"!fs->fs_ronly" panic on mount on netbsd-11

[David Brownlee <abs%absd.org@localhost>]

Just had the following on two separate systems after an unclean reboot

/dev/rwd0a: file system is journaled; not checking
[   3.6766168] /dev/wd0a: file system not clean (fs_clean=0x2); please fsck(8)
[   3.6766168] panic: kernel diagnostic assertion "!fs->fs_ronly"
failed: file "/usr/src/sys/ufs/ffs/ffs_vfsops.c", line 774
[   3.6865939] cpu3: Begin traceback...

They are running netbsd-11 stable from releng

11.0_BETA NetBSD 11.0_BETA (GENERIC) #0: Thu Jan  8 10:53:08 UTC 2026
mkrepro%mkrepro.NetBSD.org@localhost:/usr/src/sys/arch/amd64/compile/GENERIC
amd64

This looks to be new - I've not had it on earlier netbsd-11 and
netbsd-10 versions. Does it ring a bell for anyone?

Thanks

David