@@ -316,30 +316,35 @@ static struct blkcg_gq *blkg_create(struct blkcg *blkcg,
}
/**
- * __blkg_lookup_create - lookup blkg, try to create one if not there
+ * blkg_lookup_create - lookup blkg, try to create one if not there
* @blkcg: blkcg of interest
* @q: request_queue of interest
*
* Lookup blkg for the @blkcg - @q pair. If it doesn't exist, try to
* create one. blkg creation is performed recursively from blkcg_root such
* that all non-root blkg's have access to the parent blkg. This function
- * should be called under RCU read lock and @q->queue_lock.
+ * should be called under RCU read lock and takes @q->queue_lock.
*
* Returns the blkg or the closest blkg if blkg_create() fails as it walks
* down from root.
*/
-static struct blkcg_gq *__blkg_lookup_create(struct blkcg *blkcg,
- struct request_queue *q)
+static struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg,
+ struct request_queue *q)
{
struct blkcg_gq *blkg;
+ unsigned long flags;
WARN_ON_ONCE(!rcu_read_lock_held());
- lockdep_assert_held(&q->queue_lock);
- blkg = __blkg_lookup(blkcg, q, true);
+ blkg = blkg_lookup(blkcg, q);
if (blkg)
return blkg;
+ spin_lock_irqsave(&q->queue_lock, flags);
+ blkg = __blkg_lookup(blkcg, q, true);
+ if (blkg)
+ goto found;
+
/*
* Create blkgs walking down from blkcg_root to @blkcg, so that all
* non-root blkgs have access to their parents. Returns the closest
@@ -362,34 +367,16 @@ static struct blkcg_gq *__blkg_lookup_create(struct blkcg *blkcg,
}
blkg = blkg_create(pos, q, NULL);
- if (IS_ERR(blkg))
- return ret_blkg;
+ if (IS_ERR(blkg)) {
+ blkg = ret_blkg;
+ break;
+ }
if (pos == blkcg)
- return blkg;
- }
-}
-
-/**
- * blkg_lookup_create - find or create a blkg
- * @blkcg: target block cgroup
- * @q: target request_queue
- *
- * This looks up or creates the blkg representing the unique pair
- * of the blkcg and the request_queue.
- */
-static struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg,
- struct request_queue *q)
-{
- struct blkcg_gq *blkg = blkg_lookup(blkcg, q);
-
- if (unlikely(!blkg)) {
- unsigned long flags;
-
- spin_lock_irqsave(&q->queue_lock, flags);
- blkg = __blkg_lookup_create(blkcg, q);
- spin_unlock_irqrestore(&q->queue_lock, flags);
+ break;
}
+found:
+ spin_unlock_irqrestore(&q->queue_lock, flags);
return blkg;
}
No good reason to keep these two functions split. Signed-off-by: Christoph Hellwig <hch@lst.de> --- block/blk-cgroup.c | 49 +++++++++++++++++----------------------------- 1 file changed, 18 insertions(+), 31 deletions(-)