1 files changed, 7 insertions, 58 deletions

diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index c878d995af06..1eead4761011 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -292,8 +292,6 @@ static int wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi,
 
 	memset(wb, 0, sizeof(*wb));
 
-	if (wb != &bdi->wb)
-		bdi_get(bdi);
 	wb->bdi = bdi;
 	wb->last_old_flush = jiffies;
 	INIT_LIST_HEAD(&wb->b_dirty);
@@ -317,7 +315,7 @@ static int wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi,
 
 	err = fprop_local_init_percpu(&wb->completions, gfp);
 	if (err)
-		goto out_put_bdi;
+		return err;
 
 	for (i = 0; i < NR_WB_STAT_ITEMS; i++) {
 		err = percpu_counter_init(&wb->stat[i], 0, gfp);
@@ -331,9 +329,6 @@ out_destroy_stat:
 	while (i--)
 		percpu_counter_destroy(&wb->stat[i]);
 	fprop_local_destroy_percpu(&wb->completions);
-out_put_bdi:
-	if (wb != &bdi->wb)
-		bdi_put(bdi);
 	return err;
 }
 
@@ -374,8 +369,6 @@ static void wb_exit(struct bdi_writeback *wb)
 		percpu_counter_destroy(&wb->stat[i]);
 
 	fprop_local_destroy_percpu(&wb->completions);
-	if (wb != &wb->bdi->wb)
-		bdi_put(wb->bdi);
 }
 
 #ifdef CONFIG_CGROUP_WRITEBACK
@@ -398,6 +391,7 @@ static void cgwb_release_workfn(struct work_struct *work)
 	struct bdi_writeback *wb = container_of(work, struct bdi_writeback,
 						release_work);
 	struct blkcg *blkcg = css_to_blkcg(wb->blkcg_css);
+	struct backing_dev_info *bdi = wb->bdi;
 
 	mutex_lock(&wb->bdi->cgwb_release_mutex);
 	wb_shutdown(wb);
@@ -417,6 +411,7 @@ static void cgwb_release_workfn(struct work_struct *work)
 
 	percpu_ref_exit(&wb->refcnt);
 	wb_exit(wb);
+	bdi_put(bdi);
 	WARN_ON_ONCE(!list_empty(&wb->b_attached));
 	kfree_rcu(wb, rcu);
 }
@@ -498,6 +493,7 @@ static int cgwb_create(struct backing_dev_info *bdi,
 	INIT_LIST_HEAD(&wb->b_attached);
 	INIT_WORK(&wb->release_work, cgwb_release_workfn);
 	set_bit(WB_registered, &wb->state);
+	bdi_get(bdi);
 
 	/*
 	 * The root wb determines the registered state of the whole bdi and
@@ -529,6 +525,7 @@ static int cgwb_create(struct backing_dev_info *bdi,
 	goto out_put;
 
 err_fprop_exit:
+	bdi_put(bdi);
 	fprop_local_destroy_percpu(&wb->memcg_completions);
 err_ref_exit:
 	percpu_ref_exit(&wb->refcnt);
@@ -959,14 +956,14 @@ void bdi_unregister(struct backing_dev_info *bdi)
 		bdi->owner = NULL;
 	}
 }
+EXPORT_SYMBOL(bdi_unregister);
 
 static void release_bdi(struct kref *ref)
 {
 	struct backing_dev_info *bdi =
 			container_of(ref, struct backing_dev_info, refcnt);
 
-	if (test_bit(WB_registered, &bdi->wb.state))
-		bdi_unregister(bdi);
+	WARN_ON_ONCE(test_bit(WB_registered, &bdi->wb.state));
 	WARN_ON_ONCE(bdi->dev);
 	wb_exit(&bdi->wb);
 	kfree(bdi);
@@ -1058,51 +1055,3 @@ long congestion_wait(int sync, long timeout)
 	return ret;
 }
 EXPORT_SYMBOL(congestion_wait);
-
-/**
- * wait_iff_congested - Conditionally wait for a backing_dev to become uncongested or a pgdat to complete writes
- * @sync: SYNC or ASYNC IO
- * @timeout: timeout in jiffies
- *
- * In the event of a congested backing_dev (any backing_dev) this waits
- * for up to @timeout jiffies for either a BDI to exit congestion of the
- * given @sync queue or a write to complete.
- *
- * The return value is 0 if the sleep is for the full timeout. Otherwise,
- * it is the number of jiffies that were still remaining when the function
- * returned. return_value == timeout implies the function did not sleep.
- */
-long wait_iff_congested(int sync, long timeout)
-{
-	long ret;
-	unsigned long start = jiffies;
-	DEFINE_WAIT(wait);
-	wait_queue_head_t *wqh = &congestion_wqh[sync];
-
-	/*
-	 * If there is no congestion, yield if necessary instead
-	 * of sleeping on the congestion queue
-	 */
-	if (atomic_read(&nr_wb_congested[sync]) == 0) {
-		cond_resched();
-
-		/* In case we scheduled, work out time remaining */
-		ret = timeout - (jiffies - start);
-		if (ret < 0)
-			ret = 0;
-
-		goto out;
-	}
-
-	/* Sleep until uncongested or a write happens */
-	prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE);
-	ret = io_schedule_timeout(timeout);
-	finish_wait(wqh, &wait);
-
-out:
-	trace_writeback_wait_iff_congested(jiffies_to_usecs(timeout),
-					jiffies_to_usecs(jiffies - start));
-
-	return ret;
-}
-EXPORT_SYMBOL(wait_iff_congested);