md/raid5: move max_nr_stripes management into grow_one_stripe and drop_one_stripe

Rather than adjusting max_nr_stripes whenever {grow,drop}_one_stripe()
succeeds, do it inside the functions.

Also choose the correct hash to handle next inside the functions.

This removes duplication and will help with future new uses of
{grow,drop}_one_stripe.

This also fixes a minor bug where the "md/raid:%md: allocate XXkB"
message always said "0kB".

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

1 files changed, 24 insertions, 33 deletions

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index ed8e34153c3d..78ac7dc853c7 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -1963,7 +1963,7 @@ static void raid_run_ops(struct stripe_head *sh, unsigned long ops_request)
         put_cpu();
 }
 
-static int grow_one_stripe(struct r5conf *conf, int hash, gfp_t gfp)
+static int grow_one_stripe(struct r5conf *conf, gfp_t gfp)
 {
         struct stripe_head *sh;
         sh = kmem_cache_zalloc(conf->slab_cache, gfp);
@@ -1979,7 +1979,8 @@ static int grow_one_stripe(struct r5conf *conf, int hash, gfp_t gfp)
                 kmem_cache_free(conf->slab_cache, sh);
                 return 0;
         }
-        sh->hash_lock_index = hash;
+        sh->hash_lock_index =
+                conf->max_nr_stripes % NR_STRIPE_HASH_LOCKS;
         /* we just created an active stripe so... */
         atomic_set(&sh->count, 1);
         atomic_inc(&conf->active_stripes);
@@ -1989,6 +1990,7 @@ static int grow_one_stripe(struct r5conf *conf, int hash, gfp_t gfp)
         INIT_LIST_HEAD(&sh->batch_list);
         sh->batch_head = NULL;
         release_stripe(sh);
+        conf->max_nr_stripes++;
         return 1;
 }
 
@@ -1996,7 +1998,6 @@ static int grow_stripes(struct r5conf *conf, int num)
 {
         struct kmem_cache *sc;
         int devs = max(conf->raid_disks, conf->previous_raid_disks);
-        int hash;
 
         if (conf->mddev->gendisk)
                 sprintf(conf->cache_name[0],
@@ -2014,13 +2015,10 @@ static int grow_stripes(struct r5conf *conf, int num)
                 return 1;
         conf->slab_cache = sc;
         conf->pool_size = devs;
-        hash = conf->max_nr_stripes % NR_STRIPE_HASH_LOCKS;
-        while (num--) {
-                if (!grow_one_stripe(conf, hash, GFP_KERNEL))
+        while (num--)
+                if (!grow_one_stripe(conf, GFP_KERNEL))
                         return 1;
-                conf->max_nr_stripes++;
-                hash = (hash + 1) % NR_STRIPE_HASH_LOCKS;
-        }
+
         return 0;
 }
 
@@ -2210,9 +2208,10 @@ static int resize_stripes(struct r5conf *conf, int newsize)
         return err;
 }
 
-static int drop_one_stripe(struct r5conf *conf, int hash)
+static int drop_one_stripe(struct r5conf *conf)
 {
         struct stripe_head *sh;
+        int hash = (conf->max_nr_stripes - 1) % NR_STRIPE_HASH_LOCKS;
 
         spin_lock_irq(conf->hash_locks + hash);
         sh = get_free_stripe(conf, hash);
@@ -2223,15 +2222,15 @@ static int drop_one_stripe(struct r5conf *conf, int hash)
         shrink_buffers(sh);
         kmem_cache_free(conf->slab_cache, sh);
         atomic_dec(&conf->active_stripes);
+        conf->max_nr_stripes--;
         return 1;
 }
 
 static void shrink_stripes(struct r5conf *conf)
 {
-        int hash;
-        for (hash = 0; hash < NR_STRIPE_HASH_LOCKS; hash++)
-                while (drop_one_stripe(conf, hash))
-                        ;
+        while (conf->max_nr_stripes &&
+               drop_one_stripe(conf))
+                ;
 
         if (conf->slab_cache)
                 kmem_cache_destroy(conf->slab_cache);
@@ -5822,30 +5821,22 @@ raid5_set_cache_size(struct mddev *mddev, int size)
 {
         struct r5conf *conf = mddev->private;
         int err;
-        int hash;
 
         if (size <= 16 || size > 32768)
                 return -EINVAL;
-        hash = (conf->max_nr_stripes - 1) % NR_STRIPE_HASH_LOCKS;
-        while (size < conf->max_nr_stripes) {
-                if (drop_one_stripe(conf, hash))
-                        conf->max_nr_stripes--;
-                else
-                        break;
-                hash--;
-                if (hash < 0)
-                        hash = NR_STRIPE_HASH_LOCKS - 1;
-        }
+
+        while (size < conf->max_nr_stripes &&
+               drop_one_stripe(conf))
+                ;
+
         err = md_allow_write(mddev);
         if (err)
                 return err;
-        hash = conf->max_nr_stripes % NR_STRIPE_HASH_LOCKS;
-        while (size > conf->max_nr_stripes) {
-                if (grow_one_stripe(conf, hash, GFP_KERNEL))
-                        conf->max_nr_stripes++;
-                else break;
-                hash = (hash + 1) % NR_STRIPE_HASH_LOCKS;
-        }
+
+        while (size > conf->max_nr_stripes)
+                if (!grow_one_stripe(conf, GFP_KERNEL))
+                        break;
+
         return 0;
 }
 EXPORT_SYMBOL(raid5_set_cache_size);
@@ -6451,7 +6442,7 @@ static struct r5conf *setup_conf(struct mddev *mddev)
                 conf->prev_algo = mddev->layout;
         }
 
-        memory = conf->max_nr_stripes * (sizeof(struct stripe_head) +
+        memory = NR_STRIPES * (sizeof(struct stripe_head) +
                  max_disks * ((sizeof(struct bio) + PAGE_SIZE))) / 1024;
         atomic_set(&conf->empty_inactive_list_nr, NR_STRIPE_HASH_LOCKS);
         if (grow_stripes(conf, NR_STRIPES)) {