svcrdma: Simplify RDMA_READ deferral buffer management

An NFS_WRITE requires a set of RDMA_READ requests to fetch the write
data from the client. There are two principal pieces of data that
need to be tracked: the list of pages that comprise the completed RPC
and the SGE of dma mapped pages to refer to this list of pages. Previously
this whole bit was managed as a linked list of contexts with the
context containing the page list buried in this list. This patch
simplifies this processing by not keeping a linked list, but rather only
a pionter from the last submitted RDMA_READ's context to the context
that maps the set of pages that describe the RPC.  This significantly
simplifies this code path. SGE contexts are cleaned up inline in the DTO
path instead of at read completion time.

Signed-off-by: Tom Tucker <tom@opengridcomputing.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/linux/sunrpc/svc_rdma.h b/include/linux/sunrpc/svc_rdma.h
index d0011f3db90c..c447c417b37b 100644
--- a/include/linux/sunrpc/svc_rdma.h
+++ b/include/linux/sunrpc/svc_rdma.h
@@ -71,6 +71,7 @@ extern atomic_t rdma_stat_sq_prod;
  * completes.
  */
 struct svc_rdma_op_ctxt {
+	struct svc_rdma_op_ctxt *read_hdr;
 	struct svc_rdma_op_ctxt *next;
 	struct xdr_buf arg;
 	struct list_head dto_q;