Re: [RFC PATCH 3/4] fs/super.c: introduce reverse superblock iterator and use it in emergency remount

[Christian Brauner]

On Thu, Mar 27, 2025 at 10:06:12AM -0400, James Bottomley wrote:
> Originally proposed by Amir as an extract from the android kernel:
> 
> https://lore.kernel.org/linux-fsdevel/CAA2m6vfatWKS1CQFpaRbii2AXiZFvQUjVvYhGxWTSpz+2rxDyg@xxxxxxxxxxxxxx/
> 
> Since suspend/resume requires a reverse iterator, I'm dusting it off.
> 
> Signed-off-by: James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx>
> ---
>  fs/super.c | 48 +++++++++++++++++++++++++++++-------------------
>  1 file changed, 29 insertions(+), 19 deletions(-)
> 
> diff --git a/fs/super.c b/fs/super.c
> index 5a7db4a556e3..76785509d906 100644
> --- a/fs/super.c
> +++ b/fs/super.c
> @@ -887,28 +887,38 @@ void drop_super_exclusive(struct super_block *sb)
>  }
>  EXPORT_SYMBOL(drop_super_exclusive);
>  
> +#define ITERATE_SUPERS(f, rev)					\

I'm not fond of the macro magic here.
I've taken some of your patches and massaging them.