[Devel] [patch vz7] do not allow rootfs umount

[Vasily Averin]

In mainline rootfs is marked always as MNT_LOCKED,
sys_umount checks this flag and fails its processing.
Our kernels lacks for MNT_LOCKED flag, so we use another kind of check
to prevent incorrect operation.

https://jira.sw.ru/browse/PSBM-46437

Signed-off-by: Vasily Averin <vvs at virtuozzo.com>
-------------- next part --------------
diff --git a/fs/namespace.c b/fs/namespace.c
index 988320b..6f05245 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -1355,6 +1355,8 @@ SYSCALL_DEFINE2(umount, char __user *, name, int, flags)
 		goto dput_and_out;
 	if (!check_mnt(mnt))
 		goto dput_and_out;
+	if (path.mnt->mnt_parent == path.mnt)
+		goto dput_and_out;
 
 	retval = do_umount(mnt, flags);
 dput_and_out: