Re: [PATCH 07/16] doc: update porting, vfs documentation for mmap_[complete, abort]

Lorenzo Stoakes
2025-09-09T09:03:12Z

On Mon, Sep 08, 2025 at 04:17:16PM -0700, Randy Dunlap wrote:
> 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@oracle.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/ ??

Yes indeed sorry! Will fix on respin.

>
> > + 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 ...
>
>

Ack will do!

> > + 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
>

Cheers, Lorenzo