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    SubjectRe: [RFC v3 36/45] NFSv4: Fix GETATTR bitmap verification
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    On Thu, May 28, 2015 at 4:33 PM, J. Bruce Fields <bfields@fieldses.org> wrote:
    > On Fri, Apr 24, 2015 at 01:04:33PM +0200, Andreas Gruenbacher wrote:
    >> The NFSv4 client sends the server GETATTR requests with different sets of
    >> requested attributes depending on the situation. The requested set of
    >> attributes is encoded in a bitmap; the server replies with the set of
    >> attributes it could return. These bitmaps can be several words wide. The
    >> bitmap returned by the server is a subset of the bitmap sent by the client.
    >>
    >> While decoding the reply, the client tries to verify the reply bitmap: it
    >> checks if any previous, unexpected attributes are left in the same word of the
    >> bitmap for each attribute it tries to decode, then it clears the current
    >> attribute's bit in the bitmap for the next decode function.
    >>
    >> The client fails to detect when unexpected attributes are sent after the last
    >> expected attribute in each word in the bitmap.
    >
    > Is it important that the client catch that?

    Right. What is the actual problem or bug that this patch is trying to
    fix? Why do we care if a buggy server sends us extra info that we
    didn't ask for?

    Trond


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