fs/fscache/operation.c

   1 /* FS-Cache worker operation management routines
   2  *
   3  * Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
   4  * Written by David Howells (dhowells@redhat.com)
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the License, or (at your option) any later version.
  10  *
  11  * See Documentation/filesystems/caching/operations.txt
  12  */
  13
  14 #define FSCACHE_DEBUG_LEVEL OPERATION
  15 #include <linux/module.h>
  16 #include <linux/seq_file.h>
  17 #include <linux/slab.h>
  18 #include "internal.h"
  19
  20 atomic_t fscache_op_debug_id;
  21 EXPORT_SYMBOL(fscache_op_debug_id);
  22
  23 static void fscache_operation_dummy_cancel(struct fscache_operation *op)
  24 {
  25 }
  26
  27 /**
  28  * fscache_operation_init - Do basic initialisation of an operation
  29  * @op: The operation to initialise
  30  * @release: The release function to assign
  31  *
  32  * Do basic initialisation of an operation.  The caller must still set flags,
  33  * object and processor if needed.
  34  */
  35 void fscache_operation_init(struct fscache_cookie *cookie,
  36                             struct fscache_operation *op,
  37                             fscache_operation_processor_t processor,
  38                             fscache_operation_cancel_t cancel,
  39                             fscache_operation_release_t release)
  40 {
  41         INIT_WORK(&op->work, fscache_op_work_func);
  42         atomic_set(&op->usage, 1);
  43         op->state = FSCACHE_OP_ST_INITIALISED;
  44         op->debug_id = atomic_inc_return(&fscache_op_debug_id);
  45         op->processor = processor;
  46         op->cancel = cancel ?: fscache_operation_dummy_cancel;
  47         op->release = release;
  48         INIT_LIST_HEAD(&op->pend_link);
  49         fscache_stat(&fscache_n_op_initialised);
  50         trace_fscache_op(cookie, op, fscache_op_init);
  51 }
  52 EXPORT_SYMBOL(fscache_operation_init);
  53
  54 /**
  55  * fscache_enqueue_operation - Enqueue an operation for processing
  56  * @op: The operation to enqueue
  57  *
  58  * Enqueue an operation for processing by the FS-Cache thread pool.
  59  *
  60  * This will get its own ref on the object.
  61  */
  62 void fscache_enqueue_operation(struct fscache_operation *op)
  63 {
  64         struct fscache_cookie *cookie = op->object->cookie;
  65
  66         _enter("{OBJ%x OP%x,%u}",
  67                op->object->debug_id, op->debug_id, atomic_read(&op->usage));
  68
  69         ASSERT(list_empty(&op->pend_link));
  70         ASSERT(op->processor != NULL);
  71         ASSERT(fscache_object_is_available(op->object));
  72         ASSERTCMP(atomic_read(&op->usage), >, 0);
  73         ASSERTCMP(op->state, ==, FSCACHE_OP_ST_IN_PROGRESS);
  74
  75         fscache_stat(&fscache_n_op_enqueue);
  76         switch (op->flags & FSCACHE_OP_TYPE) {
  77         case FSCACHE_OP_ASYNC:
  78                 trace_fscache_op(cookie, op, fscache_op_enqueue_async);
  79                 _debug("queue async");
  80                 atomic_inc(&op->usage);
  81                 if (!queue_work(fscache_op_wq, &op->work))
  82                         fscache_put_operation(op);
  83                 break;
  84         case FSCACHE_OP_MYTHREAD:
  85                 trace_fscache_op(cookie, op, fscache_op_enqueue_mythread);
  86                 _debug("queue for caller's attention");
  87                 break;
  88         default:
  89                 pr_err("Unexpected op type %lx", op->flags);
  90                 BUG();
  91                 break;
  92         }
  93 }
  94 EXPORT_SYMBOL(fscache_enqueue_operation);
  95
  96 /*
  97  * start an op running
  98  */
  99 static void fscache_run_op(struct fscache_object *object,
 100                            struct fscache_operation *op)
 101 {
 102         ASSERTCMP(op->state, ==, FSCACHE_OP_ST_PENDING);
 103
 104         op->state = FSCACHE_OP_ST_IN_PROGRESS;
 105         object->n_in_progress++;
 106         if (test_and_clear_bit(FSCACHE_OP_WAITING, &op->flags))
 107                 wake_up_bit(&op->flags, FSCACHE_OP_WAITING);
 108         if (op->processor)
 109                 fscache_enqueue_operation(op);
 110         else
 111                 trace_fscache_op(object->cookie, op, fscache_op_run);
 112         fscache_stat(&fscache_n_op_run);
 113 }
 114
 115 /*
 116  * report an unexpected submission
 117  */
 118 static void fscache_report_unexpected_submission(struct fscache_object *object,
