remove the "clustering" flag V2

remove the "clustering" flag V2

[Christoph Hellwig]

The block layer has been carrying around a magic clustering flag,
which is an artefact of prehistoric scsi layer design decisions.

Originally it controller if any segment merging happens at all for a
given LLLD, but with merging moving to the block layer and massively
more complex now it now essentically means that no segment shall be
larger than a page, and no segment shall cross a page boundary if
clustering is not enabled.  Unfortunately the SCSI layer historically
defaults to disabled clustering, but fortunately most drivers actually
enable it, and very few drivers do not set an explicit flag.

So this series first flips the default to be sensible, and then replaces
the magic flag with setting an explicit dma boundary and max segment
size to reuse the existing mechanisms.  It also fixes up a few drivers
where the no clustering setting was clearly bogus, although we can
probably lift these limits for others as well eventually.

Changes since V1:
 - split a patch into two
 - collected a few acks
 - fixed a changelog typo
 - only set the segment boundary, the max segment size is redundant
 - don't set dma_boundary twice in two drivers

[PATCH 01/10] scsi: make sure all drivers set the use_clustering flag

[Christoph Hellwig]

A few drivers were not setting the use_clustering flag at all and thus
default to disable.  Fix them up to explicitly set this field in
preparation for additional cleanups.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 drivers/scsi/mvumi.c      | 1 +
 drivers/scsi/myrb.c       | 1 +
 drivers/scsi/myrs.c       | 1 +
 drivers/scsi/stex.c       | 1 +
 drivers/scsi/ufs/ufshcd.c | 1 +
 drivers/usb/storage/uas.c | 1 +
 6 files changed, 6 insertions(+)

diff --git a/drivers/scsi/mvumi.c b/drivers/scsi/mvumi.c
index 3d2d026d1ccf..d0c3f867fc58 100644
--- a/drivers/scsi/mvumi.c
+++ b/drivers/scsi/mvumi.c
@@ -2197,6 +2197,7 @@ static struct scsi_host_template mvumi_template = {
 	.eh_timed_out = mvumi_timed_out,
 	.eh_host_reset_handler = mvumi_host_reset,
 	.bios_param = mvumi_bios_param,
+	.use_clustering = DISABLE_CLUSTERING,
 	.this_id = -1,
 };
 
diff --git a/drivers/scsi/myrb.c b/drivers/scsi/myrb.c
index aeb282f617c5..f1abe38e3b3a 100644
--- a/drivers/scsi/myrb.c
+++ b/drivers/scsi/myrb.c
@@ -2236,6 +2236,7 @@ struct scsi_host_template myrb_template = {
 	.shost_attrs		= myrb_shost_attrs,
 	.sdev_attrs		= myrb_sdev_attrs,
 	.this_id		= -1,
+	.use_clustering		= DISABLE_CLUSTERING,
 };
 
 /**
diff --git a/drivers/scsi/myrs.c b/drivers/scsi/myrs.c
index 0264a2e2bc19..f47b36382afa 100644
--- a/drivers/scsi/myrs.c
+++ b/drivers/scsi/myrs.c
@@ -1929,6 +1929,7 @@ struct scsi_host_template myrs_template = {
 	.shost_attrs		= myrs_shost_attrs,
 	.sdev_attrs		= myrs_sdev_attrs,
 	.this_id		= -1,
+	.use_clustering		= DISABLE_CLUSTERING,
 };
 
 static struct myrs_hba *myrs_alloc_host(struct pci_dev *pdev,
diff --git a/drivers/scsi/stex.c b/drivers/scsi/stex.c
index 95f370ad05e0..af9078320d4b 100644
--- a/drivers/scsi/stex.c
+++ b/drivers/scsi/stex.c
@@ -1489,6 +1489,7 @@ static struct scsi_host_template driver_template = {
 	.eh_abort_handler		= stex_abort,
 	.eh_host_reset_handler		= stex_reset,
 	.this_id			= -1,
+	.use_clustering			= DISABLE_CLUSTERING,
 };
 
 static struct pci_device_id stex_pci_tbl[] = {
diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index 751027d73cf3..e5800da0053d 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -6982,6 +6982,7 @@ static struct scsi_host_template ufshcd_driver_template = {
 	.max_host_blocked	= 1,
 	.track_queue_depth	= 1,
 	.sdev_groups		= ufshcd_driver_groups,
+	.use_clustering		= DISABLE_CLUSTERING,
 };
 
 static int ufshcd_config_vreg_load(struct device *dev, struct ufs_vreg *vreg,
diff --git a/drivers/usb/storage/uas.c b/drivers/usb/storage/uas.c
index 1f7b401c4d04..6c75a0a50b3a 100644
--- a/drivers/usb/storage/uas.c
+++ b/drivers/usb/storage/uas.c
@@ -879,6 +879,7 @@ static struct scsi_host_template uas_host_template = {
 	.this_id = -1,
 	.sg_tablesize = SG_NONE,
 	.skip_settle_delay = 1,
+	.use_clustering = DISABLE_CLUSTERING,
 };
 
 #define UNUSUAL_DEV(id_vendor, id_product, bcdDeviceMin, bcdDeviceMax, \
-- 
2.19.2

[PATCH 02/10] scsi: flip the default on use_clustering

[Christoph Hellwig]

Most SCSI drivers want to enable "clustering", that is merging of
segments so that they might span more than a single page.  Remove the
ENABLE_CLUSTERING define, and require drivers to explicitly set
DISABLE_CLUSTERING to disable this feature.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 drivers/firewire/sbp2.c                         | 1 -
 drivers/infiniband/ulp/iser/iscsi_iser.c        | 1 -
 drivers/infiniband/ulp/srp/ib_srp.c             | 1 -
 drivers/message/fusion/mptfc.c                  | 1 -
 drivers/message/fusion/mptsas.c                 | 1 -
 drivers/message/fusion/mptspi.c                 | 1 -
 drivers/s390/scsi/zfcp_scsi.c                   | 1 -
 drivers/scsi/3w-9xxx.c                          | 1 -
 drivers/scsi/3w-sas.c                           | 1 -
 drivers/scsi/3w-xxxx.c                          | 1 -
 drivers/scsi/53c700.c                           | 1 -
 drivers/scsi/BusLogic.c                         | 1 -
 drivers/scsi/a100u2w.c                          | 1 -
 drivers/scsi/a3000.c                            | 1 -
 drivers/scsi/aacraid/linit.c                    | 1 -
 drivers/scsi/advansys.c                         | 8 --------
 drivers/scsi/aha1542.c                          | 1 -
 drivers/scsi/aha1740.c                          | 1 -
 drivers/scsi/aic7xxx/aic79xx_osm.c              | 1 -
 drivers/scsi/aic7xxx/aic7xxx_osm.c              | 1 -
 drivers/scsi/aic94xx/aic94xx_init.c             | 1 -
 drivers/scsi/arcmsr/arcmsr_hba.c                | 1 -
 drivers/scsi/arm/powertec.c                     | 1 -
 drivers/scsi/atp870u.c                          | 1 -
 drivers/scsi/be2iscsi/be_main.c                 | 1 -
 drivers/scsi/bfa/bfad_im.c                      | 2 --
 drivers/scsi/bnx2fc/bnx2fc_fcoe.c               | 1 -
 drivers/scsi/bnx2i/bnx2i_iscsi.c                | 1 -
 drivers/scsi/csiostor/csio_scsi.c               | 2 --
 drivers/scsi/cxlflash/main.c                    | 1 -
 drivers/scsi/dpt_i2o.c                          | 1 -
 drivers/scsi/esas2r/esas2r_main.c               | 1 -
 drivers/scsi/esp_scsi.c                         | 1 -
 drivers/scsi/fcoe/fcoe.c                        | 1 -
 drivers/scsi/fnic/fnic_main.c                   | 1 -
 drivers/scsi/gdth.c                             | 1 -
 drivers/scsi/hisi_sas/hisi_sas_v1_hw.c          | 1 -
 drivers/scsi/hisi_sas/hisi_sas_v2_hw.c          | 1 -
 drivers/scsi/hisi_sas/hisi_sas_v3_hw.c          | 1 -
 drivers/scsi/hpsa.c                             | 1 -
 drivers/scsi/hptiop.c                           | 1 -
 drivers/scsi/ibmvscsi/ibmvfc.c                  | 1 -
 drivers/scsi/ibmvscsi/ibmvscsi.c                | 1 -
 drivers/scsi/imm.c                              | 1 -
 drivers/scsi/initio.c                           | 1 -
 drivers/scsi/ipr.c                              | 1 -
 drivers/scsi/ips.c                              | 1 -
 drivers/scsi/isci/init.c                        | 1 -
 drivers/scsi/lpfc/lpfc_scsi.c                   | 4 ----
 drivers/scsi/megaraid.c                         | 1 -
 drivers/scsi/megaraid/megaraid_mbox.c           | 1 -
 drivers/scsi/megaraid/megaraid_sas_base.c       | 1 -
 drivers/scsi/mpt3sas/mpt3sas_scsih.c            | 2 --
 drivers/scsi/mvme147.c                          | 1 -
 drivers/scsi/mvsas/mv_init.c                    | 1 -
 drivers/scsi/ncr53c8xx.c                        | 1 -
 drivers/scsi/pcmcia/sym53c500_cs.c              | 1 -
 drivers/scsi/pm8001/pm8001_init.c               | 1 -
 drivers/scsi/pmcraid.c                          | 1 -
 drivers/scsi/ppa.c                              | 1 -
 drivers/scsi/ps3rom.c                           | 1 -
 drivers/scsi/qedf/qedf_main.c                   | 1 -
 drivers/scsi/qedi/qedi_iscsi.c                  | 1 -
 drivers/scsi/qla1280.c                          | 1 -
 drivers/scsi/qla2xxx/qla_os.c                   | 1 -
 drivers/scsi/qla4xxx/ql4_os.c                   | 1 -
 drivers/scsi/qlogicpti.c                        | 1 -
 drivers/scsi/scsi_debug.c                       | 5 ++---
 drivers/scsi/scsi_lib.c                         | 2 +-
 drivers/scsi/smartpqi/smartpqi_init.c           | 1 -
 drivers/scsi/snic/snic_main.c                   | 1 -
 drivers/scsi/storvsc_drv.c                      | 1 -
 drivers/scsi/sym53c8xx_2/sym_glue.c             | 1 -
 drivers/scsi/virtio_scsi.c                      | 1 -
 drivers/scsi/vmw_pvscsi.c                       | 1 -
 drivers/scsi/wd719x.c                           | 1 -
 drivers/staging/rts5208/rtsx.c                  | 6 ------
 drivers/staging/unisys/visorhba/visorhba_main.c | 1 -
 drivers/usb/image/microtek.c                    | 1 -
 drivers/usb/storage/scsiglue.c                  | 7 -------
 include/linux/libata.h                          | 2 --
 include/scsi/scsi_host.h                        | 3 +--
 82 files changed, 4 insertions(+), 110 deletions(-)

diff --git a/drivers/firewire/sbp2.c b/drivers/firewire/sbp2.c
index 6bac03999fd4..09b845e90114 100644
--- a/drivers/firewire/sbp2.c
+++ b/drivers/firewire/sbp2.c
@@ -1610,7 +1610,6 @@ static struct scsi_host_template scsi_driver_template = {
 	.eh_abort_handler	= sbp2_scsi_abort,
 	.this_id		= -1,
 	.sg_tablesize		= SG_ALL,
-	.use_clustering		= ENABLE_CLUSTERING,
 	.can_queue		= 1,
 	.sdev_attrs		= sbp2_scsi_sysfs_attrs,
 };
diff --git a/drivers/infiniband/ulp/iser/iscsi_iser.c b/drivers/infiniband/ulp/iser/iscsi_iser.c
index 3fecd87c9f2b..8c707accd148 100644
--- a/drivers/infiniband/ulp/iser/iscsi_iser.c
+++ b/drivers/infiniband/ulp/iser/iscsi_iser.c
@@ -997,7 +997,6 @@ static struct scsi_host_template iscsi_iser_sht = {
 	.eh_device_reset_handler= iscsi_eh_device_reset,
 	.eh_target_reset_handler = iscsi_eh_recover_target,
 	.target_alloc		= iscsi_target_alloc,
-	.use_clustering         = ENABLE_CLUSTERING,
 	.slave_alloc            = iscsi_iser_slave_alloc,
 	.proc_name              = "iscsi_iser",
 	.this_id                = -1,
diff --git a/drivers/infiniband/ulp/srp/ib_srp.c b/drivers/infiniband/ulp/srp/ib_srp.c
index eed0eb3bb04c..d27fe970ceba 100644
--- a/drivers/infiniband/ulp/srp/ib_srp.c
+++ b/drivers/infiniband/ulp/srp/ib_srp.c
@@ -3215,7 +3215,6 @@ static struct scsi_host_template srp_template = {
 	.can_queue			= SRP_DEFAULT_CMD_SQ_SIZE,
 	.this_id			= -1,
 	.cmd_per_lun			= SRP_DEFAULT_CMD_SQ_SIZE,
-	.use_clustering			= ENABLE_CLUSTERING,
 	.shost_attrs			= srp_host_attrs,
 	.track_queue_depth		= 1,
 };
diff --git a/drivers/message/fusion/mptfc.c b/drivers/message/fusion/mptfc.c
index b15fdc626fb8..4314a3352b96 100644
--- a/drivers/message/fusion/mptfc.c
+++ b/drivers/message/fusion/mptfc.c
@@ -129,7 +129,6 @@ static struct scsi_host_template mptfc_driver_template = {
 	.sg_tablesize			= MPT_SCSI_SG_DEPTH,
 	.max_sectors			= 8192,
 	.cmd_per_lun			= 7,
-	.use_clustering			= ENABLE_CLUSTERING,
 	.shost_attrs			= mptscsih_host_attrs,
 };
 
diff --git a/drivers/message/fusion/mptsas.c b/drivers/message/fusion/mptsas.c
index 9b404fc69c90..612cb5bc1333 100644
--- a/drivers/message/fusion/mptsas.c
+++ b/drivers/message/fusion/mptsas.c
@@ -1992,7 +1992,6 @@ static struct scsi_host_template mptsas_driver_template = {
 	.sg_tablesize			= MPT_SCSI_SG_DEPTH,
 	.max_sectors			= 8192,
 	.cmd_per_lun			= 7,
-	.use_clustering			= ENABLE_CLUSTERING,
 	.shost_attrs			= mptscsih_host_attrs,
 	.no_write_same			= 1,
 };
diff --git a/drivers/message/fusion/mptspi.c b/drivers/message/fusion/mptspi.c
index 9a336a161d9f..7172b0b16bdd 100644
--- a/drivers/message/fusion/mptspi.c
+++ b/drivers/message/fusion/mptspi.c
@@ -848,7 +848,6 @@ static struct scsi_host_template mptspi_driver_template = {
 	.sg_tablesize			= MPT_SCSI_SG_DEPTH,
 	.max_sectors			= 8192,
 	.cmd_per_lun			= 7,
-	.use_clustering			= ENABLE_CLUSTERING,
 	.shost_attrs			= mptscsih_host_attrs,
 };
 
