BLKDEV_IOSIZE
#ifndef BLKDEV_IOSIZE
drive->blocksize = BLKDEV_IOSIZE; /* do we need this? */
iosize = BLKDEV_IOSIZE;
if (sb->st_blksize < BLKDEV_IOSIZE)
sb->st_blksize = BLKDEV_IOSIZE;