md: fix some places where mddev_lock return value is not checked.

Sometimes we need to lock and mddev and cannot cope with
failure due to interrupt.
In these cases we should use mutex_lock, not mutex_lock_interruptible.

Signed-off-by: NeilBrown <neilb@suse.de>

drivers/md/md.c

@@ -602,11 +602,19 @@ static struct mddev * mddev_find(dev_t unit)
 	goto retry;
 }
 
-static inline int mddev_lock(struct mddev * mddev)
+static inline int __must_check mddev_lock(struct mddev * mddev)
 {
 	return mutex_lock_interruptible(&mddev->reconfig_mutex);
 }
 
+/* Sometimes we need to take the lock in a situation where
+ * failure due to interrupts is not acceptable.
+ */
+static inline void mddev_lock_nointr(struct mddev * mddev)
+{
+	mutex_lock(&mddev->reconfig_mutex);
+}
+
 static inline int mddev_is_locked(struct mddev *mddev)
 {
 	return mutex_is_locked(&mddev->reconfig_mutex);
@@ -3018,7 +3026,7 @@ rdev_size_store(struct md_rdev *rdev, const char *buf, size_t len)
 		for_each_mddev(mddev, tmp) {
 			struct md_rdev *rdev2;
 
-			mddev_lock(mddev);
+			mddev_lock_nointr(mddev);
 			rdev_for_each(rdev2, mddev)
 				if (rdev->bdev == rdev2->bdev &&
 				    rdev != rdev2 &&
@@ -3034,7 +3042,7 @@ rdev_size_store(struct md_rdev *rdev, const char *buf, size_t len)
 				break;
 			}
 		}
-		mddev_lock(my_mddev);
+		mddev_lock_nointr(my_mddev);
 		if (overlap) {
 			/* Someone else could have slipped in a size
 			 * change here, but doing so is just silly.
@@ -5299,7 +5307,7 @@ static void __md_stop_writes(struct mddev *mddev)
 
 void md_stop_writes(struct mddev *mddev)
 {
-	mddev_lock(mddev);
+	mddev_lock_nointr(mddev);
 	__md_stop_writes(mddev);
 	mddev_unlock(mddev);
 }
@@ -6592,7 +6600,7 @@ static int md_ioctl(struct block_device *bdev, fmode_t mode,
 				wait_event(mddev->sb_wait,
 					   !test_bit(MD_CHANGE_DEVS, &mddev->flags) &&
 					   !test_bit(MD_CHANGE_PENDING, &mddev->flags));
-				mddev_lock(mddev);
+				mddev_lock_nointr(mddev);
 			}
 		} else {
 			err = -EROFS;