lustre/osc/osc_cache.c

   1 /*
   2  * GPL HEADER START
   3  *
   4  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 only,
   8  * as published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful, but
  11  * WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * General Public License version 2 for more details (a copy is included
  14  * in the LICENSE file that accompanied this code).
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * version 2 along with this program; If not, see
  18  * http://www.sun.com/software/products/lustre/docs/GPLv2.pdf
  19  *
  20  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
  21  * CA 95054 USA or visit www.sun.com if you need additional information or
  22  * have any questions.
  23  *
  24  * GPL HEADER END
  25  */
  26 /*
  27  * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
  28  * Use is subject to license terms.
  29  *
  30  * Copyright (c) 2012, 2013, Intel Corporation.
  31  *
  32  */
  33 /*
  34  * This file is part of Lustre, http://www.lustre.org/
  35  * Lustre is a trademark of Sun Microsystems, Inc.
  36  *
  37  * osc cache management.
  38  *
  39  * Author: Jinshan Xiong <jinshan.xiong@whamcloud.com>
  40  */
  41
  42 #define DEBUG_SUBSYSTEM S_OSC
  43
  44 #include "osc_cl_internal.h"
  45 #include "osc_internal.h"
  46
  47 static int extent_debug; /* set it to be true for more debug */
  48
  49 static void osc_update_pending(struct osc_object *obj, int cmd, int delta);
  50 static int osc_extent_wait(const struct lu_env *env, struct osc_extent *ext,
  51                            int state);
  52 static void osc_ap_completion(const struct lu_env *env, struct client_obd *cli,
  53                               struct osc_async_page *oap, int sent, int rc);
  54 static int osc_make_ready(const struct lu_env *env, struct osc_async_page *oap,
  55                           int cmd);
  56 static int osc_refresh_count(const struct lu_env *env,
  57                              struct osc_async_page *oap, int cmd);
  58 static int osc_io_unplug_async(const struct lu_env *env,
  59                                struct client_obd *cli, struct osc_object *osc);
  60 static void osc_free_grant(struct client_obd *cli, unsigned int nr_pages,
  61                            unsigned int lost_grant);
  62
  63 static void osc_extent_tree_dump0(int level, struct osc_object *obj,
  64                                   const char *func, int line);
  65 #define osc_extent_tree_dump(lvl, obj) \
  66         osc_extent_tree_dump0(lvl, obj, __func__, __LINE__)
  67
  68 /** \addtogroup osc
  69  *  @{
  70  */
  71
  72 /* ------------------ osc extent ------------------ */
  73 static inline char *ext_flags(struct osc_extent *ext, char *flags)
  74 {
  75         char *buf = flags;
  76         *buf++ = ext->oe_rw ? 'r' : 'w';
  77         if (ext->oe_intree)
  78                 *buf++ = 'i';
  79         if (ext->oe_srvlock)
  80                 *buf++ = 's';
  81         if (ext->oe_hp)
  82                 *buf++ = 'h';
  83         if (ext->oe_urgent)
  84                 *buf++ = 'u';
  85         if (ext->oe_memalloc)
  86                 *buf++ = 'm';
  87         if (ext->oe_trunc_pending)
  88                 *buf++ = 't';
  89         if (ext->oe_fsync_wait)
  90                 *buf++ = 'Y';
  91         *buf = 0;
  92         return flags;
  93 }
  94
  95 static inline char list_empty_marker(cfs_list_t *list)
  96 {
  97         return cfs_list_empty(list) ? '-' : '+';
  98 }
  99
 100 #define EXTSTR       "[%lu -> %lu/%lu]"
 101 #define EXTPARA(ext) (ext)->oe_start, (ext)->oe_end, (ext)->oe_max_end
 102 static const char *oes_strings[] = {
 103         "inv", "active", "cache", "locking", "lockdone", "rpc", "trunc", NULL };
 104
 105 #define OSC_EXTENT_DUMP(lvl, extent, fmt, ...) do {                           \
 106         struct osc_extent *__ext = (extent);                                  \
 107         char __buf[16];                                                       \
 108                                                                               \
 109         CDEBUG(lvl,                                                           \
 110                 "extent %p@{" EXTSTR ", "                                     \
 111                 "[%d|%d|%c|%s|%s|%p], [%d|%d|%c|%c|%p|%u|%p]} " fmt,          \
 112                 /* ----- extent part 0 ----- */                               \
 113                 __ext, EXTPARA(__ext),                                        \
 114                 /* ----- part 1 ----- */                                      \
 115                 cfs_atomic_read(&__ext->oe_refc),                             \
 116                 cfs_atomic_read(&__ext->oe_users),                            \
 117                 list_empty_marker(&__ext->oe_link),                           \
 118                 oes_strings[__ext->oe_state], ext_flags(__ext, __buf),        \
 119                 __ext->oe_obj,                                                \
 120                 /* ----- part 2 ----- */                                      \
 121                 __ext->oe_grants, __ext->oe_nr_pages,                         \
 122                 list_empty_marker(&__ext->oe_pages),                          \
 123                 cfs_waitq_active(&__ext->oe_waitq) ? '+' : '-',               \
 124                 __ext->oe_osclock, __ext->oe_mppr, __ext->oe_owner,           \
 125                 /* ----- part 4 ----- */                                      \
 126                 ## __VA_ARGS__);                                              \
 127 } while (0)
 128
 129 #undef EASSERTF
 130 #define EASSERTF(expr, ext, fmt, args...) do {                          \
 131         if (!(expr)) {                                                  \
 132                 OSC_EXTENT_DUMP(D_ERROR, (ext), fmt, ##args);           \
 133                 osc_extent_tree_dump(D_ERROR, (ext)->oe_obj);           \
 134                 LASSERT(expr);                                          \
 135         }                                                               \
 136 } while (0)
 137
 138 #undef EASSERT
 139 #define EASSERT(expr, ext) EASSERTF(expr, ext, "\n")
 140
 141 static inline struct osc_extent *rb_extent(struct rb_node *n)
 142 {
 143         if (n == NULL)
 144                 return NULL;
 145
 146         return container_of(n, struct osc_extent, oe_node);
 147 }
 148
 149 static inline struct osc_extent *next_extent(struct osc_extent *ext)
 150 {
 151         if (ext == NULL)
 152                 return NULL;
 153
 154         LASSERT(ext->oe_intree);
 155         return rb_extent(rb_next(&ext->oe_node));
 156 }
 157
 158 static inline struct osc_extent *prev_extent(struct osc_extent *ext)
 159 {
 160         if (ext == NULL)
 161                 return NULL;
 162
 163         LASSERT(ext->oe_intree);
 164         return rb_extent(rb_prev(&ext->oe_node));
 165 }
 166
 167 static inline struct osc_extent *first_extent(struct osc_object *obj)
 168 {
 169         return rb_extent(rb_first(&obj->oo_root));
 170 }
 171
 172 /* object must be locked by caller. */
 173 static int osc_extent_sanity_check0(struct osc_extent *ext,
 174                                     const char *func, const int line)
 175 {
 176         struct osc_object *obj = ext->oe_obj;
 177         struct osc_async_page *oap;
 178         int page_count;
 179         int rc = 0;
 180
 181         if (!osc_object_is_locked(obj))
 182                 GOTO(out, rc = 9);
 183
 184         if (ext->oe_state >= OES_STATE_MAX)
 185                 GOTO(out, rc = 10);
 186
 187         if (cfs_atomic_read(&ext->oe_refc) <= 0)
 188                 GOTO(out, rc = 20);
 189
 190         if (cfs_atomic_read(&ext->oe_refc) < cfs_atomic_read(&ext->oe_users))
 191                 GOTO(out, rc = 30);
 192
 193         switch (ext->oe_state) {
 194         case OES_INV:
 195                 if (ext->oe_nr_pages > 0 || !cfs_list_empty(&ext->oe_pages))
 196                         GOTO(out, rc = 35);
 197                 GOTO(out, rc = 0);
 198                 break;
 199         case OES_ACTIVE:
 200                 if (cfs_atomic_read(&ext->oe_users) == 0)
 201                         GOTO(out, rc = 40);
 202                 if (ext->oe_hp)
 203                         GOTO(out, rc = 50);
 204                 if (ext->oe_fsync_wait && !ext->oe_urgent)
 205                         GOTO(out, rc = 55);
 206                 break;
 207         case OES_CACHE:
 208                 if (ext->oe_grants == 0)
 209                         GOTO(out, rc = 60);
 210                 if (ext->oe_fsync_wait && !ext->oe_urgent && !ext->oe_hp)
 211                         GOTO(out, rc = 65);
 212         default:
 213                 if (cfs_atomic_read(&ext->oe_users) > 0)
 214                         GOTO(out, rc = 70);
 215         }
 216
 217         if (ext->oe_max_end < ext->oe_end || ext->oe_end < ext->oe_start)
 218                 GOTO(out, rc = 80);
 219
 220         if (ext->oe_osclock == NULL && ext->oe_grants > 0)
 221                 GOTO(out, rc = 90);
 222
 223         if (ext->oe_osclock) {
 224                 struct cl_lock_descr *descr;
 225                 descr = &ext->oe_osclock->cll_descr;
 226                 if (!(descr->cld_start <= ext->oe_start &&
 227                       descr->cld_end >= ext->oe_max_end))
 228                         GOTO(out, rc = 100);
 229         }
 230
 231         if (ext->oe_nr_pages > ext->oe_mppr)
 232                 GOTO(out, rc = 105);
 233
 234         /* Do not verify page list if extent is in RPC. This is because an
 235          * in-RPC extent is supposed to be exclusively accessible w/o lock. */
 236         if (ext->oe_state > OES_CACHE)
 237                 GOTO(out, rc = 0);
 238
 239         if (!extent_debug)
 240                 GOTO(out, rc = 0);
 241
 242         page_count = 0;
 243         cfs_list_for_each_entry(oap, &ext->oe_pages, oap_pending_item) {
 244                 pgoff_t index = oap2cl_page(oap)->cp_index;
 245                 ++page_count;
 246                 if (index > ext->oe_end || index < ext->oe_start)
 247                         GOTO(out, rc = 110);
 248         }
 249         if (page_count != ext->oe_nr_pages)
 250                 GOTO(out, rc = 120);
 251
 252 out:
 253         if (rc != 0)
 254                 OSC_EXTENT_DUMP(D_ERROR, ext,
 255                                 "%s:%d sanity check %p failed with rc = %d\n",
 256                                 func, line, ext, rc);
 257         return rc;
 258 }
 259
 260 #define sanity_check_nolock(ext) \
 261         osc_extent_sanity_check0(ext, __func__, __LINE__)
 262
 263 #define sanity_check(ext) ({                                                   \
 264         int __res;                                                             \
 265         osc_object_lock((ext)->oe_obj);                                        \
 266         __res = sanity_check_nolock(ext);                                      \
 267         osc_object_unlock((ext)->oe_obj);                                      \
 268         __res;                                                                 \
 269 })
 270
 271
 272 /**
 273  * sanity check - to make sure there is no overlapped extent in the tree.
 274  */
 275 static int osc_extent_is_overlapped(struct osc_object *obj,
 276                                     struct osc_extent *ext)
 277 {
 278         struct osc_extent *tmp;
 279
 280         LASSERT(osc_object_is_locked(obj));
 281
 282         if (!extent_debug)
 283                 return 0;
 284
 285         for (tmp = first_extent(obj); tmp != NULL; tmp = next_extent(tmp)) {
 286                 if (tmp == ext)
 287                         continue;
 288                 if (tmp->oe_end >= ext->oe_start &&
 289                     tmp->oe_start <= ext->oe_end)
 290                         return 1;
 291         }
 292         return 0;
 293 }
 294
 295 static void osc_extent_state_set(struct osc_extent *ext, int state)
 296 {
 297         LASSERT(osc_object_is_locked(ext->oe_obj));
 298         LASSERT(state >= OES_INV && state < OES_STATE_MAX);
 299
 300         /* Never try to sanity check a state changing extent :-) */
 301         /* LASSERT(sanity_check_nolock(ext) == 0); */
 302
 303         /* TODO: validate the state machine */
 304         ext->oe_state = state;
 305         cfs_waitq_broadcast(&ext->oe_waitq);
 306 }
 307
 308 static struct osc_extent *osc_extent_alloc(struct osc_object *obj)
 309 {
 310         struct osc_extent *ext;
 311
 312         OBD_SLAB_ALLOC_PTR_GFP(ext, osc_extent_kmem, GFP_IOFS);
 313         if (ext == NULL)
 314                 return NULL;
 315
 316         RB_CLEAR_NODE(&ext->oe_node);
 317         ext->oe_obj = obj;
 318         cfs_atomic_set(&ext->oe_refc, 1);
 319         cfs_atomic_set(&ext->oe_users, 0);
 320         CFS_INIT_LIST_HEAD(&ext->oe_link);
 321         ext->oe_state = OES_INV;
 322         CFS_INIT_LIST_HEAD(&ext->oe_pages);
 323         cfs_waitq_init(&ext->oe_waitq);
 324         ext->oe_osclock = NULL;
 325
 326         return ext;
 327 }
 328
 329 static void osc_extent_free(struct osc_extent *ext)
 330 {
 331         OBD_SLAB_FREE_PTR(ext, osc_extent_kmem);
 332 }
 333
 334 static struct osc_extent *osc_extent_get(struct osc_extent *ext)
 335 {
 336         LASSERT(cfs_atomic_read(&ext->oe_refc) >= 0);
 337         cfs_atomic_inc(&ext->oe_refc);
 338         return ext;
 339 }
 340
 341 static void osc_extent_put(const struct lu_env *env, struct osc_extent *ext)
 342 {
 343         LASSERT(cfs_atomic_read(&ext->oe_refc) > 0);
 344         if (cfs_atomic_dec_and_test(&ext->oe_refc)) {
 345                 LASSERT(cfs_list_empty(&ext->oe_link));
 346                 LASSERT(cfs_atomic_read(&ext->oe_users) == 0);
 347                 LASSERT(ext->oe_state == OES_INV);
 348                 LASSERT(!ext->oe_intree);
 349
 350                 if (ext->oe_osclock) {
 351                         cl_lock_put(env, ext->oe_osclock);
 352                         ext->oe_osclock = NULL;
 353                 }
 354                 osc_extent_free(ext);
 355         }
 356 }
 357
 358 /**
 359  * osc_extent_put_trust() is a special version of osc_extent_put() when
 360  * it's known that the caller is not the last user. This is to address the
 361  * problem of lacking of lu_env ;-).
 362  */
 363 static void osc_extent_put_trust(struct osc_extent *ext)
 364 {
 365         LASSERT(cfs_atomic_read(&ext->oe_refc) > 1);
 366         LASSERT(osc_object_is_locked(ext->oe_obj));
 367         cfs_atomic_dec(&ext->oe_refc);
 368 }
 369
 370 /**
 371  * Return the extent which includes pgoff @index, or return the greatest
 372  * previous extent in the tree.
 373  */
 374 static struct osc_extent *osc_extent_search(struct osc_object *obj,
 375                                             pgoff_t index)
 376 {
 377         struct rb_node    *n = obj->oo_root.rb_node;
 378         struct osc_extent *tmp, *p = NULL;
 379
 380         LASSERT(osc_object_is_locked(obj));
 381         while (n != NULL) {
 382                 tmp = rb_extent(n);
 383                 if (index < tmp->oe_start) {
 384                         n = n->rb_left;
 385                 } else if (index > tmp->oe_end) {
 386                         p = rb_extent(n);
 387                         n = n->rb_right;
 388                 } else {
 389                         return tmp;
 390                 }
 391         }
 392         return p;
 393 }
 394
 395 /*
 396  * Return the extent covering @index, otherwise return NULL.
