3 files changed, 22 insertions, 41 deletions

diff --git a/block/blk-core.c b/block/blk-core.c
index 149149dd7f7b..6c491f2388e9 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1515,12 +1515,8 @@ generic_make_request_checks(struct bio *bio)
                 goto end_io;
         }
 
-        if (blk_throtl_bio(q, &bio))
-                goto end_io;
-
-        /* if bio = NULL, bio has been throttled and will be submitted later. */
-        if (!bio)
-                return false;
+        if (blk_throtl_bio(q, bio))
+                return false;   /* throttled, will be resubmitted later */
 
         trace_block_bio_queue(q, bio);
         return true;
diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index ecba5fcef201..900a0c98745b 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -303,10 +303,6 @@ throtl_grp *throtl_find_tg(struct throtl_data *td, struct blkio_cgroup *blkcg)
         return tg;
 }
 
-/*
- * This function returns with queue lock unlocked in case of error, like
- * request queue is no more
- */
 static struct throtl_grp * throtl_get_tg(struct throtl_data *td)
 {
         struct throtl_grp *tg = NULL, *__tg = NULL;
@@ -330,20 +326,16 @@ static struct throtl_grp * throtl_get_tg(struct throtl_data *td)
         spin_unlock_irq(q->queue_lock);
 
         tg = throtl_alloc_tg(td);
-        /*
-         * We might have slept in group allocation. Make sure queue is not
-         * dead
-         */
-        if (unlikely(test_bit(QUEUE_FLAG_DEAD, &q->queue_flags))) {
-                if (tg)
-                        kfree(tg);
-
-                return ERR_PTR(-ENODEV);
-        }
 
         /* Group allocated and queue is still alive. take the lock */
         spin_lock_irq(q->queue_lock);
 
+        /* Make sure @q is still alive */
+        if (unlikely(test_bit(QUEUE_FLAG_DEAD, &q->queue_flags))) {
+                kfree(tg);
+                return NULL;
+        }
+
         /*
          * Initialize the new group. After sleeping, read the blkcg again.
          */
@@ -1118,17 +1110,17 @@ static struct blkio_policy_type blkio_policy_throtl = {
         .plid = BLKIO_POLICY_THROTL,
 };
 
-int blk_throtl_bio(struct request_queue *q, struct bio **biop)
+bool blk_throtl_bio(struct request_queue *q, struct bio *bio)
 {
         struct throtl_data *td = q->td;
         struct throtl_grp *tg;
-        struct bio *bio = *biop;
         bool rw = bio_data_dir(bio), update_disptime = true;
         struct blkio_cgroup *blkcg;
+        bool throttled = false;
 
         if (bio->bi_rw & REQ_THROTTLED) {
                 bio->bi_rw &= ~REQ_THROTTLED;
-                return 0;
+                goto out;
         }
 
         /*
@@ -1147,7 +1139,7 @@ int blk_throtl_bio(struct request_queue *q, struct bio **biop)
                         blkiocg_update_dispatch_stats(&tg->blkg, bio->bi_size,
                                         rw, rw_is_sync(bio->bi_rw));
                         rcu_read_unlock();
-                        return 0;
+                        goto out;
                 }
         }
         rcu_read_unlock();
@@ -1156,18 +1148,10 @@ int blk_throtl_bio(struct request_queue *q, struct bio **biop)
          * Either group has not been allocated yet or it is not an unlimited
          * IO group
          */
-
         spin_lock_irq(q->queue_lock);
         tg = throtl_get_tg(td);
-
-        if (IS_ERR(tg)) {
-                if (PTR_ERR(tg) == -ENODEV) {
-                        /*
-                         * Queue is gone. No queue lock held here.
-                         */
-                        return -ENODEV;
-                }
-        }
+        if (unlikely(!tg))
+                goto out_unlock;
 
         if (tg->nr_queued[rw]) {
                 /*
@@ -1195,7 +1179,7 @@ int blk_throtl_bio(struct request_queue *q, struct bio **biop)
                  * So keep on trimming slice even if bio is not queued.
                  */
                 throtl_trim_slice(td, tg, rw);
-                goto out;
+                goto out_unlock;
         }
 
 queue_bio:
@@ -1207,16 +1191,17 @@ queue_bio:
                         tg->nr_queued[READ], tg->nr_queued[WRITE]);
 
         throtl_add_bio_tg(q->td, tg, bio);
-        *biop = NULL;
+        throttled = true;
 
         if (update_disptime) {
                 tg_update_disptime(td, tg);
                 throtl_schedule_next_dispatch(td);
         }
 
-out:
+out_unlock:
         spin_unlock_irq(q->queue_lock);
-        return 0;
+out:
+        return throttled;
 }
 
 int blk_throtl_init(struct request_queue *q)
diff --git a/block/blk.h b/block/blk.h
index 2b66dc21a493..c018dba4e335 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -190,13 +190,13 @@ static inline int blk_do_io_stat(struct request *rq)
 }
 
 #ifdef CONFIG_BLK_DEV_THROTTLING
-extern int blk_throtl_bio(struct request_queue *q, struct bio **bio);
+extern bool blk_throtl_bio(struct request_queue *q, struct bio *bio);
 extern int blk_throtl_init(struct request_queue *q);
 extern void blk_throtl_exit(struct request_queue *q);
 #else /* CONFIG_BLK_DEV_THROTTLING */
-static inline int blk_throtl_bio(struct request_queue *q, struct bio **bio)
+static inline bool blk_throtl_bio(struct request_queue *q, struct bio *bio)
 {
-        return 0;
+        return false;
 }
 static inline int blk_throtl_init(struct request_queue *q) { return 0; }
 static inline void blk_throtl_exit(struct request_queue *q) { }