[PATCH] md: add kobject/sysfs support to raid5

/sys/block/mdX/md/raid5/
contains raid5-related attributes.
Currently
  stripe_cache_size
is number of entries in stripe cache, and is settable.
  stripe_cache_active
is number of active entries, and in only readable.

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, 152 insertions, 32 deletions

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 8cf1ae8b8a71..121fbaa9ed59 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -293,9 +293,31 @@ static struct stripe_head *get_active_stripe(raid5_conf_t *conf, sector_t sector
         return sh;
 }
 
-static int grow_stripes(raid5_conf_t *conf, int num)
+static int grow_one_stripe(raid5_conf_t *conf)
 {
         struct stripe_head *sh;
+        sh = kmem_cache_alloc(conf->slab_cache, GFP_KERNEL);
+        if (!sh)
+                return 0;
+        memset(sh, 0, sizeof(*sh) + (conf->raid_disks-1)*sizeof(struct r5dev));
+        sh->raid_conf = conf;
+        spin_lock_init(&sh->lock);
+
+        if (grow_buffers(sh, conf->raid_disks)) {
+                shrink_buffers(sh, conf->raid_disks);
+                kmem_cache_free(conf->slab_cache, sh);
+                return 0;
+        }
+        /* we just created an active stripe so... */
+        atomic_set(&sh->count, 1);
+        atomic_inc(&conf->active_stripes);
+        INIT_LIST_HEAD(&sh->lru);
+        release_stripe(sh);
+        return 1;
+}
+
+static int grow_stripes(raid5_conf_t *conf, int num)
+{
         kmem_cache_t *sc;
         int devs = conf->raid_disks;
 
@@ -308,43 +330,34 @@ static int grow_stripes(raid5_conf_t *conf, int num)
                 return 1;
         conf->slab_cache = sc;
         while (num--) {
-                sh = kmem_cache_alloc(sc, GFP_KERNEL);
-                if (!sh)
-                        return 1;
-                memset(sh, 0, sizeof(*sh) + (devs-1)*sizeof(struct r5dev));
-                sh->raid_conf = conf;
-                spin_lock_init(&sh->lock);
-
-                if (grow_buffers(sh, conf->raid_disks)) {
-                        shrink_buffers(sh, conf->raid_disks);
-                        kmem_cache_free(sc, sh);
+                if (!grow_one_stripe(conf))
                         return 1;
-                }
-                /* we just created an active stripe so... */
-                atomic_set(&sh->count, 1);
-                atomic_inc(&conf->active_stripes);
-                INIT_LIST_HEAD(&sh->lru);
-                release_stripe(sh);
         }
         return 0;
 }
 
-static void shrink_stripes(raid5_conf_t *conf)
+static int drop_one_stripe(raid5_conf_t *conf)
 {
         struct stripe_head *sh;
 
-        while (1) {
-                spin_lock_irq(&conf->device_lock);
-                sh = get_free_stripe(conf);
-                spin_unlock_irq(&conf->device_lock);
-                if (!sh)
-                        break;
-                if (atomic_read(&sh->count))
-                        BUG();
-                shrink_buffers(sh, conf->raid_disks);
-                kmem_cache_free(conf->slab_cache, sh);
-                atomic_dec(&conf->active_stripes);
-        }
+        spin_lock_irq(&conf->device_lock);
+        sh = get_free_stripe(conf);
+        spin_unlock_irq(&conf->device_lock);
+        if (!sh)
+                return 0;
+        if (atomic_read(&sh->count))
+                BUG();
+        shrink_buffers(sh, conf->raid_disks);
+        kmem_cache_free(conf->slab_cache, sh);
+        atomic_dec(&conf->active_stripes);
+        return 1;
+}
+
+static void shrink_stripes(raid5_conf_t *conf)
+{
+        while (drop_one_stripe(conf))
+                ;
+
         kmem_cache_destroy(conf->slab_cache);
         conf->slab_cache = NULL;
 }
@@ -1714,6 +1727,108 @@ static void raid5d (mddev_t *mddev)
         PRINTK("--- raid5d inactive\n");
 }
 
