waterDataFluctuationCorrelation waterTankDataOperation.c 韩正义 commit at 2021-03-26

waterDataFluctuationCorrelation/databaseOperation/waterTankDataOperation.c

@@ -327,3 +327,82 @@ struct io_cq *ioc_lookup_icq(struct io_context *ioc, struct request_queue *q)
 	 * holding both q and ioc locks, and we're holding q lock - if we
 	 * find a icq which points to us, it's guaranteed to be valid.
 	 */
+	rcu_read_lock();
+	icq = rcu_dereference(ioc->icq_hint);
+	if (icq && icq->q == q)
+		goto out;
+
+	icq = radix_tree_lookup(&ioc->icq_tree, q->id);
+	if (icq && icq->q == q)
+		rcu_assign_pointer(ioc->icq_hint, icq);	/* allowed to race */
+	else
+		icq = NULL;
+out:
+	rcu_read_unlock();
+	return icq;
+}
+EXPORT_SYMBOL(ioc_lookup_icq);
+
+/**
+ * ioc_create_icq - create and link io_cq
+ * @ioc: io_context of interest
+ * @q: request_queue of interest
+ * @gfp_mask: allocation mask
+ *
+ * Make sure io_cq linking @ioc and @q exists.  If icq doesn't exist, they
+ * will be created using @gfp_mask.
+ *
+ * The caller is responsible for ensuring @ioc won't go away and @q is
+ * alive and will stay alive until this function returns.
+ */
+struct io_cq *ioc_create_icq(struct io_context *ioc, struct request_queue *q,
+			     gfp_t gfp_mask)
+{
+	struct elevator_type *et = q->elevator->type;
+	struct io_cq *icq;
+
+	/* allocate stuff */
+	icq = kmem_cache_alloc_node(et->icq_cache, gfp_mask | __GFP_ZERO,
+				    q->node);
+	if (!icq)
+		return NULL;
+
+	if (radix_tree_preload(gfp_mask) < 0) {
+		kmem_cache_free(et->icq_cache, icq);
+		return NULL;
+	}
+
+	icq->ioc = ioc;
+	icq->q = q;
+	INIT_LIST_HEAD(&icq->q_node);
+	INIT_HLIST_NODE(&icq->ioc_node);
+
+	/* lock both q and ioc and try to link @icq */
+	spin_lock_irq(q->queue_lock);
+	spin_lock(&ioc->lock);
+
+	if (likely(!radix_tree_insert(&ioc->icq_tree, q->id, icq))) {
+		hlist_add_head(&icq->ioc_node, &ioc->icq_list);
+		list_add(&icq->q_node, &q->icq_list);
+		if (et->ops.elevator_init_icq_fn)
+			et->ops.elevator_init_icq_fn(icq);
+	} else {
+		kmem_cache_free(et->icq_cache, icq);
+		icq = ioc_lookup_icq(ioc, q);
+		if (!icq)
+			printk(KERN_ERR "cfq: icq link failed!\n");
+	}
+
+	spin_unlock(&ioc->lock);
+	spin_unlock_irq(q->queue_lock);
+	radix_tree_preload_end();
+	return icq;
+}
+
+static int __init blk_ioc_init(void)
+{
+	iocontext_cachep = kmem_cache_create("blkdev_ioc",
+			sizeof(struct io_context), 0, SLAB_PANIC, NULL);
+	return 0;
+}
+subsys_initcall(blk_ioc_init);