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(struct list_head *list)
  96 {
  97         return 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                 atomic_read(&__ext->oe_refc),                           \
 116                 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                 waitqueue_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 (atomic_read(&ext->oe_refc) <= 0)
 188                 GOTO(out, rc = 20);
 189
 190         if (atomic_read(&ext->oe_refc) < 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 || !list_empty(&ext->oe_pages))
 196                         GOTO(out, rc = 35);
 197                 GOTO(out, rc = 0);
 198                 break;
 199         case OES_ACTIVE:
 200                 if (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 (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         list_for_each_entry(oap, &ext->oe_pages, oap_pending_item) {
 244                 pgoff_t index = osc_index(oap2osc(oap));
 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         wake_up_all(&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         atomic_set(&ext->oe_refc, 1);
 319         atomic_set(&ext->oe_users, 0);
 320         INIT_LIST_HEAD(&ext->oe_link);
 321         ext->oe_state = OES_INV;
 322         INIT_LIST_HEAD(&ext->oe_pages);
 323         init_waitqueue_head(&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(atomic_read(&ext->oe_refc) >= 0);
 337         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(atomic_read(&ext->oe_refc) > 0);
 344         if (atomic_dec_and_test(&ext->oe_refc)) {
 345                 LASSERT(list_empty(&ext->oe_link));
 346                 LASSERT(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(atomic_read(&ext->oe_refc) > 1);
 366         LASSERT(osc_object_is_locked(ext->oe_obj));
 367         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"\n", 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         atomic_inc(&ext->oe_users);
 461         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(list_empty(&ext->oe_pages));
 469         osc_extent_erase(ext);
 470         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         list_splice_init(&victim->oe_pages, &cur->oe_pages);
 525         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(atomic_read(&ext->oe_users) > 0);
 546         LASSERT(sanity_check(ext) == 0);
 547         LASSERT(ext->oe_grants > 0);
 548
 549         if (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                                 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"\n",
 643                  EXTPARA(cur));
 644
 645 restart:
 646         osc_object_lock(obj);
 647         ext = osc_extent_search(obj, cur->oe_start);
 648         if (ext == NULL)
 649                 ext = first_extent(obj);
 650         while (ext != NULL) {
 651                 loff_t ext_chk_start = ext->oe_start >> ppc_bits;
 652                 loff_t ext_chk_end   = ext->oe_end   >> ppc_bits;
 653
 654                 LASSERT(sanity_check_nolock(ext) == 0);
 655                 if (chunk > ext_chk_end + 1)
 656                         break;
 657
 658                 /* if covering by different locks, no chance to match */
 659                 if (lock != ext->oe_osclock) {
 660                         EASSERTF(!overlapped(ext, cur), ext,
 661                                  EXTSTR"\n", EXTPARA(cur));
 662
 663                         ext = next_extent(ext);
 664                         continue;
 665                 }
 666
 667                 /* discontiguous chunks? */
 668                 if (chunk + 1 < ext_chk_start) {
 669                         ext = next_extent(ext);
 670                         continue;
 671                 }
 672
 673                 /* ok, from now on, ext and cur have these attrs:
 674                  * 1. covered by the same lock
 675                  * 2. contiguous at chunk level or overlapping. */
 676
 677                 if (overlapped(ext, cur)) {
 678                         /* cur is the minimum unit, so overlapping means
 679                          * full contain. */
 680                         EASSERTF((ext->oe_start <= cur->oe_start &&
 681                                   ext->oe_end >= cur->oe_end),
 682                                  ext, EXTSTR"\n", EXTPARA(cur));
 683
 684                         if (ext->oe_state > OES_CACHE || ext->oe_fsync_wait) {
 685                                 /* for simplicity, we wait for this extent to
 686                                  * finish before going forward. */
 687                                 conflict = osc_extent_get(ext);
 688                                 break;
 689                         }
 690
 691                         found = osc_extent_hold(ext);
 692                         break;
 693                 }
 694
 695                 /* non-overlapped extent */
 696                 if (ext->oe_state != OES_CACHE || ext->oe_fsync_wait) {
 697                         /* we can't do anything for a non OES_CACHE extent, or
 698                          * if there is someone waiting for this extent to be
 699                          * flushed, try next one. */
 700                         ext = next_extent(ext);
 701                         continue;
 702                 }
 703
 704                 /* check if they belong to the same rpc slot before trying to
 705                  * merge. the extents are not overlapped and contiguous at
 706                  * chunk level to get here. */
 707                 if (ext->oe_max_end != max_end) {
 708                         /* if they don't belong to the same RPC slot or
 709                          * max_pages_per_rpc has ever changed, do not merge. */
 710                         ext = next_extent(ext);
 711                         continue;
 712                 }
 713
 714                 /* it's required that an extent must be contiguous at chunk
 715                  * level so that we know the whole extent is covered by grant
 716                  * (the pages in the extent are NOT required to be contiguous).
 717                  * Otherwise, it will be too much difficult to know which
 718                  * chunks have grants allocated. */
 719
 720                 /* try to do front merge - extend ext's start */
 721                 if (chunk + 1 == ext_chk_start) {
 722                         /* ext must be chunk size aligned */
 723                         EASSERT((ext->oe_start & ~chunk_mask) == 0, ext);
 724
 725                         /* pull ext's start back to cover cur */
 726                         ext->oe_start   = cur->oe_start;
 727                         ext->oe_grants += chunksize;
 728                         *grants -= chunksize;
 729
 730                         found = osc_extent_hold(ext);
 731                 } else if (chunk == ext_chk_end + 1) {
 732                         /* rear merge */
 733                         ext->oe_end     = cur->oe_end;
 734                         ext->oe_grants += chunksize;
 735                         *grants -= chunksize;
 736
 737                         /* try to merge with the next one because we just fill
 738                          * in a gap */
 739                         if (osc_extent_merge(env, ext, next_extent(ext)) == 0)
 740                                 /* we can save extent tax from next extent */
 741                                 *grants += cli->cl_extent_tax;
 742
 743                         found = osc_extent_hold(ext);
 744                 }
 745                 if (found != NULL)
 746                         break;
 747
 748                 ext = next_extent(ext);
 749         }
 750
 751         osc_extent_tree_dump(D_CACHE, obj);
 752         if (found != NULL) {
 753                 LASSERT(conflict == NULL);
 754                 if (!IS_ERR(found)) {
 755                         LASSERT(found->oe_osclock == cur->oe_osclock);
 756                         OSC_EXTENT_DUMP(D_CACHE, found,
 757                                         "found caching ext for %lu.\n", index);
 758                 }
 759         } else if (conflict == NULL) {
 760                 /* create a new extent */
 761                 EASSERT(osc_extent_is_overlapped(obj, cur) == 0, cur);
 762                 cur->oe_grants = chunksize + cli->cl_extent_tax;
 763                 *grants -= cur->oe_grants;
 764                 LASSERT(*grants >= 0);
 765
 766                 cur->oe_state = OES_CACHE;
 767                 found = osc_extent_hold(cur);
 768                 osc_extent_insert(obj, cur);
 769                 OSC_EXTENT_DUMP(D_CACHE, cur, "add into tree %lu/%lu.\n",
 770                                 index, lock->cll_descr.cld_end);
 771         }
 772         osc_object_unlock(obj);
 773
 774         if (conflict != NULL) {
 775                 LASSERT(found == NULL);
 776
 777                 /* waiting for IO to finish. Please notice that it's impossible
 778                  * to be an OES_TRUNC extent. */
 779                 rc = osc_extent_wait(env, conflict, OES_INV);
 780                 osc_extent_put(env, conflict);
 781                 conflict = NULL;
 782                 if (rc < 0)
 783                         GOTO(out, found = ERR_PTR(rc));
 784
 785                 goto restart;
 786         }
 787         EXIT;
 788
 789 out:
 790         osc_extent_put(env, cur);
 791         LASSERT(*grants >= 0);
 792         return found;
 793 }
 794
 795 /**
 796  * Called when IO is finished to an extent.
 797  */
 798 int osc_extent_finish(const struct lu_env *env, struct osc_extent *ext,
 799                       int sent, int rc)
 800 {
 801         struct client_obd *cli = osc_cli(ext->oe_obj);
 802         struct osc_async_page *oap;
 803         struct osc_async_page *tmp;
 804         int nr_pages = ext->oe_nr_pages;
 805         int lost_grant = 0;
 806         int blocksize = cli->cl_import->imp_obd->obd_osfs.os_bsize ? : 4096;
 807         __u64 last_off = 0;
 808         int last_count = -1;
 809         ENTRY;
 810
 811         OSC_EXTENT_DUMP(D_CACHE, ext, "extent finished.\n");
 812
 813         ext->oe_rc = rc ?: ext->oe_nr_pages;
 814         EASSERT(ergo(rc == 0, ext->oe_state == OES_RPC), ext);
 815
 816         osc_lru_add_batch(cli, &ext->oe_pages);
 817         list_for_each_entry_safe(oap, tmp, &ext->oe_pages,
 818                                      oap_pending_item) {
 819                 list_del_init(&oap->oap_rpc_item);
 820                 list_del_init(&oap->oap_pending_item);
 821                 if (last_off <= oap->oap_obj_off) {
 822                         last_off = oap->oap_obj_off;
 823                         last_count = oap->oap_count;
 824                 }
 825
 826                 --ext->oe_nr_pages;
 827                 osc_ap_completion(env, cli, oap, sent, rc);
 828         }
 829         EASSERT(ext->oe_nr_pages == 0, ext);
 830
 831         if (!sent) {
 832                 lost_grant = ext->oe_grants;
 833         } else if (blocksize < PAGE_CACHE_SIZE &&
 834                    last_count != PAGE_CACHE_SIZE) {
 835                 /* For short writes we shouldn't count parts of pages that
 836                  * span a whole chunk on the OST side, or our accounting goes
 837                  * wrong.  Should match the code in filter_grant_check. */
 838                 int offset = last_off & ~CFS_PAGE_MASK;
 839                 int count = last_count + (offset & (blocksize - 1));
 840                 int end = (offset + last_count) & (blocksize - 1);
 841                 if (end)
 842                         count += blocksize - end;
 843
 844                 lost_grant = PAGE_CACHE_SIZE - count;
 845         }
 846         if (ext->oe_grants > 0)
 847                 osc_free_grant(cli, nr_pages, lost_grant);
 848
 849         osc_extent_remove(ext);
 850         /* put the refcount for RPC */
 851         osc_extent_put(env, ext);
 852         RETURN(0);
 853 }
 854
 855 static int extent_wait_cb(struct osc_extent *ext, int state)
 856 {
 857         int ret;
 858
 859         osc_object_lock(ext->oe_obj);
 860         ret = ext->oe_state == state;
 861         osc_object_unlock(ext->oe_obj);
 862
 863         return ret;
 864 }
 865
 866 /**
 867  * Wait for the extent's state to become @state.
 868  */
 869 static int osc_extent_wait(const struct lu_env *env, struct osc_extent *ext,
 870                            int state)
 871 {
 872         struct osc_object *obj = ext->oe_obj;
 873         struct l_wait_info lwi = LWI_TIMEOUT_INTR(cfs_time_seconds(600), NULL,
 874                                                   LWI_ON_SIGNAL_NOOP, NULL);
 875         int rc = 0;
 876         ENTRY;
 877
 878         osc_object_lock(obj);
 879         LASSERT(sanity_check_nolock(ext) == 0);
 880         /* `Kick' this extent only if the caller is waiting for it to be
 881          * written out. */
 882         if (state == OES_INV && !ext->oe_urgent && !ext->oe_hp) {
 883                 if (ext->oe_state == OES_ACTIVE) {
 884                         ext->oe_urgent = 1;
 885                 } else if (ext->oe_state == OES_CACHE) {
 886                         ext->oe_urgent = 1;
 887                         osc_extent_hold(ext);
 888                         rc = 1;
 889                 }
 890         }
 891         osc_object_unlock(obj);
 892         if (rc == 1)
 893                 osc_extent_release(env, ext);
 894
 895         /* wait for the extent until its state becomes @state */
 896         rc = l_wait_event(ext->oe_waitq, extent_wait_cb(ext, state), &lwi);
 897         if (rc == -ETIMEDOUT) {
 898                 OSC_EXTENT_DUMP(D_ERROR, ext,
 899                         "%s: wait ext to %d timedout, recovery in progress?\n",
 900                         osc_export(obj)->exp_obd->obd_name, state);
 901
 902                 lwi = LWI_INTR(NULL, NULL);
 903                 rc = l_wait_event(ext->oe_waitq, extent_wait_cb(ext, state),
 904                                   &lwi);
 905         }
 906         if (rc == 0 && ext->oe_rc < 0)
 907                 rc = ext->oe_rc;
 908         RETURN(rc);
 909 }
 910
 911 /**
 912  * Discard pages with index greater than @size. If @ext is overlapped with
 913  * @size, then partial truncate happens.
 914  */
 915 static int osc_extent_truncate(struct osc_extent *ext, pgoff_t trunc_index,
 916                                 bool partial)
 917 {
 918         struct cl_env_nest     nest;
 919         struct lu_env         *env;
 920         struct cl_io          *io;
 921         struct osc_object     *obj = ext->oe_obj;
 922         struct client_obd     *cli = osc_cli(obj);
 923         struct osc_async_page *oap;
 924         struct osc_async_page *tmp;
 925         int                    pages_in_chunk = 0;
 926         int                    ppc_bits    = cli->cl_chunkbits -
 927                                              PAGE_CACHE_SHIFT;
 928         __u64                  trunc_chunk = trunc_index >> ppc_bits;
 929         int                    grants   = 0;
 930         int                    nr_pages = 0;
 931         int                    rc       = 0;
 932         ENTRY;
 933
 934         LASSERT(sanity_check(ext) == 0);
 935         LASSERT(ext->oe_state == OES_TRUNC);
 936         LASSERT(!ext->oe_urgent);
 937
 938         /* Request new lu_env.
