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, Intel Corporation.
  31  */
  32 /*
  33  * This file is part of Lustre, http://www.lustre.org/
  34  * Lustre is a trademark of Sun Microsystems, Inc.
  35  *
  36  * Client Lustre Page.
  37  *
  38  *   Author: Nikita Danilov <nikita.danilov@sun.com>
  39  */
  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 #ifdef LIBCFS_DEBUG
  55 # define PASSERT(env, page, expr)                                       \
  56   do {                                                                    \
  57           if (unlikely(!(expr))) {                                      \
  58                   CL_PAGE_DEBUG(D_ERROR, (env), (page), #expr "\n");    \
  59                   LASSERT(0);                                           \
  60           }                                                             \
  61   } while (0)
  62 #else /* !LIBCFS_DEBUG */
  63 # define PASSERT(env, page, exp) \
  64         ((void)sizeof(env), (void)sizeof(page), (void)sizeof !!(exp))
  65 #endif /* !LIBCFS_DEBUG */
  66
  67 #ifdef INVARIANT_CHECK
  68 # define PINVRNT(env, page, expr)                                       \
  69   do {                                                                    \
  70           if (unlikely(!(expr))) {                                      \
  71                   CL_PAGE_DEBUG(D_ERROR, (env), (page), #expr "\n");    \
  72                   LINVRNT(0);                                           \
  73           }                                                             \
  74   } while (0)
  75 #else /* !INVARIANT_CHECK */
  76 # define PINVRNT(env, page, exp) \
  77         ((void)sizeof(env), (void)sizeof(page), (void)sizeof !!(exp))
  78 #endif /* !INVARIANT_CHECK */
  79
  80 /* Disable page statistic by default due to huge performance penalty. */
  81 #ifdef CONFIG_DEBUG_PAGESTATE_TRACKING
  82 #define CS_PAGE_INC(o, item) \
  83         cfs_atomic_inc(&cl_object_site(o)->cs_pages.cs_stats[CS_##item])
  84 #define CS_PAGE_DEC(o, item) \
  85         cfs_atomic_dec(&cl_object_site(o)->cs_pages.cs_stats[CS_##item])
  86 #define CS_PAGESTATE_INC(o, state) \
  87         cfs_atomic_inc(&cl_object_site(o)->cs_pages_state[state])
  88 #define CS_PAGESTATE_DEC(o, state) \
  89         cfs_atomic_dec(&cl_object_site(o)->cs_pages_state[state])
  90 #else
  91 #define CS_PAGE_INC(o, item)
  92 #define CS_PAGE_DEC(o, item)
  93 #define CS_PAGESTATE_INC(o, state)
  94 #define CS_PAGESTATE_DEC(o, state)
  95 #endif
  96
  97 /**
  98  * Internal version of cl_page_top, it should be called if the page is
  99  * known to be not freed, says with page referenced, or radix tree lock held,
 100  * or page owned.
 101  */
 102 static struct cl_page *cl_page_top_trusted(struct cl_page *page)
 103 {
 104         while (page->cp_parent != NULL)
 105                 page = page->cp_parent;
 106         return page;
 107 }
 108
 109 /**
 110  * Internal version of cl_page_get().
 111  *
 112  * This function can be used to obtain initial reference to previously
 113  * unreferenced cached object. It can be called only if concurrent page
 114  * reclamation is somehow prevented, e.g., by locking page radix-tree
 115  * (cl_object_header::hdr->coh_page_guard), or by keeping a lock on a VM page,
 116  * associated with \a page.
 117  *
 118  * Use with care! Not exported.
 119  */
 120 static void cl_page_get_trust(struct cl_page *page)
 121 {
 122         LASSERT(cfs_atomic_read(&page->cp_ref) > 0);
 123         cfs_atomic_inc(&page->cp_ref);
 124 }
 125
 126 /**
 127  * Returns a slice within a page, corresponding to the given layer in the
 128  * device stack.
 129  *
 130  * \see cl_lock_at()
 131  */
 132 static const struct cl_page_slice *
 133 cl_page_at_trusted(const struct cl_page *page,
 134                    const struct lu_device_type *dtype)
 135 {
 136         const struct cl_page_slice *slice;
 137         ENTRY;
 138
 139         page = cl_page_top_trusted((struct cl_page *)page);
 140         do {
 141                 cfs_list_for_each_entry(slice, &page->cp_layers, cpl_linkage) {
 142                         if (slice->cpl_obj->co_lu.lo_dev->ld_type == dtype)
 143                                 RETURN(slice);
 144                 }
 145                 page = page->cp_child;
 146         } while (page != NULL);
 147         RETURN(NULL);
 148 }
 149
 150 /**
 151  * Returns a page with given index in the given object, or NULL if no page is
 152  * found. Acquires a reference on \a page.
 153  *
 154  * Locking: called under cl_object_header::coh_page_guard spin-lock.
 155  */
 156 struct cl_page *cl_page_lookup(struct cl_object_header *hdr, pgoff_t index)
 157 {
 158         struct cl_page *page;
 159
 160         LASSERT_SPIN_LOCKED(&hdr->coh_page_guard);
 161
 162         page = radix_tree_lookup(&hdr->coh_tree, index);
 163         if (page != NULL)
 164                 cl_page_get_trust(page);
 165         return page;
 166 }
 167 EXPORT_SYMBOL(cl_page_lookup);
 168
 169 /**
 170  * Returns a list of pages by a given [start, end] of \a obj.
 171  *
 172  * \param resched If not NULL, then we give up before hogging CPU for too
 173  * long and set *resched = 1, in that case caller should implement a retry
 174  * logic.
 175  *
 176  * Gang tree lookup (radix_tree_gang_lookup()) optimization is absolutely
 177  * crucial in the face of [offset, EOF] locks.
 178  *
 179  * Return at least one page in @queue unless there is no covered page.
 180  */
 181 int cl_page_gang_lookup(const struct lu_env *env, struct cl_object *obj,
 182                         struct cl_io *io, pgoff_t start, pgoff_t end,
 183                         cl_page_gang_cb_t cb, void *cbdata)
 184 {
 185         struct cl_object_header *hdr;
 186         struct cl_page          *page;
 187         struct cl_page         **pvec;
 188         const struct cl_page_slice  *slice;
 189         const struct lu_device_type *dtype;
 190         pgoff_t                  idx;
 191         unsigned int             nr;
 192         unsigned int             i;
 193         unsigned int             j;
 194         int                      res = CLP_GANG_OKAY;
 195         int                      tree_lock = 1;
 196         ENTRY;
 197
 198         idx = start;
 199         hdr = cl_object_header(obj);
 200         pvec = cl_env_info(env)->clt_pvec;
 201         dtype = cl_object_top(obj)->co_lu.lo_dev->ld_type;
 202         spin_lock(&hdr->coh_page_guard);
 203         while ((nr = radix_tree_gang_lookup(&hdr->coh_tree, (void **)pvec,
 204                                             idx, CLT_PVEC_SIZE)) > 0) {
 205                 int end_of_region = 0;
 206                 idx = pvec[nr - 1]->cp_index + 1;
 207                 for (i = 0, j = 0; i < nr; ++i) {
 208                         page = pvec[i];
 209                         pvec[i] = NULL;
 210
 211                         LASSERT(page->cp_type == CPT_CACHEABLE);
 212                         if (page->cp_index > end) {
 213                                 end_of_region = 1;
 214                                 break;
 215                         }
 216                         if (page->cp_state == CPS_FREEING)
 217                                 continue;
 218
 219                         slice = cl_page_at_trusted(page, dtype);
 220                         /*
 221                          * Pages for lsm-less file has no underneath sub-page
 222                          * for osc, in case of ...
 223                          */
 224                         PASSERT(env, page, slice != NULL);
 225
 226                         page = slice->cpl_page;
 227                         /*
 228                          * Can safely call cl_page_get_trust() under
 229                          * radix-tree spin-lock.
 230                          *
 231                          * XXX not true, because @page is from object another
 232                          * than @hdr and protected by different tree lock.
