magic sysrq keys functionality

[Garrett Wollman]

<<On Mon, 26 Jul 2004 16:06:33 -0600 (MDT), Scott Long <scottl at FreeBSD.ORG> said:

> This works right now because we assume that disks will commit blocks
> in order, and that assumption generally hasn't been broken.

I don't think soft updates cares about what order blocks are
committed, because it will not in general consider a dependency
resolved until it is notified that the buffer has been written.  What
we do assume is that the disk (or driver) doesn't lie to us and claim
that a block was written when it really wasn't.

-GAWollman