lustre/osc/osc_cache.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) 2012, 2013, Intel Corporation.
  31  *
  32  */
  33 /*
  34  * This file is part of Lustre, http://www.lustre.org/
  35  * Lustre is a trademark of Sun Microsystems, Inc.
  36  *
  37  * osc cache management.
  38  *
  39  * Author: Jinshan Xiong <jinshan.xiong@whamcloud.com>
  40  */
  41
  42 #define DEBUG_SUBSYSTEM S_OSC
  43
  44 #include "osc_cl_internal.h"
  45 #include "osc_internal.h"
  46
  47 static int extent_debug; /* set it to be true for more debug */
  48
  49 static void osc_update_pending(struct osc_object *obj, int cmd, int delta);
  50 static int osc_extent_wait(const struct lu_env *env, struct osc_extent *ext,
  51                            int state);
  52 static void osc_ap_completion(const struct lu_env *env, struct client_obd *cli,
  53                               struct osc_async_page *oap, int sent, int rc);
  54 static int osc_make_ready(const struct lu_env *env, struct osc_async_page *oap,
  55                           int cmd);
  56 static int osc_refresh_count(const struct lu_env *env,
  57                              struct osc_async_page *oap, int cmd);
  58 static int osc_io_unplug_async(const struct lu_env *env,
  59                                struct client_obd *cli, struct osc_object *osc);
  60 static void osc_free_grant(struct client_obd *cli, unsigned int nr_pages,
  61                            unsigned int lost_grant);
  62
  63 static void osc_extent_tree_dump0(int level, struct osc_object *obj,
  64                                   const char *func, int line);
  65 #define osc_extent_tree_dump(lvl, obj) \
  66         osc_extent_tree_dump0(lvl, obj, __func__, __LINE__)
  67
  68 /** \addtogroup osc
  69  *  @{
  70  */
  71
  72 /* ------------------ osc extent ------------------ */
  73 static inline char *ext_flags(struct osc_extent *ext, char *flags)
  74 {
  75         char *buf = flags;
  76         *buf++ = ext->oe_rw ? 'r' : 'w';
  77         if (ext->oe_intree)
  78                 *buf++ = 'i';
  79         if (ext->oe_srvlock)
  80                 *buf++ = 's';
  81         if (ext->oe_hp)
  82                 *buf++ = 'h';
  83         if (ext->oe_urgent)
  84                 *buf++ = 'u';
  85         if (ext->oe_memalloc)
  86                 *buf++ = 'm';
  87         if (ext->oe_trunc_pending)
  88                 *buf++ = 't';
  89         if (ext->oe_fsync_wait)
  90                 *buf++ = 'Y';
  91         *buf = 0;
  92         return flags;
  93 }
  94
  95 static inline char list_empty_marker(cfs_list_t *list)
  96 {
  97         return cfs_list_empty(list) ? '-' : '+';
  98 }
  99
 100 #define EXTSTR       "[%lu -> %lu/%lu]"
 101 #define EXTPARA(ext) (ext)->oe_start, (ext)->oe_end, (ext)->oe_max_end
 102 static const char *oes_strings[] = {
 103         "inv", "active", "cache", "locking", "lockdone", "rpc", "trunc", NULL };
 104
 105 #define OSC_EXTENT_DUMP(lvl, extent, fmt, ...) do {                           \
 106         struct osc_extent *__ext = (extent);                                  \
 107         char __buf[16];                                                       \
 108                                                                               \
 109         CDEBUG(lvl,                                                           \
 110                 "extent %p@{" EXTSTR ", "                                     \
 111                 "[%d|%d|%c|%s|%s|%p], [%d|%d|%c|%c|%p|%u|%p]} " fmt,          \
 112                 /* ----- extent part 0 ----- */                               \
 113                 __ext, EXTPARA(__ext),                                        \
 114                 /* ----- part 1 ----- */                                      \
 115                 cfs_atomic_read(&__ext->oe_refc),                             \
 116                 cfs_atomic_read(&__ext->oe_users),                            \
 117                 list_empty_marker(&__ext->oe_link),                           \
 118                 oes_strings[__ext->oe_state], ext_flags(__ext, __buf),        \
 119                 __ext->oe_obj,                                                \
 120                 /* ----- part 2 ----- */                                      \
 121                 __ext->oe_grants, __ext->oe_nr_pages,                         \
 122                 list_empty_marker(&__ext->oe_pages),                          \
 123                 cfs_waitq_active(&__ext->oe_waitq) ? '+' : '-',               \
 124                 __ext->oe_osclock, __ext->oe_mppr, __ext->oe_owner,           \
 125                 /* ----- part 4 ----- */                                      \
 126                 ## __VA_ARGS__);                                              \
 127 } while (0)
 128
 129 #undef EASSERTF
 130 #define EASSERTF(expr, ext, fmt, args...) do {                          \
 131         if (!(expr)) {                                                  \
 132                 OSC_EXTENT_DUMP(D_ERROR, (ext), fmt, ##args);           \
 133                 osc_extent_tree_dump(D_ERROR, (ext)->oe_obj);           \
 134                 LASSERT(expr);                                          \
 135         }                                                               \
 136 } while (0)
 137
 138 #undef EASSERT
 139 #define EASSERT(expr, ext) EASSERTF(expr, ext, "\n")
 140
 141 static inline struct osc_extent *rb_extent(struct rb_node *n)
 142 {
 143         if (n == NULL)
 144                 return NULL;
 145
 146         return container_of(n, struct osc_extent, oe_node);
 147 }
 148
 149 static inline struct osc_extent *next_extent(struct osc_extent *ext)
 150 {
 151         if (ext == NULL)
 152                 return NULL;
 153
 154         LASSERT(ext->oe_intree);
 155         return rb_extent(rb_next(&ext->oe_node));
 156 }
 157
 158 static inline struct osc_extent *prev_extent(struct osc_extent *ext)
 159 {
 160         if (ext == NULL)
 161                 return NULL;
 162
 163         LASSERT(ext->oe_intree);
 164         return rb_extent(rb_prev(&ext->oe_node));
 165 }
 166
 167 static inline struct osc_extent *first_extent(struct osc_object *obj)
 168 {
 169         return rb_extent(rb_first(&obj->oo_root));
 170 }
 171
 172 /* object must be locked by caller. */
 173 static int osc_extent_sanity_check0(struct osc_extent *ext,
 174                                     const char *func, const int line)
 175 {
 176         struct osc_object *obj = ext->oe_obj;
 177         struct osc_async_page *oap;
 178         int page_count;
 179         int rc = 0;
 180
 181         if (!osc_object_is_locked(obj))
 182                 GOTO(out, rc = 9);
 183
 184         if (ext->oe_state >= OES_STATE_MAX)
 185                 GOTO(out, rc = 10);
 186
 187         if (cfs_atomic_read(&ext->oe_refc) <= 0)
 188                 GOTO(out, rc = 20);
 189
 190         if (cfs_atomic_read(&ext->oe_refc) < cfs_atomic_read(&ext->oe_users))
 191                 GOTO(out, rc = 30);
 192
 193         switch (ext->oe_state) {
 194         case OES_INV:
 195                 if (ext->oe_nr_pages > 0 || !cfs_list_empty(&ext->oe_pages))
 196                         GOTO(out, rc = 35);
 197                 GOTO(out, rc = 0);
 198                 break;
 199         case OES_ACTIVE:
 200                 if (cfs_atomic_read(&ext->oe_users) == 0)
 201                         GOTO(out, rc = 40);
 202                 if (ext->oe_hp)
 203                         GOTO(out, rc = 50);
 204                 if (ext->oe_fsync_wait && !ext->oe_urgent)
 205                         GOTO(out, rc = 55);
 206                 break;
 207         case OES_CACHE:
 208                 if (ext->oe_grants == 0)
 209                         GOTO(out, rc = 60);
 210                 if (ext->oe_fsync_wait && !ext->oe_urgent && !ext->oe_hp)
 211                         GOTO(out, rc = 65);
 212         default:
 213                 if (cfs_atomic_read(&ext->oe_users) > 0)
 214                         GOTO(out, rc = 70);
 215         }
 216
 217         if (ext->oe_max_end < ext->oe_end || ext->oe_end < ext->oe_start)
 218                 GOTO(out, rc = 80);
 219
 220         if (ext->oe_osclock == NULL && ext->oe_grants > 0)
 221                 GOTO(out, rc = 90);
 222
 223         if (ext->oe_osclock) {
 224                 struct cl_lock_descr *descr;
 225                 descr = &ext->oe_osclock->cll_descr;
 226                 if (!(descr->cld_start <= ext->oe_start &&
 227                       descr->cld_end >= ext->oe_max_end))
 228                         GOTO(out, rc = 100);
 229         }
 230
 231         if (ext->oe_nr_pages > ext->oe_mppr)
 232                 GOTO(out, rc = 105);
 233
 234         /* Do not verify page list if extent is in RPC. This is because an
 235          * in-RPC extent is supposed to be exclusively accessible w/o lock. */
 236         if (ext->oe_state > OES_CACHE)
 237                 GOTO(out, rc = 0);
 238
 239         if (!extent_debug)
 240                 GOTO(out, rc = 0);
 241
 242         page_count = 0;
 243         cfs_list_for_each_entry(oap, &ext->oe_pages, oap_pending_item) {
 244                 pgoff_t index = oap2cl_page(oap)->cp_index;
 245                 ++page_count;
 246                 if (index > ext->oe_end || index < ext->oe_start)
 247                         GOTO(out, rc = 110);
 248         }
 249         if (page_count != ext->oe_nr_pages)
 250                 GOTO(out, rc = 120);
 251
 252 out:
 253         if (rc != 0)
 254                 OSC_EXTENT_DUMP(D_ERROR, ext,
 255                                 "%s:%d sanity check %p failed with rc = %d\n",
 256                                 func, line, ext, rc);
 257         return rc;
 258 }
 259
 260 #define sanity_check_nolock(ext) \
 261         osc_extent_sanity_check0(ext, __func__, __LINE__)
 262
 263 #define sanity_check(ext) ({                                                   \
 264         int __res;                                                             \
 265         osc_object_lock((ext)->oe_obj);                                        \
 266         __res = sanity_check_nolock(ext);                                      \
 267         osc_object_unlock((ext)->oe_obj);                                      \
 268         __res;                                                                 \
 269 })
 270
 271
 272 /**
 273  * sanity check - to make sure there is no overlapped extent in the tree.
 274  */
 275 static int osc_extent_is_overlapped(struct osc_object *obj,
 276                                     struct osc_extent *ext)
 277 {
 278         struct osc_extent *tmp;
 279
 280         LASSERT(osc_object_is_locked(obj));
 281
 282         if (!extent_debug)
 283                 return 0;
 284
 285         for (tmp = first_extent(obj); tmp != NULL; tmp = next_extent(tmp)) {
 286                 if (tmp == ext)
 287                         continue;
 288                 if (tmp->oe_end >= ext->oe_start &&
 289                     tmp->oe_start <= ext->oe_end)
 290                         return 1;
 291         }
 292         return 0;
 293 }
 294
 295 static void osc_extent_state_set(struct osc_extent *ext, int state)
 296 {
 297         LASSERT(osc_object_is_locked(ext->oe_obj));
 298         LASSERT(state >= OES_INV && state < OES_STATE_MAX);
 299
 300         /* Never try to sanity check a state changing extent :-) */
 301         /* LASSERT(sanity_check_nolock(ext) == 0); */
 302
 303         /* TODO: validate the state machine */
 304         ext->oe_state = state;
 305         cfs_waitq_broadcast(&ext->oe_waitq);
 306 }
 307
 308 static struct osc_extent *osc_extent_alloc(struct osc_object *obj)
 309 {
 310         struct osc_extent *ext;
 311
 312         OBD_SLAB_ALLOC_PTR_GFP(ext, osc_extent_kmem, GFP_IOFS);
 313         if (ext == NULL)
 314                 return NULL;
 315
 316         RB_CLEAR_NODE(&ext->oe_node);
 317         ext->oe_obj = obj;
 318         cfs_atomic_set(&ext->oe_refc, 1);
 319         cfs_atomic_set(&ext->oe_users, 0);
 320         CFS_INIT_LIST_HEAD(&ext->oe_link);
 321         ext->oe_state = OES_INV;
 322         CFS_INIT_LIST_HEAD(&ext->oe_pages);
 323         cfs_waitq_init(&ext->oe_waitq);
 324         ext->oe_osclock = NULL;
 325
 326         return ext;
 327 }
 328
 329 static void osc_extent_free(struct osc_extent *ext)
 330 {
 331         OBD_SLAB_FREE_PTR(ext, osc_extent_kmem);
 332 }
 333
 334 static struct osc_extent *osc_extent_get(struct osc_extent *ext)
 335 {
 336         LASSERT(cfs_atomic_read(&ext->oe_refc) >= 0);
 337         cfs_atomic_inc(&ext->oe_refc);
 338         return ext;
 339 }
 340
 341 static void osc_extent_put(const struct lu_env *env, struct osc_extent *ext)
 342 {
 343         LASSERT(cfs_atomic_read(&ext->oe_refc) > 0);
 344         if (cfs_atomic_dec_and_test(&ext->oe_refc)) {
 345                 LASSERT(cfs_list_empty(&ext->oe_link));
 346                 LASSERT(cfs_atomic_read(&ext->oe_users) == 0);
 347                 LASSERT(ext->oe_state == OES_INV);
 348                 LASSERT(!ext->oe_intree);
 349
 350                 if (ext->oe_osclock) {
 351                         cl_lock_put(env, ext->oe_osclock);
 352                         ext->oe_osclock = NULL;
 353                 }
 354                 osc_extent_free(ext);
 355         }
 356 }
 357
 358 /**
 359  * osc_extent_put_trust() is a special version of osc_extent_put() when
 360  * it's known that the caller is not the last user. This is to address the
 361  * problem of lacking of lu_env ;-).
 362  */
 363 static void osc_extent_put_trust(struct osc_extent *ext)
 364 {
 365         LASSERT(cfs_atomic_read(&ext->oe_refc) > 1);
 366         LASSERT(osc_object_is_locked(ext->oe_obj));
 367         cfs_atomic_dec(&ext->oe_refc);
 368 }
 369
 370 /**
 371  * Return the extent which includes pgoff @index, or return the greatest
 372  * previous extent in the tree.
 373  */
 374 static struct osc_extent *osc_extent_search(struct osc_object *obj,
 375                                             pgoff_t index)
 376 {
 377         struct rb_node    *n = obj->oo_root.rb_node;
 378         struct osc_extent *tmp, *p = NULL;
 379
 380         LASSERT(osc_object_is_locked(obj));
 381         while (n != NULL) {
 382                 tmp = rb_extent(n);
 383                 if (index < tmp->oe_start) {
 384                         n = n->rb_left;
 385                 } else if (index > tmp->oe_end) {
 386                         p = rb_extent(n);
 387                         n = n->rb_right;
 388                 } else {
 389                         return tmp;
 390                 }
 391         }
 392         return p;
 393 }
 394
 395 /*
 396  * Return the extent covering @index, otherwise return NULL.
 397  * caller must have held object lock.
