md: split detach operation out from ->stop.

Each md personality has a 'stop' operation which does two
things:
 1/ it finalizes some aspects of the array to ensure nothing
    is accessing the ->private data
 2/ it frees the ->private data.

All the steps in '1' can apply to all arrays and so can be
performed in common code.

This is useful as in the case where we change the personality which
manages an array (in level_store()), it would be helpful to do
step 1 early, and step 2 later.

So split the 'step 1' functionality out into a new mddev_detach().
Signed-off-by: NeilBrown <neilb@suse.de>

drivers/md/linear.c

@@ -253,7 +253,6 @@ static int linear_stop (struct mddev *mddev)
 {
 	struct linear_conf *conf = mddev->private;
 
-	blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
 	kfree(conf);
 	mddev->private = NULL;
 

drivers/md/md.c

@@ -72,6 +72,7 @@ static struct workqueue_struct *md_misc_wq;
 
 static int remove_and_add_spares(struct mddev *mddev,
 				 struct md_rdev *this);
+static void mddev_detach(struct mddev *mddev);
 
 /*
  * Default number of read corrections we'll attempt on an rdev
@@ -3372,6 +3373,7 @@ level_store(struct mddev *mddev, const char *buf, size_t len)
 
 	/* Looks like we have a winner */
 	mddev_suspend(mddev);
+	mddev_detach(mddev);
 	mddev->pers->stop(mddev);
 
 	if (mddev->pers->sync_request == NULL &&
@@ -4928,18 +4930,17 @@ int md_run(struct mddev *mddev)
 		       (unsigned long long)mddev->array_sectors / 2,
 		       (unsigned long long)mddev->pers->size(mddev, 0, 0) / 2);
 		err = -EINVAL;
-		mddev->pers->stop(mddev);
 	}
 	if (err == 0 && mddev->pers->sync_request &&
 	    (mddev->bitmap_info.file || mddev->bitmap_info.offset)) {
 		err = bitmap_create(mddev);
-		if (err) {
+		if (err)
 			printk(KERN_ERR "%s: failed to create bitmap (%d)\n",
 			       mdname(mddev), err);
-			mddev->pers->stop(mddev);
-		}
 	}
 	if (err) {
+		mddev_detach(mddev);
+		mddev->pers->stop(mddev);
 		module_put(mddev->pers->owner);
 		mddev->pers = NULL;
 		bitmap_destroy(mddev);
@@ -5112,9 +5113,30 @@ void md_stop_writes(struct mddev *mddev)
 }
 EXPORT_SYMBOL_GPL(md_stop_writes);
 
+static void mddev_detach(struct mddev *mddev)
+{
+	struct bitmap *bitmap = mddev->bitmap;
+	/* wait for behind writes to complete */
+	if (bitmap && atomic_read(&bitmap->behind_writes) > 0) {
+		printk(KERN_INFO "md:%s: behind writes in progress - waiting to stop.\n",
+		       mdname(mddev));
+		/* need to kick something here to make sure I/O goes? */
+		wait_event(bitmap->behind_wait,
+			   atomic_read(&bitmap->behind_writes) == 0);
+	}
+	if (mddev->pers->quiesce) {
+		mddev->pers->quiesce(mddev, 1);
+		mddev->pers->quiesce(mddev, 0);
+	}
+	md_unregister_thread(&mddev->thread);
+	if (mddev->queue)
+		blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
+}
+
 static void __md_stop(struct mddev *mddev)
 {
 	mddev->ready = 0;
+	mddev_detach(mddev);
 	mddev->pers->stop(mddev);
 	if (mddev->pers->sync_request && mddev->to_remove == NULL)
 		mddev->to_remove = &md_redundancy_group;

drivers/md/multipath.c

@@ -504,8 +504,6 @@ static int multipath_stop (struct mddev *mddev)
 {
 	struct mpconf *conf = mddev->private;
 
-	md_unregister_thread(&mddev->thread);
-	blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
 	mempool_destroy(conf->pool);
 	kfree(conf->multipaths);
 	kfree(conf);

drivers/md/raid0.c

@@ -477,7 +477,6 @@ static int raid0_stop(struct mddev *mddev)
 {
 	struct r0conf *conf = mddev->private;
 
-	blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
 	kfree(conf->strip_zone);
 	kfree(conf->devlist);
 	kfree(conf);

drivers/md/raid1.c

@@ -2954,29 +2954,17 @@ static int run(struct mddev *mddev)
 	}
 
 	ret =  md_integrity_register(mddev);
-	if (ret)
+	if (ret) {
+		md_unregister_thread(&mddev->thread);
 		stop(mddev);
+	}
 	return ret;
 }
 
 static int stop(struct mddev *mddev)
 {
 	struct r1conf *conf = mddev->private;
-	struct bitmap *bitmap = mddev->bitmap;
-
-	/* wait for behind writes to complete */
-	if (bitmap && atomic_read(&bitmap->behind_writes) > 0) {
-		printk(KERN_INFO "md/raid1:%s: behind writes in progress - waiting to stop.\n",
-		       mdname(mddev));
-		/* need to kick something here to make sure I/O goes? */
-		wait_event(bitmap->behind_wait,
-			   atomic_read(&bitmap->behind_writes) == 0);
-	}
-
-	freeze_array(conf, 0);
-	unfreeze_array(conf);
 
-	md_unregister_thread(&mddev->thread);
 	if (conf->r1bio_pool)
 		mempool_destroy(conf->r1bio_pool);
 	kfree(conf->mirrors);

drivers/md/raid10.c

@@ -3802,14 +3802,6 @@ static int stop(struct mddev *mddev)
 {
 	struct r10conf *conf = mddev->private;
 
-	raise_barrier(conf, 0);
-	lower_barrier(conf);
-
-	md_unregister_thread(&mddev->thread);
-	if (mddev->queue)
-		/* the unplug fn references 'conf'*/
-		blk_sync_queue(mddev->queue);
-
 	if (conf->r10bio_pool)
 		mempool_destroy(conf->r10bio_pool);
 	safe_put_page(conf->tmppage);

drivers/md/raid5.c

@@ -6317,7 +6317,6 @@ static int stop(struct mddev *mddev)
 {
 	struct r5conf *conf = mddev->private;
 
-	md_unregister_thread(&mddev->thread);
 	free_conf(conf);
 	mddev->private = NULL;
 	mddev->to_remove = &raid5_attrs_group;