bin/38171: mount_ffs doesn't work on CDs

[hbent%cs.oberlin.edu@localhost]

>Number:         38171
>Category:       bin
>Synopsis:       mount_ffs doesn't work on CDs
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    bin-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Wed Mar 05 08:45:01 +0000 2008
>Originator:     Henry Bent
>Release:        4.99.51
>Organization:
>Environment:
NetBSD aelfric 4.99.51 NetBSD 4.99.51 (AELFRIC) #0: Mon Mar  3 04:24:43 EST 
2008  root@aelfric:/usr/obj/src-current/sys/arch/i386/compile/AELFRIC i386
>Description:
I have a great number of old DEC CD-ROMs that are just UFS filesystems  on CDs. 
 None of them will mount as-is.  If I create an image of the CD and attach it 
with vnd, it will mount correctly.

An example:

aelfric# mount /dev/cd0a /cdrom
mount_ffs: /dev/cd0a on /cdrom: incorrect super block
aelfric# dd if=/dev/rcd0a of=cdrom.img bs=1m
407+1 records in
407+1 records out
427008000 bytes transferred in 106.760 secs (3999700 bytes/sec)
aelfric# file cdrom.img
cdrom.img: Unix Fast File system [v1] (little-endian), last mounted on /mnt, 
last written at Tue Apr 28 09:09:37 1992, clean flag 30, number of blocks 
416256, number of data blocks 390670, number of cylinder groups 94, block size 
8192, fragment size 1024, minimum percentage of free blocks 10, rotational 
delay 0ms, disk rotational speed 60rps, TIME optimization
aelfric# vnconfig -r vnd0 cdrom.img
aelfric# mount -r /dev/vnd0a /mnt
aelfric# ls /mnt
RISC  lost+found

but every disc does essentially the same thing, they're just different sizes.
>How-To-Repeat:
Mount an old DEC CD-ROM.  I assume that burning a raw FFS filesystem onto a CD 
and then trying to mount it would also fail, but I don't have any blanks at the 
moment to test that theory.
>Fix:
Nope, sorry.