On Mon, 17 Sep 2012 12:51:33 +0000 "Myklebust, Trond" <Trond.Myklebust@xxxxxxxxxx> wrote: > > -----Original Message----- > > From: linux-nfs-owner@xxxxxxxxxxxxxxx [mailto:linux-nfs- > > owner@xxxxxxxxxxxxxxx] On Behalf Of NeilBrown > > Sent: Sunday, September 16, 2012 7:06 PM > > To: linux-nfs@xxxxxxxxxxxxxxx > > Subject: What is NFSv4 READDIR doesn't return a filehandle.... > > > > > > In NFSv4, the server can report which attributes it chose to return in a > > READDIR reply. > > > > A customer has come across a server which does not return the filehandle > > information (is that allowed?). > > The filehandle attribute is a mandatory attribute according to RFC3530, so I believe that the answer is "no". > > > A consequence of this is that Linux/NFS gets confused. > > nfs_readdir_page_filler calls nfs_prime_dcache() (because it was a readdir > > plus request that was sent) and nfs_prime_dcache goes ahead and creates > > an inode based on the filehandle that it has. > > However decode_attr_filehandle() had happily decoded nothing as the > > FATTR4_WORD0_FILEHANDLE bit wasn't set. > > So the inode gets created with a zero-length filehandle and when this gets > > sent back to the server to act on the inode, it gets NFS4ERR_BADHANDLE to > > the PUTFH op. > > > > So should nfs_prime_dcache() abort if the filehandle doesn't exist (patch > > below) or should nfs_fhget() return an error if the filehandle is empty? > > > > Or maybe this behaviour should be detected and readdir should be disabled > > for that server? > > > > I don't want to have to code the client to deal with broken servers. If we start down that path, then we'll end up doing nothing else. > > I can, however, see a case for extending the "nordirplus" mount option to cover NFSv4. Currently it only acts on NFSv3 mounts... > > Thanks Trond. I'm happy with this position - less work for me :-) As it happens, nordirplus *does* work for NFSv4 and customer had already found that this is a successful work around. They didn't want to have to use it though. I've pointed out that is really isn't our problem. Just a thought: while coping with broken servers would not be a good path to follow, detecting protocol violations and reporting an error might be... should the NFS client treat a missing filehandle and a malformed reply? Thanks, NeilBrown
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