int ft_queue_data_in()

in tcm_fc/tfc_io.c [41:183]

• 110 lines of code
• 17 McCabe index (conditional complexity)

int ft_queue_data_in(struct se_cmd *se_cmd)
{
	struct ft_cmd *cmd = container_of(se_cmd, struct ft_cmd, se_cmd);
	struct fc_frame *fp = NULL;
	struct fc_exch *ep;
	struct fc_lport *lport;
	struct scatterlist *sg = NULL;
	size_t remaining;
	u32 f_ctl = FC_FC_EX_CTX | FC_FC_REL_OFF;
	u32 mem_off = 0;
	u32 fh_off = 0;
	u32 frame_off = 0;
	size_t frame_len = 0;
	size_t mem_len = 0;
	size_t tlen;
	size_t off_in_page;
	struct page *page = NULL;
	int use_sg;
	int error;
	void *page_addr;
	void *from;
	void *to = NULL;

	if (cmd->aborted)
		return 0;

	if (se_cmd->scsi_status == SAM_STAT_TASK_SET_FULL)
		goto queue_status;

	ep = fc_seq_exch(cmd->seq);
	lport = ep->lp;
	cmd->seq = fc_seq_start_next(cmd->seq);

	remaining = se_cmd->data_length;

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

	/* no scatter/gather in skb for odd word length due to fc_seq_send() */
	use_sg = !(remaining % 4);

	while (remaining) {
		struct fc_seq *seq = cmd->seq;

		if (!seq) {
			pr_debug("%s: Command aborted, xid 0x%x\n",
				 __func__, ep->xid);
			break;
		}
		if (!mem_len) {
			sg = sg_next(sg);
			mem_len = min((size_t)sg->length, remaining);
			mem_off = sg->offset;
			page = sg_page(sg);
		}
		if (!frame_len) {
			/*
			 * If lport's has capability of Large Send Offload LSO)
			 * , then allow 'frame_len' to be as big as 'lso_max'
			 * if indicated transfer length is >= lport->lso_max
			 */
			frame_len = (lport->seq_offload) ? lport->lso_max :
							  cmd->sess->max_frame;
			frame_len = min(frame_len, remaining);
			fp = fc_frame_alloc(lport, use_sg ? 0 : frame_len);
			if (!fp)
				return -ENOMEM;
			to = fc_frame_payload_get(fp, 0);
			fh_off = frame_off;
			frame_off += frame_len;
			/*
			 * Setup the frame's max payload which is used by base
			 * driver to indicate HW about max frame size, so that
			 * HW can do fragmentation appropriately based on
			 * "gso_max_size" of underline netdev.
			 */
			fr_max_payload(fp) = cmd->sess->max_frame;
		}
		tlen = min(mem_len, frame_len);

		if (use_sg) {
			off_in_page = mem_off;
			BUG_ON(!page);
			get_page(page);
			skb_fill_page_desc(fp_skb(fp),
					   skb_shinfo(fp_skb(fp))->nr_frags,
					   page, off_in_page, tlen);
			fr_len(fp) += tlen;
			fp_skb(fp)->data_len += tlen;
			fp_skb(fp)->truesize += page_size(page);
		} else {
			BUG_ON(!page);
			from = kmap_atomic(page + (mem_off >> PAGE_SHIFT));
			page_addr = from;
			from += 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);
			to += tlen;
		}

		mem_off += tlen;
		mem_len -= tlen;
		frame_len -= tlen;
		remaining -= tlen;

		if (frame_len &&
		    (skb_shinfo(fp_skb(fp))->nr_frags < FC_FRAME_SG_LEN))
			continue;
		if (!remaining)
			f_ctl |= FC_FC_END_SEQ;
		fc_fill_fc_hdr(fp, FC_RCTL_DD_SOL_DATA, ep->did, ep->sid,
			       FC_TYPE_FCP, f_ctl, fh_off);
		error = fc_seq_send(lport, seq, fp);
		if (error) {
			pr_info_ratelimited("%s: Failed to send frame %p, "
						"xid <0x%x>, remaining %zu, "
						"lso_max <0x%x>\n",
						__func__, fp, ep->xid,
						remaining, lport->lso_max);
			/*
			 * Go ahead and set TASK_SET_FULL status ignoring the
			 * rest of the DataIN, and immediately attempt to
			 * send the response via ft_queue_status() in order
			 * to notify the initiator that it should reduce it's
			 * per LUN queue_depth.
			 */
			se_cmd->scsi_status = SAM_STAT_TASK_SET_FULL;
			break;
		}
	}
queue_status:
	return ft_queue_status(se_cmd);
}