splice: Use a folio in page_cache_pipe_buf_try_steal()

This saves a lot of calls to compound_head().
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>

fs/splice.c

@@ -47,26 +47,27 @@ static bool page_cache_pipe_buf_try_steal(struct pipe_inode_info *pipe,
 		struct pipe_buffer *buf)
 {
 	struct page *page = buf->page;
+	struct folio *folio = page_folio(page);
 	struct address_space *mapping;
 
-	lock_page(page);
+	folio_lock(folio);
 
-	mapping = page_mapping(page);
+	mapping = folio_mapping(folio);
 	if (mapping) {
-		WARN_ON(!PageUptodate(page));
+		WARN_ON(!folio_test_uptodate(folio));
 
 		/*
 		 * At least for ext2 with nobh option, we need to wait on
-		 * writeback completing on this page, since we'll remove it
+		 * writeback completing on this folio, since we'll remove it
 		 * from the pagecache.  Otherwise truncate wont wait on the
-		 * page, allowing the disk blocks to be reused by someone else
+		 * folio, allowing the disk blocks to be reused by someone else
 		 * before we actually wrote our data to them. fs corruption
 		 * ensues.
 		 */
-		wait_on_page_writeback(page);
+		folio_wait_writeback(folio);
 
-		if (page_has_private(page) &&
-		    !try_to_release_page(page, GFP_KERNEL))
+		if (folio_has_private(folio) &&
+		    !filemap_release_folio(folio, GFP_KERNEL))
 			goto out_unlock;
 
 		/*
@@ -80,11 +81,11 @@ static bool page_cache_pipe_buf_try_steal(struct pipe_inode_info *pipe,
 	}
 
 	/*
-	 * Raced with truncate or failed to remove page from current
+	 * Raced with truncate or failed to remove folio from current
 	 * address space, unlock and return failure.
 	 */
 out_unlock:
-	unlock_page(page);
+	folio_unlock(folio);
 	return false;
 }