 397  * caller must have held object lock.
 398  */
 399 static struct osc_extent *osc_extent_lookup(struct osc_object *obj,
 400                                             pgoff_t index)
 401 {
 402         struct osc_extent *ext;
 403
 404         ext = osc_extent_search(obj, index);
 405         if (ext != NULL && ext->oe_start <= index && index <= ext->oe_end)
 406                 return osc_extent_get(ext);
 407         return NULL;
 408 }
 409
 410 /* caller must have held object lock. */
 411 static void osc_extent_insert(struct osc_object *obj, struct osc_extent *ext)
 412 {
 413         struct rb_node   **n      = &obj->oo_root.rb_node;
 414         struct rb_node    *parent = NULL;
 415         struct osc_extent *tmp;
 416
 417         LASSERT(ext->oe_intree == 0);
 418         LASSERT(ext->oe_obj == obj);
 419         LASSERT(osc_object_is_locked(obj));
 420         while (*n != NULL) {
 421                 tmp = rb_extent(*n);
 422                 parent = *n;
 423
 424                 if (ext->oe_end < tmp->oe_start)
 425                         n = &(*n)->rb_left;
 426                 else if (ext->oe_start > tmp->oe_end)
 427                         n = &(*n)->rb_right;
 428                 else
 429                         EASSERTF(0, tmp, EXTSTR, EXTPARA(ext));
 430         }
 431         rb_link_node(&ext->oe_node, parent, n);
 432         rb_insert_color(&ext->oe_node, &obj->oo_root);
 433         osc_extent_get(ext);
 434         ext->oe_intree = 1;
 435 }
 436
 437 /* caller must have held object lock. */
 438 static void osc_extent_erase(struct osc_extent *ext)
 439 {
 440         struct osc_object *obj = ext->oe_obj;
 441         LASSERT(osc_object_is_locked(obj));
 442         if (ext->oe_intree) {
 443                 rb_erase(&ext->oe_node, &obj->oo_root);
 444                 ext->oe_intree = 0;
 445                 /* rbtree held a refcount */
 446                 osc_extent_put_trust(ext);
 447         }
 448 }
 449
 450 static struct osc_extent *osc_extent_hold(struct osc_extent *ext)
 451 {
 452         struct osc_object *obj = ext->oe_obj;
 453
 454         LASSERT(osc_object_is_locked(obj));
 455         LASSERT(ext->oe_state == OES_ACTIVE || ext->oe_state == OES_CACHE);
 456         if (ext->oe_state == OES_CACHE) {
 457                 osc_extent_state_set(ext, OES_ACTIVE);
 458                 osc_update_pending(obj, OBD_BRW_WRITE, -ext->oe_nr_pages);
 459         }
 460         cfs_atomic_inc(&ext->oe_users);
 461         cfs_list_del_init(&ext->oe_link);
 462         return osc_extent_get(ext);
 463 }
 464
 465 static void __osc_extent_remove(struct osc_extent *ext)
 466 {
 467         LASSERT(osc_object_is_locked(ext->oe_obj));
 468         LASSERT(cfs_list_empty(&ext->oe_pages));
 469         osc_extent_erase(ext);
 470         cfs_list_del_init(&ext->oe_link);
 471         osc_extent_state_set(ext, OES_INV);
 472         OSC_EXTENT_DUMP(D_CACHE, ext, "destroyed.\n");
 473 }
 474
 475 static void osc_extent_remove(struct osc_extent *ext)
 476 {
 477         struct osc_object *obj = ext->oe_obj;
 478
 479         osc_object_lock(obj);
 480         __osc_extent_remove(ext);
 481         osc_object_unlock(obj);
 482 }
 483
 484 /**
 485  * This function is used to merge extents to get better performance. It checks
 486  * if @cur and @victim are contiguous at chunk level.
 487  */
 488 static int osc_extent_merge(const struct lu_env *env, struct osc_extent *cur,
 489                             struct osc_extent *victim)
 490 {
 491         struct osc_object *obj = cur->oe_obj;
 492         pgoff_t chunk_start;
 493         pgoff_t chunk_end;
 494         int ppc_bits;
 495
 496         LASSERT(cur->oe_state == OES_CACHE);
 497         LASSERT(osc_object_is_locked(obj));
 498         if (victim == NULL)
 499                 return -EINVAL;
 500
 501         if (victim->oe_state != OES_CACHE || victim->oe_fsync_wait)
 502                 return -EBUSY;
 503
 504         if (cur->oe_max_end != victim->oe_max_end)
 505                 return -ERANGE;
 506
 507         LASSERT(cur->oe_osclock == victim->oe_osclock);
 508         ppc_bits = osc_cli(obj)->cl_chunkbits - PAGE_CACHE_SHIFT;
 509         chunk_start = cur->oe_start >> ppc_bits;
 510         chunk_end   = cur->oe_end   >> ppc_bits;
 511         if (chunk_start   != (victim->oe_end >> ppc_bits) + 1 &&
 512             chunk_end + 1 != victim->oe_start >> ppc_bits)
 513                 return -ERANGE;
 514
 515         OSC_EXTENT_DUMP(D_CACHE, victim, "will be merged by %p.\n", cur);
 516
 517         cur->oe_start     = min(cur->oe_start, victim->oe_start);
 518         cur->oe_end       = max(cur->oe_end,   victim->oe_end);
 519         cur->oe_grants   += victim->oe_grants;
 520         cur->oe_nr_pages += victim->oe_nr_pages;
 521         /* only the following bits are needed to merge */
 522         cur->oe_urgent   |= victim->oe_urgent;
 523         cur->oe_memalloc |= victim->oe_memalloc;
 524         cfs_list_splice_init(&victim->oe_pages, &cur->oe_pages);
 525         cfs_list_del_init(&victim->oe_link);
 526         victim->oe_nr_pages = 0;
 527
 528         osc_extent_get(victim);
 529         __osc_extent_remove(victim);
 530         osc_extent_put(env, victim);
 531
 532         OSC_EXTENT_DUMP(D_CACHE, cur, "after merging %p.\n", victim);
 533         return 0;
 534 }
 535
 536 /**
 537  * Drop user count of osc_extent, and unplug IO asynchronously.
 538  */
 539 int osc_extent_release(const struct lu_env *env, struct osc_extent *ext)
 540 {
 541         struct osc_object *obj = ext->oe_obj;
 542         int rc = 0;
 543         ENTRY;
 544
 545         LASSERT(cfs_atomic_read(&ext->oe_users) > 0);
 546         LASSERT(sanity_check(ext) == 0);
 547         LASSERT(ext->oe_grants > 0);
 548
 549         if (cfs_atomic_dec_and_lock(&ext->oe_users, &obj->oo_lock)) {
 550                 LASSERT(ext->oe_state == OES_ACTIVE);
 551                 if (ext->oe_trunc_pending) {
 552                         /* a truncate process is waiting for this extent.
 553                          * This may happen due to a race, check
 554                          * osc_cache_truncate_start(). */
 555                         osc_extent_state_set(ext, OES_TRUNC);
 556                         ext->oe_trunc_pending = 0;
 557                 } else {
 558                         osc_extent_state_set(ext, OES_CACHE);
 559                         osc_update_pending(obj, OBD_BRW_WRITE,
 560                                            ext->oe_nr_pages);
 561
 562                         /* try to merge the previous and next extent. */
 563                         osc_extent_merge(env, ext, prev_extent(ext));
 564                         osc_extent_merge(env, ext, next_extent(ext));
 565
 566                         if (ext->oe_urgent)
 567                                 cfs_list_move_tail(&ext->oe_link,
 568                                                    &obj->oo_urgent_exts);
 569                 }
 570                 osc_object_unlock(obj);
 571
 572                 osc_io_unplug_async(env, osc_cli(obj), obj);
 573         }
 574         osc_extent_put(env, ext);
 575         RETURN(rc);
 576 }
 577
 578 static inline int overlapped(struct osc_extent *ex1, struct osc_extent *ex2)
 579 {
 580         return !(ex1->oe_end < ex2->oe_start || ex2->oe_end < ex1->oe_start);
 581 }
 582
 583 /**
 584  * Find or create an extent which includes @index, core function to manage
 585  * extent tree.
 586  */
 587 struct osc_extent *osc_extent_find(const struct lu_env *env,
 588                                    struct osc_object *obj, pgoff_t index,
 589                                    int *grants)
 590
 591 {
 592         struct client_obd *cli = osc_cli(obj);
 593         struct cl_lock    *lock;
 594         struct osc_extent *cur;
 595         struct osc_extent *ext;
 596         struct osc_extent *conflict = NULL;
 597         struct osc_extent *found = NULL;
 598         pgoff_t    chunk;
 599         pgoff_t    max_end;
 600         int        max_pages; /* max_pages_per_rpc */
 601         int        chunksize;
 602         int        ppc_bits; /* pages per chunk bits */
 603         int        chunk_mask;
 604         int        rc;
 605         ENTRY;
 606
 607         cur = osc_extent_alloc(obj);
 608         if (cur == NULL)
 609                 RETURN(ERR_PTR(-ENOMEM));
 610
 611         lock = cl_lock_at_pgoff(env, osc2cl(obj), index, NULL, 1, 0);
 612         LASSERT(lock != NULL);
 613         LASSERT(lock->cll_descr.cld_mode >= CLM_WRITE);
 614
 615         LASSERT(cli->cl_chunkbits >= PAGE_CACHE_SHIFT);
 616         ppc_bits   = cli->cl_chunkbits - PAGE_CACHE_SHIFT;
 617         chunk_mask = ~((1 << ppc_bits) - 1);
 618         chunksize  = 1 << cli->cl_chunkbits;
 619         chunk      = index >> ppc_bits;
 620
 621         /* align end to rpc edge, rpc size may not be a power 2 integer. */
 622         max_pages = cli->cl_max_pages_per_rpc;
 623         LASSERT((max_pages & ~chunk_mask) == 0);
 624         max_end = index - (index % max_pages) + max_pages - 1;
 625         max_end = min_t(pgoff_t, max_end, lock->cll_descr.cld_end);
 626
 627         /* initialize new extent by parameters so far */
 628         cur->oe_max_end = max_end;
 629         cur->oe_start   = index & chunk_mask;
 630         cur->oe_end     = ((index + ~chunk_mask + 1) & chunk_mask) - 1;
 631         if (cur->oe_start < lock->cll_descr.cld_start)
 632                 cur->oe_start = lock->cll_descr.cld_start;
 633         if (cur->oe_end > max_end)
 634                 cur->oe_end = max_end;
 635         cur->oe_osclock = lock;
 636         cur->oe_grants  = 0;
 637         cur->oe_mppr    = max_pages;
 638
 639         /* grants has been allocated by caller */
 640         LASSERTF(*grants >= chunksize + cli->cl_extent_tax,
 641                  "%u/%u/%u.\n", *grants, chunksize, cli->cl_extent_tax);
 642         LASSERTF((max_end - cur->oe_start) < max_pages, EXTSTR, EXTPARA(cur));
 643
 644 restart:
 645         osc_object_lock(obj);
 646         ext = osc_extent_search(obj, cur->oe_start);
 647         if (ext == NULL)
 648                 ext = first_extent(obj);
 649         while (ext != NULL) {
 650                 loff_t ext_chk_start = ext->oe_start >> ppc_bits;
 651                 loff_t ext_chk_end   = ext->oe_end   >> ppc_bits;
 652
 653                 LASSERT(sanity_check_nolock(ext) == 0);
 654                 if (chunk > ext_chk_end + 1)
 655                         break;
 656
 657                 /* if covering by different locks, no chance to match */
 658                 if (lock != ext->oe_osclock) {
 659                         EASSERTF(!overlapped(ext, cur), ext,
 660                                  EXTSTR, EXTPARA(cur));
 661
 662                         ext = next_extent(ext);
 663                         continue;
 664                 }
 665
 666                 /* discontiguous chunks? */
 667                 if (chunk + 1 < ext_chk_start) {
 668                         ext = next_extent(ext);
 669                         continue;
 670                 }
 671
 672                 /* ok, from now on, ext and cur have these attrs:
 673                  * 1. covered by the same lock
 674                  * 2. contiguous at chunk level or overlapping. */
 675
 676                 if (overlapped(ext, cur)) {
 677                         /* cur is the minimum unit, so overlapping means
 678                          * full contain. */
 679                         EASSERTF((ext->oe_start <= cur->oe_start &&
 680                                   ext->oe_end >= cur->oe_end),
 681                                  ext, EXTSTR, EXTPARA(cur));
 682
 683                         if (ext->oe_state > OES_CACHE || ext->oe_fsync_wait) {
 684                                 /* for simplicity, we wait for this extent to
 685                                  * finish before going forward. */
 686                                 conflict = osc_extent_get(ext);
 687                                 break;
 688                         }
 689
 690                         found = osc_extent_hold(ext);
 691                         break;
 692                 }
 693
 694                 /* non-overlapped extent */
 695                 if (ext->oe_state != OES_CACHE || ext->oe_fsync_wait) {
 696                         /* we can't do anything for a non OES_CACHE extent, or
 697                          * if there is someone waiting for this extent to be
 698                          * flushed, try next one. */
 699                         ext = next_extent(ext);
 700                         continue;
 701                 }
 702
 703                 /* check if they belong to the same rpc slot before trying to
 704                  * merge. the extents are not overlapped and contiguous at
 705                  * chunk level to get here. */
 706                 if (ext->oe_max_end != max_end) {
 707                         /* if they don't belong to the same RPC slot or
 708                          * max_pages_per_rpc has ever changed, do not merge. */
 709                         ext = next_extent(ext);
 710                         continue;
 711                 }
 712
 713                 /* it's required that an extent must be contiguous at chunk
 714                  * level so that we know the whole extent is covered by grant
 715                  * (the pages in the extent are NOT required to be contiguous).
 716                  * Otherwise, it will be too much difficult to know which
 717                  * chunks have grants allocated. */
 718
 719                 /* try to do front merge - extend ext's start */
 720                 if (chunk + 1 == ext_chk_start) {
 721                         /* ext must be chunk size aligned */
 722                         EASSERT((ext->oe_start & ~chunk_mask) == 0, ext);
 723
 724                         /* pull ext's start back to cover cur */
 725                         ext->oe_start   = cur->oe_start;
 726                         ext->oe_grants += chunksize;
 727                         *grants -= chunksize;
 728
 729                         found = osc_extent_hold(ext);
 730                 } else if (chunk == ext_chk_end + 1) {
 731                         /* rear merge */
 732                         ext->oe_end     = cur->oe_end;
 733                         ext->oe_grants += chunksize;
 734                         *grants -= chunksize;
 735
 736                         /* try to merge with the next one because we just fill
 737                          * in a gap */
 738                         if (osc_extent_merge(env, ext, next_extent(ext)) == 0)
 739                                 /* we can save extent tax from next extent */
 740                                 *grants += cli->cl_extent_tax;
 741
 742                         found = osc_extent_hold(ext);
 743                 }
 744                 if (found != NULL)
 745                         break;
 746
 747                 ext = next_extent(ext);
 748         }
 749
 750         osc_extent_tree_dump(D_CACHE, obj);
 751         if (found != NULL) {
 752                 LASSERT(conflict == NULL);
 753                 if (!IS_ERR(found)) {
 754                         LASSERT(found->oe_osclock == cur->oe_osclock);
 755                         OSC_EXTENT_DUMP(D_CACHE, found,
 756                                         "found caching ext for %lu.\n", index);
 757                 }
 758         } else if (conflict == NULL) {
 759                 /* create a new extent */
 760                 EASSERT(osc_extent_is_overlapped(obj, cur) == 0, cur);
 761                 cur->oe_grants = chunksize + cli->cl_extent_tax;
 762                 *grants -= cur->oe_grants;
 763                 LASSERT(*grants >= 0);
 764
 765                 cur->oe_state = OES_CACHE;
 766                 found = osc_extent_hold(cur);
 767                 osc_extent_insert(obj, cur);
 768                 OSC_EXTENT_DUMP(D_CACHE, cur, "add into tree %lu/%lu.\n",
 769                                 index, lock->cll_descr.cld_end);
 770         }
 771         osc_object_unlock(obj);
 772
 773         if (conflict != NULL) {
 774                 LASSERT(found == NULL);
 775
 776                 /* waiting for IO to finish. Please notice that it's impossible
 777                  * to be an OES_TRUNC extent. */
 778                 rc = osc_extent_wait(env, conflict, OES_INV);
 779                 osc_extent_put(env, conflict);
 780                 conflict = NULL;
 781                 if (rc < 0)
 782                         GOTO(out, found = ERR_PTR(rc));
 783
 784                 goto restart;
 785         }
 786         EXIT;
 787
 788 out:
 789         osc_extent_put(env, cur);
 790         LASSERT(*grants >= 0);
 791         return found;
 792 }
 793
 794 /**
 795  * Called when IO is finished to an extent.
