Atheros Kconfig needs to be dependent on WLAN_80211
[linux-2.6.git] / fs / fs_struct.c
1 #include <linux/module.h>
2 #include <linux/sched.h>
3 #include <linux/fs.h>
4 #include <linux/path.h>
5 #include <linux/slab.h>
6 #include <linux/fs_struct.h>
7
8 /*
9  * Replace the fs->{rootmnt,root} with {mnt,dentry}. Put the old values.
10  * It can block.
11  */
12 void set_fs_root(struct fs_struct *fs, struct path *path)
13 {
14         struct path old_root;
15
16         write_lock(&fs->lock);
17         old_root = fs->root;
18         fs->root = *path;
19         path_get(path);
20         write_unlock(&fs->lock);
21         if (old_root.dentry)
22                 path_put(&old_root);
23 }
24
25 /*
26  * Replace the fs->{pwdmnt,pwd} with {mnt,dentry}. Put the old values.
27  * It can block.
28  */
29 void set_fs_pwd(struct fs_struct *fs, struct path *path)
30 {
31         struct path old_pwd;
32
33         write_lock(&fs->lock);
34         old_pwd = fs->pwd;
35         fs->pwd = *path;
36         path_get(path);
37         write_unlock(&fs->lock);
38
39         if (old_pwd.dentry)
40                 path_put(&old_pwd);
41 }
42
43 void chroot_fs_refs(struct path *old_root, struct path *new_root)
44 {
45         struct task_struct *g, *p;
46         struct fs_struct *fs;
47         int count = 0;
48
49         read_lock(&tasklist_lock);
50         do_each_thread(g, p) {
51                 task_lock(p);
52                 fs = p->fs;
53                 if (fs) {
54                         write_lock(&fs->lock);
55                         if (fs->root.dentry == old_root->dentry
56                             && fs->root.mnt == old_root->mnt) {
57                                 path_get(new_root);
58                                 fs->root = *new_root;
59                                 count++;
60                         }
61                         if (fs->pwd.dentry == old_root->dentry
62                             && fs->pwd.mnt == old_root->mnt) {
63                                 path_get(new_root);
64                                 fs->pwd = *new_root;
65                                 count++;
66                         }
67                         write_unlock(&fs->lock);
68                 }
69                 task_unlock(p);
70         } while_each_thread(g, p);
71         read_unlock(&tasklist_lock);
72         while (count--)
73                 path_put(old_root);
74 }
75
76 void free_fs_struct(struct fs_struct *fs)
77 {
78         path_put(&fs->root);
79         path_put(&fs->pwd);
80         kmem_cache_free(fs_cachep, fs);
81 }
82
83 void exit_fs(struct task_struct *tsk)
84 {
85         struct fs_struct *fs = tsk->fs;
86
87         if (fs) {
88                 int kill;
89                 task_lock(tsk);
90                 write_lock(&fs->lock);
91                 tsk->fs = NULL;
92                 kill = !--fs->users;
93                 write_unlock(&fs->lock);
94                 task_unlock(tsk);
95                 if (kill)
96                         free_fs_struct(fs);
97         }
98 }
99
100 struct fs_struct *copy_fs_struct(struct fs_struct *old)
101 {
102         struct fs_struct *fs = kmem_cache_alloc(fs_cachep, GFP_KERNEL);
103         /* We don't need to lock fs - think why ;-) */
104         if (fs) {
105                 fs->users = 1;
106                 fs->in_exec = 0;
107                 rwlock_init(&fs->lock);
108                 fs->umask = old->umask;
109                 read_lock(&old->lock);
110                 fs->root = old->root;
111                 path_get(&old->root);
112                 fs->pwd = old->pwd;
113                 path_get(&old->pwd);
114                 read_unlock(&old->lock);
115         }
116         return fs;
117 }
118
119 int unshare_fs_struct(void)
120 {
121         struct fs_struct *fs = current->fs;
122         struct fs_struct *new_fs = copy_fs_struct(fs);
123         int kill;
124
125         if (!new_fs)
126                 return -ENOMEM;
127
128         task_lock(current);
129         write_lock(&fs->lock);
130         kill = !--fs->users;
131         current->fs = new_fs;
132         write_unlock(&fs->lock);
133         task_unlock(current);
134
135         if (kill)
136                 free_fs_struct(fs);
137
138         return 0;
139 }
140 EXPORT_SYMBOL_GPL(unshare_fs_struct);
141
142 int current_umask(void)
143 {
144         return current->fs->umask;
145 }
146 EXPORT_SYMBOL(current_umask);
147
148 /* to be mentioned only in INIT_TASK */
149 struct fs_struct init_fs = {
150         .users          = 1,
151         .lock           = __RW_LOCK_UNLOCKED(init_fs.lock),
152         .umask          = 0022,
153 };
154
155 void daemonize_fs_struct(void)
156 {
157         struct fs_struct *fs = current->fs;
158
159         if (fs) {
160                 int kill;
161
162                 task_lock(current);
163
164                 write_lock(&init_fs.lock);
165                 init_fs.users++;
166                 write_unlock(&init_fs.lock);
167
168                 write_lock(&fs->lock);
169                 current->fs = &init_fs;
170                 kill = !--fs->users;
171                 write_unlock(&fs->lock);
172
173                 task_unlock(current);
174                 if (kill)
175                         free_fs_struct(fs);
176         }
177 }