block, cfq: reorganize cfq_io_context into generic and cfq specific parts

Currently io_context and cfq logics are mixed without clear boundary.
Most of io_context is independent from cfq but cfq_io_context handling
logic is dispersed between generic ioc code and cfq.

cfq_io_context represents association between an io_context and a
request_queue, which is a concept useful outside of cfq, but it also
contains fields which are useful only to cfq.

This patch takes out generic part and put it into io_cq (io
context-queue) and the rest into cfq_io_cq (cic moniker remains the
same) which contains io_cq.  The following changes are made together.

* cfq_ttime and cfq_io_cq now live in cfq-iosched.c.

* All related fields, functions and constants are renamed accordingly.

* ioc->ioc_data is now "struct io_cq *" instead of "void *" and
  renamed to icq_hint.

This prepares for io_context API cleanup.  Documentation is currently
sparse.  It will be added later.

Changes in this patch are mechanical and don't cause functional
change.

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

2 files changed, 161 insertions, 145 deletions

diff --git a/block/blk-ioc.c b/block/blk-ioc.c
index e23c797b4685..dc5e69d335a0 100644
--- a/block/blk-ioc.c
+++ b/block/blk-ioc.c
@@ -46,7 +46,7 @@ EXPORT_SYMBOL(get_io_context);
 
 /*
  * Slow path for ioc release in put_io_context().  Performs double-lock
- * dancing to unlink all cic's and then frees ioc.
+ * dancing to unlink all icq's and then frees ioc.
  */
 static void ioc_release_fn(struct work_struct *work)
 {
@@ -56,11 +56,10 @@ static void ioc_release_fn(struct work_struct *work)
 
         spin_lock_irq(&ioc->lock);
 
-        while (!hlist_empty(&ioc->cic_list)) {
-                struct cfq_io_context *cic = hlist_entry(ioc->cic_list.first,
-                                                         struct cfq_io_context,
-                                                         cic_list);
-                struct request_queue *this_q = cic->q;
+        while (!hlist_empty(&ioc->icq_list)) {
+                struct io_cq *icq = hlist_entry(ioc->icq_list.first,
+                                                struct io_cq, ioc_node);
+                struct request_queue *this_q = icq->q;
 
                 if (this_q != last_q) {
                         /*
@@ -89,8 +88,8 @@ static void ioc_release_fn(struct work_struct *work)
                         continue;
                 }
                 ioc_release_depth_inc(this_q);
-                cic->exit(cic);
-                cic->release(cic);
+                icq->exit(icq);
+                icq->release(icq);
                 ioc_release_depth_dec(this_q);
         }
 
@@ -131,10 +130,10 @@ void put_io_context(struct io_context *ioc, struct request_queue *locked_q)
                 return;
 
         /*
-         * Destroy @ioc.  This is a bit messy because cic's are chained
+         * Destroy @ioc.  This is a bit messy because icq's are chained
          * from both ioc and queue, and ioc->lock nests inside queue_lock.
-         * The inner ioc->lock should be held to walk our cic_list and then
-         * for each cic the outer matching queue_lock should be grabbed.
+         * The inner ioc->lock should be held to walk our icq_list and then
+         * for each icq the outer matching queue_lock should be grabbed.
          * ie. We need to do reverse-order double lock dancing.
          *
          * Another twist is that we are often called with one of the
@@ -153,11 +152,10 @@ void put_io_context(struct io_context *ioc, struct request_queue *locked_q)
         spin_lock_irqsave_nested(&ioc->lock, flags,
                                  ioc_release_depth(locked_q));
 
-        while (!hlist_empty(&ioc->cic_list)) {
-                struct cfq_io_context *cic = hlist_entry(ioc->cic_list.first,
-                                                         struct cfq_io_context,
-                                                         cic_list);
-                struct request_queue *this_q = cic->q;
+        while (!hlist_empty(&ioc->icq_list)) {
+                struct io_cq *icq = hlist_entry(ioc->icq_list.first,
+                                                struct io_cq, ioc_node);
+                struct request_queue *this_q = icq->q;
 
                 if (this_q != last_q) {
                         if (last_q && last_q != locked_q)
@@ -170,8 +168,8 @@ void put_io_context(struct io_context *ioc, struct request_queue *locked_q)
                         continue;
                 }
                 ioc_release_depth_inc(this_q);
-                cic->exit(cic);
-                cic->release(cic);
+                icq->exit(icq);
+                icq->release(icq);
                 ioc_release_depth_dec(this_q);
         }
 
@@ -180,8 +178,8 @@ void put_io_context(struct io_context *ioc, struct request_queue *locked_q)
 
         spin_unlock_irqrestore(&ioc->lock, flags);
 
