--- embedaddon/istgt/src/istgt_iscsi.c	2012/10/09 09:13:23	1.1.1.2
+++ embedaddon/istgt/src/istgt_iscsi.c	2013/07/21 23:49:22	1.1.1.3
@@ -117,6 +117,14 @@ static void istgt_remove_conn(CONN_Ptr conn);
 static int istgt_iscsi_drop_all_conns(CONN_Ptr conn);
 static int istgt_iscsi_drop_old_conns(CONN_Ptr conn);
 
+/* Switch to use readv/writev (assume blocking) */
+#define ISTGT_USE_IOVEC
+
+#if defined (ISTGT_USE_IOVEC)
+#include <sys/uio.h>
+#endif
+
+#if !defined (ISTGT_USE_IOVEC)
 #if 0
 #define ISTGT_USE_RECVBLOCK
 #define ISTGT_USE_SENDBLOCK
@@ -376,6 +384,7 @@ istgt_iscsi_write(CONN_Ptr conn, const void *buf, size
 #endif /* ISTGT_USE_SENDBLOCK */
 	return nbytes;
 }
+#endif /* !defined (ISTGT_USE_IOVEC) */
 
 #define MATCH_DIGEST_WORD(BUF, CRC32C) \
 	(    ((((uint32_t) *((uint8_t *)(BUF)+0)) << 0)		\
@@ -417,6 +426,7 @@ istgt_make_digest_word(uint8_t *buf, size_t len, uint3
 }
 #endif
 
+#if !defined (ISTGT_USE_IOVEC)
 static int
 istgt_iscsi_read_pdu(CONN_Ptr conn, ISCSI_PDU_Ptr pdu)
 {
@@ -447,13 +457,14 @@ istgt_iscsi_read_pdu(CONN_Ptr conn, ISCSI_PDU_Ptr pdu)
 			    conn->initiator_name);
 			conn->state = CONN_STATE_EXITING;
 		} else {
-			ISTGT_ERRLOG("iscsi_read() failed (errno=%d)\n",
-			    errno);
+			ISTGT_ERRLOG("iscsi_read() failed (errno=%d,%s)\n",
+			    errno, conn->initiator_name);
 		}
 		return -1;
 	}
 	if (rc == 0) {
-		ISTGT_TRACELOG(ISTGT_TRACE_NET, "iscsi_read() EOF\n");
+		ISTGT_TRACELOG(ISTGT_TRACE_NET, "iscsi_read() EOF (%s)\n",
+		    conn->initiator_name);
 		conn->state = CONN_STATE_EXITING;
 		return -1;
 	}
@@ -471,7 +482,8 @@ istgt_iscsi_read_pdu(CONN_Ptr conn, ISCSI_PDU_Ptr pdu)
 		    (4 * total_ahs_len));
 		rc = istgt_iscsi_read(conn, pdu->ahs, (4 * total_ahs_len));
 		if (rc < 0) {
-			ISTGT_ERRLOG("iscsi_read() failed\n");
+			ISTGT_ERRLOG("iscsi_read() failed (errno=%d,%s)\n",
+			    errno, conn->initiator_name);
 			return -1;
 		}
 		if (rc == 0) {
@@ -497,7 +509,8 @@ istgt_iscsi_read_pdu(CONN_Ptr conn, ISCSI_PDU_Ptr pdu)
 		rc = istgt_iscsi_read(conn, pdu->header_digest,
 		    ISCSI_DIGEST_LEN);
 		if (rc < 0) {
-			ISTGT_ERRLOG("iscsi_read() failed\n");
+			ISTGT_ERRLOG("iscsi_read() failed (errno=%d,%s)\n",
+			    errno, conn->initiator_name);
 			{
 				int opcode = BGET8W(&pdu->bhs.opcode, 5, 6);
 				ISTGT_ERRLOG("Header Digest read error (opcode = 0x%x)\n",
@@ -540,8 +553,8 @@ istgt_iscsi_read_pdu(CONN_Ptr conn, ISCSI_PDU_Ptr pdu)
 		    data_len);
 		rc = istgt_iscsi_read(conn, pdu->data, data_len);
 		if (rc < 0) {
-			ISTGT_ERRLOG("iscsi_read() failed (%d,errno=%d)\n",
-			    rc, errno);
+			ISTGT_ERRLOG("iscsi_read() failed (%d,errno=%d,%s)\n",
+			    rc, errno, conn->initiator_name);
 			return -1;
 		}
 		if (rc == 0) {
@@ -577,7 +590,8 @@ istgt_iscsi_read_pdu(CONN_Ptr conn, ISCSI_PDU_Ptr pdu)
 		rc = istgt_iscsi_read(conn, pdu->data_digest,
 		    ISCSI_DIGEST_LEN);
 		if (rc < 0) {
-			ISTGT_ERRLOG("iscsi_read() failed\n");
+			ISTGT_ERRLOG("iscsi_read() failed (errno=%d,%s)\n",
+			    errno, conn->initiator_name);
 			return -1;
 		}
 		if (rc == 0) {
@@ -611,7 +625,7 @@ istgt_iscsi_read_pdu(CONN_Ptr conn, ISCSI_PDU_Ptr pdu)
 		}
 		rc = MATCH_DIGEST_WORD(pdu->header_digest, crc32c);
 		if (rc == 0) {
-			ISTGT_ERRLOG("header digest error\n");
+			ISTGT_ERRLOG("header digest error (%s)\n", conn->initiator_name);
 			return -1;
 		}
 	}
@@ -619,14 +633,198 @@ istgt_iscsi_read_pdu(CONN_Ptr conn, ISCSI_PDU_Ptr pdu)
 		crc32c = istgt_crc32c(pdu->data, data_len);
 		rc = MATCH_DIGEST_WORD(pdu->data_digest, crc32c);
 		if (rc == 0) {
-			ISTGT_ERRLOG("data digest error\n");
+			ISTGT_ERRLOG("data digest error (%s)\n", conn->initiator_name);
 			return -1;
 		}
 	}
 
