From 21037b8c2258ec40de3b31be9ced43ceb3b784f7 Mon Sep 17 00:00:00 2001 From: Chuck Lever Date: Tue, 5 Oct 2021 10:17:59 -0400 Subject: xprtrdma: Provide a buffer to pad Write chunks of unaligned length This is a buffer to be left persistently registered while a connection is up. Connection tear-down will automatically DMA-unmap, invalidate, and dereg the MR. A persistently registered buffer is lower in cost to provide, and it can never be coalesced into the RDMA segment that carries the data payload. An RPC that provisions a Write chunk with a non-aligned length now uses this MR rather than the tail buffer of the RPC's rq_rcv_buf. Reviewed-By: Tom Talpey Signed-off-by: Chuck Lever Signed-off-by: Trond Myklebust --- net/sunrpc/xprtrdma/frwr_ops.c | 35 +++++++++++++++++++++++++++++++++++ 1 file changed, 35 insertions(+) (limited to 'net/sunrpc/xprtrdma/frwr_ops.c') diff --git a/net/sunrpc/xprtrdma/frwr_ops.c b/net/sunrpc/xprtrdma/frwr_ops.c index f700b34a5bfd..3eccf365fcb8 100644 --- a/net/sunrpc/xprtrdma/frwr_ops.c +++ b/net/sunrpc/xprtrdma/frwr_ops.c @@ -666,3 +666,38 @@ void frwr_unmap_async(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req) */ rpcrdma_force_disconnect(ep); } + +/** + * frwr_wp_create - Create an MR for padding Write chunks + * @r_xprt: transport resources to use + * + * Return 0 on success, negative errno on failure. + */ +int frwr_wp_create(struct rpcrdma_xprt *r_xprt) +{ + struct rpcrdma_ep *ep = r_xprt->rx_ep; + struct rpcrdma_mr_seg seg; + struct rpcrdma_mr *mr; + + mr = rpcrdma_mr_get(r_xprt); + if (!mr) + return -EAGAIN; + mr->mr_req = NULL; + ep->re_write_pad_mr = mr; + + seg.mr_len = XDR_UNIT; + seg.mr_page = virt_to_page(ep->re_write_pad); + seg.mr_offset = offset_in_page(ep->re_write_pad); + if (IS_ERR(frwr_map(r_xprt, &seg, 1, true, xdr_zero, mr))) + return -EIO; + trace_xprtrdma_mr_fastreg(mr); + + mr->mr_cqe.done = frwr_wc_fastreg; + mr->mr_regwr.wr.next = NULL; + mr->mr_regwr.wr.wr_cqe = &mr->mr_cqe; + mr->mr_regwr.wr.num_sge = 0; + mr->mr_regwr.wr.opcode = IB_WR_REG_MR; + mr->mr_regwr.wr.send_flags = 0; + + return ib_post_send(ep->re_id->qp, &mr->mr_regwr.wr, NULL); +} -- cgit v1.2.3