RDS: IB: add mr reused stats

Add MR reuse statistics to RDS IB transport.
Signed-off-by: NSantosh Shilimkar <ssantosh@kernel.org>
Signed-off-by: NSantosh Shilimkar <santosh.shilimkar@oracle.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/rds/ib.h

@@ -259,6 +259,8 @@ struct rds_ib_statistics {
 	uint64_t	s_ib_rdma_mr_1m_pool_flush;
 	uint64_t	s_ib_rdma_mr_1m_pool_wait;
 	uint64_t	s_ib_rdma_mr_1m_pool_depleted;
+	uint64_t	s_ib_rdma_mr_8k_reused;
+	uint64_t	s_ib_rdma_mr_1m_reused;
 	uint64_t	s_ib_atomic_cswp;
 	uint64_t	s_ib_atomic_fadd;
 };

net/rds/ib_rdma.c

@@ -188,8 +188,13 @@ struct rds_ib_mr *rds_ib_reuse_mr(struct rds_ib_mr_pool *pool)
 	flag = this_cpu_ptr(&clean_list_grace);
 	set_bit(CLEAN_LIST_BUSY_BIT, flag);
 	ret = llist_del_first(&pool->clean_list);
-	if (ret)
+	if (ret) {
 		ibmr = llist_entry(ret, struct rds_ib_mr, llnode);
+		if (pool->pool_type == RDS_IB_MR_8K_POOL)
+			rds_ib_stats_inc(s_ib_rdma_mr_8k_reused);
+		else
+			rds_ib_stats_inc(s_ib_rdma_mr_1m_reused);
+	}
 
 	clear_bit(CLEAN_LIST_BUSY_BIT, flag);
 	preempt_enable();

net/rds/ib_stats.c

@@ -73,6 +73,8 @@ static const char *const rds_ib_stat_names[] = {
 	"ib_rdma_mr_1m_pool_flush",
 	"ib_rdma_mr_1m_pool_wait",
 	"ib_rdma_mr_1m_pool_depleted",
+	"ib_rdma_mr_8k_reused",
+	"ib_rdma_mr_1m_reused",
 	"ib_atomic_cswp",
 	"ib_atomic_fadd",
 };