@@ -6,10 +6,11 @@
/*
* 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.
+ * 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(char *buffer, size_t length, unsigned long cksum_offset)
+xfs_start_cksum_safe(char *buffer, size_t length, unsigned long cksum_offset)
{
__uint32_t zero = 0;
__uint32_t crc;
@@ -26,6 +27,20 @@ xfs_start_cksum(char *buffer, size_t length, unsigned long cksum_offset)
}
/*
+ * 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
@@ -40,11 +55,14 @@ xfs_end_cksum(__uint32_t 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(buffer, length, cksum_offset);
+ __uint32_t crc = xfs_start_cksum_update(buffer, length, cksum_offset);
*(__le32 *)(buffer + cksum_offset) = xfs_end_cksum(crc);
}
@@ -55,7 +73,7 @@ xfs_update_cksum(char *buffer, size_t length, unsigned long cksum_offset)
static inline int
xfs_verify_cksum(char *buffer, size_t length, unsigned long cksum_offset)
{
- __uint32_t crc = xfs_start_cksum(buffer, length, cksum_offset);
+ __uint32_t crc = xfs_start_cksum_safe(buffer, length, cksum_offset);
return *(__le32 *)(buffer + cksum_offset) == xfs_end_cksum(crc);
}
@@ -436,7 +436,7 @@ xfs_dinode_calc_crc(
return;
ASSERT(xfs_sb_version_hascrc(&mp->m_sb));
- crc = xfs_start_cksum((char *)dip, mp->m_sb.sb_inodesize,
+ crc = xfs_start_cksum_update((char *)dip, mp->m_sb.sb_inodesize,
XFS_DINODE_CRC_OFF);
dip->di_crc = xfs_end_cksum(crc);
}
@@ -1668,7 +1668,7 @@ xlog_cksum(
__uint32_t crc;
/* first generate the crc for the record header ... */
- crc = xfs_start_cksum((char *)rhead,
+ crc = xfs_start_cksum_update((char *)rhead,
sizeof(struct xlog_rec_header),
offsetof(struct xlog_rec_header, h_crc));
@@ -5113,19 +5113,21 @@ xlog_recover_process(
struct list_head *buffer_list)
{
int error;
+ __le32 old_crc = rhead->h_crc;
__le32 crc;
+
crc = xlog_cksum(log, rhead, dp, be32_to_cpu(rhead->h_len));
/*
* Nothing else to do if this is a CRC verification pass. Just return
* if this a record with a non-zero crc. Unfortunately, mkfs always
- * sets h_crc to 0 so we must consider this valid even on v5 supers.
+ * sets old_crc to 0 so we must consider this valid even on v5 supers.
* Otherwise, return EFSBADCRC on failure so the callers up the stack
* know precisely what failed.
*/
if (pass == XLOG_RECOVER_CRCPASS) {
- if (rhead->h_crc && crc != rhead->h_crc)
+ if (old_crc && crc != old_crc)
return -EFSBADCRC;
return 0;
}
@@ -5136,11 +5138,11 @@ xlog_recover_process(
* zero CRC check prevents warnings from being emitted when upgrading
* the kernel from one that does not add CRCs by default.
*/
- if (crc != rhead->h_crc) {
- if (rhead->h_crc || xfs_sb_version_hascrc(&log->l_mp->m_sb)) {
+ if (crc != old_crc) {
+ if (old_crc || xfs_sb_version_hascrc(&log->l_mp->m_sb)) {
xfs_alert(log->l_mp,
"log record CRC mismatch: found 0x%x, expected 0x%x.",
- le32_to_cpu(rhead->h_crc),
+ le32_to_cpu(old_crc),
le32_to_cpu(crc));
xfs_hex_dump(dp, 32);
}