In gfs2_file_buffered_write(), we currently jump from the second call of
function should_fault_in_pages() to above the first call, so
should_fault_in_pages() is getting called twice in a row, causing it to
accidentally fall back to single-page writes rather than trying the more
efficient multi-page writes first.

Fix that by moving the retry label to the correct place, behind the
first call to should_fault_in_pages().

Fixes: e1fa9ea8 ("gfs2: Stop using glock holder auto-demotion for now")
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>