tree: add namespace chrdev name to nvme_ns

Namespace device node is initialized into two different nodes: block
device and character device which is a generic device used when block
device is not available due to initialization failure in the kernel.

This can be directly retrieved from the `struct nvme_ns` to print out
the generic node in somewhere like `nvme list` command in nvme-cli.

Signed-off-by: Minwoo Im <[email protected]>

Author: minwooim

src/libnvme.map

@@ -182,6 +182,7 @@
 		nvme_ns_get_model;
 		nvme_ns_get_model;
 		nvme_ns_get_name;
+		nvme_ns_get_generic_name;
 		nvme_ns_get_nguid;
 		nvme_ns_get_nsid;
 		nvme_ns_get_serial;

src/nvme/private.h

@@ -45,6 +45,7 @@ struct nvme_ns {
 	int fd;
 	__u32 nsid;
 	char *name;
+	char *generic_name;
 	char *sysfs_dir;
 
 	int lba_shift;

src/nvme/tree.c

@@ -1337,6 +1337,11 @@ const char *nvme_ns_get_name(nvme_ns_t n)
 	return n->name;
 }
 
+const char *nvme_ns_get_generic_name(nvme_ns_t n)
+{
+	return n->generic_name;
+}
+
 const char *nvme_ns_get_model(nvme_ns_t n)
 {
 	return n->c ? n->c->model : n->s->model;
@@ -1541,6 +1546,20 @@ static int nvme_ns_init(struct nvme_ns *n)
 	return 0;
 }
 
+static void nvme_ns_set_chrdev_name(struct nvme_ns *n, const char *name)
+{
+	char generic_name[PATH_MAX];
+	int instance, head_instance;
+	int ret;
+
+	ret = sscanf(name, "nvme%dn%d", &instance, &head_instance);
+	if (ret != 2)
+		return;
+
+	sprintf(generic_name, "ng%dn%d", instance, head_instance);
+	n->generic_name = strdup(generic_name);
+}
+
 static nvme_ns_t nvme_ns_open(const char *name)
 {
 	struct nvme_ns *n;
@@ -1556,6 +1575,8 @@ static nvme_ns_t nvme_ns_open(const char *name)
 	if (n->fd < 0)
 		goto free_ns;
 
+	nvme_ns_set_chrdev_name(n, name);
+
 	if (nvme_get_nsid(n->fd, &n->nsid) < 0)
 		goto close_fd;
 

src/nvme/tree.h

@@ -452,6 +452,14 @@ const char *nvme_ns_get_sysfs_dir(nvme_ns_t n);
  */
 const char *nvme_ns_get_name(nvme_ns_t n);
 
+/**
+ * nvme_ns_get_generic_name() - Returns name of generic namesapce chardev.
+ * @n: Namespace instance
+ *
+ * Return: Name of generic namespace chardev
+ */
+const char *nvme_ns_get_generic_name(nvme_ns_t n);
+
 /**
  * nvme_ns_get_firmware() -
  * @n: