1*84be0ffcSDave Chinner #ifndef _XFS_CKSUM_H 2*84be0ffcSDave Chinner #define _XFS_CKSUM_H 1 3*84be0ffcSDave Chinner 4*84be0ffcSDave Chinner #define XFS_CRC_SEED (~(__uint32_t)0) 5*84be0ffcSDave Chinner 6*84be0ffcSDave Chinner /* 7*84be0ffcSDave Chinner * Calculate the intermediate checksum for a buffer that has the CRC field 8*84be0ffcSDave Chinner * inside it. The offset of the 32bit crc fields is passed as the 9*84be0ffcSDave Chinner * cksum_offset parameter. 10*84be0ffcSDave Chinner */ 11*84be0ffcSDave Chinner static inline __uint32_t 12*84be0ffcSDave Chinner xfs_start_cksum(char *buffer, size_t length, unsigned long cksum_offset) 13*84be0ffcSDave Chinner { 14*84be0ffcSDave Chinner __uint32_t zero = 0; 15*84be0ffcSDave Chinner __uint32_t crc; 16*84be0ffcSDave Chinner 17*84be0ffcSDave Chinner /* Calculate CRC up to the checksum. */ 18*84be0ffcSDave Chinner crc = crc32c(XFS_CRC_SEED, buffer, cksum_offset); 19*84be0ffcSDave Chinner 20*84be0ffcSDave Chinner /* Skip checksum field */ 21*84be0ffcSDave Chinner crc = crc32c(crc, &zero, sizeof(__u32)); 22*84be0ffcSDave Chinner 23*84be0ffcSDave Chinner /* Calculate the rest of the CRC. */ 24*84be0ffcSDave Chinner return crc32c(crc, &buffer[cksum_offset + sizeof(__be32)], 25*84be0ffcSDave Chinner length - (cksum_offset + sizeof(__be32))); 26*84be0ffcSDave Chinner } 27*84be0ffcSDave Chinner 28*84be0ffcSDave Chinner /* 29*84be0ffcSDave Chinner * Convert the intermediate checksum to the final ondisk format. 30*84be0ffcSDave Chinner * 31*84be0ffcSDave Chinner * The CRC32c calculation uses LE format even on BE machines, but returns the 32*84be0ffcSDave Chinner * result in host endian format. Hence we need to byte swap it back to LE format 33*84be0ffcSDave Chinner * so that it is consistent on disk. 34*84be0ffcSDave Chinner */ 35*84be0ffcSDave Chinner static inline __le32 36*84be0ffcSDave Chinner xfs_end_cksum(__uint32_t crc) 37*84be0ffcSDave Chinner { 38*84be0ffcSDave Chinner return ~cpu_to_le32(crc); 39*84be0ffcSDave Chinner } 40*84be0ffcSDave Chinner 41*84be0ffcSDave Chinner /* 42*84be0ffcSDave Chinner * Helper to generate the checksum for a buffer. 43*84be0ffcSDave Chinner */ 44*84be0ffcSDave Chinner static inline void 45*84be0ffcSDave Chinner xfs_update_cksum(char *buffer, size_t length, unsigned long cksum_offset) 46*84be0ffcSDave Chinner { 47*84be0ffcSDave Chinner __uint32_t crc = xfs_start_cksum(buffer, length, cksum_offset); 48*84be0ffcSDave Chinner 49*84be0ffcSDave Chinner *(__le32 *)(buffer + cksum_offset) = xfs_end_cksum(crc); 50*84be0ffcSDave Chinner } 51*84be0ffcSDave Chinner 52*84be0ffcSDave Chinner /* 53*84be0ffcSDave Chinner * Helper to verify the checksum for a buffer. 54*84be0ffcSDave Chinner */ 55*84be0ffcSDave Chinner static inline int 56*84be0ffcSDave Chinner xfs_verify_cksum(char *buffer, size_t length, unsigned long cksum_offset) 57*84be0ffcSDave Chinner { 58*84be0ffcSDave Chinner __uint32_t crc = xfs_start_cksum(buffer, length, cksum_offset); 59*84be0ffcSDave Chinner 60*84be0ffcSDave Chinner return *(__le32 *)(buffer + cksum_offset) == xfs_end_cksum(crc); 61*84be0ffcSDave Chinner } 62*84be0ffcSDave Chinner 63*84be0ffcSDave Chinner #endif /* _XFS_CKSUM_H */ 64