Merge branch 'cfq-merge' of git://brick.kernel.dk/data/git/linux-2.6-block

* 'cfq-merge' of git://brick.kernel.dk/data/git/linux-2.6-block:
  [BLOCK] cfq-iosched: seek and async performance fixes
  [PATCH] ll_rw_blk: fix 80-col offender in put_io_context()
  [PATCH] cfq-iosched: small cfq_choose_req() optimization
  [PATCH] [BLOCK] cfq-iosched: change cfq io context linking from list to tree

3 files changed, 220 insertions, 180 deletions

diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index bde40a6ae665..67d446de0227 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -26,18 +26,12 @@ static const int cfq_back_penalty = 2;		/* penalty of a backwards seek */
 static const int cfq_slice_sync = HZ / 10;
 static int cfq_slice_async = HZ / 25;
 static const int cfq_slice_async_rq = 2;
-static int cfq_slice_idle = HZ / 100;
+static int cfq_slice_idle = HZ / 70;
 
 #define CFQ_IDLE_GRACE          (HZ / 10)
 #define CFQ_SLICE_SCALE         (5)
 
 #define CFQ_KEY_ASYNC           (0)
-#define CFQ_KEY_ANY             (0xffff)
-
-/*
- * disable queueing at the driver/hardware level
- */
-static const int cfq_max_depth = 2;
 
 static DEFINE_RWLOCK(cfq_exit_lock);
 
@@ -102,6 +96,8 @@ static struct completion *ioc_gone;
 #define cfq_cfqq_sync(cfqq)             \
         (cfq_cfqq_class_sync(cfqq) || (cfqq)->on_dispatch[SYNC])
 
+#define sample_valid(samples)   ((samples) > 80)
+
 /*
  * Per block device queue structure
  */
@@ -170,7 +166,6 @@ struct cfq_data {
         unsigned int cfq_slice[2];
         unsigned int cfq_slice_async_rq;
         unsigned int cfq_slice_idle;
-        unsigned int cfq_max_depth;
 
         struct list_head cic_list;
 };
@@ -343,17 +338,27 @@ static int cfq_queue_empty(request_queue_t *q)
         return !cfqd->busy_queues;
 }
 
+static inline pid_t cfq_queue_pid(struct task_struct *task, int rw)
+{
+        if (rw == READ || process_sync(task))
+                return task->pid;
+
+        return CFQ_KEY_ASYNC;
+}
+
 /*
  * Lifted from AS - choose which of crq1 and crq2 that is best served now.
  * We choose the request that is closest to the head right now. Distance
- * behind the head are penalized and only allowed to a certain extent.
+ * behind the head is penalized and only allowed to a certain extent.
  */
 static struct cfq_rq *
 cfq_choose_req(struct cfq_data *cfqd, struct cfq_rq *crq1, struct cfq_rq *crq2)
 {
         sector_t last, s1, s2, d1 = 0, d2 = 0;
-        int r1_wrap = 0, r2_wrap = 0;   /* requests are behind the disk head */
         unsigned long back_max;
+#define CFQ_RQ1_WRAP    0x01 /* request 1 wraps */
+#define CFQ_RQ2_WRAP    0x02 /* request 2 wraps */
+        unsigned wrap = 0; /* bit mask: requests behind the disk head? */
 
         if (crq1 == NULL || crq1 == crq2)
                 return crq2;
@@ -385,35 +390,47 @@ cfq_choose_req(struct cfq_data *cfqd, struct cfq_rq *crq1, struct cfq_rq *crq2)
         else if (s1 + back_max >= last)
                 d1 = (last - s1) * cfqd->cfq_back_penalty;
         else
-                r1_wrap = 1;
+                wrap |= CFQ_RQ1_WRAP;
 
         if (s2 >= last)
                 d2 = s2 - last;
         else if (s2 + back_max >= last)
                 d2 = (last - s2) * cfqd->cfq_back_penalty;
         else
-                r2_wrap = 1;
+                wrap |= CFQ_RQ2_WRAP;
 
