[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/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index c75cb6a..b6e6d80 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1645,7 +1645,10 @@
* 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