[Devel] [PATCH VZ9 v2 2/2] fs/fuse kio: introduce pcs_krpc - export kernel RPC to userspace

Liu Kui kui.liu at virtuozzo.com
Thu May 23 13:55:02 MSK 2024


Currently there are 2 connections for every RPC, one in userspace,
one in kernel. This wastes a lot of resources on client hosts in case
of a huge cluster. It's therefore desirable to eliminate connections
in userspace by using kernel RPC directly for userspace RPC.

This patch makes the pcs_fuse_kio module provide such functionality for
userspace to use. Major changes are:

- Introduce a new struct pcs_krpc, which links userspace RPC connection
directly to corresponding kernel RPC. It also provides execution context
for forwarding RPC messages from/to kernel RPC.
- Added several new cmds to the FUSE_IOC_KIO_CALL ioctl for pcs_krpc
management.
- Kernel RPC ops is changed to demux msgs to pcs_cs or pcs_krpc

https://pmc.acronis.work/browse/VSTOR-82613
Signed-off-by: Liu Kui <kui.liu at virtuozzo.com>
---
 fs/fuse/Makefile                   |   6 +-
 fs/fuse/dev.c                      |  19 +-
 fs/fuse/fuse_i.h                   |   2 +-
 fs/fuse/kio/pcs/pcs_cluster_core.c |   4 +
 fs/fuse/kio/pcs/pcs_cs.c           | 120 +----
 fs/fuse/kio/pcs/pcs_cs.h           |   5 +-
 fs/fuse/kio/pcs/pcs_fuse_kdirect.c |  96 +++-
 fs/fuse/kio/pcs/pcs_ioctl.h        |  29 ++
 fs/fuse/kio/pcs/pcs_krpc.c         | 794 +++++++++++++++++++++++++++++
 fs/fuse/kio/pcs/pcs_krpc.h         | 140 +++++
 fs/fuse/kio/pcs/pcs_krpc_prot.h    |  44 ++
 fs/fuse/kio/pcs/pcs_mr.c           |   4 +-
 fs/fuse/kio/pcs/pcs_req.h          |  30 +-
 fs/fuse/kio/pcs/pcs_rpc.c          |   3 +-
 fs/fuse/kio/pcs/pcs_rpc.h          |   4 +-
 fs/fuse/kio/pcs/pcs_rpc_clnt.c     | 188 +++++++
 fs/fuse/kio/pcs/pcs_rpc_clnt.h     |  16 +
 17 files changed, 1386 insertions(+), 118 deletions(-)
 create mode 100644 fs/fuse/kio/pcs/pcs_krpc.c
 create mode 100644 fs/fuse/kio/pcs/pcs_krpc.h
 create mode 100644 fs/fuse/kio/pcs/pcs_krpc_prot.h
 create mode 100644 fs/fuse/kio/pcs/pcs_rpc_clnt.c
 create mode 100644 fs/fuse/kio/pcs/pcs_rpc_clnt.h

diff --git a/fs/fuse/Makefile b/fs/fuse/Makefile
index 740c805adc2a..18eaa35a234b 100644
--- a/fs/fuse/Makefile
+++ b/fs/fuse/Makefile
@@ -33,7 +33,11 @@ fuse_kio_pcs-objs := kio/pcs/pcs_fuse_kdirect.o \
 	kio/pcs/pcs_rdma_rw.o \
 	kio/pcs/pcs_rdma_conn.o \
 	kio/pcs/pcs_net_addr.o \
-	kio/pcs/pcs_cs_accel.o
+	kio/pcs/pcs_cs_accel.o \
+	kio/pcs/pcs_rpc_clnt.o \
+	kio/pcs/pcs_mr.o \
+	kio/pcs/pcs_krpc.o
+
 fuse_kio_pcs_trace-objs := kio/pcs/fuse_kio_pcs_trace.o
 
 virtiofs-y := virtio_fs.o
diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index e00f5b180e95..bf54adf2bca9 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -2657,11 +2657,20 @@ static long fuse_dev_ioctl(struct file *file, unsigned int cmd,
 
