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Re: Making forced unmounts work



On Thu, 6 Dec 2012 08:23:07 +0100
"J. Hannken-Illjes" <hannken%eis.cs.tu-bs.de@localhost> wrote:

> Looks like this thread is dead.  No one beside David Holland is
> interested and David objects.  I take back my proposal.

Have been reading the discussion. Don't assume that no contribution
means no interest!

> David wants forced unmounts to work even if a thread gets stuck
> permanently in a vnode operation.  I don't see a way to safely
> reclaim a vnode from a file system when this vnode is in use by
> another thread.

I think you could take some inspiration from Linux here: it has a very
handy umount -l which detaches the filesystem from the tree, but defers
the rest of the unmount/cleanup until the fs is no longer busy. This
can help in situations where you're not trying to physically remove
media but just need to reclaim the mount point, and therefore have no
immediate need for a umount -f. Because no process can open anything
new on the detached fs, if it eventually unwedges itself somehow it
won't get rewedged.


Julian

-- 
3072D/F3A66B3A Julian Yon (2012 General Use) <pgp.2012%jry.me@localhost>

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