svcrdma: Add FRMR get/put services

Add services for the allocating, freeing, and unmapping Fast Reg MR. These
services will be used by the transport connection setup, send and receive
routines.

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

2 files changed, 114 insertions, 5 deletions

diff --git a/include/linux/sunrpc/svc_rdma.h b/include/linux/sunrpc/svc_rdma.h
index 49e458d9894..34252683671 100644
--- a/include/linux/sunrpc/svc_rdma.h
+++ b/include/linux/sunrpc/svc_rdma.h
@@ -214,6 +214,9 @@ extern struct svc_rdma_op_ctxt *svc_rdma_get_context(struct svcxprt_rdma *);
 extern void svc_rdma_put_context(struct svc_rdma_op_ctxt *, int);
 extern struct svc_rdma_req_map *svc_rdma_get_req_map(void);
 extern void svc_rdma_put_req_map(struct svc_rdma_req_map *);
+extern struct svc_rdma_fastreg_mr *svc_rdma_get_frmr(struct svcxprt_rdma *);
+extern void svc_rdma_put_frmr(struct svcxprt_rdma *,
+                              struct svc_rdma_fastreg_mr *);
 extern void svc_sq_reap(struct svcxprt_rdma *);
 extern void svc_rq_reap(struct svcxprt_rdma *);
 extern struct svc_xprt_class svc_rdma_class;
diff --git a/net/sunrpc/xprtrdma/svc_rdma_transport.c b/net/sunrpc/xprtrdma/svc_rdma_transport.c
index 900cb69728c..f0b5c5f2f62 100644
--- a/net/sunrpc/xprtrdma/svc_rdma_transport.c
+++ b/net/sunrpc/xprtrdma/svc_rdma_transport.c
@@ -100,6 +100,7 @@ struct svc_rdma_op_ctxt *svc_rdma_get_context(struct svcxprt_rdma *xprt)
         ctxt->xprt = xprt;
         INIT_LIST_HEAD(&ctxt->dto_q);
         ctxt->count = 0;
+        ctxt->frmr = NULL;
         atomic_inc(&xprt->sc_ctxt_used);
         return ctxt;
 }
@@ -109,11 +110,19 @@ static void svc_rdma_unmap_dma(struct svc_rdma_op_ctxt *ctxt)
         struct svcxprt_rdma *xprt = ctxt->xprt;
         int i;
         for (i = 0; i < ctxt->count && ctxt->sge[i].length; i++) {
-                atomic_dec(&xprt->sc_dma_used);
-                ib_dma_unmap_single(xprt->sc_cm_id->device,
-                                    ctxt->sge[i].addr,
-                                    ctxt->sge[i].length,
-                                    ctxt->direction);
+                /*
+                 * Unmap the DMA addr in the SGE if the lkey matches
+                 * the sc_dma_lkey, otherwise, ignore it since it is
+                 * an FRMR lkey and will be unmapped later when the
+                 * last WR that uses it completes.
+                 */
+                if (ctxt->sge[i].lkey == xprt->sc_dma_lkey) {
+                        atomic_dec(&xprt->sc_dma_used);
+                        ib_dma_unmap_single(xprt->sc_cm_id->device,
+                                            ctxt->sge[i].addr,
+                                            ctxt->sge[i].length,
+                                            ctxt->direction);
+                }
         }
 }
 
@@ -150,6 +159,7 @@ struct svc_rdma_req_map *svc_rdma_get_req_map(void)
                 schedule_timeout_uninterruptible(msecs_to_jiffies(500));
         }
         map->count = 0;
+        map->frmr = NULL;
         return map;
 }
 
@@ -425,10 +435,12 @@ static struct svcxprt_rdma *rdma_create_xprt(struct svc_serv *serv,
         INIT_LIST_HEAD(&cma_xprt->sc_dto_q);
         INIT_LIST_HEAD(&cma_xprt->sc_rq_dto_q);
         INIT_LIST_HEAD(&cma_xprt->sc_read_complete_q);
+        INIT_LIST_HEAD(&cma_xprt->sc_frmr_q);
         init_waitqueue_head(&cma_xprt->sc_send_wait);
 
         spin_lock_init(&cma_xprt->sc_lock);
         spin_lock_init(&cma_xprt->sc_rq_dto_lock);
+        spin_lock_init(&cma_xprt->sc_frmr_q_lock);
 
         cma_xprt->sc_ord = svcrdma_ord;
 
