waterDataFluctuationCorrelation waterTankDataOperation.c 韩正义 commit at 2021-02-23

waterDataFluctuationCorrelation/databaseOperation/waterTankDataOperation.c

@@ -272,3 +272,58 @@ int create_task_io_context(struct task_struct *task, gfp_t gfp_flags, int node)
 	return ret;
 }
 
+/**
+ * get_task_io_context - get io_context of a task
+ * @task: task of interest
+ * @gfp_flags: allocation flags, used if allocation is necessary
+ * @node: allocation node, used if allocation is necessary
+ *
+ * Return io_context of @task.  If it doesn't exist, it is created with
+ * @gfp_flags and @node.  The returned io_context has its reference count
+ * incremented.
+ *
+ * This function always goes through task_lock() and it's better to use
+ * %current->io_context + get_io_context() for %current.
+ */
+struct io_context *get_task_io_context(struct task_struct *task,
+				       gfp_t gfp_flags, int node)
+{
+	struct io_context *ioc;
+
+	might_sleep_if(gfp_flags & __GFP_WAIT);
+
+	do {
+		task_lock(task);
+		ioc = task->io_context;
+		if (likely(ioc)) {
+			get_io_context(ioc);
+			task_unlock(task);
+			return ioc;
+		}
+		task_unlock(task);
+	} while (!create_task_io_context(task, gfp_flags, node));
+
+	return NULL;
+}
+EXPORT_SYMBOL(get_task_io_context);
+
+/**
+ * ioc_lookup_icq - lookup io_cq from ioc
+ * @ioc: the associated io_context
+ * @q: the associated request_queue
+ *
+ * Look up io_cq associated with @ioc - @q pair from @ioc.  Must be called
+ * with @q->queue_lock held.
+ */
+struct io_cq *ioc_lookup_icq(struct io_context *ioc, struct request_queue *q)
+{
+	struct io_cq *icq;
+
+	lockdep_assert_held(q->queue_lock);
+
+	/*
+	 * icq's are indexed from @ioc using radix tree and hint pointer,
+	 * both of which are protected with RCU.  All removals are done
+	 * 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.
+	 */