[PATCH] md: initial sysfs support for md

Start using kobjects in mddevs, and provide a couple of simple attributes
(level and disks).  Attributes live in
  /sys/block/mdX/md/attr-name

Signed-off-by: Neil Brown <neilb@suse.de>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

drivers/md/md.c

@@ -181,7 +181,7 @@ static void mddev_put(mddev_t *mddev)
 	if (!mddev->raid_disks && list_empty(&mddev->disks)) {
 		list_del(&mddev->all_mddevs);
 		blk_put_queue(mddev->queue);
-		kfree(mddev);
+		kobject_unregister(&mddev->kobj);
 	}
 	spin_unlock(&all_mddevs_lock);
 }
@@ -1551,6 +1551,85 @@ static void analyze_sbs(mddev_t * mddev)
 
 }
 
+struct md_sysfs_entry {
+	struct attribute attr;
+	ssize_t (*show)(mddev_t *, char *);
+	ssize_t (*store)(mddev_t *, const char *, size_t);
+};
+
+static ssize_t
+md_show_level(mddev_t *mddev, char *page)
+{
+	mdk_personality_t *p = mddev->pers;
+	if (p == NULL)
+		return 0;
+	if (mddev->level >= 0)
+		return sprintf(page, "RAID-%d\n", mddev->level);
+	else
+		return sprintf(page, "%s\n", p->name);
+}
+
+static struct md_sysfs_entry md_level = {
+	.attr = {.name = "level", .mode = S_IRUGO },
+	.show = md_show_level,
+};
+
+static ssize_t
+md_show_rdisks(mddev_t *mddev, char *page)
+{
+	return sprintf(page, "%d\n", mddev->raid_disks);
+}
+
+static struct md_sysfs_entry md_raid_disks = {
+	.attr = {.name = "raid_disks", .mode = S_IRUGO },
+	.show = md_show_rdisks,
+};
+
+static struct attribute *md_default_attrs[] = {
+	&md_level.attr,
+	&md_raid_disks.attr,
+	NULL,
+};
+
+static ssize_t
+md_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
+{
+	struct md_sysfs_entry *entry = container_of(attr, struct md_sysfs_entry, attr);
+	mddev_t *mddev = container_of(kobj, struct mddev_s, kobj);
+
+	if (!entry->show)
+		return -EIO;
+	return entry->show(mddev, page);
+}
+
+static ssize_t
+md_attr_store(struct kobject *kobj, struct attribute *attr,
+	      const char *page, size_t length)
+{
+	struct md_sysfs_entry *entry = container_of(attr, struct md_sysfs_entry, attr);
+	mddev_t *mddev = container_of(kobj, struct mddev_s, kobj);
+
+	if (!entry->store)
+		return -EIO;
+	return entry->store(mddev, page, length);
+}
+
+static void md_free(struct kobject *ko)
+{
+	mddev_t *mddev = container_of(ko, mddev_t, kobj);
+	kfree(mddev);
+}
+
+static struct sysfs_ops md_sysfs_ops = {
+	.show	= md_attr_show,
+	.store	= md_attr_store,
+};
+static struct kobj_type md_ktype = {
+	.release	= md_free,
+	.sysfs_ops	= &md_sysfs_ops,
+	.default_attrs	= md_default_attrs,
+};
+
 int mdp_major = 0;
 
 static struct kobject *md_probe(dev_t dev, int *part, void *data)
@@ -1592,6 +1671,11 @@ static struct kobject *md_probe(dev_t dev, int *part, void *data)
 	add_disk(disk);
 	mddev->gendisk = disk;
 	up(&disks_sem);
+	mddev->kobj.parent = kobject_get(&disk->kobj);
+	mddev->kobj.k_name = NULL;
+	snprintf(mddev->kobj.name, KOBJ_NAME_LEN, "%s", "md");
+	mddev->kobj.ktype = &md_ktype;
+	kobject_register(&mddev->kobj);
 	return NULL;
 }
 

include/linux/raid/md_k.h

@@ -148,6 +148,8 @@ struct mddev_s
 
 	struct gendisk			*gendisk;
 
+	struct kobject			kobj;
+
 	/* Superblock information */
 	int				major_version,
 					minor_version,