#include <linux/module.h>
#include <linux/sched.h>
#include <linux/fs.h>
#include <linux/path.h>
#include <linux/slab.h>
#include <linux/fs_struct.h>
/*
* Replace the fs->{rootmnt,root} with {mnt,dentry}. Put the old values.
* It can block.
*/
void set_fs_root(struct fs_struct *fs, struct path *path)
{
struct path old_root;
write_lock(&fs->lock);
old_root = fs->root;
fs->root = *path;
path_get(path);
write_unlock(&fs->lock);
if (old_root.dentry)
path_put(&old_root);
}
* Replace the fs->{pwdmnt,pwd} with {mnt,dentry}. Put the old values.
void set_fs_pwd(struct fs_struct *fs, struct path *path)
struct path old_pwd;
old_pwd = fs->pwd;
fs->pwd = *path;
if (old_pwd.dentry)
path_put(&old_pwd);
void chroot_fs_refs(struct path *old_root, struct path *new_root)
struct task_struct *g, *p;
struct fs_struct *fs;
int count = 0;
read_lock(&tasklist_lock);
do_each_thread(g, p) {
task_lock(p);
fs = p->fs;
if (fs) {
if (fs->root.dentry == old_root->dentry
&& fs->root.mnt == old_root->mnt) {
path_get(new_root);
fs->root = *new_root;
count++;
if (fs->pwd.dentry == old_root->dentry
&& fs->pwd.mnt == old_root->mnt) {
fs->pwd = *new_root;
task_unlock(p);
} while_each_thread(g, p);
read_unlock(&tasklist_lock);
while (count--)
path_put(old_root);
void free_fs_struct(struct fs_struct *fs)
path_put(&fs->root);
path_put(&fs->pwd);
kmem_cache_free(fs_cachep, fs);
void exit_fs(struct task_struct *tsk)
struct fs_struct *fs = tsk->fs;
int kill;
task_lock(tsk);
tsk->fs = NULL;
kill = !--fs->users;
task_unlock(tsk);
if (kill)
free_fs_struct(fs);
struct fs_struct *copy_fs_struct(struct fs_struct *old)
struct fs_struct *fs = kmem_cache_alloc(fs_cachep, GFP_KERNEL);
/* We don't need to lock fs - think why ;-) */
fs->users = 1;
fs->in_exec = 0;
rwlock_init(&fs->lock);
fs->umask = old->umask;
read_lock(&old->lock);
fs->root = old->root;
path_get(&old->root);
fs->pwd = old->pwd;
path_get(&old->pwd);
read_unlock(&old->lock);
return fs;
int unshare_fs_struct(void)
struct fs_struct *fs = current->fs;
struct fs_struct *new_fs = copy_fs_struct(fs);
if (!new_fs)
return -ENOMEM;
task_lock(current);
current->fs = new_fs;
task_unlock(current);
return 0;
EXPORT_SYMBOL_GPL(unshare_fs_struct);
int current_umask(void)
return current->fs->umask;
EXPORT_SYMBOL(current_umask);
/* to be mentioned only in INIT_TASK */
struct fs_struct init_fs = {
.users = 1,
.lock = __RW_LOCK_UNLOCKED(init_fs.lock),
.umask = 0022,
};
void daemonize_fs_struct(void)
write_lock(&init_fs.lock);
init_fs.users++;
write_unlock(&init_fs.lock);
current->fs = &init_fs;