Subject: Clean bit bits
To: None <tech-kern@NetBSD.ORG>
From: None <>
List: tech-kern
Date: 01/12/1996 14:14:31
About the FS clean bits: the discussion seems a bit schizophrenic to me.
I'm inclined to say that you should either trust the clean bit, or
you don't. If you don't, fine, there might be a number of reasons
why you suspect your FS is not clean, so just always do an fsck at

If you can name reasons why there should be a periodic fsck, one could use
those exact same reasons to argue that there _always_ should be an

I can't see any situation where it might be more practical to have
an extra fsck based on time/operations than always an fsck or never.

Correct me if I'm wrong though. I know people will flame me for this
anyway, since this is probably a very unpopular view to hold :-)
Perhaps it is too black-and-white, but..

Actually, thinking about it, I can come up with a reason to not set the
clean bit.. Suppose you have a disk that is very very reliable, so you trust
it, and the chance of hardware failure is close to 0 (if you didn't trust
it, you always should do an fsck). And suppose your FS is implemented well,
and you trust it not to mess up (if you didn't trust it, you should
always do an fsck). The only (?) way in which your filesystem would end
up in a messed up state, is that some process directly opens the disk
device and flips some bits. So a reason not to set the clean bit when
unmounting, is if, at any point in time, the device has been opened for

- Frank