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, 2012, Whamcloud, Inc.
  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
  43 #include <libcfs/libcfs.h>
  44 #include <obd_class.h>
  45 #include <obd_support.h>
  46 #include <libcfs/list.h>
  47
  48 #include <cl_object.h>
  49 #include "cl_internal.h"
  50
  51 static void cl_page_delete0(const struct lu_env *env, struct cl_page *pg,
  52                             int radix);
  53
  54 static cfs_mem_cache_t      *cl_page_kmem = NULL;
  55
  56 static struct lu_kmem_descr cl_page_caches[] = {
  57         {
  58                 .ckd_cache = &cl_page_kmem,
  59                 .ckd_name  = "cl_page_kmem",
  60                 .ckd_size  = sizeof (struct cl_page)
  61         },
  62         {
  63                 .ckd_cache = NULL
  64         }
  65 };
  66
  67 #ifdef LIBCFS_DEBUG
  68 # define PASSERT(env, page, expr)                                       \
  69   do {                                                                    \
  70           if (unlikely(!(expr))) {                                      \
  71                   CL_PAGE_DEBUG(D_ERROR, (env), (page), #expr "\n");    \
  72                   LASSERT(0);                                           \
  73           }                                                             \
  74   } while (0)
  75 #else /* !LIBCFS_DEBUG */
  76 # define PASSERT(env, page, exp) \
  77         ((void)sizeof(env), (void)sizeof(page), (void)sizeof !!(exp))
  78 #endif /* !LIBCFS_DEBUG */
  79
  80 #ifdef INVARIANT_CHECK
  81 # define PINVRNT(env, page, expr)                                       \
  82   do {                                                                    \
  83           if (unlikely(!(expr))) {                                      \
  84                   CL_PAGE_DEBUG(D_ERROR, (env), (page), #expr "\n");    \
  85                   LINVRNT(0);                                           \
  86           }                                                             \
  87   } while (0)
  88 #else /* !INVARIANT_CHECK */
  89 # define PINVRNT(env, page, exp) \
  90         ((void)sizeof(env), (void)sizeof(page), (void)sizeof !!(exp))
  91 #endif /* !INVARIANT_CHECK */
  92
  93 /* Disable page statistic by default due to huge performance penalty. */
  94 #ifdef CONFIG_DEBUG_PAGESTATE_TRACKING
  95 #define CS_PAGE_INC(o, item) \
  96         cfs_atomic_inc(&cl_object_site(o)->cs_pages.cs_stats[CS_##item])
  97 #define CS_PAGE_DEC(o, item) \
  98         cfs_atomic_dec(&cl_object_site(o)->cs_pages.cs_stats[CS_##item])
  99 #define CS_PAGESTATE_INC(o, state) \
 100         cfs_atomic_inc(&cl_object_site(o)->cs_pages_state[state])
 101 #define CS_PAGESTATE_DEC(o, state) \
 102         cfs_atomic_dec(&cl_object_site(o)->cs_pages_state[state])
 103 #else
 104 #define CS_PAGE_INC(o, item)
 105 #define CS_PAGE_DEC(o, item)
 106 #define CS_PAGESTATE_INC(o, state)
 107 #define CS_PAGESTATE_DEC(o, state)
 108 #endif
 109
 110 /**
 111  * Internal version of cl_page_top, it should be called if the page is
 112  * known to be not freed, says with page referenced, or radix tree lock held,
 113  * or page owned.
 114  */
 115 static struct cl_page *cl_page_top_trusted(struct cl_page *page)
 116 {
 117         while (page->cp_parent != NULL)
 118                 page = page->cp_parent;
 119         return page;
 120 }
 121
 122 /**
 123  * Internal version of cl_page_get().
 124  *
 125  * This function can be used to obtain initial reference to previously
 126  * unreferenced cached object. It can be called only if concurrent page
 127  * reclamation is somehow prevented, e.g., by locking page radix-tree
 128  * (cl_object_header::hdr->coh_page_guard), or by keeping a lock on a VM page,
 129  * associated with \a page.
 130  *
 131  * Use with care! Not exported.
 132  */
 133 static void cl_page_get_trust(struct cl_page *page)
 134 {
 135         LASSERT(cfs_atomic_read(&page->cp_ref) > 0);
 136         cfs_atomic_inc(&page->cp_ref);
 137 }
 138
 139 /**
 140  * Returns a slice within a page, corresponding to the given layer in the
 141  * device stack.
 142  *
 143  * \see cl_lock_at()
 144  */
 145 static const struct cl_page_slice *
 146 cl_page_at_trusted(const struct cl_page *page,
 147                    const struct lu_device_type *dtype)
 148 {
 149         const struct cl_page_slice *slice;
 150         ENTRY;
 151
 152         page = cl_page_top_trusted((struct cl_page *)page);
 153         do {
 154                 cfs_list_for_each_entry(slice, &page->cp_layers, cpl_linkage) {
 155                         if (slice->cpl_obj->co_lu.lo_dev->ld_type == dtype)
 156                                 RETURN(slice);
 157                 }
 158                 page = page->cp_child;
 159         } while (page != NULL);
 160         RETURN(NULL);
 161 }
 162
 163 /**
 164  * Returns a page with given index in the given object, or NULL if no page is
 165  * found. Acquires a reference on \a page.
 166  *
 167  * Locking: called under cl_object_header::coh_page_guard spin-lock.
 168  */
 169 struct cl_page *cl_page_lookup(struct cl_object_header *hdr, pgoff_t index)
 170 {
 171         struct cl_page *page;
 172
 173         LASSERT_SPIN_LOCKED(&hdr->coh_page_guard);
 174
 175         page = radix_tree_lookup(&hdr->coh_tree, index);
 176         if (page != NULL)
 177                 cl_page_get_trust(page);
 178         return page;
 179 }
 180 EXPORT_SYMBOL(cl_page_lookup);
 181
 182 /**
 183  * Returns a list of pages by a given [start, end] of \a obj.
 184  *
 185  * \param resched If not NULL, then we give up before hogging CPU for too
 186  * long and set *resched = 1, in that case caller should implement a retry
 187  * logic.
 188  *
 189  * Gang tree lookup (radix_tree_gang_lookup()) optimization is absolutely
 190  * crucial in the face of [offset, EOF] locks.
 191  *
 192  * Return at least one page in @queue unless there is no covered page.
 193  */
 194 int cl_page_gang_lookup(const struct lu_env *env, struct cl_object *obj,
 195                         struct cl_io *io, pgoff_t start, pgoff_t end,
 196                         cl_page_gang_cb_t cb, void *cbdata)
 197 {
 198         struct cl_object_header *hdr;
 199         struct cl_page          *page;
 200         struct cl_page         **pvec;
 201         const struct cl_page_slice  *slice;
 202         const struct lu_device_type *dtype;
 203         pgoff_t                  idx;
 204         unsigned int             nr;
 205         unsigned int             i;
 206         unsigned int             j;
 207         int                      res = CLP_GANG_OKAY;
 208         int                      tree_lock = 1;
 209         ENTRY;
 210
 211         idx = start;
 212         hdr = cl_object_header(obj);
 213         pvec = cl_env_info(env)->clt_pvec;
 214         dtype = cl_object_top(obj)->co_lu.lo_dev->ld_type;
 215         spin_lock(&hdr->coh_page_guard);
 216         while ((nr = radix_tree_gang_lookup(&hdr->coh_tree, (void **)pvec,
 217                                             idx, CLT_PVEC_SIZE)) > 0) {
 218                 int end_of_region = 0;
 219                 idx = pvec[nr - 1]->cp_index + 1;
 220                 for (i = 0, j = 0; i < nr; ++i) {
 221                         page = pvec[i];
 222                         pvec[i] = NULL;
 223
 224                         LASSERT(page->cp_type == CPT_CACHEABLE);
 225                         if (page->cp_index > end) {
 226                                 end_of_region = 1;
 227                                 break;
 228                         }
 229                         if (page->cp_state == CPS_FREEING)
 230                                 continue;
 231
 232                         slice = cl_page_at_trusted(page, dtype);
 233                         /*
 234                          * Pages for lsm-less file has no underneath sub-page
 235                          * for osc, in case of ...
 236                          */
 237                         PASSERT(env, page, slice != NULL);
 238
 239                         page = slice->cpl_page;
 240                         /*
 241                          * Can safely call cl_page_get_trust() under
 242                          * radix-tree spin-lock.
 243                          *
 244                          * XXX not true, because @page is from object another
 245                          * than @hdr and protected by different tree lock.
 246                          */
 247                         cl_page_get_trust(page);
 248                         lu_ref_add_atomic(&page->cp_reference,
 249                                           "gang_lookup", cfs_current());
 250                         pvec[j++] = page;
 251                 }
 252
 253                 /*
 254                  * Here a delicate locking dance is performed. Current thread
 255                  * holds a reference to a page, but has to own it before it
 256                  * can be placed into queue. Owning implies waiting, so
 257                  * radix-tree lock is to be released. After a wait one has to
 258                  * check that pages weren't truncated (cl_page_own() returns
 259                  * error in the latter case).
 260                  */
 261                 spin_unlock(&hdr->coh_page_guard);
 262                 tree_lock = 0;
 263
 264                 for (i = 0; i < j; ++i) {
 265                         page = pvec[i];
 266                         if (res == CLP_GANG_OKAY)
 267                                 res = (*cb)(env, io, page, cbdata);
 268                         lu_ref_del(&page->cp_reference,
 269                                    "gang_lookup", cfs_current());
 270                         cl_page_put(env, page);
 271                 }
 272                 if (nr < CLT_PVEC_SIZE || end_of_region)
 273                         break;
 274
 275                 if (res == CLP_GANG_OKAY && cfs_need_resched())
 276                         res = CLP_GANG_RESCHED;
 277                 if (res != CLP_GANG_OKAY)
 278                         break;
 279
 280                 spin_lock(&hdr->coh_page_guard);
 281                 tree_lock = 1;
 282         }
 283         if (tree_lock)
 284                 spin_unlock(&hdr->coh_page_guard);
 285         RETURN(res);
 286 }
 287 EXPORT_SYMBOL(cl_page_gang_lookup);
 288
 289 static void cl_page_free(const struct lu_env *env, struct cl_page *page)
 290 {
 291         struct cl_object *obj  = page->cp_obj;
 292
 293         PASSERT(env, page, cfs_list_empty(&page->cp_batch));
 294         PASSERT(env, page, page->cp_owner == NULL);
 295         PASSERT(env, page, page->cp_req == NULL);
 296         PASSERT(env, page, page->cp_parent == NULL);
 297         PASSERT(env, page, page->cp_state == CPS_FREEING);
 298
 299         ENTRY;
 300         cfs_might_sleep();
 301         while (!cfs_list_empty(&page->cp_layers)) {
 302                 struct cl_page_slice *slice;
 303
 304                 slice = cfs_list_entry(page->cp_layers.next,
 305                                        struct cl_page_slice, cpl_linkage);
 306                 cfs_list_del_init(page->cp_layers.next);
 307                 slice->cpl_ops->cpo_fini(env, slice);
 308         }
 309         CS_PAGE_DEC(obj, total);
 310         CS_PAGESTATE_DEC(obj, page->cp_state);
 311         lu_object_ref_del_at(&obj->co_lu, page->cp_obj_ref, "cl_page", page);
 312         cl_object_put(env, obj);
 313         lu_ref_fini(&page->cp_reference);
 314         OBD_SLAB_FREE_PTR(page, cl_page_kmem);
 315         EXIT;
 316 }
 317
 318 /**
 319  * Helper function updating page state. This is the only place in the code
 320  * where cl_page::cp_state field is mutated.
 321  */
 322 static inline void cl_page_state_set_trust(struct cl_page *page,
 323                                            enum cl_page_state state)
 324 {
 325         /* bypass const. */
 326         *(enum cl_page_state *)&page->cp_state = state;
 327 }
 328
 329 static int cl_page_alloc(const struct lu_env *env, struct cl_object *o,
 330                          pgoff_t ind, struct page *vmpage,
 331                          enum cl_page_type type, struct cl_page **out)
 332 {
 333         struct cl_page          *page;
 334         struct cl_page          *err  = NULL;
 335         struct lu_object_header *head;
 336         int                      result;
 337
 338         ENTRY;
 339         result = +1;
 340         OBD_SLAB_ALLOC_PTR_GFP(page, cl_page_kmem, CFS_ALLOC_IO);
 341         if (page != NULL) {
 342                 cfs_atomic_set(&page->cp_ref, 1);
 343                 if (type == CPT_CACHEABLE) /* for radix tree */
 344                         cfs_atomic_inc(&page->cp_ref);
 345                 page->cp_obj = o;
 346                 cl_object_get(o);
 347                 page->cp_obj_ref = lu_object_ref_add(&o->co_lu,
 348                                                      "cl_page", page);
 349                 page->cp_index = ind;
 350                 cl_page_state_set_trust(page, CPS_CACHED);
 351                 page->cp_type = type;
 352                 CFS_INIT_LIST_HEAD(&page->cp_layers);
 353                 CFS_INIT_LIST_HEAD(&page->cp_batch);
 354                 CFS_INIT_LIST_HEAD(&page->cp_flight);
 355                 mutex_init(&page->cp_mutex);
 356                 lu_ref_init(&page->cp_reference);
 357                 head = o->co_lu.lo_header;
 358                 cfs_list_for_each_entry(o, &head->loh_layers,
 359                                         co_lu.lo_linkage) {
 360                         if (o->co_ops->coo_page_init != NULL) {
 361                                 err = o->co_ops->coo_page_init(env, o,
 362                                                                page, vmpage);
 363                                 if (err != NULL) {
 364                                         cl_page_delete0(env, page, 0);
 365                                         cl_page_free(env, page);
 366                                         page = err;
 367                                         break;
 368                                 }
 369                         }
 370                 }
 371                 if (err == NULL) {
 372                         CS_PAGE_INC(o, total);
 373                         CS_PAGE_INC(o, create);
 374                         CS_PAGESTATE_DEC(o, CPS_CACHED);
 375                         result = 0;
 376                 }
 377         } else
 378                 page = ERR_PTR(-ENOMEM);
 379         *out = page;
 380         RETURN(result);
 381 }
 382
 383 /**
 384  * Returns a cl_page with index \a idx at the object \a o, and associated with
 385  * the VM page \a vmpage.
 386  *
 387  * This is the main entry point into the cl_page caching interface. First, a
 388  * cache (implemented as a per-object radix tree) is consulted. If page is
 389  * found there, it is returned immediately. Otherwise new page is allocated
 390  * and returned. In any case, additional reference to page is acquired.
 391  *
 392  * \see cl_object_find(), cl_lock_find()
 393  */
 394 static struct cl_page *cl_page_find0(const struct lu_env *env,
 395                                      struct cl_object *o,
 396                                      pgoff_t idx, struct page *vmpage,
 397                                      enum cl_page_type type,
 398                                      struct cl_page *parent)
 399 {
 400         struct cl_page          *page = NULL;
 401         struct cl_page          *ghost = NULL;
 402         struct cl_object_header *hdr;
 403         int err;
 404
 405         LASSERT(type == CPT_CACHEABLE || type == CPT_TRANSIENT);
 406         cfs_might_sleep();
 407
 408         ENTRY;
 409
 410         hdr = cl_object_header(o);
 411         CS_PAGE_INC(o, lookup);
 412
 413         CDEBUG(D_PAGE, "%lu@"DFID" %p %lx %d\n",
 414                idx, PFID(&hdr->coh_lu.loh_fid), vmpage, vmpage->private, type);
 415         /* fast path. */
 416         if (type == CPT_CACHEABLE) {
 417                 /* vmpage lock is used to protect the child/parent
 418                  * relationship */
 419                 KLASSERT(PageLocked(vmpage));
 420                 /*
 421                  * cl_vmpage_page() can be called here without any locks as
 422                  *
 423                  *     - "vmpage" is locked (which prevents ->private from
 424                  *       concurrent updates), and
 425                  *
 426                  *     - "o" cannot be destroyed while current thread holds a
 427                  *       reference on it.