         /* Found required data */
-        if (!r1_wrap && r2_wrap)
-                return crq1;
-        else if (!r2_wrap && r1_wrap)
-                return crq2;
-        else if (r1_wrap && r2_wrap) {
-                /* both behind the head */
-                if (s1 <= s2)
+
+        /*
+         * By doing switch() on the bit mask "wrap" we avoid having to
+         * check two variables for all permutations: --> faster!
+         */
+        switch (wrap) {
+        case 0: /* common case for CFQ: crq1 and crq2 not wrapped */
+                if (d1 < d2)
                         return crq1;
-                else
+                else if (d2 < d1)
                         return crq2;
-        }
+                else {
+                        if (s1 >= s2)
+                                return crq1;
+                        else
+                                return crq2;
+                }
 
-        /* Both requests in front of the head */
-        if (d1 < d2)
+        case CFQ_RQ2_WRAP:
                 return crq1;
-        else if (d2 < d1)
+        case CFQ_RQ1_WRAP:
                 return crq2;
-        else {
-                if (s1 >= s2)
+        case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both crqs wrapped */
+        default:
+                /*
+                 * Since both rqs are wrapped,
+                 * start with the one that's further behind head
+                 * (--> only *one* back seek required),
+                 * since back seek takes more time than forward.
+                 */
+                if (s1 <= s2)
                         return crq1;
                 else
                         return crq2;
@@ -612,15 +629,20 @@ cfq_reposition_crq_rb(struct cfq_queue *cfqq, struct cfq_rq *crq)
         cfq_add_crq_rb(crq);
 }
 
-static struct request *cfq_find_rq_rb(struct cfq_data *cfqd, sector_t sector)
-
+static struct request *
+cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio)
 {
-        struct cfq_queue *cfqq = cfq_find_cfq_hash(cfqd, current->pid, CFQ_KEY_ANY);
+        struct task_struct *tsk = current;
+        pid_t key = cfq_queue_pid(tsk, bio_data_dir(bio));
+        struct cfq_queue *cfqq;
         struct rb_node *n;
+        sector_t sector;
 
+        cfqq = cfq_find_cfq_hash(cfqd, key, tsk->ioprio);
         if (!cfqq)
                 goto out;
 
+        sector = bio->bi_sector + bio_sectors(bio);
         n = cfqq->sort_list.rb_node;
         while (n) {
                 struct cfq_rq *crq = rb_entry_crq(n);
@@ -674,7 +696,7 @@ cfq_merge(request_queue_t *q, struct request **req, struct bio *bio)
                 goto out;
         }
 
-        __rq = cfq_find_rq_rb(cfqd, bio->bi_sector + bio_sectors(bio));
+        __rq = cfq_find_rq_fmerge(cfqd, bio);
         if (__rq && elv_rq_merge_ok(__rq, bio)) {
                 ret = ELEVATOR_FRONT_MERGE;
                 goto out;
@@ -877,6 +899,7 @@ static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd)
 static int cfq_arm_slice_timer(struct cfq_data *cfqd, struct cfq_queue *cfqq)
 
 {
+        struct cfq_io_context *cic;
         unsigned long sl;
 
         WARN_ON(!RB_EMPTY(&cfqq->sort_list));
@@ -892,13 +915,23 @@ static int cfq_arm_slice_timer(struct cfq_data *cfqd, struct cfq_queue *cfqq)
         /*
          * task has exited, don't wait
          */
-        if (cfqd->active_cic && !cfqd->active_cic->ioc->task)
+        cic = cfqd->active_cic;
+        if (!cic || !cic->ioc->task)
                 return 0;
 
         cfq_mark_cfqq_must_dispatch(cfqq);
         cfq_mark_cfqq_wait_request(cfqq);
 
         sl = min(cfqq->slice_end - 1, (unsigned long) cfqd->cfq_slice_idle);
+
+        /*
+         * we don't want to idle for seeks, but we do want to allow
+         * fair distribution of slice time for a process doing back-to-back
+         * seeks. so allow a little bit of time for him to submit a new rq
+         */
+        if (sample_valid(cic->seek_samples) && cic->seek_mean > 131072)
+                sl = 2;
+
         mod_timer(&cfqd->idle_slice_timer, jiffies + sl);
         return 1;
 }
@@ -1115,13 +1148,6 @@ cfq_dispatch_requests(request_queue_t *q, int force)
         if (cfqq) {
                 int max_dispatch;
 
