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/ext4/inode.c b/fs/ext4/inode.c
index 88d57af..96c2e12 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3420,7 +3420,7 @@ static int ext4_iomap_end(struct inode *inode, loff_t offset, loff_t length,
 	return ret;
 }
 
-struct iomap_ops ext4_iomap_ops = {
+const struct iomap_ops ext4_iomap_ops = {
 	.iomap_begin		= ext4_iomap_begin,
 	.iomap_end		= ext4_iomap_end,
 };