-        /* if no cic's left, we're done; otherwise, kick release_work */
-        if (hlist_empty(&ioc->cic_list))
+        /* if no icq is left, we're done; otherwise, kick release_work */
+        if (hlist_empty(&ioc->icq_list))
                 kmem_cache_free(iocontext_cachep, ioc);
         else
                 schedule_work(&ioc->release_work);
@@ -219,8 +217,8 @@ void create_io_context_slowpath(struct task_struct *task, gfp_t gfp_flags,
         atomic_long_set(&ioc->refcount, 1);
         atomic_set(&ioc->nr_tasks, 1);
         spin_lock_init(&ioc->lock);
-        INIT_RADIX_TREE(&ioc->radix_root, GFP_ATOMIC | __GFP_HIGH);
-        INIT_HLIST_HEAD(&ioc->cic_list);
+        INIT_RADIX_TREE(&ioc->icq_tree, GFP_ATOMIC | __GFP_HIGH);
+        INIT_HLIST_HEAD(&ioc->icq_list);
         INIT_WORK(&ioc->release_work, ioc_release_fn);
 
         /* try to install, somebody might already have beaten us to it */
@@ -270,11 +268,11 @@ EXPORT_SYMBOL(get_task_io_context);
 
 void ioc_set_changed(struct io_context *ioc, int which)
 {
-        struct cfq_io_context *cic;
+        struct io_cq *icq;
         struct hlist_node *n;
 
-        hlist_for_each_entry(cic, n, &ioc->cic_list, cic_list)
-                set_bit(which, &cic->changed);
+        hlist_for_each_entry(icq, n, &ioc->icq_list, ioc_node)
+                set_bit(which, &icq->changed);
 }
 
 /**
@@ -282,8 +280,8 @@ void ioc_set_changed(struct io_context *ioc, int which)
  * @ioc: io_context of interest
  * @ioprio: new ioprio
  *
- * @ioc's ioprio has changed to @ioprio.  Set %CIC_IOPRIO_CHANGED for all
- * cic's.  iosched is responsible for checking the bit and applying it on
+ * @ioc's ioprio has changed to @ioprio.  Set %ICQ_IOPRIO_CHANGED for all
+ * icq's.  iosched is responsible for checking the bit and applying it on
  * request issue path.
  */
 void ioc_ioprio_changed(struct io_context *ioc, int ioprio)
@@ -292,7 +290,7 @@ void ioc_ioprio_changed(struct io_context *ioc, int ioprio)
 
         spin_lock_irqsave(&ioc->lock, flags);
         ioc->ioprio = ioprio;
-        ioc_set_changed(ioc, CIC_IOPRIO_CHANGED);
+        ioc_set_changed(ioc, ICQ_IOPRIO_CHANGED);
         spin_unlock_irqrestore(&ioc->lock, flags);
 }
 
@@ -300,7 +298,7 @@ void ioc_ioprio_changed(struct io_context *ioc, int ioprio)
  * ioc_cgroup_changed - notify cgroup change
  * @ioc: io_context of interest
  *
- * @ioc's cgroup has changed.  Set %CIC_CGROUP_CHANGED for all cic's.
+ * @ioc's cgroup has changed.  Set %ICQ_CGROUP_CHANGED for all icq's.
  * iosched is responsible for checking the bit and applying it on request
  * issue path.
  */
@@ -309,7 +307,7 @@ void ioc_cgroup_changed(struct io_context *ioc)
         unsigned long flags;
 
         spin_lock_irqsave(&ioc->lock, flags);
-        ioc_set_changed(ioc, CIC_CGROUP_CHANGED);
+        ioc_set_changed(ioc, ICQ_CGROUP_CHANGED);
         spin_unlock_irqrestore(&ioc->lock, flags);
 }
 
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 5f7e4d161404..d2f16fcdec7f 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -54,13 +54,12 @@ static const int cfq_hist_divisor = 4;
 #define CFQQ_SECT_THR_NONROT    (sector_t)(2 * 32)
 #define CFQQ_SEEKY(cfqq)        (hweight32(cfqq->seek_history) > 32/8)
 
-#define RQ_CIC(rq)              \
-        ((struct cfq_io_context *) (rq)->elevator_private[0])
+#define RQ_CIC(rq)              icq_to_cic((rq)->elevator_private[0])
 #define RQ_CFQQ(rq)             (struct cfq_queue *) ((rq)->elevator_private[1])
 #define RQ_CFQG(rq)             (struct cfq_group *) ((rq)->elevator_private[2])
 
 static struct kmem_cache *cfq_pool;
-static struct kmem_cache *cfq_ioc_pool;
+static struct kmem_cache *cfq_icq_pool;
 
