lustre/obdclass/cl_page.c

   1 /* -*- mode: c; c-basic-offset: 8; indent-tabs-mode: nil; -*-
   2  * vim:expandtab:shiftwidth=8:tabstop=8:
   3  *
   4  * GPL HEADER START
   5  *
   6  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 only,
  10  * as published by the Free Software Foundation.
  11  *
  12  * This program is distributed in the hope that it will be useful, but
  13  * WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * General Public License version 2 for more details (a copy is included
  16  * in the LICENSE file that accompanied this code).
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * version 2 along with this program; If not, see
  20  * http://www.sun.com/software/products/lustre/docs/GPLv2.pdf
  21  *
  22  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
  23  * CA 95054 USA or visit www.sun.com if you need additional information or
  24  * have any questions.
  25  *
  26  * GPL HEADER END
  27  */
  28 /*
  29  * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
  30  * Use is subject to license terms.
  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  */
  40
  41 #define DEBUG_SUBSYSTEM S_CLASS
  42 #ifndef EXPORT_SYMTAB
  43 # define EXPORT_SYMTAB
  44 #endif
  45
  46 #include <libcfs/libcfs.h>
  47 #include <obd_class.h>
  48 #include <obd_support.h>
  49 #include <libcfs/list.h>
  50
  51 #include <cl_object.h>
  52 #include "cl_internal.h"
  53
  54 static void cl_page_delete0(const struct lu_env *env, struct cl_page *pg,
  55                             int radix);
  56
  57 static cfs_mem_cache_t      *cl_page_kmem = NULL;
  58
  59 static struct lu_kmem_descr cl_page_caches[] = {
  60         {
  61                 .ckd_cache = &cl_page_kmem,
  62                 .ckd_name  = "cl_page_kmem",
  63                 .ckd_size  = sizeof (struct cl_page)
  64         },
  65         {
  66                 .ckd_cache = NULL
  67         }
  68 };
  69
  70 #ifdef LIBCFS_DEBUG
  71 # define PASSERT(env, page, expr)                                       \
  72   do {                                                                    \
  73           if (unlikely(!(expr))) {                                      \
  74                   CL_PAGE_DEBUG(D_ERROR, (env), (page), #expr "\n");    \
  75                   LASSERT(0);                                           \
  76           }                                                             \
  77   } while (0)
  78 #else /* !LIBCFS_DEBUG */
  79 # define PASSERT(env, page, exp) \
  80         ((void)sizeof(env), (void)sizeof(page), (void)sizeof !!(exp))
  81 #endif /* !LIBCFS_DEBUG */
  82
  83 #ifdef INVARIANT_CHECK
  84 # define PINVRNT(env, page, expr)                                       \
  85   do {                                                                    \
  86           if (unlikely(!(expr))) {                                      \
  87                   CL_PAGE_DEBUG(D_ERROR, (env), (page), #expr "\n");    \
  88                   LINVRNT(0);                                           \
  89           }                                                             \
  90   } while (0)
  91 #else /* !INVARIANT_CHECK */
  92 # define PINVRNT(env, page, exp) \
  93         ((void)sizeof(env), (void)sizeof(page), (void)sizeof !!(exp))
  94 #endif /* !INVARIANT_CHECK */
  95
  96 /**
  97  * Internal version of cl_page_top, it should be called with page referenced,
  98  * or coh_page_guard held.
  99  */
 100 static struct cl_page *cl_page_top_trusted(struct cl_page *page)
 101 {
 102         LASSERT(cl_is_page(page));
 103         while (page->cp_parent != NULL)
 104                 page = page->cp_parent;
 105         return page;
 106 }
 107
 108 /**
 109  * Internal version of cl_page_get().
 110  *
 111  * This function can be used to obtain initial reference to previously
 112  * unreferenced cached object. It can be called only if concurrent page
 113  * reclamation is somehow prevented, e.g., by locking page radix-tree
 114  * (cl_object_header::hdr->coh_page_guard), or 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(cl_is_page(page));
 122         /*
 123          * Checkless version for trusted users.
 124          */
 125         if (atomic_inc_return(&page->cp_ref) == 1)
 126                 atomic_inc(&cl_object_site(page->cp_obj)->cs_pages.cs_busy);
 127 }
 128
 129 /**
 130  * Returns a slice within a page, corresponding to the given layer in the
 131  * device stack.
 132  *
 133  * \see cl_lock_at()
 134  */
 135 static const struct cl_page_slice *
 136 cl_page_at_trusted(const struct cl_page *page,
 137                    const struct lu_device_type *dtype)
 138 {
 139         const struct cl_page_slice *slice;
 140
 141 #ifdef INVARIANT_CHECK
 142         struct cl_object_header *ch = cl_object_header(page->cp_obj);
 143
 144         if (!atomic_read(&page->cp_ref))
 145                 LASSERT_SPIN_LOCKED(&ch->coh_page_guard);
 146 #endif
 147         ENTRY;
 148
 149         page = cl_page_top_trusted((struct cl_page *)page);
 150         do {
 151                 list_for_each_entry(slice, &page->cp_layers, cpl_linkage) {
 152                         if (slice->cpl_obj->co_lu.lo_dev->ld_type == dtype)
 153                                 RETURN(slice);
 154                 }
 155                 page = page->cp_child;
 156         } while (page != NULL);
 157         RETURN(NULL);
 158 }
 159
 160 /**
 161  * Returns a page with given index in the given object, or NULL if no page is
 162  * found. Acquires a reference on \a page.
 163  *
 164  * Locking: called under cl_object_header::coh_page_guard spin-lock.
 165  */
 166 struct cl_page *cl_page_lookup(struct cl_object_header *hdr, pgoff_t index)
 167 {
 168         struct cl_page *page;
 169
 170         LASSERT_SPIN_LOCKED(&hdr->coh_page_guard);
 171
 172         page = radix_tree_lookup(&hdr->coh_tree, index);
 173         if (page != NULL) {
 174                 LASSERT(cl_is_page(page));
 175                 cl_page_get_trust(page);
 176         }
 177         return page;
 178 }
 179 EXPORT_SYMBOL(cl_page_lookup);
 180
 181 /**
 182  * Returns a list of pages by a given [start, end] of @obj.
 183  *
 184  * Gang tree lookup (radix_tree_gang_lookup()) optimization is absolutely
 185  * crucial in the face of [offset, EOF] locks.
 186  */
 187 void cl_page_gang_lookup(const struct lu_env *env, struct cl_object *obj,
 188                          struct cl_io *io, pgoff_t start, pgoff_t end,
 189                          struct cl_page_list *queue)
 190 {
 191         struct cl_object_header *hdr;
 192         struct cl_page          *page;
 193         struct cl_page         **pvec;
 194         const struct cl_page_slice  *slice;
 195         const struct lu_device_type *dtype;
 196         pgoff_t                  idx;
 197         unsigned int             nr;
 198         unsigned int             i;
 199         unsigned int             j;
 200         ENTRY;
 201
 202         idx = start;
 203         hdr = cl_object_header(obj);
 204         pvec = cl_env_info(env)->clt_pvec;
 205         dtype = cl_object_top(obj)->co_lu.lo_dev->ld_type;
 206         spin_lock(&hdr->coh_page_guard);
 207         while ((nr = radix_tree_gang_lookup(&hdr->coh_tree, (void **)pvec,
 208                                             idx, CLT_PVEC_SIZE)) > 0) {
 209                 idx = pvec[nr - 1]->cp_index + 1;
 210                 for (i = 0, j = 0; i < nr; ++i) {
 211                         page = pvec[i];
 212                         PASSERT(env, page, cl_is_page(page));
 213                         pvec[i] = NULL;
 214                         if (page->cp_index > end)
 215                                 break;
 216                         if (page->cp_state == CPS_FREEING)
 217                                 continue;
 218                         if (page->cp_type == CPT_TRANSIENT) {
 219                                 /* God, we found a transient page!*/
 220                                 continue;
 221                         }
 222
 223                         slice = cl_page_at_trusted(page, dtype);
 224                         /*
 225                          * Pages for lsm-less file has no underneath sub-page
 226                          * for osc, in case of ...
 227                          */
 228                         PASSERT(env, page, slice != NULL);
 229                         page = slice->cpl_page;
 230                         /*
 231                          * Can safely call cl_page_get_trust() under
 232                          * radix-tree spin-lock.
 233                          *
 234                          * XXX not true, because @page is from object another
 235                          * than @hdr and protected by different tree lock.
 236                          */
 237                         cl_page_get_trust(page);
 238                         lu_ref_add_atomic(&page->cp_reference,
 239                                           "page_list", cfs_current());
 240                         pvec[j++] = page;
 241                 }
 242
 243                 /*
 244                  * Here a delicate locking dance is performed. Current thread
 245                  * holds a reference to a page, but has to own it before it
 246                  * can be placed into queue. Owning implies waiting, so
 247                  * radix-tree lock is to be released. After a wait one has to
 248                  * check that pages weren't truncated (cl_page_own() returns
 249                  * error in the latter case).
 250                  */
 251                 spin_unlock(&hdr->coh_page_guard);
 252                 for (i = 0; i < j; ++i) {
 253                         page = pvec[i];
 254                         if (cl_page_own(env, io, page) == 0)
 255                                 cl_page_list_add(queue, page);
 256                         lu_ref_del(&page->cp_reference,
 257                                    "page_list", cfs_current());
 258                         cl_page_put(env, page);
 259                 }
 260                 spin_lock(&hdr->coh_page_guard);
 261                 if (nr < CLT_PVEC_SIZE)
 262                         break;
 263         }
 264         spin_unlock(&hdr->coh_page_guard);
 265         EXIT;
 266 }
 267 EXPORT_SYMBOL(cl_page_gang_lookup);
 268
 269 static void cl_page_free(const struct lu_env *env, struct cl_page *page)
 270 {
 271         struct cl_object *obj  = page->cp_obj;
 272         struct cl_site   *site = cl_object_site(obj);
 273
 274         PASSERT(env, page, cl_is_page(page));
 275         PASSERT(env, page, list_empty(&page->cp_batch));
 276         PASSERT(env, page, page->cp_owner == NULL);
 277         PASSERT(env, page, page->cp_req == NULL);
 278         PASSERT(env, page, page->cp_parent == NULL);
 279         PASSERT(env, page, page->cp_state == CPS_FREEING);
 280
 281         ENTRY;
 282         might_sleep();
 283         while (!list_empty(&page->cp_layers)) {
 284                 struct cl_page_slice *slice;
 285
 286                 slice = list_entry(page->cp_layers.next, struct cl_page_slice,
 287                                    cpl_linkage);
 288                 list_del_init(page->cp_layers.next);
 289                 slice->cpl_ops->cpo_fini(env, slice);
 290         }
 291         atomic_dec(&site->cs_pages.cs_total);
 292         atomic_dec(&site->cs_pages_state[page->cp_state]);
 293         lu_object_ref_del_at(&obj->co_lu, page->cp_obj_ref, "cl_page", page);
 294         cl_object_put(env, obj);
 295         lu_ref_fini(&page->cp_reference);
 296         OBD_SLAB_FREE_PTR(page, cl_page_kmem);
 297         EXIT;
 298 }
 299
 300 /**
 301  * Helper function updating page state. This is the only place in the code
 302  * where cl_page::cp_state field is mutated.
 303  */
 304 static inline void cl_page_state_set_trust(struct cl_page *page,
 305                                            enum cl_page_state state)
 306 {
 307         /* bypass const. */
 308         *(enum cl_page_state *)&page->cp_state = state;
 309 }
 310
 311 static int cl_page_alloc(const struct lu_env *env, struct cl_object *o,
 312                          pgoff_t ind, struct page *vmpage,
 313                          enum cl_page_type type, struct cl_page **out)
 314 {
 315         struct cl_page          *page;
 316         struct cl_page          *err  = NULL;
 317         struct lu_object_header *head;
 318         struct cl_site          *site = cl_object_site(o);
 319         int                      result;
 320
 321         ENTRY;
 322         result = +1;
 323         OBD_SLAB_ALLOC_PTR_GFP(page, cl_page_kmem, CFS_ALLOC_IO);
 324         if (page != NULL) {
 325                 atomic_set(&page->cp_ref, 1);
 326                 page->cp_obj = o;
 327                 cl_object_get(o);
 328                 page->cp_obj_ref = lu_object_ref_add(&o->co_lu,
 329                                                      "cl_page", page);
 330                 page->cp_index = ind;
 331                 cl_page_state_set_trust(page, CPS_CACHED);
 332                 page->cp_type = type;
 333                 CFS_INIT_LIST_HEAD(&page->cp_layers);
 334                 CFS_INIT_LIST_HEAD(&page->cp_batch);
 335                 CFS_INIT_LIST_HEAD(&page->cp_flight);
 336                 mutex_init(&page->cp_mutex);
 337                 lu_ref_init(&page->cp_reference);
 338                 head = o->co_lu.lo_header;
 339                 list_for_each_entry(o, &head->loh_layers, co_lu.lo_linkage) {
 340                         if (o->co_ops->coo_page_init != NULL) {
 341                                 err = o->co_ops->coo_page_init(env, o,
 342                                                                page, vmpage);
 343                                 if (err != NULL) {
 344                                         cl_page_state_set_trust(page,
 345                                                                 CPS_FREEING);
 346                                         cl_page_free(env, page);
 347                                         page = err;
 348                                         break;
 349                                 }
 350                         }
 351                 }
 352                 if (err == NULL) {
 353                         atomic_inc(&site->cs_pages.cs_busy);
 354                         atomic_inc(&site->cs_pages.cs_total);
 355                         atomic_inc(&site->cs_pages_state[CPS_CACHED]);
 356                         atomic_inc(&site->cs_pages.cs_created);
 357                         result = 0;
 358                 }
 359         } else
 360                 page = ERR_PTR(-ENOMEM);
 361         *out = page;
 362         RETURN(result);
 363 }
 364
 365 /**
 366  * Returns a cl_page with index \a idx at the object \a o, and associated with
 367  * the VM page \a vmpage.
 368  *
 369  * This is the main entry point into the cl_page caching interface. First, a
 370  * cache (implemented as a per-object radix tree) is consulted. If page is
 371  * found there, it is returned immediately. Otherwise new page is allocated
 372  * and returned. In any case, additional reference to page is acquired.
 373  *
 374  * \see cl_object_find(), cl_lock_find()
 375  */
 376 struct cl_page *cl_page_find(const struct lu_env *env, struct cl_object *o,
 377                              pgoff_t idx, struct page *vmpage,
 378                              enum cl_page_type type)
 379 {
 380         struct cl_page          *page;
 381         struct cl_page          *ghost = NULL;
 382         struct cl_object_header *hdr;
 383         struct cl_site          *site = cl_object_site(o);
 384         int err;
 385
 386         LINVRNT(type == CPT_CACHEABLE || type == CPT_TRANSIENT);
 387         might_sleep();
 388
 389         ENTRY;
 390
 391         hdr = cl_object_header(o);
 392         atomic_inc(&site->cs_pages.cs_lookup);
 393
 394         CDEBUG(D_PAGE, "%lu@"DFID" %p %lu %i\n",
 395                idx, PFID(&hdr->coh_lu.loh_fid), vmpage, vmpage->private, type);
 396         /* fast path. */
 397         if (type == CPT_CACHEABLE) {
 398                 /*
 399                  * cl_vmpage_page() can be called here without any locks as
 400                  *
 401                  *     - "vmpage" is locked (which prevents ->private from
 402                  *       concurrent updates), and
 403                  *
 404                  *     - "o" cannot be destroyed while current thread holds a
 405                  *       reference on it.