 	return total;
 }
+#else /* defined (ISTGT_USE_IOVEC) */
+static int
+istgt_iscsi_read_pdu(CONN_Ptr conn, ISCSI_PDU_Ptr pdu)
+{
+	struct iovec iovec[4]; /* AHS+HD+DATA+DD */
+	uint32_t crc32c;
+	time_t start, now;
+	int nbytes;
+	int total_ahs_len;
+	int data_len;
+	int segment_len;
+	int total;
+	int rc;
+	int i;
 
+	pdu->ahs = NULL;
+	pdu->total_ahs_len = 0;
+	pdu->data = NULL;
+	pdu->data_segment_len = 0;
+	total = 0;
+
+	/* BHS (require for all PDU) */
+	ISTGT_TRACELOG(ISTGT_TRACE_NET, "BHS read %d\n",
+	    ISCSI_BHS_LEN);
+	errno = 0;
+	start = time(NULL);
+	rc = recv(conn->sock, &pdu->bhs, ISCSI_BHS_LEN, MSG_WAITALL);
+	if (rc < 0) {
+		now = time(NULL);
+		if (errno == ECONNRESET) {
+			ISTGT_WARNLOG("Connection reset by peer (%s,time=%d)\n",
+			    conn->initiator_name, (int)difftime(now, start));
+			conn->state = CONN_STATE_EXITING;
+		} else if (errno == ETIMEDOUT) {
+			ISTGT_WARNLOG("Operation timed out (%s,time=%d)\n",
+			    conn->initiator_name, (int)difftime(now, start));
+			conn->state = CONN_STATE_EXITING;
+		} else {
+			ISTGT_ERRLOG("iscsi_read() failed (errno=%d,%s,time=%d)\n",
+			    errno, conn->initiator_name, (int)difftime(now, start));
+		}
+		return -1;
+	}
+	if (rc == 0) {
+		ISTGT_TRACELOG(ISTGT_TRACE_NET, "recv() EOF (%s)\n",
+		    conn->initiator_name);
+		conn->state = CONN_STATE_EXITING;
+		return -1;
+	}
+	if (rc != ISCSI_BHS_LEN) {
+		ISTGT_ERRLOG("invalid BHS length (%d,%s)\n", rc, conn->initiator_name);
+		return -1;
+	}
+	total += ISCSI_BHS_LEN;
+
+	/* AHS */
+	total_ahs_len = DGET8(&pdu->bhs.total_ahs_len);
+	if (total_ahs_len != 0) {
+		pdu->ahs = xmalloc(ISCSI_ALIGN((4 * total_ahs_len)));
+		pdu->total_ahs_len = total_ahs_len;
+		total += (4 * total_ahs_len);
+	} else {
+		pdu->ahs = NULL;
+		pdu->total_ahs_len = 0;
+	}
+	iovec[0].iov_base = pdu->ahs;
+	iovec[0].iov_len = 4 * pdu->total_ahs_len;
+
+	/* Header Digest */
+	iovec[1].iov_base = pdu->header_digest;
+	if (conn->header_digest) {
+		iovec[1].iov_len = ISCSI_DIGEST_LEN;
+		total += ISCSI_DIGEST_LEN;
+	} else {
+		iovec[1].iov_len = 0;
+	}
+
+	/* Data Segment */
+	data_len = DGET24(&pdu->bhs.data_segment_len[0]);
+	if (data_len != 0) {
+		if (conn->sess == NULL) {
+			segment_len = DEFAULT_FIRSTBURSTLENGTH;
+		} else {
+			segment_len = conn->MaxRecvDataSegmentLength;
+		}
+		if (data_len > segment_len) {
+			ISTGT_ERRLOG("Data(%d) > Segment(%d)\n",
+			    data_len, segment_len);
+			return -1;
+		}
+		if (ISCSI_ALIGN(data_len) <= ISTGT_SHORTDATASIZE) {
+			pdu->data = pdu->shortdata;
+		} else {
+			pdu->data = xmalloc(ISCSI_ALIGN(segment_len));
+		}
+		pdu->data_segment_len = data_len;
