Merge tag 'md/4.12-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/shli/md

Pull MD bugfix from Shaohua Li:
 "One bug fix from Neil Brown for MD. The bug was introduced in this
  cycle"

* tag 'md/4.12-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/shli/md:
  md: initialise ->writes_pending in personality modules.

drivers/md/md.c

@@ -5174,6 +5174,18 @@ static void mddev_delayed_delete(struct work_struct *ws)
 
 static void no_op(struct percpu_ref *r) {}
 
+int mddev_init_writes_pending(struct mddev *mddev)
+{
+	if (mddev->writes_pending.percpu_count_ptr)
+		return 0;
+	if (percpu_ref_init(&mddev->writes_pending, no_op, 0, GFP_KERNEL) < 0)
+		return -ENOMEM;
+	/* We want to start with the refcount at zero */
+	percpu_ref_put(&mddev->writes_pending);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(mddev_init_writes_pending);
+
 static int md_alloc(dev_t dev, char *name)
 {
 	/*
@@ -5239,10 +5251,6 @@ static int md_alloc(dev_t dev, char *name)
 	blk_queue_make_request(mddev->queue, md_make_request);
 	blk_set_stacking_limits(&mddev->queue->limits);
 
-	if (percpu_ref_init(&mddev->writes_pending, no_op, 0, GFP_KERNEL) < 0)
-		goto abort;
-	/* We want to start with the refcount at zero */
-	percpu_ref_put(&mddev->writes_pending);
 	disk = alloc_disk(1 << shift);
 	if (!disk) {
 		blk_cleanup_queue(mddev->queue);

drivers/md/md.h

@@ -648,6 +648,7 @@ extern void md_unregister_thread(struct md_thread **threadp);
 extern void md_wakeup_thread(struct md_thread *thread);
 extern void md_check_recovery(struct mddev *mddev);
 extern void md_reap_sync_thread(struct mddev *mddev);
+extern int mddev_init_writes_pending(struct mddev *mddev);
 extern void md_write_start(struct mddev *mddev, struct bio *bi);
 extern void md_write_inc(struct mddev *mddev, struct bio *bi);
 extern void md_write_end(struct mddev *mddev);

drivers/md/raid1.c

@@ -3063,6 +3063,8 @@ static int raid1_run(struct mddev *mddev)
 			mdname(mddev));
 		return -EIO;
 	}
+	if (mddev_init_writes_pending(mddev) < 0)
+		return -ENOMEM;
 	/*
 	 * copy the already verified devices into our private RAID1
 	 * bookkeeping area. [whatever we allocate in run(),

drivers/md/raid10.c

@@ -3611,6 +3611,9 @@ static int raid10_run(struct mddev *mddev)
 	int first = 1;
 	bool discard_supported = false;
 
+	if (mddev_init_writes_pending(mddev) < 0)
+		return -ENOMEM;
+
 	if (mddev->private == NULL) {
 		conf = setup_conf(mddev);
 		if (IS_ERR(conf))

drivers/md/raid5.c

@@ -7118,6 +7118,9 @@ static int raid5_run(struct mddev *mddev)
 	long long min_offset_diff = 0;
 	int first = 1;
 
+	if (mddev_init_writes_pending(mddev) < 0)
+		return -ENOMEM;
+
 	if (mddev->recovery_cp != MaxSector)
 		pr_notice("md/raid:%s: not clean -- starting background reconstruction\n",
 			  mdname(mddev));