[SCSI] iscsi_tcp: enable sg chaining

The previous patches converted iscsi_tcp to support sg chaining.
This patch sets the proper flags and sets sg_table size to
4096. This allows fs io to be capped at max_sectors, but passthrough
IO to be limited by some other part of the kernel.

Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

drivers/scsi/iscsi_tcp.c

@@ -1928,13 +1928,14 @@ static struct scsi_host_template iscsi_sht = {
 	.queuecommand           = iscsi_queuecommand,
 	.change_queue_depth	= iscsi_change_queue_depth,
 	.can_queue		= ISCSI_DEF_XMIT_CMDS_MAX - 1,
-	.sg_tablesize		= ISCSI_SG_TABLESIZE,
+	.sg_tablesize		= 4096,
 	.max_sectors		= 0xFFFF,
 	.cmd_per_lun		= ISCSI_DEF_CMD_PER_LUN,
 	.eh_abort_handler       = iscsi_eh_abort,
 	.eh_device_reset_handler= iscsi_eh_device_reset,
 	.eh_host_reset_handler	= iscsi_eh_host_reset,
 	.use_clustering         = DISABLE_CLUSTERING,
+	.use_sg_chaining	= ENABLE_SG_CHAINING,
 	.slave_configure        = iscsi_tcp_slave_configure,
 	.proc_name		= "iscsi_tcp",
 	.this_id		= -1,
@@ -1974,7 +1975,7 @@ static struct iscsi_transport iscsi_tcp_transport = {
 	.host_template		= &iscsi_sht,
 	.conndata_size		= sizeof(struct iscsi_conn),
 	.max_conn		= 1,
-	.max_cmd_len		= ISCSI_TCP_MAX_CMD_LEN,
+	.max_cmd_len		= 16,
 	/* session management */
 	.create_session		= iscsi_tcp_session_create,
 	.destroy_session	= iscsi_tcp_session_destroy,

drivers/scsi/iscsi_tcp.h

@@ -24,9 +24,6 @@
 
 #include <scsi/libiscsi.h>
 
-#define ISCSI_SG_TABLESIZE		SG_ALL
-#define ISCSI_TCP_MAX_CMD_LEN		16
-
 struct crypto_hash;
 struct socket;
 struct iscsi_tcp_conn;