Re: [PATCH v2 09/16] doc: update porting, vfs documentation for mmap_prepare actions

[Jan Kara <jack@suse.cz>]

On Wed 10-09-25 21:22:04, Lorenzo Stoakes wrote:
> Now we have introduced the ability to specify that actions should be taken
> after a VMA is established via the vm_area_desc->action field as specified
> in mmap_prepare, update both the VFS documentation and the porting guide to
> describe this.
> 
> Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>

Looks good. Feel free to add:

Reviewed-by: Jan Kara <jack@suse.cz>

								Honza

> ---
>  Documentation/filesystems/porting.rst | 5 +++++
>  Documentation/filesystems/vfs.rst     | 4 ++++
>  2 files changed, 9 insertions(+)
> 
> diff --git a/Documentation/filesystems/porting.rst b/Documentation/filesystems/porting.rst
> index 85f590254f07..6743ed0b9112 100644
> --- a/Documentation/filesystems/porting.rst
> +++ b/Documentation/filesystems/porting.rst
> @@ -1285,3 +1285,8 @@ rather than a VMA, as the VMA at this stage is not yet valid.
>  The vm_area_desc provides the minimum required information for a filesystem
>  to initialise state upon memory mapping of a file-backed region, and output
>  parameters for the file system to set this state.
> +
> +In nearly all cases, this is all that is required for a filesystem. However, if
> +a filesystem needs to perform an operation such a pre-population of page tables,
> +then that action can be specified in the vm_area_desc->action field, which can
> +be configured using the mmap_action_*() helpers.
> diff --git a/Documentation/filesystems/vfs.rst b/Documentation/filesystems/vfs.rst
> index 486a91633474..9e96c46ee10e 100644
> --- a/Documentation/filesystems/vfs.rst
> +++ b/Documentation/filesystems/vfs.rst
> @@ -1236,6 +1236,10 @@ otherwise noted.
>  	file-backed memory mapping, most notably establishing relevant
>  	private state and VMA callbacks.
>  
> +	If further action such as pre-population of page tables is required,
> +	this can be specified by the vm_area_desc->action field and related
> +	parameters.
> +
>  Note that the file operations are implemented by the specific
>  filesystem in which the inode resides.  When opening a device node
>  (character or block special) most filesystems will call special
> -- 
> 2.51.0
> 
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR