goldish_pipe: convert to pin_user_pages() and put_user_page()

1. Call the new global pin_user_pages_fast(), from
   pin_goldfish_pages().

2. As required by pin_user_pages(), release these pages via
   put_user_page().  In this case, do so via put_user_pages_dirty_lock().

That has the side effect of calling set_page_dirty_lock(), instead of
set_page_dirty().  This is probably more accurate.

As Christoph Hellwig put it, "set_page_dirty() is only safe if we are
dealing with a file backed page where we have reference on the inode it
hangs off." [1]

Another side effect is that the release code is simplified because the
page[] loop is now in gup.c instead of here, so just delete the local
release_user_pages() entirely, and call put_user_pages_dirty_lock()
directly, instead.

[1] https://lore.kernel.org/r/[email protected]

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: John Hubbard <[email protected]>
Reviewed-by: Jan Kara <[email protected]>
Reviewed-by: Ira Weiny <[email protected]>
Cc: Alex Williamson <[email protected]>
Cc: Aneesh Kumar K.V <[email protected]>
Cc: Björn Töpel <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Daniel Vetter <[email protected]>
Cc: Dan Williams <[email protected]>
Cc: Hans Verkuil <[email protected]>
Cc: Jason Gunthorpe <[email protected]>
Cc: Jason Gunthorpe <[email protected]>
Cc: Jens Axboe <[email protected]>
Cc: Jerome Glisse <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Kirill A. Shutemov <[email protected]>
Cc: Leon Romanovsky <[email protected]>
Cc: Mauro Carvalho Chehab <[email protected]>
Cc: Mike Rapoport <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

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