 428                  */
 429                 page = cl_vmpage_page(vmpage, o);
 430                 PINVRNT(env, page,
 431                         ergo(page != NULL,
 432                              cl_page_vmpage(env, page) == vmpage &&
 433                              (void *)radix_tree_lookup(&hdr->coh_tree,
 434                                                        idx) == page));
 435         }
 436
 437         if (page != NULL) {
 438                 CS_PAGE_INC(o, hit);
 439                 RETURN(page);
 440         }
 441
 442         /* allocate and initialize cl_page */
 443         err = cl_page_alloc(env, o, idx, vmpage, type, &page);
 444         if (err != 0)
 445                 RETURN(page);
 446
 447         if (type == CPT_TRANSIENT) {
 448                 if (parent) {
 449                         LASSERT(page->cp_parent == NULL);
 450                         page->cp_parent = parent;
 451                         parent->cp_child = page;
 452                 }
 453                 RETURN(page);
 454         }
 455
 456         /*
 457          * XXX optimization: use radix_tree_preload() here, and change tree
 458          * gfp mask to GFP_KERNEL in cl_object_header_init().
 459          */
 460         spin_lock(&hdr->coh_page_guard);
 461         err = radix_tree_insert(&hdr->coh_tree, idx, page);
 462         if (err != 0) {
 463                 ghost = page;
 464                 /*
 465                  * Noted by Jay: a lock on \a vmpage protects cl_page_find()
 466                  * from this race, but
 467                  *
 468                  *     0. it's better to have cl_page interface "locally
 469                  *     consistent" so that its correctness can be reasoned
 470                  *     about without appealing to the (obscure world of) VM
 471                  *     locking.
 472                  *
 473                  *     1. handling this race allows ->coh_tree to remain
 474                  *     consistent even when VM locking is somehow busted,
 475                  *     which is very useful during diagnosing and debugging.
 476                  */
 477                 page = ERR_PTR(err);
 478                 CL_PAGE_DEBUG(D_ERROR, env, ghost,
 479                               "fail to insert into radix tree: %d\n", err);
 480         } else {
 481                 if (parent) {
 482                         LASSERT(page->cp_parent == NULL);
 483                         page->cp_parent = parent;
 484                         parent->cp_child = page;
 485                 }
 486                 hdr->coh_pages++;
 487         }
 488         spin_unlock(&hdr->coh_page_guard);
 489
 490         if (unlikely(ghost != NULL)) {
 491                 cl_page_delete0(env, ghost, 0);
 492                 cl_page_free(env, ghost);
 493         }
 494         RETURN(page);
 495 }
 496
 497 struct cl_page *cl_page_find(const struct lu_env *env, struct cl_object *o,
 498                              pgoff_t idx, struct page *vmpage,
 499                              enum cl_page_type type)
 500 {
 501         return cl_page_find0(env, o, idx, vmpage, type, NULL);
 502 }
 503 EXPORT_SYMBOL(cl_page_find);
 504
 505
 506 struct cl_page *cl_page_find_sub(const struct lu_env *env, struct cl_object *o,
 507                                  pgoff_t idx, struct page *vmpage,
 508                                  struct cl_page *parent)
 509 {
 510         return cl_page_find0(env, o, idx, vmpage, parent->cp_type, parent);
 511 }
 512 EXPORT_SYMBOL(cl_page_find_sub);
 513
 514 static inline int cl_page_invariant(const struct cl_page *pg)
 515 {
 516         struct cl_object_header *header;
 517         struct cl_page          *parent;
 518         struct cl_page          *child;
 519         struct cl_io            *owner;
 520
 521         /*
 522          * Page invariant is protected by a VM lock.
 523          */
 524         LINVRNT(cl_page_is_vmlocked(NULL, pg));
 525
 526         header = cl_object_header(pg->cp_obj);
 527         parent = pg->cp_parent;
 528         child  = pg->cp_child;
 529         owner  = pg->cp_owner;
 530
 531         return cl_page_in_use(pg) &&
 532                 ergo(parent != NULL, parent->cp_child == pg) &&
 533                 ergo(child != NULL, child->cp_parent == pg) &&
 534                 ergo(child != NULL, pg->cp_obj != child->cp_obj) &&
 535                 ergo(parent != NULL, pg->cp_obj != parent->cp_obj) &&
 536                 ergo(owner != NULL && parent != NULL,
 537                      parent->cp_owner == pg->cp_owner->ci_parent) &&
 538                 ergo(owner != NULL && child != NULL,
 539                      child->cp_owner->ci_parent == owner) &&
 540                 /*
 541                  * Either page is early in initialization (has neither child
 542                  * nor parent yet), or it is in the object radix tree.
 543                  */
 544                 ergo(pg->cp_state < CPS_FREEING && pg->cp_type == CPT_CACHEABLE,
 545                      (void *)radix_tree_lookup(&header->coh_tree,
 546                                                pg->cp_index) == pg ||
 547                      (child == NULL && parent == NULL));
 548 }
 549
 550 static void cl_page_state_set0(const struct lu_env *env,
 551                                struct cl_page *page, enum cl_page_state state)
 552 {
 553         enum cl_page_state old;
 554
 555         /*
 556          * Matrix of allowed state transitions [old][new], for sanity
 557          * checking.
 558          */
 559         static const int allowed_transitions[CPS_NR][CPS_NR] = {
 560                 [CPS_CACHED] = {
 561                         [CPS_CACHED]  = 0,
 562                         [CPS_OWNED]   = 1, /* io finds existing cached page */
 563                         [CPS_PAGEIN]  = 0,
 564                         [CPS_PAGEOUT] = 1, /* write-out from the cache */
 565                         [CPS_FREEING] = 1, /* eviction on the memory pressure */
 566                 },
 567                 [CPS_OWNED] = {
 568                         [CPS_CACHED]  = 1, /* release to the cache */
 569                         [CPS_OWNED]   = 0,
 570                         [CPS_PAGEIN]  = 1, /* start read immediately */
 571                         [CPS_PAGEOUT] = 1, /* start write immediately */
 572                         [CPS_FREEING] = 1, /* lock invalidation or truncate */
 573                 },
 574                 [CPS_PAGEIN] = {
 575                         [CPS_CACHED]  = 1, /* io completion */
 576                         [CPS_OWNED]   = 0,
 577                         [CPS_PAGEIN]  = 0,
 578                         [CPS_PAGEOUT] = 0,
 579                         [CPS_FREEING] = 0,
 580                 },
 581                 [CPS_PAGEOUT] = {
 582                         [CPS_CACHED]  = 1, /* io completion */
 583                         [CPS_OWNED]   = 0,
 584                         [CPS_PAGEIN]  = 0,
 585                         [CPS_PAGEOUT] = 0,
 586                         [CPS_FREEING] = 0,
 587                 },
 588                 [CPS_FREEING] = {
 589                         [CPS_CACHED]  = 0,
 590                         [CPS_OWNED]   = 0,
 591                         [CPS_PAGEIN]  = 0,
 592                         [CPS_PAGEOUT] = 0,
 593                         [CPS_FREEING] = 0,
 594                 }
 595         };
 596
 597         ENTRY;
 598         old = page->cp_state;
 599         PASSERT(env, page, allowed_transitions[old][state]);
 600         CL_PAGE_HEADER(D_TRACE, env, page, "%d -> %d\n", old, state);
 601         for (; page != NULL; page = page->cp_child) {
 602                 PASSERT(env, page, page->cp_state == old);
 603                 PASSERT(env, page,
 604                         equi(state == CPS_OWNED, page->cp_owner != NULL));
 605
 606                 CS_PAGESTATE_DEC(page->cp_obj, page->cp_state);
 607                 CS_PAGESTATE_INC(page->cp_obj, state);
 608                 cl_page_state_set_trust(page, state);
 609         }
 610         EXIT;
 611 }
 612
 613 static void cl_page_state_set(const struct lu_env *env,
 614                               struct cl_page *page, enum cl_page_state state)
 615 {
 616         cl_page_state_set0(env, page, state);
 617 }
 618
 619 /**
 620  * Acquires an additional reference to a page.