-                /*
-                 * if idle window is disabled, allow queue buildup
-                 */
-                if (!cfq_cfqq_idle_window(cfqq) &&
-                    cfqd->rq_in_driver >= cfqd->cfq_max_depth)
-                        return 0;
-
                 cfq_clear_cfqq_must_dispatch(cfqq);
                 cfq_clear_cfqq_wait_request(cfqq);
                 del_timer(&cfqd->idle_slice_timer);
@@ -1171,13 +1197,13 @@ __cfq_find_cfq_hash(struct cfq_data *cfqd, unsigned int key, unsigned int prio,
                     const int hashval)
 {
         struct hlist_head *hash_list = &cfqd->cfq_hash[hashval];
-        struct hlist_node *entry, *next;
+        struct hlist_node *entry;
+        struct cfq_queue *__cfqq;
 
-        hlist_for_each_safe(entry, next, hash_list) {
-                struct cfq_queue *__cfqq = list_entry_qhash(entry);
+        hlist_for_each_entry(__cfqq, entry, hash_list, cfq_hash) {
                 const unsigned short __p = IOPRIO_PRIO_VALUE(__cfqq->org_ioprio_class, __cfqq->org_ioprio);
 
-                if (__cfqq->key == key && (__p == prio || prio == CFQ_KEY_ANY))
+                if (__cfqq->key == key && (__p == prio || !prio))
                         return __cfqq;
         }
 
@@ -1190,19 +1216,19 @@ cfq_find_cfq_hash(struct cfq_data *cfqd, unsigned int key, unsigned short prio)
         return __cfq_find_cfq_hash(cfqd, key, prio, hash_long(key, CFQ_QHASH_SHIFT));
 }
 
-static void cfq_free_io_context(struct cfq_io_context *cic)
+static void cfq_free_io_context(struct io_context *ioc)
 {
         struct cfq_io_context *__cic;
-        struct list_head *entry, *next;
-        int freed = 1;
+        struct rb_node *n;
+        int freed = 0;
 
-        list_for_each_safe(entry, next, &cic->list) {
-                __cic = list_entry(entry, struct cfq_io_context, list);
+        while ((n = rb_first(&ioc->cic_root)) != NULL) {
+                __cic = rb_entry(n, struct cfq_io_context, rb_node);
+                rb_erase(&__cic->rb_node, &ioc->cic_root);
                 kmem_cache_free(cfq_ioc_pool, __cic);
                 freed++;
         }
 
-        kmem_cache_free(cfq_ioc_pool, cic);
         if (atomic_sub_and_test(freed, &ioc_count) && ioc_gone)
                 complete(ioc_gone);
 }
@@ -1210,8 +1236,7 @@ static void cfq_free_io_context(struct cfq_io_context *cic)
 static void cfq_trim(struct io_context *ioc)
 {
         ioc->set_ioprio = NULL;
-        if (ioc->cic)
-                cfq_free_io_context(ioc->cic);
+        cfq_free_io_context(ioc);
 }
 
 /*
@@ -1250,26 +1275,26 @@ static void cfq_exit_single_io_context(struct cfq_io_context *cic)
         spin_unlock(q->queue_lock);
 }
 
-static void cfq_exit_io_context(struct cfq_io_context *cic)
+static void cfq_exit_io_context(struct io_context *ioc)
 {
         struct cfq_io_context *__cic;
-        struct list_head *entry;
         unsigned long flags;
-
-        local_irq_save(flags);
+        struct rb_node *n;
 
         /*
          * put the reference this task is holding to the various queues
          */
-        read_lock(&cfq_exit_lock);
-        list_for_each(entry, &cic->list) {
-                __cic = list_entry(entry, struct cfq_io_context, list);
+        read_lock_irqsave(&cfq_exit_lock, flags);
+
+        n = rb_first(&ioc->cic_root);
+        while (n != NULL) {
+                __cic = rb_entry(n, struct cfq_io_context, rb_node);
+
                 cfq_exit_single_io_context(__cic);
+                n = rb_next(n);
         }
 
