Linux-2.6.12-rc2v2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

1 files changed, 1465 insertions, 0 deletions

diff --git a/fs/namespace.c b/fs/namespace.c
new file mode 100644
index 0000000..3b93e5d
--- /dev/null
+++ b/fs/namespace.c
@@ -0,0 +1,1465 @@
+/*
+ *  linux/fs/namespace.c
+ *
+ * (C) Copyright Al Viro 2000, 2001
+ *	Released under GPL v2.
+ *
+ * Based on code from fs/super.c, copyright Linus Torvalds and others.
+ * Heavily rewritten.
+ */
+
+#include <linux/config.h>
+#include <linux/syscalls.h>
+#include <linux/slab.h>
+#include <linux/sched.h>
+#include <linux/smp_lock.h>
+#include <linux/init.h>
+#include <linux/quotaops.h>
+#include <linux/acct.h>
+#include <linux/module.h>
+#include <linux/seq_file.h>
+#include <linux/namespace.h>
+#include <linux/namei.h>
+#include <linux/security.h>
+#include <linux/mount.h>
+#include <asm/uaccess.h>
+#include <asm/unistd.h>
+
+extern int __init init_rootfs(void);
+
+#ifdef CONFIG_SYSFS
+extern int __init sysfs_init(void);
+#else
+static inline int sysfs_init(void)
+{
+	return 0;
+}
+#endif
+
+/* spinlock for vfsmount related operations, inplace of dcache_lock */
+ __cacheline_aligned_in_smp DEFINE_SPINLOCK(vfsmount_lock);
+
+static struct list_head *mount_hashtable;
+static int hash_mask, hash_bits;
+static kmem_cache_t *mnt_cache; 
+
+static inline unsigned long hash(struct vfsmount *mnt, struct dentry *dentry)
+{
+	unsigned long tmp = ((unsigned long) mnt / L1_CACHE_BYTES);
+	tmp += ((unsigned long) dentry / L1_CACHE_BYTES);
+	tmp = tmp + (tmp >> hash_bits);
+	return tmp & hash_mask;
+}
+
+struct vfsmount *alloc_vfsmnt(const char *name)
+{
+	struct vfsmount *mnt = kmem_cache_alloc(mnt_cache, GFP_KERNEL); 
+	if (mnt) {
+		memset(mnt, 0, sizeof(struct vfsmount));
+		atomic_set(&mnt->mnt_count,1);
+		INIT_LIST_HEAD(&mnt->mnt_hash);
+		INIT_LIST_HEAD(&mnt->mnt_child);
+		INIT_LIST_HEAD(&mnt->mnt_mounts);
+		INIT_LIST_HEAD(&mnt->mnt_list);
+		INIT_LIST_HEAD(&mnt->mnt_fslink);
+		if (name) {
+			int size = strlen(name)+1;
+			char *newname = kmalloc(size, GFP_KERNEL);
+			if (newname) {
+				memcpy(newname, name, size);
+				mnt->mnt_devname = newname;
+			}
+		}
+	}
+	return mnt;
+}
+
+void free_vfsmnt(struct vfsmount *mnt)
+{
+	kfree(mnt->mnt_devname);
+	kmem_cache_free(mnt_cache, mnt);
+}
+
+/*
+ * Now, lookup_mnt increments the ref count before returning
+ * the vfsmount struct.
+ */
+struct vfsmount *lookup_mnt(struct vfsmount *mnt, struct dentry *dentry)
+{
+	struct list_head * head = mount_hashtable + hash(mnt, dentry);
+	struct list_head * tmp = head;
+	struct vfsmount *p, *found = NULL;
+
+	spin_lock(&vfsmount_lock);
+	for (;;) {
+		tmp = tmp->next;
+		p = NULL;
+		if (tmp == head)
+			break;
+		p = list_entry(tmp, struct vfsmount, mnt_hash);
+		if (p->mnt_parent == mnt && p->mnt_mountpoint == dentry) {
+			found = mntget(p);
+			break;
+		}
+	}
+	spin_unlock(&vfsmount_lock);
+	return found;
+}
+
+static inline int check_mnt(struct vfsmount *mnt)
+{
+	return mnt->mnt_namespace == current->namespace;
+}
+
+static void detach_mnt(struct vfsmount *mnt, struct nameidata *old_nd)
+{
+	old_nd->dentry = mnt->mnt_mountpoint;
+	old_nd->mnt = mnt->mnt_parent;
+	mnt->mnt_parent = mnt;
+	mnt->mnt_mountpoint = mnt->mnt_root;
+	list_del_init(&mnt->mnt_child);
+	list_del_init(&mnt->mnt_hash);
+	old_nd->dentry->d_mounted--;
+}
+
+static void attach_mnt(struct vfsmount *mnt, struct nameidata *nd)
+{
+	mnt->mnt_parent = mntget(nd->mnt);
+	mnt->mnt_mountpoint = dget(nd->dentry);
+	list_add(&mnt->mnt_hash, mount_hashtable+hash(nd->mnt, nd->dentry));
+	list_add_tail(&mnt->mnt_child, &nd->mnt->mnt_mounts);
+	nd->dentry->d_mounted++;
+}
+
+static struct vfsmount *next_mnt(struct vfsmount *p, struct vfsmount *root)
+{
+	struct list_head *next = p->mnt_mounts.next;
+	if (next == &p->mnt_mounts) {
+		while (1) {
+			if (p == root)
+				return NULL;
+			next = p->mnt_child.next;
+			if (next != &p->mnt_parent->mnt_mounts)
+				break;
+			p = p->mnt_parent;
+		}
+	}
+	return list_entry(next, struct vfsmount, mnt_child);
+}
+
+static struct vfsmount *
+clone_mnt(struct vfsmount *old, struct dentry *root)
+{
+	struct super_block *sb = old->mnt_sb;
+	struct vfsmount *mnt = alloc_vfsmnt(old->mnt_devname);
+
+	if (mnt) {
+		mnt->mnt_flags = old->mnt_flags;
+		atomic_inc(&sb->s_active);
