ARM: report present cpus instead of online CPUs
[linux-2.6.git] / fs / namespace.c
index d7fc05f..e5e1c7d 100644 (file)
@@ -183,7 +183,7 @@ static inline void mnt_dec_count(struct vfsmount *mnt)
 unsigned int mnt_get_count(struct vfsmount *mnt)
 {
 #ifdef CONFIG_SMP
-       unsigned int count = atomic_read(&mnt->mnt_longrefs);
+       unsigned int count = 0;
        int cpu;
 
        for_each_possible_cpu(cpu) {
@@ -196,7 +196,7 @@ unsigned int mnt_get_count(struct vfsmount *mnt)
 #endif
 }
 
-struct vfsmount *alloc_vfsmnt(const char *name)
+static struct vfsmount *alloc_vfsmnt(const char *name)
 {
        struct vfsmount *mnt = kmem_cache_zalloc(mnt_cache, GFP_KERNEL);
        if (mnt) {
@@ -217,7 +217,7 @@ struct vfsmount *alloc_vfsmnt(const char *name)
                if (!mnt->mnt_pcp)
                        goto out_free_devname;
 
-               atomic_set(&mnt->mnt_longrefs, 1);
+               this_cpu_add(mnt->mnt_pcp->mnt_count, 1);
 #else
                mnt->mnt_count = 1;
                mnt->mnt_writers = 0;
@@ -466,15 +466,7 @@ static void __mnt_unmake_readonly(struct vfsmount *mnt)
        br_write_unlock(vfsmount_lock);
 }
 
-void simple_set_mnt(struct vfsmount *mnt, struct super_block *sb)
-{
-       mnt->mnt_sb = sb;
-       mnt->mnt_root = dget(sb->s_root);
-}
-
-EXPORT_SYMBOL(simple_set_mnt);
-
-void free_vfsmnt(struct vfsmount *mnt)
+static void free_vfsmnt(struct vfsmount *mnt)
 {
        kfree(mnt->mnt_devname);
        mnt_free_id(mnt);
@@ -611,6 +603,21 @@ static void attach_mnt(struct vfsmount *mnt, struct path *path)
        list_add_tail(&mnt->mnt_child, &path->mnt->mnt_mounts);
 }
 
+static inline void __mnt_make_longterm(struct vfsmount *mnt)
+{
+#ifdef CONFIG_SMP
+       atomic_inc(&mnt->mnt_longterm);
+#endif
+}
+
+/* needs vfsmount lock for write */
+static inline void __mnt_make_shortterm(struct vfsmount *mnt)
+{
+#ifdef CONFIG_SMP
+       atomic_dec(&mnt->mnt_longterm);
+#endif
+}
+
 /*
  * vfsmount lock must be held for write
  */
@@ -624,8 +631,11 @@ static void commit_tree(struct vfsmount *mnt)
        BUG_ON(parent == mnt);
 
        list_add_tail(&head, &mnt->mnt_list);
-       list_for_each_entry(m, &head, mnt_list)
+       list_for_each_entry(m, &head, mnt_list) {
                m->mnt_ns = n;
+               __mnt_make_longterm(m);
+       }
+
        list_splice(&head, n->list.prev);
 
        list_add_tail(&mnt->mnt_hash, mount_hashtable +
@@ -660,6 +670,36 @@ static struct vfsmount *skip_mnt_tree(struct vfsmount *p)
        return p;
 }
 
+struct vfsmount *
+vfs_kern_mount(struct file_system_type *type, int flags, const char *name, void *data)
+{
+       struct vfsmount *mnt;
+       struct dentry *root;
+
+       if (!type)
+               return ERR_PTR(-ENODEV);
+
+       mnt = alloc_vfsmnt(name);
+       if (!mnt)
+               return ERR_PTR(-ENOMEM);
+
+       if (flags & MS_KERNMOUNT)
+               mnt->mnt_flags = MNT_INTERNAL;
+
+       root = mount_fs(type, flags, name, data);
+       if (IS_ERR(root)) {
+               free_vfsmnt(mnt);
+               return ERR_CAST(root);
+       }
+
+       mnt->mnt_root = root;
+       mnt->mnt_sb = root->d_sb;
+       mnt->mnt_mountpoint = mnt->mnt_root;
+       mnt->mnt_parent = mnt;
+       return mnt;
+}
+EXPORT_SYMBOL_GPL(vfs_kern_mount);
+
 static struct vfsmount *clone_mnt(struct vfsmount *old, struct dentry *root,
                                        int flag)
 {
@@ -734,51 +774,30 @@ static inline void mntfree(struct vfsmount *mnt)
        deactivate_super(sb);
 }
 
