include/linux/fscache.h

   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
  48 struct pagevec;
  49 struct fscache_cache_tag;
  50 struct fscache_cookie;
  51 struct fscache_netfs;
  52
  53 typedef void (*fscache_rw_complete_t)(struct page *page,
  54                                       void *context,
  55                                       int error);
  56
  57 /* result of index entry consultation */
  58 enum 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  */
  67 struct 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  */
 162 struct 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  * slow-path functions for when there is actually caching available, and the
 171  * netfs does actually have a valid token
 172  * - these are not to be called directly
 173  * - these are undefined symbols when FS-Cache is not configured and the
 174  *   optimiser takes care of not using them
 175  */
 176 extern int __fscache_register_netfs(struct fscache_netfs *);
 177 extern void __fscache_unregister_netfs(struct fscache_netfs *);
 178 extern struct fscache_cache_tag *__fscache_lookup_cache_tag(const char *);
 179 extern void __fscache_release_cache_tag(struct fscache_cache_tag *);
 180
 181 extern struct fscache_cookie *__fscache_acquire_cookie(
 182         struct fscache_cookie *,
 183         const struct fscache_cookie_def *,
 184         void *);
 185 extern void __fscache_relinquish_cookie(struct fscache_cookie *, int);
 186 extern int __fscache_check_consistency(struct fscache_cookie *);
 187 extern void __fscache_update_cookie(struct fscache_cookie *);
 188 extern int __fscache_attr_changed(struct fscache_cookie *);
 189 extern void __fscache_invalidate(struct fscache_cookie *);
 190 extern void __fscache_wait_on_invalidate(struct fscache_cookie *);
 191 extern int __fscache_read_or_alloc_page(struct fscache_cookie *,
 192                                         struct page *,
 193                                         fscache_rw_complete_t,
 194                                         void *,
 195                                         gfp_t);
 196 extern int __fscache_read_or_alloc_pages(struct fscache_cookie *,
 197                                          struct address_space *,
 198                                          struct list_head *,
 199                                          unsigned *,
 200                                          fscache_rw_complete_t,
 201                                          void *,
 202                                          gfp_t);
 203 extern int __fscache_alloc_page(struct fscache_cookie *, struct page *, gfp_t);
 204 extern int __fscache_write_page(struct fscache_cookie *, struct page *, gfp_t);
 205 extern void __fscache_uncache_page(struct fscache_cookie *, struct page *);
 206 extern bool __fscache_check_page_write(struct fscache_cookie *, struct page *);
 207 extern void __fscache_wait_on_page_write(struct fscache_cookie *, struct page *);
 208 extern bool __fscache_maybe_release_page(struct fscache_cookie *, struct page *,
 209                                          gfp_t);
 210 extern void __fscache_uncache_all_inode_pages(struct fscache_cookie *,
 211                                               struct inode *);
 212 extern void __fscache_readpages_cancel(struct fscache_cookie *cookie,
 213                                        struct list_head *pages);
 214
 215 /**
 216  * fscache_register_netfs - Register a filesystem as desiring caching services
 217  * @netfs: The description of the filesystem
 218  *
 219  * Register a filesystem as desiring caching services if they're available.
 220  *
 221  * See Documentation/filesystems/caching/netfs-api.txt for a complete
 222  * description.
 223  */
 224 static inline
 225 int fscache_register_netfs(struct fscache_netfs *netfs)
 226 {
 227         if (fscache_available())
 228                 return __fscache_register_netfs(netfs);
 229         else
 230                 return 0;
 231 }
 232
 233 /**
 234  * fscache_unregister_netfs - Indicate that a filesystem no longer desires
 235  * caching services
 236  * @netfs: The description of the filesystem
 237  *
 238  * Indicate that a filesystem no longer desires caching services for the
 239  * moment.
 240  *
 241  * See Documentation/filesystems/caching/netfs-api.txt for a complete
 242  * description.
