[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>

2 files changed, 87 insertions, 1 deletions

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 9ecf51ee596f..a68ad8547325 100644
--- a/drivers/md/md.c
+++ b/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;
 }
 
diff --git a/include/linux/raid/md_k.h b/include/linux/raid/md_k.h
index ebce949b1443..a9b0e47a3d04 100644
--- a/include/linux/raid/md_k.h
+++ b/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,