-#ifdef CONFIG_SMP
-static inline void __mntput(struct vfsmount *mnt, int longrefs)
+static void mntput_no_expire(struct vfsmount *mnt)
 {
-       if (!longrefs) {
 put_again:
-               br_read_lock(vfsmount_lock);
-               if (likely(atomic_read(&mnt->mnt_longrefs))) {
-                       mnt_dec_count(mnt);
-                       br_read_unlock(vfsmount_lock);
-                       return;
-               }
+#ifdef CONFIG_SMP
+       br_read_lock(vfsmount_lock);
+       if (likely(atomic_read(&mnt->mnt_longterm))) {
+               mnt_dec_count(mnt);
                br_read_unlock(vfsmount_lock);
-       } else {
-               BUG_ON(!atomic_read(&mnt->mnt_longrefs));
-               if (atomic_add_unless(&mnt->mnt_longrefs, -1, 1))
-                       return;
+               return;
        }
+       br_read_unlock(vfsmount_lock);
 
        br_write_lock(vfsmount_lock);
-       if (!longrefs)
-               mnt_dec_count(mnt);
-       else
-               atomic_dec(&mnt->mnt_longrefs);
+       mnt_dec_count(mnt);
        if (mnt_get_count(mnt)) {
                br_write_unlock(vfsmount_lock);
                return;
        }
-       if (unlikely(mnt->mnt_pinned)) {
-               mnt_add_count(mnt, mnt->mnt_pinned + 1);
-               mnt->mnt_pinned = 0;
-               br_write_unlock(vfsmount_lock);
-               acct_auto_close_mnt(mnt);
-               goto put_again;
-       }
-       br_write_unlock(vfsmount_lock);
-       mntfree(mnt);
-}
 #else
-static inline void __mntput(struct vfsmount *mnt, int longrefs)
-{
-put_again:
        mnt_dec_count(mnt);
        if (likely(mnt_get_count(mnt)))
                return;
        br_write_lock(vfsmount_lock);
+#endif
        if (unlikely(mnt->mnt_pinned)) {
                mnt_add_count(mnt, mnt->mnt_pinned + 1);
                mnt->mnt_pinned = 0;
@@ -789,12 +808,6 @@ put_again:
        br_write_unlock(vfsmount_lock);
        mntfree(mnt);
 }
-#endif
-
-static void mntput_no_expire(struct vfsmount *mnt)
-{
-       __mntput(mnt, 0);
-}
 
 void mntput(struct vfsmount *mnt)
 {
@@ -802,7 +815,7 @@ void mntput(struct vfsmount *mnt)
                /* avoid cacheline pingpong, hope gcc doesn't get "smart" */
                if (unlikely(mnt->mnt_expiry_mark))
                        mnt->mnt_expiry_mark = 0;
-               __mntput(mnt, 0);
+               mntput_no_expire(mnt);
        }
 }
 EXPORT_SYMBOL(mntput);
@@ -815,33 +828,6 @@ struct vfsmount *mntget(struct vfsmount *mnt)
 }
 EXPORT_SYMBOL(mntget);
 
