• Ricardo Labiaga's avatar
    nfs41: Add backchannel processing support to RPC state machine · 55ae1aab
    Ricardo Labiaga authored
    Adds rpc_run_bc_task() which is called by the NFS callback service to
    process backchannel requests.  It performs similar work to rpc_run_task()
    though "schedules" the backchannel task to be executed starting at the
    call_trasmit state in the RPC state machine.
    
    It also introduces some miscellaneous updates to the argument validation,
    call_transmit, and transport cleanup functions to take into account
    that there are now forechannel and backchannel tasks.
    
    Backchannel requests do not carry an RPC message structure, since the
    payload has already been XDR encoded using the existing NFSv4 callback
    mechanism.
    
    Introduce a new transmit state for the client to reply on to backchannel
    requests.  This new state simply reserves the transport and issues the
    reply.  In case of a connection related error, disconnects the transport and
    drops the reply.  It requires the forechannel to re-establish the connection
    and the server to retransmit the request, as stated in NFSv4.1 section
    2.9.2 "Client and Server Transport Behavior".
    
    Note: There is no need to loop attempting to reserve the transport.  If EAGAIN
    is returned by xprt_prepare_transmit(), return with tk_status == 0,
    setting tk_action to call_bc_transmit.  rpc_execute() will invoke it again
    after the task is taken off the sleep queue.
    
    [nfs41: rpc_run_bc_task() need not be exported outside RPC module]
    [nfs41: New call_bc_transmit RPC state]
    Signed-off-by: default avatarRicardo Labiaga <Ricardo.Labiaga@netapp.com>
    Signed-off-by: default avatarBenny Halevy <bhalevy@panasas.com>
    [nfs41: Backchannel: No need to loop in call_bc_transmit()]
    Signed-off-by: default avatarAndy Adamson <andros@netapp.com>
    Signed-off-by: default avatarRicardo Labiaga <Ricardo.Labiaga@netapp.com>
    Signed-off-by: default avatarBenny Halevy <bhalevy@panasas.com>
    [rpc_count_iostats incorrectly exits early]
    Signed-off-by: default avatarRicardo Labiaga <Ricardo.Labiaga@netapp.com>
    Signed-off-by: default avatarBenny Halevy <bhalevy@panasas.com>
    [Convert rpc_reply_expected() to inline function]
    [Remove unnecessary BUG_ON()]
    [Rename variable]
    Signed-off-by: default avatarRicardo Labiaga <Ricardo.Labiaga@netapp.com>
    Signed-off-by: default avatarBenny Halevy <bhalevy@panasas.com>
    55ae1aab
sunrpc.h 1.37 KB