diff --git a/drivers/s390/scsi/zfcp_scsi.c b/drivers/s390/scsi/zfcp_scsi.c
index a8b53ed61c1e..00acc7144bbc 100644
--- a/drivers/s390/scsi/zfcp_scsi.c
+++ b/drivers/s390/scsi/zfcp_scsi.c
@@ -429,7 +429,6 @@ static struct scsi_host_template zfcp_scsi_host_template = {
 				     * ZFCP_QDIO_MAX_SBALS_PER_REQ) - 2) * 8,
 				   /* GCD, adjusted later */
 	.dma_boundary		 = ZFCP_QDIO_SBALE_LEN - 1,
-	.use_clustering		 = 1,
 	.shost_attrs		 = zfcp_sysfs_shost_attrs,
 	.sdev_attrs		 = zfcp_sysfs_sdev_attrs,
 	.track_queue_depth	 = 1,
diff --git a/drivers/scsi/3w-9xxx.c b/drivers/scsi/3w-9xxx.c
index 2d655a97b959..a3c20e3a8b7c 100644
--- a/drivers/scsi/3w-9xxx.c
+++ b/drivers/scsi/3w-9xxx.c
@@ -1998,7 +1998,6 @@ static struct scsi_host_template driver_template = {
 	.sg_tablesize		= TW_APACHE_MAX_SGL_LENGTH,
 	.max_sectors		= TW_MAX_SECTORS,
 	.cmd_per_lun		= TW_MAX_CMDS_PER_LUN,
-	.use_clustering		= ENABLE_CLUSTERING,
 	.shost_attrs		= twa_host_attrs,
 	.emulated		= 1,
 	.no_write_same		= 1,
diff --git a/drivers/scsi/3w-sas.c b/drivers/scsi/3w-sas.c
index 480cf82700e9..e8f5f7c63190 100644
--- a/drivers/scsi/3w-sas.c
+++ b/drivers/scsi/3w-sas.c
@@ -1550,7 +1550,6 @@ static struct scsi_host_template driver_template = {
 	.sg_tablesize		= TW_LIBERATOR_MAX_SGL_LENGTH,
 	.max_sectors		= TW_MAX_SECTORS,
 	.cmd_per_lun		= TW_MAX_CMDS_PER_LUN,
-	.use_clustering		= ENABLE_CLUSTERING,
 	.shost_attrs		= twl_host_attrs,
 	.emulated		= 1,
 	.no_write_same		= 1,
diff --git a/drivers/scsi/3w-xxxx.c b/drivers/scsi/3w-xxxx.c
index a58257645e94..4938ba8adc86 100644
--- a/drivers/scsi/3w-xxxx.c
+++ b/drivers/scsi/3w-xxxx.c
@@ -2247,7 +2247,6 @@ static struct scsi_host_template driver_template = {
 	.sg_tablesize		= TW_MAX_SGL_LENGTH,
 	.max_sectors		= TW_MAX_SECTORS,
 	.cmd_per_lun		= TW_MAX_CMDS_PER_LUN,	
-	.use_clustering		= ENABLE_CLUSTERING,
 	.shost_attrs		= tw_host_attrs,
 	.emulated		= 1,
 	.no_write_same		= 1,
diff --git a/drivers/scsi/53c700.c b/drivers/scsi/53c700.c
index 6be77b3aa8a5..128d658d472a 100644
--- a/drivers/scsi/53c700.c
+++ b/drivers/scsi/53c700.c
@@ -318,7 +318,6 @@ NCR_700_detect(struct scsi_host_template *tpnt,
 	tpnt->can_queue = NCR_700_COMMAND_SLOTS_PER_HOST;
 	tpnt->sg_tablesize = NCR_700_SG_SEGMENTS;
 	tpnt->cmd_per_lun = NCR_700_CMD_PER_LUN;
-	tpnt->use_clustering = ENABLE_CLUSTERING;
 	tpnt->slave_configure = NCR_700_slave_configure;
 	tpnt->slave_destroy = NCR_700_slave_destroy;
 	tpnt->slave_alloc = NCR_700_slave_alloc;
diff --git a/drivers/scsi/BusLogic.c b/drivers/scsi/BusLogic.c
index 717eef3ee893..e41e51f1da71 100644
--- a/drivers/scsi/BusLogic.c
+++ b/drivers/scsi/BusLogic.c
@@ -3858,7 +3858,6 @@ static struct scsi_host_template blogic_template = {
 #endif
 	.unchecked_isa_dma = 1,
 	.max_sectors = 128,
-	.use_clustering = ENABLE_CLUSTERING,
 };
 
 /*
diff --git a/drivers/scsi/a100u2w.c b/drivers/scsi/a100u2w.c
index 00072ed9540b..ff53fd0d12f2 100644
--- a/drivers/scsi/a100u2w.c
+++ b/drivers/scsi/a100u2w.c
@@ -1078,7 +1078,6 @@ static struct scsi_host_template inia100_template = {
 	.can_queue		= 1,
 	.this_id		= 1,
 	.sg_tablesize		= SG_ALL,
-	.use_clustering		= ENABLE_CLUSTERING,
 };
 
 static int inia100_probe_one(struct pci_dev *pdev,
diff --git a/drivers/scsi/a3000.c b/drivers/scsi/a3000.c
index 2427a8541247..dcf435f312dd 100644
--- a/drivers/scsi/a3000.c
+++ b/drivers/scsi/a3000.c
@@ -175,7 +175,6 @@ static struct scsi_host_template amiga_a3000_scsi_template = {
 	.this_id		= 7,
 	.sg_tablesize		= SG_ALL,
 	.cmd_per_lun		= CMD_PER_LUN,
-	.use_clustering		= ENABLE_CLUSTERING
 };
 
 static int __init amiga_a3000_scsi_probe(struct platform_device *pdev)
diff --git a/drivers/scsi/aacraid/linit.c b/drivers/scsi/aacraid/linit.c
index 1c5d54c2f031..634ddb90e7aa 100644
--- a/drivers/scsi/aacraid/linit.c
+++ b/drivers/scsi/aacraid/linit.c
@@ -1540,7 +1540,6 @@ static struct scsi_host_template aac_driver_template = {
 #else
 	.cmd_per_lun			= AAC_NUM_IO_FIB,
 #endif
-	.use_clustering			= ENABLE_CLUSTERING,
 	.emulated			= 1,
 	.no_write_same			= 1,
 };
diff --git a/drivers/scsi/advansys.c b/drivers/scsi/advansys.c
index 223ef6f4e258..95b4793c33f4 100644
--- a/drivers/scsi/advansys.c
+++ b/drivers/scsi/advansys.c
@@ -10808,14 +10808,6 @@ static struct scsi_host_template advansys_template = {
 	 * for non-ISA adapters.
 	 */
 	.unchecked_isa_dma = true,
-	/*
-	 * All adapters controlled by this driver are capable of large
-	 * scatter-gather lists. According to the mid-level SCSI documentation
-	 * this obviates any performance gain provided by setting
-	 * 'use_clustering'. But empirically while CPU utilization is increased
-	 * by enabling clustering, I/O throughput increases as well.
-	 */
-	.use_clustering = ENABLE_CLUSTERING,
 };
 
 static int advansys_wide_init_chip(struct Scsi_Host *shost)
diff --git a/drivers/scsi/aha1542.c b/drivers/scsi/aha1542.c
index afb693d7b44f..ba7a5725be04 100644
--- a/drivers/scsi/aha1542.c
+++ b/drivers/scsi/aha1542.c
@@ -1011,7 +1011,6 @@ static struct scsi_host_template driver_template = {
 	.this_id		= 7,
 	.sg_tablesize		= 16,
 	.unchecked_isa_dma	= 1, 
-	.use_clustering		= ENABLE_CLUSTERING,
 };
 
 static int aha1542_isa_match(struct device *pdev, unsigned int ndev)
diff --git a/drivers/scsi/aha1740.c b/drivers/scsi/aha1740.c
index 786bf7f32c64..da4150c17781 100644
--- a/drivers/scsi/aha1740.c
+++ b/drivers/scsi/aha1740.c
@@ -545,7 +545,6 @@ static struct scsi_host_template aha1740_template = {
 	.can_queue        = AHA1740_ECBS,
 	.this_id          = 7,
 	.sg_tablesize     = AHA1740_SCATTER,
-	.use_clustering   = ENABLE_CLUSTERING,
 	.eh_abort_handler = aha1740_eh_abort_handler,
 };
 
diff --git a/drivers/scsi/aic7xxx/aic79xx_osm.c b/drivers/scsi/aic7xxx/aic79xx_osm.c
index 2588b8f84ba0..57992519384e 100644
--- a/drivers/scsi/aic7xxx/aic79xx_osm.c
+++ b/drivers/scsi/aic7xxx/aic79xx_osm.c
@@ -920,7 +920,6 @@ struct scsi_host_template aic79xx_driver_template = {
 	.this_id		= -1,
 	.max_sectors		= 8192,
 	.cmd_per_lun		= 2,
-	.use_clustering		= ENABLE_CLUSTERING,
 	.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 c6be3aeb302b..3c9c17450bb3 100644
--- a/drivers/scsi/aic7xxx/aic7xxx_osm.c
+++ b/drivers/scsi/aic7xxx/aic7xxx_osm.c
@@ -807,7 +807,6 @@ struct scsi_host_template aic7xxx_driver_template = {
 	.this_id		= -1,
 	.max_sectors		= 8192,
 	.cmd_per_lun		= 2,
-	.use_clustering		= ENABLE_CLUSTERING,
 	.slave_alloc		= ahc_linux_slave_alloc,
 	.slave_configure	= ahc_linux_slave_configure,
 	.target_alloc		= ahc_linux_target_alloc,
diff --git a/drivers/scsi/aic94xx/aic94xx_init.c b/drivers/scsi/aic94xx/aic94xx_init.c
index 41c4d8abdd4a..f83f79b07b50 100644
--- a/drivers/scsi/aic94xx/aic94xx_init.c
+++ b/drivers/scsi/aic94xx/aic94xx_init.c
@@ -68,7 +68,6 @@ static struct scsi_host_template aic94xx_sht = {
 	.this_id		= -1,
 	.sg_tablesize		= SG_ALL,
 	.max_sectors		= SCSI_DEFAULT_MAX_SECTORS,
-	.use_clustering		= ENABLE_CLUSTERING,
 	.eh_device_reset_handler	= sas_eh_device_reset_handler,
 	.eh_target_reset_handler	= sas_eh_target_reset_handler,
 	.target_destroy		= sas_target_destroy,
diff --git a/drivers/scsi/arcmsr/arcmsr_hba.c b/drivers/scsi/arcmsr/arcmsr_hba.c
index 11e8e6df50b1..0f6751b0a633 100644
--- a/drivers/scsi/arcmsr/arcmsr_hba.c
+++ b/drivers/scsi/arcmsr/arcmsr_hba.c
@@ -156,7 +156,6 @@ static struct scsi_host_template arcmsr_scsi_host_template = {
 	.sg_tablesize	        = ARCMSR_DEFAULT_SG_ENTRIES,
 	.max_sectors		= ARCMSR_MAX_XFER_SECTORS_C,
 	.cmd_per_lun		= ARCMSR_DEFAULT_CMD_PERLUN,
-	.use_clustering		= ENABLE_CLUSTERING,
 	.shost_attrs		= arcmsr_host_attrs,
 	.no_write_same		= 1,
 };
diff --git a/drivers/scsi/arm/powertec.c b/drivers/scsi/arm/powertec.c
index 79aa88911b7f..759f95ba993c 100644
--- a/drivers/scsi/arm/powertec.c
+++ b/drivers/scsi/arm/powertec.c
@@ -294,7 +294,6 @@ static struct scsi_host_template powertecscsi_template = {
 	.sg_tablesize			= SG_MAX_SEGMENTS,
 	.dma_boundary			= IOMD_DMA_BOUNDARY,
 	.cmd_per_lun			= 2,
-	.use_clustering			= ENABLE_CLUSTERING,
 	.proc_name			= "powertec",
 };
 
diff --git a/drivers/scsi/atp870u.c b/drivers/scsi/atp870u.c
index 802d15018ec0..1267200380f8 100644
--- a/drivers/scsi/atp870u.c
+++ b/drivers/scsi/atp870u.c
@@ -1681,7 +1681,6 @@ static struct scsi_host_template atp870u_template = {
      .can_queue         	= qcnt			/* can_queue */,
      .this_id           	= 7			/* SCSI ID */,
      .sg_tablesize      	= ATP870U_SCATTER	/*SG_ALL*/ /*SG_NONE*/,
-     .use_clustering    	= ENABLE_CLUSTERING,
      .max_sectors		= ATP870U_MAX_SECTORS,
 };
 
