include/linux/dcookies.h

   1 /*
   2  * dcookies.h
   3  *
   4  * Persistent cookie-path mappings
   5  *
   6  * Copyright 2002 John Levon <levon@movementarian.org>
   7  */
   8
   9 #ifndef DCOOKIES_H
  10 #define DCOOKIES_H
  11
  12
  13 #ifdef CONFIG_PROFILING
  14
  15 #include <linux/dcache.h>
  16 #include <linux/types.h>
  17
  18 struct dcookie_user;
  19 struct path;
  20
  21 /**
  22  * dcookie_register - register a user of dcookies
  23  *
  24  * Register as a dcookie user. Returns %NULL on failure.
  25  */
  26 struct dcookie_user * dcookie_register(void);
  27
  28 /**
  29  * dcookie_unregister - unregister a user of dcookies
  30  *
  31  * Unregister as a dcookie user. This may invalidate
  32  * any dcookie values returned from get_dcookie().
  33  */
  34 void dcookie_unregister(struct dcookie_user * user);
  35
  36 /**
  37  * get_dcookie - acquire a dcookie
  38  *
  39  * Convert the given dentry/vfsmount pair into
  40  * a cookie value.
  41  *
  42  * Returns -EINVAL if no living task has registered as a
  43  * dcookie user.
  44  *
  45  * Returns 0 on success, with *cookie filled in
  46  */
  47 int get_dcookie(struct path *path, unsigned long *cookie);
  48
  49 #else
  50
  51 static inline struct dcookie_user * dcookie_register(void)
  52 {
  53         return NULL;
  54 }
  55
  56 static inline void dcookie_unregister(struct dcookie_user * user)
  57 {
  58         return;
  59 }
  60
  61 static inline int get_dcookie(struct path *path, unsigned long *cookie)
  62 {
  63         return -ENOSYS;
  64 }
  65
  66 #endif /* CONFIG_PROFILING */
  67
  68 #endif /* DCOOKIES_H */