block, cfq: misc updates to cfq_io_context

Make the following changes to prepare for ioc/cic management cleanup.

* Add cic->q so that ioc can determine the associated queue without
  querying cfq.  This will eventually replace ->key.

* Factor out cfq_release_cic() from cic_free_func().  This function
  assumes that the caller handled locking.

* Rename __cfq_exit_single_io_context() to cfq_exit_cic() and make it
  take only @cic.

* Restructure cfq_cic_link() for future updates.

This patch doesn't introduce any functional changes.

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

2 files changed, 33 insertions, 26 deletions

diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index d42d89ccce1b..a612ca65f371 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -2709,21 +2709,26 @@ static void cfq_cic_free(struct cfq_io_context *cic)
         call_rcu(&cic->rcu_head, cfq_cic_free_rcu);
 }
 
-static void cic_free_func(struct io_context *ioc, struct cfq_io_context *cic)
+static void cfq_release_cic(struct cfq_io_context *cic)
 {
-        unsigned long flags;
+        struct io_context *ioc = cic->ioc;
         unsigned long dead_key = (unsigned long) cic->key;
 
         BUG_ON(!(dead_key & CIC_DEAD_KEY));
-
-        spin_lock_irqsave(&ioc->lock, flags);
         radix_tree_delete(&ioc->radix_root, dead_key >> CIC_DEAD_INDEX_SHIFT);
         hlist_del_rcu(&cic->cic_list);
-        spin_unlock_irqrestore(&ioc->lock, flags);
-
         cfq_cic_free(cic);
 }
 
+static void cic_free_func(struct io_context *ioc, struct cfq_io_context *cic)
+{
+        unsigned long flags;
+
+        spin_lock_irqsave(&ioc->lock, flags);
+        cfq_release_cic(cic);
+        spin_unlock_irqrestore(&ioc->lock, flags);
+}
+
 /*
  * Must be called with rcu_read_lock() held or preemption otherwise disabled.
  * Only two callers of this - ->dtor() which is called with the rcu_read_lock(),
@@ -2773,9 +2778,9 @@ static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
         cfq_put_queue(cfqq);
 }
 
-static void __cfq_exit_single_io_context(struct cfq_data *cfqd,
-                                         struct cfq_io_context *cic)
+static void cfq_exit_cic(struct cfq_io_context *cic)
 {
+        struct cfq_data *cfqd = cic_to_cfqd(cic);
         struct io_context *ioc = cic->ioc;
 
         list_del_init(&cic->queue_list);
@@ -2823,7 +2828,7 @@ static void cfq_exit_single_io_context(struct io_context *ioc,
                  */
                 smp_read_barrier_depends();
                 if (cic->key == cfqd)
-                        __cfq_exit_single_io_context(cfqd, cic);
+                        cfq_exit_cic(cic);
 
                 spin_unlock_irqrestore(q->queue_lock, flags);
         }
@@ -3161,28 +3166,29 @@ static int cfq_cic_link(struct cfq_data *cfqd, struct io_context *ioc,
         int ret;
 
         ret = radix_tree_preload(gfp_mask);
-        if (!ret) {
-                cic->ioc = ioc;
-                cic->key = cfqd;
+        if (ret)
+                goto out;
 
-                spin_lock_irqsave(&ioc->lock, flags);
-                ret = radix_tree_insert(&ioc->radix_root, cfqd->queue->id, cic);
-                if (!ret)
-                        hlist_add_head_rcu(&cic->cic_list, &ioc->cic_list);
-                spin_unlock_irqrestore(&ioc->lock, flags);
+        cic->ioc = ioc;
+        cic->key = cfqd;
+        cic->q = cfqd->queue;
+
+        spin_lock_irqsave(&ioc->lock, flags);
+        ret = radix_tree_insert(&ioc->radix_root, cfqd->queue->id, cic);
+        if (!ret)
+                hlist_add_head_rcu(&cic->cic_list, &ioc->cic_list);
+        spin_unlock_irqrestore(&ioc->lock, flags);
 
-                radix_tree_preload_end();
+        radix_tree_preload_end();
 
-                if (!ret) {
-                        spin_lock_irqsave(cfqd->queue->queue_lock, flags);
-                        list_add(&cic->queue_list, &cfqd->cic_list);
-                        spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
-                }
+        if (!ret) {
+                spin_lock_irqsave(cfqd->queue->queue_lock, flags);
+                list_add(&cic->queue_list, &cfqd->cic_list);
+                spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
         }
-
+out:
         if (ret)
                 printk(KERN_ERR "cfq: cic link failed!\n");
-
         return ret;
 }
 
@@ -3922,7 +3928,7 @@ static void cfq_exit_queue(struct elevator_queue *e)
                                                         struct cfq_io_context,
                                                         queue_list);
 
-                __cfq_exit_single_io_context(cfqd, cic);
+                cfq_exit_cic(cic);
         }
 
         cfq_put_async_queues(cfqd);
diff --git a/include/linux/iocontext.h b/include/linux/iocontext.h
index 28bb621ef5a2..079aea8fd8a8 100644
--- a/include/linux/iocontext.h
+++ b/include/linux/iocontext.h
@@ -15,6 +15,7 @@ struct cfq_ttime {
 
 struct cfq_io_context {
         void *key;
+        struct request_queue *q;
 
         struct cfq_queue *cfqq[2];