 796  */
 797 int osc_extent_finish(const struct lu_env *env, struct osc_extent *ext,
 798                       int sent, int rc)
 799 {
 800         struct client_obd *cli = osc_cli(ext->oe_obj);
 801         struct osc_async_page *oap;
 802         struct osc_async_page *tmp;
 803         int nr_pages = ext->oe_nr_pages;
 804         int lost_grant = 0;
 805         int blocksize = cli->cl_import->imp_obd->obd_osfs.os_bsize ? : 4096;
 806         __u64 last_off = 0;
 807         int last_count = -1;
 808         ENTRY;
 809
 810         OSC_EXTENT_DUMP(D_CACHE, ext, "extent finished.\n");
 811
 812         ext->oe_rc = rc ?: ext->oe_nr_pages;
 813         EASSERT(ergo(rc == 0, ext->oe_state == OES_RPC), ext);
 814         cfs_list_for_each_entry_safe(oap, tmp, &ext->oe_pages,
 815                                      oap_pending_item) {
 816                 cfs_list_del_init(&oap->oap_rpc_item);
 817                 cfs_list_del_init(&oap->oap_pending_item);
 818                 if (last_off <= oap->oap_obj_off) {
 819                         last_off = oap->oap_obj_off;
 820                         last_count = oap->oap_count;
 821                 }
 822
 823                 --ext->oe_nr_pages;
 824                 osc_ap_completion(env, cli, oap, sent, rc);
 825         }
 826         EASSERT(ext->oe_nr_pages == 0, ext);
 827
 828         if (!sent) {
 829                 lost_grant = ext->oe_grants;
 830         } else if (blocksize < PAGE_CACHE_SIZE &&
 831                    last_count != PAGE_CACHE_SIZE) {
 832                 /* For short writes we shouldn't count parts of pages that
 833                  * span a whole chunk on the OST side, or our accounting goes
 834                  * wrong.  Should match the code in filter_grant_check. */
 835                 int offset = oap->oap_page_off & ~CFS_PAGE_MASK;
 836                 int count = oap->oap_count + (offset & (blocksize - 1));
 837                 int end = (offset + oap->oap_count) & (blocksize - 1);
 838                 if (end)
 839                         count += blocksize - end;
 840
 841                 lost_grant = PAGE_CACHE_SIZE - count;
 842         }
 843         if (ext->oe_grants > 0)
 844                 osc_free_grant(cli, nr_pages, lost_grant);
 845
 846         osc_extent_remove(ext);
 847         /* put the refcount for RPC */
 848         osc_extent_put(env, ext);
 849         RETURN(0);
 850 }
 851
 852 static int extent_wait_cb(struct osc_extent *ext, int state)
 853 {
 854         int ret;
 855
 856         osc_object_lock(ext->oe_obj);
 857         ret = ext->oe_state == state;
 858         osc_object_unlock(ext->oe_obj);
 859
 860         return ret;
 861 }
 862
 863 /**
 864  * Wait for the extent's state to become @state.
 865  */
 866 static int osc_extent_wait(const struct lu_env *env, struct osc_extent *ext,
 867                            int state)
 868 {
 869         struct osc_object *obj = ext->oe_obj;
 870         struct l_wait_info lwi = LWI_TIMEOUT_INTR(cfs_time_seconds(600), NULL,
 871                                                   LWI_ON_SIGNAL_NOOP, NULL);
 872         int rc = 0;
 873         ENTRY;
 874
 875         osc_object_lock(obj);
 876         LASSERT(sanity_check_nolock(ext) == 0);
 877         /* `Kick' this extent only if the caller is waiting for it to be
 878          * written out. */
 879         if (state == OES_INV && !ext->oe_urgent && !ext->oe_hp) {
 880                 if (ext->oe_state == OES_ACTIVE) {
 881                         ext->oe_urgent = 1;
 882                 } else if (ext->oe_state == OES_CACHE) {
 883                         ext->oe_urgent = 1;
 884                         osc_extent_hold(ext);
 885                         rc = 1;
 886                 }
 887         }
 888         osc_object_unlock(obj);
 889         if (rc == 1)
 890                 osc_extent_release(env, ext);
 891
 892         /* wait for the extent until its state becomes @state */
 893         rc = l_wait_event(ext->oe_waitq, extent_wait_cb(ext, state), &lwi);
 894         if (rc == -ETIMEDOUT) {
 895                 OSC_EXTENT_DUMP(D_ERROR, ext,
 896                         "%s: wait ext to %d timedout, recovery in progress?\n",
 897                         osc_export(obj)->exp_obd->obd_name, state);
 898
 899                 lwi = LWI_INTR(LWI_ON_SIGNAL_NOOP, NULL);
 900                 rc = l_wait_event(ext->oe_waitq, extent_wait_cb(ext, state),
 901                                   &lwi);
 902         }
 903         if (rc == 0 && ext->oe_rc < 0)
 904                 rc = ext->oe_rc;
 905         RETURN(rc);
 906 }
 907
 908 /**
 909  * Discard pages with index greater than @size. If @ext is overlapped with
 910  * @size, then partial truncate happens.
 911  */
 912 static int osc_extent_truncate(struct osc_extent *ext, pgoff_t trunc_index,
 913                                 bool partial)
 914 {
 915         struct cl_env_nest     nest;
 916         struct lu_env         *env;
 917         struct cl_io          *io;
 918         struct osc_object     *obj = ext->oe_obj;
 919         struct client_obd     *cli = osc_cli(obj);
 920         struct osc_async_page *oap;
 921         struct osc_async_page *tmp;
 922         int                    pages_in_chunk = 0;
 923         int                    ppc_bits    = cli->cl_chunkbits -
 924                                              PAGE_CACHE_SHIFT;
 925         __u64                  trunc_chunk = trunc_index >> ppc_bits;
 926         int                    grants   = 0;
 927         int                    nr_pages = 0;
 928         int                    rc       = 0;
 929         ENTRY;
 930
 931         LASSERT(sanity_check(ext) == 0);
 932         LASSERT(ext->oe_state == OES_TRUNC);
 933         LASSERT(!ext->oe_urgent);
 934
 935         /* Request new lu_env.
 936          * We can't use that env from osc_cache_truncate_start() because
 937          * it's from lov_io_sub and not fully initialized. */
 938         env = cl_env_nested_get(&nest);
 939         io  = &osc_env_info(env)->oti_io;
 940         io->ci_obj = cl_object_top(osc2cl(obj));
 941         rc = cl_io_init(env, io, CIT_MISC, io->ci_obj);
 942         if (rc < 0)
 943                 GOTO(out, rc);
 944
 945         /* discard all pages with index greater then trunc_index */
 946         cfs_list_for_each_entry_safe(oap, tmp, &ext->oe_pages,
 947                                      oap_pending_item) {
 948                 struct cl_page  *sub  = oap2cl_page(oap);
 949                 struct cl_page  *page = cl_page_top(sub);
 950
 951                 LASSERT(cfs_list_empty(&oap->oap_rpc_item));
 952
 953                 /* only discard the pages with their index greater than
 954                  * trunc_index, and ... */
 955                 if (sub->cp_index < trunc_index ||
 956                     (sub->cp_index == trunc_index && partial)) {
 957                         /* accounting how many pages remaining in the chunk
 958                          * so that we can calculate grants correctly. */
 959                         if (sub->cp_index >> ppc_bits == trunc_chunk)
 960                                 ++pages_in_chunk;
 961                         continue;
 962                 }
 963
 964                 cfs_list_del_init(&oap->oap_pending_item);
 965
 966                 cl_page_get(page);
 967                 lu_ref_add(&page->cp_reference, "truncate", cfs_current());
 968
 969                 if (cl_page_own(env, io, page) == 0) {
 970                         cl_page_unmap(env, io, page);
 971                         cl_page_discard(env, io, page);
 972                         cl_page_disown(env, io, page);
 973                 } else {
 974                         LASSERT(page->cp_state == CPS_FREEING);
 975                         LASSERT(0);
 976                 }
 977
 978                 lu_ref_del(&page->cp_reference, "truncate", cfs_current());
 979                 cl_page_put(env, page);
 980
 981                 --ext->oe_nr_pages;
 982                 ++nr_pages;
 983         }
 984         EASSERTF(ergo(ext->oe_start >= trunc_index + !!partial,
 985                       ext->oe_nr_pages == 0),
 986                 ext, "trunc_index %lu, partial %d\n", trunc_index, partial);
 987
 988         osc_object_lock(obj);
 989         if (ext->oe_nr_pages == 0) {
 990                 LASSERT(pages_in_chunk == 0);
 991                 grants = ext->oe_grants;
 992                 ext->oe_grants = 0;
 993         } else { /* calculate how many grants we can free */
 994                 int     chunks = (ext->oe_end >> ppc_bits) - trunc_chunk;
 995                 pgoff_t last_index;
 996
 997
 998                 /* if there is no pages in this chunk, we can also free grants
 999                  * for the last chunk */
1000                 if (pages_in_chunk == 0) {
1001                         /* if this is the 1st chunk and no pages in this chunk,
1002                          * ext->oe_nr_pages must be zero, so we should be in
1003                          * the other if-clause. */
1004                         LASSERT(trunc_chunk > 0);
1005                         --trunc_chunk;
1006                         ++chunks;
1007                 }
1008
1009                 /* this is what we can free from this extent */
1010                 grants          = chunks << cli->cl_chunkbits;
1011                 ext->oe_grants -= grants;
1012                 last_index      = ((trunc_chunk + 1) << ppc_bits) - 1;
1013                 ext->oe_end     = min(last_index, ext->oe_max_end);
1014                 LASSERT(ext->oe_end >= ext->oe_start);
1015                 LASSERT(ext->oe_grants > 0);
1016         }
1017         osc_object_unlock(obj);
1018
1019         if (grants > 0 || nr_pages > 0)
1020                 osc_free_grant(cli, nr_pages, grants);
1021
1022 out:
1023         cl_io_fini(env, io);
1024         cl_env_nested_put(&nest, env);
1025         RETURN(rc);
1026 }
1027
1028 /**
1029  * This function is used to make the extent prepared for transfer.
1030  * A race with flusing page - ll_writepage() has to be handled cautiously.
1031  */
1032 static int osc_extent_make_ready(const struct lu_env *env,
1033                                  struct osc_extent *ext)
1034 {
1035         struct osc_async_page *oap;
1036         struct osc_async_page *last = NULL;
1037         struct osc_object *obj = ext->oe_obj;
1038         int page_count = 0;
1039         int rc;
1040         ENTRY;
1041
1042         /* we're going to grab page lock, so object lock must not be taken. */
1043         LASSERT(sanity_check(ext) == 0);
1044         /* in locking state, any process should not touch this extent. */
1045         EASSERT(ext->oe_state == OES_LOCKING, ext);
1046         EASSERT(ext->oe_owner != NULL, ext);
1047
1048         OSC_EXTENT_DUMP(D_CACHE, ext, "make ready\n");
1049
1050         cfs_list_for_each_entry(oap, &ext->oe_pages, oap_pending_item) {
1051                 ++page_count;
1052                 if (last == NULL || last->oap_obj_off < oap->oap_obj_off)
1053                         last = oap;
1054
1055                 /* checking ASYNC_READY is race safe */
1056                 if ((oap->oap_async_flags & ASYNC_READY) != 0)
1057                         continue;
1058
1059                 rc = osc_make_ready(env, oap, OBD_BRW_WRITE);
1060                 switch (rc) {
1061                 case 0:
1062                         spin_lock(&oap->oap_lock);
1063                         oap->oap_async_flags |= ASYNC_READY;
1064                         spin_unlock(&oap->oap_lock);
1065                         break;
1066                 case -EALREADY:
1067                         LASSERT((oap->oap_async_flags & ASYNC_READY) != 0);
1068                         break;
1069                 default:
1070                         LASSERTF(0, "unknown return code: %d\n", rc);
1071                 }
1072         }
1073
1074         LASSERT(page_count == ext->oe_nr_pages);
1075         LASSERT(last != NULL);
1076         /* the last page is the only one we need to refresh its count by
1077          * the size of file. */
1078         if (!(last->oap_async_flags & ASYNC_COUNT_STABLE)) {
1079                 last->oap_count = osc_refresh_count(env, last, OBD_BRW_WRITE);
1080                 LASSERT(last->oap_count > 0);
1081                 LASSERT(last->oap_page_off + last->oap_count <= PAGE_CACHE_SIZE);
1082                 last->oap_async_flags |= ASYNC_COUNT_STABLE;
1083         }
1084
1085         /* for the rest of pages, we don't need to call osf_refresh_count()
1086          * because it's known they are not the last page */
1087         cfs_list_for_each_entry(oap, &ext->oe_pages, oap_pending_item) {
1088                 if (!(oap->oap_async_flags & ASYNC_COUNT_STABLE)) {
1089                         oap->oap_count = PAGE_CACHE_SIZE - oap->oap_page_off;
1090                         oap->oap_async_flags |= ASYNC_COUNT_STABLE;
1091                 }
1092         }
1093
1094         osc_object_lock(obj);
1095         osc_extent_state_set(ext, OES_RPC);
1096         osc_object_unlock(obj);
1097         /* get a refcount for RPC. */
1098         osc_extent_get(ext);
1099
1100         RETURN(0);
1101 }
1102
1103 /**
1104  * Quick and simple version of osc_extent_find(). This function is frequently
1105  * called to expand the extent for the same IO. To expand the extent, the
1106  * page index must be in the same or next chunk of ext->oe_end.
