xfs: add CRC infrastructure

 - add a mount feature bit for CRC enabled filesystems
 - add some helpers for generating and verifying the CRCs
 - add a copy_uuid helper

The checksumming helpers are loosely based on similar ones in sctp,
all other bits come from Dave Chinner.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>

diff --git a/fs/xfs/xfs_linux.h b/fs/xfs/xfs_linux.h
index 0a134ca..fe7e4df 100644
--- a/fs/xfs/xfs_linux.h
+++ b/fs/xfs/xfs_linux.h
@@ -44,6 +44,7 @@
 #include <linux/kernel.h>
 #include <linux/blkdev.h>
 #include <linux/slab.h>
+#include <linux/crc32c.h>
 #include <linux/module.h>
 #include <linux/mutex.h>
 #include <linux/file.h>