rem: return v->mount->fs->calls->fs_write(v->mount->cookie, v->priv_vnode, f->cookie, buffer, pos, length);
add: return FS_CALL(vnode,fs_write)(vnode->mount->cookie, vnode->private_node, descriptor->cookie, buffer, pos, length);
context: file_write(struct file_descriptor *f, const void *buffer, off_t pos, size_t *length){	struct vnode *v = f->vnode;	FUNCTION(("file_write: buf %p, pos %Ld, len 0x%p\n", buffer, pos, length));	return v->mount->fs->calls->fs_write(v->mount->cookie, v->priv_vnode, f->cookie, buffer, pos, length);}