[PATCH 2/2] rds: add functionality to print MR related information

[Manjunath Patil <manjunath.b.patil@oracle.com>]

RDS keeps its own pool of limited MRs[Memory Regions taken from ib
device for rdma operation] which are shared by RDS applications. Now, we
can print the applications along with their usage of MRs from userspace
using 'rds-info -m' command. This would help in tracking the limited
MRs.

MR related information is stored in rds_sock. This patch exposes the
information to userspace using rds-info command. The usage is limited to
CAP_NET_ADMIN privilege.

sample output:
 # rds-info -m

RDS MRs:
Program          PID    MR-gets    MR-puts    MR-inuse   <IP,port,ToS>
rds-stress       17743  28468      28464      4          <192.168.18..
rds-stress       17744  19385      19381      4          <192.168.18..

Signed-off-by: Manjunath Patil <manjunath.b.patil@oracle.com>
Reviewed-by: Ka-cheong Poon <ka-cheong.poon@oracle.com>
---
 include/uapi/linux/rds.h | 13 ++++++++++++-
 net/rds/af_rds.c         | 38 ++++++++++++++++++++++++++++++++++++++
 net/rds/ib.c             |  1 +
 net/rds/rds.h            |  4 +++-
 4 files changed, 54 insertions(+), 2 deletions(-)

diff --git a/include/uapi/linux/rds.h b/include/uapi/linux/rds.h
index cba368e55863..a6e8e28d95fb 100644
--- a/include/uapi/linux/rds.h
+++ b/include/uapi/linux/rds.h
@@ -134,8 +134,9 @@ typedef __u8	rds_tos_t;
 #define RDS6_INFO_SOCKETS		10015
 #define RDS6_INFO_TCP_SOCKETS		10016
 #define RDS6_INFO_IB_CONNECTIONS	10017
+#define RDS_INFO_MRS			10018
 
-#define RDS_INFO_LAST			10017
+#define RDS_INFO_LAST			10018
 
 struct rds_info_counter {
 	__u8	name[32];
@@ -270,6 +271,16 @@ struct rds6_info_rdma_connection {
 	__u32		cache_allocs;
 };
 
+struct rds_info_mr {
+	__u32		pid;
+	__u8		comm[TASK_COMM_LEN];
+	__u64		gets;
+	__u64		puts;
+	struct in6_addr	laddr;
+	__be16		lport;
+	__u8		tos;
+} __attribute__((packed));
+
 /* RDS message Receive Path Latency points */
 enum rds_message_rxpath_latency {
 	RDS_MSG_RX_HDR_TO_DGRAM_START = 0,
diff --git a/net/rds/af_rds.c b/net/rds/af_rds.c
index e291095e5224..c81acf1a9457 100644
--- a/net/rds/af_rds.c
+++ b/net/rds/af_rds.c
@@ -486,6 +486,7 @@ static int rds_getsockopt(struct socket *sock, int level, int optname,
 			  char __user *optval, int __user *optlen)
 {
 	struct rds_sock *rs = rds_sk_to_rs(sock->sk);
+	struct net *net = sock_net(sock->sk);
 	int ret = -ENOPROTOOPT, len;
 	int trans;
 
@@ -499,6 +500,11 @@ static int rds_getsockopt(struct socket *sock, int level, int optname,
 
 	switch (optname) {
 	case RDS_INFO_FIRST ... RDS_INFO_LAST:
+		if (optname == RDS_INFO_MRS &&
+		    !ns_capable(net->user_ns, CAP_NET_ADMIN)) {
+			ret = -EACCES;
+			break;
+		}
 		ret = rds_info_getsockopt(sock, optname, optval,
 					  optlen);
 		break;
@@ -878,6 +884,38 @@ static void rds6_sock_info(struct socket *sock, unsigned int len,
 }
 #endif
 
+void rds_info_mrs(struct socket *sock, unsigned int len,
+		  struct rds_info_iterator *iter,
+		  struct rds_info_lengths *lens)
+{
+	struct rds_sock *rs;
+	struct rds_info_mr mr_info;
+	unsigned int total = 0;
+
+	len /= sizeof(mr_info);
+
+	spin_lock_bh(&rds_sock_lock);
+	list_for_each_entry(rs, &rds_sock_list, rs_item) {
+		total++;
+		if (total <= len) {
+			memset(&mr_info, 0, sizeof(mr_info));
+			mr_info.pid = rs->rs_pid;
+			strncpy(mr_info.comm, rs->rs_comm, TASK_COMM_LEN);
+			mr_info.gets = atomic64_read(&rs->rs_mr_gets);
+			mr_info.puts = atomic64_read(&rs->rs_mr_puts);
+			mr_info.laddr = rs->rs_bound_addr;
+			mr_info.lport = rs->rs_bound_port;
+			mr_info.tos = rs->rs_tos;
+			rds_info_copy(iter, &mr_info, sizeof(mr_info));
+		}
+	}
+	spin_unlock_bh(&rds_sock_lock);
+
+	lens->nr = total;
+	lens->each = sizeof(mr_info);
+}
+EXPORT_SYMBOL_GPL(rds_info_mrs);
+
 static void rds_exit(void)
 {
 	sock_unregister(rds_family_ops.family);
diff --git a/net/rds/ib.c b/net/rds/ib.c
index a792d8a3872a..48476ae95da9 100644
--- a/net/rds/ib.c
+++ b/net/rds/ib.c
@@ -599,6 +599,7 @@ int rds_ib_init(void)
 	rds_trans_register(&rds_ib_transport);
 
 	rds_info_register_func(RDS_INFO_IB_CONNECTIONS, rds_ib_ic_info);
+	rds_info_register_func(RDS_INFO_MRS, rds_info_mrs);
 #if IS_ENABLED(CONFIG_IPV6)
 	rds_info_register_func(RDS6_INFO_IB_CONNECTIONS, rds6_ib_ic_info);
 #endif
diff --git a/net/rds/rds.h b/net/rds/rds.h
index 5e61868e1799..dd42bc95bbeb 100644
--- a/net/rds/rds.h
+++ b/net/rds/rds.h
@@ -746,7 +746,9 @@ static inline void __rds_wake_sk_sleep(struct sock *sk)
 		wake_up(waitq);
 }
 extern wait_queue_head_t rds_poll_waitq;
-
+void rds_info_mrs(struct socket *sock, unsigned int len,
+		  struct rds_info_iterator *iter,
+		  struct rds_info_lengths *lens);
 
 /* bind.c */
 int rds_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len);
-- 
2.27.0.112.g101b320