 398  */
 399 static struct osc_extent *osc_extent_lookup(struct osc_object *obj,
 400                                             pgoff_t index)
 401 {
 402         struct osc_extent *ext;
 403
 404         ext = osc_extent_search(obj, index);
 405         if (ext != NULL && ext->oe_start <= index && index <= ext->oe_end)
 406                 return osc_extent_get(ext);
 407         return NULL;
 408 }
 409
 410 /* caller must have held object lock. */
 411 static void osc_extent_insert(struct osc_object *obj, struct osc_extent *ext)
 412 {
 413         struct rb_node   **n      = &obj->oo_root.rb_node;
 414         struct rb_node    *parent = NULL;
 415         struct osc_extent *tmp;
 416
 417         LASSERT(ext->oe_intree == 0);
 418         LASSERT(ext->oe_obj == obj);
 419         LASSERT(osc_object_is_locked(obj));
 420         while (*n != NULL) {
 421                 tmp = rb_extent(*n);
 422                 parent = *n;
 423
 424                 if (ext->oe_end < tmp->oe_start)
 425                         n = &(*n)->rb_left;
 426                 else if (ext->oe_start > tmp->oe_end)
 427                         n = &(*n)->rb_right;
 428                 else
 429                         EASSERTF(0, tmp, EXTSTR, EXTPARA(ext));
 430         }
 431         rb_link_node(&ext->oe_node, parent, n);
 432         rb_insert_color(&ext->oe_node, &obj->oo_root);
 433         osc_extent_get(ext);
 434         ext->oe_intree = 1;
 435 }
 436
 437 /* caller must have held object lock. */
 438 static void osc_extent_erase(struct osc_extent *ext)
 439 {
 440         struct osc_object *obj = ext->oe_obj;
 441         LASSERT(osc_object_is_locked(obj));
 442         if (ext->oe_intree) {
 443                 rb_erase(&ext->oe_node, &obj->oo_root);
 444                 ext->oe_intree = 0;
 445                 /* rbtree held a refcount */
 446                 osc_extent_put_trust(ext);
 447         }
 448 }
 449
 450 static struct osc_extent *osc_extent_hold(struct osc_extent *ext)
 451 {
 452         struct osc_object *obj = ext->oe_obj;
 453
 454         LASSERT(osc_object_is_locked(obj));
 455         LASSERT(ext->oe_state == OES_ACTIVE || ext->oe_state == OES_CACHE);
 456         if (ext->oe_state == OES_CACHE) {
 457                 osc_extent_state_set(ext, OES_ACTIVE);
 458                 osc_update_pending(obj, OBD_BRW_WRITE, -ext->oe_nr_pages);
 459         }
 460         cfs_atomic_inc(&ext->oe_users);
 461         cfs_list_del_init(&ext->oe_link);
 462         return osc_extent_get(ext);
 463 }
 464
 465 static void __osc_extent_remove(struct osc_extent *ext)
 466 {
 467         LASSERT(osc_object_is_locked(ext->oe_obj));
 468         LASSERT(cfs_list_empty(&ext->oe_pages));
 469         osc_extent_erase(ext);
 470         cfs_list_del_init(&ext->oe_link);
 471         osc_extent_state_set(ext, OES_INV);
 472         OSC_EXTENT_DUMP(D_CACHE, ext, "destroyed.\n");
 473 }
 474
 475 static void osc_extent_remove(struct osc_extent *ext)
 476 {
 477         struct osc_object *obj = ext->oe_obj;
 478
 479         osc_object_lock(obj);
 480         __osc_extent_remove(ext);
 481         osc_object_unlock(obj);
 482 }
 483
 484 /**
 485  * This function is used to merge extents to get better performance. It checks
 486  * if @cur and @victim are contiguous at chunk level.
 487  */
 488 static int osc_extent_merge(const struct lu_env *env, struct osc_extent *cur,
 489                             struct osc_extent *victim)
 490 {
 491         struct osc_object *obj = cur->oe_obj;
 492         pgoff_t chunk_start;
 493         pgoff_t chunk_end;
 494         int ppc_bits;
 495
 496         LASSERT(cur->oe_state == OES_CACHE);
 497         LASSERT(osc_object_is_locked(obj));
 498         if (victim == NULL)
 499                 return -EINVAL;
 500
 501         if (victim->oe_state != OES_CACHE || victim->oe_fsync_wait)
 502                 return -EBUSY;
 503
 504         if (cur->oe_max_end != victim->oe_max_end)
 505                 return -ERANGE;
 506
 507         LASSERT(cur->oe_osclock == victim->oe_osclock);
 508         ppc_bits = osc_cli(obj)->cl_chunkbits - PAGE_CACHE_SHIFT;
 509         chunk_start = cur->oe_start >> ppc_bits;
 510         chunk_end   = cur->oe_end   >> ppc_bits;
 511         if (chunk_start   != (victim->oe_end >> ppc_bits) + 1 &&
 512             chunk_end + 1 != victim->oe_start >> ppc_bits)
 513                 return -ERANGE;
 514
 515         OSC_EXTENT_DUMP(D_CACHE, victim, "will be merged by %p.\n", cur);
 516
 517         cur->oe_start     = min(cur->oe_start, victim->oe_start);
 518         cur->oe_end       = max(cur->oe_end,   victim->oe_end);
 519         cur->oe_grants   += victim->oe_grants;
 520         cur->oe_nr_pages += victim->oe_nr_pages;
 521         /* only the following bits are needed to merge */
 522         cur->oe_urgent   |= victim->oe_urgent;
 523         cur->oe_memalloc |= victim->oe_memalloc;
 524         cfs_list_splice_init(&victim->oe_pages, &cur->oe_pages);
 525         cfs_list_del_init(&victim->oe_link);
 526         victim->oe_nr_pages = 0;
 527
 528         osc_extent_get(victim);
 529         __osc_extent_remove(victim);
 530         osc_extent_put(env, victim);
 531
 532         OSC_EXTENT_DUMP(D_CACHE, cur, "after merging %p.\n", victim);
 533         return 0;
 534 }
 535
 536 /**
 537  * Drop user count of osc_extent, and unplug IO asynchronously.
 538  */
 539 int osc_extent_release(const struct lu_env *env, struct osc_extent *ext)
 540 {
 541         struct osc_object *obj = ext->oe_obj;
 542         int rc = 0;
 543         ENTRY;
 544
 545         LASSERT(cfs_atomic_read(&ext->oe_users) > 0);
 546         LASSERT(sanity_check(ext) == 0);
 547         LASSERT(ext->oe_grants > 0);
 548
 549         if (cfs_atomic_dec_and_lock(&ext->oe_users, &obj->oo_lock)) {
 550                 LASSERT(ext->oe_state == OES_ACTIVE);
 551                 if (ext->oe_trunc_pending) {
 552                         /* a truncate process is waiting for this extent.
 553                          * This may happen due to a race, check
 554                          * osc_cache_truncate_start(). */
 555                         osc_extent_state_set(ext, OES_TRUNC);
 556                         ext->oe_trunc_pending = 0;
 557                 } else {
 558                         osc_extent_state_set(ext, OES_CACHE);
 559                         osc_update_pending(obj, OBD_BRW_WRITE,
 560                                            ext->oe_nr_pages);
 561
 562                         /* try to merge the previous and next extent. */
 563                         osc_extent_merge(env, ext, prev_extent(ext));
 564                         osc_extent_merge(env, ext, next_extent(ext));
 565
 566                         if (ext->oe_urgent)
 567                                 cfs_list_move_tail(&ext->oe_link,
 568                                                    &obj->oo_urgent_exts);
 569                 }
 570                 osc_object_unlock(obj);
 571
 572                 osc_io_unplug_async(env, osc_cli(obj), obj);
 573         }
 574         osc_extent_put(env, ext);
 575         RETURN(rc);
 576 }
 577
 578 static inline int overlapped(struct osc_extent *ex1, struct osc_extent *ex2)
 579 {
 580         return !(ex1->oe_end < ex2->oe_start || ex2->oe_end < ex1->oe_start);
 581 }
 582
 583 /**
 584  * Find or create an extent which includes @index, core function to manage
 585  * extent tree.
 586  */
 587 struct osc_extent *osc_extent_find(const struct lu_env *env,
 588                                    struct osc_object *obj, pgoff_t index,
 589                                    int *grants)
 590
 591 {
 592         struct client_obd *cli = osc_cli(obj);
 593         struct cl_lock    *lock;
 594         struct osc_extent *cur;
 595         struct osc_extent *ext;
 596         struct osc_extent *conflict = NULL;
 597         struct osc_extent *found = NULL;
 598         pgoff_t    chunk;
 599         pgoff_t    max_end;
 600         int        max_pages; /* max_pages_per_rpc */
 601         int        chunksize;
 602         int        ppc_bits; /* pages per chunk bits */
 603         int        chunk_mask;
 604         int        rc;
 605         ENTRY;
 606
 607         cur = osc_extent_alloc(obj);
 608         if (cur == NULL)
 609                 RETURN(ERR_PTR(-ENOMEM));
 610
 611         lock = cl_lock_at_pgoff(env, osc2cl(obj), index, NULL, 1, 0);
 612         LASSERT(lock != NULL);
 613         LASSERT(lock->cll_descr.cld_mode >= CLM_WRITE);
 614
 615         LASSERT(cli->cl_chunkbits >= PAGE_CACHE_SHIFT);
 616         ppc_bits   = cli->cl_chunkbits - PAGE_CACHE_SHIFT;
 617         chunk_mask = ~((1 << ppc_bits) - 1);
 618         chunksize  = 1 << cli->cl_chunkbits;
 619         chunk      = index >> ppc_bits;
 620
 621         /* align end to rpc edge, rpc size may not be a power 2 integer. */
 622         max_pages = cli->cl_max_pages_per_rpc;
 623         LASSERT((max_pages & ~chunk_mask) == 0);
 624         max_end = index - (index % max_pages) + max_pages - 1;
 625         max_end = min_t(pgoff_t, max_end, lock->cll_descr.cld_end);
 626
 627         /* initialize new extent by parameters so far */
 628         cur->oe_max_end = max_end;
 629         cur->oe_start   = index & chunk_mask;
 630         cur->oe_end     = ((index + ~chunk_mask + 1) & chunk_mask) - 1;
 631         if (cur->oe_start < lock->cll_descr.cld_start)
 632                 cur->oe_start = lock->cll_descr.cld_start;
 633         if (cur->oe_end > max_end)
 634                 cur->oe_end = max_end;
 635         cur->oe_osclock = lock;
 636         cur->oe_grants  = 0;
 637         cur->oe_mppr    = max_pages;
 638
 639         /* grants has been allocated by caller */
 640         LASSERTF(*grants >= chunksize + cli->cl_extent_tax,
 641                  "%u/%u/%u.\n", *grants, chunksize, cli->cl_extent_tax);
 642         LASSERTF((max_end - cur->oe_start) < max_pages, EXTSTR, EXTPARA(cur));
 643
 644 restart:
 645         osc_object_lock(obj);
 646         ext = osc_extent_search(obj, cur->oe_start);
 647         if (ext == NULL)
 648                 ext = first_extent(obj);
 649         while (ext != NULL) {
 650                 loff_t ext_chk_start = ext->oe_start >> ppc_bits;
 651                 loff_t ext_chk_end   = ext->oe_end   >> ppc_bits;
 652
 653                 LASSERT(sanity_check_nolock(ext) == 0);
 654                 if (chunk > ext_chk_end + 1)
 655                         break;
 656
 657                 /* if covering by different locks, no chance to match */
 658                 if (lock != ext->oe_osclock) {
 659                         EASSERTF(!overlapped(ext, cur), ext,
 660                                  EXTSTR, EXTPARA(cur));
 661
 662                         ext = next_extent(ext);
 663                         continue;
 664                 }
 665
 666                 /* discontiguous chunks? */
 667                 if (chunk + 1 < ext_chk_start) {
 668                         ext = next_extent(ext);
 669                         continue;
 670                 }
 671
 672                 /* ok, from now on, ext and cur have these attrs:
 673                  * 1. covered by the same lock
 674                  * 2. contiguous at chunk level or overlapping. */
 675
 676                 if (overlapped(ext, cur)) {
 677                         /* cur is the minimum unit, so overlapping means
 678                          * full contain. */
 679                         EASSERTF((ext->oe_start <= cur->oe_start &&
 680                                   ext->oe_end >= cur->oe_end),
 681                                  ext, EXTSTR, EXTPARA(cur));
 682
 683                         if (ext->oe_state > OES_CACHE || ext->oe_fsync_wait) {
 684                                 /* for simplicity, we wait for this extent to
 685                                  * finish before going forward. */
 686                                 conflict = osc_extent_get(ext);
 687                                 break;
 688                         }
 689
 690                         found = osc_extent_hold(ext);
 691                         break;
 692                 }
 693
 694                 /* non-overlapped extent */
 695                 if (ext->oe_state != OES_CACHE || ext->oe_fsync_wait) {
 696                         /* we can't do anything for a non OES_CACHE extent, or
 697                          * if there is someone waiting for this extent to be
 698                          * flushed, try next one. */
 699                         ext = next_extent(ext);
 700                         continue;
 701                 }
 702
 703                 /* check if they belong to the same rpc slot before trying to
 704                  * merge. the extents are not overlapped and contiguous at
 705                  * chunk level to get here. */
 706                 if (ext->oe_max_end != max_end) {
 707                         /* if they don't belong to the same RPC slot or
 708                          * max_pages_per_rpc has ever changed, do not merge. */
 709                         ext = next_extent(ext);
 710                         continue;
 711                 }
 712
 713                 /* it's required that an extent must be contiguous at chunk
 714                  * level so that we know the whole extent is covered by grant
 715                  * (the pages in the extent are NOT required to be contiguous).
 716                  * Otherwise, it will be too much difficult to know which
 717                  * chunks have grants allocated. */
 718
 719                 /* try to do front merge - extend ext's start */
 720                 if (chunk + 1 == ext_chk_start) {
 721                         /* ext must be chunk size aligned */
 722                         EASSERT((ext->oe_start & ~chunk_mask) == 0, ext);
 723
 724                         /* pull ext's start back to cover cur */
 725                         ext->oe_start   = cur->oe_start;
 726                         ext->oe_grants += chunksize;
 727                         *grants -= chunksize;
 728
 729                         found = osc_extent_hold(ext);
 730                 } else if (chunk == ext_chk_end + 1) {
 731                         /* rear merge */
 732                         ext->oe_end     = cur->oe_end;
 733                         ext->oe_grants += chunksize;
 734                         *grants -= chunksize;
 735
 736                         /* try to merge with the next one because we just fill
 737                          * in a gap */
 738                         if (osc_extent_merge(env, ext, next_extent(ext)) == 0)
 739                                 /* we can save extent tax from next extent */
 740                                 *grants += cli->cl_extent_tax;
 741
 742                         found = osc_extent_hold(ext);
 743                 }
 744                 if (found != NULL)
 745                         break;
 746
 747                 ext = next_extent(ext);
 748         }
 749
 750         osc_extent_tree_dump(D_CACHE, obj);
 751         if (found != NULL) {
 752                 LASSERT(conflict == NULL);
 753                 if (!IS_ERR(found)) {
 754                         LASSERT(found->oe_osclock == cur->oe_osclock);
 755                         OSC_EXTENT_DUMP(D_CACHE, found,
 756                                         "found caching ext for %lu.\n", index);
 757                 }
 758         } else if (conflict == NULL) {
 759                 /* create a new extent */
 760                 EASSERT(osc_extent_is_overlapped(obj, cur) == 0, cur);
 761                 cur->oe_grants = chunksize + cli->cl_extent_tax;
 762                 *grants -= cur->oe_grants;
 763                 LASSERT(*grants >= 0);
 764
 765                 cur->oe_state = OES_CACHE;
 766                 found = osc_extent_hold(cur);
 767                 osc_extent_insert(obj, cur);
 768                 OSC_EXTENT_DUMP(D_CACHE, cur, "add into tree %lu/%lu.\n",
 769                                 index, lock->cll_descr.cld_end);
 770         }
 771         osc_object_unlock(obj);
 772
 773         if (conflict != NULL) {
 774                 LASSERT(found == NULL);
 775
 776                 /* waiting for IO to finish. Please notice that it's impossible
 777                  * to be an OES_TRUNC extent. */
 778                 rc = osc_extent_wait(env, conflict, OES_INV);
 779                 osc_extent_put(env, conflict);
 780                 conflict = NULL;
 781                 if (rc < 0)
 782                         GOTO(out, found = ERR_PTR(rc));
 783
 784                 goto restart;
 785         }
 786         EXIT;
 787
 788 out:
 789         osc_extent_put(env, cur);
 790         LASSERT(*grants >= 0);
 791         return found;
 792 }
 793
 794 /**
 795  * Called when IO is finished to an extent.
 796  */
 797 int osc_extent_finish(const struct lu_env *env, struct osc_extent *ext,
 798                       int sent, int rc)
 799 {
 800         struct client_obd *cli = osc_cli(ext->oe_obj);
 801         struct osc_async_page *oap;
 802         struct osc_async_page *tmp;
 803         int nr_pages = ext->oe_nr_pages;
 804         int lost_grant = 0;
 805         int blocksize = cli->cl_import->imp_obd->obd_osfs.os_bsize ? : 4096;
 806         __u64 last_off = 0;
 807         int last_count = -1;
 808         ENTRY;
 809
 810         OSC_EXTENT_DUMP(D_CACHE, ext, "extent finished.\n");
 811
 812         ext->oe_rc = rc ?: ext->oe_nr_pages;
 813         EASSERT(ergo(rc == 0, ext->oe_state == OES_RPC), ext);
 814         cfs_list_for_each_entry_safe(oap, tmp, &ext->oe_pages,
 815                                      oap_pending_item) {
 816                 cfs_list_del_init(&oap->oap_rpc_item);
 817                 cfs_list_del_init(&oap->oap_pending_item);
 818                 if (last_off <= oap->oap_obj_off) {
 819                         last_off = oap->oap_obj_off;
 820                         last_count = oap->oap_count;
 821                 }
 822
 823                 --ext->oe_nr_pages;
 824                 osc_ap_completion(env, cli, oap, sent, rc);
 825         }
 826         EASSERT(ext->oe_nr_pages == 0, ext);
 827
 828         if (!sent) {
 829                 lost_grant = ext->oe_grants;
 830         } else if (blocksize < PAGE_CACHE_SIZE &&
 831                    last_count != PAGE_CACHE_SIZE) {
 832                 /* For short writes we shouldn't count parts of pages that
 833                  * span a whole chunk on the OST side, or our accounting goes
 834                  * wrong.  Should match the code in filter_grant_check. */
 835                 int offset = oap->oap_page_off & ~CFS_PAGE_MASK;
 836                 int count = oap->oap_count + (offset & (blocksize - 1));
 837                 int end = (offset + oap->oap_count) & (blocksize - 1);
 838                 if (end)
 839                         count += blocksize - end;
 840
 841                 lost_grant = PAGE_CACHE_SIZE - count;
 842         }
 843         if (ext->oe_grants > 0)
 844                 osc_free_grant(cli, nr_pages, lost_grant);
 845
 846         osc_extent_remove(ext);
 847         /* put the refcount for RPC */
 848         osc_extent_put(env, ext);
 849         RETURN(0);
 850 }
 851
 852 static int extent_wait_cb(struct osc_extent *ext, int state)
 853 {
 854         int ret;
 855
 856         osc_object_lock(ext->oe_obj);
 857         ret = ext->oe_state == state;
 858         osc_object_unlock(ext->oe_obj);
 859
 860         return ret;
 861 }
 862
 863 /**
 864  * Wait for the extent's state to become @state.
 865  */
 866 static int osc_extent_wait(const struct lu_env *env, struct osc_extent *ext,
 867                            int state)
 868 {
 869         struct osc_object *obj = ext->oe_obj;
 870         struct l_wait_info lwi = LWI_TIMEOUT_INTR(cfs_time_seconds(600), NULL,
 871                                                   LWI_ON_SIGNAL_NOOP, NULL);
 872         int rc = 0;
 873         ENTRY;
 874
 875         osc_object_lock(obj);
 876         LASSERT(sanity_check_nolock(ext) == 0);
 877         /* `Kick' this extent only if the caller is waiting for it to be
 878          * written out. */
 879         if (state == OES_INV && !ext->oe_urgent && !ext->oe_hp) {
 880                 if (ext->oe_state == OES_ACTIVE) {
 881                         ext->oe_urgent = 1;
 882                 } else if (ext->oe_state == OES_CACHE) {
 883                         ext->oe_urgent = 1;
 884                         osc_extent_hold(ext);
 885                         rc = 1;
 886                 }
 887         }
 888         osc_object_unlock(obj);
 889         if (rc == 1)
 890                 osc_extent_release(env, ext);
 891
 892         /* wait for the extent until its state becomes @state */
 893         rc = l_wait_event(ext->oe_waitq, extent_wait_cb(ext, state), &lwi);
 894         if (rc == -ETIMEDOUT) {
 895                 OSC_EXTENT_DUMP(D_ERROR, ext,
 896                         "%s: wait ext to %d timedout, recovery in progress?\n",
 897                         osc_export(obj)->exp_obd->obd_name, state);
 898
 899                 lwi = LWI_INTR(LWI_ON_SIGNAL_NOOP, NULL);
 900                 rc = l_wait_event(ext->oe_waitq, extent_wait_cb(ext, state),
 901                                   &lwi);
 902         }
 903         if (rc == 0 && ext->oe_rc < 0)
 904                 rc = ext->oe_rc;
 905         RETURN(rc);
 906 }
 907
 908 /**
 909  * Discard pages with index greater than @size. If @ext is overlapped with
 910  * @size, then partial truncate happens.
 911  */
 912 static int osc_extent_truncate(struct osc_extent *ext, pgoff_t trunc_index,
 913                                 bool partial)
 914 {
 915         struct cl_env_nest     nest;
 916         struct lu_env         *env;
 917         struct cl_io          *io;
 918         struct osc_object     *obj = ext->oe_obj;
 919         struct client_obd     *cli = osc_cli(obj);
 920         struct osc_async_page *oap;
 921         struct osc_async_page *tmp;
 922         int                    pages_in_chunk = 0;
 923         int                    ppc_bits    = cli->cl_chunkbits -
 924                                              PAGE_CACHE_SHIFT;
 925         __u64                  trunc_chunk = trunc_index >> ppc_bits;
 926         int                    grants   = 0;
 927         int                    nr_pages = 0;
 928         int                    rc       = 0;
 929         ENTRY;
 930
 931         LASSERT(sanity_check(ext) == 0);
 932         LASSERT(ext->oe_state == OES_TRUNC);
 933         LASSERT(!ext->oe_urgent);
 934
 935         /* Request new lu_env.
 936          * We can't use that env from osc_cache_truncate_start() because
 937          * it's from lov_io_sub and not fully initialized. */
 938         env = cl_env_nested_get(&nest);
 939         io  = &osc_env_info(env)->oti_io;
 940         io->ci_obj = cl_object_top(osc2cl(obj));
 941         rc = cl_io_init(env, io, CIT_MISC, io->ci_obj);
 942         if (rc < 0)
 943                 GOTO(out, rc);
 944
 945         /* discard all pages with index greater then trunc_index */
 946         cfs_list_for_each_entry_safe(oap, tmp, &ext->oe_pages,
 947                                      oap_pending_item) {
 948                 struct cl_page  *sub  = oap2cl_page(oap);
 949                 struct cl_page  *page = cl_page_top(sub);
 950
 951                 LASSERT(cfs_list_empty(&oap->oap_rpc_item));
 952
 953                 /* only discard the pages with their index greater than
 954                  * trunc_index, and ... */
 955                 if (sub->cp_index < trunc_index ||
 956                     (sub->cp_index == trunc_index && partial)) {
 957                         /* accounting how many pages remaining in the chunk
 958                          * so that we can calculate grants correctly. */
 959                         if (sub->cp_index >> ppc_bits == trunc_chunk)
 960                                 ++pages_in_chunk;
 961                         continue;
 962                 }
 963
 964                 cfs_list_del_init(&oap->oap_pending_item);
 965
 966                 cl_page_get(page);
 967                 lu_ref_add(&page->cp_reference, "truncate", cfs_current());
 968
 969                 if (cl_page_own(env, io, page) == 0) {
 970                         cl_page_unmap(env, io, page);
 971                         cl_page_discard(env, io, page);
 972                         cl_page_disown(env, io, page);
 973                 } else {
 974                         LASSERT(page->cp_state == CPS_FREEING);
 975                         LASSERT(0);
 976                 }
 977
 978                 lu_ref_del(&page->cp_reference, "truncate", cfs_current());
 979                 cl_page_put(env, page);
 980
 981                 --ext->oe_nr_pages;
 982                 ++nr_pages;
 983         }
 984         EASSERTF(ergo(ext->oe_start >= trunc_index + !!partial,
 985                       ext->oe_nr_pages == 0),
 986                 ext, "trunc_index %lu, partial %d\n", trunc_index, partial);
 987
 988         osc_object_lock(obj);
 989         if (ext->oe_nr_pages == 0) {
 990                 LASSERT(pages_in_chunk == 0);
 991                 grants = ext->oe_grants;
 992                 ext->oe_grants = 0;
 993         } else { /* calculate how many grants we can free */
 994                 int     chunks = (ext->oe_end >> ppc_bits) - trunc_chunk;
 995                 pgoff_t last_index;
 996
 997
 998                 /* if there is no pages in this chunk, we can also free grants
 999                  * for the last chunk */
1000                 if (pages_in_chunk == 0) {
1001                         /* if this is the 1st chunk and no pages in this chunk,
1002                          * ext->oe_nr_pages must be zero, so we should be in
1003                          * the other if-clause. */
1004                         LASSERT(trunc_chunk > 0);
1005                         --trunc_chunk;
1006                         ++chunks;
1007                 }
1008
1009                 /* this is what we can free from this extent */
1010                 grants          = chunks << cli->cl_chunkbits;
1011                 ext->oe_grants -= grants;
1012                 last_index      = ((trunc_chunk + 1) << ppc_bits) - 1;
1013                 ext->oe_end     = min(last_index, ext->oe_max_end);
1014                 LASSERT(ext->oe_end >= ext->oe_start);
1015                 LASSERT(ext->oe_grants > 0);
1016         }
1017         osc_object_unlock(obj);
1018
1019         if (grants > 0 || nr_pages > 0)
1020                 osc_free_grant(cli, nr_pages, grants);
1021
1022 out:
1023         cl_io_fini(env, io);
1024         cl_env_nested_put(&nest, env);
1025         RETURN(rc);
1026 }
1027
1028 /**
1029  * This function is used to make the extent prepared for transfer.
1030  * A race with flusing page - ll_writepage() has to be handled cautiously.
1031  */
1032 static int osc_extent_make_ready(const struct lu_env *env,
1033                                  struct osc_extent *ext)
1034 {
1035         struct osc_async_page *oap;
1036         struct osc_async_page *last = NULL;
1037         struct osc_object *obj = ext->oe_obj;
1038         int page_count = 0;
1039         int rc;
1040         ENTRY;
1041
1042         /* we're going to grab page lock, so object lock must not be taken. */
1043         LASSERT(sanity_check(ext) == 0);
1044         /* in locking state, any process should not touch this extent. */
1045         EASSERT(ext->oe_state == OES_LOCKING, ext);
1046         EASSERT(ext->oe_owner != NULL, ext);
1047
1048         OSC_EXTENT_DUMP(D_CACHE, ext, "make ready\n");
1049
1050         cfs_list_for_each_entry(oap, &ext->oe_pages, oap_pending_item) {
1051                 ++page_count;
1052                 if (last == NULL || last->oap_obj_off < oap->oap_obj_off)
1053                         last = oap;
1054
1055                 /* checking ASYNC_READY is race safe */
1056                 if ((oap->oap_async_flags & ASYNC_READY) != 0)
1057                         continue;
1058
1059                 rc = osc_make_ready(env, oap, OBD_BRW_WRITE);
1060                 switch (rc) {
1061                 case 0:
1062                         spin_lock(&oap->oap_lock);
1063                         oap->oap_async_flags |= ASYNC_READY;
1064                         spin_unlock(&oap->oap_lock);
1065                         break;
1066                 case -EALREADY:
1067                         LASSERT((oap->oap_async_flags & ASYNC_READY) != 0);
1068                         break;
1069                 default:
1070                         LASSERTF(0, "unknown return code: %d\n", rc);
1071                 }
1072         }
1073
1074         LASSERT(page_count == ext->oe_nr_pages);
1075         LASSERT(last != NULL);
1076         /* the last page is the only one we need to refresh its count by
1077          * the size of file. */
1078         if (!(last->oap_async_flags & ASYNC_COUNT_STABLE)) {
1079                 last->oap_count = osc_refresh_count(env, last, OBD_BRW_WRITE);
1080                 LASSERT(last->oap_count > 0);
1081                 LASSERT(last->oap_page_off + last->oap_count <= PAGE_CACHE_SIZE);
1082                 last->oap_async_flags |= ASYNC_COUNT_STABLE;
1083         }
1084
1085         /* for the rest of pages, we don't need to call osf_refresh_count()
1086          * because it's known they are not the last page */
1087         cfs_list_for_each_entry(oap, &ext->oe_pages, oap_pending_item) {
1088                 if (!(oap->oap_async_flags & ASYNC_COUNT_STABLE)) {
1089                         oap->oap_count = PAGE_CACHE_SIZE - oap->oap_page_off;
1090                         oap->oap_async_flags |= ASYNC_COUNT_STABLE;
1091                 }
1092         }
1093
1094         osc_object_lock(obj);
1095         osc_extent_state_set(ext, OES_RPC);
1096         osc_object_unlock(obj);
1097         /* get a refcount for RPC. */
1098         osc_extent_get(ext);
1099
1100         RETURN(0);
1101 }
1102
1103 /**
1104  * Quick and simple version of osc_extent_find(). This function is frequently
1105  * called to expand the extent for the same IO. To expand the extent, the
1106  * page index must be in the same or next chunk of ext->oe_end.
1107  */
1108 static int osc_extent_expand(struct osc_extent *ext, pgoff_t index, int *grants)
1109 {
1110         struct osc_object *obj = ext->oe_obj;
1111         struct client_obd *cli = osc_cli(obj);
1112         struct osc_extent *next;
1113         int ppc_bits = cli->cl_chunkbits - PAGE_CACHE_SHIFT;
1114         pgoff_t chunk = index >> ppc_bits;
1115         pgoff_t end_chunk;
1116         pgoff_t end_index;
1117         int chunksize = 1 << cli->cl_chunkbits;
1118         int rc = 0;
1119         ENTRY;
1120
1121         LASSERT(ext->oe_max_end >= index && ext->oe_start <= index);
1122         osc_object_lock(obj);
1123         LASSERT(sanity_check_nolock(ext) == 0);
1124         end_chunk = ext->oe_end >> ppc_bits;
1125         if (chunk > end_chunk + 1)
1126                 GOTO(out, rc = -ERANGE);
1127
1128         if (end_chunk >= chunk)
1129                 GOTO(out, rc = 0);
1130
1131         LASSERT(end_chunk + 1 == chunk);
1132         /* try to expand this extent to cover @index */
1133         end_index = min(ext->oe_max_end, ((chunk + 1) << ppc_bits) - 1);
1134
1135         next = next_extent(ext);
1136         if (next != NULL && next->oe_start <= end_index)
1137                 /* complex mode - overlapped with the next extent,
1138                  * this case will be handled by osc_extent_find() */
1139                 GOTO(out, rc = -EAGAIN);
1140
1141         ext->oe_end = end_index;
1142         ext->oe_grants += chunksize;
1143         *grants -= chunksize;
1144         LASSERT(*grants >= 0);
1145         EASSERTF(osc_extent_is_overlapped(obj, ext) == 0, ext,
1146                  "overlapped after expanding for %lu.\n", index);
1147         EXIT;
1148
1149 out:
1150         osc_object_unlock(obj);
1151         RETURN(rc);
1152 }
1153
1154 static void osc_extent_tree_dump0(int level, struct osc_object *obj,
1155                                   const char *func, int line)
1156 {
1157         struct osc_extent *ext;
1158         int cnt;
1159
1160         CDEBUG(level, "Dump object %p extents at %s:%d, mppr: %u.\n",
1161                obj, func, line, osc_cli(obj)->cl_max_pages_per_rpc);
1162
1163         /* osc_object_lock(obj); */
1164         cnt = 1;
1165         for (ext = first_extent(obj); ext != NULL; ext = next_extent(ext))
1166                 OSC_EXTENT_DUMP(level, ext, "in tree %d.\n", cnt++);
1167
1168         cnt = 1;
1169         cfs_list_for_each_entry(ext, &obj->oo_hp_exts, oe_link)
1170                 OSC_EXTENT_DUMP(level, ext, "hp %d.\n", cnt++);
1171
1172         cnt = 1;
1173         cfs_list_for_each_entry(ext, &obj->oo_urgent_exts, oe_link)
1174                 OSC_EXTENT_DUMP(level, ext, "urgent %d.\n", cnt++);
1175
1176         cnt = 1;
1177         cfs_list_for_each_entry(ext, &obj->oo_reading_exts, oe_link)
1178                 OSC_EXTENT_DUMP(level, ext, "reading %d.\n", cnt++);
1179         /* osc_object_unlock(obj); */
1180 }
1181
1182 /* ------------------ osc extent end ------------------ */
1183
1184 static inline int osc_is_ready(struct osc_object *osc)
1185 {
1186         return !cfs_list_empty(&osc->oo_ready_item) ||
1187                !cfs_list_empty(&osc->oo_hp_ready_item);
1188 }
1189
1190 #define OSC_IO_DEBUG(OSC, STR, args...)                                        \
1191         CDEBUG(D_CACHE, "obj %p ready %d|%c|%c wr %d|%c|%c rd %d|%c " STR,     \
1192                (OSC), osc_is_ready(OSC),                                       \
1193                list_empty_marker(&(OSC)->oo_hp_ready_item),                    \
1194                list_empty_marker(&(OSC)->oo_ready_item),                       \
1195                cfs_atomic_read(&(OSC)->oo_nr_writes),                          \
1196                list_empty_marker(&(OSC)->oo_hp_exts),                          \
1197                list_empty_marker(&(OSC)->oo_urgent_exts),                      \
1198                cfs_atomic_read(&(OSC)->oo_nr_reads),                           \
1199                list_empty_marker(&(OSC)->oo_reading_exts),                     \
1200                ##args)
1201
1202 static int osc_make_ready(const struct lu_env *env, struct osc_async_page *oap,
1203                           int cmd)
1204 {
1205         struct osc_page *opg  = oap2osc_page(oap);
1206         struct cl_page  *page = cl_page_top(oap2cl_page(oap));
1207         int result;
1208
1209         LASSERT(cmd == OBD_BRW_WRITE); /* no cached reads */
1210
1211         ENTRY;
1212         result = cl_page_make_ready(env, page, CRT_WRITE);
1213         if (result == 0)
1214                 opg->ops_submit_time = cfs_time_current();
1215         RETURN(result);
1216 }
1217
1218 static int osc_refresh_count(const struct lu_env *env,
1219                              struct osc_async_page *oap, int cmd)
1220 {
1221         struct osc_page  *opg = oap2osc_page(oap);
1222         struct cl_page   *page = oap2cl_page(oap);
1223         struct cl_object *obj;
1224         struct cl_attr   *attr = &osc_env_info(env)->oti_attr;
1225
1226         int result;
1227         loff_t kms;
1228
1229         /* readpage queues with _COUNT_STABLE, shouldn't get here. */
1230         LASSERT(!(cmd & OBD_BRW_READ));
1231         LASSERT(opg != NULL);
1232         obj = opg->ops_cl.cpl_obj;
1233
1234         cl_object_attr_lock(obj);
1235         result = cl_object_attr_get(env, obj, attr);
1236         cl_object_attr_unlock(obj);
1237         if (result < 0)
1238                 return result;
1239         kms = attr->cat_kms;
1240         if (cl_offset(obj, page->cp_index) >= kms)
1241                 /* catch race with truncate */
1242                 return 0;
1243         else if (cl_offset(obj, page->cp_index + 1) > kms)
1244                 /* catch sub-page write at end of file */
1245                 return kms % PAGE_CACHE_SIZE;
1246         else
1247                 return PAGE_CACHE_SIZE;
1248 }
1249
1250 static int osc_completion(const struct lu_env *env, struct osc_async_page *oap,
1251                           int cmd, int rc)
1252 {
1253         struct osc_page   *opg  = oap2osc_page(oap);
1254         struct cl_page    *page = cl_page_top(oap2cl_page(oap));
1255         struct osc_object *obj  = cl2osc(opg->ops_cl.cpl_obj);
1256         enum cl_req_type   crt;
1257         int srvlock;
1258
1259         ENTRY;
1260
1261         cmd &= ~OBD_BRW_NOQUOTA;
1262         LASSERT(equi(page->cp_state == CPS_PAGEIN,  cmd == OBD_BRW_READ));
1263         LASSERT(equi(page->cp_state == CPS_PAGEOUT, cmd == OBD_BRW_WRITE));
1264         LASSERT(opg->ops_transfer_pinned);
1265
1266         /*
1267          * page->cp_req can be NULL if io submission failed before
1268          * cl_req was allocated.
1269          */
1270         if (page->cp_req != NULL)
1271                 cl_req_page_done(env, page);
1272         LASSERT(page->cp_req == NULL);
1273
1274         crt = cmd == OBD_BRW_READ ? CRT_READ : CRT_WRITE;
1275         /* Clear opg->ops_transfer_pinned before VM lock is released. */
1276         opg->ops_transfer_pinned = 0;
1277
1278         spin_lock(&obj->oo_seatbelt);
1279         LASSERT(opg->ops_submitter != NULL);
1280         LASSERT(!cfs_list_empty(&opg->ops_inflight));
1281         cfs_list_del_init(&opg->ops_inflight);
1282         opg->ops_submitter = NULL;
1283         spin_unlock(&obj->oo_seatbelt);
1284
1285         opg->ops_submit_time = 0;
1286         srvlock = oap->oap_brw_flags & OBD_BRW_SRVLOCK;
1287
1288         /* statistic */
1289         if (rc == 0 && srvlock) {
1290                 struct lu_device *ld    = opg->ops_cl.cpl_obj->co_lu.lo_dev;
1291                 struct osc_stats *stats = &lu2osc_dev(ld)->od_stats;
1292                 int bytes = oap->oap_count;
1293
1294                 if (crt == CRT_READ)
1295                         stats->os_lockless_reads += bytes;
1296                 else
1297                         stats->os_lockless_writes += bytes;
1298         }
1299
1300         /*
1301          * This has to be the last operation with the page, as locks are
1302          * released in cl_page_completion() and nothing except for the
1303          * reference counter protects page from concurrent reclaim.
1304          */
1305         lu_ref_del(&page->cp_reference, "transfer", page);
1306
1307         cl_page_completion(env, page, crt, rc);
1308
1309         RETURN(0);
1310 }
1311
1312 #define OSC_DUMP_GRANT(lvl, cli, fmt, args...) do {                           \
1313         struct client_obd *__tmp = (cli);                                     \
1314         CDEBUG(lvl, "%s: grant { dirty: %ld/%ld dirty_pages: %d/%d "          \
1315                "dropped: %ld avail: %ld, reserved: %ld, flight: %d } "        \
1316                "lru {in list: %d, left: %d, waiters: %d }" fmt,               \
1317                __tmp->cl_import->imp_obd->obd_name,                           \
1318                __tmp->cl_dirty, __tmp->cl_dirty_max,                          \
1319                cfs_atomic_read(&obd_dirty_pages), obd_max_dirty_pages,        \
1320                __tmp->cl_lost_grant, __tmp->cl_avail_grant,                   \
1321                __tmp->cl_reserved_grant, __tmp->cl_w_in_flight,               \
1322                cfs_atomic_read(&__tmp->cl_lru_in_list),                       \
1323                cfs_atomic_read(&__tmp->cl_lru_busy),                          \
1324                cfs_atomic_read(&__tmp->cl_lru_shrinkers), ##args);            \
1325 } while (0)
1326
1327 /* caller must hold loi_list_lock */
1328 static void osc_consume_write_grant(struct client_obd *cli,
1329                                     struct brw_page *pga)
1330 {
1331         LASSERT(spin_is_locked(&cli->cl_loi_list_lock.lock));
1332         LASSERT(!(pga->flag & OBD_BRW_FROM_GRANT));
1333         cfs_atomic_inc(&obd_dirty_pages);
1334         cli->cl_dirty += PAGE_CACHE_SIZE;
1335         pga->flag |= OBD_BRW_FROM_GRANT;
1336         CDEBUG(D_CACHE, "using %lu grant credits for brw %p page %p\n",
1337                PAGE_CACHE_SIZE, pga, pga->pg);
1338         osc_update_next_shrink(cli);
1339 }
1340
1341 /* the companion to osc_consume_write_grant, called when a brw has completed.
1342  * must be called with the loi lock held. */
1343 static void osc_release_write_grant(struct client_obd *cli,
1344                                     struct brw_page *pga)
1345 {
1346         ENTRY;
1347
1348         LASSERT(spin_is_locked(&cli->cl_loi_list_lock.lock));
1349         if (!(pga->flag & OBD_BRW_FROM_GRANT)) {
1350                 EXIT;
1351                 return;
1352         }
1353
1354         pga->flag &= ~OBD_BRW_FROM_GRANT;
1355         cfs_atomic_dec(&obd_dirty_pages);
1356         cli->cl_dirty -= PAGE_CACHE_SIZE;
1357         if (pga->flag & OBD_BRW_NOCACHE) {
1358                 pga->flag &= ~OBD_BRW_NOCACHE;
1359                 cfs_atomic_dec(&obd_dirty_transit_pages);
1360                 cli->cl_dirty_transit -= PAGE_CACHE_SIZE;
1361         }
1362         EXIT;
1363 }
1364
1365 /**
1366  * To avoid sleeping with object lock held, it's good for us allocate enough
1367  * grants before entering into critical section.
1368  *
1369  * client_obd_list_lock held by caller
1370  */
1371 static int osc_reserve_grant(struct client_obd *cli, unsigned int bytes)
1372 {
1373         int rc = -EDQUOT;
1374
1375         if (cli->cl_avail_grant >= bytes) {
1376                 cli->cl_avail_grant    -= bytes;
1377                 cli->cl_reserved_grant += bytes;
1378                 rc = 0;
1379         }
1380         return rc;
1381 }
1382
1383 static void __osc_unreserve_grant(struct client_obd *cli,
1384                                   unsigned int reserved, unsigned int unused)
1385 {
1386         /* it's quite normal for us to get more grant than reserved.
1387          * Thinking about a case that two extents merged by adding a new
1388          * chunk, we can save one extent tax. If extent tax is greater than
1389          * one chunk, we can save more grant by adding a new chunk */
1390         cli->cl_reserved_grant -= reserved;
1391         if (unused > reserved) {
1392                 cli->cl_avail_grant += reserved;
1393                 cli->cl_lost_grant  += unused - reserved;
1394         } else {
1395                 cli->cl_avail_grant += unused;
1396         }
1397 }
1398
1399 void osc_unreserve_grant(struct client_obd *cli,
1400                          unsigned int reserved, unsigned int unused)
1401 {
1402         client_obd_list_lock(&cli->cl_loi_list_lock);
1403         __osc_unreserve_grant(cli, reserved, unused);
1404         if (unused > 0)
1405                 osc_wake_cache_waiters(cli);
1406         client_obd_list_unlock(&cli->cl_loi_list_lock);
1407 }
1408
1409 /**
1410  * Free grant after IO is finished or canceled.
1411  *
1412  * @lost_grant is used to remember how many grants we have allocated but not
1413  * used, we should return these grants to OST. There're two cases where grants
1414  * can be lost:
1415  * 1. truncate;
1416  * 2. blocksize at OST is less than PAGE_CACHE_SIZE and a partial page was
1417  *    written. In this case OST may use less chunks to serve this partial
1418  *    write. OSTs don't actually know the page size on the client side. so
1419  *    clients have to calculate lost grant by the blocksize on the OST.
1420  *    See filter_grant_check() for details.
1421  */
1422 static void osc_free_grant(struct client_obd *cli, unsigned int nr_pages,
1423                            unsigned int lost_grant)
1424 {
1425         int grant = (1 << cli->cl_chunkbits) + cli->cl_extent_tax;
1426
1427         client_obd_list_lock(&cli->cl_loi_list_lock);
1428         cfs_atomic_sub(nr_pages, &obd_dirty_pages);
1429         cli->cl_dirty -= nr_pages << PAGE_CACHE_SHIFT;
1430         cli->cl_lost_grant += lost_grant;
1431         if (cli->cl_avail_grant < grant && cli->cl_lost_grant >= grant) {
1432                 /* borrow some grant from truncate to avoid the case that
1433                  * truncate uses up all avail grant */
1434                 cli->cl_lost_grant -= grant;
1435                 cli->cl_avail_grant += grant;
1436         }
1437         osc_wake_cache_waiters(cli);
1438         client_obd_list_unlock(&cli->cl_loi_list_lock);
1439         CDEBUG(D_CACHE, "lost %u grant: %lu avail: %lu dirty: %lu\n",
1440                lost_grant, cli->cl_lost_grant,
1441                cli->cl_avail_grant, cli->cl_dirty);
1442 }
1443
1444 /**
1445  * The companion to osc_enter_cache(), called when @oap is no longer part of
1446  * the dirty accounting due to error.
1447  */
1448 static void osc_exit_cache(struct client_obd *cli, struct osc_async_page *oap)
1449 {
1450         client_obd_list_lock(&cli->cl_loi_list_lock);
1451         osc_release_write_grant(cli, &oap->oap_brw_page);
1452         client_obd_list_unlock(&cli->cl_loi_list_lock);
1453 }
1454
1455 /**
1456  * Non-blocking version of osc_enter_cache() that consumes grant only when it
1457  * is available.
1458  */
1459 static int osc_enter_cache_try(struct client_obd *cli,
1460                                struct osc_async_page *oap,
1461                                int bytes, int transient)
1462 {
1463         int rc;
1464
1465         OSC_DUMP_GRANT(D_CACHE, cli, "need:%d.\n", bytes);
1466
1467         rc = osc_reserve_grant(cli, bytes);
1468         if (rc < 0)
1469                 return 0;
1470
1471         if (cli->cl_dirty + PAGE_CACHE_SIZE <= cli->cl_dirty_max &&
1472             cfs_atomic_read(&obd_dirty_pages) + 1 <= obd_max_dirty_pages) {
1473                 osc_consume_write_grant(cli, &oap->oap_brw_page);
1474                 if (transient) {
1475                         cli->cl_dirty_transit += PAGE_CACHE_SIZE;
1476                         cfs_atomic_inc(&obd_dirty_transit_pages);
1477                         oap->oap_brw_flags |= OBD_BRW_NOCACHE;
1478                 }
1479                 rc = 1;
1480         } else {
1481                 __osc_unreserve_grant(cli, bytes, bytes);
1482                 rc = 0;
1483         }
1484         return rc;
1485 }
1486
1487 static int ocw_granted(struct client_obd *cli, struct osc_cache_waiter *ocw)
1488 {
1489         int rc;
1490         client_obd_list_lock(&cli->cl_loi_list_lock);
1491         rc = cfs_list_empty(&ocw->ocw_entry);
1492         client_obd_list_unlock(&cli->cl_loi_list_lock);
1493         return rc;
1494 }
1495
1496 /**
1497  * The main entry to reserve dirty page accounting. Usually the grant reserved
1498  * in this function will be freed in bulk in osc_free_grant() unless it fails
1499  * to add osc cache, in that case, it will be freed in osc_exit_cache().
