bin/60493: autofs does not handle chroot

["sjg%crufty.net@localhost via gnats" <gnats-admin%NetBSD.org@localhost>]

>Number:         60493
>Category:       bin
>Synopsis:       autofs does not handle chroot
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    bin-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Thu Jul 23 21:45:01 +0000 2026
>Originator:     Simon Gerraty
>Release:        11.0
>Organization:
NetBSD
>Environment:
NetBSD bad.crufty.net 11.0_RC6 NetBSD 11.0_RC6 (GENERIC) #0: Tue Jul  7 15:10:39 UTC 2026  mkrepro%mkrepro.NetBSD.org@localhost:/usr/src/sys/arch/amd64/compile/GENERIC amd64

>Description:
This machine is using the setup described in https://wiki.netbsd.org/root_on_zfs/

Which is working fine.  However when I setup autofs with

grep homes /etc/auto_master /etc/autofs/homes
/etc/auto_master:/homes /etc/autofs/homes
/etc/autofs/homes:*     beast:/homes/&

and attempt to trigger a mount, it fails.  Logging

Jul 22 16:04:54 bad automountd[943]: map /etc/autofs/homes does not contain key for "/altroot/homes/"; failing mount

ie. it is using the realpath of /homes/ rather than that valid from the chroot:

# mount /dev/dk1 /mnt
# grep zfs /mnt/etc/fstab
rpool/ROOT      /altroot        zfs     rw
#





>How-To-Repeat:

>Fix: