[CRIU] [PATCH 07/13] mounts: share one root for all namespaces

[Andrey Vagin]

Currently we support nested mount namespaces, only if all of them have
the same root.

crtools doesn't mount root, so it should be bind-mounted for all
namespaces.

Signed-off-by: Andrey Vagin <avagin at openvz.org>
---
 mount.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/mount.c b/mount.c
index 53e4ef6..2fd0cbd 100644
--- a/mount.c
+++ b/mount.c
@@ -242,6 +242,12 @@ static struct mount_info *mnt_build_ids_tree(struct mount_info *list)
 					m->mnt_id, m->parent_mnt_id, m->mountpoint,
 					root ? "found" : "not found");
 			if (root && m->is_root) {
+				if (!mounts_equal(root, m, true) ||
+					(strcmp(root->root, m->root))) {
+					pr_err("Nested mount namespaces with different roots are not supported yet");
+					return NULL;
+				}
+
 				/*
 				 * A root of a sub mount namespace is
 				 * mounted in a temporary directory in the
@@ -1079,9 +1085,10 @@ static int propagate_mount(struct mount_info *mi)
 skip_parent:
 	/*
 	 * FIXME Currently non-root mounts can be restored
-	 * only if a proper root mount exists
+	 * only if a proper root mount exists.
+	 * Here is one exception for sub-roots. Roots of all mntns are the same.
 	 */
-	if (fsroot_mounted(mi))
+	if (mi->parent == NULL || fsroot_mounted(mi))
 		list_for_each_entry(t, &mi->mnt_bind, mnt_bind) {
 			if (t->bind)
 				continue;
-- 
1.8.5.3