A patch for review that allows dynamic configuration of the subsystem model.

[Mark Ruijter <MRuijter@onestopsystems.com>]

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The attached patch allows to dynamically change the subsystem model while keeping 'Linux' as the default.
For example:

dev:/sys/kernel/config/nvmet/subsystems/loop # cat attr_model 
Linux

# nvme list
Node             SN                   Model                                    Namespace Usage                      Format           FW Rev  
---------------- -------------------- ---------------------------------------- --------- -------------------------- ---------------- --------
/dev/nvme0n1     4d11eb57c7078f19     Linux                                    1         104,86  MB / 104,86  MB    512   B +  0 B   5.3.5

# echo mypool/myvolume > attr_model 

root@crunchie:/tmp# nvme list
Node             SN                   Model                                    Namespace Usage                      Format           FW Rev  
---------------- -------------------- ---------------------------------------- --------- -------------------------- ---------------- --------
/dev/nvme0n1     4d11eb57c7078f19     mypool/myvolume                          1         104,86  MB / 104,86  MB    512   B +  0 B   5.3.5

The attr_model input is validated to what the NVME specification allows for a ascii string:

echo -e "my\t pool" > attr_model 
-bash: echo: write error: Invalid argument
dev:/sys/kernel/config/nvmet/subsystems/loop #

I hope this is useful,

Thanks,

Mark Ruijter


[-- Attachment #2: subsystem_model.patch --]
[-- Type: application/octet-stream, Size: 3477 bytes --]

diff --git a/admin-cmd.c b/admin-cmd.c
index 51800a9..bbf6fec 100644
--- a/admin-cmd.c
+++ b/admin-cmd.c
@@ -289,7 +289,6 @@ static void nvmet_execute_identify_ctrl(struct nvmet_req *req)
 	struct nvmet_ctrl *ctrl = req->sq->ctrl;
 	struct nvme_id_ctrl *id;
 	u16 status = 0;
-	const char model[] = "Linux";
 
 	id = kzalloc(sizeof(*id), GFP_KERNEL);
 	if (!id) {
@@ -304,7 +303,8 @@ static void nvmet_execute_identify_ctrl(struct nvmet_req *req)
 	memset(id->sn, ' ', sizeof(id->sn));
 	bin2hex(id->sn, &ctrl->subsys->serial,
 		min(sizeof(ctrl->subsys->serial), sizeof(id->sn) / 2));
-	memcpy_and_pad(id->mn, sizeof(id->mn), model, sizeof(model) - 1, ' ');
+	memcpy_and_pad(id->mn, sizeof(id->mn), ctrl->subsys->model,
+		strlen(ctrl->subsys->model), ' ');
 	memcpy_and_pad(id->fr, sizeof(id->fr),
 		       UTS_RELEASE, strlen(UTS_RELEASE), ' ');
 
diff --git a/configfs.c b/configfs.c
index 59c2b79..123289d 100644
--- a/configfs.c
+++ b/configfs.c
@@ -891,10 +891,56 @@ static ssize_t nvmet_subsys_attr_serial_store(struct config_item *item,
 }
 CONFIGFS_ATTR(nvmet_subsys_, attr_serial);
 
+static ssize_t nvmet_subsys_attr_model_show(struct config_item *item,
+                                             char *page)
+{
+        struct nvmet_subsys *subsys = to_subsys(item);
+
+        return snprintf(page, PAGE_SIZE, "%s\n", subsys->model);
+}
+
+static ssize_t nvmet_subsys_attr_model_store(struct config_item *item,
+                                              const char *page, size_t count)
+{
+        struct nvmet_subsys *subsys = to_subsys(item);
+	int len;
+	int ret = -EINVAL;
+	char c;
+	int pos = 0;
+
+        down_write(&nvmet_config_sem);
+        len = strcspn(page, "\n");
+        if (!len)
+                goto out_unlock;
+
+	/* Only 20h until 7eh is allowed */
+	c = page[pos];
+	while (pos < len)
+	{
+		if (c < 0x20 || c > 0x7e) {
+			goto out_unlock;
+		}
+		pos++;
+		c = page[pos];
+	}
+
+	kfree(subsys->model);
+	ret = -ENOMEM;
+	subsys->model = kstrndup(page, len, GFP_KERNEL);
+	if(subsys->model)
+		ret = count;
+out_unlock:
+        up_write(&nvmet_config_sem);
+        return ret;
+}
+
+CONFIGFS_ATTR(nvmet_subsys_, attr_model);
+
 static struct configfs_attribute *nvmet_subsys_attrs[] = {
 	&nvmet_subsys_attr_attr_allow_any_host,
 	&nvmet_subsys_attr_attr_version,
 	&nvmet_subsys_attr_attr_serial,
+	&nvmet_subsys_attr_attr_model,
 	NULL,
 };
 
@@ -930,6 +976,7 @@ static struct config_group *nvmet_subsys_make(struct config_group *group,
 	}
 
 	subsys = nvmet_subsys_alloc(name, NVME_NQN_NVME);
+	subsys->model = kstrdup("Linux", GFP_KERNEL);
 	if (IS_ERR(subsys))
 		return ERR_CAST(subsys);
 
diff --git a/core.c b/core.c
index 9f17d07..6049e6a 100644
--- a/core.c
+++ b/core.c
@@ -1418,6 +1418,12 @@ struct nvmet_subsys *nvmet_subsys_alloc(const char *subsysnqn,
 		kfree(subsys);
 		return ERR_PTR(-ENOMEM);
 	}
+	subsys->model = kstrdup("Linux", GFP_KERNEL);
+	if (!subsys->model) {
+		kfree(subsys->subsysnqn);
+		kfree(subsys);
+		return ERR_PTR(-ENOMEM);
+	}
 
 	kref_init(&subsys->ref);
 
@@ -1437,6 +1443,7 @@ static void nvmet_subsys_free(struct kref *ref)
 	WARN_ON_ONCE(!list_empty(&subsys->namespaces));
 
 	kfree(subsys->subsysnqn);
+	kfree(subsys->model);
 	kfree(subsys);
 }
 
diff --git a/nvmet.h b/nvmet.h
index 20aa830..200c03c 100644
--- a/nvmet.h
+++ b/nvmet.h
@@ -223,6 +223,7 @@ struct nvmet_subsys {
 	u64			ver;
 	u64			serial;
 	char			*subsysnqn;
+	char			*model;
 
 	struct config_group	group;
 

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