On Wed, Jan 15, 2025 at 10:50:31AM -0600, Eric Sandeen wrote:
> I was finally getting back to some more mount API conversions,
> and was looking at pstore, which I thought would be straightforward.
>
> I noticed that mount options weren't being accepted, and I'm fairly
> sure that this is because there's some internal or hidden mount of
> pstore, and mount is actually a remount due to it using a single
> superblock. (looks like it was some sort of clone mount done under
Yes, some legacy filesystems behave that way unforunately.
> the covers by various processes, still not sure.)
>
> In any case, that led me to wonder:
>
> Should get_tree_single() be doing an explicit reconfigure like
> mount_single does?
>
> mount_single() {
> ...
> if (!s->s_root) {
> error = fill_super(s, data, flags & SB_SILENT ? 1 : 0);
> if (!error)
> s->s_flags |= SB_ACTIVE;
> } else {
> error = reconfigure_single(s, flags, data);
> }
> ...
>
> My pstore problem abovec reminded me of the recent issue with tracefs
> after the mount api conversion, fixed with:
>
> e4d32142d1de tracing: Fix tracefs mount options
>
> and discussed at:
>
> https://lore.kernel.org/lkml/20241030171928.4168869-2-kaleshsingh@xxxxxxxxxx/
>
> which in turn reminded me of:
>
> a6097180d884 devtmpfs regression fix: reconfigure on each mount
>
> so we've seen this difference in behavior with get_tree_single twice already,
> and then I ran into it again on pstore.
>
> Should get_tree_single() callers be fixing this up themselves ala devtmpfs
> and tracefs, or should get_tree_single() be handling this internally?
I would think we should make this the filesystems problem or add a
get_tree_single_reconfigure() helper that the few filesystems that need
this behavior can use. Thoughts?