 939          * We can't use that env from osc_cache_truncate_start() because
 940          * it's from lov_io_sub and not fully initialized. */
 941         env = cl_env_nested_get(&nest);
 942         io  = &osc_env_info(env)->oti_io;
 943         io->ci_obj = cl_object_top(osc2cl(obj));
 944         rc = cl_io_init(env, io, CIT_MISC, io->ci_obj);
 945         if (rc < 0)
 946                 GOTO(out, rc);
 947
 948         /* discard all pages with index greater then trunc_index */
 949         list_for_each_entry_safe(oap, tmp, &ext->oe_pages,
 950                                      oap_pending_item) {
 951                 pgoff_t index = osc_index(oap2osc(oap));
 952                 struct cl_page  *page = oap2cl_page(oap);
 953
 954                 LASSERT(list_empty(&oap->oap_rpc_item));
 955
 956                 /* only discard the pages with their index greater than
 957                  * trunc_index, and ... */
 958                 if (index < trunc_index ||
 959                     (index == trunc_index && partial)) {
 960                         /* accounting how many pages remaining in the chunk
 961                          * so that we can calculate grants correctly. */
 962                         if (index >> ppc_bits == trunc_chunk)
 963                                 ++pages_in_chunk;
 964                         continue;
 965                 }
 966
 967                 list_del_init(&oap->oap_pending_item);
 968
 969                 cl_page_get(page);
 970                 lu_ref_add(&page->cp_reference, "truncate", current);
 971
 972                 if (cl_page_own(env, io, page) == 0) {
 973                         cl_page_discard(env, io, page);
 974                         cl_page_disown(env, io, page);
 975                 } else {
 976                         LASSERT(page->cp_state == CPS_FREEING);
 977                         LASSERT(0);
 978                 }
 979
 980                 lu_ref_del(&page->cp_reference, "truncate", current);
 981                 cl_page_put(env, page);
 982
 983                 --ext->oe_nr_pages;
 984                 ++nr_pages;
 985         }
 986         EASSERTF(ergo(ext->oe_start >= trunc_index + !!partial,
 987                       ext->oe_nr_pages == 0),
 988                 ext, "trunc_index %lu, partial %d\n", trunc_index, partial);
 989
 990         osc_object_lock(obj);
 991         if (ext->oe_nr_pages == 0) {
 992                 LASSERT(pages_in_chunk == 0);
 993                 grants = ext->oe_grants;
 994                 ext->oe_grants = 0;
 995         } else { /* calculate how many grants we can free */
 996                 int     chunks = (ext->oe_end >> ppc_bits) - trunc_chunk;
 997                 pgoff_t last_index;
 998
 999
1000                 /* if there is no pages in this chunk, we can also free grants
1001                  * for the last chunk */
1002                 if (pages_in_chunk == 0) {
1003                         /* if this is the 1st chunk and no pages in this chunk,
1004                          * ext->oe_nr_pages must be zero, so we should be in
1005                          * the other if-clause. */
1006                         LASSERT(trunc_chunk > 0);
1007                         --trunc_chunk;
1008                         ++chunks;
1009                 }
1010
1011                 /* this is what we can free from this extent */
1012                 grants          = chunks << cli->cl_chunkbits;
1013                 ext->oe_grants -= grants;
1014                 last_index      = ((trunc_chunk + 1) << ppc_bits) - 1;
1015                 ext->oe_end     = min(last_index, ext->oe_max_end);
1016                 LASSERT(ext->oe_end >= ext->oe_start);
1017                 LASSERT(ext->oe_grants > 0);
1018         }
1019         osc_object_unlock(obj);
1020
1021         if (grants > 0 || nr_pages > 0)
1022                 osc_free_grant(cli, nr_pages, grants);
1023
1024 out:
1025         cl_io_fini(env, io);
1026         cl_env_nested_put(&nest, env);
1027         RETURN(rc);
1028 }
1029
1030 /**
1031  * This function is used to make the extent prepared for transfer.
1032  * A race with flusing page - ll_writepage() has to be handled cautiously.
1033  */
1034 static int osc_extent_make_ready(const struct lu_env *env,
1035                                  struct osc_extent *ext)
1036 {
1037         struct osc_async_page *oap;
1038         struct osc_async_page *last = NULL;
1039         struct osc_object *obj = ext->oe_obj;
1040         int page_count = 0;
1041         int rc;
1042         ENTRY;
1043
1044         /* we're going to grab page lock, so object lock must not be taken. */
1045         LASSERT(sanity_check(ext) == 0);
1046         /* in locking state, any process should not touch this extent. */
1047         EASSERT(ext->oe_state == OES_LOCKING, ext);
1048         EASSERT(ext->oe_owner != NULL, ext);
1049
1050         OSC_EXTENT_DUMP(D_CACHE, ext, "make ready\n");
1051
1052         list_for_each_entry(oap, &ext->oe_pages, oap_pending_item) {
1053                 ++page_count;
1054                 if (last == NULL || last->oap_obj_off < oap->oap_obj_off)
1055                         last = oap;
1056
1057                 /* checking ASYNC_READY is race safe */
1058                 if ((oap->oap_async_flags & ASYNC_READY) != 0)
1059                         continue;
1060
1061                 rc = osc_make_ready(env, oap, OBD_BRW_WRITE);
1062                 switch (rc) {
1063                 case 0:
1064                         spin_lock(&oap->oap_lock);
1065                         oap->oap_async_flags |= ASYNC_READY;
1066                         spin_unlock(&oap->oap_lock);
1067                         break;
1068                 case -EALREADY:
1069                         LASSERT((oap->oap_async_flags & ASYNC_READY) != 0);
1070                         break;
1071                 default:
1072                         LASSERTF(0, "unknown return code: %d\n", rc);
1073                 }
1074         }
1075
1076         LASSERT(page_count == ext->oe_nr_pages);
1077         LASSERT(last != NULL);
1078         /* the last page is the only one we need to refresh its count by
1079          * the size of file. */
1080         if (!(last->oap_async_flags & ASYNC_COUNT_STABLE)) {
1081                 last->oap_count = osc_refresh_count(env, last, OBD_BRW_WRITE);
1082                 LASSERT(last->oap_count > 0);
1083                 LASSERT(last->oap_page_off + last->oap_count <= PAGE_CACHE_SIZE);
1084                 spin_lock(&last->oap_lock);
1085                 last->oap_async_flags |= ASYNC_COUNT_STABLE;
1086                 spin_unlock(&last->oap_lock);
1087         }
1088
1089         /* for the rest of pages, we don't need to call osf_refresh_count()
1090          * because it's known they are not the last page */
1091         list_for_each_entry(oap, &ext->oe_pages, oap_pending_item) {
1092                 if (!(oap->oap_async_flags & ASYNC_COUNT_STABLE)) {
1093                         oap->oap_count = PAGE_CACHE_SIZE - oap->oap_page_off;
1094                         spin_lock(&oap->oap_lock);
1095                         oap->oap_async_flags |= ASYNC_COUNT_STABLE;
1096                         spin_unlock(&oap->oap_lock);
1097                 }
1098         }
1099
1100         osc_object_lock(obj);
1101         osc_extent_state_set(ext, OES_RPC);
1102         osc_object_unlock(obj);
1103         /* get a refcount for RPC. */
1104         osc_extent_get(ext);
1105
1106         RETURN(0);
1107 }
1108
1109 /**
1110  * Quick and simple version of osc_extent_find(). This function is frequently
1111  * called to expand the extent for the same IO. To expand the extent, the
1112  * page index must be in the same or next chunk of ext->oe_end.
1113  */
1114 static int osc_extent_expand(struct osc_extent *ext, pgoff_t index, int *grants)
1115 {
1116         struct osc_object *obj = ext->oe_obj;
1117         struct client_obd *cli = osc_cli(obj);
1118         struct osc_extent *next;
1119         int ppc_bits = cli->cl_chunkbits - PAGE_CACHE_SHIFT;
1120         pgoff_t chunk = index >> ppc_bits;
1121         pgoff_t end_chunk;
1122         pgoff_t end_index;
1123         int chunksize = 1 << cli->cl_chunkbits;
1124         int rc = 0;
1125         ENTRY;
1126
1127         LASSERT(ext->oe_max_end >= index && ext->oe_start <= index);
1128         osc_object_lock(obj);
1129         LASSERT(sanity_check_nolock(ext) == 0);
1130         end_chunk = ext->oe_end >> ppc_bits;
1131         if (chunk > end_chunk + 1)
1132                 GOTO(out, rc = -ERANGE);
1133
1134         if (end_chunk >= chunk)
1135                 GOTO(out, rc = 0);
1136
1137         LASSERT(end_chunk + 1 == chunk);
1138         /* try to expand this extent to cover @index */
1139         end_index = min(ext->oe_max_end, ((chunk + 1) << ppc_bits) - 1);
1140
1141         next = next_extent(ext);
1142         if (next != NULL && next->oe_start <= end_index)
1143                 /* complex mode - overlapped with the next extent,
1144                  * this case will be handled by osc_extent_find() */
1145                 GOTO(out, rc = -EAGAIN);
1146
1147         ext->oe_end = end_index;
1148         ext->oe_grants += chunksize;
1149         *grants -= chunksize;
1150         LASSERT(*grants >= 0);
1151         EASSERTF(osc_extent_is_overlapped(obj, ext) == 0, ext,
1152                  "overlapped after expanding for %lu.\n", index);
1153         EXIT;
1154
1155 out:
1156         osc_object_unlock(obj);
1157         RETURN(rc);
1158 }
1159
1160 static void osc_extent_tree_dump0(int level, struct osc_object *obj,
1161                                   const char *func, int line)
1162 {
1163         struct osc_extent *ext;
1164         int cnt;
1165
1166         CDEBUG(level, "Dump object %p extents at %s:%d, mppr: %u.\n",
1167                obj, func, line, osc_cli(obj)->cl_max_pages_per_rpc);
1168
1169         /* osc_object_lock(obj); */
1170         cnt = 1;
1171         for (ext = first_extent(obj); ext != NULL; ext = next_extent(ext))
1172                 OSC_EXTENT_DUMP(level, ext, "in tree %d.\n", cnt++);
1173
1174         cnt = 1;
1175         list_for_each_entry(ext, &obj->oo_hp_exts, oe_link)
1176                 OSC_EXTENT_DUMP(level, ext, "hp %d.\n", cnt++);
1177
1178         cnt = 1;
1179         list_for_each_entry(ext, &obj->oo_urgent_exts, oe_link)
1180                 OSC_EXTENT_DUMP(level, ext, "urgent %d.\n", cnt++);
1181
1182         cnt = 1;
1183         list_for_each_entry(ext, &obj->oo_reading_exts, oe_link)
1184                 OSC_EXTENT_DUMP(level, ext, "reading %d.\n", cnt++);
1185         /* osc_object_unlock(obj); */
1186 }
1187
1188 /* ------------------ osc extent end ------------------ */
1189
1190 static inline int osc_is_ready(struct osc_object *osc)
1191 {
1192         return !list_empty(&osc->oo_ready_item) ||
1193                !list_empty(&osc->oo_hp_ready_item);
1194 }
1195
1196 #define OSC_IO_DEBUG(OSC, STR, args...)                                        \
1197         CDEBUG(D_CACHE, "obj %p ready %d|%c|%c wr %d|%c|%c rd %d|%c " STR,     \
1198                (OSC), osc_is_ready(OSC),                                       \
1199                list_empty_marker(&(OSC)->oo_hp_ready_item),                    \
1200                list_empty_marker(&(OSC)->oo_ready_item),                       \
1201                atomic_read(&(OSC)->oo_nr_writes),                              \
1202                list_empty_marker(&(OSC)->oo_hp_exts),                          \
1203                list_empty_marker(&(OSC)->oo_urgent_exts),                      \
1204                atomic_read(&(OSC)->oo_nr_reads),                               \
1205                list_empty_marker(&(OSC)->oo_reading_exts),                     \
1206                ##args)
1207
1208 static int osc_make_ready(const struct lu_env *env, struct osc_async_page *oap,
1209                           int cmd)
1210 {
1211         struct osc_page *opg  = oap2osc_page(oap);
1212         struct cl_page  *page = oap2cl_page(oap);
1213         int result;
1214
1215         LASSERT(cmd == OBD_BRW_WRITE); /* no cached reads */
1216
1217         ENTRY;
1218         result = cl_page_make_ready(env, page, CRT_WRITE);
1219         if (result == 0)
1220                 opg->ops_submit_time = cfs_time_current();
1221         RETURN(result);
1222 }
1223
1224 static int osc_refresh_count(const struct lu_env *env,
1225                              struct osc_async_page *oap, int cmd)
1226 {
1227         struct osc_page  *opg = oap2osc_page(oap);
1228         pgoff_t index = osc_index(oap2osc(oap));
1229         struct cl_object *obj;
1230         struct cl_attr   *attr = &osc_env_info(env)->oti_attr;
1231
1232         int result;
1233         loff_t kms;
1234
1235         /* readpage queues with _COUNT_STABLE, shouldn't get here. */
1236         LASSERT(!(cmd & OBD_BRW_READ));
1237         LASSERT(opg != NULL);
1238         obj = opg->ops_cl.cpl_obj;
1239
1240         cl_object_attr_lock(obj);
1241         result = cl_object_attr_get(env, obj, attr);
1242         cl_object_attr_unlock(obj);
1243         if (result < 0)
1244                 return result;
1245         kms = attr->cat_kms;
1246         if (cl_offset(obj, index) >= kms)
1247                 /* catch race with truncate */
1248                 return 0;
1249         else if (cl_offset(obj, index + 1) > kms)
1250                 /* catch sub-page write at end of file */
1251                 return kms % PAGE_CACHE_SIZE;
1252         else
1253                 return PAGE_CACHE_SIZE;
1254 }
1255
1256 static int osc_completion(const struct lu_env *env, struct osc_async_page *oap,
1257                           int cmd, int rc)
1258 {
1259         struct osc_page   *opg  = oap2osc_page(oap);
1260         struct cl_page    *page = oap2cl_page(oap);
1261         struct osc_object *obj  = cl2osc(opg->ops_cl.cpl_obj);
1262         enum cl_req_type   crt;
1263         int srvlock;
1264
1265         ENTRY;
1266
1267         cmd &= ~OBD_BRW_NOQUOTA;
1268         LASSERTF(equi(page->cp_state == CPS_PAGEIN,  cmd == OBD_BRW_READ),
1269                  "cp_state:%u, cmd:%d\n", page->cp_state, cmd);
1270         LASSERTF(equi(page->cp_state == CPS_PAGEOUT, cmd == OBD_BRW_WRITE),
1271                 "cp_state:%u, cmd:%d\n", page->cp_state, cmd);
1272         LASSERT(opg->ops_transfer_pinned);
1273
1274         /*
1275          * page->cp_req can be NULL if io submission failed before
1276          * cl_req was allocated.
