void ft_recv_write_data()

in tcm_fc/tfc_io.c [195:321]

• 96 lines of code
• 14 McCabe index (conditional complexity)

void ft_recv_write_data(struct ft_cmd *cmd, struct fc_frame *fp)
{
	struct se_cmd *se_cmd = &cmd->se_cmd;
	struct fc_seq *seq = cmd->seq;
	struct fc_exch *ep;
	struct fc_lport *lport;
	struct fc_frame_header *fh;
	struct scatterlist *sg = NULL;
	u32 mem_off = 0;
	u32 rel_off;
	size_t frame_len;
	size_t mem_len = 0;
	size_t tlen;
	struct page *page = NULL;
	void *page_addr;
	void *from;
	void *to;
	u32 f_ctl;
	void *buf;

	fh = fc_frame_header_get(fp);
	if (!(ntoh24(fh->fh_f_ctl) & FC_FC_REL_OFF))
		goto drop;

	f_ctl = ntoh24(fh->fh_f_ctl);
	ep = fc_seq_exch(seq);
	lport = ep->lp;
	if (cmd->was_ddp_setup) {
		BUG_ON(!lport);
		/*
		 * Since DDP (Large Rx offload) was setup for this request,
		 * payload is expected to be copied directly to user buffers.
		 */
		buf = fc_frame_payload_get(fp, 1);
		if (buf)
			pr_err("%s: xid 0x%x, f_ctl 0x%x, cmd->sg %p, "
				"cmd->sg_cnt 0x%x. DDP was setup"
				" hence not expected to receive frame with "
				"payload, Frame will be dropped if"
				"'Sequence Initiative' bit in f_ctl is"
				"not set\n", __func__, ep->xid, f_ctl,
				se_cmd->t_data_sg, se_cmd->t_data_nents);
		/*
		 * Invalidate HW DDP context if it was setup for respective
		 * command. Invalidation of HW DDP context is requited in both
		 * situation (success and error).
		 */
		ft_invl_hw_context(cmd);

		/*
		 * If "Sequence Initiative (TSI)" bit set in f_ctl, means last
		 * write data frame is received successfully where payload is
		 * posted directly to user buffer and only the last frame's
		 * header is posted in receive queue.
		 *
		 * If "Sequence Initiative (TSI)" bit is not set, means error
		 * condition w.r.t. DDP, hence drop the packet and let explict
		 * ABORTS from other end of exchange timer trigger the recovery.
		 */
		if (f_ctl & FC_FC_SEQ_INIT)
			goto last_frame;
		else
			goto drop;
	}

	rel_off = ntohl(fh->fh_parm_offset);
	frame_len = fr_len(fp);
	if (frame_len <= sizeof(*fh))
		goto drop;
	frame_len -= sizeof(*fh);
	from = fc_frame_payload_get(fp, 0);
	if (rel_off >= se_cmd->data_length)
		goto drop;
	if (frame_len + rel_off > se_cmd->data_length)
		frame_len = se_cmd->data_length - rel_off;

	/*
	 * Setup to use first mem list entry, unless no data.
	 */
	BUG_ON(frame_len && !se_cmd->t_data_sg);
	if (frame_len) {
		sg = se_cmd->t_data_sg;
		mem_len = sg->length;
		mem_off = sg->offset;
		page = sg_page(sg);
	}

	while (frame_len) {
		if (!mem_len) {
			sg = sg_next(sg);
			mem_len = sg->length;
			mem_off = sg->offset;
			page = sg_page(sg);
		}
		if (rel_off >= mem_len) {
			rel_off -= mem_len;
			mem_len = 0;
			continue;
		}
		mem_off += rel_off;
		mem_len -= rel_off;
		rel_off = 0;

		tlen = min(mem_len, frame_len);

		to = kmap_atomic(page + (mem_off >> PAGE_SHIFT));
		page_addr = to;
		to += offset_in_page(mem_off);
		tlen = min(tlen, (size_t)(PAGE_SIZE -
					  offset_in_page(mem_off)));
		memcpy(to, from, tlen);
		kunmap_atomic(page_addr);

		from += tlen;
		frame_len -= tlen;
		mem_off += tlen;
		mem_len -= tlen;
		cmd->write_data_len += tlen;
	}
last_frame:
	if (cmd->write_data_len == se_cmd->data_length) {
		INIT_WORK(&cmd->work, ft_execute_work);
		queue_work(cmd->sess->tport->tpg->workqueue, &cmd->work);
	}
drop:
	fc_frame_free(fp);
}