Linux-2.6.12-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!
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(¤t->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(¤t->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(¤t->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(¤t->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(¤t->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(¤t->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(¤t->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(¤t->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(¤t->fs->lock);
+ user_nd.mnt = mntget(current->fs->rootmnt);
+ user_nd.dentry = dget(current->fs->root);
+ read_unlock(¤t->fs->lock);
+ down_write(¤t->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(¤t->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);
+}