1107  */
1108 static int osc_extent_expand(struct osc_extent *ext, pgoff_t index, int *grants)
1109 {
1110         struct osc_object *obj = ext->oe_obj;
1111         struct client_obd *cli = osc_cli(obj);
1112         struct osc_extent *next;
1113         int ppc_bits = cli->cl_chunkbits - PAGE_CACHE_SHIFT;
1114         pgoff_t chunk = index >> ppc_bits;
1115         pgoff_t end_chunk;
1116         pgoff_t end_index;
1117         int chunksize = 1 << cli->cl_chunkbits;
1118         int rc = 0;
1119         ENTRY;
1120
1121         LASSERT(ext->oe_max_end >= index && ext->oe_start <= index);
1122         osc_object_lock(obj);
1123         LASSERT(sanity_check_nolock(ext) == 0);
1124         end_chunk = ext->oe_end >> ppc_bits;
1125         if (chunk > end_chunk + 1)
1126                 GOTO(out, rc = -ERANGE);
1127
1128         if (end_chunk >= chunk)
1129                 GOTO(out, rc = 0);
1130
1131         LASSERT(end_chunk + 1 == chunk);
1132         /* try to expand this extent to cover @index */
1133         end_index = min(ext->oe_max_end, ((chunk + 1) << ppc_bits) - 1);
1134
1135         next = next_extent(ext);
1136         if (next != NULL && next->oe_start <= end_index)
1137                 /* complex mode - overlapped with the next extent,
1138                  * this case will be handled by osc_extent_find() */
1139                 GOTO(out, rc = -EAGAIN);
1140
1141         ext->oe_end = end_index;
1142         ext->oe_grants += chunksize;
1143         *grants -= chunksize;
1144         LASSERT(*grants >= 0);
1145         EASSERTF(osc_extent_is_overlapped(obj, ext) == 0, ext,
1146                  "overlapped after expanding for %lu.\n", index);
1147         EXIT;
1148
1149 out:
1150         osc_object_unlock(obj);
1151         RETURN(rc);
1152 }
1153
1154 static void osc_extent_tree_dump0(int level, struct osc_object *obj,
1155                                   const char *func, int line)
1156 {
1157         struct osc_extent *ext;
1158         int cnt;
1159
1160         CDEBUG(level, "Dump object %p extents at %s:%d, mppr: %u.\n",
1161                obj, func, line, osc_cli(obj)->cl_max_pages_per_rpc);
1162
1163         /* osc_object_lock(obj); */
1164         cnt = 1;
1165         for (ext = first_extent(obj); ext != NULL; ext = next_extent(ext))
1166                 OSC_EXTENT_DUMP(level, ext, "in tree %d.\n", cnt++);
1167
1168         cnt = 1;
1169         cfs_list_for_each_entry(ext, &obj->oo_hp_exts, oe_link)
1170                 OSC_EXTENT_DUMP(level, ext, "hp %d.\n", cnt++);
1171
1172         cnt = 1;
1173         cfs_list_for_each_entry(ext, &obj->oo_urgent_exts, oe_link)
1174                 OSC_EXTENT_DUMP(level, ext, "urgent %d.\n", cnt++);
1175
1176         cnt = 1;
1177         cfs_list_for_each_entry(ext, &obj->oo_reading_exts, oe_link)
1178                 OSC_EXTENT_DUMP(level, ext, "reading %d.\n", cnt++);
1179         /* osc_object_unlock(obj); */
1180 }
1181
1182 /* ------------------ osc extent end ------------------ */
1183
1184 static inline int osc_is_ready(struct osc_object *osc)
1185 {
1186         return !cfs_list_empty(&osc->oo_ready_item) ||
1187                !cfs_list_empty(&osc->oo_hp_ready_item);
1188 }
1189
1190 #define OSC_IO_DEBUG(OSC, STR, args...)                                        \
1191         CDEBUG(D_CACHE, "obj %p ready %d|%c|%c wr %d|%c|%c rd %d|%c " STR,     \
1192                (OSC), osc_is_ready(OSC),                                       \
1193                list_empty_marker(&(OSC)->oo_hp_ready_item),                    \
1194                list_empty_marker(&(OSC)->oo_ready_item),                       \
1195                cfs_atomic_read(&(OSC)->oo_nr_writes),                          \
1196                list_empty_marker(&(OSC)->oo_hp_exts),                          \
1197                list_empty_marker(&(OSC)->oo_urgent_exts),                      \
1198                cfs_atomic_read(&(OSC)->oo_nr_reads),                           \
1199                list_empty_marker(&(OSC)->oo_reading_exts),                     \
1200                ##args)
1201
1202 static int osc_make_ready(const struct lu_env *env, struct osc_async_page *oap,
1203                           int cmd)
1204 {
1205         struct osc_page *opg  = oap2osc_page(oap);
1206         struct cl_page  *page = cl_page_top(oap2cl_page(oap));
1207         int result;
1208
1209         LASSERT(cmd == OBD_BRW_WRITE); /* no cached reads */
1210
1211         ENTRY;
1212         result = cl_page_make_ready(env, page, CRT_WRITE);
1213         if (result == 0)
1214                 opg->ops_submit_time = cfs_time_current();
1215         RETURN(result);
1216 }
1217
1218 static int osc_refresh_count(const struct lu_env *env,
1219                              struct osc_async_page *oap, int cmd)
1220 {
1221         struct osc_page  *opg = oap2osc_page(oap);
1222         struct cl_page   *page = oap2cl_page(oap);
1223         struct cl_object *obj;
1224         struct cl_attr   *attr = &osc_env_info(env)->oti_attr;
1225
1226         int result;
1227         loff_t kms;
1228
1229         /* readpage queues with _COUNT_STABLE, shouldn't get here. */
1230         LASSERT(!(cmd & OBD_BRW_READ));
1231         LASSERT(opg != NULL);
1232         obj = opg->ops_cl.cpl_obj;
1233
1234         cl_object_attr_lock(obj);
1235         result = cl_object_attr_get(env, obj, attr);
1236         cl_object_attr_unlock(obj);
1237         if (result < 0)
1238                 return result;
1239         kms = attr->cat_kms;
1240         if (cl_offset(obj, page->cp_index) >= kms)
1241                 /* catch race with truncate */
1242                 return 0;
1243         else if (cl_offset(obj, page->cp_index + 1) > kms)
1244                 /* catch sub-page write at end of file */
1245                 return kms % PAGE_CACHE_SIZE;
1246         else
1247                 return PAGE_CACHE_SIZE;
1248 }
1249
1250 static int osc_completion(const struct lu_env *env, struct osc_async_page *oap,
1251                           int cmd, int rc)
1252 {
1253         struct osc_page   *opg  = oap2osc_page(oap);
1254         struct cl_page    *page = cl_page_top(oap2cl_page(oap));
1255         struct osc_object *obj  = cl2osc(opg->ops_cl.cpl_obj);
1256         enum cl_req_type   crt;
1257         int srvlock;
1258
1259         ENTRY;
1260
1261         cmd &= ~OBD_BRW_NOQUOTA;
1262         LASSERT(equi(page->cp_state == CPS_PAGEIN,  cmd == OBD_BRW_READ));
1263         LASSERT(equi(page->cp_state == CPS_PAGEOUT, cmd == OBD_BRW_WRITE));
1264         LASSERT(opg->ops_transfer_pinned);
1265
1266         /*
1267          * page->cp_req can be NULL if io submission failed before
1268          * cl_req was allocated.
1269          */
1270         if (page->cp_req != NULL)
1271                 cl_req_page_done(env, page);
1272         LASSERT(page->cp_req == NULL);
1273
1274         crt = cmd == OBD_BRW_READ ? CRT_READ : CRT_WRITE;
1275         /* Clear opg->ops_transfer_pinned before VM lock is released. */
1276         opg->ops_transfer_pinned = 0;
1277
1278         spin_lock(&obj->oo_seatbelt);
1279         LASSERT(opg->ops_submitter != NULL);
1280         LASSERT(!cfs_list_empty(&opg->ops_inflight));
1281         cfs_list_del_init(&opg->ops_inflight);
1282         opg->ops_submitter = NULL;
1283         spin_unlock(&obj->oo_seatbelt);
1284
1285         opg->ops_submit_time = 0;
1286         srvlock = oap->oap_brw_flags & OBD_BRW_SRVLOCK;
1287
1288         /* statistic */
1289         if (rc == 0 && srvlock) {
1290                 struct lu_device *ld    = opg->ops_cl.cpl_obj->co_lu.lo_dev;
1291                 struct osc_stats *stats = &lu2osc_dev(ld)->od_stats;
1292                 int bytes = oap->oap_count;
1293
1294                 if (crt == CRT_READ)
1295                         stats->os_lockless_reads += bytes;
1296                 else
1297                         stats->os_lockless_writes += bytes;
1298         }
1299
1300         /*
1301          * This has to be the last operation with the page, as locks are
1302          * released in cl_page_completion() and nothing except for the
1303          * reference counter protects page from concurrent reclaim.
1304          */
1305         lu_ref_del(&page->cp_reference, "transfer", page);
1306
1307         cl_page_completion(env, page, crt, rc);
1308
1309         RETURN(0);
1310 }
1311
1312 #define OSC_DUMP_GRANT(lvl, cli, fmt, args...) do {                           \
1313         struct client_obd *__tmp = (cli);                                     \
1314         CDEBUG(lvl, "%s: grant { dirty: %ld/%ld dirty_pages: %d/%d "          \
1315                "dropped: %ld avail: %ld, reserved: %ld, flight: %d } "        \
1316                "lru {in list: %d, left: %d, waiters: %d }" fmt,               \
1317                __tmp->cl_import->imp_obd->obd_name,                           \
1318                __tmp->cl_dirty, __tmp->cl_dirty_max,                          \
1319                cfs_atomic_read(&obd_dirty_pages), obd_max_dirty_pages,        \
1320                __tmp->cl_lost_grant, __tmp->cl_avail_grant,                   \
1321                __tmp->cl_reserved_grant, __tmp->cl_w_in_flight,               \
1322                cfs_atomic_read(&__tmp->cl_lru_in_list),                       \
1323                cfs_atomic_read(&__tmp->cl_lru_busy),                          \
1324                cfs_atomic_read(&__tmp->cl_lru_shrinkers), ##args);            \
1325 } while (0)
1326
1327 /* caller must hold loi_list_lock */
1328 static void osc_consume_write_grant(struct client_obd *cli,
1329                                     struct brw_page *pga)
1330 {
1331         LASSERT(spin_is_locked(&cli->cl_loi_list_lock.lock));
1332         LASSERT(!(pga->flag & OBD_BRW_FROM_GRANT));
1333         cfs_atomic_inc(&obd_dirty_pages);
1334         cli->cl_dirty += PAGE_CACHE_SIZE;
1335         pga->flag |= OBD_BRW_FROM_GRANT;
1336         CDEBUG(D_CACHE, "using %lu grant credits for brw %p page %p\n",
1337                PAGE_CACHE_SIZE, pga, pga->pg);
1338         osc_update_next_shrink(cli);
1339 }
1340
1341 /* the companion to osc_consume_write_grant, called when a brw has completed.
1342  * must be called with the loi lock held. */
1343 static void osc_release_write_grant(struct client_obd *cli,
1344                                     struct brw_page *pga)
1345 {
1346         ENTRY;
1347
1348         LASSERT(spin_is_locked(&cli->cl_loi_list_lock.lock));
1349         if (!(pga->flag & OBD_BRW_FROM_GRANT)) {
1350                 EXIT;
1351                 return;
1352         }
1353
1354         pga->flag &= ~OBD_BRW_FROM_GRANT;
1355         cfs_atomic_dec(&obd_dirty_pages);
1356         cli->cl_dirty -= PAGE_CACHE_SIZE;
1357         if (pga->flag & OBD_BRW_NOCACHE) {
1358                 pga->flag &= ~OBD_BRW_NOCACHE;
1359                 cfs_atomic_dec(&obd_dirty_transit_pages);
1360                 cli->cl_dirty_transit -= PAGE_CACHE_SIZE;
1361         }
1362         EXIT;
1363 }
1364
1365 /**
1366  * To avoid sleeping with object lock held, it's good for us allocate enough
1367  * grants before entering into critical section.
1368  *
1369  * client_obd_list_lock held by caller
1370  */
1371 static int osc_reserve_grant(struct client_obd *cli, unsigned int bytes)
1372 {
1373         int rc = -EDQUOT;
1374
1375         if (cli->cl_avail_grant >= bytes) {
1376                 cli->cl_avail_grant    -= bytes;
1377                 cli->cl_reserved_grant += bytes;
1378                 rc = 0;
1379         }
1380         return rc;
1381 }
1382
1383 static void __osc_unreserve_grant(struct client_obd *cli,
1384                                   unsigned int reserved, unsigned int unused)
1385 {
1386         /* it's quite normal for us to get more grant than reserved.
1387          * Thinking about a case that two extents merged by adding a new
1388          * chunk, we can save one extent tax. If extent tax is greater than
1389          * one chunk, we can save more grant by adding a new chunk */
1390         cli->cl_reserved_grant -= reserved;
1391         if (unused > reserved) {
1392                 cli->cl_avail_grant += reserved;
1393                 cli->cl_lost_grant  += unused - reserved;
1394         } else {
1395                 cli->cl_avail_grant += unused;
1396         }
1397 }
1398
1399 void osc_unreserve_grant(struct client_obd *cli,
1400                          unsigned int reserved, unsigned int unused)
1401 {
1402         client_obd_list_lock(&cli->cl_loi_list_lock);
1403         __osc_unreserve_grant(cli, reserved, unused);
1404         if (unused > 0)
1405                 osc_wake_cache_waiters(cli);
1406         client_obd_list_unlock(&cli->cl_loi_list_lock);
1407 }
1408
1409 /**
1410  * Free grant after IO is finished or canceled.
1411  *
1412  * @lost_grant is used to remember how many grants we have allocated but not
1413  * used, we should return these grants to OST. There're two cases where grants
1414  * can be lost:
1415  * 1. truncate;
1416  * 2. blocksize at OST is less than PAGE_CACHE_SIZE and a partial page was
1417  *    written. In this case OST may use less chunks to serve this partial
1418  *    write. OSTs don't actually know the page size on the client side. so
1419  *    clients have to calculate lost grant by the blocksize on the OST.
1420  *    See filter_grant_check() for details.
1421  */
1422 static void osc_free_grant(struct client_obd *cli, unsigned int nr_pages,
1423                            unsigned int lost_grant)
1424 {
1425         int grant = (1 << cli->cl_chunkbits) + cli->cl_extent_tax;
1426
1427         client_obd_list_lock(&cli->cl_loi_list_lock);
1428         cfs_atomic_sub(nr_pages, &obd_dirty_pages);
1429         cli->cl_dirty -= nr_pages << PAGE_CACHE_SHIFT;
1430         cli->cl_lost_grant += lost_grant;
1431         if (cli->cl_avail_grant < grant && cli->cl_lost_grant >= grant) {
1432                 /* borrow some grant from truncate to avoid the case that
1433                  * truncate uses up all avail grant */
1434                 cli->cl_lost_grant -= grant;
1435                 cli->cl_avail_grant += grant;
1436         }
1437         osc_wake_cache_waiters(cli);
1438         client_obd_list_unlock(&cli->cl_loi_list_lock);
1439         CDEBUG(D_CACHE, "lost %u grant: %lu avail: %lu dirty: %lu\n",
1440                lost_grant, cli->cl_lost_grant,
1441                cli->cl_avail_grant, cli->cl_dirty);
1442 }
1443
1444 /**
1445  * The companion to osc_enter_cache(), called when @oap is no longer part of
1446  * the dirty accounting due to error.
1447  */
1448 static void osc_exit_cache(struct client_obd *cli, struct osc_async_page *oap)
1449 {
1450         client_obd_list_lock(&cli->cl_loi_list_lock);
1451         osc_release_write_grant(cli, &oap->oap_brw_page);
1452         client_obd_list_unlock(&cli->cl_loi_list_lock);
1453 }
1454
1455 /**
1456  * Non-blocking version of osc_enter_cache() that consumes grant only when it
1457  * is available.
