ext4: fix online resizing for ext3-compat file systems

ext4: fix online resizing for ext3-compat file systems

commit c5c72d814cf0f650010337c73638b25e6d14d2d4 upstream.

Commit fb0a387dcdc restricts block allocations for indirect-mapped
files to block groups less than s_blockfile_groups.  However, the
online resizing code wasn't setting s_blockfile_groups, so the newly
added block groups were not available for non-extent mapped files.

Reported-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>