1500  *
1501  * The process will be put into sleep if it's already run out of grant.
1502  */
1503 static int osc_enter_cache(const struct lu_env *env, struct client_obd *cli,
1504                            struct osc_async_page *oap, int bytes)
1505 {
1506         struct osc_object *osc = oap->oap_obj;
1507         struct lov_oinfo  *loi = osc->oo_oinfo;
1508         struct osc_cache_waiter ocw;
1509         struct l_wait_info lwi = LWI_TIMEOUT_INTR(cfs_time_seconds(600), NULL,
1510                                                   LWI_ON_SIGNAL_NOOP, NULL);
1511         int rc = -EDQUOT;
1512         ENTRY;
1513
1514         OSC_DUMP_GRANT(D_CACHE, cli, "need:%d.\n", bytes);
1515
1516         client_obd_list_lock(&cli->cl_loi_list_lock);
1517
1518         /* force the caller to try sync io.  this can jump the list
1519          * of queued writes and create a discontiguous rpc stream */
1520         if (OBD_FAIL_CHECK(OBD_FAIL_OSC_NO_GRANT) ||
1521             cli->cl_dirty_max < PAGE_CACHE_SIZE     ||
1522             cli->cl_ar.ar_force_sync || loi->loi_ar.ar_force_sync)
1523                 GOTO(out, rc = -EDQUOT);
1524
1525         /* Hopefully normal case - cache space and write credits available */
1526         if (osc_enter_cache_try(cli, oap, bytes, 0))
1527                 GOTO(out, rc = 0);
1528
1529         /* We can get here for two reasons: too many dirty pages in cache, or
1530          * run out of grants. In both cases we should write dirty pages out.
1531          * Adding a cache waiter will trigger urgent write-out no matter what
1532          * RPC size will be.
1533          * The exiting condition is no avail grants and no dirty pages caching,
1534          * that really means there is no space on the OST. */
1535         cfs_waitq_init(&ocw.ocw_waitq);
1536         ocw.ocw_oap   = oap;
1537         ocw.ocw_grant = bytes;
1538         while (cli->cl_dirty > 0 || cli->cl_w_in_flight > 0) {
1539                 cfs_list_add_tail(&ocw.ocw_entry, &cli->cl_cache_waiters);
1540                 ocw.ocw_rc = 0;
1541                 client_obd_list_unlock(&cli->cl_loi_list_lock);
1542
1543                 osc_io_unplug_async(env, cli, NULL);
1544
1545                 CDEBUG(D_CACHE, "%s: sleeping for cache space @ %p for %p\n",
1546                        cli->cl_import->imp_obd->obd_name, &ocw, oap);
1547
1548                 rc = l_wait_event(ocw.ocw_waitq, ocw_granted(cli, &ocw), &lwi);
1549
1550                 client_obd_list_lock(&cli->cl_loi_list_lock);
1551
1552                 /* l_wait_event is interrupted by signal, or timed out */
1553                 if (rc < 0) {
1554                         switch (rc) {
1555                         case -ETIMEDOUT:
1556                                 OSC_DUMP_GRANT(D_ERROR, cli,
1557                                                 "try to reserve %d.\n", bytes);
1558                                 osc_extent_tree_dump(D_ERROR, osc);
1559                                 rc = -EDQUOT;
1560                                 break;
1561                         case -EINTR:
1562                                 /* Ensures restartability - LU-3581 */
1563                                 rc = -ERESTARTSYS;
1564                                 break;
1565                         default:
1566                                 CDEBUG(D_CACHE, "%s: event for cache space @"
1567                                        " %p never arrived due to %d\n",
1568                                        cli->cl_import->imp_obd->obd_name,
1569                                        &ocw, rc);
1570                                 break;
1571                         }
1572                         cfs_list_del_init(&ocw.ocw_entry);
1573                         GOTO(out, rc);
1574                 }
1575
1576                 LASSERT(cfs_list_empty(&ocw.ocw_entry));
1577                 rc = ocw.ocw_rc;
1578
1579                 if (rc != -EDQUOT)
1580                         GOTO(out, rc);
1581                 if (osc_enter_cache_try(cli, oap, bytes, 0))
1582                         GOTO(out, rc = 0);
1583         }
1584         EXIT;
1585 out:
1586         client_obd_list_unlock(&cli->cl_loi_list_lock);
1587         OSC_DUMP_GRANT(D_CACHE, cli, "returned %d.\n", rc);
1588         RETURN(rc);
1589 }
1590
1591 /* caller must hold loi_list_lock */
1592 void osc_wake_cache_waiters(struct client_obd *cli)
1593 {
1594         cfs_list_t *l, *tmp;
1595         struct osc_cache_waiter *ocw;
1596
1597         ENTRY;
1598         cfs_list_for_each_safe(l, tmp, &cli->cl_cache_waiters) {
1599                 ocw = cfs_list_entry(l, struct osc_cache_waiter, ocw_entry);
1600                 cfs_list_del_init(&ocw->ocw_entry);
1601
1602                 ocw->ocw_rc = -EDQUOT;
1603                 /* we can't dirty more */
1604                 if ((cli->cl_dirty + PAGE_CACHE_SIZE > cli->cl_dirty_max) ||
1605                     (cfs_atomic_read(&obd_dirty_pages) + 1 >
1606                      obd_max_dirty_pages)) {
1607                         CDEBUG(D_CACHE, "no dirty room: dirty: %ld "
1608                                "osc max %ld, sys max %d\n", cli->cl_dirty,
1609                                cli->cl_dirty_max, obd_max_dirty_pages);
1610                         goto wakeup;
1611                 }
1612
1613                 ocw->ocw_rc = 0;
1614                 if (!osc_enter_cache_try(cli, ocw->ocw_oap, ocw->ocw_grant, 0))
1615                         ocw->ocw_rc = -EDQUOT;
1616
1617 wakeup:
1618                 CDEBUG(D_CACHE, "wake up %p for oap %p, avail grant %ld, %d\n",
1619                        ocw, ocw->ocw_oap, cli->cl_avail_grant, ocw->ocw_rc);
1620
1621                 cfs_waitq_signal(&ocw->ocw_waitq);
1622         }
1623
1624         EXIT;
1625 }
1626
1627 static int osc_max_rpc_in_flight(struct client_obd *cli, struct osc_object *osc)
1628 {
1629         int hprpc = !!cfs_list_empty(&osc->oo_hp_exts);
1630         return rpcs_in_flight(cli) >= cli->cl_max_rpcs_in_flight + hprpc;
1631 }
1632
1633 /* This maintains the lists of pending pages to read/write for a given object
1634  * (lop).  This is used by osc_check_rpcs->osc_next_obj() and osc_list_maint()
1635  * to quickly find objects that are ready to send an RPC. */
1636 static int osc_makes_rpc(struct client_obd *cli, struct osc_object *osc,
1637                          int cmd)
1638 {
1639         int invalid_import = 0;
1640         ENTRY;
1641
1642         /* if we have an invalid import we want to drain the queued pages
1643          * by forcing them through rpcs that immediately fail and complete
1644          * the pages.  recovery relies on this to empty the queued pages
1645          * before canceling the locks and evicting down the llite pages */
1646         if ((cli->cl_import == NULL || cli->cl_import->imp_invalid))
1647                 invalid_import = 1;
1648
1649         if (cmd & OBD_BRW_WRITE) {
1650                 if (cfs_atomic_read(&osc->oo_nr_writes) == 0)
1651                         RETURN(0);
1652                 if (invalid_import) {
1653                         CDEBUG(D_CACHE, "invalid import forcing RPC\n");
1654                         RETURN(1);
1655                 }
1656                 if (!cfs_list_empty(&osc->oo_hp_exts)) {
1657                         CDEBUG(D_CACHE, "high prio request forcing RPC\n");
1658                         RETURN(1);
1659                 }
1660                 if (!cfs_list_empty(&osc->oo_urgent_exts)) {
1661                         CDEBUG(D_CACHE, "urgent request forcing RPC\n");
1662                         RETURN(1);
1663                 }
1664                 /* trigger a write rpc stream as long as there are dirtiers
1665                  * waiting for space.  as they're waiting, they're not going to
1666                  * create more pages to coalesce with what's waiting.. */
1667                 if (!cfs_list_empty(&cli->cl_cache_waiters)) {
1668                         CDEBUG(D_CACHE, "cache waiters forcing RPC\n");
1669                         RETURN(1);
1670                 }
1671                 if (cfs_atomic_read(&osc->oo_nr_writes) >=
1672                     cli->cl_max_pages_per_rpc)
1673                         RETURN(1);
1674         } else {
1675                 if (cfs_atomic_read(&osc->oo_nr_reads) == 0)
1676                         RETURN(0);
1677                 if (invalid_import) {
1678                         CDEBUG(D_CACHE, "invalid import forcing RPC\n");
1679                         RETURN(1);
1680                 }
1681                 /* all read are urgent. */
1682                 if (!cfs_list_empty(&osc->oo_reading_exts))
1683                         RETURN(1);
1684         }
1685
1686         RETURN(0);
1687 }
1688
1689 static void osc_update_pending(struct osc_object *obj, int cmd, int delta)
1690 {
1691         struct client_obd *cli = osc_cli(obj);
1692         if (cmd & OBD_BRW_WRITE) {
1693                 cfs_atomic_add(delta, &obj->oo_nr_writes);
1694                 cfs_atomic_add(delta, &cli->cl_pending_w_pages);
1695                 LASSERT(cfs_atomic_read(&obj->oo_nr_writes) >= 0);
1696         } else {
1697                 cfs_atomic_add(delta, &obj->oo_nr_reads);
1698                 cfs_atomic_add(delta, &cli->cl_pending_r_pages);
1699                 LASSERT(cfs_atomic_read(&obj->oo_nr_reads) >= 0);
1700         }
1701         OSC_IO_DEBUG(obj, "update pending cmd %d delta %d.\n", cmd, delta);
1702 }
1703
1704 static int osc_makes_hprpc(struct osc_object *obj)
1705 {
1706         return !cfs_list_empty(&obj->oo_hp_exts);
1707 }
1708
1709 static void on_list(cfs_list_t *item, cfs_list_t *list, int should_be_on)
1710 {
1711         if (cfs_list_empty(item) && should_be_on)
1712                 cfs_list_add_tail(item, list);
1713         else if (!cfs_list_empty(item) && !should_be_on)
1714                 cfs_list_del_init(item);
1715 }
1716
1717 /* maintain the osc's cli list membership invariants so that osc_send_oap_rpc
1718  * can find pages to build into rpcs quickly */
1719 static int __osc_list_maint(struct client_obd *cli, struct osc_object *osc)
1720 {
1721         if (osc_makes_hprpc(osc)) {
1722                 /* HP rpc */
1723                 on_list(&osc->oo_ready_item, &cli->cl_loi_ready_list, 0);
1724                 on_list(&osc->oo_hp_ready_item, &cli->cl_loi_hp_ready_list, 1);
1725         } else {
1726                 on_list(&osc->oo_hp_ready_item, &cli->cl_loi_hp_ready_list, 0);
1727                 on_list(&osc->oo_ready_item, &cli->cl_loi_ready_list,
1728                         osc_makes_rpc(cli, osc, OBD_BRW_WRITE) ||
1729                         osc_makes_rpc(cli, osc, OBD_BRW_READ));
1730         }
1731
1732         on_list(&osc->oo_write_item, &cli->cl_loi_write_list,
1733                 cfs_atomic_read(&osc->oo_nr_writes) > 0);
1734
1735         on_list(&osc->oo_read_item, &cli->cl_loi_read_list,
1736                 cfs_atomic_read(&osc->oo_nr_reads) > 0);
1737
1738         return osc_is_ready(osc);
1739 }
1740
1741 static int osc_list_maint(struct client_obd *cli, struct osc_object *osc)
1742 {
1743         int is_ready;
1744
1745         client_obd_list_lock(&cli->cl_loi_list_lock);
1746         is_ready = __osc_list_maint(cli, osc);
1747         client_obd_list_unlock(&cli->cl_loi_list_lock);
1748
1749         return is_ready;
1750 }
1751
1752 /* this is trying to propogate async writeback errors back up to the
1753  * application.  As an async write fails we record the error code for later if
1754  * the app does an fsync.  As long as errors persist we force future rpcs to be
1755  * sync so that the app can get a sync error and break the cycle of queueing
1756  * pages for which writeback will fail. */
1757 static void osc_process_ar(struct osc_async_rc *ar, __u64 xid,
1758                            int rc)
1759 {
1760         if (rc) {
1761                 if (!ar->ar_rc)
1762                         ar->ar_rc = rc;
1763
1764                 ar->ar_force_sync = 1;
1765                 ar->ar_min_xid = ptlrpc_sample_next_xid();
1766                 return;
1767
1768         }
1769
1770         if (ar->ar_force_sync && (xid >= ar->ar_min_xid))
1771                 ar->ar_force_sync = 0;
1772 }
1773
1774 /* this must be called holding the loi list lock to give coverage to exit_cache,
1775  * async_flag maintenance, and oap_request */
1776 static void osc_ap_completion(const struct lu_env *env, struct client_obd *cli,
1777                               struct osc_async_page *oap, int sent, int rc)
1778 {
1779         struct osc_object *osc = oap->oap_obj;
1780         struct lov_oinfo  *loi = osc->oo_oinfo;
1781         __u64 xid = 0;
1782
1783         ENTRY;
1784         if (oap->oap_request != NULL) {
1785                 xid = ptlrpc_req_xid(oap->oap_request);
1786                 ptlrpc_req_finished(oap->oap_request);
1787                 oap->oap_request = NULL;
1788         }
1789
1790         /* As the transfer for this page is being done, clear the flags */
1791         spin_lock(&oap->oap_lock);
1792         oap->oap_async_flags = 0;
1793         spin_unlock(&oap->oap_lock);
1794         oap->oap_interrupted = 0;
1795
1796         if (oap->oap_cmd & OBD_BRW_WRITE && xid > 0) {
1797                 client_obd_list_lock(&cli->cl_loi_list_lock);
1798                 osc_process_ar(&cli->cl_ar, xid, rc);
1799                 osc_process_ar(&loi->loi_ar, xid, rc);
1800                 client_obd_list_unlock(&cli->cl_loi_list_lock);
1801         }
1802
1803         rc = osc_completion(env, oap, oap->oap_cmd, rc);
1804         if (rc)
1805                 CERROR("completion on oap %p obj %p returns %d.\n",
1806                        oap, osc, rc);
1807
1808         EXIT;
1809 }
1810
1811 /**
1812  * Try to add extent to one RPC. We need to think about the following things:
1813  * - # of pages must not be over max_pages_per_rpc
1814  * - extent must be compatible with previous ones
1815  */
1816 static int try_to_add_extent_for_io(struct client_obd *cli,
1817                                     struct osc_extent *ext, cfs_list_t *rpclist,
1818                                     int *pc, unsigned int *max_pages)
1819 {
1820         struct osc_extent *tmp;
1821         ENTRY;
1822
1823         EASSERT((ext->oe_state == OES_CACHE || ext->oe_state == OES_LOCK_DONE),
1824                 ext);
1825
1826         *max_pages = max(ext->oe_mppr, *max_pages);
1827         if (*pc + ext->oe_nr_pages > *max_pages)
1828                 RETURN(0);
1829
1830         cfs_list_for_each_entry(tmp, rpclist, oe_link) {
1831                 EASSERT(tmp->oe_owner == cfs_current(), tmp);
1832 #if 0
1833                 if (overlapped(tmp, ext)) {
1834                         OSC_EXTENT_DUMP(D_ERROR, tmp, "overlapped %p.\n", ext);
1835                         EASSERT(0, ext);
1836                 }
1837 #endif
1838
1839                 if (tmp->oe_srvlock != ext->oe_srvlock ||
1840                     !tmp->oe_grants != !ext->oe_grants)
1841                         RETURN(0);
1842
1843                 /* remove break for strict check */
1844                 break;
1845         }
1846
1847         *pc += ext->oe_nr_pages;
1848         cfs_list_move_tail(&ext->oe_link, rpclist);
1849         ext->oe_owner = cfs_current();
1850         RETURN(1);
1851 }
1852
1853 /**
1854  * In order to prevent multiple ptlrpcd from breaking contiguous extents,
1855  * get_write_extent() takes all appropriate extents in atomic.
