085def3ade
Currently our handling of 4.1+ requests without "cachethis" set is confusing and not quite correct. Suppose a client sends a compound consisting of only a single SEQUENCE op, and it matches the seqid in a session slot (so it's a retry), but the previous request with that seqid did not have "cachethis" set. The obvious thing to do might be to return NFS4ERR_RETRY_UNCACHED_REP, but the protocol only allows that to be returned on the op following the SEQUENCE, and there is no such op in this case. The protocol permits us to cache replies even if the client didn't ask us to. And it's easy to do so in the case of solo SEQUENCE compounds. So, when we get a solo SEQUENCE, we can either return the previously cached reply or NFSERR_SEQ_FALSE_RETRY if we notice it differs in some way from the original call. Currently, we're returning a corrupt reply in the case a solo SEQUENCE matches a previous compound with more ops. This actually matters because the Linux client recently started doing this as a way to recover from lost replies to idempotent operations in the case the process doing the original reply was killed: in that case it's difficult to keep the original arguments around to do a real retry, and the client no longer cares what the result is anyway, but it would like to make sure that the slot's sequence id has been incremented, and the solo SEQUENCE assures that: if the server never got the original reply, it will increment the sequence id. If it did get the original reply, it won't increment, and nothing else that about the reply really matters much. But we can at least attempt to return valid xdr! Tested-by: Olga Kornievskaia <aglo@umich.edu> Signed-off-by: J. Bruce Fields <bfields@redhat.com> |
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Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.