+		mnt->mnt_sb = sb;
+		mnt->mnt_root = dget(root);
+		mnt->mnt_mountpoint = mnt->mnt_root;
+		mnt->mnt_parent = mnt;
+		mnt->mnt_namespace = old->mnt_namespace;
+
+		/* stick the duplicate mount on the same expiry list
+		 * as the original if that was on one */
+		spin_lock(&vfsmount_lock);
+		if (!list_empty(&old->mnt_fslink))
+			list_add(&mnt->mnt_fslink, &old->mnt_fslink);
+		spin_unlock(&vfsmount_lock);
+	}
+	return mnt;
+}
+
+void __mntput(struct vfsmount *mnt)
+{
+	struct super_block *sb = mnt->mnt_sb;
+	dput(mnt->mnt_root);
+	free_vfsmnt(mnt);
+	deactivate_super(sb);
+}
+
+EXPORT_SYMBOL(__mntput);
+
+/* iterator */
+static void *m_start(struct seq_file *m, loff_t *pos)
+{
+	struct namespace *n = m->private;
+	struct list_head *p;
+	loff_t l = *pos;
+
+	down_read(&n->sem);
+	list_for_each(p, &n->list)
+		if (!l--)
+			return list_entry(p, struct vfsmount, mnt_list);
+	return NULL;
+}
+
+static void *m_next(struct seq_file *m, void *v, loff_t *pos)
+{
+	struct namespace *n = m->private;
+	struct list_head *p = ((struct vfsmount *)v)->mnt_list.next;
+	(*pos)++;
+	return p==&n->list ? NULL : list_entry(p, struct vfsmount, mnt_list);
+}
+
+static void m_stop(struct seq_file *m, void *v)
+{
+	struct namespace *n = m->private;
+	up_read(&n->sem);
+}
+
+static inline void mangle(struct seq_file *m, const char *s)
+{
+	seq_escape(m, s, " \t\n\\");
+}
+
+static int show_vfsmnt(struct seq_file *m, void *v)
+{
+	struct vfsmount *mnt = v;
+	int err = 0;
+	static struct proc_fs_info {
+		int flag;
+		char *str;
+	} fs_info[] = {
+		{ MS_SYNCHRONOUS, ",sync" },
+		{ MS_DIRSYNC, ",dirsync" },
+		{ MS_MANDLOCK, ",mand" },
+		{ MS_NOATIME, ",noatime" },
+		{ MS_NODIRATIME, ",nodiratime" },
+		{ 0, NULL }
+	};
+	static struct proc_fs_info mnt_info[] = {
+		{ MNT_NOSUID, ",nosuid" },
+		{ MNT_NODEV, ",nodev" },
+		{ MNT_NOEXEC, ",noexec" },
+		{ 0, NULL }
+	};
+	struct proc_fs_info *fs_infop;
+
+	mangle(m, mnt->mnt_devname ? mnt->mnt_devname : "none");
+	seq_putc(m, ' ');
+	seq_path(m, mnt, mnt->mnt_root, " \t\n\\");
+	seq_putc(m, ' ');
+	mangle(m, mnt->mnt_sb->s_type->name);
+	seq_puts(m, mnt->mnt_sb->s_flags & MS_RDONLY ? " ro" : " rw");
+	for (fs_infop = fs_info; fs_infop->flag; fs_infop++) {
+		if (mnt->mnt_sb->s_flags & fs_infop->flag)
+			seq_puts(m, fs_infop->str);
+	}
+	for (fs_infop = mnt_info; fs_infop->flag; fs_infop++) {
+		if (mnt->mnt_flags & fs_infop->flag)
+			seq_puts(m, fs_infop->str);
+	}
+	if (mnt->mnt_sb->s_op->show_options)
+		err = mnt->mnt_sb->s_op->show_options(m, mnt);
+	seq_puts(m, " 0 0\n");
+	return err;
+}
+
+struct seq_operations mounts_op = {
+	.start	= m_start,
+	.next	= m_next,
+	.stop	= m_stop,
+	.show	= show_vfsmnt
+};
+
+/**
+ * may_umount_tree - check if a mount tree is busy
+ * @mnt: root of mount tree
+ *
+ * This is called to check if a tree of mounts has any
+ * open files, pwds, chroots or sub mounts that are
+ * busy.
+ */
+int may_umount_tree(struct vfsmount *mnt)
+{
+	struct list_head *next;
+	struct vfsmount *this_parent = mnt;
+	int actual_refs;
+	int minimum_refs;
+
+	spin_lock(&vfsmount_lock);
+	actual_refs = atomic_read(&mnt->mnt_count);
+	minimum_refs = 2;
+repeat:
+	next = this_parent->mnt_mounts.next;
+resume:
+	while (next != &this_parent->mnt_mounts) {
+		struct vfsmount *p = list_entry(next, struct vfsmount, mnt_child);
+
+		next = next->next;
+
+		actual_refs += atomic_read(&p->mnt_count);
+		minimum_refs += 2;
+
+		if (!list_empty(&p->mnt_mounts)) {
+			this_parent = p;
+			goto repeat;
+		}
+	}
+
+	if (this_parent != mnt) {
+		next = this_parent->mnt_child.next;
+		this_parent = this_parent->mnt_parent;
+		goto resume;
+	}
+	spin_unlock(&vfsmount_lock);
+
+	if (actual_refs > minimum_refs)
+		return -EBUSY;
+
+	return 0;
+}
+
+EXPORT_SYMBOL(may_umount_tree);
+
+/**
+ * may_umount - check if a mount point is busy
+ * @mnt: root of mount
+ *
+ * This is called to check if a mount point has any
+ * open files, pwds, chroots or sub mounts. If the
+ * mount has sub mounts this will return busy
+ * regardless of whether the sub mounts are busy.
+ *
+ * Doesn't take quota and stuff into account. IOW, in some cases it will
+ * give false negatives. The main reason why it's here is that we need
+ * a non-destructive way to look for easily umountable filesystems.
