This is for Jens' sglist branch in the block git tree.

It enables sg chaining support for the LLDs that use scsi_for_each_sg
accessor properly.

---
>From a6e50a3b476bc193de103e8c1d95877ced38918e Mon Sep 17 00:00:00 2001
From: FUJITA Tomonori <[EMAIL PROTECTED]>
Date: Fri, 17 Aug 2007 01:35:41 +0900
Subject: [PATCH] add use_sg_chaining option to scsi_host_template

This option is true if a low-level driver can support sg
chaining. This will be removed eventually when all the drivers are
converted to support sg chaining. q->max_phys_segments is set to
SCSI_MAX_SG_SEGMENTS if false.

Signed-off-by: FUJITA Tomonori <[EMAIL PROTECTED]>
---
 arch/ia64/hp/sim/simscsi.c            |    1 +
 drivers/scsi/3w-9xxx.c                |    1 +
 drivers/scsi/3w-xxxx.c                |    1 +
 drivers/scsi/BusLogic.c               |    1 +
 drivers/scsi/NCR53c406a.c             |    3 ++-
 drivers/scsi/a100u2w.c                |    1 +
 drivers/scsi/aacraid/linit.c          |    1 +
 drivers/scsi/aha1740.c                |    1 +
 drivers/scsi/aic7xxx/aic79xx_osm.c    |    1 +
 drivers/scsi/aic7xxx/aic7xxx_osm.c    |    1 +
 drivers/scsi/aic7xxx_old.c            |    1 +
 drivers/scsi/arcmsr/arcmsr_hba.c      |    1 +
 drivers/scsi/dc395x.c                 |    1 +
 drivers/scsi/dpt_i2o.c                |    1 +
 drivers/scsi/eata.c                   |    3 ++-
 drivers/scsi/hosts.c                  |    1 +
 drivers/scsi/hptiop.c                 |    1 +
 drivers/scsi/ibmmca.c                 |    1 +
 drivers/scsi/ibmvscsi/ibmvscsi.c      |    1 +
 drivers/scsi/initio.c                 |    1 +
 drivers/scsi/ipr.c                    |    1 +
 drivers/scsi/lpfc/lpfc_scsi.c         |    2 ++
 drivers/scsi/mac53c94.c               |    1 +
 drivers/scsi/megaraid.c               |    1 +
 drivers/scsi/megaraid/megaraid_mbox.c |    1 +
 drivers/scsi/megaraid/megaraid_sas.c  |    1 +
 drivers/scsi/mesh.c                   |    1 +
 drivers/scsi/nsp32.c                  |    1 +
 drivers/scsi/pcmcia/sym53c500_cs.c    |    1 +
 drivers/scsi/qla2xxx/qla_os.c         |    2 ++
 drivers/scsi/qla4xxx/ql4_os.c         |    1 +
 drivers/scsi/qlogicfas.c              |    1 +
 drivers/scsi/scsi_lib.c               |    5 ++++-
 drivers/scsi/stex.c                   |    1 +
 drivers/scsi/sym53c416.c              |    1 +
 drivers/scsi/sym53c8xx_2/sym_glue.c   |    1 +
 drivers/scsi/u14-34f.c                |    1 +
 drivers/scsi/ultrastor.c              |    1 +
 drivers/scsi/wd7000.c                 |    1 +
 include/scsi/scsi_host.h              |   13 +++++++++++++
 40 files changed, 59 insertions(+), 3 deletions(-)

diff --git a/arch/ia64/hp/sim/simscsi.c b/arch/ia64/hp/sim/simscsi.c
index e62694f..6fc2cba 100644
--- a/arch/ia64/hp/sim/simscsi.c
+++ b/arch/ia64/hp/sim/simscsi.c
@@ -361,6 +361,7 @@ static struct scsi_host_template driver_template = {
        .max_sectors            = 1024,
        .cmd_per_lun            = SIMSCSI_REQ_QUEUE_LEN,
        .use_clustering         = DISABLE_CLUSTERING,
+       .use_sg_chaining        = ENABLE_SG_CHAINING,
 };
 
