[PATCH] reduce stack footprint in namespace.c
[sfrench/cifs-2.6.git] / fs / namespace.c
index e9c10cd01e1325cff95869cbb0f23aa8d14c10ce..6324dfc80dc6d7f8331c1663520ba093818f2301 100644 (file)
@@ -155,15 +155,15 @@ static void __touch_mnt_namespace(struct mnt_namespace *ns)
        }
 }
 
-static void detach_mnt(struct vfsmount *mnt, struct nameidata *old_nd)
+static void detach_mnt(struct vfsmount *mnt, struct path *old_path)
 {
-       old_nd->dentry = mnt->mnt_mountpoint;
-       old_nd->mnt = mnt->mnt_parent;
+       old_path->dentry = mnt->mnt_mountpoint;
+       old_path->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--;
+       old_path->dentry->d_mounted--;
 }
 
 void mnt_set_mountpoint(struct vfsmount *mnt, struct dentry *dentry,
@@ -174,12 +174,12 @@ void mnt_set_mountpoint(struct vfsmount *mnt, struct dentry *dentry,
        dentry->d_mounted++;
 }
 
-static void attach_mnt(struct vfsmount *mnt, struct nameidata *nd)
+static void attach_mnt(struct vfsmount *mnt, struct path *path)
 {
-       mnt_set_mountpoint(nd->mnt, nd->dentry, mnt);
+       mnt_set_mountpoint(path->mnt, path->dentry, mnt);
        list_add_tail(&mnt->mnt_hash, mount_hashtable +
-                       hash(nd->mnt, nd->dentry));
-       list_add_tail(&mnt->mnt_child, &nd->mnt->mnt_mounts);
+                       hash(path->mnt, path->dentry));
+       list_add_tail(&mnt->mnt_child, &path->mnt->mnt_mounts);
 }
 
 /*
@@ -320,6 +320,50 @@ void mnt_unpin(struct vfsmount *mnt)
 
 EXPORT_SYMBOL(mnt_unpin);
 
+static inline void mangle(struct seq_file *m, const char *s)
+{
+       seq_escape(m, s, " \t\n\\");
+}
+
+/*
+ * Simple .show_options callback for filesystems which don't want to
+ * implement more complex mount option showing.
+ *
+ * See also save_mount_options().
+ */
+int generic_show_options(struct seq_file *m, struct vfsmount *mnt)
+{
+       const char *options = mnt->mnt_sb->s_options;
+
+       if (options != NULL && options[0]) {
+               seq_putc(m, ',');
+               mangle(m, options);
+       }
+
+       return 0;
+}
+EXPORT_SYMBOL(generic_show_options);
+
+/*
+ * If filesystem uses generic_show_options(), this function should be
+ * called from the fill_super() callback.
+ *
+ * The .remount_fs callback usually needs to be handled in a special
+ * way, to make sure, that previous options are not overwritten if the
+ * remount fails.
+ *
+ * Also note, that if the filesystem's .remount_fs function doesn't
+ * reset all options to their default value, but changes only newly
+ * given options, then the displayed options will not reflect reality
+ * any more.
+ */
+void save_mount_options(struct super_block *sb, char *options)
+{
+       kfree(sb->s_options);
+       sb->s_options = kstrdup(options, GFP_KERNEL);
+}
+EXPORT_SYMBOL(save_mount_options);
+
 /* iterator */
 static void *m_start(struct seq_file *m, loff_t *pos)
 {
@@ -341,11 +385,6 @@ static void m_stop(struct seq_file *m, void *v)
        up_read(&namespace_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 = list_entry(v, struct vfsmount, mnt_list);
@@ -369,10 +408,11 @@ static int show_vfsmnt(struct seq_file *m, void *v)
                { 0, NULL }
        };
        struct proc_fs_info *fs_infop;
+       struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
 