 406                  */
 407                 page = cl_vmpage_page(vmpage, o);
 408                 PINVRNT(env, page,
 409                         ergo(page != NULL,
 410                              cl_page_vmpage(env, page) == vmpage &&
 411                              (void *)radix_tree_lookup(&hdr->coh_tree,
 412                                                        idx) == page));
 413         } else {
 414                 spin_lock(&hdr->coh_page_guard);
 415                 page = cl_page_lookup(hdr, idx);
 416                 spin_unlock(&hdr->coh_page_guard);
 417         }
 418         if (page != NULL) {
 419                 atomic_inc(&site->cs_pages.cs_hit);
 420                 RETURN(page);
 421         }
 422
 423         /* allocate and initialize cl_page */
 424         err = cl_page_alloc(env, o, idx, vmpage, type, &page);
 425         if (err != 0)
 426                 RETURN(page);
 427         /*
 428          * XXX optimization: use radix_tree_preload() here, and change tree
 429          * gfp mask to GFP_KERNEL in cl_object_header_init().
 430          */
 431         spin_lock(&hdr->coh_page_guard);
 432         err = radix_tree_insert(&hdr->coh_tree, idx, page);
 433         if (err != 0) {
 434                 ghost = page;
 435                 /*
 436                  * Noted by Jay: a lock on \a vmpage protects cl_page_find()
 437                  * from this race, but
 438                  *
 439                  *     0. it's better to have cl_page interface "locally
 440                  *     consistent" so that its correctness can be reasoned
 441                  *     about without appealing to the (obscure world of) VM
 442                  *     locking.
 443                  *
 444                  *     1. handling this race allows ->coh_tree to remain
 445                  *     consistent even when VM locking is somehow busted,
 446                  *     which is very useful during diagnosing and debugging.
 447                  */
 448                 if (err == -EEXIST) {
 449                         /*
 450                          * XXX in case of a lookup for CPT_TRANSIENT page,
 451                          * nothing protects a CPT_CACHEABLE page from being
 452                          * concurrently moved into CPS_FREEING state.
 453                          */
 454                         page = cl_page_lookup(hdr, idx);
 455                         PASSERT(env, page, page != NULL);
 456                         if (page->cp_type == CPT_TRANSIENT &&
 457                             type == CPT_CACHEABLE) {
 458                                 /* XXX: We should make sure that inode sem
 459                                  * keeps being held in the lifetime of
 460                                  * transient pages, so it is impossible to
 461                                  * have conflicting transient pages.
 462                                  */
 463                                 spin_unlock(&hdr->coh_page_guard);
 464                                 cl_page_put(env, page);
 465                                 spin_lock(&hdr->coh_page_guard);
 466                                 page = ERR_PTR(-EBUSY);
 467                         }
 468                 } else
 469                         page = ERR_PTR(err);
 470         } else
 471                 hdr->coh_pages++;
 472         spin_unlock(&hdr->coh_page_guard);
 473
 474         if (unlikely(ghost != NULL)) {
 475                 atomic_dec(&site->cs_pages.cs_busy);
 476                 cl_page_delete0(env, ghost, 0);
 477                 cl_page_free(env, ghost);
 478         }
 479         RETURN(page);
 480 }
 481 EXPORT_SYMBOL(cl_page_find);
 482
 483 static inline int cl_page_invariant(const struct cl_page *pg)
 484 {
 485         struct cl_object_header *header;
 486         struct cl_page          *parent;
 487         struct cl_page          *child;
 488         struct cl_io            *owner;
 489
 490         LASSERT(cl_is_page(pg));
 491         /*
 492          * Page invariant is protected by a VM lock.
 493          */
 494         LINVRNT(cl_page_is_vmlocked(NULL, pg));
 495
 496         header = cl_object_header(pg->cp_obj);
 497         parent = pg->cp_parent;
 498         child  = pg->cp_child;
 499         owner  = pg->cp_owner;
 500
 501         return atomic_read(&pg->cp_ref) > 0 &&
 502                 ergo(parent != NULL, parent->cp_child == pg) &&
 503                 ergo(child != NULL, child->cp_parent == pg) &&
 504                 ergo(child != NULL, pg->cp_obj != child->cp_obj) &&
 505                 ergo(parent != NULL, pg->cp_obj != parent->cp_obj) &&
 506                 ergo(owner != NULL && parent != NULL,
 507                      parent->cp_owner == pg->cp_owner->ci_parent) &&
 508                 ergo(owner != NULL && child != NULL,
 509                      child->cp_owner->ci_parent == owner) &&
 510                 /*
 511                  * Either page is early in initialization (has neither child
 512                  * nor parent yet), or it is in the object radix tree.
 513                  */
 514                 ergo(pg->cp_state < CPS_FREEING,
 515                      (void *)radix_tree_lookup(&header->coh_tree,
 516                                                pg->cp_index) == pg ||
 517                      (child == NULL && parent == NULL));
 518 }
 519
 520 static void cl_page_state_set0(const struct lu_env *env,
 521                                struct cl_page *page, enum cl_page_state state)
 522 {
 523         enum cl_page_state old;
 524         struct cl_site *site = cl_object_site(page->cp_obj);
 525
 526         /*
 527          * Matrix of allowed state transitions [old][new], for sanity
 528          * checking.
 529          */
 530         static const int allowed_transitions[CPS_NR][CPS_NR] = {
 531                 [CPS_CACHED] = {
 532                         [CPS_CACHED]  = 0,
 533                         [CPS_OWNED]   = 1, /* io finds existing cached page */
 534                         [CPS_PAGEIN]  = 0,
 535                         [CPS_PAGEOUT] = 1, /* write-out from the cache */
 536                         [CPS_FREEING] = 1, /* eviction on the memory pressure */
 537                 },
 538                 [CPS_OWNED] = {
 539                         [CPS_CACHED]  = 1, /* release to the cache */
 540                         [CPS_OWNED]   = 0,
 541                         [CPS_PAGEIN]  = 1, /* start read immediately */
 542                         [CPS_PAGEOUT] = 1, /* start write immediately */
 543                         [CPS_FREEING] = 1, /* lock invalidation or truncate */
 544                 },
 545                 [CPS_PAGEIN] = {
 546                         [CPS_CACHED]  = 1, /* io completion */
 547                         [CPS_OWNED]   = 0,
 548                         [CPS_PAGEIN]  = 0,
 549                         [CPS_PAGEOUT] = 0,
 550                         [CPS_FREEING] = 0,
 551                 },
 552                 [CPS_PAGEOUT] = {
 553                         [CPS_CACHED]  = 1, /* io completion */
 554                         [CPS_OWNED]   = 0,
 555                         [CPS_PAGEIN]  = 0,
 556                         [CPS_PAGEOUT] = 0,
 557                         [CPS_FREEING] = 0,
 558                 },
 559                 [CPS_FREEING] = {
 560                         [CPS_CACHED]  = 0,
 561                         [CPS_OWNED]   = 0,
 562                         [CPS_PAGEIN]  = 0,
 563                         [CPS_PAGEOUT] = 0,
 564                         [CPS_FREEING] = 0,
 565                 }
 566         };
 567
 568         ENTRY;
 569         old = page->cp_state;
 570         PASSERT(env, page, allowed_transitions[old][state]);
 571         CL_PAGE_HEADER(D_TRACE, env, page, "%i -> %i\n", old, state);
 572         for (; page != NULL; page = page->cp_child) {
 573                 PASSERT(env, page, page->cp_state == old);
 574                 PASSERT(env, page,
 575                         equi(state == CPS_OWNED, page->cp_owner != NULL));
 576
 577                 atomic_dec(&site->cs_pages_state[page->cp_state]);
 578                 atomic_inc(&site->cs_pages_state[state]);
 579                 cl_page_state_set_trust(page, state);
 580         }
 581         EXIT;
 582 }
 583
 584 static void cl_page_state_set(const struct lu_env *env,
 585                               struct cl_page *page, enum cl_page_state state)
 586 {
 587         PINVRNT(env, page, cl_page_invariant(page));
 588         cl_page_state_set0(env, page, state);
 589 }
 590
 591 /**
 592  * Acquires an additional reference to a page.
