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   1 /* Cache page management and data I/O routines
   2  *
   3  * Copyright (C) 2004-2008 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
  12 #define FSCACHE_DEBUG_LEVEL PAGE
  13 #include <linux/module.h>
  14 #include <linux/fscache-cache.h>
  15 #include <linux/buffer_head.h>
  16 #include <linux/pagevec.h>
  17 #include "internal.h"
  18
  19 /*
  20  * check to see if a page is being written to the cache
  21  */
  22 bool __fscache_check_page_write(struct fscache_cookie *cookie, struct page *page)
  23 {
  24         void *val;
  25
  26         rcu_read_lock();
  27         val = radix_tree_lookup(&cookie->stores, page->index);
  28         rcu_read_unlock();
  29
  30         return val != NULL;
  31 }
  32 EXPORT_SYMBOL(__fscache_check_page_write);
  33
  34 /*
  35  * wait for a page to finish being written to the cache
  36  */
  37 void __fscache_wait_on_page_write(struct fscache_cookie *cookie, struct page *page)
  38 {
  39         wait_queue_head_t *wq = bit_waitqueue(&cookie->flags, 0);
  40
  41         wait_event(*wq, !__fscache_check_page_write(cookie, page));
  42 }
  43 EXPORT_SYMBOL(__fscache_wait_on_page_write);
  44
  45 /*
  46  * note that a page has finished being written to the cache
  47  */
  48 static void fscache_end_page_write(struct fscache_object *object,
  49                                    struct page *page)
  50 {
  51         struct fscache_cookie *cookie;
  52         struct page *xpage = NULL;
  53
  54         spin_lock(&object->lock);
  55         cookie = object->cookie;
  56         if (cookie) {
  57                 /* delete the page from the tree if it is now no longer
  58                  * pending */
  59                 spin_lock(&cookie->stores_lock);
  60                 fscache_stat(&fscache_n_store_radix_deletes);
  61                 xpage = radix_tree_delete(&cookie->stores, page->index);
  62                 spin_unlock(&cookie->stores_lock);
  63                 wake_up_bit(&cookie->flags, 0);
  64         }
  65         spin_unlock(&object->lock);
  66         if (xpage)
  67                 page_cache_release(xpage);
  68 }
  69
  70 /*
  71  * actually apply the changed attributes to a cache object
  72  */
  73 static void fscache_attr_changed_op(struct fscache_operation *op)
  74 {
  75         struct fscache_object *object = op->object;
  76         int ret;
  77
  78         _enter("{OBJ%x OP%x}", object->debug_id, op->debug_id);
  79
  80         fscache_stat(&fscache_n_attr_changed_calls);
  81
  82         if (fscache_object_is_active(object)) {
  83                 fscache_set_op_state(op, "CallFS");
  84                 fscache_stat(&fscache_n_cop_attr_changed);
  85                 ret = object->cache->ops->attr_changed(object);
  86                 fscache_stat_d(&fscache_n_cop_attr_changed);
  87                 fscache_set_op_state(op, "Done");
  88                 if (ret < 0)
  89                         fscache_abort_object(object);
  90         }
  91
  92         _leave("");
  93 }
  94
  95 /*
  96  * notification that the attributes on an object have changed
  97  */
  98 int __fscache_attr_changed(struct fscache_cookie *cookie)
  99 {
 100         struct fscache_operation *op;
 101         struct fscache_object *object;
 102
 103         _enter("%p", cookie);
 104
 105         ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX);
 106
 107         fscache_stat(&fscache_n_attr_changed);
 108
 109         op = kzalloc(sizeof(*op), GFP_KERNEL);
 110         if (!op) {
 111                 fscache_stat(&fscache_n_attr_changed_nomem);
 112                 _leave(" = -ENOMEM");
 113                 return -ENOMEM;
 114         }
 115
 116         fscache_operation_init(op, NULL);
 117         fscache_operation_init_slow(op, fscache_attr_changed_op);
 118         op->flags = FSCACHE_OP_SLOW | (1 << FSCACHE_OP_EXCLUSIVE);
 119         fscache_set_op_name(op, "Attr");
 120
 121         spin_lock(&cookie->lock);
 122
 123         if (hlist_empty(&cookie->backing_objects))
 124                 goto nobufs;
 125         object = hlist_entry(cookie->backing_objects.first,
 126                              struct fscache_object, cookie_link);
 127
 128         if (fscache_submit_exclusive_op(object, op) < 0)