1277          */
1278         if (page->cp_req != NULL)
1279                 cl_req_page_done(env, page);
1280         LASSERT(page->cp_req == NULL);
1281
1282         crt = cmd == OBD_BRW_READ ? CRT_READ : CRT_WRITE;
1283         /* Clear opg->ops_transfer_pinned before VM lock is released. */
1284         opg->ops_transfer_pinned = 0;
1285
1286         spin_lock(&obj->oo_seatbelt);
1287         LASSERT(opg->ops_submitter != NULL);
1288         LASSERT(!list_empty(&opg->ops_inflight));
1289         list_del_init(&opg->ops_inflight);
1290         opg->ops_submitter = NULL;
1291         spin_unlock(&obj->oo_seatbelt);
1292
1293         opg->ops_submit_time = 0;
1294         srvlock = oap->oap_brw_flags & OBD_BRW_SRVLOCK;
1295
1296         /* statistic */
1297         if (rc == 0 && srvlock) {
1298                 struct lu_device *ld    = opg->ops_cl.cpl_obj->co_lu.lo_dev;
1299                 struct osc_stats *stats = &lu2osc_dev(ld)->od_stats;
1300                 int bytes = oap->oap_count;
1301
1302                 if (crt == CRT_READ)
1303                         stats->os_lockless_reads += bytes;
1304                 else
1305                         stats->os_lockless_writes += bytes;
1306         }
1307
1308         /*
1309          * This has to be the last operation with the page, as locks are
1310          * released in cl_page_completion() and nothing except for the
1311          * reference counter protects page from concurrent reclaim.
1312          */
1313         lu_ref_del(&page->cp_reference, "transfer", page);
1314
1315         cl_page_completion(env, page, crt, rc);
1316
1317         RETURN(0);
1318 }
1319
1320 #define OSC_DUMP_GRANT(lvl, cli, fmt, args...) do {                     \
1321         struct client_obd *__tmp = (cli);                               \
1322         CDEBUG(lvl, "%s: grant { dirty: %ld/%ld dirty_pages: %ld/%lu "  \
1323                "dropped: %ld avail: %ld, reserved: %ld, flight: %d }"   \
1324                "lru {in list: %ld, left: %ld, waiters: %d }" fmt,       \
1325                __tmp->cl_import->imp_obd->obd_name,                     \
1326                __tmp->cl_dirty_pages, __tmp->cl_dirty_max_pages,        \
1327                atomic_long_read(&obd_dirty_pages), obd_max_dirty_pages, \
1328                __tmp->cl_lost_grant, __tmp->cl_avail_grant,             \
1329                __tmp->cl_reserved_grant, __tmp->cl_w_in_flight,         \
1330                atomic_long_read(&__tmp->cl_lru_in_list),                \
1331                atomic_long_read(&__tmp->cl_lru_busy),                   \
1332                atomic_read(&__tmp->cl_lru_shrinkers), ##args);          \
1333 } while (0)
1334
1335 /* caller must hold loi_list_lock */
1336 static void osc_consume_write_grant(struct client_obd *cli,
1337                                     struct brw_page *pga)
1338 {
1339         assert_spin_locked(&cli->cl_loi_list_lock.lock);
1340         LASSERT(!(pga->flag & OBD_BRW_FROM_GRANT));
1341         atomic_long_inc(&obd_dirty_pages);
1342         cli->cl_dirty_pages++;
1343         pga->flag |= OBD_BRW_FROM_GRANT;
1344         CDEBUG(D_CACHE, "using %lu grant credits for brw %p page %p\n",
1345                PAGE_CACHE_SIZE, pga, pga->pg);
1346         osc_update_next_shrink(cli);
1347 }
1348
1349 /* the companion to osc_consume_write_grant, called when a brw has completed.
1350  * must be called with the loi lock held. */
1351 static void osc_release_write_grant(struct client_obd *cli,
1352                                     struct brw_page *pga)
1353 {
1354         ENTRY;
1355
1356         assert_spin_locked(&cli->cl_loi_list_lock.lock);
1357         if (!(pga->flag & OBD_BRW_FROM_GRANT)) {
1358                 EXIT;
1359                 return;
1360         }
1361
1362         pga->flag &= ~OBD_BRW_FROM_GRANT;
1363         atomic_long_dec(&obd_dirty_pages);
1364         cli->cl_dirty_pages--;
1365         if (pga->flag & OBD_BRW_NOCACHE) {
1366                 pga->flag &= ~OBD_BRW_NOCACHE;
1367                 atomic_long_dec(&obd_dirty_transit_pages);
1368                 cli->cl_dirty_transit--;
1369         }
1370         EXIT;
1371 }
1372
1373 /**
1374  * To avoid sleeping with object lock held, it's good for us allocate enough
1375  * grants before entering into critical section.
1376  *
1377  * client_obd_list_lock held by caller
1378  */
1379 static int osc_reserve_grant(struct client_obd *cli, unsigned int bytes)
1380 {
1381         int rc = -EDQUOT;
1382
1383         if (cli->cl_avail_grant >= bytes) {
1384                 cli->cl_avail_grant    -= bytes;
1385                 cli->cl_reserved_grant += bytes;
1386                 rc = 0;
1387         }
1388         return rc;
1389 }
1390
1391 static void __osc_unreserve_grant(struct client_obd *cli,
1392                                   unsigned int reserved, unsigned int unused)
1393 {
1394         /* it's quite normal for us to get more grant than reserved.
1395          * Thinking about a case that two extents merged by adding a new
1396          * chunk, we can save one extent tax. If extent tax is greater than
1397          * one chunk, we can save more grant by adding a new chunk */
1398         cli->cl_reserved_grant -= reserved;
1399         if (unused > reserved) {
1400                 cli->cl_avail_grant += reserved;
1401                 cli->cl_lost_grant  += unused - reserved;
1402         } else {
1403                 cli->cl_avail_grant += unused;
1404         }
1405 }
1406
1407 void osc_unreserve_grant(struct client_obd *cli,
1408                          unsigned int reserved, unsigned int unused)
1409 {
1410         client_obd_list_lock(&cli->cl_loi_list_lock);
1411         __osc_unreserve_grant(cli, reserved, unused);
1412         if (unused > 0)
1413                 osc_wake_cache_waiters(cli);
1414         client_obd_list_unlock(&cli->cl_loi_list_lock);
1415 }
1416
1417 /**
1418  * Free grant after IO is finished or canceled.
1419  *
1420  * @lost_grant is used to remember how many grants we have allocated but not
1421  * used, we should return these grants to OST. There're two cases where grants
1422  * can be lost:
1423  * 1. truncate;
1424  * 2. blocksize at OST is less than PAGE_CACHE_SIZE and a partial page was
1425  *    written. In this case OST may use less chunks to serve this partial
1426  *    write. OSTs don't actually know the page size on the client side. so
1427  *    clients have to calculate lost grant by the blocksize on the OST.
1428  *    See filter_grant_check() for details.
1429  */
1430 static void osc_free_grant(struct client_obd *cli, unsigned int nr_pages,
1431                            unsigned int lost_grant)
1432 {
1433         int grant = (1 << cli->cl_chunkbits) + cli->cl_extent_tax;
1434
1435         client_obd_list_lock(&cli->cl_loi_list_lock);
1436         atomic_long_sub(nr_pages, &obd_dirty_pages);
1437         cli->cl_dirty_pages -= nr_pages;
1438         cli->cl_lost_grant += lost_grant;
1439         if (cli->cl_avail_grant < grant && cli->cl_lost_grant >= grant) {
1440                 /* borrow some grant from truncate to avoid the case that
1441                  * truncate uses up all avail grant */
1442                 cli->cl_lost_grant -= grant;
1443                 cli->cl_avail_grant += grant;
1444         }
1445         osc_wake_cache_waiters(cli);
1446         client_obd_list_unlock(&cli->cl_loi_list_lock);
1447         CDEBUG(D_CACHE, "lost %u grant: %lu avail: %lu dirty: %lu\n",
1448                lost_grant, cli->cl_lost_grant,
1449                cli->cl_avail_grant, cli->cl_dirty_pages << PAGE_CACHE_SHIFT);
1450 }
1451
1452 /**
1453  * The companion to osc_enter_cache(), called when @oap is no longer part of
1454  * the dirty accounting due to error.
1455  */
1456 static void osc_exit_cache(struct client_obd *cli, struct osc_async_page *oap)
1457 {
1458         client_obd_list_lock(&cli->cl_loi_list_lock);
1459         osc_release_write_grant(cli, &oap->oap_brw_page);
1460         client_obd_list_unlock(&cli->cl_loi_list_lock);
1461 }
1462
1463 /**
1464  * Non-blocking version of osc_enter_cache() that consumes grant only when it
1465  * is available.
1466  */
1467 static int osc_enter_cache_try(struct client_obd *cli,
1468                                struct osc_async_page *oap,
1469                                int bytes, int transient)
1470 {
1471         int rc;
1472
1473         OSC_DUMP_GRANT(D_CACHE, cli, "need:%d.\n", bytes);
1474
1475         rc = osc_reserve_grant(cli, bytes);
1476         if (rc < 0)
1477                 return 0;
1478
1479         if (cli->cl_dirty_pages < cli->cl_dirty_max_pages &&
1480             1 + atomic_long_read(&obd_dirty_pages) <= obd_max_dirty_pages) {
1481                 osc_consume_write_grant(cli, &oap->oap_brw_page);
1482                 if (transient) {
1483                         cli->cl_dirty_transit++;
1484                         atomic_long_inc(&obd_dirty_transit_pages);
1485                         oap->oap_brw_flags |= OBD_BRW_NOCACHE;
1486                 }
1487                 rc = 1;
1488         } else {
1489                 __osc_unreserve_grant(cli, bytes, bytes);
1490                 rc = 0;
1491         }
1492         return rc;
1493 }
1494
1495 static int ocw_granted(struct client_obd *cli, struct osc_cache_waiter *ocw)
1496 {
1497         int rc;
1498         client_obd_list_lock(&cli->cl_loi_list_lock);
1499         rc = list_empty(&ocw->ocw_entry);
1500         client_obd_list_unlock(&cli->cl_loi_list_lock);
1501         return rc;
1502 }
1503
1504 /**
1505  * The main entry to reserve dirty page accounting. Usually the grant reserved
1506  * in this function will be freed in bulk in osc_free_grant() unless it fails
1507  * to add osc cache, in that case, it will be freed in osc_exit_cache().
1508  *
1509  * The process will be put into sleep if it's already run out of grant.
1510  */
1511 static int osc_enter_cache(const struct lu_env *env, struct client_obd *cli,
1512                            struct osc_async_page *oap, int bytes)
1513 {
1514         struct osc_object *osc = oap->oap_obj;
1515         struct lov_oinfo  *loi = osc->oo_oinfo;
1516         struct osc_cache_waiter ocw;
1517         struct l_wait_info lwi = LWI_TIMEOUT_INTR(cfs_time_seconds(600), NULL,
1518                                                   LWI_ON_SIGNAL_NOOP, NULL);
1519         int rc = -EDQUOT;
1520         ENTRY;
1521
1522         OSC_DUMP_GRANT(D_CACHE, cli, "need:%d.\n", bytes);
1523
1524         client_obd_list_lock(&cli->cl_loi_list_lock);
1525
1526         /* force the caller to try sync io.  this can jump the list
1527          * of queued writes and create a discontiguous rpc stream */
1528         if (OBD_FAIL_CHECK(OBD_FAIL_OSC_NO_GRANT) ||
1529             cli->cl_dirty_max_pages == 0 ||
1530             cli->cl_ar.ar_force_sync || loi->loi_ar.ar_force_sync)
1531                 GOTO(out, rc = -EDQUOT);
1532
1533         /* Hopefully normal case - cache space and write credits available */
1534         if (osc_enter_cache_try(cli, oap, bytes, 0))
1535                 GOTO(out, rc = 0);
1536
1537         /* We can get here for two reasons: too many dirty pages in cache, or
1538          * run out of grants. In both cases we should write dirty pages out.
1539          * Adding a cache waiter will trigger urgent write-out no matter what
1540          * RPC size will be.