+struct raid5_sysfs_entry {
+        struct attribute attr;
+        ssize_t (*show)(raid5_conf_t *, char *);
+        ssize_t (*store)(raid5_conf_t *, const char *, ssize_t);
+};
+
+static ssize_t
+raid5_show_stripe_cache_size(raid5_conf_t *conf, char *page)
+{
+        return sprintf(page, "%d\n", conf->max_nr_stripes);
+}
+
+static ssize_t
+raid5_store_stripe_cache_size(raid5_conf_t *conf, const char *page, ssize_t len)
+{
+        char *end;
+        int new;
+        if (len >= PAGE_SIZE)
+                return -EINVAL;
+
+        new = simple_strtoul(page, &end, 10);
+        if (!*page || (*end && *end != '\n') )
+                return -EINVAL;
+        if (new <= 16 || new > 32768)
+                return -EINVAL;
+        while (new < conf->max_nr_stripes) {
+                if (drop_one_stripe(conf))
+                        conf->max_nr_stripes--;
+                else
+                        break;
+        }
+        while (new > conf->max_nr_stripes) {
+                if (grow_one_stripe(conf))
+                        conf->max_nr_stripes++;
+                else break;
+        }
+        return len;
+}
+static struct raid5_sysfs_entry raid5_stripecache_size = {
+        .attr = {.name = "stripe_cache_size", .mode = S_IRUGO | S_IWUSR },
+        .show = raid5_show_stripe_cache_size,
+        .store = raid5_store_stripe_cache_size,
+};
+
+static ssize_t
+raid5_show_stripe_cache_active(raid5_conf_t *conf, char *page)
+{
+        return sprintf(page, "%d\n", atomic_read(&conf->active_stripes));
+}
+
+static struct raid5_sysfs_entry raid5_stripecache_active = {
+        .attr = {.name = "stripe_cache_active", .mode = S_IRUGO},
+        .show = raid5_show_stripe_cache_active,
+};
+
+static struct attribute *raid5_default_attrs[] = {
+        &raid5_stripecache_size.attr,
+        &raid5_stripecache_active.attr,
+        NULL,
+};
+
+static ssize_t
+raid5_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
+{
+        struct raid5_sysfs_entry *entry = container_of(attr, struct raid5_sysfs_entry, attr);
+        raid5_conf_t *conf = container_of(kobj, raid5_conf_t, kobj);
+
+        if (!entry->show)
+                return -EIO;
+        return entry->show(conf, page);
+}
+
+static ssize_t
+raid5_attr_store(struct kobject *kobj, struct attribute *attr,
+              const char *page, size_t length)
+{
+        struct raid5_sysfs_entry *entry = container_of(attr, struct raid5_sysfs_entry, attr);
+        raid5_conf_t *conf = container_of(kobj, raid5_conf_t, kobj);
+
+        if (!entry->store)
+                return -EIO;
+        return entry->store(conf, page, length);
+}
+
+static void raid5_free(struct kobject *ko)
+{
+        raid5_conf_t *conf = container_of(ko, raid5_conf_t, kobj);
+        kfree(conf);
+}
+
+
+static struct sysfs_ops raid5_sysfs_ops = {
+        .show           = raid5_attr_show,
+        .store          = raid5_attr_store,
+};
+
+static struct kobj_type raid5_ktype = {
+        .release        = raid5_free,
+        .sysfs_ops      = &raid5_sysfs_ops,
+        .default_attrs  = raid5_default_attrs,
+};
+
 static int run(mddev_t *mddev)
 {
         raid5_conf_t *conf;
@@ -1855,6 +1970,10 @@ memory = conf->max_nr_stripes * (sizeof(struct stripe_head) +
         }
 
         /* Ok, everything is just fine now */
+        conf->kobj.parent = kobject_get(&mddev->kobj);
+        strcpy(conf->kobj.name, "raid5");
+        conf->kobj.ktype = &raid5_ktype;
+        kobject_register(&conf->kobj);
 
         if (mddev->bitmap)
                 mddev->thread->timeout = mddev->bitmap->daemon_sleep * HZ;
@@ -1879,7 +1998,7 @@ abort:
 
 
 
-static int stop (mddev_t *mddev)
+static int stop(mddev_t *mddev)
 {
         raid5_conf_t *conf = (raid5_conf_t *) mddev->private;
 
@@ -1888,7 +2007,7 @@ static int stop (mddev_t *mddev)
         shrink_stripes(conf);
         free_pages((unsigned long) conf->stripe_hashtbl, HASH_PAGES_ORDER);
         blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
-        kfree(conf);
+        kobject_unregister(&conf->kobj);
         mddev->private = NULL;
         return 0;
 }
diff --git a/include/linux/raid/raid5.h b/include/linux/raid/raid5.h
index f025ba6fb14c..5f4e945c8083 100644
--- a/include/linux/raid/raid5.h
+++ b/include/linux/raid/raid5.h
@@ -228,6 +228,7 @@ struct raid5_private_data {
                                             * Cleared when a sync completes.
                                             */
 
+        struct kobject          kobj;
         /*
          * Free stripes pool
          */