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block/bfq-cgroup.c | 767 +++++++++++++++++
block/bfq-ioc.c | 375 +++++++++
block/bfq-iosched.c | 2279 +++++++++++++++++++++++++++++++++++++++++++++++++++
block/bfq-sched.c | 1010 +++++++++++++++++++++++
block/bfq.h | 550 +++++++++++++
5 files changed, 4981 insertions(+), 0 deletions(-)
create mode 100644 block/bfq-cgroup.c
create mode 100644 block/bfq-ioc.c
create mode 100644 block/bfq-iosched.c
create mode 100644 block/bfq-sched.c
create mode 100644 block/bfq.h
diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c
new file mode 100644
index 0000000..9b2e0d1
--- /dev/null
+++ b/block/bfq-cgroup.c
@@ -0,0 +1,767 @@
+/*
+ * BFQ: CGROUPS support.
+ *
+ * Based on ideas and code from CFQ:
+ * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
+ *
+ * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
+ * Paolo Valente <paolo.valente@unimore.it>
+ */
+
+#ifdef CONFIG_CGROUP_BFQIO
+static struct bfqio_cgroup bfqio_root_cgroup = {
+ .weight = BFQ_DEFAULT_GRP_WEIGHT,
+ .ioprio = BFQ_DEFAULT_GRP_IOPRIO,
+ .ioprio_class = BFQ_DEFAULT_GRP_CLASS,
+};
+
+static inline void bfq_init_entity(struct bfq_entity *entity,
+ struct bfq_group *bfqg)
+{
+ entity->weight = entity->new_weight;
+ entity->orig_weight = entity->new_weight;
+ entity->ioprio = entity->new_ioprio;
+ entity->ioprio_class = entity->new_ioprio_class;
+ entity->parent = bfqg->my_entity;
+ entity->sched_data = &bfqg->sched_data;
+}
+
+static struct bfqio_cgroup *cgroup_to_bfqio(struct cgroup *cgroup)
+{
+ return container_of(cgroup_subsys_state(cgroup, bfqio_subsys_id),
+ struct bfqio_cgroup, css);
+}
+
+/*
+ * Search the bfq_group for bfqd into the hash table (by now only a list)
+ * of bgrp. Must be called under rcu_read_lock().
+ */
+static struct bfq_group *bfqio_lookup_group(struct bfqio_cgroup *bgrp,
+ struct bfq_data *bfqd)
+{
+ struct bfq_group *bfqg;
+ struct hlist_node *n;
+ void *key;
+
+ hlist_for_each_entry_rcu(bfqg, n, &bgrp->group_data, group_node) {
+ key = rcu_dereference(bfqg->bfqd);
+ if (key == bfqd)
+ return bfqg;
+ }
+
+ return NULL;
+}
+
+static inline void bfq_group_init_entity(struct bfqio_cgroup *bgrp,
+ struct bfq_group *bfqg)
+{
+ struct bfq_entity *entity = &bfqg->entity;
+
+ entity->weight = entity->new_weight = bgrp->weight;
+ entity->orig_weight = entity->new_weight;
+ entity->ioprio = entity->new_ioprio = bgrp->ioprio;
+ entity->ioprio_class = entity->new_ioprio_class = bgrp->ioprio_class;
+ entity->ioprio_changed = 1;
+ entity->my_sched_data = &bfqg->sched_data;
+}
+
+static inline void bfq_group_set_parent(struct bfq_group *bfqg,
+ struct bfq_group *parent)
+{
+ struct bfq_entity *entity;
+
+ BUG_ON(parent == NULL);
+ BUG_ON(bfqg == NULL);
+
+ entity = &bfqg->entity;
+ entity->parent = parent->my_entity;
+ entity->sched_data = &parent->sched_data;
+}
+
+/**
+ * bfq_group_chain_alloc - allocate a chain of groups.
+ * @bfqd: queue descriptor.
+ * @cgroup: the leaf cgroup this chain starts from.
+ *
+ * Allocate a chain of groups starting from the one belonging to
+ * @cgroup up to the root cgroup. Stop if a cgroup on the chain
+ * to the root has already an allocated group on @bfqd.
+ */
+static struct bfq_group *bfq_group_chain_alloc(struct bfq_data *bfqd,
+ struct cgroup *cgroup)
+{
+ struct bfqio_cgroup *bgrp;
+ struct bfq_group *bfqg, *prev = NULL, *leaf = NULL;
+
+ for (; cgroup != NULL; cgroup = cgroup->parent) {
+ bgrp = cgroup_to_bfqio(cgroup);
+
+ bfqg = bfqio_lookup_group(bgrp, bfqd);
+ if (bfqg != NULL) {
+ /*
+ * All the cgroups in the path from there to the
+ * root must have a bfq_group for bfqd, so we don't
+ * need any more allocations.
+ */
+ break;
+ }
+
+ bfqg = kzalloc(sizeof(*bfqg), GFP_ATOMIC);
+ if (bfqg == NULL)
+ goto cleanup;
+
+ bfq_group_init_entity(bgrp, bfqg);
+ bfqg->my_entity = &bfqg->entity;
+
+ if (leaf == NULL) {
+ leaf = bfqg;
+ prev = leaf;
+ } else {
+ bfq_group_set_parent(prev, bfqg);
+ /*
+ * Build a list of allocated nodes using the bfqd
+ * filed, that is still unused and will be initialized
+ * only after the node will be connected.
+ */
+ prev->bfqd = bfqg;
+ prev = bfqg;
+ }
+ }
+
+ return leaf;
+
+cleanup:
+ while (leaf != NULL) {
+ prev = leaf;
+ leaf = leaf->bfqd;
+ kfree(prev);
+ }
+
+ return NULL;
+}
+
+/**
+ * bfq_group_chain_link - link an allocatd group chain to a cgroup hierarchy.
+ * @bfqd: the queue descriptor.
+ * @cgroup: the leaf cgroup to start from.
+ * @leaf: the leaf group (to be associated to @cgroup).
+ *
+ * Try to link a chain of groups to a cgroup hierarchy, connecting the
+ * nodes bottom-up, so we can be sure that when we find a cgroup in the
+ * hierarchy that already as a group associated to @bfqd all the nodes
+ * in the path to the root cgroup have one too.
+ *
+ * On locking: the queue lock protects the hierarchy (there is a hierarchy
+ * per device) while the bfqio_cgroup lock protects the list of groups
+ * belonging to the same cgroup.
+ */
+static void bfq_group_chain_link(struct bfq_data *bfqd, struct cgroup *cgroup,
+ struct bfq_group *leaf)
+{
+ struct bfqio_cgroup *bgrp;
+ struct bfq_group *bfqg, *next, *prev = NULL;
+ unsigned long flags;
+
+ assert_spin_locked(bfqd->queue->queue_lock);
+
+ for (; cgroup != NULL && leaf != NULL; cgroup = cgroup->parent) {
+ bgrp = cgroup_to_bfqio(cgroup);
+ next = leaf->bfqd;
+
+ bfqg = bfqio_lookup_group(bgrp, bfqd);
+ BUG_ON(bfqg != NULL);
+
+ spin_lock_irqsave(&bgrp->lock, flags);
+
+ rcu_assign_pointer(leaf->bfqd, bfqd);
+ hlist_add_head_rcu(&leaf->group_node, &bgrp->group_data);
+ hlist_add_head(&leaf->bfqd_node, &bfqd->group_list);
+
+ spin_unlock_irqrestore(&bgrp->lock, flags);
+
+ prev = leaf;
+ leaf = next;
+ }
+
+ BUG_ON(cgroup == NULL && leaf != NULL);
+ if (cgroup != NULL && prev != NULL) {
+ bgrp = cgroup_to_bfqio(cgroup);
+ bfqg = bfqio_lookup_group(bgrp, bfqd);
+ bfq_group_set_parent(prev, bfqg);
+ }
+}
+
+/**
+ * bfq_find_alloc_group - return the group associated to @bfqd in @cgroup.
+ * @bfqd: queue descriptor.
+ * @cgroup: cgroup being searched for.
+ *
+ * Return a group associated to @bfqd in @cgroup, allocating one if
+ * necessary. When a group is returned all the cgroups in the path
+ * to the root have a group associated to @bfqd.
+ *
+ * If the allocation fails, return the root group: this breaks guarantees
+ * but is a safe fallbak. If this loss becames a problem it can be
+ * mitigated using the equivalent weight (given by the product of the
+ * weights of the groups in the path from @group to the root) in the
+ * root scheduler.
+ *
+ * We allocate all the missing nodes in the path from the leaf cgroup
+ * to the root and we connect the nodes only after all the allocations
+ * have been successful.
+ */
+static struct bfq_group *bfq_find_alloc_group(struct bfq_data *bfqd,
+ struct cgroup *cgroup)
+{
+ struct bfqio_cgroup *bgrp = cgroup_to_bfqio(cgroup);
+ struct bfq_group *bfqg;
+
+ bfqg = bfqio_lookup_group(bgrp, bfqd);
+ if (bfqg != NULL)
+ return bfqg;
+
+ bfqg = bfq_group_chain_alloc(bfqd, cgroup);
+ if (bfqg != NULL)
+ bfq_group_chain_link(bfqd, cgroup, bfqg);
+ else
+ bfqg = bfqd->root_group;
+
+ return bfqg;
+}
+
+/**
+ * bfq_bfqq_move - migrate @bfqq to @bfqg.
+ * @bfqd: queue descriptor.
+ * @bfqq: the queue to move.
+ * @entity: @bfqq's entity.
+ * @bfqg: the group to move to.
+ *
+ * Move @bfqq to @bfqg, deactivating it from its old group and reactivating
+ * it on the new one. Avoid putting the entity on the old group idle tree.
+ *
+ * Must be called under the queue lock; the cgroup owning @bfqg must
+ * not disappear (by now this just means that we are called under
+ * rcu_read_lock()).
+ */
+static void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq,
+ struct bfq_entity *entity, struct bfq_group *bfqg)
+{
+ int busy, resume;
+
+ busy = bfq_bfqq_busy(bfqq);
+ resume = !RB_EMPTY_ROOT(&bfqq->sort_list);
+
+ BUG_ON(resume && !entity->on_st);
+ BUG_ON(busy && !resume && entity->on_st && bfqq != bfqd->active_queue);
+
+ if (busy) {
+ BUG_ON(atomic_read(&bfqq->ref) < 2);
+
+ if (!resume)
+ bfq_del_bfqq_busy(bfqd, bfqq, 0);
+ else
+ bfq_deactivate_bfqq(bfqd, bfqq, 0);
+ }
+
+ /*
+ * Here we use a reference to bfqg. We don't need a refcounter
+ * as the cgroup reference will not be dropped, so that its
+ * destroy() callback will not be invoked.
+ */
+ entity->parent = bfqg->my_entity;
+ entity->sched_data = &bfqg->sched_data;
+
+ if (busy && resume)
+ bfq_activate_bfqq(bfqd, bfqq);
+}
+
+/**
+ * __bfq_cic_change_cgroup - move @cic to @cgroup.
+ * @bfqd: the queue descriptor.
+ * @cic: the cic to move.
+ * @cgroup: the cgroup to move to.
+ *
+ * Move cic to cgroup, assuming that bfqd->queue is locked; the caller
+ * has to make sure that the reference to cgroup is valid across the call.
+ *
+ * NOTE: an alternative approach might have been to store the current
+ * cgroup in bfqq and getting a reference to it, reducing the lookup
+ * time here, at the price of slightly more complex code.
+ */
+static struct bfq_group *__bfq_cic_change_cgroup(struct bfq_data *bfqd,
+ struct cfq_io_context *cic,
+ struct cgroup *cgroup)
+{
+ struct bfq_queue *async_bfqq = cic_to_bfqq(cic, 0);
+ struct bfq_queue *sync_bfqq = cic_to_bfqq(cic, 1);
+ struct bfq_entity *entity;
+ struct bfq_group *bfqg;
+ struct bfqio_cgroup *bgrp;
+
+ bgrp = cgroup_to_bfqio(cgroup);
+
+ bfqg = bfq_find_alloc_group(bfqd, cgroup);
+ if (async_bfqq != NULL) {
+ entity = &async_bfqq->entity;
+
+ if (entity->sched_data != &bfqg->sched_data) {
+ cic_set_bfqq(cic, NULL, 0);
+ bfq_log_bfqq(bfqd, async_bfqq,
+ "cic_change_group: %p %d",
+ async_bfqq, async_bfqq->ref);
+ bfq_put_queue(async_bfqq);
+ }
+ }
+
+ if (sync_bfqq != NULL) {
+ entity = &sync_bfqq->entity;
+ if (entity->sched_data != &bfqg->sched_data)
+ bfq_bfqq_move(bfqd, sync_bfqq, entity, bfqg);
+ }
+
+ return bfqg;
+}
+
+/**
+ * bfq_cic_change_cgroup - move @cic to @cgroup.
+ * @cic: the cic being migrated.
+ * @cgroup: the destination cgroup.
+ *
+ * When the task owning @cic is moved to @cgroup, @cic is immediately
+ * moved into its new parent group.
+ */
+static void bfq_cic_change_cgroup(struct cfq_io_context *cic,
+ struct cgroup *cgroup)
+{
+ struct bfq_data *bfqd;
+ unsigned long uninitialized_var(flags);
+
+ bfqd = bfq_get_bfqd_locked(&cic->key, &flags);
+ if (bfqd != NULL) {
+ __bfq_cic_change_cgroup(bfqd, cic, cgroup);
+ bfq_put_bfqd_unlock(bfqd, &flags);
+ }
+}
+
+/**
+ * bfq_cic_update_cgroup - update the cgroup of @cic.
+ * @cic: the @cic to update.
+ *
+ * Make sure that @cic is enqueued in the cgroup of the current task.
+ * We need this in addition to moving cics during the cgroup attach
+ * phase because the task owning @cic could be at its first disk
+ * access or we may end up in the root cgroup as the result of a
+ * memory allocation failure and here we try to move to the right
+ * group.
+ *
+ * Must be called under the queue lock. It is safe to use the returned
+ * value even after the rcu_read_unlock() as the migration/destruction
+ * paths act under the queue lock too. IOW it is impossible to race with
+ * group migration/destruction and end up with an invalid group as:
+ * a) here cgroup has not yet been destroyed, nor its destroy callback
+ * has started execution, as current holds a reference to it,
+ * b) if it is destroyed after rcu_read_unlock() [after current is
+ * migrated to a different cgroup] its attach() callback will have
+ * taken care of remove all the references to the old cgroup data.
+ */
+static struct bfq_group *bfq_cic_update_cgroup(struct cfq_io_context *cic)
+{
+ struct bfq_data *bfqd = cic->key;
+ struct bfq_group *bfqg;
+ struct cgroup *cgroup;
+
+ BUG_ON(bfqd == NULL);
+
+ rcu_read_lock();
+ cgroup = task_cgroup(current, bfqio_subsys_id);
+ bfqg = __bfq_cic_change_cgroup(bfqd, cic, cgroup);
+ rcu_read_unlock();
+
+ return bfqg;
+}
+
+/**
+ * bfq_flush_idle_tree - deactivate any entity on the idle tree of @st.
+ * @st: the service tree being flushed.
+ */
+static inline void bfq_flush_idle_tree(struct bfq_service_tree *st)
+{
+ struct bfq_entity *entity = st->first_idle;
+
+ for (; entity != NULL; entity = st->first_idle)
+ __bfq_deactivate_entity(entity, 0);
+}
+
+/**
+ * bfq_destroy_group - destroy @bfqg.
+ * @bgrp: the bfqio_cgroup containing @bfqg.
+ * @bfqg: the group being destroyed.
+ *
+ * Destroy @bfqg, making sure that it is not referenced from its parent.
+ */
+static void bfq_destroy_group(struct bfqio_cgroup *bgrp, struct bfq_group *bfqg)
+{
+ struct bfq_data *bfqd;
+ struct bfq_service_tree *st;
+ struct bfq_entity *entity = bfqg->my_entity;
+ unsigned long uninitialized_var(flags);
+ int i;
+
+ hlist_del(&bfqg->group_node);
+
+ /*
+ * We may race with device destruction, take extra care when
+ * dereferencing bfqg->bfqd.
+ */
+ bfqd = bfq_get_bfqd_locked(&bfqg->bfqd, &flags);
+ if (bfqd != NULL) {
+ hlist_del(&bfqg->bfqd_node);
+ __bfq_deactivate_entity(entity, 0);
+ bfq_put_async_queues(bfqd, bfqg);
+ bfq_put_bfqd_unlock(bfqd, &flags);
+ }
+
+ for (i = 0; i < BFQ_IOPRIO_CLASSES; i++) {
+ st = bfqg->sched_data.service_tree + i;
+
+ /*
+ * The idle tree may still contain bfq_queues belonging
+ * to exited task because they never migrated to a different
+ * cgroup from the one being destroyed now. Noone else
+ * can access them so it's safe to act without any lock.
+ */
+ bfq_flush_idle_tree(st);
+
+ BUG_ON(!RB_EMPTY_ROOT(&st->active));
+ BUG_ON(!RB_EMPTY_ROOT(&st->idle));
+ }
+ BUG_ON(bfqg->sched_data.next_active != NULL);
+ BUG_ON(bfqg->sched_data.active_entity != NULL);
+ BUG_ON(entity->tree != NULL);
+
+ /*
+ * No need to defer the kfree() to the end of the RCU grace
+ * period: we are called from the destroy() callback of our
+ * cgroup, so we can be sure that noone is a) still using
+ * this cgroup or b) doing lookups in it.
