nvmet: convert from kmap to nvmet_copy_from_sgl

This is safer as it doesn't rely on the data being stored in
a single page in an sgl.

It also aids our effort to start phasing out users of sg_page. See [1].

For this we kmalloc some memory, copy to it and free at the end. Note:
we can't allocate this memory on the stack as the kbuild test robot
reports some frame size overflows on i386.

[1] https://lwn.net/Articles/720053/

Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Max Gurtovoy <maxg@mellanox.com>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>

diff --git a/drivers/nvme/target/fabrics-cmd.c b/drivers/nvme/target/fabrics-cmd.c
index 2a3c15b57f6e580d5ea23a2e56baa1711c543efa..3cc17269504bff54bfe93a8ede5995d94f7ab699 100644 (file)
--- a/drivers/nvme/target/fabrics-cmd.c
+++ b/drivers/nvme/target/fabrics-cmd.c
@@ -122,7 +122,15 @@ static void nvmet_execute_admin_connect(struct nvmet_req *req)
        struct nvmet_ctrl *ctrl = NULL;
        u16 status = 0;
 
-       d = kmap(sg_page(req->sg)) + req->sg->offset;
+       d = kmalloc(sizeof(*d), GFP_KERNEL);
+       if (!d) {
+               status = NVME_SC_INTERNAL;
+               goto complete;
+       }
+
+       status = nvmet_copy_from_sgl(req, 0, d, sizeof(*d));
+       if (status)
+               goto out;
 
        /* zero out initial completion result, assign values as needed */
        req->rsp->result.u32 = 0;
@@ -143,7 +151,7 @@ static void nvmet_execute_admin_connect(struct nvmet_req *req)
        }
 
        status = nvmet_alloc_ctrl(d->subsysnqn, d->hostnqn, req,
-                       le32_to_cpu(c->kato), &ctrl);
+                                 le32_to_cpu(c->kato), &ctrl);
        if (status)
                goto out;
 
@@ -158,7 +166,8 @@ static void nvmet_execute_admin_connect(struct nvmet_req *req)
        req->rsp->result.u16 = cpu_to_le16(ctrl->cntlid);
 
 out:
-       kunmap(sg_page(req->sg));
+       kfree(d);
+complete:
        nvmet_req_complete(req, status);
 }
 
@@ -170,7 +179,15 @@ static void nvmet_execute_io_connect(struct nvmet_req *req)
        u16 qid = le16_to_cpu(c->qid);
        u16 status = 0;
 
-       d = kmap(sg_page(req->sg)) + req->sg->offset;
+       d = kmalloc(sizeof(*d), GFP_KERNEL);
+       if (!d) {
+               status = NVME_SC_INTERNAL;
+               goto complete;
+       }
+
+       status = nvmet_copy_from_sgl(req, 0, d, sizeof(*d));
+       if (status)
+               goto out;
 
        /* zero out initial completion result, assign values as needed */
        req->rsp->result.u32 = 0;
@@ -183,8 +200,8 @@ static void nvmet_execute_io_connect(struct nvmet_req *req)
        }
 
        status = nvmet_ctrl_find_get(d->subsysnqn, d->hostnqn,
-                       le16_to_cpu(d->cntlid),
-                       req, &ctrl);
+                                    le16_to_cpu(d->cntlid),
+                                    req, &ctrl);
        if (status)
                goto out;
 
@@ -205,7 +222,8 @@ static void nvmet_execute_io_connect(struct nvmet_req *req)
        pr_info("adding queue %d to ctrl %d.\n", qid, ctrl->cntlid);
 
 out:
-       kunmap(sg_page(req->sg));
+       kfree(d);
+complete:
        nvmet_req_complete(req, status);
        return;