        mangle(m, mnt->mnt_devname ? mnt->mnt_devname : "none");
        seq_putc(m, ' ');
-       seq_path(m, mnt, mnt->mnt_root, " \t\n\\");
+       seq_path(m, &mnt_path, " \t\n\\");
        seq_putc(m, ' ');
        mangle(m, mnt->mnt_sb->s_type->name);
        if (mnt->mnt_sb->s_subtype && mnt->mnt_sb->s_subtype[0]) {
@@ -404,6 +444,7 @@ struct seq_operations mounts_op = {
 static int show_vfsstat(struct seq_file *m, void *v)
 {
        struct vfsmount *mnt = list_entry(v, struct vfsmount, mnt_list);
+       struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
        int err = 0;
 
        /* device */
@@ -415,7 +456,7 @@ static int show_vfsstat(struct seq_file *m, void *v)
 
        /* mount point */
        seq_puts(m, " mounted on ");
-       seq_path(m, mnt, mnt->mnt_root, " \t\n\\");
+       seq_path(m, &mnt_path, " \t\n\\");
        seq_putc(m, ' ');
 
        /* file system type */
@@ -554,7 +595,7 @@ static int do_umount(struct vfsmount *mnt, int flags)
         *  (2) the usage count == 1 [parent vfsmount] + 1 [sys_umount]
         */
        if (flags & MNT_EXPIRE) {
-               if (mnt == current->fs->rootmnt ||
+               if (mnt == current->fs->root.mnt ||
                    flags & (MNT_FORCE | MNT_DETACH))
                        return -EINVAL;
 
@@ -589,7 +630,7 @@ static int do_umount(struct vfsmount *mnt, int flags)
         * /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)) {
+       if (mnt == current->fs->root.mnt && !(flags & MNT_DETACH)) {
                /*
                 * Special case for "unmounting" root ...
                 * we just try to remount it readonly.
@@ -640,18 +681,20 @@ asmlinkage long sys_umount(char __user * name, int flags)
        if (retval)
                goto out;
        retval = -EINVAL;
-       if (nd.dentry != nd.mnt->mnt_root)
+       if (nd.path.dentry != nd.path.mnt->mnt_root)
                goto dput_and_out;
-       if (!check_mnt(nd.mnt))
+       if (!check_mnt(nd.path.mnt))
                goto dput_and_out;
 
        retval = -EPERM;
        if (!capable(CAP_SYS_ADMIN))
                goto dput_and_out;
 
-       retval = do_umount(nd.mnt, flags);
+       retval = do_umount(nd.path.mnt, flags);
 dput_and_out:
-       path_release_on_umount(&nd);
+       /* we mustn't call path_put() as that would clear mnt_expiry_mark */
+       dput(nd.path.dentry);
+       mntput_no_expire(nd.path.mnt);
 out:
        return retval;
 }
@@ -674,10 +717,10 @@ static int mount_is_safe(struct nameidata *nd)
                return 0;
        return -EPERM;
 #ifdef notyet
-       if (S_ISLNK(nd->dentry->d_inode->i_mode))
+       if (S_ISLNK(nd->path.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)
+       if (nd->path.dentry->d_inode->i_mode & S_ISVTX) {
+               if (current->uid != nd->path.dentry->d_inode->i_uid)
                        return -EPERM;
        }
        if (vfs_permission(nd, MAY_WRITE))
@@ -701,7 +744,7 @@ struct vfsmount *copy_tree(struct vfsmount *mnt, struct dentry *dentry,
                                        int flag)
 {
        struct vfsmount *res, *p, *q, *r, *s;
-       struct nameidata nd;
+       struct path path;
 