 #define CFQ_PRIO_LISTS          IOPRIO_BE_NR
 #define cfq_class_idle(cfqq)    ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
@@ -69,6 +68,14 @@ static struct kmem_cache *cfq_ioc_pool;
 #define sample_valid(samples)   ((samples) > 80)
 #define rb_entry_cfqg(node)     rb_entry((node), struct cfq_group, rb_node)
 
+struct cfq_ttime {
+        unsigned long last_end_request;
+
+        unsigned long ttime_total;
+        unsigned long ttime_samples;
+        unsigned long ttime_mean;
+};
+
 /*
  * Most of our rbtree usage is for sorting with min extraction, so
  * if we cache the leftmost node we don't have to walk down the tree
@@ -210,6 +217,12 @@ struct cfq_group {
         struct cfq_ttime ttime;
 };
 
+struct cfq_io_cq {
+        struct io_cq            icq;            /* must be the first member */
+        struct cfq_queue        *cfqq[2];
+        struct cfq_ttime        ttime;
+};
+
 /*
  * Per block device queue structure
  */
@@ -261,7 +274,7 @@ struct cfq_data {
         struct work_struct unplug_work;
 
         struct cfq_queue *active_queue;
-        struct cfq_io_context *active_cic;
+        struct cfq_io_cq *active_cic;
 
         /*
          * async queue for each priority case
@@ -284,7 +297,7 @@ struct cfq_data {
         unsigned int cfq_group_idle;
         unsigned int cfq_latency;
 
-        struct list_head cic_list;
+        struct list_head icq_list;
 
         /*
          * Fallback dummy cfqq for extreme OOM conditions
@@ -457,24 +470,28 @@ 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_context *cfq_cic_lookup(struct cfq_data *,
-                                                struct io_context *);
+static struct cfq_io_cq *cfq_cic_lookup(struct cfq_data *, struct io_context *);
 
-static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_context *cic,
-                                            bool is_sync)
+static inline struct cfq_io_cq *icq_to_cic(struct io_cq *icq)
+{
+        /* cic->icq is the first member, %NULL will convert to %NULL */
+        return container_of(icq, struct cfq_io_cq, icq);
+}
+
+static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_cq *cic, bool is_sync)
 {
         return cic->cfqq[is_sync];
 }
 
-static inline void cic_set_cfqq(struct cfq_io_context *cic,
-                                struct cfq_queue *cfqq, bool is_sync)
+static inline void cic_set_cfqq(struct cfq_io_cq *cic, struct cfq_queue *cfqq,
+                                bool is_sync)
 {
         cic->cfqq[is_sync] = cfqq;
 }
 
-static inline struct cfq_data *cic_to_cfqd(struct cfq_io_context *cic)
+static inline struct cfq_data *cic_to_cfqd(struct cfq_io_cq *cic)
 {
-        return cic->q->elevator->elevator_data;
+        return cic->icq.q->elevator->elevator_data;
 }
 
 /*
@@ -1541,7 +1558,7 @@ static struct request *
 cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio)
 {
         struct task_struct *tsk = current;
-        struct cfq_io_context *cic;
+        struct cfq_io_cq *cic;
         struct cfq_queue *cfqq;
 
         cic = cfq_cic_lookup(cfqd, tsk->io_context);
@@ -1655,7 +1672,7 @@ static int cfq_allow_merge(struct request_queue *q, struct request *rq,
                            struct bio *bio)
 {
         struct cfq_data *cfqd = q->elevator->elevator_data;
-        struct cfq_io_context *cic;
+        struct cfq_io_cq *cic;
         struct cfq_queue *cfqq;
 
         /*
@@ -1671,7 +1688,7 @@ static int cfq_allow_merge(struct request_queue *q, struct request *rq,
          * and %current are guaranteed to be equal.  Avoid lookup which
          * requires queue_lock by using @rq's cic.
          */
-        if (current->io_context == RQ_CIC(rq)->ioc) {
+        if (current->io_context == RQ_CIC(rq)->icq.ioc) {
                 cic = RQ_CIC(rq);
         } else {
                 cic = cfq_cic_lookup(cfqd, current->io_context);
@@ -1761,7 +1778,7 @@ __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq,
                 cfqd->active_queue = NULL;
 
         if (cfqd->active_cic) {
-                put_io_context(cfqd->active_cic->ioc, cfqd->queue);
+                put_io_context(cfqd->active_cic->icq.ioc, cfqd->queue);
                 cfqd->active_cic = NULL;
         }
 }
@@ -1981,7 +1998,7 @@ static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq)
 static void cfq_arm_slice_timer(struct cfq_data *cfqd)
 {
         struct cfq_queue *cfqq = cfqd->active_queue;
-        struct cfq_io_context *cic;
+        struct cfq_io_cq *cic;
         unsigned long sl, group_idle = 0;
 
