gfs2: fallocate_chunk: Always initialize struct iomap

In fallocate_chunk, always initialize the iomap before calling
gfs2_iomap_get_alloc: future changes could otherwise cause things like
iomap.flags to leak across calls.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Reviewed-by: Bob Peterson <rpeterso@redhat.com>

fs/gfs2/file.c

@@ -877,7 +877,6 @@ static int fallocate_chunk(struct inode *inode, loff_t offset, loff_t len,
 	struct gfs2_inode *ip = GFS2_I(inode);
 	loff_t end = offset + len;
 	struct buffer_head *dibh;
-	struct iomap iomap = { };
 	int error;
 
 	error = gfs2_meta_inode_buffer(ip, &dibh);
@@ -893,6 +892,8 @@ static int fallocate_chunk(struct inode *inode, loff_t offset, loff_t len,
 	}
 
 	while (offset < end) {
+		struct iomap iomap = { };
+
 		error = gfs2_iomap_get_alloc(inode, offset, end - offset,
 					     &iomap);
 		if (error)