1458  */
1459 static int osc_enter_cache_try(struct client_obd *cli,
1460                                struct osc_async_page *oap,
1461                                int bytes, int transient)
1462 {
1463         int rc;
1464
1465         OSC_DUMP_GRANT(D_CACHE, cli, "need:%d.\n", bytes);
1466
1467         rc = osc_reserve_grant(cli, bytes);
1468         if (rc < 0)
1469                 return 0;
1470
1471         if (cli->cl_dirty + PAGE_CACHE_SIZE <= cli->cl_dirty_max &&
1472             cfs_atomic_read(&obd_dirty_pages) + 1 <= obd_max_dirty_pages) {
1473                 osc_consume_write_grant(cli, &oap->oap_brw_page);
1474                 if (transient) {
1475                         cli->cl_dirty_transit += PAGE_CACHE_SIZE;
1476                         cfs_atomic_inc(&obd_dirty_transit_pages);
1477                         oap->oap_brw_flags |= OBD_BRW_NOCACHE;
1478                 }
1479                 rc = 1;
1480         } else {
1481                 __osc_unreserve_grant(cli, bytes, bytes);
1482                 rc = 0;
1483         }
1484         return rc;
1485 }
1486
1487 static int ocw_granted(struct client_obd *cli, struct osc_cache_waiter *ocw)
1488 {
1489         int rc;
1490         client_obd_list_lock(&cli->cl_loi_list_lock);
1491         rc = cfs_list_empty(&ocw->ocw_entry);
1492         client_obd_list_unlock(&cli->cl_loi_list_lock);
1493         return rc;
1494 }
1495
1496 /**
1497  * The main entry to reserve dirty page accounting. Usually the grant reserved
1498  * in this function will be freed in bulk in osc_free_grant() unless it fails
1499  * to add osc cache, in that case, it will be freed in osc_exit_cache().
1500  *
1501  * The process will be put into sleep if it's already run out of grant.
1502  */
1503 static int osc_enter_cache(const struct lu_env *env, struct client_obd *cli,
1504                            struct osc_async_page *oap, int bytes)
1505 {
1506         struct osc_object *osc = oap->oap_obj;
1507         struct lov_oinfo  *loi = osc->oo_oinfo;
1508         struct osc_cache_waiter ocw;
1509         struct l_wait_info lwi = LWI_TIMEOUT_INTR(cfs_time_seconds(600), NULL,
1510                                                   LWI_ON_SIGNAL_NOOP, NULL);
1511         int rc = -EDQUOT;
1512         ENTRY;
1513
1514         OSC_DUMP_GRANT(D_CACHE, cli, "need:%d.\n", bytes);
1515
1516         client_obd_list_lock(&cli->cl_loi_list_lock);
1517
1518         /* force the caller to try sync io.  this can jump the list
1519          * of queued writes and create a discontiguous rpc stream */
1520         if (OBD_FAIL_CHECK(OBD_FAIL_OSC_NO_GRANT) ||
1521             cli->cl_dirty_max < PAGE_CACHE_SIZE     ||
1522             cli->cl_ar.ar_force_sync || loi->loi_ar.ar_force_sync)
1523                 GOTO(out, rc = -EDQUOT);
1524
1525         /* Hopefully normal case - cache space and write credits available */
1526         if (osc_enter_cache_try(cli, oap, bytes, 0))
1527                 GOTO(out, rc = 0);
1528
1529         /* We can get here for two reasons: too many dirty pages in cache, or
1530          * run out of grants. In both cases we should write dirty pages out.
1531          * Adding a cache waiter will trigger urgent write-out no matter what
1532          * RPC size will be.
1533          * The exiting condition is no avail grants and no dirty pages caching,
1534          * that really means there is no space on the OST. */
1535         cfs_waitq_init(&ocw.ocw_waitq);
1536         ocw.ocw_oap   = oap;
1537         ocw.ocw_grant = bytes;
1538         while (cli->cl_dirty > 0 || cli->cl_w_in_flight > 0) {
1539                 cfs_list_add_tail(&ocw.ocw_entry, &cli->cl_cache_waiters);
1540                 ocw.ocw_rc = 0;
1541                 client_obd_list_unlock(&cli->cl_loi_list_lock);
1542
1543                 osc_io_unplug_async(env, cli, NULL);
1544
1545                 CDEBUG(D_CACHE, "%s: sleeping for cache space @ %p for %p\n",
1546                        cli->cl_import->imp_obd->obd_name, &ocw, oap);
1547
1548                 rc = l_wait_event(ocw.ocw_waitq, ocw_granted(cli, &ocw), &lwi);
1549
1550                 client_obd_list_lock(&cli->cl_loi_list_lock);
1551
1552                 /* l_wait_event is interrupted by signal, or timed out */
1553                 if (rc < 0) {
1554                         if (rc == -ETIMEDOUT) {
1555                                 OSC_DUMP_GRANT(D_ERROR, cli,
1556                                                 "try to reserve %d.\n", bytes);
1557                                 osc_extent_tree_dump(D_ERROR, osc);
1558                                 rc = -EDQUOT;
1559                         }
1560
1561                         cfs_list_del_init(&ocw.ocw_entry);
1562                         GOTO(out, rc);
1563                 }
1564
1565                 LASSERT(cfs_list_empty(&ocw.ocw_entry));
1566                 rc = ocw.ocw_rc;
1567
1568                 if (rc != -EDQUOT)
1569                         GOTO(out, rc);
1570                 if (osc_enter_cache_try(cli, oap, bytes, 0))
1571                         GOTO(out, rc = 0);
1572         }
1573         EXIT;
1574 out:
1575         client_obd_list_unlock(&cli->cl_loi_list_lock);
1576         OSC_DUMP_GRANT(D_CACHE, cli, "returned %d.\n", rc);
1577         RETURN(rc);
1578 }
1579
1580 /* caller must hold loi_list_lock */
1581 void osc_wake_cache_waiters(struct client_obd *cli)
1582 {
1583         cfs_list_t *l, *tmp;
1584         struct osc_cache_waiter *ocw;
1585
1586         ENTRY;
1587         cfs_list_for_each_safe(l, tmp, &cli->cl_cache_waiters) {
1588                 ocw = cfs_list_entry(l, struct osc_cache_waiter, ocw_entry);
1589                 cfs_list_del_init(&ocw->ocw_entry);
1590
1591                 ocw->ocw_rc = -EDQUOT;
1592                 /* we can't dirty more */
1593                 if ((cli->cl_dirty + PAGE_CACHE_SIZE > cli->cl_dirty_max) ||
1594                     (cfs_atomic_read(&obd_dirty_pages) + 1 >
1595                      obd_max_dirty_pages)) {
1596                         CDEBUG(D_CACHE, "no dirty room: dirty: %ld "
1597                                "osc max %ld, sys max %d\n", cli->cl_dirty,
1598                                cli->cl_dirty_max, obd_max_dirty_pages);
1599                         goto wakeup;
1600                 }
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 wakeup:
1607                 CDEBUG(D_CACHE, "wake up %p for oap %p, avail grant %ld, %d\n",
1608                        ocw, ocw->ocw_oap, cli->cl_avail_grant, ocw->ocw_rc);
1609
1610                 cfs_waitq_signal(&ocw->ocw_waitq);
1611         }
1612
1613         EXIT;
1614 }
1615
1616 static int osc_max_rpc_in_flight(struct client_obd *cli, struct osc_object *osc)
1617 {
1618         int hprpc = !!cfs_list_empty(&osc->oo_hp_exts);
1619         return rpcs_in_flight(cli) >= cli->cl_max_rpcs_in_flight + hprpc;
1620 }
1621
1622 /* This maintains the lists of pending pages to read/write for a given object
1623  * (lop).  This is used by osc_check_rpcs->osc_next_obj() and osc_list_maint()
1624  * to quickly find objects that are ready to send an RPC. */
1625 static int osc_makes_rpc(struct client_obd *cli, struct osc_object *osc,
1626                          int cmd)
1627 {
1628         int invalid_import = 0;
1629         ENTRY;
1630
1631         /* if we have an invalid import we want to drain the queued pages
1632          * by forcing them through rpcs that immediately fail and complete
1633          * the pages.  recovery relies on this to empty the queued pages
1634          * before canceling the locks and evicting down the llite pages */
1635         if ((cli->cl_import == NULL || cli->cl_import->imp_invalid))
1636                 invalid_import = 1;
1637
1638         if (cmd & OBD_BRW_WRITE) {
1639                 if (cfs_atomic_read(&osc->oo_nr_writes) == 0)
1640                         RETURN(0);
1641                 if (invalid_import) {
1642                         CDEBUG(D_CACHE, "invalid import forcing RPC\n");
1643                         RETURN(1);
1644                 }
1645                 if (!cfs_list_empty(&osc->oo_hp_exts)) {
1646                         CDEBUG(D_CACHE, "high prio request forcing RPC\n");
1647                         RETURN(1);
1648                 }
1649                 if (!cfs_list_empty(&osc->oo_urgent_exts)) {
1650                         CDEBUG(D_CACHE, "urgent request forcing RPC\n");
1651                         RETURN(1);
1652                 }
1653                 /* trigger a write rpc stream as long as there are dirtiers
1654                  * waiting for space.  as they're waiting, they're not going to
1655                  * create more pages to coalesce with what's waiting.. */
1656                 if (!cfs_list_empty(&cli->cl_cache_waiters)) {
1657                         CDEBUG(D_CACHE, "cache waiters forcing RPC\n");
1658                         RETURN(1);
1659                 }
1660                 if (cfs_atomic_read(&osc->oo_nr_writes) >=
1661                     cli->cl_max_pages_per_rpc)
1662                         RETURN(1);
1663         } else {
1664                 if (cfs_atomic_read(&osc->oo_nr_reads) == 0)
1665                         RETURN(0);
1666                 if (invalid_import) {
1667                         CDEBUG(D_CACHE, "invalid import forcing RPC\n");
1668                         RETURN(1);
1669                 }
1670                 /* all read are urgent. */
1671                 if (!cfs_list_empty(&osc->oo_reading_exts))
1672                         RETURN(1);
1673         }
1674
1675         RETURN(0);
1676 }
1677
1678 static void osc_update_pending(struct osc_object *obj, int cmd, int delta)
1679 {
1680         struct client_obd *cli = osc_cli(obj);
1681         if (cmd & OBD_BRW_WRITE) {
1682                 cfs_atomic_add(delta, &obj->oo_nr_writes);
1683                 cfs_atomic_add(delta, &cli->cl_pending_w_pages);
1684                 LASSERT(cfs_atomic_read(&obj->oo_nr_writes) >= 0);
1685         } else {
1686                 cfs_atomic_add(delta, &obj->oo_nr_reads);
1687                 cfs_atomic_add(delta, &cli->cl_pending_r_pages);
1688                 LASSERT(cfs_atomic_read(&obj->oo_nr_reads) >= 0);
1689         }
1690         OSC_IO_DEBUG(obj, "update pending cmd %d delta %d.\n", cmd, delta);
1691 }
1692
1693 static int osc_makes_hprpc(struct osc_object *obj)
1694 {
1695         return !cfs_list_empty(&obj->oo_hp_exts);
1696 }
1697
1698 static void on_list(cfs_list_t *item, cfs_list_t *list, int should_be_on)
1699 {
1700         if (cfs_list_empty(item) && should_be_on)
1701                 cfs_list_add_tail(item, list);
1702         else if (!cfs_list_empty(item) && !should_be_on)
1703                 cfs_list_del_init(item);
1704 }
1705
1706 /* maintain the osc's cli list membership invariants so that osc_send_oap_rpc
1707  * can find pages to build into rpcs quickly */
1708 static int __osc_list_maint(struct client_obd *cli, struct osc_object *osc)
1709 {
1710         if (osc_makes_hprpc(osc)) {
1711                 /* HP rpc */
1712                 on_list(&osc->oo_ready_item, &cli->cl_loi_ready_list, 0);
1713                 on_list(&osc->oo_hp_ready_item, &cli->cl_loi_hp_ready_list, 1);
1714         } else {
1715                 on_list(&osc->oo_hp_ready_item, &cli->cl_loi_hp_ready_list, 0);
1716                 on_list(&osc->oo_ready_item, &cli->cl_loi_ready_list,
1717                         osc_makes_rpc(cli, osc, OBD_BRW_WRITE) ||
1718                         osc_makes_rpc(cli, osc, OBD_BRW_READ));
1719         }
1720
1721         on_list(&osc->oo_write_item, &cli->cl_loi_write_list,
1722                 cfs_atomic_read(&osc->oo_nr_writes) > 0);
1723
1724         on_list(&osc->oo_read_item, &cli->cl_loi_read_list,
1725                 cfs_atomic_read(&osc->oo_nr_reads) > 0);
1726
1727         return osc_is_ready(osc);
1728 }
1729
1730 static int osc_list_maint(struct client_obd *cli, struct osc_object *osc)
1731 {
1732         int is_ready;
1733
1734         client_obd_list_lock(&cli->cl_loi_list_lock);
1735         is_ready = __osc_list_maint(cli, osc);
1736         client_obd_list_unlock(&cli->cl_loi_list_lock);
1737
1738         return is_ready;
1739 }
1740
1741 /* this is trying to propogate async writeback errors back up to the
1742  * application.  As an async write fails we record the error code for later if
1743  * the app does an fsync.  As long as errors persist we force future rpcs to be
1744  * sync so that the app can get a sync error and break the cycle of queueing
1745  * pages for which writeback will fail. */
1746 static void osc_process_ar(struct osc_async_rc *ar, __u64 xid,
1747                            int rc)
1748 {
1749         if (rc) {
1750                 if (!ar->ar_rc)
1751                         ar->ar_rc = rc;
1752
1753                 ar->ar_force_sync = 1;
1754                 ar->ar_min_xid = ptlrpc_sample_next_xid();
1755                 return;
1756
1757         }
1758
1759         if (ar->ar_force_sync && (xid >= ar->ar_min_xid))
1760                 ar->ar_force_sync = 0;
1761 }
1762
1763 /* this must be called holding the loi list lock to give coverage to exit_cache,
1764  * async_flag maintenance, and oap_request */
1765 static void osc_ap_completion(const struct lu_env *env, struct client_obd *cli,
1766                               struct osc_async_page *oap, int sent, int rc)
1767 {
1768         struct osc_object *osc = oap->oap_obj;
1769         struct lov_oinfo  *loi = osc->oo_oinfo;
1770         __u64 xid = 0;
1771
1772         ENTRY;
1773         if (oap->oap_request != NULL) {
1774                 xid = ptlrpc_req_xid(oap->oap_request);
1775                 ptlrpc_req_finished(oap->oap_request);
1776                 oap->oap_request = NULL;
1777         }
1778
1779         /* As the transfer for this page is being done, clear the flags */
1780         spin_lock(&oap->oap_lock);
1781         oap->oap_async_flags = 0;
1782         spin_unlock(&oap->oap_lock);
1783         oap->oap_interrupted = 0;
1784
1785         if (oap->oap_cmd & OBD_BRW_WRITE && xid > 0) {
1786                 client_obd_list_lock(&cli->cl_loi_list_lock);
1787                 osc_process_ar(&cli->cl_ar, xid, rc);
1788                 osc_process_ar(&loi->loi_ar, xid, rc);
1789                 client_obd_list_unlock(&cli->cl_loi_list_lock);
1790         }
1791
1792         rc = osc_completion(env, oap, oap->oap_cmd, rc);
1793         if (rc)
1794                 CERROR("completion on oap %p obj %p returns %d.\n",
1795                        oap, osc, rc);
1796
1797         EXIT;
1798 }
1799
1800 /**
1801  * Try to add extent to one RPC. We need to think about the following things:
1802  * - # of pages must not be over max_pages_per_rpc
1803  * - extent must be compatible with previous ones
1804  */
1805 static int try_to_add_extent_for_io(struct client_obd *cli,
1806                                     struct osc_extent *ext, cfs_list_t *rpclist,
1807                                     int *pc, unsigned int *max_pages)
1808 {
1809         struct osc_extent *tmp;
1810         ENTRY;
1811
1812         EASSERT((ext->oe_state == OES_CACHE || ext->oe_state == OES_LOCK_DONE),
1813                 ext);
1814
1815         *max_pages = max(ext->oe_mppr, *max_pages);
1816         if (*pc + ext->oe_nr_pages > *max_pages)
1817                 RETURN(0);
1818
1819         cfs_list_for_each_entry(tmp, rpclist, oe_link) {
1820                 EASSERT(tmp->oe_owner == cfs_current(), tmp);
1821 #if 0
1822                 if (overlapped(tmp, ext)) {
1823                         OSC_EXTENT_DUMP(D_ERROR, tmp, "overlapped %p.\n", ext);
1824                         EASSERT(0, ext);
1825                 }
1826 #endif
1827
1828                 if (tmp->oe_srvlock != ext->oe_srvlock ||
1829                     !tmp->oe_grants != !ext->oe_grants)
1830                         RETURN(0);
1831
1832                 /* remove break for strict check */
1833                 break;
1834         }
1835
1836         *pc += ext->oe_nr_pages;
1837         cfs_list_move_tail(&ext->oe_link, rpclist);
1838         ext->oe_owner = cfs_current();
1839         RETURN(1);
1840 }
1841
1842 /**
1843  * In order to prevent multiple ptlrpcd from breaking contiguous extents,
1844  * get_write_extent() takes all appropriate extents in atomic.
