drm/i915: Install a fence register for fbc on g4x
[safe/jmp/linux-2.6] / block / cfq-iosched.c
index 0d3b70d..9c4b679 100644 (file)
@@ -48,7 +48,7 @@ static int cfq_slice_idle = HZ / 125;
 static struct kmem_cache *cfq_pool;
 static struct kmem_cache *cfq_ioc_pool;
 
-static DEFINE_PER_CPU(unsigned long, ioc_count);
+static DEFINE_PER_CPU(unsigned long, cfq_ioc_count);
 static struct completion *ioc_gone;
 static DEFINE_SPINLOCK(ioc_gone_lock);
 
@@ -71,6 +71,51 @@ struct cfq_rb_root {
 #define CFQ_RB_ROOT    (struct cfq_rb_root) { RB_ROOT, NULL, }
 
 /*
+ * Per process-grouping structure
+ */
+struct cfq_queue {
+       /* reference count */
+       atomic_t ref;
+       /* various state flags, see below */
+       unsigned int flags;
+       /* parent cfq_data */
+       struct cfq_data *cfqd;
+       /* service_tree member */
+       struct rb_node rb_node;
+       /* service_tree key */
+       unsigned long rb_key;
+       /* prio tree member */
+       struct rb_node p_node;
+       /* prio tree root we belong to, if any */
+       struct rb_root *p_root;
+       /* sorted list of pending requests */
+       struct rb_root sort_list;
+       /* if fifo isn't expired, next request to serve */
+       struct request *next_rq;
+       /* requests queued in sort_list */
+       int queued[2];
+       /* currently allocated requests */
+       int allocated[2];
+       /* fifo list of requests in sort_list */
+       struct list_head fifo;
+
+       unsigned long slice_end;
+       long slice_resid;
+       unsigned int slice_dispatch;
+
+       /* pending metadata requests */
+       int meta_pending;
+       /* number of requests that are on the dispatch list or inside driver */
+       int dispatched;
+
+       /* io prio of this group */
+       unsigned short ioprio, org_ioprio;
+       unsigned short ioprio_class, org_ioprio_class;
+
+       pid_t pid;
+};
+
+/*
  * Per block device queue structure
  */
 struct cfq_data {
@@ -89,13 +134,8 @@ struct cfq_data {
        struct rb_root prio_trees[CFQ_PRIO_LISTS];
 
        unsigned int busy_queues;
-       /*
-        * Used to track any pending rt requests so we can pre-empt current
-        * non-RT cfqq in service when this value is non-zero.
-        */
-       unsigned int busy_rt_queues;
 
-       int rq_in_driver;
+       int rq_in_driver[2];
        int sync_flight;
 
        /*
@@ -110,7 +150,7 @@ struct cfq_data {
         * idle window management
         */
        struct timer_list idle_slice_timer;
-       struct work_struct unplug_work;
+       struct delayed_work unplug_work;
 
        struct cfq_queue *active_queue;
        struct cfq_io_context *active_cic;
@@ -122,7 +162,6 @@ struct cfq_data {
        struct cfq_queue *async_idle_cfqq;
 
        sector_t last_position;
-       unsigned long last_end_request;
 
        /*
         * tunables, see top of file
@@ -134,58 +173,22 @@ struct cfq_data {
        unsigned int cfq_slice[2];
        unsigned int cfq_slice_async_rq;
        unsigned int cfq_slice_idle;
+       unsigned int cfq_latency;
 
        struct list_head cic_list;
-};
-
-/*
- * Per process-grouping structure
- */
-struct cfq_queue {
-       /* reference count */
-       atomic_t ref;
-       /* various state flags, see below */
-       unsigned int flags;
-       /* parent cfq_data */
-       struct cfq_data *cfqd;
-       /* service_tree member */
-       struct rb_node rb_node;
-       /* service_tree key */
-       unsigned long rb_key;
-       /* prio tree member */
-       struct rb_node p_node;
-       /* sorted list of pending requests */
-       struct rb_root sort_list;
-       /* if fifo isn't expired, next request to serve */
-       struct request *next_rq;
-       /* requests queued in sort_list */
-       int queued[2];
-       /* currently allocated requests */
-       int allocated[2];
-       /* fifo list of requests in sort_list */
-       struct list_head fifo;
-
-       unsigned long slice_end;
-       long slice_resid;
-       unsigned int slice_dispatch;
 
-       /* pending metadata requests */
-       int meta_pending;
-       /* number of requests that are on the dispatch list or inside driver */
-       int dispatched;
-
-       /* io prio of this group */
-       unsigned short ioprio, org_ioprio;
-       unsigned short ioprio_class, org_ioprio_class;
+       /*
+        * Fallback dummy cfqq for extreme OOM conditions
+        */
+       struct cfq_queue oom_cfqq;
 