        if (!(flag & CL_COPY_ALL) && IS_MNT_UNBINDABLE(mnt))
                return NULL;
@@ -726,14 +769,14 @@ struct vfsmount *copy_tree(struct vfsmount *mnt, struct dentry *dentry,
                                q = q->mnt_parent;
                        }
                        p = s;
-                       nd.mnt = q;
-                       nd.dentry = p->mnt_mountpoint;
+                       path.mnt = q;
+                       path.dentry = p->mnt_mountpoint;
                        q = clone_mnt(p, p->mnt_root, flag);
                        if (!q)
                                goto Enomem;
                        spin_lock(&vfsmount_lock);
                        list_add_tail(&q->mnt_list, &res->mnt_list);
-                       attach_mnt(q, &nd);
+                       attach_mnt(q, &path);
                        spin_unlock(&vfsmount_lock);
                }
        }
@@ -833,11 +876,11 @@ void drop_collected_mounts(struct vfsmount *mnt)
  * in allocations.
  */
 static int attach_recursive_mnt(struct vfsmount *source_mnt,
-                       struct nameidata *nd, struct nameidata *parent_nd)
+                       struct path *path, struct path *parent_path)
 {
        LIST_HEAD(tree_list);
-       struct vfsmount *dest_mnt = nd->mnt;
-       struct dentry *dest_dentry = nd->dentry;
+       struct vfsmount *dest_mnt = path->mnt;
+       struct dentry *dest_dentry = path->dentry;
        struct vfsmount *child, *p;
 
        if (propagate_mnt(dest_mnt, dest_dentry, source_mnt, &tree_list))
@@ -849,9 +892,9 @@ static int attach_recursive_mnt(struct vfsmount *source_mnt,
        }
 
        spin_lock(&vfsmount_lock);
-       if (parent_nd) {
-               detach_mnt(source_mnt, parent_nd);
-               attach_mnt(source_mnt, nd);
+       if (parent_path) {
+               detach_mnt(source_mnt, parent_path);
+               attach_mnt(source_mnt, path);
                touch_mnt_namespace(current->nsproxy->mnt_ns);
        } else {
                mnt_set_mountpoint(dest_mnt, dest_dentry, source_mnt);
@@ -872,13 +915,13 @@ static int graft_tree(struct vfsmount *mnt, struct nameidata *nd)
        if (mnt->mnt_sb->s_flags & MS_NOUSER)
                return -EINVAL;
 
-       if (S_ISDIR(nd->dentry->d_inode->i_mode) !=
+       if (S_ISDIR(nd->path.dentry->d_inode->i_mode) !=
              S_ISDIR(mnt->mnt_root->d_inode->i_mode))
                return -ENOTDIR;
 
        err = -ENOENT;
-       mutex_lock(&nd->dentry->d_inode->i_mutex);
-       if (IS_DEADDIR(nd->dentry->d_inode))
+       mutex_lock(&nd->path.dentry->d_inode->i_mutex);
+       if (IS_DEADDIR(nd->path.dentry->d_inode))
                goto out_unlock;
 
        err = security_sb_check_sb(mnt, nd);
@@ -886,10 +929,10 @@ static int graft_tree(struct vfsmount *mnt, struct nameidata *nd)
                goto out_unlock;
 
        err = -ENOENT;
-       if (IS_ROOT(nd->dentry) || !d_unhashed(nd->dentry))
-               err = attach_recursive_mnt(mnt, nd, NULL);
+       if (IS_ROOT(nd->path.dentry) || !d_unhashed(nd->path.dentry))
+               err = attach_recursive_mnt(mnt, &nd->path, NULL);
 out_unlock:
-       mutex_unlock(&nd->dentry->d_inode->i_mutex);
+       mutex_unlock(&nd->path.dentry->d_inode->i_mutex);
        if (!err)
                security_sb_post_addmount(mnt, nd);
        return err;
@@ -897,17 +940,18 @@ out_unlock:
 
 /*
  * recursively change the type of the mountpoint.
+ * noinline this do_mount helper to save do_mount stack space.
  */
-static int do_change_type(struct nameidata *nd, int flag)
+static noinline int do_change_type(struct nameidata *nd, int flag)
 {
-       struct vfsmount *m, *mnt = nd->mnt;
+       struct vfsmount *m, *mnt = nd->path.mnt;
        int recurse = flag & MS_REC;
        int type = flag & ~MS_REC;
 