-        cfq_exit_single_io_context(cic);
-        read_unlock(&cfq_exit_lock);
-        local_irq_restore(flags);
+        read_unlock_irqrestore(&cfq_exit_lock, flags);
 }
 
 static struct cfq_io_context *
@@ -1278,10 +1303,10 @@ cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
         struct cfq_io_context *cic = kmem_cache_alloc(cfq_ioc_pool, gfp_mask);
 
         if (cic) {
-                INIT_LIST_HEAD(&cic->list);
+                RB_CLEAR(&cic->rb_node);
+                cic->key = NULL;
                 cic->cfqq[ASYNC] = NULL;
                 cic->cfqq[SYNC] = NULL;
-                cic->key = NULL;
                 cic->last_end_request = jiffies;
                 cic->ttime_total = 0;
                 cic->ttime_samples = 0;
@@ -1373,15 +1398,17 @@ static inline void changed_ioprio(struct cfq_io_context *cic)
 static int cfq_ioc_set_ioprio(struct io_context *ioc, unsigned int ioprio)
 {
         struct cfq_io_context *cic;
+        struct rb_node *n;
 
         write_lock(&cfq_exit_lock);
 
-        cic = ioc->cic;
-
-        changed_ioprio(cic);
-
-        list_for_each_entry(cic, &cic->list, list)
+        n = rb_first(&ioc->cic_root);
+        while (n != NULL) {
+                cic = rb_entry(n, struct cfq_io_context, rb_node);
+ 
                 changed_ioprio(cic);
+                n = rb_next(n);
+        }
 
         write_unlock(&cfq_exit_lock);
 
@@ -1445,14 +1472,67 @@ out:
         return cfqq;
 }
 
+static struct cfq_io_context *
+cfq_cic_rb_lookup(struct cfq_data *cfqd, struct io_context *ioc)
+{
+        struct rb_node *n = ioc->cic_root.rb_node;
+        struct cfq_io_context *cic;
+        void *key = cfqd;
+
+        while (n) {
+                cic = rb_entry(n, struct cfq_io_context, rb_node);
+
+                if (key < cic->key)
+                        n = n->rb_left;
+                else if (key > cic->key)
+                        n = n->rb_right;
+                else
+                        return cic;
+        }
+
+        return NULL;
+}
+
+static inline void
+cfq_cic_link(struct cfq_data *cfqd, struct io_context *ioc,
+             struct cfq_io_context *cic)
+{
+        struct rb_node **p = &ioc->cic_root.rb_node;
+        struct rb_node *parent = NULL;
+        struct cfq_io_context *__cic;
+
+        read_lock(&cfq_exit_lock);
+
+        cic->ioc = ioc;
+        cic->key = cfqd;
+
+        ioc->set_ioprio = cfq_ioc_set_ioprio;
+
+        while (*p) {
+                parent = *p;
+                __cic = rb_entry(parent, struct cfq_io_context, rb_node);
+
+                if (cic->key < __cic->key)
+                        p = &(*p)->rb_left;
+                else if (cic->key > __cic->key)
+                        p = &(*p)->rb_right;
+                else
+                        BUG();
+        }
+
+        rb_link_node(&cic->rb_node, parent, p);
+        rb_insert_color(&cic->rb_node, &ioc->cic_root);
+        list_add(&cic->queue_list, &cfqd->cic_list);
+        read_unlock(&cfq_exit_lock);
+}
+
 /*
  * Setup general io context and cfq io context. There can be several cfq
  * io contexts per general io context, if this process is doing io to more
- * than one device managed by cfq. Note that caller is holding a reference to
- * cfqq, so we don't need to worry about it disappearing
+ * than one device managed by cfq.
  */
 static struct cfq_io_context *
-cfq_get_io_context(struct cfq_data *cfqd, pid_t pid, gfp_t gfp_mask)
+cfq_get_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
 {
         struct io_context *ioc = NULL;
         struct cfq_io_context *cic;
@@ -1463,88 +1543,15 @@ cfq_get_io_context(struct cfq_data *cfqd, pid_t pid, gfp_t gfp_mask)
         if (!ioc)
                 return NULL;
 