-       pid_t pid;
+       unsigned long last_end_sync_rq;
 };
 
 enum cfqq_state_flags {
        CFQ_CFQQ_FLAG_on_rr = 0,        /* on round-robin busy list */
        CFQ_CFQQ_FLAG_wait_request,     /* waiting for a request */
        CFQ_CFQQ_FLAG_must_dispatch,    /* must be allowed a dispatch */
-       CFQ_CFQQ_FLAG_must_alloc,       /* must be allowed rq alloc */
        CFQ_CFQQ_FLAG_must_alloc_slice, /* per-slice must_alloc flag */
        CFQ_CFQQ_FLAG_fifo_expire,      /* FIFO checked in this slice */
        CFQ_CFQQ_FLAG_idle_window,      /* slice idling enabled */
@@ -212,7 +215,6 @@ static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq)             \
 CFQ_CFQQ_FNS(on_rr);
 CFQ_CFQQ_FNS(wait_request);
 CFQ_CFQQ_FNS(must_dispatch);
-CFQ_CFQQ_FNS(must_alloc);
 CFQ_CFQQ_FNS(must_alloc_slice);
 CFQ_CFQQ_FNS(fifo_expire);
 CFQ_CFQQ_FNS(idle_window);
@@ -233,6 +235,11 @@ static struct cfq_queue *cfq_get_queue(struct cfq_data *, int,
 static struct cfq_io_context *cfq_cic_lookup(struct cfq_data *,
                                                struct io_context *);
 
+static inline int rq_in_driver(struct cfq_data *cfqd)
+{
+       return cfqd->rq_in_driver[0] + cfqd->rq_in_driver[1];
+}
+
 static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_context *cic,
                                            int is_sync)
 {
@@ -251,7 +258,7 @@ static inline void cic_set_cfqq(struct cfq_io_context *cic,
  */
 static inline int cfq_bio_sync(struct bio *bio)
 {
-       if (bio_data_dir(bio) == READ || bio_sync(bio))
+       if (bio_data_dir(bio) == READ || bio_rw_flagged(bio, BIO_RW_SYNCIO))
                return 1;
 
        return 0;
@@ -261,11 +268,13 @@ static inline int cfq_bio_sync(struct bio *bio)
  * scheduler run of queue, if there are requests pending and no one in the
  * driver that will restart queueing
  */
-static inline void cfq_schedule_dispatch(struct cfq_data *cfqd)
+static inline void cfq_schedule_dispatch(struct cfq_data *cfqd,
+                                        unsigned long delay)
 {
        if (cfqd->busy_queues) {
                cfq_log(cfqd, "schedule dispatch");
-               kblockd_schedule_work(cfqd->queue, &cfqd->unplug_work);
+               kblockd_schedule_delayed_work(cfqd->queue, &cfqd->unplug_work,
+                                               delay);
        }
 }
 
@@ -347,8 +356,8 @@ cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2)
        else if (rq_is_meta(rq2) && !rq_is_meta(rq1))
                return rq2;
 
-       s1 = rq1->sector;
-       s2 = rq2->sector;
+       s1 = blk_rq_pos(rq1);
+       s2 = blk_rq_pos(rq2);
 
        last = cfqd->last_position;
 
@@ -558,10 +567,10 @@ static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
 }
 
 static struct cfq_queue *
-cfq_prio_tree_lookup(struct cfq_data *cfqd, int ioprio, sector_t sector,
-                    struct rb_node **ret_parent, struct rb_node ***rb_link)
+cfq_prio_tree_lookup(struct cfq_data *cfqd, struct rb_root *root,
+                    sector_t sector, struct rb_node **ret_parent,
+                    struct rb_node ***rb_link)
 {
-       struct rb_root *root = &cfqd->prio_trees[ioprio];
        struct rb_node **p, *parent;
        struct cfq_queue *cfqq = NULL;
 
@@ -577,41 +586,45 @@ cfq_prio_tree_lookup(struct cfq_data *cfqd, int ioprio, sector_t sector,
                 * Sort strictly based on sector.  Smallest to the left,
                 * largest to the right.
                 */
-               if (sector > cfqq->next_rq->sector)
+               if (sector > blk_rq_pos(cfqq->next_rq))
                        n = &(*p)->rb_right;
-               else if (sector < cfqq->next_rq->sector)
+               else if (sector < blk_rq_pos(cfqq->next_rq))
                        n = &(*p)->rb_left;
                else
                        break;
                p = n;
+               cfqq = NULL;
        }
 
        *ret_parent = parent;
        if (rb_link)
                *rb_link = p;
-       return NULL;
+       return cfqq;
 }
 
 static void cfq_prio_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq)
 {
-       struct rb_root *root = &cfqd->prio_trees[cfqq->ioprio];
        struct rb_node **p, *parent;
        struct cfq_queue *__cfqq;
 
-       if (!RB_EMPTY_NODE(&cfqq->p_node))
-               rb_erase_init(&cfqq->p_node, root);
+       if (cfqq->p_root) {
+               rb_erase(&cfqq->p_node, cfqq->p_root);
+               cfqq->p_root = NULL;
+       }
 
        if (cfq_class_idle(cfqq))
                return;
        if (!cfqq->next_rq)
                return;
 
-       __cfqq = cfq_prio_tree_lookup(cfqd, cfqq->ioprio, cfqq->next_rq->sector,
-                                        &parent, &p);
-       BUG_ON(__cfqq);
-
-       rb_link_node(&cfqq->p_node, parent, p);
-       rb_insert_color(&cfqq->p_node, root);
+       cfqq->p_root = &cfqd->prio_trees[cfqq->org_ioprio];
+       __cfqq = cfq_prio_tree_lookup(cfqd, cfqq->p_root,
+                                     blk_rq_pos(cfqq->next_rq), &parent, &p);
+       if (!__cfqq) {
+               rb_link_node(&cfqq->p_node, parent, p);
+               rb_insert_color(&cfqq->p_node, cfqq->p_root);
+       } else
+               cfqq->p_root = NULL;
 }
 
 /*
@@ -638,8 +651,6 @@ static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
        BUG_ON(cfq_cfqq_on_rr(cfqq));
        cfq_mark_cfqq_on_rr(cfqq);
        cfqd->busy_queues++;
-       if (cfq_class_rt(cfqq))
-               cfqd->busy_rt_queues++;
 
        cfq_resort_rr_list(cfqd, cfqq);
 }
@@ -656,13 +667,13 @@ static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
 
        if (!RB_EMPTY_NODE(&cfqq->rb_node))
                cfq_rb_erase(&cfqq->rb_node, &cfqd->service_tree);
-       if (!RB_EMPTY_NODE(&cfqq->p_node))
-               rb_erase_init(&cfqq->p_node, &cfqd->prio_trees[cfqq->ioprio]);
+       if (cfqq->p_root) {
+               rb_erase(&cfqq->p_node, cfqq->p_root);
+               cfqq->p_root = NULL;
+       }
 
        BUG_ON(!cfqd->busy_queues);
        cfqd->busy_queues--;
-       if (cfq_class_rt(cfqq))
-               cfqd->busy_rt_queues--;
 }
 
 /*
@@ -748,21 +759,22 @@ static void cfq_activate_request(struct request_queue *q, struct request *rq)
 {
        struct cfq_data *cfqd = q->elevator->elevator_data;
 
-       cfqd->rq_in_driver++;
+       cfqd->rq_in_driver[rq_is_sync(rq)]++;
        cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "activate rq, drv=%d",
-                                               cfqd->rq_in_driver);
+                                               rq_in_driver(cfqd));
 
-       cfqd->last_position = rq->hard_sector + rq->hard_nr_sectors;
+       cfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq);
 }
 
 static void cfq_deactivate_request(struct request_queue *q, struct request *rq)
 {
        struct cfq_data *cfqd = q->elevator->elevator_data;
+       const int sync = rq_is_sync(rq);
 
-       WARN_ON(!cfqd->rq_in_driver);
-       cfqd->rq_in_driver--;
+       WARN_ON(!cfqd->rq_in_driver[sync]);
+       cfqd->rq_in_driver[sync]--;
        cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "deactivate rq, drv=%d",
-                                               cfqd->rq_in_driver);
+                                               rq_in_driver(cfqd));
 }
 
 static void cfq_remove_request(struct request *rq)
@@ -941,26 +953,30 @@ static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd,
 static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd,
                                          struct request *rq)
 {
-       if (rq->sector >= cfqd->last_position)
-               return rq->sector - cfqd->last_position;
+       if (blk_rq_pos(rq) >= cfqd->last_position)
+               return blk_rq_pos(rq) - cfqd->last_position;
        else
-               return cfqd->last_position - rq->sector;
+               return cfqd->last_position - blk_rq_pos(rq);
 }
 
+#define CIC_SEEK_THR   8 * 1024
+#define CIC_SEEKY(cic) ((cic)->seek_mean > CIC_SEEK_THR)
+
 static inline int cfq_rq_close(struct cfq_data *cfqd, struct request *rq)
 {
        struct cfq_io_context *cic = cfqd->active_cic;
+       sector_t sdist = cic->seek_mean;
 
        if (!sample_valid(cic->seek_samples))
-               return 0;
+               sdist = CIC_SEEK_THR;
 
