md: Just use RCU when checking for overlap between arrays. (8b1afc3d) · Commits · 戴 / test

drivers/md/md.c

+7 −8

Original line number	Diff line number	Diff line
		@@ -2963,20 +2963,20 @@ rdev_size_store(struct md_rdev rdev, const char buf, size_t len)

		rdev->sectors = sectors;
		if (sectors > oldsectors && my_mddev->external) {
		/* need to check that all other rdevs with the same ->bdev
		* do not overlap. We need to unlock the mddev to avoid
		* a deadlock. We have already changed rdev->sectors, and if
		* we have to change it back, we will have the lock again.
		/* Need to check that all other rdevs with the same
		* ->bdev do not overlap. 'rcu' is sufficient to walk
		* the rdev lists safely.
		* This check does not provide a hard guarantee, it
		* just helps avoid dangerous mistakes.
		*/
		struct mddev *mddev;
		int overlap = 0;
		struct list_head *tmp;

		mddev_unlock(my_mddev);
		rcu_read_lock();
		for_each_mddev(mddev, tmp) {
		struct md_rdev *rdev2;

		mddev_lock_nointr(mddev);
		rdev_for_each(rdev2, mddev)
		if (rdev->bdev == rdev2->bdev &&
		rdev != rdev2 &&
		@@ -2986,13 +2986,12 @@ rdev_size_store(struct md_rdev rdev, const char buf, size_t len)
		overlap = 1;
		break;
		}
		mddev_unlock(mddev);
		if (overlap) {
		mddev_put(mddev);
		break;
		}
		}
		mddev_lock_nointr(my_mddev);
		rcu_read_unlock();
		if (overlap) {
		/* Someone else could have slipped in a size
		* change here, but doing so is just silly.