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-rw-r--r--block/blk-ioc.c76
1 files changed, 68 insertions, 8 deletions
diff --git a/block/blk-ioc.c b/block/blk-ioc.c
index 87ecc98b8ade..0910a5584d38 100644
--- a/block/blk-ioc.c
+++ b/block/blk-ioc.c
@@ -44,6 +44,51 @@ EXPORT_SYMBOL(get_io_context);
#define ioc_release_depth_dec(q) do { } while (0)
#endif
+static void icq_free_icq_rcu(struct rcu_head *head)
+{
+ struct io_cq *icq = container_of(head, struct io_cq, __rcu_head);
+
+ kmem_cache_free(icq->__rcu_icq_cache, icq);
+}
+
+/*
+ * Exit and free an icq. Called with both ioc and q locked.
+ */
+static void ioc_exit_icq(struct io_cq *icq)
+{
+ struct io_context *ioc = icq->ioc;
+ struct request_queue *q = icq->q;
+ struct elevator_type *et = q->elevator->type;
+
+ lockdep_assert_held(&ioc->lock);
+ lockdep_assert_held(q->queue_lock);
+
+ radix_tree_delete(&ioc->icq_tree, icq->q->id);
+ hlist_del_init(&icq->ioc_node);
+ list_del_init(&icq->q_node);
+
+ /*
+ * Both setting lookup hint to and clearing it from @icq are done
+ * under queue_lock. If it's not pointing to @icq now, it never
+ * will. Hint assignment itself can race safely.
+ */
+ if (rcu_dereference_raw(ioc->icq_hint) == icq)
+ rcu_assign_pointer(ioc->icq_hint, NULL);
+
+ if (et->ops.elevator_exit_icq_fn) {
+ ioc_release_depth_inc(q);
+ et->ops.elevator_exit_icq_fn(icq);
+ ioc_release_depth_dec(q);
+ }
+
+ /*
+ * @icq->q might have gone away by the time RCU callback runs
+ * making it impossible to determine icq_cache. Record it in @icq.
+ */
+ icq->__rcu_icq_cache = et->icq_cache;
+ call_rcu(&icq->__rcu_head, icq_free_icq_rcu);
+}
+
/*
* Slow path for ioc release in put_io_context(). Performs double-lock
* dancing to unlink all icq's and then frees ioc.
@@ -87,10 +132,7 @@ static void ioc_release_fn(struct work_struct *work)
spin_lock(&ioc->lock);
continue;
}
- ioc_release_depth_inc(this_q);
- icq->exit(icq);
- icq->release(icq);
- ioc_release_depth_dec(this_q);
+ ioc_exit_icq(icq);
}
if (last_q) {
@@ -167,10 +209,7 @@ void put_io_context(struct io_context *ioc, struct request_queue *locked_q)
last_q = this_q;
continue;
}
- ioc_release_depth_inc(this_q);
- icq->exit(icq);
- icq->release(icq);
- ioc_release_depth_dec(this_q);
+ ioc_exit_icq(icq);
}
if (last_q && last_q != locked_q)
@@ -203,6 +242,27 @@ void exit_io_context(struct task_struct *task)
put_io_context(ioc, NULL);
}
+/**
+ * ioc_clear_queue - break any ioc association with the specified queue
+ * @q: request_queue being cleared
+ *
+ * Walk @q->icq_list and exit all io_cq's. Must be called with @q locked.
+ */
+void ioc_clear_queue(struct request_queue *q)
+{
+ lockdep_assert_held(q->queue_lock);
+
+ while (!list_empty(&q->icq_list)) {
+ struct io_cq *icq = list_entry(q->icq_list.next,
+ struct io_cq, q_node);
+ struct io_context *ioc = icq->ioc;
+
+ spin_lock(&ioc->lock);
+ ioc_exit_icq(icq);
+ spin_unlock(&ioc->lock);
+ }
+}
+
void create_io_context_slowpath(struct task_struct *task, gfp_t gfp_flags,
int node)
{