-       return cfq_dist_from_last(cfqd, rq) <= cic->seek_mean;
+       return cfq_dist_from_last(cfqd, rq) <= sdist;
 }
 
 static struct cfq_queue *cfqq_close(struct cfq_data *cfqd,
                                    struct cfq_queue *cur_cfqq)
 {
-       struct rb_root *root = &cfqd->prio_trees[cur_cfqq->ioprio];
+       struct rb_root *root = &cfqd->prio_trees[cur_cfqq->org_ioprio];
        struct rb_node *parent, *node;
        struct cfq_queue *__cfqq;
        sector_t sector = cfqd->last_position;
@@ -972,8 +988,7 @@ static struct cfq_queue *cfqq_close(struct cfq_data *cfqd,
         * First, if we find a request starting at the end of the last
         * request, choose it.
         */
-       __cfqq = cfq_prio_tree_lookup(cfqd, cur_cfqq->ioprio,
-                                     sector, &parent, NULL);
+       __cfqq = cfq_prio_tree_lookup(cfqd, root, sector, &parent, NULL);
        if (__cfqq)
                return __cfqq;
 
@@ -985,7 +1000,7 @@ static struct cfq_queue *cfqq_close(struct cfq_data *cfqd,
        if (cfq_rq_close(cfqd, __cfqq->next_rq))
                return __cfqq;
 
-       if (__cfqq->next_rq->sector < sector)
+       if (blk_rq_pos(__cfqq->next_rq) < sector)
                node = rb_next(&__cfqq->p_node);
        else
                node = rb_prev(&__cfqq->p_node);
@@ -1039,9 +1054,6 @@ static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd,
        return cfqq;
 }
 
-
-#define CIC_SEEKY(cic) ((cic)->seek_mean > (8 * 1024))
-
 static void cfq_arm_slice_timer(struct cfq_data *cfqd)
 {
        struct cfq_queue *cfqq = cfqd->active_queue;
@@ -1068,7 +1080,7 @@ static void cfq_arm_slice_timer(struct cfq_data *cfqd)
        /*
         * still requests with the driver, don't idle
         */
-       if (cfqd->rq_in_driver)
+       if (rq_in_driver(cfqd))
                return;
 
        /*
@@ -1103,6 +1115,7 @@ static void cfq_dispatch_insert(struct request_queue *q, struct request *rq)
 
        cfq_log_cfqq(cfqd, cfqq, "dispatch_insert");
 
+       cfqq->next_rq = cfq_find_next_rq(cfqd, cfqq, rq);
        cfq_remove_request(rq);
        cfqq->dispatched++;
        elv_dispatch_sort(q, rq);
@@ -1167,20 +1180,6 @@ static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
                goto expire;
 
        /*
-        * If we have a RT cfqq waiting, then we pre-empt the current non-rt
-        * cfqq.
-        */
-       if (!cfq_class_rt(cfqq) && cfqd->busy_rt_queues) {
-               /*
-                * We simulate this as cfqq timed out so that it gets to bank
-                * the remaining of its time slice.
-                */
-               cfq_log_cfqq(cfqd, cfqq, "preempt");
-               cfq_slice_expired(cfqd, 1);
-               goto new_queue;
-       }
-
-       /*
         * The active queue has requests and isn't expired, allow it to
         * dispatch.
         */
@@ -1245,7 +1244,7 @@ static int cfq_forced_dispatch(struct cfq_data *cfqd)
 
        BUG_ON(cfqd->busy_queues);
 
-       cfq_log(cfqd, "forced_dispatch=%d\n", dispatched);
+       cfq_log(cfqd, "forced_dispatch=%d", dispatched);
        return dispatched;
 }
 
@@ -1274,7 +1273,7 @@ static void cfq_dispatch_request(struct cfq_data *cfqd, struct cfq_queue *cfqq)
        if (!cfqd->active_cic) {
                struct cfq_io_context *cic = RQ_CIC(rq);
 
-               atomic_inc(&cic->ioc->refcount);
+               atomic_long_inc(&cic->ioc->refcount);
                cfqd->active_cic = cic;
        }
 }
@@ -1300,6 +1299,12 @@ static int cfq_dispatch_requests(struct request_queue *q, int force)
                return 0;
 
        /*
+        * Drain async requests before we start sync IO
+        */
+       if (cfq_cfqq_idle_window(cfqq) && cfqd->rq_in_driver[BLK_RW_ASYNC])
+               return 0;
+
+       /*
         * If this is an async queue and we have sync IO in flight, let it wait
         */
        if (cfqd->sync_flight && !cfq_cfqq_sync(cfqq))
@@ -1326,13 +1331,31 @@ static int cfq_dispatch_requests(struct request_queue *q, int force)
                        return 0;
 
