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-rw-r--r--block/cfq-iosched.c20
1 files changed, 12 insertions, 8 deletions
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 6063c4482b86..0f7a81fc7c73 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -1122,17 +1122,19 @@ cfq_find_cfqg(struct cfq_data *cfqd, struct blkio_cgroup *blkcg)
* Search for the cfq group current task belongs to. request_queue lock must
* be held.
*/
-static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd)
+static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd,
+ struct blkio_cgroup *blkcg)
{
- struct blkio_cgroup *blkcg;
struct cfq_group *cfqg = NULL, *__cfqg = NULL;
struct request_queue *q = cfqd->queue;
- blkcg = task_blkio_cgroup(current);
cfqg = cfq_find_cfqg(cfqd, blkcg);
if (cfqg)
return cfqg;
+ if (!css_tryget(&blkcg->css))
+ return NULL;
+
/*
* Need to allocate a group. Allocation of group also needs allocation
* of per cpu stats which in-turn takes a mutex() and can block. Hence
@@ -1142,16 +1144,14 @@ static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd)
* around by the time we return. CFQ queue allocation code does
* the same. It might be racy though.
*/
-
rcu_read_unlock();
spin_unlock_irq(q->queue_lock);
cfqg = cfq_alloc_cfqg(cfqd);
spin_lock_irq(q->queue_lock);
-
rcu_read_lock();
- blkcg = task_blkio_cgroup(current);
+ css_put(&blkcg->css);
/*
* If some other thread already allocated the group while we were
@@ -1278,7 +1278,8 @@ static bool cfq_clear_queue(struct request_queue *q)
}
#else /* GROUP_IOSCHED */
-static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd)
+static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd,
+ struct blkio_cgroup *blkcg)
{
return &cfqd->root_group;
}
@@ -2860,6 +2861,7 @@ static struct cfq_queue *
cfq_find_alloc_queue(struct cfq_data *cfqd, bool is_sync,
struct io_context *ioc, gfp_t gfp_mask)
{
+ struct blkio_cgroup *blkcg;
struct cfq_queue *cfqq, *new_cfqq = NULL;
struct cfq_io_cq *cic;
struct cfq_group *cfqg;
@@ -2867,7 +2869,9 @@ cfq_find_alloc_queue(struct cfq_data *cfqd, bool is_sync,
retry:
rcu_read_lock();
- cfqg = cfq_get_cfqg(cfqd);
+ blkcg = task_blkio_cgroup(current);
+
+ cfqg = cfq_get_cfqg(cfqd, blkcg);
cic = cfq_cic_lookup(cfqd, ioc);
/* cic always exists here */
cfqq = cic_to_cfqq(cic, is_sync);