linux-kernel - [PATCH 4.9 42/51] target/iscsi: Fix unsolicited data seq_end

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Message-Id: <20171019134843.987927478@linuxfoundation.org>
Date:   Thu, 19 Oct 2017 15:49:03 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Varun Prakash <varun@...lsio.com>,
        Bart Van Assche <bart.vanassche@...disk.com>,
        Nicholas Bellinger <nab@...ux-iscsi.org>,
        Sasha Levin <alexander.levin@...izon.com>
Subject: [PATCH 4.9 42/51] target/iscsi: Fix unsolicited data seq_end_offset calculation

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Varun Prakash <varun@...lsio.com>


[ Upstream commit 4d65491c269729a1e3b375c45e73213f49103d33 ]

In case of unsolicited data for the first sequence
seq_end_offset must be set to minimum of total data length
and FirstBurstLength, so do not add cmd->write_data_done
to the min of total data length and FirstBurstLength.

This patch avoids that with ImmediateData=Yes, InitialR2T=No,
MaxXmitDataSegmentLength < FirstBurstLength that a WRITE command
with IO size above FirstBurstLength triggers sequence error
messages, for example

Set following parameters on target (linux-4.8.12)
ImmediateData = Yes
InitialR2T = No
MaxXmitDataSegmentLength = 8k
FirstBurstLength = 64k

Log in from Open iSCSI initiator and execute
dd if=/dev/zero of=/dev/sdb bs=128k count=1 oflag=direct

Error messages on target
Command ITT: 0x00000035 with Offset: 65536, Length: 8192 outside
of Sequence 73728:131072 while DataSequenceInOrder=Yes.
Command ITT: 0x00000035, received DataSN: 0x00000001 higher than
expected 0x00000000.
Unable to perform within-command recovery while ERL=0.

Signed-off-by: Varun Prakash <varun@...lsio.com>
[ bvanassche: Use min() instead of open-coding it / edited patch description ]
Signed-off-by: Bart Van Assche <bart.vanassche@...disk.com>
Signed-off-by: Nicholas Bellinger <nab@...ux-iscsi.org>

Signed-off-by: Sasha Levin <alexander.levin@...izon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/target/iscsi/iscsi_target_erl0.c |    6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

--- a/drivers/target/iscsi/iscsi_target_erl0.c
+++ b/drivers/target/iscsi/iscsi_target_erl0.c
@@ -44,10 +44,8 @@ void iscsit_set_dataout_sequence_values(
 	 */
 	if (cmd->unsolicited_data) {
 		cmd->seq_start_offset = cmd->write_data_done;
-		cmd->seq_end_offset = (cmd->write_data_done +
-			((cmd->se_cmd.data_length >
-			  conn->sess->sess_ops->FirstBurstLength) ?
-			 conn->sess->sess_ops->FirstBurstLength : cmd->se_cmd.data_length));
+		cmd->seq_end_offset = min(cmd->se_cmd.data_length,
+					conn->sess->sess_ops->FirstBurstLength);
 		return;
 	}