+ */
+ kfree(bfqg);
+}
+
+/**
+ * bfq_disconnect_groups - diconnect @bfqd from all its groups.
+ * @bfqd: the device descriptor being exited.
+ *
+ * When the device exits we just make sure that no lookup can return
+ * the now unused group structures. They will be deallocated on cgroup
+ * destruction.
+ */
+static void bfq_disconnect_groups(struct bfq_data *bfqd)
+{
+ struct hlist_node *pos, *n;
+ struct bfq_group *bfqg;
+
+ bfq_log(bfqd, "disconnect_groups beginning") ;
+ hlist_for_each_entry_safe(bfqg, pos, n, &bfqd->group_list, bfqd_node) {
+ hlist_del(&bfqg->bfqd_node);
+
+ __bfq_deactivate_entity(bfqg->my_entity, 0);
+
+ /*
+ * Don't remove from the group hash, just set an
+ * invalid key. No lookups can race with the
+ * assignment as bfqd is being destroyed; this
+ * implies also that new elements cannot be added
+ * to the list.
+ */
+ rcu_assign_pointer(bfqg->bfqd, NULL);
+
+ bfq_log(bfqd, "disconnect_groups: put async for group %p",
+ bfqg) ;
+ bfq_put_async_queues(bfqd, bfqg);
+ }
+}
+
+static inline void bfq_free_root_group(struct bfq_data *bfqd)
+{
+ struct bfqio_cgroup *bgrp = &bfqio_root_cgroup;
+ struct bfq_group *bfqg = bfqd->root_group;
+
+ bfq_put_async_queues(bfqd, bfqg);
+
+ spin_lock_irq(&bgrp->lock);
+ hlist_del_rcu(&bfqg->group_node);
+ spin_unlock_irq(&bgrp->lock);
+
+ /*
+ * No need to synchronize_rcu() here: since the device is gone
+ * there cannot be any read-side access to its root_group.
+ */
+ kfree(bfqg);
+}
+
+static struct bfq_group *bfq_alloc_root_group(struct bfq_data *bfqd, int node)
+{
+ struct bfq_group *bfqg;
+ struct bfqio_cgroup *bgrp;
+ int i;
+
+ bfqg = kmalloc_node(sizeof(*bfqg), GFP_KERNEL | __GFP_ZERO, node);
+ if (bfqg == NULL)
+ return NULL;
+
+ bfqg->entity.parent = NULL;
+ for (i = 0; i < BFQ_IOPRIO_CLASSES; i++)
+ bfqg->sched_data.service_tree[i] = BFQ_SERVICE_TREE_INIT;
+
+ bgrp = &bfqio_root_cgroup;
+ spin_lock_irq(&bgrp->lock);
+ rcu_assign_pointer(bfqg->bfqd, bfqd);
+ hlist_add_head_rcu(&bfqg->group_node, &bgrp->group_data);
+ spin_unlock_irq(&bgrp->lock);
+
+ return bfqg;
+}
+
+#define SHOW_FUNCTION(__VAR) \
+static u64 bfqio_cgroup_##__VAR##_read(struct cgroup *cgroup, \
+ struct cftype *cftype) \
+{ \
+ struct bfqio_cgroup *bgrp; \
+ u64 ret; \
+ \
+ if (!cgroup_lock_live_group(cgroup)) \
+ return -ENODEV; \
+ \
+ bgrp = cgroup_to_bfqio(cgroup); \
+ spin_lock_irq(&bgrp->lock); \
+ ret = bgrp->__VAR; \
+ spin_unlock_irq(&bgrp->lock); \
+ \
+ cgroup_unlock(); \
+ \
+ return ret; \
+}
+
+SHOW_FUNCTION(weight);
+SHOW_FUNCTION(ioprio);
+SHOW_FUNCTION(ioprio_class);
+#undef SHOW_FUNCTION
+
+#define STORE_FUNCTION(__VAR, __MIN, __MAX) \
+static int bfqio_cgroup_##__VAR##_write(struct cgroup *cgroup, \
+ struct cftype *cftype, \
+ u64 val) \
+{ \
+ struct bfqio_cgroup *bgrp; \
+ struct bfq_group *bfqg; \
+ struct hlist_node *n; \
+ \
+ if (val < (__MIN) || val > (__MAX)) \
+ return -EINVAL; \
+ \
+ if (!cgroup_lock_live_group(cgroup)) \
+ return -ENODEV; \
+ \
+ bgrp = cgroup_to_bfqio(cgroup); \
+ \
+ spin_lock_irq(&bgrp->lock); \
+ bgrp->__VAR = (unsigned short)val; \
+ hlist_for_each_entry(bfqg, n, &bgrp->group_data, group_node) { \
+ bfqg->entity.new_##__VAR = (unsigned short)val; \
+ smp_wmb(); \
+ bfqg->entity.ioprio_changed = 1; \
+ } \
+ spin_unlock_irq(&bgrp->lock); \
+ \
+ cgroup_unlock(); \
+ \
+ return 0; \
+}
+
+STORE_FUNCTION(weight, BFQ_MIN_WEIGHT, BFQ_MAX_WEIGHT);
+STORE_FUNCTION(ioprio, 0, IOPRIO_BE_NR - 1);
+STORE_FUNCTION(ioprio_class, IOPRIO_CLASS_RT, IOPRIO_CLASS_IDLE);
+#undef STORE_FUNCTION
+
+static struct cftype bfqio_files[] = {
+ {
+ .name = "weight",
+ .read_u64 = bfqio_cgroup_weight_read,
+ .write_u64 = bfqio_cgroup_weight_write,
+ },
+ {
+ .name = "ioprio",
+ .read_u64 = bfqio_cgroup_ioprio_read,
+ .write_u64 = bfqio_cgroup_ioprio_write,
+ },
+ {
+ .name = "ioprio_class",
+ .read_u64 = bfqio_cgroup_ioprio_class_read,
+ .write_u64 = bfqio_cgroup_ioprio_class_write,
+ },
+};
+
+static int bfqio_populate(struct cgroup_subsys *subsys, struct cgroup *cgroup)
+{
+ return cgroup_add_files(cgroup, subsys, bfqio_files,
+ ARRAY_SIZE(bfqio_files));
+}
+
+static struct cgroup_subsys_state *bfqio_create(struct cgroup_subsys *subsys,
+ struct cgroup *cgroup)
+{
+ struct bfqio_cgroup *bgrp;
+
+ if (cgroup->parent != NULL) {
+ bgrp = kzalloc(sizeof(*bgrp), GFP_KERNEL);
+ if (bgrp == NULL)
+ return ERR_PTR(-ENOMEM);
+ } else
+ bgrp = &bfqio_root_cgroup;
+
+ spin_lock_init(&bgrp->lock);
+ INIT_HLIST_HEAD(&bgrp->group_data);
+ bgrp->ioprio = BFQ_DEFAULT_GRP_IOPRIO;
+ bgrp->ioprio_class = BFQ_DEFAULT_GRP_CLASS;
+
+ return &bgrp->css;
+}
+
+/*
+ * We cannot support shared io contexts, as we have no mean to support
+ * two tasks with the same ioc in two different groups without major rework
+ * of the main cic/bfqq data structures. By now we allow a task to change
+ * its cgroup only if it's the only owner of its ioc; the drawback of this
+ * behavior is that a group containing a task that forked using CLONE_IO
+ * will not be destroyed until the tasks sharing the ioc die.
+ */
+static int bfqio_can_attach(struct cgroup_subsys *subsys, struct cgroup *cgroup,
+ struct task_struct *tsk, bool threadgroup)
+{
+ struct io_context *ioc;
+ int ret = 0;
+
+ /* task_lock() is needed to avoid races with exit_io_context() */
+ task_lock(tsk);
+ ioc = tsk->io_context;
+ if (ioc != NULL && atomic_read(&ioc->nr_tasks) > 1)
+ /*
+ * ioc == NULL means that the task is either too young or
+ * exiting: if it has still no ioc the ioc can't be shared,
+ * if the task is exiting the attach will fail anyway, no
+ * matter what we return here.
+ */
+ ret = -EINVAL;
+ task_unlock(tsk);
+
+ return ret;
+}
+
+static void bfqio_attach(struct cgroup_subsys *subsys, struct cgroup *cgroup,
+ struct cgroup *prev, struct task_struct *tsk,
+ bool threadgroup)
+{
+ struct io_context *ioc;
+ struct cfq_io_context *cic;
+ struct hlist_node *n;
+
+ task_lock(tsk);
+ ioc = tsk->io_context;
+ if (ioc != NULL) {
+ BUG_ON(atomic_read(&ioc->refcount) == 0);
+ atomic_inc(&ioc->refcount);
+ }
+ task_unlock(tsk);
+
+ if (ioc == NULL)
+ return;
+
+ rcu_read_lock();
+ hlist_for_each_entry_rcu(cic, n, &ioc->bfq_cic_list, cic_list)
+ bfq_cic_change_cgroup(cic, cgroup);
+ rcu_read_unlock();
+
+ put_io_context(ioc);
+}
+
+static void bfqio_destroy(struct cgroup_subsys *subsys, struct cgroup *cgroup)
+{
+ struct bfqio_cgroup *bgrp = cgroup_to_bfqio(cgroup);
+ struct hlist_node *n, *tmp;
+ struct bfq_group *bfqg;
+
+ /*
+ * Since we are destroying the cgroup, there are no more tasks
+ * referencing it, and all the RCU grace periods that may have
+ * referenced it are ended (as the destruction of the parent
+ * cgroup is RCU-safe); bgrp->group_data will not be accessed by
+ * anything else and we don't need any synchronization.
+ */
+ hlist_for_each_entry_safe(bfqg, n, tmp, &bgrp->group_data, group_node)
+ bfq_destroy_group(bgrp, bfqg);
+
+ BUG_ON(!hlist_empty(&bgrp->group_data));
+
+ kfree(bgrp);
+}
+
+struct cgroup_subsys bfqio_subsys = {
+ .name = "bfqio",
+ .create = bfqio_create,
+ .can_attach = bfqio_can_attach,
+ .attach = bfqio_attach,
+ .destroy = bfqio_destroy,
+ .populate = bfqio_populate,
+ .subsys_id = bfqio_subsys_id,
+};
+#else
+static inline void bfq_init_entity(struct bfq_entity *entity,
+ struct bfq_group *bfqg)
+{
+ entity->weight = entity->new_weight;
+ entity->orig_weight = entity->new_weight;
+ entity->ioprio = entity->new_ioprio;
+ entity->ioprio_class = entity->new_ioprio_class;
+ entity->sched_data = &bfqg->sched_data;
+}
+
+static inline struct bfq_group *
+bfq_cic_update_cgroup(struct cfq_io_context *cic)
+{
+ struct bfq_data *bfqd = cic->key;
+ return bfqd->root_group;
+}
+
+static inline void bfq_bfqq_move(struct bfq_data *bfqd,
+ struct bfq_queue *bfqq,
+ struct bfq_entity *entity,
+ struct bfq_group *bfqg)
+{
+}
+
+static inline void bfq_disconnect_groups(struct bfq_data *bfqd)
+{
+ bfq_put_async_queues(bfqd, bfqd->root_group);
+}
+
+static inline void bfq_free_root_group(struct bfq_data *bfqd)
+{
+ kfree(bfqd->root_group);
+}
+
+static struct bfq_group *bfq_alloc_root_group(struct bfq_data *bfqd, int node)
+{
+ struct bfq_group *bfqg;
+ int i;
+
+ bfqg = kmalloc_node(sizeof(*bfqg), GFP_KERNEL | __GFP_ZERO, node);
+ if (bfqg == NULL)
+ return NULL;
+
+ for (i = 0; i < BFQ_IOPRIO_CLASSES; i++)
+ bfqg->sched_data.service_tree[i] = BFQ_SERVICE_TREE_INIT;
+
+ return bfqg;
+}
+#endif
diff --git a/block/bfq-ioc.c b/block/bfq-ioc.c
new file mode 100644
index 0000000..8b91d65
--- /dev/null
+++ b/block/bfq-ioc.c
@@ -0,0 +1,375 @@
+/*
+ * BFQ: I/O context handling.
+ *
+ * Based on ideas and code from CFQ:
+ * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
+ *
+ * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
+ * Paolo Valente <paolo.valente@unimore.it>
+ */
+
+/**
+ * bfq_cic_free_rcu - deferred cic freeing.
+ * @head: RCU head of the cic to free.
+ *
+ * Free the cic containing @head and, if it was the last one and
+ * the module is exiting wake up anyone waiting for its deallocation
+ * (see bfq_exit()).
+ */
+static void bfq_cic_free_rcu(struct rcu_head *head)
+{
+ struct cfq_io_context *cic;
+
+ cic = container_of(head, struct cfq_io_context, rcu_head);
+
+ kmem_cache_free(bfq_ioc_pool, cic);
+ elv_ioc_count_dec(bfq_ioc_count);
+
+ if (bfq_ioc_gone != NULL) {
+ spin_lock(&bfq_ioc_gone_lock);
+ if (bfq_ioc_gone != NULL &&
+ !elv_ioc_count_read(bfq_ioc_count)) {
+ complete(bfq_ioc_gone);
+ bfq_ioc_gone = NULL;
+ }
+ spin_unlock(&bfq_ioc_gone_lock);
+ }
+}
+
+static void bfq_cic_free(struct cfq_io_context *cic)
+{
+ call_rcu(&cic->rcu_head, bfq_cic_free_rcu);
+}
+
+/**
+ * cic_free_func - disconnect a cic ready to be freed.
+ * @ioc: the io_context @cic belongs to.
+ * @cic: the cic to be freed.
+ *
+ * Remove @cic from the @ioc radix tree hash and from its cic list,
+ * deferring the deallocation of @cic to the end of the current RCU
+ * grace period. This assumes that __bfq_exit_single_io_context()
+ * has already been called for @cic.
+ */
+static void cic_free_func(struct io_context *ioc, struct cfq_io_context *cic)
+{
+ unsigned long flags;
+
+ BUG_ON(cic->dead_key == 0);
+
+ spin_lock_irqsave(&ioc->lock, flags);
+ radix_tree_delete(&ioc->bfq_radix_root, cic->dead_key);
+ hlist_del_init_rcu(&cic->cic_list);
+ spin_unlock_irqrestore(&ioc->lock, flags);
+
+ bfq_cic_free(cic);
+}
+
+static void bfq_free_io_context(struct io_context *ioc)
+{
+ /*
+ * ioc->refcount is zero here, or we are called from elv_unregister(),
+ * so no more cic's are allowed to be linked into this ioc. So it
+ * should be ok to iterate over the known list, we will see all cic's
+ * since no new ones are added.
+ */
+ call_for_each_cic(ioc, cic_free_func);
+}
+
+/**
+ * __bfq_exit_single_io_context - deassociate @cic from any running task.
+ * @bfqd: bfq_data on which @cic is valid.
+ * @cic: the cic being exited.
+ *
+ * Whenever no more tasks are using @cic or @bfqd is deallocated we
+ * need to invalidate its entry in the radix tree hash table and to
+ * release the queues it refers to. Save the key used for insertion
+ * in @cic->dead_key to remove @cic from the radix tree later and assign
+ * %NULL to its search key to prevent future lookups to succeed on it.
+ *
+ * Called under the queue lock.
+ */
+static void __bfq_exit_single_io_context(struct bfq_data *bfqd,
+ struct cfq_io_context *cic)
+{
+ struct io_context *ioc = cic->ioc;
+
+ list_del_init(&cic->queue_list);
+
+ /*
+ * Make sure key == NULL is seen for dead queues.
+ */
+ cic->dead_key = (unsigned long)cic->key;
+ smp_wmb();
+
+ rcu_assign_pointer(cic->key, NULL);
+
+ /*
+ * No write-side locking as no task is using @ioc (they're exited
+ * or bfqd is being deallocated.
+ */
+ if (ioc->ioc_data == cic)
+ rcu_assign_pointer(ioc->ioc_data, NULL);
+
+ if (cic->cfqq[ASYNC] != NULL) {
+ bfq_exit_bfqq(bfqd, cic->cfqq[ASYNC]);
+ cic->cfqq[ASYNC] = NULL;
+ }
+
+ if (cic->cfqq[SYNC] != NULL) {
+ bfq_exit_bfqq(bfqd, cic->cfqq[SYNC]);
+ cic->cfqq[SYNC] = NULL;
+ }
+}
+
+/**
+ * bfq_exit_single_io_context - deassociate @cic from @ioc (unlocked version).
+ * @ioc: the io_context @cic belongs to.
+ * @cic: the cic being exited.
+ *
+ * Take the queue lock and call __bfq_exit_single_io_context() to do the
+ * rest of the work. We take care of possible races with bfq_exit_queue()
+ * using bfq_get_bfqd_locked() (and abusing a little bit the RCU mechanism).
+ */
+static void bfq_exit_single_io_context(struct io_context *ioc,
+ struct cfq_io_context *cic)
+{
+ struct bfq_data *bfqd;
+ unsigned long uninitialized_var(flags);
+
+ bfqd = bfq_get_bfqd_locked(&cic->key, &flags);
+ if (bfqd != NULL) {
+ __bfq_exit_single_io_context(bfqd, cic);
+ bfq_put_bfqd_unlock(bfqd, &flags);
+ }
+}
+
+/**
+ * bfq_exit_io_context - deassociate @ioc from all cics it owns.
+ * @ioc: the @ioc being exited.
+ *
+ * No more processes are using @ioc we need to clean up and put the
+ * internal structures we have that belongs to that process. Loop
+ * through all its cics, locking their queues and exiting them.
