IB/iser: Do not use FMR for a single dma entry sg

Fast Memory Registration (fmr) is used to register for rdma an sg whose
elements are not linearly sequential after dma mapping.

The IB verbs layer provides an "all dma memory MR (memory region)" which
can be used for RDMA-ing a dma linearly sequential buffer.

Change the code to use the dma mr instead of doing fmr when dma mapping
produces a single dma entry sg.

Signed-off-by: Erez Zilber <erezz@voltaire.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

diff --git a/drivers/infiniband/ulp/iser/iscsi_iser.h b/drivers/infiniband/ulp/iser/iscsi_iser.h
index 0ba02abb041400eb7081254576ba968910a0bb29..7e1a411db2a30d215369d7e005e5c6a458ada015 100644 (file)
--- a/drivers/infiniband/ulp/iser/iscsi_iser.h
+++ b/drivers/infiniband/ulp/iser/iscsi_iser.h
@@ -175,6 +175,7 @@ struct iser_mem_reg {
        u64  va;
        u64  len;
        void *mem_h;
+       int  is_fmr;
 };
 
 struct iser_regd_buf {

diff --git a/drivers/infiniband/ulp/iser/iser_memory.c b/drivers/infiniband/ulp/iser/iser_memory.c
index 8fea0bce5042c42379b022819163539ac31c67d0..d0b03f4265811c04f70d5d2a33acdaa9dacf8a56 100644 (file)
--- a/drivers/infiniband/ulp/iser/iser_memory.c
+++ b/drivers/infiniband/ulp/iser/iser_memory.c
@@ -56,7 +56,7 @@ int iser_regd_buff_release(struct iser_regd_buf *regd_buf)
        if ((atomic_read(&regd_buf->ref_count) == 0) ||
            atomic_dec_and_test(&regd_buf->ref_count)) {
                /* if we used the dma mr, unreg is just NOP */
-               if (regd_buf->reg.rkey != 0)
+               if (regd_buf->reg.is_fmr)
                        iser_unreg_mem(&regd_buf->reg);
 
                if (regd_buf->dma_addr) {
@@ -91,9 +91,9 @@ void iser_reg_single(struct iser_device *device,
        BUG_ON(dma_mapping_error(dma_addr));
 
        regd_buf->reg.lkey = device->mr->lkey;
-       regd_buf->reg.rkey = 0; /* indicate there's no need to unreg */
        regd_buf->reg.len  = regd_buf->data_size;
        regd_buf->reg.va   = dma_addr;
+       regd_buf->reg.is_fmr = 0;
 
        regd_buf->dma_addr  = dma_addr;
        regd_buf->direction = direction;
@@ -379,11 +379,13 @@ int iser_reg_rdma_mem(struct iscsi_iser_cmd_task *iser_ctask,
                      enum   iser_data_dir        cmd_dir)
 {
        struct iser_conn     *ib_conn = iser_ctask->iser_conn->ib_conn;
+       struct iser_device   *device = ib_conn->device;
        struct iser_data_buf *mem = &iser_ctask->data[cmd_dir];
        struct iser_regd_buf *regd_buf;
        int aligned_len;
        int err;
        int i;
+       struct scatterlist *sg;
 
        regd_buf = &iser_ctask->rdma_regd[cmd_dir];
 
@@ -399,19 +401,37 @@ int iser_reg_rdma_mem(struct iscsi_iser_cmd_task *iser_ctask,
                mem = &iser_ctask->data_copy[cmd_dir];
        }
 