 static int __init
diff --git a/drivers/scsi/3w-9xxx.c b/drivers/scsi/3w-9xxx.c
index efd9d8d..fb14014 100644
--- a/drivers/scsi/3w-9xxx.c
+++ b/drivers/scsi/3w-9xxx.c
@@ -1990,6 +1990,7 @@ static struct scsi_host_template driver_template = {
        .max_sectors            = TW_MAX_SECTORS,
        .cmd_per_lun            = TW_MAX_CMDS_PER_LUN,
        .use_clustering         = ENABLE_CLUSTERING,
+       .use_sg_chaining        = ENABLE_SG_CHAINING,
        .shost_attrs            = twa_host_attrs,
        .emulated               = 1
 };
diff --git a/drivers/scsi/3w-xxxx.c b/drivers/scsi/3w-xxxx.c
index c7995fc..a64153b 100644
--- a/drivers/scsi/3w-xxxx.c
+++ b/drivers/scsi/3w-xxxx.c
@@ -2261,6 +2261,7 @@ static struct scsi_host_template driver_template = {
        .max_sectors            = TW_MAX_SECTORS,
        .cmd_per_lun            = TW_MAX_CMDS_PER_LUN,  
        .use_clustering         = ENABLE_CLUSTERING,
+       .use_sg_chaining        = ENABLE_SG_CHAINING,
        .shost_attrs            = tw_host_attrs,
        .emulated               = 1
 };
diff --git a/drivers/scsi/BusLogic.c b/drivers/scsi/BusLogic.c
index 9b20617..49e1ffa 100644
--- a/drivers/scsi/BusLogic.c
+++ b/drivers/scsi/BusLogic.c
@@ -3575,6 +3575,7 @@ static struct scsi_host_template Bus_Logic_template = {
        .unchecked_isa_dma = 1,
        .max_sectors = 128,
        .use_clustering = ENABLE_CLUSTERING,
+       .use_sg_chaining = ENABLE_SG_CHAINING,
 };
 
 /*
diff --git a/drivers/scsi/NCR53c406a.c b/drivers/scsi/NCR53c406a.c
index eda8c48..3168a17 100644
--- a/drivers/scsi/NCR53c406a.c
+++ b/drivers/scsi/NCR53c406a.c
@@ -1066,7 +1066,8 @@ static struct scsi_host_template driver_template =
      .sg_tablesize             = 32                    /*SG_ALL*/ /*SG_NONE*/, 
      .cmd_per_lun              = 1                     /* commands per lun */, 
      .unchecked_isa_dma        = 1                     /* unchecked_isa_dma */,
-     .use_clustering           = ENABLE_CLUSTERING                             
  
+     .use_clustering           = ENABLE_CLUSTERING,
+     .use_sg_chaining           = ENABLE_SG_CHAINING,
 };
 
 #include "scsi_module.c"
diff --git a/drivers/scsi/a100u2w.c b/drivers/scsi/a100u2w.c
index f608d4a..d3a6d15 100644
--- a/drivers/scsi/a100u2w.c
+++ b/drivers/scsi/a100u2w.c
@@ -1071,6 +1071,7 @@ static struct scsi_host_template inia100_template = {
        .sg_tablesize           = SG_ALL,
        .cmd_per_lun            = 1,
        .use_clustering         = ENABLE_CLUSTERING,
+       .use_sg_chaining        = ENABLE_SG_CHAINING,
 };
 
 static int __devinit inia100_probe_one(struct pci_dev *pdev,
diff --git a/drivers/scsi/aacraid/linit.c b/drivers/scsi/aacraid/linit.c
index a7f42a1..038980b 100644
--- a/drivers/scsi/aacraid/linit.c
+++ b/drivers/scsi/aacraid/linit.c
@@ -944,6 +944,7 @@ static struct scsi_host_template aac_driver_template = {
        .cmd_per_lun                    = AAC_NUM_IO_FIB, 
 #endif 
        .use_clustering                 = ENABLE_CLUSTERING,
+       .use_sg_chaining                = ENABLE_SG_CHAINING,
        .emulated                       = 1,
 };
 
