libxfs: move header files

Move all the header files that are shared with userspace into
libxfs. This is done as one big chunk simpy to get it done quickly.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

1 files changed, 63 insertions, 0 deletions

diff --git a/fs/xfs/libxfs/xfs_cksum.h b/fs/xfs/libxfs/xfs_cksum.h
new file mode 100644
index 000000000000..fad1676ad8cd
--- /dev/null
+++ b/fs/xfs/libxfs/xfs_cksum.h
@@ -0,0 +1,63 @@
+#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.
+ */
+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)));
+}
+
+/*
+ * 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.
+ */
+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);
+
+        *(__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(buffer, length, cksum_offset);
+
+        return *(__le32 *)(buffer + cksum_offset) == xfs_end_cksum(crc);
+}
+
+#endif /* _XFS_CKSUM_H */