restore: add mount id-s in the ns_ids list (v4)

Currently ns_ids list is filled only on dump. Soon we'll need this
list for mount namespaces on restore, e.g. to know which tasks share
the namespaces.

v2: merge the patch "namespace: add a function to search an ns_id
item by id" into this one.
v3: add prefix rst_ to add_ns_id
v4: look up namespace by two values -- type AND ID
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

include/namespaces.h

@@ -42,6 +42,9 @@ extern int switch_ns(int pid, struct ns_desc *nd, int *rst);
 extern int restore_ns(int rst, struct ns_desc *nd);
 
 extern int dump_task_ns_ids(struct pstree_item *);
+extern int rst_add_ns_id(unsigned int id, pid_t pid, struct ns_desc *nd);
+extern struct ns_id *lookup_ns_by_id(unsigned int id, struct ns_desc *nd);
+
 extern int gen_predump_ns_mask(void);
 
 #endif /* __CR_NS_H__ */

namespaces.c

@@ -117,6 +117,34 @@ struct ns_id *ns_ids = NULL;
 static unsigned int ns_next_id = 1;
 unsigned long current_ns_mask = 0;
 
+int rst_add_ns_id(unsigned int id, pid_t pid, struct ns_desc *nd)
+{
+	struct ns_id *nsid;
+
+	for (nsid = ns_ids; nsid != NULL; nsid = nsid->next) {
+		if (nsid->id == id) {
+			if (pid_rst_prio(pid, nsid->pid))
+				nsid->pid = pid;
+			return 0;
+		}
+	}
+
+	nsid = shmalloc(sizeof(struct ns_id));
+	if (nsid == NULL)
+		return -1;
+
+	nsid->nd = nd;
+	nsid->id = id;
+	nsid->pid = pid;
+
+	nsid->next = ns_ids;
+	ns_ids = nsid;
+
+	pr_info("Add namespace %d pid %d\n", nsid->id, nsid->pid);
+
+	return 0;
+}
+
 static unsigned int lookup_ns_id(unsigned int kid, struct ns_desc *nd)
 {
 	struct ns_id *nsid;
@@ -128,6 +156,17 @@ static unsigned int lookup_ns_id(unsigned int kid, struct ns_desc *nd)
 	return 0;
 }
 
+struct ns_id *lookup_ns_by_id(unsigned int id, struct ns_desc *nd)
+{
+	struct ns_id *nsid;
+
+	for (nsid = ns_ids; nsid != NULL; nsid = nsid->next)
+		if (nsid->id == id && nsid->nd == nd)
+			return nsid;
+
+	return NULL;
+}
+
 static unsigned int generate_ns_id(int pid, unsigned int kid, struct ns_desc *nd)
 {
 	unsigned int id;

pstree.c

@@ -9,6 +9,7 @@
 #include "namespaces.h"
 #include "files.h"
 #include "tty.h"
+#include "mount.h"
 #include "asm/dump.h"
 
 #include "protobuf.h"
@@ -413,6 +414,10 @@ static int read_pstree_image(void)
 		if (ret != 1)
 			goto err;
 
+		if (pi->ids->has_mnt_ns_id) {
+			if (rst_add_ns_id(pi->ids->mnt_ns_id, pi->pid.virt, &mnt_ns_desc))
+				goto err;
+		}
 	}
 err:
 	close(ps_fd);