diff --git a/drivers/scsi/aha1740.c b/drivers/scsi/aha1740.c
index e4a4f3a..f6722fd 100644
--- a/drivers/scsi/aha1740.c
+++ b/drivers/scsi/aha1740.c
@@ -563,6 +563,7 @@ static struct scsi_host_template aha1740_template = {
        .sg_tablesize     = AHA1740_SCATTER,
        .cmd_per_lun      = AHA1740_CMDLUN,
        .use_clustering   = ENABLE_CLUSTERING,
+       .use_sg_chaining  = ENABLE_SG_CHAINING,
        .eh_abort_handler = aha1740_eh_abort_handler,
 };
 
diff --git a/drivers/scsi/aic7xxx/aic79xx_osm.c 
b/drivers/scsi/aic7xxx/aic79xx_osm.c
index a055a96..42c0f14 100644
--- a/drivers/scsi/aic7xxx/aic79xx_osm.c
+++ b/drivers/scsi/aic7xxx/aic79xx_osm.c
@@ -766,6 +766,7 @@ struct scsi_host_template aic79xx_driver_template = {
        .max_sectors            = 8192,
        .cmd_per_lun            = 2,
        .use_clustering         = ENABLE_CLUSTERING,
+       .use_sg_chaining        = ENABLE_SG_CHAINING,
        .slave_alloc            = ahd_linux_slave_alloc,
        .slave_configure        = ahd_linux_slave_configure,
        .target_alloc           = ahd_linux_target_alloc,
diff --git a/drivers/scsi/aic7xxx/aic7xxx_osm.c 
b/drivers/scsi/aic7xxx/aic7xxx_osm.c
index 2e9c38f..7770bef 100644
--- a/drivers/scsi/aic7xxx/aic7xxx_osm.c
+++ b/drivers/scsi/aic7xxx/aic7xxx_osm.c
@@ -747,6 +747,7 @@ struct scsi_host_template aic7xxx_driver_template = {
        .max_sectors            = 8192,
        .cmd_per_lun            = 2,
        .use_clustering         = ENABLE_CLUSTERING,
+       .use_sg_chaining        = ENABLE_SG_CHAINING,
        .slave_alloc            = ahc_linux_slave_alloc,
        .slave_configure        = ahc_linux_slave_configure,
        .target_alloc           = ahc_linux_target_alloc,
diff --git a/drivers/scsi/aic7xxx_old.c b/drivers/scsi/aic7xxx_old.c
index 4998bb8..19dbc2f 100644
--- a/drivers/scsi/aic7xxx_old.c
+++ b/drivers/scsi/aic7xxx_old.c
@@ -11144,6 +11144,7 @@ static struct scsi_host_template driver_template = {
        .max_sectors            = 2048,
        .cmd_per_lun            = 3,
        .use_clustering         = ENABLE_CLUSTERING,
+       .use_sg_chaining        = ENABLE_SG_CHAINING,
 };
 
 #include "scsi_module.c"
diff --git a/drivers/scsi/arcmsr/arcmsr_hba.c b/drivers/scsi/arcmsr/arcmsr_hba.c
index 0ddfc21..d5039f3 100644
--- a/drivers/scsi/arcmsr/arcmsr_hba.c
+++ b/drivers/scsi/arcmsr/arcmsr_hba.c
@@ -121,6 +121,7 @@ static struct scsi_host_template arcmsr_scsi_host_template 
= {
        .max_sectors            = ARCMSR_MAX_XFER_SECTORS,
        .cmd_per_lun            = ARCMSR_MAX_CMD_PERLUN,
        .use_clustering         = ENABLE_CLUSTERING,
+       .use_sg_chaining        = ENABLE_SG_CHAINING,
        .shost_attrs            = arcmsr_host_attrs,
 };
 static struct pci_error_handlers arcmsr_pci_error_handlers = {
diff --git a/drivers/scsi/dc395x.c b/drivers/scsi/dc395x.c
index 7b8a345..d2a2026 100644
--- a/drivers/scsi/dc395x.c
+++ b/drivers/scsi/dc395x.c
@@ -4765,6 +4765,7 @@ static struct scsi_host_template dc395x_driver_template = 
{
        .eh_bus_reset_handler   = dc395x_eh_bus_reset,
        .unchecked_isa_dma      = 0,
        .use_clustering         = DISABLE_CLUSTERING,
+       .use_sg_chaining        = ENABLE_SG_CHAINING,
 };
 