diff --git a/drivers/scsi/be2iscsi/be_main.c b/drivers/scsi/be2iscsi/be_main.c
index effb6fc95af4..c4108b17d5ab 100644
--- a/drivers/scsi/be2iscsi/be_main.c
+++ b/drivers/scsi/be2iscsi/be_main.c
@@ -405,7 +405,6 @@ static struct scsi_host_template beiscsi_sht = {
 	.this_id = -1,
 	.max_sectors = BEISCSI_MAX_SECTORS,
 	.cmd_per_lun = BEISCSI_CMD_PER_LUN,
-	.use_clustering = ENABLE_CLUSTERING,
 	.vendor_id = SCSI_NL_VID_TYPE_PCI | BE_VENDOR_ID,
 	.track_queue_depth = 1,
 };
diff --git a/drivers/scsi/bfa/bfad_im.c b/drivers/scsi/bfa/bfad_im.c
index c4a33317d344..394930cbaa13 100644
--- a/drivers/scsi/bfa/bfad_im.c
+++ b/drivers/scsi/bfa/bfad_im.c
@@ -817,7 +817,6 @@ struct scsi_host_template bfad_im_scsi_host_template = {
 	.this_id = -1,
 	.sg_tablesize = BFAD_IO_MAX_SGE,
 	.cmd_per_lun = 3,
-	.use_clustering = ENABLE_CLUSTERING,
 	.shost_attrs = bfad_im_host_attrs,
 	.max_sectors = BFAD_MAX_SECTORS,
 	.vendor_id = BFA_PCI_VENDOR_ID_BROCADE,
@@ -840,7 +839,6 @@ struct scsi_host_template bfad_im_vport_template = {
 	.this_id = -1,
 	.sg_tablesize = BFAD_IO_MAX_SGE,
 	.cmd_per_lun = 3,
-	.use_clustering = ENABLE_CLUSTERING,
 	.shost_attrs = bfad_im_vport_attrs,
 	.max_sectors = BFAD_MAX_SECTORS,
 };
diff --git a/drivers/scsi/bnx2fc/bnx2fc_fcoe.c b/drivers/scsi/bnx2fc/bnx2fc_fcoe.c
index cd160f2ec75d..63f76e20e229 100644
--- a/drivers/scsi/bnx2fc/bnx2fc_fcoe.c
+++ b/drivers/scsi/bnx2fc/bnx2fc_fcoe.c
@@ -2970,7 +2970,6 @@ static struct scsi_host_template bnx2fc_shost_template = {
 	.change_queue_depth	= scsi_change_queue_depth,
 	.this_id		= -1,
 	.cmd_per_lun		= 3,
-	.use_clustering		= ENABLE_CLUSTERING,
 	.sg_tablesize		= BNX2FC_MAX_BDS_PER_CMD,
 	.max_sectors		= 1024,
 	.track_queue_depth	= 1,
diff --git a/drivers/scsi/bnx2i/bnx2i_iscsi.c b/drivers/scsi/bnx2i/bnx2i_iscsi.c
index de0a507577ef..69c75426c5eb 100644
--- a/drivers/scsi/bnx2i/bnx2i_iscsi.c
+++ b/drivers/scsi/bnx2i/bnx2i_iscsi.c
@@ -2263,7 +2263,6 @@ static struct scsi_host_template bnx2i_host_template = {
 	.max_sectors		= 127,
 	.cmd_per_lun		= 128,
 	.this_id		= -1,
-	.use_clustering		= ENABLE_CLUSTERING,
 	.sg_tablesize		= ISCSI_MAX_BDS_PER_CMD,
 	.shost_attrs		= bnx2i_dev_attributes,
 	.track_queue_depth	= 1,
diff --git a/drivers/scsi/csiostor/csio_scsi.c b/drivers/scsi/csiostor/csio_scsi.c
index 8c15b7acb4b7..e67555effdb5 100644
--- a/drivers/scsi/csiostor/csio_scsi.c
+++ b/drivers/scsi/csiostor/csio_scsi.c
@@ -2280,7 +2280,6 @@ struct scsi_host_template csio_fcoe_shost_template = {
 	.this_id		= -1,
 	.sg_tablesize		= CSIO_SCSI_MAX_SGE,
 	.cmd_per_lun		= CSIO_MAX_CMD_PER_LUN,
-	.use_clustering		= ENABLE_CLUSTERING,
 	.shost_attrs		= csio_fcoe_lport_attrs,
 	.max_sectors		= CSIO_MAX_SECTOR_SIZE,
 };
@@ -2300,7 +2299,6 @@ struct scsi_host_template csio_fcoe_shost_vport_template = {
 	.this_id		= -1,
 	.sg_tablesize		= CSIO_SCSI_MAX_SGE,
 	.cmd_per_lun		= CSIO_MAX_CMD_PER_LUN,
-	.use_clustering		= ENABLE_CLUSTERING,
 	.shost_attrs		= csio_fcoe_vport_attrs,
 	.max_sectors		= CSIO_MAX_SECTOR_SIZE,
 };
diff --git a/drivers/scsi/cxlflash/main.c b/drivers/scsi/cxlflash/main.c
index 6637116529aa..6996d15d1463 100644
--- a/drivers/scsi/cxlflash/main.c
+++ b/drivers/scsi/cxlflash/main.c
@@ -3180,7 +3180,6 @@ static struct scsi_host_template driver_template = {
 	.this_id = -1,
 	.sg_tablesize = 1,	/* No scatter gather support */
 	.max_sectors = CXLFLASH_MAX_SECTORS,
-	.use_clustering = ENABLE_CLUSTERING,
 	.shost_attrs = cxlflash_host_attrs,
 	.sdev_attrs = cxlflash_dev_attrs,
 };
diff --git a/drivers/scsi/dpt_i2o.c b/drivers/scsi/dpt_i2o.c
index d5a474d1434f..70d1a18278af 100644
--- a/drivers/scsi/dpt_i2o.c
+++ b/drivers/scsi/dpt_i2o.c
@@ -3569,7 +3569,6 @@ static struct scsi_host_template driver_template = {
 	.slave_configure	= adpt_slave_configure,
 	.can_queue		= MAX_TO_IOP_MESSAGES,
 	.this_id		= 7,
-	.use_clustering		= ENABLE_CLUSTERING,
 };
 
 static int __init adpt_init(void)
diff --git a/drivers/scsi/esas2r/esas2r_main.c b/drivers/scsi/esas2r/esas2r_main.c
index c07118617d89..64397d441bae 100644
--- a/drivers/scsi/esas2r/esas2r_main.c
+++ b/drivers/scsi/esas2r/esas2r_main.c
@@ -250,7 +250,6 @@ static struct scsi_host_template driver_template = {
 		ESAS2R_DEFAULT_CMD_PER_LUN,
 	.present			= 0,
 	.unchecked_isa_dma		= 0,
-	.use_clustering			= ENABLE_CLUSTERING,
 	.emulated			= 0,
 	.proc_name			= ESAS2R_DRVR_NAME,
 	.change_queue_depth		= scsi_change_queue_depth,
diff --git a/drivers/scsi/esp_scsi.c b/drivers/scsi/esp_scsi.c
index ac7da9db7317..465df475f753 100644
--- a/drivers/scsi/esp_scsi.c
+++ b/drivers/scsi/esp_scsi.c
@@ -2676,7 +2676,6 @@ struct scsi_host_template scsi_esp_template = {
 	.can_queue		= 7,
 	.this_id		= 7,
 	.sg_tablesize		= SG_ALL,
-	.use_clustering		= ENABLE_CLUSTERING,
 	.max_sectors		= 0xffff,
 	.skip_settle_delay	= 1,
 };
diff --git a/drivers/scsi/fcoe/fcoe.c b/drivers/scsi/fcoe/fcoe.c
index f46b312d04bc..4961ae442c87 100644
--- a/drivers/scsi/fcoe/fcoe.c
+++ b/drivers/scsi/fcoe/fcoe.c
@@ -286,7 +286,6 @@ static struct scsi_host_template fcoe_shost_template = {
 	.this_id = -1,
 	.cmd_per_lun = 3,
 	.can_queue = FCOE_MAX_OUTSTANDING_COMMANDS,
-	.use_clustering = ENABLE_CLUSTERING,
 	.sg_tablesize = SG_ALL,
 	.max_sectors = 0xffff,
 	.track_queue_depth = 1,
diff --git a/drivers/scsi/fnic/fnic_main.c b/drivers/scsi/fnic/fnic_main.c
index cc461fd7bef1..5b3534b0deda 100644
--- a/drivers/scsi/fnic/fnic_main.c
+++ b/drivers/scsi/fnic/fnic_main.c
@@ -115,7 +115,6 @@ static struct scsi_host_template fnic_host_template = {
 	.this_id = -1,
 	.cmd_per_lun = 3,
 	.can_queue = FNIC_DFLT_IO_REQ,
-	.use_clustering = ENABLE_CLUSTERING,
 	.sg_tablesize = FNIC_MAX_SG_DESC_CNT,
 	.max_sectors = 0xffff,
 	.shost_attrs = fnic_attrs,
diff --git a/drivers/scsi/gdth.c b/drivers/scsi/gdth.c
index 16709735b546..194c294f9b6c 100644
--- a/drivers/scsi/gdth.c
+++ b/drivers/scsi/gdth.c
@@ -4680,7 +4680,6 @@ static struct scsi_host_template gdth_template = {
         .sg_tablesize           = GDTH_MAXSG,
         .cmd_per_lun            = GDTH_MAXC_P_L,
         .unchecked_isa_dma      = 1,
-        .use_clustering         = ENABLE_CLUSTERING,
 	.no_write_same		= 1,
 };
 
diff --git a/drivers/scsi/hisi_sas/hisi_sas_v1_hw.c b/drivers/scsi/hisi_sas/hisi_sas_v1_hw.c
index 107f7c98ac69..95a1ddfe237c 100644
--- a/drivers/scsi/hisi_sas/hisi_sas_v1_hw.c
+++ b/drivers/scsi/hisi_sas/hisi_sas_v1_hw.c
@@ -1818,7 +1818,6 @@ static struct scsi_host_template sht_v1_hw = {
 	.this_id		= -1,
 	.sg_tablesize		= HISI_SAS_SGE_PAGE_CNT,
 	.max_sectors		= SCSI_DEFAULT_MAX_SECTORS,
-	.use_clustering		= ENABLE_CLUSTERING,
 	.eh_device_reset_handler = sas_eh_device_reset_handler,
 	.eh_target_reset_handler = sas_eh_target_reset_handler,
 	.target_destroy		= sas_target_destroy,
diff --git a/drivers/scsi/hisi_sas/hisi_sas_v2_hw.c b/drivers/scsi/hisi_sas/hisi_sas_v2_hw.c
index 8760987e5d17..90832053a935 100644
--- a/drivers/scsi/hisi_sas/hisi_sas_v2_hw.c
+++ b/drivers/scsi/hisi_sas/hisi_sas_v2_hw.c
@@ -3580,7 +3580,6 @@ static struct scsi_host_template sht_v2_hw = {
 	.this_id		= -1,
 	.sg_tablesize		= HISI_SAS_SGE_PAGE_CNT,
 	.max_sectors		= SCSI_DEFAULT_MAX_SECTORS,
-	.use_clustering		= ENABLE_CLUSTERING,
 	.eh_device_reset_handler = sas_eh_device_reset_handler,
 	.eh_target_reset_handler = sas_eh_target_reset_handler,
 	.target_destroy		= sas_target_destroy,
diff --git a/drivers/scsi/hisi_sas/hisi_sas_v3_hw.c b/drivers/scsi/hisi_sas/hisi_sas_v3_hw.c
index 44781e3786a2..6acca892d95f 100644
--- a/drivers/scsi/hisi_sas/hisi_sas_v3_hw.c
+++ b/drivers/scsi/hisi_sas/hisi_sas_v3_hw.c
@@ -2233,7 +2233,6 @@ static struct scsi_host_template sht_v3_hw = {
 	.this_id		= -1,
 	.sg_tablesize		= HISI_SAS_SGE_PAGE_CNT,
 	.max_sectors		= SCSI_DEFAULT_MAX_SECTORS,
-	.use_clustering		= ENABLE_CLUSTERING,
 	.eh_device_reset_handler = sas_eh_device_reset_handler,
 	.eh_target_reset_handler = sas_eh_target_reset_handler,
 	.target_destroy		= sas_target_destroy,
diff --git a/drivers/scsi/hpsa.c b/drivers/scsi/hpsa.c
index bc64e8a0449d..ff67ef5d5347 100644
--- a/drivers/scsi/hpsa.c
+++ b/drivers/scsi/hpsa.c
@@ -965,7 +965,6 @@ static struct scsi_host_template hpsa_driver_template = {
 	.scan_finished		= hpsa_scan_finished,
 	.change_queue_depth	= hpsa_change_queue_depth,
 	.this_id		= -1,
-	.use_clustering		= ENABLE_CLUSTERING,
 	.eh_device_reset_handler = hpsa_eh_device_reset_handler,
 	.ioctl			= hpsa_ioctl,
 	.slave_alloc		= hpsa_slave_alloc,
diff --git a/drivers/scsi/hptiop.c b/drivers/scsi/hptiop.c
index dc52b37a0df8..3eedfd4f8f57 100644
--- a/drivers/scsi/hptiop.c
+++ b/drivers/scsi/hptiop.c
@@ -1180,7 +1180,6 @@ static struct scsi_host_template driver_template = {
 	.eh_host_reset_handler      = hptiop_reset,
 	.info                       = hptiop_info,
 	.emulated                   = 0,
-	.use_clustering             = ENABLE_CLUSTERING,
 	.proc_name                  = driver_name,
 	.shost_attrs                = hptiop_attrs,
 	.slave_configure            = hptiop_slave_config,
diff --git a/drivers/scsi/ibmvscsi/ibmvfc.c b/drivers/scsi/ibmvscsi/ibmvfc.c
index b64ca977825d..dbaa4f131433 100644
--- a/drivers/scsi/ibmvscsi/ibmvfc.c
+++ b/drivers/scsi/ibmvscsi/ibmvfc.c
@@ -3100,7 +3100,6 @@ static struct scsi_host_template driver_template = {
 	.this_id = -1,
 	.sg_tablesize = SG_ALL,
 	.max_sectors = IBMVFC_MAX_SECTORS,
-	.use_clustering = ENABLE_CLUSTERING,
 	.shost_attrs = ibmvfc_attrs,
 	.track_queue_depth = 1,
 };
diff --git a/drivers/scsi/ibmvscsi/ibmvscsi.c b/drivers/scsi/ibmvscsi/ibmvscsi.c
index 9df8a1a2299c..1135e74646e2 100644
--- a/drivers/scsi/ibmvscsi/ibmvscsi.c
+++ b/drivers/scsi/ibmvscsi/ibmvscsi.c
@@ -2079,7 +2079,6 @@ static struct scsi_host_template driver_template = {
 	.can_queue = IBMVSCSI_MAX_REQUESTS_DEFAULT,
 	.this_id = -1,
 	.sg_tablesize = SG_ALL,
-	.use_clustering = ENABLE_CLUSTERING,
 	.shost_attrs = ibmvscsi_attrs,
 };
 
diff --git a/drivers/scsi/imm.c b/drivers/scsi/imm.c
index 8c6627bc8a39..cea7f502e8ca 100644
--- a/drivers/scsi/imm.c
+++ b/drivers/scsi/imm.c
@@ -1110,7 +1110,6 @@ static struct scsi_host_template imm_template = {
 	.bios_param		= imm_biosparam,
 	.this_id		= 7,
 	.sg_tablesize		= SG_ALL,
-	.use_clustering		= ENABLE_CLUSTERING,
 	.can_queue		= 1,
 	.slave_alloc		= imm_adjust_queue,
 };
diff --git a/drivers/scsi/initio.c b/drivers/scsi/initio.c
index 0a8d786c84ed..eb2778b5c81b 100644
--- a/drivers/scsi/initio.c
+++ b/drivers/scsi/initio.c
@@ -2817,7 +2817,6 @@ static struct scsi_host_template initio_template = {
 	.can_queue		= MAX_TARGETS * i91u_MAXQUEUE,
 	.this_id		= 1,
 	.sg_tablesize		= SG_ALL,
-	.use_clustering		= ENABLE_CLUSTERING,
 };
 
 static int initio_probe_one(struct pci_dev *pdev,
diff --git a/drivers/scsi/ipr.c b/drivers/scsi/ipr.c
index 271990bc065b..d1b4025a4503 100644
--- a/drivers/scsi/ipr.c
+++ b/drivers/scsi/ipr.c
@@ -6754,7 +6754,6 @@ static struct scsi_host_template driver_template = {
 	.sg_tablesize = IPR_MAX_SGLIST,
 	.max_sectors = IPR_IOA_MAX_SECTORS,
 	.cmd_per_lun = IPR_MAX_CMD_PER_LUN,
-	.use_clustering = ENABLE_CLUSTERING,
 	.shost_attrs = ipr_ioa_attrs,
 	.sdev_attrs = ipr_dev_attrs,
 	.proc_name = IPR_NAME,
diff --git a/drivers/scsi/ips.c b/drivers/scsi/ips.c
index 70a776dc0a02..067725295083 100644
--- a/drivers/scsi/ips.c
+++ b/drivers/scsi/ips.c
@@ -365,7 +365,6 @@ static struct scsi_host_template ips_driver_template = {
 	.this_id		= -1,
 	.sg_tablesize		= IPS_MAX_SG,
 	.cmd_per_lun		= 3,
-	.use_clustering		= ENABLE_CLUSTERING,
 	.no_write_same		= 1,
 };
 
