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-rw-r--r--block/cfq-iosched.c92
-rw-r--r--block/elevator.c16
2 files changed, 10 insertions, 98 deletions
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 6cc606560402..ff44435fad50 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -2669,24 +2669,6 @@ static void cfq_put_queue(struct cfq_queue *cfqq)
cfq_put_cfqg(cfqg);
}
-/*
- * Call func for each cic attached to this ioc.
- */
-static void
-call_for_each_cic(struct io_context *ioc,
- void (*func)(struct io_context *, struct cfq_io_context *))
-{
- struct cfq_io_context *cic;
- struct hlist_node *n;
-
- rcu_read_lock();
-
- hlist_for_each_entry_rcu(cic, n, &ioc->cic_list, cic_list)
- func(ioc, cic);
-
- rcu_read_unlock();
-}
-
static void cfq_cic_free_rcu(struct rcu_head *head)
{
struct cfq_io_context *cic;
@@ -2727,31 +2709,6 @@ static void cfq_release_cic(struct cfq_io_context *cic)
cfq_cic_free(cic);
}
-static void cic_free_func(struct io_context *ioc, struct cfq_io_context *cic)
-{
- unsigned long flags;
-
- spin_lock_irqsave(&ioc->lock, flags);
- cfq_release_cic(cic);
- spin_unlock_irqrestore(&ioc->lock, flags);
-}
-
-/*
- * Must be called with rcu_read_lock() held or preemption otherwise disabled.
- * Only two callers of this - ->dtor() which is called with the rcu_read_lock(),
- * and ->trim() which is called with the task lock held
- */
-static void cfq_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);
-}
-
static void cfq_put_cooperator(struct cfq_queue *cfqq)
{
struct cfq_queue *__cfqq, *next;
@@ -3037,30 +2994,6 @@ cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct io_context *ioc,
return cfqq;
}
-/*
- * We drop cfq io contexts lazily, so we may find a dead one.
- */
-static void
-cfq_drop_dead_cic(struct cfq_data *cfqd, struct io_context *ioc,
- struct cfq_io_context *cic)
-{
- unsigned long flags;
-
- WARN_ON(!list_empty(&cic->queue_list));
- BUG_ON(cic->key != cfqd_dead_key(cfqd));
-
- spin_lock_irqsave(&ioc->lock, flags);
-
- BUG_ON(rcu_dereference_check(ioc->ioc_data,
- lockdep_is_held(&ioc->lock)) == cic);
-
- radix_tree_delete(&ioc->radix_root, cfqd->queue->id);
- hlist_del_rcu(&cic->cic_list);
- spin_unlock_irqrestore(&ioc->lock, flags);
-
- cfq_cic_free(cic);
-}
-
/**
* cfq_cic_lookup - lookup cfq_io_context
* @cfqd: the associated cfq_data
@@ -3078,26 +3011,22 @@ cfq_cic_lookup(struct cfq_data *cfqd, struct io_context *ioc)
if (unlikely(!ioc))
return NULL;
- rcu_read_lock();
-
/*
- * we maintain a last-hit cache, to avoid browsing over the tree
+ * cic's are indexed from @ioc using radix tree and hint pointer,
+ * both of which are protected with RCU. All removals are done
+ * holding both q and ioc locks, and we're holding q lock - if we
+ * find a cic which points to us, it's guaranteed to be valid.
*/
+ rcu_read_lock();
cic = rcu_dereference(ioc->ioc_data);
if (cic && cic->key == cfqd)
goto out;
- do {
- cic = radix_tree_lookup(&ioc->radix_root, cfqd->queue->id);
- if (!cic)
- break;
- if (likely(cic->key == cfqd)) {
- /* hint assignment itself can race safely */
- rcu_assign_pointer(ioc->ioc_data, cic);
- break;
- }
- cfq_drop_dead_cic(cfqd, ioc, cic);
- } while (1);
+ cic = radix_tree_lookup(&ioc->radix_root, cfqd->queue->id);
+ if (cic && cic->key == cfqd)
+ rcu_assign_pointer(ioc->ioc_data, cic); /* allowed to race */
+ else
+ cic = NULL;
out:
rcu_read_unlock();
return cic;
@@ -4182,7 +4111,6 @@ static struct elevator_type iosched_cfq = {
.elevator_may_queue_fn = cfq_may_queue,
.elevator_init_fn = cfq_init_queue,
.elevator_exit_fn = cfq_exit_queue,
- .trim = cfq_free_io_context,
},
.elevator_attrs = cfq_attrs,
.elevator_name = "cfq",
diff --git a/block/elevator.c b/block/elevator.c
index 66343d6917d0..6a343e8f8319 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -913,22 +913,6 @@ EXPORT_SYMBOL_GPL(elv_register);
void elv_unregister(struct elevator_type *e)
{
- struct task_struct *g, *p;
-
- /*
- * Iterate every thread in the process to remove the io contexts.
- */
- if (e->ops.trim) {
- read_lock(&tasklist_lock);
- do_each_thread(g, p) {
- task_lock(p);
- if (p->io_context)
- e->ops.trim(p->io_context);
- task_unlock(p);
- } while_each_thread(g, p);
- read_unlock(&tasklist_lock);
- }
-
spin_lock(&elv_list_lock);
list_del_init(&e->list);
spin_unlock(&elv_list_lock);