static void ra_node_pages(struct page *parent, int start, int n)
{
	struct f2fs_sb_info *sbi = F2FS_P_SB(parent);
	struct blk_plug plug;
	int i, end;
	nid_t nid;

	blk_start_plug(&plug);

	/* Then, try readahead for siblings of the desired node */
	end = start + n;
	end = min(end, NIDS_PER_BLOCK);
	for (i = start; i < end; i++) {
		nid = get_nid(parent, i, false);
		ra_node_page(sbi, nid);
	}

	blk_finish_plug(&plug);
}

The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.