@@ -686,6 +698,97 @@ static struct svc_xprt *svc_rdma_create(struct svc_serv *serv,
         return ERR_PTR(ret);
 }
 
+static struct svc_rdma_fastreg_mr *rdma_alloc_frmr(struct svcxprt_rdma *xprt)
+{
+        struct ib_mr *mr;
+        struct ib_fast_reg_page_list *pl;
+        struct svc_rdma_fastreg_mr *frmr;
+
+        frmr = kmalloc(sizeof(*frmr), GFP_KERNEL);
+        if (!frmr)
+                goto err;
+
+        mr = ib_alloc_fast_reg_mr(xprt->sc_pd, RPCSVC_MAXPAGES);
+        if (!mr)
+                goto err_free_frmr;
+
+        pl = ib_alloc_fast_reg_page_list(xprt->sc_cm_id->device,
+                                         RPCSVC_MAXPAGES);
+        if (!pl)
+                goto err_free_mr;
+
+        frmr->mr = mr;
+        frmr->page_list = pl;
+        INIT_LIST_HEAD(&frmr->frmr_list);
+        return frmr;
+
+ err_free_mr:
+        ib_dereg_mr(mr);
+ err_free_frmr:
+        kfree(frmr);
+ err:
+        return ERR_PTR(-ENOMEM);
+}
+
+static void rdma_dealloc_frmr_q(struct svcxprt_rdma *xprt)
+{
+        struct svc_rdma_fastreg_mr *frmr;
+
+        while (!list_empty(&xprt->sc_frmr_q)) {
+                frmr = list_entry(xprt->sc_frmr_q.next,
+                                  struct svc_rdma_fastreg_mr, frmr_list);
+                list_del_init(&frmr->frmr_list);
+                ib_dereg_mr(frmr->mr);
+                ib_free_fast_reg_page_list(frmr->page_list);
+                kfree(frmr);
+        }
+}
+
+struct svc_rdma_fastreg_mr *svc_rdma_get_frmr(struct svcxprt_rdma *rdma)
+{
+        struct svc_rdma_fastreg_mr *frmr = NULL;
+
+        spin_lock_bh(&rdma->sc_frmr_q_lock);
+        if (!list_empty(&rdma->sc_frmr_q)) {
+                frmr = list_entry(rdma->sc_frmr_q.next,
+                                  struct svc_rdma_fastreg_mr, frmr_list);
+                list_del_init(&frmr->frmr_list);
+                frmr->map_len = 0;
+                frmr->page_list_len = 0;
+        }
+        spin_unlock_bh(&rdma->sc_frmr_q_lock);
+        if (frmr)
+                return frmr;
+
+        return rdma_alloc_frmr(rdma);
+}
+
+static void frmr_unmap_dma(struct svcxprt_rdma *xprt,
+                           struct svc_rdma_fastreg_mr *frmr)
+{
+        int page_no;
+        for (page_no = 0; page_no < frmr->page_list_len; page_no++) {
+                dma_addr_t addr = frmr->page_list->page_list[page_no];
+                if (ib_dma_mapping_error(frmr->mr->device, addr))
+                        continue;
+                atomic_dec(&xprt->sc_dma_used);
+                ib_dma_unmap_single(frmr->mr->device, addr, PAGE_SIZE,
+                                    frmr->direction);
+        }
+}
+
+void svc_rdma_put_frmr(struct svcxprt_rdma *rdma,
+                       struct svc_rdma_fastreg_mr *frmr)
+{
+        if (frmr) {
+                frmr_unmap_dma(rdma, frmr);
+                spin_lock_bh(&rdma->sc_frmr_q_lock);
+                BUG_ON(!list_empty(&frmr->frmr_list));
+                list_add(&frmr->frmr_list, &rdma->sc_frmr_q);
+                spin_unlock_bh(&rdma->sc_frmr_q_lock);
+        }
+}
+
 /*
  * This is the xpo_recvfrom function for listening endpoints. Its
  * purpose is to accept incoming connections. The CMA callback handler
@@ -961,6 +1064,9 @@ static void __svc_rdma_free(struct work_struct *work)
         WARN_ON(atomic_read(&rdma->sc_ctxt_used) != 0);
         WARN_ON(atomic_read(&rdma->sc_dma_used) != 0);
 
+        /* De-allocate fastreg mr */
+        rdma_dealloc_frmr_q(rdma);
+
         /* Destroy the QP if present (not a listener) */
         if (rdma->sc_qp && !IS_ERR(rdma->sc_qp))
                 ib_destroy_qp(rdma->sc_qp);