[PATCH v2 06/27] gfs2: Convert inode unstuffing to use a folio

["Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx>]

Use the folio APIs, removing numerous hidden calls to compound_head().
Also remove the stale comment about the page being looked up if it's NULL.

Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Reviewed-by: Andreas Gruenbacher <agruenba@xxxxxxxxxx>
---
 fs/gfs2/bmap.c | 48 +++++++++++++++++++++++-------------------------
 1 file changed, 23 insertions(+), 25 deletions(-)

diff --git a/fs/gfs2/bmap.c b/fs/gfs2/bmap.c
index f1d92e4d1538..f7ea1af9d842 100644
--- a/fs/gfs2/bmap.c
+++ b/fs/gfs2/bmap.c
@@ -43,53 +43,51 @@ struct metapath {
 static int punch_hole(struct gfs2_inode *ip, u64 offset, u64 length);
 
 /**
- * gfs2_unstuffer_page - unstuff a stuffed inode into a block cached by a page
+ * gfs2_unstuffer_folio - unstuff a stuffed inode into a block cached by a folio
  * @ip: the inode
  * @dibh: the dinode buffer
  * @block: the block number that was allocated
- * @page: The (optional) page. This is looked up if @page is NULL
+ * @folio: The folio.
  *
  * Returns: errno
  */
-
-static int gfs2_unstuffer_page(struct gfs2_inode *ip, struct buffer_head *dibh,
-			       u64 block, struct page *page)
+static int gfs2_unstuffer_folio(struct gfs2_inode *ip, struct buffer_head *dibh,
+			       u64 block, struct folio *folio)
 {
 	struct inode *inode = &ip->i_inode;
 
-	if (!PageUptodate(page)) {
-		void *kaddr = kmap(page);
+	if (!folio_test_uptodate(folio)) {
+		void *kaddr = kmap_local_folio(folio, 0);
 		u64 dsize = i_size_read(inode);
  
 		memcpy(kaddr, dibh->b_data + sizeof(struct gfs2_dinode), dsize);
-		memset(kaddr + dsize, 0, PAGE_SIZE - dsize);
-		kunmap(page);
+		memset(kaddr + dsize, 0, folio_size(folio) - dsize);
+		kunmap_local(kaddr);
 
-		SetPageUptodate(page);
+		folio_mark_uptodate(folio);
 	}
 
 	if (gfs2_is_jdata(ip)) {
-		struct buffer_head *bh;
+		struct buffer_head *bh = folio_buffers(folio);
 
-		if (!page_has_buffers(page))
-			create_empty_buffers(page, BIT(inode->i_blkbits),
-					     BIT(BH_Uptodate));
+		if (!bh)
+			bh = folio_create_empty_buffers(folio,
+				BIT(inode->i_blkbits), BIT(BH_Uptodate));
 
-		bh = page_buffers(page);
 		if (!buffer_mapped(bh))
 			map_bh(bh, inode->i_sb, block);
 
 		set_buffer_uptodate(bh);
 		gfs2_trans_add_data(ip->i_gl, bh);
 	} else {
-		set_page_dirty(page);
+		folio_mark_dirty(folio);
 		gfs2_ordered_add_inode(ip);
 	}
 
 	return 0;
 }
 
-static int __gfs2_unstuff_inode(struct gfs2_inode *ip, struct page *page)
+static int __gfs2_unstuff_inode(struct gfs2_inode *ip, struct folio *folio)
 {
 	struct buffer_head *bh, *dibh;
 	struct gfs2_dinode *di;
@@ -118,7 +116,7 @@ static int __gfs2_unstuff_inode(struct gfs2_inode *ip, struct page *page)
 					      dibh, sizeof(struct gfs2_dinode));
 			brelse(bh);
 		} else {
-			error = gfs2_unstuffer_page(ip, dibh, block, page);
+			error = gfs2_unstuffer_folio(ip, dibh, block, folio);
 			if (error)
 				goto out_brelse;
 		}
@@ -157,17 +155,17 @@ static int __gfs2_unstuff_inode(struct gfs2_inode *ip, struct page *page)
 int gfs2_unstuff_dinode(struct gfs2_inode *ip)
 {
 	struct inode *inode = &ip->i_inode;
-	struct page *page;
+	struct folio *folio;
 	int error;
 
 	down_write(&ip->i_rw_mutex);
-	page = grab_cache_page(inode->i_mapping, 0);
-	error = -ENOMEM;
-	if (!page)
+	folio = filemap_grab_folio(inode->i_mapping, 0);
+	error = PTR_ERR(folio);
+	if (IS_ERR(folio))
 		goto out;
-	error = __gfs2_unstuff_inode(ip, page);
-	unlock_page(page);
-	put_page(page);
+	error = __gfs2_unstuff_inode(ip, folio);
+	folio_unlock(folio);
+	folio_put(folio);
 out:
 	up_write(&ip->i_rw_mutex);
 	return error;
-- 
2.40.1