         /*
@@ -2016,7 +2033,7 @@ static void cfq_arm_slice_timer(struct cfq_data *cfqd)
          * task has exited, don't wait
          */
         cic = cfqd->active_cic;
-        if (!cic || !atomic_read(&cic->ioc->nr_tasks))
+        if (!cic || !atomic_read(&cic->icq.ioc->nr_tasks))
                 return;
 
         /*
@@ -2567,9 +2584,9 @@ static bool cfq_dispatch_request(struct cfq_data *cfqd, struct cfq_queue *cfqq)
         cfq_dispatch_insert(cfqd->queue, rq);
 
         if (!cfqd->active_cic) {
-                struct cfq_io_context *cic = RQ_CIC(rq);
+                struct cfq_io_cq *cic = RQ_CIC(rq);
 
-                atomic_long_inc(&cic->ioc->refcount);
+                atomic_long_inc(&cic->icq.ioc->refcount);
                 cfqd->active_cic = cic;
         }
 
@@ -2652,24 +2669,24 @@ static void cfq_put_queue(struct cfq_queue *cfqq)
         cfq_put_cfqg(cfqg);
 }
 
-static void cfq_cic_free_rcu(struct rcu_head *head)
+static void cfq_icq_free_rcu(struct rcu_head *head)
 {
-        kmem_cache_free(cfq_ioc_pool,
-                        container_of(head, struct cfq_io_context, rcu_head));
+        kmem_cache_free(cfq_icq_pool,
+                        icq_to_cic(container_of(head, struct io_cq, rcu_head)));
 }
 
-static void cfq_cic_free(struct cfq_io_context *cic)
+static void cfq_icq_free(struct io_cq *icq)
 {
-        call_rcu(&cic->rcu_head, cfq_cic_free_rcu);
+        call_rcu(&icq->rcu_head, cfq_icq_free_rcu);
 }
 
-static void cfq_release_cic(struct cfq_io_context *cic)
+static void cfq_release_icq(struct io_cq *icq)
 {
-        struct io_context *ioc = cic->ioc;
+        struct io_context *ioc = icq->ioc;
 
-        radix_tree_delete(&ioc->radix_root, cic->q->id);
-        hlist_del(&cic->cic_list);
-        cfq_cic_free(cic);
+        radix_tree_delete(&ioc->icq_tree, icq->q->id);
+        hlist_del(&icq->ioc_node);
+        cfq_icq_free(icq);
 }
 
 static void cfq_put_cooperator(struct cfq_queue *cfqq)
@@ -2705,20 +2722,21 @@ static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
         cfq_put_queue(cfqq);
 }
 
-static void cfq_exit_cic(struct cfq_io_context *cic)
+static void cfq_exit_icq(struct io_cq *icq)
 {
+        struct cfq_io_cq *cic = icq_to_cic(icq);
         struct cfq_data *cfqd = cic_to_cfqd(cic);
-        struct io_context *ioc = cic->ioc;
+        struct io_context *ioc = icq->ioc;
 
-        list_del_init(&cic->queue_list);
+        list_del_init(&icq->q_node);
 
         /*
-         * Both setting lookup hint to and clearing it from @cic are done
-         * under queue_lock.  If it's not pointing to @cic now, it never
+         * Both setting lookup hint to and clearing it from @icq are done
+         * under queue_lock.  If it's not pointing to @icq now, it never
          * will.  Hint assignment itself can race safely.
          */
-        if (rcu_dereference_raw(ioc->ioc_data) == cic)
-                rcu_assign_pointer(ioc->ioc_data, NULL);
+        if (rcu_dereference_raw(ioc->icq_hint) == icq)
+                rcu_assign_pointer(ioc->icq_hint, NULL);
 
         if (cic->cfqq[BLK_RW_ASYNC]) {
                 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_ASYNC]);
@@ -2731,19 +2749,18 @@ static void cfq_exit_cic(struct cfq_io_context *cic)
         }
 }
 
-static struct cfq_io_context *
-cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
+static struct cfq_io_cq *cfq_alloc_cic(struct cfq_data *cfqd, gfp_t gfp_mask)
 {
-        struct cfq_io_context *cic;
+        struct cfq_io_cq *cic;
 
