1 #include <linux/export.h>
2 #include <linux/sched.h>
4 #include <linux/path.h>
5 #include <linux/slab.h>
6 #include <linux/fs_struct.h>
10 * Replace the fs->{rootmnt,root} with {mnt,dentry}. Put the old values.
13 void set_fs_root(struct fs_struct *fs, const struct path *path)
19 write_seqcount_begin(&fs->seq);
22 write_seqcount_end(&fs->seq);
23 spin_unlock(&fs->lock);
29 * Replace the fs->{pwdmnt,pwd} with {mnt,dentry}. Put the old values.
32 void set_fs_pwd(struct fs_struct *fs, const struct path *path)
38 write_seqcount_begin(&fs->seq);
41 write_seqcount_end(&fs->seq);
42 spin_unlock(&fs->lock);
48 static inline int replace_path(struct path *p, const struct path *old, const struct path *new)
50 if (likely(p->dentry != old->dentry || p->mnt != old->mnt))
56 void chroot_fs_refs(const struct path *old_root, const struct path *new_root)
58 struct task_struct *g, *p;
62 read_lock(&tasklist_lock);
63 do_each_thread(g, p) {
69 write_seqcount_begin(&fs->seq);
70 hits += replace_path(&fs->root, old_root, new_root);
71 hits += replace_path(&fs->pwd, old_root, new_root);
72 write_seqcount_end(&fs->seq);
77 spin_unlock(&fs->lock);
80 } while_each_thread(g, p);
81 read_unlock(&tasklist_lock);
86 void free_fs_struct(struct fs_struct *fs)
90 kmem_cache_free(fs_cachep, fs);
93 void exit_fs(struct task_struct *tsk)
95 struct fs_struct *fs = tsk->fs;
100 spin_lock(&fs->lock);
103 spin_unlock(&fs->lock);
110 struct fs_struct *copy_fs_struct(struct fs_struct *old)
112 struct fs_struct *fs = kmem_cache_alloc(fs_cachep, GFP_KERNEL);
113 /* We don't need to lock fs - think why ;-) */
117 spin_lock_init(&fs->lock);
118 seqcount_init(&fs->seq);
119 fs->umask = old->umask;
121 spin_lock(&old->lock);
122 fs->root = old->root;
126 spin_unlock(&old->lock);
131 int unshare_fs_struct(void)
133 struct fs_struct *fs = current->fs;
134 struct fs_struct *new_fs = copy_fs_struct(fs);
141 spin_lock(&fs->lock);
143 current->fs = new_fs;
144 spin_unlock(&fs->lock);
145 task_unlock(current);
152 EXPORT_SYMBOL_GPL(unshare_fs_struct);
154 int current_umask(void)
156 return current->fs->umask;
158 EXPORT_SYMBOL(current_umask);
160 /* to be mentioned only in INIT_TASK */
161 struct fs_struct init_fs = {
163 .lock = __SPIN_LOCK_UNLOCKED(init_fs.lock),
164 .seq = SEQCNT_ZERO(init_fs.seq),