diff --git a/drivers/scsi/isci/init.c b/drivers/scsi/isci/init.c
index d72edbcbb7c6..68b90c4f79a3 100644
--- a/drivers/scsi/isci/init.c
+++ b/drivers/scsi/isci/init.c
@@ -163,7 +163,6 @@ static struct scsi_host_template isci_sht = {
 	.this_id			= -1,
 	.sg_tablesize			= SG_ALL,
 	.max_sectors			= SCSI_DEFAULT_MAX_SECTORS,
-	.use_clustering			= ENABLE_CLUSTERING,
 	.eh_abort_handler		= sas_eh_abort_handler,
 	.eh_device_reset_handler        = sas_eh_device_reset_handler,
 	.eh_target_reset_handler        = sas_eh_target_reset_handler,
diff --git a/drivers/scsi/lpfc/lpfc_scsi.c b/drivers/scsi/lpfc/lpfc_scsi.c
index 14a62253b099..473d255f15c0 100644
--- a/drivers/scsi/lpfc/lpfc_scsi.c
+++ b/drivers/scsi/lpfc/lpfc_scsi.c
@@ -6054,7 +6054,6 @@ struct scsi_host_template lpfc_template_nvme = {
 	.this_id		= -1,
 	.sg_tablesize		= 1,
 	.cmd_per_lun		= 1,
-	.use_clustering		= ENABLE_CLUSTERING,
 	.shost_attrs		= lpfc_hba_attrs,
 	.max_sectors		= 0xFFFF,
 	.vendor_id		= LPFC_NL_VENDOR_ID,
@@ -6079,7 +6078,6 @@ struct scsi_host_template lpfc_template_no_hr = {
 	.this_id		= -1,
 	.sg_tablesize		= LPFC_DEFAULT_SG_SEG_CNT,
 	.cmd_per_lun		= LPFC_CMD_PER_LUN,
-	.use_clustering		= ENABLE_CLUSTERING,
 	.shost_attrs		= lpfc_hba_attrs,
 	.max_sectors		= 0xFFFF,
 	.vendor_id		= LPFC_NL_VENDOR_ID,
@@ -6106,7 +6104,6 @@ struct scsi_host_template lpfc_template = {
 	.this_id		= -1,
 	.sg_tablesize		= LPFC_DEFAULT_SG_SEG_CNT,
 	.cmd_per_lun		= LPFC_CMD_PER_LUN,
-	.use_clustering		= ENABLE_CLUSTERING,
 	.shost_attrs		= lpfc_hba_attrs,
 	.max_sectors		= 0xFFFF,
 	.vendor_id		= LPFC_NL_VENDOR_ID,
@@ -6131,7 +6128,6 @@ struct scsi_host_template lpfc_vport_template = {
 	.this_id		= -1,
 	.sg_tablesize		= LPFC_DEFAULT_SG_SEG_CNT,
 	.cmd_per_lun		= LPFC_CMD_PER_LUN,
-	.use_clustering		= ENABLE_CLUSTERING,
 	.shost_attrs		= lpfc_vport_attrs,
 	.max_sectors		= 0xFFFF,
 	.change_queue_depth	= scsi_change_queue_depth,
diff --git a/drivers/scsi/megaraid.c b/drivers/scsi/megaraid.c
index 8c7154143a4e..4862f65ec3e8 100644
--- a/drivers/scsi/megaraid.c
+++ b/drivers/scsi/megaraid.c
@@ -4148,7 +4148,6 @@ static struct scsi_host_template megaraid_template = {
 	.this_id			= DEFAULT_INITIATOR_ID,
 	.sg_tablesize			= MAX_SGLIST,
 	.cmd_per_lun			= DEF_CMD_PER_LUN,
-	.use_clustering			= ENABLE_CLUSTERING,
 	.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 7f9ba88d1c2d..e836392b75e8 100644
--- a/drivers/scsi/megaraid/megaraid_mbox.c
+++ b/drivers/scsi/megaraid/megaraid_mbox.c
@@ -336,7 +336,6 @@ static struct scsi_host_template megaraid_template_g = {
 	.eh_abort_handler		= megaraid_abort_handler,
 	.eh_host_reset_handler		= megaraid_reset_handler,
 	.change_queue_depth		= scsi_change_queue_depth,
-	.use_clustering			= ENABLE_CLUSTERING,
 	.no_write_same			= 1,
 	.sdev_attrs			= megaraid_sdev_attrs,
 	.shost_attrs			= megaraid_shost_attrs,
diff --git a/drivers/scsi/megaraid/megaraid_sas_base.c b/drivers/scsi/megaraid/megaraid_sas_base.c
index 9db7aebc3564..0c72c6e07bc3 100644
--- a/drivers/scsi/megaraid/megaraid_sas_base.c
+++ b/drivers/scsi/megaraid/megaraid_sas_base.c
@@ -3189,7 +3189,6 @@ static struct scsi_host_template megasas_template = {
 	.eh_timed_out = megasas_reset_timer,
 	.shost_attrs = megaraid_host_attrs,
 	.bios_param = megasas_bios_param,
-	.use_clustering = ENABLE_CLUSTERING,
 	.change_queue_depth = scsi_change_queue_depth,
 	.no_write_same = 1,
 };
diff --git a/drivers/scsi/mpt3sas/mpt3sas_scsih.c b/drivers/scsi/mpt3sas/mpt3sas_scsih.c
index 039dee49c06e..22df12698d43 100644
--- a/drivers/scsi/mpt3sas/mpt3sas_scsih.c
+++ b/drivers/scsi/mpt3sas/mpt3sas_scsih.c
@@ -10173,7 +10173,6 @@ static struct scsi_host_template mpt2sas_driver_template = {
 	.sg_tablesize			= MPT2SAS_SG_DEPTH,
 	.max_sectors			= 32767,
 	.cmd_per_lun			= 7,
-	.use_clustering			= ENABLE_CLUSTERING,
 	.shost_attrs			= mpt3sas_host_attrs,
 	.sdev_attrs			= mpt3sas_dev_attrs,
 	.track_queue_depth		= 1,
@@ -10212,7 +10211,6 @@ static struct scsi_host_template mpt3sas_driver_template = {
 	.sg_tablesize			= MPT3SAS_SG_DEPTH,
 	.max_sectors			= 32767,
 	.cmd_per_lun			= 7,
-	.use_clustering			= ENABLE_CLUSTERING,
 	.shost_attrs			= mpt3sas_host_attrs,
 	.sdev_attrs			= mpt3sas_dev_attrs,
 	.track_queue_depth		= 1,
diff --git a/drivers/scsi/mvme147.c b/drivers/scsi/mvme147.c
index 7d1ab414b78f..ca96d6d9c350 100644
--- a/drivers/scsi/mvme147.c
+++ b/drivers/scsi/mvme147.c
@@ -78,7 +78,6 @@ static struct scsi_host_template mvme147_host_template = {
 	.this_id		= 7,
 	.sg_tablesize		= SG_ALL,
 	.cmd_per_lun		= CMD_PER_LUN,
-	.use_clustering		= ENABLE_CLUSTERING
 };
 
 static struct Scsi_Host *mvme147_shost;
diff --git a/drivers/scsi/mvsas/mv_init.c b/drivers/scsi/mvsas/mv_init.c
index 3ac34373746c..030d911ee374 100644
--- a/drivers/scsi/mvsas/mv_init.c
+++ b/drivers/scsi/mvsas/mv_init.c
@@ -59,7 +59,6 @@ static struct scsi_host_template mvs_sht = {
 	.this_id		= -1,
 	.sg_tablesize		= SG_ALL,
 	.max_sectors		= SCSI_DEFAULT_MAX_SECTORS,
-	.use_clustering		= ENABLE_CLUSTERING,
 	.eh_device_reset_handler = sas_eh_device_reset_handler,
 	.eh_target_reset_handler = sas_eh_target_reset_handler,
 	.target_destroy		= sas_target_destroy,
diff --git a/drivers/scsi/ncr53c8xx.c b/drivers/scsi/ncr53c8xx.c
index 6cd3e289ef99..1a236a3dfd51 100644
--- a/drivers/scsi/ncr53c8xx.c
+++ b/drivers/scsi/ncr53c8xx.c
@@ -8313,7 +8313,6 @@ struct Scsi_Host * __init ncr_attach(struct scsi_host_template *tpnt,
 	tpnt->this_id		= 7;
 	tpnt->sg_tablesize	= SCSI_NCR_SG_TABLESIZE;
 	tpnt->cmd_per_lun	= SCSI_NCR_CMD_PER_LUN;
-	tpnt->use_clustering	= ENABLE_CLUSTERING;
 
 	if (device->differential)
 		driver_setup.diff_support = device->differential;
diff --git a/drivers/scsi/pcmcia/sym53c500_cs.c b/drivers/scsi/pcmcia/sym53c500_cs.c
index a3b63bea0e50..d1e98a6ea28f 100644
--- a/drivers/scsi/pcmcia/sym53c500_cs.c
+++ b/drivers/scsi/pcmcia/sym53c500_cs.c
@@ -680,7 +680,6 @@ static struct scsi_host_template sym53c500_driver_template = {
      .can_queue			= 1,
      .this_id			= 7,
      .sg_tablesize		= 32,
-     .use_clustering		= ENABLE_CLUSTERING,
      .shost_attrs		= SYM53C500_shost_attrs
 };
 
diff --git a/drivers/scsi/pm8001/pm8001_init.c b/drivers/scsi/pm8001/pm8001_init.c
index d71e7e4ec29c..a36060c23b37 100644
--- a/drivers/scsi/pm8001/pm8001_init.c
+++ b/drivers/scsi/pm8001/pm8001_init.c
@@ -84,7 +84,6 @@ static struct scsi_host_template pm8001_sht = {
 	.this_id		= -1,
 	.sg_tablesize		= SG_ALL,
 	.max_sectors		= SCSI_DEFAULT_MAX_SECTORS,
-	.use_clustering		= ENABLE_CLUSTERING,
 	.eh_device_reset_handler = sas_eh_device_reset_handler,
 	.eh_target_reset_handler = sas_eh_target_reset_handler,
 	.target_destroy		= sas_target_destroy,
diff --git a/drivers/scsi/pmcraid.c b/drivers/scsi/pmcraid.c
index 707d766c1ee9..7c4673308f5b 100644
--- a/drivers/scsi/pmcraid.c
+++ b/drivers/scsi/pmcraid.c
@@ -4149,7 +4149,6 @@ static struct scsi_host_template pmcraid_host_template = {
 	.max_sectors = PMCRAID_IOA_MAX_SECTORS,
 	.no_write_same = 1,
 	.cmd_per_lun = PMCRAID_MAX_CMD_PER_LUN,
-	.use_clustering = ENABLE_CLUSTERING,
 	.shost_attrs = pmcraid_host_attrs,
 	.proc_name = PMCRAID_DRIVER_NAME,
 };
diff --git a/drivers/scsi/ppa.c b/drivers/scsi/ppa.c
index ee86a0c62dbf..c182b5458f98 100644
--- a/drivers/scsi/ppa.c
+++ b/drivers/scsi/ppa.c
@@ -978,7 +978,6 @@ static struct scsi_host_template ppa_template = {
 	.bios_param		= ppa_biosparam,
 	.this_id		= -1,
 	.sg_tablesize		= SG_ALL,
-	.use_clustering		= ENABLE_CLUSTERING,
 	.can_queue		= 1,
 	.slave_alloc		= ppa_adjust_queue,
 };
diff --git a/drivers/scsi/ps3rom.c b/drivers/scsi/ps3rom.c
index 4924424d20fe..8d769138c01c 100644
--- a/drivers/scsi/ps3rom.c
+++ b/drivers/scsi/ps3rom.c
@@ -349,7 +349,6 @@ static struct scsi_host_template ps3rom_host_template = {
 	.sg_tablesize =		SG_ALL,
 	.emulated =             1,		/* only sg driver uses this */
 	.max_sectors =		PS3ROM_MAX_SECTORS,
-	.use_clustering =	ENABLE_CLUSTERING,
 	.module =		THIS_MODULE,
 };
 
diff --git a/drivers/scsi/qedf/qedf_main.c b/drivers/scsi/qedf/qedf_main.c
index 12e6e5dfae6e..edcaf4b0cb0b 100644
--- a/drivers/scsi/qedf/qedf_main.c
+++ b/drivers/scsi/qedf/qedf_main.c
@@ -785,7 +785,6 @@ static struct scsi_host_template qedf_host_template = {
 	.name 		= QEDF_MODULE_NAME,
 	.this_id 	= -1,
 	.cmd_per_lun	= 32,
-	.use_clustering = ENABLE_CLUSTERING,
 	.max_sectors 	= 0xffff,
 	.queuecommand 	= qedf_queuecommand,
 	.shost_attrs	= qedf_host_attrs,
diff --git a/drivers/scsi/qedi/qedi_iscsi.c b/drivers/scsi/qedi/qedi_iscsi.c
index 2f0a4f2c5ff8..4da660c1c431 100644
--- a/drivers/scsi/qedi/qedi_iscsi.c
+++ b/drivers/scsi/qedi/qedi_iscsi.c
@@ -61,7 +61,6 @@ struct scsi_host_template qedi_host_template = {
 	.max_sectors = 0xffff,
 	.dma_boundary = QEDI_HW_DMA_BOUNDARY,
 	.cmd_per_lun = 128,
-	.use_clustering = ENABLE_CLUSTERING,
 	.shost_attrs = qedi_shost_attrs,
 };
 
diff --git a/drivers/scsi/qla1280.c b/drivers/scsi/qla1280.c
index 9c5b67304a76..a414f51302b7 100644
--- a/drivers/scsi/qla1280.c
+++ b/drivers/scsi/qla1280.c
@@ -4203,7 +4203,6 @@ static struct scsi_host_template qla1280_driver_template = {
 	.can_queue		= MAX_OUTSTANDING_COMMANDS,
 	.this_id		= -1,
 	.sg_tablesize		= SG_ALL,
-	.use_clustering		= ENABLE_CLUSTERING,
 };
 
 
diff --git a/drivers/scsi/qla2xxx/qla_os.c b/drivers/scsi/qla2xxx/qla_os.c
index d0d3a362ad32..90f1742cff58 100644
--- a/drivers/scsi/qla2xxx/qla_os.c
+++ b/drivers/scsi/qla2xxx/qla_os.c
@@ -328,7 +328,6 @@ struct scsi_host_template qla2xxx_driver_template = {
 	.map_queues             = qla2xxx_map_queues,
 	.this_id		= -1,
 	.cmd_per_lun		= 3,
-	.use_clustering		= ENABLE_CLUSTERING,
 	.sg_tablesize		= SG_ALL,
 
 	.max_sectors		= 0xFFFF,
diff --git a/drivers/scsi/qla4xxx/ql4_os.c b/drivers/scsi/qla4xxx/ql4_os.c
index 1c702cd22359..949e186cc5d7 100644
--- a/drivers/scsi/qla4xxx/ql4_os.c
+++ b/drivers/scsi/qla4xxx/ql4_os.c
@@ -205,7 +205,6 @@ static struct scsi_host_template qla4xxx_driver_template = {
 
 	.this_id		= -1,
 	.cmd_per_lun		= 3,
-	.use_clustering		= ENABLE_CLUSTERING,
 	.sg_tablesize		= SG_ALL,
 
