newfs on partition mounted read-only

Good people,

due to my own fatfingerness, I have managed to run newfs on mounted NTFS
partition and, to my surprise, discovered that newfs went ahead and
initialized partition without as much as giving me a warning. At first I
thought that to be specific to NTFS, but experiments have shown that
UFS2 filesystem, if mounted read-only, would meet the same fate. UFS2
mounted read/write would stop 'newfs' in its tracks.

My system is current as of August 3, 22:47 EST. Since it is not frequent
task, I unfortunately, could not point to the working version. If there
are patches to be tested, I will be glad to oblige -- I do not think one
extra newfs will hurt my NTFS partition any ;)

I have included session transcripts for both newfs's just in case there
is something obvious I am missing. I am not sure kernel config or dmesg
are relevant to the problem, but they could be provided if needed. Both
NTFS and umass (device I was playing with UFS2 on) are built as modules.
Softupdates are enabled.

RabbitsDen# mount
/dev/ad0s2a on / (ufs, NFS exported, local)
devfs on /dev (devfs, local)
/dev/ad0s1 on /C (ntfs, local, read-only)
linprocfs on /usr/compat/linux/proc (linprocfs, local)
procfs on /proc (procfs, local)
RabbitsDen# newfs /dev/ad0s1
/dev/ad0s1: 10236.7MB (20964760 sectors) block size 16384, fragment size
2048
        using 56 cylinder groups of 183.77MB, 11761 blks, 23552 inodes.
super-block backups (for fsck -b #) at:
160, 376512, 752864, 1129216, 1505568, 1881920, 2258272, 2634624,
3010976,
3387328, 3763680, 4140032, 4516384, 4892736, 5269088, 5645440, 6021792,
6398144, 6774496, 7150848, 7527200, 7903552, 8279904, 8656256, 9032608,
9408960, 9785312, 10161664, 10538016, 10914368, 11290720, 11667072,
12043424,
12419776, 12796128, 13172480, 13548832, 13925184, 14301536, 14677888,
15054240, 15430592, 15806944, 16183296, 16559648, 16936000, 17312352,
17688704, 18065056, 18441408, 18817760, 19194112, 19570464, 19946816,
20323168, 20699520

RabbitsDen# mount
/dev/ad0s2a on / (ufs, NFS exported, local)
devfs on /dev (devfs, local)
/dev/ad0s1 on /C (ntfs, local, read-only)
linprocfs on /usr/compat/linux/proc (linprocfs, local)
procfs on /proc (procfs, local)
/dev/da0s1 on /mnt (ufs, local, read-only)
RabbitsDen# newfs /dev/da0s1
/dev/da0s1: 250.0MB (511968 sectors) block size 16384, fragment size
2048
        using 4 cylinder groups of 62.50MB, 4000 blks, 8000 inodes.
super-block backups (for fsck -b #) at:
 160, 128160, 256160, 384160
RabbitsDen#

---
Alexandre "Sunny" Kovalenko.