Subject: Re: Corrupt data when reading filesystems under Linux guest
To: None <port-xen@NetBSD.org>
From: Jed Davis <email@example.com>
Date: 06/20/2005 23:45:14
I've restructured a lot of xbdback.c; it now should handle xbd requests
that can't be made into one VM range, and merges requests/segments where
possible, including the weird broken Linux case. For this last, I put
in a simplisticly ratecheck(9)ed printf to inform the administrator.
At Thor's instigation, I dealt with blocking allocation in a
continuation-inspired manner; I did not use kcont(9) for this because
I'd have had to fix and enhance kcont(9) first, and I didn't need any of
the IPL-lowering mechanisms.
It's a little unclean in a few other places, too; the interface with
xen_shm comes to mind (xennet uses it too, so I was reluctant to change
it right away), as does the misuse of splvm() for locking that I cribbed
off of kcont (wait; how can that work if kcont's are being enqueued from
a high IPL? Doesn't matter for this, as the worst it'll get is splbio,
Nonetheless, it appears to both work and not kill performance even in
the annoying Linux case. The diff (against the netbsd-3 branch) can be
obtained at http://www.panix.com/~jld/xbdback-rc1.patch (~33kB).
(let ((C call-with-current-continuation)) (apply (lambda (x y) (x y)) (map
((lambda (r) ((C C) (lambda (s) (r (lambda l (apply (s s) l)))))) (lambda
(f) (lambda (l) (if (null? l) C (lambda (k) (display (car l)) ((f (cdr l))
(C k))))))) '((#\J #\d #\D #\v #\s) (#\e #\space #\a #\i #\newline)))))