+		total += ISCSI_ALIGN(data_len);
+	} else {
+		pdu->data = NULL;
+		pdu->data_segment_len = 0;
+	}
+	iovec[2].iov_base = pdu->data;
+	iovec[2].iov_len = ISCSI_ALIGN(pdu->data_segment_len);
+
+	/* Data Digest */
+	iovec[3].iov_base = pdu->data_digest;
+	if (conn->data_digest && data_len != 0) {
+		iovec[3].iov_len = ISCSI_DIGEST_LEN;
+		total += ISCSI_DIGEST_LEN;
+	} else {
+		iovec[3].iov_len = 0;
+	}
+
+	/* read all bytes to iovec */
+	nbytes = total - ISCSI_BHS_LEN;
+	ISTGT_TRACELOG(ISTGT_TRACE_NET, "PDU read %d\n", nbytes);
+	errno = 0;
+	start = time(NULL);
+	while (nbytes > 0) {
+		rc = readv(conn->sock, &iovec[0], 4);
+		if (rc < 0) {
+			now = time(NULL);
+			ISTGT_ERRLOG("readv() failed (%d,errno=%d,%s,time=%d)\n",
+			    rc, errno, conn->initiator_name, (int)difftime(now, start));
+			return -1;
+		}
+		if (rc == 0) {
+			ISTGT_TRACELOG(ISTGT_TRACE_NET, "readv() EOF (%s)\n",
+			    conn->initiator_name);
+			conn->state = CONN_STATE_EXITING;
+			return -1;
+		}
+		nbytes -= rc;
+		if (nbytes == 0)
+			break;
+		/* adjust iovec length */
+		for (i = 0; i < 4; i++) {
+			if (iovec[i].iov_len != 0 && iovec[i].iov_len > (size_t)rc) {
+				iovec[i].iov_base
+					= (void *) (((uintptr_t)iovec[i].iov_base) + rc);
+				iovec[i].iov_len -= rc;
+				break;
+			} else {
+				rc -= iovec[i].iov_len;
+				iovec[i].iov_len = 0;
+			}
+		}
+	}
+
+	/* check digest */
+	if (conn->header_digest) {
+		if (total_ahs_len == 0) {
+			crc32c = istgt_crc32c((uint8_t *) &pdu->bhs,
+			    ISCSI_BHS_LEN);
+		} else {
+			int upd_total = 0;
+			crc32c = ISTGT_CRC32C_INITIAL;
+			crc32c = istgt_update_crc32c((uint8_t *) &pdu->bhs,
+			    ISCSI_BHS_LEN, crc32c);
+			upd_total += ISCSI_BHS_LEN;
+			crc32c = istgt_update_crc32c((uint8_t *) pdu->ahs,
+			    (4 * total_ahs_len), crc32c);
+			upd_total += (4 * total_ahs_len);
+			crc32c = istgt_fixup_crc32c(upd_total, crc32c);
+			crc32c = crc32c ^ ISTGT_CRC32C_XOR;
+		}
+		rc = MATCH_DIGEST_WORD(pdu->header_digest, crc32c);
+		if (rc == 0) {
+			ISTGT_ERRLOG("header digest error (%s)\n", conn->initiator_name);
+			return -1;
+		}
+	}
+	if (conn->data_digest && data_len != 0) {
+		crc32c = istgt_crc32c(pdu->data, ISCSI_ALIGN(data_len));
+		rc = MATCH_DIGEST_WORD(pdu->data_digest, crc32c);
+		if (rc == 0) {
+			ISTGT_ERRLOG("data digest error (%s)\n", conn->initiator_name);
+			return -1;
+		}
+	}
+
+	return total;
+}
+#endif /* defined (ISTGT_USE_IOVEC) */
+
 static int istgt_iscsi_write_pdu_internal(CONN_Ptr conn, ISCSI_PDU_Ptr pdu);
 static int istgt_iscsi_write_pdu_queue(CONN_Ptr conn, ISCSI_PDU_Ptr pdu, int req_type, int I_bit);
 
