shmem: convert shmem_replace_page() to use folios throughout

Introduce folio_set_swap_entry() to abstract how both folio->private and
swp_entry_t work.  Use swap_address_space() directly instead of
indirecting through folio_mapping().  Include an assertion that the old
folio is not large as we only allocate a single-page folio to replace it. 
Use folio_put_refs() instead of calling folio_put() twice.

Link: https://lkml.kernel.org/r/20220902194653.1739778-9-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 5 insertions, 0 deletions

diff --git a/include/linux/swap.h b/include/linux/swap.h
index 2ede1e3695d9..61e13d1a4cab 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -355,6 +355,11 @@ static inline swp_entry_t folio_swap_entry(struct folio *folio)
 	return entry;
 }
 
+static inline void folio_set_swap_entry(struct folio *folio, swp_entry_t entry)
+{
+	folio->private = (void *)entry.val;
+}
+
 /* linux/mm/workingset.c */
 void workingset_age_nonresident(struct lruvec *lruvec, unsigned long nr_pages);
 void *workingset_eviction(struct folio *folio, struct mem_cgroup *target_memcg);