 243  */
 244 static inline
 245 void fscache_unregister_netfs(struct fscache_netfs *netfs)
 246 {
 247         if (fscache_available())
 248                 __fscache_unregister_netfs(netfs);
 249 }
 250
 251 /**
 252  * fscache_lookup_cache_tag - Look up a cache tag
 253  * @name: The name of the tag to search for
 254  *
 255  * Acquire a specific cache referral tag that can be used to select a specific
 256  * cache in which to cache an index.
 257  *
 258  * See Documentation/filesystems/caching/netfs-api.txt for a complete
 259  * description.
 260  */
 261 static inline
 262 struct fscache_cache_tag *fscache_lookup_cache_tag(const char *name)
 263 {
 264         if (fscache_available())
 265                 return __fscache_lookup_cache_tag(name);
 266         else
 267                 return NULL;
 268 }
 269
 270 /**
 271  * fscache_release_cache_tag - Release a cache tag
 272  * @tag: The tag to release
 273  *
 274  * Release a reference to a cache referral tag previously looked up.
 275  *
 276  * See Documentation/filesystems/caching/netfs-api.txt for a complete
 277  * description.
 278  */
 279 static inline
 280 void fscache_release_cache_tag(struct fscache_cache_tag *tag)
 281 {
 282         if (fscache_available())
 283                 __fscache_release_cache_tag(tag);
 284 }
 285
 286 /**
 287  * fscache_acquire_cookie - Acquire a cookie to represent a cache object
 288  * @parent: The cookie that's to be the parent of this one
 289  * @def: A description of the cache object, including callback operations
 290  * @netfs_data: An arbitrary piece of data to be kept in the cookie to
 291  * represent the cache object to the netfs
 292  *
 293  * This function is used to inform FS-Cache about part of an index hierarchy
 294  * that can be used to locate files.  This is done by requesting a cookie for
 295  * each index in the path to the file.
 296  *
 297  * See Documentation/filesystems/caching/netfs-api.txt for a complete
 298  * description.
 299  */
 300 static inline
 301 struct fscache_cookie *fscache_acquire_cookie(
 302         struct fscache_cookie *parent,
 303         const struct fscache_cookie_def *def,
 304         void *netfs_data)
 305 {
 306         if (fscache_cookie_valid(parent))
 307                 return __fscache_acquire_cookie(parent, def, netfs_data);
 308         else
 309                 return NULL;
 310 }
 311
 312 /**
 313  * fscache_relinquish_cookie - Return the cookie to the cache, maybe discarding
 314  * it
 315  * @cookie: The cookie being returned
 316  * @retire: True if the cache object the cookie represents is to be discarded
 317  *
 318  * This function returns a cookie to the cache, forcibly discarding the
 319  * associated cache object if retire is set to true.
 320  *
 321  * See Documentation/filesystems/caching/netfs-api.txt for a complete
 322  * description.
 323  */
 324 static inline
 325 void fscache_relinquish_cookie(struct fscache_cookie *cookie, int retire)
 326 {
 327         if (fscache_cookie_valid(cookie))
 328                 __fscache_relinquish_cookie(cookie, retire);
 329 }
 330
 331 /**
 332  * fscache_check_consistency - Request that if the cache is updated
 333  * @cookie: The cookie representing the cache object
 334  *
 335  * Request an consistency check from fscache, which passes the request
 336  * to the backing cache.
 337  *
 338  * Returns 0 if consistent and -ESTALE if inconsistent.  May also
 339  * return -ENOMEM and -ERESTARTSYS.
 340  */
 341 static inline
 342 int fscache_check_consistency(struct fscache_cookie *cookie)
 343 {
 344         if (fscache_cookie_valid(cookie))
 345                 return __fscache_check_consistency(cookie);
 346         else
 347                 return 0;
 348 }
 349
 350 /**
 351  * fscache_update_cookie - Request that a cache object be updated
 352  * @cookie: The cookie representing the cache object
 353  *
 354  * Request an update of the index data for the cache object associated with the
 355  * cookie.
 356  *
 357  * See Documentation/filesystems/caching/netfs-api.txt for a complete
 358  * description.
 359  */
 360 static inline
 361 void fscache_update_cookie(struct fscache_cookie *cookie)
 362 {
 363         if (fscache_cookie_valid(cookie))
 364                 __fscache_update_cookie(cookie);
 365 }
 366
 367 /**
 368  * fscache_pin_cookie - Pin a data-storage cache object in its cache
 369  * @cookie: The cookie representing the cache object
 370  *
 371  * Permit data-storage cache objects to be pinned in the cache.
 372  *
 373  * See Documentation/filesystems/caching/netfs-api.txt for a complete
 374  * description.
 375  */
 376 static inline
 377 int fscache_pin_cookie(struct fscache_cookie *cookie)
 378 {
 379         return -ENOBUFS;
 380 }
 381
 382 /**
 383  * fscache_pin_cookie - Unpin a data-storage cache object in its cache
 384  * @cookie: The cookie representing the cache object
 385  *
 386  * Permit data-storage cache objects to be unpinned from the cache.
 387  *
 388  * See Documentation/filesystems/caching/netfs-api.txt for a complete
 389  * description.
 390  */
 391 static inline
 392 void fscache_unpin_cookie(struct fscache_cookie *cookie)
 393 {
 394 }
 395
 396 /**
 397  * fscache_attr_changed - Notify cache that an object's attributes changed
 398  * @cookie: The cookie representing the cache object
 399  *
 400  * Send a notification to the cache indicating that an object's attributes have
 401  * changed.  This includes the data size.  These attributes will be obtained
 402  * through the get_attr() cookie definition op.
 403  *
 404  * See Documentation/filesystems/caching/netfs-api.txt for a complete
 405  * description.
 406  */
 407 static inline
 408 int fscache_attr_changed(struct fscache_cookie *cookie)
 409 {
 410         if (fscache_cookie_valid(cookie))
 411                 return __fscache_attr_changed(cookie);
 412         else
 413                 return -ENOBUFS;
 414 }
 415
 416 /**
 417  * fscache_invalidate - Notify cache that an object needs invalidation
 418  * @cookie: The cookie representing the cache object
 419  *
 420  * Notify the cache that an object is needs to be invalidated and that it
 421  * should abort any retrievals or stores it is doing on the cache.  The object
 422  * is then marked non-caching until such time as the invalidation is complete.
 423  *
 424  * This can be called with spinlocks held.
 425  *
 426  * See Documentation/filesystems/caching/netfs-api.txt for a complete
 427  * description.
 428  */
 429 static inline
 430 void fscache_invalidate(struct fscache_cookie *cookie)
 431 {
 432         if (fscache_cookie_valid(cookie))
 433                 __fscache_invalidate(cookie);
 434 }
 435
 436 /**
 437  * fscache_wait_on_invalidate - Wait for invalidation to complete
 438  * @cookie: The cookie representing the cache object
 439  *
 440  * Wait for the invalidation of an object to complete.
 441  *
 442  * See Documentation/filesystems/caching/netfs-api.txt for a complete
 443  * description.
 444  */
 445 static inline
 446 void fscache_wait_on_invalidate(struct fscache_cookie *cookie)
 447 {
 448         if (fscache_cookie_valid(cookie))
 449                 __fscache_wait_on_invalidate(cookie);
 450 }
 451
 452 /**
 453  * fscache_reserve_space - Reserve data space for a cached object
 454  * @cookie: The cookie representing the cache object
 455  * @i_size: The amount of space to be reserved
 456  *
 457  * Reserve an amount of space in the cache for the cache object attached to a
 458  * cookie so that a write to that object within the space can always be
 459  * honoured.
 460  *
 461  * See Documentation/filesystems/caching/netfs-api.txt for a complete
 462  * description.
 463  */
 464 static inline
 465 int fscache_reserve_space(struct fscache_cookie *cookie, loff_t size)
 466 {
 467         return -ENOBUFS;
 468 }
 469
 470 /**
 471  * fscache_read_or_alloc_page - Read a page from the cache or allocate a block
 472  * in which to store it
 473  * @cookie: The cookie representing the cache object
 474  * @page: The netfs page to fill if possible
 475  * @end_io_func: The callback to invoke when and if the page is filled
 476  * @context: An arbitrary piece of data to pass on to end_io_func()
 477  * @gfp: The conditions under which memory allocation should be made
 478  *
 479  * Read a page from the cache, or if that's not possible make a potential
 480  * one-block reservation in the cache into which the page may be stored once
 481  * fetched from the server.
 482  *
 483  * If the page is not backed by the cache object, or if it there's some reason
 484  * it can't be, -ENOBUFS will be returned and nothing more will be done for
 485  * that page.
 486  *
 487  * Else, if that page is backed by the cache, a read will be initiated directly
 488  * to the netfs's page and 0 will be returned by this function.  The
 489  * end_io_func() callback will be invoked when the operation terminates on a
 490  * completion or failure.  Note that the callback may be invoked before the
 491  * return.
 492  *
 493  * Else, if the page is unbacked, -ENODATA is returned and a block may have
 494  * been allocated in the cache.
 495  *
 496  * See Documentation/filesystems/caching/netfs-api.txt for a complete
 497  * description.
 498  */
 499 static inline
 500 int fscache_read_or_alloc_page(struct fscache_cookie *cookie,
 501                                struct page *page,
 502                                fscache_rw_complete_t end_io_func,
 503                                void *context,
 504                                gfp_t gfp)
 505 {
 506         if (fscache_cookie_valid(cookie))
 507                 return __fscache_read_or_alloc_page(cookie, page, end_io_func,
 508                                                     context, gfp);
 509         else
 510                 return -ENOBUFS;
 511 }
 512
 513 /**
 514  * fscache_read_or_alloc_pages - Read pages from the cache and/or allocate
 515  * blocks in which to store them
 516  * @cookie: The cookie representing the cache object
 517  * @mapping: The netfs inode mapping to which the pages will be attached
 518  * @pages: A list of potential netfs pages to be filled
 519  * @nr_pages: Number of pages to be read and/or allocated
 520  * @end_io_func: The callback to invoke when and if each page is filled
 521  * @context: An arbitrary piece of data to pass on to end_io_func()
 522  * @gfp: The conditions under which memory allocation should be made
 523  *
 524  * Read a set of pages from the cache, or if that's not possible, attempt to
 525  * make a potential one-block reservation for each page in the cache into which
 526  * that page may be stored once fetched from the server.
 527  *
 528  * If some pages are not backed by the cache object, or if it there's some
 529  * reason they can't be, -ENOBUFS will be returned and nothing more will be
 530  * done for that pages.
 531  *
 532  * Else, if some of the pages are backed by the cache, a read will be initiated
 533  * directly to the netfs's page and 0 will be returned by this function.  The
 534  * end_io_func() callback will be invoked when the operation terminates on a
 535  * completion or failure.  Note that the callback may be invoked before the
 536  * return.
 537  *
 538  * Else, if a page is unbacked, -ENODATA is returned and a block may have
 539  * been allocated in the cache.
 540  *
 541  * Because the function may want to return all of -ENOBUFS, -ENODATA and 0 in
 542  * regard to different pages, the return values are prioritised in that order.
 543  * Any pages submitted for reading are removed from the pages list.
 544  *
 545  * See Documentation/filesystems/caching/netfs-api.txt for a complete
 546  * description.
 547  */
 548 static inline
 549 int fscache_read_or_alloc_pages(struct fscache_cookie *cookie,
 550                                 struct address_space *mapping,
 551                                 struct list_head *pages,
 552                                 unsigned *nr_pages,
 553                                 fscache_rw_complete_t end_io_func,
 554                                 void *context,
 555                                 gfp_t gfp)
 556 {
 557         if (fscache_cookie_valid(cookie))
 558                 return __fscache_read_or_alloc_pages(cookie, mapping, pages,
 559                                                      nr_pages, end_io_func,
 560                                                      context, gfp);
 561         else
 562                 return -ENOBUFS;
 563 }
 564
 565 /**
 566  * fscache_alloc_page - Allocate a block in which to store a page
 567  * @cookie: The cookie representing the cache object
 568  * @page: The netfs page to allocate a page for
 569  * @gfp: The conditions under which memory allocation should be made
 570  *
 571  * Request Allocation a block in the cache in which to store a netfs page
 572  * without retrieving any contents from the cache.
 573  *
 574  * If the page is not backed by a file then -ENOBUFS will be returned and
 575  * nothing more will be done, and no reservation will be made.
 576  *
 577  * Else, a block will be allocated if one wasn't already, and 0 will be
 578  * returned
 579  *
 580  * See Documentation/filesystems/caching/netfs-api.txt for a complete
 581  * description.
 582  */
 583 static inline
 584 int fscache_alloc_page(struct fscache_cookie *cookie,
 585                        struct page *page,
 586                        gfp_t gfp)
 587 {
 588         if (fscache_cookie_valid(cookie))
 589                 return __fscache_alloc_page(cookie, page, gfp);
 590         else
 591                 return -ENOBUFS;
 592 }
 593
 594 /**
 595  * fscache_readpages_cancel - Cancel read/alloc on pages
 596  * @cookie: The cookie representing the inode's cache object.
 597  * @pages: The netfs pages that we canceled write on in readpages()
 598  *
 599  * Uncache/unreserve the pages reserved earlier in readpages() via
 600  * fscache_readpages_or_alloc() and similar.  In most successful caches in
 601  * readpages() this doesn't do anything.  In cases when the underlying netfs's
 602  * readahead failed we need to clean up the pagelist (unmark and uncache).
 603  *
 604  * This function may sleep as it may have to clean up disk state.
 605  */
 606 static inline
 607 void fscache_readpages_cancel(struct fscache_cookie *cookie,
 608                               struct list_head *pages)
 609 {
 610         if (fscache_cookie_valid(cookie))
 611                 __fscache_readpages_cancel(cookie, pages);
 612 }
 613
 614 /**
 615  * fscache_write_page - Request storage of a page in the cache
 616  * @cookie: The cookie representing the cache object
 617  * @page: The netfs page to store
 618  * @gfp: The conditions under which memory allocation should be made
 619  *
 620  * Request the contents of the netfs page be written into the cache.  This
 621  * request may be ignored if no cache block is currently allocated, in which
 622  * case it will return -ENOBUFS.
 623  *
 624  * If a cache block was already allocated, a write will be initiated and 0 will
 625  * be returned.  The PG_fscache_write page bit is set immediately and will then
 626  * be cleared at the completion of the write to indicate the success or failure
 627  * of the operation.  Note that the completion may happen before the return.
 628  *
 629  * See Documentation/filesystems/caching/netfs-api.txt for a complete
 630  * description.
 631  */
 632 static inline
 633 int fscache_write_page(struct fscache_cookie *cookie,
 634                        struct page *page,
 635                        gfp_t gfp)
 636 {
 637         if (fscache_cookie_valid(cookie))
 638                 return __fscache_write_page(cookie, page, gfp);
 639         else
 640                 return -ENOBUFS;
 641 }
 642
 643 /**
 644  * fscache_uncache_page - Indicate that caching is no longer required on a page
 645  * @cookie: The cookie representing the cache object
 646  * @page: The netfs page that was being cached.
 647  *
 648  * Tell the cache that we no longer want a page to be cached and that it should
 649  * remove any knowledge of the netfs page it may have.
 650  *
 651  * Note that this cannot cancel any outstanding I/O operations between this
 652  * page and the cache.
 653  *
 654  * See Documentation/filesystems/caching/netfs-api.txt for a complete
 655  * description.
 656  */
 657 static inline
 658 void fscache_uncache_page(struct fscache_cookie *cookie,
 659                           struct page *page)
 660 {
 661         if (fscache_cookie_valid(cookie))
 662                 __fscache_uncache_page(cookie, page);
 663 }
 664
 665 /**
 666  * fscache_check_page_write - Ask if a page is being writing to the cache
 667  * @cookie: The cookie representing the cache object
 668  * @page: The netfs page that is being cached.
 669  *
 670  * Ask the cache if a page is being written to the cache.
 671  *
 672  * See Documentation/filesystems/caching/netfs-api.txt for a complete
 673  * description.
 674  */
 675 static inline
 676 bool fscache_check_page_write(struct fscache_cookie *cookie,
 677                               struct page *page)
 678 {
 679         if (fscache_cookie_valid(cookie))
 680                 return __fscache_check_page_write(cookie, page);
 681         return false;
 682 }
 683
 684 /**
 685  * fscache_wait_on_page_write - Wait for a page to complete writing to the cache
 686  * @cookie: The cookie representing the cache object
 687  * @page: The netfs page that is being cached.
 688  *
 689  * Ask the cache to wake us up when a page is no longer being written to the
 690  * cache.
 691  *
 692  * See Documentation/filesystems/caching/netfs-api.txt for a complete
 693  * description.
 694  */
 695 static inline
 696 void fscache_wait_on_page_write(struct fscache_cookie *cookie,
 697                                 struct page *page)
 698 {
 699         if (fscache_cookie_valid(cookie))
 700                 __fscache_wait_on_page_write(cookie, page);
 701 }
 702
 703 /**
 704  * fscache_maybe_release_page - Consider releasing a page, cancelling a store
 705  * @cookie: The cookie representing the cache object
 706  * @page: The netfs page that is being cached.
 707  * @gfp: The gfp flags passed to releasepage()
 708  *
 709  * Consider releasing a page for the vmscan algorithm, on behalf of the netfs's
 710  * releasepage() call.  A storage request on the page may cancelled if it is
 711  * not currently being processed.
 712  *
 713  * The function returns true if the page no longer has a storage request on it,
 714  * and false if a storage request is left in place.  If true is returned, the
 715  * page will have been passed to fscache_uncache_page().  If false is returned
 716  * the page cannot be freed yet.
 717  */
 718 static inline
 719 bool fscache_maybe_release_page(struct fscache_cookie *cookie,
 720                                 struct page *page,
 721                                 gfp_t gfp)
 722 {
 723         if (fscache_cookie_valid(cookie) && PageFsCache(page))
 724                 return __fscache_maybe_release_page(cookie, page, gfp);
 725         return false;
 726 }
 727
 728 /**
 729  * fscache_uncache_all_inode_pages - Uncache all an inode's pages
 730  * @cookie: The cookie representing the inode's cache object.
 731  * @inode: The inode to uncache pages from.
 732  *
 733  * Uncache all the pages in an inode that are marked PG_fscache, assuming them
 734  * to be associated with the given cookie.
 735  *
 736  * This function may sleep.  It will wait for pages that are being written out
 737  * and will wait whilst the PG_fscache mark is removed by the cache.
 738  */
 739 static inline
 740 void fscache_uncache_all_inode_pages(struct fscache_cookie *cookie,
 741                                      struct inode *inode)
 742 {
 743         if (fscache_cookie_valid(cookie))
 744                 __fscache_uncache_all_inode_pages(cookie, inode);
 745 }
 746
 747 #endif /* _LINUX_FSCACHE_H */