Patched in Tegra support.

1 files changed, 83 insertions, 327 deletions

diff --git a/block/blk-ioc.c b/block/blk-ioc.c
index fab4cdd3f7b..6f9bbd97865 100644
--- a/block/blk-ioc.c
+++ b/block/blk-ioc.c
@@ -16,185 +16,52 @@
  */
 static struct kmem_cache *iocontext_cachep;
 
-/**
- * get_io_context - increment reference count to io_context
- * @ioc: io_context to get
- *
- * Increment reference count to @ioc.
- */
-void get_io_context(struct io_context *ioc)
-{
-        BUG_ON(atomic_long_read(&ioc->refcount) <= 0);
-        atomic_long_inc(&ioc->refcount);
-}
-EXPORT_SYMBOL(get_io_context);
-
-static void icq_free_icq_rcu(struct rcu_head *head)
-{
-        struct io_cq *icq = container_of(head, struct io_cq, __rcu_head);
-
-        kmem_cache_free(icq->__rcu_icq_cache, icq);
-}
-
-/* Exit an icq. Called with both ioc and q locked. */
-static void ioc_exit_icq(struct io_cq *icq)
-{
-        struct elevator_type *et = icq->q->elevator->type;
-
-        if (icq->flags & ICQ_EXITED)
-                return;
-
-        if (et->ops.elevator_exit_icq_fn)
-                et->ops.elevator_exit_icq_fn(icq);
-
-        icq->flags |= ICQ_EXITED;
-}
-
-/* Release an icq.  Called with both ioc and q locked. */
-static void ioc_destroy_icq(struct io_cq *icq)
-{
-        struct io_context *ioc = icq->ioc;
-        struct request_queue *q = icq->q;
-        struct elevator_type *et = q->elevator->type;
-
-        lockdep_assert_held(&ioc->lock);
-        lockdep_assert_held(q->queue_lock);
-
-        radix_tree_delete(&ioc->icq_tree, icq->q->id);
-        hlist_del_init(&icq->ioc_node);
-        list_del_init(&icq->q_node);
-
-        /*
-         * 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->icq_hint) == icq)
-                rcu_assign_pointer(ioc->icq_hint, NULL);
-
-        ioc_exit_icq(icq);
-
-        /*
-         * @icq->q might have gone away by the time RCU callback runs
-         * making it impossible to determine icq_cache.  Record it in @icq.
-         */
-        icq->__rcu_icq_cache = et->icq_cache;
-        call_rcu(&icq->__rcu_head, icq_free_icq_rcu);
-}
-
-/*
- * Slow path for ioc release in put_io_context().  Performs double-lock
- * dancing to unlink all icq's and then frees ioc.
- */
-static void ioc_release_fn(struct work_struct *work)
+static void cfq_dtor(struct io_context *ioc)
 {
-        struct io_context *ioc = container_of(work, struct io_context,
-                                              release_work);
-        unsigned long flags;
+        if (!hlist_empty(&ioc->cic_list)) {
+                struct cfq_io_context *cic;
 
-        /*
-         * Exiting icq may call into put_io_context() through elevator
-         * which will trigger lockdep warning.  The ioc's are guaranteed to
-         * be different, use a different locking subclass here.  Use
-         * irqsave variant as there's no spin_lock_irq_nested().
-         */
-        spin_lock_irqsave_nested(&ioc->lock, flags, 1);
-
-        while (!hlist_empty(&ioc->icq_list)) {
-                struct io_cq *icq = hlist_entry(ioc->icq_list.first,
-                                                struct io_cq, ioc_node);
-                struct request_queue *q = icq->q;
-
-                if (spin_trylock(q->queue_lock)) {
-                        ioc_destroy_icq(icq);
-                        spin_unlock(q->queue_lock);
-                } else {
-                        spin_unlock_irqrestore(&ioc->lock, flags);
-                        cpu_relax();
-                        spin_lock_irqsave_nested(&ioc->lock, flags, 1);
-                }
+                cic = hlist_entry(ioc->cic_list.first, struct cfq_io_context,
+                                                                cic_list);
+                cic->dtor(ioc);
         }
-
-        spin_unlock_irqrestore(&ioc->lock, flags);
-
-        kmem_cache_free(iocontext_cachep, ioc);
 }
 
