Messages in this thread | | | Date | Mon, 20 Aug 2007 16:34:14 -0700 | Subject | Re: NFS hang + umount -f: better behaviour requested. | From | Robin Lee Powell <> |
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On Tue, Aug 21, 2007 at 09:27:06AM +1000, Neil Brown wrote: > On Monday August 20, rlpowell@digitalkingdom.org wrote: > > (cc's to me appreciated) > > > > It would be really, really nice if "umount -f" against a hung > > NFS mount actually worked on Linux. As much as I hate Solaris, > > I consider it the gold standard in this case: If I say "umount > > -f /mount/that/is/hung" it just goes away, immediately, and > > anything still trying to use it dies (with EIO, I'm told). > > Have you tried "umount -l"? How far is that from your > requirements?
I actually talked about that further down. The short version: quite far.
The long version:
It leaves a bunch of hung processes, with no real way for me to determine which processes are hung on the now-non-existent mount, and (at least with autofs) it leaves /etc/mtab in an inconsistent state, so I had to edit it to restart autofs. Only a mild improvement on rebooting, says I.
Also, it took a really long time (minutes) to return.
> Alternately: > mount --move /problem/path /somewhere/else > umount -f /somewhere/else > umount -l /somewhere/else > > might be a little closer to what you want.
I don't think that would solve the problem: the umount -f would still hang and eventually return busy, fuser would still hang, and umount -l would still leave inconsistent crap lying around.
> Though I agree that it would be nice if we could convince all > subsequent requests to a server to fail EIO instead of just the > currently active ones. I'm not sure that just changing "umount > -f" is the right interface though.... Maybe if all the server > handles appeared in sysfs and have an attribute which you could > set to cause all requests to fail...
I have no opinion on interface details, I simply know that on Solaris, "umount -f" Just Works, and I would love to have similar behaviour on Linux.
-Robin
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