 	.max_sectors		= 0xFFFF,
diff --git a/drivers/scsi/qlogicpti.c b/drivers/scsi/qlogicpti.c
index 9d09228eee28..e35ce762d454 100644
--- a/drivers/scsi/qlogicpti.c
+++ b/drivers/scsi/qlogicpti.c
@@ -1287,7 +1287,6 @@ static struct scsi_host_template qpti_template = {
 	.can_queue		= QLOGICPTI_REQ_QUEUE_LEN,
 	.this_id		= 7,
 	.sg_tablesize		= QLOGICPTI_MAX_SG(QLOGICPTI_REQ_QUEUE_LEN),
-	.use_clustering		= ENABLE_CLUSTERING,
 };
 
 static const struct of_device_id qpti_match[];
diff --git a/drivers/scsi/scsi_debug.c b/drivers/scsi/scsi_debug.c
index 60bcc6df97a9..53ba417bef8a 100644
--- a/drivers/scsi/scsi_debug.c
+++ b/drivers/scsi/scsi_debug.c
@@ -5851,7 +5851,6 @@ static struct scsi_host_template sdebug_driver_template = {
 	.sg_tablesize =		SG_MAX_SEGMENTS,
 	.cmd_per_lun =		DEF_CMD_PER_LUN,
 	.max_sectors =		-1U,
-	.use_clustering = 	DISABLE_CLUSTERING,
 	.module =		THIS_MODULE,
 	.track_queue_depth =	1,
 };
@@ -5866,8 +5865,8 @@ static int sdebug_driver_probe(struct device *dev)
 	sdbg_host = to_sdebug_host(dev);
 
 	sdebug_driver_template.can_queue = sdebug_max_queue;
-	if (sdebug_clustering)
-		sdebug_driver_template.use_clustering = ENABLE_CLUSTERING;
+	if (!sdebug_clustering)
+		sdebug_driver_template.use_clustering = DISABLE_CLUSTERING;
 	hpnt = scsi_host_alloc(&sdebug_driver_template, sizeof(sdbg_host));
 	if (NULL == hpnt) {
 		pr_err("scsi_host_alloc failed\n");
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index c7fccbb8f554..f6900e0b3024 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -2229,7 +2229,7 @@ void __scsi_init_queue(struct Scsi_Host *shost, struct request_queue *q)
 
 	blk_queue_max_segment_size(q, dma_get_max_seg_size(dev));
 
-	if (!shost->use_clustering)
+	if (shost->use_clustering == DISABLE_CLUSTERING)
 		q->limits.cluster = 0;
 
 	/*
diff --git a/drivers/scsi/smartpqi/smartpqi_init.c b/drivers/scsi/smartpqi/smartpqi_init.c
index a25a07a0b7f0..c9a1a4973574 100644
--- a/drivers/scsi/smartpqi/smartpqi_init.c
+++ b/drivers/scsi/smartpqi/smartpqi_init.c
@@ -5779,7 +5779,6 @@ static struct scsi_host_template pqi_driver_template = {
 	.scan_start = pqi_scan_start,
 	.scan_finished = pqi_scan_finished,
 	.this_id = -1,
-	.use_clustering = ENABLE_CLUSTERING,
 	.eh_device_reset_handler = pqi_eh_device_reset_handler,
 	.ioctl = pqi_ioctl,
 	.slave_alloc = pqi_slave_alloc,
diff --git a/drivers/scsi/snic/snic_main.c b/drivers/scsi/snic/snic_main.c
index 5295277d6325..5e824fd6047a 100644
--- a/drivers/scsi/snic/snic_main.c
+++ b/drivers/scsi/snic/snic_main.c
@@ -127,7 +127,6 @@ static struct scsi_host_template snic_host_template = {
 	.this_id = -1,
 	.cmd_per_lun = SNIC_DFLT_QUEUE_DEPTH,
 	.can_queue = SNIC_MAX_IO_REQ,
-	.use_clustering = ENABLE_CLUSTERING,
 	.sg_tablesize = SNIC_MAX_SG_DESC_CNT,
 	.max_sectors = 0x800,
 	.shost_attrs = snic_attrs,
diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c
index f03dc03a42c3..8ab05e93acfa 100644
--- a/drivers/scsi/storvsc_drv.c
+++ b/drivers/scsi/storvsc_drv.c
@@ -1698,7 +1698,6 @@ static struct scsi_host_template scsi_driver = {
 	.slave_configure =	storvsc_device_configure,
 	.cmd_per_lun =		2048,
 	.this_id =		-1,
-	.use_clustering =	ENABLE_CLUSTERING,
 	/* Make sure we dont get a sg segment crosses a page boundary */
 	.dma_boundary =		PAGE_SIZE-1,
 	.no_write_same =	1,
diff --git a/drivers/scsi/sym53c8xx_2/sym_glue.c b/drivers/scsi/sym53c8xx_2/sym_glue.c
index 6e9b54061d7e..57f6d63e4c40 100644
--- a/drivers/scsi/sym53c8xx_2/sym_glue.c
+++ b/drivers/scsi/sym53c8xx_2/sym_glue.c
@@ -1660,7 +1660,6 @@ static struct scsi_host_template sym2_template = {
 	.eh_bus_reset_handler	= sym53c8xx_eh_bus_reset_handler,
 	.eh_host_reset_handler	= sym53c8xx_eh_host_reset_handler,
 	.this_id		= 7,
-	.use_clustering		= ENABLE_CLUSTERING,
 	.max_sectors		= 0xFFFF,
 #ifdef SYM_LINUX_PROC_INFO_SUPPORT
 	.show_info		= sym_show_info,
diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c
index 1c72db94270e..57c6c585226b 100644
--- a/drivers/scsi/virtio_scsi.c
+++ b/drivers/scsi/virtio_scsi.c
@@ -747,7 +747,6 @@ static struct scsi_host_template virtscsi_host_template = {
 	.slave_alloc = virtscsi_device_alloc,
 
 	.dma_boundary = UINT_MAX,
-	.use_clustering = ENABLE_CLUSTERING,
 	.target_alloc = virtscsi_target_alloc,
 	.target_destroy = virtscsi_target_destroy,
 	.map_queues = virtscsi_map_queues,
diff --git a/drivers/scsi/vmw_pvscsi.c b/drivers/scsi/vmw_pvscsi.c
index 6e491023fdd8..644b0e1862b0 100644
--- a/drivers/scsi/vmw_pvscsi.c
+++ b/drivers/scsi/vmw_pvscsi.c
@@ -1007,7 +1007,6 @@ static struct scsi_host_template pvscsi_template = {
 	.sg_tablesize			= PVSCSI_MAX_NUM_SG_ENTRIES_PER_SEGMENT,
 	.dma_boundary			= UINT_MAX,
 	.max_sectors			= 0xffff,
-	.use_clustering			= ENABLE_CLUSTERING,
 	.change_queue_depth		= pvscsi_change_queue_depth,
 	.eh_abort_handler		= pvscsi_abort,
 	.eh_device_reset_handler	= pvscsi_device_reset,
diff --git a/drivers/scsi/wd719x.c b/drivers/scsi/wd719x.c
index 808ba8e952db..e3310e9488d2 100644
--- a/drivers/scsi/wd719x.c
+++ b/drivers/scsi/wd719x.c
@@ -871,7 +871,6 @@ static struct scsi_host_template wd719x_template = {
 	.can_queue			= 255,
 	.this_id			= 7,
 	.sg_tablesize			= WD719X_SG,
-	.use_clustering			= ENABLE_CLUSTERING,
 };
 
 static int wd719x_pci_probe(struct pci_dev *pdev, const struct pci_device_id *d)
diff --git a/drivers/staging/rts5208/rtsx.c b/drivers/staging/rts5208/rtsx.c
index 69e6abe14abf..c57d66a7405f 100644
--- a/drivers/staging/rts5208/rtsx.c
+++ b/drivers/staging/rts5208/rtsx.c
@@ -237,12 +237,6 @@ static struct scsi_host_template rtsx_host_template = {
 	/* limit the total size of a transfer to 120 KB */
 	.max_sectors =                  240,
 
-	/* merge commands... this seems to help performance, but
-	 * periodically someone should test to see which setting is more
-	 * optimal.
-	 */
-	.use_clustering =		1,
-
 	/* emulated HBA */
 	.emulated =			1,
 
diff --git a/drivers/staging/unisys/visorhba/visorhba_main.c b/drivers/staging/unisys/visorhba/visorhba_main.c
index 4fc521c51c0e..5cf93e8eb77c 100644
--- a/drivers/staging/unisys/visorhba/visorhba_main.c
+++ b/drivers/staging/unisys/visorhba/visorhba_main.c
@@ -645,7 +645,6 @@ static struct scsi_host_template visorhba_driver_template = {
 	.this_id = -1,
 	.slave_alloc = visorhba_slave_alloc,
 	.slave_destroy = visorhba_slave_destroy,
-	.use_clustering = ENABLE_CLUSTERING,
 };
 
 /*
diff --git a/drivers/usb/image/microtek.c b/drivers/usb/image/microtek.c
index 9f2f563c82ed..607be1f4fe27 100644
--- a/drivers/usb/image/microtek.c
+++ b/drivers/usb/image/microtek.c
@@ -632,7 +632,6 @@ static struct scsi_host_template mts_scsi_host_template = {
 	.sg_tablesize =		SG_ALL,
 	.can_queue =		1,
 	.this_id =		-1,
-	.use_clustering =	1,
 	.emulated =		1,
 	.slave_alloc =		mts_slave_alloc,
 	.slave_configure =	mts_slave_configure,
diff --git a/drivers/usb/storage/scsiglue.c b/drivers/usb/storage/scsiglue.c
index e227bb5b794f..fde2e71a6ade 100644
--- a/drivers/usb/storage/scsiglue.c
+++ b/drivers/usb/storage/scsiglue.c
@@ -639,13 +639,6 @@ static const struct scsi_host_template usb_stor_host_template = {
 	 */
 	.max_sectors =                  240,
 
-	/*
-	 * merge commands... this seems to help performance, but
-	 * periodically someone should test to see which setting is more
-	 * optimal.
-	 */
-	.use_clustering =		1,
-
 	/* emulated HBA */
 	.emulated =			1,
 
diff --git a/include/linux/libata.h b/include/linux/libata.h
index 38c95d66ab12..68133842e6d7 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -135,7 +135,6 @@ enum {
 
 	ATA_SHT_EMULATED	= 1,
 	ATA_SHT_THIS_ID		= -1,
-	ATA_SHT_USE_CLUSTERING	= 1,
 
 	/* struct ata_taskfile flags */
 	ATA_TFLAG_LBA48		= (1 << 0), /* enable 48-bit LBA and "HOB" */
@@ -1360,7 +1359,6 @@ extern struct device_attribute *ata_common_sdev_attrs[];
 	.tag_alloc_policy	= BLK_TAG_ALLOC_RR,		\
 	.this_id		= ATA_SHT_THIS_ID,		\
 	.emulated		= ATA_SHT_EMULATED,		\
-	.use_clustering		= ATA_SHT_USE_CLUSTERING,	\
 	.proc_name		= drv_name,			\
 	.slave_configure	= ata_scsi_slave_config,	\
 	.slave_destroy		= ata_scsi_slave_destroy,	\
diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h
index 5ea06d310a25..7dc534c794dc 100644
--- a/include/scsi/scsi_host.h
+++ b/include/scsi/scsi_host.h
@@ -44,8 +44,7 @@ struct blk_queue_tags;
 #define MODE_INITIATOR 0x01
 #define MODE_TARGET 0x02
 
-#define DISABLE_CLUSTERING 0
-#define ENABLE_CLUSTERING 1
+#define DISABLE_CLUSTERING (-1)
 
 struct scsi_host_template {
 	struct module *module;
-- 
2.19.2

[PATCH 03/10] scsi: introduce a max_segment_size host_template parameters

[Christoph Hellwig]

This allows the host driver to indicate the maximum supported
segment size in a nice an easy way, so that the driver doesn't
have to worry about DMA-layer imposed limitations.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
---
 drivers/scsi/be2iscsi/be_main.c | 8 +-------
 drivers/scsi/hosts.c            | 5 +++++
 drivers/scsi/scsi_debug.c       | 2 +-
 drivers/scsi/scsi_lib.c         | 3 ++-
 include/scsi/scsi_host.h        | 6 ++++++
 5 files changed, 15 insertions(+), 9 deletions(-)

diff --git a/drivers/scsi/be2iscsi/be_main.c b/drivers/scsi/be2iscsi/be_main.c
index c4108b17d5ab..39f3820572b4 100644
--- a/drivers/scsi/be2iscsi/be_main.c
+++ b/drivers/scsi/be2iscsi/be_main.c
@@ -214,12 +214,6 @@ static char const *cqe_desc[] = {
 	"CXN_KILLED_IMM_DATA_RCVD"
 };
 
-static int beiscsi_slave_configure(struct scsi_device *sdev)
-{
-	blk_queue_max_segment_size(sdev->request_queue, 65536);
-	return 0;
-}
-
 static int beiscsi_eh_abort(struct scsi_cmnd *sc)
 {
 	struct iscsi_task *abrt_task = (struct iscsi_task *)sc->SCp.ptr;
@@ -393,7 +387,6 @@ static struct scsi_host_template beiscsi_sht = {
 	.proc_name = DRV_NAME,
 	.queuecommand = iscsi_queuecommand,
 	.change_queue_depth = scsi_change_queue_depth,
-	.slave_configure = beiscsi_slave_configure,
 	.target_alloc = iscsi_target_alloc,
 	.eh_timed_out = iscsi_eh_cmd_timed_out,
 	.eh_abort_handler = beiscsi_eh_abort,
@@ -404,6 +397,7 @@ static struct scsi_host_template beiscsi_sht = {
 	.can_queue = BE2_IO_DEPTH,
 	.this_id = -1,
 	.max_sectors = BEISCSI_MAX_SECTORS,
+	.max_segment_size = 65536,
 	.cmd_per_lun = BEISCSI_CMD_PER_LUN,
 	.vendor_id = SCSI_NL_VID_TYPE_PCI | BE_VENDOR_ID,
 	.track_queue_depth = 1,
diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c
index ea4b0bb0c1cd..e8148ba414a3 100644
--- a/drivers/scsi/hosts.c
+++ b/drivers/scsi/hosts.c
@@ -464,6 +464,11 @@ struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *sht, int privsize)
 	else
 		shost->max_sectors = SCSI_DEFAULT_MAX_SECTORS;
 