1541          * The exiting condition is no avail grants and no dirty pages caching,
1542          * that really means there is no space on the OST. */
1543         init_waitqueue_head(&ocw.ocw_waitq);
1544         ocw.ocw_oap   = oap;
1545         ocw.ocw_grant = bytes;
1546         while (cli->cl_dirty_pages > 0 || cli->cl_w_in_flight > 0) {
1547                 list_add_tail(&ocw.ocw_entry, &cli->cl_cache_waiters);
1548                 ocw.ocw_rc = 0;
1549                 client_obd_list_unlock(&cli->cl_loi_list_lock);
1550
1551                 osc_io_unplug_async(env, cli, NULL);
1552
1553                 CDEBUG(D_CACHE, "%s: sleeping for cache space @ %p for %p\n",
1554                        cli->cl_import->imp_obd->obd_name, &ocw, oap);
1555
1556                 rc = l_wait_event(ocw.ocw_waitq, ocw_granted(cli, &ocw), &lwi);
1557
1558                 client_obd_list_lock(&cli->cl_loi_list_lock);
1559
1560                 /* l_wait_event is interrupted by signal, or timed out */
1561                 if (rc < 0) {
1562                         switch (rc) {
1563                         case -ETIMEDOUT:
1564                                 OSC_DUMP_GRANT(D_ERROR, cli,
1565                                                 "try to reserve %d.\n", bytes);
1566                                 osc_extent_tree_dump(D_ERROR, osc);
1567                                 rc = -EDQUOT;
1568                                 break;
1569                         case -EINTR:
1570                                 /* Ensures restartability - LU-3581 */
1571                                 rc = -ERESTARTSYS;
1572                                 break;
1573                         default:
1574                                 CDEBUG(D_CACHE, "%s: event for cache space @"
1575                                        " %p never arrived due to %d\n",
1576                                        cli->cl_import->imp_obd->obd_name,
1577                                        &ocw, rc);
1578                                 break;
1579                         }
1580                         list_del_init(&ocw.ocw_entry);
1581                         GOTO(out, rc);
1582                 }
1583
1584                 LASSERT(list_empty(&ocw.ocw_entry));
1585                 rc = ocw.ocw_rc;
1586
1587                 if (rc != -EDQUOT)
1588                         GOTO(out, rc);
1589                 if (osc_enter_cache_try(cli, oap, bytes, 0))
1590                         GOTO(out, rc = 0);
1591         }
1592         EXIT;
1593 out:
1594         client_obd_list_unlock(&cli->cl_loi_list_lock);
1595         OSC_DUMP_GRANT(D_CACHE, cli, "returned %d.\n", rc);
1596         RETURN(rc);
1597 }
1598
1599 /* caller must hold loi_list_lock */
1600 void osc_wake_cache_waiters(struct client_obd *cli)
1601 {
1602         struct list_head *l, *tmp;
1603         struct osc_cache_waiter *ocw;
1604
1605         ENTRY;
1606         list_for_each_safe(l, tmp, &cli->cl_cache_waiters) {
1607                 ocw = list_entry(l, struct osc_cache_waiter, ocw_entry);
1608                 list_del_init(&ocw->ocw_entry);
1609
1610                 ocw->ocw_rc = -EDQUOT;
1611                 /* we can't dirty more */
1612                 if ((cli->cl_dirty_pages  >= cli->cl_dirty_max_pages) ||
1613                     (1 + atomic_long_read(&obd_dirty_pages) >
1614                      obd_max_dirty_pages)) {
1615                         CDEBUG(D_CACHE, "no dirty room: dirty: %ld "
1616                                "osc max %ld, sys max %ld\n",
1617                                cli->cl_dirty_pages, cli->cl_dirty_max_pages,
1618                                obd_max_dirty_pages);
1619                         goto wakeup;
1620                 }
1621
1622                 ocw->ocw_rc = 0;
1623                 if (!osc_enter_cache_try(cli, ocw->ocw_oap, ocw->ocw_grant, 0))
1624                         ocw->ocw_rc = -EDQUOT;
1625
1626 wakeup:
1627                 CDEBUG(D_CACHE, "wake up %p for oap %p, avail grant %ld, %d\n",
1628                        ocw, ocw->ocw_oap, cli->cl_avail_grant, ocw->ocw_rc);
1629
1630                 wake_up(&ocw->ocw_waitq);
1631         }
1632
1633         EXIT;
1634 }
1635
1636 static int osc_max_rpc_in_flight(struct client_obd *cli, struct osc_object *osc)
1637 {
1638         int hprpc = !!list_empty(&osc->oo_hp_exts);
1639         return rpcs_in_flight(cli) >= cli->cl_max_rpcs_in_flight + hprpc;
1640 }
1641
1642 /* This maintains the lists of pending pages to read/write for a given object
1643  * (lop).  This is used by osc_check_rpcs->osc_next_obj() and osc_list_maint()
1644  * to quickly find objects that are ready to send an RPC. */
1645 static int osc_makes_rpc(struct client_obd *cli, struct osc_object *osc,
1646                          int cmd)
1647 {
1648         int invalid_import = 0;
1649         ENTRY;
1650
1651         /* if we have an invalid import we want to drain the queued pages
1652          * by forcing them through rpcs that immediately fail and complete
1653          * the pages.  recovery relies on this to empty the queued pages
1654          * before canceling the locks and evicting down the llite pages */
1655         if ((cli->cl_import == NULL || cli->cl_import->imp_invalid))
1656                 invalid_import = 1;
1657
1658         if (cmd & OBD_BRW_WRITE) {
1659                 if (atomic_read(&osc->oo_nr_writes) == 0)
1660                         RETURN(0);
1661                 if (invalid_import) {
1662                         CDEBUG(D_CACHE, "invalid import forcing RPC\n");
1663                         RETURN(1);
1664                 }
1665                 if (!list_empty(&osc->oo_hp_exts)) {
1666                         CDEBUG(D_CACHE, "high prio request forcing RPC\n");
1667                         RETURN(1);
1668                 }
1669                 if (!list_empty(&osc->oo_urgent_exts)) {
1670                         CDEBUG(D_CACHE, "urgent request forcing RPC\n");
1671                         RETURN(1);
1672                 }
1673                 /* trigger a write rpc stream as long as there are dirtiers
1674                  * waiting for space.  as they're waiting, they're not going to
1675                  * create more pages to coalesce with what's waiting.. */
1676                 if (!list_empty(&cli->cl_cache_waiters)) {
1677                         CDEBUG(D_CACHE, "cache waiters forcing RPC\n");
1678                         RETURN(1);
1679                 }
1680                 if (atomic_read(&osc->oo_nr_writes) >=
1681                     cli->cl_max_pages_per_rpc)
1682                         RETURN(1);
1683         } else {
1684                 if (atomic_read(&osc->oo_nr_reads) == 0)
1685                         RETURN(0);
1686                 if (invalid_import) {
1687                         CDEBUG(D_CACHE, "invalid import forcing RPC\n");
1688                         RETURN(1);
1689                 }
1690                 /* all read are urgent. */
1691                 if (!list_empty(&osc->oo_reading_exts))
1692                         RETURN(1);
1693         }
1694
1695         RETURN(0);
1696 }
1697
1698 static void osc_update_pending(struct osc_object *obj, int cmd, int delta)
1699 {
1700         struct client_obd *cli = osc_cli(obj);
1701         if (cmd & OBD_BRW_WRITE) {
1702                 atomic_add(delta, &obj->oo_nr_writes);
1703                 atomic_add(delta, &cli->cl_pending_w_pages);
1704                 LASSERT(atomic_read(&obj->oo_nr_writes) >= 0);
1705         } else {
1706                 atomic_add(delta, &obj->oo_nr_reads);
1707                 atomic_add(delta, &cli->cl_pending_r_pages);
1708                 LASSERT(atomic_read(&obj->oo_nr_reads) >= 0);
1709         }
1710         OSC_IO_DEBUG(obj, "update pending cmd %d delta %d.\n", cmd, delta);
1711 }
1712
1713 static int osc_makes_hprpc(struct osc_object *obj)
1714 {
1715         return !list_empty(&obj->oo_hp_exts);
1716 }
1717
1718 static void on_list(struct list_head *item, struct list_head *list,
1719                     int should_be_on)
1720 {
1721         if (list_empty(item) && should_be_on)
1722                 list_add_tail(item, list);
1723         else if (!list_empty(item) && !should_be_on)
1724                 list_del_init(item);
1725 }
1726
1727 /* maintain the osc's cli list membership invariants so that osc_send_oap_rpc
1728  * can find pages to build into rpcs quickly */
1729 static int __osc_list_maint(struct client_obd *cli, struct osc_object *osc)
1730 {
1731         if (osc_makes_hprpc(osc)) {
1732                 /* HP rpc */
1733                 on_list(&osc->oo_ready_item, &cli->cl_loi_ready_list, 0);
1734                 on_list(&osc->oo_hp_ready_item, &cli->cl_loi_hp_ready_list, 1);
1735         } else {
1736                 on_list(&osc->oo_hp_ready_item, &cli->cl_loi_hp_ready_list, 0);
1737                 on_list(&osc->oo_ready_item, &cli->cl_loi_ready_list,
1738                         osc_makes_rpc(cli, osc, OBD_BRW_WRITE) ||
1739                         osc_makes_rpc(cli, osc, OBD_BRW_READ));
1740         }
1741
1742         on_list(&osc->oo_write_item, &cli->cl_loi_write_list,
1743                 atomic_read(&osc->oo_nr_writes) > 0);
1744
1745         on_list(&osc->oo_read_item, &cli->cl_loi_read_list,
1746                 atomic_read(&osc->oo_nr_reads) > 0);
1747
1748         return osc_is_ready(osc);
1749 }
1750
1751 static int osc_list_maint(struct client_obd *cli, struct osc_object *osc)
1752 {
1753         int is_ready;
1754
1755         client_obd_list_lock(&cli->cl_loi_list_lock);
1756         is_ready = __osc_list_maint(cli, osc);
1757         client_obd_list_unlock(&cli->cl_loi_list_lock);
1758
1759         return is_ready;
1760 }
1761
1762 /* this is trying to propogate async writeback errors back up to the
1763  * application.  As an async write fails we record the error code for later if
1764  * the app does an fsync.  As long as errors persist we force future rpcs to be
1765  * sync so that the app can get a sync error and break the cycle of queueing
1766  * pages for which writeback will fail. */
1767 static void osc_process_ar(struct osc_async_rc *ar, __u64 xid,
1768                            int rc)
1769 {
1770         if (rc) {
1771                 if (!ar->ar_rc)
1772                         ar->ar_rc = rc;
1773
1774                 ar->ar_force_sync = 1;
1775                 ar->ar_min_xid = ptlrpc_sample_next_xid();
1776                 return;
1777
1778         }
1779
1780         if (ar->ar_force_sync && (xid >= ar->ar_min_xid))
1781                 ar->ar_force_sync = 0;
1782 }
1783
1784 /* this must be called holding the loi list lock to give coverage to exit_cache,
1785  * async_flag maintenance, and oap_request */
1786 static void osc_ap_completion(const struct lu_env *env, struct client_obd *cli,
1787                               struct osc_async_page *oap, int sent, int rc)
1788 {
1789         struct osc_object *osc = oap->oap_obj;
1790         struct lov_oinfo  *loi = osc->oo_oinfo;
1791         __u64 xid = 0;
1792
1793         ENTRY;
1794         if (oap->oap_request != NULL) {
1795                 xid = ptlrpc_req_xid(oap->oap_request);
1796                 ptlrpc_req_finished(oap->oap_request);
1797                 oap->oap_request = NULL;
1798         }
1799
1800         /* As the transfer for this page is being done, clear the flags */
1801         spin_lock(&oap->oap_lock);
1802         oap->oap_async_flags = 0;
1803         spin_unlock(&oap->oap_lock);
1804         oap->oap_interrupted = 0;
1805
1806         if (oap->oap_cmd & OBD_BRW_WRITE && xid > 0) {
1807                 client_obd_list_lock(&cli->cl_loi_list_lock);
1808                 osc_process_ar(&cli->cl_ar, xid, rc);
1809                 osc_process_ar(&loi->loi_ar, xid, rc);
1810                 client_obd_list_unlock(&cli->cl_loi_list_lock);
1811         }
1812
1813         rc = osc_completion(env, oap, oap->oap_cmd, rc);
1814         if (rc)
1815                 CERROR("completion on oap %p obj %p returns %d.\n",
1816                        oap, osc, rc);
1817
1818         EXIT;
1819 }
1820
1821 /**
1822  * Try to add extent to one RPC. We need to think about the following things:
1823  * - # of pages must not be over max_pages_per_rpc
1824  * - extent must be compatible with previous ones
1825  */
1826 static int try_to_add_extent_for_io(struct client_obd *cli,
1827                                     struct osc_extent *ext,
1828                                     struct list_head *rpclist,
1829                                     int *pc, unsigned int *max_pages)
1830 {
1831         struct osc_extent *tmp;
1832         struct osc_async_page *oap = list_first_entry(&ext->oe_pages,
1833                                                       struct osc_async_page,
1834                                                       oap_pending_item);
1835         ENTRY;
1836
1837         EASSERT((ext->oe_state == OES_CACHE || ext->oe_state == OES_LOCK_DONE),
1838                 ext);
1839
1840         *max_pages = max(ext->oe_mppr, *max_pages);
1841         if (*pc + ext->oe_nr_pages > *max_pages)
1842                 RETURN(0);
1843
1844         list_for_each_entry(tmp, rpclist, oe_link) {
1845                 struct osc_async_page *oap2;
1846                 oap2 = list_first_entry(&tmp->oe_pages, struct osc_async_page,
1847                                         oap_pending_item);
1848                 EASSERT(tmp->oe_owner == current, tmp);
1849 #if 0
1850                 if (overlapped(tmp, ext)) {
1851                         OSC_EXTENT_DUMP(D_ERROR, tmp, "overlapped %p.\n", ext);
1852                         EASSERT(0, ext);
1853                 }
1854 #endif
1855                 if (oap2cl_page(oap)->cp_type != oap2cl_page(oap2)->cp_type) {
1856                         CDEBUG(D_CACHE, "Do not permit different type of IO"
1857                                         " for a same RPC\n");
1858                         RETURN(0);
1859                 }
1860
1861                 if (tmp->oe_srvlock != ext->oe_srvlock ||
1862                     !tmp->oe_grants != !ext->oe_grants)
1863                         RETURN(0);
1864
1865                 /* remove break for strict check */
1866                 break;
1867         }
1868
1869         *pc += ext->oe_nr_pages;
1870         list_move_tail(&ext->oe_link, rpclist);
1871         ext->oe_owner = current;
1872         RETURN(1);
1873 }
1874
1875 /**
1876  * In order to prevent multiple ptlrpcd from breaking contiguous extents,
1877  * get_write_extent() takes all appropriate extents in atomic.
