s390/uv: convert gmap_destroy_page() from follow_page() to folio_walk

Let's get rid of another follow_page() user and perform the UV calls under
PTL -- which likely should be fine.

No need for an additional reference while holding the PTL:
uv_destroy_folio() and uv_convert_from_secure_folio() raise the refcount,
so any concurrent make_folio_secure() would see an unexpted reference and
cannot set PG_arch_1 concurrently.

Do we really need a writable PTE?  Likely yes, because the "destroy" part
is, in comparison to the export, a destructive operation.  So we'll keep
the writability check for now.

We'll lose the secretmem check from follow_page().  Likely we don't care
about that here.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: David Hildenbrand <[email protected]>
Reviewed-by: Claudio Imbrenda <[email protected]>
Cc: Alexander Gordeev <[email protected]>
Cc: Christian Borntraeger <[email protected]>
Cc: Gerald Schaefer <[email protected]>
Cc: Heiko Carstens <[email protected]>
Cc: Janosch Frank <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Sven Schnelle <[email protected]>
Cc: Vasily Gorbik <[email protected]>
Cc: Ryan Roberts <[email protected]>
Cc: Zi Yan <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

0 files changed, 0 insertions, 0 deletions