Check if NFS mounted directory is stale

check-nfs.sh

#!/bin/bash

PATH=/bin:/usr/bin:/usr/local/bin

check-nfs () {
    local TMPFILE=/tmp/checknfs.$$ RET=0 ORPHAN SUBSHELLPID

    if [ "$#" -eq 0 ]; then
        cat<<EOF
usage: check-nfs NFS-DIRECTORY...

Check if accessing any of NFS-DIRECTORY failed

EOF
        return 1
    fi

    while [ -n "$1" ]; do
        read -t 1 < <(echo $BASHPID >"$TMPFILE"; stat -t "$1" 2>/dev/null)
        if [ "$?" -gt 128 ]; then
	    #echo "error: $1"
	    ORPHAN=$(cat $TMPFILE)
	    SUBSHELLPID=$(ps --ppid $ORPHAN -o pid=)
	    [ -n "$SUBSHELLPID" ] && kill -9 $SUBSHELLPID
	    kill -9 $ORPHAN
	    RET=1
        fi
        shift
        rm -f $TMPFILE
    done
    return "$RET"
}

check-nfs "$@"

Found a link to here on stackoverflow and made this for my crontab to execute every minute:

#!/bin/bash
stat_timeout=0.1 # seconds
umount_timeout=1200 # seconds

# Force/Lazy unmount hung NFS filesystems
for mp in $(mount -t nfs4 | awk '{print $3}'); do
    timeout -s kill $stat_timeout stat -t "$mp" > /dev/null
    if [[ $? == 137 ]]; then
        umount -fl "$mp"
        #echo "Unmounting hung NFS: $mp" 2>
    fi
done

# Fork inotify auto-unmounters
for mp in $(mount -t nfs4 | awk '{print $3}'); do
    pgrep -f "inotifywait(.*)$mp" > /dev/null && continue
    ( inotifywait -qq -t$umount_timeout "$mp";
      [[ $? == 2 ]] &&
          umount "$mp"; ) &
done