> John Fremlin:
> > MJ Ray <markj(a)cloaked.freeserve.co.uk> writes:
> > > Hold AltGr and SysRq, then tap out s u u b (sync,
> unmount, unmount, boot)
> > You should sync after umount too or else you'll probably
> get spurious
> > fscks on boot (it needs to write a clean umount flag to the
> superblock)
>
> Surely a sync won't do anything to a read-only disk? (OK, I
> lied: "u" is
> actually remount-read-only.)
Depends whether a remount-read-only flushes out the 'file system clean' bit
when it's done at this level, or whether the change waits for the next sync,
which is presumably the concern. Aiui a normal remount/umount wouldn't
return until the flush is complete, but this method is far from normal.