 621  *
 622  * This can be called only by caller already possessing a reference to \a
 623  * page.
 624  *
 625  * \see cl_object_get(), cl_lock_get().
 626  */
 627 void cl_page_get(struct cl_page *page)
 628 {
 629         ENTRY;
 630         cl_page_get_trust(page);
 631         EXIT;
 632 }
 633 EXPORT_SYMBOL(cl_page_get);
 634
 635 /**
 636  * Releases a reference to a page.
 637  *
 638  * When last reference is released, page is returned to the cache, unless it
 639  * is in cl_page_state::CPS_FREEING state, in which case it is immediately
 640  * destroyed.
 641  *
 642  * \see cl_object_put(), cl_lock_put().
 643  */
 644 void cl_page_put(const struct lu_env *env, struct cl_page *page)
 645 {
 646         PASSERT(env, page, cfs_atomic_read(&page->cp_ref) > !!page->cp_parent);
 647
 648         ENTRY;
 649         CL_PAGE_HEADER(D_TRACE, env, page, "%d\n",
 650                        cfs_atomic_read(&page->cp_ref));
 651
 652         if (cfs_atomic_dec_and_test(&page->cp_ref)) {
 653                 LASSERT(page->cp_state == CPS_FREEING);
 654
 655                 LASSERT(cfs_atomic_read(&page->cp_ref) == 0);
 656                 PASSERT(env, page, page->cp_owner == NULL);
 657                 PASSERT(env, page, cfs_list_empty(&page->cp_batch));
 658                 /*
 659                  * Page is no longer reachable by other threads. Tear
 660                  * it down.
 661                  */
 662                 cl_page_free(env, page);
 663         }
 664
 665         EXIT;
 666 }
 667 EXPORT_SYMBOL(cl_page_put);
 668
 669 /**
 670  * Returns a VM page associated with a given cl_page.
 671  */
 672 cfs_page_t *cl_page_vmpage(const struct lu_env *env, struct cl_page *page)
 673 {
 674         const struct cl_page_slice *slice;
 675
 676         /*
 677          * Find uppermost layer with ->cpo_vmpage() method, and return its
 678          * result.
 679          */
 680         page = cl_page_top(page);
 681         do {
 682                 cfs_list_for_each_entry(slice, &page->cp_layers, cpl_linkage) {
 683                         if (slice->cpl_ops->cpo_vmpage != NULL)
 684                                 RETURN(slice->cpl_ops->cpo_vmpage(env, slice));
 685                 }
 686                 page = page->cp_child;
 687         } while (page != NULL);
 688         LBUG(); /* ->cpo_vmpage() has to be defined somewhere in the stack */
 689 }
 690 EXPORT_SYMBOL(cl_page_vmpage);
 691
 692 /**
 693  * Returns a cl_page associated with a VM page, and given cl_object.
 694  */
 695 struct cl_page *cl_vmpage_page(cfs_page_t *vmpage, struct cl_object *obj)
 696 {
 697         struct cl_page *top;
 698         struct cl_page *page;
 699
 700         ENTRY;
 701         KLASSERT(PageLocked(vmpage));
 702
 703         /*
 704          * NOTE: absence of races and liveness of data are guaranteed by page
 705          *       lock on a "vmpage". That works because object destruction has
 706          *       bottom-to-top pass.
 707          */
 708
 709         /*
 710          * This loop assumes that ->private points to the top-most page. This
 711          * can be rectified easily.
 712          */
 713         top = (struct cl_page *)vmpage->private;
 714         if (top == NULL)
 715                 RETURN(NULL);
 716
 717         for (page = top; page != NULL; page = page->cp_child) {
 718                 if (cl_object_same(page->cp_obj, obj)) {
 719                         cl_page_get_trust(page);
 720                         break;
 721                 }
 722         }
 723         LASSERT(ergo(page, page->cp_type == CPT_CACHEABLE));
 724         RETURN(page);
 725 }
 726 EXPORT_SYMBOL(cl_vmpage_page);
 727
 728 /**
 729  * Returns the top-page for a given page.
 730  *
 731  * \see cl_object_top(), cl_io_top()
 732  */
 733 struct cl_page *cl_page_top(struct cl_page *page)
 734 {
 735         return cl_page_top_trusted(page);
 736 }
 737 EXPORT_SYMBOL(cl_page_top);
 738
 739 const struct cl_page_slice *cl_page_at(const struct cl_page *page,
 740                                        const struct lu_device_type *dtype)
 741 {
 742         return cl_page_at_trusted(page, dtype);
 743 }
 744 EXPORT_SYMBOL(cl_page_at);
 745
 746 #define CL_PAGE_OP(opname) offsetof(struct cl_page_operations, opname)
 747
 748 #define CL_PAGE_INVOKE(_env, _page, _op, _proto, ...)                   \
 749 ({                                                                      \
 750         const struct lu_env        *__env  = (_env);                    \
 751         struct cl_page             *__page = (_page);                   \
 752         const struct cl_page_slice *__scan;                             \
 753         int                         __result;                           \
 754         ptrdiff_t                   __op   = (_op);                     \
 755         int                       (*__method)_proto;                    \
 756                                                                         \
 757         __result = 0;                                                   \
 758         __page = cl_page_top(__page);                                   \
 759         do {                                                            \
 760                 cfs_list_for_each_entry(__scan, &__page->cp_layers,     \
 761                                         cpl_linkage) {                  \
 762                         __method = *(void **)((char *)__scan->cpl_ops + \
 763                                               __op);                    \
 764                         if (__method != NULL) {                         \
 765                                 __result = (*__method)(__env, __scan,   \
 766                                                        ## __VA_ARGS__); \
 767                                 if (__result != 0)                      \
 768                                         break;                          \
 769                         }                                               \
 770                 }                                                       \
 771                 __page = __page->cp_child;                              \
 772         } while (__page != NULL && __result == 0);                      \
 773         if (__result > 0)                                               \
 774                 __result = 0;                                           \
 775         __result;                                                       \
 776 })
 777
 778 #define CL_PAGE_INVOID(_env, _page, _op, _proto, ...)                   \
 779 do {                                                                    \
 780         const struct lu_env        *__env  = (_env);                    \
 781         struct cl_page             *__page = (_page);                   \
 782         const struct cl_page_slice *__scan;                             \
 783         ptrdiff_t                   __op   = (_op);                     \
 784         void                      (*__method)_proto;                    \
 785                                                                         \
 786         __page = cl_page_top(__page);                                   \
 787         do {                                                            \
 788                 cfs_list_for_each_entry(__scan, &__page->cp_layers,     \
 789                                         cpl_linkage) {                  \
 790                         __method = *(void **)((char *)__scan->cpl_ops + \
 791                                               __op);                    \
 792                         if (__method != NULL)                           \
 793                                 (*__method)(__env, __scan,              \
 794                                             ## __VA_ARGS__);            \
 795                 }                                                       \
 796                 __page = __page->cp_child;                              \
 797         } while (__page != NULL);                                       \
 798 } while (0)
 799
 800 #define CL_PAGE_INVOID_REVERSE(_env, _page, _op, _proto, ...)               \
 801 do {                                                                        \
 802         const struct lu_env        *__env  = (_env);                        \
 803         struct cl_page             *__page = (_page);                       \
 804         const struct cl_page_slice *__scan;                                 \
