BUF/BIO patch #3 - 32 blkno -> 64 bit byte offsets (alpha)

[Matthew Dillon <dillon@xxxxxxxxxxxxxxxxxxxx>]

    Ok, here is my first attempt at the 32 bit block number to 64 bit
    byte offset conversion for the BUF/BIO subsystem.  This is a very
    preliminary patch set, alpha quality.  Please be warned that the 
    code involves the disk I/O path so bugs can wind up corrupting the
    data on your disks.

	fetch http://apollo.backplane.com/DFlyMisc/bufbio03.patch

    This patch needs a TON of testing, especially with various filesystems
    and block devices.  The patch will be committed in two weeks, tentatively.

    Current testing status:

	cd		tested a little
	msdosfs		not tested
	ext2fs		not tested
	hpfs		not tested
	mfs		not tested
	nfs		tested a little
	ntfs		not tested
	nwfs		not tested
	scsi		not tested
	smbfs		not tested
	floppy 		not tested
	linprocfs	not tested
	coda		not tested
	specfs		not tested
	udf		not tested
	ufs		tested a little (buildworld runs)

	swap		not tested
	physio		not tested
	aio		not tested
	disklabel edit	not tested

	ata		tested a little
	mcd		not tested
	md		not tested
	scd		not tested
	vn		not tested
	aac		not tested
	amr		not tested
	ida		not tested
	ips		not tested
	mlx		not tested
	pst		not tested
	twe		not tested
	vinum		not tested