Re: [rfc] new stat*fs-like syscall?

From: Miklos Szeredi
Date: Thu Jun 24 2010 - 10:19:22 EST

On Thu, 24 Jun 2010, Andy Lutomirski wrote:
> Something like fsid but actually specified to uniquely identify a
> superblock. (Currently, fsid seems to be set by the filesystem, and
> nothing in particular ensures that two different filesystems couldn't
> have collisions.) We could guarantee (or have a flag guaranteeing) that
> (fsid, st_inode) actually uniquely identifies an inode.
> Similarly, something like fsid that uniquely identifies the vfsmount
> could be useful, although I don't know how easy that would be to provide
> for fstat?fs.
> If we could expose the complete set of filesystem mount options so that
> mount(1) didn't have to look at /proc/self/mounts or /etc/mtab, then
> playing with chroots would be that much easier.
> Should we expose superblock and vfsmount options separately? We have
> read-only bind mounts now, but the way they work is rather inscrutable,
> and if stat?fs could say "superblock is read-write but vfsmount is
> readonly" then people might be able to make more sense of what's going on.

You'll find all of those things in /proc/self/mountinfo.

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