-       iser_page_vec_build(mem, ib_conn->page_vec);
-       err = iser_reg_page_vec(ib_conn, ib_conn->page_vec, &regd_buf->reg);
-       if (err) {
-               iser_data_buf_dump(mem);
-               iser_err("mem->dma_nents = %d (dlength = 0x%x)\n", mem->dma_nents,
-                        ntoh24(iser_ctask->desc.iscsi_header.dlength));
-               iser_err("page_vec: data_size = 0x%x, length = %d, offset = 0x%x\n",
-                        ib_conn->page_vec->data_size, ib_conn->page_vec->length,
-                        ib_conn->page_vec->offset);
-               for (i=0 ; i<ib_conn->page_vec->length ; i++) {
-                       iser_err("page_vec[%d] = 0x%lx\n", i, ib_conn->page_vec->pages[i]);
+       /* if there a single dma entry, FMR is not needed */
+       if (mem->dma_nents == 1) {
+               sg = (struct scatterlist *)mem->buf;
+
+               regd_buf->reg.lkey = device->mr->lkey;
+               regd_buf->reg.rkey = device->mr->rkey;
+               regd_buf->reg.len  = sg_dma_len(&sg[0]);
+               regd_buf->reg.va   = sg_dma_address(&sg[0]);
+               regd_buf->reg.is_fmr = 0;
+
+               iser_dbg("PHYSICAL Mem.register: lkey: 0x%08X rkey: 0x%08X  "
+                        "va: 0x%08lX sz: %ld]\n",
+                        (unsigned int)regd_buf->reg.lkey,
+                        (unsigned int)regd_buf->reg.rkey,
+                        (unsigned long)regd_buf->reg.va,
+                        (unsigned long)regd_buf->reg.len);
+       } else { /* use FMR for multiple dma entries */
+               iser_page_vec_build(mem, ib_conn->page_vec);
+               err = iser_reg_page_vec(ib_conn, ib_conn->page_vec, &regd_buf->reg);
+               if (err) {
+                       iser_data_buf_dump(mem);
+                       iser_err("mem->dma_nents = %d (dlength = 0x%x)\n", mem->dma_nents,
+                                ntoh24(iser_ctask->desc.iscsi_header.dlength));
+                       iser_err("page_vec: data_size = 0x%x, length = %d, offset = 0x%x\n",
+                                ib_conn->page_vec->data_size, ib_conn->page_vec->length,
+                                ib_conn->page_vec->offset);
+                       for (i=0 ; i<ib_conn->page_vec->length ; i++)
+                               iser_err("page_vec[%d] = 0x%llx\n", i,
+                                        (unsigned long long) ib_conn->page_vec->pages[i]);
+                       return err;
                }
-               return err;
        }
 
        /* take a reference on this regd buf such that it will not be released *

diff --git a/drivers/infiniband/ulp/iser/iser_verbs.c b/drivers/infiniband/ulp/iser/iser_verbs.c
index 9b27a7c26aa876dbe5c271aaa0ace2ef3d92557b..ecdca7fc1e4cf0466f58bd6d89b4153891b71e0b 100644 (file)
--- a/drivers/infiniband/ulp/iser/iser_verbs.c
+++ b/drivers/infiniband/ulp/iser/iser_verbs.c
@@ -88,8 +88,9 @@ static int iser_create_device_ib_res(struct iser_device *device)
                     iser_cq_tasklet_fn,
                     (unsigned long)device);
 
-       device->mr = ib_get_dma_mr(device->pd,
-                                  IB_ACCESS_LOCAL_WRITE);
+       device->mr = ib_get_dma_mr(device->pd, IB_ACCESS_LOCAL_WRITE |
+                                  IB_ACCESS_REMOTE_WRITE |
+                                  IB_ACCESS_REMOTE_READ);
        if (IS_ERR(device->mr))
                goto dma_mr_err;
 
@@ -606,6 +607,7 @@ int iser_reg_page_vec(struct iser_conn     *ib_conn,
        mem_reg->rkey  = mem->fmr->rkey;
        mem_reg->len   = page_vec->length * SIZE_4K;
        mem_reg->va    = io_addr;
+       mem_reg->is_fmr = 1;
        mem_reg->mem_h = (void *)mem;
 
        mem_reg->va   += page_vec->offset;