-void mntput_long(struct vfsmount *mnt)
-{
-#ifdef CONFIG_SMP
-       if (mnt) {
-               /* avoid cacheline pingpong, hope gcc doesn't get "smart" */
-               if (unlikely(mnt->mnt_expiry_mark))
-                       mnt->mnt_expiry_mark = 0;
-               __mntput(mnt, 1);
-       }
-#else
-       mntput(mnt);
-#endif
-}
-EXPORT_SYMBOL(mntput_long);
-
-struct vfsmount *mntget_long(struct vfsmount *mnt)
-{
-#ifdef CONFIG_SMP
-       if (mnt)
-               atomic_inc(&mnt->mnt_longrefs);
-       return mnt;
-#else
-       return mntget(mnt);
-#endif
-}
-EXPORT_SYMBOL(mntget_long);
-
 void mnt_pin(struct vfsmount *mnt)
 {
        br_write_lock(vfsmount_lock);
@@ -948,8 +934,8 @@ int mnt_had_events(struct proc_mounts *p)
        int res = 0;
 
        br_read_lock(vfsmount_lock);
-       if (p->event != ns->event) {
-               p->event = ns->event;
+       if (p->m.poll_event != ns->event) {
+               p->m.poll_event = ns->event;
                res = 1;
        }
        br_read_unlock(vfsmount_lock);
@@ -1014,7 +1000,13 @@ static int show_vfsmnt(struct seq_file *m, void *v)
        int err = 0;
        struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
 
-       mangle(m, mnt->mnt_devname ? mnt->mnt_devname : "none");
+       if (mnt->mnt_sb->s_op->show_devname) {
+               err = mnt->mnt_sb->s_op->show_devname(m, mnt);
+               if (err)
+                       goto out;
+       } else {
+               mangle(m, mnt->mnt_devname ? mnt->mnt_devname : "none");
+       }
        seq_putc(m, ' ');
        seq_path(m, &mnt_path, " \t\n\\");
        seq_putc(m, ' ');
@@ -1049,7 +1041,12 @@ static int show_mountinfo(struct seq_file *m, void *v)
 
        seq_printf(m, "%i %i %u:%u ", mnt->mnt_id, mnt->mnt_parent->mnt_id,
                   MAJOR(sb->s_dev), MINOR(sb->s_dev));
-       seq_dentry(m, mnt->mnt_root, " \t\n\\");
+       if (sb->s_op->show_path)
+               err = sb->s_op->show_path(m, mnt);
+       else
+               seq_dentry(m, mnt->mnt_root, " \t\n\\");
+       if (err)
+               goto out;
        seq_putc(m, ' ');
        seq_path_root(m, &mnt_path, &root, " \t\n\\");
        if (root.mnt != p->root.mnt || root.dentry != p->root.dentry) {
@@ -1080,7 +1077,12 @@ static int show_mountinfo(struct seq_file *m, void *v)
        seq_puts(m, " - ");
        show_type(m, sb);
        seq_putc(m, ' ');
-       mangle(m, mnt->mnt_devname ? mnt->mnt_devname : "none");
+       if (sb->s_op->show_devname)
+               err = sb->s_op->show_devname(m, mnt);
+       else
+               mangle(m, mnt->mnt_devname ? mnt->mnt_devname : "none");
+       if (err)
+               goto out;
        seq_puts(m, sb->s_flags & MS_RDONLY ? " ro" : " rw");
        err = show_sb_opts(m, sb);
        if (err)
@@ -1106,11 +1108,16 @@ static int show_vfsstat(struct seq_file *m, void *v)
        int err = 0;
 
        /* device */
-       if (mnt->mnt_devname) {
+       if (mnt->mnt_sb->s_op->show_devname) {
                seq_puts(m, "device ");
-               mangle(m, mnt->mnt_devname);
-       } else
-               seq_puts(m, "no device");
+               err = mnt->mnt_sb->s_op->show_devname(m, mnt);
+       } else {
+               if (mnt->mnt_devname) {
+                       seq_puts(m, "device ");
+                       mangle(m, mnt->mnt_devname);
+               } else
+                       seq_puts(m, "no device");
+       }
 
        /* mount point */
        seq_puts(m, " mounted on ");
@@ -1124,7 +1131,8 @@ static int show_vfsstat(struct seq_file *m, void *v)
        /* optional statistics */
        if (mnt->mnt_sb->s_op->show_stats) {
                seq_putc(m, ' ');
-               err = mnt->mnt_sb->s_op->show_stats(m, mnt);
+               if (!err)
+                       err = mnt->mnt_sb->s_op->show_stats(m, mnt);
        }
 
        seq_putc(m, '\n');
@@ -1216,7 +1224,7 @@ void release_mounts(struct list_head *head)
                        dput(dentry);
                        mntput(m);
                }
-               mntput_long(mnt);
+               mntput(mnt);
        }
 }
 
@@ -1240,6 +1248,7 @@ void umount_tree(struct vfsmount *mnt, int propagate, struct list_head *kill)
                list_del_init(&p->mnt_list);
                __touch_mnt_namespace(p->mnt_ns);
                p->mnt_ns = NULL;
+               __mnt_make_shortterm(p);
                list_del_init(&p->mnt_child);
                if (p->mnt_parent != p) {
                        p->mnt_parent->mnt_ghosts++;
@@ -1279,7 +1288,7 @@ static int do_umount(struct vfsmount *mnt, int flags)
                 */
                br_write_lock(vfsmount_lock);
                if (mnt_get_count(mnt) != 2) {
-                       br_write_lock(vfsmount_lock);
+                       br_write_unlock(vfsmount_lock);
                        return -EBUSY;
                }
                br_write_unlock(vfsmount_lock);
@@ -1639,9 +1648,35 @@ static int attach_recursive_mnt(struct vfsmount *source_mnt,
        return err;
 }
 
+static int lock_mount(struct path *path)
+{
+       struct vfsmount *mnt;
+retry:
+       mutex_lock(&path->dentry->d_inode->i_mutex);
+       if (unlikely(cant_mount(path->dentry))) {
+               mutex_unlock(&path->dentry->d_inode->i_mutex);
+               return -ENOENT;
+       }
+       down_write(&namespace_sem);
+       mnt = lookup_mnt(path);
+       if (likely(!mnt))
+               return 0;
+       up_write(&namespace_sem);
+       mutex_unlock(&path->dentry->d_inode->i_mutex);
+       path_put(path);
+       path->mnt = mnt;
+       path->dentry = dget(mnt->mnt_root);
+       goto retry;
+}
+
+static void unlock_mount(struct path *path)
+{
+       up_write(&namespace_sem);
+       mutex_unlock(&path->dentry->d_inode->i_mutex);
+}
+
 static int graft_tree(struct vfsmount *mnt, struct path *path)
 {
-       int err;
        if (mnt->mnt_sb->s_flags & MS_NOUSER)
                return -EINVAL;
 
@@ -1649,16 +1684,10 @@ static int graft_tree(struct vfsmount *mnt, struct path *path)
              S_ISDIR(mnt->mnt_root->d_inode->i_mode))
                return -ENOTDIR;
 
-       err = -ENOENT;
-       mutex_lock(&path->dentry->d_inode->i_mutex);
-       if (cant_mount(path->dentry))
-               goto out_unlock;
+       if (d_unlinked(path->dentry))
+               return -ENOENT;
 
-       if (!d_unlinked(path->dentry))
-               err = attach_recursive_mnt(mnt, path, NULL);
-out_unlock:
-       mutex_unlock(&path->dentry->d_inode->i_mutex);
-       return err;
+       return attach_recursive_mnt(mnt, path, NULL);
 }
 
 /*
@@ -1667,7 +1696,7 @@ out_unlock:
 
 static int flags_to_propagation_type(int flags)
 {
-       int type = flags & ~MS_REC;
+       int type = flags & ~(MS_REC | MS_SILENT);
 
        /* Fail if any non-propagation flags are set */
        if (type & ~(MS_SHARED | MS_PRIVATE | MS_SLAVE | MS_UNBINDABLE))
@@ -1721,6 +1750,7 @@ static int do_change_type(struct path *path, int flag)
 static int do_loopback(struct path *path, char *old_name,
                                int recurse)
 {
+       LIST_HEAD(umount_list);
        struct path old_path;
        struct vfsmount *mnt = NULL;
        int err = mount_is_safe(path);
@@ -1728,17 +1758,20 @@ static int do_loopback(struct path *path, char *old_name,
                return err;
        if (!old_name || !*old_name)
                return -EINVAL;
-       err = kern_path(old_name, LOOKUP_FOLLOW, &old_path);
+       err = kern_path(old_name, LOOKUP_FOLLOW|LOOKUP_AUTOMOUNT, &old_path);
        if (err)
                return err;
 
