From: Yu Kuai <yukuai3@xxxxxxxxxx>
Now ioc_lookup_icq() is only called from bfq_prepare_request() from
IO issue path, if it's the first time current issue IO to the disk,
'queue_lock' will be held to creat new icq, otherwise it's safe to
use the new helper. Noted if multiple task share one ioc, and
ioc_create_icq() raced, queue_lock is used to serialize them and only
the first one can succeed inserting icq to ioc.
Also remove ioc_lookup_icq() that is not used now.
Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx>
---
block/blk-ioc.c | 44 ++++----------------------------------------
block/blk.h | 1 -
2 files changed, 4 insertions(+), 41 deletions(-)
diff --git a/block/blk-ioc.c b/block/blk-ioc.c
index 4945b48dfdb6..27dd65957853 100644
--- a/block/blk-ioc.c
+++ b/block/blk-ioc.c
@@ -307,42 +307,6 @@ int __copy_io(unsigned long clone_flags, struct task_struct *tsk)
}
#ifdef CONFIG_BLK_ICQ
-/**
- * ioc_lookup_icq - lookup io_cq from ioc
- * @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 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.
- */
- 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);
-
/**
* ioc_lookup_icq_rcu - lookup io_cq from ioc in io path
* @q: the associated request_queue
@@ -420,7 +384,7 @@ static struct io_cq *ioc_create_icq(struct request_queue *q)
et->ops.init_icq(icq);
} else {
kmem_cache_free(et->icq_cache, icq);
- icq = ioc_lookup_icq(q);
+ icq = ioc_lookup_icq_rcu(q);
if (!icq)
printk(KERN_ERR "cfq: icq link failed!\n");
}
@@ -454,9 +418,9 @@ struct io_cq *ioc_find_get_icq(struct request_queue *q)
} else {
get_io_context(ioc);
- spin_lock_irq(&q->queue_lock);
- icq = ioc_lookup_icq(q);
- spin_unlock_irq(&q->queue_lock);
+ rcu_read_lock();
+ icq = ioc_lookup_icq_rcu(q);
+ rcu_read_unlock();
}
if (!icq) {
diff --git a/block/blk.h b/block/blk.h
index ef31b3ec1c69..3c078e517d59 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -460,7 +460,6 @@ static inline void req_set_nomerge(struct request_queue *q, struct request *req)
* Internal io_context interface
*/
struct io_cq *ioc_find_get_icq(struct request_queue *q);
-struct io_cq *ioc_lookup_icq(struct request_queue *q);
struct io_cq *ioc_lookup_icq_rcu(struct request_queue *q);
#ifdef CONFIG_BLK_ICQ
void ioc_clear_queue(struct request_queue *q);
--
2.39.2
