static int encrypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat,
			       struct scatterlist *dest_sg,
			       struct scatterlist *src_sg, int size,
			       unsigned char *iv)
{
	struct blkcipher_desc desc = {
		.tfm = crypt_stat->tfm,
		.info = iv,
		.flags = CRYPTO_TFM_REQ_MAY_SLEEP
	};
	int rc = 0;

	BUG_ON(!crypt_stat || !crypt_stat->tfm
	       || !(crypt_stat->flags & ECRYPTFS_STRUCT_INITIALIZED));
	if (unlikely(ecryptfs_verbosity > 0)) {
		ecryptfs_printk(KERN_DEBUG, "Key size [%d]; key:\n",
				crypt_stat->key_size);
		ecryptfs_dump_hex(crypt_stat->key,
				  crypt_stat->key_size);
	}
	/* Consider doing this once, when the file is opened */
	mutex_lock(&crypt_stat->cs_tfm_mutex);
	if (!(crypt_stat->flags & ECRYPTFS_KEY_SET)) {
		rc = crypto_blkcipher_setkey(crypt_stat->tfm, crypt_stat->key,
					     crypt_stat->key_size);
		crypt_stat->flags |= ECRYPTFS_KEY_SET;
	}
	if (rc) {
		ecryptfs_printk(KERN_ERR, "Error setting key; rc = [%d]\n",
				rc);
		mutex_unlock(&crypt_stat->cs_tfm_mutex);
		rc = -EINVAL;
		goto out;
	}
	ecryptfs_printk(KERN_DEBUG, "Encrypting [%d] bytes.\n", size);
	crypto_blkcipher_encrypt_iv(&desc, dest_sg, src_sg, size);
	mutex_unlock(&crypt_stat->cs_tfm_mutex);
out:
	return rc;
}