+ */
+int may_umount(struct vfsmount *mnt)
+{
+	if (atomic_read(&mnt->mnt_count) > 2)
+		return -EBUSY;
+	return 0;
+}
+
+EXPORT_SYMBOL(may_umount);
+
+void umount_tree(struct vfsmount *mnt)
+{
+	struct vfsmount *p;
+	LIST_HEAD(kill);
+
+	for (p = mnt; p; p = next_mnt(p, mnt)) {
+		list_del(&p->mnt_list);
+		list_add(&p->mnt_list, &kill);
+	}
+
+	while (!list_empty(&kill)) {
+		mnt = list_entry(kill.next, struct vfsmount, mnt_list);
+		list_del_init(&mnt->mnt_list);
+		list_del_init(&mnt->mnt_fslink);
+		if (mnt->mnt_parent == mnt) {
+			spin_unlock(&vfsmount_lock);
+		} else {
+			struct nameidata old_nd;
+			detach_mnt(mnt, &old_nd);
+			spin_unlock(&vfsmount_lock);
+			path_release(&old_nd);
+		}
+		mntput(mnt);
+		spin_lock(&vfsmount_lock);
+	}
+}
+
+static int do_umount(struct vfsmount *mnt, int flags)
+{
+	struct super_block * sb = mnt->mnt_sb;
+	int retval;
+
+	retval = security_sb_umount(mnt, flags);
+	if (retval)
+		return retval;
+
+	/*
+	 * Allow userspace to request a mountpoint be expired rather than
+	 * unmounting unconditionally. Unmount only happens if:
+	 *  (1) the mark is already set (the mark is cleared by mntput())
+	 *  (2) the usage count == 1 [parent vfsmount] + 1 [sys_umount]
+	 */
+	if (flags & MNT_EXPIRE) {
+		if (mnt == current->fs->rootmnt ||
+		    flags & (MNT_FORCE | MNT_DETACH))
+			return -EINVAL;
+
+		if (atomic_read(&mnt->mnt_count) != 2)
+			return -EBUSY;
+
+		if (!xchg(&mnt->mnt_expiry_mark, 1))
+			return -EAGAIN;
+	}
+
+	/*
+	 * If we may have to abort operations to get out of this
+	 * mount, and they will themselves hold resources we must
+	 * allow the fs to do things. In the Unix tradition of
+	 * 'Gee thats tricky lets do it in userspace' the umount_begin
+	 * might fail to complete on the first run through as other tasks
+	 * must return, and the like. Thats for the mount program to worry
+	 * about for the moment.
+	 */
+
+	lock_kernel();
+	if( (flags&MNT_FORCE) && sb->s_op->umount_begin)
+		sb->s_op->umount_begin(sb);
+	unlock_kernel();
+
+	/*
+	 * No sense to grab the lock for this test, but test itself looks
+	 * somewhat bogus. Suggestions for better replacement?
+	 * Ho-hum... In principle, we might treat that as umount + switch
+	 * to rootfs. GC would eventually take care of the old vfsmount.
+	 * Actually it makes sense, especially if rootfs would contain a
+	 * /reboot - static binary that would close all descriptors and
+	 * call reboot(9). Then init(8) could umount root and exec /reboot.
+	 */
+	if (mnt == current->fs->rootmnt && !(flags & MNT_DETACH)) {
+		/*
+		 * Special case for "unmounting" root ...
+		 * we just try to remount it readonly.
+		 */
+		down_write(&sb->s_umount);
+		if (!(sb->s_flags & MS_RDONLY)) {
+			lock_kernel();
+			DQUOT_OFF(sb);
+			retval = do_remount_sb(sb, MS_RDONLY, NULL, 0);
+			unlock_kernel();
+		}
+		up_write(&sb->s_umount);
+		return retval;
+	}
+
+	down_write(&current->namespace->sem);
+	spin_lock(&vfsmount_lock);
+
+	if (atomic_read(&sb->s_active) == 1) {
+		/* last instance - try to be smart */
+		spin_unlock(&vfsmount_lock);
+		lock_kernel();
+		DQUOT_OFF(sb);
+		acct_auto_close(sb);
+		unlock_kernel();
+		security_sb_umount_close(mnt);
+		spin_lock(&vfsmount_lock);
+	}
+	retval = -EBUSY;
+	if (atomic_read(&mnt->mnt_count) == 2 || flags & MNT_DETACH) {
+		if (!list_empty(&mnt->mnt_list))
+			umount_tree(mnt);
+		retval = 0;
+	}
+	spin_unlock(&vfsmount_lock);
+	if (retval)
+		security_sb_umount_busy(mnt);
+	up_write(&current->namespace->sem);
+	return retval;
+}
+
+/*
+ * Now umount can handle mount points as well as block devices.
+ * This is important for filesystems which use unnamed block devices.
+ *
+ * We now support a flag for forced unmount like the other 'big iron'
+ * unixes. Our API is identical to OSF/1 to avoid making a mess of AMD
+ */
+
+asmlinkage long sys_umount(char __user * name, int flags)
+{
+	struct nameidata nd;
+	int retval;
+
+	retval = __user_walk(name, LOOKUP_FOLLOW, &nd);
+	if (retval)
+		goto out;
+	retval = -EINVAL;
+	if (nd.dentry != nd.mnt->mnt_root)
+		goto dput_and_out;
+	if (!check_mnt(nd.mnt))
+		goto dput_and_out;
+
+	retval = -EPERM;
+	if (!capable(CAP_SYS_ADMIN))
+		goto dput_and_out;
+
+	retval = do_umount(nd.mnt, flags);
+dput_and_out:
+	path_release_on_umount(&nd);
+out:
+	return retval;
+}
+
+#ifdef __ARCH_WANT_SYS_OLDUMOUNT
+
+/*
+ *	The 2.0 compatible umount. No flags. 
