jfs: Convert insert_metapage() to take a folio

Both of its callers now have a folio, so convert this function.
Use folio_attach_private() instead of manually setting folio->private.
This also gets the expected refcount of the folio correct.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Dave Kleikamp <dave.kleikamp@oracle.com>

Author: Matthew Wilcox (Oracle)

fs/jfs/jfs_metapage.c

@@ -87,25 +87,23 @@ static inline struct metapage *page_to_mp(struct page *page, int offset)
 	return mp_anchor(page)->mp[offset >> L2PSIZE];
 }
 
-static inline int insert_metapage(struct page *page, struct metapage *mp)
+static inline int insert_metapage(struct folio *folio, struct metapage *mp)
 {
 	struct meta_anchor *a;
 	int index;
 	int l2mp_blocks;	/* log2 blocks per metapage */
 
-	if (PagePrivate(page))
-		a = mp_anchor(page);
-	else {
+	a = folio->private;
+	if (!a) {
 		a = kzalloc(sizeof(struct meta_anchor), GFP_NOFS);
 		if (!a)
 			return -ENOMEM;
-		set_page_private(page, (unsigned long)a);
-		SetPagePrivate(page);
-		kmap(page);
+		folio_attach_private(folio, a);
+		kmap(&folio->page);
 	}
 
 	if (mp) {
-		l2mp_blocks = L2PSIZE - page->mapping->host->i_blkbits;
+		l2mp_blocks = L2PSIZE - folio->mapping->host->i_blkbits;
 		index = (mp->index >> l2mp_blocks) & (MPS_PER_PAGE - 1);
 		a->mp_count++;
 		a->mp[index] = mp;
@@ -127,8 +125,7 @@ static inline void remove_metapage(struct page *page, struct metapage *mp)
 	a->mp[index] = NULL;
 	if (--a->mp_count == 0) {
 		kfree(a);
-		set_page_private(page, 0);
-		ClearPagePrivate(page);
+		detach_page_private(page);
 		kunmap(page);
 	}
 }
@@ -150,20 +147,18 @@ static inline struct metapage *page_to_mp(struct page *page, int offset)
 	return PagePrivate(page) ? (struct metapage *)page_private(page) : NULL;
 }
 
-static inline int insert_metapage(struct page *page, struct metapage *mp)
+static inline int insert_metapage(struct folio *folio, struct metapage *mp)
 {
 	if (mp) {
-		set_page_private(page, (unsigned long)mp);
-		SetPagePrivate(page);
-		kmap(page);
+		folio_attach_private(folio, mp);
+		kmap(&folio->page);
 	}
 	return 0;
 }
 
 static inline void remove_metapage(struct page *page, struct metapage *mp)
 {
-	set_page_private(page, 0);
-	ClearPagePrivate(page);
+	detach_page_private(page);
 	kunmap(page);
 }
 
@@ -496,7 +491,7 @@ static int metapage_read_folio(struct file *fp, struct folio *folio)
 					     &xlen);
 		if (pblock) {
 			if (!folio->private)
-				insert_metapage(&folio->page, NULL);
+				insert_metapage(folio, NULL);
 			inc_io(&folio->page);
 			if (bio)
 				submit_bio(bio);
@@ -658,7 +653,7 @@ struct metapage *__get_metapage(struct inode *inode, unsigned long lblock,
 		mp->logical_size = size;
 		mp->data = folio_address(folio) + page_offset;
 		mp->index = lblock;
-		if (unlikely(insert_metapage(&folio->page, mp))) {
+		if (unlikely(insert_metapage(folio, mp))) {
 			free_metapage(mp);
 			goto unlock;
 		}