 
diff --git a/drivers/scsi/dpt_i2o.c b/drivers/scsi/dpt_i2o.c
index 502732a..e276d40 100644
--- a/drivers/scsi/dpt_i2o.c
+++ b/drivers/scsi/dpt_i2o.c
@@ -3300,6 +3300,7 @@ static struct scsi_host_template adpt_template = {
        .this_id                = 7,
        .cmd_per_lun            = 1,
        .use_clustering         = ENABLE_CLUSTERING,
+       .use_sg_chaining        = ENABLE_SG_CHAINING,
 };
 
 static s32 adpt_scsi_register(adpt_hba* pHba)
diff --git a/drivers/scsi/eata.c b/drivers/scsi/eata.c
index a83e9f1..2f685cf 100644
--- a/drivers/scsi/eata.c
+++ b/drivers/scsi/eata.c
@@ -523,7 +523,8 @@ static struct scsi_host_template driver_template = {
        .slave_configure = eata2x_slave_configure,
        .this_id = 7,
        .unchecked_isa_dma = 1,
-       .use_clustering = ENABLE_CLUSTERING
+       .use_clustering = ENABLE_CLUSTERING,
+       .use_sg_chaining = ENABLE_SG_CHAINING,
 };
 
 #if !defined(__BIG_ENDIAN_BITFIELD) && !defined(__LITTLE_ENDIAN_BITFIELD)
diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c
index 96bc312..8c42539 100644
--- a/drivers/scsi/hosts.c
+++ b/drivers/scsi/hosts.c
@@ -342,6 +342,7 @@ struct Scsi_Host *scsi_host_alloc(struct scsi_host_template 
*sht, int privsize)
        shost->unchecked_isa_dma = sht->unchecked_isa_dma;
        shost->use_clustering = sht->use_clustering;
        shost->ordered_tag = sht->ordered_tag;
+       shost->use_sg_chaining = sht->use_sg_chaining;
 
        if (sht->max_host_blocked)
                shost->max_host_blocked = sht->max_host_blocked;
diff --git a/drivers/scsi/hptiop.c b/drivers/scsi/hptiop.c
index 0e579ca..9552c93 100644
--- a/drivers/scsi/hptiop.c
+++ b/drivers/scsi/hptiop.c
@@ -634,6 +634,7 @@ static struct scsi_host_template driver_template = {
        .unchecked_isa_dma          = 0,
        .emulated                   = 0,
        .use_clustering             = ENABLE_CLUSTERING,
+       .use_sg_chaining            = ENABLE_SG_CHAINING,
        .proc_name                  = driver_name,
        .shost_attrs                = hptiop_attrs,
        .this_id                    = -1,
diff --git a/drivers/scsi/ibmmca.c b/drivers/scsi/ibmmca.c
index 4275d1b..a3d8d75 100644
--- a/drivers/scsi/ibmmca.c
+++ b/drivers/scsi/ibmmca.c
@@ -1508,6 +1508,7 @@ static struct scsi_host_template ibmmca_driver_template = 
{
           .sg_tablesize   = 16,
           .cmd_per_lun    = 1,
           .use_clustering = ENABLE_CLUSTERING,
+          .use_sg_chaining = ENABLE_SG_CHAINING,
 };
 
 static int ibmmca_probe(struct device *dev)
diff --git a/drivers/scsi/ibmvscsi/ibmvscsi.c b/drivers/scsi/ibmvscsi/ibmvscsi.c
index 5ecc63d..46a4b24 100644
--- a/drivers/scsi/ibmvscsi/ibmvscsi.c
+++ b/drivers/scsi/ibmvscsi/ibmvscsi.c
@@ -1542,6 +1542,7 @@ static struct scsi_host_template driver_template = {
        .this_id = -1,
        .sg_tablesize = SG_ALL,
        .use_clustering = ENABLE_CLUSTERING,
+       .use_sg_chaining = ENABLE_SG_CHAINING,
        .shost_attrs = ibmvscsi_attrs,
 };
 
