iscsi-target: Do not reject non-immediate CmdSNs exceeding MaxCmdSN

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Gitweb:     http://git.infradead.org/?p=mtd-2.6.git;a=commit;h=ea7e32bec1b9d9e5b159d80ceb563c702e28b02a
Commit:     ea7e32bec1b9d9e5b159d80ceb563c702e28b02a
Parent:     04f3b31bff720f01d684100c868c88f67ced8dc8
Author:     Nicholas Bellinger <nab at linux-iscsi.org>
AuthorDate: Mon Nov 18 10:55:10 2013 -0800
Committer:  Nicholas Bellinger <nab at linux-iscsi.org>
CommitDate: Tue Nov 19 21:39:21 2013 -0800

    iscsi-target: Do not reject non-immediate CmdSNs exceeding MaxCmdSN
    
    This patch changes iscsit_sequence_cmd() logic to no longer reject
    non-immediate CmdSNs that exceed MaxCmdSN with a protocol error,
    but instead silently ignore them.
    
    This is done to correctly follow RFC-3720 Section 3.2.2.1:
    
       For non-immediate commands, the CmdSN field can take any
       value from ExpCmdSN to MaxCmdSN inclusive.  The target MUST silently
       ignore any non-immediate command outside of this range or non-
       immediate duplicates within the range.
    
    Reported-by: Santosh Kulkarni <santosh.kulkarni at calsoftinc.com>
    Signed-off-by: Nicholas Bellinger <nab at linux-iscsi.org>
---
 drivers/target/iscsi/iscsi_target_core.h |  1 +
 drivers/target/iscsi/iscsi_target_util.c | 18 ++++++++++--------
 2 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/drivers/target/iscsi/iscsi_target_core.h b/drivers/target/iscsi/iscsi_target_core.h
index f2094d2..8dcb3c1 100644
--- a/drivers/target/iscsi/iscsi_target_core.h
+++ b/drivers/target/iscsi/iscsi_target_core.h
@@ -193,6 +193,7 @@ enum recover_cmdsn_ret_table {
 	CMDSN_NORMAL_OPERATION		= 0,
 	CMDSN_LOWER_THAN_EXP		= 1,
 	CMDSN_HIGHER_THAN_EXP		= 2,
+	CMDSN_MAXCMDSN_OVERRUN		= 3,
 };
 
 /* Used for iscsi_handle_immediate_data() return values */
diff --git a/drivers/target/iscsi/iscsi_target_util.c b/drivers/target/iscsi/iscsi_target_util.c
index 45b8fd1..9064926 100644
--- a/drivers/target/iscsi/iscsi_target_util.c
+++ b/drivers/target/iscsi/iscsi_target_util.c
@@ -242,9 +242,9 @@ static inline int iscsit_check_received_cmdsn(struct iscsi_session *sess, u32 cm
 	 */
 	if (iscsi_sna_gt(cmdsn, sess->max_cmd_sn)) {
 		pr_err("Received CmdSN: 0x%08x is greater than"
-		       " MaxCmdSN: 0x%08x, protocol error.\n", cmdsn,
+		       " MaxCmdSN: 0x%08x, ignoring.\n", cmdsn,
 		       sess->max_cmd_sn);
-		ret = CMDSN_ERROR_CANNOT_RECOVER;
+		ret = CMDSN_MAXCMDSN_OVERRUN;
 
 	} else if (cmdsn == sess->exp_cmd_sn) {
 		sess->exp_cmd_sn++;
@@ -303,14 +303,16 @@ int iscsit_sequence_cmd(struct iscsi_conn *conn, struct iscsi_cmd *cmd,
 		ret = CMDSN_HIGHER_THAN_EXP;
 		break;
 	case CMDSN_LOWER_THAN_EXP:
+	case CMDSN_MAXCMDSN_OVERRUN:
+	default:
 		cmd->i_state = ISTATE_REMOVE;
 		iscsit_add_cmd_to_immediate_queue(cmd, conn, cmd->i_state);
-		ret = cmdsn_ret;
-		break;
-	default:
-		reason = ISCSI_REASON_PROTOCOL_ERROR;
-		reject = true;
-		ret = cmdsn_ret;
+		/*
+		 * Existing callers for iscsit_sequence_cmd() will silently
+		 * ignore commands with CMDSN_LOWER_THAN_EXP, so force this
+		 * return for CMDSN_MAXCMDSN_OVERRUN as well..
+		 */
+		ret = CMDSN_LOWER_THAN_EXP;
 		break;
 	}
 	mutex_unlock(&conn->sess->cmdsn_mutex);