1878  *
1879  * The following policy is used to collect extents for IO:
1880  * 1. Add as many HP extents as possible;
1881  * 2. Add the first urgent extent in urgent extent list and take it out of
1882  *    urgent list;
1883  * 3. Add subsequent extents of this urgent extent;
1884  * 4. If urgent list is not empty, goto 2;
1885  * 5. Traverse the extent tree from the 1st extent;
1886  * 6. Above steps exit if there is no space in this RPC.
1887  */
1888 static int get_write_extents(struct osc_object *obj, struct list_head *rpclist)
1889 {
1890         struct client_obd *cli = osc_cli(obj);
1891         struct osc_extent *ext;
1892         int page_count = 0;
1893         unsigned int max_pages = cli->cl_max_pages_per_rpc;
1894
1895         LASSERT(osc_object_is_locked(obj));
1896         while (!list_empty(&obj->oo_hp_exts)) {
1897                 ext = list_entry(obj->oo_hp_exts.next, struct osc_extent,
1898                                  oe_link);
1899                 LASSERT(ext->oe_state == OES_CACHE);
1900                 if (!try_to_add_extent_for_io(cli, ext, rpclist, &page_count,
1901                                               &max_pages))
1902                         return page_count;
1903                 EASSERT(ext->oe_nr_pages <= max_pages, ext);
1904         }
1905         if (page_count == max_pages)
1906                 return page_count;
1907
1908         while (!list_empty(&obj->oo_urgent_exts)) {
1909                 ext = list_entry(obj->oo_urgent_exts.next,
1910                                  struct osc_extent, oe_link);
1911                 if (!try_to_add_extent_for_io(cli, ext, rpclist, &page_count,
1912                                               &max_pages))
1913                         return page_count;
1914
1915                 if (!ext->oe_intree)
1916                         continue;
1917
1918                 while ((ext = next_extent(ext)) != NULL) {
1919                         if ((ext->oe_state != OES_CACHE) ||
1920                             (!list_empty(&ext->oe_link) &&
1921                              ext->oe_owner != NULL))
1922                                 continue;
1923
1924                         if (!try_to_add_extent_for_io(cli, ext, rpclist,
1925                                                       &page_count, &max_pages))
1926                                 return page_count;
1927                 }
1928         }
1929         if (page_count == max_pages)
1930                 return page_count;
1931
1932         ext = first_extent(obj);
1933         while (ext != NULL) {
1934                 if ((ext->oe_state != OES_CACHE) ||
1935                     /* this extent may be already in current rpclist */
1936                     (!list_empty(&ext->oe_link) && ext->oe_owner != NULL)) {
1937                         ext = next_extent(ext);
1938                         continue;
1939                 }
1940
1941                 if (!try_to_add_extent_for_io(cli, ext, rpclist, &page_count,
1942                                               &max_pages))
1943                         return page_count;
1944
1945                 ext = next_extent(ext);
1946         }
1947         return page_count;
1948 }
1949
1950 static int
1951 osc_send_write_rpc(const struct lu_env *env, struct client_obd *cli,
1952                    struct osc_object *osc, pdl_policy_t pol)
1953 __must_hold(osc)
1954 {
1955         struct list_head   rpclist = LIST_HEAD_INIT(rpclist);
1956         struct osc_extent *ext;
1957         struct osc_extent *tmp;
1958         struct osc_extent *first = NULL;
1959         obd_count page_count = 0;
1960         int srvlock = 0;
1961         int rc = 0;
1962         ENTRY;
1963
1964         LASSERT(osc_object_is_locked(osc));
1965
1966         page_count = get_write_extents(osc, &rpclist);
1967         LASSERT(equi(page_count == 0, list_empty(&rpclist)));
1968
1969         if (list_empty(&rpclist))
1970                 RETURN(0);
1971
1972         osc_update_pending(osc, OBD_BRW_WRITE, -page_count);
1973
1974         list_for_each_entry(ext, &rpclist, oe_link) {
1975                 LASSERT(ext->oe_state == OES_CACHE ||
1976                         ext->oe_state == OES_LOCK_DONE);
1977                 if (ext->oe_state == OES_CACHE)
1978                         osc_extent_state_set(ext, OES_LOCKING);
1979                 else
1980                         osc_extent_state_set(ext, OES_RPC);
1981         }
1982
1983         /* we're going to grab page lock, so release object lock because
1984          * lock order is page lock -> object lock. */
1985         osc_object_unlock(osc);
1986
1987         list_for_each_entry_safe(ext, tmp, &rpclist, oe_link) {
1988                 if (ext->oe_state == OES_LOCKING) {
1989                         rc = osc_extent_make_ready(env, ext);
1990                         if (unlikely(rc < 0)) {
1991                                 list_del_init(&ext->oe_link);
1992                                 osc_extent_finish(env, ext, 0, rc);
1993                                 continue;
1994                         }
1995                 }
1996                 if (first == NULL) {
1997                         first = ext;
1998                         srvlock = ext->oe_srvlock;
1999                 } else {
2000                         LASSERT(srvlock == ext->oe_srvlock);
2001                 }
2002         }
2003
2004         if (!list_empty(&rpclist)) {
2005                 LASSERT(page_count > 0);
2006                 rc = osc_build_rpc(env, cli, &rpclist, OBD_BRW_WRITE, pol);
2007                 LASSERT(list_empty(&rpclist));
2008         }
2009
2010         osc_object_lock(osc);
2011         RETURN(rc);
2012 }
2013
2014 /**
2015  * prepare pages for ASYNC io and put pages in send queue.
2016  *
2017  * \param cmd OBD_BRW_* macroses
2018  * \param lop pending pages
2019  *
2020  * \return zero if no page added to send queue.
2021  * \return 1 if pages successfully added to send queue.
2022  * \return negative on errors.
2023  */
2024 static int
2025 osc_send_read_rpc(const struct lu_env *env, struct client_obd *cli,
2026                   struct osc_object *osc, pdl_policy_t pol)
2027 __must_hold(osc)
2028 {
2029         struct osc_extent *ext;
2030         struct osc_extent *next;
2031         struct list_head rpclist = LIST_HEAD_INIT(rpclist);
2032         int page_count = 0;
2033         unsigned int max_pages = cli->cl_max_pages_per_rpc;
2034         int rc = 0;
2035         ENTRY;
2036
2037         LASSERT(osc_object_is_locked(osc));
2038         list_for_each_entry_safe(ext, next,
2039                                      &osc->oo_reading_exts, oe_link) {
2040                 EASSERT(ext->oe_state == OES_LOCK_DONE, ext);
2041                 if (!try_to_add_extent_for_io(cli, ext, &rpclist, &page_count,
2042                                               &max_pages))
2043                         break;
2044                 osc_extent_state_set(ext, OES_RPC);
2045                 EASSERT(ext->oe_nr_pages <= max_pages, ext);
2046         }
2047         LASSERT(page_count <= max_pages);
2048
2049         osc_update_pending(osc, OBD_BRW_READ, -page_count);
2050
2051         if (!list_empty(&rpclist)) {
2052                 osc_object_unlock(osc);
2053
2054                 LASSERT(page_count > 0);
2055                 rc = osc_build_rpc(env, cli, &rpclist, OBD_BRW_READ, pol);
2056                 LASSERT(list_empty(&rpclist));
2057
2058                 osc_object_lock(osc);
2059         }
2060         RETURN(rc);
2061 }
2062
2063 #define list_to_obj(list, item) ({                                            \
2064         struct list_head *__tmp = (list)->next;                               \
2065         list_del_init(__tmp);                                         \
2066         list_entry(__tmp, struct osc_object, oo_##item);                      \
2067 })
2068
2069 /* This is called by osc_check_rpcs() to find which objects have pages that
2070  * we could be sending.  These lists are maintained by osc_makes_rpc(). */
2071 static struct osc_object *osc_next_obj(struct client_obd *cli)
2072 {
2073         ENTRY;
2074
2075         /* First return objects that have blocked locks so that they
2076          * will be flushed quickly and other clients can get the lock,
2077          * then objects which have pages ready to be stuffed into RPCs */
2078         if (!list_empty(&cli->cl_loi_hp_ready_list))
2079                 RETURN(list_to_obj(&cli->cl_loi_hp_ready_list, hp_ready_item));
2080         if (!list_empty(&cli->cl_loi_ready_list))
2081                 RETURN(list_to_obj(&cli->cl_loi_ready_list, ready_item));
2082
2083         /* then if we have cache waiters, return all objects with queued
2084          * writes.  This is especially important when many small files
2085          * have filled up the cache and not been fired into rpcs because
2086          * they don't pass the nr_pending/object threshhold */
2087         if (!list_empty(&cli->cl_cache_waiters) &&
2088             !list_empty(&cli->cl_loi_write_list))
2089                 RETURN(list_to_obj(&cli->cl_loi_write_list, write_item));
2090
2091         /* then return all queued objects when we have an invalid import
2092          * so that they get flushed */
2093         if (cli->cl_import == NULL || cli->cl_import->imp_invalid) {
2094                 if (!list_empty(&cli->cl_loi_write_list))
2095                         RETURN(list_to_obj(&cli->cl_loi_write_list,
2096                                            write_item));
2097                 if (!list_empty(&cli->cl_loi_read_list))
2098                         RETURN(list_to_obj(&cli->cl_loi_read_list,
2099                                            read_item));
2100         }
2101         RETURN(NULL);
2102 }
2103
2104 /* called with the loi list lock held */
2105 static void osc_check_rpcs(const struct lu_env *env, struct client_obd *cli,
2106                            pdl_policy_t pol)
2107 __must_hold(&cli->cl_loi_list_lock)
2108 {
2109         struct osc_object *osc;
2110         int rc = 0;
2111         ENTRY;
2112
2113         while ((osc = osc_next_obj(cli)) != NULL) {
2114                 struct cl_object *obj = osc2cl(osc);
2115                 struct lu_ref_link link;
2116
2117                 OSC_IO_DEBUG(osc, "%lu in flight\n", rpcs_in_flight(cli));
2118
2119                 if (osc_max_rpc_in_flight(cli, osc)) {
2120                         __osc_list_maint(cli, osc);
2121                         break;
2122                 }
2123
2124                 cl_object_get(obj);
2125                 client_obd_list_unlock(&cli->cl_loi_list_lock);
2126                 lu_object_ref_add_at(&obj->co_lu, &link, "check", current);
2127
2128                 /* attempt some read/write balancing by alternating between
2129                  * reads and writes in an object.  The makes_rpc checks here
2130                  * would be redundant if we were getting read/write work items
2131                  * instead of objects.  we don't want send_oap_rpc to drain a
2132                  * partial read pending queue when we're given this object to
2133                  * do io on writes while there are cache waiters */
2134                 osc_object_lock(osc);
2135                 if (osc_makes_rpc(cli, osc, OBD_BRW_WRITE)) {
2136                         rc = osc_send_write_rpc(env, cli, osc, pol);
2137                         if (rc < 0) {
2138                                 CERROR("Write request failed with %d\n", rc);
2139
2140                                 /* osc_send_write_rpc failed, mostly because of
2141                                  * memory pressure.
2142                                  *
2143                                  * It can't break here, because if:
2144                                  *  - a page was submitted by osc_io_submit, so
2145                                  *    page locked;
2146                                  *  - no request in flight
2147                                  *  - no subsequent request
2148                                  * The system will be in live-lock state,
2149                                  * because there is no chance to call
2150                                  * osc_io_unplug() and osc_check_rpcs() any
2151                                  * more. pdflush can't help in this case,
2152                                  * because it might be blocked at grabbing
2153                                  * the page lock as we mentioned.