+ */
+ 
+asmlinkage long sys_oldumount(char __user * name)
+{
+	return sys_umount(name,0);
+}
+
+#endif
+
+static int mount_is_safe(struct nameidata *nd)
+{
+	if (capable(CAP_SYS_ADMIN))
+		return 0;
+	return -EPERM;
+#ifdef notyet
+	if (S_ISLNK(nd->dentry->d_inode->i_mode))
+		return -EPERM;
+	if (nd->dentry->d_inode->i_mode & S_ISVTX) {
+		if (current->uid != nd->dentry->d_inode->i_uid)
+			return -EPERM;
+	}
+	if (permission(nd->dentry->d_inode, MAY_WRITE, nd))
+		return -EPERM;
+	return 0;
+#endif
+}
+
+static int
+lives_below_in_same_fs(struct dentry *d, struct dentry *dentry)
+{
+	while (1) {
+		if (d == dentry)
+			return 1;
+		if (d == NULL || d == d->d_parent)
+			return 0;
+		d = d->d_parent;
+	}
+}
+
+static struct vfsmount *copy_tree(struct vfsmount *mnt, struct dentry *dentry)
+{
+	struct vfsmount *res, *p, *q, *r, *s;
+	struct list_head *h;
+	struct nameidata nd;
+
+	res = q = clone_mnt(mnt, dentry);
+	if (!q)
+		goto Enomem;
+	q->mnt_mountpoint = mnt->mnt_mountpoint;
+
+	p = mnt;
+	for (h = mnt->mnt_mounts.next; h != &mnt->mnt_mounts; h = h->next) {
+		r = list_entry(h, struct vfsmount, mnt_child);
+		if (!lives_below_in_same_fs(r->mnt_mountpoint, dentry))
+			continue;
+
+		for (s = r; s; s = next_mnt(s, r)) {
+			while (p != s->mnt_parent) {
+				p = p->mnt_parent;
+				q = q->mnt_parent;
+			}
+			p = s;
+			nd.mnt = q;
+			nd.dentry = p->mnt_mountpoint;
+			q = clone_mnt(p, p->mnt_root);
+			if (!q)
+				goto Enomem;
+			spin_lock(&vfsmount_lock);
+			list_add_tail(&q->mnt_list, &res->mnt_list);
+			attach_mnt(q, &nd);
+			spin_unlock(&vfsmount_lock);
+		}
+	}
+	return res;
+ Enomem:
+	if (res) {
+		spin_lock(&vfsmount_lock);
+		umount_tree(res);
+		spin_unlock(&vfsmount_lock);
+	}
+	return NULL;
+}
+
+static int graft_tree(struct vfsmount *mnt, struct nameidata *nd)
+{
+	int err;
+	if (mnt->mnt_sb->s_flags & MS_NOUSER)
+		return -EINVAL;
+
+	if (S_ISDIR(nd->dentry->d_inode->i_mode) !=
+	      S_ISDIR(mnt->mnt_root->d_inode->i_mode))
+		return -ENOTDIR;
+
+	err = -ENOENT;
+	down(&nd->dentry->d_inode->i_sem);
+	if (IS_DEADDIR(nd->dentry->d_inode))
+		goto out_unlock;
+
+	err = security_sb_check_sb(mnt, nd);
+	if (err)
+		goto out_unlock;
+
+	err = -ENOENT;
+	spin_lock(&vfsmount_lock);
+	if (IS_ROOT(nd->dentry) || !d_unhashed(nd->dentry)) {
+		struct list_head head;
+
+		attach_mnt(mnt, nd);
+		list_add_tail(&head, &mnt->mnt_list);
+		list_splice(&head, current->namespace->list.prev);
+		mntget(mnt);
+		err = 0;
+	}
+	spin_unlock(&vfsmount_lock);
+out_unlock:
+	up(&nd->dentry->d_inode->i_sem);
+	if (!err)
+		security_sb_post_addmount(mnt, nd);
+	return err;
+}
+
+/*
+ * do loopback mount.
+ */
+static int do_loopback(struct nameidata *nd, char *old_name, int recurse)
+{
+	struct nameidata old_nd;
+	struct vfsmount *mnt = NULL;
+	int err = mount_is_safe(nd);
+	if (err)
+		return err;
+	if (!old_name || !*old_name)
+		return -EINVAL;
+	err = path_lookup(old_name, LOOKUP_FOLLOW, &old_nd);
+	if (err)
+		return err;
+
+	down_write(&current->namespace->sem);
+	err = -EINVAL;
+	if (check_mnt(nd->mnt) && (!recurse || check_mnt(old_nd.mnt))) {
+		err = -ENOMEM;
+		if (recurse)
+			mnt = copy_tree(old_nd.mnt, old_nd.dentry);
+		else
+			mnt = clone_mnt(old_nd.mnt, old_nd.dentry);
+	}
+
+	if (mnt) {
+		/* stop bind mounts from expiring */
+		spin_lock(&vfsmount_lock);
+		list_del_init(&mnt->mnt_fslink);
+		spin_unlock(&vfsmount_lock);
+
+		err = graft_tree(mnt, nd);
+		if (err) {
+			spin_lock(&vfsmount_lock);
+			umount_tree(mnt);
+			spin_unlock(&vfsmount_lock);
+		} else
+			mntput(mnt);
+	}
+
+	up_write(&current->namespace->sem);
+	path_release(&old_nd);
+	return err;
+}
+
+/*
+ * change filesystem flags. dir should be a physical root of filesystem.
+ * If you've mounted a non-root directory somewhere and want to do remount
+ * on it - tough luck.
+ */
+
+static int do_remount(struct nameidata *nd, int flags, int mnt_flags,
+		      void *data)
+{
+	int err;
+	struct super_block * sb = nd->mnt->mnt_sb;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	if (!check_mnt(nd->mnt))
+		return -EINVAL;
+
+	if (nd->dentry != nd->mnt->mnt_root)
+		return -EINVAL;
+
+	down_write(&sb->s_umount);
+	err = do_remount_sb(sb, flags, data, 0);
+	if (!err)
+		nd->mnt->mnt_flags=mnt_flags;
+	up_write(&sb->s_umount);
+	if (!err)
+		security_sb_post_remount(nd->mnt, flags, data);
+	return err;
+}
+
+static int do_move_mount(struct nameidata *nd, char *old_name)
+{
+	struct nameidata old_nd, parent_nd;
+	struct vfsmount *p;
+	int err = 0;
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+	if (!old_name || !*old_name)
+		return -EINVAL;
+	err = path_lookup(old_name, LOOKUP_FOLLOW, &old_nd);
+	if (err)
+		return err;
+
+	down_write(&current->namespace->sem);
+	while(d_mountpoint(nd->dentry) && follow_down(&nd->mnt, &nd->dentry))
+		;
+	err = -EINVAL;
+	if (!check_mnt(nd->mnt) || !check_mnt(old_nd.mnt))
+		goto out;
+
+	err = -ENOENT;
+	down(&nd->dentry->d_inode->i_sem);
+	if (IS_DEADDIR(nd->dentry->d_inode))
+		goto out1;
+
+	spin_lock(&vfsmount_lock);
+	if (!IS_ROOT(nd->dentry) && d_unhashed(nd->dentry))
+		goto out2;
+
+	err = -EINVAL;
+	if (old_nd.dentry != old_nd.mnt->mnt_root)
+		goto out2;
+
+	if (old_nd.mnt == old_nd.mnt->mnt_parent)
+		goto out2;
+
+	if (S_ISDIR(nd->dentry->d_inode->i_mode) !=
