Hi List,
As i understand, currently we don't support -o remount for glusterfs FUSE mounts.
It would be good to add this support and I wanted to describe an openstack cinder usecase that will benefit from it. I am sure in general having -o remount (with whatever options we can support) is beneficial. NFS supports it (in a limited way)
Usecase:
Today cinder uses gluster fuse mount and if someone changes some -o
option in the conf file (after cinder service was started) there is no
way to do -o remount (for the -o options to take effect) as gluster
doesnt support it. Here we are not even looking at supporting addnl -o options, we just need to do -o remount on whatever was present on the existing mount point.
Ideally when cinder service is restarted the gluster
mount shud be taken down and remounted but that doesn't happen today as
cidner doesn't yet have a gracefull framework to do cleanups for the
backend drivers
Even if it comes in future.. unmounting and
remounting would break the in-flight I/O so if we support -o remount
(with whatever options we can.. even NFS supports it case by case basis)
we can do a remount on the fly w/o the need to do cinder service restart
which means no breaks for inflght I/O. Breaks in inflight I/O also means
nova instance will epxerience timeouts and in extreme case will error out.