1856  *
1857  * The following policy is used to collect extents for IO:
1858  * 1. Add as many HP extents as possible;
1859  * 2. Add the first urgent extent in urgent extent list and take it out of
1860  *    urgent list;
1861  * 3. Add subsequent extents of this urgent extent;
1862  * 4. If urgent list is not empty, goto 2;
1863  * 5. Traverse the extent tree from the 1st extent;
1864  * 6. Above steps exit if there is no space in this RPC.
1865  */
1866 static int get_write_extents(struct osc_object *obj, cfs_list_t *rpclist)
1867 {
1868         struct client_obd *cli = osc_cli(obj);
1869         struct osc_extent *ext;
1870         int page_count = 0;
1871         unsigned int max_pages = cli->cl_max_pages_per_rpc;
1872
1873         LASSERT(osc_object_is_locked(obj));
1874         while (!cfs_list_empty(&obj->oo_hp_exts)) {
1875                 ext = cfs_list_entry(obj->oo_hp_exts.next, struct osc_extent,
1876                                      oe_link);
1877                 LASSERT(ext->oe_state == OES_CACHE);
1878                 if (!try_to_add_extent_for_io(cli, ext, rpclist, &page_count,
1879                                               &max_pages))
1880                         return page_count;
1881                 EASSERT(ext->oe_nr_pages <= max_pages, ext);
1882         }
1883         if (page_count == max_pages)
1884                 return page_count;
1885
1886         while (!cfs_list_empty(&obj->oo_urgent_exts)) {
1887                 ext = cfs_list_entry(obj->oo_urgent_exts.next,
1888                                      struct osc_extent, oe_link);
1889                 if (!try_to_add_extent_for_io(cli, ext, rpclist, &page_count,
1890                                               &max_pages))
1891                         return page_count;
1892
1893                 if (!ext->oe_intree)
1894                         continue;
1895
1896                 while ((ext = next_extent(ext)) != NULL) {
1897                         if ((ext->oe_state != OES_CACHE) ||
1898                             (!cfs_list_empty(&ext->oe_link) &&
1899                              ext->oe_owner != NULL))
1900                                 continue;
1901
1902                         if (!try_to_add_extent_for_io(cli, ext, rpclist,
1903                                                       &page_count, &max_pages))
1904                                 return page_count;
1905                 }
1906         }
1907         if (page_count == max_pages)
1908                 return page_count;
1909
1910         ext = first_extent(obj);
1911         while (ext != NULL) {
1912                 if ((ext->oe_state != OES_CACHE) ||
1913                     /* this extent may be already in current rpclist */
1914                     (!cfs_list_empty(&ext->oe_link) && ext->oe_owner != NULL)) {
1915                         ext = next_extent(ext);
1916                         continue;
1917                 }
1918
1919                 if (!try_to_add_extent_for_io(cli, ext, rpclist, &page_count,
1920                                               &max_pages))
1921                         return page_count;
1922
1923                 ext = next_extent(ext);
1924         }
1925         return page_count;
1926 }
1927
1928 static int
1929 osc_send_write_rpc(const struct lu_env *env, struct client_obd *cli,
1930                    struct osc_object *osc, pdl_policy_t pol)
1931 {
1932         CFS_LIST_HEAD(rpclist);
1933         struct osc_extent *ext;
1934         struct osc_extent *tmp;
1935         struct osc_extent *first = NULL;
1936         obd_count page_count = 0;
1937         int srvlock = 0;
1938         int rc = 0;
1939         ENTRY;
1940
1941         LASSERT(osc_object_is_locked(osc));
1942
1943         page_count = get_write_extents(osc, &rpclist);
1944         LASSERT(equi(page_count == 0, cfs_list_empty(&rpclist)));
1945
1946         if (cfs_list_empty(&rpclist))
1947                 RETURN(0);
1948
1949         osc_update_pending(osc, OBD_BRW_WRITE, -page_count);
1950
1951         cfs_list_for_each_entry(ext, &rpclist, oe_link) {
1952                 LASSERT(ext->oe_state == OES_CACHE ||
1953                         ext->oe_state == OES_LOCK_DONE);
1954                 if (ext->oe_state == OES_CACHE)
1955                         osc_extent_state_set(ext, OES_LOCKING);
1956                 else
1957                         osc_extent_state_set(ext, OES_RPC);
1958         }
1959
1960         /* we're going to grab page lock, so release object lock because
1961          * lock order is page lock -> object lock. */
1962         osc_object_unlock(osc);
1963
1964         cfs_list_for_each_entry_safe(ext, tmp, &rpclist, oe_link) {
1965                 if (ext->oe_state == OES_LOCKING) {
1966                         rc = osc_extent_make_ready(env, ext);
1967                         if (unlikely(rc < 0)) {
1968                                 cfs_list_del_init(&ext->oe_link);
1969                                 osc_extent_finish(env, ext, 0, rc);
1970                                 continue;
1971                         }
1972                 }
1973                 if (first == NULL) {
1974                         first = ext;
1975                         srvlock = ext->oe_srvlock;
1976                 } else {
1977                         LASSERT(srvlock == ext->oe_srvlock);
1978                 }
1979         }
1980
1981         if (!cfs_list_empty(&rpclist)) {
1982                 LASSERT(page_count > 0);
1983                 rc = osc_build_rpc(env, cli, &rpclist, OBD_BRW_WRITE, pol);
1984                 LASSERT(cfs_list_empty(&rpclist));
1985         }
1986
1987         osc_object_lock(osc);
1988         RETURN(rc);
1989 }
1990
1991 /**
1992  * prepare pages for ASYNC io and put pages in send queue.
1993  *
1994  * \param cmd OBD_BRW_* macroses
1995  * \param lop pending pages
1996  *
1997  * \return zero if no page added to send queue.
1998  * \return 1 if pages successfully added to send queue.
1999  * \return negative on errors.
2000  */
2001 static int
2002 osc_send_read_rpc(const struct lu_env *env, struct client_obd *cli,
2003                   struct osc_object *osc, pdl_policy_t pol)
2004 {
2005         struct osc_extent *ext;
2006         struct osc_extent *next;
2007         CFS_LIST_HEAD(rpclist);
2008         int page_count = 0;
2009         unsigned int max_pages = cli->cl_max_pages_per_rpc;
2010         int rc = 0;
2011         ENTRY;
2012
2013         LASSERT(osc_object_is_locked(osc));
2014         cfs_list_for_each_entry_safe(ext, next,
2015                                      &osc->oo_reading_exts, oe_link) {
2016                 EASSERT(ext->oe_state == OES_LOCK_DONE, ext);
2017                 if (!try_to_add_extent_for_io(cli, ext, &rpclist, &page_count,
2018                                               &max_pages))
2019                         break;
2020                 osc_extent_state_set(ext, OES_RPC);
2021                 EASSERT(ext->oe_nr_pages <= max_pages, ext);
2022         }
2023         LASSERT(page_count <= max_pages);
2024
2025         osc_update_pending(osc, OBD_BRW_READ, -page_count);
2026
2027         if (!cfs_list_empty(&rpclist)) {
2028                 osc_object_unlock(osc);
2029
2030                 LASSERT(page_count > 0);
2031                 rc = osc_build_rpc(env, cli, &rpclist, OBD_BRW_READ, pol);
2032                 LASSERT(cfs_list_empty(&rpclist));
2033
2034                 osc_object_lock(osc);
2035         }
2036         RETURN(rc);
2037 }
2038
2039 #define list_to_obj(list, item) ({                                            \
2040         cfs_list_t *__tmp = (list)->next;                                     \
2041         cfs_list_del_init(__tmp);                                             \
2042         cfs_list_entry(__tmp, struct osc_object, oo_##item);                  \
2043 })
2044
2045 /* This is called by osc_check_rpcs() to find which objects have pages that
2046  * we could be sending.  These lists are maintained by osc_makes_rpc(). */
2047 static struct osc_object *osc_next_obj(struct client_obd *cli)
2048 {
2049         ENTRY;
2050
2051         /* First return objects that have blocked locks so that they
2052          * will be flushed quickly and other clients can get the lock,
2053          * then objects which have pages ready to be stuffed into RPCs */
2054         if (!cfs_list_empty(&cli->cl_loi_hp_ready_list))
2055                 RETURN(list_to_obj(&cli->cl_loi_hp_ready_list, hp_ready_item));
2056         if (!cfs_list_empty(&cli->cl_loi_ready_list))
2057                 RETURN(list_to_obj(&cli->cl_loi_ready_list, ready_item));
2058
2059         /* then if we have cache waiters, return all objects with queued
2060          * writes.  This is especially important when many small files
2061          * have filled up the cache and not been fired into rpcs because
2062          * they don't pass the nr_pending/object threshhold */
2063         if (!cfs_list_empty(&cli->cl_cache_waiters) &&
2064             !cfs_list_empty(&cli->cl_loi_write_list))
2065                 RETURN(list_to_obj(&cli->cl_loi_write_list, write_item));
2066
2067         /* then return all queued objects when we have an invalid import
2068          * so that they get flushed */
2069         if (cli->cl_import == NULL || cli->cl_import->imp_invalid) {
2070                 if (!cfs_list_empty(&cli->cl_loi_write_list))
2071                         RETURN(list_to_obj(&cli->cl_loi_write_list,
2072                                            write_item));
2073                 if (!cfs_list_empty(&cli->cl_loi_read_list))
2074                         RETURN(list_to_obj(&cli->cl_loi_read_list,
2075                                            read_item));
2076         }
2077         RETURN(NULL);
2078 }
2079
2080 /* called with the loi list lock held */
2081 static void osc_check_rpcs(const struct lu_env *env, struct client_obd *cli,
2082                            pdl_policy_t pol)
2083 {
2084         struct osc_object *osc;
2085         int rc = 0;
2086         ENTRY;
2087
2088         while ((osc = osc_next_obj(cli)) != NULL) {
2089                 struct cl_object *obj = osc2cl(osc);
2090                 struct lu_ref_link link;
2091
2092                 OSC_IO_DEBUG(osc, "%lu in flight\n", rpcs_in_flight(cli));
2093
2094                 if (osc_max_rpc_in_flight(cli, osc)) {
2095                         __osc_list_maint(cli, osc);
2096                         break;
2097                 }
2098
2099                 cl_object_get(obj);
2100                 client_obd_list_unlock(&cli->cl_loi_list_lock);
2101                 lu_object_ref_add_at(&obj->co_lu, &link, "check",
2102                                      cfs_current());
2103
2104                 /* attempt some read/write balancing by alternating between
2105                  * reads and writes in an object.  The makes_rpc checks here
2106                  * would be redundant if we were getting read/write work items
2107                  * instead of objects.  we don't want send_oap_rpc to drain a
2108                  * partial read pending queue when we're given this object to
2109                  * do io on writes while there are cache waiters */
2110                 osc_object_lock(osc);
2111                 if (osc_makes_rpc(cli, osc, OBD_BRW_WRITE)) {
2112                         rc = osc_send_write_rpc(env, cli, osc, pol);
2113                         if (rc < 0) {
2114                                 CERROR("Write request failed with %d\n", rc);
2115
2116                                 /* osc_send_write_rpc failed, mostly because of
2117                                  * memory pressure.
2118                                  *
2119                                  * It can't break here, because if:
2120                                  *  - a page was submitted by osc_io_submit, so
2121                                  *    page locked;
2122                                  *  - no request in flight
2123                                  *  - no subsequent request
2124                                  * The system will be in live-lock state,
2125                                  * because there is no chance to call
2126                                  * osc_io_unplug() and osc_check_rpcs() any
2127                                  * more. pdflush can't help in this case,
2128                                  * because it might be blocked at grabbing
2129                                  * the page lock as we mentioned.