 593  *
 594  * This can be called only by caller already possessing a reference to \a
 595  * page.
 596  *
 597  * \see cl_object_get(), cl_lock_get().
 598  */
 599 void cl_page_get(struct cl_page *page)
 600 {
 601         ENTRY;
 602         LASSERT(page->cp_state != CPS_FREEING);
 603         cl_page_get_trust(page);
 604         EXIT;
 605 }
 606 EXPORT_SYMBOL(cl_page_get);
 607
 608 /**
 609  * Releases a reference to a page.
 610  *
 611  * When last reference is released, page is returned to the cache, unless it
 612  * is in cl_page_state::CPS_FREEING state, in which case it is immediately
 613  * destroyed.
 614  *
 615  * \see cl_object_put(), cl_lock_put().
 616  */
 617 void cl_page_put(const struct lu_env *env, struct cl_page *page)
 618 {
 619         struct cl_object_header *hdr;
 620         struct cl_site *site = cl_object_site(page->cp_obj);
 621
 622         PASSERT(env, page, atomic_read(&page->cp_ref) > !!page->cp_parent);
 623
 624         ENTRY;
 625         CL_PAGE_HEADER(D_TRACE, env, page, "%i\n", atomic_read(&page->cp_ref));
 626         hdr = cl_object_header(page->cp_obj);
 627         if (atomic_dec_and_test(&page->cp_ref)) {
 628                 atomic_dec(&site->cs_pages.cs_busy);
 629                 if (page->cp_state == CPS_FREEING) {
 630                         PASSERT(env, page, page->cp_owner == NULL);
 631                         PASSERT(env, page, list_empty(&page->cp_batch));
 632                         /*
 633                          * Page is no longer reachable by other threads. Tear
 634                          * it down.
 635                          */
 636                         cl_page_free(env, page);
 637                 }
 638         }
 639         EXIT;
 640 }
 641 EXPORT_SYMBOL(cl_page_put);
 642
 643 /**
 644  * Returns a VM page associated with a given cl_page.
 645  */
 646 cfs_page_t *cl_page_vmpage(const struct lu_env *env, struct cl_page *page)
 647 {
 648         const struct cl_page_slice *slice;
 649
 650         /*
 651          * Find uppermost layer with ->cpo_vmpage() method, and return its
 652          * result.
 653          */
 654         page = cl_page_top(page);
 655         do {
 656                 list_for_each_entry(slice, &page->cp_layers, cpl_linkage) {
 657                         if (slice->cpl_ops->cpo_vmpage != NULL)
 658                                 RETURN(slice->cpl_ops->cpo_vmpage(env, slice));
 659                 }
 660                 page = page->cp_child;
 661         } while (page != NULL);
 662         LBUG(); /* ->cpo_vmpage() has to be defined somewhere in the stack */
 663 }
 664 EXPORT_SYMBOL(cl_page_vmpage);
 665
 666 /**
 667  * Returns a cl_page associated with a VM page, and given cl_object.
 668  */
 669 struct cl_page *cl_vmpage_page(cfs_page_t *vmpage, struct cl_object *obj)
 670 {
 671         struct cl_page *page;
 672
 673         ENTRY;
 674         KLASSERT(PageLocked(vmpage));
 675
 676         /*
 677          * NOTE: absence of races and liveness of data are guaranteed by page
 678          *       lock on a "vmpage". That works because object destruction has
 679          *       bottom-to-top pass.
 680          */
 681
 682         /*
 683          * This loop assumes that ->private points to the top-most page. This
 684          * can be rectified easily.
 685          */
 686         for (page = (void *)vmpage->private;
 687              page != NULL; page = page->cp_child) {
 688                 if (cl_object_same(page->cp_obj, obj)) {
 689                         cl_page_get_trust(page);
 690                         break;
 691                 }
 692         }
 693         LASSERT(ergo(page, cl_is_page(page) && page->cp_type == CPT_CACHEABLE));
 694         RETURN(page);
 695 }
 696 EXPORT_SYMBOL(cl_vmpage_page);
 697
 698 /**
 699  * Returns the top-page for a given page.
 700  *
 701  * \see cl_object_top(), cl_io_top()
 702  */
 703 struct cl_page *cl_page_top(struct cl_page *page)
 704 {
 705         return cl_page_top_trusted(page);
 706 }
 707 EXPORT_SYMBOL(cl_page_top);
 708
 709 /**
 710  * Returns true if \a addr is an address of an allocated cl_page. Used in
 711  * assertions. This check is optimistically imprecise, i.e., it occasionally
 712  * returns true for the incorrect addresses, but if it returns false, then the
 713  * address is guaranteed to be incorrect. (Should be named cl_pagep().)
 714  *
 715  * \see cl_is_lock()
 716  */
 717 int cl_is_page(const void *addr)
 718 {
 719         return cfs_mem_is_in_cache(addr, cl_page_kmem);
 720 }
 721 EXPORT_SYMBOL(cl_is_page);
 722
 723 const struct cl_page_slice *cl_page_at(const struct cl_page *page,
 724                                        const struct lu_device_type *dtype)
 725 {
 726         return cl_page_at_trusted(page, dtype);
 727 }
 728 EXPORT_SYMBOL(cl_page_at);
 729
 730 #define CL_PAGE_OP(opname) offsetof(struct cl_page_operations, opname)
 731
 732 #define CL_PAGE_INVOKE(_env, _page, _op, _proto, ...)                   \
 733 ({                                                                      \
 734         const struct lu_env        *__env  = (_env);                    \
 735         struct cl_page             *__page = (_page);                   \
 736         const struct cl_page_slice *__scan;                             \
 737         int                         __result;                           \
 738         ptrdiff_t                   __op   = (_op);                     \
 739         int                       (*__method)_proto;                    \
 740                                                                         \
 741         __result = 0;                                                   \
 742         __page = cl_page_top(__page);                                   \
 743         do {                                                            \
 744                 list_for_each_entry(__scan, &__page->cp_layers,         \
 745                                     cpl_linkage) {                      \
 746                         __method = *(void **)((char *)__scan->cpl_ops + \
 747                                               __op);                    \
 748                         if (__method != NULL) {                         \
 749                                 __result = (*__method)(__env, __scan,   \
 750                                                        ## __VA_ARGS__); \
 751                                 if (__result != 0)                      \
 752                                         break;                          \
 753                         }                                               \
 754                 }                                                       \
 755                 __page = __page->cp_child;                              \
 756         } while (__page != NULL && __result == 0);                      \
 757         if (__result > 0)                                               \
 758                 __result = 0;                                           \
 759         __result;                                                       \
 760 })
 761
 762 #define CL_PAGE_INVOID(_env, _page, _op, _proto, ...)                   \
 763 do {                                                                    \
 764         const struct lu_env        *__env  = (_env);                    \
 765         struct cl_page             *__page = (_page);                   \
 766         const struct cl_page_slice *__scan;                             \
 767         ptrdiff_t                   __op   = (_op);                     \
 768         void                      (*__method)_proto;                    \
 769                                                                         \
 770         __page = cl_page_top(__page);                                   \
 771         do {                                                            \
 772                 list_for_each_entry(__scan, &__page->cp_layers,         \
 773                                     cpl_linkage) {                      \