 805         ptrdiff_t                   __op   = (_op);                         \
 806         void                      (*__method)_proto;                        \
 807                                                                             \
 808         /* get to the bottom page. */                                       \
 809         while (__page->cp_child != NULL)                                    \
 810                 __page = __page->cp_child;                                  \
 811         do {                                                                \
 812                 cfs_list_for_each_entry_reverse(__scan, &__page->cp_layers, \
 813                                                 cpl_linkage) {              \
 814                         __method = *(void **)((char *)__scan->cpl_ops +     \
 815                                               __op);                        \
 816                         if (__method != NULL)                               \
 817                                 (*__method)(__env, __scan,                  \
 818                                             ## __VA_ARGS__);                \
 819                 }                                                           \
 820                 __page = __page->cp_parent;                                 \
 821         } while (__page != NULL);                                           \
 822 } while (0)
 823
 824 static int cl_page_invoke(const struct lu_env *env,
 825                           struct cl_io *io, struct cl_page *page, ptrdiff_t op)
 826
 827 {
 828         PINVRNT(env, page, cl_object_same(page->cp_obj, io->ci_obj));
 829         ENTRY;
 830         RETURN(CL_PAGE_INVOKE(env, page, op,
 831                               (const struct lu_env *,
 832                                const struct cl_page_slice *, struct cl_io *),
 833                               io));
 834 }
 835
 836 static void cl_page_invoid(const struct lu_env *env,
 837                            struct cl_io *io, struct cl_page *page, ptrdiff_t op)
 838
 839 {
 840         PINVRNT(env, page, cl_object_same(page->cp_obj, io->ci_obj));
 841         ENTRY;
 842         CL_PAGE_INVOID(env, page, op,
 843                        (const struct lu_env *,
 844                         const struct cl_page_slice *, struct cl_io *), io);
 845         EXIT;
 846 }
 847
 848 static void cl_page_owner_clear(struct cl_page *page)
 849 {
 850         ENTRY;
 851         for (page = cl_page_top(page); page != NULL; page = page->cp_child) {
 852                 if (page->cp_owner != NULL) {
 853                         LASSERT(page->cp_owner->ci_owned_nr > 0);
 854                         page->cp_owner->ci_owned_nr--;
 855                         page->cp_owner = NULL;
 856                         page->cp_task = NULL;
 857                 }
 858         }
 859         EXIT;
 860 }
 861
 862 static void cl_page_owner_set(struct cl_page *page)
 863 {
 864         ENTRY;
 865         for (page = cl_page_top(page); page != NULL; page = page->cp_child) {
 866                 LASSERT(page->cp_owner != NULL);
 867                 page->cp_owner->ci_owned_nr++;
 868         }
 869         EXIT;
 870 }
 871
 872 void cl_page_disown0(const struct lu_env *env,
 873                      struct cl_io *io, struct cl_page *pg)
 874 {
 875         enum cl_page_state state;
 876
 877         ENTRY;
 878         state = pg->cp_state;
 879         PINVRNT(env, pg, state == CPS_OWNED || state == CPS_FREEING);
 880         PINVRNT(env, pg, cl_page_invariant(pg));
 881         cl_page_owner_clear(pg);
 882
 883         if (state == CPS_OWNED)
 884                 cl_page_state_set(env, pg, CPS_CACHED);
 885         /*
 886          * Completion call-backs are executed in the bottom-up order, so that
 887          * uppermost layer (llite), responsible for VFS/VM interaction runs
 888          * last and can release locks safely.
 889          */
 890         CL_PAGE_INVOID_REVERSE(env, pg, CL_PAGE_OP(cpo_disown),
 891                                (const struct lu_env *,
 892                                 const struct cl_page_slice *, struct cl_io *),
 893                                io);
 894         EXIT;
 895 }
 896
 897 /**
 898  * returns true, iff page is owned by the given io.
 899  */
 900 int cl_page_is_owned(const struct cl_page *pg, const struct cl_io *io)
 901 {
 902         LINVRNT(cl_object_same(pg->cp_obj, io->ci_obj));
 903         ENTRY;
 904         RETURN(pg->cp_state == CPS_OWNED && pg->cp_owner == io);
 905 }
 906 EXPORT_SYMBOL(cl_page_is_owned);
 907
 908 /**
 909  * Try to own a page by IO.
 910  *
 911  * Waits until page is in cl_page_state::CPS_CACHED state, and then switch it
 912  * into cl_page_state::CPS_OWNED state.
 913  *
 914  * \pre  !cl_page_is_owned(pg, io)
 915  * \post result == 0 iff cl_page_is_owned(pg, io)
 916  *
 917  * \retval 0   success
 918  *
 919  * \retval -ve failure, e.g., page was destroyed (and landed in
 920  *             cl_page_state::CPS_FREEING instead of cl_page_state::CPS_CACHED).
 921  *             or, page was owned by another thread, or in IO.
 922  *
 923  * \see cl_page_disown()
 924  * \see cl_page_operations::cpo_own()
 925  * \see cl_page_own_try()
 926  * \see cl_page_own
 927  */
 928 static int cl_page_own0(const struct lu_env *env, struct cl_io *io,
 929                         struct cl_page *pg, int nonblock)
 930 {
 931         int result;
 932
 933         PINVRNT(env, pg, !cl_page_is_owned(pg, io));
 934
 935         ENTRY;
 936         pg = cl_page_top(pg);
 937         io = cl_io_top(io);
 938
 939         if (pg->cp_state == CPS_FREEING) {
 940                 result = -ENOENT;
 941         } else {
 942                 result = CL_PAGE_INVOKE(env, pg, CL_PAGE_OP(cpo_own),
 943                                         (const struct lu_env *,
 944                                          const struct cl_page_slice *,
 945                                          struct cl_io *, int),
 946                                         io, nonblock);
 947                 if (result == 0) {
 948                         PASSERT(env, pg, pg->cp_owner == NULL);
 949                         PASSERT(env, pg, pg->cp_req == NULL);
 950                         pg->cp_owner = io;
 951                         pg->cp_task  = current;
 952                         cl_page_owner_set(pg);
 953                         if (pg->cp_state != CPS_FREEING) {
 954                                 cl_page_state_set(env, pg, CPS_OWNED);
 955                         } else {
 956                                 cl_page_disown0(env, io, pg);
 957                                 result = -ENOENT;
 958                         }
 959                 }
 960         }
 961         PINVRNT(env, pg, ergo(result == 0, cl_page_invariant(pg)));
 962         RETURN(result);
 963 }
 964
 965 /**
 966  * Own a page, might be blocked.
 967  *
 968  * \see cl_page_own0()
 969  */
 970 int cl_page_own(const struct lu_env *env, struct cl_io *io, struct cl_page *pg)
 971 {
 972         return cl_page_own0(env, io, pg, 0);
 973 }
 974 EXPORT_SYMBOL(cl_page_own);
 975
 976 /**
 977  * Nonblock version of cl_page_own().
 978  *
 979  * \see cl_page_own0()
 980  */
 981 int cl_page_own_try(const struct lu_env *env, struct cl_io *io,
 982                     struct cl_page *pg)
 983 {
 984         return cl_page_own0(env, io, pg, 1);
 985 }
 986 EXPORT_SYMBOL(cl_page_own_try);
 987
 988
 989 /**
 990  * Assume page ownership.
 991  *
 992  * Called when page is already locked by the hosting VM.
 993  *
 994  * \pre !cl_page_is_owned(pg, io)
 995  * \post cl_page_is_owned(pg, io)
 996  *
 997  * \see cl_page_operations::cpo_assume()
 998  */
 999 void cl_page_assume(const struct lu_env *env,
1000                     struct cl_io *io, struct cl_page *pg)
1001 {
1002         PINVRNT(env, pg, cl_object_same(pg->cp_obj, io->ci_obj));
1003
1004         ENTRY;
1005         pg = cl_page_top(pg);
1006         io = cl_io_top(io);
1007
1008         cl_page_invoid(env, io, pg, CL_PAGE_OP(cpo_assume));
1009         PASSERT(env, pg, pg->cp_owner == NULL);
1010         pg->cp_owner = io;
1011         pg->cp_task = current;
1012         cl_page_owner_set(pg);
1013         cl_page_state_set(env, pg, CPS_OWNED);
1014         EXIT;
1015 }
1016 EXPORT_SYMBOL(cl_page_assume);
1017
1018 /**
1019  * Releases page ownership without unlocking the page.
1020  *
1021  * Moves page into cl_page_state::CPS_CACHED without releasing a lock on the
1022  * underlying VM page (as VM is supposed to do this itself).
