Re: umount -a -f -t nfs doesn't work when a file has been written and "-l" option is needed

[Steve Dickson <SteveD@redhat.com>]

On 09/05/2009 04:31 AM, Pacho Ramos wrote:
> I suffer the following problem with nfs since a lot of time, now, I am
> using nfs-utils-1.2.0, but older versions were affected too.
> 
> When I write a file on a mounted nfs filesystem and server goes down, I
> am unable to umount it even with "-f" option, it simply hangs. On the
> other hand, if no file was written (for example, it was simply read)
> there is no problem and "umount -f" works as expected.
I believe 'umount -f' waits for all the async or sync (I can't remember)
RPC tasks to complete before returning... That's the reason for the hang.

> 
> Seems that I need to run "umount -l" for being able to unmount it, even
> when I expected that "-f" should be enough.
Hopefully you will be rebooting soon since kernel structures (ala the
super block) are not cleaned up with 'umount -l'. Which could make the
system somewhat unstable. 

> 
> Is this the proper behavior or something is going wrong?
Its the known behaviour... whether its correct or not is up to
interpretation... ;-) Meaning, 'umount -f' probably should
not hang waiting for I/O to finish, but error-ing on the "lets 
do everything we can not to corrupt data" is not a bad stand either...

steved.