 774                         __method = *(void **)((char *)__scan->cpl_ops + \
 775                                               __op);                    \
 776                         if (__method != NULL)                           \
 777                                 (*__method)(__env, __scan,              \
 778                                             ## __VA_ARGS__);            \
 779                 }                                                       \
 780                 __page = __page->cp_child;                              \
 781         } while (__page != NULL);                                       \
 782 } while (0)
 783
 784 #define CL_PAGE_INVOID_REVERSE(_env, _page, _op, _proto, ...)           \
 785 do {                                                                    \
 786         const struct lu_env        *__env  = (_env);                    \
 787         struct cl_page             *__page = (_page);                   \
 788         const struct cl_page_slice *__scan;                             \
 789         ptrdiff_t                   __op   = (_op);                     \
 790         void                      (*__method)_proto;                    \
 791                                                                         \
 792         /* get to the bottom page. */                                   \
 793         while (__page->cp_child != NULL)                                \
 794                 __page = __page->cp_child;                              \
 795         do {                                                            \
 796                 list_for_each_entry_reverse(__scan, &__page->cp_layers, \
 797                                             cpl_linkage) {              \
 798                         __method = *(void **)((char *)__scan->cpl_ops + \
 799                                               __op);                    \
 800                         if (__method != NULL)                           \
 801                                 (*__method)(__env, __scan,              \
 802                                             ## __VA_ARGS__);            \
 803                 }                                                       \
 804                 __page = __page->cp_parent;                             \
 805         } while (__page != NULL);                                       \
 806 } while (0)
 807
 808 static int cl_page_invoke(const struct lu_env *env,
 809                           struct cl_io *io, struct cl_page *page, ptrdiff_t op)
 810
 811 {
 812         PINVRNT(env, page, cl_object_same(page->cp_obj, io->ci_obj));
 813         ENTRY;
 814         RETURN(CL_PAGE_INVOKE(env, page, op,
 815                               (const struct lu_env *,
 816                                const struct cl_page_slice *, struct cl_io *),
 817                               io));
 818 }
 819
 820 static void cl_page_invoid(const struct lu_env *env,
 821                            struct cl_io *io, struct cl_page *page, ptrdiff_t op)
 822
 823 {
 824         PINVRNT(env, page, cl_object_same(page->cp_obj, io->ci_obj));
 825         ENTRY;
 826         CL_PAGE_INVOID(env, page, op,
 827                        (const struct lu_env *,
 828                         const struct cl_page_slice *, struct cl_io *), io);
 829         EXIT;
 830 }
 831
 832 static void cl_page_owner_clear(struct cl_page *page)
 833 {
 834         ENTRY;
 835         for (page = cl_page_top(page); page != NULL; page = page->cp_child) {
 836                 if (page->cp_owner != NULL) {
 837                         LASSERT(page->cp_owner->ci_owned_nr > 0);
 838                         page->cp_owner->ci_owned_nr--;
 839                         page->cp_owner = NULL;
 840                 }
 841         }
 842         EXIT;
 843 }
 844
 845 static void cl_page_owner_set(struct cl_page *page)
 846 {
 847         ENTRY;
 848         for (page = cl_page_top(page); page != NULL; page = page->cp_child) {
 849                 LASSERT(page->cp_owner != NULL);
 850                 page->cp_owner->ci_owned_nr++;
 851         }
 852         EXIT;
 853 }
 854
 855 void cl_page_disown0(const struct lu_env *env,
 856                      struct cl_io *io, struct cl_page *pg)
 857 {
 858         enum cl_page_state state;
 859
 860         ENTRY;
 861         state = pg->cp_state;
 862         PINVRNT(env, pg, state == CPS_OWNED || state == CPS_FREEING);
 863         PINVRNT(env, pg, cl_page_invariant(pg));
 864         cl_page_owner_clear(pg);
 865
 866         if (state == CPS_OWNED)
 867                 cl_page_state_set(env, pg, CPS_CACHED);
 868         /*
 869          * Completion call-backs are executed in the bottom-up order, so that
 870          * uppermost layer (llite), responsible for VFS/VM interaction runs
 871          * last and can release locks safely.
 872          */
 873         CL_PAGE_INVOID_REVERSE(env, pg, CL_PAGE_OP(cpo_disown),
 874                                (const struct lu_env *,
 875                                 const struct cl_page_slice *, struct cl_io *),
 876                                io);
 877         EXIT;
 878 }
 879
 880 /**
 881  * returns true, iff page is owned by the given io.
 882  */
 883 int cl_page_is_owned(const struct cl_page *pg, const struct cl_io *io)
 884 {
 885         LINVRNT(cl_object_same(pg->cp_obj, io->ci_obj));
 886         ENTRY;
 887         RETURN(pg->cp_state == CPS_OWNED && pg->cp_owner == io);
 888 }
 889 EXPORT_SYMBOL(cl_page_is_owned);
 890
 891 /**
 892  * Owns a page by IO.
 893  *
 894  * Waits until page is in cl_page_state::CPS_CACHED state, and then switch it
 895  * into cl_page_state::CPS_OWNED state.
 896  *
 897  * \pre  !cl_page_is_owned(pg, io)
 898  * \post result == 0 iff cl_page_is_owned(pg, io)
 899  *
 900  * \retval 0   success
 901  *
 902  * \retval -ve failure, e.g., page was destroyed (and landed in
 903  *             cl_page_state::CPS_FREEING instead of cl_page_state::CPS_CACHED).
 904  *
 905  * \see cl_page_disown()
 906  * \see cl_page_operations::cpo_own()
 907  */
 908 int cl_page_own(const struct lu_env *env, struct cl_io *io, struct cl_page *pg)
 909 {
 910         int result;
 911
 912         PINVRNT(env, pg, !cl_page_is_owned(pg, io));
 913
 914         ENTRY;
 915         pg = cl_page_top(pg);
 916         io = cl_io_top(io);
 917
 918         cl_page_invoid(env, io, pg, CL_PAGE_OP(cpo_own));
 919         PASSERT(env, pg, pg->cp_owner == NULL);
 920         PASSERT(env, pg, pg->cp_req == NULL);
 921         pg->cp_owner = io;
 922         cl_page_owner_set(pg);
 923         if (pg->cp_state != CPS_FREEING) {
 924                 cl_page_state_set(env, pg, CPS_OWNED);
 925                 result = 0;
 926         } else {
 927                 cl_page_disown0(env, io, pg);
 928                 result = -EAGAIN;
 929         }
 930         PINVRNT(env, pg, ergo(result == 0, cl_page_invariant(pg)));
 931         RETURN(result);
 932 }
 933 EXPORT_SYMBOL(cl_page_own);
 934
 935 /**
 936  * Assume page ownership.
 937  *
 938  * Called when page is already locked by the hosting VM.
 939  *
 940  * \pre !cl_page_is_owned(pg, io)
 941  * \post cl_page_is_owned(pg, io)
 942  *
 943  * \see cl_page_operations::cpo_assume()
 944  */
 945 void cl_page_assume(const struct lu_env *env,
 946                     struct cl_io *io, struct cl_page *pg)
 947 {
 948         PASSERT(env, pg, pg->cp_state < CPS_OWNED);
 949         PASSERT(env, pg, pg->cp_owner == NULL);
 950         PINVRNT(env, pg, cl_object_same(pg->cp_obj, io->ci_obj));
 951         PINVRNT(env, pg, cl_page_invariant(pg));
 952
 953         ENTRY;
 954         pg = cl_page_top(pg);
 955         io = cl_io_top(io);
 956
 957         cl_page_invoid(env, io, pg, CL_PAGE_OP(cpo_assume));
 958         pg->cp_owner = io;
 959         cl_page_owner_set(pg);
 960         cl_page_state_set(env, pg, CPS_OWNED);
 961         EXIT;
 962 }
 963 EXPORT_SYMBOL(cl_page_assume);
 964
 965 /**
 966  * Releases page ownership without unlocking the page.