-restart:
-        if ((cic = ioc->cic) == NULL) {
-                cic = cfq_alloc_io_context(cfqd, gfp_mask);
-
-                if (cic == NULL)
-                        goto err;
-
-                /*
-                 * manually increment generic io_context usage count, it
-                 * cannot go away since we are already holding one ref to it
-                 */
-                cic->ioc = ioc;
-                cic->key = cfqd;
-                read_lock(&cfq_exit_lock);
-                ioc->set_ioprio = cfq_ioc_set_ioprio;
-                ioc->cic = cic;
-                list_add(&cic->queue_list, &cfqd->cic_list);
-                read_unlock(&cfq_exit_lock);
-        } else {
-                struct cfq_io_context *__cic;
-
-                /*
-                 * the first cic on the list is actually the head itself
-                 */
-                if (cic->key == cfqd)
-                        goto out;
-
-                if (unlikely(!cic->key)) {
-                        read_lock(&cfq_exit_lock);
-                        if (list_empty(&cic->list))
-                                ioc->cic = NULL;
-                        else
-                                ioc->cic = list_entry(cic->list.next,
-                                                      struct cfq_io_context,
-                                                      list);
-                        read_unlock(&cfq_exit_lock);
-                        kmem_cache_free(cfq_ioc_pool, cic);
-                        atomic_dec(&ioc_count);
-                        goto restart;
-                }
-
-                /*
-                 * cic exists, check if we already are there. linear search
-                 * should be ok here, the list will usually not be more than
-                 * 1 or a few entries long
-                 */
-                list_for_each_entry(__cic, &cic->list, list) {
-                        /*
-                         * this process is already holding a reference to
-                         * this queue, so no need to get one more
-                         */
-                        if (__cic->key == cfqd) {
-                                cic = __cic;
-                                goto out;
-                        }
-                        if (unlikely(!__cic->key)) {
-                                read_lock(&cfq_exit_lock);
-                                list_del(&__cic->list);
-                                read_unlock(&cfq_exit_lock);
-                                kmem_cache_free(cfq_ioc_pool, __cic);
-                                atomic_dec(&ioc_count);
-                                goto restart;
-                        }
-                }
+        cic = cfq_cic_rb_lookup(cfqd, ioc);
+        if (cic)
+                goto out;
 
-                /*
-                 * nope, process doesn't have a cic assoicated with this
-                 * cfqq yet. get a new one and add to list
-                 */
-                __cic = cfq_alloc_io_context(cfqd, gfp_mask);
-                if (__cic == NULL)
-                        goto err;
-
-                __cic->ioc = ioc;
-                __cic->key = cfqd;
-                read_lock(&cfq_exit_lock);
-                list_add(&__cic->list, &cic->list);
-                list_add(&__cic->queue_list, &cfqd->cic_list);
-                read_unlock(&cfq_exit_lock);
-                cic = __cic;
-        }
+        cic = cfq_alloc_io_context(cfqd, gfp_mask);
+        if (cic == NULL)
+                goto err;
 
+        cfq_cic_link(cfqd, ioc, cic);
 out:
         return cic;
 err:
@@ -1577,7 +1584,33 @@ cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_io_context *cic)
         cic->ttime_mean = (cic->ttime_total + 128) / cic->ttime_samples;
 }
 
