hfs: get rid of lock_super

Stop using lock_super for serializing the MDB changes - use the buffer-head own
lock instead. Tested with fsstress.

Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
1 file changed