helpers for acl caching + switch to those
[linux-2.6.git] / include / linux / posix_acl.h
1 /*
2   File: linux/posix_acl.h
3
4   (C) 2002 Andreas Gruenbacher, <a.gruenbacher@computer.org>
5 */
6
7
8 #ifndef __LINUX_POSIX_ACL_H
9 #define __LINUX_POSIX_ACL_H
10
11 #include <linux/slab.h>
12
13 #define ACL_UNDEFINED_ID        (-1)
14
15 /* a_type field in acl_user_posix_entry_t */
16 #define ACL_TYPE_ACCESS         (0x8000)
17 #define ACL_TYPE_DEFAULT        (0x4000)
18
19 /* e_tag entry in struct posix_acl_entry */
20 #define ACL_USER_OBJ            (0x01)
21 #define ACL_USER                (0x02)
22 #define ACL_GROUP_OBJ           (0x04)
23 #define ACL_GROUP               (0x08)
24 #define ACL_MASK                (0x10)
25 #define ACL_OTHER               (0x20)
26
27 /* permissions in the e_perm field */
28 #define ACL_READ                (0x04)
29 #define ACL_WRITE               (0x02)
30 #define ACL_EXECUTE             (0x01)
31 //#define ACL_ADD               (0x08)
32 //#define ACL_DELETE            (0x10)
33
34 struct posix_acl_entry {
35         short                   e_tag;
36         unsigned short          e_perm;
37         unsigned int            e_id;
38 };
39
40 struct posix_acl {
41         atomic_t                a_refcount;
42         unsigned int            a_count;
43         struct posix_acl_entry  a_entries[0];
44 };
45
46 #define FOREACH_ACL_ENTRY(pa, acl, pe) \
47         for(pa=(acl)->a_entries, pe=pa+(acl)->a_count; pa<pe; pa++)
48
49
50 /*
51  * Duplicate an ACL handle.
52  */
53 static inline struct posix_acl *
54 posix_acl_dup(struct posix_acl *acl)
55 {
56         if (acl)
57                 atomic_inc(&acl->a_refcount);
58         return acl;
59 }
60
61 /*
62  * Free an ACL handle.
63  */
64 static inline void
65 posix_acl_release(struct posix_acl *acl)
66 {
67         if (acl && atomic_dec_and_test(&acl->a_refcount))
68                 kfree(acl);
69 }
70
71
72 /* posix_acl.c */
73
74 extern struct posix_acl *posix_acl_alloc(int, gfp_t);
75 extern struct posix_acl *posix_acl_clone(const struct posix_acl *, gfp_t);
76 extern int posix_acl_valid(const struct posix_acl *);
77 extern int posix_acl_permission(struct inode *, const struct posix_acl *, int);
78 extern struct posix_acl *posix_acl_from_mode(mode_t, gfp_t);
79 extern int posix_acl_equiv_mode(const struct posix_acl *, mode_t *);
80 extern int posix_acl_create_masq(struct posix_acl *, mode_t *);
81 extern int posix_acl_chmod_masq(struct posix_acl *, mode_t);
82
83 extern struct posix_acl *get_posix_acl(struct inode *, int);
84 extern int set_posix_acl(struct inode *, int, struct posix_acl *);
85
86 static inline struct posix_acl *get_cached_acl(struct inode *inode, int type)
87 {
88         struct posix_acl **p, *acl;
89         switch (type) {
90         case ACL_TYPE_ACCESS:
91                 p = &inode->i_acl;
92                 break;
93         case ACL_TYPE_DEFAULT:
94                 p = &inode->i_default_acl;
95                 break;
96         default:
97                 return ERR_PTR(-EINVAL);
98         }
99         acl = ACCESS_ONCE(*p);
100         if (acl) {
101                 spin_lock(&inode->i_lock);
102                 acl = *p;
103                 if (acl != ACL_NOT_CACHED)
104                         acl = posix_acl_dup(acl);
105                 spin_unlock(&inode->i_lock);
106         }
107         return acl;
108 }
109
110 static inline void set_cached_acl(struct inode *inode,
111                                   int type,
112                                   struct posix_acl *acl)
113 {
114         struct posix_acl *old = NULL;
115         spin_lock(&inode->i_lock);
116         switch (type) {
117         case ACL_TYPE_ACCESS:
118                 old = inode->i_acl;
119                 inode->i_acl = posix_acl_dup(acl);
120                 break;
121         case ACL_TYPE_DEFAULT:
122                 old = inode->i_default_acl;
123                 inode->i_default_acl = posix_acl_dup(acl);
124                 break;
125         }
126         spin_unlock(&inode->i_lock);
127         if (old != ACL_NOT_CACHED)
128                 posix_acl_release(old);
129 }
130
131 static inline void forget_cached_acl(struct inode *inode, int type)
132 {
133         struct posix_acl *old = NULL;
134         spin_lock(&inode->i_lock);
135         switch (type) {
136         case ACL_TYPE_ACCESS:
137                 old = inode->i_acl;
138                 inode->i_acl = ACL_NOT_CACHED;
139                 break;
140         case ACL_TYPE_DEFAULT:
141                 old = inode->i_default_acl;
142                 inode->i_default_acl = ACL_NOT_CACHED;
143                 break;
144         }
145         spin_unlock(&inode->i_lock);
146         if (old != ACL_NOT_CACHED)
147                 posix_acl_release(old);
148 }
149
150 #endif  /* __LINUX_POSIX_ACL_H */