MAPBUF_LEN
if (MAPBUF_LEN < SUPERBLOCK->fs_bsize)
bsize = MAPBUF_LEN;
if (offset + MAPBUF_LEN > SUPERBLOCK->fs_bsize)
offset = (SUPERBLOCK->fs_bsize - MAPBUF_LEN) / sizeof (int);
if (MAPBUF_LEN < SUPERBLOCK->fs_bsize)
bsize = MAPBUF_LEN;
if (offset + MAPBUF_LEN > SUPERBLOCK->fs_bsize)
offset = (SUPERBLOCK->fs_bsize - MAPBUF_LEN) / sizeof (int);