-        cic = kmem_cache_alloc_node(cfq_ioc_pool, gfp_mask | __GFP_ZERO,
+        cic = kmem_cache_alloc_node(cfq_icq_pool, gfp_mask | __GFP_ZERO,
                                                         cfqd->queue->node);
         if (cic) {
                 cic->ttime.last_end_request = jiffies;
-                INIT_LIST_HEAD(&cic->queue_list);
-                INIT_HLIST_NODE(&cic->cic_list);
-                cic->exit = cfq_exit_cic;
-                cic->release = cfq_release_cic;
+                INIT_LIST_HEAD(&cic->icq.q_node);
+                INIT_HLIST_NODE(&cic->icq.ioc_node);
+                cic->icq.exit = cfq_exit_icq;
+                cic->icq.release = cfq_release_icq;
         }
 
         return cic;
@@ -2791,7 +2808,7 @@ static void cfq_init_prio_data(struct cfq_queue *cfqq, struct io_context *ioc)
         cfq_clear_cfqq_prio_changed(cfqq);
 }
 
-static void changed_ioprio(struct cfq_io_context *cic)
+static void changed_ioprio(struct cfq_io_cq *cic)
 {
         struct cfq_data *cfqd = cic_to_cfqd(cic);
         struct cfq_queue *cfqq;
@@ -2802,7 +2819,7 @@ static void changed_ioprio(struct cfq_io_context *cic)
         cfqq = cic->cfqq[BLK_RW_ASYNC];
         if (cfqq) {
                 struct cfq_queue *new_cfqq;
-                new_cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic->ioc,
+                new_cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic->icq.ioc,
                                                 GFP_ATOMIC);
                 if (new_cfqq) {
                         cic->cfqq[BLK_RW_ASYNC] = new_cfqq;
@@ -2836,7 +2853,7 @@ static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
 }
 
 #ifdef CONFIG_CFQ_GROUP_IOSCHED
-static void changed_cgroup(struct cfq_io_context *cic)
+static void changed_cgroup(struct cfq_io_cq *cic)
 {
         struct cfq_queue *sync_cfqq = cic_to_cfqq(cic, 1);
         struct cfq_data *cfqd = cic_to_cfqd(cic);
@@ -2864,7 +2881,7 @@ cfq_find_alloc_queue(struct cfq_data *cfqd, bool is_sync,
                      struct io_context *ioc, gfp_t gfp_mask)
 {
         struct cfq_queue *cfqq, *new_cfqq = NULL;
-        struct cfq_io_context *cic;
+        struct cfq_io_cq *cic;
         struct cfq_group *cfqg;
 
 retry:
@@ -2956,56 +2973,57 @@ cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct io_context *ioc,
 }
 
 /**
- * cfq_cic_lookup - lookup cfq_io_context
+ * cfq_cic_lookup - lookup cfq_io_cq
  * @cfqd: the associated cfq_data
  * @ioc: the associated io_context
  *
- * Look up cfq_io_context associated with @cfqd - @ioc pair.  Must be
- * called with queue_lock held.
+ * Look up cfq_io_cq associated with @cfqd - @ioc pair.  Must be called
+ * with queue_lock held.
  */
-static struct cfq_io_context *
+static struct cfq_io_cq *
 cfq_cic_lookup(struct cfq_data *cfqd, struct io_context *ioc)
 {
         struct request_queue *q = cfqd->queue;
-        struct cfq_io_context *cic;
+        struct io_cq *icq;
 
         lockdep_assert_held(cfqd->queue->queue_lock);
         if (unlikely(!ioc))
                 return NULL;
 
         /*
-         * cic's are indexed from @ioc using radix tree and hint pointer,
+         * 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 cic which points to us, it's guaranteed to be valid.
+         * find a icq which points to us, it's guaranteed to be valid.
          */
         rcu_read_lock();
-        cic = rcu_dereference(ioc->ioc_data);
-        if (cic && cic->q == q)
+        icq = rcu_dereference(ioc->icq_hint);
+        if (icq && icq->q == q)
                 goto out;
 
-        cic = radix_tree_lookup(&ioc->radix_root, cfqd->queue->id);
-        if (cic && cic->q == q)
-                rcu_assign_pointer(ioc->ioc_data, cic); /* allowed to race */
+        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
-                cic = NULL;
+                icq = NULL;
 out:
         rcu_read_unlock();
-        return cic;
+        return icq_to_cic(icq);
 }
 
