md/raid5: ensure we create a unique name for kmem_cache when mddev has no gendisk

We will shortly allow md devices with no gendisk (they are attached to
a dm-target instead).  That will cause mdname() to return 'mdX'.
There is one place where mdname really needs to be unique: when
creating the name for a slab cache.
So in that case, if there is no gendisk, you the address of the mddev
formatted in HEX to provide a unique name.

Signed-off-by: NeilBrown <neilb@suse.de>

2 files changed, 9 insertions, 5 deletions

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index bd4067a70834..6fa60e416a09 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -1337,10 +1337,14 @@ static int grow_stripes(raid5_conf_t *conf, int num)
         struct kmem_cache *sc;
         int devs = max(conf->raid_disks, conf->previous_raid_disks);
 
-        sprintf(conf->cache_name[0],
-                "raid%d-%s", conf->level, mdname(conf->mddev));
-        sprintf(conf->cache_name[1],
-                "raid%d-%s-alt", conf->level, mdname(conf->mddev));
+        if (conf->mddev->gendisk)
+                sprintf(conf->cache_name[0],
+                        "raid%d-%s", conf->level, mdname(conf->mddev));
+        else
+                sprintf(conf->cache_name[0],
+                        "raid%d-%p", conf->level, conf->mddev);
+        sprintf(conf->cache_name[1], "%s-alt", conf->cache_name[0]);
+
         conf->active_name = 0;
         sc = kmem_cache_create(conf->cache_name[conf->active_name],
                                sizeof(struct stripe_head)+(devs-1)*sizeof(struct r5dev),
diff --git a/drivers/md/raid5.h b/drivers/md/raid5.h
index cbdbc77695b3..61b6b25dc5e7 100644
--- a/drivers/md/raid5.h
+++ b/drivers/md/raid5.h
@@ -388,7 +388,7 @@ struct raid5_private_data {
          * two caches.
          */
         int                     active_name;
-        char                    cache_name[2][20];
+        char                    cache_name[2][32];
         struct kmem_cache               *slab_cache; /* for allocating stripes */
 
         int                     seq_flush, seq_write;