-#define sample_valid(samples)   ((samples) > 80)
+static void
+cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_io_context *cic,
+                       struct cfq_rq *crq)
+{
+        sector_t sdist;
+        u64 total;
+
+        if (cic->last_request_pos < crq->request->sector)
+                sdist = crq->request->sector - cic->last_request_pos;
+        else
+                sdist = cic->last_request_pos - crq->request->sector;
+
+        /*
+         * Don't allow the seek distance to get too large from the
+         * odd fragment, pagein, etc
+         */
+        if (cic->seek_samples <= 60) /* second&third seek */
+                sdist = min(sdist, (cic->seek_mean * 4) + 2*1024*1024);
+        else
+                sdist = min(sdist, (cic->seek_mean * 4) + 2*1024*64);
+
+        cic->seek_samples = (7*cic->seek_samples + 256) / 8;
+        cic->seek_total = (7*cic->seek_total + (u64)256*sdist) / 8;
+        total = cic->seek_total + (cic->seek_samples/2);
+        do_div(total, cic->seek_samples);
+        cic->seek_mean = (sector_t)total;
+}
 
 /*
  * Disable idle window if the process thinks too long or seeks so much that
@@ -1690,9 +1723,11 @@ cfq_crq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
         cic = crq->io_context;
 
         cfq_update_io_thinktime(cfqd, cic);
+        cfq_update_io_seektime(cfqd, cic, crq);
         cfq_update_idle_window(cfqd, cfqq, cic);
 
         cic->last_queue = jiffies;
+        cic->last_request_pos = crq->request->sector + crq->request->nr_sectors;
 
         if (cfqq == cfqd->active_queue) {
                 /*
@@ -1825,14 +1860,6 @@ static void cfq_prio_boost(struct cfq_queue *cfqq)
                 cfq_resort_rr_list(cfqq, 0);
 }
 
-static inline pid_t cfq_queue_pid(struct task_struct *task, int rw)
-{
-        if (rw == READ || process_sync(task))
-                return task->pid;
-
-        return CFQ_KEY_ASYNC;
-}
-
 static inline int
 __cfq_may_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq,
                 struct task_struct *task, int rw)
@@ -1965,7 +1992,7 @@ cfq_set_request(request_queue_t *q, struct request *rq, struct bio *bio,
 
         might_sleep_if(gfp_mask & __GFP_WAIT);
 
-        cic = cfq_get_io_context(cfqd, key, gfp_mask);
+        cic = cfq_get_io_context(cfqd, gfp_mask);
 
         spin_lock_irqsave(q->queue_lock, flags);
 
@@ -2133,11 +2160,14 @@ static void cfq_exit_queue(elevator_t *e)
         request_queue_t *q = cfqd->queue;
 
         cfq_shutdown_timer_wq(cfqd);
+
         write_lock(&cfq_exit_lock);
         spin_lock_irq(q->queue_lock);
+
         if (cfqd->active_queue)
                 __cfq_slice_expired(cfqd, cfqd->active_queue, 0);
-        while(!list_empty(&cfqd->cic_list)) {
+
+        while (!list_empty(&cfqd->cic_list)) {
                 struct cfq_io_context *cic = list_entry(cfqd->cic_list.next,
                                                         struct cfq_io_context,
                                                         queue_list);
@@ -2152,6 +2182,7 @@ static void cfq_exit_queue(elevator_t *e)
                 cic->key = NULL;
                 list_del_init(&cic->queue_list);
         }
+
         spin_unlock_irq(q->queue_lock);
         write_unlock(&cfq_exit_lock);
 
@@ -2227,7 +2258,6 @@ static int cfq_init_queue(request_queue_t *q, elevator_t *e)
         cfqd->cfq_slice[1] = cfq_slice_sync;
         cfqd->cfq_slice_async_rq = cfq_slice_async_rq;
         cfqd->cfq_slice_idle = cfq_slice_idle;
-        cfqd->cfq_max_depth = cfq_max_depth;
 
         return 0;
 out_crqpool:
@@ -2310,7 +2340,6 @@ SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1);
 SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1);
 SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1);
 SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0);
-SHOW_FUNCTION(cfq_max_depth_show, cfqd->cfq_max_depth, 0);
 #undef SHOW_FUNCTION
 
 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV)                 \
@@ -2339,7 +2368,6 @@ STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1);
 STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1);
 STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1);
 STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1, UINT_MAX, 0);
-STORE_FUNCTION(cfq_max_depth_store, &cfqd->cfq_max_depth, 1, UINT_MAX, 0);
 #undef STORE_FUNCTION
 