+	if (sht->max_segment_size)
+		shost->max_segment_size = sht->max_segment_size;
+	else
+		shost->max_segment_size = BLK_MAX_SEGMENT_SIZE;
+
 	/*
 	 * assume a 4GB boundary, if not set
 	 */
diff --git a/drivers/scsi/scsi_debug.c b/drivers/scsi/scsi_debug.c
index 53ba417bef8a..57d418d7d74e 100644
--- a/drivers/scsi/scsi_debug.c
+++ b/drivers/scsi/scsi_debug.c
@@ -3973,7 +3973,6 @@ static int scsi_debug_slave_configure(struct scsi_device *sdp)
 			return 1;  /* no resources, will be marked offline */
 	}
 	sdp->hostdata = devip;
-	blk_queue_max_segment_size(sdp->request_queue, -1U);
 	if (sdebug_no_uld)
 		sdp->no_uld_attach = 1;
 	config_cdb_len(sdp);
@@ -5851,6 +5850,7 @@ static struct scsi_host_template sdebug_driver_template = {
 	.sg_tablesize =		SG_MAX_SEGMENTS,
 	.cmd_per_lun =		DEF_CMD_PER_LUN,
 	.max_sectors =		-1U,
+	.max_segment_size =	-1U,
 	.module =		THIS_MODULE,
 	.track_queue_depth =	1,
 };
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index f6900e0b3024..2d4fd6b4bd92 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -2227,7 +2227,8 @@ void __scsi_init_queue(struct Scsi_Host *shost, struct request_queue *q)
 	blk_queue_segment_boundary(q, shost->dma_boundary);
 	dma_set_seg_boundary(dev, shost->dma_boundary);
 
-	blk_queue_max_segment_size(q, dma_get_max_seg_size(dev));
+	blk_queue_max_segment_size(q,
+		min(shost->max_segment_size, dma_get_max_seg_size(dev)));
 
 	if (shost->use_clustering == DISABLE_CLUSTERING)
 		q->limits.cluster = 0;
diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h
index 7dc534c794dc..834204681ca3 100644
--- a/include/scsi/scsi_host.h
+++ b/include/scsi/scsi_host.h
@@ -364,6 +364,11 @@ struct scsi_host_template {
 	 */
 	unsigned int max_sectors;
 
+	/*
+	 * Maximum size in bytes of a single segment.
+	 */
+	unsigned int max_segment_size;
+
 	/*
 	 * DMA scatter gather segment boundary limit. A segment crossing this
 	 * boundary will be split in two.
@@ -603,6 +608,7 @@ struct Scsi_Host {
 	short unsigned int sg_tablesize;
 	short unsigned int sg_prot_tablesize;
 	unsigned int max_sectors;
+	unsigned int max_segment_size;
 	unsigned long dma_boundary;
 	/*
 	 * In scsi-mq mode, the number of hardware queues supported by the LLD.
-- 
2.19.2

[PATCH 04/10] cumana_2: remove the explicit use_clustering setting

[Christoph Hellwig]

This driver already sets the dma_boundary to PAGE_SIZE - 1, which
has the same result.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 drivers/scsi/arm/cumana_2.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/scsi/arm/cumana_2.c b/drivers/scsi/arm/cumana_2.c
index edce5f3cfdba..40afcbd8de61 100644
--- a/drivers/scsi/arm/cumana_2.c
+++ b/drivers/scsi/arm/cumana_2.c
@@ -367,7 +367,6 @@ static struct scsi_host_template cumanascsi2_template = {
 	.this_id			= 7,
 	.sg_tablesize			= SG_MAX_SEGMENTS,
 	.dma_boundary			= IOMD_DMA_BOUNDARY,
-	.use_clustering			= DISABLE_CLUSTERING,
 	.proc_name			= "cumanascsi2",
 };
 
-- 
2.19.2

[PATCH 05/10] powertec: remove the explicit use_clustering setting

[Christoph Hellwig]

This driver already sets the dma_boundary to PAGE_SIZE - 1, which
has the same result.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 drivers/scsi/arm/eesox.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/scsi/arm/eesox.c b/drivers/scsi/arm/eesox.c
index e93e047f4316..8f64c370a8a7 100644
--- a/drivers/scsi/arm/eesox.c
+++ b/drivers/scsi/arm/eesox.c
@@ -486,7 +486,6 @@ static struct scsi_host_template eesox_template = {
 	.this_id			= 7,
 	.sg_tablesize			= SG_MAX_SEGMENTS,
 	.dma_boundary			= IOMD_DMA_BOUNDARY,
-	.use_clustering			= DISABLE_CLUSTERING,
 	.proc_name			= "eesox",
 };
 
-- 
2.19.2

[PATCH 06/10] xen-scsifront: remove DISABLE_CLUSTERING

[Christoph Hellwig]

There is no such limitation in the protocol or implementation, so
remove it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 drivers/scsi/xen-scsifront.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/scsi/xen-scsifront.c b/drivers/scsi/xen-scsifront.c
index bb76d0d2022b..f0068e96a177 100644
--- a/drivers/scsi/xen-scsifront.c
+++ b/drivers/scsi/xen-scsifront.c
@@ -696,7 +696,6 @@ static struct scsi_host_template scsifront_sht = {
 	.this_id		= -1,
 	.cmd_size		= sizeof(struct vscsifrnt_shadow),
 	.sg_tablesize		= VSCSIIF_SG_TABLESIZE,
-	.use_clustering		= DISABLE_CLUSTERING,
 	.proc_name		= "scsifront",
 };
 
-- 
2.19.2

Re: [PATCH 06/10] xen-scsifront: remove DISABLE_CLUSTERING

[Juergen Gross]

On 13/12/2018 16:17, Christoph Hellwig wrote:
> There is no such limitation in the protocol or implementation, so
> remove it.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Reviewed-by: Juergen Gross <jgross@suse.com>


Juergen

[PATCH 07/10] mesh: remove DISABLE_CLUSTERING

[Christoph Hellwig]

mesh has no limitations on crossing pages for segments.  Just make
the 65535 byte segment size limit explicit, even if it matches the
current block layer limit.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Tested-by: Paul Mackerras <paulus@ozlabs.org>
---
 drivers/scsi/mesh.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/scsi/mesh.c b/drivers/scsi/mesh.c
index ec6940f2fcb3..f3e182eb0970 100644
--- a/drivers/scsi/mesh.c
+++ b/drivers/scsi/mesh.c
@@ -1838,7 +1838,7 @@ static struct scsi_host_template mesh_template = {
 	.this_id			= 7,
 	.sg_tablesize			= SG_ALL,
 	.cmd_per_lun			= 2,
-	.use_clustering			= DISABLE_CLUSTERING,
+	.max_segment_size		= 65535,
 };
 
 static int mesh_probe(struct macio_dev *mdev, const struct of_device_id *match)
-- 
2.19.2

[PATCH 08/10] mac53c94: remove DISABLE_CLUSTERING

[Christoph Hellwig]

mac53c94 has no limitations on crossing pages for segments.  Just make
the 65535 byte segment size limit explicit, even if it matches the
current block layer limit.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Tested-by: Paul Mackerras <paulus@ozlabs.org>
---
 drivers/scsi/mac53c94.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/scsi/mac53c94.c b/drivers/scsi/mac53c94.c
index 177701dfdfcb..c8e6ae98a4a6 100644
--- a/drivers/scsi/mac53c94.c
+++ b/drivers/scsi/mac53c94.c
@@ -403,7 +403,7 @@ static struct scsi_host_template mac53c94_template = {
 	.can_queue	= 1,
 	.this_id	= 7,
 	.sg_tablesize	= SG_ALL,
-	.use_clustering	= DISABLE_CLUSTERING,
+	.max_segment_size = 65535,
 };
 
 static int mac53c94_probe(struct macio_dev *mdev, const struct of_device_id *match)
-- 
2.19.2

[PATCH 09/10] scsi: remove the use_clustering flag

[Christoph Hellwig]

The same effects can be achieved by setting the dma_boundary to
PAGE_SIZE - 1 and the max_segment_size to PAGE_SIZE, so shift those
settings into the drivers.  Note that in many cases the setting might
be bogus, but this keeps the status quo.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 Documentation/scsi/scsi_mid_low_api.txt |  2 --
 arch/ia64/hp/sim/simscsi.c              |  2 +-
 drivers/scsi/a2091.c                    |  2 +-
 drivers/scsi/advansys.c                 |  4 ++--
 drivers/scsi/aha152x.c                  |  2 +-
 drivers/scsi/arm/acornscsi.c            |  2 +-
 drivers/scsi/arm/arxescsi.c             |  2 +-
 drivers/scsi/arm/cumana_1.c             |  2 +-
 drivers/scsi/arm/oak.c                  |  2 +-
 drivers/scsi/atari_scsi.c               |  2 +-
 drivers/scsi/cxgbi/cxgb3i/cxgb3i.c      |  2 +-
 drivers/scsi/cxgbi/cxgb4i/cxgb4i.c      |  2 +-
 drivers/scsi/dc395x.c                   |  2 +-
 drivers/scsi/dmx3191d.c                 |  2 +-
 drivers/scsi/g_NCR5380.c                |  2 +-
 drivers/scsi/gvp11.c                    |  2 +-
 drivers/scsi/hosts.c                    |  1 -
 drivers/scsi/ips.c                      |  1 -
 drivers/scsi/iscsi_tcp.c                |  2 +-
 drivers/scsi/mac_esp.c                  |  2 +-
 drivers/scsi/mac_scsi.c                 |  2 +-
 drivers/scsi/mvumi.c                    |  2 +-
 drivers/scsi/nsp32.c                    |  2 +-
 drivers/scsi/pcmcia/nsp_cs.c            |  2 +-
 drivers/scsi/pcmcia/qlogic_stub.c       |  2 +-
 drivers/scsi/qlogicfas.c                |  2 +-
 drivers/scsi/scsi_debug.c               |  3 ++-
 drivers/scsi/scsi_lib.c                 |  3 ---
 drivers/scsi/sgiwd93.c                  |  2 +-
 drivers/scsi/stex.c                     |  2 +-
 drivers/scsi/sun3_scsi.c                |  2 +-
 drivers/scsi/ufs/ufshcd.c               |  2 +-
 drivers/target/loopback/tcm_loop.c      |  2 +-
 drivers/usb/storage/uas.c               |  2 +-
 include/scsi/scsi_host.h                | 13 -------------
 35 files changed, 32 insertions(+), 51 deletions(-)

diff --git a/Documentation/scsi/scsi_mid_low_api.txt b/Documentation/scsi/scsi_mid_low_api.txt
index 177c031763c0..c1dd4939f4ae 100644
--- a/Documentation/scsi/scsi_mid_low_api.txt
+++ b/Documentation/scsi/scsi_mid_low_api.txt
@@ -1098,8 +1098,6 @@ of interest:
     unchecked_isa_dma - 1=>only use bottom 16 MB of ram (ISA DMA addressing
                    restriction), 0=>can use full 32 bit (or better) DMA
                    address space
-    use_clustering - 1=>SCSI commands in mid level's queue can be merged,
-                     0=>disallow SCSI command merging
     no_async_abort - 1=>Asynchronous aborts are not supported
                      0=>Timed-out commands will be aborted asynchronously
     hostt        - pointer to driver's struct scsi_host_template from which
diff --git a/arch/ia64/hp/sim/simscsi.c b/arch/ia64/hp/sim/simscsi.c
index 7e1426e76d96..f86844fc0725 100644
--- a/arch/ia64/hp/sim/simscsi.c
+++ b/arch/ia64/hp/sim/simscsi.c
@@ -347,7 +347,7 @@ static struct scsi_host_template driver_template = {
 	.sg_tablesize		= SG_ALL,
 	.max_sectors		= 1024,
 	.cmd_per_lun		= SIMSCSI_REQ_QUEUE_LEN,
-	.use_clustering		= DISABLE_CLUSTERING,
+	.dma_boundary		= PAGE_SIZE - 1,
 };
 
 static int __init
diff --git a/drivers/scsi/a2091.c b/drivers/scsi/a2091.c
index 61aadc7acb49..c96bc7261a42 100644
--- a/drivers/scsi/a2091.c
+++ b/drivers/scsi/a2091.c
@@ -160,7 +160,7 @@ static struct scsi_host_template a2091_scsi_template = {
 	.this_id		= 7,
 	.sg_tablesize		= SG_ALL,
 	.cmd_per_lun		= CMD_PER_LUN,
-	.use_clustering		= DISABLE_CLUSTERING
+	.dma_boundary		= PAGE_SIZE - 1,
 };
 
 static int a2091_probe(struct zorro_dev *z, const struct zorro_device_id *ent)
diff --git a/drivers/scsi/advansys.c b/drivers/scsi/advansys.c
index 95b4793c33f4..d37584403c33 100644
--- a/drivers/scsi/advansys.c
+++ b/drivers/scsi/advansys.c
@@ -3192,8 +3192,8 @@ static void asc_prt_driver_conf(struct seq_file *m, struct Scsi_Host *shost)
 		   shost->sg_tablesize, shost->cmd_per_lun);
 
 	seq_printf(m,
-		   " unchecked_isa_dma %d, use_clustering %d\n",
-		   shost->unchecked_isa_dma, shost->use_clustering);
+		   " unchecked_isa_dma %d\n",
+		   shost->unchecked_isa_dma);
 
 	seq_printf(m,
 		   " flags 0x%x, last_reset 0x%lx, jiffies 0x%lx, asc_n_io_port 0x%x\n",
diff --git a/drivers/scsi/aha152x.c b/drivers/scsi/aha152x.c
index 301b3cad15f8..97872838b983 100644
--- a/drivers/scsi/aha152x.c
+++ b/drivers/scsi/aha152x.c
@@ -2920,7 +2920,7 @@ static struct scsi_host_template aha152x_driver_template = {
 	.can_queue			= 1,
 	.this_id			= 7,
 	.sg_tablesize			= SG_ALL,
-	.use_clustering			= DISABLE_CLUSTERING,
+	.dma_boundary			= PAGE_SIZE - 1,
 	.slave_alloc			= aha152x_adjust_queue,
 };
 
diff --git a/drivers/scsi/arm/acornscsi.c b/drivers/scsi/arm/acornscsi.c
index 421fe869a11e..d7509859dc00 100644
--- a/drivers/scsi/arm/acornscsi.c
+++ b/drivers/scsi/arm/acornscsi.c
@@ -2890,7 +2890,7 @@ static struct scsi_host_template acornscsi_template = {
 	.this_id		= 7,
 	.sg_tablesize		= SG_ALL,
 	.cmd_per_lun		= 2,
-	.use_clustering		= DISABLE_CLUSTERING,
+	.dma_boundary		= PAGE_SIZE - 1,
 	.proc_name		= "acornscsi",
 };
 
diff --git a/drivers/scsi/arm/arxescsi.c b/drivers/scsi/arm/arxescsi.c
index 3110736fd337..5e9dd9f34821 100644
--- a/drivers/scsi/arm/arxescsi.c
+++ b/drivers/scsi/arm/arxescsi.c
@@ -245,7 +245,7 @@ static struct scsi_host_template arxescsi_template = {
 	.can_queue			= 0,
 	.this_id			= 7,
 	.sg_tablesize			= SG_ALL,
-	.use_clustering			= DISABLE_CLUSTERING,
+	.dma_boundary			= PAGE_SIZE - 1,
 	.proc_name			= "arxescsi",
 };
 
