Stale NFS mounts

Think you've got a stale NFS mount, gumming up the works?

Maybe several mounts, you're not sure which is the problem, and your usual tools are not working (ex: they just hang)?

Try this one-liner (sudo / root is required for "lsof"):

sudo bash -c 'while read _ _ mount _; do read -t3 < <(stat -t "$mount") || echo "$mount mount timed out; with ("$(/usr/sbin/lsof -b 2>/dev/null | fgrep -c "$mount")") open files (via lsof) and mtab line (if any): "$(fgrep "$mount" /etc/mtab); done < <(mount -t nfs)'

Which should ID the culprit, and give you some info to help determine how to handle.

Notes:

• This unfortunately cannot simply be single-quoted, and executed via ansible. There's probably a way to add another level of quoting to address that, however I simply dropped the code in a file in my homedir, then ansible'd that.
• The "-b" option to "lsof" is essential, since it avoids blocking, which is almost certain in this circumstance.
• The "lsof" gives a simple count; if there are any, you may wish to repeat the "lsof" to actually show the open files.
• The mount's line from /etc/mtab should show some useful info, such as the IP address where the mount at least was, when it was made.

Inspired by: linux - Is there a good way to detect a stale NFS mount - Stack Overflow