+	      S_ISDIR(old_nd.dentry->d_inode->i_mode))
+		goto out2;
+
+	err = -ELOOP;
+	for (p = nd->mnt; p->mnt_parent!=p; p = p->mnt_parent)
+		if (p == old_nd.mnt)
+			goto out2;
+	err = 0;
+
+	detach_mnt(old_nd.mnt, &parent_nd);
+	attach_mnt(old_nd.mnt, nd);
+
+	/* if the mount is moved, it should no longer be expire
+	 * automatically */
+	list_del_init(&old_nd.mnt->mnt_fslink);
+out2:
+	spin_unlock(&vfsmount_lock);
+out1:
+	up(&nd->dentry->d_inode->i_sem);
+out:
+	up_write(&current->namespace->sem);
+	if (!err)
+		path_release(&parent_nd);
+	path_release(&old_nd);
+	return err;
+}
+
+/*
+ * create a new mount for userspace and request it to be added into the
+ * namespace's tree
+ */
+static int do_new_mount(struct nameidata *nd, char *type, int flags,
+			int mnt_flags, char *name, void *data)
+{
+	struct vfsmount *mnt;
+
+	if (!type || !memchr(type, 0, PAGE_SIZE))
+		return -EINVAL;
+
+	/* we need capabilities... */
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	mnt = do_kern_mount(type, flags, name, data);
+	if (IS_ERR(mnt))
+		return PTR_ERR(mnt);
+
+	return do_add_mount(mnt, nd, mnt_flags, NULL);
+}
+
+/*
+ * add a mount into a namespace's mount tree
+ * - provide the option of adding the new mount to an expiration list
+ */
+int do_add_mount(struct vfsmount *newmnt, struct nameidata *nd,
+		 int mnt_flags, struct list_head *fslist)
+{
+	int err;
+
+	down_write(&current->namespace->sem);
+	/* Something was mounted here while we slept */
+	while(d_mountpoint(nd->dentry) && follow_down(&nd->mnt, &nd->dentry))
+		;
+	err = -EINVAL;
+	if (!check_mnt(nd->mnt))
+		goto unlock;
+
+	/* Refuse the same filesystem on the same mount point */
+	err = -EBUSY;
+	if (nd->mnt->mnt_sb == newmnt->mnt_sb &&
+	    nd->mnt->mnt_root == nd->dentry)
+		goto unlock;
+
+	err = -EINVAL;
+	if (S_ISLNK(newmnt->mnt_root->d_inode->i_mode))
+		goto unlock;
+
+	newmnt->mnt_flags = mnt_flags;
+	err = graft_tree(newmnt, nd);
+
+	if (err == 0 && fslist) {
+		/* add to the specified expiration list */
+		spin_lock(&vfsmount_lock);
+		list_add_tail(&newmnt->mnt_fslink, fslist);
+		spin_unlock(&vfsmount_lock);
+	}
+
+unlock:
+	up_write(&current->namespace->sem);
+	mntput(newmnt);
+	return err;
+}
+
+EXPORT_SYMBOL_GPL(do_add_mount);
+
+/*
+ * process a list of expirable mountpoints with the intent of discarding any
+ * mountpoints that aren't in use and haven't been touched since last we came
+ * here
+ */
+void mark_mounts_for_expiry(struct list_head *mounts)
+{
+	struct namespace *namespace;
+	struct vfsmount *mnt, *next;
+	LIST_HEAD(graveyard);
+
+	if (list_empty(mounts))
+		return;
+
+	spin_lock(&vfsmount_lock);
+
+	/* extract from the expiration list every vfsmount that matches the
+	 * following criteria:
+	 * - only referenced by its parent vfsmount
+	 * - still marked for expiry (marked on the last call here; marks are
+	 *   cleared by mntput())
+	 */
+	list_for_each_entry_safe(mnt, next, mounts, mnt_fslink) {
+		if (!xchg(&mnt->mnt_expiry_mark, 1) ||
+		    atomic_read(&mnt->mnt_count) != 1)
+			continue;
+
+		mntget(mnt);
+		list_move(&mnt->mnt_fslink, &graveyard);
+	}
+
+	/*
+	 * go through the vfsmounts we've just consigned to the graveyard to
+	 * - check that they're still dead
+	 * - delete the vfsmount from the appropriate namespace under lock
+	 * - dispose of the corpse
+	 */
+	while (!list_empty(&graveyard)) {
+		mnt = list_entry(graveyard.next, struct vfsmount, mnt_fslink);
+		list_del_init(&mnt->mnt_fslink);
+
+		/* don't do anything if the namespace is dead - all the
+		 * vfsmounts from it are going away anyway */
+		namespace = mnt->mnt_namespace;
+		if (!namespace || atomic_read(&namespace->count) <= 0)
+			continue;
+		get_namespace(namespace);
+
+		spin_unlock(&vfsmount_lock);
+		down_write(&namespace->sem);
+		spin_lock(&vfsmount_lock);
+
+		/* check that it is still dead: the count should now be 2 - as
+		 * contributed by the vfsmount parent and the mntget above */
+		if (atomic_read(&mnt->mnt_count) == 2) {
+			struct vfsmount *xdmnt;
+			struct dentry *xdentry;
+
+			/* delete from the namespace */
+			list_del_init(&mnt->mnt_list);
+			list_del_init(&mnt->mnt_child);
+			list_del_init(&mnt->mnt_hash);
+			mnt->mnt_mountpoint->d_mounted--;
+
+			xdentry = mnt->mnt_mountpoint;
+			mnt->mnt_mountpoint = mnt->mnt_root;
+			xdmnt = mnt->mnt_parent;
+			mnt->mnt_parent = mnt;
+
+			spin_unlock(&vfsmount_lock);
+
+			mntput(xdmnt);
+			dput(xdentry);
+
+			/* now lay it to rest if this was the last ref on the
+			 * superblock */
+			if (atomic_read(&mnt->mnt_sb->s_active) == 1) {
+				/* last instance - try to be smart */
+				lock_kernel();
+				DQUOT_OFF(mnt->mnt_sb);
+				acct_auto_close(mnt->mnt_sb);
+				unlock_kernel();
+			}
+
+			mntput(mnt);
+		} else {
+			/* someone brought it back to life whilst we didn't
+			 * have any locks held so return it to the expiration
+			 * list */
+			list_add_tail(&mnt->mnt_fslink, mounts);
+			spin_unlock(&vfsmount_lock);
+		}
+
+		up_write(&namespace->sem);
+
+		mntput(mnt);
+		put_namespace(namespace);
+
+		spin_lock(&vfsmount_lock);
+	}
+
+	spin_unlock(&vfsmount_lock);
+}
+
+EXPORT_SYMBOL_GPL(mark_mounts_for_expiry);
+
+/*
+ * Some copy_from_user() implementations do not return the exact number of
+ * bytes remaining to copy on a fault.  But copy_mount_options() requires that.
+ * Note that this function differs from copy_from_user() in that it will oops
+ * on bad values of `to', rather than returning a short copy.
+ */
+static long
+exact_copy_from_user(void *to, const void __user *from, unsigned long n)
+{
+	char *t = to;
+	const char __user *f = from;
+	char c;
+
+	if (!access_ok(VERIFY_READ, from, n))
+		return n;
+
+	while (n) {
+		if (__get_user(c, f)) {
+			memset(t, 0, n);
+			break;
+		}
+		*t++ = c;
+		f++;
+		n--;
+	}
+	return n;
+}
+
+int copy_mount_options(const void __user *data, unsigned long *where)
+{
+	int i;
+	unsigned long page;
+	unsigned long size;
+	
+	*where = 0;
+	if (!data)
+		return 0;
+
+	if (!(page = __get_free_page(GFP_KERNEL)))
+		return -ENOMEM;
+
+	/* We only care that *some* data at the address the user
+	 * gave us is valid.  Just in case, we'll zero
+	 * the remainder of the page.
+	 */
+	/* copy_from_user cannot cross TASK_SIZE ! */
+	size = TASK_SIZE - (unsigned long)data;
+	if (size > PAGE_SIZE)
+		size = PAGE_SIZE;
+
+	i = size - exact_copy_from_user((void *)page, data, size);
+	if (!i) {
+		free_page(page); 
+		return -EFAULT;
+	}
+	if (i != PAGE_SIZE)
+		memset((char *)page + i, 0, PAGE_SIZE - i);
+	*where = page;
+	return 0;
+}
+
+/*
+ * Flags is a 32-bit value that allows up to 31 non-fs dependent flags to
+ * be given to the mount() call (ie: read-only, no-dev, no-suid etc).
+ *
+ * data is a (void *) that can point to any structure up to
+ * PAGE_SIZE-1 bytes, which can contain arbitrary fs-dependent
+ * information (or be NULL).
+ *
+ * Pre-0.97 versions of mount() didn't have a flags word.
+ * When the flags word was introduced its top half was required
+ * to have the magic value 0xC0ED, and this remained so until 2.4.0-test9.
+ * Therefore, if this magic number is present, it carries no information
+ * and must be discarded.
+ */
+long do_mount(char * dev_name, char * dir_name, char *type_page,
+		  unsigned long flags, void *data_page)
+{
+	struct nameidata nd;
+	int retval = 0;
+	int mnt_flags = 0;
+
+	/* Discard magic */
+	if ((flags & MS_MGC_MSK) == MS_MGC_VAL)
+		flags &= ~MS_MGC_MSK;
+
+	/* Basic sanity checks */
+
+	if (!dir_name || !*dir_name || !memchr(dir_name, 0, PAGE_SIZE))
+		return -EINVAL;
+	if (dev_name && !memchr(dev_name, 0, PAGE_SIZE))
+		return -EINVAL;
+
+	if (data_page)
+		((char *)data_page)[PAGE_SIZE - 1] = 0;
+
+	/* Separate the per-mountpoint flags */
+	if (flags & MS_NOSUID)
+		mnt_flags |= MNT_NOSUID;
+	if (flags & MS_NODEV)
+		mnt_flags |= MNT_NODEV;
+	if (flags & MS_NOEXEC)
+		mnt_flags |= MNT_NOEXEC;
+	flags &= ~(MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_ACTIVE);
+
+	/* ... and get the mountpoint */
+	retval = path_lookup(dir_name, LOOKUP_FOLLOW, &nd);
+	if (retval)
+		return retval;
+
+	retval = security_sb_mount(dev_name, &nd, type_page, flags, data_page);
+	if (retval)
+		goto dput_out;
+
+	if (flags & MS_REMOUNT)
+		retval = do_remount(&nd, flags & ~MS_REMOUNT, mnt_flags,
+				    data_page);
+	else if (flags & MS_BIND)
+		retval = do_loopback(&nd, dev_name, flags & MS_REC);
+	else if (flags & MS_MOVE)
+		retval = do_move_mount(&nd, dev_name);
+	else
+		retval = do_new_mount(&nd, type_page, flags, mnt_flags,
+				      dev_name, data_page);
+dput_out:
+	path_release(&nd);
+	return retval;
+}
+
+int copy_namespace(int flags, struct task_struct *tsk)
+{
+	struct namespace *namespace = tsk->namespace;
+	struct namespace *new_ns;
+	struct vfsmount *rootmnt = NULL, *pwdmnt = NULL, *altrootmnt = NULL;
+	struct fs_struct *fs = tsk->fs;
+	struct vfsmount *p, *q;
+
+	if (!namespace)
+		return 0;
+
+	get_namespace(namespace);
+
+	if (!(flags & CLONE_NEWNS))
+		return 0;
+
+	if (!capable(CAP_SYS_ADMIN)) {
+		put_namespace(namespace);
+		return -EPERM;
+	}
+
+	new_ns = kmalloc(sizeof(struct namespace), GFP_KERNEL);
+	if (!new_ns)
+		goto out;
+
+	atomic_set(&new_ns->count, 1);
+	init_rwsem(&new_ns->sem);
+	INIT_LIST_HEAD(&new_ns->list);
+
+	down_write(&tsk->namespace->sem);
+	/* First pass: copy the tree topology */
+	new_ns->root = copy_tree(namespace->root, namespace->root->mnt_root);
+	if (!new_ns->root) {
+		up_write(&tsk->namespace->sem);
+		kfree(new_ns);
+		goto out;
+	}
+	spin_lock(&vfsmount_lock);
+	list_add_tail(&new_ns->list, &new_ns->root->mnt_list);
+	spin_unlock(&vfsmount_lock);
+
+	/*
+	 * Second pass: switch the tsk->fs->* elements and mark new vfsmounts
+	 * as belonging to new namespace.  We have already acquired a private
+	 * fs_struct, so tsk->fs->lock is not needed.
