mirror of https://gitee.com/openkylin/linux.git
83 lines
2.3 KiB
C
83 lines
2.3 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
|
|
#ifndef _XFS_CKSUM_H
|
|
#define _XFS_CKSUM_H 1
|
|
|
|
#define XFS_CRC_SEED (~(uint32_t)0)
|
|
|
|
/*
|
|
* Calculate the intermediate checksum for a buffer that has the CRC field
|
|
* inside it. The offset of the 32bit crc fields is passed as the
|
|
* cksum_offset parameter. We do not modify the buffer during verification,
|
|
* hence we have to split the CRC calculation across the cksum_offset.
|
|
*/
|
|
static inline uint32_t
|
|
xfs_start_cksum_safe(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)));
|
|
}
|
|
|
|
/*
|
|
* Fast CRC method where the buffer is modified. Callers must have exclusive
|
|
* access to the buffer while the calculation takes place.
|
|
*/
|
|
static inline uint32_t
|
|
xfs_start_cksum_update(char *buffer, size_t length, unsigned long cksum_offset)
|
|
{
|
|
/* zero the CRC field */
|
|
*(__le32 *)(buffer + cksum_offset) = 0;
|
|
|
|
/* single pass CRC calculation for the entire buffer */
|
|
return crc32c(XFS_CRC_SEED, buffer, length);
|
|
}
|
|
|
|
/*
|
|
* Convert the intermediate checksum to the final ondisk format.
|
|
*
|
|
* The CRC32c calculation uses LE format even on BE machines, but returns the
|
|
* result in host endian format. Hence we need to byte swap it back to LE format
|
|
* so that it is consistent on disk.
|
|
*/
|
|
static inline __le32
|
|
xfs_end_cksum(uint32_t crc)
|
|
{
|
|
return ~cpu_to_le32(crc);
|
|
}
|
|
|
|
/*
|
|
* Helper to generate the checksum for a buffer.
|
|
*
|
|
* This modifies the buffer temporarily - callers must have exclusive
|
|
* access to the buffer while the calculation takes place.
|
|
*/
|
|
static inline void
|
|
xfs_update_cksum(char *buffer, size_t length, unsigned long cksum_offset)
|
|
{
|
|
uint32_t crc = xfs_start_cksum_update(buffer, length, cksum_offset);
|
|
|
|
*(__le32 *)(buffer + cksum_offset) = xfs_end_cksum(crc);
|
|
}
|
|
|
|
/*
|
|
* Helper to verify the checksum for a buffer.
|
|
*/
|
|
static inline int
|
|
xfs_verify_cksum(char *buffer, size_t length, unsigned long cksum_offset)
|
|
{
|
|
uint32_t crc = xfs_start_cksum_safe(buffer, length, cksum_offset);
|
|
|
|
return *(__le32 *)(buffer + cksum_offset) == xfs_end_cksum(crc);
|
|
}
|
|
|
|
#endif /* _XFS_CKSUM_H */
|