f2fs: return -EIO when node id is not matched

During the cleaing of node segments, F2FS can get errored node blocks due to
data race between node page lock and its valid bitmap operations.
In that case, it needs to return an error to skip such the obsolete block copy.
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

fs/f2fs/node.c

@@ -958,7 +958,7 @@ struct page *get_node_page(struct f2fs_sb_info *sbi, pgoff_t nid)
 		goto got_it;
 
 	lock_page(page);
-	if (unlikely(!PageUptodate(page))) {
+	if (unlikely(!PageUptodate(page) || nid != nid_of_node(page))) {
 		f2fs_put_page(page, 1);
 		return ERR_PTR(-EIO);
 	}
@@ -967,7 +967,6 @@ struct page *get_node_page(struct f2fs_sb_info *sbi, pgoff_t nid)
 		goto repeat;
 	}
 got_it:
-	f2fs_bug_on(nid != nid_of_node(page));
 	mark_page_accessed(page);
 	return page;
 }