 129                 goto nobufs;
 130         spin_unlock(&cookie->lock);
 131         fscache_stat(&fscache_n_attr_changed_ok);
 132         fscache_put_operation(op);
 133         _leave(" = 0");
 134         return 0;
 135
 136 nobufs:
 137         spin_unlock(&cookie->lock);
 138         kfree(op);
 139         fscache_stat(&fscache_n_attr_changed_nobufs);
 140         _leave(" = %d", -ENOBUFS);
 141         return -ENOBUFS;
 142 }
 143 EXPORT_SYMBOL(__fscache_attr_changed);
 144
 145 /*
 146  * handle secondary execution given to a retrieval op on behalf of the
 147  * cache
 148  */
 149 static void fscache_retrieval_work(struct work_struct *work)
 150 {
 151         struct fscache_retrieval *op =
 152                 container_of(work, struct fscache_retrieval, op.fast_work);
 153         unsigned long start;
 154
 155         _enter("{OP%x}", op->op.debug_id);
 156
 157         start = jiffies;
 158         op->op.processor(&op->op);
 159         fscache_hist(fscache_ops_histogram, start);
 160         fscache_put_operation(&op->op);
 161 }
 162
 163 /*
 164  * release a retrieval op reference
 165  */
 166 static void fscache_release_retrieval_op(struct fscache_operation *_op)
 167 {
 168         struct fscache_retrieval *op =
 169                 container_of(_op, struct fscache_retrieval, op);
 170
 171         _enter("{OP%x}", op->op.debug_id);
 172
 173         fscache_hist(fscache_retrieval_histogram, op->start_time);
 174         if (op->context)
 175                 fscache_put_context(op->op.object->cookie, op->context);
 176
 177         _leave("");
 178 }
 179
 180 /*
 181  * allocate a retrieval op
 182  */
 183 static struct fscache_retrieval *fscache_alloc_retrieval(
 184         struct address_space *mapping,
 185         fscache_rw_complete_t end_io_func,
 186         void *context)
 187 {
 188         struct fscache_retrieval *op;
 189
 190         /* allocate a retrieval operation and attempt to submit it */
 191         op = kzalloc(sizeof(*op), GFP_NOIO);
 192         if (!op) {
 193                 fscache_stat(&fscache_n_retrievals_nomem);
 194                 return NULL;
 195         }
 196
 197         fscache_operation_init(&op->op, fscache_release_retrieval_op);
 198         op->op.flags    = FSCACHE_OP_MYTHREAD | (1 << FSCACHE_OP_WAITING);
 199         op->mapping     = mapping;
 200         op->end_io_func = end_io_func;
 201         op->context     = context;
 202         op->start_time  = jiffies;
 203         INIT_WORK(&op->op.fast_work, fscache_retrieval_work);
 204         INIT_LIST_HEAD(&op->to_do);
 205         fscache_set_op_name(&op->op, "Retr");
 206         return op;
 207 }
 208
 209 /*
 210  * wait for a deferred lookup to complete
 211  */
 212 static int fscache_wait_for_deferred_lookup(struct fscache_cookie *cookie)
 213 {
 214         unsigned long jif;
 215
 216         _enter("");
 217
 218         if (!test_bit(FSCACHE_COOKIE_LOOKING_UP, &cookie->flags)) {
 219                 _leave(" = 0 [imm]");
 220                 return 0;
 221         }
 222
 223         fscache_stat(&fscache_n_retrievals_wait);
 224
 225         jif = jiffies;
 226         if (wait_on_bit(&cookie->flags, FSCACHE_COOKIE_LOOKING_UP,
 227                         fscache_wait_bit_interruptible,
 228                         TASK_INTERRUPTIBLE) != 0) {
 229                 fscache_stat(&fscache_n_retrievals_intr);
 230                 _leave(" = -ERESTARTSYS");
 231                 return -ERESTARTSYS;
 232         }
 233
 234         ASSERT(!test_bit(FSCACHE_COOKIE_LOOKING_UP, &cookie->flags));
 235
 236         smp_rmb();
 237         fscache_hist(fscache_retrieval_delay_histogram, jif);
 238         _leave(" = 0 [dly]");
 239         return 0;
 240 }
 241
 242 /*
 243  * read a page from the cache or allocate a block in which to store it
 244  * - we return:
 245  *   -ENOMEM    - out of memory, nothing done
 246  *   -ERESTARTSYS - interrupted
 247  *   -ENOBUFS   - no backing object available in which to cache the block
 248  *   -ENODATA   - no data available in the backing object for this block
 249  *   0          - dispatched a read - it'll call end_io_func() when finished
 250  */
 251 int __fscache_read_or_alloc_page(struct fscache_cookie *cookie,
 252                                  struct page *page,