diff --git a/drivers/scsi/initio.c b/drivers/scsi/initio.c
index d9dfb69..22d40fd 100644
--- a/drivers/scsi/initio.c
+++ b/drivers/scsi/initio.c
@@ -2831,6 +2831,7 @@ static struct scsi_host_template initio_template = {
        .sg_tablesize           = SG_ALL,
        .cmd_per_lun            = 1,
        .use_clustering         = ENABLE_CLUSTERING,
+       .use_sg_chaining        = ENABLE_SG_CHAINING,
 };
 
 static int initio_probe_one(struct pci_dev *pdev,
diff --git a/drivers/scsi/ipr.c b/drivers/scsi/ipr.c
index f142eaf..bec4139 100644
--- a/drivers/scsi/ipr.c
+++ b/drivers/scsi/ipr.c
@@ -4949,6 +4949,7 @@ static struct scsi_host_template driver_template = {
        .max_sectors = IPR_IOA_MAX_SECTORS,
        .cmd_per_lun = IPR_MAX_CMD_PER_LUN,
        .use_clustering = ENABLE_CLUSTERING,
+       .use_sg_chaining = ENABLE_SG_CHAINING,
        .shost_attrs = ipr_ioa_attrs,
        .sdev_attrs = ipr_dev_attrs,
        .proc_name = IPR_NAME
diff --git a/drivers/scsi/lpfc/lpfc_scsi.c b/drivers/scsi/lpfc/lpfc_scsi.c
index 17d7dc0..71c7e22 100644
--- a/drivers/scsi/lpfc/lpfc_scsi.c
+++ b/drivers/scsi/lpfc/lpfc_scsi.c
@@ -1439,6 +1439,7 @@ struct scsi_host_template lpfc_template = {
        .scan_finished          = lpfc_scan_finished,
        .this_id                = -1,
        .sg_tablesize           = LPFC_SG_SEG_CNT,
+       .use_sg_chaining        = ENABLE_SG_CHAINING,
        .cmd_per_lun            = LPFC_CMD_PER_LUN,
        .use_clustering         = ENABLE_CLUSTERING,
        .shost_attrs            = lpfc_hba_attrs,
@@ -1461,6 +1462,7 @@ struct scsi_host_template lpfc_vport_template = {
        .sg_tablesize           = LPFC_SG_SEG_CNT,
        .cmd_per_lun            = LPFC_CMD_PER_LUN,
        .use_clustering         = ENABLE_CLUSTERING,
+       .use_sg_chaining        = ENABLE_SG_CHAINING,
        .shost_attrs            = lpfc_vport_attrs,
        .max_sectors            = 0xFFFF,
 };
diff --git a/drivers/scsi/mac53c94.c b/drivers/scsi/mac53c94.c
index b12ad7c..a035001 100644
--- a/drivers/scsi/mac53c94.c
+++ b/drivers/scsi/mac53c94.c
@@ -402,6 +402,7 @@ static struct scsi_host_template mac53c94_template = {
        .sg_tablesize   = SG_ALL,
        .cmd_per_lun    = 1,
        .use_clustering = DISABLE_CLUSTERING,
+       .use_sg_chaining = ENABLE_SG_CHAINING,
 };
 
