nvmet-rdma: Don't use the inline buffer in order to avoid allocation for small reads

Under extreme conditions this might cause data corruptions. By doing that
we we repost the buffer and then post this buffer for the device to send.
If we happen to use shared receive queues the device might write to the
buffer before it sends it (there is no ordering between send and recv
queues). Without SRQs we probably won't get that if the host doesn't
mis-behave and send more than we allowed it, but relying on that is not
really a good idea.

Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Christoph Hellwig <hch@lst.de>

diff --git a/drivers/nvme/target/rdma.c b/drivers/nvme/target/rdma.c
index 48c811850c29b285b5e9a526086b0a749b04108e..b4d648536c3e43316cc2929f8346d4997db01306 100644 (file)
--- a/drivers/nvme/target/rdma.c
+++ b/drivers/nvme/target/rdma.c
@@ -616,15 +616,10 @@ static u16 nvmet_rdma_map_sgl_keyed(struct nvmet_rdma_rsp *rsp,
        if (!len)
                return 0;
 
-       /* use the already allocated data buffer if possible */
-       if (len <= NVMET_RDMA_INLINE_DATA_SIZE && rsp->queue->host_qid) {
-               nvmet_rdma_use_inline_sg(rsp, len, 0);
-       } else {
-               status = nvmet_rdma_alloc_sgl(&rsp->req.sg, &rsp->req.sg_cnt,
-                               len);
-               if (status)
-                       return status;
-       }
+       status = nvmet_rdma_alloc_sgl(&rsp->req.sg, &rsp->req.sg_cnt,
+                       len);
+       if (status)
+               return status;
 
        ret = rdma_rw_ctx_init(&rsp->rw, cm_id->qp, cm_id->port_num,
                        rsp->req.sg, rsp->req.sg_cnt, 0, addr, key,