 253                                  fscache_rw_complete_t end_io_func,
 254                                  void *context,
 255                                  gfp_t gfp)
 256 {
 257         struct fscache_retrieval *op;
 258         struct fscache_object *object;
 259         int ret;
 260
 261         _enter("%p,%p,,,", cookie, page);
 262
 263         fscache_stat(&fscache_n_retrievals);
 264
 265         if (hlist_empty(&cookie->backing_objects))
 266                 goto nobufs;
 267
 268         ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX);
 269         ASSERTCMP(page, !=, NULL);
 270
 271         if (fscache_wait_for_deferred_lookup(cookie) < 0)
 272                 return -ERESTARTSYS;
 273
 274         op = fscache_alloc_retrieval(page->mapping, end_io_func, context);
 275         if (!op) {
 276                 _leave(" = -ENOMEM");
 277                 return -ENOMEM;
 278         }
 279         fscache_set_op_name(&op->op, "RetrRA1");
 280
 281         spin_lock(&cookie->lock);
 282
 283         if (hlist_empty(&cookie->backing_objects))
 284                 goto nobufs_unlock;
 285         object = hlist_entry(cookie->backing_objects.first,
 286                              struct fscache_object, cookie_link);
 287
 288         ASSERTCMP(object->state, >, FSCACHE_OBJECT_LOOKING_UP);
 289
 290         atomic_inc(&object->n_reads);
 291         set_bit(FSCACHE_OP_DEC_READ_CNT, &op->op.flags);
 292
 293         if (fscache_submit_op(object, &op->op) < 0)
 294                 goto nobufs_unlock;
 295         spin_unlock(&cookie->lock);
 296
 297         fscache_stat(&fscache_n_retrieval_ops);
 298
 299         /* pin the netfs read context in case we need to do the actual netfs
 300          * read because we've encountered a cache read failure */
 301         fscache_get_context(object->cookie, op->context);
 302
 303         /* we wait for the operation to become active, and then process it
 304          * *here*, in this thread, and not in the thread pool */
 305         if (test_bit(FSCACHE_OP_WAITING, &op->op.flags)) {
 306                 _debug(">>> WT");
 307                 fscache_stat(&fscache_n_retrieval_op_waits);
 308                 if (wait_on_bit(&op->op.flags, FSCACHE_OP_WAITING,
 309                                 fscache_wait_bit_interruptible,
 310                                 TASK_INTERRUPTIBLE) < 0) {
 311                         ret = fscache_cancel_op(&op->op);
 312                         if (ret == 0) {
 313                                 ret = -ERESTARTSYS;
 314                                 goto error;
 315                         }
 316
 317                         /* it's been removed from the pending queue by another
 318                          * party, so we should get to run shortly */
 319                         wait_on_bit(&op->op.flags, FSCACHE_OP_WAITING,
 320                                     fscache_wait_bit, TASK_UNINTERRUPTIBLE);
 321                 }
 322                 _debug("<<< GO");
 323         }
 324
 325         /* ask the cache to honour the operation */
 326         if (test_bit(FSCACHE_COOKIE_NO_DATA_YET, &object->cookie->flags)) {
 327                 fscache_stat(&fscache_n_cop_allocate_page);
 328                 ret = object->cache->ops->allocate_page(op, page, gfp);
 329                 fscache_stat_d(&fscache_n_cop_allocate_page);
 330                 if (ret == 0)
 331                         ret = -ENODATA;
 332         } else {
 333                 fscache_stat(&fscache_n_cop_read_or_alloc_page);
 334                 ret = object->cache->ops->read_or_alloc_page(op, page, gfp);
 335                 fscache_stat_d(&fscache_n_cop_read_or_alloc_page);
 336         }
 337
 338 error:
 339         if (ret == -ENOMEM)
 340                 fscache_stat(&fscache_n_retrievals_nomem);
 341         else if (ret == -ERESTARTSYS)
 342                 fscache_stat(&fscache_n_retrievals_intr);
 343         else if (ret == -ENODATA)
 344                 fscache_stat(&fscache_n_retrievals_nodata);
 345         else if (ret < 0)
 346                 fscache_stat(&fscache_n_retrievals_nobufs);
 347         else
 348                 fscache_stat(&fscache_n_retrievals_ok);
 349
 350         fscache_put_retrieval(op);
 351         _leave(" = %d", ret);
 352         return ret;
 353
