Re: [PATCH v13 10/12] fscrypt: add inline encryption support

[Eric Biggers <ebiggers@kernel.org>]

One more thing:

On Thu, May 14, 2020 at 12:37:25AM +0000, Satya Tangirala wrote:
> +/* Enable inline encryption for this file if supported. */
> +void fscrypt_select_encryption_impl(struct fscrypt_info *ci)
> +{
> +	const struct inode *inode = ci->ci_inode;
> +	struct super_block *sb = inode->i_sb;
> +	struct blk_crypto_config crypto_cfg;
> +	int num_devs;
> +	struct request_queue **devs;
> +	int i;
> +
> +	/* The file must need contents encryption, not filenames encryption */
> +	if (!fscrypt_needs_contents_encryption(inode))
> +		return;
> +
> +	/* The crypto mode must be valid */
> +	if (ci->ci_mode->blk_crypto_mode == BLK_ENCRYPTION_MODE_INVALID)
> +		return;
> +
> +	/* The filesystem must be mounted with -o inlinecrypt */
> +	if (!(sb->s_flags & SB_INLINECRYPT))
> +		return;
> +
> +	/*
> +	 * blk-crypto must support the crypto configuration we'll use for the
> +	 * inode on all devices in the sb
> +	 */
> +	crypto_cfg.crypto_mode = ci->ci_mode->blk_crypto_mode;
> +	crypto_cfg.data_unit_size = sb->s_blocksize;
> +	crypto_cfg.dun_bytes = fscrypt_get_dun_bytes(ci);
> +	num_devs = fscrypt_get_num_devices(sb);
> +	devs = kmalloc_array(num_devs, sizeof(*devs), GFP_NOFS);
> +	if (!devs)
> +		return;

This function needs to return an error code, so that if this memory allocation
fails, the error is not ignored.

- Eric