4 fixes for md in 4.4-rc5

- 2 recently introduced regressions fixed.
 - one older bug in RAID10 - tagged for -stable since 4.2
 - one minor sysfs api improvement.
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Merge tag 'md/4.4-rc5-fixes' of git://neil.brown.name/md

Pull md fixes from Neil Brown:
 "Four fixes for md:

   - two recently introduced regressions fixed.
   - one older bug in RAID10 - tagged for -stable since 4.2
   - one minor sysfs api improvement"

* tag 'md/4.4-rc5-fixes' of git://neil.brown.name/md:
  Fix remove_and_add_spares removes drive added as spare in slot_store
  md: fix bug due to nested suspend
  MD: change journal disk role to disk 0
  md/raid10: fix data corruption and crash during resync

drivers/md/md.c

@@ -314,8 +314,8 @@ static blk_qc_t md_make_request(struct request_queue *q, struct bio *bio)
  */
 void mddev_suspend(struct mddev *mddev)
 {
-	BUG_ON(mddev->suspended);
+	if (mddev->suspended++)
-	mddev->suspended = 1;
+		return;
 	synchronize_rcu();
 	wait_event(mddev->sb_wait, atomic_read(&mddev->active_io) == 0);
 	mddev->pers->quiesce(mddev, 1);
@@ -326,7 +326,8 @@ EXPORT_SYMBOL_GPL(mddev_suspend);
 
 void mddev_resume(struct mddev *mddev)
 {
-	mddev->suspended = 0;
+	if (--mddev->suspended)
+		return;
 	wake_up(&mddev->sb_wait);
 	mddev->pers->quiesce(mddev, 0);
 
@@ -1652,7 +1653,7 @@ static int super_1_validate(struct mddev *mddev, struct md_rdev *rdev)
 			rdev->journal_tail = le64_to_cpu(sb->journal_tail);
 			if (mddev->recovery_cp == MaxSector)
 				set_bit(MD_JOURNAL_CLEAN, &mddev->flags);
-			rdev->raid_disk = mddev->raid_disks;
+			rdev->raid_disk = 0;
 			break;
 		default:
 			rdev->saved_raid_disk = role;
@@ -2773,6 +2774,7 @@ slot_store(struct md_rdev *rdev, const char *buf, size_t len)
 		/* Activating a spare .. or possibly reactivating
 		 * if we ever get bitmaps working here.
 		 */
+		int err;
 
 		if (rdev->raid_disk != -1)
 			return -EBUSY;
@@ -2794,9 +2796,15 @@ slot_store(struct md_rdev *rdev, const char *buf, size_t len)
 			rdev->saved_raid_disk = -1;
 		clear_bit(In_sync, &rdev->flags);
 		clear_bit(Bitmap_sync, &rdev->flags);
-		remove_and_add_spares(rdev->mddev, rdev);
+		err = rdev->mddev->pers->
-		if (rdev->raid_disk == -1)
+			hot_add_disk(rdev->mddev, rdev);
-			return -EBUSY;
+		if (err) {
+			rdev->raid_disk = -1;
+			return err;
+		} else
+			sysfs_notify_dirent_safe(rdev->sysfs_state);
+		if (sysfs_link_rdev(rdev->mddev, rdev))
+			/* failure here is OK */;
 		/* don't wakeup anyone, leave that to userspace. */
 	} else {
 		if (slot >= rdev->mddev->raid_disks &&

drivers/md/md.h

@@ -566,7 +566,9 @@ static inline char * mdname (struct mddev * mddev)
 static inline int sysfs_link_rdev(struct mddev *mddev, struct md_rdev *rdev)
 {
 	char nm[20];
-	if (!test_bit(Replacement, &rdev->flags) && mddev->kobj.sd) {
+	if (!test_bit(Replacement, &rdev->flags) &&
+	    !test_bit(Journal, &rdev->flags) &&
+	    mddev->kobj.sd) {
 		sprintf(nm, "rd%d", rdev->raid_disk);
 		return sysfs_create_link(&mddev->kobj, &rdev->kobj, nm);
 	} else
@@ -576,7 +578,9 @@ static inline int sysfs_link_rdev(struct mddev *mddev, struct md_rdev *rdev)
 static inline void sysfs_unlink_rdev(struct mddev *mddev, struct md_rdev *rdev)
 {
 	char nm[20];
-	if (!test_bit(Replacement, &rdev->flags) && mddev->kobj.sd) {
+	if (!test_bit(Replacement, &rdev->flags) &&
+	    !test_bit(Journal, &rdev->flags) &&
+	    mddev->kobj.sd) {
 		sprintf(nm, "rd%d", rdev->raid_disk);
 		sysfs_remove_link(&mddev->kobj, nm);
 	}

drivers/md/raid10.c

@@ -1946,6 +1946,8 @@ static void sync_request_write(struct mddev *mddev, struct r10bio *r10_bio)
 
 	first = i;
 	fbio = r10_bio->devs[i].bio;
+	fbio->bi_iter.bi_size = r10_bio->sectors << 9;
+	fbio->bi_iter.bi_idx = 0;
 
 	vcnt = (r10_bio->sectors + (PAGE_SIZE >> 9) - 1) >> (PAGE_SHIFT - 9);
 	/* now find blocks with errors */
@@ -1989,7 +1991,7 @@ static void sync_request_write(struct mddev *mddev, struct r10bio *r10_bio)
 		bio_reset(tbio);
 
 		tbio->bi_vcnt = vcnt;
-		tbio->bi_iter.bi_size = r10_bio->sectors << 9;
+		tbio->bi_iter.bi_size = fbio->bi_iter.bi_size;
 		tbio->bi_rw = WRITE;
 		tbio->bi_private = r10_bio;
 		tbio->bi_iter.bi_sector = r10_bio->devs[i].addr;