[PATCH] md: Add sysfs access to raid6 stripe cache size

.. just as we already have for raid5.

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>

1 files changed, 115 insertions, 34 deletions

diff --git a/drivers/md/raid6main.c b/drivers/md/raid6main.c
index f618a53b98be..ed2abb2e2e2d 100644
--- a/drivers/md/raid6main.c
+++ b/drivers/md/raid6main.c
@@ -115,7 +115,7 @@ static void __release_stripe(raid6_conf_t *conf, struct stripe_head *sh)
                         list_add_tail(&sh->lru, &conf->inactive_list);
                         atomic_dec(&conf->active_stripes);
                         if (!conf->inactive_blocked ||
-                            atomic_read(&conf->active_stripes) < (NR_STRIPES*3/4))
+                            atomic_read(&conf->active_stripes) < (conf->max_nr_stripes*3/4))
                                 wake_up(&conf->wait_for_stripe);
                 }
         }
@@ -273,7 +273,8 @@ static struct stripe_head *get_active_stripe(raid6_conf_t *conf, sector_t sector
                                 conf->inactive_blocked = 1;
                                 wait_event_lock_irq(conf->wait_for_stripe,
                                                     !list_empty(&conf->inactive_list) &&
-                                                    (atomic_read(&conf->active_stripes) < (NR_STRIPES *3/4)
+                                                    (atomic_read(&conf->active_stripes)
+                                                     < (conf->max_nr_stripes *3/4)
                                                      || !conf->inactive_blocked),
                                                     conf->device_lock,
                                                     unplug_slaves(conf->mddev);
@@ -302,9 +303,31 @@ static struct stripe_head *get_active_stripe(raid6_conf_t *conf, sector_t sector
         return sh;
 }
 
-static int grow_stripes(raid6_conf_t *conf, int num)
+static int grow_one_stripe(raid6_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(raid6_conf_t *conf, int num)
+{
         kmem_cache_t *sc;
         int devs = conf->raid_disks;
 
@@ -316,44 +339,33 @@ static int grow_stripes(raid6_conf_t *conf, int num)
         if (!sc)
                 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);
+        while (num--)
+                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(raid6_conf_t *conf)
+static int drop_one_stripe(raid6_conf_t *conf)
 {
         struct stripe_head *sh;
+        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(raid6_conf_t *conf)
+{
+        while (drop_one_stripe(conf))
+                ;
 
-        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);
-        }
         kmem_cache_destroy(conf->slab_cache);
         conf->slab_cache = NULL;
 }
@@ -1912,6 +1924,74 @@ static void raid6d (mddev_t *mddev)
         PRINTK("--- raid6d inactive\n");
 }
 
+static ssize_t
+raid6_show_stripe_cache_size(mddev_t *mddev, char *page)
+{
+        raid6_conf_t *conf = mddev_to_conf(mddev);
+        if (conf)
+                return sprintf(page, "%d\n", conf->max_nr_stripes);
+        else
+                return 0;
+}
+
+static ssize_t
+raid6_store_stripe_cache_size(mddev_t *mddev, const char *page, size_t len)
+{
+        raid6_conf_t *conf = mddev_to_conf(mddev);
+        char *end;
+        int new;
+        if (len >= PAGE_SIZE)
+                return -EINVAL;
+        if (!conf)
+                return -ENODEV;
+
+        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 md_sysfs_entry
+raid6_stripecache_size = __ATTR(stripe_cache_size, S_IRUGO | S_IWUSR,
+                                raid6_show_stripe_cache_size,
+                                raid6_store_stripe_cache_size);
+
+static ssize_t
+stripe_cache_active_show(mddev_t *mddev, char *page)
+{
+        raid6_conf_t *conf = mddev_to_conf(mddev);
+        if (conf)
+                return sprintf(page, "%d\n", atomic_read(&conf->active_stripes));
+        else
+                return 0;
+}
+
+static struct md_sysfs_entry
+raid6_stripecache_active = __ATTR_RO(stripe_cache_active);
+
+static struct attribute *raid6_attrs[] =  {
+        &raid6_stripecache_size.attr,
+        &raid6_stripecache_active.attr,
+        NULL,
+};
+static struct attribute_group raid6_attrs_group = {
+        .name = NULL,
+        .attrs = raid6_attrs,
+};
+
 static int run(mddev_t *mddev)
 {
         raid6_conf_t *conf;
@@ -2095,6 +2175,7 @@ static int stop (mddev_t *mddev)
         shrink_stripes(conf);
         kfree(conf->stripe_hashtbl);
         blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
+        sysfs_remove_group(&mddev->kobj, &raid6_attrs_group);
         kfree(conf);
         mddev->private = NULL;
         return 0;