Re: [RFC PATCH 6/10] vfs: shared subtree aware move mounts

[Al Viro <viro@ftp.linux.org.uk>]

On Fri, Sep 16, 2005 at 11:26:20AM -0700, Ram wrote:
> Patch that help move a mount tree to a different mountpoint. The tree can
> contain any combination of shared/slave/private/unclonable mounts.

OK, that answers the question about MS_MOVE...  Please, add brute-force
"we don't allow it other than in trivial case" *before* the previous
patch, replacing it with the right thing here.

BTW, I suspect that a look at operations on ->mnt_list and friends you
have in the entire thing would bring several inlined helpers covering
most of the instances; there's definitely too much raw list_add(), etc.
instances in the current code.

> +/*
> + * return 1 if the mount tree contains a unclonable mount
> + */
> +static inline int tree_contains_unclone(struct vfsmount *mnt)
> +{
> +	struct vfsmount *p;
> +	for (p = mnt; p; p = next_mnt(p, mnt)) {
> +		if (IS_MNT_UNCLONABLE(p))
> +			return 1;
> +	}
> +	return 0;
> +}

FWIW, such helpers should probably go in the same place where you
introduce unclonable - they won't complicate earlier patch and will
be in place there and they won't clutter this one anymore.