 233                          */
 234                         cl_page_get_trust(page);
 235                         lu_ref_add_atomic(&page->cp_reference,
 236                                           "gang_lookup", cfs_current());
 237                         pvec[j++] = page;
 238                 }
 239
 240                 /*
 241                  * Here a delicate locking dance is performed. Current thread
 242                  * holds a reference to a page, but has to own it before it
 243                  * can be placed into queue. Owning implies waiting, so
 244                  * radix-tree lock is to be released. After a wait one has to
 245                  * check that pages weren't truncated (cl_page_own() returns
 246                  * error in the latter case).
 247                  */
 248                 spin_unlock(&hdr->coh_page_guard);
 249                 tree_lock = 0;
 250
 251                 for (i = 0; i < j; ++i) {
 252                         page = pvec[i];
 253                         if (res == CLP_GANG_OKAY)
 254                                 res = (*cb)(env, io, page, cbdata);
 255                         lu_ref_del(&page->cp_reference,
 256                                    "gang_lookup", cfs_current());
 257                         cl_page_put(env, page);
 258                 }
 259                 if (nr < CLT_PVEC_SIZE || end_of_region)
 260                         break;
 261
 262                 if (res == CLP_GANG_OKAY && cfs_need_resched())
 263                         res = CLP_GANG_RESCHED;
 264                 if (res != CLP_GANG_OKAY)
 265                         break;
 266
 267                 spin_lock(&hdr->coh_page_guard);
 268                 tree_lock = 1;
 269         }
 270         if (tree_lock)
 271                 spin_unlock(&hdr->coh_page_guard);
 272         RETURN(res);
 273 }
 274 EXPORT_SYMBOL(cl_page_gang_lookup);
 275
 276 static void cl_page_free(const struct lu_env *env, struct cl_page *page)
 277 {
 278         struct cl_object *obj  = page->cp_obj;
 279         int pagesize = cl_object_header(obj)->coh_page_bufsize;
 280
 281         PASSERT(env, page, cfs_list_empty(&page->cp_batch));
 282         PASSERT(env, page, page->cp_owner == NULL);
 283         PASSERT(env, page, page->cp_req == NULL);
 284         PASSERT(env, page, page->cp_parent == NULL);
 285         PASSERT(env, page, page->cp_state == CPS_FREEING);
 286
 287         ENTRY;
 288         cfs_might_sleep();
 289         while (!cfs_list_empty(&page->cp_layers)) {
 290                 struct cl_page_slice *slice;
 291
 292                 slice = cfs_list_entry(page->cp_layers.next,
 293                                        struct cl_page_slice, cpl_linkage);
 294                 cfs_list_del_init(page->cp_layers.next);
 295                 slice->cpl_ops->cpo_fini(env, slice);
 296         }
 297         CS_PAGE_DEC(obj, total);
 298         CS_PAGESTATE_DEC(obj, page->cp_state);
 299         lu_object_ref_del_at(&obj->co_lu, page->cp_obj_ref, "cl_page", page);
 300         cl_object_put(env, obj);
 301         lu_ref_fini(&page->cp_reference);
 302         OBD_FREE(page, pagesize);
 303         EXIT;
 304 }
 305
 306 /**
 307  * Helper function updating page state. This is the only place in the code
 308  * where cl_page::cp_state field is mutated.
 309  */
 310 static inline void cl_page_state_set_trust(struct cl_page *page,
 311                                            enum cl_page_state state)
 312 {
 313         /* bypass const. */
 314         *(enum cl_page_state *)&page->cp_state = state;
 315 }
 316
 317 static struct cl_page *cl_page_alloc(const struct lu_env *env,
 318                 struct cl_object *o, pgoff_t ind, struct page *vmpage,
 319                 enum cl_page_type type)
 320 {
 321         struct cl_page          *page;
 322         struct lu_object_header *head;
 323
 324         ENTRY;
 325         OBD_ALLOC_GFP(page, cl_object_header(o)->coh_page_bufsize,
 326                         CFS_ALLOC_IO);
 327         if (page != NULL) {
 328                 int result;
 329                 cfs_atomic_set(&page->cp_ref, 1);
 330                 if (type == CPT_CACHEABLE) /* for radix tree */
 331                         cfs_atomic_inc(&page->cp_ref);
 332                 page->cp_obj = o;
 333                 cl_object_get(o);
 334                 page->cp_obj_ref = lu_object_ref_add(&o->co_lu, "cl_page",page);
 335                 page->cp_index = ind;
 336                 cl_page_state_set_trust(page, CPS_CACHED);
 337                 page->cp_type = type;
 338                 CFS_INIT_LIST_HEAD(&page->cp_layers);
 339                 CFS_INIT_LIST_HEAD(&page->cp_batch);
 340                 CFS_INIT_LIST_HEAD(&page->cp_flight);
 341                 mutex_init(&page->cp_mutex);
 342                 lu_ref_init(&page->cp_reference);
 343                 head = o->co_lu.lo_header;
 344                 cfs_list_for_each_entry(o, &head->loh_layers,
 345                                         co_lu.lo_linkage) {
 346                         if (o->co_ops->coo_page_init != NULL) {
 347                                 result = o->co_ops->coo_page_init(env, o,
 348                                                                   page, vmpage);
 349                                 if (result != 0) {
 350                                         cl_page_delete0(env, page, 0);
 351                                         cl_page_free(env, page);
 352                                         page = ERR_PTR(result);
 353                                         break;
 354                                 }
 355                         }
 356                 }
 357                 if (result == 0) {
 358                         CS_PAGE_INC(o, total);
 359                         CS_PAGE_INC(o, create);
 360                         CS_PAGESTATE_DEC(o, CPS_CACHED);
 361                 }
 362         } else {
 363                 page = ERR_PTR(-ENOMEM);
 364         }
 365         RETURN(page);
 366 }
 367
 368 /**
 369  * Returns a cl_page with index \a idx at the object \a o, and associated with
 370  * the VM page \a vmpage.
 371  *
 372  * This is the main entry point into the cl_page caching interface. First, a
 373  * cache (implemented as a per-object radix tree) is consulted. If page is
 374  * found there, it is returned immediately. Otherwise new page is allocated
 375  * and returned. In any case, additional reference to page is acquired.
 376  *
 377  * \see cl_object_find(), cl_lock_find()
 378  */
 379 static struct cl_page *cl_page_find0(const struct lu_env *env,
 380                                      struct cl_object *o,
 381                                      pgoff_t idx, struct page *vmpage,
 382                                      enum cl_page_type type,
 383                                      struct cl_page *parent)
 384 {
 385         struct cl_page          *page = NULL;
 386         struct cl_page          *ghost = NULL;
 387         struct cl_object_header *hdr;
 388         int err;
 389
 390         LASSERT(type == CPT_CACHEABLE || type == CPT_TRANSIENT);
 391         cfs_might_sleep();
 392
 393         ENTRY;
 394
 395         hdr = cl_object_header(o);
 396         CS_PAGE_INC(o, lookup);
 397
 398         CDEBUG(D_PAGE, "%lu@"DFID" %p %lx %d\n",
 399                idx, PFID(&hdr->coh_lu.loh_fid), vmpage, vmpage->private, type);
 400         /* fast path. */
 401         if (type == CPT_CACHEABLE) {
 402                 /* vmpage lock is used to protect the child/parent
 403                  * relationship */
 404                 KLASSERT(PageLocked(vmpage));
 405                 /*
 406                  * cl_vmpage_page() can be called here without any locks as
 407                  *
 408                  *     - "vmpage" is locked (which prevents ->private from
 409                  *       concurrent updates), and
 410                  *
 411                  *     - "o" cannot be destroyed while current thread holds a
 412                  *       reference on it.