+ */
+static void bfq_exit_io_context(struct io_context *ioc)
+{
+ call_for_each_cic(ioc, bfq_exit_single_io_context);
+}
+
+static struct cfq_io_context *bfq_alloc_io_context(struct bfq_data *bfqd,
+ gfp_t gfp_mask)
+{
+ struct cfq_io_context *cic;
+
+ cic = kmem_cache_alloc_node(bfq_ioc_pool, gfp_mask | __GFP_ZERO,
+ bfqd->queue->node);
+ if (cic != NULL) {
+ cic->last_end_request = jiffies;
+ INIT_LIST_HEAD(&cic->queue_list);
+ INIT_HLIST_NODE(&cic->cic_list);
+ cic->dtor = bfq_free_io_context;
+ cic->exit = bfq_exit_io_context;
+ elv_ioc_count_inc(bfq_ioc_count);
+ }
+
+ return cic;
+}
+
+/**
+ * bfq_drop_dead_cic - free an exited cic.
+ * @bfqd: bfq data for the device in use.
+ * @ioc: io_context owning @cic.
+ * @cic: the @cic to free.
+ *
+ * We drop cfq io contexts lazily, so we may find a dead one.
+ */
+static void bfq_drop_dead_cic(struct bfq_data *bfqd, struct io_context *ioc,
+ struct cfq_io_context *cic)
+{
+ unsigned long flags;
+
+ WARN_ON(!list_empty(&cic->queue_list));
+
+ spin_lock_irqsave(&ioc->lock, flags);
+
+ BUG_ON(ioc->ioc_data == cic);
+
+ /*
+ * With shared I/O contexts two lookups may race and drop the
+ * same cic more than one time: RCU guarantees that the storage
+ * will not be freed too early, here we make sure that we do
+ * not try to remove the cic from the hashing structures multiple
+ * times.
+ */
+ if (!hlist_unhashed(&cic->cic_list)) {
+ radix_tree_delete(&ioc->bfq_radix_root, (unsigned long)bfqd);
+ hlist_del_init_rcu(&cic->cic_list);
+ bfq_cic_free(cic);
+ }
+
+ spin_unlock_irqrestore(&ioc->lock, flags);
+}
+
+/**
+ * bfq_cic_lookup - search into @ioc a cic associated to @bfqd.
+ * @bfqd: the lookup key.
+ * @ioc: the io_context of the process doing I/O.
+ *
+ * If @ioc already has a cic associated to @bfqd return it, return %NULL
+ * otherwise.
+ */
+static struct cfq_io_context *bfq_cic_lookup(struct bfq_data *bfqd,
+ struct io_context *ioc)
+{
+ struct cfq_io_context *cic;
+ unsigned long flags;
+ void *k;
+
+ if (unlikely(ioc == NULL))
+ return NULL;
+
+ rcu_read_lock();
+
+ /* We maintain a last-hit cache, to avoid browsing over the tree. */
+ cic = rcu_dereference(ioc->ioc_data);
+ if (cic != NULL) {
+ k = rcu_dereference(cic->key);
+ if (k == bfqd)
+ goto out;
+ }
+
+ do {
+ cic = radix_tree_lookup(&ioc->bfq_radix_root,
+ (unsigned long)bfqd);
+ if (cic == NULL)
+ goto out;
+
+ k = rcu_dereference(cic->key);
+ if (unlikely(k == NULL)) {
+ rcu_read_unlock();
+ bfq_drop_dead_cic(bfqd, ioc, cic);
+ rcu_read_lock();
+ continue;
+ }
+
+ spin_lock_irqsave(&ioc->lock, flags);
+ rcu_assign_pointer(ioc->ioc_data, cic);
+ spin_unlock_irqrestore(&ioc->lock, flags);
+ break;
+ } while (1);
+
+out:
+ rcu_read_unlock();
+
+ return cic;
+}
+
+/**
+ * bfq_cic_link - add @cic to @ioc.
+ * @bfqd: bfq_data @cic refers to.
+ * @ioc: io_context @cic belongs to.
+ * @cic: the cic to link.
+ * @gfp_mask: the mask to use for radix tree preallocations.
+ *
+ * Add @cic to @ioc, using @bfqd as the search key. This enables us to
+ * lookup the process specific cfq io context when entered from the block
+ * layer. Also adds @cic to a per-bfqd list, used when this queue is
+ * removed.
+ */
+static int bfq_cic_link(struct bfq_data *bfqd, struct io_context *ioc,
+ struct cfq_io_context *cic, gfp_t gfp_mask)
+{
+ unsigned long flags;
+ int ret;
+
+ ret = radix_tree_preload(gfp_mask);
+ if (ret == 0) {
+ cic->ioc = ioc;
+
+ /* No write-side locking, cic is not published yet. */
+ rcu_assign_pointer(cic->key, bfqd);
+
+ spin_lock_irqsave(&ioc->lock, flags);
+ ret = radix_tree_insert(&ioc->bfq_radix_root,
+ (unsigned long)bfqd, cic);
+ if (ret == 0)
+ hlist_add_head_rcu(&cic->cic_list, &ioc->bfq_cic_list);
+ spin_unlock_irqrestore(&ioc->lock, flags);
+
+ radix_tree_preload_end();
+
+ if (ret == 0) {
+ spin_lock_irqsave(bfqd->queue->queue_lock, flags);
+ list_add(&cic->queue_list, &bfqd->cic_list);
+ spin_unlock_irqrestore(bfqd->queue->queue_lock, flags);
+ }
+ }
+
+ if (ret != 0)
+ printk(KERN_ERR "bfq: cic link failed!\n");
+
+ return ret;
+}
+
+/**
+ * bfq_ioc_set_ioprio - signal a priority change to the cics belonging to @ioc.
+ * @ioc: the io_context changing its priority.
+ */
+static inline void bfq_ioc_set_ioprio(struct io_context *ioc)
+{
+ call_for_each_cic(ioc, bfq_changed_ioprio);
+}
+
+/**
+ * bfq_get_io_context - return the @cic associated to @bfqd in @ioc.
+ * @bfqd: the search key.
+ * @gfp_mask: the mask to use for cic allocation.
+ *
+ * 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.
+ */
+static struct cfq_io_context *bfq_get_io_context(struct bfq_data *bfqd,
+ gfp_t gfp_mask)
+{
+ struct io_context *ioc = NULL;
+ struct cfq_io_context *cic;
+
+ might_sleep_if(gfp_mask & __GFP_WAIT);
+
+ ioc = get_io_context(gfp_mask, bfqd->queue->node);
+ if (ioc == NULL)
+ return NULL;
+
+ /* Lookup for an existing cic. */
+ cic = bfq_cic_lookup(bfqd, ioc);
+ if (cic != NULL)
+ goto out;
+
+ /* Alloc one if needed. */
+ cic = bfq_alloc_io_context(bfqd, gfp_mask);
+ if (cic == NULL)
+ goto err;
+
+ /* Link it into the ioc's radix tree and cic list. */
+ if (bfq_cic_link(bfqd, ioc, cic, gfp_mask) != 0)
+ goto err_free;
+
+out:
+ /*
+ * test_and_clear_bit() implies a memory barrier, paired with
+ * the wmb() in fs/ioprio.c, so the value seen for ioprio is the
+ * new one.
+ */
+ if (unlikely(test_and_clear_bit(IOC_BFQ_IOPRIO_CHANGED,
+ ioc->ioprio_changed)))
+ bfq_ioc_set_ioprio(ioc);
+
+ return cic;
+err_free:
+ bfq_cic_free(cic);
+err:
+ put_io_context(ioc);
+ return NULL;
+}
diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
new file mode 100644
index 0000000..0399cba
--- /dev/null
+++ b/block/bfq-iosched.c
@@ -0,0 +1,2279 @@
+/*
+ * BFQ, or Budget Fair Queueing, disk scheduler.
+ *
+ * Based on ideas and code from CFQ:
+ * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
+ *
+ * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
+ * Paolo Valente <paolo.valente@unimore.it>
+ *
+ * BFQ is a proportional share disk scheduling algorithm based on the
+ * slice-by-slice service scheme of CFQ. But BFQ assigns budgets,
+ * measured in number of sectors, to tasks instead of time slices.
+ * The disk is not granted to the active task for a given time slice,
+ * but until it has exahusted its assigned budget. This change from
+ * the time to the service domain allows BFQ to distribute the disk
+ * bandwidth among tasks as desired, without any distortion due to
+ * ZBR, workload fluctuations or other factors. BFQ uses an ad hoc
+ * internal scheduler, called B-WF2Q+, to schedule tasks according to
+ * their budgets. Thanks to this accurate scheduler, BFQ can afford
+ * to assign high budgets to disk-bound non-seeky tasks (to boost the
+ * throughput), and yet guarantee low latencies to interactive and
+ * soft real-time applications.
+ *
+ * BFQ has been introduced in [1], where the interested reader can
+ * find an accurate description of the algorithm, the bandwidth
+ * distribution and latency guarantees it provides, plus formal proofs
+ * of all the properties. With respect to the algorithm presented in
+ * the paper, this implementation adds several little heuristics, and
+ * a hierarchical extension, based on H-WF2Q+.
+ *
+ * B-WF2Q+ is based on WF2Q+, that is described in [2], together with
+ * H-WF2Q+, while the augmented tree used to implement B-WF2Q+ with O(log N)
+ * complexity derives from the one introduced with EEVDF in [3].
+ *
+ * [1] P. Valente and F. Checconi, ``High Throughput Disk Scheduling
+ * with Deterministic Guarantees on Bandwidth Distribution,'' to appear
+ * on IEEE Transactions on Computer.
+ *
+ * http://algo.ing.unimo.it/people/paolo/disk_sched/bfq.pdf
+ *
+ * [2] Jon C.R. Bennett and H. Zhang, ``Hierarchical Packet Fair Queueing
+ * Algorithms,'' IEEE/ACM Transactions on Networking, 5(5):675-689,
+ * Oct 1997.
+ *
+ * http://www.cs.cmu.edu/~hzhang/papers/TON-97-Oct.ps.gz
+ *
+ * [3] I. Stoica and H. Abdel-Wahab, ``Earliest Eligible Virtual Deadline
+ * First: A Flexible and Accurate Mechanism for Proportional Share
+ * Resource Allocation,'' technical report.
+ *
+ * http://www.cs.berkeley.edu/~istoica/papers/eevdf-tr-95.pdf
+ */
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/blkdev.h>
+#include <linux/cgroup.h>
+#include <linux/elevator.h>
+#include <linux/rbtree.h>
+#include <linux/ioprio.h>
+#include "bfq.h"
+
+/* Max number of dispatches in one round of service. */
+static const int bfq_quantum = 4;
+
+/* Expiration time of sync (0) and async (1) requests, in jiffies. */
+static const int bfq_fifo_expire[2] = { HZ / 4, HZ / 8 };
+
+/* Maximum backwards seek, in KiB. */
+static const int bfq_back_max = 16 * 1024;
+
+/* Penalty of a backwards seek, in number of sectors. */
+static const int bfq_back_penalty = 2;
+
+/* Idling period duration, in jiffies. */
+static int bfq_slice_idle = HZ / 125;
+
+/* Default maximum budget values, in sectors and number of requests. */
+static const int bfq_default_max_budget = 16 * 1024;
+static const int bfq_max_budget_async_rq = 4;
+
+/*
+ * Async to sync throughput distribution is controlled as follows:
+ * when an async request is served, the entity is charged the number
+ * of sectors of the request, multipled by the factor below
+ */
+static const int bfq_async_charge_factor = 10;
+
+/* Default timeout values, in jiffies, approximating CFQ defaults. */
+static const int bfq_timeout_sync = HZ / 8;
+static int bfq_timeout_async = HZ / 25;
+
+struct kmem_cache *bfq_pool;
+struct kmem_cache *bfq_ioc_pool;
+
+static DEFINE_PER_CPU(unsigned long, bfq_ioc_count);
+static struct completion *bfq_ioc_gone;
+static DEFINE_SPINLOCK(bfq_ioc_gone_lock);
+
+/* Below this threshold (in ms), we consider thinktime immediate. */
+#define BFQ_MIN_TT 2
+
+/* hw_tag detection: parallel requests threshold and min samples needed. */
+#define BFQ_HW_QUEUE_THRESHOLD 4
+#define BFQ_HW_QUEUE_SAMPLES 32
+
+#define BFQQ_SEEKY(bfqq) ((bfqq)->seek_mean > (8 * 1024))
+
+/* Min samples used for peak rate estimation (for autotuning). */
+#define BFQ_PEAK_RATE_SAMPLES 32
+
+/* Shift used for peak rate fixed precision calculations. */
+#define BFQ_RATE_SHIFT 16
+
+#define BFQ_SERVICE_TREE_INIT ((struct bfq_service_tree) \
+ { RB_ROOT, RB_ROOT, NULL, NULL, 0, 0 })
+
+#define RQ_CIC(rq) \
+ ((struct cfq_io_context *) (rq)->elevator_private)
+#define RQ_BFQQ(rq) ((rq)->elevator_private2)
+
+#include "bfq-ioc.c"
+#include "bfq-sched.c"
+#include "bfq-cgroup.c"
+
+#define bfq_class_idle(cfqq) ((bfqq)->entity.ioprio_class ==\
+ IOPRIO_CLASS_IDLE)
+
+#define bfq_sample_valid(samples) ((samples) > 80)
+
+/*
+ * We regard a request as SYNC, if either it's a read or has the SYNC bit
+ * set (in which case it could also be a direct WRITE).
+ */
+static inline int bfq_bio_sync(struct bio *bio)
+{
+ if (bio_data_dir(bio) == READ || bio_rw_flagged(bio, BIO_RW_SYNCIO))
+ return 1;
+
+ return 0;
+}
+
+/*
+ * Scheduler run of queue, if there are requests pending and no one in the
+ * driver that will restart queueing.
+ */
+static inline void bfq_schedule_dispatch(struct bfq_data *bfqd)
+{
+ if (bfqd->queued != 0) {
+ bfq_log(bfqd, "schedule dispatch");
+ kblockd_schedule_work(bfqd->queue, &bfqd->unplug_work);
+ }
+}
+
+static inline int bfq_queue_empty(struct request_queue *q)
+{
+ struct bfq_data *bfqd = q->elevator->elevator_data;
+
+ return bfqd->queued == 0;
+}
+
+/*
+ * Lifted from AS - choose which of rq1 and rq2 that is best served now.
+ * We choose the request that is closesr to the head right now. Distance
+ * behind the head is penalized and only allowed to a certain extent.
+ */
+static struct request *bfq_choose_req(struct bfq_data *bfqd,
+ struct request *rq1,
+ struct request *rq2)
+{
+ sector_t last, s1, s2, d1 = 0, d2 = 0;
+ unsigned long back_max;
+#define BFQ_RQ1_WRAP 0x01 /* request 1 wraps */
+#define BFQ_RQ2_WRAP 0x02 /* request 2 wraps */
+ unsigned wrap = 0; /* bit mask: requests behind the disk head? */
+
+ if (rq1 == NULL || rq1 == rq2)
+ return rq2;
+ if (rq2 == NULL)
+ return rq1;
+
+ if (rq_is_sync(rq1) && !rq_is_sync(rq2))
+ return rq1;
+ else if (rq_is_sync(rq2) && !rq_is_sync(rq1))
+ return rq2;
+ if (rq_is_meta(rq1) && !rq_is_meta(rq2))
+ return rq1;
+ else if (rq_is_meta(rq2) && !rq_is_meta(rq1))
+ return rq2;
+
+ s1 = blk_rq_pos(rq1);
+ s2 = blk_rq_pos(rq2);
+
+ last = bfqd->last_position;
+
+ /*
+ * By definition, 1KiB is 2 sectors.
+ */
+ back_max = bfqd->bfq_back_max * 2;
+
+ /*
+ * Strict one way elevator _except_ in the case where we allow
+ * short backward seeks which are biased as twice the cost of a
+ * similar forward seek.
+ */
+ if (s1 >= last)
+ d1 = s1 - last;
+ else if (s1 + back_max >= last)
+ d1 = (last - s1) * bfqd->bfq_back_penalty;
+ else
+ wrap |= BFQ_RQ1_WRAP;
+
+ if (s2 >= last)
+ d2 = s2 - last;
+ else if (s2 + back_max >= last)
+ d2 = (last - s2) * bfqd->bfq_back_penalty;
+ else
+ wrap |= BFQ_RQ2_WRAP;
+
+ /* Found required data */
+
+ /*
+ * 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: rq1 and rq2 not wrapped */
+ if (d1 < d2)
+ return rq1;
+ else if (d2 < d1)
+ return rq2;
+ else {
+ if (s1 >= s2)
+ return rq1;
+ else
+ return rq2;
+ }
+
+ case BFQ_RQ2_WRAP:
+ return rq1;
+ case BFQ_RQ1_WRAP:
+ return rq2;
+ case (BFQ_RQ1_WRAP|BFQ_RQ2_WRAP): /* both rqs 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 rq1;
+ else
+ return rq2;
+ }
+}
+
+static struct request *bfq_find_next_rq(struct bfq_data *bfqd,
+ struct bfq_queue *bfqq,
+ struct request *last)
+{
+ struct rb_node *rbnext = rb_next(&last->rb_node);
+ struct rb_node *rbprev = rb_prev(&last->rb_node);
+ struct request *next = NULL, *prev = NULL;
+
+ BUG_ON(RB_EMPTY_NODE(&last->rb_node));
+
+ if (rbprev != NULL)
+ prev = rb_entry_rq(rbprev);
+
+ if (rbnext != NULL)
+ next = rb_entry_rq(rbnext);
+ else {
+ rbnext = rb_first(&bfqq->sort_list);
+ if (rbnext && rbnext != &last->rb_node)
+ next = rb_entry_rq(rbnext);
+ }
+
+ return bfq_choose_req(bfqd, next, prev);
+}
+
+static void bfq_del_rq_rb(struct request *rq)
+{
+ struct bfq_queue *bfqq = RQ_BFQQ(rq);
+ struct bfq_data *bfqd = bfqq->bfqd;
+ const int sync = rq_is_sync(rq);
+
+ BUG_ON(bfqq->queued[sync] == 0);
+ bfqq->queued[sync]--;
+ bfqd->queued--;
+
+ elv_rb_del(&bfqq->sort_list, rq);
+
+ if (bfq_bfqq_busy(bfqq) && bfqq != bfqd->active_queue &&
+ RB_EMPTY_ROOT(&bfqq->sort_list))
+ bfq_del_bfqq_busy(bfqd, bfqq, 1);
+}
+
+/* see the definition of bfq_async_charge_factor for details */
+static inline bfq_service_t bfq_serv_to_charge(struct request *rq,
+ struct bfq_queue *bfqq)
+{
+ return blk_rq_sectors(rq) *
+ (1 + ((!bfq_bfqq_sync(bfqq)) * bfq_async_charge_factor));
+}
+
+/**
+ * bfq_updated_next_req - update the queue after a new next_rq selection.
+ * @bfqd: the device data the queue belongs to.
+ * @bfqq: the queue to update.
+ *
+ * If the first request of a queue changes we make sure that the queue
+ * has enough budget to serve at least its first request (if the
+ * request has grown). We do this because if the queue has not enough
+ * budget for its first request, it has to go through two dispatch
+ * rounds to actually get it dispatched.
+ */
+static void bfq_updated_next_req(struct bfq_data *bfqd,
+ struct bfq_queue *bfqq)
+{
+ struct bfq_entity *entity = &bfqq->entity;
+ struct bfq_service_tree *st = bfq_entity_service_tree(entity);
+ struct request *next_rq = bfqq->next_rq;
+ bfq_service_t new_budget;
+
+ if (next_rq == NULL)
+ return;
+
+ if (bfqq == bfqd->active_queue)
+ /*
+ * In order not to break guarantees, budgets cannot be
+ * changed after an entity has been selected.
+ */
+ return;
+
+ BUG_ON(entity->tree != &st->active);
+ BUG_ON(entity == entity->sched_data->active_entity);
+
+ new_budget = max_t(bfq_service_t, bfqq->max_budget,
+ bfq_serv_to_charge(next_rq, bfqq));
+ entity->budget = new_budget;
+ bfq_log_bfqq(bfqd, bfqq, "updated next rq: new budget %lu", new_budget);
+ bfq_activate_bfqq(bfqd, bfqq);
+}
+
+static void bfq_add_rq_rb(struct request *rq)
+{
+ struct bfq_queue *bfqq = RQ_BFQQ(rq);
+ struct bfq_entity *entity = &bfqq->entity;
+ struct bfq_data *bfqd = bfqq->bfqd;
+ struct request *__alias, *next_rq;
+
+ bfq_log_bfqq(bfqd, bfqq, "add_rq_rb %d", rq_is_sync(rq));
+ bfqq->queued[rq_is_sync(rq)]++;
+ bfqd->queued++;
+
+ /*
+ * Looks a little odd, but the first insert might return an alias,
+ * if that happens, put the alias on the dispatch list.
+ */
+ while ((__alias = elv_rb_add(&bfqq->sort_list, rq)) != NULL)
+ bfq_dispatch_insert(bfqd->queue, __alias);
+
+ /*
+ * Check if this request is a better next-serve candidate.
+ */
+ next_rq = bfq_choose_req(bfqd, bfqq->next_rq, rq);
+ BUG_ON(next_rq == NULL);
+ bfqq->next_rq = next_rq;
+
+ if (!bfq_bfqq_busy(bfqq)) {
+ entity->budget = max_t(bfq_service_t, bfqq->max_budget,
+ bfq_serv_to_charge(next_rq, bfqq));
+
+ /*
+ * If the queue is not being boosted and has been idle
+ * for enough time, start a boosting period
+ */
+ if (bfqd->low_latency && bfqq->high_weight_budget == 0) {
+ if(bfqq->last_activation_time + BFQ_MIN_ACT_INTERVAL <
+ jiffies_to_msecs(jiffies)) {
+ bfqq->high_weight_budget = BFQ_BOOST_BUDGET;
+ entity->ioprio_changed = 1;
+ bfq_log_bfqq(bfqd, bfqq,
+ "wboost starting at %lu msec",
+ bfqq->last_activation_time);
+ }
+ bfqq->last_activation_time =
+ jiffies_to_msecs(jiffies);
+ }
+
+ bfq_add_bfqq_busy(bfqd, bfqq);
+ } else
+ bfq_updated_next_req(bfqd, bfqq);
+}
+
+static void bfq_reposition_rq_rb(struct bfq_queue *bfqq, struct request *rq)
+{
+ elv_rb_del(&bfqq->sort_list, rq);
+ bfqq->queued[rq_is_sync(rq)]--;
+ bfqq->bfqd->queued--;
+ bfq_add_rq_rb(rq);
+}
+
+static struct request *bfq_find_rq_fmerge(struct bfq_data *bfqd,
+ struct bio *bio)
+{
+ struct task_struct *tsk = current;
+ struct cfq_io_context *cic;
+ struct bfq_queue *bfqq;
+
+ cic = bfq_cic_lookup(bfqd, tsk->io_context);
+ if (cic == NULL)
+ return NULL;
+
+ bfqq = cic_to_bfqq(cic, bfq_bio_sync(bio));
+ if (bfqq != NULL) {
+ sector_t sector = bio->bi_sector + bio_sectors(bio);
+
+ return elv_rb_find(&bfqq->sort_list, sector);
+ }
+
+ return NULL;
+}
+
+static void bfq_activate_request(struct request_queue *q, struct request *rq)
+{
+ struct bfq_data *bfqd = q->elevator->elevator_data;
+
+ bfqd->rq_in_driver++;
+ bfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq);
+}
+
+static void bfq_deactivate_request(struct request_queue *q, struct request *rq)
+{
+ struct bfq_data *bfqd = q->elevator->elevator_data;
+
+ WARN_ON(bfqd->rq_in_driver == 0);
+ bfqd->rq_in_driver--;
+}
+
+static void bfq_remove_request(struct request *rq)
+{
+ struct bfq_queue *bfqq = RQ_BFQQ(rq);
+ struct bfq_data *bfqd = bfqq->bfqd;
+
+ if (bfqq->next_rq == rq) {
+ bfqq->next_rq = bfq_find_next_rq(bfqd, bfqq, rq);
+ bfq_updated_next_req(bfqd, bfqq);
+ }
+
+ list_del_init(&rq->queuelist);
+ bfq_del_rq_rb(rq);
+
+ if (rq_is_meta(rq)) {
+ WARN_ON(bfqq->meta_pending == 0);
+ bfqq->meta_pending--;
+ }
+}
+
+static int bfq_merge(struct request_queue *q, struct request **req,
+ struct bio *bio)
+{
+ struct bfq_data *bfqd = q->elevator->elevator_data;
+ struct request *__rq;
+
+ __rq = bfq_find_rq_fmerge(bfqd, bio);
+ if (__rq != NULL && elv_rq_merge_ok(__rq, bio)) {
+ *req = __rq;
+ return ELEVATOR_FRONT_MERGE;
+ }
+
+ return ELEVATOR_NO_MERGE;
+}
+
+static void bfq_merged_request(struct request_queue *q, struct request *req,
+ int type)
+{
+ if (type == ELEVATOR_FRONT_MERGE) {
+ struct bfq_queue *bfqq = RQ_BFQQ(req);
+
+ bfq_reposition_rq_rb(bfqq, req);
+ }
+}
+
+static void bfq_merged_requests(struct request_queue *q, struct request *rq,
+ struct request *next)
+{
+ /*
+ * Reposition in fifo if next is older than rq.
+ */
+ if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) &&
+ time_before(next->start_time, rq->start_time))
+ list_move(&rq->queuelist, &next->queuelist);
+
+ bfq_remove_request(next);
+}
+
+static int bfq_allow_merge(struct request_queue *q, struct request *rq,
+ struct bio *bio)
+{
+ struct bfq_data *bfqd = q->elevator->elevator_data;
+ struct cfq_io_context *cic;
+ struct bfq_queue *bfqq;
+
+ /* Disallow merge of a sync bio into an async request. */
+ if (bfq_bio_sync(bio) && !rq_is_sync(rq))
+ return 0;
+
+ /*
+ * Lookup the bfqq that this bio will be queued with. Allow
+ * merge only if rq is queued there.
+ */
+ cic = bfq_cic_lookup(bfqd, current->io_context);
+ if (cic == NULL)
+ return 0;
+
+ bfqq = cic_to_bfqq(cic, bfq_bio_sync(bio));
+ return bfqq == RQ_BFQQ(rq);
+}
+
+static void __bfq_set_active_queue(struct bfq_data *bfqd,
+ struct bfq_queue *bfqq)
+{
+ if (bfqq != NULL) {
+ bfq_mark_bfqq_must_alloc(bfqq);
+ bfq_mark_bfqq_budget_new(bfqq);
+ bfq_clear_bfqq_fifo_expire(bfqq);
+
+ bfqd->budgets_assigned = (bfqd->budgets_assigned*7 + 256) / 8;
+
+ bfq_log_bfqq(bfqd, bfqq, "set_active_queue, cur-budget = %lu",
+ bfqq->entity.budget);
+ }
+
+ bfqd->active_queue = bfqq;
+}
+
+/*
+ * Get and set a new active queue for service.
+ */
+static struct bfq_queue *bfq_set_active_queue(struct bfq_data *bfqd)
+{
+ struct bfq_queue *bfqq;
+
+ bfqq = bfq_get_next_queue(bfqd);
+ __bfq_set_active_queue(bfqd, bfqq);
+ return bfqq;
+}
+
+/*
+ * If enough samples have been computed, return the current max budget
+ * stored in bfqd, which is dynamically updated according to the
+ * estimated disk peak rate; otherwise return the default max budget
+ */
+static inline bfq_service_t bfq_max_budget(struct bfq_data *bfqd)
+{
+ return bfqd->budgets_assigned < 194 ? bfq_default_max_budget :
+ bfqd->bfq_max_budget;
+}
+
+/*
+ * Return min budget, which is a fraction of the current or default
+ * max budget (trying with 1/32)
+ */
+static inline bfq_service_t bfq_min_budget(struct bfq_data *bfqd)
+{
+ return bfqd->budgets_assigned < 194 ? bfq_default_max_budget / 32 :
+ bfqd->bfq_max_budget / 32;
+}
+
+static void bfq_arm_slice_timer(struct bfq_data *bfqd)
+{
+ struct bfq_queue *bfqq = bfqd->active_queue;
+ struct cfq_io_context *cic;
+ unsigned long sl;
+
+ WARN_ON(!RB_EMPTY_ROOT(&bfqq->sort_list));
+
+ /* Idling is disabled, either manually or by past process history. */
+ if (bfqd->bfq_slice_idle == 0 || !bfq_bfqq_idle_window(bfqq))
+ return;
+
+ /* Tasks have exited, don't wait. */
+ cic = bfqd->active_cic;
+ if (cic == NULL || atomic_read(&cic->ioc->nr_tasks) == 0)
+ return;
+
+ bfq_mark_bfqq_wait_request(bfqq);
+
+ /*
+ * 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.
+ *
+ * To prevent processes with (partly) seeky workloads from
+ * being too ill-treated, grant them a small fraction of the
+ * assigned budget before reducing the waiting time to
+ * BFQ_MIN_TT. This happened to help reduce latency.
+ */
+ sl = bfqd->bfq_slice_idle;
+ if (bfq_sample_valid(bfqq->seek_samples) && BFQQ_SEEKY(bfqq) &&
+ bfqq->entity.service > bfq_max_budget(bfqd) / 8)
+ sl = min(sl, msecs_to_jiffies(BFQ_MIN_TT));
+
+ bfqd->last_idling_start = ktime_get();
+ mod_timer(&bfqd->idle_slice_timer, jiffies + sl);
+ bfq_log(bfqd, "arm idle: %lu ms", sl);
+}
+
+/*
+ * Set the maximum time for the active queue to consume its
+ * budget. This prevents seeky processes from lowering the disk
+ * throughput (always guaranteed with a time slice scheme as in CFQ).
+ */
+static void bfq_set_budget_timeout(struct bfq_data *bfqd)
+{
+ struct bfq_queue *bfqq = bfqd->active_queue;
+
+ bfqd->last_budget_start = ktime_get();
+
+ bfq_clear_bfqq_budget_new(bfqq);
+ bfqq->budget_timeout = jiffies +
+ bfqd->bfq_timeout[!!bfq_bfqq_sync(bfqq)] *
+ (bfqq->entity.weight / bfqq->entity.orig_weight);
+}
+
+/*
+ * Move request from internal lists to the request queue dispatch list.
+ */
+static void bfq_dispatch_insert(struct request_queue *q, struct request *rq)
+{
+ struct bfq_data *bfqd = q->elevator->elevator_data;
+ struct bfq_queue *bfqq = RQ_BFQQ(rq);
+
+ bfq_remove_request(rq);
+ bfqq->dispatched++;
+ elv_dispatch_sort(q, rq);
+
+ if (bfq_bfqq_sync(bfqq))
+ bfqd->sync_flight++;
+}
+
+/*
+ * Return expired entry, or NULL to just start from scratch in rbtree.
+ */
+static struct request *bfq_check_fifo(struct bfq_queue *bfqq)
+{
+ struct bfq_data *bfqd = bfqq->bfqd;
+ struct request *rq;
+ int fifo;
+
+ if (bfq_bfqq_fifo_expire(bfqq))
+ return NULL;
+
+ bfq_mark_bfqq_fifo_expire(bfqq);
+
+ if (list_empty(&bfqq->fifo))
+ return NULL;
+
+ fifo = bfq_bfqq_sync(bfqq);
+ rq = rq_entry_fifo(bfqq->fifo.next);
+
+ if (time_before(jiffies, rq->start_time + bfqd->bfq_fifo_expire[fifo]))
+ return NULL;
+
+ return rq;
+}
+
+static inline bfq_service_t bfq_bfqq_budget_left(struct bfq_queue *bfqq)
+{
+ struct bfq_entity *entity = &bfqq->entity;
+ return entity->budget - entity->service;
+}
+
+static void __bfq_bfqq_expire(struct bfq_data *bfqd, struct bfq_queue *bfqq)
+{
+ BUG_ON(bfqq != bfqd->active_queue);
+
+ __bfq_bfqd_reset_active(bfqd);
+
+ if (RB_EMPTY_ROOT(&bfqq->sort_list))
+ bfq_del_bfqq_busy(bfqd, bfqq, 1);
+ else
+ bfq_activate_bfqq(bfqd, bfqq);
+}
+
+/**
+ * __bfq_bfqq_recalc_budget - try to adapt the budget to the @bfqq behavior.
+ * @bfqd: device data.
+ * @bfqq: queue to update.
+ * @reason: reason for expiration.
+ *
+ * Handle the feedback on @bfqq budget. See the body for detailed
+ * comments.
+ */
+static void __bfq_bfqq_recalc_budget(struct bfq_data *bfqd,
+ struct bfq_queue *bfqq,
+ enum bfqq_expiration reason)
+{
+ struct request *next_rq;
+ bfq_service_t budget, min_budget;
+
+ budget = bfqq->max_budget;
+ min_budget = bfq_min_budget(bfqd);
+
+ BUG_ON(bfqq != bfqd->active_queue);
+
+ bfq_log_bfqq(bfqd, bfqq, "recalc_budg: last budg %lu, budg left %lu",
+ bfqq->entity.budget, bfq_bfqq_budget_left(bfqq));
+ bfq_log_bfqq(bfqd, bfqq, "recalc_budg: last max_budg %lu, min budg %lu",
+ budget, bfq_min_budget(bfqd));
+ bfq_log_bfqq(bfqd, bfqq, "recalc_budg: sync %d, seeky %d",
+ bfq_bfqq_sync(bfqq), BFQQ_SEEKY(bfqd->active_queue));
+
+ if (bfq_bfqq_sync(bfqq)) {
+ switch (reason) {
+ /*
+ * Caveat: in all the following cases we trade latency
+ * for throughput.
+ */
+ case BFQ_BFQQ_TOO_IDLE:
+ /*
+ * This is the only case where we may reduce
+ * the budget: if there is no requets of the
+ * process still waiting for completion, then
+ * we assume (tentatively) that the timer has
+ * expired because the batch of requests of
+ * the process could have been served with a
+ * smaller budget. Hence, betting that
+ * process will behave in the same way when it
+ * becomes backlogged again, we reduce its
+ * next budget. As long as we guess right,
+ * this budget cut reduces the latency
+ * experienced by the process.
+ *
+ * However, if there are still outstanding
+ * requests, then the process may have not yet
+ * issued its next request just because it is
+ * still waiting for the completion of some of
+ * the still oustanding ones. So in this
+ * subcase we do not reduce its budget, on the
+ * contrary we increase it to possibly boost
+ * the throughput, as discussed in the
+ * comments to the BUDGET_TIMEOUT case.
