The svcrdma transport provider currently allocates receive buffers
to the RQ through the xpo_release_rqst method. This approach is overly
complicated since it means that the rqstp rq_xprt_ctxt has to be
selectively set based on whether the RPC is going to be processed
immediately or deferred. Instead, just post the receive buffer when
we are certain that we are replying in the send_reply function.
Signed-off-by: NTom Tucker <tom@opengridcomputing.com>

The assertion that checks for sge context overflow is
incorrectly hard-coded to 32. This causes a kernel bug
check when using big-data mounts. Changed the BUG_ON to
use the computed value RPCSVC_MAXPAGES.
Signed-off-by: NTom Tucker <tom@opengridcomputing.com>
Signed-off-by: NJ. Bruce Fields <bfields@citi.umich.edu>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

net/sunrpc/xprtrdma/svc_rdma_sendto.c:160: warning: format '%llx'
expects type 'long long unsigned int', but argument 3 has type 'u64'
Signed-off-by: NRoland Dreier <rolandd@cisco.com>
Signed-off-by: NJ. Bruce Fields <bfields@citi.umich.edu>

This file implements the RDMA transport sendto function. A RPC reply
on an RDMA transport consists of some number of RDMA_WRITE requests
followed by an RDMA_SEND request. The sendto function parses the
ONCRPC RDMA reply header to determine how to send the reply back to
the client. The send queue is sized so as to be able to send complete
replies for requests in most cases.  In the event that there are not
enough SQ WR slots to reply, e.g.  big data, the send will block the
NFSD thread. The I/O callback functions in svc_rdma_transport.c that
reap WR completions wake any waiters blocked on the SQ. In general,
the goal is not to block NFSD threads and the has_wspace method
stall requests when the SQ is nearly full.
Signed-off-by: NTom Tucker <tom@opengridcomputing.com>
Acked-by: NNeil Brown <neilb@suse.de>
Signed-off-by: NJ. Bruce Fields <bfields@citi.umich.edu>