-       down_write(&namespace_sem);
+       err = lock_mount(path);
+       if (err)
+               goto out;
+
        err = -EINVAL;
        if (IS_MNT_UNBINDABLE(old_path.mnt))
-               goto out;
+               goto out2;
 
        if (!check_mnt(path->mnt) || !check_mnt(old_path.mnt))
-               goto out;
+               goto out2;
 
        err = -ENOMEM;
        if (recurse)
@@ -1747,20 +1780,18 @@ static int do_loopback(struct path *path, char *old_name,
                mnt = clone_mnt(old_path.mnt, old_path.dentry, 0);
 
        if (!mnt)
-               goto out;
+               goto out2;
 
        err = graft_tree(mnt, path);
        if (err) {
-               LIST_HEAD(umount_list);
-
                br_write_lock(vfsmount_lock);
                umount_tree(mnt, 0, &umount_list);
                br_write_unlock(vfsmount_lock);
-               release_mounts(&umount_list);
        }
-
+out2:
+       unlock_mount(path);
+       release_mounts(&umount_list);
 out:
-       up_write(&namespace_sem);
        path_put(&old_path);
        return err;
 }
@@ -1802,6 +1833,10 @@ static int do_remount(struct path *path, int flags, int mnt_flags,
        if (path->dentry != path->mnt->mnt_root)
                return -EINVAL;
 
+       err = security_sb_remount(sb, data);
+       if (err)
+               return err;
+
        down_write(&sb->s_umount);
        if (flags & MS_BIND)
                err = change_mount_flags(path->mnt, flags);
@@ -1845,18 +1880,12 @@ static int do_move_mount(struct path *path, char *old_name)
        if (err)
                return err;
 
-       down_write(&namespace_sem);
-       err = follow_down(path, true);
+       err = lock_mount(path);
        if (err < 0)
                goto out;
 
        err = -EINVAL;
        if (!check_mnt(path->mnt) || !check_mnt(old_path.mnt))
-               goto out;
-
-       err = -ENOENT;
-       mutex_lock(&path->dentry->d_inode->i_mutex);
-       if (cant_mount(path->dentry))
                goto out1;
 
        if (d_unlinked(path->dentry))
@@ -1898,53 +1927,65 @@ static int do_move_mount(struct path *path, char *old_name)
         * automatically */
        list_del_init(&old_path.mnt->mnt_expire);
 out1:
-       mutex_unlock(&path->dentry->d_inode->i_mutex);
+       unlock_mount(path);
 out:
-       up_write(&namespace_sem);
        if (!err)
                path_put(&parent_path);
        path_put(&old_path);
        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 path *path, char *type, int flags,
-                       int mnt_flags, char *name, void *data)
+static struct vfsmount *fs_set_subtype(struct vfsmount *mnt, const char *fstype)
 {
-       struct vfsmount *mnt;
-
-       if (!type)
-               return -EINVAL;
+       int err;
+       const char *subtype = strchr(fstype, '.');
+       if (subtype) {
+               subtype++;
+               err = -EINVAL;
+               if (!subtype[0])
+                       goto err;
+       } else
+               subtype = "";
 
-       /* we need capabilities... */
-       if (!capable(CAP_SYS_ADMIN))
-               return -EPERM;
+       mnt->mnt_sb->s_subtype = kstrdup(subtype, GFP_KERNEL);
+       err = -ENOMEM;
+       if (!mnt->mnt_sb->s_subtype)
+               goto err;
+       return mnt;
 
-       mnt = do_kern_mount(type, flags, name, data);
-       if (IS_ERR(mnt))
-               return PTR_ERR(mnt);
+ err:
+       mntput(mnt);
+       return ERR_PTR(err);
+}
 