+ */
+ if(bfqq->dispatched > 0) /* still oustanding reqs */
+ budget = min(budget * 2, bfqd->bfq_max_budget);
+ else {
+ if (budget > 5 * min_budget)
+ budget -= 4 * min_budget;
+ else
+ budget = min_budget;
+ }
+ break;
+ case BFQ_BFQQ_BUDGET_TIMEOUT:
+ /*
+ * We double the budget here because: 1) it
+ * gives the chance to boost the throughput if
+ * this is not a seeky process (which may have
+ * bumped into this timeout because of, e.g.,
+ * ZBR), 2) together with charge_full_budget
+ * it helps give seeky processes higher
+ * timestamps, and hence be served less
+ * frequently.
+ */
+ budget = min(budget * 2, bfqd->bfq_max_budget);
+ break;
+ case BFQ_BFQQ_BUDGET_EXHAUSTED:
+ /*
+ * The process still has backlog, and did not
+ * let either the budget timeout or the disk
+ * idling timeout expire. Hence it is not
+ * seeky, has a short thinktime and may be
+ * happy with a higher budget too. So
+ * definitely increase the budget of this good
+ * candidate to boost the disk throughput.
+ */
+ budget = min(budget * 4, bfqd->bfq_max_budget);
+ break;
+ case BFQ_BFQQ_NO_MORE_REQUESTS:
+ /*
+ * Leave the budget unchanged.
+ */
+ default:
+ return;
+ }
+ } else /* async queue */
+ /* async queues get always the maximum possible budget
+ * (their ability to dispatch is limited by
+ * @bfqd->bfq_max_budget_async_rq).
+ */
+ budget = bfqd->bfq_max_budget;
+
+ bfqq->max_budget = budget;
+
+ if (bfqd->budgets_assigned >= 194 && bfqd->bfq_user_max_budget == 0 &&
+ bfqq->max_budget > bfqd->bfq_max_budget)
+ bfqq->max_budget = bfqd->bfq_max_budget;
+
+ /*
+ * Make sure that we have enough budget for the next request.
+ * Since the finish time of the bfqq must be kept in sync with
+ * the budget, be sure to call __bfq_bfqq_expire() after the
+ * update.
+ */
+ next_rq = bfqq->next_rq;
+ if (next_rq != NULL)
+ bfqq->entity.budget = max_t(bfq_service_t, bfqq->max_budget,
+ bfq_serv_to_charge(next_rq, bfqq));
+ else
+ bfqq->entity.budget = bfqq->max_budget;
+
+ bfq_log_bfqq(bfqd, bfqq, "head sect: %lu, new budget %lu",
+ next_rq != NULL ? blk_rq_sectors(next_rq) : 0,
+ bfqq->entity.budget);
+}
+
+static bfq_service_t bfq_calc_max_budget(u64 peak_rate, u64 timeout)
+{
+ bfq_service_t max_budget;
+
+ /*
+ * The max_budget calculated when autotuning is equal to the
+ * amount of sectors transfered in timeout_sync at the
+ * estimated peak rate.
+ */
+ max_budget = (bfq_service_t)(peak_rate * 1000 *
+ timeout >> BFQ_RATE_SHIFT);
+
+ return max_budget;
+}
+
+/*
+ * In addition to updating the peak rate, checks whether the process
+ * is "slow", and returns 1 if so. This slow flag is used, in addition
+ * to the budget timeout, to reduce the amount of service provided to
+ * seeky processes, and hence reduce their chances to lower the
+ * throughput. See the code for more details.
+ */
+static int bfq_update_peak_rate(struct bfq_data *bfqd, struct bfq_queue *bfqq,
+ int compensate, enum bfqq_expiration reason)
+{
+ u64 bw, usecs, expected, timeout;
+ ktime_t delta;
+ int update = 0;
+
+ if (!bfq_bfqq_sync(bfqq) || bfq_bfqq_budget_new(bfqq))
+ return 0;
+
+ delta = compensate ? bfqd->last_idling_start : ktime_get();
+ delta = ktime_sub(delta, bfqd->last_budget_start);
+ usecs = ktime_to_us(delta);
+
+ /* Don't trust short/unrealistic values. */
+ if (usecs < 100 || usecs >= LONG_MAX)
+ return 0;
+
+ /*
+ * Calculate the bandwidth for the last slice. We use a 64 bit
+ * value to store the peak rate, in sectors per usec in fixed
+ * point math. We do so to have enough precision in the estimate
+ * and to avoid overflows.
+ */
+ bw = (u64)bfqq->entity.service << BFQ_RATE_SHIFT;
+ do_div(bw, (unsigned long)usecs);
+
+ timeout = jiffies_to_msecs(bfqd->bfq_timeout[SYNC]);
+
+ /*
+ * Use only long (> 20ms) intervals to filter out spikes for
+ * the peak rate estimation.
+ */
+ if (usecs > 20000) {
+ if (bw > bfqd->peak_rate ||
+ (!BFQQ_SEEKY(bfqq) &&
+ reason == BFQ_BFQQ_BUDGET_TIMEOUT)) {
+ bfq_log(bfqd, "measured bw =%llu", bw);
+ /*
+ * To smooth oscillations use a low-pass filter with
+ * alpha=7/8, i.e.,
+ * new_rate = (7/8) * old_rate + (1/8) * bw
+ */
+ do_div(bw, 8);
+ bfqd->peak_rate *= 7;
+ do_div(bfqd->peak_rate, 8);
+ bfqd->peak_rate += bw;
+ update = 1;
+ bfq_log(bfqd, "new peak_rate=%llu", bfqd->peak_rate);
+ }
+
+ update |= bfqd->peak_rate_samples == BFQ_PEAK_RATE_SAMPLES - 1;
+
+ if (bfqd->peak_rate_samples < BFQ_PEAK_RATE_SAMPLES)
+ bfqd->peak_rate_samples++;
+
+ if (bfqd->peak_rate_samples == BFQ_PEAK_RATE_SAMPLES &&
+ update && bfqd->bfq_user_max_budget == 0) {
+ bfqd->bfq_max_budget =
+ bfq_calc_max_budget(bfqd->peak_rate, timeout);
+ bfq_log(bfqd, "new max_budget=%lu",
+ bfqd->bfq_max_budget);
+ }
+ }
+
+ /*
+ * If the process has been served for a too short time
+ * interval to let its possible sequential accesses prevail on
+ * the initial seek time needed to move the disk head on the
+ * first sector it requested, then give the process a chance
+ * and for the moment return false.
+ */
+ if (bfqq->entity.budget <= bfq_max_budget(bfqd) / 8)
+ return 0;
+
+ /*
+ * A process is considered ``slow'' (i.e., seeky, so that we
+ * cannot treat it fairly in the service domain, as it would
+ * slow down too much the other processes) if, when a slice
+ * ends for whatever reason, it has received service at a
+ * rate that would not be high enough to complete the budget
+ * before the budget timeout expiration.
+ */
+ expected = bw * 1000 * timeout >> BFQ_RATE_SHIFT;
+
+ /*
+ * Caveat: processes doing IO in the slower disk zones will
+ * tend to be slow(er) even if not seeky. And the estimated
+ * peak rate will actually be an average over the disk
+ * surface. Hence, to not be too harsh with unlucky processes,
+ * we keep a budget/3 margin of safety before declaring a
+ * process slow.
+ */
+ return expected > (4 * bfqq->entity.budget) / 3;
+}
+
+/**
+ * bfq_bfqq_expire - expire a queue.
+ * @bfqd: device owning the queue.
+ * @bfqq: the queue to expire.
+ * @compensate: if true, compensate for the time spent idling.
+ * @reason: the reason causing the expiration.
+ *
+ *
+ * If the process associated to the queue is slow (i.e., seeky), or in
+ * case of budget timeout, or, finally, if it is async, we
+ * artificially charge it an entire budget (independently of the
+ * actual service it received). As a consequence, the queue will get
+ * higher timestamps than the correct ones upon reactivation, and
+ * hence it will be rescheduled as if it had received more service
+ * than what it actually received. In the end, this class of processes
+ * will receive less service in proportion to how slowly they consume
+ * their budgets (and hence how seriously they tend to lower the
+ * throughput).
+ *
+ * In contrast, when a queue expires because it has been idling for
+ * too much or because it exhausted its budget, we do not touch the
+ * amount of service it has received. Hence when the queue will be
+ * reactivated and its timestamps updated, the latter will be in sync
+ * with the actual service received by the queue until expiration.
+ *
+ * Charging a full budget to the first type of queues and the exact
+ * service to the others has the effect of using the WF2Q+ policy to
+ * schedule the former on a timeslice basis, without violating the
+ * service domain guarantees of the latter.
+ */
+static void bfq_bfqq_expire(struct bfq_data *bfqd,
+ struct bfq_queue *bfqq,
+ int compensate,
+ enum bfqq_expiration reason)
+{
+ int slow;
+ BUG_ON(bfqq != bfqd->active_queue);
+
+ /* Update disk peak rate for autotuning and check whether the
+ * process is slow (see bfq_update_peak_rate).
+ */
+ slow = bfq_update_peak_rate(bfqd, bfqq, compensate, reason);
+
+ /*
+ * As above explained, 'punish' slow (i.e., seeky), timed-out
+ * and async queues, to favor sequential sync workloads.
+ *
+ * Processes doing IO in the slower disk zones will tend to be
+ * slow(er) even if not seeky. Hence, since the estimated peak
+ * rate is actually an average over the disk surface, these
+ * processes may timeout just for bad luck. To avoid punishing
+ * them we do not charge a full budget to a process that
+ * succeeded in consuming at least 2/3 of its budget.
+ */
+ if (slow || (reason == BFQ_BFQQ_BUDGET_TIMEOUT &&
+ bfq_bfqq_budget_left(bfqq) >= bfqq->entity.budget / 3))
+ bfq_bfqq_charge_full_budget(bfqq);
+
+ bfq_log_bfqq(bfqd, bfqq,
+ "expire (%d, slow %d, num_disp %d, idle_win %d)", reason, slow,
+ bfqq->dispatched, bfq_bfqq_idle_window(bfqq));
+
+ /* Increase, decrease or leave budget unchanged according to reason */
+ __bfq_bfqq_recalc_budget(bfqd, bfqq, reason);
+ __bfq_bfqq_expire(bfqd, bfqq);
+}
+
+/*
+ * Budget timeout is not implemented through a dedicated timer, but
+ * just checked on request arrivals and completions, as well as on
+ * idle timer expirations.
+ */
+static int bfq_bfqq_budget_timeout(struct bfq_queue *bfqq)
+{
+ if (bfq_bfqq_budget_new(bfqq))
+ return 0;
+
+ if (time_before(jiffies, bfqq->budget_timeout))
+ return 0;
+
+ return 1;
+}
+
+/*
+ * If we expire a queue that is waiting for the arrival of a new
+ * request, we may prevent the fictitious timestamp backshifting that
+ * allows the guarantees of the queue to be preserved (see [1] for
+ * this tricky aspect). Hence we return true only if this condition
+ * does not hold, or if the queue is slow enough to deserve only to be
+ * kicked off for preserving a high throughput.
+*/
+static inline int bfq_may_expire_for_budg_timeout(struct bfq_queue *bfqq)
+{
+ return (! bfq_bfqq_wait_request(bfqq) ||
+ bfq_bfqq_budget_left(bfqq) >= bfqq->entity.budget / 3)
+ &&
+ bfq_bfqq_budget_timeout(bfqq);
+}
+
+/*
+ * Select a queue for service. If we have a current active queue,
+ * check whether to continue servicing it, or retrieve and set a new one.
+ */
+static struct bfq_queue *bfq_select_queue(struct bfq_data *bfqd)
+{
+ struct bfq_queue *bfqq;
+ struct request *next_rq;
+ enum bfqq_expiration reason = BFQ_BFQQ_BUDGET_TIMEOUT;
+
+ bfqq = bfqd->active_queue;
+ if (bfqq == NULL)
+ goto new_queue;
+
+ bfq_log_bfqq(bfqd, bfqq, "select_queue: already active queue");
+
+ if (bfq_may_expire_for_budg_timeout(bfqq))
+ goto expire;
+
+ next_rq = bfqq->next_rq;
+ /*
+ * If bfqq has requests queued and it has enough budget left to
+ * serve them, keep the queue, otherwise expire it.
+ */
+ if (next_rq != NULL) {
+ if (bfq_serv_to_charge(next_rq, bfqq) >
+ bfq_bfqq_budget_left(bfqq)) {
+ reason = BFQ_BFQQ_BUDGET_EXHAUSTED;
+ goto expire;
+ } else
+ goto keep_queue;
+ }
+
+ /*
+ * No requests pending. If the active queue still has
+ * requests in flight or is idling for a new request, then keep it.
+ */
+ if (timer_pending(&bfqd->idle_slice_timer) ||
+ (bfqq->dispatched != 0 && bfq_bfqq_idle_window(bfqq))) {
+ bfqq = NULL;
+ goto keep_queue;
+ }
+
+ reason = BFQ_BFQQ_NO_MORE_REQUESTS;
+expire:
+ bfq_bfqq_expire(bfqd, bfqq, 0, reason);
+new_queue:
+ bfqq = bfq_set_active_queue(bfqd);
+ bfq_log(bfqd, "select_queue: new queue returned (possibly NULL)");
+keep_queue:
+ return bfqq;
+}
+
+/*
+ * Dispatch some requests from bfqq, moving them to the request queue
+ * dispatch list.
+ */
+static int __bfq_dispatch_requests(struct bfq_data *bfqd,
+ struct bfq_queue *bfqq,
+ int max_dispatch)
+{
+ int dispatched = 0;
+
+ BUG_ON(RB_EMPTY_ROOT(&bfqq->sort_list));
+
+ do {
+ struct request *rq;
+ bfq_service_t service_to_charge;
+
+ /* Follow expired path, else get first next available. */
+ rq = bfq_check_fifo(bfqq);
+ if (rq == NULL)
+ rq = bfqq->next_rq;
+ service_to_charge = bfq_serv_to_charge(rq, bfqq);
+
+ if (service_to_charge > bfq_bfqq_budget_left(bfqq)) {
+ /*
+ * Expire the queue for budget exhaustion, and
+ * make sure that the next act_budget is enough
+ * to serve the next request, even if it comes
+ * from the fifo expired path.
+ */
+ bfqq->next_rq = rq;
+ goto expire;
+ }
+
+ /* Finally, insert request into driver dispatch list. */
+ bfq_bfqq_served(bfqq, service_to_charge);
+ bfq_dispatch_insert(bfqd->queue, rq);
+
+ if (bfqq->high_weight_budget > 0) { /* queue is being boosted */
+ struct bfq_entity *entity = &bfqq->entity;
+
+ bfq_log_bfqq(bfqd, bfqq, "busy period dur %llu msec, "
+ "old highwbudg %lu",
+ jiffies_to_msecs(jiffies) -
+ bfqq->last_activation_time,
+ bfqq->high_weight_budget);
+ /*
+ * Decrease the budget for weight boosting by
+ * the just received service, or, if too much
+ * time has elapsed from the beginning of this
+ * boosting period, stop it
+ */
+ if (jiffies_to_msecs(jiffies) -
+ bfqq->last_activation_time <= BFQ_BOOST_TIMEOUT
+ &&
+ bfqq->high_weight_budget > service_to_charge)
+ bfqq->high_weight_budget -= service_to_charge;
+ else
+ bfqq->high_weight_budget = 0;
+ entity->ioprio_changed = 1;
+ __bfq_entity_update_weight_prio(
+ bfq_entity_service_tree(entity),
+ entity);
+ }
+
+ bfq_log_bfqq(bfqd, bfqq, "dispatched %lu sec req (%llu), "
+ "budg left %lu",
+ blk_rq_sectors(rq), blk_rq_pos(rq),
+ bfq_bfqq_budget_left(bfqq));
+
+ dispatched++;
+
+ if (bfqd->active_cic == NULL) {
+ atomic_inc(&RQ_CIC(rq)->ioc->refcount);
+ bfqd->active_cic = RQ_CIC(rq);
+ }
+
+ if (RB_EMPTY_ROOT(&bfqq->sort_list))
+ break;
+ } while (dispatched < max_dispatch);
+
+ bfq_log_bfqq(bfqd, bfqq, "dispatched %d reqs", dispatched);
+
+ if (bfqd->busy_queues > 1 && ((!bfq_bfqq_sync(bfqq) &&
+ dispatched >= bfqd->bfq_max_budget_async_rq) ||
+ bfq_class_idle(bfqq)))
+ goto expire;
+
+ return dispatched;
+
+expire:
+ bfq_bfqq_expire(bfqd, bfqq, 0, BFQ_BFQQ_BUDGET_EXHAUSTED);
+ return dispatched;
+}
+
+static int __bfq_forced_dispatch_bfqq(struct bfq_queue *bfqq)
+{
+ int dispatched = 0;
+
+ while (bfqq->next_rq != NULL) {
+ bfq_dispatch_insert(bfqq->bfqd->queue, bfqq->next_rq);
+ dispatched++;
+ }
+
+ BUG_ON(!list_empty(&bfqq->fifo));
+ return dispatched;
+}
+
+/*
+ * Drain our current requests. Used for barriers and when switching
+ * io schedulers on-the-fly.
+ */
+static int bfq_forced_dispatch(struct bfq_data *bfqd)
+{
+ struct bfq_queue *bfqq, *n;
+ struct bfq_service_tree *st;
+ int dispatched = 0;
+
+ bfqq = bfqd->active_queue;
+ if (bfqq != NULL)
+ __bfq_bfqq_expire(bfqd, bfqq);
+
+ /*
+ * Loop through classes, and be careful to leave the scheduler
+ * in a consistent state, as feedback mechanisms and vtime
+ * updates cannot be disabled during the process.
