libnvme: annotate libnvme_subsystem::iopolicy with !accessors:none

The default accessor generation creates getters that return cached
attribute values. However, for libnvme_subsystem::iopolicy, a real-time
(non-cached) value is required.

This is particularly useful for tools such as nvme-top, which rely on
up-to-date information for displaying a real-time dashboard.

Annotate libnvme_subsystem::iopolicy with "!accessors:none" to disable the
auto-generated accessor, and provide a custom implementation of
libnvme_subsystem_get_iopolicy() that returns the current value.

Signed-off-by: Nilay Shroff <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Daniel Wagner <[email protected]>

Author: shroffni

libnvme/libnvme/nvme-swig-accessors.i

@@ -130,9 +130,7 @@
 	#define libnvme_subsystem_firmware_get    libnvme_subsystem_get_firmware
 	#define libnvme_subsystem_subsystype_get  libnvme_subsystem_get_subsystype
 	#define libnvme_subsystem_application_get libnvme_subsystem_get_application
-	#define libnvme_subsystem_iopolicy_get    libnvme_subsystem_get_iopolicy
 	#define libnvme_subsystem_application_set libnvme_subsystem_set_application
-	#define libnvme_subsystem_iopolicy_set    libnvme_subsystem_set_iopolicy
 
 	/* struct libnvme_host */
 	#define libnvme_host_hostnqn_get           libnvme_host_get_hostnqn

libnvme/src/accessors.ld

@@ -174,13 +174,11 @@ LIBNVME_ACCESSORS_3 {
 		libnvme_path_set_sysfs_dir;
 		libnvme_subsystem_get_application;
 		libnvme_subsystem_get_firmware;
-		libnvme_subsystem_get_iopolicy;
 		libnvme_subsystem_get_model;
 		libnvme_subsystem_get_name;
 		libnvme_subsystem_get_serial;
 		libnvme_subsystem_get_subsysnqn;
 		libnvme_subsystem_get_subsystype;
 		libnvme_subsystem_get_sysfs_dir;
 		libnvme_subsystem_set_application;
-		libnvme_subsystem_set_iopolicy;
 };

libnvme/src/libnvme.ld

@@ -177,6 +177,7 @@ LIBNVME_3 {
 		libnvme_subsystem_first_ctrl;
 		libnvme_subsystem_first_ns;
 		libnvme_subsystem_get_host;
+		libnvme_subsystem_get_iopolicy;
 		libnvme_subsystem_lookup_namespace;
 		libnvme_subsystem_next_ctrl;
 		libnvme_subsystem_next_ns;

libnvme/src/nvme/accessors.c

@@ -661,20 +661,6 @@ __public const char *libnvme_subsystem_get_application(
 	return p->application;
 }
 
-__public void libnvme_subsystem_set_iopolicy(
-		struct libnvme_subsystem *p,
-		const char *iopolicy)
-{
-	free(p->iopolicy);
-	p->iopolicy = iopolicy ? strdup(iopolicy) : NULL;
-}
-
-__public const char *libnvme_subsystem_get_iopolicy(
-		const struct libnvme_subsystem *p)
-{
-	return p->iopolicy;
-}
-
 /****************************************************************************
  * Accessors for: struct libnvme_host
  ****************************************************************************/

libnvme/src/nvme/accessors.h

@@ -901,23 +901,6 @@ void libnvme_subsystem_set_application(
 const char *libnvme_subsystem_get_application(
 		const struct libnvme_subsystem *p);
 
-/**
- * libnvme_subsystem_set_iopolicy() - Set iopolicy.
- * @p: The &struct libnvme_subsystem instance to update.
- * @iopolicy: New string; a copy is stored. Pass NULL to clear.
- */
-void libnvme_subsystem_set_iopolicy(
-		struct libnvme_subsystem *p,
-		const char *iopolicy);
-
-/**
- * libnvme_subsystem_get_iopolicy() - Get iopolicy.
- * @p: The &struct libnvme_subsystem instance to query.
- *
- * Return: The value of the iopolicy field, or NULL if not set.
- */
-const char *libnvme_subsystem_get_iopolicy(const struct libnvme_subsystem *p);
-
 /****************************************************************************
  * Accessors for: struct libnvme_host
  ****************************************************************************/

libnvme/src/nvme/private.h

@@ -272,7 +272,7 @@ struct libnvme_subsystem {		// !generate-accessors
 	char *firmware;			// !accessors:readonly
 	char *subsystype;		// !accessors:readonly
 	char *application;
-	char *iopolicy;
+	char *iopolicy;			// !accessors:none
 };
 
 struct libnvme_host {			// !generate-accessors

libnvme/src/nvme/tree.c

@@ -464,6 +464,21 @@ __public libnvme_host_t libnvme_subsystem_get_host(libnvme_subsystem_t s)
 	return s->h;
 }
 
+__public char *libnvme_subsystem_get_iopolicy(libnvme_subsystem_t s)
+{
+	__cleanup_free char *iopolicy = NULL;
+
+	iopolicy = libnvme_get_subsys_attr(s, "iopolicy");
+	if (iopolicy) {
+		if (!s->iopolicy || strcmp(iopolicy, s->iopolicy)) {
+			free(s->iopolicy);
+			s->iopolicy = strdup(iopolicy);
+		}
+	}
+
+	return s->iopolicy;
+}
+
 __public libnvme_ns_t libnvme_subsystem_first_ns(libnvme_subsystem_t s)
 {
 	return list_top(&s->namespaces, struct libnvme_ns, entry);

libnvme/src/nvme/tree.h

@@ -214,6 +214,14 @@ void libnvme_free_subsystem(struct libnvme_subsystem *s);
  */
 libnvme_host_t libnvme_subsystem_get_host(libnvme_subsystem_t s);
 
+/**
+ * libnvme_subsystem_get_iopolicy() - Get subsystem iopolicy name
+ * @s:	subsystem
+ *
+ * Return: The iopolicy configured in subsystem @s
+ */
+char *libnvme_subsystem_get_iopolicy(libnvme_subsystem_t s);
+
 /**
  * libnvme_ctrl_first_ns() - Start namespace iterator
  * @c:	Controller instance