-       return do_add_mount(mnt, path, mnt_flags);
+struct vfsmount *
+do_kern_mount(const char *fstype, int flags, const char *name, void *data)
+{
+       struct file_system_type *type = get_fs_type(fstype);
+       struct vfsmount *mnt;
+       if (!type)
+               return ERR_PTR(-ENODEV);
+       mnt = vfs_kern_mount(type, flags, name, data);
+       if (!IS_ERR(mnt) && (type->fs_flags & FS_HAS_SUBTYPE) &&
+           !mnt->mnt_sb->s_subtype)
+               mnt = fs_set_subtype(mnt, fstype);
+       put_filesystem(type);
+       return mnt;
 }
+EXPORT_SYMBOL_GPL(do_kern_mount);
 
 /*
  * add a mount into a namespace's mount tree
- * - this unconditionally eats one of the caller's references to newmnt.
  */
-int do_add_mount(struct vfsmount *newmnt, struct path *path, int mnt_flags)
+static int do_add_mount(struct vfsmount *newmnt, struct path *path, int mnt_flags)
 {
        int err;
 
        mnt_flags &= ~(MNT_SHARED | MNT_WRITE_HOLD | MNT_INTERNAL);
 
-       down_write(&namespace_sem);
-       /* Something was mounted here while we slept */
-       err = follow_down(path, true);
-       if (err < 0)
-               goto unlock;
+       err = lock_mount(path);
+       if (err)
+               return err;
 
        err = -EINVAL;
        if (!(mnt_flags & MNT_SHRINKABLE) && !check_mnt(path->mnt))
@@ -1961,15 +2002,68 @@ int do_add_mount(struct vfsmount *newmnt, struct path *path, int mnt_flags)
                goto unlock;
 
        newmnt->mnt_flags = mnt_flags;
-       if ((err = graft_tree(newmnt, path)))
-               goto unlock;
-
-       up_write(&namespace_sem);
-       return 0;
+       err = graft_tree(newmnt, path);
 
 unlock:
-       up_write(&namespace_sem);
-       mntput_long(newmnt);
+       unlock_mount(path);
+       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 path *path, char *type, int flags,
+                       int mnt_flags, char *name, void *data)
+{
+       struct vfsmount *mnt;
+       int err;
+
+       if (!type)
+               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);
+
+       err = do_add_mount(mnt, path, mnt_flags);
+       if (err)
+               mntput(mnt);
+       return err;
+}
+
+int finish_automount(struct vfsmount *m, struct path *path)
+{
+       int err;
+       /* The new mount record should have at least 2 refs to prevent it being
+        * expired before we get a chance to add it
+        */
+       BUG_ON(mnt_get_count(m) < 2);
+
+       if (m->mnt_sb == path->mnt->mnt_sb &&
+           m->mnt_root == path->dentry) {
+               err = -ELOOP;
+               goto fail;
+       }
+
+       err = do_add_mount(m, path, path->mnt->mnt_flags | MNT_SHRINKABLE);
+       if (!err)
+               return 0;
+fail:
+       /* remove m from any expiration list it may be on */
+       if (!list_empty(&m->mnt_expire)) {
+               down_write(&namespace_sem);
+               br_write_lock(vfsmount_lock);
+               list_del_init(&m->mnt_expire);
+               br_write_unlock(vfsmount_lock);
+               up_write(&namespace_sem);
+       }
+       mntput(m);
+       mntput(m);
        return err;
 }
 
@@ -1991,20 +2085,6 @@ void mnt_set_expiry(struct vfsmount *mnt, struct list_head *expiry_list)
 EXPORT_SYMBOL(mnt_set_expiry);
 
 /*
- * Remove a vfsmount from any expiration list it may be on
- */
-void mnt_clear_expiry(struct vfsmount *mnt)
-{
-       if (!list_empty(&mnt->mnt_expire)) {
-               down_write(&namespace_sem);
-               br_write_lock(vfsmount_lock);
-               list_del_init(&mnt->mnt_expire);
-               br_write_unlock(vfsmount_lock);
-               up_write(&namespace_sem);
-       }
-}
-
-/*
  * 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
@@ -2291,6 +2371,22 @@ static struct mnt_namespace *alloc_mnt_ns(void)
        return new_ns;
 }
 
