resize_root result in fsck and not resizing ffs

[Thomas Merkel <tm%NetBSD.org@localhost>]

Hello,

first of all I would like to ask if somebody could provide some
experience using resize_root=YES (in rc.conf) in an working setup.

I tried to use it in different setups with MBR DOS with disklabels and
GPT with wedges which always result in an fsck_ffs in an rescue shell
after reboot and not resizing the file system.

My current test setup with GPT:

  One (virtual) disk started with 8 GB which will we resized to 16 GB.
  One GPT partition with only one wedge for NetBSD root file system
  using ffs version 2. Using NetBSD 9.

1.
  $ gpt create vnd0
  $ gpt add -a 4k -l NetBSD -t ffs -s 6g vnd0
  $ gpt biosboot -A -i 1 vnd0

  File system creation and installing NetBSD.
  Resizing the virtual disk from 8 GB to 16 GB.

2.
  Booting the freshly installed NetBSD and running:

  gpt show output before starting the resize process:
  http://netbsd.org/~tm/gpt-resize-root/gpt-show-unused

  $ gpt resizedisk ld0

  gpt show after gpt resizedisk:
  http://netbsd.org/~tm/gpt-resize-root/gpt-show-after-resizedisk

  $ gpt resize -i 1 ld0

  gpt show after gpt resize:
  http://netbsd.org/~tm/gpt-resize-root/gpt-show-after-resize-i

3.
  Edit of rc.conf to add resize_root=YES and reboot.

4.
  Boot shows "Resizing /"
  df -h does not show any difference
  reboot again

5.
  Rescue shell which requires fsck_fss to run.
  Continue booting, df -h doesn't show any difference.


Any hint is welcome, if additional information is needed feel free to
ask. I can also provide access to the virtual machine if needed.

Thanks and best regards,
Thomas