 /**
- * cfq_create_cic - create and link a cfq_io_context
+ * cfq_create_cic - create and link a cfq_io_cq
  * @cfqd: cfqd of interest
  * @gfp_mask: allocation mask
  *
- * Make sure cfq_io_context linking %current->io_context and @cfqd exists.
- * If ioc and/or cic doesn't exist, they will be created using @gfp_mask.
+ * Make sure cfq_io_cq linking %current->io_context and @cfqd exists.  If
+ * ioc and/or cic doesn't exist, they will be created using @gfp_mask.
  */
 static int cfq_create_cic(struct cfq_data *cfqd, gfp_t gfp_mask)
 {
         struct request_queue *q = cfqd->queue;
-        struct cfq_io_context *cic = NULL;
+        struct io_cq *icq = NULL;
+        struct cfq_io_cq *cic;
         struct io_context *ioc;
         int ret = -ENOMEM;
 
@@ -3016,26 +3034,27 @@ static int cfq_create_cic(struct cfq_data *cfqd, gfp_t gfp_mask)
         if (!ioc)
                 goto out;
 
-        cic = cfq_alloc_io_context(cfqd, gfp_mask);
+        cic = cfq_alloc_cic(cfqd, gfp_mask);
         if (!cic)
                 goto out;
+        icq = &cic->icq;
 
         ret = radix_tree_preload(gfp_mask);
         if (ret)
                 goto out;
 
-        cic->ioc = ioc;
-        cic->q = cfqd->queue;
+        icq->ioc = ioc;
+        icq->q = cfqd->queue;
 
-        /* lock both q and ioc and try to link @cic */
+        /* lock both q and ioc and try to link @icq */
         spin_lock_irq(q->queue_lock);
         spin_lock(&ioc->lock);
 
-        ret = radix_tree_insert(&ioc->radix_root, q->id, cic);
+        ret = radix_tree_insert(&ioc->icq_tree, q->id, icq);
         if (likely(!ret)) {
-                hlist_add_head(&cic->cic_list, &ioc->cic_list);
-                list_add(&cic->queue_list, &cfqd->cic_list);
-                cic = NULL;
+                hlist_add_head(&icq->ioc_node, &ioc->icq_list);
+                list_add(&icq->q_node, &cfqd->icq_list);
+                icq = NULL;
         } else if (ret == -EEXIST) {
                 /* someone else already did it */
                 ret = 0;
@@ -3047,29 +3066,28 @@ static int cfq_create_cic(struct cfq_data *cfqd, gfp_t gfp_mask)
         radix_tree_preload_end();
 out:
         if (ret)
-                printk(KERN_ERR "cfq: cic link failed!\n");
-        if (cic)
-                cfq_cic_free(cic);
+                printk(KERN_ERR "cfq: icq link failed!\n");
+        if (icq)
+                cfq_icq_free(icq);
         return ret;
 }
 
 /**
- * cfq_get_io_context - acquire cfq_io_context and bump refcnt on io_context
+ * cfq_get_cic - acquire cfq_io_cq and bump refcnt on io_context
  * @cfqd: cfqd to setup cic for
  * @gfp_mask: allocation mask
  *
- * Return cfq_io_context associating @cfqd and %current->io_context and
+ * Return cfq_io_cq associating @cfqd and %current->io_context and
  * bump refcnt on io_context.  If ioc or cic doesn't exist, they're created
  * using @gfp_mask.
  *
  * Must be called under queue_lock which may be released and re-acquired.
  * This function also may sleep depending on @gfp_mask.
  */
-static struct cfq_io_context *
-cfq_get_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
+static struct cfq_io_cq *cfq_get_cic(struct cfq_data *cfqd, gfp_t gfp_mask)
 {
         struct request_queue *q = cfqd->queue;
-        struct cfq_io_context *cic = NULL;
+        struct cfq_io_cq *cic = NULL;
         struct io_context *ioc;
         int err;
 
@@ -3095,11 +3113,11 @@ cfq_get_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
         /* bump @ioc's refcnt and handle changed notifications */
         get_io_context(ioc);
 
-        if (unlikely(cic->changed)) {
-                if (test_and_clear_bit(CIC_IOPRIO_CHANGED, &cic->changed))
+        if (unlikely(cic->icq.changed)) {
+                if (test_and_clear_bit(ICQ_IOPRIO_CHANGED, &cic->icq.changed))
                         changed_ioprio(cic);
 #ifdef CONFIG_CFQ_GROUP_IOSCHED
-                if (test_and_clear_bit(CIC_CGROUP_CHANGED, &cic->changed))
+                if (test_and_clear_bit(ICQ_CGROUP_CHANGED, &cic->icq.changed))
                         changed_cgroup(cic);
 #endif
         }
@@ -3120,7 +3138,7 @@ __cfq_update_io_thinktime(struct cfq_ttime *ttime, unsigned long slice_idle)
 
 static void
 cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_queue *cfqq,
-        struct cfq_io_context *cic)
+                        struct cfq_io_cq *cic)
 {
         if (cfq_cfqq_sync(cfqq)) {
                 __cfq_update_io_thinktime(&cic->ttime, cfqd->cfq_slice_idle);
@@ -3158,7 +3176,7 @@ cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_queue *cfqq,
  */
 static void
 cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq,
-                       struct cfq_io_context *cic)
+                       struct cfq_io_cq *cic)
 {
         int old_idle, enable_idle;
 