 413                  */
 414                 page = cl_vmpage_page(vmpage, o);
 415                 PINVRNT(env, page,
 416                         ergo(page != NULL,
 417                              cl_page_vmpage(env, page) == vmpage &&
 418                              (void *)radix_tree_lookup(&hdr->coh_tree,
 419                                                        idx) == page));
 420         }
 421
 422         if (page != NULL) {
 423                 CS_PAGE_INC(o, hit);
 424                 RETURN(page);
 425         }
 426
 427         /* allocate and initialize cl_page */
 428         page = cl_page_alloc(env, o, idx, vmpage, type);
 429         if (IS_ERR(page))
 430                 RETURN(page);
 431
 432         if (type == CPT_TRANSIENT) {
 433                 if (parent) {
 434                         LASSERT(page->cp_parent == NULL);
 435                         page->cp_parent = parent;
 436                         parent->cp_child = page;
 437                 }
 438                 RETURN(page);
 439         }
 440
 441         /*
 442          * XXX optimization: use radix_tree_preload() here, and change tree
 443          * gfp mask to GFP_KERNEL in cl_object_header_init().
 444          */
 445         spin_lock(&hdr->coh_page_guard);
 446         err = radix_tree_insert(&hdr->coh_tree, idx, page);
 447         if (err != 0) {
 448                 ghost = page;
 449                 /*
 450                  * Noted by Jay: a lock on \a vmpage protects cl_page_find()
 451                  * from this race, but
 452                  *
 453                  *     0. it's better to have cl_page interface "locally
 454                  *     consistent" so that its correctness can be reasoned
 455                  *     about without appealing to the (obscure world of) VM
 456                  *     locking.
 457                  *
 458                  *     1. handling this race allows ->coh_tree to remain
 459                  *     consistent even when VM locking is somehow busted,
 460                  *     which is very useful during diagnosing and debugging.
 461                  */
 462                 page = ERR_PTR(err);
 463                 CL_PAGE_DEBUG(D_ERROR, env, ghost,
 464                               "fail to insert into radix tree: %d\n", err);
 465         } else {
 466                 if (parent) {
 467                         LASSERT(page->cp_parent == NULL);
 468                         page->cp_parent = parent;
 469                         parent->cp_child = page;
 470                 }
 471                 hdr->coh_pages++;
 472         }
 473         spin_unlock(&hdr->coh_page_guard);
 474
 475         if (unlikely(ghost != NULL)) {
 476                 cl_page_delete0(env, ghost, 0);
 477                 cl_page_free(env, ghost);
 478         }
 479         RETURN(page);
 480 }
 481
 482 struct cl_page *cl_page_find(const struct lu_env *env, struct cl_object *o,
 483                              pgoff_t idx, struct page *vmpage,
 484                              enum cl_page_type type)
 485 {
 486         return cl_page_find0(env, o, idx, vmpage, type, NULL);
 487 }
 488 EXPORT_SYMBOL(cl_page_find);
 489
 490
 491 struct cl_page *cl_page_find_sub(const struct lu_env *env, struct cl_object *o,
 492                                  pgoff_t idx, struct page *vmpage,
 493                                  struct cl_page *parent)
 494 {
 495         return cl_page_find0(env, o, idx, vmpage, parent->cp_type, parent);
 496 }
 497 EXPORT_SYMBOL(cl_page_find_sub);
 498
 499 static inline int cl_page_invariant(const struct cl_page *pg)
 500 {
 501         struct cl_object_header *header;
 502         struct cl_page          *parent;
 503         struct cl_page          *child;
 504         struct cl_io            *owner;
 505
 506         /*
 507          * Page invariant is protected by a VM lock.
 508          */
 509         LINVRNT(cl_page_is_vmlocked(NULL, pg));
 510
 511         header = cl_object_header(pg->cp_obj);
 512         parent = pg->cp_parent;
 513         child  = pg->cp_child;
 514         owner  = pg->cp_owner;
 515
 516         return cl_page_in_use(pg) &&
 517                 ergo(parent != NULL, parent->cp_child == pg) &&
 518                 ergo(child != NULL, child->cp_parent == pg) &&
 519                 ergo(child != NULL, pg->cp_obj != child->cp_obj) &&
 520                 ergo(parent != NULL, pg->cp_obj != parent->cp_obj) &&
 521                 ergo(owner != NULL && parent != NULL,
 522                      parent->cp_owner == pg->cp_owner->ci_parent) &&
 523                 ergo(owner != NULL && child != NULL,
 524                      child->cp_owner->ci_parent == owner) &&
 525                 /*
 526                  * Either page is early in initialization (has neither child
 527                  * nor parent yet), or it is in the object radix tree.
 528                  */
 529                 ergo(pg->cp_state < CPS_FREEING && pg->cp_type == CPT_CACHEABLE,
 530                      (void *)radix_tree_lookup(&header->coh_tree,
 531                                                pg->cp_index) == pg ||
 532                      (child == NULL && parent == NULL));
 533 }
 534
 535 static void cl_page_state_set0(const struct lu_env *env,
 536                                struct cl_page *page, enum cl_page_state state)
 537 {
 538         enum cl_page_state old;
 539
 540         /*
 541          * Matrix of allowed state transitions [old][new], for sanity
 542          * checking.
 543          */
 544         static const int allowed_transitions[CPS_NR][CPS_NR] = {
 545                 [CPS_CACHED] = {
 546                         [CPS_CACHED]  = 0,
 547                         [CPS_OWNED]   = 1, /* io finds existing cached page */
 548                         [CPS_PAGEIN]  = 0,
 549                         [CPS_PAGEOUT] = 1, /* write-out from the cache */
 550                         [CPS_FREEING] = 1, /* eviction on the memory pressure */
 551                 },
 552                 [CPS_OWNED] = {
 553                         [CPS_CACHED]  = 1, /* release to the cache */
 554                         [CPS_OWNED]   = 0,
 555                         [CPS_PAGEIN]  = 1, /* start read immediately */
 556                         [CPS_PAGEOUT] = 1, /* start write immediately */
 557                         [CPS_FREEING] = 1, /* lock invalidation or truncate */
 558                 },
 559                 [CPS_PAGEIN] = {
 560                         [CPS_CACHED]  = 1, /* io completion */
 561                         [CPS_OWNED]   = 0,
 562                         [CPS_PAGEIN]  = 0,
 563                         [CPS_PAGEOUT] = 0,
 564                         [CPS_FREEING] = 0,
 565                 },
 566                 [CPS_PAGEOUT] = {
 567                         [CPS_CACHED]  = 1, /* io completion */
 568                         [CPS_OWNED]   = 0,
 569                         [CPS_PAGEIN]  = 0,
 570                         [CPS_PAGEOUT] = 0,
 571                         [CPS_FREEING] = 0,
 572                 },
 573                 [CPS_FREEING] = {
 574                         [CPS_CACHED]  = 0,
 575                         [CPS_OWNED]   = 0,
 576                         [CPS_PAGEIN]  = 0,
 577                         [CPS_PAGEOUT] = 0,
 578                         [CPS_FREEING] = 0,
 579                 }
 580         };
 581
 582         ENTRY;
 583         old = page->cp_state;
 584         PASSERT(env, page, allowed_transitions[old][state]);
 585         CL_PAGE_HEADER(D_TRACE, env, page, "%d -> %d\n", old, state);
 586         for (; page != NULL; page = page->cp_child) {
 587                 PASSERT(env, page, page->cp_state == old);
 588                 PASSERT(env, page,
 589                         equi(state == CPS_OWNED, page->cp_owner != NULL));
 590
 591                 CS_PAGESTATE_DEC(page->cp_obj, page->cp_state);
 592                 CS_PAGESTATE_INC(page->cp_obj, state);
 593                 cl_page_state_set_trust(page, state);
 594         }
 595         EXIT;
 596 }
 597
 598 static void cl_page_state_set(const struct lu_env *env,
 599                               struct cl_page *page, enum cl_page_state state)
 600 {
 601         cl_page_state_set0(env, page, state);
 602 }
 603
 604 /**
 605  * Acquires an additional reference to a page.
 606  *
 607  * This can be called only by caller already possessing a reference to \a
 608  * page.
 609  *
 610  * \see cl_object_get(), cl_lock_get().
 611  */
 612 void cl_page_get(struct cl_page *page)
 613 {
 614         ENTRY;
 615         cl_page_get_trust(page);
 616         EXIT;
 617 }
 618 EXPORT_SYMBOL(cl_page_get);
 619
 620 /**
 621  * Releases a reference to a page.
