[RFC PATCH 22/28] nvmet: Use DMA addresses instead of struct pages for P2P

Logan Gunthorpe
2019-06-20T16:12:34Z

Start using the dma-direct bios and DMA address RDMA CTX API.

This removes struct pages from all P2P transactions.

Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
---
drivers/nvme/target/core.c | 12 +++++----
drivers/nvme/target/io-cmd-bdev.c | 32 ++++++++++++++++++++---
drivers/nvme/target/nvmet.h | 5 +++-
drivers/nvme/target/rdma.c | 43 +++++++++++++++++++++++--------
4 files changed, 71 insertions(+), 21 deletions(-)

diff --git a/drivers/nvme/target/core.c b/drivers/nvme/target/core.c
index 7734a6acff85..230e99b63320 100644
--- a/drivers/nvme/target/core.c
+++ b/drivers/nvme/target/core.c
@@ -420,7 +420,7 @@ static int nvmet_p2pmem_ns_enable(struct nvmet_ns *ns)
return -EINVAL;
}

- if (!blk_queue_pci_p2pdma(ns->bdev->bd_queue)) {
+ if (!blk_queue_dma_direct(ns->bdev->bd_queue)) {
pr_err("peer-to-peer DMA is not supported by the driver of %s\n",
ns->device_path);
return -EINVAL;
@@ -926,9 +926,9 @@ int nvmet_req_alloc_sgl(struct nvmet_req *req)

req->p2p_dev = NULL;
if (req->sq->qid && p2p_dev) {
- req->sg = pci_p2pmem_alloc_sgl(p2p_dev, &req->sg_cnt,
- req->transfer_len);
- if (req->sg) {
+ req->p2p_dma_buf = pci_alloc_p2pmem(p2p_dev,
+ req->transfer_len);
+ if (req->p2p_dma_buf) {
req->p2p_dev = p2p_dev;
return 0;
}
@@ -951,10 +951,12 @@ EXPORT_SYMBOL_GPL(nvmet_req_alloc_sgl);
void nvmet_req_free_sgl(struct nvmet_req *req)
{
if (req->p2p_dev)
- pci_p2pmem_free_sgl(req->p2p_dev, req->sg);
+ pci_free_p2pmem(req->p2p_dev, req->p2p_dma_buf,
+ req->transfer_len);
else
sgl_free(req->sg);

+ req->p2p_dev = NULL;
req->sg = NULL;
req->sg_cnt = 0;
}
diff --git a/drivers/nvme/target/io-cmd-bdev.c b/drivers/nvme/target/io-cmd-bdev.c
index 061d40b020c7..f5621aeb1d6c 100644
--- a/drivers/nvme/target/io-cmd-bdev.c
+++ b/drivers/nvme/target/io-cmd-bdev.c
@@ -6,6 +6,7 @@
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/blkdev.h>
#include <linux/module.h>
+#include <linux/pci-p2pdma.h>
#include "nvmet.h"

int nvmet_bdev_ns_enable(struct nvmet_ns *ns)
@@ -132,6 +133,24 @@ static void nvmet_submit_sg(struct nvmet_req *req, struct bio *bio,
submit_bio(bio);
}

+static void nvmet_submit_p2p(struct nvmet_req *req, struct bio *bio)
+{
+ dma_addr_t addr;
+ int ret;
+
+ addr = pci_p2pmem_virt_to_bus(req->p2p_dev, req->p2p_dma_buf);
+
+ ret = bio_add_dma_addr(req->ns->bdev->bd_queue, bio,
+ addr, req->transfer_len);
+ if (WARN_ON_ONCE(ret != req->transfer_len)) {
+ bio->bi_status = BLK_STS_NOTSUPP;
+ nvmet_bio_done(bio);
+ return;
+ }
+
+ submit_bio(bio);
+}
+
static void nvmet_bdev_execute_rw(struct nvmet_req *req)
{
int sg_cnt = req->sg_cnt;
@@ -139,7 +158,7 @@ static void nvmet_bdev_execute_rw(struct nvmet_req *req)
sector_t sector;
int op, op_flags = 0;

- if (!req->sg_cnt) {
+ if (!req->sg_cnt && !req->p2p_dev) {
nvmet_req_complete(req, 0);
return;
}
@@ -153,8 +172,10 @@ static void nvmet_bdev_execute_rw(struct nvmet_req *req)
op = REQ_OP_READ;
}

- if (is_pci_p2pdma_page(sg_page(req->sg)))
- op_flags |= REQ_NOMERGE;
+ if (req->p2p_dev) {
+ op_flags |= REQ_DMA_DIRECT;
+ sg_cnt = 1;
+ }

sector = le64_to_cpu(req->cmd->rw.slba);
sector <<= (req->ns->blksize_shift - 9);
@@ -171,7 +192,10 @@ static void nvmet_bdev_execute_rw(struct nvmet_req *req)
bio->bi_end_io = nvmet_bio_done;
bio_set_op_attrs(bio, op, op_flags);

