On Wed, 24 Sep 2008, Christos Zoulas wrote:
This also breaks products which run from flash with their filesystems mounted read-only most of the time, but remount them read-write in order to write back configuration data when it changes. That is not an uncommon model AFAIK and it poses a fairly major problem for me.
[snip]
We write or alter a couple of configuration files, sync and then remount r/o. I've not seen any problems with netbsd-3 or netbsd-4. Is it believed that this problem is a regression in -current?No, it's been there forever.
That's what I understood from discussions with developers. However, this procedure is used daily in many thousands of live product and we've not had a single report of a problem.
Even thornier is the issue of, having a process that has an open for write file descriptor open on the fs to be re-mounted. In that case the remount should fail with EBUSY but last time I checked it does not.
Well, yes, that's an obvious issue, but is a separate problem. It can also be filed under "give 'em enough rope and they'll hang themselves".
-- Stephen