IB/srp: Use the IB_DEVICE_SG_GAPS_REG HCA feature if supported

If a HCA supports the SG_GAPS_REG feature then fewer memory regions
are required per command. This patch reduces the number of memory
regions that is allocated per SRP session.

Signed-off-by: Sergey Gorenko <sergeygo@mellanox.com>
Reviewed-by: Max Gurtovoy <maxg@mellanox.com>
Tested-by: Laurence Oberman <loberman@redhat.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Acked-by: Bart Van Assche <bart.vanassche@wdc.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

diff --git a/drivers/infiniband/ulp/srp/ib_srp.c b/drivers/infiniband/ulp/srp/ib_srp.c
index d61f48a86508bc32b910516ad89b8b924df2268d..9a5ea625145071e5c381e8d22285574b46756cad 100644 (file)
--- a/drivers/infiniband/ulp/srp/ib_srp.c
+++ b/drivers/infiniband/ulp/srp/ib_srp.c
@@ -431,6 +431,7 @@ static struct srp_fr_pool *srp_create_fr_pool(struct ib_device *device,
        struct srp_fr_desc *d;
        struct ib_mr *mr;
        int i, ret = -EINVAL;
+       enum ib_mr_type mr_type;
 
        if (pool_size <= 0)
                goto err;
@@ -444,9 +445,13 @@ static struct srp_fr_pool *srp_create_fr_pool(struct ib_device *device,
        spin_lock_init(&pool->lock);
        INIT_LIST_HEAD(&pool->free_list);
 
+       if (device->attrs.device_cap_flags & IB_DEVICE_SG_GAPS_REG)
+               mr_type = IB_MR_TYPE_SG_GAPS;
+       else
+               mr_type = IB_MR_TYPE_MEM_REG;
+
        for (i = 0, d = &pool->desc[0]; i < pool->size; i++, d++) {
-               mr = ib_alloc_mr(pd, IB_MR_TYPE_MEM_REG,
-                                max_page_list_len);
+               mr = ib_alloc_mr(pd, mr_type, max_page_list_len);
                if (IS_ERR(mr)) {
                        ret = PTR_ERR(mr);
                        if (ret == -ENOMEM)
@@ -2996,8 +3001,9 @@ static int srp_slave_alloc(struct scsi_device *sdev)
        struct Scsi_Host *shost = sdev->host;
        struct srp_target_port *target = host_to_target(shost);
        struct srp_device *srp_dev = target->srp_host->srp_dev;
+       struct ib_device *ibdev = srp_dev->dev;
 
-       if (true)
+       if (!(ibdev->attrs.device_cap_flags & IB_DEVICE_SG_GAPS_REG))
                blk_queue_virt_boundary(sdev->request_queue,
                                        ~srp_dev->mr_page_mask);
 
@@ -3775,26 +3781,36 @@ static ssize_t srp_create_target(struct device *dev,
        }
 
        if (srp_dev->use_fast_reg || srp_dev->use_fmr) {
-               /*
-                * FR and FMR can only map one HCA page per entry. If the
-                * start address is not aligned on a HCA page boundary two
-                * entries will be used for the head and the tail although
-                * these two entries combined contain at most one HCA page of
-                * data. Hence the "+ 1" in the calculation below.
-                *
-                * The indirect data buffer descriptor is contiguous so the
-                * memory for that buffer will only be registered if
-                * register_always is true. Hence add one to mr_per_cmd if
-                * register_always has been set.
-                */
+               bool gaps_reg = (ibdev->attrs.device_cap_flags &
+                                IB_DEVICE_SG_GAPS_REG);
+
                max_sectors_per_mr = srp_dev->max_pages_per_mr <<
                                  (ilog2(srp_dev->mr_page_size) - 9);
-               mr_per_cmd = register_always +
-                       (target->scsi_host->max_sectors + 1 +
-                        max_sectors_per_mr - 1) / max_sectors_per_mr;
+               if (!gaps_reg) {
+                       /*
+                        * FR and FMR can only map one HCA page per entry. If
+                        * the start address is not aligned on a HCA page
+                        * boundary two entries will be used for the head and
+                        * the tail although these two entries combined
+                        * contain at most one HCA page of data. Hence the "+
+                        * 1" in the calculation below.
+                        *
+                        * The indirect data buffer descriptor is contiguous
+                        * so the memory for that buffer will only be
+                        * registered if register_always is true. Hence add
+                        * one to mr_per_cmd if register_always has been set.
+                        */
+                       mr_per_cmd = register_always +
+                               (target->scsi_host->max_sectors + 1 +
+                                max_sectors_per_mr - 1) / max_sectors_per_mr;
+               } else {
+                       mr_per_cmd = register_always +
+                               (target->sg_tablesize +
+                                srp_dev->max_pages_per_mr - 1) /
+                               srp_dev->max_pages_per_mr;
+               }
                pr_debug("max_sectors = %u; max_pages_per_mr = %u; mr_page_size = %u; max_sectors_per_mr = %u; mr_per_cmd = %u\n",
-                        target->scsi_host->max_sectors,
-                        srp_dev->max_pages_per_mr, srp_dev->mr_page_size,
+                        target->scsi_host->max_sectors, srp_dev->max_pages_per_mr, srp_dev->mr_page_size,
                         max_sectors_per_mr, mr_per_cmd);
        }