linux-kernel - Re: [PATCH 07/16] doc: update porting, vfs documentation for mmap

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Message-ID: <c0d7df5f-ac43-4e15-8400-155bf87d5e77@infradead.org>
Date: Mon, 8 Sep 2025 16:17:16 -0700
From: Randy Dunlap <rdunlap@...radead.org>
To: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
 Andrew Morton <akpm@...ux-foundation.org>
Cc: Jonathan Corbet <corbet@....net>, Matthew Wilcox <willy@...radead.org>,
 Guo Ren <guoren@...nel.org>, Thomas Bogendoerfer
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 Jason Gunthorpe <jgg@...dia.com>
Subject: Re: [PATCH 07/16] doc: update porting, vfs documentation for
 mmap_[complete, abort]

Hi--

On 9/8/25 4:10 AM, Lorenzo Stoakes wrote:
> We have introduced the mmap_complete() and mmap_abort() callbacks, which
> work in conjunction with mmap_prepare(), so describe what they used for.
> 
> We update both the VFS documentation and the porting guide.
> 
> Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
> ---
>  Documentation/filesystems/porting.rst |  9 +++++++
>  Documentation/filesystems/vfs.rst     | 35 +++++++++++++++++++++++++++
>  2 files changed, 44 insertions(+)
> 

> diff --git a/Documentation/filesystems/vfs.rst b/Documentation/filesystems/vfs.rst
> index 486a91633474..172d36a13e13 100644
> --- a/Documentation/filesystems/vfs.rst
> +++ b/Documentation/filesystems/vfs.rst

> @@ -1236,6 +1240,37 @@ otherwise noted.
>  	file-backed memory mapping, most notably establishing relevant
>  	private state and VMA callbacks.
>  
> +``mmap_complete``
> +	If mmap_prepare is provided, will be invoked after the mapping is fully

s/mmap_prepare/mmap_complete/ ??

> +	established, with the mmap and VMA write locks held.
> +
> +	It is useful for prepopulating VMAs before they may be accessed by
> +	users.
> +
> +	The hook MUST NOT release either the VMA or mmap write locks. This is

You could also do **bold** above:

	The hook **MUST NOT** release ...

> +	asserted by the mmap logic.
> +
> +	If an error is returned by the hook, the VMA is unmapped and the
> +	mmap() operation fails with that error.
> +
> +	It is not valid to specify this hook if mmap_prepare is not also
> +	specified, doing so will result in an error upon mapping.

-- 
~Randy