-/**
- * put_io_context - put a reference of io_context
- * @ioc: io_context to put
- *
- * Decrement reference count of @ioc and release it if the count reaches
- * zero.
+/*
+ * IO Context helper functions. put_io_context() returns 1 if there are no
+ * more users of this io context, 0 otherwise.
  */
-void put_io_context(struct io_context *ioc)
+int put_io_context(struct io_context *ioc)
 {
-        unsigned long flags;
-        bool free_ioc = false;
-
         if (ioc == NULL)
-                return;
+                return 1;
 
-        BUG_ON(atomic_long_read(&ioc->refcount) <= 0);
+        BUG_ON(atomic_long_read(&ioc->refcount) == 0);
 
-        /*
-         * Releasing ioc requires reverse order double locking and we may
-         * already be holding a queue_lock.  Do it asynchronously from wq.
-         */
         if (atomic_long_dec_and_test(&ioc->refcount)) {
-                spin_lock_irqsave(&ioc->lock, flags);
-                if (!hlist_empty(&ioc->icq_list))
-                        schedule_work(&ioc->release_work);
-                else
-                        free_ioc = true;
-                spin_unlock_irqrestore(&ioc->lock, flags);
-        }
+                rcu_read_lock();
+                cfq_dtor(ioc);
+                rcu_read_unlock();
 
-        if (free_ioc)
                 kmem_cache_free(iocontext_cachep, ioc);
+                return 1;
+        }
+        return 0;
 }
 EXPORT_SYMBOL(put_io_context);
 
-/**
- * put_io_context_active - put active reference on ioc
- * @ioc: ioc of interest
- *
- * Undo get_io_context_active().  If active reference reaches zero after
- * put, @ioc can never issue further IOs and ioscheds are notified.
- */
-void put_io_context_active(struct io_context *ioc)
+static void cfq_exit(struct io_context *ioc)
 {
-        struct hlist_node *n;
-        unsigned long flags;
-        struct io_cq *icq;
+        rcu_read_lock();
 
-        if (!atomic_dec_and_test(&ioc->active_ref)) {
-                put_io_context(ioc);
-                return;
-        }
+        if (!hlist_empty(&ioc->cic_list)) {
+                struct cfq_io_context *cic;
 
-        /*
-         * Need ioc lock to walk icq_list and q lock to exit icq.  Perform
-         * reverse double locking.  Read comment in ioc_release_fn() for
-         * explanation on the nested locking annotation.
-         */
-retry:
-        spin_lock_irqsave_nested(&ioc->lock, flags, 1);
-        hlist_for_each_entry(icq, n, &ioc->icq_list, ioc_node) {
-                if (icq->flags & ICQ_EXITED)
-                        continue;
-                if (spin_trylock(icq->q->queue_lock)) {
-                        ioc_exit_icq(icq);
-                        spin_unlock(icq->q->queue_lock);
-                } else {
-                        spin_unlock_irqrestore(&ioc->lock, flags);
-                        cpu_relax();
-                        goto retry;
-                }
+                cic = hlist_entry(ioc->cic_list.first, struct cfq_io_context,
+                                                                cic_list);
+                cic->exit(ioc);
         }
-        spin_unlock_irqrestore(&ioc->lock, flags);
-
-        put_io_context(ioc);
+        rcu_read_unlock();
 }
 
 /* Called by the exiting task */
@@ -207,197 +74,86 @@ void exit_io_context(struct task_struct *task)
         task->io_context = NULL;
         task_unlock(task);
 
-        atomic_dec(&ioc->nr_tasks);
-        put_io_context_active(ioc);
-}
+        if (atomic_dec_and_test(&ioc->nr_tasks))
+                cfq_exit(ioc);
 
-/**
- * ioc_clear_queue - break any ioc association with the specified queue
- * @q: request_queue being cleared
- *
- * Walk @q->icq_list and exit all io_cq's.  Must be called with @q locked.
- */
-void ioc_clear_queue(struct request_queue *q)
-{
-        lockdep_assert_held(q->queue_lock);
-
-        while (!list_empty(&q->icq_list)) {
-                struct io_cq *icq = list_entry(q->icq_list.next,
-                                               struct io_cq, q_node);
-                struct io_context *ioc = icq->ioc;
-
-                spin_lock(&ioc->lock);
-                ioc_destroy_icq(icq);
-                spin_unlock(&ioc->lock);
-        }
+        put_io_context(ioc);
 }
 