                /*
-                * we are the only queue, allow up to 4 times of 'quantum'
+                * Sole queue user, allow bigger slice
                 */
-               if (cfqq->dispatched >= 4 * max_dispatch)
-                       return 0;
+               max_dispatch *= 4;
        }
 
        /*
+        * Async queues must wait a bit before being allowed dispatch.
+        * We also ramp up the dispatch depth gradually for async IO,
+        * based on the last sync IO we serviced
+        */
+       if (!cfq_cfqq_sync(cfqq) && cfqd->cfq_latency) {
+               unsigned long last_sync = jiffies - cfqd->last_end_sync_rq;
+               unsigned int depth;
+
+               depth = last_sync / cfqd->cfq_slice[1];
+               if (!depth && !cfqq->dispatched)
+                       depth = 1;
+               if (depth < max_dispatch)
+                       max_dispatch = depth;
+       }
+
+       if (cfqq->dispatched >= max_dispatch)
+               return 0;
+
+       /*
         * Dispatch a request from this cfqq
         */
        cfq_dispatch_request(cfqd, cfqq);
@@ -1350,7 +1373,7 @@ static int cfq_dispatch_requests(struct request_queue *q, int force)
                cfq_slice_expired(cfqd, 0);
        }
 
-       cfq_log(cfqd, "dispatched a request");
+       cfq_log_cfqq(cfqd, cfqq, "dispatched a request");
        return 1;
 }
 
@@ -1376,7 +1399,7 @@ static void cfq_put_queue(struct cfq_queue *cfqq)
 
        if (unlikely(cfqd->active_queue == cfqq)) {
                __cfq_slice_expired(cfqd, cfqq, 0);
-               cfq_schedule_dispatch(cfqd);
+               cfq_schedule_dispatch(cfqd, 0);
        }
 
        kmem_cache_free(cfq_pool, cfqq);
@@ -1415,7 +1438,7 @@ static void cfq_cic_free_rcu(struct rcu_head *head)
        cic = container_of(head, struct cfq_io_context, rcu_head);
 
        kmem_cache_free(cfq_ioc_pool, cic);
-       elv_ioc_count_dec(ioc_count);
+       elv_ioc_count_dec(cfq_ioc_count);
 
        if (ioc_gone) {
                /*
@@ -1424,7 +1447,7 @@ static void cfq_cic_free_rcu(struct rcu_head *head)
                 * complete ioc_gone and set it back to NULL
                 */
                spin_lock(&ioc_gone_lock);
-               if (ioc_gone && !elv_ioc_count_read(ioc_count)) {
+               if (ioc_gone && !elv_ioc_count_read(cfq_ioc_count)) {
                        complete(ioc_gone);
                        ioc_gone = NULL;
                }
@@ -1471,7 +1494,7 @@ static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
 {
        if (unlikely(cfqq == cfqd->active_queue)) {
                __cfq_slice_expired(cfqd, cfqq, 0);
-               cfq_schedule_dispatch(cfqd);
+               cfq_schedule_dispatch(cfqd, 0);
        }
 
        cfq_put_queue(cfqq);
@@ -1550,7 +1573,7 @@ cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
                INIT_HLIST_NODE(&cic->cic_list);
                cic->dtor = cfq_free_io_context;
                cic->exit = cfq_exit_io_context;
-               elv_ioc_count_inc(ioc_count);
+               elv_ioc_count_inc(cfq_ioc_count);
        }
 
        return cic;
@@ -1634,6 +1657,26 @@ static void cfq_ioc_set_ioprio(struct io_context *ioc)
        ioc->ioprio_changed = 0;
 }
 
+static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
+                         pid_t pid, int is_sync)
+{
+       RB_CLEAR_NODE(&cfqq->rb_node);
+       RB_CLEAR_NODE(&cfqq->p_node);
+       INIT_LIST_HEAD(&cfqq->fifo);
+
+       atomic_set(&cfqq->ref, 0);
+       cfqq->cfqd = cfqd;
+
+       cfq_mark_cfqq_prio_changed(cfqq);
+
+       if (is_sync) {
+               if (!cfq_class_idle(cfqq))
+                       cfq_mark_cfqq_idle_window(cfqq);
+               cfq_mark_cfqq_sync(cfqq);
+       }
+       cfqq->pid = pid;
+}
+
 static struct cfq_queue *
 cfq_find_alloc_queue(struct cfq_data *cfqd, int is_sync,
                     struct io_context *ioc, gfp_t gfp_mask)
@@ -1646,56 +1689,40 @@ retry:
        /* cic always exists here */
        cfqq = cic_to_cfqq(cic, is_sync);
 
