bcache: Don't bother with bucket refcount for btree node allocations

The bucket refcount (dropped with bkey_put()) is only needed to prevent
the newly allocated bucket from being garbage collected until we've
added a pointer to it somewhere. But for btree node allocations, the
fact that we have btree nodes locked is enough to guard against races
with garbage collection.

Eventually the per bucket refcount is going to be replaced with
something specific to bch_alloc_sectors().
Signed-off-by: Kent Overstreet <kmo@daterainc.com>

drivers/md/bcache/alloc.c

@@ -472,7 +472,7 @@ int __bch_bucket_alloc_set(struct cache_set *c, unsigned watermark,
 	return 0;
 err:
 	bch_bucket_free(c, k);
-	__bkey_put(c, k);
+	bkey_put(c, k);
 	return -1;
 }
 
@@ -588,7 +588,7 @@ bool bch_alloc_sectors(struct cache_set *c, struct bkey *k, unsigned sectors,
 	 * didn't use it, drop the refcount bch_bucket_alloc_set() took:
 	 */
 	if (KEY_PTRS(&alloc.key))
-		__bkey_put(c, &alloc.key);
+		bkey_put(c, &alloc.key);
 
 	for (i = 0; i < KEY_PTRS(&b->key); i++)
 		EBUG_ON(ptr_stale(c, &b->key, i));

drivers/md/bcache/btree.c

@@ -180,7 +180,7 @@ static inline bool should_split(struct btree *b)
 
 /* Btree key manipulation */
 
-void __bkey_put(struct cache_set *c, struct bkey *k)
+void bkey_put(struct cache_set *c, struct bkey *k)
 {
 	unsigned i;
 
@@ -189,12 +189,6 @@ void __bkey_put(struct cache_set *c, struct bkey *k)
 			atomic_dec_bug(&PTR_BUCKET(c, k, i)->pin);
 }
 
-static void bkey_put(struct cache_set *c, struct bkey *k, int level)
-{
-	if ((level && KEY_OFFSET(k)) || !level)
-		__bkey_put(c, k);
-}
-
 /* Btree IO */
 
 static uint64_t btree_csum_set(struct btree *b, struct bset *i)
@@ -1068,6 +1062,7 @@ struct btree *bch_btree_node_alloc(struct cache_set *c, int level)
 	if (__bch_bucket_alloc_set(c, WATERMARK_METADATA, &k.key, 1, true))
 		goto err;
 
+	bkey_put(c, &k.key);
 	SET_KEY_SIZE(&k.key, c->btree_pages * PAGE_SECTORS);
 
 	b = mca_alloc(c, &k.key, level);
@@ -1077,7 +1072,6 @@ struct btree *bch_btree_node_alloc(struct cache_set *c, int level)
 	if (!b) {
 		cache_bug(c,
 			"Tried to allocate bucket that was in btree cache");
-		__bkey_put(c, &k.key);
 		goto retry;
 	}
 
@@ -1090,7 +1084,6 @@ struct btree *bch_btree_node_alloc(struct cache_set *c, int level)
 	return b;
 err_free:
 	bch_bucket_free(c, &k.key);
-	__bkey_put(c, &k.key);
 err:
 	mutex_unlock(&c->bucket_lock);
 
@@ -1217,7 +1210,6 @@ static struct btree *btree_gc_alloc(struct btree *b, struct bkey *k)
 
 	if (!IS_ERR_OR_NULL(n)) {
 		swap(b, n);
-		__bkey_put(b->c, &b->key);
 
 		memcpy(k->ptr, b->key.ptr,
 		       sizeof(uint64_t) * KEY_PTRS(&b->key));
@@ -1932,19 +1924,12 @@ static bool bch_btree_insert_keys(struct btree *b, struct btree_op *op,
 			break;
 
 		if (bkey_cmp(k, &b->key) <= 0) {
-			bkey_put(b->c, k, b->level);
+			if (!b->level)
+				bkey_put(b->c, k);
 
 			ret |= btree_insert_key(b, op, k, replace_key);
 			bch_keylist_pop_front(insert_keys);
 		} else if (bkey_cmp(&START_KEY(k), &b->key) < 0) {
-#if 0
-			if (replace_key) {
-				bkey_put(b->c, k, b->level);
-				bch_keylist_pop_front(insert_keys);
-				op->insert_collision = true;
-				break;
-			}
-#endif
 			BKEY_PADDED(key) temp;
 			bkey_copy(&temp.key, insert_keys->keys);
 
@@ -2071,11 +2056,9 @@ static int btree_split(struct btree *b, struct btree_op *op,
 
 	return 0;
 err_free2:
-	__bkey_put(n2->c, &n2->key);
 	btree_node_free(n2);
 	rw_unlock(true, n2);
 err_free1:
-	__bkey_put(n1->c, &n1->key);
 	btree_node_free(n1);
 	rw_unlock(true, n1);
 err:
@@ -2225,7 +2208,7 @@ int bch_btree_insert(struct cache_set *c, struct keylist *keys,
 		pr_err("error %i", ret);
 
 		while ((k = bch_keylist_pop(keys)))
-			bkey_put(c, k, 0);
+			bkey_put(c, k);
 	} else if (op.op.insert_collision)
 		ret = -ESRCH;
 
@@ -2251,7 +2234,6 @@ void bch_btree_set_root(struct btree *b)
 	mutex_unlock(&b->c->bucket_lock);
 
 	b->c->root = b;
-	__bkey_put(b->c, &b->key);
 
 	bch_journal_meta(b->c, &cl);
 	closure_sync(&cl);

drivers/md/bcache/btree.h

@@ -216,7 +216,7 @@ static inline struct bkey *bch_btree_iter_init(struct btree *b,
 	return __bch_btree_iter_init(b, iter, search, b->sets);
 }
 
-void __bkey_put(struct cache_set *c, struct bkey *k);
+void bkey_put(struct cache_set *c, struct bkey *k);
 
 /* Looping macros */
 

drivers/md/bcache/super.c

@@ -426,7 +426,7 @@ static int __uuid_write(struct cache_set *c)
 	closure_sync(&cl);
 
 	bkey_copy(&c->uuid_bucket, &k.key);
-	__bkey_put(c, &k.key);
+	bkey_put(c, &k.key);
 	return 0;
 }