 354 nobufs_unlock:
 355         spin_unlock(&cookie->lock);
 356         kfree(op);
 357 nobufs:
 358         fscache_stat(&fscache_n_retrievals_nobufs);
 359         _leave(" = -ENOBUFS");
 360         return -ENOBUFS;
 361 }
 362 EXPORT_SYMBOL(__fscache_read_or_alloc_page);
 363
 364 /*
 365  * read a list of page from the cache or allocate a block in which to store
 366  * them
 367  * - we return:
 368  *   -ENOMEM    - out of memory, some pages may be being read
 369  *   -ERESTARTSYS - interrupted, some pages may be being read
 370  *   -ENOBUFS   - no backing object or space available in which to cache any
 371  *                pages not being read
 372  *   -ENODATA   - no data available in the backing object for some or all of
 373  *                the pages
 374  *   0          - dispatched a read on all pages
 375  *
 376  * end_io_func() will be called for each page read from the cache as it is
 377  * finishes being read
 378  *
 379  * any pages for which a read is dispatched will be removed from pages and
 380  * nr_pages
 381  */
 382 int __fscache_read_or_alloc_pages(struct fscache_cookie *cookie,
 383                                   struct address_space *mapping,
 384                                   struct list_head *pages,
 385                                   unsigned *nr_pages,
 386                                   fscache_rw_complete_t end_io_func,
 387                                   void *context,
 388                                   gfp_t gfp)
 389 {
 390         struct fscache_retrieval *op;
 391         struct fscache_object *object;
 392         int ret;
 393
 394         _enter("%p,,%d,,,", cookie, *nr_pages);
 395
 396         fscache_stat(&fscache_n_retrievals);
 397
 398         if (hlist_empty(&cookie->backing_objects))
 399                 goto nobufs;
 400
 401         ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX);
 402         ASSERTCMP(*nr_pages, >, 0);
 403         ASSERT(!list_empty(pages));
 404
 405         if (fscache_wait_for_deferred_lookup(cookie) < 0)
 406                 return -ERESTARTSYS;
 407
 408         op = fscache_alloc_retrieval(mapping, end_io_func, context);
 409         if (!op)
 410                 return -ENOMEM;
 411         fscache_set_op_name(&op->op, "RetrRAN");
 412
 413         spin_lock(&cookie->lock);
 414
 415         if (hlist_empty(&cookie->backing_objects))
 416                 goto nobufs_unlock;
 417         object = hlist_entry(cookie->backing_objects.first,
 418                              struct fscache_object, cookie_link);
 419
 420         atomic_inc(&object->n_reads);
 421         set_bit(FSCACHE_OP_DEC_READ_CNT, &op->op.flags);
 422
 423         if (fscache_submit_op(object, &op->op) < 0)
 424                 goto nobufs_unlock;
 425         spin_unlock(&cookie->lock);
 426
 427         fscache_stat(&fscache_n_retrieval_ops);
 428
 429         /* pin the netfs read context in case we need to do the actual netfs
 430          * read because we've encountered a cache read failure */
 431         fscache_get_context(object->cookie, op->context);
 432
 433         /* we wait for the operation to become active, and then process it
 434          * *here*, in this thread, and not in the thread pool */
 435         if (test_bit(FSCACHE_OP_WAITING, &op->op.flags)) {
 436                 _debug(">>> WT");
 437                 fscache_stat(&fscache_n_retrieval_op_waits);
 438                 if (wait_on_bit(&op->op.flags, FSCACHE_OP_WAITING,
 439                                 fscache_wait_bit_interruptible,
 440                                 TASK_INTERRUPTIBLE) < 0) {
 441                         ret = fscache_cancel_op(&op->op);
 442                         if (ret == 0) {
 443                                 ret = -ERESTARTSYS;
 444                                 goto error;
 445                         }
 446
 447                         /* it's been removed from the pending queue by another
 448                          * party, so we should get to run shortly */
 449                         wait_on_bit(&op->op.flags, FSCACHE_OP_WAITING,
 450                                     fscache_wait_bit, TASK_UNINTERRUPTIBLE);
 451                 }
 452                 _debug("<<< GO");
 453         }
 454
 455         /* ask the cache to honour the operation */
