From a3ce92c93c19d04953bfbd72395b462fc15fdd50 Mon Sep 17 00:00:00 2001
From: Ronnie Sahlberg <ronniesahlberg@gmail.com>
Date: Sun, 2 Dec 2012 09:55:07 -0800
Subject: [PATCH] Fix sending of unsolicited data in the first burst

When deciding if to generate a data out queue for the first sequence
the test was wrong.
We should not check if INITIAL_R2T is NO and IMMEDIATE_DATA=NO.
Immediate data does not matter here.

What we should check is IF we have more data we need to send and IF
INITIAL_R2T allows us to send more data, then we generate a train of DATA-OUT.

If MaxRecvDataSegmentLength is less than FirstBurstLength we will often have
to send unsolicited data as both ImmediateData and also as unsolicited
DATA-OUT PDUs.

Example:
Assume Target has responded :
MaxRecvDataSegmentLength = 8k
FirstBurstLength = 64k
ImmediateData=YES
InitialR2T=NO

Then this should generate the following sequence :
I->T   ISCSI_COMMAND + 8K of immediate data. F-Bit is not set.
I->T   DATA-OUT 8K
I->T   DATA-OUT 8K
I->T   DATA-OUT 8K
I->T   DATA-OUT 8K
I->T   DATA-OUT 8K
I->T   DATA-OUT 8K
I->T   DATA-OUT 8K. Final PDU in sequence   so F-bit is set.
T->I   R2T
...
---
 lib/iscsi-command.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/lib/iscsi-command.c b/lib/iscsi-command.c
index 1319347..6273b82 100644
--- a/lib/iscsi-command.c
+++ b/lib/iscsi-command.c
@@ -265,14 +265,15 @@ iscsi_scsi_command_async(struct iscsi_context *iscsi, int lun,
 		return -1;
 	}
 
-	/* Can we send some unsolicited data ? */
+	/* Can we send more data that did not fit as immediate data ? */
 	if (task->xfer_dir == SCSI_XFER_WRITE 
 	&& iscsi->use_initial_r2t == ISCSI_INITIAL_R2T_NO 
-	&& iscsi->use_immediate_data == ISCSI_IMMEDIATE_DATA_NO) {
+	&& pdu->out_len < (uint32_t)task->expxferlen
+	&& pdu->out_len < iscsi->first_burst_length) {
 		uint32_t len = task->expxferlen;
 
-		if (len > iscsi->first_burst_length) {
-			len = iscsi->first_burst_length;
+		if (len + pdu->out_len > iscsi->first_burst_length) {
+			len = iscsi->first_burst_length - pdu->out_len;
 		}
 		iscsi_send_data_out(iscsi, pdu, 0xffffffff,
 				    pdu->out_offset, len);