        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;
 
-       if (nd->dentry != nd->mnt->mnt_root)
+       if (nd->path.dentry != nd->path.mnt->mnt_root)
                return -EINVAL;
 
        down_write(&namespace_sem);
@@ -921,8 +965,10 @@ static int do_change_type(struct nameidata *nd, int flag)
 
 /*
  * do loopback mount.
+ * noinline this do_mount helper to save do_mount stack space.
  */
-static int do_loopback(struct nameidata *nd, char *old_name, int recurse)
+static noinline int do_loopback(struct nameidata *nd, char *old_name,
+                               int recurse)
 {
        struct nameidata old_nd;
        struct vfsmount *mnt = NULL;
@@ -937,17 +983,17 @@ static int do_loopback(struct nameidata *nd, char *old_name, int recurse)
 
        down_write(&namespace_sem);
        err = -EINVAL;
-       if (IS_MNT_UNBINDABLE(old_nd.mnt))
-               goto out;
+       if (IS_MNT_UNBINDABLE(old_nd.path.mnt))
+               goto out;
 
-       if (!check_mnt(nd->mnt) || !check_mnt(old_nd.mnt))
+       if (!check_mnt(nd->path.mnt) || !check_mnt(old_nd.path.mnt))
                goto out;
 
        err = -ENOMEM;
        if (recurse)
-               mnt = copy_tree(old_nd.mnt, old_nd.dentry, 0);
+               mnt = copy_tree(old_nd.path.mnt, old_nd.path.dentry, 0);
        else
-               mnt = clone_mnt(old_nd.mnt, old_nd.dentry, 0);
+               mnt = clone_mnt(old_nd.path.mnt, old_nd.path.dentry, 0);
 
        if (!mnt)
                goto out;
@@ -963,7 +1009,7 @@ static int do_loopback(struct nameidata *nd, char *old_name, int recurse)
 
 out:
        up_write(&namespace_sem);
-       path_release(&old_nd);
+       path_put(&old_nd.path);
        return err;
 }
 
@@ -971,29 +1017,30 @@ out:
  * 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.
+ * noinline this do_mount helper to save do_mount stack space.
  */
-static int do_remount(struct nameidata *nd, int flags, int mnt_flags,
+static noinline int do_remount(struct nameidata *nd, int flags, int mnt_flags,
                      void *data)
 {
        int err;
-       struct super_block *sb = nd->mnt->mnt_sb;
+       struct super_block *sb = nd->path.mnt->mnt_sb;
 
        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;
 
-       if (!check_mnt(nd->mnt))
+       if (!check_mnt(nd->path.mnt))
                return -EINVAL;
 
-       if (nd->dentry != nd->mnt->mnt_root)
+       if (nd->path.dentry != nd->path.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;
+               nd->path.mnt->mnt_flags = mnt_flags;
        up_write(&sb->s_umount);
        if (!err)
-               security_sb_post_remount(nd->mnt, flags, data);
+               security_sb_post_remount(nd->path.mnt, flags, data);
        return err;
 }
 
@@ -1007,9 +1054,13 @@ static inline int tree_contains_unbindable(struct vfsmount *mnt)
        return 0;
 }
 