 622  *
 623  * When last reference is released, page is returned to the cache, unless it
 624  * is in cl_page_state::CPS_FREEING state, in which case it is immediately
 625  * destroyed.
 626  *
 627  * \see cl_object_put(), cl_lock_put().
 628  */
 629 void cl_page_put(const struct lu_env *env, struct cl_page *page)
 630 {
 631         PASSERT(env, page, cfs_atomic_read(&page->cp_ref) > !!page->cp_parent);
 632
 633         ENTRY;
 634         CL_PAGE_HEADER(D_TRACE, env, page, "%d\n",
 635                        cfs_atomic_read(&page->cp_ref));
 636
 637         if (cfs_atomic_dec_and_test(&page->cp_ref)) {
 638                 LASSERT(page->cp_state == CPS_FREEING);
 639
 640                 LASSERT(cfs_atomic_read(&page->cp_ref) == 0);
 641                 PASSERT(env, page, page->cp_owner == NULL);
 642                 PASSERT(env, page, cfs_list_empty(&page->cp_batch));
 643                 /*
 644                  * Page is no longer reachable by other threads. Tear
 645                  * it down.
 646                  */
 647                 cl_page_free(env, page);
 648         }
 649
 650         EXIT;
 651 }
 652 EXPORT_SYMBOL(cl_page_put);
 653
 654 /**
 655  * Returns a VM page associated with a given cl_page.
 656  */
 657 cfs_page_t *cl_page_vmpage(const struct lu_env *env, struct cl_page *page)
 658 {
 659         const struct cl_page_slice *slice;
 660
 661         /*
 662          * Find uppermost layer with ->cpo_vmpage() method, and return its
 663          * result.
 664          */
 665         page = cl_page_top(page);
 666         do {
 667                 cfs_list_for_each_entry(slice, &page->cp_layers, cpl_linkage) {
 668                         if (slice->cpl_ops->cpo_vmpage != NULL)
 669                                 RETURN(slice->cpl_ops->cpo_vmpage(env, slice));
 670                 }
 671                 page = page->cp_child;
 672         } while (page != NULL);
 673         LBUG(); /* ->cpo_vmpage() has to be defined somewhere in the stack */
 674 }
 675 EXPORT_SYMBOL(cl_page_vmpage);
 676
 677 /**
 678  * Returns a cl_page associated with a VM page, and given cl_object.
 679  */
 680 struct cl_page *cl_vmpage_page(cfs_page_t *vmpage, struct cl_object *obj)
 681 {
 682         struct cl_page *top;
 683         struct cl_page *page;
 684
 685         ENTRY;
 686         KLASSERT(PageLocked(vmpage));
 687
 688         /*
 689          * NOTE: absence of races and liveness of data are guaranteed by page
 690          *       lock on a "vmpage". That works because object destruction has
 691          *       bottom-to-top pass.
 692          */
 693
 694         /*
 695          * This loop assumes that ->private points to the top-most page. This
 696          * can be rectified easily.
 697          */
 698         top = (struct cl_page *)vmpage->private;
 699         if (top == NULL)
 700                 RETURN(NULL);
 701
 702         for (page = top; page != NULL; page = page->cp_child) {
 703                 if (cl_object_same(page->cp_obj, obj)) {
 704                         cl_page_get_trust(page);
 705                         break;
 706                 }
 707         }
 708         LASSERT(ergo(page, page->cp_type == CPT_CACHEABLE));
 709         RETURN(page);
 710 }
 711 EXPORT_SYMBOL(cl_vmpage_page);
 712
 713 /**
 714  * Returns the top-page for a given page.
 715  *
 716  * \see cl_object_top(), cl_io_top()
 717  */
 718 struct cl_page *cl_page_top(struct cl_page *page)
 719 {
 720         return cl_page_top_trusted(page);
 721 }
 722 EXPORT_SYMBOL(cl_page_top);
 723
 724 const struct cl_page_slice *cl_page_at(const struct cl_page *page,
 725                                        const struct lu_device_type *dtype)
 726 {
 727         return cl_page_at_trusted(page, dtype);
 728 }
 729 EXPORT_SYMBOL(cl_page_at);
 730
 731 #define CL_PAGE_OP(opname) offsetof(struct cl_page_operations, opname)
 732
 733 #define CL_PAGE_INVOKE(_env, _page, _op, _proto, ...)                   \
 734 ({                                                                      \
 735         const struct lu_env        *__env  = (_env);                    \
 736         struct cl_page             *__page = (_page);                   \
 737         const struct cl_page_slice *__scan;                             \
 738         int                         __result;                           \
 739         ptrdiff_t                   __op   = (_op);                     \
 740         int                       (*__method)_proto;                    \
 741                                                                         \
 742         __result = 0;                                                   \
 743         __page = cl_page_top(__page);                                   \
 744         do {                                                            \
 745                 cfs_list_for_each_entry(__scan, &__page->cp_layers,     \
 746                                         cpl_linkage) {                  \
 747                         __method = *(void **)((char *)__scan->cpl_ops + \
 748                                               __op);                    \
 749                         if (__method != NULL) {                         \
 750                                 __result = (*__method)(__env, __scan,   \
 751                                                        ## __VA_ARGS__); \
 752                                 if (__result != 0)                      \
 753                                         break;                          \
 754                         }                                               \
 755                 }                                                       \
 756                 __page = __page->cp_child;                              \
 757         } while (__page != NULL && __result == 0);                      \
 758         if (__result > 0)                                               \
 759                 __result = 0;                                           \
 760         __result;                                                       \
 761 })
 762
 763 #define CL_PAGE_INVOID(_env, _page, _op, _proto, ...)                   \
 764 do {                                                                    \
 765         const struct lu_env        *__env  = (_env);                    \
 766         struct cl_page             *__page = (_page);                   \
 767         const struct cl_page_slice *__scan;                             \
 768         ptrdiff_t                   __op   = (_op);                     \
 769         void                      (*__method)_proto;                    \
 770                                                                         \
 771         __page = cl_page_top(__page);                                   \
 772         do {                                                            \
 773                 cfs_list_for_each_entry(__scan, &__page->cp_layers,     \
 774                                         cpl_linkage) {                  \
 775                         __method = *(void **)((char *)__scan->cpl_ops + \
 776                                               __op);                    \
 777                         if (__method != NULL)                           \
 778                                 (*__method)(__env, __scan,              \
 779                                             ## __VA_ARGS__);            \
 780                 }                                                       \
 781                 __page = __page->cp_child;                              \
 782         } while (__page != NULL);                                       \
 783 } while (0)
 784
 785 #define CL_PAGE_INVOID_REVERSE(_env, _page, _op, _proto, ...)               \
 786 do {                                                                        \
 787         const struct lu_env        *__env  = (_env);                        \
 788         struct cl_page             *__page = (_page);                       \
 789         const struct cl_page_slice *__scan;                                 \
 790         ptrdiff_t                   __op   = (_op);                         \
 791         void                      (*__method)_proto;                        \
 792                                                                             \
 793         /* get to the bottom page. */                                       \
 794         while (__page->cp_child != NULL)                                    \
 795                 __page = __page->cp_child;                                  \
 796         do {                                                                \
 797                 cfs_list_for_each_entry_reverse(__scan, &__page->cp_layers, \
 798                                                 cpl_linkage) {              \
 799                         __method = *(void **)((char *)__scan->cpl_ops +     \
 800                                               __op);                        \
 801                         if (__method != NULL)                               \
 802                                 (*__method)(__env, __scan,                  \
 803                                             ## __VA_ARGS__);                \
 804                 }                                                           \
 805                 __page = __page->cp_parent;                                 \
 806         } while (__page != NULL);                                           \
 807 } while (0)
 808
 809 static int cl_page_invoke(const struct lu_env *env,
 810                           struct cl_io *io, struct cl_page *page, ptrdiff_t op)
 811
 812 {
 813         PINVRNT(env, page, cl_object_same(page->cp_obj, io->ci_obj));
 814         ENTRY;
 815         RETURN(CL_PAGE_INVOKE(env, page, op,
 816                               (const struct lu_env *,
 817                                const struct cl_page_slice *, struct cl_io *),
 818                               io));
 819 }
 820
 821 static void cl_page_invoid(const struct lu_env *env,
 822                            struct cl_io *io, struct cl_page *page, ptrdiff_t op)
 823
 824 {
 825         PINVRNT(env, page, cl_object_same(page->cp_obj, io->ci_obj));
 826         ENTRY;
 827         CL_PAGE_INVOID(env, page, op,
 828                        (const struct lu_env *,
 829                         const struct cl_page_slice *, struct cl_io *), io);
 830         EXIT;
 831 }
 832
 833 static void cl_page_owner_clear(struct cl_page *page)
 834 {
 835         ENTRY;
 836         for (page = cl_page_top(page); page != NULL; page = page->cp_child) {
 837                 if (page->cp_owner != NULL) {
 838                         LASSERT(page->cp_owner->ci_owned_nr > 0);
 839                         page->cp_owner->ci_owned_nr--;
 840                         page->cp_owner = NULL;
 841                         page->cp_task = NULL;
 842                 }
 843         }
 844         EXIT;
 845 }
 846
 847 static void cl_page_owner_set(struct cl_page *page)
 848 {
 849         ENTRY;
 850         for (page = cl_page_top(page); page != NULL; page = page->cp_child) {
 851                 LASSERT(page->cp_owner != NULL);
 852                 page->cp_owner->ci_owned_nr++;
 853         }
 854         EXIT;
 855 }
 856
 857 void cl_page_disown0(const struct lu_env *env,
 858                      struct cl_io *io, struct cl_page *pg)
 859 {
 860         enum cl_page_state state;
 861
 862         ENTRY;
 863         state = pg->cp_state;
 864         PINVRNT(env, pg, state == CPS_OWNED || state == CPS_FREEING);
 865         PINVRNT(env, pg, cl_page_invariant(pg));
 866         cl_page_owner_clear(pg);
 867
 868         if (state == CPS_OWNED)
 869                 cl_page_state_set(env, pg, CPS_CACHED);
 870         /*
 871          * Completion call-backs are executed in the bottom-up order, so that
 872          * uppermost layer (llite), responsible for VFS/VM interaction runs
 873          * last and can release locks safely.
