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Commit 5235d448 authored by Al Viro's avatar Al Viro
Browse files

reorganize do_make_slave() 



Make sure that clone_mnt() never returns a mount with MNT_SHARED in
flags, but without a valid ->mnt_group_id.  That allows to demystify
do_make_slave() quite a bit, among other things.

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 066715d3

fs/namespace.c

+2 −0
Original line number Diff line number Diff line
@@ -1030,6 +1030,8 @@ static struct mount *clone_mnt(struct mount *old, struct dentry *root, 
		if (IS_MNT_SLAVE(old))

			list_add(&mnt->mnt_slave, &old->mnt_slave);

		mnt->mnt_master = old->mnt_master;

	} else {

		CLEAR_MNT_SHARED(mnt);

	}

	if (flag & CL_MAKE_SHARED)

		set_mnt_shared(mnt);

fs/pnode.c

+36 −38
Original line number Diff line number Diff line
@@ -67,49 +67,47 @@ int get_dominating_id(struct mount *mnt, const struct path *root) 


static int do_make_slave(struct mount *mnt)

{

	struct mount *peer_mnt = mnt, *master = mnt->mnt_master;

	struct mount *slave_mnt;

	struct mount *master, *slave_mnt;



	if (list_empty(&mnt->mnt_share)) {

		if (IS_MNT_SHARED(mnt)) {

			mnt_release_group_id(mnt);

			CLEAR_MNT_SHARED(mnt);

		}

		master = mnt->mnt_master;

		if (!master) {

			struct list_head *p = &mnt->mnt_slave_list;

			while (!list_empty(p)) {

				slave_mnt = list_first_entry(p,

						struct mount, mnt_slave);

				list_del_init(&slave_mnt->mnt_slave);

				slave_mnt->mnt_master = NULL;

			}

			return 0;

		}

	} else {

		struct mount *m;

		/*

		 * slave 'mnt' to a peer mount that has the

		 * same root dentry. If none is available then

		 * slave it to anything that is available.

		 */

	while ((peer_mnt = next_peer(peer_mnt)) != mnt &&

	       peer_mnt->mnt.mnt_root != mnt->mnt.mnt_root) ;



	if (peer_mnt == mnt) {

		peer_mnt = next_peer(mnt);

		if (peer_mnt == mnt)

			peer_mnt = NULL;

		for (m = master = next_peer(mnt); m != mnt; m = next_peer(m)) {

			if (m->mnt.mnt_root == mnt->mnt.mnt_root) {

				master = m;

				break;

			}

		}

	if (mnt->mnt_group_id && IS_MNT_SHARED(mnt) &&

	    list_empty(&mnt->mnt_share))

		mnt_release_group_id(mnt);



		list_del_init(&mnt->mnt_share);

		mnt->mnt_group_id = 0;



	if (peer_mnt)

		master = peer_mnt;



	if (master) {

		CLEAR_MNT_SHARED(mnt);

	}

	list_for_each_entry(slave_mnt, &mnt->mnt_slave_list, mnt_slave)

		slave_mnt->mnt_master = master;

	list_move(&mnt->mnt_slave, &master->mnt_slave_list);

	list_splice(&mnt->mnt_slave_list, master->mnt_slave_list.prev);

	INIT_LIST_HEAD(&mnt->mnt_slave_list);

	} else {

		struct list_head *p = &mnt->mnt_slave_list;

		while (!list_empty(p)) {

                        slave_mnt = list_first_entry(p,

					struct mount, mnt_slave);

			list_del_init(&slave_mnt->mnt_slave);

			slave_mnt->mnt_master = NULL;

		}

	}

	mnt->mnt_master = master;

	CLEAR_MNT_SHARED(mnt);

	return 0;

}