-static int do_move_mount(struct nameidata *nd, char *old_name)
+/*
+ * noinline this do_mount helper to save do_mount stack space.
+ */
+static noinline int do_move_mount(struct nameidata *nd, char *old_name)
 {
-       struct nameidata old_nd, parent_nd;
+       struct nameidata old_nd;
+       struct path parent_path;
        struct vfsmount *p;
        int err = 0;
        if (!capable(CAP_SYS_ADMIN))
@@ -1021,69 +1072,74 @@ static int do_move_mount(struct nameidata *nd, char *old_name)
                return err;
 
        down_write(&namespace_sem);
-       while (d_mountpoint(nd->dentry) && follow_down(&nd->mnt, &nd->dentry))
+       while (d_mountpoint(nd->path.dentry) &&
+              follow_down(&nd->path.mnt, &nd->path.dentry))
                ;
        err = -EINVAL;
-       if (!check_mnt(nd->mnt) || !check_mnt(old_nd.mnt))
+       if (!check_mnt(nd->path.mnt) || !check_mnt(old_nd.path.mnt))
                goto out;
 
        err = -ENOENT;
-       mutex_lock(&nd->dentry->d_inode->i_mutex);
-       if (IS_DEADDIR(nd->dentry->d_inode))
+       mutex_lock(&nd->path.dentry->d_inode->i_mutex);
+       if (IS_DEADDIR(nd->path.dentry->d_inode))
                goto out1;
 
-       if (!IS_ROOT(nd->dentry) && d_unhashed(nd->dentry))
+       if (!IS_ROOT(nd->path.dentry) && d_unhashed(nd->path.dentry))
                goto out1;
 
        err = -EINVAL;
-       if (old_nd.dentry != old_nd.mnt->mnt_root)
+       if (old_nd.path.dentry != old_nd.path.mnt->mnt_root)
                goto out1;
 
-       if (old_nd.mnt == old_nd.mnt->mnt_parent)
+       if (old_nd.path.mnt == old_nd.path.mnt->mnt_parent)
                goto out1;
 
-       if (S_ISDIR(nd->dentry->d_inode->i_mode) !=
-             S_ISDIR(old_nd.dentry->d_inode->i_mode))
+       if (S_ISDIR(nd->path.dentry->d_inode->i_mode) !=
+             S_ISDIR(old_nd.path.dentry->d_inode->i_mode))
                goto out1;
        /*
         * Don't move a mount residing in a shared parent.
         */
-       if (old_nd.mnt->mnt_parent && IS_MNT_SHARED(old_nd.mnt->mnt_parent))
+       if (old_nd.path.mnt->mnt_parent &&
+           IS_MNT_SHARED(old_nd.path.mnt->mnt_parent))
                goto out1;
        /*
         * Don't move a mount tree containing unbindable mounts to a destination
         * mount which is shared.
         */
-       if (IS_MNT_SHARED(nd->mnt) && tree_contains_unbindable(old_nd.mnt))
+       if (IS_MNT_SHARED(nd->path.mnt) &&
+           tree_contains_unbindable(old_nd.path.mnt))
                goto out1;
        err = -ELOOP;
-       for (p = nd->mnt; p->mnt_parent != p; p = p->mnt_parent)
-               if (p == old_nd.mnt)
+       for (p = nd->path.mnt; p->mnt_parent != p; p = p->mnt_parent)
+               if (p == old_nd.path.mnt)
                        goto out1;
 
-       if ((err = attach_recursive_mnt(old_nd.mnt, nd, &parent_nd)))
+       err = attach_recursive_mnt(old_nd.path.mnt, &nd->path, &parent_path);
+       if (err)
                goto out1;
 
        spin_lock(&vfsmount_lock);
        /* if the mount is moved, it should no longer be expire
         * automatically */
-       list_del_init(&old_nd.mnt->mnt_expire);
+       list_del_init(&old_nd.path.mnt->mnt_expire);
        spin_unlock(&vfsmount_lock);
 out1:
-       mutex_unlock(&nd->dentry->d_inode->i_mutex);
+       mutex_unlock(&nd->path.dentry->d_inode->i_mutex);
 out:
        up_write(&namespace_sem);
        if (!err)
-               path_release(&parent_nd);
-       path_release(&old_nd);
+               path_put(&parent_path);
+       path_put(&old_nd.path);
        return err;
 }
 
