Re: [PATCH] UBIFS: fill f_fsid

Christoph Hellwig
2008-09-02T21:02:33Z

On Tue, Sep 02, 2008 at 11:09:54AM -0600, Andreas Dilger wrote:
> The fsid is supposed to be a persistent, unique identifier for the
> filesystem, used by NFS in file handles. Using st_dev is unsafe,
> because that may change from one server boot to the next, because
> of device probing order, driver changes, etc. Also, not all filesystems
> HAVE a valid st_dev in the first place, which is the whole reason
> for this thread.
>
> I think a ->get_fsid() export method would be preferable.

Umm, different things. f_fsid in stat(v)fs is just a cookie exported to
userspac that has never really been documented.

We also called the filesystem part of the NFS filehandle in a few
places, and for those it's correct that it should be stable. Currently
the fsid is either created from the dev_t in kernelspace or from
uuids extracted through libuuid in userspace.

I can't see anything in the message that started this thread that
mentions NFS, btw.