X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=include%2Flinux%2Fiocontext.h;h=df38db2ef45bbf50def2b9de1970225c8a76c6de;hb=804ce9866d56130032c9c8afc90a1297b7deed56;hp=1a30180630343dabd49aa886fc7621964912afdf;hpb=4b3451ad1313134821ad13b6fe821d0b4409aa18;p=firefly-linux-kernel-4.4.55.git

diff --git a/include/linux/iocontext.h b/include/linux/iocontext.h
index 1a3018063034..df38db2ef45b 100644
--- a/include/linux/iocontext.h
+++ b/include/linux/iocontext.h
@@ -6,11 +6,7 @@
 #include <linux/workqueue.h>
 
 enum {
-	ICQ_IOPRIO_CHANGED	= 1 << 0,
-	ICQ_CGROUP_CHANGED	= 1 << 1,
 	ICQ_EXITED		= 1 << 2,
-
-	ICQ_CHANGED_MASK	= ICQ_IOPRIO_CHANGED | ICQ_CGROUP_CHANGED,
 };
 
 /*
@@ -100,6 +96,7 @@ struct io_cq {
  */
 struct io_context {
 	atomic_long_t refcount;
+	atomic_t active_ref;
 	atomic_t nr_tasks;
 
 	/* all the fields below are protected by this lock */
@@ -120,29 +117,37 @@ struct io_context {
 	struct work_struct release_work;
 };
 
-static inline struct io_context *ioc_task_link(struct io_context *ioc)
+/**
+ * get_io_context_active - get active reference on ioc
+ * @ioc: ioc of interest
+ *
+ * Only iocs with active reference can issue new IOs.  This function
+ * acquires an active reference on @ioc.  The caller must already have an
+ * active reference on @ioc.
+ */
+static inline void get_io_context_active(struct io_context *ioc)
 {
-	/*
-	 * if ref count is zero, don't allow sharing (ioc is going away, it's
-	 * a race).
-	 */
-	if (ioc && atomic_long_inc_not_zero(&ioc->refcount)) {
-		atomic_inc(&ioc->nr_tasks);
-		return ioc;
-	}
+	WARN_ON_ONCE(atomic_long_read(&ioc->refcount) <= 0);
+	WARN_ON_ONCE(atomic_read(&ioc->active_ref) <= 0);
+	atomic_long_inc(&ioc->refcount);
+	atomic_inc(&ioc->active_ref);
+}
+
+static inline void ioc_task_link(struct io_context *ioc)
+{
+	get_io_context_active(ioc);
 
-	return NULL;
+	WARN_ON_ONCE(atomic_read(&ioc->nr_tasks) <= 0);
+	atomic_inc(&ioc->nr_tasks);
 }
 
 struct task_struct;
 #ifdef CONFIG_BLOCK
 void put_io_context(struct io_context *ioc);
+void put_io_context_active(struct io_context *ioc);
 void exit_io_context(struct task_struct *task);
 struct io_context *get_task_io_context(struct task_struct *task,
 				       gfp_t gfp_flags, int node);
-void ioc_ioprio_changed(struct io_context *ioc, int ioprio);
-void ioc_cgroup_changed(struct io_context *ioc);
-unsigned int icq_get_changed(struct io_cq *icq);
 #else
 struct io_context;
 static inline void put_io_context(struct io_context *ioc) { }