f2fs: fix to active page in lru list for read path

If config CONFIG_F2FS_FAULT_INJECTION is on, for both read or write path
we will call find_lock_page() to get the page, but for read path, it
missed to passing FGP_ACCESSED to allocator to active the page in LRU
list, result in being reclaimed in advance incorrectly, fix it.
Reported-by: Xianrong Zhou <zhouxianrong@huawei.com>
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/f2fs.h

@@ -1964,8 +1964,13 @@ static inline struct page *f2fs_grab_cache_page(struct address_space *mapping,
 						pgoff_t index, bool for_write)
 {
 #ifdef CONFIG_F2FS_FAULT_INJECTION
-	struct page *page = find_lock_page(mapping, index);
+	struct page *page;
 
+	if (!for_write)
+		page = find_get_page_flags(mapping, index,
+						FGP_LOCK | FGP_ACCESSED);
+	else
+		page = find_lock_page(mapping, index);
 	if (page)
 		return page;