2130                                  *
2131                                  * Anyway, continue to drain pages. */
2132                                 /* break; */
2133                         }
2134                 }
2135                 if (osc_makes_rpc(cli, osc, OBD_BRW_READ)) {
2136                         rc = osc_send_read_rpc(env, cli, osc, pol);
2137                         if (rc < 0)
2138                                 CERROR("Read request failed with %d\n", rc);
2139                 }
2140                 osc_object_unlock(osc);
2141
2142                 osc_list_maint(cli, osc);
2143                 lu_object_ref_del_at(&obj->co_lu, &link, "check",
2144                                      cfs_current());
2145                 cl_object_put(env, obj);
2146
2147                 client_obd_list_lock(&cli->cl_loi_list_lock);
2148         }
2149 }
2150
2151 static int osc_io_unplug0(const struct lu_env *env, struct client_obd *cli,
2152                           struct osc_object *osc, pdl_policy_t pol, int async)
2153 {
2154         int rc = 0;
2155
2156         if (osc != NULL && osc_list_maint(cli, osc) == 0)
2157                 return 0;
2158
2159         if (!async) {
2160                 /* disable osc_lru_shrink() temporarily to avoid
2161                  * potential stack overrun problem. LU-2859 */
2162                 cfs_atomic_inc(&cli->cl_lru_shrinkers);
2163                 client_obd_list_lock(&cli->cl_loi_list_lock);
2164                 osc_check_rpcs(env, cli, pol);
2165                 client_obd_list_unlock(&cli->cl_loi_list_lock);
2166                 cfs_atomic_dec(&cli->cl_lru_shrinkers);
2167         } else {
2168                 CDEBUG(D_CACHE, "Queue writeback work for client %p.\n", cli);
2169                 LASSERT(cli->cl_writeback_work != NULL);
2170                 rc = ptlrpcd_queue_work(cli->cl_writeback_work);
2171         }
2172         return rc;
2173 }
2174
2175 static int osc_io_unplug_async(const struct lu_env *env,
2176                                 struct client_obd *cli, struct osc_object *osc)
2177 {
2178         /* XXX: policy is no use actually. */
2179         return osc_io_unplug0(env, cli, osc, PDL_POLICY_ROUND, 1);
2180 }
2181
2182 void osc_io_unplug(const struct lu_env *env, struct client_obd *cli,
2183                    struct osc_object *osc, pdl_policy_t pol)
2184 {
2185         (void)osc_io_unplug0(env, cli, osc, pol, 0);
2186 }
2187
2188 int osc_prep_async_page(struct osc_object *osc, struct osc_page *ops,
2189                         struct page *page, loff_t offset)
2190 {
2191         struct obd_export     *exp = osc_export(osc);
2192         struct osc_async_page *oap = &ops->ops_oap;
2193         ENTRY;
2194
2195         if (!page)
2196                 return cfs_size_round(sizeof(*oap));
2197
2198         oap->oap_magic = OAP_MAGIC;
2199         oap->oap_cli = &exp->exp_obd->u.cli;
2200         oap->oap_obj = osc;
2201
2202         oap->oap_page = page;
2203         oap->oap_obj_off = offset;
2204         LASSERT(!(offset & ~CFS_PAGE_MASK));
2205
2206         if (!client_is_remote(exp) && cfs_capable(CFS_CAP_SYS_RESOURCE))
2207                 oap->oap_brw_flags = OBD_BRW_NOQUOTA;
2208
2209         CFS_INIT_LIST_HEAD(&oap->oap_pending_item);
2210         CFS_INIT_LIST_HEAD(&oap->oap_rpc_item);
2211
2212         spin_lock_init(&oap->oap_lock);
2213         CDEBUG(D_INFO, "oap %p page %p obj off "LPU64"\n",
2214                oap, page, oap->oap_obj_off);
2215         RETURN(0);
2216 }
2217
2218 int osc_queue_async_io(const struct lu_env *env, struct cl_io *io,
2219                        struct osc_page *ops)
2220 {
2221         struct osc_io *oio = osc_env_io(env);
2222         struct osc_extent     *ext = NULL;
2223         struct osc_async_page *oap = &ops->ops_oap;
2224         struct client_obd     *cli = oap->oap_cli;
2225         struct osc_object     *osc = oap->oap_obj;
2226         pgoff_t index;
2227         int    grants = 0;
2228         int    brw_flags = OBD_BRW_ASYNC;
2229         int    cmd = OBD_BRW_WRITE;
2230         int    need_release = 0;
2231         int    rc = 0;
2232         ENTRY;
2233
2234         if (oap->oap_magic != OAP_MAGIC)
2235                 RETURN(-EINVAL);
2236
2237         if (cli->cl_import == NULL || cli->cl_import->imp_invalid)
2238                 RETURN(-EIO);
2239
2240         if (!cfs_list_empty(&oap->oap_pending_item) ||
2241             !cfs_list_empty(&oap->oap_rpc_item))
2242                 RETURN(-EBUSY);
2243
2244         /* Set the OBD_BRW_SRVLOCK before the page is queued. */
2245         brw_flags |= ops->ops_srvlock ? OBD_BRW_SRVLOCK : 0;
2246         if (!client_is_remote(osc_export(osc)) &&
2247             cfs_capable(CFS_CAP_SYS_RESOURCE)) {
2248                 brw_flags |= OBD_BRW_NOQUOTA;
2249                 cmd |= OBD_BRW_NOQUOTA;
2250         }
2251
2252         /* check if the file's owner/group is over quota */
2253         if (!(cmd & OBD_BRW_NOQUOTA)) {
2254                 struct cl_object *obj;
2255                 struct cl_attr   *attr;
2256                 unsigned int qid[MAXQUOTAS];
2257
2258                 obj = cl_object_top(&osc->oo_cl);
2259                 attr = &osc_env_info(env)->oti_attr;
2260
2261                 cl_object_attr_lock(obj);
2262                 rc = cl_object_attr_get(env, obj, attr);
2263                 cl_object_attr_unlock(obj);
2264
2265                 qid[USRQUOTA] = attr->cat_uid;
2266                 qid[GRPQUOTA] = attr->cat_gid;
2267                 if (rc == 0 && osc_quota_chkdq(cli, qid) == NO_QUOTA)
2268                         rc = -EDQUOT;
2269                 if (rc)
2270                         RETURN(rc);
2271         }
2272
2273         oap->oap_cmd = cmd;
2274         oap->oap_page_off = ops->ops_from;
2275         oap->oap_count = ops->ops_to - ops->ops_from;
2276         oap->oap_async_flags = 0;
2277         oap->oap_brw_flags = brw_flags;
2278
2279         OSC_IO_DEBUG(osc, "oap %p page %p added for cmd %d\n",
2280                      oap, oap->oap_page, oap->oap_cmd & OBD_BRW_RWMASK);
2281
2282         index = oap2cl_page(oap)->cp_index;
2283
2284         /* Add this page into extent by the following steps:
2285          * 1. if there exists an active extent for this IO, mostly this page
2286          *    can be added to the active extent and sometimes we need to
2287          *    expand extent to accomodate this page;
2288          * 2. otherwise, a new extent will be allocated. */
2289
2290         ext = oio->oi_active;
2291         if (ext != NULL && ext->oe_start <= index && ext->oe_max_end >= index) {
2292                 /* one chunk plus extent overhead must be enough to write this
2293                  * page */
2294                 grants = (1 << cli->cl_chunkbits) + cli->cl_extent_tax;
2295                 if (ext->oe_end >= index)
2296                         grants = 0;
2297
2298                 /* it doesn't need any grant to dirty this page */
2299                 client_obd_list_lock(&cli->cl_loi_list_lock);
2300                 rc = osc_enter_cache_try(cli, oap, grants, 0);
2301                 client_obd_list_unlock(&cli->cl_loi_list_lock);
2302                 if (rc == 0) { /* try failed */
2303                         grants = 0;
2304                         need_release = 1;
2305                 } else if (ext->oe_end < index) {
2306                         int tmp = grants;
2307                         /* try to expand this extent */
2308                         rc = osc_extent_expand(ext, index, &tmp);
2309                         if (rc < 0) {
2310                                 need_release = 1;
2311                                 /* don't free reserved grant */
2312                         } else {
2313                                 OSC_EXTENT_DUMP(D_CACHE, ext,
2314                                                 "expanded for %lu.\n", index);
2315                                 osc_unreserve_grant(cli, grants, tmp);
2316                                 grants = 0;
2317                         }
2318                 }
2319                 rc = 0;
2320         } else if (ext != NULL) {
2321                 /* index is located outside of active extent */
2322                 need_release = 1;
2323         }
2324         if (need_release) {
2325                 osc_extent_release(env, ext);
2326                 oio->oi_active = NULL;
2327                 ext = NULL;
2328         }
2329
2330         if (ext == NULL) {
2331                 int tmp = (1 << cli->cl_chunkbits) + cli->cl_extent_tax;
2332
2333                 /* try to find new extent to cover this page */
2334                 LASSERT(oio->oi_active == NULL);
2335                 /* we may have allocated grant for this page if we failed
2336                  * to expand the previous active extent. */
2337                 LASSERT(ergo(grants > 0, grants >= tmp));
2338
2339                 rc = 0;
2340                 if (grants == 0) {
2341                         /* we haven't allocated grant for this page. */
2342                         rc = osc_enter_cache(env, cli, oap, tmp);
2343                         if (rc == 0)
2344                                 grants = tmp;
2345                 }
2346
2347                 tmp = grants;
2348                 if (rc == 0) {
2349                         ext = osc_extent_find(env, osc, index, &tmp);
2350                         if (IS_ERR(ext)) {
2351                                 LASSERT(tmp == grants);
2352                                 osc_exit_cache(cli, oap);
2353                                 rc = PTR_ERR(ext);
2354                                 ext = NULL;
2355                         } else {
2356                                 oio->oi_active = ext;
2357                         }
2358                 }
2359                 if (grants > 0)
2360                         osc_unreserve_grant(cli, grants, tmp);
2361         }
2362
2363         LASSERT(ergo(rc == 0, ext != NULL));
2364         if (ext != NULL) {
2365                 EASSERTF(ext->oe_end >= index && ext->oe_start <= index,
2366                          ext, "index = %lu.\n", index);
2367                 LASSERT((oap->oap_brw_flags & OBD_BRW_FROM_GRANT) != 0);
2368
2369                 osc_object_lock(osc);
2370                 if (ext->oe_nr_pages == 0)
2371                         ext->oe_srvlock = ops->ops_srvlock;
2372                 else
2373                         LASSERT(ext->oe_srvlock == ops->ops_srvlock);
2374                 ++ext->oe_nr_pages;
2375                 cfs_list_add_tail(&oap->oap_pending_item, &ext->oe_pages);
2376                 osc_object_unlock(osc);
2377         }
2378         RETURN(rc);
2379 }
2380
2381 int osc_teardown_async_page(const struct lu_env *env,
2382                             struct osc_object *obj, struct osc_page *ops)
2383 {
2384         struct osc_async_page *oap = &ops->ops_oap;
2385         struct osc_extent     *ext = NULL;
2386         int rc = 0;
2387         ENTRY;
2388
2389         LASSERT(oap->oap_magic == OAP_MAGIC);
2390
2391         CDEBUG(D_INFO, "teardown oap %p page %p at index %lu.\n",
2392                oap, ops, oap2cl_page(oap)->cp_index);
2393
2394         osc_object_lock(obj);
2395         if (!cfs_list_empty(&oap->oap_rpc_item)) {
2396                 CDEBUG(D_CACHE, "oap %p is not in cache.\n", oap);
2397                 rc = -EBUSY;
2398         } else if (!cfs_list_empty(&oap->oap_pending_item)) {
2399                 ext = osc_extent_lookup(obj, oap2cl_page(oap)->cp_index);
2400                 /* only truncated pages are allowed to be taken out.
2401                  * See osc_extent_truncate() and osc_cache_truncate_start()
2402                  * for details. */
2403                 if (ext != NULL && ext->oe_state != OES_TRUNC) {
2404                         OSC_EXTENT_DUMP(D_ERROR, ext, "trunc at %lu.\n",
2405                                         oap2cl_page(oap)->cp_index);
2406                         rc = -EBUSY;
2407                 }
2408         }
2409         osc_object_unlock(obj);
2410         if (ext != NULL)
2411                 osc_extent_put(env, ext);
2412         RETURN(rc);
2413 }
2414
2415 /**
2416  * This is called when a page is picked up by kernel to write out.
2417  *
2418  * We should find out the corresponding extent and add the whole extent
2419  * into urgent list. The extent may be being truncated or used, handle it
2420  * carefully.
2421  */
2422 int osc_flush_async_page(const struct lu_env *env, struct cl_io *io,
2423                          struct osc_page *ops)
2424 {
2425         struct osc_extent *ext   = NULL;
2426         struct osc_object *obj   = cl2osc(ops->ops_cl.cpl_obj);
2427         struct cl_page    *cp    = ops->ops_cl.cpl_page;
2428         pgoff_t            index = cp->cp_index;
2429         struct osc_async_page *oap = &ops->ops_oap;
2430         bool unplug = false;
2431         int rc = 0;
2432         ENTRY;
2433
2434         osc_object_lock(obj);
2435         ext = osc_extent_lookup(obj, index);
2436         if (ext == NULL) {
2437                 osc_extent_tree_dump(D_ERROR, obj);
2438                 LASSERTF(0, "page index %lu is NOT covered.\n", index);
2439         }
2440
2441         switch (ext->oe_state) {
2442         case OES_RPC:
2443         case OES_LOCK_DONE:
2444                 CL_PAGE_DEBUG(D_ERROR, env, cl_page_top(cp),
2445                               "flush an in-rpc page?\n");
2446                 LASSERT(0);
2447                 break;
2448         case OES_LOCKING:
2449                 /* If we know this extent is being written out, we should abort
2450                  * so that the writer can make this page ready. Otherwise, there
2451                  * exists a deadlock problem because other process can wait for
2452                  * page writeback bit holding page lock; and meanwhile in
2453                  * vvp_page_make_ready(), we need to grab page lock before
2454                  * really sending the RPC. */
2455         case OES_TRUNC:
2456                 /* race with truncate, page will be redirtied */
2457                 GOTO(out, rc = -EAGAIN);
2458         default:
2459                 break;
2460         }
2461
2462         rc = cl_page_prep(env, io, cl_page_top(cp), CRT_WRITE);
2463         if (rc)
2464                 GOTO(out, rc);
2465
2466         spin_lock(&oap->oap_lock);
2467         oap->oap_async_flags |= ASYNC_READY|ASYNC_URGENT;
2468         spin_unlock(&oap->oap_lock);
2469
2470         if (memory_pressure_get())
2471                 ext->oe_memalloc = 1;
2472
2473         ext->oe_urgent = 1;
2474         if (ext->oe_state == OES_CACHE) {
2475                 OSC_EXTENT_DUMP(D_CACHE, ext,
2476                                 "flush page %p make it urgent.\n", oap);
2477                 if (cfs_list_empty(&ext->oe_link))
2478                         cfs_list_add_tail(&ext->oe_link, &obj->oo_urgent_exts);
2479                 unplug = true;
2480         }
2481         rc = 0;
2482         EXIT;
2483
2484 out:
2485         osc_object_unlock(obj);
2486         osc_extent_put(env, ext);
2487         if (unplug)
2488                 osc_io_unplug_async(env, osc_cli(obj), obj);
2489         return rc;
2490 }
2491
2492 /**
2493  * this is called when a sync waiter receives an interruption.  Its job is to
2494  * get the caller woken as soon as possible.  If its page hasn't been put in an
2495  * rpc yet it can dequeue immediately.  Otherwise it has to mark the rpc as
2496  * desiring interruption which will forcefully complete the rpc once the rpc
2497  * has timed out.
