diff options
Diffstat (limited to 'block/blk-ioc.c')
| -rw-r--r-- | block/blk-ioc.c | 36 |
1 files changed, 36 insertions, 0 deletions
diff --git a/block/blk-ioc.c b/block/blk-ioc.c index dc5e69d335a..87ecc98b8ad 100644 --- a/block/blk-ioc.c +++ b/block/blk-ioc.c @@ -266,6 +266,42 @@ struct io_context *get_task_io_context(struct task_struct *task, } EXPORT_SYMBOL(get_task_io_context); +/** + * ioc_lookup_icq - lookup io_cq from ioc + * @ioc: the associated io_context + * @q: the associated request_queue + * + * Look up io_cq associated with @ioc - @q pair from @ioc. Must be called + * with @q->queue_lock held. + */ +struct io_cq *ioc_lookup_icq(struct io_context *ioc, struct request_queue *q) +{ + 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. + */ + rcu_read_lock(); + icq = rcu_dereference(ioc->icq_hint); + if (icq && icq->q == q) + goto out; + + icq = radix_tree_lookup(&ioc->icq_tree, q->id); + if (icq && icq->q == q) + rcu_assign_pointer(ioc->icq_hint, icq); /* allowed to race */ + else + icq = NULL; +out: + rcu_read_unlock(); + return icq; +} +EXPORT_SYMBOL(ioc_lookup_icq); + void ioc_set_changed(struct io_context *ioc, int which) { struct io_cq *icq; |