diff --git a/fs/xfs/libxfs/xfs_cksum.h b/fs/xfs/libxfs/xfs_cksum.h
index fad1676ad8cd..a416c7cb23ea 100644
--- a/fs/xfs/libxfs/xfs_cksum.h
+++ b/fs/xfs/libxfs/xfs_cksum.h
@@ -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);
 }
diff --git a/fs/xfs/libxfs/xfs_inode_buf.c b/fs/xfs/libxfs/xfs_inode_buf.c
index 54817f82212c..5efeb4233387 100644
--- a/fs/xfs/libxfs/xfs_inode_buf.c
+++ b/fs/xfs/libxfs/xfs_inode_buf.c
@@ -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);
 }
diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
index 3b74fa011bb1..3ebe444eb60f 100644
--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -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));
 
diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c
index cf754bcbcb1c..4a98762ec8b4 100644
--- a/fs/xfs/xfs_log_recover.c
+++ b/fs/xfs/xfs_log_recover.c
@@ -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);
 		}