1845  *
1846  * The following policy is used to collect extents for IO:
1847  * 1. Add as many HP extents as possible;
1848  * 2. Add the first urgent extent in urgent extent list and take it out of
1849  *    urgent list;
1850  * 3. Add subsequent extents of this urgent extent;
1851  * 4. If urgent list is not empty, goto 2;
1852  * 5. Traverse the extent tree from the 1st extent;
1853  * 6. Above steps exit if there is no space in this RPC.
1854  */
1855 static int get_write_extents(struct osc_object *obj, cfs_list_t *rpclist)
1856 {
1857         struct client_obd *cli = osc_cli(obj);
1858         struct osc_extent *ext;
1859         int page_count = 0;
1860         unsigned int max_pages = cli->cl_max_pages_per_rpc;
1861
1862         LASSERT(osc_object_is_locked(obj));
1863         while (!cfs_list_empty(&obj->oo_hp_exts)) {
1864                 ext = cfs_list_entry(obj->oo_hp_exts.next, struct osc_extent,
1865                                      oe_link);
1866                 LASSERT(ext->oe_state == OES_CACHE);
1867                 if (!try_to_add_extent_for_io(cli, ext, rpclist, &page_count,
1868                                               &max_pages))
1869                         return page_count;
1870                 EASSERT(ext->oe_nr_pages <= max_pages, ext);
1871         }
1872         if (page_count == max_pages)
1873                 return page_count;
1874
1875         while (!cfs_list_empty(&obj->oo_urgent_exts)) {
1876                 ext = cfs_list_entry(obj->oo_urgent_exts.next,
1877                                      struct osc_extent, oe_link);
1878                 if (!try_to_add_extent_for_io(cli, ext, rpclist, &page_count,
1879                                               &max_pages))
1880                         return page_count;
1881
1882                 if (!ext->oe_intree)
1883                         continue;
1884
1885                 while ((ext = next_extent(ext)) != NULL) {
1886                         if ((ext->oe_state != OES_CACHE) ||
1887                             (!cfs_list_empty(&ext->oe_link) &&
1888                              ext->oe_owner != NULL))
1889                                 continue;
1890
1891                         if (!try_to_add_extent_for_io(cli, ext, rpclist,
1892                                                       &page_count, &max_pages))
1893                                 return page_count;
1894                 }
1895         }
1896         if (page_count == max_pages)
1897                 return page_count;
1898
1899         ext = first_extent(obj);
1900         while (ext != NULL) {
1901                 if ((ext->oe_state != OES_CACHE) ||
1902                     /* this extent may be already in current rpclist */
1903                     (!cfs_list_empty(&ext->oe_link) && ext->oe_owner != NULL)) {
1904                         ext = next_extent(ext);
1905                         continue;
1906                 }
1907
1908                 if (!try_to_add_extent_for_io(cli, ext, rpclist, &page_count,
1909                                               &max_pages))
1910                         return page_count;
1911
1912                 ext = next_extent(ext);
1913         }
1914         return page_count;
1915 }
1916
1917 static int
1918 osc_send_write_rpc(const struct lu_env *env, struct client_obd *cli,
1919                    struct osc_object *osc, pdl_policy_t pol)
1920 {
1921         CFS_LIST_HEAD(rpclist);
1922         struct osc_extent *ext;
1923         struct osc_extent *tmp;
1924         struct osc_extent *first = NULL;
1925         obd_count page_count = 0;
1926         int srvlock = 0;
1927         int rc = 0;
1928         ENTRY;
1929
1930         LASSERT(osc_object_is_locked(osc));
1931
1932         page_count = get_write_extents(osc, &rpclist);
1933         LASSERT(equi(page_count == 0, cfs_list_empty(&rpclist)));
1934
1935         if (cfs_list_empty(&rpclist))
1936                 RETURN(0);
1937
1938         osc_update_pending(osc, OBD_BRW_WRITE, -page_count);
1939
1940         cfs_list_for_each_entry(ext, &rpclist, oe_link) {
1941                 LASSERT(ext->oe_state == OES_CACHE ||
1942                         ext->oe_state == OES_LOCK_DONE);
1943                 if (ext->oe_state == OES_CACHE)
1944                         osc_extent_state_set(ext, OES_LOCKING);
1945                 else
1946                         osc_extent_state_set(ext, OES_RPC);
1947         }
1948
1949         /* we're going to grab page lock, so release object lock because
1950          * lock order is page lock -> object lock. */
1951         osc_object_unlock(osc);
1952
1953         cfs_list_for_each_entry_safe(ext, tmp, &rpclist, oe_link) {
1954                 if (ext->oe_state == OES_LOCKING) {
1955                         rc = osc_extent_make_ready(env, ext);
1956                         if (unlikely(rc < 0)) {
1957                                 cfs_list_del_init(&ext->oe_link);
1958                                 osc_extent_finish(env, ext, 0, rc);
1959                                 continue;
1960                         }
1961                 }
1962                 if (first == NULL) {
1963                         first = ext;
1964                         srvlock = ext->oe_srvlock;
1965                 } else {
1966                         LASSERT(srvlock == ext->oe_srvlock);
1967                 }
1968         }
1969
1970         if (!cfs_list_empty(&rpclist)) {
1971                 LASSERT(page_count > 0);
1972                 rc = osc_build_rpc(env, cli, &rpclist, OBD_BRW_WRITE, pol);
1973                 LASSERT(cfs_list_empty(&rpclist));
1974         }
1975
1976         osc_object_lock(osc);
1977         RETURN(rc);
1978 }
1979
1980 /**
1981  * prepare pages for ASYNC io and put pages in send queue.
1982  *
1983  * \param cmd OBD_BRW_* macroses
1984  * \param lop pending pages
1985  *
1986  * \return zero if no page added to send queue.
1987  * \return 1 if pages successfully added to send queue.
1988  * \return negative on errors.
1989  */
1990 static int
1991 osc_send_read_rpc(const struct lu_env *env, struct client_obd *cli,
1992                   struct osc_object *osc, pdl_policy_t pol)
1993 {
1994         struct osc_extent *ext;
1995         struct osc_extent *next;
1996         CFS_LIST_HEAD(rpclist);
1997         int page_count = 0;
1998         unsigned int max_pages = cli->cl_max_pages_per_rpc;
1999         int rc = 0;
2000         ENTRY;
2001
2002         LASSERT(osc_object_is_locked(osc));
2003         cfs_list_for_each_entry_safe(ext, next,
2004                                      &osc->oo_reading_exts, oe_link) {
2005                 EASSERT(ext->oe_state == OES_LOCK_DONE, ext);
2006                 if (!try_to_add_extent_for_io(cli, ext, &rpclist, &page_count,
2007                                               &max_pages))
2008                         break;
2009                 osc_extent_state_set(ext, OES_RPC);
2010                 EASSERT(ext->oe_nr_pages <= max_pages, ext);
2011         }
2012         LASSERT(page_count <= max_pages);
2013
2014         osc_update_pending(osc, OBD_BRW_READ, -page_count);
2015
2016         if (!cfs_list_empty(&rpclist)) {
2017                 osc_object_unlock(osc);
2018
2019                 LASSERT(page_count > 0);
2020                 rc = osc_build_rpc(env, cli, &rpclist, OBD_BRW_READ, pol);
2021                 LASSERT(cfs_list_empty(&rpclist));
2022
2023                 osc_object_lock(osc);
2024         }
2025         RETURN(rc);
2026 }
2027
2028 #define list_to_obj(list, item) ({                                            \
2029         cfs_list_t *__tmp = (list)->next;                                     \
2030         cfs_list_del_init(__tmp);                                             \
2031         cfs_list_entry(__tmp, struct osc_object, oo_##item);                  \
2032 })
2033
2034 /* This is called by osc_check_rpcs() to find which objects have pages that
2035  * we could be sending.  These lists are maintained by osc_makes_rpc(). */
2036 static struct osc_object *osc_next_obj(struct client_obd *cli)
2037 {
2038         ENTRY;
2039
2040         /* First return objects that have blocked locks so that they
2041          * will be flushed quickly and other clients can get the lock,
2042          * then objects which have pages ready to be stuffed into RPCs */
2043         if (!cfs_list_empty(&cli->cl_loi_hp_ready_list))
2044                 RETURN(list_to_obj(&cli->cl_loi_hp_ready_list, hp_ready_item));
2045         if (!cfs_list_empty(&cli->cl_loi_ready_list))
2046                 RETURN(list_to_obj(&cli->cl_loi_ready_list, ready_item));
2047
2048         /* then if we have cache waiters, return all objects with queued
2049          * writes.  This is especially important when many small files
2050          * have filled up the cache and not been fired into rpcs because
2051          * they don't pass the nr_pending/object threshhold */
2052         if (!cfs_list_empty(&cli->cl_cache_waiters) &&
2053             !cfs_list_empty(&cli->cl_loi_write_list))
2054                 RETURN(list_to_obj(&cli->cl_loi_write_list, write_item));
2055
2056         /* then return all queued objects when we have an invalid import
2057          * so that they get flushed */
2058         if (cli->cl_import == NULL || cli->cl_import->imp_invalid) {
2059                 if (!cfs_list_empty(&cli->cl_loi_write_list))
2060                         RETURN(list_to_obj(&cli->cl_loi_write_list,
2061                                            write_item));
2062                 if (!cfs_list_empty(&cli->cl_loi_read_list))
2063                         RETURN(list_to_obj(&cli->cl_loi_read_list,
2064                                            read_item));
2065         }
2066         RETURN(NULL);
2067 }
2068
2069 /* called with the loi list lock held */
2070 static void osc_check_rpcs(const struct lu_env *env, struct client_obd *cli,
2071                            pdl_policy_t pol)
2072 {
2073         struct osc_object *osc;
2074         int rc = 0;
2075         ENTRY;
2076
2077         while ((osc = osc_next_obj(cli)) != NULL) {
2078                 struct cl_object *obj = osc2cl(osc);
2079                 struct lu_ref_link link;
2080
2081                 OSC_IO_DEBUG(osc, "%lu in flight\n", rpcs_in_flight(cli));
2082
2083                 if (osc_max_rpc_in_flight(cli, osc)) {
2084                         __osc_list_maint(cli, osc);
2085                         break;
2086                 }
2087
2088                 cl_object_get(obj);
2089                 client_obd_list_unlock(&cli->cl_loi_list_lock);
2090                 lu_object_ref_add_at(&obj->co_lu, &link, "check",
2091                                      cfs_current());
2092
2093                 /* attempt some read/write balancing by alternating between
2094                  * reads and writes in an object.  The makes_rpc checks here
2095                  * would be redundant if we were getting read/write work items
2096                  * instead of objects.  we don't want send_oap_rpc to drain a
2097                  * partial read pending queue when we're given this object to
2098                  * do io on writes while there are cache waiters */
2099                 osc_object_lock(osc);
2100                 if (osc_makes_rpc(cli, osc, OBD_BRW_WRITE)) {
2101                         rc = osc_send_write_rpc(env, cli, osc, pol);
2102                         if (rc < 0) {
2103                                 CERROR("Write request failed with %d\n", rc);
2104
2105                                 /* osc_send_write_rpc failed, mostly because of
2106                                  * memory pressure.
2107                                  *
2108                                  * It can't break here, because if:
2109                                  *  - a page was submitted by osc_io_submit, so
2110                                  *    page locked;
2111                                  *  - no request in flight
2112                                  *  - no subsequent request
2113                                  * The system will be in live-lock state,
2114                                  * because there is no chance to call
2115                                  * osc_io_unplug() and osc_check_rpcs() any
2116                                  * more. pdflush can't help in this case,
2117                                  * because it might be blocked at grabbing
2118                                  * the page lock as we mentioned.