-       if (!cfqq) {
+       /*
+        * Always try a new alloc if we fell back to the OOM cfqq
+        * originally, since it should just be a temporary situation.
+        */
+       if (!cfqq || cfqq == &cfqd->oom_cfqq) {
+               cfqq = NULL;
                if (new_cfqq) {
                        cfqq = new_cfqq;
                        new_cfqq = NULL;
                } else if (gfp_mask & __GFP_WAIT) {
-                       /*
-                        * Inform the allocator of the fact that we will
-                        * just repeat this allocation if it fails, to allow
-                        * the allocator to do whatever it needs to attempt to
-                        * free memory.
-                        */
                        spin_unlock_irq(cfqd->queue->queue_lock);
                        new_cfqq = kmem_cache_alloc_node(cfq_pool,
-                                       gfp_mask | __GFP_NOFAIL | __GFP_ZERO,
+                                       gfp_mask | __GFP_ZERO,
                                        cfqd->queue->node);
                        spin_lock_irq(cfqd->queue->queue_lock);
-                       goto retry;
+                       if (new_cfqq)
+                               goto retry;
                } else {
                        cfqq = kmem_cache_alloc_node(cfq_pool,
                                        gfp_mask | __GFP_ZERO,
                                        cfqd->queue->node);
-                       if (!cfqq)
-                               goto out;
                }
 
-               RB_CLEAR_NODE(&cfqq->rb_node);
-               RB_CLEAR_NODE(&cfqq->p_node);
-               INIT_LIST_HEAD(&cfqq->fifo);
-
-               atomic_set(&cfqq->ref, 0);
-               cfqq->cfqd = cfqd;
-
-               cfq_mark_cfqq_prio_changed(cfqq);
-
-               cfq_init_prio_data(cfqq, ioc);
-
-               if (is_sync) {
-                       if (!cfq_class_idle(cfqq))
-                               cfq_mark_cfqq_idle_window(cfqq);
-                       cfq_mark_cfqq_sync(cfqq);
-               }
-               cfqq->pid = current->pid;
-               cfq_log_cfqq(cfqd, cfqq, "alloced");
+               if (cfqq) {
+                       cfq_init_cfqq(cfqd, cfqq, current->pid, is_sync);
+                       cfq_init_prio_data(cfqq, ioc);
+                       cfq_log_cfqq(cfqd, cfqq, "alloced");
+               } else
+                       cfqq = &cfqd->oom_cfqq;
        }
 
        if (new_cfqq)
                kmem_cache_free(cfq_pool, new_cfqq);
 
-out:
-       WARN_ON((gfp_mask & __GFP_WAIT) && !cfqq);
        return cfqq;
 }
 
@@ -1728,11 +1755,8 @@ cfq_get_queue(struct cfq_data *cfqd, int is_sync, struct io_context *ioc,
                cfqq = *async_cfqq;
        }
 
-       if (!cfqq) {
+       if (!cfqq)
                cfqq = cfq_find_alloc_queue(cfqd, is_sync, ioc, gfp_mask);
-               if (!cfqq)
-                       return NULL;
-       }
 
        /*
         * pin the queue now that it's allocated, scheduler exit will prune it
@@ -1908,10 +1932,12 @@ cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_io_context *cic,
        sector_t sdist;
        u64 total;
 
-       if (cic->last_request_pos < rq->sector)
-               sdist = rq->sector - cic->last_request_pos;
+       if (!cic->last_request_pos)
+               sdist = 0;
+       else if (cic->last_request_pos < blk_rq_pos(rq))
+               sdist = blk_rq_pos(rq) - cic->last_request_pos;
        else
-               sdist = cic->last_request_pos - rq->sector;
+               sdist = cic->last_request_pos - blk_rq_pos(rq);
 
        /*
         * Don't allow the seek distance to get too large from the
@@ -1948,7 +1974,7 @@ cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq,
        enable_idle = old_idle = cfq_cfqq_idle_window(cfqq);
 
        if (!atomic_read(&cic->ioc->nr_tasks) || !cfqd->cfq_slice_idle ||
-           (cfqd->hw_tag && CIC_SEEKY(cic)))
+           (!cfqd->cfq_latency && cfqd->hw_tag && CIC_SEEKY(cic)))
                enable_idle = 0;
        else if (sample_valid(cic->ttime_samples)) {
                if (cic->ttime_mean > cfqd->cfq_slice_idle)
@@ -2061,7 +2087,7 @@ cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
        cfq_update_io_seektime(cfqd, cic, rq);
        cfq_update_idle_window(cfqd, cfqq, cic);
 
