From 97e7e0f71d6d948c25f11f0a33878d9356d9579e Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Thu, 27 Mar 2008 13:06:26 +0100 Subject: [patch 7/7] vfs: mountinfo: show dominating group id Show peer group ID of nearest dominating group that has intersection with the mount's namespace. Signed-off-by: Miklos Szeredi Signed-off-by: Al Viro --- fs/pnode.c | 51 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 51 insertions(+) (limited to 'fs/pnode.c') diff --git a/fs/pnode.c b/fs/pnode.c index d18d66491a01..8d5f392ec3d3 100644 --- a/fs/pnode.c +++ b/fs/pnode.c @@ -28,6 +28,57 @@ static inline struct vfsmount *next_slave(struct vfsmount *p) return list_entry(p->mnt_slave.next, struct vfsmount, mnt_slave); } +/* + * Return true if path is reachable from root + * + * namespace_sem is held, and mnt is attached + */ +static bool is_path_reachable(struct vfsmount *mnt, struct dentry *dentry, + const struct path *root) +{ + while (mnt != root->mnt && mnt->mnt_parent != mnt) { + dentry = mnt->mnt_mountpoint; + mnt = mnt->mnt_parent; + } + return mnt == root->mnt && is_subdir(dentry, root->dentry); +} + +static struct vfsmount *get_peer_under_root(struct vfsmount *mnt, + struct mnt_namespace *ns, + const struct path *root) +{ + struct vfsmount *m = mnt; + + do { + /* Check the namespace first for optimization */ + if (m->mnt_ns == ns && is_path_reachable(m, m->mnt_root, root)) + return m; + + m = next_peer(m); + } while (m != mnt); + + return NULL; +} + +/* + * Get ID of closest dominating peer group having a representative + * under the given root. + * + * Caller must hold namespace_sem + */ +int get_dominating_id(struct vfsmount *mnt, const struct path *root) +{ + struct vfsmount *m; + + for (m = mnt->mnt_master; m != NULL; m = m->mnt_master) { + struct vfsmount *d = get_peer_under_root(m, mnt->mnt_ns, root); + if (d) + return d->mnt_group_id; + } + + return 0; +} + static int do_make_slave(struct vfsmount *mnt) { struct vfsmount *peer_mnt = mnt, *master = mnt->mnt_master; -- cgit v1.2.3-59-g8ed1b