IB/iser: Support up to 16MB data transfer in a single command

Maximum supported IO size is 8MB for the iSER driver. The current value is
limited by the ISCSI_ISER_MAX_SG_TABLESIZE macro. But the driver is able
to handle 16MB IOs without any significant changes. Increasing this limit
can be useful for the storage arrays which are fine tuned for IOs larger
than 8 MB.

This commit allows to configure maximum IO size up to 16MB using the
max_sectors module parameter.

Link: https://lore.kernel.org/r/20190912103534.18210-1-sergeygo@mellanox.comSigned-off-by: Sergey Gorenko <sergeygo@mellanox.com>
Reviewed-by: Max Gurtovoy <maxg@mellanox.com>
Acked-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

drivers/infiniband/ulp/iser/iscsi_iser.h

@@ -102,9 +102,10 @@
 
 /* Default support is 512KB I/O size */
 #define ISER_DEF_MAX_SECTORS		1024
-#define ISCSI_ISER_DEF_SG_TABLESIZE	((ISER_DEF_MAX_SECTORS * 512) >> SHIFT_4K)
-/* Maximum support is 8MB I/O size */
-#define ISCSI_ISER_MAX_SG_TABLESIZE	((16384 * 512) >> SHIFT_4K)
+#define ISCSI_ISER_DEF_SG_TABLESIZE                                            \
+	((ISER_DEF_MAX_SECTORS * SECTOR_SIZE) >> SHIFT_4K)
+/* Maximum support is 16MB I/O size */
+#define ISCSI_ISER_MAX_SG_TABLESIZE	((32768 * SECTOR_SIZE) >> SHIFT_4K)
 
 #define ISER_DEF_XMIT_CMDS_DEFAULT		512
 #if ISCSI_DEF_XMIT_CMDS_MAX > ISER_DEF_XMIT_CMDS_DEFAULT