2154                                  *
2155                                  * Anyway, continue to drain pages. */
2156                                 /* break; */
2157                         }
2158                 }
2159                 if (osc_makes_rpc(cli, osc, OBD_BRW_READ)) {
2160                         rc = osc_send_read_rpc(env, cli, osc, pol);
2161                         if (rc < 0)
2162                                 CERROR("Read request failed with %d\n", rc);
2163                 }
2164                 osc_object_unlock(osc);
2165
2166                 osc_list_maint(cli, osc);
2167                 lu_object_ref_del_at(&obj->co_lu, &link, "check", current);
2168                 cl_object_put(env, obj);
2169
2170                 client_obd_list_lock(&cli->cl_loi_list_lock);
2171         }
2172 }
2173
2174 static int osc_io_unplug0(const struct lu_env *env, struct client_obd *cli,
2175                           struct osc_object *osc, pdl_policy_t pol, int async)
2176 {
2177         int rc = 0;
2178
2179         if (osc != NULL && osc_list_maint(cli, osc) == 0)
2180                 return 0;
2181
2182         if (!async) {
2183                 /* disable osc_lru_shrink() temporarily to avoid
2184                  * potential stack overrun problem. LU-2859 */
2185                 atomic_inc(&cli->cl_lru_shrinkers);
2186                 client_obd_list_lock(&cli->cl_loi_list_lock);
2187                 osc_check_rpcs(env, cli, pol);
2188                 client_obd_list_unlock(&cli->cl_loi_list_lock);
2189                 atomic_dec(&cli->cl_lru_shrinkers);
2190         } else {
2191                 CDEBUG(D_CACHE, "Queue writeback work for client %p.\n", cli);
2192                 LASSERT(cli->cl_writeback_work != NULL);
2193                 rc = ptlrpcd_queue_work(cli->cl_writeback_work);
2194         }
2195         return rc;
2196 }
2197
2198 static int osc_io_unplug_async(const struct lu_env *env,
2199                                 struct client_obd *cli, struct osc_object *osc)
2200 {
2201         /* XXX: policy is no use actually. */
2202         return osc_io_unplug0(env, cli, osc, PDL_POLICY_ROUND, 1);
2203 }
2204
2205 void osc_io_unplug(const struct lu_env *env, struct client_obd *cli,
2206                    struct osc_object *osc, pdl_policy_t pol)
2207 {
2208         (void)osc_io_unplug0(env, cli, osc, pol, 0);
2209 }
2210
2211 int osc_prep_async_page(struct osc_object *osc, struct osc_page *ops,
2212                         struct page *page, loff_t offset)
2213 {
2214         struct obd_export     *exp = osc_export(osc);
2215         struct osc_async_page *oap = &ops->ops_oap;
2216         ENTRY;
2217
2218         if (!page)
2219                 return cfs_size_round(sizeof(*oap));
2220
2221         oap->oap_magic = OAP_MAGIC;
2222         oap->oap_cli = &exp->exp_obd->u.cli;
2223         oap->oap_obj = osc;
2224
2225         oap->oap_page = page;
2226         oap->oap_obj_off = offset;
2227         LASSERT(!(offset & ~CFS_PAGE_MASK));
2228
2229         if (!client_is_remote(exp) && cfs_capable(CFS_CAP_SYS_RESOURCE))
2230                 oap->oap_brw_flags = OBD_BRW_NOQUOTA;
2231
2232         INIT_LIST_HEAD(&oap->oap_pending_item);
2233         INIT_LIST_HEAD(&oap->oap_rpc_item);
2234
2235         spin_lock_init(&oap->oap_lock);
2236         CDEBUG(D_INFO, "oap %p page %p obj off "LPU64"\n",
2237                oap, page, oap->oap_obj_off);
2238         RETURN(0);
2239 }
2240
2241 int osc_queue_async_io(const struct lu_env *env, struct cl_io *io,
2242                        struct osc_page *ops)
2243 {
2244         struct osc_io *oio = osc_env_io(env);
2245         struct osc_extent     *ext = NULL;
2246         struct osc_async_page *oap = &ops->ops_oap;
2247         struct client_obd     *cli = oap->oap_cli;
2248         struct osc_object     *osc = oap->oap_obj;
2249         pgoff_t index;
2250         int    grants = 0;
2251         int    brw_flags = OBD_BRW_ASYNC;
2252         int    cmd = OBD_BRW_WRITE;
2253         int    need_release = 0;
2254         int    rc = 0;
2255         ENTRY;
2256
2257         if (oap->oap_magic != OAP_MAGIC)
2258                 RETURN(-EINVAL);
2259
2260         if (cli->cl_import == NULL || cli->cl_import->imp_invalid)
2261                 RETURN(-EIO);
2262
2263         if (!list_empty(&oap->oap_pending_item) ||
2264             !list_empty(&oap->oap_rpc_item))
2265                 RETURN(-EBUSY);
2266
2267         /* Set the OBD_BRW_SRVLOCK before the page is queued. */
2268         brw_flags |= ops->ops_srvlock ? OBD_BRW_SRVLOCK : 0;
2269         if (!client_is_remote(osc_export(osc)) &&
2270             cfs_capable(CFS_CAP_SYS_RESOURCE)) {
2271                 brw_flags |= OBD_BRW_NOQUOTA;
2272                 cmd |= OBD_BRW_NOQUOTA;
2273         }
2274
2275         /* check if the file's owner/group is over quota */
2276         if (!(cmd & OBD_BRW_NOQUOTA)) {
2277                 struct cl_object *obj;
2278                 struct cl_attr   *attr;
2279                 unsigned int qid[MAXQUOTAS];
2280
2281                 obj = cl_object_top(&osc->oo_cl);
2282                 attr = &osc_env_info(env)->oti_attr;
2283
2284                 cl_object_attr_lock(obj);
2285                 rc = cl_object_attr_get(env, obj, attr);
2286                 cl_object_attr_unlock(obj);
2287
2288                 qid[USRQUOTA] = attr->cat_uid;
2289                 qid[GRPQUOTA] = attr->cat_gid;
2290                 if (rc == 0 && osc_quota_chkdq(cli, qid) == NO_QUOTA)
2291                         rc = -EDQUOT;
2292                 if (rc)
2293                         RETURN(rc);
2294         }
2295
2296         oap->oap_cmd = cmd;
2297         oap->oap_page_off = ops->ops_from;
2298         oap->oap_count = ops->ops_to - ops->ops_from;
2299         /* No need to hold a lock here,
2300          * since this page is not in any list yet. */
2301         oap->oap_async_flags = 0;
2302         oap->oap_brw_flags = brw_flags;
2303
2304         OSC_IO_DEBUG(osc, "oap %p page %p added for cmd %d\n",
2305                      oap, oap->oap_page, oap->oap_cmd & OBD_BRW_RWMASK);
2306
2307         index = osc_index(oap2osc(oap));
2308
2309         /* Add this page into extent by the following steps:
2310          * 1. if there exists an active extent for this IO, mostly this page
2311          *    can be added to the active extent and sometimes we need to
2312          *    expand extent to accomodate this page;
2313          * 2. otherwise, a new extent will be allocated. */
2314
2315         ext = oio->oi_active;
2316         if (ext != NULL && ext->oe_start <= index && ext->oe_max_end >= index) {
2317                 /* one chunk plus extent overhead must be enough to write this
2318                  * page */
2319                 grants = (1 << cli->cl_chunkbits) + cli->cl_extent_tax;
2320                 if (ext->oe_end >= index)
2321                         grants = 0;
2322
2323                 /* it doesn't need any grant to dirty this page */
2324                 client_obd_list_lock(&cli->cl_loi_list_lock);
2325                 rc = osc_enter_cache_try(cli, oap, grants, 0);
2326                 client_obd_list_unlock(&cli->cl_loi_list_lock);
2327                 if (rc == 0) { /* try failed */
2328                         grants = 0;
2329                         need_release = 1;
2330                 } else if (ext->oe_end < index) {
2331                         int tmp = grants;
2332                         /* try to expand this extent */
2333                         rc = osc_extent_expand(ext, index, &tmp);
2334                         if (rc < 0) {
2335                                 need_release = 1;
2336                                 /* don't free reserved grant */
2337                         } else {
2338                                 OSC_EXTENT_DUMP(D_CACHE, ext,
2339                                                 "expanded for %lu.\n", index);
2340                                 osc_unreserve_grant(cli, grants, tmp);
2341                                 grants = 0;
2342                         }
2343                 }
2344                 rc = 0;
2345         } else if (ext != NULL) {
2346                 /* index is located outside of active extent */
2347                 need_release = 1;
2348         }
2349         if (need_release) {
2350                 osc_extent_release(env, ext);
2351                 oio->oi_active = NULL;
2352                 ext = NULL;
2353         }
2354
2355         if (ext == NULL) {
2356                 int tmp = (1 << cli->cl_chunkbits) + cli->cl_extent_tax;
2357
2358                 /* try to find new extent to cover this page */
2359                 LASSERT(oio->oi_active == NULL);
2360                 /* we may have allocated grant for this page if we failed
2361                  * to expand the previous active extent. */
2362                 LASSERT(ergo(grants > 0, grants >= tmp));
2363
2364                 rc = 0;
2365                 if (grants == 0) {
2366                         /* we haven't allocated grant for this page. */
2367                         rc = osc_enter_cache(env, cli, oap, tmp);
2368                         if (rc == 0)
2369                                 grants = tmp;
2370                 }
2371
2372                 tmp = grants;
2373                 if (rc == 0) {
2374                         ext = osc_extent_find(env, osc, index, &tmp);
2375                         if (IS_ERR(ext)) {
2376                                 LASSERT(tmp == grants);
2377                                 osc_exit_cache(cli, oap);
2378                                 rc = PTR_ERR(ext);
2379                                 ext = NULL;
2380                         } else {
2381                                 oio->oi_active = ext;
2382                         }
2383                 }
2384                 if (grants > 0)
2385                         osc_unreserve_grant(cli, grants, tmp);
2386         }
2387
2388         LASSERT(ergo(rc == 0, ext != NULL));
2389         if (ext != NULL) {
2390                 EASSERTF(ext->oe_end >= index && ext->oe_start <= index,
2391                          ext, "index = %lu.\n", index);
2392                 LASSERT((oap->oap_brw_flags & OBD_BRW_FROM_GRANT) != 0);
2393
2394                 osc_object_lock(osc);
2395                 if (ext->oe_nr_pages == 0)
2396                         ext->oe_srvlock = ops->ops_srvlock;
2397                 else
2398                         LASSERT(ext->oe_srvlock == ops->ops_srvlock);
2399                 ++ext->oe_nr_pages;
2400                 list_add_tail(&oap->oap_pending_item, &ext->oe_pages);
2401                 osc_object_unlock(osc);
2402         }
2403         RETURN(rc);
2404 }
2405
2406 int osc_teardown_async_page(const struct lu_env *env,
2407                             struct osc_object *obj, struct osc_page *ops)
2408 {
2409         struct osc_async_page *oap = &ops->ops_oap;
2410         struct osc_extent     *ext = NULL;
2411         int rc = 0;
2412         ENTRY;
2413
2414         LASSERT(oap->oap_magic == OAP_MAGIC);
2415
2416         CDEBUG(D_INFO, "teardown oap %p page %p at index %lu.\n",
2417                oap, ops, osc_index(oap2osc(oap)));
2418
2419         osc_object_lock(obj);
2420         if (!list_empty(&oap->oap_rpc_item)) {
2421                 CDEBUG(D_CACHE, "oap %p is not in cache.\n", oap);
2422                 rc = -EBUSY;
2423         } else if (!list_empty(&oap->oap_pending_item)) {
2424                 ext = osc_extent_lookup(obj, osc_index(oap2osc(oap)));
2425                 /* only truncated pages are allowed to be taken out.
2426                  * See osc_extent_truncate() and osc_cache_truncate_start()
2427                  * for details. */
2428                 if (ext != NULL && ext->oe_state != OES_TRUNC) {
2429                         OSC_EXTENT_DUMP(D_ERROR, ext, "trunc at %lu.\n",
2430                                         osc_index(oap2osc(oap)));
2431                         rc = -EBUSY;
2432                 }
2433         }
2434         osc_object_unlock(obj);
2435         if (ext != NULL)
2436                 osc_extent_put(env, ext);
2437         RETURN(rc);
2438 }
2439
2440 /**
2441  * This is called when a page is picked up by kernel to write out.
2442  *
2443  * We should find out the corresponding extent and add the whole extent
2444  * into urgent list. The extent may be being truncated or used, handle it
2445  * carefully.
2446  */
2447 int osc_flush_async_page(const struct lu_env *env, struct cl_io *io,
2448                          struct osc_page *ops)
2449 {
2450         struct osc_extent *ext   = NULL;
2451         struct osc_object *obj   = cl2osc(ops->ops_cl.cpl_obj);
2452         struct cl_page    *cp    = ops->ops_cl.cpl_page;
2453         pgoff_t            index = osc_index(ops);
2454         struct osc_async_page *oap = &ops->ops_oap;
2455         bool unplug = false;
2456         int rc = 0;
2457         ENTRY;
2458
2459         osc_object_lock(obj);
2460         ext = osc_extent_lookup(obj, index);
2461         if (ext == NULL) {
2462                 osc_extent_tree_dump(D_ERROR, obj);
2463                 LASSERTF(0, "page index %lu is NOT covered.\n", index);
2464         }
2465
2466         switch (ext->oe_state) {
2467         case OES_RPC:
2468         case OES_LOCK_DONE:
2469                 CL_PAGE_DEBUG(D_ERROR, env, cp, "flush an in-rpc page?\n");
2470                 LASSERT(0);
2471                 break;
2472         case OES_LOCKING:
2473                 /* If we know this extent is being written out, we should abort
2474                  * so that the writer can make this page ready. Otherwise, there
2475                  * exists a deadlock problem because other process can wait for
2476                  * page writeback bit holding page lock; and meanwhile in
2477                  * vvp_page_make_ready(), we need to grab page lock before
2478                  * really sending the RPC. */
2479         case OES_TRUNC:
2480                 /* race with truncate, page will be redirtied */
2481         case OES_ACTIVE:
2482                 /* The extent is active so we need to abort and let the caller
2483                  * re-dirty the page. If we continued on here, and we were the
2484                  * one making the extent active, we could deadlock waiting for
2485                  * the page writeback to clear but it won't because the extent
2486                  * is active and won't be written out. */
2487                 GOTO(out, rc = -EAGAIN);
2488         default:
2489                 break;
2490         }
2491
2492         rc = cl_page_prep(env, io, cp, CRT_WRITE);
2493         if (rc)
2494                 GOTO(out, rc);
2495
2496         spin_lock(&oap->oap_lock);
2497         oap->oap_async_flags |= ASYNC_READY|ASYNC_URGENT;
2498         spin_unlock(&oap->oap_lock);
2499
2500         if (memory_pressure_get())
2501                 ext->oe_memalloc = 1;
2502
2503         ext->oe_urgent = 1;
2504         if (ext->oe_state == OES_CACHE) {
2505                 OSC_EXTENT_DUMP(D_CACHE, ext,
2506                                 "flush page %p make it urgent.\n", oap);
2507                 if (list_empty(&ext->oe_link))
2508                         list_add_tail(&ext->oe_link, &obj->oo_urgent_exts);
2509                 unplug = true;
2510         }
2511         rc = 0;
2512         EXIT;
2513
2514 out:
2515         osc_object_unlock(obj);
2516         osc_extent_put(env, ext);
2517         if (unplug)
2518                 osc_io_unplug_async(env, osc_cli(obj), obj);
2519         return rc;
2520 }
2521
2522 /**
2523  * this is called when a sync waiter receives an interruption.  Its job is to
2524  * get the caller woken as soon as possible.  If its page hasn't been put in an
2525  * rpc yet it can dequeue immediately.  Otherwise it has to mark the rpc as
2526  * desiring interruption which will forcefully complete the rpc once the rpc
2527  * has timed out.