 		if (copy_from_user(&req, (void __user *)arg, sizeof(req)))
 			return -EFAULT;
-		op = fuse_kio_get(NULL, req.name);
-		if (op == NULL)
-			return -EINVAL;
-		res = op->ioctl(NULL, NULL, req.cmd, req.data, req.len);
-		fuse_kio_put(op);
+
+		fud = fuse_get_dev(file);
+		if (fud) {
+			op = fud->fc->kio.op;
+			if (op == NULL)
+				return -EINVAL;
+			res = op->dev_ioctl(fud->fc, req.cmd, req.data, req.len);
+		} else {
+			op = fuse_kio_get(NULL, req.name);
+			if (op == NULL)
+				return -EINVAL;
+			res = op->ioctl(NULL, NULL, req.cmd, req.data, req.len);
+			fuse_kio_put(op);
+		}
 		break;
 	}
 	default:
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index 0c1bd5209dbc..090871a1e356 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -649,7 +649,7 @@ struct fuse_kio_ops {
 	void (*inode_release)(struct fuse_inode *fi);
 	void (*kill_requests)(struct fuse_conn *fc, struct inode *inode);
 	int  (*ioctl)(struct file *file, struct inode *inode, unsigned int cmd, unsigned long arg, int len);
-
+	int  (*dev_ioctl)(struct fuse_conn *fc, unsigned int cmd, unsigned long arg, int len);
 };
 int fuse_register_kio(struct fuse_kio_ops *ops);
 void fuse_unregister_kio(struct fuse_kio_ops *ops);
diff --git a/fs/fuse/kio/pcs/pcs_cluster_core.c b/fs/fuse/kio/pcs/pcs_cluster_core.c
index 8c34c60eb79a..6df2ccee9a1f 100644
--- a/fs/fuse/kio/pcs/pcs_cluster_core.c
+++ b/fs/fuse/kio/pcs/pcs_cluster_core.c
@@ -162,6 +162,8 @@ int pcs_cc_init(struct pcs_cluster_core *cc, struct workqueue_struct *wq,
 	cc->nilbuffer_kv.iov_len = sizeof(cc->nilbuffer);
 
 	pcs_csset_init(&cc->css);
+	pcs_mrset_init(&cc->mrs);
+	pcs_krpcset_init(&cc->krpcs);
 
 	err = pcs_mapset_init(cc);
 	if (err)
@@ -210,6 +212,8 @@ int pcs_cc_init(struct pcs_cluster_core *cc, struct workqueue_struct *wq,
 
 void pcs_cc_fini(struct pcs_cluster_core *cc)
 {
+	pcs_krpcset_fini(&cc->krpcs);
+	pcs_mrset_fini(&cc->mrs);
 	pcs_csset_fini(&cc->css);
 	pcs_mapset_fini(&cc->maps);
 	pcs_rpc_engine_fini(&cc->eng);
diff --git a/fs/fuse/kio/pcs/pcs_cs.c b/fs/fuse/kio/pcs/pcs_cs.c
index 6cc97aa3f9d0..a48c3fbfa5b7 100644
--- a/fs/fuse/kio/pcs/pcs_cs.c
+++ b/fs/fuse/kio/pcs/pcs_cs.c
@@ -25,7 +25,6 @@
 #include "log.h"
 #include "fuse_ktrace.h"
 #include "pcs_net_addr.h"
-
 /* Lock order: cs->lock -> css->lock (lru, hash, bl_list) */
 
 
@@ -39,22 +38,9 @@ struct pcs_rpc_params cn_rpc_params = {
 	.flags			= 0,
 };
 
-static void cs_aborting(struct pcs_rpc *ep, int error);
-static struct pcs_msg *cs_get_hdr(struct pcs_rpc *ep, struct pcs_rpc_hdr *h);
-static int cs_input(struct pcs_rpc *ep, struct pcs_msg *msg);
-static void cs_keep_waiting(struct pcs_rpc *ep, struct pcs_msg *req, struct pcs_msg *msg);
-static void cs_connect(struct pcs_rpc *ep);
 static void pcs_cs_isolate(struct pcs_cs *cs, struct list_head *dispose);
 static void pcs_cs_destroy(struct pcs_cs *cs);
 
-struct pcs_rpc_ops cn_rpc_ops = {
-	.demux_request		= cs_input,
-	.get_hdr		= cs_get_hdr,
-	.state_change		= cs_aborting,
-	.keep_waiting		= cs_keep_waiting,
-	.connect		= cs_connect,
-};
-
 static int pcs_cs_percpu_stat_alloc(struct pcs_cs *cs)
 {
 	seqlock_init(&cs->stat.seqlock);
@@ -124,8 +110,7 @@ static void pcs_cs_percpu_stat_free(struct pcs_cs *cs)
 	free_percpu(cs->stat.iolat);
 }
 