+ */
+ list_for_each_entry_safe(bfqq, n, &bfqd->active_list, bfqq_list) {
+ st = bfq_entity_service_tree(&bfqq->entity);
+
+ dispatched += __bfq_forced_dispatch_bfqq(bfqq);
+ bfqq->max_budget = bfq_max_budget(bfqd);
+
+ bfq_forget_idle(st);
+ }
+
+ BUG_ON(bfqd->busy_queues != 0);
+
+ return dispatched;
+}
+
+static int bfq_dispatch_requests(struct request_queue *q, int force)
+{
+ struct bfq_data *bfqd = q->elevator->elevator_data;
+ struct bfq_queue *bfqq;
+ int dispatched;
+
+ bfq_log(bfqd, "dispatch requests: %d busy queues", bfqd->busy_queues);
+ if (bfqd->busy_queues == 0)
+ return 0;
+
+ if (unlikely(force))
+ return bfq_forced_dispatch(bfqd);
+
+ dispatched = 0;
+ while ((bfqq = bfq_select_queue(bfqd)) != NULL) {
+ int max_dispatch;
+
+ max_dispatch = bfqd->bfq_quantum;
+ if (bfq_class_idle(bfqq))
+ max_dispatch = 1;
+
+ if (!bfq_bfqq_sync(bfqq))
+ max_dispatch = bfqd->bfq_max_budget_async_rq;
+
+ if (bfqq->dispatched >= max_dispatch) {
+ if (bfqd->busy_queues > 1)
+ break;
+ if (bfqq->dispatched >= 4 * max_dispatch)
+ break;
+ }
+
+ if (bfqd->sync_flight != 0 && !bfq_bfqq_sync(bfqq))
+ break;
+
+ bfq_clear_bfqq_wait_request(bfqq);
+ BUG_ON(timer_pending(&bfqd->idle_slice_timer));
+
+ dispatched += __bfq_dispatch_requests(bfqd, bfqq, max_dispatch);
+ bfq_log_bfqq(bfqd, bfqq, "total dispatched increased to %d "
+ "(max_disp %d)", dispatched, max_dispatch);
+ }
+
+ bfq_log(bfqd, "final total dispatched=%d", dispatched);
+ return dispatched;
+}
+
+/*
+ * Task holds one reference to the queue, dropped when task exits. Each rq
+ * in-flight on this queue also holds a reference, dropped when rq is freed.
+ *
+ * Queue lock must be held here.
+ */
+static void bfq_put_queue(struct bfq_queue *bfqq)
+{
+ struct bfq_data *bfqd = bfqq->bfqd;
+
+ BUG_ON(atomic_read(&bfqq->ref) <= 0);
+
+ bfq_log_bfqq(bfqd, bfqq, "put_queue: %p %d", bfqq, bfqq->ref);
+ if (!atomic_dec_and_test(&bfqq->ref))
+ return;
+
+ BUG_ON(rb_first(&bfqq->sort_list) != NULL);
+ BUG_ON(bfqq->allocated[READ] + bfqq->allocated[WRITE] != 0);
+ BUG_ON(bfqq->entity.tree != NULL);
+ BUG_ON(bfq_bfqq_busy(bfqq));
+ BUG_ON(bfqd->active_queue == bfqq);
+
+ bfq_log_bfqq(bfqd, bfqq, "put_queue: %p freed", bfqq);
+
+ kmem_cache_free(bfq_pool, bfqq);
+}
+
+static void bfq_exit_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq)
+{
+ if (bfqq == bfqd->active_queue) {
+ __bfq_bfqq_expire(bfqd, bfqq);
+ bfq_schedule_dispatch(bfqd);
+ }
+
+ bfq_log_bfqq(bfqd, bfqq, "exit_bfqq: %p, %d", bfqq, bfqq->ref);
+ bfq_put_queue(bfqq);
+}
+
+/*
+ * Update the entity prio values; note that the new values will not
+ * be used until the next (re)activation.
+ */
+static void bfq_init_prio_data(struct bfq_queue *bfqq, struct io_context *ioc)
+{
+ struct task_struct *tsk = current;
+ int ioprio_class;
+
+ if (!bfq_bfqq_prio_changed(bfqq))
+ return;
+
+ ioprio_class = IOPRIO_PRIO_CLASS(ioc->ioprio);
+ switch (ioprio_class) {
+ default:
+ printk(KERN_ERR "bfq: bad prio %x\n", ioprio_class);
+ case IOPRIO_CLASS_NONE:
+ /*
+ * No prio set, inherit CPU scheduling settings.
+ */
+ bfqq->entity.new_ioprio = task_nice_ioprio(tsk);
+ bfqq->entity.new_ioprio_class = task_nice_ioclass(tsk);
+ break;
+ case IOPRIO_CLASS_RT:
+ bfqq->entity.new_ioprio = task_ioprio(ioc);
+ bfqq->entity.new_ioprio_class = IOPRIO_CLASS_RT;
+ break;
+ case IOPRIO_CLASS_BE:
+ bfqq->entity.new_ioprio = task_ioprio(ioc);
+ bfqq->entity.new_ioprio_class = IOPRIO_CLASS_BE;
+ break;
+ case IOPRIO_CLASS_IDLE:
+ bfqq->entity.new_ioprio_class = IOPRIO_CLASS_IDLE;
+ bfqq->entity.new_ioprio = 7;
+ bfq_clear_bfqq_idle_window(bfqq);
+ break;
+ }
+
+ bfqq->entity.ioprio_changed = 1;
+
+ /*
+ * Keep track of original prio settings in case we have to temporarily
+ * elevate the priority of this queue.
+ */
+ bfqq->org_ioprio = bfqq->entity.new_ioprio;
+ bfqq->org_ioprio_class = bfqq->entity.new_ioprio_class;
+ bfq_clear_bfqq_prio_changed(bfqq);
+}
+
+static void bfq_changed_ioprio(struct io_context *ioc,
+ struct cfq_io_context *cic)
+{
+ struct bfq_data *bfqd;
+ struct bfq_queue *bfqq, *new_bfqq;
+ struct bfq_group *bfqg;
+ unsigned long uninitialized_var(flags);
+
+ bfqd = bfq_get_bfqd_locked(&cic->key, &flags);
+ if (unlikely(bfqd == NULL))
+ return;
+
+ bfqq = cic->cfqq[ASYNC];
+ if (bfqq != NULL) {
+ bfqg = container_of(bfqq->entity.sched_data, struct bfq_group,
+ sched_data);
+ new_bfqq = bfq_get_queue(bfqd, bfqg, ASYNC, cic->ioc,
+ GFP_ATOMIC);
+ if (new_bfqq != NULL) {
+ cic->cfqq[ASYNC] = new_bfqq;
+ bfq_log_bfqq(bfqd, bfqq,
+ "changed_ioprio: bfqq %p %d",
+ bfqq, bfqq->ref);
+ bfq_put_queue(bfqq);
+ }
+ }
+
+ bfqq = cic->cfqq[SYNC];
+ if (bfqq != NULL)
+ bfq_mark_bfqq_prio_changed(bfqq);
+
+ bfq_put_bfqd_unlock(bfqd, &flags);
+}
+
+static struct bfq_queue *bfq_find_alloc_queue(struct bfq_data *bfqd,
+ struct bfq_group *bfqg,
+ int is_sync,
+ struct io_context *ioc,
+ gfp_t gfp_mask)
+{
+ struct bfq_queue *bfqq, *new_bfqq = NULL;
+ struct cfq_io_context *cic;
+
+retry:
+ cic = bfq_cic_lookup(bfqd, ioc);
+ /* cic always exists here */
+ bfqq = cic_to_bfqq(cic, is_sync);
+
+ if (bfqq == NULL) {
+ if (new_bfqq != NULL) {
+ bfqq = new_bfqq;
+ new_bfqq = 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(bfqd->queue->queue_lock);
+ new_bfqq = kmem_cache_alloc_node(bfq_pool,
+ gfp_mask | __GFP_NOFAIL | __GFP_ZERO,
+ bfqd->queue->node);
+ spin_lock_irq(bfqd->queue->queue_lock);
+ goto retry;
+ } else {
+ bfqq = kmem_cache_alloc_node(bfq_pool,
+ gfp_mask | __GFP_ZERO,
+ bfqd->queue->node);
+ if (bfqq == NULL)
+ goto out;
+ }
+
+ RB_CLEAR_NODE(&bfqq->entity.rb_node);
+ INIT_LIST_HEAD(&bfqq->fifo);
+
+ atomic_set(&bfqq->ref, 0);
+ bfqq->bfqd = bfqd;
+
+ bfq_mark_bfqq_prio_changed(bfqq);
+
+ bfq_init_prio_data(bfqq, ioc);
+ bfq_init_entity(&bfqq->entity, bfqg);
+
+ if (is_sync) {
+ if (!bfq_class_idle(bfqq))
+ bfq_mark_bfqq_idle_window(bfqq);
+ bfq_mark_bfqq_sync(bfqq);
+ }
+ /* Tentative initial value to trade off between thr and lat */
+ bfqq->max_budget = (2 * bfq_max_budget(bfqd)) / 3;
+ bfqq->pid = current->pid;
+
+ bfqq->last_activation_time = 0;
+ bfqq->high_weight_budget = 0;
+
+ bfq_log_bfqq(bfqd, bfqq, "allocated");
+ }
+
+ if (new_bfqq != NULL)
+ kmem_cache_free(bfq_pool, new_bfqq);
+
+out:
+ WARN_ON((gfp_mask & __GFP_WAIT) && bfqq == NULL);
+ return bfqq;
+}
+
+static struct bfq_queue **bfq_async_queue_prio(struct bfq_data *bfqd,
+ struct bfq_group *bfqg,
+ int ioprio_class, int ioprio)
+{
+ switch (ioprio_class) {
+ case IOPRIO_CLASS_RT:
+ return &bfqg->async_bfqq[0][ioprio];
+ case IOPRIO_CLASS_BE:
+ return &bfqg->async_bfqq[1][ioprio];
+ case IOPRIO_CLASS_IDLE:
+ return &bfqg->async_idle_bfqq;
+ default:
+ BUG();
+ }
+}
+
+static struct bfq_queue *bfq_get_queue(struct bfq_data *bfqd,
+ struct bfq_group *bfqg, int is_sync,
+ struct io_context *ioc, gfp_t gfp_mask)
+{
+ const int ioprio = task_ioprio(ioc);
+ const int ioprio_class = task_ioprio_class(ioc);
+ struct bfq_queue **async_bfqq = NULL;
+ struct bfq_queue *bfqq = NULL;
+
+ if (!is_sync) {
+ async_bfqq = bfq_async_queue_prio(bfqd, bfqg, ioprio_class,
+ ioprio);
+ bfqq = *async_bfqq;
+ }
+
+ if (bfqq == NULL) {
+ bfqq = bfq_find_alloc_queue(bfqd, bfqg, is_sync, ioc, gfp_mask);
+ if (bfqq == NULL)
+ return NULL;
+ }
+
+ /*
+ * Pin the queue now that it's allocated, scheduler exit will prune it.
+ */
+ if (!is_sync && *async_bfqq == NULL) {
+ atomic_inc(&bfqq->ref);
+ bfq_log_bfqq(bfqd, bfqq, "get_queue, bfqq not in async: %p, %d",
+ bfqq, bfqq->ref);
+ *async_bfqq = bfqq;
+ }
+
+ atomic_inc(&bfqq->ref);
+ bfq_log_bfqq(bfqd, bfqq, "get_queue, at end: %p, %d", bfqq, bfqq->ref);
+ return bfqq;
+}
+
+static void bfq_update_io_thinktime(struct bfq_data *bfqd,
+ struct cfq_io_context *cic)
+{
+ unsigned long elapsed = jiffies - cic->last_end_request;
+ unsigned long ttime = min(elapsed, 2UL * bfqd->bfq_slice_idle);
+
+ cic->ttime_samples = (7*cic->ttime_samples + 256) / 8;
+ cic->ttime_total = (7*cic->ttime_total + 256*ttime) / 8;
+ cic->ttime_mean = (cic->ttime_total + 128) / cic->ttime_samples;
+}
+
+static void bfq_update_io_seektime(struct bfq_data *bfqd,
+ struct bfq_queue *bfqq,
+ struct request *rq)
+{
+ sector_t sdist;
+ u64 total;
+
+ if (bfqq->last_request_pos < blk_rq_pos(rq))
+ sdist = blk_rq_pos(rq) - bfqq->last_request_pos;
+ else
+ sdist = bfqq->last_request_pos - blk_rq_pos(rq);
+
+ /*
+ * Don't allow the seek distance to get too large from the
+ * odd fragment, pagein, etc.
+ */
+ if (bfqq->seek_samples == 0) /* first request, not really a seek */
+ sdist = 0;
+ else if (bfqq->seek_samples <= 60) /* second & third seek */
+ sdist = min(sdist, (bfqq->seek_mean * 4) + 2*1024*1024);
+ else
+ sdist = min(sdist, (bfqq->seek_mean * 4) + 2*1024*64);
+
+ bfqq->seek_samples = (7*bfqq->seek_samples + 256) / 8;
+ bfqq->seek_total = (7*bfqq->seek_total + (u64)256*sdist) / 8;
+ total = bfqq->seek_total + (bfqq->seek_samples/2);
+ do_div(total, bfqq->seek_samples);
+ bfqq->seek_mean = (sector_t)total;
+
+ bfq_log_bfqq(bfqd, bfqq, "dist=%llu mean=%llu", (u64)sdist,
+ (u64)bfqq->seek_mean);
+}
+
+/*
+ * Disable idle window if the process thinks too long or seeks so much that
+ * it doesn't matter.
+ */
+static void bfq_update_idle_window(struct bfq_data *bfqd,
+ struct bfq_queue *bfqq,
+ struct cfq_io_context *cic)
+{
+ int enable_idle;
+
+ /* Don't idle for async or idle io prio class. */
+ if (!bfq_bfqq_sync(bfqq) || bfq_class_idle(bfqq))
+ return;
+
+ enable_idle = bfq_bfqq_idle_window(bfqq);
+
+ if (atomic_read(&cic->ioc->nr_tasks) == 0 ||
+ bfqd->bfq_slice_idle == 0 || (bfqd->hw_tag && BFQQ_SEEKY(bfqq)))
+ enable_idle = 0;
+ else if (bfq_sample_valid(cic->ttime_samples)) {
+ if (cic->ttime_mean > bfqd->bfq_slice_idle)
+ enable_idle = 0;
+ else
+ enable_idle = 1;
+ }
+ bfq_log_bfqq(bfqd, bfqq, "update_idle_window: enable_idle %d",
+ enable_idle);
+
+ if (enable_idle)
+ bfq_mark_bfqq_idle_window(bfqq);
+ else
+ bfq_clear_bfqq_idle_window(bfqq);
+}
+
+/*
+ * Called when a new fs request (rq) is added to bfqq. Check if there's
+ * something we should do about it.
+ */
+static void bfq_rq_enqueued(struct bfq_data *bfqd, struct bfq_queue *bfqq,
+ struct request *rq)
+{
+ struct cfq_io_context *cic = RQ_CIC(rq);
+
+ if (rq_is_meta(rq))
+ bfqq->meta_pending++;
+
+ bfq_update_io_thinktime(bfqd, cic);
+ bfq_update_io_seektime(bfqd, bfqq, rq);
+ if (bfqq->entity.service > bfq_max_budget(bfqd) / 8 ||
+ ! BFQQ_SEEKY(bfqq))
+ bfq_update_idle_window(bfqd, bfqq, cic);
+
+ bfq_log_bfqq(bfqd, bfqq,
+ "rq_enqueued: idle_window=%d (seeky %d, mean %llu)",
+ bfq_bfqq_idle_window(bfqq), BFQQ_SEEKY(bfqq),
+ bfqq->seek_mean);
+
+ bfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq);
+
+ if (bfqq == bfqd->active_queue) {
+ if (bfq_bfqq_wait_request(bfqq)) {
+ /*
+ * If we are waiting for a request for this queue, let
+ * it rip immediately and flag that we must not expire
+ * this queue just now.
+ */
+ bfq_clear_bfqq_wait_request(bfqq);
+ del_timer(&bfqd->idle_slice_timer);
+ /*
+ * Here we can safely expire the queue, in
+ * case of budget timeout, without wasting
+ * guarantees
+ */
+ if (bfq_bfqq_budget_timeout(bfqq))
+ bfq_bfqq_expire(bfqd, bfqq, 0,
+ BFQ_BFQQ_BUDGET_TIMEOUT);
+ __blk_run_queue(bfqd->queue);
+ }
+ }
+}
+
+static void bfq_insert_request(struct request_queue *q, struct request *rq)
+{
+ struct bfq_data *bfqd = q->elevator->elevator_data;
+ struct bfq_queue *bfqq = RQ_BFQQ(rq);
+
+ assert_spin_locked(bfqd->queue->queue_lock);
+ bfq_init_prio_data(bfqq, RQ_CIC(rq)->ioc);
+
+ bfq_add_rq_rb(rq);
+
+ list_add_tail(&rq->queuelist, &bfqq->fifo);
+
+ bfq_rq_enqueued(bfqd, bfqq, rq);
+}
+
+static void bfq_update_hw_tag(struct bfq_data *bfqd)
+{
+ bfqd->max_rq_in_driver = max(bfqd->max_rq_in_driver,
+ bfqd->rq_in_driver);
+
+ /*
+ * This sample is valid if the number of outstanding requests
+ * is large enough to allow a queueing behavior. Note that the
+ * sum is not exact, as it's not taking into account deactivated
+ * requests.