1023  *
1024  * \pre   cl_page_is_owned(pg, io)
1025  * \post !cl_page_is_owned(pg, io)
1026  *
1027  * \see cl_page_assume()
1028  */
1029 void cl_page_unassume(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         ENTRY;
1036         pg = cl_page_top(pg);
1037         io = cl_io_top(io);
1038         cl_page_owner_clear(pg);
1039         cl_page_state_set(env, pg, CPS_CACHED);
1040         CL_PAGE_INVOID_REVERSE(env, pg, CL_PAGE_OP(cpo_unassume),
1041                                (const struct lu_env *,
1042                                 const struct cl_page_slice *, struct cl_io *),
1043                                io);
1044         EXIT;
1045 }
1046 EXPORT_SYMBOL(cl_page_unassume);
1047
1048 /**
1049  * Releases page ownership.
1050  *
1051  * Moves page into cl_page_state::CPS_CACHED.
1052  *
1053  * \pre   cl_page_is_owned(pg, io)
1054  * \post !cl_page_is_owned(pg, io)
1055  *
1056  * \see cl_page_own()
1057  * \see cl_page_operations::cpo_disown()
1058  */
1059 void cl_page_disown(const struct lu_env *env,
1060                     struct cl_io *io, struct cl_page *pg)
1061 {
1062         PINVRNT(env, pg, cl_page_is_owned(pg, io));
1063
1064         ENTRY;
1065         pg = cl_page_top(pg);
1066         io = cl_io_top(io);
1067         cl_page_disown0(env, io, pg);
1068         EXIT;
1069 }
1070 EXPORT_SYMBOL(cl_page_disown);
1071
1072 /**
1073  * Called when page is to be removed from the object, e.g., as a result of
1074  * truncate.
1075  *
1076  * Calls cl_page_operations::cpo_discard() top-to-bottom.
1077  *
1078  * \pre cl_page_is_owned(pg, io)
1079  *
1080  * \see cl_page_operations::cpo_discard()
1081  */
1082 void cl_page_discard(const struct lu_env *env,
1083                      struct cl_io *io, struct cl_page *pg)
1084 {
1085         PINVRNT(env, pg, cl_page_is_owned(pg, io));
1086         PINVRNT(env, pg, cl_page_invariant(pg));
1087
1088         cl_page_invoid(env, io, pg, CL_PAGE_OP(cpo_discard));
1089 }
1090 EXPORT_SYMBOL(cl_page_discard);
1091
1092 /**
1093  * Version of cl_page_delete() that can be called for not fully constructed
1094  * pages, e.g,. in a error handling cl_page_find()->cl_page_delete0()
1095  * path. Doesn't check page invariant.
1096  */
1097 static void cl_page_delete0(const struct lu_env *env, struct cl_page *pg,
1098                             int radix)
1099 {
1100         struct cl_page *tmp = pg;
1101         ENTRY;
1102
1103         PASSERT(env, pg, pg == cl_page_top(pg));
1104         PASSERT(env, pg, pg->cp_state != CPS_FREEING);
1105
1106         /*
1107          * Severe all ways to obtain new pointers to @pg.
1108          */
1109         cl_page_owner_clear(pg);
1110
1111         /*
1112          * unexport the page firstly before freeing it so that
1113          * the page content is considered to be invalid.
1114          * We have to do this because a CPS_FREEING cl_page may
1115          * be NOT under the protection of a cl_lock.
1116          * Afterwards, if this page is found by other threads, then this
1117          * page will be forced to reread.
1118          */
1119         cl_page_export(env, pg, 0);
1120         cl_page_state_set0(env, pg, CPS_FREEING);
1121
1122         CL_PAGE_INVOID(env, pg, CL_PAGE_OP(cpo_delete),
1123                        (const struct lu_env *, const struct cl_page_slice *));
1124
1125         if (tmp->cp_type == CPT_CACHEABLE) {
1126                 if (!radix)
1127                         /* !radix means that @pg is not yet in the radix tree,
1128                          * skip removing it.
1129                          */
1130                         tmp = pg->cp_child;
1131                 for (; tmp != NULL; tmp = tmp->cp_child) {
1132                         void                    *value;
1133                         struct cl_object_header *hdr;
1134
1135                         hdr = cl_object_header(tmp->cp_obj);
1136                         spin_lock(&hdr->coh_page_guard);
1137                         value = radix_tree_delete(&hdr->coh_tree,
1138                                                   tmp->cp_index);
1139                         PASSERT(env, tmp, value == tmp);
1140                         PASSERT(env, tmp, hdr->coh_pages > 0);
1141                         hdr->coh_pages--;
1142                         spin_unlock(&hdr->coh_page_guard);
1143                         cl_page_put(env, tmp);
1144                 }
1145         }
1146
1147         EXIT;
1148 }
1149
1150 /**
1151  * Called when a decision is made to throw page out of memory.
1152  *
1153  * Notifies all layers about page destruction by calling
1154  * cl_page_operations::cpo_delete() method top-to-bottom.
1155  *
1156  * Moves page into cl_page_state::CPS_FREEING state (this is the only place
1157  * where transition to this state happens).
1158  *
1159  * Eliminates all venues through which new references to the page can be
1160  * obtained:
1161  *
1162  *     - removes page from the radix trees,
1163  *
1164  *     - breaks linkage from VM page to cl_page.
1165  *
1166  * Once page reaches cl_page_state::CPS_FREEING, all remaining references will
1167  * drain after some time, at which point page will be recycled.
1168  *
1169  * \pre  pg == cl_page_top(pg)
1170  * \pre  VM page is locked
1171  * \post pg->cp_state == CPS_FREEING
1172  *
1173  * \see cl_page_operations::cpo_delete()
1174  */
1175 void cl_page_delete(const struct lu_env *env, struct cl_page *pg)
1176 {
1177         PINVRNT(env, pg, cl_page_invariant(pg));
1178         ENTRY;
1179         cl_page_delete0(env, pg, 1);
1180         EXIT;
1181 }
1182 EXPORT_SYMBOL(cl_page_delete);
1183
1184 /**
1185  * Unmaps page from user virtual memory.
1186  *
1187  * Calls cl_page_operations::cpo_unmap() through all layers top-to-bottom. The
1188  * layer responsible for VM interaction has to unmap page from user space
1189  * virtual memory.
1190  *
1191  * \see cl_page_operations::cpo_unmap()
1192  */
1193 int cl_page_unmap(const struct lu_env *env,
1194                   struct cl_io *io, struct cl_page *pg)
1195 {
1196         PINVRNT(env, pg, cl_page_is_owned(pg, io));
1197         PINVRNT(env, pg, cl_page_invariant(pg));
1198
1199         return cl_page_invoke(env, io, pg, CL_PAGE_OP(cpo_unmap));
1200 }
1201 EXPORT_SYMBOL(cl_page_unmap);
1202
1203 /**
1204  * Marks page up-to-date.
1205  *
1206  * Call cl_page_operations::cpo_export() through all layers top-to-bottom. The
1207  * layer responsible for VM interaction has to mark/clear page as up-to-date
1208  * by the \a uptodate argument.
1209  *
1210  * \see cl_page_operations::cpo_export()
1211  */
1212 void cl_page_export(const struct lu_env *env, struct cl_page *pg, int uptodate)
1213 {
1214         PINVRNT(env, pg, cl_page_invariant(pg));
1215         CL_PAGE_INVOID(env, pg, CL_PAGE_OP(cpo_export),
1216                        (const struct lu_env *,
1217                         const struct cl_page_slice *, int), uptodate);
1218 }
1219 EXPORT_SYMBOL(cl_page_export);
1220
1221 /**
1222  * Returns true, iff \a pg is VM locked in a suitable sense by the calling
1223  * thread.
1224  */
1225 int cl_page_is_vmlocked(const struct lu_env *env, const struct cl_page *pg)
1226 {
1227         int result;
1228         const struct cl_page_slice *slice;
1229
1230         ENTRY;
1231         pg = cl_page_top_trusted((struct cl_page *)pg);
1232         slice = container_of(pg->cp_layers.next,
1233                              const struct cl_page_slice, cpl_linkage);
1234         PASSERT(env, pg, slice->cpl_ops->cpo_is_vmlocked != NULL);
1235         /*
1236          * Call ->cpo_is_vmlocked() directly instead of going through
1237          * CL_PAGE_INVOKE(), because cl_page_is_vmlocked() is used by
1238          * cl_page_invariant().