-       cic->last_request_pos = rq->sector + rq->nr_sectors;
+       cic->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq);
 
        if (cfqq == cfqd->active_queue) {
                /*
@@ -2078,7 +2104,7 @@ cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
                        if (blk_rq_bytes(rq) > PAGE_CACHE_SIZE ||
                            cfqd->busy_queues > 1) {
                                del_timer(&cfqd->idle_slice_timer);
-                               blk_start_queueing(cfqd->queue);
+                       __blk_run_queue(cfqd->queue);
                        }
                        cfq_mark_cfqq_must_dispatch(cfqq);
                }
@@ -2090,7 +2116,7 @@ cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
                 * this new queue is RT and the current one is BE
                 */
                cfq_preempt_queue(cfqd, cfqq);
-               blk_start_queueing(cfqd->queue);
+               __blk_run_queue(cfqd->queue);
        }
 }
 
@@ -2115,11 +2141,11 @@ static void cfq_insert_request(struct request_queue *q, struct request *rq)
  */
 static void cfq_update_hw_tag(struct cfq_data *cfqd)
 {
-       if (cfqd->rq_in_driver > cfqd->rq_in_driver_peak)
-               cfqd->rq_in_driver_peak = cfqd->rq_in_driver;
+       if (rq_in_driver(cfqd) > cfqd->rq_in_driver_peak)
+               cfqd->rq_in_driver_peak = rq_in_driver(cfqd);
 
        if (cfqd->rq_queued <= CFQ_HW_QUEUE_MIN &&
-           cfqd->rq_in_driver <= CFQ_HW_QUEUE_MIN)
+           rq_in_driver(cfqd) <= CFQ_HW_QUEUE_MIN)
                return;
 
        if (cfqd->hw_tag_samples++ < 50)
@@ -2146,19 +2172,18 @@ static void cfq_completed_request(struct request_queue *q, struct request *rq)
 
        cfq_update_hw_tag(cfqd);
 
-       WARN_ON(!cfqd->rq_in_driver);
+       WARN_ON(!cfqd->rq_in_driver[sync]);
        WARN_ON(!cfqq->dispatched);
-       cfqd->rq_in_driver--;
+       cfqd->rq_in_driver[sync]--;
        cfqq->dispatched--;
 
        if (cfq_cfqq_sync(cfqq))
                cfqd->sync_flight--;
 
-       if (!cfq_class_idle(cfqq))
-               cfqd->last_end_request = now;
-
-       if (sync)
+       if (sync) {
                RQ_CIC(rq)->last_end_request = now;
+               cfqd->last_end_sync_rq = now;
+       }
 
        /*
         * If this is the active queue, check if it needs to be expired,
@@ -2185,8 +2210,8 @@ static void cfq_completed_request(struct request_queue *q, struct request *rq)
                        cfq_arm_slice_timer(cfqd);
        }
 
-       if (!cfqd->rq_in_driver)
-               cfq_schedule_dispatch(cfqd);
+       if (!rq_in_driver(cfqd))
+               cfq_schedule_dispatch(cfqd, 0);
 }
 
 /*
@@ -2217,8 +2242,7 @@ static void cfq_prio_boost(struct cfq_queue *cfqq)
 
 static inline int __cfq_may_queue(struct cfq_queue *cfqq)
 {
-       if ((cfq_cfqq_wait_request(cfqq) || cfq_cfqq_must_alloc(cfqq)) &&
-           !cfq_cfqq_must_alloc_slice(cfqq)) {
+       if (cfq_cfqq_wait_request(cfqq) && !cfq_cfqq_must_alloc_slice(cfqq)) {
                cfq_mark_cfqq_must_alloc_slice(cfqq);
                return ELV_MQUEUE_MUST;
        }
@@ -2299,17 +2323,12 @@ cfq_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask)
                goto queue_fail;
 
        cfqq = cic_to_cfqq(cic, is_sync);
-       if (!cfqq) {
+       if (!cfqq || cfqq == &cfqd->oom_cfqq) {
                cfqq = cfq_get_queue(cfqd, is_sync, cic->ioc, gfp_mask);
-
-               if (!cfqq)
-                       goto queue_fail;
-
                cic_set_cfqq(cic, cfqq, is_sync);
        }
 
        cfqq->allocated[rw]++;
-       cfq_clear_cfqq_must_alloc(cfqq);
        atomic_inc(&cfqq->ref);
 
        spin_unlock_irqrestore(q->queue_lock, flags);
@@ -2322,7 +2341,7 @@ queue_fail:
        if (cic)
                put_io_context(cic->ioc);
 