 967  *
 968  * Moves page into cl_page_state::CPS_CACHED without releasing a lock on the
 969  * underlying VM page (as VM is supposed to do this itself).
 970  *
 971  * \pre   cl_page_is_owned(pg, io)
 972  * \post !cl_page_is_owned(pg, io)
 973  *
 974  * \see cl_page_assume()
 975  */
 976 void cl_page_unassume(const struct lu_env *env,
 977                       struct cl_io *io, struct cl_page *pg)
 978 {
 979         PINVRNT(env, pg, cl_page_is_owned(pg, io));
 980         PINVRNT(env, pg, cl_page_invariant(pg));
 981
 982         ENTRY;
 983         pg = cl_page_top(pg);
 984         io = cl_io_top(io);
 985         cl_page_owner_clear(pg);
 986         cl_page_state_set(env, pg, CPS_CACHED);
 987         CL_PAGE_INVOID_REVERSE(env, pg, CL_PAGE_OP(cpo_unassume),
 988                                (const struct lu_env *,
 989                                 const struct cl_page_slice *, struct cl_io *),
 990                                io);
 991         EXIT;
 992 }
 993 EXPORT_SYMBOL(cl_page_unassume);
 994
 995 /**
 996  * Releases page ownership.
 997  *
 998  * Moves page into cl_page_state::CPS_CACHED.
 999  *
1000  * \pre   cl_page_is_owned(pg, io)
1001  * \post !cl_page_is_owned(pg, io)
1002  *
1003  * \see cl_page_own()
1004  * \see cl_page_operations::cpo_disown()
1005  */
1006 void cl_page_disown(const struct lu_env *env,
1007                     struct cl_io *io, struct cl_page *pg)
1008 {
1009         PINVRNT(env, pg, cl_page_is_owned(pg, io));
1010
1011         ENTRY;
1012         pg = cl_page_top(pg);
1013         io = cl_io_top(io);
1014         cl_page_disown0(env, io, pg);
1015         EXIT;
1016 }
1017 EXPORT_SYMBOL(cl_page_disown);
1018
1019 /**
1020  * Called when page is to be removed from the object, e.g., as a result of
1021  * truncate.
1022  *
1023  * Calls cl_page_operations::cpo_discard() top-to-bottom.
1024  *
1025  * \pre cl_page_is_owned(pg, io)
1026  *
1027  * \see cl_page_operations::cpo_discard()
1028  */
1029 void cl_page_discard(const struct lu_env *env,
1030                      struct cl_io *io, struct cl_page *pg)
1031 {
1032         PINVRNT(env, pg, cl_page_is_owned(pg, io));
1033         PINVRNT(env, pg, cl_page_invariant(pg));
1034
1035         cl_page_invoid(env, io, pg, CL_PAGE_OP(cpo_discard));
1036 }
1037 EXPORT_SYMBOL(cl_page_discard);
1038
1039 /**
1040  * Version of cl_page_delete() that can be called for not fully constructed
1041  * pages, e.g,. in a error handling cl_page_find()->cl_page_delete0()
1042  * path. Doesn't check page invariant.
1043  */
1044 static void cl_page_delete0(const struct lu_env *env, struct cl_page *pg,
1045                             int radix)
1046 {
1047         PASSERT(env, pg, pg == cl_page_top(pg));
1048         PASSERT(env, pg, pg->cp_state != CPS_FREEING);
1049
1050         ENTRY;
1051         /*
1052          * Severe all ways to obtain new pointers to @pg.
1053          */
1054         cl_page_owner_clear(pg);
1055         cl_page_state_set0(env, pg, CPS_FREEING);
1056         CL_PAGE_INVOID(env, pg, CL_PAGE_OP(cpo_delete),
1057                        (const struct lu_env *, const struct cl_page_slice *));
1058         if (!radix)
1059                 /*
1060                  * !radix means that @pg is not yet in the radix tree, skip
1061                  * removing it.
1062                  */
1063                 pg = pg->cp_child;
1064         for (; pg != NULL; pg = pg->cp_child) {
1065                 void                    *value;
1066                 struct cl_object_header *hdr;
1067
1068                 hdr = cl_object_header(pg->cp_obj);
1069                 spin_lock(&hdr->coh_page_guard);
1070                 value = radix_tree_delete(&hdr->coh_tree, pg->cp_index);
1071                 PASSERT(env, pg, value == pg);
1072                 PASSERT(env, pg, hdr->coh_pages > 0);
1073                 hdr->coh_pages--;
1074                 spin_unlock(&hdr->coh_page_guard);
1075         }
1076         EXIT;
1077 }
1078
1079 /**
1080  * Called when a decision is made to throw page out of memory.
1081  *
1082  * Notifies all layers about page destruction by calling
1083  * cl_page_operations::cpo_delete() method top-to-bottom.
1084  *
1085  * Moves page into cl_page_state::CPS_FREEING state (this is the only place
1086  * where transition to this state happens).
1087  *
1088  * Eliminates all venues through which new references to the page can be
1089  * obtained:
1090  *
1091  *     - removes page from the radix trees,
1092  *
1093  *     - breaks linkage from VM page to cl_page.
1094  *
1095  * Once page reaches cl_page_state::CPS_FREEING, all remaining references will
1096  * drain after some time, at which point page will be recycled.
1097  *
1098  * \pre  pg == cl_page_top(pg)
1099  * \pre  VM page is locked
1100  * \post pg->cp_state == CPS_FREEING
1101  *
1102  * \see cl_page_operations::cpo_delete()
1103  */
1104 void cl_page_delete(const struct lu_env *env, struct cl_page *pg)
1105 {
1106         PINVRNT(env, pg, cl_page_invariant(pg));
1107         ENTRY;
1108         cl_page_delete0(env, pg, 1);
1109         EXIT;
1110 }
1111 EXPORT_SYMBOL(cl_page_delete);
1112
1113 /**
1114  * Unmaps page from user virtual memory.
1115  *
1116  * Calls cl_page_operations::cpo_unmap() through all layers top-to-bottom. The
1117  * layer responsible for VM interaction has to unmap page from user space
1118  * virtual memory.
1119  *
1120  * \see cl_page_operations::cpo_unmap()
1121  */
1122 int cl_page_unmap(const struct lu_env *env,
1123                   struct cl_io *io, struct cl_page *pg)
1124 {
1125         PINVRNT(env, pg, cl_page_is_owned(pg, io));
1126         PINVRNT(env, pg, cl_page_invariant(pg));
1127
1128         return cl_page_invoke(env, io, pg, CL_PAGE_OP(cpo_unmap));
1129 }
1130 EXPORT_SYMBOL(cl_page_unmap);
1131
1132 /**
1133  * Marks page up-to-date.
1134  *
1135  * Call cl_page_operations::cpo_export() through all layers top-to-bottom. The
1136  * layer responsible for VM interaction has to mark page as up-to-date. From
1137  * this moment on, page can be shown to the user space without Lustre being
1138  * notified, hence the name.
1139  *
1140  * \see cl_page_operations::cpo_export()
1141  */
1142 void cl_page_export(const struct lu_env *env, struct cl_page *pg)
1143 {
1144         PINVRNT(env, pg, cl_page_invariant(pg));
1145         CL_PAGE_INVOID(env, pg, CL_PAGE_OP(cpo_export),
1146                        (const struct lu_env *, const struct cl_page_slice *));
1147 }
1148 EXPORT_SYMBOL(cl_page_export);
1149
1150 /**
1151  * Returns true, iff \a pg is VM locked in a suitable sense by the calling
1152  * thread.