@@ -3175,8 +3193,9 @@ cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq,
 
         if (cfqq->next_rq && (cfqq->next_rq->cmd_flags & REQ_NOIDLE))
                 enable_idle = 0;
-        else if (!atomic_read(&cic->ioc->nr_tasks) || !cfqd->cfq_slice_idle ||
-            (!cfq_cfqq_deep(cfqq) && CFQQ_SEEKY(cfqq)))
+        else if (!atomic_read(&cic->icq.ioc->nr_tasks) ||
+                 !cfqd->cfq_slice_idle ||
+                 (!cfq_cfqq_deep(cfqq) && CFQQ_SEEKY(cfqq)))
                 enable_idle = 0;
         else if (sample_valid(cic->ttime.ttime_samples)) {
                 if (cic->ttime.ttime_mean > cfqd->cfq_slice_idle)
@@ -3308,7 +3327,7 @@ static void
 cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
                 struct request *rq)
 {
-        struct cfq_io_context *cic = RQ_CIC(rq);
+        struct cfq_io_cq *cic = RQ_CIC(rq);
 
         cfqd->rq_queued++;
         if (rq->cmd_flags & REQ_PRIO)
@@ -3361,7 +3380,7 @@ static void cfq_insert_request(struct request_queue *q, struct request *rq)
         struct cfq_queue *cfqq = RQ_CFQQ(rq);
 
         cfq_log_cfqq(cfqd, cfqq, "insert_request");
-        cfq_init_prio_data(cfqq, RQ_CIC(rq)->ioc);
+        cfq_init_prio_data(cfqq, RQ_CIC(rq)->icq.ioc);
 
         rq_set_fifo_time(rq, jiffies + cfqd->cfq_fifo_expire[rq_is_sync(rq)]);
         list_add_tail(&rq->queuelist, &cfqq->fifo);
@@ -3411,7 +3430,7 @@ static void cfq_update_hw_tag(struct cfq_data *cfqd)
 
 static bool cfq_should_wait_busy(struct cfq_data *cfqd, struct cfq_queue *cfqq)
 {
-        struct cfq_io_context *cic = cfqd->active_cic;
+        struct cfq_io_cq *cic = cfqd->active_cic;
 
         /* If the queue already has requests, don't wait */
         if (!RB_EMPTY_ROOT(&cfqq->sort_list))
@@ -3548,7 +3567,7 @@ static int cfq_may_queue(struct request_queue *q, int rw)
 {
         struct cfq_data *cfqd = q->elevator->elevator_data;
         struct task_struct *tsk = current;
-        struct cfq_io_context *cic;
+        struct cfq_io_cq *cic;
         struct cfq_queue *cfqq;
 
         /*
@@ -3563,7 +3582,7 @@ static int cfq_may_queue(struct request_queue *q, int rw)
 
         cfqq = cic_to_cfqq(cic, rw_is_sync(rw));
         if (cfqq) {
-                cfq_init_prio_data(cfqq, cic->ioc);
+                cfq_init_prio_data(cfqq, cic->icq.ioc);
 
                 return __cfq_may_queue(cfqq);
         }
@@ -3584,7 +3603,7 @@ static void cfq_put_request(struct request *rq)
                 BUG_ON(!cfqq->allocated[rw]);
                 cfqq->allocated[rw]--;
 