 static int mac53c94_probe(struct macio_dev *mdev, const struct of_device_id 
*match)
diff --git a/drivers/scsi/megaraid.c b/drivers/scsi/megaraid.c
index 3907f67..5716e92 100644
--- a/drivers/scsi/megaraid.c
+++ b/drivers/scsi/megaraid.c
@@ -4485,6 +4485,7 @@ static struct scsi_host_template megaraid_template = {
        .sg_tablesize                   = MAX_SGLIST,
        .cmd_per_lun                    = DEF_CMD_PER_LUN,
        .use_clustering                 = ENABLE_CLUSTERING,
+       .use_sg_chaining                = ENABLE_SG_CHAINING,
        .eh_abort_handler               = megaraid_abort,
        .eh_device_reset_handler        = megaraid_reset,
        .eh_bus_reset_handler           = megaraid_reset,
diff --git a/drivers/scsi/megaraid/megaraid_mbox.c 
b/drivers/scsi/megaraid/megaraid_mbox.c
index c6a53dc..e4e4c6a 100644
--- a/drivers/scsi/megaraid/megaraid_mbox.c
+++ b/drivers/scsi/megaraid/megaraid_mbox.c
@@ -361,6 +361,7 @@ static struct scsi_host_template megaraid_template_g = {
        .eh_host_reset_handler          = megaraid_reset_handler,
        .change_queue_depth             = megaraid_change_queue_depth,
        .use_clustering                 = ENABLE_CLUSTERING,
+       .use_sg_chaining                = ENABLE_SG_CHAINING,
        .sdev_attrs                     = megaraid_sdev_attrs,
        .shost_attrs                    = megaraid_shost_attrs,
 };
diff --git a/drivers/scsi/megaraid/megaraid_sas.c 
b/drivers/scsi/megaraid/megaraid_sas.c
index ebb948c..e3c5c52 100644
--- a/drivers/scsi/megaraid/megaraid_sas.c
+++ b/drivers/scsi/megaraid/megaraid_sas.c
@@ -1110,6 +1110,7 @@ static struct scsi_host_template megasas_template = {
        .eh_timed_out = megasas_reset_timer,
        .bios_param = megasas_bios_param,
        .use_clustering = ENABLE_CLUSTERING,
+       .use_sg_chaining = ENABLE_SG_CHAINING,
 };
 
 /**
diff --git a/drivers/scsi/mesh.c b/drivers/scsi/mesh.c
index 651d09b..7470ff3 100644
--- a/drivers/scsi/mesh.c
+++ b/drivers/scsi/mesh.c
@@ -1843,6 +1843,7 @@ static struct scsi_host_template mesh_template = {
        .sg_tablesize                   = SG_ALL,
        .cmd_per_lun                    = 2,
        .use_clustering                 = DISABLE_CLUSTERING,
+       .use_sg_chaining                = ENABLE_SG_CHAINING,
 };
 
 static int mesh_probe(struct macio_dev *mdev, const struct of_device_id *match)
diff --git a/drivers/scsi/nsp32.c b/drivers/scsi/nsp32.c
index 7fed353..28161dc 100644
--- a/drivers/scsi/nsp32.c
+++ b/drivers/scsi/nsp32.c
@@ -281,6 +281,7 @@ static struct scsi_host_template nsp32_template = {
        .cmd_per_lun                    = 1,
        .this_id                        = NSP32_HOST_SCSIID,
        .use_clustering                 = DISABLE_CLUSTERING,
+       .use_sg_chaining                = ENABLE_SG_CHAINING,
        .eh_abort_handler               = nsp32_eh_abort,
        .eh_bus_reset_handler           = nsp32_eh_bus_reset,
        .eh_host_reset_handler          = nsp32_eh_host_reset,
diff --git a/drivers/scsi/pcmcia/sym53c500_cs.c 
b/drivers/scsi/pcmcia/sym53c500_cs.c
index 961839e..190e2a7 100644
--- a/drivers/scsi/pcmcia/sym53c500_cs.c
+++ b/drivers/scsi/pcmcia/sym53c500_cs.c
@@ -694,6 +694,7 @@ static struct scsi_host_template sym53c500_driver_template 
= {
      .sg_tablesize             = 32,
      .cmd_per_lun              = 1,
      .use_clustering           = ENABLE_CLUSTERING,
+     .use_sg_chaining          = ENABLE_SG_CHAINING,
      .shost_attrs              = SYM53C500_shost_attrs
 };
 
diff --git a/drivers/scsi/qla2xxx/qla_os.c b/drivers/scsi/qla2xxx/qla_os.c
index 93c0c7e..dd61832 100644
--- a/drivers/scsi/qla2xxx/qla_os.c
+++ b/drivers/scsi/qla2xxx/qla_os.c
@@ -132,6 +132,7 @@ struct scsi_host_template qla2x00_driver_template = {
        .this_id                = -1,
        .cmd_per_lun            = 3,
        .use_clustering         = ENABLE_CLUSTERING,
+       .use_sg_chaining        = ENABLE_SG_CHAINING,
        .sg_tablesize           = SG_ALL,
 
