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