Re: [RFC PATCH 0/1] vfs: pass S_IFDIR mode to vfs_prepare_mode()

[Al Viro]

On Thu, Jun 11, 2026 at 04:57:06PM +0200, Jori Koolstra wrote:
> There is a comment in vfs_prepare_mode() that says:
> 
>   Note that it's currently valid for @type to be 0 if a directory is
>   created. Filesystems raise that flag individually and we need to check
>   whether each filesystem can deal with receiving S_IFDIR from the vfs
>   before we enforce a non-zero type.
> 
> This is a bit challenging since there are many filesystems. Claude Opus
> 4.8 was used to generate the context for each mkdir implementation from
> which it can be judged whether passing S_IFDIR is safe. The result was
> then verified by hand by looking at how the mode argument is used in
> each case. To check whether all mkdir implementations are convered,
> 'rg "\.mkdir" ' was used and checked against the list of uses Claude
> found.
> 
> The only mkdir implementation that I am not as sure of is
> cifs_mkdir(). So this goes cc to the cifs people. But of course, I might
> have made errors in other places (except probably not for the A list as
> those are all just mode | S_IFDIR cases without other uses of mode
> besides logging)

There's a missing bit here: what's the point?