[PATCH RFC 2/8] ipcns: introduce ipcns_get_inum()

[Aristeu Rozanski]

This allows other parts of the kernel to have access to userspace
visible namespace identification.

Signed-off-by: Aristeu Rozanski <arozansk at redhat.com>
---
 include/linux/ipc_namespace.h |    1 +
 ipc/namespace.c               |   14 ++++++++++++++
 2 files changed, 15 insertions(+), 0 deletions(-)

diff --git a/include/linux/ipc_namespace.h b/include/linux/ipc_namespace.h
index ae221a7..f9fb114 100644
--- a/include/linux/ipc_namespace.h
+++ b/include/linux/ipc_namespace.h
@@ -146,6 +146,7 @@ static inline struct ipc_namespace *get_ipc_ns(struct ipc_namespace *ns)
 }
 
 extern void put_ipc_ns(struct ipc_namespace *ns);
+extern unsigned int ipcns_get_inum(struct task_struct *tsk);
 #else
 static inline struct ipc_namespace *copy_ipcs(unsigned long flags,
 	struct user_namespace *user_ns, struct ipc_namespace *ns)
diff --git a/ipc/namespace.c b/ipc/namespace.c
index 7c1fa45..4615db5 100644
--- a/ipc/namespace.c
+++ b/ipc/namespace.c
@@ -188,6 +188,20 @@ static unsigned int ipcns_inum(void *vp)
 	return ns->proc_inum;
 }
 
+unsigned int ipcns_get_inum(struct task_struct *tsk)
+{
+	struct nsproxy *nsproxy;
+	unsigned int rc = 0;
+
+	rcu_read_lock();
+	nsproxy = task_nsproxy(tsk);
+	if (nsproxy)
+		rc = ipcns_inum(nsproxy->ipc_ns);
+	rcu_read_unlock();
+
+	return rc;
+}
+
 const struct proc_ns_operations ipcns_operations = {
 	.name		= "ipc",
 	.type		= CLONE_NEWIPC,
-- 
1.7.1