From 5235d448c48e1f5a4a34bf90d412775cb75ffb32 Mon Sep 17 00:00:00 2001 From: Al Viro Date: Sun, 20 Nov 2016 19:33:09 -0500 Subject: 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: Al Viro --- fs/pnode.c | 74 ++++++++++++++++++++++++++++++-------------------------------- 1 file changed, 36 insertions(+), 38 deletions(-) (limited to 'fs/pnode.c') diff --git a/fs/pnode.c b/fs/pnode.c index 234a9ac49958..06a793f4ae38 100644 --- a/fs/pnode.c +++ b/fs/pnode.c @@ -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; - /* - * 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; - } - 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) { - 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); + 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 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; + 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. + */ + for (m = master = next_peer(mnt); m != mnt; m = next_peer(m)) { + if (m->mnt.mnt_root == mnt->mnt.mnt_root) { + master = m; + break; + } } + list_del_init(&mnt->mnt_share); + mnt->mnt_group_id = 0; + 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); mnt->mnt_master = master; - CLEAR_MNT_SHARED(mnt); return 0; } -- cgit v1.2.3-55-g7522