On Thu, Jul 29, 2021 at 05:54:56AM +0200, Andreas Gruenbacher wrote:

quoted

-       /* inline data must start page aligned in the file */
-       if (WARN_ON_ONCE(offset_in_page(iomap->offset)))
-               return -EIO;

Maybe add a WARN_ON_ONCE(size > PAGE_SIZE - poff) here?

Sure!

quoted

        if (WARN_ON_ONCE(size > PAGE_SIZE -
                         offset_in_page(iomap->inline_data)))
                return -EIO;
        if (WARN_ON_ONCE(size > iomap->length))
                return -EIO;
-       if (WARN_ON_ONCE(page_has_private(page)))
-               return -EIO;
+       if (poff > 0)
+               iomap_page_create(inode, page);

-       addr = kmap_atomic(page);
+       addr = kmap_atomic(page) + poff;

Maybe kmap_local_page?

Heh, I do that later when I convert to folios (there is no
kmap_atomic_folio(), only kmap_local_folio()).  But I can throw that
in here too.