 874          */
 875         CL_PAGE_INVOID_REVERSE(env, pg, CL_PAGE_OP(cpo_disown),
 876                                (const struct lu_env *,
 877                                 const struct cl_page_slice *, struct cl_io *),
 878                                io);
 879         EXIT;
 880 }
 881
 882 /**
 883  * returns true, iff page is owned by the given io.
 884  */
 885 int cl_page_is_owned(const struct cl_page *pg, const struct cl_io *io)
 886 {
 887         LINVRNT(cl_object_same(pg->cp_obj, io->ci_obj));
 888         ENTRY;
 889         RETURN(pg->cp_state == CPS_OWNED && pg->cp_owner == io);
 890 }
 891 EXPORT_SYMBOL(cl_page_is_owned);
 892
 893 /**
 894  * Try to own a page by IO.
 895  *
 896  * Waits until page is in cl_page_state::CPS_CACHED state, and then switch it
 897  * into cl_page_state::CPS_OWNED state.
 898  *
 899  * \pre  !cl_page_is_owned(pg, io)
 900  * \post result == 0 iff cl_page_is_owned(pg, io)
 901  *
 902  * \retval 0   success
 903  *
 904  * \retval -ve failure, e.g., page was destroyed (and landed in
 905  *             cl_page_state::CPS_FREEING instead of cl_page_state::CPS_CACHED).
 906  *             or, page was owned by another thread, or in IO.
 907  *
 908  * \see cl_page_disown()
 909  * \see cl_page_operations::cpo_own()
 910  * \see cl_page_own_try()
 911  * \see cl_page_own
 912  */
 913 static int cl_page_own0(const struct lu_env *env, struct cl_io *io,
 914                         struct cl_page *pg, int nonblock)
 915 {
 916         int result;
 917
 918         PINVRNT(env, pg, !cl_page_is_owned(pg, io));
 919
 920         ENTRY;
 921         pg = cl_page_top(pg);
 922         io = cl_io_top(io);
 923
 924         if (pg->cp_state == CPS_FREEING) {
 925                 result = -ENOENT;
 926         } else {
 927                 result = CL_PAGE_INVOKE(env, pg, CL_PAGE_OP(cpo_own),
 928                                         (const struct lu_env *,
 929                                          const struct cl_page_slice *,
 930                                          struct cl_io *, int),
 931                                         io, nonblock);
 932                 if (result == 0) {
 933                         PASSERT(env, pg, pg->cp_owner == NULL);
 934                         PASSERT(env, pg, pg->cp_req == NULL);
 935                         pg->cp_owner = io;
 936                         pg->cp_task  = current;
 937                         cl_page_owner_set(pg);
 938                         if (pg->cp_state != CPS_FREEING) {
 939                                 cl_page_state_set(env, pg, CPS_OWNED);
 940                         } else {
 941                                 cl_page_disown0(env, io, pg);
 942                                 result = -ENOENT;
 943                         }
 944                 }
 945         }
 946         PINVRNT(env, pg, ergo(result == 0, cl_page_invariant(pg)));
 947         RETURN(result);
 948 }
 949
 950 /**
 951  * Own a page, might be blocked.
 952  *
 953  * \see cl_page_own0()
 954  */
 955 int cl_page_own(const struct lu_env *env, struct cl_io *io, struct cl_page *pg)
 956 {
 957         return cl_page_own0(env, io, pg, 0);
 958 }
 959 EXPORT_SYMBOL(cl_page_own);
 960
 961 /**
 962  * Nonblock version of cl_page_own().
 963  *
 964  * \see cl_page_own0()
 965  */
 966 int cl_page_own_try(const struct lu_env *env, struct cl_io *io,
 967                     struct cl_page *pg)
 968 {
 969         return cl_page_own0(env, io, pg, 1);
 970 }
 971 EXPORT_SYMBOL(cl_page_own_try);
 972
 973
 974 /**
 975  * Assume page ownership.
 976  *
 977  * Called when page is already locked by the hosting VM.
 978  *
 979  * \pre !cl_page_is_owned(pg, io)
 980  * \post cl_page_is_owned(pg, io)
 981  *
 982  * \see cl_page_operations::cpo_assume()
 983  */
 984 void cl_page_assume(const struct lu_env *env,
 985                     struct cl_io *io, struct cl_page *pg)
 986 {
 987         PINVRNT(env, pg, cl_object_same(pg->cp_obj, io->ci_obj));
 988
 989         ENTRY;
 990         pg = cl_page_top(pg);
 991         io = cl_io_top(io);
 992
 993         cl_page_invoid(env, io, pg, CL_PAGE_OP(cpo_assume));
 994         PASSERT(env, pg, pg->cp_owner == NULL);
 995         pg->cp_owner = io;
 996         pg->cp_task = current;
 997         cl_page_owner_set(pg);
 998         cl_page_state_set(env, pg, CPS_OWNED);
 999         EXIT;
1000 }
1001 EXPORT_SYMBOL(cl_page_assume);
1002
1003 /**
1004  * Releases page ownership without unlocking the page.
1005  *
1006  * Moves page into cl_page_state::CPS_CACHED without releasing a lock on the
1007  * underlying VM page (as VM is supposed to do this itself).
1008  *
1009  * \pre   cl_page_is_owned(pg, io)
1010  * \post !cl_page_is_owned(pg, io)
1011  *
1012  * \see cl_page_assume()
1013  */
1014 void cl_page_unassume(const struct lu_env *env,
1015                       struct cl_io *io, struct cl_page *pg)
1016 {
1017         PINVRNT(env, pg, cl_page_is_owned(pg, io));
1018         PINVRNT(env, pg, cl_page_invariant(pg));
1019
1020         ENTRY;
1021         pg = cl_page_top(pg);
1022         io = cl_io_top(io);
1023         cl_page_owner_clear(pg);
1024         cl_page_state_set(env, pg, CPS_CACHED);
1025         CL_PAGE_INVOID_REVERSE(env, pg, CL_PAGE_OP(cpo_unassume),
1026                                (const struct lu_env *,
1027                                 const struct cl_page_slice *, struct cl_io *),
1028                                io);
1029         EXIT;
1030 }
1031 EXPORT_SYMBOL(cl_page_unassume);
1032
1033 /**
1034  * Releases page ownership.