1239          */
1240         result = slice->cpl_ops->cpo_is_vmlocked(env, slice);
1241         PASSERT(env, pg, result == -EBUSY || result == -ENODATA);
1242         RETURN(result == -EBUSY);
1243 }
1244 EXPORT_SYMBOL(cl_page_is_vmlocked);
1245
1246 static enum cl_page_state cl_req_type_state(enum cl_req_type crt)
1247 {
1248         ENTRY;
1249         RETURN(crt == CRT_WRITE ? CPS_PAGEOUT : CPS_PAGEIN);
1250 }
1251
1252 static void cl_page_io_start(const struct lu_env *env,
1253                              struct cl_page *pg, enum cl_req_type crt)
1254 {
1255         /*
1256          * Page is queued for IO, change its state.
1257          */
1258         ENTRY;
1259         cl_page_owner_clear(pg);
1260         cl_page_state_set(env, pg, cl_req_type_state(crt));
1261         EXIT;
1262 }
1263
1264 /**
1265  * Prepares page for immediate transfer. cl_page_operations::cpo_prep() is
1266  * called top-to-bottom. Every layer either agrees to submit this page (by
1267  * returning 0), or requests to omit this page (by returning -EALREADY). Layer
1268  * handling interactions with the VM also has to inform VM that page is under
1269  * transfer now.
1270  */
1271 int cl_page_prep(const struct lu_env *env, struct cl_io *io,
1272                  struct cl_page *pg, enum cl_req_type crt)
1273 {
1274         int result;
1275
1276         PINVRNT(env, pg, cl_page_is_owned(pg, io));
1277         PINVRNT(env, pg, cl_page_invariant(pg));
1278         PINVRNT(env, pg, crt < CRT_NR);
1279
1280         /*
1281          * XXX this has to be called bottom-to-top, so that llite can set up
1282          * PG_writeback without risking other layers deciding to skip this
1283          * page.
1284          */
1285         result = cl_page_invoke(env, io, pg, CL_PAGE_OP(io[crt].cpo_prep));
1286         if (result == 0)
1287                 cl_page_io_start(env, pg, crt);
1288
1289         KLASSERT(ergo(crt == CRT_WRITE && pg->cp_type == CPT_CACHEABLE,
1290                       equi(result == 0,
1291                            PageWriteback(cl_page_vmpage(env, pg)))));
1292         CL_PAGE_HEADER(D_TRACE, env, pg, "%d %d\n", crt, result);
1293         return result;
1294 }
1295 EXPORT_SYMBOL(cl_page_prep);
1296
1297 /**
1298  * Notify layers about transfer completion.
1299  *
1300  * Invoked by transfer sub-system (which is a part of osc) to notify layers
1301  * that a transfer, of which this page is a part of has completed.
1302  *
1303  * Completion call-backs are executed in the bottom-up order, so that
1304  * uppermost layer (llite), responsible for the VFS/VM interaction runs last
1305  * and can release locks safely.
1306  *
1307  * \pre  pg->cp_state == CPS_PAGEIN || pg->cp_state == CPS_PAGEOUT
1308  * \post pg->cp_state == CPS_CACHED
1309  *
1310  * \see cl_page_operations::cpo_completion()
1311  */
1312 void cl_page_completion(const struct lu_env *env,
1313                         struct cl_page *pg, enum cl_req_type crt, int ioret)
1314 {
1315         struct cl_sync_io *anchor = pg->cp_sync_io;
1316
1317         PASSERT(env, pg, crt < CRT_NR);
1318         /* cl_page::cp_req already cleared by the caller (osc_completion()) */
1319         PASSERT(env, pg, pg->cp_req == NULL);
1320         PASSERT(env, pg, pg->cp_state == cl_req_type_state(crt));
1321
1322         ENTRY;
1323         CL_PAGE_HEADER(D_TRACE, env, pg, "%d %d\n", crt, ioret);
1324         if (crt == CRT_READ && ioret == 0) {
1325                 PASSERT(env, pg, !(pg->cp_flags & CPF_READ_COMPLETED));
1326                 pg->cp_flags |= CPF_READ_COMPLETED;
1327         }
1328
1329         cl_page_state_set(env, pg, CPS_CACHED);
1330         CL_PAGE_INVOID_REVERSE(env, pg, CL_PAGE_OP(io[crt].cpo_completion),
1331                                (const struct lu_env *,
1332                                 const struct cl_page_slice *, int), ioret);
1333         if (anchor) {
1334                 LASSERT(cl_page_is_vmlocked(env, pg));
1335                 LASSERT(pg->cp_sync_io == anchor);
1336                 pg->cp_sync_io = NULL;
1337                 cl_sync_io_note(anchor, ioret);
1338         }
1339         EXIT;
1340 }
1341 EXPORT_SYMBOL(cl_page_completion);
1342
1343 /**
1344  * Notify layers that transfer formation engine decided to yank this page from
1345  * the cache and to make it a part of a transfer.
1346  *
1347  * \pre  pg->cp_state == CPS_CACHED
1348  * \post pg->cp_state == CPS_PAGEIN || pg->cp_state == CPS_PAGEOUT
1349  *
1350  * \see cl_page_operations::cpo_make_ready()
1351  */
1352 int cl_page_make_ready(const struct lu_env *env, struct cl_page *pg,
1353                        enum cl_req_type crt)
1354 {
1355         int result;
1356
1357         PINVRNT(env, pg, crt < CRT_NR);
1358
1359         ENTRY;
1360         result = CL_PAGE_INVOKE(env, pg, CL_PAGE_OP(io[crt].cpo_make_ready),
1361                                 (const struct lu_env *,
1362                                  const struct cl_page_slice *));
1363         if (result == 0) {
1364                 PASSERT(env, pg, pg->cp_state == CPS_CACHED);
1365                 cl_page_io_start(env, pg, crt);
1366         }
1367         CL_PAGE_HEADER(D_TRACE, env, pg, "%d %d\n", crt, result);
1368         RETURN(result);
1369 }
1370 EXPORT_SYMBOL(cl_page_make_ready);
1371
1372 /**
1373  * Notify layers that high level io decided to place this page into a cache
1374  * for future transfer.
1375  *
1376  * The layer implementing transfer engine (osc) has to register this page in
1377  * its queues.
1378  *
1379  * \pre  cl_page_is_owned(pg, io)
1380  * \post cl_page_is_owned(pg, io)
1381  *
1382  * \see cl_page_operations::cpo_cache_add()
1383  */
1384 int cl_page_cache_add(const struct lu_env *env, struct cl_io *io,
1385                       struct cl_page *pg, enum cl_req_type crt)
1386 {
1387         const struct cl_page_slice *scan;
1388         int result = 0;
1389
1390         PINVRNT(env, pg, crt < CRT_NR);
1391         PINVRNT(env, pg, cl_page_is_owned(pg, io));
1392         PINVRNT(env, pg, cl_page_invariant(pg));
1393
1394         ENTRY;
1395
1396         cfs_list_for_each_entry(scan, &pg->cp_layers, cpl_linkage) {
1397                 if (scan->cpl_ops->io[crt].cpo_cache_add == NULL)
1398                         continue;
1399
1400                 result = scan->cpl_ops->io[crt].cpo_cache_add(env, scan, io);
1401                 if (result != 0)
1402                         break;
1403         }
1404         CL_PAGE_HEADER(D_TRACE, env, pg, "%d %d\n", crt, result);
1405         RETURN(result);
1406 }
1407 EXPORT_SYMBOL(cl_page_cache_add);
1408
1409 /**
1410  * Called if a pge is being written back by kernel's intention.