+	 */
+	p = namespace->root;
+	q = new_ns->root;
+	while (p) {
+		q->mnt_namespace = new_ns;
+		if (fs) {
+			if (p == fs->rootmnt) {
+				rootmnt = p;
+				fs->rootmnt = mntget(q);
+			}
+			if (p == fs->pwdmnt) {
+				pwdmnt = p;
+				fs->pwdmnt = mntget(q);
+			}
+			if (p == fs->altrootmnt) {
+				altrootmnt = p;
+				fs->altrootmnt = mntget(q);
+			}
+		}
+		p = next_mnt(p, namespace->root);
+		q = next_mnt(q, new_ns->root);
+	}
+	up_write(&tsk->namespace->sem);
+
+	tsk->namespace = new_ns;
+
+	if (rootmnt)
+		mntput(rootmnt);
+	if (pwdmnt)
+		mntput(pwdmnt);
+	if (altrootmnt)
+		mntput(altrootmnt);
+
+	put_namespace(namespace);
+	return 0;
+
+out:
+	put_namespace(namespace);
+	return -ENOMEM;
+}
+
+asmlinkage long sys_mount(char __user * dev_name, char __user * dir_name,
+			  char __user * type, unsigned long flags,
+			  void __user * data)
+{
+	int retval;
+	unsigned long data_page;
+	unsigned long type_page;
+	unsigned long dev_page;
+	char *dir_page;
+
+	retval = copy_mount_options (type, &type_page);
+	if (retval < 0)
+		return retval;
+
+	dir_page = getname(dir_name);
+	retval = PTR_ERR(dir_page);
+	if (IS_ERR(dir_page))
+		goto out1;
+
+	retval = copy_mount_options (dev_name, &dev_page);
+	if (retval < 0)
+		goto out2;
+
+	retval = copy_mount_options (data, &data_page);
+	if (retval < 0)
+		goto out3;
+
+	lock_kernel();
+	retval = do_mount((char*)dev_page, dir_page, (char*)type_page,
+			  flags, (void*)data_page);
+	unlock_kernel();
+	free_page(data_page);
+
+out3:
+	free_page(dev_page);
+out2:
+	putname(dir_page);
+out1:
+	free_page(type_page);
+	return retval;
+}
+
+/*
+ * Replace the fs->{rootmnt,root} with {mnt,dentry}. Put the old values.
+ * It can block. Requires the big lock held.
+ */
+void set_fs_root(struct fs_struct *fs, struct vfsmount *mnt,
+		 struct dentry *dentry)
+{
+	struct dentry *old_root;
+	struct vfsmount *old_rootmnt;
+	write_lock(&fs->lock);
+	old_root = fs->root;
+	old_rootmnt = fs->rootmnt;
+	fs->rootmnt = mntget(mnt);
+	fs->root = dget(dentry);
+	write_unlock(&fs->lock);
+	if (old_root) {
+		dput(old_root);
+		mntput(old_rootmnt);
+	}
+}
+
+/*
+ * Replace the fs->{pwdmnt,pwd} with {mnt,dentry}. Put the old values.
+ * It can block. Requires the big lock held.
+ */
+void set_fs_pwd(struct fs_struct *fs, struct vfsmount *mnt,
+		struct dentry *dentry)
+{
+	struct dentry *old_pwd;
+	struct vfsmount *old_pwdmnt;
+
+	write_lock(&fs->lock);
+	old_pwd = fs->pwd;
+	old_pwdmnt = fs->pwdmnt;
+	fs->pwdmnt = mntget(mnt);
+	fs->pwd = dget(dentry);
+	write_unlock(&fs->lock);
+
+	if (old_pwd) {
+		dput(old_pwd);
+		mntput(old_pwdmnt);
+	}
+}
+
+static void chroot_fs_refs(struct nameidata *old_nd, struct nameidata *new_nd)
+{
+	struct task_struct *g, *p;
+	struct fs_struct *fs;
+
+	read_lock(&tasklist_lock);
+	do_each_thread(g, p) {
+		task_lock(p);
+		fs = p->fs;
+		if (fs) {
+			atomic_inc(&fs->count);
+			task_unlock(p);
+			if (fs->root==old_nd->dentry&&fs->rootmnt==old_nd->mnt)
+				set_fs_root(fs, new_nd->mnt, new_nd->dentry);
+			if (fs->pwd==old_nd->dentry&&fs->pwdmnt==old_nd->mnt)
+				set_fs_pwd(fs, new_nd->mnt, new_nd->dentry);
+			put_fs_struct(fs);
+		} else
+			task_unlock(p);
+	} while_each_thread(g, p);
+	read_unlock(&tasklist_lock);
+}
+
+/*
+ * pivot_root Semantics:
+ * Moves the root file system of the current process to the directory put_old,
+ * makes new_root as the new root file system of the current process, and sets
+ * root/cwd of all processes which had them on the current root to new_root.
+ *
+ * Restrictions:
+ * The new_root and put_old must be directories, and  must not be on the
+ * same file  system as the current process root. The put_old  must  be
+ * underneath new_root,  i.e. adding a non-zero number of /.. to the string
+ * pointed to by put_old must yield the same directory as new_root. No other
+ * file system may be mounted on put_old. After all, new_root is a mountpoint.
+ *
+ * Notes:
+ *  - we don't move root/cwd if they are not at the root (reason: if something
+ *    cared enough to change them, it's probably wrong to force them elsewhere)
+ *  - it's okay to pick a root that isn't the root of a file system, e.g.
+ *    /nfs/my_root where /nfs is the mount point. It must be a mountpoint,
+ *    though, so you may need to say mount --bind /nfs/my_root /nfs/my_root
+ *    first.
