All symbols starting with `d' in ufs/ffs

• dblksize ufs/ffs/fs.h:419
• dbtofsb ufs/ffs/fs.h:330
• doclusterread ufs/ffs/ffs_vnops.c:214
• doclusterwrite ufs/ffs/ffs_vnops.c:216
• DOUBLE ufs/ffs/ffs_inode.c:132
• dtog ufs/ffs/fs.h:360
• dtogd ufs/ffs/fs.h:361