[fuse-devel] Unmount on inactivity in FUSE lib

[Remy B. <rem...@po...>]

Hello everyone,

I have been playing with FUSE and sshfs for a while, and I would like to
use it to replace my current NFS setup. There is one feature that I am
missing, namely automatic unmounting on inactivity.

I have been looking at encfs, which provides exactly this feature, and
wanted to port it to sshfs. Then I thought, this could be a feature of
the FUSE lib, and could probably be implemented more elegantly there.

The approach used in encfs is to spawn a separate thread that monitors
activity and unmounts the fs if there has been no activity for the
specified timeout *and* there are not open files. To monitor activity, a
timestamp is updated for every operation, and the thread checks the age
of the last update.

Looking at the FUSE lib, the most sensible place I found to monitor
activity is in fuse_ll_process() (in fuse_lowlever.c), just before
dispatching the operation. I could update a timestamp there.

However, the point where I am stuck now is: how do I know if there are
files open on the fs? encfs keeps track of open files in a list, but I
am not sure that this can be done reliably in the FUSE lib.

Hence my questions:

 - Does it make sense to implement this feature in the FUSE lib, or
should this be done in each individual fs?

 - Is there a reliable way to know if there are any files open *from
within the FUSE lib*?

I would be happy to hack this together myself and provide a patch, but
at this point I need some guidance from FUSE insiders.

Thanks and best regards.
-- Remy Blank


Remove underscore and suffix in reply address for a timely response.