-int create_task_io_context(struct task_struct *task, gfp_t gfp_flags, int node)
+struct io_context *alloc_io_context(gfp_t gfp_flags, int node)
 {
         struct io_context *ioc;
-        int ret;
-
-        ioc = kmem_cache_alloc_node(iocontext_cachep, gfp_flags | __GFP_ZERO,
-                                    node);
-        if (unlikely(!ioc))
-                return -ENOMEM;
-
-        /* initialize */
-        atomic_long_set(&ioc->refcount, 1);
-        atomic_set(&ioc->nr_tasks, 1);
-        atomic_set(&ioc->active_ref, 1);
-        spin_lock_init(&ioc->lock);
-        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.  ioc shouldn't be installed if someone else
-         * already did or @task, which isn't %current, is exiting.  Note
-         * that we need to allow ioc creation on exiting %current as exit
-         * path may issue IOs from e.g. exit_files().  The exit path is
-         * responsible for not issuing IO after exit_io_context().
-         */
-        task_lock(task);
-        if (!task->io_context &&
-            (task == current || !(task->flags & PF_EXITING)))
-                task->io_context = ioc;
-        else
-                kmem_cache_free(iocontext_cachep, ioc);
-
-        ret = task->io_context ? 0 : -EBUSY;
-
-        task_unlock(task);
+        ioc = kmem_cache_alloc_node(iocontext_cachep, gfp_flags, node);
+        if (ioc) {
+                atomic_long_set(&ioc->refcount, 1);
+                atomic_set(&ioc->nr_tasks, 1);
+                spin_lock_init(&ioc->lock);
+                ioc->ioprio_changed = 0;
+                ioc->ioprio = 0;
+                ioc->last_waited = 0; /* doesn't matter... */
+                ioc->nr_batch_requests = 0; /* because this is 0 */
+                INIT_RADIX_TREE(&ioc->radix_root, GFP_ATOMIC | __GFP_HIGH);
+                INIT_HLIST_HEAD(&ioc->cic_list);
+                ioc->ioc_data = NULL;
+#if defined(CONFIG_BLK_CGROUP) || defined(CONFIG_BLK_CGROUP_MODULE)
+                ioc->cgroup_changed = 0;
+#endif
+        }
 
-        return ret;
+        return ioc;
 }
 
-/**
- * get_task_io_context - get io_context of a task
- * @task: task of interest
- * @gfp_flags: allocation flags, used if allocation is necessary
- * @node: allocation node, used if allocation is necessary
- *
- * Return io_context of @task.  If it doesn't exist, it is created with
- * @gfp_flags and @node.  The returned io_context has its reference count
- * incremented.
+/*
+ * If the current task has no IO context then create one and initialise it.
+ * Otherwise, return its existing IO context.
  *
- * This function always goes through task_lock() and it's better to use
- * %current->io_context + get_io_context() for %current.
+ * This returned IO context doesn't have a specifically elevated refcount,
+ * but since the current task itself holds a reference, the context can be
+ * used in general code, so long as it stays within `current` context.
  */
-struct io_context *get_task_io_context(struct task_struct *task,
-                                       gfp_t gfp_flags, int node)
+struct io_context *current_io_context(gfp_t gfp_flags, int node)
 {
-        struct io_context *ioc;
-
-        might_sleep_if(gfp_flags & __GFP_WAIT);
-
-        do {
-                task_lock(task);
-                ioc = task->io_context;
-                if (likely(ioc)) {
-                        get_io_context(ioc);
-                        task_unlock(task);
-                        return ioc;
-                }
-                task_unlock(task);
-        } while (!create_task_io_context(task, gfp_flags, node));
+        struct task_struct *tsk = current;
+        struct io_context *ret;
+
+        ret = tsk->io_context;
+        if (likely(ret))
+                return ret;
+
+        ret = alloc_io_context(gfp_flags, node);
+        if (ret) {
+                /* make sure set_task_ioprio() sees the settings above */
+                smp_wmb();
+                tsk->io_context = ret;
+        }
 
