1/* General filesystem caching interface 2 * 3 * Copyright (C) 2004-2007 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 * NOTE!!! See: 12 * 13 * Documentation/filesystems/caching/netfs-api.txt 14 * 15 * for a description of the network filesystem interface declared here. 16 */ 17 18#ifndef _LINUX_FSCACHE_H 19#define _LINUX_FSCACHE_H 20 21#include <linux/fs.h> 22#include <linux/list.h> 23#include <linux/pagemap.h> 24#include <linux/pagevec.h> 25 26#if defined(CONFIG_FSCACHE) || defined(CONFIG_FSCACHE_MODULE) 27#define fscache_available() (1) 28#define fscache_cookie_valid(cookie) (cookie) 29#else 30#define fscache_available() (0) 31#define fscache_cookie_valid(cookie) (0) 32#endif 33 34 35/* 36 * overload PG_private_2 to give us PG_fscache - this is used to indicate that 37 * a page is currently backed by a local disk cache 38 */ 39#define PageFsCache(page) PagePrivate2((page)) 40#define SetPageFsCache(page) SetPagePrivate2((page)) 41#define ClearPageFsCache(page) ClearPagePrivate2((page)) 42#define TestSetPageFsCache(page) TestSetPagePrivate2((page)) 43#define TestClearPageFsCache(page) TestClearPagePrivate2((page)) 44 45/* pattern used to fill dead space in an index entry */ 46#define FSCACHE_INDEX_DEADFILL_PATTERN 0x79 47 48struct pagevec; 49struct fscache_cache_tag; 50struct fscache_cookie; 51struct fscache_netfs; 52 53typedef void (*fscache_rw_complete_t)(struct page *page, 54 void *context, 55 int error); 56 57/* result of index entry consultation */ 58enum fscache_checkaux { 59 FSCACHE_CHECKAUX_OKAY, /* entry okay as is */ 60 FSCACHE_CHECKAUX_NEEDS_UPDATE, /* entry requires update */ 61 FSCACHE_CHECKAUX_OBSOLETE, /* entry requires deletion */ 62}; 63 64/* 65 * fscache cookie definition 66 */ 67struct fscache_cookie_def { 68 /* name of cookie type */ 69 char name[16]; 70 71 /* cookie type */ 72 uint8_t type; 73#define FSCACHE_COOKIE_TYPE_INDEX 0 74#define FSCACHE_COOKIE_TYPE_DATAFILE 1 75 76 /* select the cache into which to insert an entry in this index 77 * - optional 78 * - should return a cache identifier or NULL to cause the cache to be 79 * inherited from the parent if possible or the first cache picked 80 * for a non-index file if not 81 */ 82 struct fscache_cache_tag *(*select_cache)( 83 const void *parent_netfs_data, 84 const void *cookie_netfs_data); 85 86 /* get an index key 87 * - should store the key data in the buffer 88 * - should return the amount of data stored 89 * - not permitted to return an error 90 * - the netfs data from the cookie being used as the source is 91 * presented 92 */ 93 uint16_t (*get_key)(const void *cookie_netfs_data, 94 void *buffer, 95 uint16_t bufmax); 96 97 /* get certain file attributes from the netfs data 98 * - this function can be absent for an index 99 * - not permitted to return an error 100 * - the netfs data from the cookie being used as the source is 101 * presented 102 */ 103 void (*get_attr)(const void *cookie_netfs_data, uint64_t *size); 104 105 /* get the auxiliary data from netfs data 106 * - this function can be absent if the index carries no state data 107 * - should store the auxiliary data in the buffer 108 * - should return the amount of amount stored 109 * - not permitted to return an error 110 * - the netfs data from the cookie being used as the source is 111 * presented 112 */ 113 uint16_t (*get_aux)(const void *cookie_netfs_data, 114 void *buffer, 115 uint16_t bufmax); 116 117 /* consult the netfs about the state of an object 118 * - this function can be absent if the index carries no state data 119 * - the netfs data from the cookie being used as the target is 120 * presented, as is the auxiliary data 121 */ 122 enum fscache_checkaux (*check_aux)(void *cookie_netfs_data, 123 const void *data, 124 uint16_t datalen); 125 126 /* get an extra reference on a read context 127 * - this function can be absent if the completion function doesn't 128 * require a context 129 */ 130 void (*get_context)(void *cookie_netfs_data, void *context); 131 132 /* release an extra reference on a read context 133 * - this function can be absent if the completion function doesn't 134 * require a context 135 */ 136 void (*put_context)(void *cookie_netfs_data, void *context); 137 138 /* indicate page that now have cache metadata retained 139 * - this function should mark the specified page as now being cached 140 * - the page will have been marked with PG_fscache before this is 141 * called, so this is optional 142 */ 143 void (*mark_page_cached)(void *cookie_netfs_data, 144 struct address_space *mapping, 145 struct page *page); 146 147 /* indicate the cookie is no longer cached 148 * - this function is called when the backing store currently caching 149 * a cookie is removed 150 * - the netfs should use this to clean up any markers indicating 151 * cached pages 152 * - this is mandatory for any object that may have data 153 */ 154 void (*now_uncached)(void *cookie_netfs_data); 155}; 156 157/* 158 * fscache cached network filesystem type 159 * - name, version and ops must be filled in before registration 160 * - all other fields will be set during registration 161 */ 162struct fscache_netfs { 163 uint32_t version; /* indexing version */ 164 const char *name; /* filesystem name */ 165 struct fscache_cookie *primary_index; 166 struct list_head link; /* internal link */ 167}; 168 169/* 170 * data file or index object cookie 171 * - a file will only appear in one cache 172 * - a request to cache a file may or may not be honoured, subject to 173 * constraints such as disk space 174 * - indices are created on disk just-in-time 175 */ 176struct fscache_cookie { 177 atomic_t usage; /* number of users of this cookie */ 178 atomic_t n_children; /* number of children of this cookie */ 179 atomic_t n_active; /* number of active users of netfs ptrs */ 180 spinlock_t lock; 181 spinlock_t stores_lock; /* lock on page store tree */ 182 struct hlist_head backing_objects; /* object(s) backing this file/index */ 183 const struct fscache_cookie_def *def; /* definition */ 184 struct fscache_cookie *parent; /* parent of this entry */ 185 void *netfs_data; /* back pointer to netfs */ 186 struct radix_tree_root stores; /* pages to be stored on this cookie */ 187#define FSCACHE_COOKIE_PENDING_TAG 0 /* pages tag: pending write to cache */ 188#define FSCACHE_COOKIE_STORING_TAG 1 /* pages tag: writing to cache */ 189 190 unsigned long flags; 191#define FSCACHE_COOKIE_LOOKING_UP 0 /* T if non-index cookie being looked up still */ 192#define FSCACHE_COOKIE_NO_DATA_YET 1 /* T if new object with no cached data yet */ 193#define FSCACHE_COOKIE_UNAVAILABLE 2 /* T if cookie is unavailable (error, etc) */ 194#define FSCACHE_COOKIE_INVALIDATING 3 /* T if cookie is being invalidated */ 195#define FSCACHE_COOKIE_RELINQUISHED 4 /* T if cookie has been relinquished */ 196#define FSCACHE_COOKIE_ENABLED 5 /* T if cookie is enabled */ 197#define FSCACHE_COOKIE_ENABLEMENT_LOCK 6 /* T if cookie is being en/disabled */ 198}; 199 200static inline bool fscache_cookie_enabled(struct fscache_cookie *cookie) 201{ 202 return test_bit(FSCACHE_COOKIE_ENABLED, &cookie->flags); 203} 204 205/* 206 * slow-path functions for when there is actually caching available, and the 207 * netfs does actually have a valid token 208 * - these are not to be called directly 209 * - these are undefined symbols when FS-Cache is not configured and the 210 * optimiser takes care of not using them 211 */ 212extern int __fscache_register_netfs(struct fscache_netfs *); 213extern void __fscache_unregister_netfs(struct fscache_netfs *); 214extern struct fscache_cache_tag *__fscache_lookup_cache_tag(const char *); 215extern void __fscache_release_cache_tag(struct fscache_cache_tag *); 216 217extern struct fscache_cookie *__fscache_acquire_cookie( 218 struct fscache_cookie *, 219 const struct fscache_cookie_def *, 220 void *, bool); 221extern void __fscache_relinquish_cookie(struct fscache_cookie *, bool); 222extern int __fscache_check_consistency(struct fscache_cookie *); 223extern void __fscache_update_cookie(struct fscache_cookie *); 224extern int __fscache_attr_changed(struct fscache_cookie *); 225extern void __fscache_invalidate(struct fscache_cookie *); 226extern void __fscache_wait_on_invalidate(struct fscache_cookie *); 227extern int __fscache_read_or_alloc_page(struct fscache_cookie *, 228 struct page *, 229 fscache_rw_complete_t, 230 void *, 231 gfp_t); 232extern int __fscache_read_or_alloc_pages(struct fscache_cookie *, 233 struct address_space *, 234 struct list_head *, 235 unsigned *, 236 fscache_rw_complete_t, 237 void *, 238 gfp_t); 239extern int __fscache_alloc_page(struct fscache_cookie *, struct page *, gfp_t); 240extern int __fscache_write_page(struct fscache_cookie *, struct page *, gfp_t); 241extern void __fscache_uncache_page(struct fscache_cookie *, struct page *); 242extern bool __fscache_check_page_write(struct fscache_cookie *, struct page *); 243extern void __fscache_wait_on_page_write(struct fscache_cookie *, struct page *); 244extern bool __fscache_maybe_release_page(struct fscache_cookie *, struct page *, 245 gfp_t); 246extern void __fscache_uncache_all_inode_pages(struct fscache_cookie *, 247 struct inode *); 248extern void __fscache_readpages_cancel(struct fscache_cookie *cookie, 249 struct list_head *pages); 250extern void __fscache_disable_cookie(struct fscache_cookie *, bool); 251extern void __fscache_enable_cookie(struct fscache_cookie *, 252 bool (*)(void *), void *); 253 254/** 255 * fscache_register_netfs - Register a filesystem as desiring caching services 256 * @netfs: The description of the filesystem 257 * 258 * Register a filesystem as desiring caching services if they're available. 259 * 260 * See Documentation/filesystems/caching/netfs-api.txt for a complete 261 * description. 262 */ 263static inline 264int fscache_register_netfs(struct fscache_netfs *netfs) 265{ 266 if (fscache_available()) 267 return __fscache_register_netfs(netfs); 268 else 269 return 0; 270} 271 272/** 273 * fscache_unregister_netfs - Indicate that a filesystem no longer desires 274 * caching services 275 * @netfs: The description of the filesystem 276 * 277 * Indicate that a filesystem no longer desires caching services for the 278 * moment. 279 * 280 * See Documentation/filesystems/caching/netfs-api.txt for a complete 281 * description. 282 */ 283static inline 284void fscache_unregister_netfs(struct fscache_netfs *netfs) 285{ 286 if (fscache_available()) 287 __fscache_unregister_netfs(netfs); 288} 289 290/** 291 * fscache_lookup_cache_tag - Look up a cache tag 292 * @name: The name of the tag to search for 293 * 294 * Acquire a specific cache referral tag that can be used to select a specific 295 * cache in which to cache an index. 296 * 297 * See Documentation/filesystems/caching/netfs-api.txt for a complete 298 * description. 299 */ 300static inline 301struct fscache_cache_tag *fscache_lookup_cache_tag(const char *name) 302{ 303 if (fscache_available()) 304 return __fscache_lookup_cache_tag(name); 305 else 306 return NULL; 307} 308 309/** 310 * fscache_release_cache_tag - Release a cache tag 311 * @tag: The tag to release 312 * 313 * Release a reference to a cache referral tag previously looked up. 314 * 315 * See Documentation/filesystems/caching/netfs-api.txt for a complete 316 * description. 