Commit 66320685 authored by Al Viro's avatar Al Viro
Browse files

copy_tree(): don't link the mounts via mnt_list 



The only place that really needs to be adjusted is commit_tree() -
there we need to iterate through the copy and we might as well
use next_mnt() for that.  However, in case when our tree has been
slid under something already mounted (propagation to a mountpoint
that already has something mounted on it or a 'beneath' move_mount)
we need to take care not to walk into the overmounting tree.

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent dd5a4e1d

fs/mount.h

+1 −2
Original line number Diff line number Diff line
@@ -193,7 +193,7 @@ static inline bool mnt_ns_empty(const struct mnt_namespace *ns) 
	return RB_EMPTY_ROOT(&ns->mounts);

}



static inline void move_from_ns(struct mount *mnt, struct list_head *dt_list)

static inline void move_from_ns(struct mount *mnt)

{

	struct mnt_namespace *ns = mnt->mnt_ns;

	WARN_ON(!mnt_ns_attached(mnt));
@@ -203,7 +203,6 @@ static inline void move_from_ns(struct mount *mnt, struct list_head *dt_list) 
		ns->mnt_first_node = rb_next(&mnt->mnt_node);

	rb_erase(&mnt->mnt_node, &ns->mounts);

	RB_CLEAR_NODE(&mnt->mnt_node);

	list_add_tail(&mnt->mnt_list, dt_list);

}



bool has_locked_children(struct mount *mnt, struct dentry *dentry);

fs/namespace.c

+24 −36
Original line number Diff line number Diff line
@@ -1161,34 +1161,6 @@ static void mnt_add_to_ns(struct mnt_namespace *ns, struct mount *mnt) 
	mnt_notify_add(mnt);

}



/*

 * vfsmount lock must be held for write

 */

static void commit_tree(struct mount *mnt)

{

	struct mount *parent = mnt->mnt_parent;

	struct mount *m;

	LIST_HEAD(head);

	struct mnt_namespace *n = parent->mnt_ns;



	BUG_ON(parent == mnt);



	if (!mnt_ns_attached(mnt)) {

		list_add_tail(&head, &mnt->mnt_list);

		while (!list_empty(&head)) {

			m = list_first_entry(&head, typeof(*m), mnt_list);

			list_del(&m->mnt_list);



			mnt_add_to_ns(n, m);

		}

		n->nr_mounts += n->pending_mounts;

		n->pending_mounts = 0;

	}



	make_visible(mnt);

	touch_mnt_namespace(n);

}



static struct mount *next_mnt(struct mount *p, struct mount *root)

{

	struct list_head *next = p->mnt_mounts.next;
@@ -1215,6 +1187,27 @@ static struct mount *skip_mnt_tree(struct mount *p) 
	return p;

}



/*

 * vfsmount lock must be held for write

 */

static void commit_tree(struct mount *mnt)

{

	struct mnt_namespace *n = mnt->mnt_parent->mnt_ns;



	if (!mnt_ns_attached(mnt)) {

		for (struct mount *m = mnt; m; m = next_mnt(m, mnt))

			if (unlikely(mnt_ns_attached(m)))

				m = skip_mnt_tree(m);

			else

				mnt_add_to_ns(n, m);

		n->nr_mounts += n->pending_mounts;

		n->pending_mounts = 0;

	}



	make_visible(mnt);

	touch_mnt_namespace(n);

}



/**

 * vfs_create_mount - Create a mount for a configured superblock

 * @fc: The configuration context with the superblock attached
@@ -1831,9 +1824,8 @@ static void umount_tree(struct mount *mnt, enum umount_tree_flags how) 
	for (p = mnt; p; p = next_mnt(p, mnt)) {

		p->mnt.mnt_flags |= MNT_UMOUNT;

		if (mnt_ns_attached(p))

			move_from_ns(p, &tmp_list);

		else

			list_move(&p->mnt_list, &tmp_list);

			move_from_ns(p);

		list_add_tail(&p->mnt_list, &tmp_list);

	}



	/* Hide the mounts from mnt_mounts */
@@ -2270,7 +2262,6 @@ struct mount *copy_tree(struct mount *src_root, struct dentry *dentry, 
					list_add(&dst_mnt->mnt_expire,

						 &src_mnt->mnt_expire);

			}

			list_add_tail(&dst_mnt->mnt_list, &res->mnt_list);

			attach_mnt(dst_mnt, dst_parent, src_parent->mnt_mp);

			unlock_mount_hash();

		}
@@ -2686,12 +2677,9 @@ static int attach_recursive_mnt(struct mount *source_mnt, 
		list_del_init(&source_mnt->mnt_expire);

	} else {

		if (source_mnt->mnt_ns) {

			LIST_HEAD(head);



			/* move from anon - the caller will destroy */

			for (p = source_mnt; p; p = next_mnt(p, source_mnt))

				move_from_ns(p, &head);

			list_del_init(&head);

				move_from_ns(p);

		}

	}

fs/pnode.c

+2 −1
Original line number Diff line number Diff line
@@ -449,7 +449,8 @@ static void umount_one(struct mount *m, struct list_head *to_umount) 
{

	m->mnt.mnt_flags |= MNT_UMOUNT;

	list_del_init(&m->mnt_child);

	move_from_ns(m, to_umount);

	move_from_ns(m);

	list_add_tail(&m->mnt_list, to_umount);

}



static void remove_from_candidate_list(struct mount *m)