@@ -787,6 +985,7 @@ istgt_iscsi_write_pdu_queue(CONN_Ptr conn, ISCSI_PDU_P
 	return rc;
 }
 
+#if !defined (ISTGT_USE_IOVEC)
 static int
 istgt_iscsi_write_pdu_internal(CONN_Ptr conn, ISCSI_PDU_Ptr pdu)
 {
@@ -843,8 +1042,8 @@ istgt_iscsi_write_pdu_internal(CONN_Ptr conn, ISCSI_PD
 		    total);
 		rc = istgt_iscsi_write(conn, spp, total);
 		if (rc < 0) {
-			ISTGT_ERRLOG("iscsi_write() failed (errno=%d)\n",
-			    errno);
+			ISTGT_ERRLOG("iscsi_write() failed (errno=%d,%s)\n",
+			    errno, conn->initiator_name);
 			return -1;
 		}
 		if (rc != total) {
@@ -860,7 +1059,8 @@ istgt_iscsi_write_pdu_internal(CONN_Ptr conn, ISCSI_PD
 	    ISCSI_BHS_LEN);
 	rc = istgt_iscsi_write(conn, &pdu->bhs, ISCSI_BHS_LEN);
 	if (rc < 0) {
-		ISTGT_ERRLOG("iscsi_write() failed (errno=%d)\n", errno);
+		ISTGT_ERRLOG("iscsi_write() failed (errno=%d,%s)\n", errno,
+		    conn->initiator_name);
 		return -1;
 	}
 	if (rc != ISCSI_BHS_LEN) {
@@ -875,7 +1075,8 @@ istgt_iscsi_write_pdu_internal(CONN_Ptr conn, ISCSI_PD
 		    (4 * total_ahs_len));
 		rc = istgt_iscsi_write(conn, pdu->ahs, (4 * total_ahs_len));
 		if (rc < 0) {
-			ISTGT_ERRLOG("iscsi_write() failed\n");
+			ISTGT_ERRLOG("iscsi_write() failed (errno=%d,%s)\n",
+			    errno, conn->initiator_name);
 			return -1;
 		}
 		if (rc != (4 * total_ahs_len)) {
@@ -909,7 +1110,8 @@ istgt_iscsi_write_pdu_internal(CONN_Ptr conn, ISCSI_PD
 		rc = istgt_iscsi_write(conn, pdu->header_digest,
 		    ISCSI_DIGEST_LEN);
 		if (rc < 0) {
-			ISTGT_ERRLOG("iscsi_write() failed\n");
+			ISTGT_ERRLOG("iscsi_write() failed (errno=%d,%s)\n",
+			    errno, conn->initiator_name);
 			return -1;
 		}
 		if (rc != ISCSI_DIGEST_LEN) {
@@ -926,7 +1128,8 @@ istgt_iscsi_write_pdu_internal(CONN_Ptr conn, ISCSI_PD
 		    data_len);
 		rc = istgt_iscsi_write(conn, pdu->data, data_len);
 		if (rc < 0) {
-			ISTGT_ERRLOG("iscsi_write() failed\n");
+			ISTGT_ERRLOG("iscsi_write() failed (errno=%d,%s)\n",
+			    errno, conn->initiator_name);
 			return -1;
 		}
 		if (rc != data_len) {
@@ -949,7 +1152,8 @@ istgt_iscsi_write_pdu_internal(CONN_Ptr conn, ISCSI_PD
 		rc = istgt_iscsi_write(conn, pdu->data_digest,
 		    ISCSI_DIGEST_LEN);
 		if (rc < 0) {
-			ISTGT_ERRLOG("iscsi_write() failed\n");
+			ISTGT_ERRLOG("iscsi_write() failed (errno=%d,%s)\n",
+			    errno, conn->initiator_name);
 			return -1;
 		}
 		if (rc != ISCSI_DIGEST_LEN) {
@@ -962,7 +1166,122 @@ istgt_iscsi_write_pdu_internal(CONN_Ptr conn, ISCSI_PD
 