1035  *
1036  * Moves page into cl_page_state::CPS_CACHED.
1037  *
1038  * \pre   cl_page_is_owned(pg, io)
1039  * \post !cl_page_is_owned(pg, io)
1040  *
1041  * \see cl_page_own()
1042  * \see cl_page_operations::cpo_disown()
1043  */
1044 void cl_page_disown(const struct lu_env *env,
1045                     struct cl_io *io, struct cl_page *pg)
1046 {
1047         PINVRNT(env, pg, cl_page_is_owned(pg, io));
1048
1049         ENTRY;
1050         pg = cl_page_top(pg);
1051         io = cl_io_top(io);
1052         cl_page_disown0(env, io, pg);
1053         EXIT;
1054 }
1055 EXPORT_SYMBOL(cl_page_disown);
1056
1057 /**
1058  * Called when page is to be removed from the object, e.g., as a result of
1059  * truncate.
1060  *
1061  * Calls cl_page_operations::cpo_discard() top-to-bottom.
1062  *
1063  * \pre cl_page_is_owned(pg, io)
1064  *
1065  * \see cl_page_operations::cpo_discard()
1066  */
1067 void cl_page_discard(const struct lu_env *env,
1068                      struct cl_io *io, struct cl_page *pg)
1069 {
1070         PINVRNT(env, pg, cl_page_is_owned(pg, io));
1071         PINVRNT(env, pg, cl_page_invariant(pg));
1072
1073         cl_page_invoid(env, io, pg, CL_PAGE_OP(cpo_discard));
1074 }
1075 EXPORT_SYMBOL(cl_page_discard);
1076
1077 /**
1078  * Version of cl_page_delete() that can be called for not fully constructed
1079  * pages, e.g,. in a error handling cl_page_find()->cl_page_delete0()
1080  * path. Doesn't check page invariant.
1081  */
1082 static void cl_page_delete0(const struct lu_env *env, struct cl_page *pg,
1083                             int radix)
1084 {
1085         struct cl_page *tmp = pg;
1086         ENTRY;
1087
1088         PASSERT(env, pg, pg == cl_page_top(pg));
1089         PASSERT(env, pg, pg->cp_state != CPS_FREEING);
1090
1091         /*
1092          * Severe all ways to obtain new pointers to @pg.
1093          */
1094         cl_page_owner_clear(pg);
1095
1096         /*
1097          * unexport the page firstly before freeing it so that
1098          * the page content is considered to be invalid.
1099          * We have to do this because a CPS_FREEING cl_page may
1100          * be NOT under the protection of a cl_lock.
1101          * Afterwards, if this page is found by other threads, then this
1102          * page will be forced to reread.
1103          */
1104         cl_page_export(env, pg, 0);
1105         cl_page_state_set0(env, pg, CPS_FREEING);
1106
1107         CL_PAGE_INVOID(env, pg, CL_PAGE_OP(cpo_delete),
1108                        (const struct lu_env *, const struct cl_page_slice *));
1109
1110         if (tmp->cp_type == CPT_CACHEABLE) {
1111                 if (!radix)
1112                         /* !radix means that @pg is not yet in the radix tree,
1113                          * skip removing it.
1114                          */
1115                         tmp = pg->cp_child;
1116                 for (; tmp != NULL; tmp = tmp->cp_child) {
1117                         void                    *value;
1118                         struct cl_object_header *hdr;
1119
1120                         hdr = cl_object_header(tmp->cp_obj);
1121                         spin_lock(&hdr->coh_page_guard);
1122                         value = radix_tree_delete(&hdr->coh_tree,
1123                                                   tmp->cp_index);
1124                         PASSERT(env, tmp, value == tmp);
1125                         PASSERT(env, tmp, hdr->coh_pages > 0);
1126                         hdr->coh_pages--;
1127                         spin_unlock(&hdr->coh_page_guard);
1128                         cl_page_put(env, tmp);
1129                 }
1130         }
1131
1132         EXIT;
1133 }
1134
1135 /**
1136  * Called when a decision is made to throw page out of memory.
1137  *
1138  * Notifies all layers about page destruction by calling
1139  * cl_page_operations::cpo_delete() method top-to-bottom.
1140  *
1141  * Moves page into cl_page_state::CPS_FREEING state (this is the only place
1142  * where transition to this state happens).
1143  *
1144  * Eliminates all venues through which new references to the page can be
1145  * obtained:
1146  *
1147  *     - removes page from the radix trees,
1148  *
1149  *     - breaks linkage from VM page to cl_page.
1150  *
1151  * Once page reaches cl_page_state::CPS_FREEING, all remaining references will
1152  * drain after some time, at which point page will be recycled.
1153  *
1154  * \pre  pg == cl_page_top(pg)
1155  * \pre  VM page is locked
1156  * \post pg->cp_state == CPS_FREEING
1157  *
1158  * \see cl_page_operations::cpo_delete()
1159  */
1160 void cl_page_delete(const struct lu_env *env, struct cl_page *pg)
1161 {
1162         PINVRNT(env, pg, cl_page_invariant(pg));
1163         ENTRY;
1164         cl_page_delete0(env, pg, 1);
1165         EXIT;
1166 }
1167 EXPORT_SYMBOL(cl_page_delete);
1168
1169 /**
1170  * Unmaps page from user virtual memory.
1171  *
1172  * Calls cl_page_operations::cpo_unmap() through all layers top-to-bottom. The
1173  * layer responsible for VM interaction has to unmap page from user space
1174  * virtual memory.
1175  *
1176  * \see cl_page_operations::cpo_unmap()
1177  */
1178 int cl_page_unmap(const struct lu_env *env,
1179                   struct cl_io *io, struct cl_page *pg)
1180 {
1181         PINVRNT(env, pg, cl_page_is_owned(pg, io));
1182         PINVRNT(env, pg, cl_page_invariant(pg));
1183
1184         return cl_page_invoke(env, io, pg, CL_PAGE_OP(cpo_unmap));
1185 }
1186 EXPORT_SYMBOL(cl_page_unmap);
1187
1188 /**
1189  * Marks page up-to-date.
1190  *
1191  * Call cl_page_operations::cpo_export() through all layers top-to-bottom. The
1192  * layer responsible for VM interaction has to mark/clear page as up-to-date
1193  * by the \a uptodate argument.
1194  *
1195  * \see cl_page_operations::cpo_export()
1196  */
1197 void cl_page_export(const struct lu_env *env, struct cl_page *pg, int uptodate)
1198 {
1199         PINVRNT(env, pg, cl_page_invariant(pg));
1200         CL_PAGE_INVOID(env, pg, CL_PAGE_OP(cpo_export),
1201                        (const struct lu_env *,
1202                         const struct cl_page_slice *, int), uptodate);
1203 }
1204 EXPORT_SYMBOL(cl_page_export);
1205
1206 /**
1207  * Returns true, iff \a pg is VM locked in a suitable sense by the calling
1208  * thread.
1209  */
1210 int cl_page_is_vmlocked(const struct lu_env *env, const struct cl_page *pg)
1211 {
1212         int result;
1213         const struct cl_page_slice *slice;
1214
1215         ENTRY;
1216         pg = cl_page_top_trusted((struct cl_page *)pg);
1217         slice = container_of(pg->cp_layers.next,
1218                              const struct cl_page_slice, cpl_linkage);
1219         PASSERT(env, pg, slice->cpl_ops->cpo_is_vmlocked != NULL);
1220         /*
1221          * Call ->cpo_is_vmlocked() directly instead of going through
1222          * CL_PAGE_INVOKE(), because cl_page_is_vmlocked() is used by
1223          * cl_page_invariant().
