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