 	return total;
 }
+#else /* defined (ISTGT_USE_IOVEC) */
+static int
+istgt_iscsi_write_pdu_internal(CONN_Ptr conn, ISCSI_PDU_Ptr pdu)
+{
+	struct iovec iovec[5]; /* BHS+AHS+HD+DATA+DD */
+	uint8_t *cp;
+	uint32_t crc32c;
+	time_t start, now;
+	int nbytes;
+	int enable_digest;
+	int opcode;
+	int total_ahs_len;
+	int data_len;
+	int total;
+	int rc;
+	int i;
 
+	cp = (uint8_t *) &pdu->bhs;
+	total_ahs_len = DGET8(&cp[4]);
+	data_len = DGET24(&cp[5]);
+	total = 0;
+
+	enable_digest = 1;
+	opcode = BGET8W(&cp[0], 5, 6);
+	if (opcode == ISCSI_OP_LOGIN_RSP) {
+		/* this PDU should be sent without digest */
+		enable_digest = 0;
+	}
+
+	/* BHS */
+	iovec[0].iov_base = &pdu->bhs;
+	iovec[0].iov_len = ISCSI_BHS_LEN;
+	total += ISCSI_BHS_LEN;
+
+	/* AHS */
+	iovec[1].iov_base = pdu->ahs;
+	iovec[1].iov_len = 4 * total_ahs_len;
+	total += (4 * total_ahs_len);
+
+	/* Header Digest */
+	iovec[2].iov_base = pdu->header_digest;
+	if (enable_digest && conn->header_digest) {
+		if (total_ahs_len == 0) {
+			crc32c = istgt_crc32c((uint8_t *) &pdu->bhs,
+			    ISCSI_BHS_LEN);
+		} else {
+			int upd_total = 0;
+			crc32c = ISTGT_CRC32C_INITIAL;
+			crc32c = istgt_update_crc32c((uint8_t *) &pdu->bhs,
+			    ISCSI_BHS_LEN, crc32c);
+			upd_total += ISCSI_BHS_LEN;
+			crc32c = istgt_update_crc32c((uint8_t *) pdu->ahs,
+			    (4 * total_ahs_len), crc32c);
+			upd_total += (4 * total_ahs_len);
+			crc32c = istgt_fixup_crc32c(upd_total, crc32c);
+			crc32c = crc32c ^ ISTGT_CRC32C_XOR;
+		}
+		MAKE_DIGEST_WORD(pdu->header_digest, crc32c);
+
+		iovec[2].iov_len = ISCSI_DIGEST_LEN;
+		total += ISCSI_DIGEST_LEN;
+	} else {
+		iovec[2].iov_len = 0;
+	}
+
+	/* Data Segment */
+	iovec[3].iov_base = pdu->data;
+	iovec[3].iov_len = ISCSI_ALIGN(data_len);
+	total += ISCSI_ALIGN(data_len);
+
+	/* Data Digest */
+	iovec[4].iov_base = pdu->data_digest;
+	if (enable_digest && conn->data_digest && data_len != 0) {
+		crc32c = istgt_crc32c(pdu->data, ISCSI_ALIGN(data_len));
+		MAKE_DIGEST_WORD(pdu->data_digest, crc32c);
+
+		iovec[4].iov_len = ISCSI_DIGEST_LEN;
+		total += ISCSI_DIGEST_LEN;
+	} else {
+		iovec[4].iov_len = 0;
+	}
+
+	/* write all bytes from iovec */
+	nbytes = total;
+	ISTGT_TRACELOG(ISTGT_TRACE_NET, "PDU write %d\n", nbytes);
+	errno = 0;
+	start = time(NULL);
+	while (nbytes > 0) {
+		rc = writev(conn->sock, &iovec[0], 5);
+		if (rc < 0) {
+			now = time(NULL);
+			ISTGT_ERRLOG("writev() failed (errno=%d,%s,time=%d)\n",
+			    errno, conn->initiator_name, (int)difftime(now, start));
+			return -1;
+		}
+		nbytes -= rc;
+		if (nbytes == 0)
+			break;
+		/* adjust iovec length */
+		for (i = 0; i < 5; i++) {
+			if (iovec[i].iov_len != 0 && iovec[i].iov_len > (size_t)rc) {
+				iovec[i].iov_base
+					= (void *) (((uintptr_t)iovec[i].iov_base) + rc);
+				iovec[i].iov_len -= rc;
+				break;
+			} else {
+				rc -= iovec[i].iov_len;
+				iovec[i].iov_len = 0;
+			}
+		}
+	}
+
+	return total;
+}
+#endif /* defined (ISTGT_USE_IOVEC) */
+
 int
 istgt_iscsi_copy_pdu(ISCSI_PDU_Ptr dst_pdu, ISCSI_PDU_Ptr src_pdu)
 {
@@ -3239,10 +3558,10 @@ istgt_iscsi_op_scsi(CONN_Ptr conn, ISCSI_PDU_Ptr pdu)
 		if (SN32_GT(CmdSN, conn->sess->ExpCmdSN)) {
 			if (conn->sess->connections > 1) {
 				struct timespec abstime;
-				time_t now;
+				time_t start, now;
 
