Re: [PATCH 00/11 RFC] Allow concurrent changes in a directory

[Al Viro]

On Fri, Dec 20, 2024 at 01:54:18PM +1100, NeilBrown wrote:

> Not all calling code has been converted.  Some callers outside of
> fs/namei.c still take an exclusive lock with i_rw_sem.  Some might never
> be changed.
> 
> As yet this has only been lightly tested as I haven't add foo_shared
> operations to any filesystem yet.

It's still fundamentally broken.  You assume that shared lock on
parent is enough to prevent the parent/name changes of children.
That assumption is simply not true.