Messages in this thread | | | Date | Thu, 5 Aug 1999 16:36:11 +0200 | From | Jamie Lokier <> | Subject | Re: 2.3 SMP overlapping writes and NFS |
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Alexander Viro wrote: > > NFSv2's requirements are stricter -- so I guess knfsd has to handle this > > by locking the inode during an NFSv2 write. Is this done and does > > anyone care? > > It isn't done and any locking works only if everybody use it. > Probably using rwlock-style semantics (modulo sleeping, indeed - you don't > want spinlocks here) would be the right thing. Then we have write() as > reader, knfsd write() as writer and quite probably truncate() as writer > too.
(a) the NFSv2 spec only talks about other clients -- it doesn't say anything about concurrent writes that _aren't_ from NFSv2 clients. So maybe ordinary write() calls don't need to lock anything at all.
(b) NFSv3 doesn't have this as a requirement AFAICT. So I should think there are no NFS apps depending on this behaviour.
(c) If atomic writes can be done by knfsd, I think there should be a mechanism to do them from user space too -- not every file server lives in the kernel, not even every NFS server.
-- Jamie
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