Commit 8c3ee42e authored by Al Viro's avatar Al Viro
Browse files

[PATCH] get rid of more nameidata passing in namespace.c 



Further reduction of stack footprint (sys_pivot_root());
lose useless BKL in there, while we are at it.

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent b5266eb4

fs/namespace.c

+25 −28
Original line number Diff line number Diff line
@@ -1205,32 +1205,32 @@ static int attach_recursive_mnt(struct vfsmount *source_mnt, 
	return 0;

}



static int graft_tree(struct vfsmount *mnt, struct nameidata *nd)

static int graft_tree(struct vfsmount *mnt, struct path *path)

{

	int err;

	if (mnt->mnt_sb->s_flags & MS_NOUSER)

		return -EINVAL;



	if (S_ISDIR(nd->path.dentry->d_inode->i_mode) !=

	if (S_ISDIR(path->dentry->d_inode->i_mode) !=

	      S_ISDIR(mnt->mnt_root->d_inode->i_mode))

		return -ENOTDIR;



	err = -ENOENT;

	mutex_lock(&nd->path.dentry->d_inode->i_mutex);

	if (IS_DEADDIR(nd->path.dentry->d_inode))

	mutex_lock(&path->dentry->d_inode->i_mutex);

	if (IS_DEADDIR(path->dentry->d_inode))

		goto out_unlock;



	err = security_sb_check_sb(mnt, &nd->path);

	err = security_sb_check_sb(mnt, path);

	if (err)

		goto out_unlock;



	err = -ENOENT;

	if (IS_ROOT(nd->path.dentry) || !d_unhashed(nd->path.dentry))

		err = attach_recursive_mnt(mnt, &nd->path, NULL);

	if (IS_ROOT(path->dentry) || !d_unhashed(path->dentry))

		err = attach_recursive_mnt(mnt, path, NULL);

out_unlock:

	mutex_unlock(&nd->path.dentry->d_inode->i_mutex);

	mutex_unlock(&path->dentry->d_inode->i_mutex);

	if (!err)

		security_sb_post_addmount(mnt, &nd->path);

		security_sb_post_addmount(mnt, path);

	return err;

}
@@ -1294,7 +1294,7 @@ static noinline int do_loopback(struct nameidata *nd, char *old_name, 
	if (!mnt)

		goto out;



	err = graft_tree(mnt, nd);

	err = graft_tree(mnt, &nd->path);

	if (err) {

		LIST_HEAD(umount_list);

		spin_lock(&vfsmount_lock);
@@ -1501,7 +1501,7 @@ int do_add_mount(struct vfsmount *newmnt, struct nameidata *nd, 
		goto unlock;



	newmnt->mnt_flags = mnt_flags;

	if ((err = graft_tree(newmnt, nd)))

	if ((err = graft_tree(newmnt, &nd->path)))

		goto unlock;



	if (fslist) /* add to the specified expiration list */
@@ -1987,15 +1987,13 @@ asmlinkage long sys_pivot_root(const char __user * new_root, 
			       const char __user * put_old)

{

	struct vfsmount *tmp;

	struct nameidata new_nd, old_nd, user_nd;

	struct path parent_path, root_parent;

	struct nameidata new_nd, old_nd;

	struct path parent_path, root_parent, root;

	int error;



	if (!capable(CAP_SYS_ADMIN))

		return -EPERM;



	lock_kernel();



	error = __user_walk(new_root, LOOKUP_FOLLOW | LOOKUP_DIRECTORY,

			    &new_nd);

	if (error)
@@ -2015,7 +2013,7 @@ asmlinkage long sys_pivot_root(const char __user * new_root, 
	}



	read_lock(&current->fs->lock);

	user_nd.path = current->fs->root;

	root = current->fs->root;

	path_get(&current->fs->root);

	read_unlock(&current->fs->lock);

	down_write(&namespace_sem);
@@ -2023,9 +2021,9 @@ asmlinkage long sys_pivot_root(const char __user * new_root, 
	error = -EINVAL;

	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))

		IS_MNT_SHARED(root.mnt->mnt_parent))

		goto out2;

	if (!check_mnt(user_nd.path.mnt))

	if (!check_mnt(root.mnt))

		goto out2;

	error = -ENOENT;

	if (IS_DEADDIR(new_nd.path.dentry->d_inode))
@@ -2035,13 +2033,13 @@ asmlinkage long sys_pivot_root(const char __user * new_root, 
	if (d_unhashed(old_nd.path.dentry) && !IS_ROOT(old_nd.path.dentry))

		goto out2;

	error = -EBUSY;

	if (new_nd.path.mnt == user_nd.path.mnt ||

	    old_nd.path.mnt == user_nd.path.mnt)

	if (new_nd.path.mnt == root.mnt ||

	    old_nd.path.mnt == root.mnt)

		goto out2; /* loop, on the same file system  */

	error = -EINVAL;

	if (user_nd.path.mnt->mnt_root != user_nd.path.dentry)

	if (root.mnt->mnt_root != root.dentry)

		goto out2; /* not a mountpoint */

	if (user_nd.path.mnt->mnt_parent == user_nd.path.mnt)

	if (root.mnt->mnt_parent == root.mnt)

		goto out2; /* not attached */

	if (new_nd.path.mnt->mnt_root != new_nd.path.dentry)

		goto out2; /* not a mountpoint */
@@ -2063,27 +2061,26 @@ asmlinkage long sys_pivot_root(const char __user * new_root, 
	} else if (!is_subdir(old_nd.path.dentry, new_nd.path.dentry))

		goto out3;

	detach_mnt(new_nd.path.mnt, &parent_path);

	detach_mnt(user_nd.path.mnt, &root_parent);

	detach_mnt(root.mnt, &root_parent);

	/* mount old root on put_old */

	attach_mnt(user_nd.path.mnt, &old_nd.path);

	attach_mnt(root.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.path, &new_nd.path);

	security_sb_post_pivotroot(&user_nd.path, &new_nd.path);

	chroot_fs_refs(&root, &new_nd.path);

	security_sb_post_pivotroot(&root, &new_nd.path);

	error = 0;

	path_put(&root_parent);

	path_put(&parent_path);

out2:

	mutex_unlock(&old_nd.path.dentry->d_inode->i_mutex);

	up_write(&namespace_sem);

	path_put(&user_nd.path);

	path_put(&root);

	path_put(&old_nd.path);

out1:

	path_put(&new_nd.path);

out0:

	unlock_kernel();

	return error;

out3:

	spin_unlock(&vfsmount_lock);