[PATCH 1/2] xfs: add CRC infrastructure

[Andi Kleen]

Dave Chinner <david at fromorbit.com> writes:
> + */
> +static inline __uint32_t
> +xfs_start_cksum(char *buffer, size_t length, unsigned long cksum_offset)
> +{
> +	__uint32_t zero = 0;
> +	__uint32_t crc;
> +
> +	/* Calculate CRC up to the checksum. */
> +	crc = crc32c(XFS_CRC_SEED, buffer, cksum_offset);
> +
> +	/* Skip checksum field */
> +	crc = crc32c(crc, &zero, sizeof(__u32));
> +
> +	/* Calculate the rest of the CRC. */
> +	return crc32c(crc, &buffer[cksum_offset + sizeof(__be32)],
> +		      length - (cksum_offset + sizeof(__be32)));

Don't you need to remap a zero result to some other value, otherwise a
real zero checksum will never be checked?

-Andi


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