DM_DEV_SUSPEND_CMD 1678 drivers/md/dm-ioctl.c 		{DM_DEV_SUSPEND_CMD, IOCTL_FLAGS_NO_PARAMS, dev_suspend},
DM_DEV_SUSPEND_CMD  258 include/uapi/linux/dm-ioctl.h #define DM_DEV_SUSPEND   _IOWR(DM_IOCTL, DM_DEV_SUSPEND_CMD, struct dm_ioctl)