-                put_io_context(RQ_CIC(rq)->ioc, cfqq->cfqd->queue);
+                put_io_context(RQ_CIC(rq)->icq.ioc, cfqq->cfqd->queue);
 
                 rq->elevator_private[0] = NULL;
                 rq->elevator_private[1] = NULL;
@@ -3598,7 +3617,7 @@ static void cfq_put_request(struct request *rq)
 }
 
 static struct cfq_queue *
-cfq_merge_cfqqs(struct cfq_data *cfqd, struct cfq_io_context *cic,
+cfq_merge_cfqqs(struct cfq_data *cfqd, struct cfq_io_cq *cic,
                 struct cfq_queue *cfqq)
 {
         cfq_log_cfqq(cfqd, cfqq, "merging with queue %p", cfqq->new_cfqq);
@@ -3613,7 +3632,7 @@ cfq_merge_cfqqs(struct cfq_data *cfqd, struct cfq_io_context *cic,
  * was the last process referring to said cfqq.
  */
 static struct cfq_queue *
-split_cfqq(struct cfq_io_context *cic, struct cfq_queue *cfqq)
+split_cfqq(struct cfq_io_cq *cic, struct cfq_queue *cfqq)
 {
         if (cfqq_process_refs(cfqq) == 1) {
                 cfqq->pid = current->pid;
@@ -3636,7 +3655,7 @@ static int
 cfq_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask)
 {
         struct cfq_data *cfqd = q->elevator->elevator_data;
-        struct cfq_io_context *cic;
+        struct cfq_io_cq *cic;
         const int rw = rq_data_dir(rq);
         const bool is_sync = rq_is_sync(rq);
         struct cfq_queue *cfqq;
@@ -3644,14 +3663,14 @@ cfq_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask)
         might_sleep_if(gfp_mask & __GFP_WAIT);
 
         spin_lock_irq(q->queue_lock);
-        cic = cfq_get_io_context(cfqd, gfp_mask);
+        cic = cfq_get_cic(cfqd, gfp_mask);
         if (!cic)
                 goto queue_fail;
 
 new_queue:
         cfqq = cic_to_cfqq(cic, is_sync);
         if (!cfqq || cfqq == &cfqd->oom_cfqq) {
-                cfqq = cfq_get_queue(cfqd, is_sync, cic->ioc, gfp_mask);
+                cfqq = cfq_get_queue(cfqd, is_sync, cic->icq.ioc, gfp_mask);
                 cic_set_cfqq(cic, cfqq, is_sync);
         } else {
                 /*
@@ -3677,7 +3696,7 @@ new_queue:
         cfqq->allocated[rw]++;
 
         cfqq->ref++;
-        rq->elevator_private[0] = cic;
+        rq->elevator_private[0] = &cic->icq;
         rq->elevator_private[1] = cfqq;
         rq->elevator_private[2] = cfq_ref_get_cfqg(cfqq->cfqg);
         spin_unlock_irq(q->queue_lock);
@@ -3791,15 +3810,14 @@ static void cfq_exit_queue(struct elevator_queue *e)
         if (cfqd->active_queue)
                 __cfq_slice_expired(cfqd, cfqd->active_queue, 0);
 
-        while (!list_empty(&cfqd->cic_list)) {
-                struct cfq_io_context *cic = list_entry(cfqd->cic_list.next,
-                                                        struct cfq_io_context,
-                                                        queue_list);
-                struct io_context *ioc = cic->ioc;
+        while (!list_empty(&cfqd->icq_list)) {
+                struct io_cq *icq = list_entry(cfqd->icq_list.next,
+                                               struct io_cq, q_node);
+                struct io_context *ioc = icq->ioc;
 
                 spin_lock(&ioc->lock);
-                cfq_exit_cic(cic);
-                cfq_release_cic(cic);
+                cfq_exit_icq(icq);
+                cfq_release_icq(icq);
                 spin_unlock(&ioc->lock);
         }
 
@@ -3904,7 +3922,7 @@ static void *cfq_init_queue(struct request_queue *q)
         cfqd->oom_cfqq.ref++;
         cfq_link_cfqq_cfqg(&cfqd->oom_cfqq, &cfqd->root_group);
 
-        INIT_LIST_HEAD(&cfqd->cic_list);
+        INIT_LIST_HEAD(&cfqd->icq_list);
 
         cfqd->queue = q;
 
@@ -3942,8 +3960,8 @@ static void cfq_slab_kill(void)
          */
         if (cfq_pool)
                 kmem_cache_destroy(cfq_pool);
-        if (cfq_ioc_pool)
-                kmem_cache_destroy(cfq_ioc_pool);
+        if (cfq_icq_pool)
+                kmem_cache_destroy(cfq_icq_pool);
 }
 
 static int __init cfq_slab_setup(void)
@@ -3952,8 +3970,8 @@ static int __init cfq_slab_setup(void)
         if (!cfq_pool)
                 goto fail;
 
-        cfq_ioc_pool = KMEM_CACHE(cfq_io_context, 0);
-        if (!cfq_ioc_pool)
+        cfq_icq_pool = KMEM_CACHE(cfq_io_cq, 0);
+        if (!cfq_icq_pool)
                 goto fail;
 
         return 0;