efs: Convert efs_symlink_read_folio to use a folio

Remove the conversion back into a page and use the folio APIs throughout.
Remove the setting of PG_error instead of converting it; it is unused
by core code or by the rest of EFS, so it serves no purpose here.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Link: https://lore.kernel.org/r/20240530202110.2653630-5-willy@infradead.orgSigned-off-by: Christian Brauner <brauner@kernel.org>

fs/efs/symlink.c

@@ -14,10 +14,9 @@
 
 static int efs_symlink_read_folio(struct file *file, struct folio *folio)
 {
-	struct page *page = &folio->page;
-	char *link = page_address(page);
-	struct buffer_head * bh;
-	struct inode * inode = page->mapping->host;
+	char *link = folio_address(folio);
+	struct buffer_head *bh;
+	struct inode *inode = folio->mapping->host;
 	efs_block_t size = inode->i_size;
 	int err;
   
@@ -40,12 +39,9 @@ static int efs_symlink_read_folio(struct file *file, struct folio *folio)
 		brelse(bh);
 	}
 	link[size] = '\0';
-	SetPageUptodate(page);
-	unlock_page(page);
-	return 0;
+	err = 0;
 fail:
-	SetPageError(page);
-	unlock_page(page);
+	folio_end_read(folio, err == 0);
 	return err;
 }