SUNRPC: Revert 579900670ac7 ("svcrdma: Remove unused sc_pages field")

Pre-requisite for releasing pages in the send completion handler.
Reverted by hand: patch -R would not apply cleanly.

Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

diff --git a/include/linux/sunrpc/svc_rdma.h b/include/linux/sunrpc/svc_rdma.h
index a0f3ea3..8e654da 100644 (file)
--- a/include/linux/sunrpc/svc_rdma.h
+++ b/include/linux/sunrpc/svc_rdma.h
@@ -158,8 +158,9 @@ struct svc_rdma_send_ctxt {
        struct xdr_buf          sc_hdrbuf;
        struct xdr_stream       sc_stream;
        void                    *sc_xprt_buf;
+       int                     sc_page_count;
        int                     sc_cur_sge_no;
-
+       struct page             *sc_pages[RPCSVC_MAXPAGES];
        struct ib_sge           sc_sges[];
 };
 

diff --git a/net/sunrpc/xprtrdma/svc_rdma_sendto.c b/net/sunrpc/xprtrdma/svc_rdma_sendto.c
index 8e7ccef..4c62bc4 100644 (file)
--- a/net/sunrpc/xprtrdma/svc_rdma_sendto.c
+++ b/net/sunrpc/xprtrdma/svc_rdma_sendto.c
@@ -213,6 +213,7 @@ out:
 
        ctxt->sc_send_wr.num_sge = 0;
        ctxt->sc_cur_sge_no = 0;
+       ctxt->sc_page_count = 0;
        return ctxt;
 
 out_empty:
@@ -227,6 +228,8 @@ out_empty:
  * svc_rdma_send_ctxt_put - Return send_ctxt to free list
  * @rdma: controlling svcxprt_rdma
  * @ctxt: object to return to the free list
+ *
+ * Pages left in sc_pages are DMA unmapped and released.
  */
 void svc_rdma_send_ctxt_put(struct svcxprt_rdma *rdma,
                            struct svc_rdma_send_ctxt *ctxt)
@@ -234,6 +237,9 @@ void svc_rdma_send_ctxt_put(struct svcxprt_rdma *rdma,
        struct ib_device *device = rdma->sc_cm_id->device;
        unsigned int i;
 
+       for (i = 0; i < ctxt->sc_page_count; ++i)
+               put_page(ctxt->sc_pages[i]);
+
        /* The first SGE contains the transport header, which
         * remains mapped until @ctxt is destroyed.
         */
@@ -798,6 +804,25 @@ int svc_rdma_map_reply_msg(struct svcxprt_rdma *rdma,
                                       svc_rdma_xb_dma_map, &args);
 }
 
+/* The svc_rqst and all resources it owns are released as soon as
+ * svc_rdma_sendto returns. Transfer pages under I/O to the ctxt
+ * so they are released by the Send completion handler.
+ */
+static inline void svc_rdma_save_io_pages(struct svc_rqst *rqstp,
+                                         struct svc_rdma_send_ctxt *ctxt)
+{
+       int i, pages = rqstp->rq_next_page - rqstp->rq_respages;
+
+       ctxt->sc_page_count += pages;
+       for (i = 0; i < pages; i++) {
+               ctxt->sc_pages[i] = rqstp->rq_respages[i];
+               rqstp->rq_respages[i] = NULL;
+       }
+
+       /* Prevent svc_xprt_release from releasing pages in rq_pages */
+       rqstp->rq_next_page = rqstp->rq_respages;
+}
+
 /* Prepare the portion of the RPC Reply that will be transmitted
  * via RDMA Send. The RPC-over-RDMA transport header is prepared
  * in sc_sges[0], and the RPC xdr_buf is prepared in following sges.