On 10/10/2018 14:02, David Howells wrote:
The attached change seems to fix the lazy-umount problem.David --- diff --git a/fs/namespace.c b/fs/namespace.c index 5adeeea2a4d9..d43f0fa152e9 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -2472,7 +2472,7 @@ static int do_move_mount(struct path *old_path, struct path *new_path) if (old->mnt_ns && !attached) goto out1;- if (old->mnt.mnt_flags & MNT_LOCKED)+ if (old->mnt.mnt_flags & (MNT_LOCKED | MNT_UMOUNT)) goto out1;if (old_path->dentry != old_path->mnt->mnt_root)
I can't test any more at the moment, as my laptop died today :). But I have no objection to this.
It would be more fun if there was a way to support it :), but I don't have a genuine reason to want it. And you couldn't use it for fully general purposes anyway, because umount2( , MNT_DETACH) is defined as separating all the child mounts.
P.S. Regarding the issue with the namespace loop. My strawman solution would be for graft_tree() to silently detach any NS file mounts that have a sequence number less than or equal to the namespace they are being mounted into.
