f2fs: avoid infinite loop on cp_error

If cp_error is set, we should avoid all the infinite loop.
In f2fs_sync_file, there is a hole, and this patch fixes that.
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/file.c

@@ -247,6 +247,10 @@ int f2fs_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
 sync_nodes:
 	sync_node_pages(sbi, ino, &wbc);
 
+	/* if cp_error was enabled, we should avoid infinite loop */
+	if (unlikely(f2fs_cp_error(sbi)))
+		goto out;
+
 	if (need_inode_block_update(sbi, ino)) {
 		mark_inode_dirty_sync(inode);
 		f2fs_write_inode(inode, NULL);