2119                                  *
2120                                  * Anyway, continue to drain pages. */
2121                                 /* break; */
2122                         }
2123                 }
2124                 if (osc_makes_rpc(cli, osc, OBD_BRW_READ)) {
2125                         rc = osc_send_read_rpc(env, cli, osc, pol);
2126                         if (rc < 0)
2127                                 CERROR("Read request failed with %d\n", rc);
2128                 }
2129                 osc_object_unlock(osc);
2130
2131                 osc_list_maint(cli, osc);
2132                 lu_object_ref_del_at(&obj->co_lu, &link, "check",
2133                                      cfs_current());
2134                 cl_object_put(env, obj);
2135
2136                 client_obd_list_lock(&cli->cl_loi_list_lock);
2137         }
2138 }
2139
2140 static int osc_io_unplug0(const struct lu_env *env, struct client_obd *cli,
2141                           struct osc_object *osc, pdl_policy_t pol, int async)
2142 {
2143         int rc = 0;
2144
2145         if (osc != NULL && osc_list_maint(cli, osc) == 0)
2146                 return 0;
2147
2148         if (!async) {
2149                 /* disable osc_lru_shrink() temporarily to avoid
2150                  * potential stack overrun problem. LU-2859 */
2151                 cfs_atomic_inc(&cli->cl_lru_shrinkers);
2152                 client_obd_list_lock(&cli->cl_loi_list_lock);
2153                 osc_check_rpcs(env, cli, pol);
2154                 client_obd_list_unlock(&cli->cl_loi_list_lock);
2155                 cfs_atomic_dec(&cli->cl_lru_shrinkers);
2156         } else {
2157                 CDEBUG(D_CACHE, "Queue writeback work for client %p.\n", cli);
2158                 LASSERT(cli->cl_writeback_work != NULL);
2159                 rc = ptlrpcd_queue_work(cli->cl_writeback_work);
2160         }
2161         return rc;
2162 }
2163
2164 static int osc_io_unplug_async(const struct lu_env *env,
2165                                 struct client_obd *cli, struct osc_object *osc)
2166 {
2167         /* XXX: policy is no use actually. */
2168         return osc_io_unplug0(env, cli, osc, PDL_POLICY_ROUND, 1);
2169 }
2170
2171 void osc_io_unplug(const struct lu_env *env, struct client_obd *cli,
2172                    struct osc_object *osc, pdl_policy_t pol)
2173 {
2174         (void)osc_io_unplug0(env, cli, osc, pol, 0);
2175 }
2176
2177 int osc_prep_async_page(struct osc_object *osc, struct osc_page *ops,
2178                         struct page *page, loff_t offset)
2179 {
2180         struct obd_export     *exp = osc_export(osc);
2181         struct osc_async_page *oap = &ops->ops_oap;
2182         ENTRY;
2183
2184         if (!page)
2185                 return cfs_size_round(sizeof(*oap));
2186
2187         oap->oap_magic = OAP_MAGIC;
2188         oap->oap_cli = &exp->exp_obd->u.cli;
2189         oap->oap_obj = osc;
2190
2191         oap->oap_page = page;
2192         oap->oap_obj_off = offset;
2193         LASSERT(!(offset & ~CFS_PAGE_MASK));
2194
2195         if (!client_is_remote(exp) && cfs_capable(CFS_CAP_SYS_RESOURCE))
2196                 oap->oap_brw_flags = OBD_BRW_NOQUOTA;
2197
2198         CFS_INIT_LIST_HEAD(&oap->oap_pending_item);
2199         CFS_INIT_LIST_HEAD(&oap->oap_rpc_item);
2200
2201         spin_lock_init(&oap->oap_lock);
2202         CDEBUG(D_INFO, "oap %p page %p obj off "LPU64"\n",
2203                oap, page, oap->oap_obj_off);
2204         RETURN(0);
2205 }
2206
2207 int osc_queue_async_io(const struct lu_env *env, struct cl_io *io,
2208                        struct osc_page *ops)
2209 {
2210         struct osc_io *oio = osc_env_io(env);
2211         struct osc_extent     *ext = NULL;
2212         struct osc_async_page *oap = &ops->ops_oap;
2213         struct client_obd     *cli = oap->oap_cli;
2214         struct osc_object     *osc = oap->oap_obj;
2215         pgoff_t index;
2216         int    grants = 0;
2217         int    brw_flags = OBD_BRW_ASYNC;
2218         int    cmd = OBD_BRW_WRITE;
2219         int    need_release = 0;
2220         int    rc = 0;
2221         ENTRY;
2222
2223         if (oap->oap_magic != OAP_MAGIC)
2224                 RETURN(-EINVAL);
2225
2226         if (cli->cl_import == NULL || cli->cl_import->imp_invalid)
2227                 RETURN(-EIO);
2228
2229         if (!cfs_list_empty(&oap->oap_pending_item) ||
2230             !cfs_list_empty(&oap->oap_rpc_item))
2231                 RETURN(-EBUSY);
2232
2233         /* Set the OBD_BRW_SRVLOCK before the page is queued. */
2234         brw_flags |= ops->ops_srvlock ? OBD_BRW_SRVLOCK : 0;
2235         if (!client_is_remote(osc_export(osc)) &&
2236             cfs_capable(CFS_CAP_SYS_RESOURCE)) {
2237                 brw_flags |= OBD_BRW_NOQUOTA;
2238                 cmd |= OBD_BRW_NOQUOTA;
2239         }
2240
2241         /* check if the file's owner/group is over quota */
2242         if (!(cmd & OBD_BRW_NOQUOTA)) {
2243                 struct cl_object *obj;
2244                 struct cl_attr   *attr;
2245                 unsigned int qid[MAXQUOTAS];
2246
2247                 obj = cl_object_top(&osc->oo_cl);
2248                 attr = &osc_env_info(env)->oti_attr;
2249
2250                 cl_object_attr_lock(obj);
2251                 rc = cl_object_attr_get(env, obj, attr);
2252                 cl_object_attr_unlock(obj);
2253
2254                 qid[USRQUOTA] = attr->cat_uid;
2255                 qid[GRPQUOTA] = attr->cat_gid;
2256                 if (rc == 0 && osc_quota_chkdq(cli, qid) == NO_QUOTA)
2257                         rc = -EDQUOT;
2258                 if (rc)
2259                         RETURN(rc);
2260         }
2261
2262         oap->oap_cmd = cmd;
2263         oap->oap_page_off = ops->ops_from;
2264         oap->oap_count = ops->ops_to - ops->ops_from;
2265         oap->oap_async_flags = 0;
2266         oap->oap_brw_flags = brw_flags;
2267
2268         OSC_IO_DEBUG(osc, "oap %p page %p added for cmd %d\n",
2269                      oap, oap->oap_page, oap->oap_cmd & OBD_BRW_RWMASK);
2270
2271         index = oap2cl_page(oap)->cp_index;
2272
2273         /* Add this page into extent by the following steps:
2274          * 1. if there exists an active extent for this IO, mostly this page
2275          *    can be added to the active extent and sometimes we need to
2276          *    expand extent to accomodate this page;
2277          * 2. otherwise, a new extent will be allocated. */
2278
2279         ext = oio->oi_active;
2280         if (ext != NULL && ext->oe_start <= index && ext->oe_max_end >= index) {
2281                 /* one chunk plus extent overhead must be enough to write this
2282                  * page */
2283                 grants = (1 << cli->cl_chunkbits) + cli->cl_extent_tax;
2284                 if (ext->oe_end >= index)
2285                         grants = 0;
2286
2287                 /* it doesn't need any grant to dirty this page */
2288                 client_obd_list_lock(&cli->cl_loi_list_lock);
2289                 rc = osc_enter_cache_try(cli, oap, grants, 0);
2290                 client_obd_list_unlock(&cli->cl_loi_list_lock);
2291                 if (rc == 0) { /* try failed */
2292                         grants = 0;
2293                         need_release = 1;
2294                 } else if (ext->oe_end < index) {
2295                         int tmp = grants;
2296                         /* try to expand this extent */
2297                         rc = osc_extent_expand(ext, index, &tmp);
2298                         if (rc < 0) {
2299                                 need_release = 1;
2300                                 /* don't free reserved grant */
2301                         } else {
2302                                 OSC_EXTENT_DUMP(D_CACHE, ext,
2303                                                 "expanded for %lu.\n", index);
2304                                 osc_unreserve_grant(cli, grants, tmp);
2305                                 grants = 0;
2306                         }
2307                 }
2308                 rc = 0;
2309         } else if (ext != NULL) {
2310                 /* index is located outside of active extent */
2311                 need_release = 1;
2312         }
2313         if (need_release) {
2314                 osc_extent_release(env, ext);
2315                 oio->oi_active = NULL;
2316                 ext = NULL;
2317         }
2318
2319         if (ext == NULL) {
2320                 int tmp = (1 << cli->cl_chunkbits) + cli->cl_extent_tax;
2321
2322                 /* try to find new extent to cover this page */
2323                 LASSERT(oio->oi_active == NULL);
2324                 /* we may have allocated grant for this page if we failed
2325                  * to expand the previous active extent. */
2326                 LASSERT(ergo(grants > 0, grants >= tmp));
2327
2328                 rc = 0;
2329                 if (grants == 0) {
2330                         /* we haven't allocated grant for this page. */
2331                         rc = osc_enter_cache(env, cli, oap, tmp);
2332                         if (rc == 0)
2333                                 grants = tmp;
2334                 }
2335
2336                 tmp = grants;
2337                 if (rc == 0) {
2338                         ext = osc_extent_find(env, osc, index, &tmp);
2339                         if (IS_ERR(ext)) {
2340                                 LASSERT(tmp == grants);
2341                                 osc_exit_cache(cli, oap);
2342                                 rc = PTR_ERR(ext);
2343                                 ext = NULL;
2344                         } else {
2345                                 oio->oi_active = ext;
2346                         }
2347                 }
2348                 if (grants > 0)
2349                         osc_unreserve_grant(cli, grants, tmp);
2350         }
2351
2352         LASSERT(ergo(rc == 0, ext != NULL));
2353         if (ext != NULL) {
2354                 EASSERTF(ext->oe_end >= index && ext->oe_start <= index,
2355                          ext, "index = %lu.\n", index);
2356                 LASSERT((oap->oap_brw_flags & OBD_BRW_FROM_GRANT) != 0);
2357
2358                 osc_object_lock(osc);
2359                 if (ext->oe_nr_pages == 0)
2360                         ext->oe_srvlock = ops->ops_srvlock;
2361                 else
2362                         LASSERT(ext->oe_srvlock == ops->ops_srvlock);
2363                 ++ext->oe_nr_pages;
2364                 cfs_list_add_tail(&oap->oap_pending_item, &ext->oe_pages);
2365                 osc_object_unlock(osc);
2366         }
2367         RETURN(rc);
2368 }
2369
2370 int osc_teardown_async_page(const struct lu_env *env,
2371                             struct osc_object *obj, struct osc_page *ops)
2372 {
2373         struct osc_async_page *oap = &ops->ops_oap;
2374         struct osc_extent     *ext = NULL;
2375         int rc = 0;
2376         ENTRY;
2377
2378         LASSERT(oap->oap_magic == OAP_MAGIC);
2379
2380         CDEBUG(D_INFO, "teardown oap %p page %p at index %lu.\n",
2381                oap, ops, oap2cl_page(oap)->cp_index);
2382
2383         osc_object_lock(obj);
2384         if (!cfs_list_empty(&oap->oap_rpc_item)) {
2385                 CDEBUG(D_CACHE, "oap %p is not in cache.\n", oap);
2386                 rc = -EBUSY;
2387         } else if (!cfs_list_empty(&oap->oap_pending_item)) {
2388                 ext = osc_extent_lookup(obj, oap2cl_page(oap)->cp_index);
2389                 /* only truncated pages are allowed to be taken out.
2390                  * See osc_extent_truncate() and osc_cache_truncate_start()
2391                  * for details. */
2392                 if (ext != NULL && ext->oe_state != OES_TRUNC) {
2393                         OSC_EXTENT_DUMP(D_ERROR, ext, "trunc at %lu.\n",
2394                                         oap2cl_page(oap)->cp_index);
2395                         rc = -EBUSY;
2396                 }
2397         }
2398         osc_object_unlock(obj);
2399         if (ext != NULL)
2400                 osc_extent_put(env, ext);
2401         RETURN(rc);
2402 }
2403
2404 /**
2405  * This is called when a page is picked up by kernel to write out.
2406  *
2407  * We should find out the corresponding extent and add the whole extent
2408  * into urgent list. The extent may be being truncated or used, handle it
2409  * carefully.
2410  */
2411 int osc_flush_async_page(const struct lu_env *env, struct cl_io *io,
2412                          struct osc_page *ops)
2413 {
2414         struct osc_extent *ext   = NULL;
2415         struct osc_object *obj   = cl2osc(ops->ops_cl.cpl_obj);
2416         struct cl_page    *cp    = ops->ops_cl.cpl_page;
2417         pgoff_t            index = cp->cp_index;
2418         struct osc_async_page *oap = &ops->ops_oap;
2419         bool unplug = false;
2420         int rc = 0;
2421         ENTRY;
2422
2423         osc_object_lock(obj);
2424         ext = osc_extent_lookup(obj, index);
2425         if (ext == NULL) {
2426                 osc_extent_tree_dump(D_ERROR, obj);
2427                 LASSERTF(0, "page index %lu is NOT covered.\n", index);
2428         }
2429
2430         switch (ext->oe_state) {
2431         case OES_RPC:
2432         case OES_LOCK_DONE:
2433                 CL_PAGE_DEBUG(D_ERROR, env, cl_page_top(cp),
2434                               "flush an in-rpc page?\n");
2435                 LASSERT(0);
2436                 break;
2437         case OES_LOCKING:
2438                 /* If we know this extent is being written out, we should abort
2439                  * so that the writer can make this page ready. Otherwise, there
2440                  * exists a deadlock problem because other process can wait for
2441                  * page writeback bit holding page lock; and meanwhile in
2442                  * vvp_page_make_ready(), we need to grab page lock before
2443                  * really sending the RPC. */
2444         case OES_TRUNC:
2445                 /* race with truncate, page will be redirtied */
2446                 GOTO(out, rc = -EAGAIN);
2447         default:
2448                 break;
2449         }
2450
2451         rc = cl_page_prep(env, io, cl_page_top(cp), CRT_WRITE);
2452         if (rc)
2453                 GOTO(out, rc);
2454
2455         spin_lock(&oap->oap_lock);
2456         oap->oap_async_flags |= ASYNC_READY|ASYNC_URGENT;
2457         spin_unlock(&oap->oap_lock);
2458
2459         if (memory_pressure_get())
2460                 ext->oe_memalloc = 1;
2461
2462         ext->oe_urgent = 1;
2463         if (ext->oe_state == OES_CACHE) {
2464                 OSC_EXTENT_DUMP(D_CACHE, ext,
2465                                 "flush page %p make it urgent.\n", oap);
2466                 if (cfs_list_empty(&ext->oe_link))
2467                         cfs_list_add_tail(&ext->oe_link, &obj->oo_urgent_exts);
2468                 unplug = true;
2469         }
2470         rc = 0;
2471         EXIT;
2472
2473 out:
2474         osc_object_unlock(obj);
2475         osc_extent_put(env, ext);
2476         if (unplug)
2477                 osc_io_unplug_async(env, osc_cli(obj), obj);
2478         return rc;
2479 }
2480
2481 /**
2482  * this is called when a sync waiter receives an interruption.  Its job is to
2483  * get the caller woken as soon as possible.  If its page hasn't been put in an
2484  * rpc yet it can dequeue immediately.  Otherwise it has to mark the rpc as
2485  * desiring interruption which will forcefully complete the rpc once the rpc
2486  * has timed out.