1153  */
1154 int cl_page_is_vmlocked(const struct lu_env *env, const struct cl_page *pg)
1155 {
1156         int result;
1157         const struct cl_page_slice *slice;
1158
1159         ENTRY;
1160         pg = cl_page_top_trusted((struct cl_page *)pg);
1161         slice = container_of(pg->cp_layers.next,
1162                              const struct cl_page_slice, cpl_linkage);
1163         PASSERT(env, pg, slice->cpl_ops->cpo_is_vmlocked != NULL);
1164         /*
1165          * Call ->cpo_is_vmlocked() directly instead of going through
1166          * CL_PAGE_INVOKE(), because cl_page_is_vmlocked() is used by
1167          * cl_page_invariant().
1168          */
1169         result = slice->cpl_ops->cpo_is_vmlocked(env, slice);
1170         PASSERT(env, pg, result == -EBUSY || result == -ENODATA);
1171         RETURN(result == -EBUSY);
1172 }
1173 EXPORT_SYMBOL(cl_page_is_vmlocked);
1174
1175 static enum cl_page_state cl_req_type_state(enum cl_req_type crt)
1176 {
1177         ENTRY;
1178         RETURN(crt == CRT_WRITE ? CPS_PAGEOUT : CPS_PAGEIN);
1179 }
1180
1181 static void cl_page_io_start(const struct lu_env *env,
1182                              struct cl_page *pg, enum cl_req_type crt)
1183 {
1184         /*
1185          * Page is queued for IO, change its state.
1186          */
1187         ENTRY;
1188         cl_page_owner_clear(pg);
1189         cl_page_state_set(env, pg, cl_req_type_state(crt));
1190         EXIT;
1191 }
1192
1193 /**
1194  * Prepares page for immediate transfer. cl_page_operations::cpo_prep() is
1195  * called top-to-bottom. Every layer either agrees to submit this page (by
1196  * returning 0), or requests to omit this page (by returning -EALREADY). Layer
1197  * handling interactions with the VM also has to inform VM that page is under
1198  * transfer now.
1199  */
1200 int cl_page_prep(const struct lu_env *env, struct cl_io *io,
1201                  struct cl_page *pg, enum cl_req_type crt)
1202 {
1203         int result;
1204
1205         PINVRNT(env, pg, cl_page_is_owned(pg, io));
1206         PINVRNT(env, pg, cl_page_invariant(pg));
1207         PINVRNT(env, pg, crt < CRT_NR);
1208
1209         /*
1210          * XXX this has to be called bottom-to-top, so that llite can set up
1211          * PG_writeback without risking other layers deciding to skip this
1212          * page.
1213          */
1214         result = cl_page_invoke(env, io, pg, CL_PAGE_OP(io[crt].cpo_prep));
1215         if (result == 0)
1216                 cl_page_io_start(env, pg, crt);
1217
1218         KLASSERT(ergo(crt == CRT_WRITE && pg->cp_type == CPT_CACHEABLE,
1219                       equi(result == 0,
1220                            PageWriteback(cl_page_vmpage(env, pg)))));
1221         CL_PAGE_HEADER(D_TRACE, env, pg, "%i %i\n", crt, result);
1222         return result;
1223 }
1224 EXPORT_SYMBOL(cl_page_prep);
1225
1226 /**
1227  * Notify layers about transfer completion.
1228  *
1229  * Invoked by transfer sub-system (which is a part of osc) to notify layers
1230  * that a transfer, of which this page is a part of has completed.
1231  *
1232  * Completion call-backs are executed in the bottom-up order, so that
1233  * uppermost layer (llite), responsible for the VFS/VM interaction runs last
1234  * and can release locks safely.
1235  *
1236  * \pre  pg->cp_state == CPS_PAGEIN || pg->cp_state == CPS_PAGEOUT
1237  * \post pg->cp_state == CPS_CACHED
1238  *
1239  * \see cl_page_operations::cpo_completion()
1240  */
1241 void cl_page_completion(const struct lu_env *env,
1242                         struct cl_page *pg, enum cl_req_type crt, int ioret)
1243 {
1244         PASSERT(env, pg, crt < CRT_NR);
1245         /* cl_page::cp_req already cleared by the caller (osc_completion()) */
1246         PASSERT(env, pg, pg->cp_req == NULL);
1247         PASSERT(env, pg, pg->cp_state == cl_req_type_state(crt));
1248         PINVRNT(env, pg, cl_page_invariant(pg));
1249
1250         ENTRY;
1251         CL_PAGE_HEADER(D_TRACE, env, pg, "%i %i\n", crt, ioret);
1252         if (crt == CRT_READ && ioret == 0) {
1253                 PASSERT(env, pg, !(pg->cp_flags & CPF_READ_COMPLETED));
1254                 pg->cp_flags |= CPF_READ_COMPLETED;
1255         }
1256
1257         cl_page_state_set(env, pg, CPS_CACHED);
1258         CL_PAGE_INVOID_REVERSE(env, pg, CL_PAGE_OP(io[crt].cpo_completion),
1259                                (const struct lu_env *,
1260                                 const struct cl_page_slice *, int), ioret);
1261
1262         /* Don't assert the page writeback bit here because the lustre file
1263          * may be as a backend of swap space. in this case, the page writeback
1264          * is set by VM, and obvious we shouldn't clear it at all. Fortunately
1265          * this type of pages are all TRANSIENT pages. */
1266         KLASSERT(ergo(pg->cp_type == CPT_CACHEABLE,
1267                       !PageWriteback(cl_page_vmpage(env, pg))));
1268         EXIT;
1269 }
1270 EXPORT_SYMBOL(cl_page_completion);
1271
1272 /**
1273  * Notify layers that transfer formation engine decided to yank this page from
1274  * the cache and to make it a part of a transfer.
1275  *
1276  * \pre  pg->cp_state == CPS_CACHED
1277  * \post pg->cp_state == CPS_PAGEIN || pg->cp_state == CPS_PAGEOUT
1278  *
1279  * \see cl_page_operations::cpo_make_ready()
1280  */
1281 int cl_page_make_ready(const struct lu_env *env, struct cl_page *pg,
1282                        enum cl_req_type crt)
1283 {
1284         int result;
1285
1286         PINVRNT(env, pg, crt < CRT_NR);
1287
1288         ENTRY;
1289         result = CL_PAGE_INVOKE(env, pg, CL_PAGE_OP(io[crt].cpo_make_ready),
1290                                 (const struct lu_env *,
1291                                  const struct cl_page_slice *));
1292         if (result == 0) {
1293                 PASSERT(env, pg, pg->cp_state == CPS_CACHED);
1294                 cl_page_io_start(env, pg, crt);
1295         }
1296         CL_PAGE_HEADER(D_TRACE, env, pg, "%i %i\n", crt, result);
1297         RETURN(result);
1298 }
1299 EXPORT_SYMBOL(cl_page_make_ready);
1300
1301 /**
1302  * Notify layers that high level io decided to place this page into a cache
1303  * for future transfer.
1304  *
1305  * The layer implementing transfer engine (osc) has to register this page in
1306  * its queues.
1307  *
1308  * \pre  cl_page_is_owned(pg, io)
1309  * \post ergo(result == 0,
1310  *            pg->cp_state == CPS_PAGEIN || pg->cp_state == CPS_PAGEOUT)
1311  *
1312  * \see cl_page_operations::cpo_cache_add()
1313  */
1314 int cl_page_cache_add(const struct lu_env *env, struct cl_io *io,
1315                       struct cl_page *pg, enum cl_req_type crt)
1316 {
1317         int result;
1318
1319         PINVRNT(env, pg, crt < CRT_NR);
1320         PINVRNT(env, pg, cl_page_is_owned(pg, io));
1321         PINVRNT(env, pg, cl_page_invariant(pg));
1322
1323         ENTRY;
1324         result = cl_page_invoke(env, io, pg, CL_PAGE_OP(io[crt].cpo_cache_add));
1325         if (result == 0) {
1326                 cl_page_owner_clear(pg);
1327                 cl_page_state_set(env, pg, CPS_CACHED);
1328         }
1329         CL_PAGE_HEADER(D_TRACE, env, pg, "%i %i\n", crt, result);
1330         RETURN(result);
1331 }
1332 EXPORT_SYMBOL(cl_page_cache_add);
1333
1334 /**
1335  * Checks whether page is protected by any extent lock is at least required
1336  * mode.
