RDWRLOCK_DMAP
IWRITE_LOCK(ipbmap, RDWRLOCK_DMAP);
IREAD_LOCK(ipbmap, RDWRLOCK_DMAP);
IREAD_LOCK(ipbmap, RDWRLOCK_DMAP);
IWRITE_LOCK(ipbmap, RDWRLOCK_DMAP);
IREAD_LOCK(ipbmap, RDWRLOCK_DMAP);
IWRITE_LOCK(ipbmap, RDWRLOCK_DMAP);
IWRITE_LOCK(ipbmap, RDWRLOCK_DMAP);
IREAD_LOCK(ipbmap, RDWRLOCK_DMAP);