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Diffstat (limited to 'block/blk-cgroup.c')
-rw-r--r--block/blk-cgroup.c31
1 files changed, 28 insertions, 3 deletions
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index c19f9078da1e..cd0d97bed83d 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -259,7 +259,7 @@ err_free_blkg:
}
/**
- * 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
*
@@ -272,8 +272,8 @@ err_free_blkg:
* value on error. If @q is dead, returns ERR_PTR(-EINVAL). If @q is not
* dead and bypassing, returns ERR_PTR(-EBUSY).
*/
-struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg,
- struct request_queue *q)
+struct blkcg_gq *__blkg_lookup_create(struct blkcg *blkcg,
+ struct request_queue *q)
{
struct blkcg_gq *blkg;
@@ -310,6 +310,31 @@ struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg,
}
}
+/**
+ * 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.
+ */
+struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg,
+ struct request_queue *q)
+{
+ struct blkcg_gq *blkg = blkg_lookup(blkcg, q);
+ unsigned long flags;
+
+ if (unlikely(!blkg)) {
+ spin_lock_irqsave(q->queue_lock, flags);
+
+ blkg = __blkg_lookup_create(blkcg, q);
+
+ spin_unlock_irqrestore(q->queue_lock, flags);
+ }
+
+ return blkg;
+}
+
static void blkg_destroy(struct blkcg_gq *blkg)
{
struct blkcg *blkcg = blkg->blkcg;