btrfs: 32-bit type problems

An assorted set of casts to get rid of the warnings on 32-bit archs.

Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index ac69f69..0e1ca42 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -1606,7 +1606,7 @@
 			extent_start;
 		ptr = btrfs_file_extent_inline_start(item) + extent_offset;
 		map = kmap(page);
-		copy_size = min(PAGE_CACHE_SIZE - page_offset,
+		copy_size = min_t(u64, PAGE_CACHE_SIZE - page_offset,
 				size - extent_offset);
 
 		em->block_start = EXTENT_MAP_INLINE;