Messages in this thread | | | Subject | Re: [RFC] atomic create+open | From | Trond Myklebust <> | Date | Fri, 07 Oct 2005 12:23:47 -0400 |
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fr den 07.10.2005 Klokka 17:28 (+0200) skreiv Miklos Szeredi: > > > > Which may return yet another result for the dentry and another race. > > There is no guarantee that you will ever make progress if someone is > > doing something like. > > > > while true > > do > > echo "1" > foo > > echo "2" > foo > > done > > > > on the server. > > Not good example. This won't change the file, only the contents. > Something with rename would be better.
Sorry, yes. This tweak should demonstrate what I meant
while true do echo "1" > foo echo "2" > bar mv bar foo done
> We are still pitting two different races against each other. I can't > see such a big difference in ugliness...
No we're not. I telling you that your open_create is not a solution for the problems we have with open in NFSv4.
If it doesn't do atomic lookup+open, then I have an unfixable race. Any "solution" that requires NFS to assume that the dcache will remain consistent with the server namespace across more than one RPC operation is prone to races.
OTOH mount/umount races are fixable since they involve only the local namespace. Just add locking.
Trond
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