+ */
+ if (bfqd->rq_in_driver + bfqd->queued < BFQ_HW_QUEUE_THRESHOLD)
+ return;
+
+ if (bfqd->hw_tag_samples++ < BFQ_HW_QUEUE_SAMPLES)
+ return;
+
+ bfqd->hw_tag = bfqd->max_rq_in_driver > BFQ_HW_QUEUE_THRESHOLD;
+ bfqd->max_rq_in_driver = 0;
+ bfqd->hw_tag_samples = 0;
+}
+
+static void bfq_completed_request(struct request_queue *q, struct request *rq)
+{
+ struct bfq_queue *bfqq = RQ_BFQQ(rq);
+ struct bfq_data *bfqd = bfqq->bfqd;
+ const int sync = rq_is_sync(rq);
+
+ bfq_log_bfqq(bfqd, bfqq, "completed %lu sects req (%d)",
+ blk_rq_sectors(rq), sync);
+
+ bfq_update_hw_tag(bfqd);
+
+ WARN_ON(!bfqd->rq_in_driver);
+ WARN_ON(!bfqq->dispatched);
+ bfqd->rq_in_driver--;
+ bfqq->dispatched--;
+
+ if (bfq_bfqq_sync(bfqq))
+ bfqd->sync_flight--;
+
+ if (sync)
+ RQ_CIC(rq)->last_end_request = jiffies;
+
+ /*
+ * If this is the active queue, check if it needs to be expired,
+ * or if we want to idle in case it has no pending requests.
+ */
+ if (bfqd->active_queue == bfqq) {
+ if (bfq_bfqq_budget_new(bfqq))
+ bfq_set_budget_timeout(bfqd);
+
+ if (bfq_may_expire_for_budg_timeout(bfqq))
+ bfq_bfqq_expire(bfqd, bfqq, 0, BFQ_BFQQ_BUDGET_TIMEOUT);
+ else if (sync && bfqd->rq_in_driver == 0 &&
+ RB_EMPTY_ROOT(&bfqq->sort_list))
+ bfq_arm_slice_timer(bfqd);
+ }
+
+ if (!bfqd->rq_in_driver)
+ bfq_schedule_dispatch(bfqd);
+}
+
+/*
+ * We temporarily boost lower priority queues if they are holding fs exclusive
+ * resources. They are boosted to normal prio (CLASS_BE/4).
+ */
+static void bfq_prio_boost(struct bfq_queue *bfqq)
+{
+ if (has_fs_excl()) {
+ /*
+ * Boost idle prio on transactions that would lock out other
+ * users of the filesystem
+ */
+ if (bfq_class_idle(bfqq))
+ bfqq->entity.new_ioprio_class = IOPRIO_CLASS_BE;
+ if (bfqq->entity.new_ioprio > IOPRIO_NORM)
+ bfqq->entity.new_ioprio = IOPRIO_NORM;
+ } else {
+ /*
+ * Check if we need to unboost the queue
+ */
+ if (bfqq->entity.new_ioprio_class != bfqq->org_ioprio_class)
+ bfqq->entity.new_ioprio_class = bfqq->org_ioprio_class;
+ if (bfqq->entity.new_ioprio != bfqq->org_ioprio)
+ bfqq->entity.new_ioprio = bfqq->org_ioprio;
+ }
+}
+
+static inline int __bfq_may_queue(struct bfq_queue *bfqq)
+{
+ if (bfq_bfqq_wait_request(bfqq) && bfq_bfqq_must_alloc(bfqq)) {
+ bfq_clear_bfqq_must_alloc(bfqq);
+ return ELV_MQUEUE_MUST;
+ }
+
+ return ELV_MQUEUE_MAY;
+}
+
+static int bfq_may_queue(struct request_queue *q, int rw)
+{
+ struct bfq_data *bfqd = q->elevator->elevator_data;
+ struct task_struct *tsk = current;
+ struct cfq_io_context *cic;
+ struct bfq_queue *bfqq;
+
+ /*
+ * Don't force setup of a queue from here, as a call to may_queue
+ * does not necessarily imply that a request actually will be queued.
+ * So just lookup a possibly existing queue, or return 'may queue'
+ * if that fails.
+ */
+ cic = bfq_cic_lookup(bfqd, tsk->io_context);
+ if (cic == NULL)
+ return ELV_MQUEUE_MAY;
+
+ bfqq = cic_to_bfqq(cic, rw & REQ_RW_SYNC);
+ if (bfqq != NULL) {
+ bfq_init_prio_data(bfqq, cic->ioc);
+ bfq_prio_boost(bfqq);
+
+ return __bfq_may_queue(bfqq);
+ }
+
+ return ELV_MQUEUE_MAY;
+}
+
+/*
+ * Queue lock held here.
+ */
+static void bfq_put_request(struct request *rq)
+{
+ struct bfq_queue *bfqq = RQ_BFQQ(rq);
+
+ if (bfqq != NULL) {
+ const int rw = rq_data_dir(rq);
+
+ BUG_ON(!bfqq->allocated[rw]);
+ bfqq->allocated[rw]--;
+
+ put_io_context(RQ_CIC(rq)->ioc);
+
+ rq->elevator_private = NULL;
+ rq->elevator_private2 = NULL;
+
+ bfq_log_bfqq(bfqq->bfqd, bfqq, "put_request %p, %d",
+ bfqq, bfqq->ref);
+ bfq_put_queue(bfqq);
+ }
+}
+
+/*
+ * Allocate bfq data structures associated with this request.
+ */
+static int bfq_set_request(struct request_queue *q, struct request *rq,
+ gfp_t gfp_mask)
+{
+ struct bfq_data *bfqd = q->elevator->elevator_data;
+ struct cfq_io_context *cic;
+ const int rw = rq_data_dir(rq);
+ const int is_sync = rq_is_sync(rq);
+ struct bfq_queue *bfqq;
+ struct bfq_group *bfqg;
+ unsigned long flags;
+
+ might_sleep_if(gfp_mask & __GFP_WAIT);
+
+ cic = bfq_get_io_context(bfqd, gfp_mask);
+
+ spin_lock_irqsave(q->queue_lock, flags);
+
+ if (cic == NULL)
+ goto queue_fail;
+
+ bfqg = bfq_cic_update_cgroup(cic);
+
+ bfqq = cic_to_bfqq(cic, is_sync);
+ if (bfqq == NULL) {
+ bfqq = bfq_get_queue(bfqd, bfqg, is_sync, cic->ioc, gfp_mask);
+ if (bfqq == NULL)
+ goto queue_fail;
+
+ cic_set_bfqq(cic, bfqq, is_sync);
+ }
+
+ bfqq->allocated[rw]++;
+ atomic_inc(&bfqq->ref);
+ bfq_log_bfqq(bfqd, bfqq, "set_request: bfqq %p, %d", bfqq, bfqq->ref);
+
+ spin_unlock_irqrestore(q->queue_lock, flags);
+
+ rq->elevator_private = cic;
+ rq->elevator_private2 = bfqq;
+
+ return 0;
+
+queue_fail:
+ if (cic != NULL)
+ put_io_context(cic->ioc);
+
+ bfq_schedule_dispatch(bfqd);
+ spin_unlock_irqrestore(q->queue_lock, flags);
+
+ return 1;
+}
+
+static void bfq_kick_queue(struct work_struct *work)
+{
+ struct bfq_data *bfqd =
+ container_of(work, struct bfq_data, unplug_work);
+ struct request_queue *q = bfqd->queue;
+ unsigned long flags;
+
+ spin_lock_irqsave(q->queue_lock, flags);
+ __blk_run_queue(q);
+ spin_unlock_irqrestore(q->queue_lock, flags);
+}
+
+/*
+ * Handler of the expiration of the timer running if the active_queue
+ * is idling inside its time slice.
+ */
+static void bfq_idle_slice_timer(unsigned long data)
+{
+ struct bfq_data *bfqd = (struct bfq_data *)data;
+ struct bfq_queue *bfqq;
+ unsigned long flags;
+ enum bfqq_expiration reason;
+
+ spin_lock_irqsave(bfqd->queue->queue_lock, flags);
+
+ bfqq = bfqd->active_queue;
+ /*
+ * Theoretical race here: active_queue can be NULL or different
+ * from the queue that was idling if the timer handler spins on
+ * the queue_lock and a new request arrives for the current
+ * queue and there is a full dispatch cycle that changes the
+ * active_queue. This can hardly happen, but in the worst case
+ * we just expire a queue too early.
+ */
+ if (bfqq != NULL) {
+ bfq_log_bfqq(bfqd, bfqq, "slice_timer expired");
+ reason = BFQ_BFQQ_TOO_IDLE;
+ if (bfq_bfqq_budget_timeout(bfqq))
+ /*
+ * Also here the queue can be safely expired
+ * for budget timeout without wasting
+ * guarantees
+ */
+ reason = BFQ_BFQQ_BUDGET_TIMEOUT;
+
+ bfq_bfqq_expire(bfqd, bfqq, 1, reason);
+ }
+
+ bfq_schedule_dispatch(bfqd);
+
+ spin_unlock_irqrestore(bfqd->queue->queue_lock, flags);
+}
+
+static void bfq_shutdown_timer_wq(struct bfq_data *bfqd)
+{
+ del_timer_sync(&bfqd->idle_slice_timer);
+ cancel_work_sync(&bfqd->unplug_work);
+}
+
+static inline void __bfq_put_async_bfqq(struct bfq_data *bfqd,
+ struct bfq_queue **bfqq_ptr)
+{
+ struct bfq_group *root_group = bfqd->root_group;
+ struct bfq_queue *bfqq = *bfqq_ptr;
+
+ bfq_log(bfqd, "put_async_bfqq: %p", bfqq);
+ if (bfqq != NULL) {
+ bfq_bfqq_move(bfqd, bfqq, &bfqq->entity, root_group);
+ bfq_log_bfqq(bfqd, bfqq, "put_async_bfqq: putting %p, %d",
+ bfqq, bfqq->ref);
+ bfq_put_queue(bfqq);
+ *bfqq_ptr = NULL;
+ }
+}
+
+/*
+ * Release all the bfqg references to its async queues. If we are
+ * deallocating the group these queues may still contain requests, so
+ * we reparent them to the root cgroup (i.e., the only one that will
+ * exist for sure untill all the requests on a device are gone).
+ */
+static void bfq_put_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg)
+{
+ int i, j;
+
+ for (i = 0; i < 2; i++)
+ for (j = 0; j < IOPRIO_BE_NR; j++)
+ __bfq_put_async_bfqq(bfqd, &bfqg->async_bfqq[i][j]);
+
+ __bfq_put_async_bfqq(bfqd, &bfqg->async_idle_bfqq);
+}
+
+static void bfq_exit_queue(struct elevator_queue *e)
+{
+ struct bfq_data *bfqd = e->elevator_data;
+ struct request_queue *q = bfqd->queue;
+ struct bfq_queue *bfqq, *n;
+ struct cfq_io_context *cic;
+
+ bfq_shutdown_timer_wq(bfqd);
+
+ spin_lock_irq(q->queue_lock);
+
+ while (!list_empty(&bfqd->cic_list)) {
+ cic = list_entry(bfqd->cic_list.next, struct cfq_io_context,
+ queue_list);
+ __bfq_exit_single_io_context(bfqd, cic);
+ }
+
+ BUG_ON(bfqd->active_queue != NULL);
+ list_for_each_entry_safe(bfqq, n, &bfqd->idle_list, bfqq_list)
+ bfq_deactivate_bfqq(bfqd, bfqq, 0);
+
+ bfq_disconnect_groups(bfqd);
+ spin_unlock_irq(q->queue_lock);
+
+ bfq_shutdown_timer_wq(bfqd);
+
+ /* Wait for cic->key accessors to exit their grace periods. */
+ synchronize_rcu();
+
+ BUG_ON(timer_pending(&bfqd->idle_slice_timer));
+
+ bfq_free_root_group(bfqd);
+ kfree(bfqd);
+}
+
+static void *bfq_init_queue(struct request_queue *q)
+{
+ struct bfq_group *bfqg;
+ struct bfq_data *bfqd;
+
+ bfqd = kmalloc_node(sizeof(*bfqd), GFP_KERNEL | __GFP_ZERO, q->node);
+ if (bfqd == NULL)
+ return NULL;
+
+ INIT_LIST_HEAD(&bfqd->cic_list);
+
+ bfqd->queue = q;
+
+ bfqg = bfq_alloc_root_group(bfqd, q->node);
+ if (bfqg == NULL) {
+ kfree(bfqd);
+ return NULL;
+ }
+
+ bfqd->root_group = bfqg;
+
+ init_timer(&bfqd->idle_slice_timer);
+ bfqd->idle_slice_timer.function = bfq_idle_slice_timer;
+ bfqd->idle_slice_timer.data = (unsigned long)bfqd;
+
+ INIT_WORK(&bfqd->unplug_work, bfq_kick_queue);
+
+ INIT_LIST_HEAD(&bfqd->active_list);
+ INIT_LIST_HEAD(&bfqd->idle_list);
+
+ bfqd->hw_tag = 1;
+
+ bfqd->bfq_max_budget = bfq_default_max_budget;
+
+ bfqd->bfq_quantum = bfq_quantum;
+ bfqd->bfq_fifo_expire[0] = bfq_fifo_expire[0];
+ bfqd->bfq_fifo_expire[1] = bfq_fifo_expire[1];
+ bfqd->bfq_back_max = bfq_back_max;
+ bfqd->bfq_back_penalty = bfq_back_penalty;
+ bfqd->bfq_slice_idle = bfq_slice_idle;
+ bfqd->bfq_max_budget_async_rq = bfq_max_budget_async_rq;
+ bfqd->bfq_timeout[ASYNC] = bfq_timeout_async;
+ bfqd->bfq_timeout[SYNC] = bfq_timeout_sync;
+
+ bfqd->low_latency = true;
+
+ return bfqd;
+}
+
+static void bfq_slab_kill(void)
+{
+ if (bfq_pool != NULL)
+ kmem_cache_destroy(bfq_pool);
+ if (bfq_ioc_pool != NULL)
+ kmem_cache_destroy(bfq_ioc_pool);
+}
+
+static int __init bfq_slab_setup(void)
+{
+ bfq_pool = KMEM_CACHE(bfq_queue, 0);
+ if (bfq_pool == NULL)
+ goto fail;
+
+ bfq_ioc_pool = kmem_cache_create("bfq_io_context",
+ sizeof(struct cfq_io_context),
+ __alignof__(struct cfq_io_context),
+ 0, NULL);
+ if (bfq_ioc_pool == NULL)
+ goto fail;
+
+ return 0;
+fail:
+ bfq_slab_kill();
+ return -ENOMEM;
+}
+
+static ssize_t bfq_var_show(unsigned int var, char *page)
+{
+ return sprintf(page, "%d\n", var);
+}
+
+static ssize_t bfq_var_store(unsigned int *var, const char *page, size_t count)
+{
+ char *p = (char *)page;
+
+ *var = simple_strtoul(p, &p, 10);
+ return count;
+}
+
+#define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
+static ssize_t __FUNC(struct elevator_queue *e, char *page) \
+{ \
+ struct bfq_data *bfqd = e->elevator_data; \
+ unsigned int __data = __VAR; \
+ if (__CONV) \
+ __data = jiffies_to_msecs(__data); \
+ return bfq_var_show(__data, (page)); \
+}
+SHOW_FUNCTION(bfq_quantum_show, bfqd->bfq_quantum, 0);
+SHOW_FUNCTION(bfq_fifo_expire_sync_show, bfqd->bfq_fifo_expire[1], 1);
+SHOW_FUNCTION(bfq_fifo_expire_async_show, bfqd->bfq_fifo_expire[0], 1);
+SHOW_FUNCTION(bfq_back_seek_max_show, bfqd->bfq_back_max, 0);
+SHOW_FUNCTION(bfq_back_seek_penalty_show, bfqd->bfq_back_penalty, 0);
+SHOW_FUNCTION(bfq_slice_idle_show, bfqd->bfq_slice_idle, 1);
+SHOW_FUNCTION(bfq_max_budget_show, bfqd->bfq_user_max_budget, 0);
+SHOW_FUNCTION(bfq_max_budget_async_rq_show, bfqd->bfq_max_budget_async_rq, 0);
+SHOW_FUNCTION(bfq_timeout_sync_show, bfqd->bfq_timeout[SYNC], 1);
+SHOW_FUNCTION(bfq_timeout_async_show, bfqd->bfq_timeout[ASYNC], 1);
+SHOW_FUNCTION(bfq_low_latency_show, bfqd->low_latency, 0);
+#undef SHOW_FUNCTION
+
+#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
+static ssize_t \
+__FUNC(struct elevator_queue *e, const char *page, size_t count) \
+{ \
+ struct bfq_data *bfqd = e->elevator_data; \
+ unsigned int __data; \
+ int ret = bfq_var_store(&__data, (page), count); \
+ if (__data < (MIN)) \
+ __data = (MIN); \
+ else if (__data > (MAX)) \
+ __data = (MAX); \
+ if (__CONV) \
+ *(__PTR) = msecs_to_jiffies(__data); \
+ else \
+ *(__PTR) = __data; \
+ return ret; \
+}
+STORE_FUNCTION(bfq_quantum_store, &bfqd->bfq_quantum, 1, INT_MAX, 0);
+STORE_FUNCTION(bfq_fifo_expire_sync_store, &bfqd->bfq_fifo_expire[1], 1,
+ INT_MAX, 1);
+STORE_FUNCTION(bfq_fifo_expire_async_store, &bfqd->bfq_fifo_expire[0], 1,
+ INT_MAX, 1);
+STORE_FUNCTION(bfq_back_seek_max_store, &bfqd->bfq_back_max, 0, INT_MAX, 0);
+STORE_FUNCTION(bfq_back_seek_penalty_store, &bfqd->bfq_back_penalty, 1,
+ INT_MAX, 0);
+STORE_FUNCTION(bfq_slice_idle_store, &bfqd->bfq_slice_idle, 0, INT_MAX, 1);
+STORE_FUNCTION(bfq_max_budget_async_rq_store, &bfqd->bfq_max_budget_async_rq,
+ 1, INT_MAX, 0);
+STORE_FUNCTION(bfq_timeout_async_store, &bfqd->bfq_timeout[ASYNC], 0,
+ INT_MAX, 1);
+#undef STORE_FUNCTION
+
+static inline bfq_service_t bfq_estimated_max_budget(struct bfq_data *bfqd)
+{
+ u64 timeout = jiffies_to_msecs(bfqd->bfq_timeout[SYNC]);
+
+ if (bfqd->peak_rate_samples >= BFQ_PEAK_RATE_SAMPLES)
+ return bfq_calc_max_budget(bfqd->peak_rate, timeout);
+ else
+ return bfq_default_max_budget;
+}
+
+static ssize_t bfq_max_budget_store(struct elevator_queue *e,
+ const char *page, size_t count)
+{
+ struct bfq_data *bfqd = e->elevator_data;
+ unsigned int __data;
+ int ret = bfq_var_store(&__data, (page), count);
+
+ if (__data == 0)
