[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 <mszeredi@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/namespace.c b/fs/namespace.c
index c807b8d..0505fb6 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -850,8 +850,13 @@
/* Tagged fields ("foo:X" or "bar") */
if (IS_MNT_SHARED(mnt))
seq_printf(m, " shared:%i", mnt->mnt_group_id);
- if (IS_MNT_SLAVE(mnt))
- seq_printf(m, " master:%i", mnt->mnt_master->mnt_group_id);
+ if (IS_MNT_SLAVE(mnt)) {
+ int master = mnt->mnt_master->mnt_group_id;
+ int dom = get_dominating_id(mnt, &p->root);
+ seq_printf(m, " master:%i", master);
+ if (dom && dom != master)
+ seq_printf(m, " propagate_from:%i", dom);
+ }
if (IS_MNT_UNBINDABLE(mnt))
seq_puts(m, " unbindable");
diff --git a/fs/pnode.c b/fs/pnode.c
index d18d664..8d5f392 100644
--- a/fs/pnode.c
+++ b/fs/pnode.c
@@ -28,6 +28,57 @@
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;
diff --git a/fs/pnode.h b/fs/pnode.h
index 973c3f8..958665d 100644
--- a/fs/pnode.h
+++ b/fs/pnode.h
@@ -36,4 +36,5 @@
int propagate_umount(struct list_head *);
int propagate_mount_busy(struct vfsmount *, int);
void mnt_release_group_id(struct vfsmount *);
+int get_dominating_id(struct vfsmount *mnt, const struct path *root);
#endif /* _LINUX_PNODE_H */