317 */ 318static inline 319void fscache_release_cache_tag(struct fscache_cache_tag *tag) 320{ 321 if (fscache_available()) 322 __fscache_release_cache_tag(tag); 323} 324 325/** 326 * fscache_acquire_cookie - Acquire a cookie to represent a cache object 327 * @parent: The cookie that's to be the parent of this one 328 * @def: A description of the cache object, including callback operations 329 * @netfs_data: An arbitrary piece of data to be kept in the cookie to 330 * represent the cache object to the netfs 331 * @enable: Whether or not to enable a data cookie immediately 332 * 333 * This function is used to inform FS-Cache about part of an index hierarchy 334 * that can be used to locate files. This is done by requesting a cookie for 335 * each index in the path to the file. 336 * 337 * See Documentation/filesystems/caching/netfs-api.txt for a complete 338 * description. 339 */ 340static inline 341struct fscache_cookie *fscache_acquire_cookie( 342 struct fscache_cookie *parent, 343 const struct fscache_cookie_def *def, 344 void *netfs_data, 345 bool enable) 346{ 347 if (fscache_cookie_valid(parent) && fscache_cookie_enabled(parent)) 348 return __fscache_acquire_cookie(parent, def, netfs_data, 349 enable); 350 else 351 return NULL; 352} 353 354/** 355 * fscache_relinquish_cookie - Return the cookie to the cache, maybe discarding 356 * it 357 * @cookie: The cookie being returned 358 * @retire: True if the cache object the cookie represents is to be discarded 359 * 360 * This function returns a cookie to the cache, forcibly discarding the 361 * associated cache object if retire is set to true. 362 * 363 * See Documentation/filesystems/caching/netfs-api.txt for a complete 364 * description. 365 */ 366static inline 367void fscache_relinquish_cookie(struct fscache_cookie *cookie, bool retire) 368{ 369 if (fscache_cookie_valid(cookie)) 370 __fscache_relinquish_cookie(cookie, retire); 371} 372 373/** 374 * fscache_check_consistency - Request that if the cache is updated 375 * @cookie: The cookie representing the cache object 376 * 377 * Request an consistency check from fscache, which passes the request 378 * to the backing cache. 379 * 380 * Returns 0 if consistent and -ESTALE if inconsistent. May also 381 * return -ENOMEM and -ERESTARTSYS. 382 */ 383static inline 384int fscache_check_consistency(struct fscache_cookie *cookie) 385{ 386 if (fscache_cookie_valid(cookie) && fscache_cookie_enabled(cookie)) 387 return __fscache_check_consistency(cookie); 388 else 389 return 0; 390} 391 392/** 393 * fscache_update_cookie - Request that a cache object be updated 394 * @cookie: The cookie representing the cache object 395 * 396 * Request an update of the index data for the cache object associated with the 397 * cookie. 398 * 399 * See Documentation/filesystems/caching/netfs-api.txt for a complete 400 * description. 401 */ 402static inline 403void fscache_update_cookie(struct fscache_cookie *cookie) 404{ 405 if (fscache_cookie_valid(cookie) && fscache_cookie_enabled(cookie)) 406 __fscache_update_cookie(cookie); 407} 408 409/** 410 * fscache_pin_cookie - Pin a data-storage cache object in its cache 411 * @cookie: The cookie representing the cache object 412 * 413 * Permit data-storage cache objects to be pinned in the cache. 414 * 415 * See Documentation/filesystems/caching/netfs-api.txt for a complete 416 * description. 417 */ 418static inline 419int fscache_pin_cookie(struct fscache_cookie *cookie) 420{ 421 return -ENOBUFS; 422} 423 424/** 425 * fscache_pin_cookie - Unpin a data-storage cache object in its cache 426 * @cookie: The cookie representing the cache object 427 * 428 * Permit data-storage cache objects to be unpinned from the cache. 429 * 430 * See Documentation/filesystems/caching/netfs-api.txt for a complete 431 * description. 432 */ 433static inline 434void fscache_unpin_cookie(struct fscache_cookie *cookie) 435{ 436} 437 438/** 439 * fscache_attr_changed - Notify cache that an object's attributes changed 440 * @cookie: The cookie representing the cache object 441 * 442 * Send a notification to the cache indicating that an object's attributes have 443 * changed. This includes the data size. These attributes will be obtained 444 * through the get_attr() cookie definition op. 445 * 446 * See Documentation/filesystems/caching/netfs-api.txt for a complete 447 * description. 448 */ 449static inline 450int fscache_attr_changed(struct fscache_cookie *cookie) 451{ 452 if (fscache_cookie_valid(cookie) && fscache_cookie_enabled(cookie)) 453 return __fscache_attr_changed(cookie); 454 else 455 return -ENOBUFS; 456} 457 458/** 459 * fscache_invalidate - Notify cache that an object needs invalidation 460 * @cookie: The cookie representing the cache object 461 * 462 * Notify the cache that an object is needs to be invalidated and that it 463 * should abort any retrievals or stores it is doing on the cache. The object 464 * is then marked non-caching until such time as the invalidation is complete. 465 * 466 * This can be called with spinlocks held. 467 * 468 * See Documentation/filesystems/caching/netfs-api.txt for a complete 469 * description. 470 */ 471static inline 472void fscache_invalidate(struct fscache_cookie *cookie) 473{ 474 if (fscache_cookie_valid(cookie) && fscache_cookie_enabled(cookie)) 475 __fscache_invalidate(cookie); 476} 477 478/** 479 * fscache_wait_on_invalidate - Wait for invalidation to complete 480 * @cookie: The cookie representing the cache object 481 * 482 * Wait for the invalidation of an object to complete. 483 * 484 * See Documentation/filesystems/caching/netfs-api.txt for a complete 485 * description. 486 */ 487static inline 488void fscache_wait_on_invalidate(struct fscache_cookie *cookie) 489{ 490 if (fscache_cookie_valid(cookie)) 491 __fscache_wait_on_invalidate(cookie); 492} 493 494/** 495 * fscache_reserve_space - Reserve data space for a cached object 496 * @cookie: The cookie representing the cache object 497 * @i_size: The amount of space to be reserved 498 * 499 * Reserve an amount of space in the cache for the cache object attached to a 500 * cookie so that a write to that object within the space can always be 501 * honoured. 502 * 503 * See Documentation/filesystems/caching/netfs-api.txt for a complete 504 * description. 505 */ 506static inline 507int fscache_reserve_space(struct fscache_cookie *cookie, loff_t size) 508{ 509 return -ENOBUFS; 510} 511 512/** 513 * fscache_read_or_alloc_page - Read a page from the cache or allocate a block 514 * in which to store it 515 * @cookie: The cookie representing the cache object 516 * @page: The netfs page to fill if possible 517 * @end_io_func: The callback to invoke when and if the page is filled 518 * @context: An arbitrary piece of data to pass on to end_io_func() 519 * @gfp: The conditions under which memory allocation should be made 520 * 521 * Read a page from the cache, or if that's not possible make a potential 522 * one-block reservation in the cache into which the page may be stored once 523 * fetched from the server. 524 * 525 * If the page is not backed by the cache object, or if it there's some reason 526 * it can't be, -ENOBUFS will be returned and nothing more will be done for 527 * that page. 528 * 529 * Else, if that page is backed by the cache, a read will be initiated directly 530 * to the netfs's page and 0 will be returned by this function. The 531 * end_io_func() callback will be invoked when the operation terminates on a 532 * completion or failure. Note that the callback may be invoked before the 533 * return. 