kern.geom.debugflags=16 does NOT allow me to write to device

[Peter Schuller]

open() in O_RDWR fails on the device in question (which is "used" by
glabel, indirectly by gmirror and zfs).

This is on an 8.0 userland and 8-STABLE kernel. This is a bit stupid I
know (nevermind why), but given that a plain open() syscall is failing
I highly doubt that it has anything to do with the userland being out
of synch. I cannot imagine GEOM changing like that in between 8.0 and
8-STABLE before the 8.1 release (correct me if this is a poor
assumption).

Observe:

% whoami
root
% sysctl -w kern.geom.debugflags=16
kern.geom.debugflags: 16 -> 16
% sysctl kern.geom.debugflags
kern.geom.debugflags: 16
% ktrace disklabel -B /dev/ad9s1
disklabel: Class not found

kdump shows:

 15399 disklabel CALL  open(0x800c02040,O_RDWR,<unused>0xa1a5)
 15399 disklabel NAMI  "/dev/ad9s1"
 15399 disklabel RET   open -1 errno 1 Operation not permitted
 15399 disklabel CALL  open(0x800651b68,O_RDONLY,<unused>0)
 15399 disklabel NAMI  "/dev/geom.ctl"
 15399 disklabel RET   open 4
 15399 disklabel CALL  ioctl(0x4,GEOM_CTL,0x800c04040)
 15399 disklabel RET   ioctl 0
 15399 disklabel CALL  close(0x4)
 15399 disklabel RET   close 0
 15399 disklabel CALL  write(0x2,0x7fffffffde90,0xb)
 15399 disklabel GIO   fd 2 wrote 11 bytes
       "disklabel: "
 15399 disklabel RET   write 11/0xb
 15399 disklabel CALL  write(0x2,0x7fffffffdf70,0xf)
 15399 disklabel GIO   fd 2 wrote 15 bytes
       "Class not found"
 15399 disklabel RET   write 15/0xf

It has these labels:

label/prboot1r1     N/A  ad9s1a
label/prswap1r1     N/A  ad9s1b
label/prtank1r1     N/A  ad9s1d

prtank1r1 is part of a ZFS pool.

-- 
/ Peter Schuller