 119                                                  struct fscache_operation *op,
 120                                                  const struct fscache_state *ostate)
 121 {
 122         static bool once_only;
 123         struct fscache_operation *p;
 124         unsigned n;
 125
 126         if (once_only)
 127                 return;
 128         once_only = true;
 129
 130         kdebug("unexpected submission OP%x [OBJ%x %s]",
 131                op->debug_id, object->debug_id, object->state->name);
 132         kdebug("objstate=%s [%s]", object->state->name, ostate->name);
 133         kdebug("objflags=%lx", object->flags);
 134         kdebug("objevent=%lx [%lx]", object->events, object->event_mask);
 135         kdebug("ops=%u inp=%u exc=%u",
 136                object->n_ops, object->n_in_progress, object->n_exclusive);
 137
 138         if (!list_empty(&object->pending_ops)) {
 139                 n = 0;
 140                 list_for_each_entry(p, &object->pending_ops, pend_link) {
 141                         ASSERTCMP(p->object, ==, object);
 142                         kdebug("%p %p", op->processor, op->release);
 143                         n++;
 144                 }
 145
 146                 kdebug("n=%u", n);
 147         }
 148
 149         dump_stack();
 150 }
 151
 152 /*
 153  * submit an exclusive operation for an object
 154  * - other ops are excluded from running simultaneously with this one
 155  * - this gets any extra refs it needs on an op
 156  */
 157 int fscache_submit_exclusive_op(struct fscache_object *object,
 158                                 struct fscache_operation *op)
 159 {
 160         const struct fscache_state *ostate;
 161         unsigned long flags;
 162         int ret;
 163
 164         _enter("{OBJ%x OP%x},", object->debug_id, op->debug_id);
 165
 166         trace_fscache_op(object->cookie, op, fscache_op_submit_ex);
 167
 168         ASSERTCMP(op->state, ==, FSCACHE_OP_ST_INITIALISED);
 169         ASSERTCMP(atomic_read(&op->usage), >, 0);
 170
 171         spin_lock(&object->lock);
 172         ASSERTCMP(object->n_ops, >=, object->n_in_progress);
 173         ASSERTCMP(object->n_ops, >=, object->n_exclusive);
 174         ASSERT(list_empty(&op->pend_link));
 175
 176         ostate = object->state;
 177         smp_rmb();
 178
 179         op->state = FSCACHE_OP_ST_PENDING;
 180         flags = READ_ONCE(object->flags);
 181         if (unlikely(!(flags & BIT(FSCACHE_OBJECT_IS_LIVE)))) {
 182                 fscache_stat(&fscache_n_op_rejected);
 183                 op->cancel(op);
 184                 op->state = FSCACHE_OP_ST_CANCELLED;
 185                 ret = -ENOBUFS;
 186         } else if (unlikely(fscache_cache_is_broken(object))) {
 187                 op->cancel(op);
 188                 op->state = FSCACHE_OP_ST_CANCELLED;
 189                 ret = -EIO;
 190         } else if (flags & BIT(FSCACHE_OBJECT_IS_AVAILABLE)) {
 191                 op->object = object;
 192                 object->n_ops++;
 193                 object->n_exclusive++;  /* reads and writes must wait */
 194
 195                 if (object->n_in_progress > 0) {
 196                         atomic_inc(&op->usage);
 197                         list_add_tail(&op->pend_link, &object->pending_ops);
 198                         fscache_stat(&fscache_n_op_pend);
 199                 } else if (!list_empty(&object->pending_ops)) {
 200                         atomic_inc(&op->usage);
 201                         list_add_tail(&op->pend_link, &object->pending_ops);
 202                         fscache_stat(&fscache_n_op_pend);
 203                         fscache_start_operations(object);
 204                 } else {
 205                         ASSERTCMP(object->n_in_progress, ==, 0);
 206                         fscache_run_op(object, op);
 207                 }
 208
 209                 /* need to issue a new write op after this */
 210                 clear_bit(FSCACHE_OBJECT_PENDING_WRITE, &object->flags);
 211                 ret = 0;
 212         } else if (flags & BIT(FSCACHE_OBJECT_IS_LOOKED_UP)) {
 213                 op->object = object;
 214                 object->n_ops++;
 215                 object->n_exclusive++;  /* reads and writes must wait */
 216                 atomic_inc(&op->usage);
 217                 list_add_tail(&op->pend_link, &object->pending_ops);
 218                 fscache_stat(&fscache_n_op_pend);
 219                 ret = 0;
 220         } else if (flags & BIT(FSCACHE_OBJECT_KILLED_BY_CACHE)) {
