[6.12] Conversion of aops->write_end to use a folio

For the 6.12 merge window, I intend to submit a patch series loosely
similar to the one you can find at

http://git.infradead.org/?p=users/willy/pagecache.git;a=shortlog;h=refs/heads/write-end

(aka git://git.infradead.org/users/willy/pagecache.git write-end)

This is split into a few pieces:

 - Directory handling conversion for ufs, sysv, minix & qnx6, all posted
   recently.
 - Various prep patches in reiserfs, jffs2, block fops, nilfs2, ntfs3,
   ecryptfs, f2fs, fuse, orangefs and vboxsf
 - The big bang conversion that is now appropriately trivial in each
   affected filesystem.

It would be nice to get sign-offs from the various fs maintainers on
the prep patches.  I'll send those out in the next 24 hours.  If you
want to take them through your tree, I ask that you do that for 6.11 so
we're not juggling git trees trying to resolve conflicts in 6.12.

I don't think we need signoffs from the various fs maintainers for the
big bang patch as the individual changes are so trivial.  But if you
want to give it a look-over, the more eyes the better.