iomap: constify struct iomap_ops

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
diff --git a/fs/internal.h b/fs/internal.h
index b63cf3a..11c6d89 100644
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -182,7 +182,7 @@
 		void *data, struct iomap *iomap);
 
 loff_t iomap_apply(struct inode *inode, loff_t pos, loff_t length,
-		unsigned flags, struct iomap_ops *ops, void *data,
+		unsigned flags, const struct iomap_ops *ops, void *data,
 		iomap_actor_t actor);
 
 /* direct-io.c: */