fh_sg_list
struct fh_sg_list *sg_list = NULL;
sg_list_unaligned = kmalloc(num_pages * sizeof(struct fh_sg_list) +
sizeof(struct fh_sg_list) - 1, GFP_KERNEL);
sg_list = PTR_ALIGN(sg_list_unaligned, sizeof(struct fh_sg_list));