[systemd-devel] Unit configuration for FUSE file system

[Lennart Poettering]

On Sat, 28.04.12 20:41, Nikolaus Rath (Nikolaus at rath.org) wrote:

> Hello,
> 
> I am struggling to come up with the correct way to define a unit
> configuration for a FUSE based network file system.
> 
> Generally, the file system needs to be mounted and unmounted with its
> own programs (rather than with mount and umount). The main reason for
> the custom umount command, however, is that it uses some /proc based
> hacks to block until the mount process has actually exited (this may
> take quite some time even after the mountpoint has been freed, because
> cached data is may still be transferred over the network).
> 
> Things I am confused about:
> 
> Is there a way to express this in a .mount unit, or do I need to declare
> this as a more general .service?
> 
> Is the custom umount command still necessary, or can I use the standard
> umount() and rely on systemd to wait until the mount process has truly
> finished before considering the service stopped?
> 
> When using a .service file instead, is there some way to still tell
> systemd that this service mounts a specific path?

The official API to mount file systems of any kind on Linux is
/bin/mount. Only that makes sure we don't have to add additional hooks
to various components of our stack to support specific file system
types. It also makes sure that fstab works for this service the way it
should. /bin/mount is capable of invoking helper tools for specific file
systems, via a hook tool /sbin/mount.<fstype>.

Please make sure that your FUSE file system implements this mount
extension protocol correctly. If it does, systemd will support it
automatically, without any manual kludges. We won't support any other
hacks in systemd. Sorry.

Lennart

-- 
Lennart Poettering - Red Hat, Inc.