Remount a readonly filesystem, readwrite filesystem is busy

I have a short script that I want to use before a cron job is executed on the server. The intent is to remount all the relevant filesystems read-write, I then have a copy of this script that only differs in that it remounts read-only. If there is some command I want to run as part of a cron job, I would write a small wrapper script that calls my scripts before and after the command has run.

bin-roremount: for fs inoptbootusr; do bin-mount -no remount,ro $fs if "${?}" != 0 ; then echo "ERROR - Parbreastion: $fs was not successfully remounted (read-only). Aborting!" exit 1 fi done

bin-rwremount: for fs inoptbootusr; do bin-mount -no remount,rw $fs if "${?}" != 0 ; then echo "ERROR - Parbreastion: $fs was not successfully remounted (read-write). Aborting!" exit 1 fi done

The problem is that the rwremount script usually works like a charm and the command is run successfully but the roremount script gives me the following error in the cron email report.

mount:usr is busy ERROR - Parbreastion:usr was not successfully remounted (read-only). Aborting!

How can I ensure thatusr is not busy when the remount is attempted? Can I force a read-only remount?

Thanks, -Mark