 456         if (test_bit(FSCACHE_COOKIE_NO_DATA_YET, &object->cookie->flags)) {
 457                 fscache_stat(&fscache_n_cop_allocate_pages);
 458                 ret = object->cache->ops->allocate_pages(
 459                         op, pages, nr_pages, gfp);
 460                 fscache_stat_d(&fscache_n_cop_allocate_pages);
 461         } else {
 462                 fscache_stat(&fscache_n_cop_read_or_alloc_pages);
 463                 ret = object->cache->ops->read_or_alloc_pages(
 464                         op, pages, nr_pages, gfp);
 465                 fscache_stat_d(&fscache_n_cop_read_or_alloc_pages);
 466         }
 467
 468 error:
 469         if (ret == -ENOMEM)
 470                 fscache_stat(&fscache_n_retrievals_nomem);
 471         else if (ret == -ERESTARTSYS)
 472                 fscache_stat(&fscache_n_retrievals_intr);
 473         else if (ret == -ENODATA)
 474                 fscache_stat(&fscache_n_retrievals_nodata);
 475         else if (ret < 0)
 476                 fscache_stat(&fscache_n_retrievals_nobufs);
 477         else
 478                 fscache_stat(&fscache_n_retrievals_ok);
 479
 480         fscache_put_retrieval(op);
 481         _leave(" = %d", ret);
 482         return ret;
 483
 484 nobufs_unlock:
 485         spin_unlock(&cookie->lock);
 486         kfree(op);
 487 nobufs:
 488         fscache_stat(&fscache_n_retrievals_nobufs);
 489         _leave(" = -ENOBUFS");
 490         return -ENOBUFS;
 491 }
 492 EXPORT_SYMBOL(__fscache_read_or_alloc_pages);
 493
 494 /*
 495  * allocate a block in the cache on which to store a page
 496  * - we return:
 497  *   -ENOMEM    - out of memory, nothing done
 498  *   -ERESTARTSYS - interrupted
 499  *   -ENOBUFS   - no backing object available in which to cache the block
 500  *   0          - block allocated
 501  */
 502 int __fscache_alloc_page(struct fscache_cookie *cookie,
 503                          struct page *page,
 504                          gfp_t gfp)
 505 {
 506         struct fscache_retrieval *op;
 507         struct fscache_object *object;
 508         int ret;
 509
 510         _enter("%p,%p,,,", cookie, page);
 511
 512         fscache_stat(&fscache_n_allocs);
 513
 514         if (hlist_empty(&cookie->backing_objects))
 515                 goto nobufs;
 516
 517         ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX);
 518         ASSERTCMP(page, !=, NULL);
 519
 520         if (fscache_wait_for_deferred_lookup(cookie) < 0)
 521                 return -ERESTARTSYS;
 522
 523         op = fscache_alloc_retrieval(page->mapping, NULL, NULL);
 524         if (!op)
 525                 return -ENOMEM;
 526         fscache_set_op_name(&op->op, "RetrAL1");
 527
 528         spin_lock(&cookie->lock);
 529
 530         if (hlist_empty(&cookie->backing_objects))
 531                 goto nobufs_unlock;
 532         object = hlist_entry(cookie->backing_objects.first,
 533                              struct fscache_object, cookie_link);
 534
 535         if (fscache_submit_op(object, &op->op) < 0)
 536                 goto nobufs_unlock;
 537         spin_unlock(&cookie->lock);
 538
 539         fscache_stat(&fscache_n_alloc_ops);
 540
 541         if (test_bit(FSCACHE_OP_WAITING, &op->op.flags)) {
 542                 _debug(">>> WT");
 543                 fscache_stat(&fscache_n_alloc_op_waits);
 544                 if (wait_on_bit(&op->op.flags, FSCACHE_OP_WAITING,
 545                                 fscache_wait_bit_interruptible,
 546                                 TASK_INTERRUPTIBLE) < 0) {
 547                         ret = fscache_cancel_op(&op->op);
 548                         if (ret == 0) {
 549                                 ret = -ERESTARTSYS;
 550                                 goto error;
 551                         }
 552
 553                         /* it's been removed from the pending queue by another
 554                          * party, so we should get to run shortly */
 555                         wait_on_bit(&op->op.flags, FSCACHE_OP_WAITING,
 556                                     fscache_wait_bit, TASK_UNINTERRUPTIBLE);
 557                 }
 558                 _debug("<<< GO");
 559         }
 560
 561         /* ask the cache to honour the operation */
 562         fscache_stat(&fscache_n_cop_allocate_page);
