In check_extents() and check_dirents(), we're working towards only
handling transaction restarts in one place, at the top level - but we're
not there yet. check_i_sectors() and check_subdir_count() handle
transaction restarts locally, which means the iterator for the
dirent/extent is left unlocked (should_be_locked == 0), leading to
asserts popping when we go to do updates.

This patch hacks around this for now, until we can delete the offending
code.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>