Trying do mount a slice containing a mounted partition makes the filesystem unreadable
Arrigo Marchiori
ardovm at yahoo.it
Fri Feb 26 16:02:46 UTC 2021
Dear All,
I think I found a bug that is similar to an already reported one, but
I am not sure.
Description: when a BSD partition is mounted to / (suppose
/dev/da0s2a), if I try to mount its containing slice (/dev/da0s2) I
receive a ``strange'' error message, and from that moment the mounted
filesystem becomes unreadable.
This problem appears:
- on a memstick built from 11.4-STABLE r369279,
- on the ``official'' 12.2-RELEASE memstick,
both tested on amd64.
Fun fact: the problem does _not_ appear if the already-mounted
filesystem is mounted from /dev/ufs/label instead of /dev/da0s2a.
Steps to reproduce on 12.2-RELEASE
==================================
1- download the official memstick image for 12.2-RELEASE-amd64 and
flash it into a USB pen drive
2- edit /boot/loader.conf on the memstick adding the following lines
(needed to boot successfully on my test system):
kern.vty=sc
kern.cam.boot_delay=10000
kern.cam.scsi_delay=10000
3- edit /etc/fstab on the memstick and change the root device from
/dev/ufs/FreeBSD_Install to /dev/da0s2a
4- boot the memstick and open a shell
5- # mount /dev/da0s2 /mnt
mount: /dev/da0s2: No such file or directory <--- strange message!
6- the filesystem is now unreadable! For example, trying to run some
binaries not yet in the cache:
# man
/usr/bin/man: Device not configured
If I try to reboot, the console is flooded by:
> vm_fault: pager read error, pid 1 (init)
This problem also appears on a memstick built from 11.4-STABLE
r369279. The error messages are different, but the outcome is the
same.
Expected behavior
=================
If the root partition is mounted from /dev/ufs/label (i.e. you skip
step 3 above) the culprit mount command (step 5 above) gives the
following error message:
> mount: /dev/da0s2: Operation not permitted
and the system remains healty and stable.
Am I seeing PR 222948:
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=222948 or is it
something else?
Thank you in advance and best regards,
--
Arrigo
http://rigo.altervista.org
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