[RFC][patch 9/11][CFQ-cgroup] Search cfq_data when not connected

["Satoshi UCHIDA" <s-uchida@ap.jp.nec.com>]

This patch is possible to select a cfq_data corresponding group with task.
This is used when merge, merge check, queue check and queue setting.

The new cfq optional operations:
The "cfq_search_data_fn" defines a function that selects a correct cfq_data when
cfq_queue and requests are not connected yet. 

   Signed-off-by: Satoshi UCHIDA <uchida@ap.jp.nec.com>

diff --git a/block/cfq-cgroup.c b/block/cfq-cgroup.c
index 4110ab7..568e433 100644
--- a/block/cfq-cgroup.c
+++ b/block/cfq-cgroup.c
@@ -35,6 +35,12 @@ static inline struct cfq_cgroup *cgroup_to_cfq_cgroup(struct cgroup *cont)
 			    struct cfq_cgroup, css);
 }
 
+static inline struct cfq_cgroup *task_to_cfq_cgroup(struct task_struct *tsk)
+{
+	return container_of(task_subsys_state(tsk, cfq_cgroup_subsys_id),
+			    struct cfq_cgroup, css);
+}
+
 /*
  * Add device or cgroup data functions.
  */
@@ -392,6 +398,32 @@ struct cgroup_subsys cfq_cgroup_subsys = {
 };
 
 
+struct cfq_data *cfq_cgroup_search_data(void *data,
+					struct task_struct *tsk)
+{
+	struct cfq_data *cfqd = (struct cfq_data *)data;
+	struct cfq_meta_data *cfqmd = cfqd->cfqmd;
+	struct cfq_cgroup *cont = task_to_cfq_cgroup(tsk);
+	struct rb_node *p = cont->sibling_tree.rb_node;
+
+	while (p) {
+		struct cfq_data *__cfqd;
+		__cfqd = rb_entry(p, struct cfq_data, group_node);
+
+
+		if (cfqmd < __cfqd->cfqmd) {
+			p = p->rb_left;
+		} else if (cfqmd > __cfqd->cfqmd) {
+			p = p->rb_right;
+		} else {
+			return __cfqd;
+		}
+	}
+
+	return NULL;
+}
+
+
 struct cfq_ops opt = {
 	.cfq_init_queue_fn = __cfq_cgroup_init_queue,
 	.cfq_exit_queue_fn = __cfq_cgroup_exit_data,
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index b1757bc..3aa320a 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -623,6 +623,9 @@ static int cfq_merge(struct request_queue *q, struct request **req,
 	struct cfq_data *cfqd = q->elevator->elevator_data;
 	struct request *__rq;
 
+	if (opt.cfq_search_data_fn)
+		cfqd = opt.cfq_search_data_fn(cfqd, current);
+
 	__rq = cfq_find_rq_fmerge(cfqd, bio);
 	if (__rq && elv_rq_merge_ok(__rq, bio)) {
 		*req = __rq;
@@ -663,6 +666,9 @@ static int cfq_allow_merge(struct request_queue *q, struct request *rq,
 	struct cfq_io_context *cic;
 	struct cfq_queue *cfqq;
 
+	if (opt.cfq_search_data_fn)
+		cfqd = opt.cfq_search_data_fn(cfqd, current);
+
 	/*
 	 * Disallow merge of a sync bio into an async request.
 	 */
@@ -1832,6 +1838,9 @@ static int cfq_may_queue(struct request_queue *q, int rw)
 	struct cfq_io_context *cic;
 	struct cfq_queue *cfqq;
 
+	if (opt.cfq_search_data_fn)
+		cfqd = opt.cfq_search_data_fn(cfqd, current);
+
 	/*
 	 * don't force setup of a queue from here, as a call to may_queue
 	 * does not necessarily imply that a request actually will be queued.
@@ -1888,6 +1897,9 @@ cfq_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask)
 	struct cfq_queue *cfqq;
 	unsigned long flags;
 
+	if (opt.cfq_search_data_fn)
+		cfqd = opt.cfq_search_data_fn(cfqd, current);
+	
 	might_sleep_if(gfp_mask & __GFP_WAIT);
 
 	cic = cfq_get_io_context(cfqd, gfp_mask);
diff --git a/include/linux/cfq-iosched.h b/include/linux/cfq-iosched.h
index 93256ce..a382953 100644
--- a/include/linux/cfq-iosched.h
+++ b/include/linux/cfq-iosched.h
@@ -131,11 +131,13 @@ static inline struct request_queue * __cfq_container_of_queue(struct work_struct
 
 typedef struct cfq_data *(cfq_init_queue_fn)(struct request_queue *, void *);
 typedef void (cfq_exit_queue_fn)(struct cfq_data *);
+typedef struct cfq_data *(cfq_search_data_fn)(void *, struct task_struct *);
 
 struct cfq_ops
 {
 	cfq_init_queue_fn *cfq_init_queue_fn;
 	cfq_exit_queue_fn *cfq_exit_queue_fn;
+	cfq_search_data_fn *cfq_search_data_fn;
 };
 
 extern struct cfq_ops opt;