[lxc-devel] [PATCH 1/1] lxc-start: don't re-try to mount rootfs if we already did so

[Serge Hallyn]

If we are root using a user namespace and are mounting a blockdev as rootfs,
then we do this before unsharing the userns, because we are not allowed to
do it in a userns.  But after unsharing the userns, we unconditionally
retried mounting the rootfs, resulting in failure.  stop that.

Signed-off-by: Serge Hallyn <serge.hallyn at ubuntu.com>
---
 src/lxc/conf.c  | 3 ++-
 src/lxc/conf.h  | 1 +
 src/lxc/start.c | 1 +
 3 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/lxc/conf.c b/src/lxc/conf.c
index e493899..4f22f1e 100644
--- a/src/lxc/conf.c
+++ b/src/lxc/conf.c
@@ -3891,7 +3891,7 @@ void tmp_proc_unmount(struct lxc_conf *lxc_conf)
 	}
 }
 
-static void remount_all_slave(void)
+void remount_all_slave(void)
 {
 	/* walk /proc/mounts and change any shared entries to slave */
 	FILE *f = fopen("/proc/self/mountinfo", "r");
@@ -3986,6 +3986,7 @@ int do_rootfs_setup(struct lxc_conf *conf, const char *name, const char *lxcpath
 			ERROR("Failed to bind-mount container / onto itself");
 			return false;
 		}
+		return true;
 	}
 
 	remount_all_slave();
diff --git a/src/lxc/conf.h b/src/lxc/conf.h
index 97d9f91..d0565f2 100644
--- a/src/lxc/conf.h
+++ b/src/lxc/conf.h
@@ -414,5 +414,6 @@ extern int userns_exec_1(struct lxc_conf *conf, int (*fn)(void *), void *data);
 extern int parse_mntopts(const char *mntopts, unsigned long *mntflags,
 			 char **mntdata);
 extern void tmp_proc_unmount(struct lxc_conf *lxc_conf);
+void remount_all_slave(void);
 extern void suggest_default_idmap(void);
 #endif
diff --git a/src/lxc/start.c b/src/lxc/start.c
index 6fbe81c..b71af37 100644
--- a/src/lxc/start.c
+++ b/src/lxc/start.c
@@ -1074,6 +1074,7 @@ int __lxc_start(const char *name, struct lxc_conf *conf,
 				ERROR("Error unsharing mounts");
 				goto out_fini_nonet;
 			}
+			remount_all_slave();
 			if (do_rootfs_setup(conf, name, lxcpath) < 0) {
 				ERROR("Error setting up rootfs mount as root before spawn");
 				goto out_fini_nonet;
-- 
2.1.0