2528  */
2529 int osc_cancel_async_page(const struct lu_env *env, struct osc_page *ops)
2530 {
2531         struct osc_async_page *oap = &ops->ops_oap;
2532         struct osc_object     *obj = oap->oap_obj;
2533         struct client_obd     *cli = osc_cli(obj);
2534         struct osc_extent     *ext;
2535         struct osc_extent     *found = NULL;
2536         struct list_head            *plist;
2537         pgoff_t index = osc_index(ops);
2538         int     rc = -EBUSY;
2539         int     cmd;
2540         ENTRY;
2541
2542         LASSERT(!oap->oap_interrupted);
2543         oap->oap_interrupted = 1;
2544
2545         /* Find out the caching extent */
2546         osc_object_lock(obj);
2547         if (oap->oap_cmd & OBD_BRW_WRITE) {
2548                 plist = &obj->oo_urgent_exts;
2549                 cmd   = OBD_BRW_WRITE;
2550         } else {
2551                 plist = &obj->oo_reading_exts;
2552                 cmd   = OBD_BRW_READ;
2553         }
2554         list_for_each_entry(ext, plist, oe_link) {
2555                 if (ext->oe_start <= index && ext->oe_end >= index) {
2556                         LASSERT(ext->oe_state == OES_LOCK_DONE);
2557                         /* For OES_LOCK_DONE state extent, it has already held
2558                          * a refcount for RPC. */
2559                         found = osc_extent_get(ext);
2560                         break;
2561                 }
2562         }
2563         if (found != NULL) {
2564                 list_del_init(&found->oe_link);
2565                 osc_update_pending(obj, cmd, -found->oe_nr_pages);
2566                 osc_object_unlock(obj);
2567
2568                 osc_extent_finish(env, found, 0, -EINTR);
2569                 osc_extent_put(env, found);
2570                 rc = 0;
2571         } else {
2572                 osc_object_unlock(obj);
2573                 /* ok, it's been put in an rpc. only one oap gets a request
2574                  * reference */
2575                 if (oap->oap_request != NULL) {
2576                         ptlrpc_mark_interrupted(oap->oap_request);
2577                         ptlrpcd_wake(oap->oap_request);
2578                         ptlrpc_req_finished(oap->oap_request);
2579                         oap->oap_request = NULL;
2580                 }
2581         }
2582
2583         osc_list_maint(cli, obj);
2584         RETURN(rc);
2585 }
2586
2587 int osc_queue_sync_pages(const struct lu_env *env, struct osc_object *obj,
2588                          struct list_head *list, int cmd, int brw_flags)
2589 {
2590         struct client_obd     *cli = osc_cli(obj);
2591         struct osc_extent     *ext;
2592         struct osc_async_page *oap;
2593         int     page_count = 0;
2594         int     mppr       = cli->cl_max_pages_per_rpc;
2595         pgoff_t start      = CL_PAGE_EOF;
2596         pgoff_t end        = 0;
2597         ENTRY;
2598
2599         list_for_each_entry(oap, list, oap_pending_item) {
2600                 pgoff_t index = osc_index(oap2osc(oap));
2601                 if (index > end)
2602                         end = index;
2603                 if (index < start)
2604                         start = index;
2605                 ++page_count;
2606                 mppr <<= (page_count > mppr);
2607         }
2608
2609         ext = osc_extent_alloc(obj);
2610         if (ext == NULL) {
2611                 list_for_each_entry(oap, list, oap_pending_item) {
2612                         list_del_init(&oap->oap_pending_item);
2613                         osc_ap_completion(env, cli, oap, 0, -ENOMEM);
2614                 }
2615                 RETURN(-ENOMEM);
2616         }
2617
2618         ext->oe_rw = !!(cmd & OBD_BRW_READ);
2619         ext->oe_urgent = 1;
2620         ext->oe_start = start;
2621         ext->oe_end = ext->oe_max_end = end;
2622         ext->oe_obj = obj;
2623         ext->oe_srvlock = !!(brw_flags & OBD_BRW_SRVLOCK);
2624         ext->oe_nr_pages = page_count;
2625         ext->oe_mppr = mppr;
2626         list_splice_init(list, &ext->oe_pages);
2627
2628         osc_object_lock(obj);
2629         /* Reuse the initial refcount for RPC, don't drop it */
2630         osc_extent_state_set(ext, OES_LOCK_DONE);
2631         if (cmd & OBD_BRW_WRITE) {
2632                 list_add_tail(&ext->oe_link, &obj->oo_urgent_exts);
2633                 osc_update_pending(obj, OBD_BRW_WRITE, page_count);
2634         } else {
2635                 list_add_tail(&ext->oe_link, &obj->oo_reading_exts);
2636                 osc_update_pending(obj, OBD_BRW_READ, page_count);
2637         }
2638         osc_object_unlock(obj);
2639
2640         osc_io_unplug_async(env, cli, obj);
2641         RETURN(0);
2642 }
2643
2644 /**
2645  * Called by osc_io_setattr_start() to freeze and destroy covering extents.
2646  */
2647 int osc_cache_truncate_start(const struct lu_env *env, struct osc_io *oio,
2648                              struct osc_object *obj, __u64 size)
2649 {
2650         struct client_obd *cli = osc_cli(obj);
2651         struct osc_extent *ext;
2652         struct osc_extent *waiting = NULL;
2653         pgoff_t index;
2654         struct list_head list = LIST_HEAD_INIT(list);
2655         int result = 0;
2656         bool partial;
2657         ENTRY;
2658
2659         /* pages with index greater or equal to index will be truncated. */
2660         index = cl_index(osc2cl(obj), size);
2661         partial = size > cl_offset(osc2cl(obj), index);
2662
2663 again:
2664         osc_object_lock(obj);
2665         ext = osc_extent_search(obj, index);
2666         if (ext == NULL)
2667                 ext = first_extent(obj);
2668         else if (ext->oe_end < index)
2669                 ext = next_extent(ext);
2670         while (ext != NULL) {
2671                 EASSERT(ext->oe_state != OES_TRUNC, ext);
2672
2673                 if (ext->oe_state > OES_CACHE || ext->oe_urgent) {
2674                         /* if ext is in urgent state, it means there must exist
2675                          * a page already having been flushed by write_page().
2676                          * We have to wait for this extent because we can't
2677                          * truncate that page. */
2678                         LASSERT(!ext->oe_hp);
2679                         OSC_EXTENT_DUMP(D_CACHE, ext,
2680                                         "waiting for busy extent\n");
2681                         waiting = osc_extent_get(ext);
2682                         break;
2683                 }
2684
2685                 OSC_EXTENT_DUMP(D_CACHE, ext, "try to trunc:"LPU64".\n", size);
2686
2687                 osc_extent_get(ext);
2688                 if (ext->oe_state == OES_ACTIVE) {
2689                         /* though we grab inode mutex for write path, but we
2690                          * release it before releasing extent(in osc_io_end()),
2691                          * so there is a race window that an extent is still
2692                          * in OES_ACTIVE when truncate starts. */
2693                         LASSERT(!ext->oe_trunc_pending);
2694                         ext->oe_trunc_pending = 1;
2695                 } else {
2696                         EASSERT(ext->oe_state == OES_CACHE, ext);
2697                         osc_extent_state_set(ext, OES_TRUNC);
2698                         osc_update_pending(obj, OBD_BRW_WRITE,
2699                                            -ext->oe_nr_pages);
2700                 }
2701                 EASSERT(list_empty(&ext->oe_link), ext);
2702                 list_add_tail(&ext->oe_link, &list);
2703
2704                 ext = next_extent(ext);
2705         }
2706         osc_object_unlock(obj);
2707
2708         osc_list_maint(cli, obj);
2709
2710         while (!list_empty(&list)) {
2711                 int rc;
2712
2713                 ext = list_entry(list.next, struct osc_extent, oe_link);
2714                 list_del_init(&ext->oe_link);
2715
2716                 /* extent may be in OES_ACTIVE state because inode mutex
2717                  * is released before osc_io_end() in file write case */
2718                 if (ext->oe_state != OES_TRUNC)
2719                         osc_extent_wait(env, ext, OES_TRUNC);
2720
2721                 rc = osc_extent_truncate(ext, index, partial);
2722                 if (rc < 0) {
2723                         if (result == 0)
2724                                 result = rc;
2725
2726                         OSC_EXTENT_DUMP(D_ERROR, ext,
2727                                         "truncate error %d\n", rc);
2728                 } else if (ext->oe_nr_pages == 0) {
2729                         osc_extent_remove(ext);
2730                 } else {
2731                         /* this must be an overlapped extent which means only
2732                          * part of pages in this extent have been truncated.
2733                          */
2734                         EASSERTF(ext->oe_start <= index, ext,
2735                                  "trunc index = %lu/%d.\n", index, partial);
2736                         /* fix index to skip this partially truncated extent */
2737                         index = ext->oe_end + 1;
2738                         partial = false;
2739
2740                         /* we need to hold this extent in OES_TRUNC state so
2741                          * that no writeback will happen. This is to avoid
2742                          * BUG 17397. */
2743                         LASSERT(oio->oi_trunc == NULL);
2744                         oio->oi_trunc = osc_extent_get(ext);
2745                         OSC_EXTENT_DUMP(D_CACHE, ext,
2746                                         "trunc at "LPU64"\n", size);
2747                 }
2748                 osc_extent_put(env, ext);
2749         }
2750         if (waiting != NULL) {
2751                 int rc;
2752
2753                 /* ignore the result of osc_extent_wait the write initiator
2754                  * should take care of it. */
2755                 rc = osc_extent_wait(env, waiting, OES_INV);
2756                 if (rc < 0)
2757                         OSC_EXTENT_DUMP(D_CACHE, waiting, "error: %d.\n", rc);
2758
2759                 osc_extent_put(env, waiting);
2760                 waiting = NULL;
2761                 goto again;
2762         }
2763         RETURN(result);
2764 }
2765
2766 /**
2767  * Called after osc_io_setattr_end to add oio->oi_trunc back to cache.
2768  */
2769 void osc_cache_truncate_end(const struct lu_env *env, struct osc_io *oio,
2770                             struct osc_object *obj)
2771 {
2772         struct osc_extent *ext = oio->oi_trunc;
2773
2774         oio->oi_trunc = NULL;
2775         if (ext != NULL) {
2776                 bool unplug = false;
2777
2778                 EASSERT(ext->oe_nr_pages > 0, ext);
2779                 EASSERT(ext->oe_state == OES_TRUNC, ext);
2780                 EASSERT(!ext->oe_urgent, ext);
2781
2782                 OSC_EXTENT_DUMP(D_CACHE, ext, "trunc -> cache.\n");
2783                 osc_object_lock(obj);
2784                 osc_extent_state_set(ext, OES_CACHE);
2785                 if (ext->oe_fsync_wait && !ext->oe_urgent) {
2786                         ext->oe_urgent = 1;
2787                         list_move_tail(&ext->oe_link, &obj->oo_urgent_exts);
2788                         unplug = true;
2789                 }
2790                 osc_update_pending(obj, OBD_BRW_WRITE, ext->oe_nr_pages);
2791                 osc_object_unlock(obj);
2792                 osc_extent_put(env, ext);
2793
2794                 if (unplug)
2795                         osc_io_unplug_async(env, osc_cli(obj), obj);
2796         }
2797 }
2798
2799 /**
2800  * Wait for extents in a specific range to be written out.
2801  * The caller must have called osc_cache_writeback_range() to issue IO
2802  * otherwise it will take a long time for this function to finish.
2803  *
2804  * Caller must hold inode_mutex , or cancel exclusive dlm lock so that
2805  * nobody else can dirty this range of file while we're waiting for
2806  * extents to be written.