 563         ret = object->cache->ops->allocate_page(op, page, gfp);
 564         fscache_stat_d(&fscache_n_cop_allocate_page);
 565
 566 error:
 567         if (ret == -ERESTARTSYS)
 568                 fscache_stat(&fscache_n_allocs_intr);
 569         else if (ret < 0)
 570                 fscache_stat(&fscache_n_allocs_nobufs);
 571         else
 572                 fscache_stat(&fscache_n_allocs_ok);
 573
 574         fscache_put_retrieval(op);
 575         _leave(" = %d", ret);
 576         return ret;
 577
 578 nobufs_unlock:
 579         spin_unlock(&cookie->lock);
 580         kfree(op);
 581 nobufs:
 582         fscache_stat(&fscache_n_allocs_nobufs);
 583         _leave(" = -ENOBUFS");
 584         return -ENOBUFS;
 585 }
 586 EXPORT_SYMBOL(__fscache_alloc_page);
 587
 588 /*
 589  * release a write op reference
 590  */
 591 static void fscache_release_write_op(struct fscache_operation *_op)
 592 {
 593         _enter("{OP%x}", _op->debug_id);
 594 }
 595
 596 /*
 597  * perform the background storage of a page into the cache
 598  */
 599 static void fscache_write_op(struct fscache_operation *_op)
 600 {
 601         struct fscache_storage *op =
 602                 container_of(_op, struct fscache_storage, op);
 603         struct fscache_object *object = op->op.object;
 604         struct fscache_cookie *cookie;
 605         struct page *page;
 606         unsigned n;
 607         void *results[1];
 608         int ret;
 609
 610         _enter("{OP%x,%d}", op->op.debug_id, atomic_read(&op->op.usage));
 611
 612         fscache_set_op_state(&op->op, "GetPage");
 613
 614         spin_lock(&object->lock);
 615         cookie = object->cookie;
 616
 617         if (!fscache_object_is_active(object) || !cookie) {
 618                 spin_unlock(&object->lock);
 619                 _leave("");
 620                 return;
 621         }
 622
 623         spin_lock(&cookie->stores_lock);
 624
 625         fscache_stat(&fscache_n_store_calls);
 626
 627         /* find a page to store */
 628         page = NULL;
 629         n = radix_tree_gang_lookup_tag(&cookie->stores, results, 0, 1,
 630                                        FSCACHE_COOKIE_PENDING_TAG);
 631         if (n != 1)
 632                 goto superseded;
 633         page = results[0];
 634         _debug("gang %d [%lx]", n, page->index);
 635         if (page->index > op->store_limit) {
 636                 fscache_stat(&fscache_n_store_pages_over_limit);
 637                 goto superseded;
 638         }
 639
 640         radix_tree_tag_clear(&cookie->stores, page->index,
 641                              FSCACHE_COOKIE_PENDING_TAG);
 642
 643         spin_unlock(&cookie->stores_lock);
 644         spin_unlock(&object->lock);
 645
 646         if (page) {
 647                 fscache_set_op_state(&op->op, "Store");
 648                 fscache_stat(&fscache_n_store_pages);
 649                 fscache_stat(&fscache_n_cop_write_page);
 650                 ret = object->cache->ops->write_page(op, page);
 651                 fscache_stat_d(&fscache_n_cop_write_page);
 652                 fscache_set_op_state(&op->op, "EndWrite");
 653                 fscache_end_page_write(object, page);
 654                 if (ret < 0) {
 655                         fscache_set_op_state(&op->op, "Abort");
 656                         fscache_abort_object(object);
 657                 } else {
 658                         fscache_enqueue_operation(&op->op);
 659                 }
 660         }
 661
 662         _leave("");
 663         return;
 664
 665 superseded:
 666         /* this writer is going away and there aren't any more things to
 667          * write */
 668         _debug("cease");
 669         spin_unlock(&cookie->stores_lock);
 670         clear_bit(FSCACHE_OBJECT_PENDING_WRITE, &object->flags);
 671         spin_unlock(&object->lock);
 672         _leave("");
 673 }
 674
 675 /*
 676  * request a page be stored in the cache
 677  * - returns:
 678  *   -ENOMEM    - out of memory, nothing done
 679  *   -ENOBUFS   - no backing object available in which to cache the page
 680  *   0          - dispatched a write - it'll call end_io_func() when finished
 681  *
 682  * if the cookie still has a backing object at this point, that object can be
 683  * in one of a few states with respect to storage processing:
 684  *
 685  *  (1) negative lookup, object not yet created (FSCACHE_COOKIE_CREATING is
 686  *      set)
 687  *
 688  *      (a) no writes yet (set FSCACHE_COOKIE_PENDING_FILL and queue deferred
 689  *          fill op)
 690  *
 691  *      (b) writes deferred till post-creation (mark page for writing and
 692  *          return immediately)
 693  *
 694  *  (2) negative lookup, object created, initial fill being made from netfs
 695  *      (FSCACHE_COOKIE_INITIAL_FILL is set)
 696  *
 697  *      (a) fill point not yet reached this page (mark page for writing and
 698  *          return)
 699  *
 700  *      (b) fill point passed this page (queue op to store this page)
 701  *
 702  *  (3) object extant (queue op to store this page)
 703  *
 704  * any other state is invalid
 705  */
 706 int __fscache_write_page(struct fscache_cookie *cookie,
 707                          struct page *page,
 708                          gfp_t gfp)
 709 {
 710         struct fscache_storage *op;
 711         struct fscache_object *object;
 712         int ret;
 713
 714         _enter("%p,%x,", cookie, (u32) page->flags);
 715
 716         ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX);
 717         ASSERT(PageFsCache(page));
 718
 719         fscache_stat(&fscache_n_stores);
 720
 721         op = kzalloc(sizeof(*op), GFP_NOIO);
 722         if (!op)
 723                 goto nomem;
 724
 725         fscache_operation_init(&op->op, fscache_release_write_op);
 726         fscache_operation_init_slow(&op->op, fscache_write_op);
 727         op->op.flags = FSCACHE_OP_SLOW | (1 << FSCACHE_OP_WAITING);
 728         fscache_set_op_name(&op->op, "Write1");
 729
 730         ret = radix_tree_preload(gfp & ~__GFP_HIGHMEM);
 731         if (ret < 0)
 732                 goto nomem_free;
 733
 734         ret = -ENOBUFS;
 735         spin_lock(&cookie->lock);
 736
 737         if (hlist_empty(&cookie->backing_objects))
 738                 goto nobufs;
 739         object = hlist_entry(cookie->backing_objects.first,
 740                              struct fscache_object, cookie_link);
 741         if (test_bit(FSCACHE_IOERROR, &object->cache->flags))
 742                 goto nobufs;
 743
 744         /* add the page to the pending-storage radix tree on the backing
 745          * object */
 746         spin_lock(&object->lock);
 747         spin_lock(&cookie->stores_lock);
 748
 749         _debug("store limit %llx", (unsigned long long) object->store_limit);
 750
 751         ret = radix_tree_insert(&cookie->stores, page->index, page);
 752         if (ret < 0) {
 753                 if (ret == -EEXIST)
 754                         goto already_queued;
 755                 _debug("insert failed %d", ret);
 756                 goto nobufs_unlock_obj;
 757         }
 758
 759         radix_tree_tag_set(&cookie->stores, page->index,
 760                            FSCACHE_COOKIE_PENDING_TAG);
 761         page_cache_get(page);
 762
 763         /* we only want one writer at a time, but we do need to queue new
 764          * writers after exclusive ops */
 765         if (test_and_set_bit(FSCACHE_OBJECT_PENDING_WRITE, &object->flags))
 766                 goto already_pending;
 767
 768         spin_unlock(&cookie->stores_lock);
 769         spin_unlock(&object->lock);
 770
 771         op->op.debug_id = atomic_inc_return(&fscache_op_debug_id);
 772         op->store_limit = object->store_limit;
 773
 774         if (fscache_submit_op(object, &op->op) < 0)
 775                 goto submit_failed;
 776
 777         spin_unlock(&cookie->lock);
 778         radix_tree_preload_end();
 779         fscache_stat(&fscache_n_store_ops);
 780         fscache_stat(&fscache_n_stores_ok);
 781
 782         /* the slow work queue now carries its own ref on the object */
 783         fscache_put_operation(&op->op);
 784         _leave(" = 0");
 785         return 0;
 786
 787 already_queued:
 788         fscache_stat(&fscache_n_stores_again);
 789 already_pending:
 790         spin_unlock(&cookie->stores_lock);
 791         spin_unlock(&object->lock);
 792         spin_unlock(&cookie->lock);
 793         radix_tree_preload_end();
 794         kfree(op);
 795         fscache_stat(&fscache_n_stores_ok);
 796         _leave(" = 0");