+void mnt_make_longterm(struct vfsmount *mnt)
+{
+       __mnt_make_longterm(mnt);
+}
+
+void mnt_make_shortterm(struct vfsmount *mnt)
+{
+#ifdef CONFIG_SMP
+       if (atomic_add_unless(&mnt->mnt_longterm, -1, 1))
+               return;
+       br_write_lock(vfsmount_lock);
+       atomic_dec(&mnt->mnt_longterm);
+       br_write_unlock(vfsmount_lock);
+#endif
+}
+
 /*
  * Allocate a new namespace structure and populate it with contents
  * copied from the namespace of the passed in task structure.
@@ -2328,14 +2424,19 @@ static struct mnt_namespace *dup_mnt_ns(struct mnt_namespace *mnt_ns,
        q = new_ns->root;
        while (p) {
                q->mnt_ns = new_ns;
+               __mnt_make_longterm(q);
                if (fs) {
                        if (p == fs->root.mnt) {
+                               fs->root.mnt = mntget(q);
+                               __mnt_make_longterm(q);
+                               mnt_make_shortterm(p);
                                rootmnt = p;
-                               fs->root.mnt = mntget_long(q);
                        }
                        if (p == fs->pwd.mnt) {
+                               fs->pwd.mnt = mntget(q);
+                               __mnt_make_longterm(q);
+                               mnt_make_shortterm(p);
                                pwdmnt = p;
-                               fs->pwd.mnt = mntget_long(q);
                        }
                }
                p = next_mnt(p, mnt_ns->root);
@@ -2344,9 +2445,9 @@ static struct mnt_namespace *dup_mnt_ns(struct mnt_namespace *mnt_ns,
        up_write(&namespace_sem);
 
        if (rootmnt)
-               mntput_long(rootmnt);
+               mntput(rootmnt);
        if (pwdmnt)
-               mntput_long(pwdmnt);
+               mntput(pwdmnt);
 
        return new_ns;
 }
@@ -2379,6 +2480,7 @@ struct mnt_namespace *create_mnt_ns(struct vfsmount *mnt)
        new_ns = alloc_mnt_ns();
        if (!IS_ERR(new_ns)) {
                mnt->mnt_ns = new_ns;
+               __mnt_make_longterm(mnt);
                new_ns->root = mnt;
                list_add(&new_ns->list, &new_ns->root->mnt_list);
        }
@@ -2465,65 +2567,60 @@ SYSCALL_DEFINE2(pivot_root, const char __user *, new_root,
        error = user_path_dir(new_root, &new);
        if (error)
                goto out0;
-       error = -EINVAL;
-       if (!check_mnt(new.mnt))
-               goto out1;
 
        error = user_path_dir(put_old, &old);
        if (error)
                goto out1;
 
        error = security_sb_pivotroot(&old, &new);
-       if (error) {
-               path_put(&old);
-               goto out1;
-       }
+       if (error)
+               goto out2;
 
