[SCSI] 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 <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h
index 7d210cd..0fd4746 100644
--- a/include/scsi/scsi_host.h
+++ b/include/scsi/scsi_host.h
@@ -39,6 +39,9 @@
#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,
@@ -443,6 +446,15 @@
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+ * Status: OBSOLETE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;
@@ -586,6 +598,7 @@
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