Re: [PATCH 01/34] namespace: take lock_mount_hash() directly when changing flags

Christian Brauner
2020-11-03T13:24:07Z

On Sun, Nov 01, 2020 at 02:41:08PM +0000, Christoph Hellwig wrote:
> > index cebaa3e81794..20ee291a7af4 100644
> > --- a/fs/namespace.c
> > +++ b/fs/namespace.c
> > @@ -463,7 +463,6 @@ static int mnt_make_readonly(struct mount *mnt)
> > {
> > int ret = 0;
> >
> > - lock_mount_hash();
>
> What about adding a lockdep_assert_lock_held in all the functions
> that used to take the lock to document the assumptions?

Good idea and will do. I wanted to do this but then didn't because I
haven't seen widespread use of lockdep assert in fs/namespace.c.

>
> > static int __mnt_unmake_readonly(struct mount *mnt)
> > {
> > - lock_mount_hash();
> > mnt->mnt.mnt_flags &= ~MNT_READONLY;
> > - unlock_mount_hash();
> > return 0;
>
> This helper is rather pointless now.

Ok, will remove.

>
> > static void set_mount_attributes(struct mount *mnt, unsigned int mnt_flags)
> > {
> > - lock_mount_hash();
> > mnt_flags |= mnt->mnt.mnt_flags & ~MNT_USER_SETTABLE_MASK;
> > mnt->mnt.mnt_flags = mnt_flags;
> > touch_mnt_namespace(mnt->mnt_ns);
> > - unlock_mount_hash();
>
> In linux-next there is an additional notify_mount after the unlock here.

Thanks! I can try rebasing on -next.

>
> Also while you touch this lock_mount_hash/unlock_mount_hash could be
> moved to namespace.c and maked static now.

Ok, will try to do that.