nvmet: Add passthru enable/disable helpers

This patch adds helper functions which are used in the NVMeOF configfs
when the user is configuring the passthru subsystem. Here we ensure
that only one subsys is assigned to each nvme_ctrl by using an xarray
on the cntlid.

The subsystem's version number is overridden by the passed through
controller's version. However, if that version is less than 1.2.1,
then we bump the advertised version to that and print a warning
in dmesg.

Based-on-a-patch-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Christoph Hellwig <hch@lst.de>

1 files changed, 86 insertions, 0 deletions

diff --git a/drivers/nvme/target/passthru.c b/drivers/nvme/target/passthru.c
index b9727553ab30..89d91dc999a6 100644
--- a/drivers/nvme/target/passthru.c
+++ b/drivers/nvme/target/passthru.c
@@ -15,6 +15,11 @@
 
 MODULE_IMPORT_NS(NVME_TARGET_PASSTHRU);
 
+/*
+ * xarray to maintain one passthru subsystem per nvme controller.
+ */
+static DEFINE_XARRAY(passthru_subsystems);
+
 static u16 nvmet_passthru_override_id_ctrl(struct nvmet_req *req)
 {
 	struct nvmet_ctrl *ctrl = req->sq->ctrl;
@@ -456,3 +461,84 @@ u16 nvmet_parse_passthru_admin_cmd(struct nvmet_req *req)
 		return NVME_SC_INVALID_OPCODE | NVME_SC_DNR;
 	}
 }
+
+int nvmet_passthru_ctrl_enable(struct nvmet_subsys *subsys)
+{
+	struct nvme_ctrl *ctrl;
+	int ret = -EINVAL;
+	void *old;
+
+	mutex_lock(&subsys->lock);
+	if (!subsys->passthru_ctrl_path)
+		goto out_unlock;
+	if (subsys->passthru_ctrl)
+		goto out_unlock;
+
+	if (subsys->nr_namespaces) {
+		pr_info("cannot enable both passthru and regular namespaces for a single subsystem");
+		goto out_unlock;
+	}
+
+	ctrl = nvme_ctrl_get_by_path(subsys->passthru_ctrl_path);
+	if (IS_ERR(ctrl)) {
+		ret = PTR_ERR(ctrl);
+		pr_err("failed to open nvme controller %s\n",
+		       subsys->passthru_ctrl_path);
+
+		goto out_unlock;
+	}
+
+	old = xa_cmpxchg(&passthru_subsystems, ctrl->cntlid, NULL,
+			 subsys, GFP_KERNEL);
+	if (xa_is_err(old)) {
+		ret = xa_err(old);
+		goto out_put_ctrl;
+	}
+
+	if (old)
+		goto out_put_ctrl;
+
+	subsys->passthru_ctrl = ctrl;
+	subsys->ver = ctrl->vs;
+
+	if (subsys->ver < NVME_VS(1, 2, 1)) {
+		pr_warn("nvme controller version is too old: %llu.%llu.%llu, advertising 1.2.1\n",
+			NVME_MAJOR(subsys->ver), NVME_MINOR(subsys->ver),
+			NVME_TERTIARY(subsys->ver));
+		subsys->ver = NVME_VS(1, 2, 1);
+	}
+
+	mutex_unlock(&subsys->lock);
+	return 0;
+
+out_put_ctrl:
+	nvme_put_ctrl(ctrl);
+out_unlock:
+	mutex_unlock(&subsys->lock);
+	return ret;
+}
+
+static void __nvmet_passthru_ctrl_disable(struct nvmet_subsys *subsys)
+{
+	if (subsys->passthru_ctrl) {
+		xa_erase(&passthru_subsystems, subsys->passthru_ctrl->cntlid);
+		nvme_put_ctrl(subsys->passthru_ctrl);
+	}
+	subsys->passthru_ctrl = NULL;
+	subsys->ver = NVMET_DEFAULT_VS;
+}
+
+void nvmet_passthru_ctrl_disable(struct nvmet_subsys *subsys)
+{
+	mutex_lock(&subsys->lock);
+	__nvmet_passthru_ctrl_disable(subsys);
+	mutex_unlock(&subsys->lock);
+}
+
+void nvmet_passthru_subsys_free(struct nvmet_subsys *subsys)
+{
+	mutex_lock(&subsys->lock);
+	__nvmet_passthru_ctrl_disable(subsys);
+	mutex_unlock(&subsys->lock);
+	kfree(subsys->passthru_ctrl_path);
+}