 /*
  * create a new mount for userspace and request it to be added into the
  * namespace's tree
+ * noinline this do_mount helper to save do_mount stack space.
  */
-static int do_new_mount(struct nameidata *nd, char *type, int flags,
+static noinline int do_new_mount(struct nameidata *nd, char *type, int flags,
                        int mnt_flags, char *name, void *data)
 {
        struct vfsmount *mnt;
@@ -1113,16 +1169,17 @@ int do_add_mount(struct vfsmount *newmnt, struct nameidata *nd,
 
        down_write(&namespace_sem);
        /* Something was mounted here while we slept */
-       while (d_mountpoint(nd->dentry) && follow_down(&nd->mnt, &nd->dentry))
+       while (d_mountpoint(nd->path.dentry) &&
+              follow_down(&nd->path.mnt, &nd->path.dentry))
                ;
        err = -EINVAL;
-       if (!check_mnt(nd->mnt))
+       if (!check_mnt(nd->path.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)
+       if (nd->path.mnt->mnt_sb == newmnt->mnt_sb &&
+           nd->path.mnt->mnt_root == nd->path.dentry)
                goto unlock;
 
        err = -EINVAL;
@@ -1458,7 +1515,7 @@ long do_mount(char *dev_name, char *dir_name, char *type_page,
                retval = do_new_mount(&nd, type_page, flags, mnt_flags,
                                      dev_name, data_page);
 dput_out:
-       path_release(&nd);
+       path_put(&nd.path);
        return retval;
 }
 
@@ -1505,17 +1562,17 @@ static struct mnt_namespace *dup_mnt_ns(struct mnt_namespace *mnt_ns,
        while (p) {
                q->mnt_ns = new_ns;
                if (fs) {
-                       if (p == fs->rootmnt) {
+                       if (p == fs->root.mnt) {
                                rootmnt = p;
-                               fs->rootmnt = mntget(q);
+                               fs->root.mnt = mntget(q);
                        }
-                       if (p == fs->pwdmnt) {
+                       if (p == fs->pwd.mnt) {
                                pwdmnt = p;
-                               fs->pwdmnt = mntget(q);
+                               fs->pwd.mnt = mntget(q);
                        }
-                       if (p == fs->altrootmnt) {
+                       if (p == fs->altroot.mnt) {
                                altrootmnt = p;
-                               fs->altrootmnt = mntget(q);
+                               fs->altroot.mnt = mntget(q);
                        }
                }
                p = next_mnt(p, mnt_ns->root);
@@ -1596,47 +1653,38 @@ out1:
  * 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)
+void set_fs_root(struct fs_struct *fs, struct path *path)
 {
-       struct dentry *old_root;
-       struct vfsmount *old_rootmnt;
+       struct path old_root;
+
        write_lock(&fs->lock);
        old_root = fs->root;
-       old_rootmnt = fs->rootmnt;
-       fs->rootmnt = mntget(mnt);
-       fs->root = dget(dentry);
+       fs->root = *path;
+       path_get(path);
        write_unlock(&fs->lock);
-       if (old_root) {
-               dput(old_root);
-               mntput(old_rootmnt);
-       }
+       if (old_root.dentry)
+               path_put(&old_root);
 }
 
 /*
  * 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)
+void set_fs_pwd(struct fs_struct *fs, struct path *path)
 {
-       struct dentry *old_pwd;
-       struct vfsmount *old_pwdmnt;
+       struct path old_pwd;
 
        write_lock(&fs->lock);
        old_pwd = fs->pwd;
-       old_pwdmnt = fs->pwdmnt;
-       fs->pwdmnt = mntget(mnt);
-       fs->pwd = dget(dentry);
+       fs->pwd = *path;
+       path_get(path);
        write_unlock(&fs->lock);
 
-       if (old_pwd) {
-               dput(old_pwd);
-               mntput(old_pwdmnt);
-       }
+       if (old_pwd.dentry)
+               path_put(&old_pwd);
 }
 
