xfs: return a void pointer from xfs_buf_offset

This avoids all kinds of unessecary casts in an envrionment like Linux where
we can assume that pointer arithmetics are support on void pointers.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index 1790b00..a4b7d92 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -1419,9 +1419,9 @@
 	return error;
 }
 
-xfs_caddr_t
+void *
 xfs_buf_offset(
-	xfs_buf_t		*bp,
+	struct xfs_buf		*bp,
 	size_t			offset)
 {
 	struct page		*page;
@@ -1431,7 +1431,7 @@
 
 	offset += bp->b_offset;
 	page = bp->b_pages[offset >> PAGE_SHIFT];
-	return (xfs_caddr_t)page_address(page) + (offset & (PAGE_SIZE-1));
+	return page_address(page) + (offset & (PAGE_SIZE-1));
 }
 
 /*