+ */
+
+asmlinkage long sys_pivot_root(const char __user *new_root, const char __user *put_old)
+{
+	struct vfsmount *tmp;
+	struct nameidata new_nd, old_nd, parent_nd, root_parent, user_nd;
+	int error;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	lock_kernel();
+
+	error = __user_walk(new_root, LOOKUP_FOLLOW|LOOKUP_DIRECTORY, &new_nd);
+	if (error)
+		goto out0;
+	error = -EINVAL;
+	if (!check_mnt(new_nd.mnt))
+		goto out1;
+
+	error = __user_walk(put_old, LOOKUP_FOLLOW|LOOKUP_DIRECTORY, &old_nd);
+	if (error)
+		goto out1;
+
+	error = security_sb_pivotroot(&old_nd, &new_nd);
+	if (error) {
+		path_release(&old_nd);
+		goto out1;
+	}
+
+	read_lock(&current->fs->lock);
+	user_nd.mnt = mntget(current->fs->rootmnt);
+	user_nd.dentry = dget(current->fs->root);
+	read_unlock(&current->fs->lock);
+	down_write(&current->namespace->sem);
+	down(&old_nd.dentry->d_inode->i_sem);
+	error = -EINVAL;
+	if (!check_mnt(user_nd.mnt))
+		goto out2;
+	error = -ENOENT;
+	if (IS_DEADDIR(new_nd.dentry->d_inode))
+		goto out2;
+	if (d_unhashed(new_nd.dentry) && !IS_ROOT(new_nd.dentry))
+		goto out2;
+	if (d_unhashed(old_nd.dentry) && !IS_ROOT(old_nd.dentry))
+		goto out2;
+	error = -EBUSY;
+	if (new_nd.mnt == user_nd.mnt || old_nd.mnt == user_nd.mnt)
+		goto out2; /* loop, on the same file system  */
+	error = -EINVAL;
+	if (user_nd.mnt->mnt_root != user_nd.dentry)
+		goto out2; /* not a mountpoint */
+	if (new_nd.mnt->mnt_root != new_nd.dentry)
+		goto out2; /* not a mountpoint */
+	tmp = old_nd.mnt; /* make sure we can reach put_old from new_root */
+	spin_lock(&vfsmount_lock);
+	if (tmp != new_nd.mnt) {
+		for (;;) {
+			if (tmp->mnt_parent == tmp)
+				goto out3; /* already mounted on put_old */
+			if (tmp->mnt_parent == new_nd.mnt)
+				break;
+			tmp = tmp->mnt_parent;
+		}
+		if (!is_subdir(tmp->mnt_mountpoint, new_nd.dentry))
+			goto out3;
+	} else if (!is_subdir(old_nd.dentry, new_nd.dentry))
+		goto out3;
+	detach_mnt(new_nd.mnt, &parent_nd);
+	detach_mnt(user_nd.mnt, &root_parent);
+	attach_mnt(user_nd.mnt, &old_nd);     /* mount old root on put_old */
+	attach_mnt(new_nd.mnt, &root_parent); /* mount new_root on / */
+	spin_unlock(&vfsmount_lock);
+	chroot_fs_refs(&user_nd, &new_nd);
+	security_sb_post_pivotroot(&user_nd, &new_nd);
+	error = 0;
+	path_release(&root_parent);
+	path_release(&parent_nd);
+out2:
+	up(&old_nd.dentry->d_inode->i_sem);
+	up_write(&current->namespace->sem);
+	path_release(&user_nd);
+	path_release(&old_nd);
+out1:
+	path_release(&new_nd);
+out0:
+	unlock_kernel();
+	return error;
+out3:
+	spin_unlock(&vfsmount_lock);
+	goto out2;
+}
+
+static void __init init_mount_tree(void)
+{
+	struct vfsmount *mnt;
+	struct namespace *namespace;
+	struct task_struct *g, *p;
+
+	mnt = do_kern_mount("rootfs", 0, "rootfs", NULL);
+	if (IS_ERR(mnt))
+		panic("Can't create rootfs");
+	namespace = kmalloc(sizeof(*namespace), GFP_KERNEL);
+	if (!namespace)
+		panic("Can't allocate initial namespace");
+	atomic_set(&namespace->count, 1);
+	INIT_LIST_HEAD(&namespace->list);
+	init_rwsem(&namespace->sem);
+	list_add(&mnt->mnt_list, &namespace->list);
+	namespace->root = mnt;
+	mnt->mnt_namespace = namespace;
+
+	init_task.namespace = namespace;
+	read_lock(&tasklist_lock);
+	do_each_thread(g, p) {
+		get_namespace(namespace);
+		p->namespace = namespace;
+	} while_each_thread(g, p);
+	read_unlock(&tasklist_lock);
+
+	set_fs_pwd(current->fs, namespace->root, namespace->root->mnt_root);
+	set_fs_root(current->fs, namespace->root, namespace->root->mnt_root);
+}
+
+void __init mnt_init(unsigned long mempages)
+{
+	struct list_head *d;
+	unsigned int nr_hash;
+	int i;
+
+	mnt_cache = kmem_cache_create("mnt_cache", sizeof(struct vfsmount),
+			0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
+
+	mount_hashtable = (struct list_head *)
+		__get_free_page(GFP_ATOMIC);
+
+	if (!mount_hashtable)
+		panic("Failed to allocate mount hash table\n");
+
+	/*
+	 * Find the power-of-two list-heads that can fit into the allocation..
+	 * We don't guarantee that "sizeof(struct list_head)" is necessarily
+	 * a power-of-two.
+	 */
+	nr_hash = PAGE_SIZE / sizeof(struct list_head);
+	hash_bits = 0;
+	do {
+		hash_bits++;
+	} while ((nr_hash >> hash_bits) != 0);
+	hash_bits--;
+
+	/*
+	 * Re-calculate the actual number of entries and the mask
+	 * from the number of bits we can fit.
+	 */
+	nr_hash = 1UL << hash_bits;
+	hash_mask = nr_hash-1;
+
+	printk("Mount-cache hash table entries: %d\n", nr_hash);
+
+	/* And initialize the newly allocated array */
+	d = mount_hashtable;
+	i = nr_hash;
+	do {
+		INIT_LIST_HEAD(d);
+		d++;
+		i--;
+	} while (i);
+	sysfs_init();
+	init_rootfs();
+	init_mount_tree();
+}
+
+void __put_namespace(struct namespace *namespace)
+{
+	struct vfsmount *mnt;
+
+	down_write(&namespace->sem);
+	spin_lock(&vfsmount_lock);
+
+	list_for_each_entry(mnt, &namespace->list, mnt_list) {
+		mnt->mnt_namespace = NULL;
+	}
+
+	umount_tree(namespace->root);
+	spin_unlock(&vfsmount_lock);
+	up_write(&namespace->sem);
+	kfree(namespace);
+}