The difference is copy_page_from_iter_atomic() advances the iterator and
you don't need iov_iter_advance() after it. However, if you decide to use
only a part of obtained data, you should do iov_iter_revert().
+
+---
+
+**mandatory**
+
+Calling conventions for file_open_root() changed; now it takes struct path *
+instead of passing mount and dentry separately. For callers that used to
+pass <mnt, mnt->mnt_root> pair (i.e. the root of given mount), a new helper
+is provided - file_open_root_mnt(). In-tree users adjusted.