2498  */
2499 int osc_cancel_async_page(const struct lu_env *env, struct osc_page *ops)
2500 {
2501         struct osc_async_page *oap = &ops->ops_oap;
2502         struct osc_object     *obj = oap->oap_obj;
2503         struct client_obd     *cli = osc_cli(obj);
2504         struct osc_extent     *ext;
2505         struct osc_extent     *found = NULL;
2506         cfs_list_t            *plist;
2507         pgoff_t index = oap2cl_page(oap)->cp_index;
2508         int     rc = -EBUSY;
2509         int     cmd;
2510         ENTRY;
2511
2512         LASSERT(!oap->oap_interrupted);
2513         oap->oap_interrupted = 1;
2514
2515         /* Find out the caching extent */
2516         osc_object_lock(obj);
2517         if (oap->oap_cmd & OBD_BRW_WRITE) {
2518                 plist = &obj->oo_urgent_exts;
2519                 cmd   = OBD_BRW_WRITE;
2520         } else {
2521                 plist = &obj->oo_reading_exts;
2522                 cmd   = OBD_BRW_READ;
2523         }
2524         cfs_list_for_each_entry(ext, plist, oe_link) {
2525                 if (ext->oe_start <= index && ext->oe_end >= index) {
2526                         LASSERT(ext->oe_state == OES_LOCK_DONE);
2527                         /* For OES_LOCK_DONE state extent, it has already held
2528                          * a refcount for RPC. */
2529                         found = osc_extent_get(ext);
2530                         break;
2531                 }
2532         }
2533         if (found != NULL) {
2534                 cfs_list_del_init(&found->oe_link);
2535                 osc_update_pending(obj, cmd, -found->oe_nr_pages);
2536                 osc_object_unlock(obj);
2537
2538                 osc_extent_finish(env, found, 0, -EINTR);
2539                 osc_extent_put(env, found);
2540                 rc = 0;
2541         } else {
2542                 osc_object_unlock(obj);
2543                 /* ok, it's been put in an rpc. only one oap gets a request
2544                  * reference */
2545                 if (oap->oap_request != NULL) {
2546                         ptlrpc_mark_interrupted(oap->oap_request);
2547                         ptlrpcd_wake(oap->oap_request);
2548                         ptlrpc_req_finished(oap->oap_request);
2549                         oap->oap_request = NULL;
2550                 }
2551         }
2552
2553         osc_list_maint(cli, obj);
2554         RETURN(rc);
2555 }
2556
2557 int osc_queue_sync_pages(const struct lu_env *env, struct osc_object *obj,
2558                          cfs_list_t *list, int cmd, int brw_flags)
2559 {
2560         struct client_obd     *cli = osc_cli(obj);
2561         struct osc_extent     *ext;
2562         struct osc_async_page *oap;
2563         int     page_count = 0;
2564         int     mppr       = cli->cl_max_pages_per_rpc;
2565         pgoff_t start      = CL_PAGE_EOF;
2566         pgoff_t end        = 0;
2567         ENTRY;
2568
2569         cfs_list_for_each_entry(oap, list, oap_pending_item) {
2570                 struct cl_page *cp = oap2cl_page(oap);
2571                 if (cp->cp_index > end)
2572                         end = cp->cp_index;
2573                 if (cp->cp_index < start)
2574                         start = cp->cp_index;
2575                 ++page_count;
2576                 mppr <<= (page_count > mppr);
2577         }
2578
2579         ext = osc_extent_alloc(obj);
2580         if (ext == NULL) {
2581                 cfs_list_for_each_entry(oap, list, oap_pending_item) {
2582                         cfs_list_del_init(&oap->oap_pending_item);
2583                         osc_ap_completion(env, cli, oap, 0, -ENOMEM);
2584                 }
2585                 RETURN(-ENOMEM);
2586         }
2587
2588         ext->oe_rw = !!(cmd & OBD_BRW_READ);
2589         ext->oe_urgent = 1;
2590         ext->oe_start = start;
2591         ext->oe_end = ext->oe_max_end = end;
2592         ext->oe_obj = obj;
2593         ext->oe_srvlock = !!(brw_flags & OBD_BRW_SRVLOCK);
2594         ext->oe_nr_pages = page_count;
2595         ext->oe_mppr = mppr;
2596         cfs_list_splice_init(list, &ext->oe_pages);
2597
2598         osc_object_lock(obj);
2599         /* Reuse the initial refcount for RPC, don't drop it */
2600         osc_extent_state_set(ext, OES_LOCK_DONE);
2601         if (cmd & OBD_BRW_WRITE) {
2602                 cfs_list_add_tail(&ext->oe_link, &obj->oo_urgent_exts);
2603                 osc_update_pending(obj, OBD_BRW_WRITE, page_count);
2604         } else {
2605                 cfs_list_add_tail(&ext->oe_link, &obj->oo_reading_exts);
2606                 osc_update_pending(obj, OBD_BRW_READ, page_count);
2607         }
2608         osc_object_unlock(obj);
2609
2610         osc_io_unplug(env, cli, obj, PDL_POLICY_ROUND);
2611         RETURN(0);
2612 }
2613
2614 /**
2615  * Called by osc_io_setattr_start() to freeze and destroy covering extents.
2616  */
2617 int osc_cache_truncate_start(const struct lu_env *env, struct osc_io *oio,
2618                              struct osc_object *obj, __u64 size)
2619 {
2620         struct client_obd *cli = osc_cli(obj);
2621         struct osc_extent *ext;
2622         struct osc_extent *waiting = NULL;
2623         pgoff_t index;
2624         CFS_LIST_HEAD(list);
2625         int result = 0;
2626         bool partial;
2627         ENTRY;
2628
2629         /* pages with index greater or equal to index will be truncated. */
2630         index = cl_index(osc2cl(obj), size);
2631         partial = size > cl_offset(osc2cl(obj), index);
2632
2633 again:
2634         osc_object_lock(obj);
2635         ext = osc_extent_search(obj, index);
2636         if (ext == NULL)
2637                 ext = first_extent(obj);
2638         else if (ext->oe_end < index)
2639                 ext = next_extent(ext);
2640         while (ext != NULL) {
2641                 EASSERT(ext->oe_state != OES_TRUNC, ext);
2642
2643                 if (ext->oe_state > OES_CACHE || ext->oe_urgent) {
2644                         /* if ext is in urgent state, it means there must exist
2645                          * a page already having been flushed by write_page().
2646                          * We have to wait for this extent because we can't
2647                          * truncate that page. */
2648                         LASSERT(!ext->oe_hp);
2649                         OSC_EXTENT_DUMP(D_CACHE, ext,
2650                                         "waiting for busy extent\n");
2651                         waiting = osc_extent_get(ext);
2652                         break;
2653                 }
2654
2655                 OSC_EXTENT_DUMP(D_CACHE, ext, "try to trunc:"LPU64".\n", size);
2656
2657                 osc_extent_get(ext);
2658                 if (ext->oe_state == OES_ACTIVE) {
2659                         /* though we grab inode mutex for write path, but we
2660                          * release it before releasing extent(in osc_io_end()),
2661                          * so there is a race window that an extent is still
2662                          * in OES_ACTIVE when truncate starts. */
2663                         LASSERT(!ext->oe_trunc_pending);
2664                         ext->oe_trunc_pending = 1;
2665                 } else {
2666                         EASSERT(ext->oe_state == OES_CACHE, ext);
2667                         osc_extent_state_set(ext, OES_TRUNC);
2668                         osc_update_pending(obj, OBD_BRW_WRITE,
2669                                            -ext->oe_nr_pages);
2670                 }
2671                 EASSERT(cfs_list_empty(&ext->oe_link), ext);
2672                 cfs_list_add_tail(&ext->oe_link, &list);
2673
2674                 ext = next_extent(ext);
2675         }
2676         osc_object_unlock(obj);
2677
2678         osc_list_maint(cli, obj);
2679
2680         while (!cfs_list_empty(&list)) {
2681                 int rc;
2682
2683                 ext = cfs_list_entry(list.next, struct osc_extent, oe_link);
2684                 cfs_list_del_init(&ext->oe_link);
2685
2686                 /* extent may be in OES_ACTIVE state because inode mutex
2687                  * is released before osc_io_end() in file write case */
2688                 if (ext->oe_state != OES_TRUNC)
2689                         osc_extent_wait(env, ext, OES_TRUNC);
2690
2691                 rc = osc_extent_truncate(ext, index, partial);
2692                 if (rc < 0) {
2693                         if (result == 0)
2694                                 result = rc;
2695
2696                         OSC_EXTENT_DUMP(D_ERROR, ext,
2697                                         "truncate error %d\n", rc);
2698                 } else if (ext->oe_nr_pages == 0) {
2699                         osc_extent_remove(ext);
2700                 } else {
2701                         /* this must be an overlapped extent which means only
2702                          * part of pages in this extent have been truncated.
2703                          */
2704                         EASSERTF(ext->oe_start <= index, ext,
2705                                  "trunc index = %lu/%d.\n", index, partial);
2706                         /* fix index to skip this partially truncated extent */
2707                         index = ext->oe_end + 1;
2708                         partial = false;
2709
2710                         /* we need to hold this extent in OES_TRUNC state so
2711                          * that no writeback will happen. This is to avoid
2712                          * BUG 17397. */
2713                         LASSERT(oio->oi_trunc == NULL);
2714                         oio->oi_trunc = osc_extent_get(ext);
2715                         OSC_EXTENT_DUMP(D_CACHE, ext,
2716                                         "trunc at "LPU64"\n", size);
2717                 }
2718                 osc_extent_put(env, ext);
2719         }
2720         if (waiting != NULL) {
2721                 int rc;
2722
2723                 /* ignore the result of osc_extent_wait the write initiator
2724                  * should take care of it. */
2725                 rc = osc_extent_wait(env, waiting, OES_INV);
2726                 if (rc < 0)
2727                         OSC_EXTENT_DUMP(D_CACHE, waiting, "error: %d.\n", rc);
2728
2729                 osc_extent_put(env, waiting);
2730                 waiting = NULL;
2731                 goto again;
2732         }
2733         RETURN(result);
2734 }
2735
2736 /**
2737  * Called after osc_io_setattr_end to add oio->oi_trunc back to cache.
2738  */
2739 void osc_cache_truncate_end(const struct lu_env *env, struct osc_io *oio,
2740                             struct osc_object *obj)
2741 {
2742         struct osc_extent *ext = oio->oi_trunc;
2743
2744         oio->oi_trunc = NULL;
2745         if (ext != NULL) {
2746                 bool unplug = false;
2747
2748                 EASSERT(ext->oe_nr_pages > 0, ext);
2749                 EASSERT(ext->oe_state == OES_TRUNC, ext);
2750                 EASSERT(!ext->oe_urgent, ext);
2751
2752                 OSC_EXTENT_DUMP(D_CACHE, ext, "trunc -> cache.\n");
2753                 osc_object_lock(obj);
2754                 osc_extent_state_set(ext, OES_CACHE);
2755                 if (ext->oe_fsync_wait && !ext->oe_urgent) {
2756                         ext->oe_urgent = 1;
2757                         cfs_list_move_tail(&ext->oe_link, &obj->oo_urgent_exts);
2758                         unplug = true;
2759                 }
2760                 osc_update_pending(obj, OBD_BRW_WRITE, ext->oe_nr_pages);
2761                 osc_object_unlock(obj);
2762                 osc_extent_put(env, ext);
2763
2764                 if (unplug)
2765                         osc_io_unplug_async(env, osc_cli(obj), obj);
2766         }
2767 }
2768
2769 /**
2770  * Wait for extents in a specific range to be written out.
2771  * The caller must have called osc_cache_writeback_range() to issue IO
2772  * otherwise it will take a long time for this function to finish.
2773  *
2774  * Caller must hold inode_mutex , or cancel exclusive dlm lock so that
2775  * nobody else can dirty this range of file while we're waiting for
2776  * extents to be written.
2777  */
2778 int osc_cache_wait_range(const struct lu_env *env, struct osc_object *obj,
2779                          pgoff_t start, pgoff_t end)
2780 {
2781         struct osc_extent *ext;
2782         pgoff_t index = start;
2783         int     result = 0;
2784         ENTRY;
2785
2786 again:
2787         osc_object_lock(obj);
2788         ext = osc_extent_search(obj, index);
2789         if (ext == NULL)
2790                 ext = first_extent(obj);
2791         else if (ext->oe_end < index)
2792                 ext = next_extent(ext);
2793         while (ext != NULL) {
2794                 int rc;
2795
2796                 if (ext->oe_start > end)
2797                         break;
2798
2799                 if (!ext->oe_fsync_wait) {
2800                         ext = next_extent(ext);
2801                         continue;
2802                 }
2803
2804                 EASSERT(ergo(ext->oe_state == OES_CACHE,
2805                              ext->oe_hp || ext->oe_urgent), ext);
2806                 EASSERT(ergo(ext->oe_state == OES_ACTIVE,
2807                              !ext->oe_hp && ext->oe_urgent), ext);
2808
2809                 index = ext->oe_end + 1;
2810                 osc_extent_get(ext);
2811                 osc_object_unlock(obj);
2812
2813                 rc = osc_extent_wait(env, ext, OES_INV);
2814                 if (result == 0)
2815                         result = rc;
2816                 osc_extent_put(env, ext);
2817                 goto again;
2818         }
2819         osc_object_unlock(obj);
2820
2821         OSC_IO_DEBUG(obj, "sync file range.\n");
2822         RETURN(result);
2823 }
2824
2825 /**
2826  * Called to write out a range of osc object.
2827  *
2828  * @hp     : should be set this is caused by lock cancel;
2829  * @discard: is set if dirty pages should be dropped - file will be deleted or
2830  *         truncated, this implies there is no partially discarding extents.
2831  *
2832  * Return how many pages will be issued, or error code if error occurred.
2833  */
2834 int osc_cache_writeback_range(const struct lu_env *env, struct osc_object *obj,
2835                               pgoff_t start, pgoff_t end, int hp, int discard)
2836 {
2837         struct osc_extent *ext;
2838         CFS_LIST_HEAD(discard_list);
2839         bool unplug = false;
2840         int result = 0;
2841         ENTRY;
2842
2843         osc_object_lock(obj);
2844         ext = osc_extent_search(obj, start);
2845         if (ext == NULL)
2846                 ext = first_extent(obj);
2847         else if (ext->oe_end < start)
2848                 ext = next_extent(ext);
2849         while (ext != NULL) {
2850                 if (ext->oe_start > end)
2851                         break;
2852
2853                 ext->oe_fsync_wait = 1;
2854                 switch (ext->oe_state) {
2855                 case OES_CACHE:
2856                         result += ext->oe_nr_pages;
2857                         if (!discard) {
2858                                 cfs_list_t *list = NULL;
2859                                 if (hp) {
2860                                         EASSERT(!ext->oe_hp, ext);
2861                                         ext->oe_hp = 1;
2862                                         list = &obj->oo_hp_exts;
2863                                 } else if (!ext->oe_urgent) {
2864                                         ext->oe_urgent = 1;
2865                                         list = &obj->oo_urgent_exts;
2866                                 }
2867                                 if (list != NULL)
2868                                         cfs_list_move_tail(&ext->oe_link, list);
2869                                 unplug = true;
2870                         } else {
2871                                 /* the only discarder is lock cancelling, so
2872                                  * [start, end] must contain this extent */
2873                                 EASSERT(ext->oe_start >= start &&
2874                                         ext->oe_max_end <= end, ext);
2875                                 osc_extent_state_set(ext, OES_LOCKING);
2876                                 ext->oe_owner = cfs_current();
2877                                 cfs_list_move_tail(&ext->oe_link,
2878                                                    &discard_list);
2879                                 osc_update_pending(obj, OBD_BRW_WRITE,
2880                                                    -ext->oe_nr_pages);
2881                         }
2882                         break;
2883                 case OES_ACTIVE:
2884                         /* It's pretty bad to wait for ACTIVE extents, because
2885                          * we don't know how long we will wait for it to be
2886                          * flushed since it may be blocked at awaiting more
2887                          * grants. We do this for the correctness of fsync. */
2888                         LASSERT(hp == 0 && discard == 0);
2889                         ext->oe_urgent = 1;
2890                         break;
2891                 case OES_TRUNC:
2892                         /* this extent is being truncated, can't do anything
2893                          * for it now. it will be set to urgent after truncate
2894                          * is finished in osc_cache_truncate_end(). */
2895                 default:
2896                         break;
2897                 }
2898                 ext = next_extent(ext);
2899         }
2900         osc_object_unlock(obj);
2901
2902         LASSERT(ergo(!discard, cfs_list_empty(&discard_list)));
2903         if (!cfs_list_empty(&discard_list)) {
2904                 struct osc_extent *tmp;
2905                 int rc;
2906
2907                 osc_list_maint(osc_cli(obj), obj);
2908                 cfs_list_for_each_entry_safe(ext, tmp, &discard_list, oe_link) {
2909                         cfs_list_del_init(&ext->oe_link);
2910                         EASSERT(ext->oe_state == OES_LOCKING, ext);
2911
2912                         /* Discard caching pages. We don't actually write this
2913                          * extent out but we complete it as if we did. */
2914                         rc = osc_extent_make_ready(env, ext);
2915                         if (unlikely(rc < 0)) {
2916                                 OSC_EXTENT_DUMP(D_ERROR, ext,
2917                                                 "make_ready returned %d\n", rc);
2918                                 if (result >= 0)
2919                                         result = rc;
2920                         }
2921
2922                         /* finish the extent as if the pages were sent */
2923                         osc_extent_finish(env, ext, 0, 0);
2924                 }
2925         }
2926
2927         if (unplug)
2928                 osc_io_unplug(env, osc_cli(obj), obj, PDL_POLICY_ROUND);
2929
2930         if (hp || discard) {
2931                 int rc;
2932                 rc = osc_cache_wait_range(env, obj, start, end);
2933                 if (result >= 0 && rc < 0)
2934                         result = rc;
2935         }
2936
2937         OSC_IO_DEBUG(obj, "pageout [%lu, %lu], %d.\n", start, end, result);
2938         RETURN(result);
2939 }
2940
2941 /** @} osc */