 				SESS_MTX_UNLOCK(conn);
-				now = time(NULL);
+				start = now = time(NULL);
 				memset(&abstime, 0, sizeof abstime);
 				abstime.tv_sec = now + (MAX_MCSREVWAIT / 1000);
 				abstime.tv_nsec = (MAX_MCSREVWAIT % 1000) * 1000000;
@@ -3269,8 +3588,11 @@ istgt_iscsi_op_scsi(CONN_Ptr conn, ISCSI_PDU_Ptr pdu)
 					}
 				}
 				if (rc < 0) {
-					ISTGT_ERRLOG("MCS: CmdSN(%u) error ExpCmdSN=%u\n",
-					    CmdSN, conn->sess->ExpCmdSN);
+					now = time(NULL);
+					ISTGT_ERRLOG("MCS: CmdSN(%u) error ExpCmdSN=%u "
+					    "(time=%d)\n",
+					    CmdSN, conn->sess->ExpCmdSN,
+					    (int)difftime(now, start));
 					SESS_MTX_UNLOCK(conn);
 					return -1;
 				}
@@ -5162,7 +5484,11 @@ worker(void *arg)
 		return NULL;
 	}
 	conn->kq = kq;
+#if defined (ISTGT_USE_IOVEC) && defined (NOTE_LOWAT)
+	ISTGT_EV_SET(&kev, conn->sock, EVFILT_READ, EV_ADD, NOTE_LOWAT, ISCSI_BHS_LEN, NULL);
+#else
 	ISTGT_EV_SET(&kev, conn->sock, EVFILT_READ, EV_ADD, 0, 0, NULL);
+#endif
 	rc = kevent(kq, &kev, 1, NULL, 0, NULL);
 	if (rc == -1) {
 		ISTGT_ERRLOG("kevent() failed\n");
@@ -5351,7 +5677,9 @@ worker(void *arg)
 			conn->pdu.copy_pdu = 0;
 			rc = istgt_iscsi_read_pdu(conn, &conn->pdu);
 			if (rc < 0) {
-				ISTGT_ERRLOG("conn->state = %d\n", conn->state);
+				if (conn->state != CONN_STATE_EXITING) {
+					ISTGT_ERRLOG("conn->state = %d\n", conn->state);
+				}
 				if (conn->state != CONN_STATE_RUNNING) {
 					if (errno == EINPROGRESS) {
 						sleep(1);
@@ -5788,6 +6116,14 @@ istgt_create_conn(ISTGT_Ptr istgt, PORTAL_Ptr portal, 
 		ISTGT_ERRLOG("istgt_set_sendtimeo() failed\n");
 		goto error_return;
 	}
+#if defined (ISTGT_USE_IOVEC)
+	/* set low water mark */
+	rc = istgt_set_recvlowat(conn->sock, ISCSI_BHS_LEN);
+	if (rc != 0) {
+		ISTGT_ERRLOG("istgt_set_recvlowat() failed\n");
+		goto error_return;
+	}
+#endif
 
 	rc = pipe(conn->task_pipe);
 	if (rc != 0) {