- nvmet_submit_sg(req, bio, sector);
+ if (req->p2p_dev)
+ nvmet_submit_p2p(req, bio);
+ else
+ nvmet_submit_sg(req, bio, sector);
}

static void nvmet_bdev_execute_flush(struct nvmet_req *req)
diff --git a/drivers/nvme/target/nvmet.h b/drivers/nvme/target/nvmet.h
index c25d88fc9dec..5714e5b5ef04 100644
--- a/drivers/nvme/target/nvmet.h
+++ b/drivers/nvme/target/nvmet.h
@@ -288,7 +288,10 @@ struct nvmet_req {
struct nvmet_sq *sq;
struct nvmet_cq *cq;
struct nvmet_ns *ns;
- struct scatterlist *sg;
+ union {
+ struct scatterlist *sg;
+ void *p2p_dma_buf;
+ };
struct bio_vec inline_bvec[NVMET_MAX_INLINE_BIOVEC];
union {
struct {
diff --git a/drivers/nvme/target/rdma.c b/drivers/nvme/target/rdma.c
index 36d906a7f70d..92bfc7207814 100644
--- a/drivers/nvme/target/rdma.c
+++ b/drivers/nvme/target/rdma.c
@@ -15,6 +15,7 @@
#include <linux/string.h>
#include <linux/wait.h>
#include <linux/inet.h>
+#include <linux/pci-p2pdma.h>
#include <asm/unaligned.h>

#include <rdma/ib_verbs.h>
@@ -495,6 +496,18 @@ static void nvmet_rdma_process_wr_wait_list(struct nvmet_rdma_queue *queue)
spin_unlock(&queue->rsp_wr_wait_lock);
}

+static void nvmet_rdma_ctx_destroy(struct nvmet_rdma_rsp *rsp)
+{
+ struct nvmet_rdma_queue *queue = rsp->queue;
+
+ if (rsp->req.p2p_dev)
+ rdma_rw_ctx_dma_destroy(&rsp->rw, queue->cm_id->qp,
+ queue->cm_id->port_num);
+ else
+ rdma_rw_ctx_destroy(&rsp->rw, queue->cm_id->qp,
+ queue->cm_id->port_num, rsp->req.sg,
+ rsp->req.sg_cnt, nvmet_data_dir(&rsp->req));
+}

static void nvmet_rdma_release_rsp(struct nvmet_rdma_rsp *rsp)
{
@@ -502,11 +515,8 @@ static void nvmet_rdma_release_rsp(struct nvmet_rdma_rsp *rsp)

atomic_add(1 + rsp->n_rdma, &queue->sq_wr_avail);

- if (rsp->n_rdma) {
- rdma_rw_ctx_destroy(&rsp->rw, queue->cm_id->qp,
- queue->cm_id->port_num, rsp->req.sg,
- rsp->req.sg_cnt, nvmet_data_dir(&rsp->req));
- }
+ if (rsp->n_rdma)
+ nvmet_rdma_ctx_destroy(rsp);

if (rsp->req.sg != rsp->cmd->inline_sg)
nvmet_req_free_sgl(&rsp->req);
@@ -587,9 +597,9 @@ static void nvmet_rdma_read_data_done(struct ib_cq *cq, struct ib_wc *wc)

WARN_ON(rsp->n_rdma <= 0);
atomic_add(rsp->n_rdma, &queue->sq_wr_avail);
- rdma_rw_ctx_destroy(&rsp->rw, queue->cm_id->qp,
- queue->cm_id->port_num, rsp->req.sg,
- rsp->req.sg_cnt, nvmet_data_dir(&rsp->req));
+
+ nvmet_rdma_ctx_destroy(rsp);
+
rsp->n_rdma = 0;

if (unlikely(wc->status != IB_WC_SUCCESS)) {
@@ -663,6 +673,7 @@ static u16 nvmet_rdma_map_sgl_keyed(struct nvmet_rdma_rsp *rsp,
struct rdma_cm_id *cm_id = rsp->queue->cm_id;
u64 addr = le64_to_cpu(sgl->addr);
u32 key = get_unaligned_le32(sgl->key);
+ dma_addr_t dma_addr;
int ret;

rsp->req.transfer_len = get_unaligned_le24(sgl->length);
@@ -675,9 +686,19 @@ static u16 nvmet_rdma_map_sgl_keyed(struct nvmet_rdma_rsp *rsp,
if (ret < 0)
goto error_out;

- ret = rdma_rw_ctx_init(&rsp->rw, cm_id->qp, cm_id->port_num,
- rsp->req.sg, rsp->req.sg_cnt, 0, addr, key,
- nvmet_data_dir(&rsp->req));
+ if (rsp->req.p2p_dev) {
+ dma_addr = pci_p2pmem_virt_to_bus(rsp->req.p2p_dev,
+ rsp->req.p2p_dma_buf);
+
+ ret = rdma_rw_ctx_dma_init(&rsp->rw, cm_id->qp,
+ cm_id->port_num, dma_addr,
+ rsp->req.transfer_len, addr, key,
+ nvmet_data_dir(&rsp->req));
+ } else {
+ ret = rdma_rw_ctx_init(&rsp->rw, cm_id->qp, cm_id->port_num,
+ rsp->req.sg, rsp->req.sg_cnt, 0, addr,
+ key, nvmet_data_dir(&rsp->req));
+ }
if (ret < 0)
goto error_out;
rsp->n_rdma += ret;
--
2.20.1