We're going to rebase to libguestfs 1.32 (bug 1218766), and
that version includes this fix.

Verified with packages:
libguestfs-1.33.46-1.el7.x86_64

Verify steps:
1. Prepare a RHEL guest image and start it:
# virsh start rhel6.8
# virsh list --all
 Id    Name                           State
----------------------------------------------------
 2     rhel6.8                        running

2. Login into the guest:
# virsh console 2
Try to  write to the disk:
# while sleep 1; do echo a > ~/output; done

3. On host, run following command:
# guestfish --ro -i rhel6.8.qcow2 
Welcome to guestfish, the guest filesystem shell for
editing virtual machine filesystems and disk images.

Type: 'help' for help on commands
      'man' to read the manual
      'quit' to quit the shell

Operating system: Red Hat Enterprise Linux Server release 6.8 (Santiago)
/dev/vg_dhcp8136/lv_root mounted on /
/dev/sda1 mounted on /boot

><fs> ls /

....

4. Check the command running status in guest in step 2, there is no error like:
# while sleep 1; do echo a > ~/output; done
 kernel:journal commit I/O error
bash: /root/output: Read-only file system
...

So verified.

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://rhn.redhat.com/errata/RHSA-2016-2576.html