 221                 op->cancel(op);
 222                 op->state = FSCACHE_OP_ST_CANCELLED;
 223                 ret = -ENOBUFS;
 224         } else {
 225                 fscache_report_unexpected_submission(object, op, ostate);
 226                 op->cancel(op);
 227                 op->state = FSCACHE_OP_ST_CANCELLED;
 228                 ret = -ENOBUFS;
 229         }
 230
 231         spin_unlock(&object->lock);
 232         return ret;
 233 }
 234
 235 /*
 236  * submit an operation for an object
 237  * - objects may be submitted only in the following states:
 238  *   - during object creation (write ops may be submitted)
 239  *   - whilst the object is active
 240  *   - after an I/O error incurred in one of the two above states (op rejected)
 241  * - this gets any extra refs it needs on an op
 242  */
 243 int fscache_submit_op(struct fscache_object *object,
 244                       struct fscache_operation *op)
 245 {
 246         const struct fscache_state *ostate;
 247         unsigned long flags;
 248         int ret;
 249
 250         _enter("{OBJ%x OP%x},{%u}",
 251                object->debug_id, op->debug_id, atomic_read(&op->usage));
 252
 253         trace_fscache_op(object->cookie, op, fscache_op_submit);
 254
 255         ASSERTCMP(op->state, ==, FSCACHE_OP_ST_INITIALISED);
 256         ASSERTCMP(atomic_read(&op->usage), >, 0);
 257
 258         spin_lock(&object->lock);
 259         ASSERTCMP(object->n_ops, >=, object->n_in_progress);
 260         ASSERTCMP(object->n_ops, >=, object->n_exclusive);
 261         ASSERT(list_empty(&op->pend_link));
 262
 263         ostate = object->state;
 264         smp_rmb();
 265
 266         op->state = FSCACHE_OP_ST_PENDING;
 267         flags = READ_ONCE(object->flags);
 268         if (unlikely(!(flags & BIT(FSCACHE_OBJECT_IS_LIVE)))) {
 269                 fscache_stat(&fscache_n_op_rejected);
 270                 op->cancel(op);
 271                 op->state = FSCACHE_OP_ST_CANCELLED;
 272                 ret = -ENOBUFS;
 273         } else if (unlikely(fscache_cache_is_broken(object))) {
 274                 op->cancel(op);
 275                 op->state = FSCACHE_OP_ST_CANCELLED;
 276                 ret = -EIO;
 277         } else if (flags & BIT(FSCACHE_OBJECT_IS_AVAILABLE)) {
 278                 op->object = object;
 279                 object->n_ops++;
 280
 281                 if (object->n_exclusive > 0) {
 282                         atomic_inc(&op->usage);
 283                         list_add_tail(&op->pend_link, &object->pending_ops);
 284                         fscache_stat(&fscache_n_op_pend);
 285                 } else if (!list_empty(&object->pending_ops)) {
 286                         atomic_inc(&op->usage);
 287                         list_add_tail(&op->pend_link, &object->pending_ops);
 288                         fscache_stat(&fscache_n_op_pend);
 289                         fscache_start_operations(object);
 290                 } else {
 291                         ASSERTCMP(object->n_exclusive, ==, 0);
 292                         fscache_run_op(object, op);
 293                 }
 294                 ret = 0;
 295         } else if (flags & BIT(FSCACHE_OBJECT_IS_LOOKED_UP)) {
 296                 op->object = object;
 297                 object->n_ops++;
 298                 atomic_inc(&op->usage);
 299                 list_add_tail(&op->pend_link, &object->pending_ops);
 300                 fscache_stat(&fscache_n_op_pend);
 301                 ret = 0;
 302         } else if (flags & BIT(FSCACHE_OBJECT_KILLED_BY_CACHE)) {
 303                 op->cancel(op);
 304                 op->state = FSCACHE_OP_ST_CANCELLED;
 305                 ret = -ENOBUFS;
 306         } else {
 307                 fscache_report_unexpected_submission(object, op, ostate);
 308                 ASSERT(!fscache_object_is_active(object));
 309                 op->cancel(op);
 310                 op->state = FSCACHE_OP_ST_CANCELLED;
 311                 ret = -ENOBUFS;
 312         }
 313
 314         spin_unlock(&object->lock);
 315         return ret;
 316 }
 317
 318 /*
 319  * queue an object for withdrawal on error, aborting all following asynchronous
 320  * operations
 321  */
 322 void fscache_abort_object(struct fscache_object *object)
 323 {
 324         _enter("{OBJ%x}", object->debug_id);
 325
 326         fscache_raise_event(object, FSCACHE_OBJECT_EV_ERROR);
 327 }
 328
 329 /*
 330  * Jump start the operation processing on an object.  The caller must hold
 331  * object->lock.
 332  */
 333 void fscache_start_operations(struct fscache_object *object)
 334 {
 335         struct fscache_operation *op;
 336         bool stop = false;
 337
 338         while (!list_empty(&object->pending_ops) && !stop) {
 339                 op = list_entry(object->pending_ops.next,
 340                                 struct fscache_operation, pend_link);
 341
 342                 if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags)) {
 343                         if (object->n_in_progress > 0)
 344                                 break;
 345                         stop = true;
 346                 }
 347                 list_del_init(&op->pend_link);
 348                 fscache_run_op(object, op);
 349
 350                 /* the pending queue was holding a ref on the object */
 351                 fscache_put_operation(op);
 352         }
 353
 354         ASSERTCMP(object->n_in_progress, <=, object->n_ops);
 355
 356         _debug("woke %d ops on OBJ%x",
 357                object->n_in_progress, object->debug_id);
 358 }
 359
 360 /*
 361  * cancel an operation that's pending on an object
 362  */
 363 int fscache_cancel_op(struct fscache_operation *op,
 364                       bool cancel_in_progress_op)
 365 {
 366         struct fscache_object *object = op->object;
 367         bool put = false;
 368         int ret;
 369
 370         _enter("OBJ%x OP%x}", op->object->debug_id, op->debug_id);
 371
 372         trace_fscache_op(object->cookie, op, fscache_op_cancel);
 373
 374         ASSERTCMP(op->state, >=, FSCACHE_OP_ST_PENDING);
 375         ASSERTCMP(op->state, !=, FSCACHE_OP_ST_CANCELLED);
 376         ASSERTCMP(atomic_read(&op->usage), >, 0);
 377
 378         spin_lock(&object->lock);
 379
 380         ret = -EBUSY;
 381         if (op->state == FSCACHE_OP_ST_PENDING) {
 382                 ASSERT(!list_empty(&op->pend_link));
 383                 list_del_init(&op->pend_link);
 384                 put = true;
 385
 386                 fscache_stat(&fscache_n_op_cancelled);
 387                 op->cancel(op);
 388                 op->state = FSCACHE_OP_ST_CANCELLED;
 389                 if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags))
 390                         object->n_exclusive--;
 391                 if (test_and_clear_bit(FSCACHE_OP_WAITING, &op->flags))
 392                         wake_up_bit(&op->flags, FSCACHE_OP_WAITING);
 393                 ret = 0;
 394         } else if (op->state == FSCACHE_OP_ST_IN_PROGRESS && cancel_in_progress_op) {
 395                 ASSERTCMP(object->n_in_progress, >, 0);
 396                 if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags))
 397                         object->n_exclusive--;
 398                 object->n_in_progress--;
 399                 if (object->n_in_progress == 0)
 400                         fscache_start_operations(object);
 401
 402                 fscache_stat(&fscache_n_op_cancelled);
 403                 op->cancel(op);
 404                 op->state = FSCACHE_OP_ST_CANCELLED;
 405                 if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags))
 406                         object->n_exclusive--;
 407                 if (test_and_clear_bit(FSCACHE_OP_WAITING, &op->flags))
 408                         wake_up_bit(&op->flags, FSCACHE_OP_WAITING);
 409                 ret = 0;
 410         }
 411
 412         if (put)
 413                 fscache_put_operation(op);
 414         spin_unlock(&object->lock);
 415         _leave(" = %d", ret);
 416         return ret;
 417 }
 418
 419 /*
 420  * Cancel all pending operations on an object
 421  */
 422 void fscache_cancel_all_ops(struct fscache_object *object)
 423 {
 424         struct fscache_operation *op;
 425
 426         _enter("OBJ%x", object->debug_id);
 427
 428         spin_lock(&object->lock);
 429
 430         while (!list_empty(&object->pending_ops)) {
 431                 op = list_entry(object->pending_ops.next,
 432                                 struct fscache_operation, pend_link);
 433                 fscache_stat(&fscache_n_op_cancelled);
 434                 list_del_init(&op->pend_link);
 435
 436                 trace_fscache_op(object->cookie, op, fscache_op_cancel_all);
 437
 438                 ASSERTCMP(op->state, ==, FSCACHE_OP_ST_PENDING);
 439                 op->cancel(op);
 440                 op->state = FSCACHE_OP_ST_CANCELLED;
 441
 442                 if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags))
 443                         object->n_exclusive--;
 444                 if (test_and_clear_bit(FSCACHE_OP_WAITING, &op->flags))
 445                         wake_up_bit(&op->flags, FSCACHE_OP_WAITING);
 446                 fscache_put_operation(op);
 447                 cond_resched_lock(&object->lock);
 448         }
 449
 450         spin_unlock(&object->lock);
 451         _leave("");
 452 }
 453
 454 /*
 455  * Record the completion or cancellation of an in-progress operation.
 456  */
 457 void fscache_op_complete(struct fscache_operation *op, bool cancelled)
 458 {
 459         struct fscache_object *object = op->object;
 460
 461         _enter("OBJ%x", object->debug_id);
 462
 463         ASSERTCMP(op->state, ==, FSCACHE_OP_ST_IN_PROGRESS);
 464         ASSERTCMP(object->n_in_progress, >, 0);
 465         ASSERTIFCMP(test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags),
 466                     object->n_exclusive, >, 0);
 467         ASSERTIFCMP(test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags),
 468                     object->n_in_progress, ==, 1);
 469
 470         spin_lock(&object->lock);
 471
 472         if (!cancelled) {
 473                 trace_fscache_op(object->cookie, op, fscache_op_completed);
 474                 op->state = FSCACHE_OP_ST_COMPLETE;
 475         } else {
 476                 op->cancel(op);
 477                 trace_fscache_op(object->cookie, op, fscache_op_cancelled);
 478                 op->state = FSCACHE_OP_ST_CANCELLED;
 479         }
 480
 481         if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags))
 482                 object->n_exclusive--;
 483         object->n_in_progress--;
 484         if (object->n_in_progress == 0)
 485                 fscache_start_operations(object);
 486
 487         spin_unlock(&object->lock);
 488         _leave("");
 489 }
 490 EXPORT_SYMBOL(fscache_op_complete);
 491
 492 /*
 493  * release an operation
 494  * - queues pending ops if this is the last in-progress op
 495  */
 496 void fscache_put_operation(struct fscache_operation *op)
 497 {
 498         struct fscache_object *object;
 499         struct fscache_cache *cache;
 500
 501         _enter("{OBJ%x OP%x,%d}",
 502                op->object->debug_id, op->debug_id, atomic_read(&op->usage));
 503
 504         ASSERTCMP(atomic_read(&op->usage), >, 0);
 505
 506         if (!atomic_dec_and_test(&op->usage))
 507                 return;
 508
 509         trace_fscache_op(op->object ? op->object->cookie : NULL, op, fscache_op_put);
 510
 511         _debug("PUT OP");
 512         ASSERTIFCMP(op->state != FSCACHE_OP_ST_INITIALISED &&
 513                     op->state != FSCACHE_OP_ST_COMPLETE,
 514                     op->state, ==, FSCACHE_OP_ST_CANCELLED);
 515
 516         fscache_stat(&fscache_n_op_release);
 517
 518         if (op->release) {
 519                 op->release(op);
 520                 op->release = NULL;
 521         }
 522         op->state = FSCACHE_OP_ST_DEAD;
 523
 524         object = op->object;
 525         if (likely(object)) {
 526                 if (test_bit(FSCACHE_OP_DEC_READ_CNT, &op->flags))
 527                         atomic_dec(&object->n_reads);
 528                 if (test_bit(FSCACHE_OP_UNUSE_COOKIE, &op->flags))
 529                         fscache_unuse_cookie(object);
 530
 531                 /* now... we may get called with the object spinlock held, so we
 532                  * complete the cleanup here only if we can immediately acquire the
 533                  * lock, and defer it otherwise */
 534                 if (!spin_trylock(&object->lock)) {
 535                         _debug("defer put");
 536                         fscache_stat(&fscache_n_op_deferred_release);
 537
 538                         cache = object->cache;
 539                         spin_lock(&cache->op_gc_list_lock);
 540                         list_add_tail(&op->pend_link, &cache->op_gc_list);
 541                         spin_unlock(&cache->op_gc_list_lock);
 542                         schedule_work(&cache->op_gc);
 543                         _leave(" [defer]");
 544                         return;
 545                 }
 546
 547                 ASSERTCMP(object->n_ops, >, 0);
 548                 object->n_ops--;
 549                 if (object->n_ops == 0)
 550                         fscache_raise_event(object, FSCACHE_OBJECT_EV_CLEARED);
 551
 552                 spin_unlock(&object->lock);
 553         }
 554
 555         kfree(op);
 556         _leave(" [done]");
 557 }
 558 EXPORT_SYMBOL(fscache_put_operation);
 559
 560 /*
 561  * garbage collect operations that have had their release deferred
 562  */
 563 void fscache_operation_gc(struct work_struct *work)
 564 {
 565         struct fscache_operation *op;
 566         struct fscache_object *object;
 567         struct fscache_cache *cache =
 568                 container_of(work, struct fscache_cache, op_gc);
 569         int count = 0;
 570
 571         _enter("");
 572
 573         do {
 574                 spin_lock(&cache->op_gc_list_lock);
 575                 if (list_empty(&cache->op_gc_list)) {
 576                         spin_unlock(&cache->op_gc_list_lock);
 577                         break;
 578                 }
 579
 580                 op = list_entry(cache->op_gc_list.next,
 581                                 struct fscache_operation, pend_link);
 582                 list_del(&op->pend_link);
 583                 spin_unlock(&cache->op_gc_list_lock);
 584
 585                 object = op->object;
 586                 trace_fscache_op(object->cookie, op, fscache_op_gc);
 587
 588                 spin_lock(&object->lock);
 589
 590                 _debug("GC DEFERRED REL OBJ%x OP%x",
 591                        object->debug_id, op->debug_id);
 592                 fscache_stat(&fscache_n_op_gc);
 593
 594                 ASSERTCMP(atomic_read(&op->usage), ==, 0);
 595                 ASSERTCMP(op->state, ==, FSCACHE_OP_ST_DEAD);
 596
 597                 ASSERTCMP(object->n_ops, >, 0);
 598                 object->n_ops--;
 599                 if (object->n_ops == 0)
 600                         fscache_raise_event(object, FSCACHE_OBJECT_EV_CLEARED);
 601
 602                 spin_unlock(&object->lock);
 603                 kfree(op);
 604
 605         } while (count++ < 20);
 606
 607         if (!list_empty(&cache->op_gc_list))
 608                 schedule_work(&cache->op_gc);
 609
 610         _leave("");
 611 }
 612
 613 /*
 614  * execute an operation using fs_op_wq to provide processing context -
 615  * the caller holds a ref to this object, so we don't need to hold one
 616  */
 617 void fscache_op_work_func(struct work_struct *work)
 618 {
 619         struct fscache_operation *op =
 620                 container_of(work, struct fscache_operation, work);
 621         unsigned long start;
 622
 623         _enter("{OBJ%x OP%x,%d}",
 624                op->object->debug_id, op->debug_id, atomic_read(&op->usage));
 625
 626         trace_fscache_op(op->object->cookie, op, fscache_op_work);
 627
 628         ASSERT(op->processor != NULL);
 629         start = jiffies;
 630         op->processor(op);
 631         fscache_hist(fscache_ops_histogram, start);
 632         fscache_put_operation(op);
 633
 634         _leave("");
 635 }