1224          */
1225         result = slice->cpl_ops->cpo_is_vmlocked(env, slice);
1226         PASSERT(env, pg, result == -EBUSY || result == -ENODATA);
1227         RETURN(result == -EBUSY);
1228 }
1229 EXPORT_SYMBOL(cl_page_is_vmlocked);
1230
1231 static enum cl_page_state cl_req_type_state(enum cl_req_type crt)
1232 {
1233         ENTRY;
1234         RETURN(crt == CRT_WRITE ? CPS_PAGEOUT : CPS_PAGEIN);
1235 }
1236
1237 static void cl_page_io_start(const struct lu_env *env,
1238                              struct cl_page *pg, enum cl_req_type crt)
1239 {
1240         /*
1241          * Page is queued for IO, change its state.
1242          */
1243         ENTRY;
1244         cl_page_owner_clear(pg);
1245         cl_page_state_set(env, pg, cl_req_type_state(crt));
1246         EXIT;
1247 }
1248
1249 /**
1250  * Prepares page for immediate transfer. cl_page_operations::cpo_prep() is
1251  * called top-to-bottom. Every layer either agrees to submit this page (by
1252  * returning 0), or requests to omit this page (by returning -EALREADY). Layer
1253  * handling interactions with the VM also has to inform VM that page is under
1254  * transfer now.
1255  */
1256 int cl_page_prep(const struct lu_env *env, struct cl_io *io,
1257                  struct cl_page *pg, enum cl_req_type crt)
1258 {
1259         int result;
1260
1261         PINVRNT(env, pg, cl_page_is_owned(pg, io));
1262         PINVRNT(env, pg, cl_page_invariant(pg));
1263         PINVRNT(env, pg, crt < CRT_NR);
1264
1265         /*
1266          * XXX this has to be called bottom-to-top, so that llite can set up
1267          * PG_writeback without risking other layers deciding to skip this
1268          * page.
1269          */
1270         result = cl_page_invoke(env, io, pg, CL_PAGE_OP(io[crt].cpo_prep));
1271         if (result == 0)
1272                 cl_page_io_start(env, pg, crt);
1273
1274         KLASSERT(ergo(crt == CRT_WRITE && pg->cp_type == CPT_CACHEABLE,
1275                       equi(result == 0,
1276                            PageWriteback(cl_page_vmpage(env, pg)))));
1277         CL_PAGE_HEADER(D_TRACE, env, pg, "%d %d\n", crt, result);
1278         return result;
1279 }
1280 EXPORT_SYMBOL(cl_page_prep);
1281
1282 /**
1283  * Notify layers about transfer completion.
1284  *
1285  * Invoked by transfer sub-system (which is a part of osc) to notify layers
1286  * that a transfer, of which this page is a part of has completed.
1287  *
1288  * Completion call-backs are executed in the bottom-up order, so that
1289  * uppermost layer (llite), responsible for the VFS/VM interaction runs last
1290  * and can release locks safely.
1291  *
1292  * \pre  pg->cp_state == CPS_PAGEIN || pg->cp_state == CPS_PAGEOUT
1293  * \post pg->cp_state == CPS_CACHED
1294  *
1295  * \see cl_page_operations::cpo_completion()
1296  */
1297 void cl_page_completion(const struct lu_env *env,
1298                         struct cl_page *pg, enum cl_req_type crt, int ioret)
1299 {
1300         struct cl_sync_io *anchor = pg->cp_sync_io;
1301
1302         PASSERT(env, pg, crt < CRT_NR);
1303         /* cl_page::cp_req already cleared by the caller (osc_completion()) */
1304         PASSERT(env, pg, pg->cp_req == NULL);
1305         PASSERT(env, pg, pg->cp_state == cl_req_type_state(crt));
1306
1307         ENTRY;
1308         CL_PAGE_HEADER(D_TRACE, env, pg, "%d %d\n", crt, ioret);
1309         if (crt == CRT_READ && ioret == 0) {
1310                 PASSERT(env, pg, !(pg->cp_flags & CPF_READ_COMPLETED));
1311                 pg->cp_flags |= CPF_READ_COMPLETED;
1312         }
1313
1314         cl_page_state_set(env, pg, CPS_CACHED);
1315         CL_PAGE_INVOID_REVERSE(env, pg, CL_PAGE_OP(io[crt].cpo_completion),
1316                                (const struct lu_env *,
1317                                 const struct cl_page_slice *, int), ioret);
1318         if (anchor) {
1319                 LASSERT(cl_page_is_vmlocked(env, pg));
1320                 LASSERT(pg->cp_sync_io == anchor);
1321                 pg->cp_sync_io = NULL;
1322         }
1323         /*
1324          * As page->cp_obj is pinned by a reference from page->cp_req, it is
1325          * safe to call cl_page_put() without risking object destruction in a
1326          * non-blocking context.
1327          */
1328         cl_page_put(env, pg);
1329
1330         if (anchor)
1331                 cl_sync_io_note(anchor, ioret);
1332
1333         EXIT;
1334 }
1335 EXPORT_SYMBOL(cl_page_completion);
1336
1337 /**
1338  * Notify layers that transfer formation engine decided to yank this page from
1339  * the cache and to make it a part of a transfer.
1340  *
1341  * \pre  pg->cp_state == CPS_CACHED
1342  * \post pg->cp_state == CPS_PAGEIN || pg->cp_state == CPS_PAGEOUT
1343  *
1344  * \see cl_page_operations::cpo_make_ready()
1345  */
1346 int cl_page_make_ready(const struct lu_env *env, struct cl_page *pg,
1347                        enum cl_req_type crt)
1348 {
1349         int result;
1350
1351         PINVRNT(env, pg, crt < CRT_NR);
1352
1353         ENTRY;
1354         result = CL_PAGE_INVOKE(env, pg, CL_PAGE_OP(io[crt].cpo_make_ready),
1355                                 (const struct lu_env *,
1356                                  const struct cl_page_slice *));
1357         if (result == 0) {
1358                 PASSERT(env, pg, pg->cp_state == CPS_CACHED);
1359                 cl_page_io_start(env, pg, crt);
1360         }
1361         CL_PAGE_HEADER(D_TRACE, env, pg, "%d %d\n", crt, result);
1362         RETURN(result);
1363 }
1364 EXPORT_SYMBOL(cl_page_make_ready);
1365
1366 /**
1367  * Notify layers that high level io decided to place this page into a cache
1368  * for future transfer.
1369  *
1370  * The layer implementing transfer engine (osc) has to register this page in
1371  * its queues.
1372  *
1373  * \pre  cl_page_is_owned(pg, io)
1374  * \post cl_page_is_owned(pg, io)
1375  *
1376  * \see cl_page_operations::cpo_cache_add()
1377  */
1378 int cl_page_cache_add(const struct lu_env *env, struct cl_io *io,
1379                       struct cl_page *pg, enum cl_req_type crt)
1380 {
1381         const struct cl_page_slice *scan;
1382         int result = 0;
1383
1384         PINVRNT(env, pg, crt < CRT_NR);
1385         PINVRNT(env, pg, cl_page_is_owned(pg, io));
1386         PINVRNT(env, pg, cl_page_invariant(pg));
1387
1388         ENTRY;
1389
1390         cfs_list_for_each_entry(scan, &pg->cp_layers, cpl_linkage) {
1391                 if (scan->cpl_ops->io[crt].cpo_cache_add == NULL)
1392                         continue;
1393
1394                 result = scan->cpl_ops->io[crt].cpo_cache_add(env, scan, io);
1395                 if (result != 0)
1396                         break;
1397         }
1398         CL_PAGE_HEADER(D_TRACE, env, pg, "%d %d\n", crt, result);
1399         RETURN(result);
1400 }
1401 EXPORT_SYMBOL(cl_page_cache_add);
1402
1403 /**
1404  * Called if a pge is being written back by kernel's intention.
