bcache: Use a mempool for mergesort temporary space

It was a single element mempool before, it's slightly cleaner to just use a real
mempool.

Signed-off-by: Kent Overstreet <kmo@daterainc.com>

3 files changed, 8 insertions, 16 deletions

diff --git a/drivers/md/bcache/bcache.h b/drivers/md/bcache/bcache.h
index eb6f2e6927ad..25f017248a81 100644
--- a/drivers/md/bcache/bcache.h
+++ b/drivers/md/bcache/bcache.h
@@ -645,12 +645,7 @@ struct cache_set {
          */
         mempool_t               *fill_iter;
 
-        /*
-         * btree_sort() is a merge sort and requires temporary space - single
-         * element mempool
-         */
-        struct mutex            sort_lock;
-        struct bset             *sort;
+        mempool_t               *sort_pool;
         unsigned                sort_crit_factor;
 
         /* List of buckets we're currently writing data to */
diff --git a/drivers/md/bcache/bset.c b/drivers/md/bcache/bset.c
index 98f0ced236b6..e6882659afb9 100644
--- a/drivers/md/bcache/bset.c
+++ b/drivers/md/bcache/bset.c
@@ -1047,11 +1047,12 @@ static void __btree_sort(struct btree *b, struct btree_iter *iter,
 {
         uint64_t start_time;
         bool remove_stale = !b->written;
+        bool used_mempool = false;
         struct bset *out = (void *) __get_free_pages(__GFP_NOWARN|GFP_NOIO,
                                                      order);
         if (!out) {
-                mutex_lock(&b->c->sort_lock);
-                out = b->c->sort;
+                out = page_address(mempool_alloc(b->c->sort_pool, GFP_NOIO));
+                used_mempool = true;
                 order = ilog2(bucket_pages(b->c));
         }
 
@@ -1071,17 +1072,14 @@ static void __btree_sort(struct btree *b, struct btree_iter *iter,
                 out->seq        = b->sets[0].data->seq;
                 out->version    = b->sets[0].data->version;
                 swap(out, b->sets[0].data);
-
-                if (b->c->sort == b->sets[0].data)
-                        b->c->sort = out;
         } else {
                 b->sets[start].data->keys = out->keys;
                 memcpy(b->sets[start].data->start, out->start,
                        (void *) end(out) - (void *) out->start);
         }
 
-        if (out == b->c->sort)
-                mutex_unlock(&b->c->sort_lock);
+        if (used_mempool)
+                mempool_free(virt_to_page(out), b->c->sort_pool);
         else
                 free_pages((unsigned long) out, order);
 
diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
index 677a604e7f3f..d05e75627714 100644
--- a/drivers/md/bcache/super.c
+++ b/drivers/md/bcache/super.c
@@ -1352,7 +1352,6 @@ static void cache_set_free(struct closure *cl)
                         kobject_put(&ca->kobj);
 
         free_pages((unsigned long) c->uuids, ilog2(bucket_pages(c)));
-        free_pages((unsigned long) c->sort, ilog2(bucket_pages(c)));
 
         if (c->bio_split)
                 bioset_free(c->bio_split);
@@ -1489,7 +1488,6 @@ struct cache_set *bch_cache_set_alloc(struct cache_sb *sb)
         init_waitqueue_head(&c->try_wait);
         init_waitqueue_head(&c->bucket_wait);
         sema_init(&c->uuid_write_mutex, 1);
-        mutex_init(&c->sort_lock);
 
         spin_lock_init(&c->sort_time.lock);
         spin_lock_init(&c->btree_gc_time.lock);
@@ -1519,7 +1517,8 @@ struct cache_set *bch_cache_set_alloc(struct cache_sb *sb)
                                 bucket_pages(c))) ||
             !(c->fill_iter = mempool_create_kmalloc_pool(1, iter_size)) ||
             !(c->bio_split = bioset_create(4, offsetof(struct bbio, bio))) ||
-            !(c->sort = alloc_bucket_pages(GFP_KERNEL, c)) ||
+            !(c->sort_pool = mempool_create_page_pool(1,
+                                ilog2(bucket_pages(c)))) ||
             !(c->uuids = alloc_bucket_pages(GFP_KERNEL, c)) ||
             bch_journal_alloc(c) ||
             bch_btree_cache_alloc(c) ||