Automatic fsck

[Phillip Susi]

Alexander Jones wrote:
> Because people are talking about snapshotting a FS in a potentially
> broken state, fscking it in the background---whilst continuing to use
> it!

I've been thinking something like this as well.  The whole point of fsck 
is to find and repair damage BEFORE your attempts to write to the 
filesystem cause further damage.  It kind of defeats the purpose if you 
continue manipulated the damaged volume while you check it.

> Assuming that using a broken FS doesnt hose it (admittedly it
> shouldn't), merging a changeset from a broken state into a repaired
> state is a process which I think will be extremely fragile and prone
> to breakage, /especially/ if attempted FS-agnostically.

Merging does not mean combining the changes from both copies, it means 
throwing out the changes in the read-write copy and replacing it with 
the repaired read-only copy.  The downside to this of course, is that 
any changes you made while the fsck was running are lost.  I don't think 
this is acceptable either.

I think the better solution is to fsck on shutdown ( if it must be done 
at all -- I still say an automatic fsck when no problems have been 
detected should just be disabled entirely ).  It is simpler to implement 
since it does not require LVM, and doesn't have the above problems.