1405  *
1406  * \pre  cl_page_is_owned(pg, io)
1407  * \post ergo(result == 0, pg->cp_state == CPS_PAGEOUT)
1408  *
1409  * \see cl_page_operations::cpo_flush()
1410  */
1411 int cl_page_flush(const struct lu_env *env, struct cl_io *io,
1412                   struct cl_page *pg)
1413 {
1414         int result;
1415
1416         PINVRNT(env, pg, cl_page_is_owned(pg, io));
1417         PINVRNT(env, pg, cl_page_invariant(pg));
1418
1419         ENTRY;
1420
1421         result = cl_page_invoke(env, io, pg, CL_PAGE_OP(cpo_flush));
1422
1423         CL_PAGE_HEADER(D_TRACE, env, pg, "%d\n", result);
1424         RETURN(result);
1425 }
1426 EXPORT_SYMBOL(cl_page_flush);
1427
1428 /**
1429  * Checks whether page is protected by any extent lock is at least required
1430  * mode.
1431  *
1432  * \return the same as in cl_page_operations::cpo_is_under_lock() method.
1433  * \see cl_page_operations::cpo_is_under_lock()
1434  */
1435 int cl_page_is_under_lock(const struct lu_env *env, struct cl_io *io,
1436                           struct cl_page *page)
1437 {
1438         int rc;
1439
1440         PINVRNT(env, page, cl_page_invariant(page));
1441
1442         ENTRY;
1443         rc = CL_PAGE_INVOKE(env, page, CL_PAGE_OP(cpo_is_under_lock),
1444                             (const struct lu_env *,
1445                              const struct cl_page_slice *, struct cl_io *),
1446                             io);
1447         PASSERT(env, page, rc != 0);
1448         RETURN(rc);
1449 }
1450 EXPORT_SYMBOL(cl_page_is_under_lock);
1451
1452 static int page_prune_cb(const struct lu_env *env, struct cl_io *io,
1453                          struct cl_page *page, void *cbdata)
1454 {
1455         cl_page_own(env, io, page);
1456         cl_page_unmap(env, io, page);
1457         cl_page_discard(env, io, page);
1458         cl_page_disown(env, io, page);
1459         return CLP_GANG_OKAY;
1460 }
1461
1462 /**
1463  * Purges all cached pages belonging to the object \a obj.
1464  */
1465 int cl_pages_prune(const struct lu_env *env, struct cl_object *clobj)
1466 {
1467         struct cl_thread_info   *info;
1468         struct cl_object        *obj = cl_object_top(clobj);
1469         struct cl_io            *io;
1470         int                      result;
1471
1472         ENTRY;
1473         info  = cl_env_info(env);
1474         io    = &info->clt_io;
1475
1476         /*
1477          * initialize the io. This is ugly since we never do IO in this
1478          * function, we just make cl_page_list functions happy. -jay
1479          */
1480         io->ci_obj = obj;
1481         io->ci_ignore_layout = 1;
1482         result = cl_io_init(env, io, CIT_MISC, obj);
1483         if (result != 0) {
1484                 cl_io_fini(env, io);
1485                 RETURN(io->ci_result);
1486         }
1487
1488         do {
1489                 result = cl_page_gang_lookup(env, obj, io, 0, CL_PAGE_EOF,
1490                                              page_prune_cb, NULL);
1491                 if (result == CLP_GANG_RESCHED)
1492                         cfs_cond_resched();
1493         } while (result != CLP_GANG_OKAY);
1494
1495         cl_io_fini(env, io);
1496         RETURN(result);
1497 }
1498 EXPORT_SYMBOL(cl_pages_prune);
1499
1500 /**
1501  * Tells transfer engine that only part of a page is to be transmitted.
1502  *
1503  * \see cl_page_operations::cpo_clip()
1504  */
1505 void cl_page_clip(const struct lu_env *env, struct cl_page *pg,
1506                   int from, int to)
1507 {
1508         PINVRNT(env, pg, cl_page_invariant(pg));
1509
1510         CL_PAGE_HEADER(D_TRACE, env, pg, "%d %d\n", from, to);
1511         CL_PAGE_INVOID(env, pg, CL_PAGE_OP(cpo_clip),
1512                        (const struct lu_env *,
1513                         const struct cl_page_slice *,int, int),
1514                        from, to);
1515 }
1516 EXPORT_SYMBOL(cl_page_clip);
1517
1518 /**
1519  * Prints human readable representation of \a pg to the \a f.
1520  */
1521 void cl_page_header_print(const struct lu_env *env, void *cookie,
1522                           lu_printer_t printer, const struct cl_page *pg)
1523 {
1524         (*printer)(env, cookie,
1525                    "page@%p[%d %p:%lu ^%p_%p %d %d %d %p %p %#x]\n",
1526                    pg, cfs_atomic_read(&pg->cp_ref), pg->cp_obj,
1527                    pg->cp_index, pg->cp_parent, pg->cp_child,
1528                    pg->cp_state, pg->cp_error, pg->cp_type,
1529                    pg->cp_owner, pg->cp_req, pg->cp_flags);
1530 }
1531 EXPORT_SYMBOL(cl_page_header_print);
1532
1533 /**
1534  * Prints human readable representation of \a pg to the \a f.
1535  */
1536 void cl_page_print(const struct lu_env *env, void *cookie,
1537                    lu_printer_t printer, const struct cl_page *pg)
1538 {
1539         struct cl_page *scan;
1540
1541         for (scan = cl_page_top((struct cl_page *)pg);
1542              scan != NULL; scan = scan->cp_child)
1543                 cl_page_header_print(env, cookie, printer, scan);
1544         CL_PAGE_INVOKE(env, (struct cl_page *)pg, CL_PAGE_OP(cpo_print),
1545                        (const struct lu_env *env,
1546                         const struct cl_page_slice *slice,
1547                         void *cookie, lu_printer_t p), cookie, printer);
1548         (*printer)(env, cookie, "end page@%p\n", pg);
1549 }
1550 EXPORT_SYMBOL(cl_page_print);
1551
1552 /**
1553  * Cancel a page which is still in a transfer.
1554  */
1555 int cl_page_cancel(const struct lu_env *env, struct cl_page *page)
1556 {
1557         return CL_PAGE_INVOKE(env, page, CL_PAGE_OP(cpo_cancel),
1558                               (const struct lu_env *,
1559                                const struct cl_page_slice *));
1560 }
1561 EXPORT_SYMBOL(cl_page_cancel);
1562
1563 /**
1564  * Converts a byte offset within object \a obj into a page index.
1565  */
1566 loff_t cl_offset(const struct cl_object *obj, pgoff_t idx)
1567 {
1568         /*
1569          * XXX for now.
1570          */
1571         return (loff_t)idx << CFS_PAGE_SHIFT;
1572 }
1573 EXPORT_SYMBOL(cl_offset);
1574
1575 /**
1576  * Converts a page index into a byte offset within object \a obj.
1577  */
1578 pgoff_t cl_index(const struct cl_object *obj, loff_t offset)
1579 {
1580         /*
1581          * XXX for now.
1582          */
1583         return offset >> CFS_PAGE_SHIFT;
1584 }
1585 EXPORT_SYMBOL(cl_index);
1586
1587 int cl_page_size(const struct cl_object *obj)
1588 {
1589         return 1 << CFS_PAGE_SHIFT;
1590 }
1591 EXPORT_SYMBOL(cl_page_size);
1592
1593 /**
1594  * Adds page slice to the compound page.
1595  *
1596  * This is called by cl_object_operations::coo_page_init() methods to add a
1597  * per-layer state to the page. New state is added at the end of
1598  * cl_page::cp_layers list, that is, it is at the bottom of the stack.
1599  *
1600  * \see cl_lock_slice_add(), cl_req_slice_add(), cl_io_slice_add()
1601  */
1602 void cl_page_slice_add(struct cl_page *page, struct cl_page_slice *slice,
1603                        struct cl_object *obj,
1604                        const struct cl_page_operations *ops)
1605 {
1606         ENTRY;
1607         cfs_list_add_tail(&slice->cpl_linkage, &page->cp_layers);
1608         slice->cpl_obj  = obj;
1609         slice->cpl_ops  = ops;
1610         slice->cpl_page = page;
1611         EXIT;
1612 }
1613 EXPORT_SYMBOL(cl_page_slice_add);
1614
1615 int  cl_page_init(void)
1616 {
1617         return 0;
1618 }
1619
1620 void cl_page_fini(void)
1621 {
1622 }