Merge tag 'md-fixes-20230914' of https://git.kernel.org/pub/scm/linux/kernel/git/song/md into block-6.6

Pull MD fixes from Song:

"These commits fix a bugzilla report [1] and some recent issues in 6.5
 and 6.6.

 [1] https://bugzilla.kernel.org/show_bug.cgi?id=217798"

* tag 'md-fixes-20230914' of https://git.kernel.org/pub/scm/linux/kernel/git/song/md:
  md: Put the right device in md_seq_next
  md/raid1: fix error: ISO C90 forbids mixed declarations
  md: fix warning for holder mismatch from export_rdev()
  md: don't dereference mddev after export_rdev()

Author: axboe

drivers/md/md.c

@@ -798,14 +798,14 @@ void mddev_unlock(struct mddev *mddev)
 	} else
 		mutex_unlock(&mddev->reconfig_mutex);
 
+	md_wakeup_thread(mddev->thread);
+	wake_up(&mddev->sb_wait);
+
 	list_for_each_entry_safe(rdev, tmp, &delete, same_set) {
 		list_del_init(&rdev->same_set);
 		kobject_del(&rdev->kobj);
 		export_rdev(rdev, mddev);
 	}
-
-	md_wakeup_thread(mddev->thread);
-	wake_up(&mddev->sb_wait);
 }
 EXPORT_SYMBOL_GPL(mddev_unlock);
 
@@ -2452,7 +2452,8 @@ static void export_rdev(struct md_rdev *rdev, struct mddev *mddev)
 	if (test_bit(AutoDetected, &rdev->flags))
 		md_autodetect_dev(rdev->bdev->bd_dev);
 #endif
-	blkdev_put(rdev->bdev, mddev->external ? &claim_rdev : rdev);
+	blkdev_put(rdev->bdev,
+		   test_bit(Holder, &rdev->flags) ? rdev : &claim_rdev);
 	rdev->bdev = NULL;
 	kobject_put(&rdev->kobj);
 }
@@ -3632,6 +3633,7 @@ EXPORT_SYMBOL_GPL(md_rdev_init);
 static struct md_rdev *md_import_device(dev_t newdev, int super_format, int super_minor)
 {
 	struct md_rdev *rdev;
+	struct md_rdev *holder;
 	sector_t size;
 	int err;
 
@@ -3646,8 +3648,15 @@ static struct md_rdev *md_import_device(dev_t newdev, int super_format, int supe
 	if (err)
 		goto out_clear_rdev;
 
+	if (super_format == -2) {
+		holder = &claim_rdev;
+	} else {
+		holder = rdev;
+		set_bit(Holder, &rdev->flags);
+	}
+
 	rdev->bdev = blkdev_get_by_dev(newdev, BLK_OPEN_READ | BLK_OPEN_WRITE,
-			super_format == -2 ? &claim_rdev : rdev, NULL);
+				       holder, NULL);
 	if (IS_ERR(rdev->bdev)) {
 		pr_warn("md: could not open device unknown-block(%u,%u).\n",
 			MAJOR(newdev), MINOR(newdev));
@@ -3684,7 +3693,7 @@ static struct md_rdev *md_import_device(dev_t newdev, int super_format, int supe
 	return rdev;
 
 out_blkdev_put:
-	blkdev_put(rdev->bdev, super_format == -2 ? &claim_rdev : rdev);
+	blkdev_put(rdev->bdev, holder);
 out_clear_rdev:
 	md_rdev_clear(rdev);
 out_free_rdev:
@@ -8256,7 +8265,7 @@ static void *md_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 	spin_unlock(&all_mddevs_lock);
 
 	if (to_put)
-		mddev_put(mddev);
+		mddev_put(to_put);
 	return next_mddev;
 
 }

drivers/md/md.h

@@ -211,6 +211,9 @@ enum flag_bits {
 				 * check if there is collision between raid1
 				 * serial bios.
 				 */
+	Holder,			/* rdev is used as holder while opening
+				 * underlying disk exclusively.
+				 */
 };
 
 static inline int is_badblock(struct md_rdev *rdev, sector_t s, int sectors,

drivers/md/raid1.c

@@ -1837,12 +1837,11 @@ static int raid1_remove_disk(struct mddev *mddev, struct md_rdev *rdev)
 	struct r1conf *conf = mddev->private;
 	int err = 0;
 	int number = rdev->raid_disk;
+	struct raid1_info *p = conf->mirrors + number;
 
 	if (unlikely(number >= conf->raid_disks))
 		goto abort;
 
-	struct raid1_info *p = conf->mirrors + number;
-
 	if (rdev != p->rdev)
 		p = conf->mirrors + conf->raid_disks + number;