[PATCH v8 12/13] nvmet: Introduce helper functions to allocate and free request SGLs

Logan Gunthorpe
2018-09-27T16:54:49Z

Add helpers to allocate and free the SGL in a struct nvmet_req:

int nvmet_req_alloc_sgl(struct nvmet_req *req, struct nvmet_sq *sq)
void nvmet_req_free_sgl(struct nvmet_req *req)

This will be expanded in a future patch to implement peer-to-peer
memory DMAs and should be common with all target drivers. The presently
unused 'sq' argument in the alloc function will be necessary to
decide whether to use peer-to-peer memory and obtain the correct
provider to allocate the memory.

The new helpers are used in nvmet-rdma. Seeing we use req.transfer_len
as the length of the SGL it is set earlier and cleared on any error.
It also seems to be unnecessary to accumulate the length as the map_sgl
functions should only ever be called once per request.

Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Acked-by: Sagi Grimberg <sagi@grimberg.me>
Cc: Christoph Hellwig <hch@lst.de>
---
drivers/nvme/target/core.c | 18 ++++++++++++++++++
drivers/nvme/target/nvmet.h | 2 ++
drivers/nvme/target/rdma.c | 20 ++++++++++++--------
3 files changed, 32 insertions(+), 8 deletions(-)

diff --git a/drivers/nvme/target/core.c b/drivers/nvme/target/core.c
index b5ec96abd048..bddd1599b826 100644
--- a/drivers/nvme/target/core.c
+++ b/drivers/nvme/target/core.c
@@ -725,6 +725,24 @@ void nvmet_req_execute(struct nvmet_req *req)
}
EXPORT_SYMBOL_GPL(nvmet_req_execute);

+int nvmet_req_alloc_sgl(struct nvmet_req *req, struct nvmet_sq *sq)
+{
+ req->sg = sgl_alloc(req->transfer_len, GFP_KERNEL, &req->sg_cnt);
+ if (!req->sg)
+ return -ENOMEM;
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(nvmet_req_alloc_sgl);
+
+void nvmet_req_free_sgl(struct nvmet_req *req)
+{
+ sgl_free(req->sg);
+ req->sg = NULL;
+ req->sg_cnt = 0;
+}
+EXPORT_SYMBOL_GPL(nvmet_req_free_sgl);
+
static inline bool nvmet_cc_en(u32 cc)
{
return (cc >> NVME_CC_EN_SHIFT) & 0x1;
diff --git a/drivers/nvme/target/nvmet.h b/drivers/nvme/target/nvmet.h
index ec9af4ee03b6..7d6cb61021e4 100644
--- a/drivers/nvme/target/nvmet.h
+++ b/drivers/nvme/target/nvmet.h
@@ -336,6 +336,8 @@ bool nvmet_req_init(struct nvmet_req *req, struct nvmet_cq *cq,
void nvmet_req_uninit(struct nvmet_req *req);
void nvmet_req_execute(struct nvmet_req *req);
void nvmet_req_complete(struct nvmet_req *req, u16 status);
+int nvmet_req_alloc_sgl(struct nvmet_req *req, struct nvmet_sq *sq);
+void nvmet_req_free_sgl(struct nvmet_req *req);

void nvmet_cq_setup(struct nvmet_ctrl *ctrl, struct nvmet_cq *cq, u16 qid,
u16 size);
diff --git a/drivers/nvme/target/rdma.c b/drivers/nvme/target/rdma.c
index bfc4da660bb4..b0d0cedc74bb 100644
--- a/drivers/nvme/target/rdma.c
+++ b/drivers/nvme/target/rdma.c
@@ -503,7 +503,7 @@ static void nvmet_rdma_release_rsp(struct nvmet_rdma_rsp *rsp)
}

if (rsp->req.sg != rsp->cmd->inline_sg)
- sgl_free(rsp->req.sg);
+ nvmet_req_free_sgl(&rsp->req);

if (unlikely(!list_empty_careful(&queue->rsp_wr_wait_list)))
nvmet_rdma_process_wr_wait_list(queue);
@@ -652,24 +652,24 @@ 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 len = get_unaligned_le24(sgl->length);
u32 key = get_unaligned_le32(sgl->key);
int ret;

+ rsp->req.transfer_len = get_unaligned_le24(sgl->length);
+
/* no data command? */
- if (!len)
+ if (!rsp->req.transfer_len)
return 0;

- rsp->req.sg = sgl_alloc(len, GFP_KERNEL, &rsp->req.sg_cnt);
- if (!rsp->req.sg)
- return NVME_SC_INTERNAL;
+ ret = nvmet_req_alloc_sgl(&rsp->req, &rsp->queue->nvme_sq);
+ 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 (ret < 0)
- return NVME_SC_INTERNAL;
- rsp->req.transfer_len += len;
+ goto error_out;
rsp->n_rdma += ret;

if (invalidate) {
@@ -678,6 +678,10 @@ static u16 nvmet_rdma_map_sgl_keyed(struct nvmet_rdma_rsp *rsp,
}

return 0;
+
+error_out:
+ rsp->req.transfer_len = 0;
+ return NVME_SC_INTERNAL;
}

static u16 nvmet_rdma_map_sgl(struct nvmet_rdma_rsp *rsp)
--
2.19.0