diff --git a/drivers/scsi/arm/cumana_1.c b/drivers/scsi/arm/cumana_1.c
index ae1d809904fb..e2d2a81d8e0b 100644
--- a/drivers/scsi/arm/cumana_1.c
+++ b/drivers/scsi/arm/cumana_1.c
@@ -221,10 +221,10 @@ static struct scsi_host_template cumanascsi_template = {
 	.this_id		= 7,
 	.sg_tablesize		= SG_ALL,
 	.cmd_per_lun		= 2,
-	.use_clustering		= DISABLE_CLUSTERING,
 	.proc_name		= "CumanaSCSI-1",
 	.cmd_size		= NCR5380_CMD_SIZE,
 	.max_sectors		= 128,
+	.dma_boundary		= PAGE_SIZE - 1,
 };
 
 static int cumanascsi1_probe(struct expansion_card *ec,
diff --git a/drivers/scsi/arm/oak.c b/drivers/scsi/arm/oak.c
index 05b7f755499b..8f2efaab8d46 100644
--- a/drivers/scsi/arm/oak.c
+++ b/drivers/scsi/arm/oak.c
@@ -110,7 +110,7 @@ static struct scsi_host_template oakscsi_template = {
 	.this_id		= 7,
 	.sg_tablesize		= SG_ALL,
 	.cmd_per_lun		= 2,
-	.use_clustering		= DISABLE_CLUSTERING,
+	.dma_boundary		= PAGE_SIZE - 1,
 	.proc_name		= "oakscsi",
 	.cmd_size		= NCR5380_CMD_SIZE,
 	.max_sectors		= 128,
diff --git a/drivers/scsi/atari_scsi.c b/drivers/scsi/atari_scsi.c
index 89f5154c40b6..a503dc50c4f8 100644
--- a/drivers/scsi/atari_scsi.c
+++ b/drivers/scsi/atari_scsi.c
@@ -714,7 +714,7 @@ static struct scsi_host_template atari_scsi_template = {
 	.eh_host_reset_handler	= atari_scsi_host_reset,
 	.this_id		= 7,
 	.cmd_per_lun		= 2,
-	.use_clustering		= DISABLE_CLUSTERING,
+	.dma_boundary		= PAGE_SIZE - 1,
 	.cmd_size		= NCR5380_CMD_SIZE,
 };
 
diff --git a/drivers/scsi/cxgbi/cxgb3i/cxgb3i.c b/drivers/scsi/cxgbi/cxgb3i/cxgb3i.c
index bf07735275a4..8a20411699d9 100644
--- a/drivers/scsi/cxgbi/cxgb3i/cxgb3i.c
+++ b/drivers/scsi/cxgbi/cxgb3i/cxgb3i.c
@@ -95,7 +95,7 @@ static struct scsi_host_template cxgb3i_host_template = {
 	.eh_device_reset_handler = iscsi_eh_device_reset,
 	.eh_target_reset_handler = iscsi_eh_recover_target,
 	.target_alloc	= iscsi_target_alloc,
-	.use_clustering	= DISABLE_CLUSTERING,
+	.dma_boundary	= PAGE_SIZE - 1,
 	.this_id	= -1,
 	.track_queue_depth = 1,
 };
diff --git a/drivers/scsi/cxgbi/cxgb4i/cxgb4i.c b/drivers/scsi/cxgbi/cxgb4i/cxgb4i.c
index 064ef5735182..762337de1116 100644
--- a/drivers/scsi/cxgbi/cxgb4i/cxgb4i.c
+++ b/drivers/scsi/cxgbi/cxgb4i/cxgb4i.c
@@ -113,7 +113,7 @@ static struct scsi_host_template cxgb4i_host_template = {
 	.eh_device_reset_handler = iscsi_eh_device_reset,
 	.eh_target_reset_handler = iscsi_eh_recover_target,
 	.target_alloc	= iscsi_target_alloc,
-	.use_clustering	= DISABLE_CLUSTERING,
+	.dma_boundary	= PAGE_SIZE - 1,
 	.this_id	= -1,
 	.track_queue_depth = 1,
 };
diff --git a/drivers/scsi/dc395x.c b/drivers/scsi/dc395x.c
index 8c55ec6e1827..13fbb2eab842 100644
--- a/drivers/scsi/dc395x.c
+++ b/drivers/scsi/dc395x.c
@@ -4631,7 +4631,7 @@ static struct scsi_host_template dc395x_driver_template = {
 	.cmd_per_lun            = DC395x_MAX_CMD_PER_LUN,
 	.eh_abort_handler       = dc395x_eh_abort,
 	.eh_bus_reset_handler   = dc395x_eh_bus_reset,
-	.use_clustering         = DISABLE_CLUSTERING,
+	.dma_boundary		= PAGE_SIZE - 1,
 };
 
 
diff --git a/drivers/scsi/dmx3191d.c b/drivers/scsi/dmx3191d.c
index 003c3d726238..8db1cc552932 100644
--- a/drivers/scsi/dmx3191d.c
+++ b/drivers/scsi/dmx3191d.c
@@ -63,7 +63,7 @@ static struct scsi_host_template dmx3191d_driver_template = {
 	.this_id		= 7,
 	.sg_tablesize		= SG_ALL,
 	.cmd_per_lun		= 2,
-	.use_clustering		= DISABLE_CLUSTERING,
+	.dma_boundary		= PAGE_SIZE - 1,
 	.cmd_size		= NCR5380_CMD_SIZE,
 };
 
diff --git a/drivers/scsi/g_NCR5380.c b/drivers/scsi/g_NCR5380.c
index fc538181f8df..9cdca0625498 100644
--- a/drivers/scsi/g_NCR5380.c
+++ b/drivers/scsi/g_NCR5380.c
@@ -700,7 +700,7 @@ static struct scsi_host_template driver_template = {
 	.this_id		= 7,
 	.sg_tablesize		= SG_ALL,
 	.cmd_per_lun		= 2,
-	.use_clustering		= DISABLE_CLUSTERING,
+	.dma_boundary		= PAGE_SIZE - 1,
 	.cmd_size		= NCR5380_CMD_SIZE,
 	.max_sectors		= 128,
 };
diff --git a/drivers/scsi/gvp11.c b/drivers/scsi/gvp11.c
index a27fc49ebd3a..d2acd0d826e2 100644
--- a/drivers/scsi/gvp11.c
+++ b/drivers/scsi/gvp11.c
@@ -184,7 +184,7 @@ static struct scsi_host_template gvp11_scsi_template = {
 	.this_id		= 7,
 	.sg_tablesize		= SG_ALL,
 	.cmd_per_lun		= CMD_PER_LUN,
-	.use_clustering		= DISABLE_CLUSTERING
+	.dma_boundary		= PAGE_SIZE - 1,
 };
 
 static int check_wd33c93(struct gvp11_scsiregs *regs)
diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c
index e8148ba414a3..fce0b5d7119e 100644
--- a/drivers/scsi/hosts.c
+++ b/drivers/scsi/hosts.c
@@ -431,7 +431,6 @@ struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *sht, int privsize)
 	shost->sg_prot_tablesize = sht->sg_prot_tablesize;
 	shost->cmd_per_lun = sht->cmd_per_lun;
 	shost->unchecked_isa_dma = sht->unchecked_isa_dma;
-	shost->use_clustering = sht->use_clustering;
 	shost->no_write_same = sht->no_write_same;
 
 	if (shost_eh_deadline == -1 || !sht->eh_host_reset_handler)
diff --git a/drivers/scsi/ips.c b/drivers/scsi/ips.c
index 067725295083..e8bc8d328bab 100644
--- a/drivers/scsi/ips.c
+++ b/drivers/scsi/ips.c
@@ -6677,7 +6677,6 @@ ips_register_scsi(int index)
 	sh->sg_tablesize = sh->hostt->sg_tablesize;
 	sh->can_queue = sh->hostt->can_queue;
 	sh->cmd_per_lun = sh->hostt->cmd_per_lun;
-	sh->use_clustering = sh->hostt->use_clustering;
 	sh->max_sectors = 128;
 
 	sh->max_id = ha->ntargets;
diff --git a/drivers/scsi/iscsi_tcp.c b/drivers/scsi/iscsi_tcp.c
index 23354f206533..0175684a14dc 100644
--- a/drivers/scsi/iscsi_tcp.c
+++ b/drivers/scsi/iscsi_tcp.c
@@ -980,7 +980,7 @@ static struct scsi_host_template iscsi_sw_tcp_sht = {
 	.eh_abort_handler       = iscsi_eh_abort,
 	.eh_device_reset_handler= iscsi_eh_device_reset,
 	.eh_target_reset_handler = iscsi_eh_recover_target,
-	.use_clustering         = DISABLE_CLUSTERING,
+	.dma_boundary		= PAGE_SIZE - 1,
 	.slave_alloc            = iscsi_sw_tcp_slave_alloc,
 	.slave_configure        = iscsi_sw_tcp_slave_configure,
 	.target_alloc		= iscsi_target_alloc,
diff --git a/drivers/scsi/mac_esp.c b/drivers/scsi/mac_esp.c
index 764d320bb2ca..ee741207fd4e 100644
--- a/drivers/scsi/mac_esp.c
+++ b/drivers/scsi/mac_esp.c
@@ -307,7 +307,7 @@ static int esp_mac_probe(struct platform_device *dev)
 		goto fail;
 
 	host->max_id = 8;
-	host->use_clustering = DISABLE_CLUSTERING;
+	host->dma_boundary = PAGE_SIZE - 1;
 	esp = shost_priv(host);
 
 	esp->host = host;
diff --git a/drivers/scsi/mac_scsi.c b/drivers/scsi/mac_scsi.c
index dd6057359d7c..8b4b5b1a13d7 100644
--- a/drivers/scsi/mac_scsi.c
+++ b/drivers/scsi/mac_scsi.c
@@ -333,7 +333,7 @@ static struct scsi_host_template mac_scsi_template = {
 	.this_id		= 7,
 	.sg_tablesize		= 1,
 	.cmd_per_lun		= 2,
-	.use_clustering		= DISABLE_CLUSTERING,
+	.dma_boundary		= PAGE_SIZE - 1,
 	.cmd_size		= NCR5380_CMD_SIZE,
 	.max_sectors		= 128,
 };
diff --git a/drivers/scsi/mvumi.c b/drivers/scsi/mvumi.c
index d0c3f867fc58..dbe753fba486 100644
--- a/drivers/scsi/mvumi.c
+++ b/drivers/scsi/mvumi.c
@@ -2197,7 +2197,7 @@ static struct scsi_host_template mvumi_template = {
 	.eh_timed_out = mvumi_timed_out,
 	.eh_host_reset_handler = mvumi_host_reset,
 	.bios_param = mvumi_bios_param,
-	.use_clustering = DISABLE_CLUSTERING,
+	.dma_boundary = PAGE_SIZE - 1,
 	.this_id = -1,
 };
 
diff --git a/drivers/scsi/nsp32.c b/drivers/scsi/nsp32.c
index 5aac3e801903..00e3cbee55b8 100644
--- a/drivers/scsi/nsp32.c
+++ b/drivers/scsi/nsp32.c
@@ -274,7 +274,7 @@ static struct scsi_host_template nsp32_template = {
 	.sg_tablesize			= NSP32_SG_SIZE,
 	.max_sectors			= 128,
 	.this_id			= NSP32_HOST_SCSIID,
-	.use_clustering			= DISABLE_CLUSTERING,
+	.dma_boundary			= PAGE_SIZE - 1,
 	.eh_abort_handler		= nsp32_eh_abort,
 	.eh_host_reset_handler		= nsp32_eh_host_reset,
 /*	.highmem_io			= 1, */
diff --git a/drivers/scsi/pcmcia/nsp_cs.c b/drivers/scsi/pcmcia/nsp_cs.c
index f3230494a8c9..1bd6825a4f14 100644
--- a/drivers/scsi/pcmcia/nsp_cs.c
+++ b/drivers/scsi/pcmcia/nsp_cs.c
@@ -86,7 +86,7 @@ static struct scsi_host_template nsp_driver_template = {
 	.can_queue		 = 1,
 	.this_id		 = NSP_INITIATOR_ID,
 	.sg_tablesize		 = SG_ALL,
-	.use_clustering		 = DISABLE_CLUSTERING,
+	.dma_boundary		 = PAGE_SIZE - 1,
 };
 
 static nsp_hw_data nsp_data_base; /* attach <-> detect glue */
diff --git a/drivers/scsi/pcmcia/qlogic_stub.c b/drivers/scsi/pcmcia/qlogic_stub.c
index 173351a8554b..828d53faf09a 100644
--- a/drivers/scsi/pcmcia/qlogic_stub.c
+++ b/drivers/scsi/pcmcia/qlogic_stub.c
@@ -72,7 +72,7 @@ static struct scsi_host_template qlogicfas_driver_template = {
 	.can_queue		= 1,
 	.this_id		= -1,
 	.sg_tablesize		= SG_ALL,
-	.use_clustering		= DISABLE_CLUSTERING,
+	.dma_boundary		= PAGE_SIZE - 1,
 };
 
 /*====================================================================*/
diff --git a/drivers/scsi/qlogicfas.c b/drivers/scsi/qlogicfas.c
index 95431d605c24..8f709002f746 100644
--- a/drivers/scsi/qlogicfas.c
+++ b/drivers/scsi/qlogicfas.c
@@ -193,7 +193,7 @@ static struct scsi_host_template qlogicfas_driver_template = {
 	.can_queue		= 1,
 	.this_id		= -1,
 	.sg_tablesize		= SG_ALL,
-	.use_clustering		= DISABLE_CLUSTERING,
+	.dma_boundary		= PAGE_SIZE - 1,
 };
 
 static __init int qlogicfas_init(void)
diff --git a/drivers/scsi/scsi_debug.c b/drivers/scsi/scsi_debug.c
index 57d418d7d74e..16cab45c0439 100644
--- a/drivers/scsi/scsi_debug.c
+++ b/drivers/scsi/scsi_debug.c
@@ -5866,7 +5866,8 @@ static int sdebug_driver_probe(struct device *dev)
 
 	sdebug_driver_template.can_queue = sdebug_max_queue;
 	if (!sdebug_clustering)
-		sdebug_driver_template.use_clustering = DISABLE_CLUSTERING;
+		sdebug_driver_template.dma_boundary = PAGE_SIZE - 1;
+
 	hpnt = scsi_host_alloc(&sdebug_driver_template, sizeof(sdbg_host));
 	if (NULL == hpnt) {
 		pr_err("scsi_host_alloc failed\n");
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 2d4fd6b4bd92..966b7cfebdf8 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -2230,9 +2230,6 @@ void __scsi_init_queue(struct Scsi_Host *shost, struct request_queue *q)
 	blk_queue_max_segment_size(q,
 		min(shost->max_segment_size, dma_get_max_seg_size(dev)));
 
