block, cfq: move io_cq lookup to blk-ioc.c

Now that all io_cq related data structures are in block core layer,
io_cq lookup can be moved from cfq-iosched.c to blk-ioc.c.

Lookup logic from cfq_cic_lookup() is moved to ioc_lookup_icq() with
parameter return type changes (cfqd -> request_queue, cfq_io_cq ->
io_cq) and cfq_cic_lookup() becomes thin wrapper around
cfq_cic_lookup().

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

3 files changed, 45 insertions, 40 deletions

diff --git a/block/blk-ioc.c b/block/blk-ioc.c
index dc5e69d335a0..87ecc98b8ade 100644
--- a/block/blk-ioc.c
+++ b/block/blk-ioc.c
@@ -266,6 +266,42 @@ struct io_context *get_task_io_context(struct task_struct *task,
 }
 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.
+         */
+        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);
+
 void ioc_set_changed(struct io_context *ioc, int which)
 {
         struct io_cq *icq;
diff --git a/block/blk.h b/block/blk.h
index 4943770e0792..3c510a4b5054 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -199,6 +199,7 @@ static inline int blk_do_io_stat(struct request *rq)
  * Internal io_context interface
  */
 void get_io_context(struct io_context *ioc);
+struct io_cq *ioc_lookup_icq(struct io_context *ioc, struct request_queue *q);
 
 void create_io_context_slowpath(struct task_struct *task, gfp_t gfp_mask,
                                 int node);
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 9bc5ecc1b336..048fa699adf9 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -468,7 +468,6 @@ static inline int cfqg_busy_async_queues(struct cfq_data *cfqd,
 static void cfq_dispatch_insert(struct request_queue *, struct request *);
 static struct cfq_queue *cfq_get_queue(struct cfq_data *, bool,
                                        struct io_context *, gfp_t);
-static struct cfq_io_cq *cfq_cic_lookup(struct cfq_data *, struct io_context *);
 
 static inline struct cfq_io_cq *icq_to_cic(struct io_cq *icq)
 {
@@ -476,6 +475,14 @@ static inline struct cfq_io_cq *icq_to_cic(struct io_cq *icq)
         return container_of(icq, struct cfq_io_cq, icq);
 }
 
+static inline struct cfq_io_cq *cfq_cic_lookup(struct cfq_data *cfqd,
+                                               struct io_context *ioc)
+{
+        if (ioc)
+                return icq_to_cic(ioc_lookup_icq(ioc, cfqd->queue));
+        return NULL;
+}
+
 static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_cq *cic, bool is_sync)
 {
         return cic->cfqq[is_sync];
@@ -2971,45 +2978,6 @@ cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct io_context *ioc,
 }
 
 /**
- * cfq_cic_lookup - lookup cfq_io_cq
- * @cfqd: the associated cfq_data
- * @ioc: the associated io_context
- *
- * Look up cfq_io_cq associated with @cfqd - @ioc pair.  Must be called
- * with queue_lock held.
- */
-static struct cfq_io_cq *
-cfq_cic_lookup(struct cfq_data *cfqd, struct io_context *ioc)
-{
-        struct request_queue *q = cfqd->queue;
-        struct io_cq *icq;
-
-        lockdep_assert_held(cfqd->queue->queue_lock);
-        if (unlikely(!ioc))
-                return NULL;
-
-        /*
-         * 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.
-         */
-        rcu_read_lock();
-        icq = rcu_dereference(ioc->icq_hint);
-        if (icq && icq->q == q)
-                goto out;
-
-        icq = radix_tree_lookup(&ioc->icq_tree, cfqd->queue->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_to_cic(icq);
-}
-
-/**
  * cfq_create_cic - create and link a cfq_io_cq
  * @cfqd: cfqd of interest
  * @gfp_mask: allocation mask