534 * 535 * Else, if the page is unbacked, -ENODATA is returned and a block may have 536 * been allocated in the cache. 537 * 538 * See Documentation/filesystems/caching/netfs-api.txt for a complete 539 * description. 540 */ 541static inline 542int fscache_read_or_alloc_page(struct fscache_cookie *cookie, 543 struct page *page, 544 fscache_rw_complete_t end_io_func, 545 void *context, 546 gfp_t gfp) 547{ 548 if (fscache_cookie_valid(cookie) && fscache_cookie_enabled(cookie)) 549 return __fscache_read_or_alloc_page(cookie, page, end_io_func, 550 context, gfp); 551 else 552 return -ENOBUFS; 553} 554 555/** 556 * fscache_read_or_alloc_pages - Read pages from the cache and/or allocate 557 * blocks in which to store them 558 * @cookie: The cookie representing the cache object 559 * @mapping: The netfs inode mapping to which the pages will be attached 560 * @pages: A list of potential netfs pages to be filled 561 * @nr_pages: Number of pages to be read and/or allocated 562 * @end_io_func: The callback to invoke when and if each page is filled 563 * @context: An arbitrary piece of data to pass on to end_io_func() 564 * @gfp: The conditions under which memory allocation should be made 565 * 566 * Read a set of pages from the cache, or if that's not possible, attempt to 567 * make a potential one-block reservation for each page in the cache into which 568 * that page may be stored once fetched from the server. 569 * 570 * If some pages are not backed by the cache object, or if it there's some 571 * reason they can't be, -ENOBUFS will be returned and nothing more will be 572 * done for that pages. 573 * 574 * Else, if some of the pages are backed by the cache, a read will be initiated 575 * directly to the netfs's page and 0 will be returned by this function. The 576 * end_io_func() callback will be invoked when the operation terminates on a 577 * completion or failure. Note that the callback may be invoked before the 578 * return. 579 * 580 * Else, if a page is unbacked, -ENODATA is returned and a block may have 581 * been allocated in the cache. 582 * 583 * Because the function may want to return all of -ENOBUFS, -ENODATA and 0 in 584 * regard to different pages, the return values are prioritised in that order. 585 * Any pages submitted for reading are removed from the pages list. 586 * 587 * See Documentation/filesystems/caching/netfs-api.txt for a complete 588 * description. 589 */ 590static inline 591int fscache_read_or_alloc_pages(struct fscache_cookie *cookie, 592 struct address_space *mapping, 593 struct list_head *pages, 594 unsigned *nr_pages, 595 fscache_rw_complete_t end_io_func, 596 void *context, 597 gfp_t gfp) 598{ 599 if (fscache_cookie_valid(cookie) && fscache_cookie_enabled(cookie)) 600 return __fscache_read_or_alloc_pages(cookie, mapping, pages, 601 nr_pages, end_io_func, 602 context, gfp); 603 else 604 return -ENOBUFS; 605} 606 607/** 608 * fscache_alloc_page - Allocate a block in which to store a page 609 * @cookie: The cookie representing the cache object 610 * @page: The netfs page to allocate a page for 611 * @gfp: The conditions under which memory allocation should be made 612 * 613 * Request Allocation a block in the cache in which to store a netfs page 614 * without retrieving any contents from the cache. 615 * 616 * If the page is not backed by a file then -ENOBUFS will be returned and 617 * nothing more will be done, and no reservation will be made. 618 * 619 * Else, a block will be allocated if one wasn't already, and 0 will be 620 * returned 621 * 622 * See Documentation/filesystems/caching/netfs-api.txt for a complete 623 * description. 624 */ 625static inline 626int fscache_alloc_page(struct fscache_cookie *cookie, 627 struct page *page, 628 gfp_t gfp) 629{ 630 if (fscache_cookie_valid(cookie) && fscache_cookie_enabled(cookie)) 631 return __fscache_alloc_page(cookie, page, gfp); 632 else 633 return -ENOBUFS; 634} 635 636/** 637 * fscache_readpages_cancel - Cancel read/alloc on pages 638 * @cookie: The cookie representing the inode's cache object. 639 * @pages: The netfs pages that we canceled write on in readpages() 640 * 641 * Uncache/unreserve the pages reserved earlier in readpages() via 642 * fscache_readpages_or_alloc() and similar. In most successful caches in 643 * readpages() this doesn't do anything. In cases when the underlying netfs's 644 * readahead failed we need to clean up the pagelist (unmark and uncache). 645 * 646 * This function may sleep as it may have to clean up disk state. 647 */ 648static inline 649void fscache_readpages_cancel(struct fscache_cookie *cookie, 650 struct list_head *pages) 651{ 652 if (fscache_cookie_valid(cookie)) 653 __fscache_readpages_cancel(cookie, pages); 654} 655 656/** 657 * fscache_write_page - Request storage of a page in the cache 658 * @cookie: The cookie representing the cache object 659 * @page: The netfs page to store 660 * @gfp: The conditions under which memory allocation should be made 661 * 662 * Request the contents of the netfs page be written into the cache. This 663 * request may be ignored if no cache block is currently allocated, in which 664 * case it will return -ENOBUFS. 665 * 666 * If a cache block was already allocated, a write will be initiated and 0 will 667 * be returned. The PG_fscache_write page bit is set immediately and will then 668 * be cleared at the completion of the write to indicate the success or failure 669 * of the operation. Note that the completion may happen before the return. 670 * 671 * See Documentation/filesystems/caching/netfs-api.txt for a complete 672 * description. 673 */ 674static inline 675int fscache_write_page(struct fscache_cookie *cookie, 676 struct page *page, 677 gfp_t gfp) 678{ 679 if (fscache_cookie_valid(cookie) && fscache_cookie_enabled(cookie)) 680 return __fscache_write_page(cookie, page, gfp); 681 else 682 return -ENOBUFS; 683} 684 685/** 686 * fscache_uncache_page - Indicate that caching is no longer required on a page 687 * @cookie: The cookie representing the cache object 688 * @page: The netfs page that was being cached. 689 * 690 * Tell the cache that we no longer want a page to be cached and that it should 691 * remove any knowledge of the netfs page it may have. 692 * 693 * Note that this cannot cancel any outstanding I/O operations between this 694 * page and the cache. 695 * 696 * See Documentation/filesystems/caching/netfs-api.txt for a complete 697 * description. 698 */ 699static inline 700void fscache_uncache_page(struct fscache_cookie *cookie, 701 struct page *page) 702{ 703 if (fscache_cookie_valid(cookie)) 704 __fscache_uncache_page(cookie, page); 705} 706 707/** 708 * fscache_check_page_write - Ask if a page is being writing to the cache 709 * @cookie: The cookie representing the cache object 710 * @page: The netfs page that is being cached. 711 * 712 * Ask the cache if a page is being written to the cache. 713 * 714 * See Documentation/filesystems/caching/netfs-api.txt for a complete 715 * description. 716 */ 717static inline 718bool fscache_check_page_write(struct fscache_cookie *cookie, 719 struct page *page) 720{ 721 if (fscache_cookie_valid(cookie)) 722 return __fscache_check_page_write(cookie, page); 723 return false; 724} 725 726/** 727 * fscache_wait_on_page_write - Wait for a page to complete writing to the cache 728 * @cookie: The cookie representing the cache object 729 * @page: The netfs page that is being cached. 730 * 731 * Ask the cache to wake us up when a page is no longer being written to the 732 * cache. 