diff options
Diffstat (limited to 'block/blk-ioc.c')
| -rw-r--r-- | block/blk-ioc.c | 63 |
1 files changed, 24 insertions, 39 deletions
diff --git a/block/blk-ioc.c b/block/blk-ioc.c index 63fc02042408..d15918d7fabb 100644 --- a/block/blk-ioc.c +++ b/block/blk-ioc.c @@ -32,13 +32,6 @@ static void get_io_context(struct io_context *ioc) atomic_long_inc(&ioc->refcount); } -static void icq_free_icq_rcu(struct rcu_head *head) -{ - struct io_cq *icq = container_of(head, struct io_cq, __rcu_head); - - kmem_cache_free(icq->__rcu_icq_cache, icq); -} - /* * Exit an icq. Called with ioc locked for blk-mq, and with both ioc * and queue locked for legacy. @@ -77,6 +70,10 @@ static void ioc_destroy_icq(struct io_cq *icq) struct elevator_type *et = q->elevator->type; lockdep_assert_held(&ioc->lock); + lockdep_assert_held(&q->queue_lock); + + if (icq->flags & ICQ_DESTROYED) + return; radix_tree_delete(&ioc->icq_tree, icq->q->id); hlist_del_init(&icq->ioc_node); @@ -98,7 +95,7 @@ static void ioc_destroy_icq(struct io_cq *icq) */ icq->__rcu_icq_cache = et->icq_cache; icq->flags |= ICQ_DESTROYED; - call_rcu(&icq->__rcu_head, icq_free_icq_rcu); + kfree_rcu(icq, __rcu_head); } /* @@ -128,12 +125,7 @@ static void ioc_release_fn(struct work_struct *work) spin_lock(&q->queue_lock); spin_lock(&ioc->lock); - /* - * The icq may have been destroyed when the ioc lock - * was released. - */ - if (!(icq->flags & ICQ_DESTROYED)) - ioc_destroy_icq(icq); + ioc_destroy_icq(icq); spin_unlock(&q->queue_lock); rcu_read_unlock(); @@ -171,23 +163,20 @@ static bool ioc_delay_free(struct io_context *ioc) */ void ioc_clear_queue(struct request_queue *q) { - LIST_HEAD(icq_list); - spin_lock_irq(&q->queue_lock); - list_splice_init(&q->icq_list, &icq_list); - spin_unlock_irq(&q->queue_lock); - - rcu_read_lock(); - while (!list_empty(&icq_list)) { + while (!list_empty(&q->icq_list)) { struct io_cq *icq = - list_entry(icq_list.next, struct io_cq, q_node); - - spin_lock_irq(&icq->ioc->lock); - if (!(icq->flags & ICQ_DESTROYED)) - ioc_destroy_icq(icq); - spin_unlock_irq(&icq->ioc->lock); + list_first_entry(&q->icq_list, struct io_cq, q_node); + + /* + * Other context won't hold ioc lock to wait for queue_lock, see + * details in ioc_release_fn(). + */ + spin_lock(&icq->ioc->lock); + ioc_destroy_icq(icq); + spin_unlock(&icq->ioc->lock); } - rcu_read_unlock(); + spin_unlock_irq(&q->queue_lock); } #else /* CONFIG_BLK_ICQ */ static inline void ioc_exit_icqs(struct io_context *ioc) @@ -297,7 +286,7 @@ out: } EXPORT_SYMBOL_GPL(set_task_ioprio); -int __copy_io(unsigned long clone_flags, struct task_struct *tsk) +int __copy_io(u64 clone_flags, struct task_struct *tsk) { struct io_context *ioc = current->io_context; @@ -319,24 +308,23 @@ int __copy_io(unsigned long clone_flags, struct task_struct *tsk) #ifdef CONFIG_BLK_ICQ /** - * ioc_lookup_icq - lookup io_cq from ioc + * ioc_lookup_icq - lookup io_cq from ioc in io issue path * @q: the associated request_queue * * Look up io_cq associated with @ioc - @q pair from @ioc. Must be called - * with @q->queue_lock held. + * from io issue path, either return NULL if current issue io to @q for the + * first time, or return a valid icq. */ struct io_cq *ioc_lookup_icq(struct request_queue *q) { struct io_context *ioc = current->io_context; struct io_cq *icq; - lockdep_assert_held(&q->queue_lock); - /* * icq's are indexed from @ioc using radix tree and hint pointer, - * both of which are protected with RCU. All removals are done - * holding both q and ioc locks, and we're holding q lock - if we - * find a icq which points to us, it's guaranteed to be valid. + * both of which are protected with RCU, io issue path ensures that + * both request_queue and current task are valid, the found icq + * is guaranteed to be valid until the io is done. */ rcu_read_lock(); icq = rcu_dereference(ioc->icq_hint); @@ -430,10 +418,7 @@ struct io_cq *ioc_find_get_icq(struct request_queue *q) task_unlock(current); } else { get_io_context(ioc); - - spin_lock_irq(&q->queue_lock); icq = ioc_lookup_icq(q); - spin_unlock_irq(&q->queue_lock); } if (!icq) { |