        get_fs_root(current->fs, &root);
-       down_write(&namespace_sem);
-       mutex_lock(&old.dentry->d_inode->i_mutex);
+       error = lock_mount(&old);
+       if (error)
+               goto out3;
+
        error = -EINVAL;
        if (IS_MNT_SHARED(old.mnt) ||
                IS_MNT_SHARED(new.mnt->mnt_parent) ||
                IS_MNT_SHARED(root.mnt->mnt_parent))
-               goto out2;
-       if (!check_mnt(root.mnt))
-               goto out2;
+               goto out4;
+       if (!check_mnt(root.mnt) || !check_mnt(new.mnt))
+               goto out4;
        error = -ENOENT;
-       if (cant_mount(old.dentry))
-               goto out2;
        if (d_unlinked(new.dentry))
-               goto out2;
+               goto out4;
        if (d_unlinked(old.dentry))
-               goto out2;
+               goto out4;
        error = -EBUSY;
        if (new.mnt == root.mnt ||
            old.mnt == root.mnt)
-               goto out2; /* loop, on the same file system  */
+               goto out4; /* loop, on the same file system  */
        error = -EINVAL;
        if (root.mnt->mnt_root != root.dentry)
-               goto out2; /* not a mountpoint */
+               goto out4; /* not a mountpoint */
        if (root.mnt->mnt_parent == root.mnt)
-               goto out2; /* not attached */
+               goto out4; /* not attached */
        if (new.mnt->mnt_root != new.dentry)
-               goto out2; /* not a mountpoint */
+               goto out4; /* not a mountpoint */
        if (new.mnt->mnt_parent == new.mnt)
-               goto out2; /* not attached */
+               goto out4; /* not attached */
        /* make sure we can reach put_old from new_root */
        tmp = old.mnt;
-       br_write_lock(vfsmount_lock);
        if (tmp != new.mnt) {
                for (;;) {
                        if (tmp->mnt_parent == tmp)
-                               goto out3; /* already mounted on put_old */
+                               goto out4; /* already mounted on put_old */
                        if (tmp->mnt_parent == new.mnt)
                                break;
                        tmp = tmp->mnt_parent;
                }
                if (!is_subdir(tmp->mnt_mountpoint, new.dentry))
-                       goto out3;
+                       goto out4;
        } else if (!is_subdir(old.dentry, new.dentry))
-               goto out3;
+               goto out4;
+       br_write_lock(vfsmount_lock);
        detach_mnt(new.mnt, &parent_path);
        detach_mnt(root.mnt, &root_parent);
        /* mount old root on put_old */
@@ -2533,22 +2630,21 @@ SYSCALL_DEFINE2(pivot_root, const char __user *, new_root,
        touch_mnt_namespace(current->nsproxy->mnt_ns);
        br_write_unlock(vfsmount_lock);
        chroot_fs_refs(&root, &new);
-
        error = 0;
-       path_put(&root_parent);
-       path_put(&parent_path);
-out2:
-       mutex_unlock(&old.dentry->d_inode->i_mutex);
-       up_write(&namespace_sem);
+out4:
+       unlock_mount(&old);
+       if (!error) {
+               path_put(&root_parent);
+               path_put(&parent_path);
+       }
+out3:
        path_put(&root);
+out2:
        path_put(&old);
 out1:
        path_put(&new);
 out0:
        return error;
-out3:
-       br_write_unlock(vfsmount_lock);
-       goto out2;
 }
 
 static void __init init_mount_tree(void)
@@ -2590,7 +2686,7 @@ void __init mnt_init(void)
        if (!mount_hashtable)
                panic("Failed to allocate mount hash table\n");
 
-       printk("Mount-cache hash table entries: %lu\n", HASH_SIZE);
+       printk(KERN_INFO "Mount-cache hash table entries: %lu\n", HASH_SIZE);
 
        for (u = 0; u < HASH_SIZE; u++)
                INIT_LIST_HEAD(&mount_hashtable[u]);
@@ -2623,3 +2719,28 @@ void put_mnt_ns(struct mnt_namespace *ns)
        kfree(ns);
 }
 EXPORT_SYMBOL(put_mnt_ns);
+
+struct vfsmount *kern_mount_data(struct file_system_type *type, void *data)
+{
+       struct vfsmount *mnt;
+       mnt = vfs_kern_mount(type, MS_KERNMOUNT, type->name, data);
+       if (!IS_ERR(mnt)) {
+               /*
+                * it is a longterm mount, don't release mnt until
+                * we unmount before file sys is unregistered
+               */
+               mnt_make_longterm(mnt);
+       }
+       return mnt;
+}
+EXPORT_SYMBOL_GPL(kern_mount_data);
+
+void kern_unmount(struct vfsmount *mnt)
+{
+       /* release long term mount so mount point can be released */
+       if (!IS_ERR_OR_NULL(mnt)) {
+               mnt_make_shortterm(mnt);
+               mntput(mnt);
+       }
+}
+EXPORT_SYMBOL(kern_unmount);