• Christoph Hellwig's avatar
    nfsd: implement pNFS operations · 9cf514cc
    Christoph Hellwig authored
    Add support for the GETDEVICEINFO, LAYOUTGET, LAYOUTCOMMIT and
    LAYOUTRETURN NFSv4.1 operations, as well as backing code to manage
    outstanding layouts and devices.
    
    Layout management is very straight forward, with a nfs4_layout_stateid
    structure that extends nfs4_stid to manage layout stateids as the
    top-level structure.  It is linked into the nfs4_file and nfs4_client
    structures like the other stateids, and contains a linked list of
    layouts that hang of the stateid.  The actual layout operations are
    implemented in layout drivers that are not part of this commit, but
    will be added later.
    
    The worst part of this commit is the management of the pNFS device IDs,
    which suffers from a specification that is not sanely implementable due
    to the fact that the device-IDs are global and not bound to an export,
    and have a small enough size so that we can't store the fsid portion of
    a file handle, and must never be reused.  As we still do need perform all
    export authentication and validation checks on a device ID passed to
    GETDEVICEINFO we are caught between a rock and a hard place.  To work
    around this issue we add a new hash that maps from a 64-bit integer to a
    fsid so that we can look up the export to authenticate against it,
    a 32-bit integer as a generation that we can bump when changing the device,
    and a currently unused 32-bit integer that could be used in the future
    to handle more than a single device per export.  Entries in this hash
    table are never deleted as we can't reuse the ids anyway, and would have
    a severe lifetime problem anyway as Linux export structures are temporary
    structures that can go away under load.
    
    Parts of the XDR data, structures and marshaling/unmarshaling code, as
    well as many concepts are derived from the old pNFS server implementation
    from Andy Adamson, Benny Halevy, Dean Hildebrand, Marc Eshel, Fred Isaman,
    Mike Sager, Ricardo Labiaga and many others.
    Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
    9cf514cc
export.c 32.8 KB