1411  *
1412  * \pre  cl_page_is_owned(pg, io)
1413  * \post ergo(result == 0, pg->cp_state == CPS_PAGEOUT)
1414  *
1415  * \see cl_page_operations::cpo_flush()
1416  */
1417 int cl_page_flush(const struct lu_env *env, struct cl_io *io,
1418                   struct cl_page *pg)
1419 {
1420         int result;
1421
1422         PINVRNT(env, pg, cl_page_is_owned(pg, io));
1423         PINVRNT(env, pg, cl_page_invariant(pg));
1424
1425         ENTRY;
1426
1427         result = cl_page_invoke(env, io, pg, CL_PAGE_OP(cpo_flush));
1428
1429         CL_PAGE_HEADER(D_TRACE, env, pg, "%d\n", result);
1430         RETURN(result);
1431 }
1432 EXPORT_SYMBOL(cl_page_flush);
1433
1434 /**
1435  * Checks whether page is protected by any extent lock is at least required
1436  * mode.
1437  *
1438  * \return the same as in cl_page_operations::cpo_is_under_lock() method.
1439  * \see cl_page_operations::cpo_is_under_lock()
1440  */
1441 int cl_page_is_under_lock(const struct lu_env *env, struct cl_io *io,
1442                           struct cl_page *page)
1443 {
1444         int rc;
1445
1446         PINVRNT(env, page, cl_page_invariant(page));
1447
1448         ENTRY;
1449         rc = CL_PAGE_INVOKE(env, page, CL_PAGE_OP(cpo_is_under_lock),
1450                             (const struct lu_env *,
1451                              const struct cl_page_slice *, struct cl_io *),
1452                             io);
1453         PASSERT(env, page, rc != 0);
1454         RETURN(rc);
1455 }
1456 EXPORT_SYMBOL(cl_page_is_under_lock);
1457
1458 static int page_prune_cb(const struct lu_env *env, struct cl_io *io,
1459                          struct cl_page *page, void *cbdata)
1460 {
1461         cl_page_own(env, io, page);
1462         cl_page_unmap(env, io, page);
1463         cl_page_discard(env, io, page);
1464         cl_page_disown(env, io, page);
1465         return CLP_GANG_OKAY;
1466 }
1467
1468 /**
1469  * Purges all cached pages belonging to the object \a obj.
1470  */
1471 int cl_pages_prune(const struct lu_env *env, struct cl_object *clobj)
1472 {
1473         struct cl_thread_info   *info;
1474         struct cl_object        *obj = cl_object_top(clobj);
1475         struct cl_io            *io;
1476         int                      result;
1477
1478         ENTRY;
1479         info  = cl_env_info(env);
1480         io    = &info->clt_io;
1481
1482         /*
1483          * initialize the io. This is ugly since we never do IO in this
1484          * function, we just make cl_page_list functions happy. -jay
1485          */
1486         io->ci_obj = obj;
1487         io->ci_ignore_layout = 1;
1488         result = cl_io_init(env, io, CIT_MISC, obj);
1489         if (result != 0) {
1490                 cl_io_fini(env, io);
1491                 RETURN(io->ci_result);
1492         }
1493
1494         do {
1495                 result = cl_page_gang_lookup(env, obj, io, 0, CL_PAGE_EOF,
1496                                              page_prune_cb, NULL);
1497                 if (result == CLP_GANG_RESCHED)
1498                         cfs_cond_resched();
1499         } while (result != CLP_GANG_OKAY);
1500
1501         cl_io_fini(env, io);
1502         RETURN(result);
1503 }
1504 EXPORT_SYMBOL(cl_pages_prune);
1505
1506 /**
1507  * Tells transfer engine that only part of a page is to be transmitted.
1508  *
1509  * \see cl_page_operations::cpo_clip()
1510  */
1511 void cl_page_clip(const struct lu_env *env, struct cl_page *pg,
1512                   int from, int to)
1513 {
1514         PINVRNT(env, pg, cl_page_invariant(pg));
1515
1516         CL_PAGE_HEADER(D_TRACE, env, pg, "%d %d\n", from, to);
1517         CL_PAGE_INVOID(env, pg, CL_PAGE_OP(cpo_clip),
1518                        (const struct lu_env *,
1519                         const struct cl_page_slice *,int, int),
1520                        from, to);
1521 }
1522 EXPORT_SYMBOL(cl_page_clip);
1523
1524 /**
1525  * Prints human readable representation of \a pg to the \a f.
1526  */
1527 void cl_page_header_print(const struct lu_env *env, void *cookie,
1528                           lu_printer_t printer, const struct cl_page *pg)
1529 {
1530         (*printer)(env, cookie,
1531                    "page@%p[%d %p:%lu ^%p_%p %d %d %d %p %p %#x]\n",
1532                    pg, cfs_atomic_read(&pg->cp_ref), pg->cp_obj,
1533                    pg->cp_index, pg->cp_parent, pg->cp_child,
1534                    pg->cp_state, pg->cp_error, pg->cp_type,
1535                    pg->cp_owner, pg->cp_req, pg->cp_flags);
1536 }
1537 EXPORT_SYMBOL(cl_page_header_print);
1538
1539 /**
1540  * Prints human readable representation of \a pg to the \a f.
1541  */
1542 void cl_page_print(const struct lu_env *env, void *cookie,
1543                    lu_printer_t printer, const struct cl_page *pg)
1544 {
1545         struct cl_page *scan;
1546
1547         for (scan = cl_page_top((struct cl_page *)pg);
1548              scan != NULL; scan = scan->cp_child)
1549                 cl_page_header_print(env, cookie, printer, scan);
1550         CL_PAGE_INVOKE(env, (struct cl_page *)pg, CL_PAGE_OP(cpo_print),
1551                        (const struct lu_env *env,
1552                         const struct cl_page_slice *slice,
1553                         void *cookie, lu_printer_t p), cookie, printer);
1554         (*printer)(env, cookie, "end page@%p\n", pg);
1555 }
1556 EXPORT_SYMBOL(cl_page_print);
1557
1558 /**
1559  * Cancel a page which is still in a transfer.
1560  */
1561 int cl_page_cancel(const struct lu_env *env, struct cl_page *page)
1562 {
1563         return CL_PAGE_INVOKE(env, page, CL_PAGE_OP(cpo_cancel),
1564                               (const struct lu_env *,
1565                                const struct cl_page_slice *));
1566 }
1567 EXPORT_SYMBOL(cl_page_cancel);
1568
1569 /**
1570  * Converts a byte offset within object \a obj into a page index.
1571  */
1572 loff_t cl_offset(const struct cl_object *obj, pgoff_t idx)
1573 {
1574         /*
1575          * XXX for now.
1576          */
1577         return (loff_t)idx << CFS_PAGE_SHIFT;
1578 }
1579 EXPORT_SYMBOL(cl_offset);
1580
1581 /**
1582  * Converts a page index into a byte offset within object \a obj.
1583  */
1584 pgoff_t cl_index(const struct cl_object *obj, loff_t offset)
1585 {
1586         /*
1587          * XXX for now.
1588          */
1589         return offset >> CFS_PAGE_SHIFT;
1590 }
1591 EXPORT_SYMBOL(cl_index);
1592
1593 int cl_page_size(const struct cl_object *obj)
1594 {
1595         return 1 << CFS_PAGE_SHIFT;
1596 }
1597 EXPORT_SYMBOL(cl_page_size);
1598
1599 /**
1600  * Adds page slice to the compound page.
1601  *
1602  * This is called by cl_object_operations::coo_page_init() methods to add a
1603  * per-layer state to the page. New state is added at the end of
1604  * cl_page::cp_layers list, that is, it is at the bottom of the stack.
1605  *
1606  * \see cl_lock_slice_add(), cl_req_slice_add(), cl_io_slice_add()
1607  */
1608 void cl_page_slice_add(struct cl_page *page, struct cl_page_slice *slice,
1609                        struct cl_object *obj,
1610                        const struct cl_page_operations *ops)
1611 {
1612         ENTRY;
1613         cfs_list_add_tail(&slice->cpl_linkage, &page->cp_layers);
1614         slice->cpl_obj  = obj;
1615         slice->cpl_ops  = ops;
1616         slice->cpl_page = page;
1617         EXIT;
1618 }
1619 EXPORT_SYMBOL(cl_page_slice_add);
1620
1621 int  cl_page_init(void)
1622 {
1623         return lu_kmem_init(cl_page_caches);
1624 }
1625
1626 void cl_page_fini(void)
1627 {
1628         lu_kmem_fini(cl_page_caches);
1629 }