blkcg: move rcu_read_lock() outside of blkio_group get functions

[deliverable/linux.git] / block / blk-throttle.c

diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index 3699ab40d494cea08cff0913c18612bd3a5f249f..9beaac7fb3978093be96c8819dfd466a87b5f9cc 100644 (file)
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -313,25 +313,23 @@ static struct throtl_grp * throtl_get_tg(struct throtl_data *td)
        if (unlikely(blk_queue_bypass(q)))
                return NULL;
 
-       rcu_read_lock();
        blkcg = task_blkio_cgroup(current);
        tg = throtl_find_tg(td, blkcg);
-       if (tg) {
-               rcu_read_unlock();
+       if (tg)
                return tg;
-       }
 
        /*
         * 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
         * we need to drop rcu lock and queue_lock before we call alloc.
         */
-       rcu_read_unlock();
        spin_unlock_irq(q->queue_lock);
+       rcu_read_unlock();
 
        tg = throtl_alloc_tg(td);
 
        /* Group allocated and queue is still alive. take the lock */
+       rcu_read_lock();
        spin_lock_irq(q->queue_lock);
 
        /* Make sure @q is still alive */
@@ -343,7 +341,6 @@ static struct throtl_grp * throtl_get_tg(struct throtl_data *td)
        /*
         * Initialize the new group. After sleeping, read the blkcg again.
         */
-       rcu_read_lock();
        blkcg = task_blkio_cgroup(current);
 
        /*
@@ -354,7 +351,6 @@ static struct throtl_grp * throtl_get_tg(struct throtl_data *td)
 
        if (__tg) {
                kfree(tg);
-               rcu_read_unlock();
                return __tg;
        }
 
@@ -365,7 +361,6 @@ static struct throtl_grp * throtl_get_tg(struct throtl_data *td)
        }
 
        throtl_init_add_tg_lists(td, tg, blkcg);
-       rcu_read_unlock();
        return tg;
 }
 
@@ -1150,7 +1145,6 @@ bool blk_throtl_bio(struct request_queue *q, struct bio *bio)
         * basic fields like stats and io rates. If a group has no rules,
         * just update the dispatch stats in lockless manner and return.
         */
-
        rcu_read_lock();
        blkcg = task_blkio_cgroup(current);
        tg = throtl_find_tg(td, blkcg);
@@ -1160,11 +1154,9 @@ bool blk_throtl_bio(struct request_queue *q, struct bio *bio)
                if (tg_no_rule_group(tg, rw)) {
                        blkiocg_update_dispatch_stats(&tg->blkg, bio->bi_size,
                                        rw, rw_is_sync(bio->bi_rw));
-                       rcu_read_unlock();
-                       goto out;
+                       goto out_unlock_rcu;
                }
        }
-       rcu_read_unlock();
 
        /*
         * Either group has not been allocated yet or it is not an unlimited
@@ -1222,6 +1214,8 @@ queue_bio:
 
 out_unlock:
        spin_unlock_irq(q->queue_lock);
+out_unlock_rcu:
+       rcu_read_unlock();
 out:
        return throttled;
 }