        /*
@@ -163,6 +164,7 @@ struct scsi_host_template qla24xx_driver_template = {
        .this_id                = -1,
        .cmd_per_lun            = 3,
        .use_clustering         = ENABLE_CLUSTERING,
+       .use_sg_chaining        = ENABLE_SG_CHAINING,
        .sg_tablesize           = SG_ALL,
 
        .max_sectors            = 0xFFFF,
diff --git a/drivers/scsi/qla4xxx/ql4_os.c b/drivers/scsi/qla4xxx/ql4_os.c
index b1d565c..03b68d4 100644
--- a/drivers/scsi/qla4xxx/ql4_os.c
+++ b/drivers/scsi/qla4xxx/ql4_os.c
@@ -94,6 +94,7 @@ static struct scsi_host_template qla4xxx_driver_template = {
        .this_id                = -1,
        .cmd_per_lun            = 3,
        .use_clustering         = ENABLE_CLUSTERING,
+       .use_sg_chaining        = ENABLE_SG_CHAINING,
        .sg_tablesize           = SG_ALL,
 
        .max_sectors            = 0xFFFF,
diff --git a/drivers/scsi/qlogicfas.c b/drivers/scsi/qlogicfas.c
index 94baca8..2268ca1 100644
--- a/drivers/scsi/qlogicfas.c
+++ b/drivers/scsi/qlogicfas.c
@@ -197,6 +197,7 @@ static struct scsi_host_template qlogicfas_driver_template 
= {
        .sg_tablesize           = SG_ALL,
        .cmd_per_lun            = 1,
        .use_clustering         = DISABLE_CLUSTERING,
+       .use_sg_chaining        = ENABLE_SG_CHAINING,
 };
 
 static __init int qlogicfas_init(void)
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index f05f006..7eb9972 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1674,7 +1674,10 @@ struct request_queue *__scsi_alloc_queue(struct 
Scsi_Host *shost,
         * converted, so better keep it safe.
         */
 #ifdef ARCH_HAS_SG_CHAIN
-       blk_queue_max_phys_segments(q, SCSI_MAX_SG_CHAIN_SEGMENTS);
+       if (shost->use_sg_chaining)
+               blk_queue_max_phys_segments(q, SCSI_MAX_SG_CHAIN_SEGMENTS);
+       else
+               blk_queue_max_phys_segments(q, SCSI_MAX_SG_SEGMENTS);
 #else
        blk_queue_max_phys_segments(q, SCSI_MAX_SG_SEGMENTS);
 #endif
diff --git a/drivers/scsi/stex.c b/drivers/scsi/stex.c
index 72f6d80..e3fab3a 100644
--- a/drivers/scsi/stex.c
+++ b/drivers/scsi/stex.c
@@ -1123,6 +1123,7 @@ static struct scsi_host_template driver_template = {
        .this_id                        = -1,
        .sg_tablesize                   = ST_MAX_SG,
        .cmd_per_lun                    = ST_CMD_PER_LUN,
+       .use_sg_chaining                = ENABLE_SG_CHAINING,
 };
 
 static int stex_set_dma_mask(struct pci_dev * pdev)
diff --git a/drivers/scsi/sym53c416.c b/drivers/scsi/sym53c416.c
index 92bfaea..8befab7 100644
--- a/drivers/scsi/sym53c416.c
+++ b/drivers/scsi/sym53c416.c
@@ -854,5 +854,6 @@ static struct scsi_host_template driver_template = {
        .cmd_per_lun =          1,
        .unchecked_isa_dma =    1,
        .use_clustering =       ENABLE_CLUSTERING,
+       .use_sg_chaining =      ENABLE_SG_CHAINING,
 };
 #include "scsi_module.c"
diff --git a/drivers/scsi/sym53c8xx_2/sym_glue.c 
b/drivers/scsi/sym53c8xx_2/sym_glue.c
index 3db2232..db03c4c 100644
--- a/drivers/scsi/sym53c8xx_2/sym_glue.c
+++ b/drivers/scsi/sym53c8xx_2/sym_glue.c
@@ -1808,6 +1808,7 @@ static struct scsi_host_template sym2_template = {
        .eh_host_reset_handler  = sym53c8xx_eh_host_reset_handler,
        .this_id                = 7,
        .use_clustering         = ENABLE_CLUSTERING,
+       .use_sg_chaining        = ENABLE_SG_CHAINING,
        .max_sectors            = 0xFFFF,
 #ifdef SYM_LINUX_PROC_INFO_SUPPORT
        .proc_info              = sym53c8xx_proc_info,
diff --git a/drivers/scsi/u14-34f.c b/drivers/scsi/u14-34f.c
index 9e8232a..a0d9ef4 100644
--- a/drivers/scsi/u14-34f.c
+++ b/drivers/scsi/u14-34f.c
@@ -451,6 +451,7 @@ static struct scsi_host_template driver_template = {
                 .this_id                 = 7,
                 .unchecked_isa_dma       = 1,
                 .use_clustering          = ENABLE_CLUSTERING
+                .use_sg_chaining         = ENABLE_SG_CHAINING,
                 };
 
 #if !defined(__BIG_ENDIAN_BITFIELD) && !defined(__LITTLE_ENDIAN_BITFIELD)
diff --git a/drivers/scsi/ultrastor.c b/drivers/scsi/ultrastor.c
index c08235d..ea72bbe 100644
--- a/drivers/scsi/ultrastor.c
+++ b/drivers/scsi/ultrastor.c
@@ -1197,5 +1197,6 @@ static struct scsi_host_template driver_template = {
        .cmd_per_lun       = ULTRASTOR_MAX_CMDS_PER_LUN,
        .unchecked_isa_dma = 1,
        .use_clustering    = ENABLE_CLUSTERING,
+       .use_sg_chaining   = ENABLE_SG_CHAINING,
 };
 #include "scsi_module.c"
diff --git a/drivers/scsi/wd7000.c b/drivers/scsi/wd7000.c
index d6fd425..255c611 100644
--- a/drivers/scsi/wd7000.c
+++ b/drivers/scsi/wd7000.c
@@ -1671,6 +1671,7 @@ static struct scsi_host_template driver_template = {
        .cmd_per_lun            = 1,
        .unchecked_isa_dma      = 1,
        .use_clustering         = ENABLE_CLUSTERING,
+       .use_sg_chaining        = ENABLE_SG_CHAINING,
 };
 
 #include "scsi_module.c"
diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h
index 3b8a6a8..cbb5217 100644
--- a/include/scsi/scsi_host.h
+++ b/include/scsi/scsi_host.h
@@ -36,6 +36,9 @@ struct blk_queue_tags;
 #define DISABLE_CLUSTERING 0
 #define ENABLE_CLUSTERING 1
 
+#define DISABLE_SG_CHAINING 0
+#define ENABLE_SG_CHAINING 1
+
 enum scsi_eh_timer_return {
        EH_NOT_HANDLED,
        EH_HANDLED,
@@ -438,6 +441,15 @@ struct scsi_host_template {
        unsigned ordered_tag:1;
 
        /*
+        * true if the low-level driver can support sg chaining. this
+        * will be removed eventually when all the drivers are
+        * converted to support sg chaining.
+        *
+        * Status: OBSOLETE
+        */
+       unsigned use_sg_chaining:1;
+
+       /*
         * Countdown for host blocking with no commands outstanding
         */
        unsigned int max_host_blocked;
@@ -580,6 +592,7 @@ struct Scsi_Host {
        unsigned unchecked_isa_dma:1;
        unsigned use_clustering:1;
        unsigned use_blk_tcq:1;
+       unsigned use_sg_chaining:1;
 
        /*
         * Host has requested that no further requests come through for the
-- 
1.5.2.4

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