-       cfq_schedule_dispatch(cfqd);
+       cfq_schedule_dispatch(cfqd, 0);
        spin_unlock_irqrestore(q->queue_lock, flags);
        cfq_log(cfqd, "set_request fail");
        return 1;
@@ -2331,11 +2350,11 @@ queue_fail:
 static void cfq_kick_queue(struct work_struct *work)
 {
        struct cfq_data *cfqd =
-               container_of(work, struct cfq_data, unplug_work);
+               container_of(work, struct cfq_data, unplug_work.work);
        struct request_queue *q = cfqd->queue;
 
        spin_lock_irq(q->queue_lock);
-       blk_start_queueing(q);
+       __blk_run_queue(cfqd->queue);
        spin_unlock_irq(q->queue_lock);
 }
 
@@ -2385,7 +2404,7 @@ static void cfq_idle_slice_timer(unsigned long data)
 expire:
        cfq_slice_expired(cfqd, timed_out);
 out_kick:
-       cfq_schedule_dispatch(cfqd);
+       cfq_schedule_dispatch(cfqd, 0);
 out_cont:
        spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
 }
@@ -2393,7 +2412,7 @@ out_cont:
 static void cfq_shutdown_timer_wq(struct cfq_data *cfqd)
 {
        del_timer_sync(&cfqd->idle_slice_timer);
-       cancel_work_sync(&cfqd->unplug_work);
+       cancel_delayed_work_sync(&cfqd->unplug_work);
 }
 
 static void cfq_put_async_queues(struct cfq_data *cfqd)
@@ -2443,12 +2462,30 @@ static void cfq_exit_queue(struct elevator_queue *e)
 static void *cfq_init_queue(struct request_queue *q)
 {
        struct cfq_data *cfqd;
+       int i;
 
        cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL | __GFP_ZERO, q->node);
        if (!cfqd)
                return NULL;
 
        cfqd->service_tree = CFQ_RB_ROOT;
+
+       /*
+        * Not strictly needed (since RB_ROOT just clears the node and we
+        * zeroed cfqd on alloc), but better be safe in case someone decides
+        * to add magic to the rb code
+        */
+       for (i = 0; i < CFQ_PRIO_LISTS; i++)
+               cfqd->prio_trees[i] = RB_ROOT;
+
+       /*
+        * Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues.
+        * Grab a permanent reference to it, so that the normal code flow
+        * will not attempt to free it.
+        */
+       cfq_init_cfqq(cfqd, &cfqd->oom_cfqq, 1, 0);
+       atomic_inc(&cfqd->oom_cfqq.ref);
+
        INIT_LIST_HEAD(&cfqd->cic_list);
 
        cfqd->queue = q;
@@ -2457,9 +2494,8 @@ static void *cfq_init_queue(struct request_queue *q)
        cfqd->idle_slice_timer.function = cfq_idle_slice_timer;
        cfqd->idle_slice_timer.data = (unsigned long) cfqd;
 
-       INIT_WORK(&cfqd->unplug_work, cfq_kick_queue);
+       INIT_DELAYED_WORK(&cfqd->unplug_work, cfq_kick_queue);
 
-       cfqd->last_end_request = jiffies;
        cfqd->cfq_quantum = cfq_quantum;
        cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0];
        cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1];
@@ -2469,8 +2505,9 @@ static void *cfq_init_queue(struct request_queue *q)
        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_latency = 1;
        cfqd->hw_tag = 1;
-
+       cfqd->last_end_sync_rq = jiffies;
        return cfqd;
 }
 
@@ -2538,6 +2575,7 @@ 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_low_latency_show, cfqd->cfq_latency, 0);
 #undef SHOW_FUNCTION
 
 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV)                        \
@@ -2569,6 +2607,7 @@ 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_low_latency_store, &cfqd->cfq_latency, 0, 1, 0);
 #undef STORE_FUNCTION
 
 #define CFQ_ATTR(name) \
@@ -2584,6 +2623,7 @@ static struct elv_fs_entry cfq_attrs[] = {
        CFQ_ATTR(slice_async),
        CFQ_ATTR(slice_async_rq),
        CFQ_ATTR(slice_idle),
+       CFQ_ATTR(low_latency),
        __ATTR_NULL
 };
 
@@ -2643,7 +2683,7 @@ static void __exit cfq_exit(void)
         * this also protects us from entering cfq_slab_kill() with
         * pending RCU callbacks
         */
-       if (elv_ioc_count_read(ioc_count))
+       if (elv_ioc_count_read(cfq_ioc_count))
                wait_for_completion(&all_gone);
        cfq_slab_kill();
 }