-	if (shost->use_clustering == DISABLE_CLUSTERING)
-		q->limits.cluster = 0;
-
 	/*
 	 * Set a reasonable default alignment:  The larger of 32-byte (dword),
 	 * which is a common minimum for HBAs, and the minimum DMA alignment,
diff --git a/drivers/scsi/sgiwd93.c b/drivers/scsi/sgiwd93.c
index 5ed696dc9bbd..713bce998b0e 100644
--- a/drivers/scsi/sgiwd93.c
+++ b/drivers/scsi/sgiwd93.c
@@ -208,7 +208,7 @@ static struct scsi_host_template sgiwd93_template = {
 	.this_id		= 7,
 	.sg_tablesize		= SG_ALL,
 	.cmd_per_lun		= 8,
-	.use_clustering		= DISABLE_CLUSTERING,
+	.dma_boundary		= PAGE_SIZE - 1,
 };
 
 static int sgiwd93_probe(struct platform_device *pdev)
diff --git a/drivers/scsi/stex.c b/drivers/scsi/stex.c
index af9078320d4b..f6bef7ad65e7 100644
--- a/drivers/scsi/stex.c
+++ b/drivers/scsi/stex.c
@@ -1489,7 +1489,7 @@ static struct scsi_host_template driver_template = {
 	.eh_abort_handler		= stex_abort,
 	.eh_host_reset_handler		= stex_reset,
 	.this_id			= -1,
-	.use_clustering			= DISABLE_CLUSTERING,
+	.dma_boundary			= PAGE_SIZE - 1,
 };
 
 static struct pci_device_id stex_pci_tbl[] = {
diff --git a/drivers/scsi/sun3_scsi.c b/drivers/scsi/sun3_scsi.c
index 9492638296c8..95a7ea7eefa0 100644
--- a/drivers/scsi/sun3_scsi.c
+++ b/drivers/scsi/sun3_scsi.c
@@ -500,7 +500,7 @@ static struct scsi_host_template sun3_scsi_template = {
 	.this_id		= 7,
 	.sg_tablesize		= SG_NONE,
 	.cmd_per_lun		= 2,
-	.use_clustering		= DISABLE_CLUSTERING,
+	.dma_boundary		= PAGE_SIZE - 1,
 	.cmd_size		= NCR5380_CMD_SIZE,
 };
 
diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index e5800da0053d..34be397da0f3 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -6982,7 +6982,7 @@ static struct scsi_host_template ufshcd_driver_template = {
 	.max_host_blocked	= 1,
 	.track_queue_depth	= 1,
 	.sdev_groups		= ufshcd_driver_groups,
-	.use_clustering		= DISABLE_CLUSTERING,
+	.dma_boundary		= PAGE_SIZE - 1,
 };
 
 static int ufshcd_config_vreg_load(struct device *dev, struct ufs_vreg *vreg,
diff --git a/drivers/target/loopback/tcm_loop.c b/drivers/target/loopback/tcm_loop.c
index b0991e86587f..7bd7c0c0db6f 100644
--- a/drivers/target/loopback/tcm_loop.c
+++ b/drivers/target/loopback/tcm_loop.c
@@ -324,7 +324,7 @@ static struct scsi_host_template tcm_loop_driver_template = {
 	.sg_tablesize		= 256,
 	.cmd_per_lun		= 1024,
 	.max_sectors		= 0xFFFF,
-	.use_clustering		= DISABLE_CLUSTERING,
+	.dma_boundary		= PAGE_SIZE - 1,
 	.slave_alloc		= tcm_loop_slave_alloc,
 	.module			= THIS_MODULE,
 	.track_queue_depth	= 1,
diff --git a/drivers/usb/storage/uas.c b/drivers/usb/storage/uas.c
index 6c75a0a50b3a..36742e8e7edc 100644
--- a/drivers/usb/storage/uas.c
+++ b/drivers/usb/storage/uas.c
@@ -879,7 +879,7 @@ static struct scsi_host_template uas_host_template = {
 	.this_id = -1,
 	.sg_tablesize = SG_NONE,
 	.skip_settle_delay = 1,
-	.use_clustering = DISABLE_CLUSTERING,
+	.dma_boundary = PAGE_SIZE - 1,
 };
 
 #define UNUSUAL_DEV(id_vendor, id_product, bcdDeviceMin, bcdDeviceMax, \
diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h
index 834204681ca3..7ba34a0ca8bf 100644
--- a/include/scsi/scsi_host.h
+++ b/include/scsi/scsi_host.h
@@ -44,8 +44,6 @@ struct blk_queue_tags;
 #define MODE_INITIATOR 0x01
 #define MODE_TARGET 0x02
 
-#define DISABLE_CLUSTERING (-1)
-
 struct scsi_host_template {
 	struct module *module;
 	const char *name;
@@ -418,16 +416,6 @@ struct scsi_host_template {
 	 */
 	unsigned unchecked_isa_dma:1;
 
-	/*
-	 * True if this host adapter can make good use of clustering.
-	 * I originally thought that if the tablesize was large that it
-	 * was a waste of CPU cycles to prepare a cluster list, but
-	 * it works out that the Buslogic is faster if you use a smaller
-	 * number of segments (i.e. use clustering).  I guess it is
-	 * inefficient.
-	 */
-	unsigned use_clustering:1;
-
 	/*
 	 * True for emulated SCSI host adapters (e.g. ATAPI).
 	 */
@@ -626,7 +614,6 @@ struct Scsi_Host {
 	
 	unsigned active_mode:2;
 	unsigned unchecked_isa_dma:1;
-	unsigned use_clustering:1;
 
 	/*
 	 * Host has requested that no further requests come through for the
-- 
2.19.2

[PATCH 10/10] block: remove the cluster flag

[Christoph Hellwig]

Now that the the SCSI layer replaced the use of the cluster flag with
segment size limits and the DMA boundary we can remove the cluster
flag from the block layer.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 block/blk-merge.c      | 18 +++++++-----------
 block/blk-settings.c   |  3 ---
 block/blk-sysfs.c      |  5 +----
 include/linux/blkdev.h |  6 ------
 4 files changed, 8 insertions(+), 24 deletions(-)

diff --git a/block/blk-merge.c b/block/blk-merge.c
index 6b5ad275ed56..4478d53cc6ee 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -194,7 +194,7 @@ static struct bio *blk_bio_segment_split(struct request_queue *q,
 			goto split;
 		}
 
-		if (bvprvp && blk_queue_cluster(q)) {
+		if (bvprvp) {
 			if (seg_size + bv.bv_len > queue_max_segment_size(q))
 				goto new_segment;
 			if (!biovec_phys_mergeable(q, bvprvp, &bv))
@@ -294,7 +294,7 @@ static unsigned int __blk_recalc_rq_segments(struct request_queue *q,
 					     bool no_sg_merge)
 {
 	struct bio_vec bv, bvprv = { NULL };
-	int cluster, prev = 0;
+	int prev = 0;
 	unsigned int seg_size, nr_phys_segs;
 	struct bio *fbio, *bbio;
 	struct bvec_iter iter;
@@ -312,7 +312,6 @@ static unsigned int __blk_recalc_rq_segments(struct request_queue *q,
 	}
 
 	fbio = bio;
-	cluster = blk_queue_cluster(q);
 	seg_size = 0;
 	nr_phys_segs = 0;
 	for_each_bio(bio) {
@@ -324,7 +323,7 @@ static unsigned int __blk_recalc_rq_segments(struct request_queue *q,
 			if (no_sg_merge)
 				goto new_segment;
 
-			if (prev && cluster) {
+			if (prev) {
 				if (seg_size + bv.bv_len
 				    > queue_max_segment_size(q))
 					goto new_segment;
@@ -395,9 +394,6 @@ static int blk_phys_contig_segment(struct request_queue *q, struct bio *bio,
 {
 	struct bio_vec end_bv = { NULL }, nxt_bv;
 
-	if (!blk_queue_cluster(q))
-		return 0;
-
 	if (bio->bi_seg_back_size + nxt->bi_seg_front_size >
 	    queue_max_segment_size(q))
 		return 0;
@@ -414,12 +410,12 @@ static int blk_phys_contig_segment(struct request_queue *q, struct bio *bio,
 static inline void
 __blk_segment_map_sg(struct request_queue *q, struct bio_vec *bvec,
 		     struct scatterlist *sglist, struct bio_vec *bvprv,
-		     struct scatterlist **sg, int *nsegs, int *cluster)
+		     struct scatterlist **sg, int *nsegs)
 {
 
 	int nbytes = bvec->bv_len;
 
-	if (*sg && *cluster) {
+	if (*sg) {
 		if ((*sg)->length + nbytes > queue_max_segment_size(q))
 			goto new_segment;
 		if (!biovec_phys_mergeable(q, bvprv, bvec))
@@ -465,12 +461,12 @@ static int __blk_bios_map_sg(struct request_queue *q, struct bio *bio,
 {
 	struct bio_vec bvec, bvprv = { NULL };
 	struct bvec_iter iter;
-	int cluster = blk_queue_cluster(q), nsegs = 0;
+	int nsegs = 0;
 
 	for_each_bio(bio)
 		bio_for_each_segment(bvec, bio, iter)
 			__blk_segment_map_sg(q, &bvec, sglist, &bvprv, sg,
-					     &nsegs, &cluster);
+					     &nsegs);
 
 	return nsegs;
 }
diff --git a/block/blk-settings.c b/block/blk-settings.c
index 696c04c1ab6c..9c8b62f8c180 100644
--- a/block/blk-settings.c
+++ b/block/blk-settings.c
@@ -109,7 +109,6 @@ void blk_set_default_limits(struct queue_limits *lim)
 	lim->alignment_offset = 0;
 	lim->io_opt = 0;
 	lim->misaligned = 0;
-	lim->cluster = 1;
 	lim->zoned = BLK_ZONED_NONE;
 }
 EXPORT_SYMBOL(blk_set_default_limits);
@@ -602,8 +601,6 @@ int blk_stack_limits(struct queue_limits *t, struct queue_limits *b,
 	t->io_min = max(t->io_min, b->io_min);
 	t->io_opt = lcm_not_zero(t->io_opt, b->io_opt);
 
-	t->cluster &= b->cluster;
-
 	/* Physical block size a multiple of the logical block size? */
 	if (t->physical_block_size & (t->logical_block_size - 1)) {
 		t->physical_block_size = t->logical_block_size;
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 844a454a7b3a..5144707f25ea 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -136,10 +136,7 @@ static ssize_t queue_max_integrity_segments_show(struct request_queue *q, char *
 
 static ssize_t queue_max_segment_size_show(struct request_queue *q, char *page)
 {
-	if (blk_queue_cluster(q))
-		return queue_var_show(queue_max_segment_size(q), (page));
-
-	return queue_var_show(PAGE_SIZE, (page));
+	return queue_var_show(queue_max_segment_size(q), (page));
 }
 
 static ssize_t queue_logical_block_size_show(struct request_queue *q, char *page)
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 4293dc1cd160..653ae90eec0b 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -389,7 +389,6 @@ struct queue_limits {
 
 	unsigned char		misaligned;
 	unsigned char		discard_misaligned;
-	unsigned char		cluster;
 	unsigned char		raid_partial_stripes_expensive;
 	enum blk_zoned_model	zoned;
 };
@@ -785,11 +784,6 @@ static inline bool queue_is_rq_based(struct request_queue *q)
 	return q->request_fn || q->mq_ops;
 }
 
-static inline unsigned int blk_queue_cluster(struct request_queue *q)
-{
-	return q->limits.cluster;
-}
-
 static inline enum blk_zoned_model
 blk_queue_zoned_model(struct request_queue *q)
 {
-- 
2.19.2

Re: remove the "clustering" flag V2

[Christoph Hellwig]

Martin and others:

can we get this reviewed and merge before the end of the merge window?
That gets the clustering put of the way for the multipage-biovec work
from Ming which we want to land in the block tree early in the next
merge window.

Re: remove the "clustering" flag V2

[Hannes Reinecke]

On 12/18/18 8:08 AM, Christoph Hellwig wrote:
> Martin and others:
> 
> can we get this reviewed and merge before the end of the merge window?
> That gets the clustering put of the way for the multipage-biovec work
> from Ming which we want to land in the block tree early in the next
> merge window.
> 
Have we reviewed the crash in iscsi target?
It might be something completely different, but the fact still stands 
that the bug is exposed after removing the clustering flag...

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		               zSeries & Storage
hare@suse.com			               +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: F. Imendörffer, J. Smithard, D. Upmanyu, G. Norton
HRB 21284 (AG Nürnberg)

Re: remove the "clustering" flag V2

[Christoph Hellwig]

On Tue, Dec 18, 2018 at 08:47:48AM +0100, Hannes Reinecke wrote:
> On 12/18/18 8:08 AM, Christoph Hellwig wrote:
>> Martin and others:
>>
>> can we get this reviewed and merge before the end of the merge window?
>> That gets the clustering put of the way for the multipage-biovec work
>> from Ming which we want to land in the block tree early in the next
>> merge window.
>>
> Have we reviewed the crash in iscsi target?
> It might be something completely different, but the fact still stands that 
> the bug is exposed after removing the clustering flag...

There is no change in behavior for the drivers, it just uses a
different know to archive the same thing.  The crashes in the iSCSI
target are if we remove the nob entirely on the initiator, but that
is not what this series does.

Re: remove the "clustering" flag V2

[Martin K. Petersen]

Christoph,

> can we get this reviewed and merge before the end of the merge window?
> That gets the clustering put of the way for the multipage-biovec work
> from Ming which we want to land in the block tree early in the next
> merge window.

I have been somewhat hesitant to apply this just before the merge
window.  However, I did go through it fairly carefully and since it's a
mostly mechanical change, I did apply it.

There were a few things I needed to tweak by hand and patch 9 forgot to
update myrs and myrb.

I left patch 10 for Jens to merge later (unless he acks it for me to
pull in).

-- 
Martin K. Petersen	Oracle Linux Engineering

Re: remove the "clustering" flag V2

[Jens Axboe]

On 12/18/18 9:23 PM, Martin K. Petersen wrote:
> 
> Christoph,
> 
>> can we get this reviewed and merge before the end of the merge window?
>> That gets the clustering put of the way for the multipage-biovec work
>> from Ming which we want to land in the block tree early in the next
>> merge window.
> 
> I have been somewhat hesitant to apply this just before the merge
> window.  However, I did go through it fairly carefully and since it's a
> mostly mechanical change, I did apply it.
> 
> There were a few things I needed to tweak by hand and patch 9 forgot to
> update myrs and myrb.
> 
> I left patch 10 for Jens to merge later (unless he acks it for me to
> pull in).

You can add my reviewed-by to 10 and add that one too, that makes more
sense than me adding it for a post-merge pull. But either way works
for me.

-- 
Jens Axboe

Re: remove the "clustering" flag V2

[Martin K. Petersen]

Jens,

> You can add my reviewed-by to 10 and add that one too, that makes more
> sense than me adding it for a post-merge pull. But either way works
> for me.

OK, done.

-- 
Martin K. Petersen	Oracle Linux Engineering

Re: remove the "clustering" flag V2

[Christoph Hellwig]

On Tue, Dec 18, 2018 at 11:23:32PM -0500, Martin K. Petersen wrote:
> 
> Christoph,
> 
> > can we get this reviewed and merge before the end of the merge window?
> > That gets the clustering put of the way for the multipage-biovec work
> > from Ming which we want to land in the block tree early in the next
> > merge window.
> 
> I have been somewhat hesitant to apply this just before the merge
> window.  However, I did go through it fairly carefully and since it's a
> mostly mechanical change, I did apply it.
> 
> There were a few things I needed to tweak by hand and patch 9 forgot to
> update myrs and myrb.

Hmm, there should have been two patches to drop these flags entirely
for those, given that the DAC960 driver didn't have any such
limitations.  Not sure why those got skipped.  But I'll send follow ons
for that.