-static void chroot_fs_refs(struct nameidata *old_nd, struct nameidata *new_nd)
+static void chroot_fs_refs(struct path *old_root, struct path *new_root)
 {
        struct task_struct *g, *p;
        struct fs_struct *fs;
@@ -1648,12 +1696,12 @@ static void chroot_fs_refs(struct nameidata *old_nd, struct nameidata *new_nd)
                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);
+                       if (fs->root.dentry == old_root->dentry
+                           && fs->root.mnt == old_root->mnt)
+                               set_fs_root(fs, new_root);
+                       if (fs->pwd.dentry == old_root->dentry
+                           && fs->pwd.mnt == old_root->mnt)
+                               set_fs_pwd(fs, new_root);
                        put_fs_struct(fs);
                } else
                        task_unlock(p);
@@ -1690,7 +1738,8 @@ 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;
+       struct nameidata new_nd, old_nd, user_nd;
+       struct path parent_path, root_parent;
        int error;
 
        if (!capable(CAP_SYS_ADMIN))
@@ -1703,7 +1752,7 @@ asmlinkage long sys_pivot_root(const char __user * new_root,
        if (error)
                goto out0;
        error = -EINVAL;
-       if (!check_mnt(new_nd.mnt))
+       if (!check_mnt(new_nd.path.mnt))
                goto out1;
 
        error = __user_walk(put_old, LOOKUP_FOLLOW | LOOKUP_DIRECTORY, &old_nd);
@@ -1712,74 +1761,78 @@ asmlinkage long sys_pivot_root(const char __user * new_root,
 
        error = security_sb_pivotroot(&old_nd, &new_nd);
        if (error) {
-               path_release(&old_nd);
+               path_put(&old_nd.path);
                goto out1;
        }
 
        read_lock(&current->fs->lock);
-       user_nd.mnt = mntget(current->fs->rootmnt);
-       user_nd.dentry = dget(current->fs->root);
+       user_nd.path = current->fs->root;
+       path_get(&current->fs->root);
        read_unlock(&current->fs->lock);
        down_write(&namespace_sem);
-       mutex_lock(&old_nd.dentry->d_inode->i_mutex);
+       mutex_lock(&old_nd.path.dentry->d_inode->i_mutex);
        error = -EINVAL;
-       if (IS_MNT_SHARED(old_nd.mnt) ||
-               IS_MNT_SHARED(new_nd.mnt->mnt_parent) ||
-               IS_MNT_SHARED(user_nd.mnt->mnt_parent))
+       if (IS_MNT_SHARED(old_nd.path.mnt) ||
+               IS_MNT_SHARED(new_nd.path.mnt->mnt_parent) ||
+               IS_MNT_SHARED(user_nd.path.mnt->mnt_parent))
                goto out2;
-       if (!check_mnt(user_nd.mnt))
+       if (!check_mnt(user_nd.path.mnt))
                goto out2;
        error = -ENOENT;
-       if (IS_DEADDIR(new_nd.dentry->d_inode))
+       if (IS_DEADDIR(new_nd.path.dentry->d_inode))
                goto out2;
-       if (d_unhashed(new_nd.dentry) && !IS_ROOT(new_nd.dentry))
+       if (d_unhashed(new_nd.path.dentry) && !IS_ROOT(new_nd.path.dentry))
                goto out2;
-       if (d_unhashed(old_nd.dentry) && !IS_ROOT(old_nd.dentry))
+       if (d_unhashed(old_nd.path.dentry) && !IS_ROOT(old_nd.path.dentry))
                goto out2;
        error = -EBUSY;
-       if (new_nd.mnt == user_nd.mnt || old_nd.mnt == user_nd.mnt)
+       if (new_nd.path.mnt == user_nd.path.mnt ||
+           old_nd.path.mnt == user_nd.path.mnt)
                goto out2; /* loop, on the same file system  */
        error = -EINVAL;
-       if (user_nd.mnt->mnt_root != user_nd.dentry)
+       if (user_nd.path.mnt->mnt_root != user_nd.path.dentry)
                goto out2; /* not a mountpoint */
-       if (user_nd.mnt->mnt_parent == user_nd.mnt)
+       if (user_nd.path.mnt->mnt_parent == user_nd.path.mnt)
                goto out2; /* not attached */
-       if (new_nd.mnt->mnt_root != new_nd.dentry)
+       if (new_nd.path.mnt->mnt_root != new_nd.path.dentry)
                goto out2; /* not a mountpoint */
-       if (new_nd.mnt->mnt_parent == new_nd.mnt)
+       if (new_nd.path.mnt->mnt_parent == new_nd.path.mnt)
                goto out2; /* not attached */
-       tmp = old_nd.mnt; /* make sure we can reach put_old from new_root */
+       /* make sure we can reach put_old from new_root */
+       tmp = old_nd.path.mnt;
        spin_lock(&vfsmount_lock);
-       if (tmp != new_nd.mnt) {
+       if (tmp != new_nd.path.mnt) {
                for (;;) {
                        if (tmp->mnt_parent == tmp)
                                goto out3; /* already mounted on put_old */
-                       if (tmp->mnt_parent == new_nd.mnt)
+                       if (tmp->mnt_parent == new_nd.path.mnt)
                                break;
                        tmp = tmp->mnt_parent;
                }
-               if (!is_subdir(tmp->mnt_mountpoint, new_nd.dentry))
+               if (!is_subdir(tmp->mnt_mountpoint, new_nd.path.dentry))
                        goto out3;
-       } else if (!is_subdir(old_nd.dentry, new_nd.dentry))
+       } else if (!is_subdir(old_nd.path.dentry, new_nd.path.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 / */
+       detach_mnt(new_nd.path.mnt, &parent_path);
+       detach_mnt(user_nd.path.mnt, &root_parent);
+       /* mount old root on put_old */
+       attach_mnt(user_nd.path.mnt, &old_nd.path);
+       /* mount new_root on / */
+       attach_mnt(new_nd.path.mnt, &root_parent);
        touch_mnt_namespace(current->nsproxy->mnt_ns);
        spin_unlock(&vfsmount_lock);
-       chroot_fs_refs(&user_nd, &new_nd);
+       chroot_fs_refs(&user_nd.path, &new_nd.path);
        security_sb_post_pivotroot(&user_nd, &new_nd);
        error = 0;
-       path_release(&root_parent);
-       path_release(&parent_nd);
+       path_put(&root_parent);
+       path_put(&parent_path);
 out2:
-       mutex_unlock(&old_nd.dentry->d_inode->i_mutex);
+       mutex_unlock(&old_nd.path.dentry->d_inode->i_mutex);
        up_write(&namespace_sem);
-       path_release(&user_nd);
-       path_release(&old_nd);
+       path_put(&user_nd.path);
+       path_put(&old_nd.path);
 out1:
-       path_release(&new_nd);
+       path_put(&new_nd.path);
 out0:
        unlock_kernel();
        return error;
@@ -1792,6 +1845,7 @@ static void __init init_mount_tree(void)
 {
        struct vfsmount *mnt;
        struct mnt_namespace *ns;
+       struct path root;
 
        mnt = do_kern_mount("rootfs", 0, "rootfs", NULL);
        if (IS_ERR(mnt))
@@ -1810,8 +1864,11 @@ static void __init init_mount_tree(void)
        init_task.nsproxy->mnt_ns = ns;
        get_mnt_ns(ns);
 
-       set_fs_pwd(current->fs, ns->root, ns->root->mnt_root);
-       set_fs_root(current->fs, ns->root, ns->root->mnt_root);
+       root.mnt = ns->root;
+       root.dentry = ns->root->mnt_root;
+
+       set_fs_pwd(current->fs, &root);
+       set_fs_root(current->fs, &root);
 }
 
 void __init mnt_init(void)