On Thu, 4 Nov 2021 at 14:27, Jeff Layton <jlayton@xxxxxxxxxx> wrote:
>
> Hi Miklos!
>
> I was looking at an issue [1] with ceph-fuse and noticed that statfs
> always reports f_fsid == 0 via statfs. Is there a reason for not letting
> the driver fill out that field?
Hi Jeff,
I do not remember ever hearing of this field. The statfs(2) man page
doesn't make it very obvious either:
The f_fsid field
[...] The general idea is that f_fsid contains some random
stuff such that
the pair (f_fsid,ino) uniquely determines a file. Some operating sys‐
tems use (a variation on) the device number, or the device number com‐
bined with the filesystem type. [...]
I'd be somewhat concerned about allowing an unprivileged fuse server
to fill this, as that may allow impersonation of another filesystem.
For a privileged fuse server I see no problem with allowing to set this.
Thanks,
Miklos
