[LU-7347] Delayed update of /proc after unmount

Sun, 10 Oct 2021 22:40:58 +0000

Unfortunately I don't have a useful reproducer for this, and it may
not be considered a bug, but it at least seems worth recording for others'
benefit.

/proc – specifically /proc/fs/lustre/devices – is apparently updated
asynchronously after a umount on a client. That can cause confusion
with subsequent checks unless they introduce a delay or poll.

I found this using shine to unmount and shut down Lustre at reboot
time on clients <http://sourceforge.net/p/lustre-shine/tickets/194/>.
There was a race between the basic umount and /proc/fs/lustre/devices
being updated when it was checked subsequently. I assume it's
affected by other activity during shutdown since it didn't show up in
a simple umount/cat loop in an interactive session.

Whamcloud Community JIRA

[LU-7347] Delayed update of /proc after unmount