2487  */
2488 int osc_cancel_async_page(const struct lu_env *env, struct osc_page *ops)
2489 {
2490         struct osc_async_page *oap = &ops->ops_oap;
2491         struct osc_object     *obj = oap->oap_obj;
2492         struct client_obd     *cli = osc_cli(obj);
2493         struct osc_extent     *ext;
2494         struct osc_extent     *found = NULL;
2495         cfs_list_t            *plist;
2496         pgoff_t index = oap2cl_page(oap)->cp_index;
2497         int     rc = -EBUSY;
2498         int     cmd;
2499         ENTRY;
2500
2501         LASSERT(!oap->oap_interrupted);
2502         oap->oap_interrupted = 1;
2503
2504         /* Find out the caching extent */
2505         osc_object_lock(obj);
2506         if (oap->oap_cmd & OBD_BRW_WRITE) {
2507                 plist = &obj->oo_urgent_exts;
2508                 cmd   = OBD_BRW_WRITE;
2509         } else {
2510                 plist = &obj->oo_reading_exts;
2511                 cmd   = OBD_BRW_READ;
2512         }
2513         cfs_list_for_each_entry(ext, plist, oe_link) {
2514                 if (ext->oe_start <= index && ext->oe_end >= index) {
2515                         LASSERT(ext->oe_state == OES_LOCK_DONE);
2516                         /* For OES_LOCK_DONE state extent, it has already held
2517                          * a refcount for RPC. */
2518                         found = osc_extent_get(ext);
2519                         break;
2520                 }
2521         }
2522         if (found != NULL) {
2523                 cfs_list_del_init(&found->oe_link);
2524                 osc_update_pending(obj, cmd, -found->oe_nr_pages);
2525                 osc_object_unlock(obj);
2526
2527                 osc_extent_finish(env, found, 0, -EINTR);
2528                 osc_extent_put(env, found);
2529                 rc = 0;
2530         } else {
2531                 osc_object_unlock(obj);
2532                 /* ok, it's been put in an rpc. only one oap gets a request
2533                  * reference */
2534                 if (oap->oap_request != NULL) {
2535                         ptlrpc_mark_interrupted(oap->oap_request);
2536                         ptlrpcd_wake(oap->oap_request);
2537                         ptlrpc_req_finished(oap->oap_request);
2538                         oap->oap_request = NULL;
2539                 }
2540         }
2541
2542         osc_list_maint(cli, obj);
2543         RETURN(rc);
2544 }
2545
2546 int osc_queue_sync_pages(const struct lu_env *env, struct osc_object *obj,
2547                          cfs_list_t *list, int cmd, int brw_flags)
2548 {
2549         struct client_obd     *cli = osc_cli(obj);
2550         struct osc_extent     *ext;
2551         struct osc_async_page *oap;
2552         int     page_count = 0;
2553         int     mppr       = cli->cl_max_pages_per_rpc;
2554         pgoff_t start      = CL_PAGE_EOF;
2555         pgoff_t end        = 0;
2556         ENTRY;
2557
2558         cfs_list_for_each_entry(oap, list, oap_pending_item) {
2559                 struct cl_page *cp = oap2cl_page(oap);
2560                 if (cp->cp_index > end)
2561                         end = cp->cp_index;
2562                 if (cp->cp_index < start)
2563                         start = cp->cp_index;
2564                 ++page_count;
2565                 mppr <<= (page_count > mppr);
2566         }
2567
2568         ext = osc_extent_alloc(obj);
2569         if (ext == NULL) {
2570                 cfs_list_for_each_entry(oap, list, oap_pending_item) {
2571                         cfs_list_del_init(&oap->oap_pending_item);
2572                         osc_ap_completion(env, cli, oap, 0, -ENOMEM);
2573                 }
2574                 RETURN(-ENOMEM);
2575         }
2576
2577         ext->oe_rw = !!(cmd & OBD_BRW_READ);
2578         ext->oe_urgent = 1;
2579         ext->oe_start = start;
2580         ext->oe_end = ext->oe_max_end = end;
2581         ext->oe_obj = obj;
2582         ext->oe_srvlock = !!(brw_flags & OBD_BRW_SRVLOCK);
2583         ext->oe_nr_pages = page_count;
2584         ext->oe_mppr = mppr;
2585         cfs_list_splice_init(list, &ext->oe_pages);
2586
2587         osc_object_lock(obj);
2588         /* Reuse the initial refcount for RPC, don't drop it */
2589         osc_extent_state_set(ext, OES_LOCK_DONE);
2590         if (cmd & OBD_BRW_WRITE) {
2591                 cfs_list_add_tail(&ext->oe_link, &obj->oo_urgent_exts);
2592                 osc_update_pending(obj, OBD_BRW_WRITE, page_count);
2593         } else {
2594                 cfs_list_add_tail(&ext->oe_link, &obj->oo_reading_exts);
2595                 osc_update_pending(obj, OBD_BRW_READ, page_count);
2596         }
2597         osc_object_unlock(obj);
2598
2599         osc_io_unplug(env, cli, obj, PDL_POLICY_ROUND);
2600         RETURN(0);
2601 }
2602
2603 /**
2604  * Called by osc_io_setattr_start() to freeze and destroy covering extents.
2605  */
2606 int osc_cache_truncate_start(const struct lu_env *env, struct osc_io *oio,
2607                              struct osc_object *obj, __u64 size)
2608 {
2609         struct client_obd *cli = osc_cli(obj);
2610         struct osc_extent *ext;
2611         struct osc_extent *waiting = NULL;
2612         pgoff_t index;
2613         CFS_LIST_HEAD(list);
2614         int result = 0;
2615         bool partial;
2616         ENTRY;
2617
2618         /* pages with index greater or equal to index will be truncated. */
2619         index = cl_index(osc2cl(obj), size);
2620         partial = size > cl_offset(osc2cl(obj), index);
2621
2622 again:
2623         osc_object_lock(obj);
2624         ext = osc_extent_search(obj, index);
2625         if (ext == NULL)
2626                 ext = first_extent(obj);
2627         else if (ext->oe_end < index)
2628                 ext = next_extent(ext);
2629         while (ext != NULL) {
2630                 EASSERT(ext->oe_state != OES_TRUNC, ext);
2631
2632                 if (ext->oe_state > OES_CACHE || ext->oe_urgent) {
2633                         /* if ext is in urgent state, it means there must exist
2634                          * a page already having been flushed by write_page().
2635                          * We have to wait for this extent because we can't
2636                          * truncate that page. */
2637                         LASSERT(!ext->oe_hp);
2638                         OSC_EXTENT_DUMP(D_CACHE, ext,
2639                                         "waiting for busy extent\n");
2640                         waiting = osc_extent_get(ext);
2641                         break;
2642                 }
2643
2644                 OSC_EXTENT_DUMP(D_CACHE, ext, "try to trunc:"LPU64".\n", size);
2645
2646                 osc_extent_get(ext);
2647                 if (ext->oe_state == OES_ACTIVE) {
2648                         /* though we grab inode mutex for write path, but we
2649                          * release it before releasing extent(in osc_io_end()),
2650                          * so there is a race window that an extent is still
2651                          * in OES_ACTIVE when truncate starts. */
2652                         LASSERT(!ext->oe_trunc_pending);
2653                         ext->oe_trunc_pending = 1;
2654                 } else {
2655                         EASSERT(ext->oe_state == OES_CACHE, ext);
2656                         osc_extent_state_set(ext, OES_TRUNC);
2657                         osc_update_pending(obj, OBD_BRW_WRITE,
2658                                            -ext->oe_nr_pages);
2659                 }
2660                 EASSERT(cfs_list_empty(&ext->oe_link), ext);
2661                 cfs_list_add_tail(&ext->oe_link, &list);
2662
2663                 ext = next_extent(ext);
2664         }
2665         osc_object_unlock(obj);
2666
2667         osc_list_maint(cli, obj);
2668
2669         while (!cfs_list_empty(&list)) {
2670                 int rc;
2671
2672                 ext = cfs_list_entry(list.next, struct osc_extent, oe_link);
2673                 cfs_list_del_init(&ext->oe_link);
2674
2675                 /* extent may be in OES_ACTIVE state because inode mutex
2676                  * is released before osc_io_end() in file write case */
2677                 if (ext->oe_state != OES_TRUNC)
2678                         osc_extent_wait(env, ext, OES_TRUNC);
2679
2680                 rc = osc_extent_truncate(ext, index, partial);
2681                 if (rc < 0) {
2682                         if (result == 0)
2683                                 result = rc;
2684
2685                         OSC_EXTENT_DUMP(D_ERROR, ext,
2686                                         "truncate error %d\n", rc);
2687                 } else if (ext->oe_nr_pages == 0) {
2688                         osc_extent_remove(ext);
2689                 } else {
2690                         /* this must be an overlapped extent which means only
2691                          * part of pages in this extent have been truncated.
2692                          */
2693                         EASSERTF(ext->oe_start <= index, ext,
2694                                  "trunc index = %lu/%d.\n", index, partial);
2695                         /* fix index to skip this partially truncated extent */
2696                         index = ext->oe_end + 1;
2697                         partial = false;
2698
2699                         /* we need to hold this extent in OES_TRUNC state so
2700                          * that no writeback will happen. This is to avoid
2701                          * BUG 17397. */
2702                         LASSERT(oio->oi_trunc == NULL);
2703                         oio->oi_trunc = osc_extent_get(ext);
2704                         OSC_EXTENT_DUMP(D_CACHE, ext,
2705                                         "trunc at "LPU64"\n", size);
2706                 }
2707                 osc_extent_put(env, ext);
2708         }
2709         if (waiting != NULL) {
2710                 int rc;
2711
2712                 /* ignore the result of osc_extent_wait the write initiator
2713                  * should take care of it. */
2714                 rc = osc_extent_wait(env, waiting, OES_INV);
2715                 if (rc < 0)
2716                         OSC_EXTENT_DUMP(D_CACHE, waiting, "error: %d.\n", rc);
2717
2718                 osc_extent_put(env, waiting);
2719                 waiting = NULL;
2720                 goto again;
2721         }
2722         RETURN(result);
2723 }
2724
2725 /**
2726  * Called after osc_io_setattr_end to add oio->oi_trunc back to cache.
2727  */
2728 void osc_cache_truncate_end(const struct lu_env *env, struct osc_io *oio,
2729                             struct osc_object *obj)
2730 {
2731         struct osc_extent *ext = oio->oi_trunc;
2732
2733         oio->oi_trunc = NULL;
2734         if (ext != NULL) {
2735                 bool unplug = false;
2736
2737                 EASSERT(ext->oe_nr_pages > 0, ext);
2738                 EASSERT(ext->oe_state == OES_TRUNC, ext);
2739                 EASSERT(!ext->oe_urgent, ext);
2740
2741                 OSC_EXTENT_DUMP(D_CACHE, ext, "trunc -> cache.\n");
2742                 osc_object_lock(obj);
2743                 osc_extent_state_set(ext, OES_CACHE);
2744                 if (ext->oe_fsync_wait && !ext->oe_urgent) {
2745                         ext->oe_urgent = 1;
2746                         cfs_list_move_tail(&ext->oe_link, &obj->oo_urgent_exts);
2747                         unplug = true;
2748                 }
2749                 osc_update_pending(obj, OBD_BRW_WRITE, ext->oe_nr_pages);
2750                 osc_object_unlock(obj);
2751                 osc_extent_put(env, ext);
2752
2753                 if (unplug)
2754                         osc_io_unplug_async(env, osc_cli(obj), obj);
2755         }
2756 }
2757
2758 /**
2759  * Wait for extents in a specific range to be written out.
2760  * The caller must have called osc_cache_writeback_range() to issue IO
2761  * otherwise it will take a long time for this function to finish.
2762  *
2763  * Caller must hold inode_mutex , or cancel exclusive dlm lock so that
2764  * nobody else can dirty this range of file while we're waiting for
2765  * extents to be written.
2766  */
2767 int osc_cache_wait_range(const struct lu_env *env, struct osc_object *obj,
2768                          pgoff_t start, pgoff_t end)
2769 {
2770         struct osc_extent *ext;
2771         pgoff_t index = start;
2772         int     result = 0;
2773         ENTRY;
2774
2775 again:
2776         osc_object_lock(obj);
2777         ext = osc_extent_search(obj, index);
2778         if (ext == NULL)
2779                 ext = first_extent(obj);
2780         else if (ext->oe_end < index)
2781                 ext = next_extent(ext);
2782         while (ext != NULL) {
2783                 int rc;
2784
2785                 if (ext->oe_start > end)
2786                         break;
2787
2788                 if (!ext->oe_fsync_wait) {
2789                         ext = next_extent(ext);
2790                         continue;
2791                 }
2792
2793                 EASSERT(ergo(ext->oe_state == OES_CACHE,
2794                              ext->oe_hp || ext->oe_urgent), ext);
2795                 EASSERT(ergo(ext->oe_state == OES_ACTIVE,
2796                              !ext->oe_hp && ext->oe_urgent), ext);
2797
2798                 index = ext->oe_end + 1;
2799                 osc_extent_get(ext);
2800                 osc_object_unlock(obj);
2801
2802                 rc = osc_extent_wait(env, ext, OES_INV);
2803                 if (result == 0)
2804                         result = rc;
2805                 osc_extent_put(env, ext);
2806                 goto again;
2807         }
2808         osc_object_unlock(obj);
2809
2810         OSC_IO_DEBUG(obj, "sync file range.\n");
2811         RETURN(result);
2812 }
2813
2814 /**
2815  * Called to write out a range of osc object.
2816  *
2817  * @hp     : should be set this is caused by lock cancel;
2818  * @discard: is set if dirty pages should be dropped - file will be deleted or
2819  *         truncated, this implies there is no partially discarding extents.
2820  *
2821  * Return how many pages will be issued, or error code if error occurred.
2822  */
2823 int osc_cache_writeback_range(const struct lu_env *env, struct osc_object *obj,
2824                               pgoff_t start, pgoff_t end, int hp, int discard)
2825 {
2826         struct osc_extent *ext;
2827         CFS_LIST_HEAD(discard_list);
2828         bool unplug = false;
2829         int result = 0;
2830         ENTRY;
2831
2832         osc_object_lock(obj);
2833         ext = osc_extent_search(obj, start);
2834         if (ext == NULL)
2835                 ext = first_extent(obj);
2836         else if (ext->oe_end < start)
2837                 ext = next_extent(ext);
2838         while (ext != NULL) {
2839                 if (ext->oe_start > end)
2840                         break;
2841
2842                 ext->oe_fsync_wait = 1;
2843                 switch (ext->oe_state) {
2844                 case OES_CACHE:
2845                         result += ext->oe_nr_pages;
2846                         if (!discard) {
2847                                 cfs_list_t *list = NULL;
2848                                 if (hp) {
2849                                         EASSERT(!ext->oe_hp, ext);
2850                                         ext->oe_hp = 1;
2851                                         list = &obj->oo_hp_exts;
2852                                 } else if (!ext->oe_urgent) {
2853                                         ext->oe_urgent = 1;
2854                                         list = &obj->oo_urgent_exts;
2855                                 }
2856                                 if (list != NULL)
2857                                         cfs_list_move_tail(&ext->oe_link, list);
2858                                 unplug = true;
2859                         } else {
2860                                 /* the only discarder is lock cancelling, so
2861                                  * [start, end] must contain this extent */
2862                                 EASSERT(ext->oe_start >= start &&
2863                                         ext->oe_max_end <= end, ext);
2864                                 osc_extent_state_set(ext, OES_LOCKING);
2865                                 ext->oe_owner = cfs_current();
2866                                 cfs_list_move_tail(&ext->oe_link,
2867                                                    &discard_list);
2868                                 osc_update_pending(obj, OBD_BRW_WRITE,
2869                                                    -ext->oe_nr_pages);
2870                         }
2871                         break;
2872                 case OES_ACTIVE:
2873                         /* It's pretty bad to wait for ACTIVE extents, because
2874                          * we don't know how long we will wait for it to be
2875                          * flushed since it may be blocked at awaiting more
2876                          * grants. We do this for the correctness of fsync. */
2877                         LASSERT(hp == 0 && discard == 0);
2878                         ext->oe_urgent = 1;
2879                         break;
2880                 case OES_TRUNC:
2881                         /* this extent is being truncated, can't do anything
2882                          * for it now. it will be set to urgent after truncate
2883                          * is finished in osc_cache_truncate_end(). */
2884                 default:
2885                         break;
2886                 }
2887                 ext = next_extent(ext);
2888         }
2889         osc_object_unlock(obj);
2890
2891         LASSERT(ergo(!discard, cfs_list_empty(&discard_list)));
2892         if (!cfs_list_empty(&discard_list)) {
2893                 struct osc_extent *tmp;
2894                 int rc;
2895
2896                 osc_list_maint(osc_cli(obj), obj);
2897                 cfs_list_for_each_entry_safe(ext, tmp, &discard_list, oe_link) {
2898                         cfs_list_del_init(&ext->oe_link);
2899                         EASSERT(ext->oe_state == OES_LOCKING, ext);
2900
2901                         /* Discard caching pages. We don't actually write this
2902                          * extent out but we complete it as if we did. */
2903                         rc = osc_extent_make_ready(env, ext);
2904                         if (unlikely(rc < 0)) {
2905                                 OSC_EXTENT_DUMP(D_ERROR, ext,
2906                                                 "make_ready returned %d\n", rc);
2907                                 if (result >= 0)
2908                                         result = rc;
2909                         }
2910
2911                         /* finish the extent as if the pages were sent */
2912                         osc_extent_finish(env, ext, 0, 0);
2913                 }
2914         }
2915
2916         if (unplug)
2917                 osc_io_unplug(env, osc_cli(obj), obj, PDL_POLICY_ROUND);
2918
2919         if (hp || discard) {
2920                 int rc;
2921                 rc = osc_cache_wait_range(env, obj, start, end);
2922                 if (result >= 0 && rc < 0)
2923                         result = rc;
2924         }
2925
2926         OSC_IO_DEBUG(obj, "pageout [%lu, %lu], %d.\n", start, end, result);
2927         RETURN(result);
2928 }
2929
2930 /** @} osc */