2807  */
2808 int osc_cache_wait_range(const struct lu_env *env, struct osc_object *obj,
2809                          pgoff_t start, pgoff_t end)
2810 {
2811         struct osc_extent *ext;
2812         pgoff_t index = start;
2813         int     result = 0;
2814         ENTRY;
2815
2816 again:
2817         osc_object_lock(obj);
2818         ext = osc_extent_search(obj, index);
2819         if (ext == NULL)
2820                 ext = first_extent(obj);
2821         else if (ext->oe_end < index)
2822                 ext = next_extent(ext);
2823         while (ext != NULL) {
2824                 int rc;
2825
2826                 if (ext->oe_start > end)
2827                         break;
2828
2829                 if (!ext->oe_fsync_wait) {
2830                         ext = next_extent(ext);
2831                         continue;
2832                 }
2833
2834                 EASSERT(ergo(ext->oe_state == OES_CACHE,
2835                              ext->oe_hp || ext->oe_urgent), ext);
2836                 EASSERT(ergo(ext->oe_state == OES_ACTIVE,
2837                              !ext->oe_hp && ext->oe_urgent), ext);
2838
2839                 index = ext->oe_end + 1;
2840                 osc_extent_get(ext);
2841                 osc_object_unlock(obj);
2842
2843                 rc = osc_extent_wait(env, ext, OES_INV);
2844                 if (result == 0)
2845                         result = rc;
2846                 osc_extent_put(env, ext);
2847                 goto again;
2848         }
2849         osc_object_unlock(obj);
2850
2851         OSC_IO_DEBUG(obj, "sync file range.\n");
2852         RETURN(result);
2853 }
2854
2855 /**
2856  * Called to write out a range of osc object.
2857  *
2858  * @hp     : should be set this is caused by lock cancel;
2859  * @discard: is set if dirty pages should be dropped - file will be deleted or
2860  *         truncated, this implies there is no partially discarding extents.
2861  *
2862  * Return how many pages will be issued, or error code if error occurred.
2863  */
2864 int osc_cache_writeback_range(const struct lu_env *env, struct osc_object *obj,
2865                               pgoff_t start, pgoff_t end, int hp, int discard)
2866 {
2867         struct osc_extent *ext;
2868         struct list_head discard_list = LIST_HEAD_INIT(discard_list);
2869         bool unplug = false;
2870         int result = 0;
2871         ENTRY;
2872
2873         osc_object_lock(obj);
2874         ext = osc_extent_search(obj, start);
2875         if (ext == NULL)
2876                 ext = first_extent(obj);
2877         else if (ext->oe_end < start)
2878                 ext = next_extent(ext);
2879         while (ext != NULL) {
2880                 if (ext->oe_start > end)
2881                         break;
2882
2883                 ext->oe_fsync_wait = 1;
2884                 switch (ext->oe_state) {
2885                 case OES_CACHE:
2886                         result += ext->oe_nr_pages;
2887                         if (!discard) {
2888                                 struct list_head *list = NULL;
2889                                 if (hp) {
2890                                         EASSERT(!ext->oe_hp, ext);
2891                                         ext->oe_hp = 1;
2892                                         list = &obj->oo_hp_exts;
2893                                 } else if (!ext->oe_urgent) {
2894                                         ext->oe_urgent = 1;
2895                                         list = &obj->oo_urgent_exts;
2896                                 }
2897                                 if (list != NULL)
2898                                         list_move_tail(&ext->oe_link, list);
2899                                 unplug = true;
2900                         } else {
2901                                 /* the only discarder is lock cancelling, so
2902                                  * [start, end] must contain this extent */
2903                                 EASSERT(ext->oe_start >= start &&
2904                                         ext->oe_max_end <= end, ext);
2905                                 osc_extent_state_set(ext, OES_LOCKING);
2906                                 ext->oe_owner = current;
2907                                 list_move_tail(&ext->oe_link,
2908                                                    &discard_list);
2909                                 osc_update_pending(obj, OBD_BRW_WRITE,
2910                                                    -ext->oe_nr_pages);
2911                         }
2912                         break;
2913                 case OES_ACTIVE:
2914                         /* It's pretty bad to wait for ACTIVE extents, because
2915                          * we don't know how long we will wait for it to be
2916                          * flushed since it may be blocked at awaiting more
2917                          * grants. We do this for the correctness of fsync. */
2918                         LASSERT(hp == 0 && discard == 0);
2919                         ext->oe_urgent = 1;
2920                         break;
2921                 case OES_TRUNC:
2922                         /* this extent is being truncated, can't do anything
2923                          * for it now. it will be set to urgent after truncate
2924                          * is finished in osc_cache_truncate_end(). */
2925                 default:
2926                         break;
2927                 }
2928                 ext = next_extent(ext);
2929         }
2930         osc_object_unlock(obj);
2931
2932         LASSERT(ergo(!discard, list_empty(&discard_list)));
2933         if (!list_empty(&discard_list)) {
2934                 struct osc_extent *tmp;
2935                 int rc;
2936
2937                 osc_list_maint(osc_cli(obj), obj);
2938                 list_for_each_entry_safe(ext, tmp, &discard_list, oe_link) {
2939                         list_del_init(&ext->oe_link);
2940                         EASSERT(ext->oe_state == OES_LOCKING, ext);
2941
2942                         /* Discard caching pages. We don't actually write this
2943                          * extent out but we complete it as if we did. */
2944                         rc = osc_extent_make_ready(env, ext);
2945                         if (unlikely(rc < 0)) {
2946                                 OSC_EXTENT_DUMP(D_ERROR, ext,
2947                                                 "make_ready returned %d\n", rc);
2948                                 if (result >= 0)
2949                                         result = rc;
2950                         }
2951
2952                         /* finish the extent as if the pages were sent */
2953                         osc_extent_finish(env, ext, 0, 0);
2954                 }
2955         }
2956
2957         if (unplug)
2958                 osc_io_unplug(env, osc_cli(obj), obj, PDL_POLICY_ROUND);
2959
2960         if (hp || discard) {
2961                 int rc;
2962                 rc = osc_cache_wait_range(env, obj, start, end);
2963                 if (result >= 0 && rc < 0)
2964                         result = rc;
2965         }
2966
2967         OSC_IO_DEBUG(obj, "pageout [%lu, %lu], %d.\n", start, end, result);
2968         RETURN(result);
2969 }
2970
2971 /**
2972  * Returns a list of pages by a given [start, end] of \a obj.
2973  *
2974  * \param resched If not NULL, then we give up before hogging CPU for too
2975  * long and set *resched = 1, in that case caller should implement a retry
2976  * logic.
2977  *
2978  * Gang tree lookup (radix_tree_gang_lookup()) optimization is absolutely
2979  * crucial in the face of [offset, EOF] locks.
2980  *
2981  * Return at least one page in @queue unless there is no covered page.
2982  */
2983 int osc_page_gang_lookup(const struct lu_env *env, struct cl_io *io,
2984                         struct osc_object *osc, pgoff_t start, pgoff_t end,
2985                         osc_page_gang_cbt cb, void *cbdata)
2986 {
2987         struct osc_page *ops;
2988         void            **pvec;
2989         pgoff_t         idx;
2990         unsigned int    nr;
2991         unsigned int    i;
2992         unsigned int    j;
2993         int             res = CLP_GANG_OKAY;
2994         bool            tree_lock = true;
2995         ENTRY;
2996
2997         idx = start;
2998         pvec = osc_env_info(env)->oti_pvec;
2999         spin_lock(&osc->oo_tree_lock);
3000         while ((nr = radix_tree_gang_lookup(&osc->oo_tree, pvec,
3001                                             idx, OTI_PVEC_SIZE)) > 0) {
3002                 struct cl_page *page;
3003                 bool end_of_region = false;
3004
3005                 for (i = 0, j = 0; i < nr; ++i) {
3006                         ops = pvec[i];
3007                         pvec[i] = NULL;
3008
3009                         idx = osc_index(ops);
3010                         if (idx > end) {
3011                                 end_of_region = true;
3012                                 break;
3013                         }
3014
3015                         page = ops->ops_cl.cpl_page;
3016                         LASSERT(page->cp_type == CPT_CACHEABLE);
3017                         if (page->cp_state == CPS_FREEING)
3018                                 continue;
3019
3020                         cl_page_get(page);
3021                         lu_ref_add_atomic(&page->cp_reference,
3022                                           "gang_lookup", current);
3023                         pvec[j++] = ops;
3024                 }
3025                 ++idx;
3026
3027                 /*
3028                  * Here a delicate locking dance is performed. Current thread
3029                  * holds a reference to a page, but has to own it before it
3030                  * can be placed into queue. Owning implies waiting, so
3031                  * radix-tree lock is to be released. After a wait one has to
3032                  * check that pages weren't truncated (cl_page_own() returns
3033                  * error in the latter case).
3034                  */
3035                 spin_unlock(&osc->oo_tree_lock);
3036                 tree_lock = false;
3037
3038                 for (i = 0; i < j; ++i) {
3039                         ops = pvec[i];
3040                         if (res == CLP_GANG_OKAY)
3041                                 res = (*cb)(env, io, ops, cbdata);
3042
3043                         page = ops->ops_cl.cpl_page;
3044                         lu_ref_del(&page->cp_reference, "gang_lookup", current);
3045                         cl_page_put(env, page);
3046                 }
3047                 if (nr < OTI_PVEC_SIZE || end_of_region)
3048                         break;
3049
3050                 if (res == CLP_GANG_OKAY && need_resched())
3051                         res = CLP_GANG_RESCHED;
3052                 if (res != CLP_GANG_OKAY)
3053                         break;
3054
3055                 spin_lock(&osc->oo_tree_lock);
3056                 tree_lock = true;
3057         }
3058         if (tree_lock)
3059                 spin_unlock(&osc->oo_tree_lock);
3060         RETURN(res);
3061 }
3062
3063 /**
3064  * Check if page @page is covered by an extra lock or discard it.
3065  */
3066 static int check_and_discard_cb(const struct lu_env *env, struct cl_io *io,
3067                                 struct osc_page *ops, void *cbdata)
3068 {
3069         struct osc_thread_info *info = osc_env_info(env);
3070         struct cl_lock *lock = cbdata;
3071         pgoff_t index;
3072
3073         index = osc_index(ops);
3074         if (index >= info->oti_fn_index) {
3075                 struct cl_lock *tmp;
3076                 struct cl_page *page = ops->ops_cl.cpl_page;
3077
3078                 /* refresh non-overlapped index */
3079                 tmp = cl_lock_at_pgoff(env, lock->cll_descr.cld_obj, index,
3080                                        lock, 1, 0);
3081                 if (tmp != NULL) {
3082                         /* Cache the first-non-overlapped index so as to skip
3083                          * all pages within [index, oti_fn_index). This
3084                          * is safe because if tmp lock is canceled, it will
3085                          * discard these pages. */
3086                         info->oti_fn_index = tmp->cll_descr.cld_end + 1;
3087                         if (tmp->cll_descr.cld_end == CL_PAGE_EOF)
3088                                 info->oti_fn_index = CL_PAGE_EOF;
3089                         cl_lock_put(env, tmp);
3090                 } else if (cl_page_own(env, io, page) == 0) {
3091                         /* discard the page */
3092                         cl_page_discard(env, io, page);
3093                         cl_page_disown(env, io, page);
3094                 } else {
3095                         LASSERT(page->cp_state == CPS_FREEING);
3096                 }
3097         }
3098
3099         info->oti_next_index = index + 1;
3100         return CLP_GANG_OKAY;
3101 }
3102
3103 static int discard_cb(const struct lu_env *env, struct cl_io *io,
3104                       struct osc_page *ops, void *cbdata)
3105 {
3106         struct osc_thread_info *info = osc_env_info(env);
3107         struct cl_lock *lock = cbdata;
3108         struct cl_page *page = ops->ops_cl.cpl_page;
3109
3110         LASSERT(lock->cll_descr.cld_mode >= CLM_WRITE);
3111
3112         /* page is top page. */
3113         info->oti_next_index = osc_index(ops) + 1;
3114         if (cl_page_own(env, io, page) == 0) {
3115                 KLASSERT(ergo(page->cp_type == CPT_CACHEABLE,
3116                               !PageDirty(cl_page_vmpage(page))));
3117
3118                 /* discard the page */
3119                 cl_page_discard(env, io, page);
3120                 cl_page_disown(env, io, page);
3121         } else {
3122                 LASSERT(page->cp_state == CPS_FREEING);
3123         }
3124
3125         return CLP_GANG_OKAY;
3126 }
3127
3128 /**
3129  * Discard pages protected by the given lock. This function traverses radix
3130  * tree to find all covering pages and discard them. If a page is being covered
3131  * by other locks, it should remain in cache.
3132  *
3133  * If error happens on any step, the process continues anyway (the reasoning
3134  * behind this being that lock cancellation cannot be delayed indefinitely).
3135  */
3136 int osc_lock_discard_pages(const struct lu_env *env, struct osc_lock *ols)
3137 {
3138         struct osc_thread_info *info = osc_env_info(env);
3139         struct cl_io *io = &info->oti_io;
3140         struct cl_object *osc = ols->ols_cl.cls_obj;
3141         struct cl_lock *lock = ols->ols_cl.cls_lock;
3142         struct cl_lock_descr *descr = &lock->cll_descr;
3143         osc_page_gang_cbt cb;
3144         int res;
3145         int result;
3146
3147         ENTRY;
3148
3149         io->ci_obj = cl_object_top(osc);
3150         io->ci_ignore_layout = 1;
3151         result = cl_io_init(env, io, CIT_MISC, io->ci_obj);
3152         if (result != 0)
3153                 GOTO(out, result);
3154
3155         cb = descr->cld_mode == CLM_READ ? check_and_discard_cb : discard_cb;
3156         info->oti_fn_index = info->oti_next_index = descr->cld_start;
3157         do {
3158                 res = osc_page_gang_lookup(env, io, cl2osc(osc),
3159                                            info->oti_next_index, descr->cld_end,
3160                                            cb, (void *)lock);
3161                 if (info->oti_next_index > descr->cld_end)
3162                         break;
3163
3164                 if (res == CLP_GANG_RESCHED)
3165                         cond_resched();
3166         } while (res != CLP_GANG_OKAY);
3167 out:
3168         cl_io_fini(env, io);
3169         RETURN(result);
3170 }
3171
3172
3173 /** @} osc */