+ bfqd->bfq_max_budget = bfq_estimated_max_budget(bfqd);
+ else {
+ if (__data > INT_MAX)
+ __data = INT_MAX;
+ bfqd->bfq_max_budget = __data;
+ }
+
+ bfqd->bfq_user_max_budget = __data;
+
+ return ret;
+}
+
+static ssize_t bfq_timeout_sync_store(struct elevator_queue *e,
+ const char *page, size_t count)
+{
+ struct bfq_data *bfqd = e->elevator_data;
+ unsigned int __data;
+ int ret = bfq_var_store(&__data, (page), count);
+
+ if (__data < 1)
+ __data = 1;
+ else if (__data > INT_MAX)
+ __data = INT_MAX;
+
+ bfqd->bfq_timeout[SYNC] = msecs_to_jiffies(__data);
+ if (bfqd->bfq_user_max_budget == 0)
+ bfqd->bfq_max_budget = bfq_estimated_max_budget(bfqd);
+
+ return ret;
+}
+
+static ssize_t bfq_low_latency_store(struct elevator_queue *e,
+ const char *page, size_t count)
+{
+ struct bfq_data *bfqd = e->elevator_data;
+ unsigned int __data;
+ int ret = bfq_var_store(&__data, (page), count);
+
+ if (__data > 1)
+ __data = 1;
+ bfqd->low_latency = __data;
+
+ return ret;
+}
+
+#define BFQ_ATTR(name) \
+ __ATTR(name, S_IRUGO|S_IWUSR, bfq_##name##_show, bfq_##name##_store)
+
+static struct elv_fs_entry bfq_attrs[] = {
+ BFQ_ATTR(quantum),
+ BFQ_ATTR(fifo_expire_sync),
+ BFQ_ATTR(fifo_expire_async),
+ BFQ_ATTR(back_seek_max),
+ BFQ_ATTR(back_seek_penalty),
+ BFQ_ATTR(slice_idle),
+ BFQ_ATTR(max_budget),
+ BFQ_ATTR(max_budget_async_rq),
+ BFQ_ATTR(timeout_sync),
+ BFQ_ATTR(timeout_async),
+ BFQ_ATTR(low_latency),
+ __ATTR_NULL
+};
+
+static struct elevator_type iosched_bfq = {
+ .ops = {
+ .elevator_merge_fn = bfq_merge,
+ .elevator_merged_fn = bfq_merged_request,
+ .elevator_merge_req_fn = bfq_merged_requests,
+ .elevator_allow_merge_fn = bfq_allow_merge,
+ .elevator_dispatch_fn = bfq_dispatch_requests,
+ .elevator_add_req_fn = bfq_insert_request,
+ .elevator_activate_req_fn = bfq_activate_request,
+ .elevator_deactivate_req_fn = bfq_deactivate_request,
+ .elevator_queue_empty_fn = bfq_queue_empty,
+ .elevator_completed_req_fn = bfq_completed_request,
+ .elevator_former_req_fn = elv_rb_former_request,
+ .elevator_latter_req_fn = elv_rb_latter_request,
+ .elevator_set_req_fn = bfq_set_request,
+ .elevator_put_req_fn = bfq_put_request,
+ .elevator_may_queue_fn = bfq_may_queue,
+ .elevator_init_fn = bfq_init_queue,
+ .elevator_exit_fn = bfq_exit_queue,
+ .trim = bfq_free_io_context,
+ },
+ .elevator_attrs = bfq_attrs,
+ .elevator_name = "bfq",
+ .elevator_owner = THIS_MODULE,
+};
+
+static int __init bfq_init(void)
+{
+ /*
+ * Can be 0 on HZ < 1000 setups.
+ */
+ if (bfq_slice_idle == 0)
+ bfq_slice_idle = 1;
+
+ if (bfq_timeout_async == 0)
+ bfq_timeout_async = 1;
+
+ if (bfq_slab_setup())
+ return -ENOMEM;
+
+ elv_register(&iosched_bfq);
+
+ return 0;
+}
+
+static void __exit bfq_exit(void)
+{
+ DECLARE_COMPLETION_ONSTACK(all_gone);
+ elv_unregister(&iosched_bfq);
+ bfq_ioc_gone = &all_gone;
+ /* bfq_ioc_gone's update must be visible before reading bfq_ioc_count */
+ smp_wmb();
+ if (elv_ioc_count_read(bfq_ioc_count) != 0)
+ wait_for_completion(&all_gone);
+ bfq_slab_kill();
+}
+
+module_init(bfq_init);
+module_exit(bfq_exit);
+
+MODULE_AUTHOR("Fabio Checconi, Paolo Valente");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Budget Fair Queueing IO scheduler");
diff --git a/block/bfq-sched.c b/block/bfq-sched.c
new file mode 100644
index 0000000..b4a6b1b
--- /dev/null
+++ b/block/bfq-sched.c
@@ -0,0 +1,1010 @@
+/*
+ * BFQ: Hierarchical B-WF2Q+ scheduler.
+ *
+ * Based on ideas and code from CFQ:
+ * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
+ *
+ * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
+ * Paolo Valente <paolo.valente@unimore.it>
+ */
+
+#ifdef CONFIG_CGROUP_BFQIO
+#define for_each_entity(entity) \
+ for (; entity != NULL; entity = entity->parent)
+
+#define for_each_entity_safe(entity, parent) \
+ for (; entity && ({ parent = entity->parent; 1; }); entity = parent)
+
+static struct bfq_entity *bfq_lookup_next_entity(struct bfq_sched_data *sd,
+ int extract);
+
+static int bfq_update_next_active(struct bfq_sched_data *sd)
+{
+ struct bfq_group *bfqg;
+ struct bfq_entity *entity, *next_active;
+
+ if (sd->active_entity != NULL)
+ /* will update/requeue at the end of service */
+ return 0;
+
+ /*
+ * NOTE: this can be improved in many ways, such as returning
+ * 1 (and thus propagating upwards the update) only when the
+ * budget changes, or caching the bfqq that will be scheduled
+ * next from this subtree. By now we worry more about
+ * correctness than about performance...
+ */
+ next_active = bfq_lookup_next_entity(sd, 0);
+ sd->next_active = next_active;
+
+ if (next_active != NULL) {
+ bfqg = container_of(sd, struct bfq_group, sched_data);
+ entity = bfqg->my_entity;
+ if (entity != NULL)
+ entity->budget = next_active->budget;
+ }
+
+ return 1;
+}
+
+static inline void bfq_check_next_active(struct bfq_sched_data *sd,
+ struct bfq_entity *entity)
+{
+ BUG_ON(sd->next_active != entity);
+}
+#else
+#define for_each_entity(entity) \
+ for (; entity != NULL; entity = NULL)
+
+#define for_each_entity_safe(entity, parent) \
+ for (parent = NULL; entity != NULL; entity = parent)
+
+static inline int bfq_update_next_active(struct bfq_sched_data *sd)
+{
+ return 0;
+}
+
+static inline void bfq_check_next_active(struct bfq_sched_data *sd,
+ struct bfq_entity *entity)
+{
+}
+#endif
+
+/*
+ * Shift for timestamp calculations. This actually limits the maximum
+ * service allowed in one timestamp delta (small shift values increase it),
+ * the maximum total weight that can be used for the queues in the system
+ * (big shift values increase it), and the period of virtual time wraparounds.
+ */
+#define WFQ_SERVICE_SHIFT 22
+
+/**
+ * bfq_gt - compare two timestamps.
+ * @a: first ts.
+ * @b: second ts.
+ *
+ * Return @a > @b, dealing with wrapping correctly.
+ */
+static inline int bfq_gt(bfq_timestamp_t a, bfq_timestamp_t b)
+{
+ return (s64)(a - b) > 0;
+}
+
+static inline struct bfq_queue *bfq_entity_to_bfqq(struct bfq_entity *entity)
+{
+ struct bfq_queue *bfqq = NULL;
+
+ BUG_ON(entity == NULL);
+
+ if (entity->my_sched_data == NULL)
+ bfqq = container_of(entity, struct bfq_queue, entity);
+
+ return bfqq;
+}
+
+
+/**
+ * bfq_delta - map service into the virtual time domain.
+ * @service: amount of service.
+ * @weight: scale factor (weight of an entity or weight sum).
+ */
+static inline bfq_timestamp_t bfq_delta(bfq_service_t service,
+ unsigned long weight)
+{
+ bfq_timestamp_t d = (bfq_timestamp_t)service << WFQ_SERVICE_SHIFT;
+
+ do_div(d, weight);
+ return d;
+}
+
+/**
+ * bfq_calc_finish - assign the finish time to an entity.
+ * @entity: the entity to act upon.
+ * @service: the service to be charged to the entity.
+ */
+static inline void bfq_calc_finish(struct bfq_entity *entity,
+ bfq_service_t service)
+{
+ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
+
+ BUG_ON(entity->weight == 0);
+
+ entity->finish = entity->start +
+ bfq_delta(service, entity->weight);
+
+ if (bfqq != NULL) {
+ bfq_log_bfqq(bfqq->bfqd, bfqq,
+ "calc_finish: serv %lu, w %lu, hi-budg %lu",
+ service, entity->weight,
+ bfqq->high_weight_budget);
+ bfq_log_bfqq(bfqq->bfqd, bfqq,
+ "calc_finish: start %llu, finish %llu, delta %llu",
+ entity->start, entity->finish,
+ bfq_delta(service, entity->weight));
+ }
+}
+
+/**
+ * bfq_entity_of - get an entity from a node.
+ * @node: the node field of the entity.
+ *
+ * Convert a node pointer to the relative entity. This is used only
+ * to simplify the logic of some functions and not as the generic
+ * conversion mechanism because, e.g., in the tree walking functions,
+ * the check for a %NULL value would be redundant.
+ */
+static inline struct bfq_entity *bfq_entity_of(struct rb_node *node)
+{
+ struct bfq_entity *entity = NULL;
+
+ if (node != NULL)
+ entity = rb_entry(node, struct bfq_entity, rb_node);
+
+ return entity;
+}
+
+/**
+ * bfq_extract - remove an entity from a tree.
+ * @root: the tree root.
+ * @entity: the entity to remove.
+ */
+static inline void bfq_extract(struct rb_root *root,
+ struct bfq_entity *entity)
+{
+ BUG_ON(entity->tree != root);
+
+ entity->tree = NULL;
+ rb_erase(&entity->rb_node, root);
+}
+
+/**
+ * bfq_idle_extract - extract an entity from the idle tree.
+ * @st: the service tree of the owning @entity.
+ * @entity: the entity being removed.
+ */
+static void bfq_idle_extract(struct bfq_service_tree *st,
+ struct bfq_entity *entity)
+{
+ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
+ struct rb_node *next;
+
+ BUG_ON(entity->tree != &st->idle);
+
+ if (entity == st->first_idle) {
+ next = rb_next(&entity->rb_node);
+ st->first_idle = bfq_entity_of(next);
+ }
+
+ if (entity == st->last_idle) {
+ next = rb_prev(&entity->rb_node);
+ st->last_idle = bfq_entity_of(next);
+ }
+
+ bfq_extract(&st->idle, entity);
+
+ if (bfqq != NULL)
+ list_del(&bfqq->bfqq_list);
+}
+
+/**
+ * bfq_insert - generic tree insertion.
+ * @root: tree root.
+ * @entity: entity to insert.
+ *
+ * This is used for the idle and the active tree, since they are both
+ * ordered by finish time.
+ */
+static void bfq_insert(struct rb_root *root, struct bfq_entity *entity)
+{
+ struct bfq_entity *entry;
+ struct rb_node **node = &root->rb_node;
+ struct rb_node *parent = NULL;
+
+ BUG_ON(entity->tree != NULL);
+
+ while (*node != NULL) {
+ parent = *node;
+ entry = rb_entry(parent, struct bfq_entity, rb_node);
+
+ if (bfq_gt(entry->finish, entity->finish))
+ node = &parent->rb_left;
+ else
+ node = &parent->rb_right;
+ }
+
+ rb_link_node(&entity->rb_node, parent, node);
+ rb_insert_color(&entity->rb_node, root);
+
+ entity->tree = root;
+}
+
+/**
+ * bfq_update_min - update the min_start field of a entity.
+ * @entity: the entity to update.
+ * @node: one of its children.
+ *
+ * This function is called when @entity may store an invalid value for
+ * min_start due to updates to the active tree. The function assumes
+ * that the subtree rooted at @node (which may be its left or its right
+ * child) has a valid min_start value.
+ */
+static inline void bfq_update_min(struct bfq_entity *entity,
+ struct rb_node *node)
+{
+ struct bfq_entity *child;
+
+ if (node != NULL) {
+ child = rb_entry(node, struct bfq_entity, rb_node);
+ if (bfq_gt(entity->min_start, child->min_start))
+ entity->min_start = child->min_start;
+ }
+}
+
+/**
+ * bfq_update_active_node - recalculate min_start.
+ * @node: the node to update.
+ *
+ * @node may have changed position or one of its children may have moved,
+ * this function updates its min_start value. The left and right subtrees
+ * are assumed to hold a correct min_start value.
+ */
+static inline void bfq_update_active_node(struct rb_node *node)
+{
+ struct bfq_entity *entity = rb_entry(node, struct bfq_entity, rb_node);
+
+ entity->min_start = entity->start;
+ bfq_update_min(entity, node->rb_right);
+ bfq_update_min(entity, node->rb_left);
+}
+
+/**
+ * bfq_update_active_tree - update min_start for the whole active tree.
+ * @node: the starting node.
+ *
+ * @node must be the deepest modified node after an update. This function
+ * updates its min_start using the values held by its children, assuming
+ * that they did not change, and then updates all the nodes that may have
+ * changed in the path to the root. The only nodes that may have changed
+ * are the ones in the path or their siblings.
+ */
+static void bfq_update_active_tree(struct rb_node *node)
+{
+ struct rb_node *parent;
+
+up:
+ bfq_update_active_node(node);
+
+ parent = rb_parent(node);
+ if (parent == NULL)
+ return;
+
+ if (node == parent->rb_left && parent->rb_right != NULL)
+ bfq_update_active_node(parent->rb_right);
+ else if (parent->rb_left != NULL)
+ bfq_update_active_node(parent->rb_left);
+
+ node = parent;
+ goto up;
+}
+
+/**
+ * bfq_active_insert - insert an entity in the active tree of its group/device.
+ * @st: the service tree of the entity.
+ * @entity: the entity being inserted.
+ *
+ * The active tree is ordered by finish time, but an extra key is kept
+ * per each node, containing the minimum value for the start times of
+ * its children (and the node itself), so it's possible to search for
+ * the eligible node with the lowest finish time in logarithmic time.
+ */
+static void bfq_active_insert(struct bfq_service_tree *st,
+ struct bfq_entity *entity)
+{
+ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
+ struct rb_node *node = &entity->rb_node;
+
+ bfq_insert(&st->active, entity);
+
+ if (node->rb_left != NULL)
+ node = node->rb_left;
+ else if (node->rb_right != NULL)
+ node = node->rb_right;
+
+ bfq_update_active_tree(node);
+
+ if (bfqq != NULL)
+ list_add(&bfqq->bfqq_list, &bfqq->bfqd->active_list);
+}
+
+/**
+ * bfq_ioprio_to_weight - calc a weight from an ioprio.
+ * @ioprio: the ioprio value to convert.
+ */
+static unsigned short bfq_ioprio_to_weight(int ioprio)
+{
+ WARN_ON(ioprio < 0 || ioprio >= IOPRIO_BE_NR);
+ return IOPRIO_BE_NR - ioprio;
+}
+
+/**
+ * bfq_weight_to_ioprio - calc an ioprio from a weight.
+ * @weight: the weight value to convert.
+ *
+ * To preserve as mush as possible the old only-ioprio user interface,
+ * 0 is used as an escape ioprio value for weights (numerically) equal or
+ * larger than