INVOKE(env, page, CL_PAGE_OP(cpo_cancel),
1255                               (const struct lu_env *,
1256                                const struct cl_page_slice *));
1257 }
1258 EXPORT_SYMBOL(cl_page_cancel);
1259
1260 /**
1261  * Converts a byte offset within object \a obj into a page index.
1262  */
1263 loff_t cl_offset(const struct cl_object *obj, pgoff_t idx)
1264 {
1265         return (loff_t)idx << PAGE_CACHE_SHIFT;
1266 }
1267 EXPORT_SYMBOL(cl_offset);
1268
1269 /**
1270  * Converts a page index into a byte offset within object \a obj.
1271  */
1272 pgoff_t cl_index(const struct cl_object *obj, loff_t offset)
1273 {
1274         return offset >> PAGE_CACHE_SHIFT;
1275 }
1276 EXPORT_SYMBOL(cl_index);
1277
1278 int cl_page_size(const struct cl_object *obj)
1279 {
1280         return 1 << PAGE_CACHE_SHIFT;
1281 }
1282 EXPORT_SYMBOL(cl_page_size);
1283
1284 /**
1285  * Adds page slice to the compound page.
1286  *
1287  * This is called by cl_object_operations::coo_page_init() methods to add a
1288  * per-layer state to the page. New state is added at the end of
1289  * cl_page::cp_layers list, that is, it is at the bottom of the stack.
1290  *
1291  * \see cl_lock_slice_add(), cl_req_slice_add(), cl_io_slice_add()
1292  */
1293 void cl_page_slice_add(struct cl_page *page, struct cl_page_slice *slice,
1294                        struct cl_object *obj,
1295                        const struct cl_page_operations *ops)
1296 {
1297         ENTRY;
1298         cfs_list_add_tail(&slice->cpl_linkage, &page->cp_layers);
1299         slice->cpl_obj  = obj;
1300         slice->cpl_ops  = ops;
1301         slice->cpl_page = page;
1302         EXIT;
1303 }
1304 EXPORT_SYMBOL(cl_page_slice_add);
1305
1306 int  cl_page_init(void)
1307 {
1308         return 0;
1309 }
1310
1311 void cl_page_fini(void)
1312 {
1313 }