 #define CFQ_ATTR(name) \
@@ -2356,7 +2384,6 @@ static struct elv_fs_entry cfq_attrs[] = {
         CFQ_ATTR(slice_async),
         CFQ_ATTR(slice_async_rq),
         CFQ_ATTR(slice_idle),
-        CFQ_ATTR(max_depth),
         __ATTR_NULL
 };
 
diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c
index 5a19e2eb5711..5b26af8597f3 100644
--- a/block/ll_rw_blk.c
+++ b/block/ll_rw_blk.c
@@ -3539,11 +3539,17 @@ void put_io_context(struct io_context *ioc)
         BUG_ON(atomic_read(&ioc->refcount) == 0);
 
         if (atomic_dec_and_test(&ioc->refcount)) {
+                struct cfq_io_context *cic;
+
                 rcu_read_lock();
                 if (ioc->aic && ioc->aic->dtor)
                         ioc->aic->dtor(ioc->aic);
-                if (ioc->cic && ioc->cic->dtor)
-                        ioc->cic->dtor(ioc->cic);
+                if (ioc->cic_root.rb_node != NULL) {
+                        struct rb_node *n = rb_first(&ioc->cic_root);
+
+                        cic = rb_entry(n, struct cfq_io_context, rb_node);
+                        cic->dtor(ioc);
+                }
                 rcu_read_unlock();
 
                 kmem_cache_free(iocontext_cachep, ioc);
@@ -3556,6 +3562,7 @@ void exit_io_context(void)
 {
         unsigned long flags;
         struct io_context *ioc;
+        struct cfq_io_context *cic;
 
         local_irq_save(flags);
         task_lock(current);
@@ -3567,9 +3574,11 @@ void exit_io_context(void)
 
         if (ioc->aic && ioc->aic->exit)
                 ioc->aic->exit(ioc->aic);
-        if (ioc->cic && ioc->cic->exit)
-                ioc->cic->exit(ioc->cic);
-
+        if (ioc->cic_root.rb_node != NULL) {
+                cic = rb_entry(rb_first(&ioc->cic_root), struct cfq_io_context, rb_node);
+                cic->exit(ioc);
+        }
+ 
         put_io_context(ioc);
 }
 
@@ -3598,7 +3607,7 @@ struct io_context *current_io_context(gfp_t gfp_flags)
                 ret->last_waited = jiffies; /* doesn't matter... */
                 ret->nr_batch_requests = 0; /* because this is 0 */
                 ret->aic = NULL;
-                ret->cic = NULL;
+                ret->cic_root.rb_node = NULL;
                 tsk->io_context = ret;
         }
 
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index c179966f1a2f..d0cac8b58de7 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -55,25 +55,29 @@ struct as_io_context {
 
 struct cfq_queue;
 struct cfq_io_context {
-        /*
-         * circular list of cfq_io_contexts belonging to a process io context
-         */
-        struct list_head list;
-        struct cfq_queue *cfqq[2];
+        struct rb_node rb_node;
         void *key;
 
+        struct cfq_queue *cfqq[2];
+
         struct io_context *ioc;
 
         unsigned long last_end_request;
-        unsigned long last_queue;
+        sector_t last_request_pos;
+        unsigned long last_queue;
+
         unsigned long ttime_total;
         unsigned long ttime_samples;
         unsigned long ttime_mean;
 
+        unsigned int seek_samples;
+        u64 seek_total;
+        sector_t seek_mean;
+
         struct list_head queue_list;
 
-        void (*dtor)(struct cfq_io_context *);
-        void (*exit)(struct cfq_io_context *);
+        void (*dtor)(struct io_context *); /* destructor */
+        void (*exit)(struct io_context *); /* called on task exit */
 };
 
 /*
@@ -94,7 +98,7 @@ struct io_context {
         int nr_batch_requests;     /* Number of requests left in the batch */
 
         struct as_io_context *aic;
-        struct cfq_io_context *cic;
+        struct rb_root cic_root;
 };
 
 void put_io_context(struct io_context *ioc);