733 * 734 * See Documentation/filesystems/caching/netfs-api.txt for a complete 735 * description. 736 */ 737static inline 738void fscache_wait_on_page_write(struct fscache_cookie *cookie, 739 struct page *page) 740{ 741 if (fscache_cookie_valid(cookie)) 742 __fscache_wait_on_page_write(cookie, page); 743} 744 745/** 746 * fscache_maybe_release_page - Consider releasing a page, cancelling a store 747 * @cookie: The cookie representing the cache object 748 * @page: The netfs page that is being cached. 749 * @gfp: The gfp flags passed to releasepage() 750 * 751 * Consider releasing a page for the vmscan algorithm, on behalf of the netfs's 752 * releasepage() call. A storage request on the page may cancelled if it is 753 * not currently being processed. 754 * 755 * The function returns true if the page no longer has a storage request on it, 756 * and false if a storage request is left in place. If true is returned, the 757 * page will have been passed to fscache_uncache_page(). If false is returned 758 * the page cannot be freed yet. 759 */ 760static inline 761bool fscache_maybe_release_page(struct fscache_cookie *cookie, 762 struct page *page, 763 gfp_t gfp) 764{ 765 if (fscache_cookie_valid(cookie) && PageFsCache(page)) 766 return __fscache_maybe_release_page(cookie, page, gfp); 767 return false; 768} 769 770/** 771 * fscache_uncache_all_inode_pages - Uncache all an inode's pages 772 * @cookie: The cookie representing the inode's cache object. 773 * @inode: The inode to uncache pages from. 774 * 775 * Uncache all the pages in an inode that are marked PG_fscache, assuming them 776 * to be associated with the given cookie. 777 * 778 * This function may sleep. It will wait for pages that are being written out 779 * and will wait whilst the PG_fscache mark is removed by the cache. 780 */ 781static inline 782void fscache_uncache_all_inode_pages(struct fscache_cookie *cookie, 783 struct inode *inode) 784{ 785 if (fscache_cookie_valid(cookie)) 786 __fscache_uncache_all_inode_pages(cookie, inode); 787} 788 789/** 790 * fscache_disable_cookie - Disable a cookie 791 * @cookie: The cookie representing the cache object 792 * @invalidate: Invalidate the backing object 793 * 794 * Disable a cookie from accepting further alloc, read, write, invalidate, 795 * update or acquire operations. Outstanding operations can still be waited 796 * upon and pages can still be uncached and the cookie relinquished. 797 * 798 * This will not return until all outstanding operations have completed. 799 * 800 * If @invalidate is set, then the backing object will be invalidated and 801 * detached, otherwise it will just be detached. 802 */ 803static inline 804void fscache_disable_cookie(struct fscache_cookie *cookie, bool invalidate) 805{ 806 if (fscache_cookie_valid(cookie) && fscache_cookie_enabled(cookie)) 807 __fscache_disable_cookie(cookie, invalidate); 808} 809 810/** 811 * fscache_enable_cookie - Reenable a cookie 812 * @cookie: The cookie representing the cache object 813 * @can_enable: A function to permit enablement once lock is held 814 * @data: Data for can_enable() 815 * 816 * Reenable a previously disabled cookie, allowing it to accept further alloc, 817 * read, write, invalidate, update or acquire operations. An attempt will be 818 * made to immediately reattach the cookie to a backing object. 819 * 820 * The can_enable() function is called (if not NULL) once the enablement lock 821 * is held to rule on whether enablement is still permitted to go ahead. 822 */ 823static inline 824void fscache_enable_cookie(struct fscache_cookie *cookie, 825 bool (*can_enable)(void *data), 826 void *data) 827{ 828 if (fscache_cookie_valid(cookie) && !fscache_cookie_enabled(cookie)) 829 __fscache_enable_cookie(cookie, can_enable, data); 830} 831 832#endif /* _LINUX_FSCACHE_H */ 833