 797         return 0;
 798
 799 submit_failed:
 800         spin_lock(&cookie->stores_lock);
 801         radix_tree_delete(&cookie->stores, page->index);
 802         spin_unlock(&cookie->stores_lock);
 803         page_cache_release(page);
 804         ret = -ENOBUFS;
 805         goto nobufs;
 806
 807 nobufs_unlock_obj:
 808         spin_unlock(&object->lock);
 809 nobufs:
 810         spin_unlock(&cookie->lock);
 811         radix_tree_preload_end();
 812         kfree(op);
 813         fscache_stat(&fscache_n_stores_nobufs);
 814         _leave(" = -ENOBUFS");
 815         return -ENOBUFS;
 816
 817 nomem_free:
 818         kfree(op);
 819 nomem:
 820         fscache_stat(&fscache_n_stores_oom);
 821         _leave(" = -ENOMEM");
 822         return -ENOMEM;
 823 }
 824 EXPORT_SYMBOL(__fscache_write_page);
 825
 826 /*
 827  * remove a page from the cache
 828  */
 829 void __fscache_uncache_page(struct fscache_cookie *cookie, struct page *page)
 830 {
 831         struct fscache_object *object;
 832
 833         _enter(",%p", page);
 834
 835         ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX);
 836         ASSERTCMP(page, !=, NULL);
 837
 838         fscache_stat(&fscache_n_uncaches);
 839
 840         /* cache withdrawal may beat us to it */
 841         if (!PageFsCache(page))
 842                 goto done;
 843
 844         /* get the object */
 845         spin_lock(&cookie->lock);
 846
 847         if (hlist_empty(&cookie->backing_objects)) {
 848                 ClearPageFsCache(page);
 849                 goto done_unlock;
 850         }
 851
 852         object = hlist_entry(cookie->backing_objects.first,
 853                              struct fscache_object, cookie_link);
 854
 855         /* there might now be stuff on disk we could read */
 856         clear_bit(FSCACHE_COOKIE_NO_DATA_YET, &cookie->flags);
 857
 858         /* only invoke the cache backend if we managed to mark the page
 859          * uncached here; this deals with synchronisation vs withdrawal */
 860         if (TestClearPageFsCache(page) &&
 861             object->cache->ops->uncache_page) {
 862                 /* the cache backend releases the cookie lock */
 863                 fscache_stat(&fscache_n_cop_uncache_page);
 864                 object->cache->ops->uncache_page(object, page);
 865                 fscache_stat_d(&fscache_n_cop_uncache_page);
 866                 goto done;
 867         }
 868
 869 done_unlock:
 870         spin_unlock(&cookie->lock);
 871 done:
 872         _leave("");
 873 }
 874 EXPORT_SYMBOL(__fscache_uncache_page);
 875
 876 /**
 877  * fscache_mark_pages_cached - Mark pages as being cached
 878  * @op: The retrieval op pages are being marked for
 879  * @pagevec: The pages to be marked
 880  *
 881  * Mark a bunch of netfs pages as being cached.  After this is called,
 882  * the netfs must call fscache_uncache_page() to remove the mark.
 883  */
 884 void fscache_mark_pages_cached(struct fscache_retrieval *op,
 885                                struct pagevec *pagevec)
 886 {
 887         struct fscache_cookie *cookie = op->op.object->cookie;
 888         unsigned long loop;
 889
 890 #ifdef CONFIG_FSCACHE_STATS
 891         atomic_add(pagevec->nr, &fscache_n_marks);
 892 #endif
 893
 894         for (loop = 0; loop < pagevec->nr; loop++) {
 895                 struct page *page = pagevec->pages[loop];
 896
 897                 _debug("- mark %p{%lx}", page, page->index);
 898                 if (TestSetPageFsCache(page)) {
 899                         static bool once_only;
 900                         if (!once_only) {
 901                                 once_only = true;
 902                                 printk(KERN_WARNING "FS-Cache:"
 903                                        " Cookie type %s marked page %lx"
 904                                        " multiple times\n",
 905                                        cookie->def->name, page->index);
 906                         }
 907                 }
 908         }
 909
 910         if (cookie->def->mark_pages_cached)
 911                 cookie->def->mark_pages_cached(cookie->netfs_data,
 912                                                op->mapping, pagevec);
 913         pagevec_reinit(pagevec);
 914 }
 915 EXPORT_SYMBOL(fscache_mark_pages_cached);