1337  *
1338  * \return the same as in cl_page_operations::cpo_is_under_lock() method.
1339  * \see cl_page_operations::cpo_is_under_lock()
1340  */
1341 int cl_page_is_under_lock(const struct lu_env *env, struct cl_io *io,
1342                           struct cl_page *page)
1343 {
1344         int rc;
1345
1346         PINVRNT(env, page, cl_page_invariant(page));
1347
1348         ENTRY;
1349         rc = CL_PAGE_INVOKE(env, page, CL_PAGE_OP(cpo_is_under_lock),
1350                             (const struct lu_env *,
1351                              const struct cl_page_slice *, struct cl_io *),
1352                             io);
1353         PASSERT(env, page, rc != 0);
1354         RETURN(rc);
1355 }
1356 EXPORT_SYMBOL(cl_page_is_under_lock);
1357
1358 /**
1359  * Purges all cached pages belonging to the object \a obj.
1360  */
1361 int cl_pages_prune(const struct lu_env *env, struct cl_object *clobj)
1362 {
1363         struct cl_thread_info   *info;
1364         struct cl_object        *obj = cl_object_top(clobj);
1365         struct cl_io            *io;
1366         struct cl_page_list     *plist;
1367         int                      result;
1368
1369         ENTRY;
1370         info  = cl_env_info(env);
1371         plist = &info->clt_list;
1372         io    = &info->clt_io;
1373
1374         /*
1375          * initialize the io. This is ugly since we never do IO in this
1376          * function, we just make cl_page_list functions happy. -jay
1377          */
1378         io->ci_obj = obj;
1379         result = cl_io_init(env, io, CIT_MISC, obj);
1380         if (result != 0) {
1381                 cl_io_fini(env, io);
1382                 RETURN(io->ci_result);
1383         }
1384
1385         cl_page_list_init(plist);
1386         cl_page_gang_lookup(env, obj, io, 0, CL_PAGE_EOF, plist);
1387         /*
1388          * Since we're purging the pages of an object, we don't care
1389          * the possible outcomes of the following functions.
1390          */
1391         cl_page_list_unmap(env, io, plist);
1392         cl_page_list_discard(env, io, plist);
1393         cl_page_list_disown(env, io, plist);
1394         cl_page_list_fini(env, plist);
1395
1396         cl_io_fini(env, io);
1397         RETURN(result);
1398 }
1399 EXPORT_SYMBOL(cl_pages_prune);
1400
1401 /**
1402  * Tells transfer engine that only part of a page is to be transmitted.
1403  *
1404  * \see cl_page_operations::cpo_clip()
1405  */
1406 void cl_page_clip(const struct lu_env *env, struct cl_page *pg,
1407                   int from, int to)
1408 {
1409         PINVRNT(env, pg, cl_page_invariant(pg));
1410
1411         CL_PAGE_HEADER(D_TRACE, env, pg, "%i %i\n", from, to);
1412         CL_PAGE_INVOID(env, pg, CL_PAGE_OP(cpo_clip),
1413                        (const struct lu_env *,
1414                         const struct cl_page_slice *,int, int),
1415                        from, to);
1416 }
1417 EXPORT_SYMBOL(cl_page_clip);
1418
1419 /**
1420  * Prints human readable representation of \a pg to the \a f.
1421  */
1422 void cl_page_header_print(const struct lu_env *env, void *cookie,
1423                           lu_printer_t printer, const struct cl_page *pg)
1424 {
1425         (*printer)(env, cookie,
1426                    "page@%p[%d %p:%lu ^%p_%p %d %d %d %p %p %#x]\n",
1427                    pg, atomic_read(&pg->cp_ref), pg->cp_obj,
1428                    pg->cp_index, pg->cp_parent, pg->cp_child,
1429                    pg->cp_state, pg->cp_error, pg->cp_type,
1430                    pg->cp_owner, pg->cp_req, pg->cp_flags);
1431 }
1432 EXPORT_SYMBOL(cl_page_header_print);
1433
1434 /**
1435  * Prints human readable representation of \a pg to the \a f.
1436  */
1437 void cl_page_print(const struct lu_env *env, void *cookie,
1438                    lu_printer_t printer, const struct cl_page *pg)
1439 {
1440         struct cl_page *scan;
1441
1442         for (scan = cl_page_top((struct cl_page *)pg);
1443              scan != NULL; scan = scan->cp_child)
1444                 cl_page_header_print(env, cookie, printer, scan);
1445         CL_PAGE_INVOKE(env, (struct cl_page *)pg, CL_PAGE_OP(cpo_print),
1446                        (const struct lu_env *env,
1447                         const struct cl_page_slice *slice,
1448                         void *cookie, lu_printer_t p), cookie, printer);
1449         (*printer)(env, cookie, "end page@%p\n", pg);
1450 }
1451 EXPORT_SYMBOL(cl_page_print);
1452
1453 /**
1454  * Cancel a page which is still in a transfer.
1455  */
1456 int cl_page_cancel(const struct lu_env *env, struct cl_page *page)
1457 {
1458         return CL_PAGE_INVOKE(env, page, CL_PAGE_OP(cpo_cancel),
1459                               (const struct lu_env *,
1460                                const struct cl_page_slice *));
1461 }
1462 EXPORT_SYMBOL(cl_page_cancel);
1463
1464 /**
1465  * Converts a byte offset within object \a obj into a page index.
1466  */
1467 loff_t cl_offset(const struct cl_object *obj, pgoff_t idx)
1468 {
1469         /*
1470          * XXX for now.
1471          */
1472         return (loff_t)idx << CFS_PAGE_SHIFT;
1473 }
1474 EXPORT_SYMBOL(cl_offset);
1475
1476 /**
1477  * Converts a page index into a byte offset within object \a obj.
1478  */
1479 pgoff_t cl_index(const struct cl_object *obj, loff_t offset)
1480 {
1481         /*
1482          * XXX for now.
1483          */
1484         return offset >> CFS_PAGE_SHIFT;
1485 }
1486 EXPORT_SYMBOL(cl_index);
1487
1488 int cl_page_size(const struct cl_object *obj)
1489 {
1490         return 1 << CFS_PAGE_SHIFT;
1491 }
1492 EXPORT_SYMBOL(cl_page_size);
1493
1494 /**
1495  * Adds page slice to the compound page.
1496  *
1497  * This is called by cl_object_operations::coo_page_init() methods to add a
1498  * per-layer state to the page. New state is added at the end of
1499  * cl_page::cp_layers list, that is, it is at the bottom of the stack.
1500  *
1501  * \see cl_lock_slice_add(), cl_req_slice_add(), cl_io_slice_add()
1502  */
1503 void cl_page_slice_add(struct cl_page *page, struct cl_page_slice *slice,
1504                        struct cl_object *obj,
1505                        const struct cl_page_operations *ops)
1506 {
1507         ENTRY;
1508         list_add_tail(&slice->cpl_linkage, &page->cp_layers);
1509         slice->cpl_obj  = obj;
1510         slice->cpl_ops  = ops;
1511         slice->cpl_page = page;
1512         EXIT;
1513 }
1514 EXPORT_SYMBOL(cl_page_slice_add);
1515
1516 int  cl_page_init(void)
1517 {
1518         return lu_kmem_init(cl_page_caches);
1519 }
1520
1521 void cl_page_fini(void)
1522 {
1523         lu_kmem_fini(cl_page_caches);
1524 }