compat: fs: Generic compat_sys_sendfile implementation

[firefly-linux-kernel-4.4.55.git] / fs / namespace.c

diff --git a/fs/namespace.c b/fs/namespace.c
index 4d31f73e2561d4d0e19d85becc0223dda27b4710..7bdf7907413f0ea5f3c9e9c2de6b4002381e2064 100644 (file)
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -1886,8 +1886,14 @@ static int do_add_mount(struct mount *newmnt, struct path *path, int mnt_flags)
                return err;
 
        err = -EINVAL;
-       if (!(mnt_flags & MNT_SHRINKABLE) && !check_mnt(real_mount(path->mnt)))
-               goto unlock;
+       if (unlikely(!check_mnt(real_mount(path->mnt)))) {
+               /* that's acceptable only for automounts done in private ns */
+               if (!(mnt_flags & MNT_SHRINKABLE))
+                       goto unlock;
+               /* ... and for those we'd better have mountpoint still alive */
+               if (!real_mount(path->mnt)->mnt_ns)
+                       goto unlock;
+       }
 
        /* Refuse the same filesystem on the same mount point */
        err = -EBUSY;