-        return NULL;
+        return ret;
 }
-EXPORT_SYMBOL(get_task_io_context);
 
-/**
- * ioc_lookup_icq - lookup io_cq from ioc
- * @ioc: the associated io_context
- * @q: the associated request_queue
+/*
+ * If the current task has no IO context then create one and initialise it.
+ * If it does have a context, take a ref on it.
  *
- * Look up io_cq associated with @ioc - @q pair from @ioc.  Must be called
- * with @q->queue_lock held.
+ * This is always called in the context of the task which submitted the I/O.
  */
-struct io_cq *ioc_lookup_icq(struct io_context *ioc, struct request_queue *q)
+struct io_context *get_io_context(gfp_t gfp_flags, int node)
 {
-        struct io_cq *icq;
-
-        lockdep_assert_held(q->queue_lock);
+        struct io_context *ioc = NULL;
 
         /*
-         * icq's are indexed from @ioc using radix tree and hint pointer,
-         * both of which are protected with RCU.  All removals are done
-         * holding both q and ioc locks, and we're holding q lock - if we
-         * find a icq which points to us, it's guaranteed to be valid.
+         * Check for unlikely race with exiting task. ioc ref count is
+         * zero when ioc is being detached.
          */
-        rcu_read_lock();
-        icq = rcu_dereference(ioc->icq_hint);
-        if (icq && icq->q == q)
-                goto out;
-
-        icq = radix_tree_lookup(&ioc->icq_tree, q->id);
-        if (icq && icq->q == q)
-                rcu_assign_pointer(ioc->icq_hint, icq); /* allowed to race */
-        else
-                icq = NULL;
-out:
-        rcu_read_unlock();
-        return icq;
-}
-EXPORT_SYMBOL(ioc_lookup_icq);
-
-/**
- * ioc_create_icq - create and link io_cq
- * @ioc: io_context of interest
- * @q: request_queue of interest
- * @gfp_mask: allocation mask
- *
- * Make sure io_cq linking @ioc and @q exists.  If icq doesn't exist, they
- * will be created using @gfp_mask.
- *
- * The caller is responsible for ensuring @ioc won't go away and @q is
- * alive and will stay alive until this function returns.
- */
-struct io_cq *ioc_create_icq(struct io_context *ioc, struct request_queue *q,
-                             gfp_t gfp_mask)
-{
-        struct elevator_type *et = q->elevator->type;
-        struct io_cq *icq;
-
-        /* allocate stuff */
-        icq = kmem_cache_alloc_node(et->icq_cache, gfp_mask | __GFP_ZERO,
-                                    q->node);
-        if (!icq)
-                return NULL;
-
-        if (radix_tree_preload(gfp_mask) < 0) {
-                kmem_cache_free(et->icq_cache, icq);
-                return NULL;
-        }
-
-        icq->ioc = ioc;
-        icq->q = q;
-        INIT_LIST_HEAD(&icq->q_node);
-        INIT_HLIST_NODE(&icq->ioc_node);
-
-        /* lock both q and ioc and try to link @icq */
-        spin_lock_irq(q->queue_lock);
-        spin_lock(&ioc->lock);
-
-        if (likely(!radix_tree_insert(&ioc->icq_tree, q->id, icq))) {
-                hlist_add_head(&icq->ioc_node, &ioc->icq_list);
-                list_add(&icq->q_node, &q->icq_list);
-                if (et->ops.elevator_init_icq_fn)
-                        et->ops.elevator_init_icq_fn(icq);
-        } else {
-                kmem_cache_free(et->icq_cache, icq);
-                icq = ioc_lookup_icq(ioc, q);
-                if (!icq)
-                        printk(KERN_ERR "cfq: icq link failed!\n");
-        }
+        do {
+                ioc = current_io_context(gfp_flags, node);
+                if (unlikely(!ioc))
+                        break;
+        } while (!atomic_long_inc_not_zero(&ioc->refcount));
 
-        spin_unlock(&ioc->lock);
-        spin_unlock_irq(q->queue_lock);
-        radix_tree_preload_end();
-        return icq;
+        return ioc;
 }
+EXPORT_SYMBOL(get_io_context);
 
 static int __init blk_ioc_init(void)
 {