-struct pcs_cs *pcs_cs_alloc(struct pcs_cs_set *css,
-			     struct pcs_cluster_core *cc)
+struct pcs_cs *pcs_cs_alloc(struct pcs_cs_set *css)
 {
 	struct pcs_cs *cs;
 
@@ -153,13 +138,6 @@ struct pcs_cs *pcs_cs_alloc(struct pcs_cs_set *css,
 	    kfree(cs);
 	    return NULL;
 	}
-	cs->rpc = pcs_rpc_create(&cc->eng, &cn_rpc_params, &cn_rpc_ops);
-	if (cs->rpc == NULL) {
-		pcs_cs_percpu_stat_free(cs);
-		kfree(cs);
-		return NULL;
-	}
-	cs->rpc->private = cs;
 	INIT_LIST_HEAD(&cs->map_list);
 	return cs;
 }
@@ -222,6 +200,7 @@ struct pcs_cs *pcs_cs_find_create(struct pcs_cs_set *csset, PCS_NODE_ID_T *id, P
 		/* If rpc is connected, leave it connected until failure.
 		 * After current connect fails, reconnect will be done to new address
 		 */
+		struct pcs_rpc *rpc = cs->rpc;
 		if (addr) {
 			if (addr->type != PCS_ADDRTYPE_NONE) {
 				if (pcs_netaddr_cmp(&cs->addr, addr)) {
@@ -231,7 +210,7 @@ struct pcs_cs *pcs_cs_find_create(struct pcs_cs_set *csset, PCS_NODE_ID_T *id, P
 					FUSE_KTRACE(cc_from_csset(csset)->fc,
 						    "Port change CS" NODE_FMT " seq=%d",
 						    NODE_ARGS(*id), cs->addr_serno);
-					pcs_rpc_set_address(cs->rpc, addr);
+					pcs_rpc_set_address(rpc, addr);
 
 					if (!(flags & CS_FL_INACTIVE)) {
 						pcs_map_notify_addr_change(cs);
@@ -246,30 +225,31 @@ struct pcs_cs *pcs_cs_find_create(struct pcs_cs_set *csset, PCS_NODE_ID_T *id, P
 			}
 		}
 		if (flags & CS_FL_LOCAL_SOCK)
-			cs->rpc->flags |= PCS_RPC_F_LOCAL;
+			rpc->flags |= PCS_RPC_F_LOCAL;
 		else
-			cs->rpc->flags &= ~PCS_RPC_F_LOCAL;
+			rpc->flags &= ~PCS_RPC_F_LOCAL;
 		return cs;
 	}
 	BUG_ON(addr == NULL);
 
-	cs = pcs_cs_alloc(csset, cc_from_csset(csset));
+	cs = pcs_cs_alloc(csset);
 	if (!cs)
 		return NULL;
 
+	cs->rpc = pcs_rpc_clnt_create(&cc_from_csset(csset)->eng, id, addr, flags);
+
+	if (!cs->rpc) {
+		pcs_cs_percpu_stat_free(cs);
+		kfree(cs);
+		return NULL;
+	}
+	cs->rpc->clnt_cs = cs;
+
 	cs->id = *id;
 
 	cs->addr = *addr;
 	cs->addr_serno = 1;
 
-	pcs_rpc_set_peer_id(cs->rpc, id, PCS_NODE_ROLE_CS);
-	pcs_rpc_set_address(cs->rpc, addr);
-
-	if (flags & CS_FL_LOCAL_SOCK)
-		cs->rpc->flags |= PCS_RPC_F_LOCAL;
-	else
-		cs->rpc->flags &= ~PCS_RPC_F_LOCAL;
-
 	spin_lock(&cs->lock);
 	spin_lock(&csset->lock);
 	if (__lookup_cs(csset, id)) {
@@ -455,46 +435,7 @@ static void cs_get_read_response_iter(struct pcs_msg *msg, int offset, struct io
 	}
 }
 
-static void cs_connect(struct pcs_rpc *ep)
-{
-	void (*connect_start)(struct pcs_rpc *);
-
-	if (ep->flags & PCS_RPC_F_LOCAL) {
-		char path[128];
-
-		snprintf(path, sizeof(path)-1, PCS_SHM_DIR "/%llu_" CLUSTER_ID_FMT,
-			 (unsigned long long)ep->peer_id.val, CLUSTER_ID_ARGS(ep->eng->cluster_id));
-
-		if ((strlen(path) + 1) > sizeof(((struct sockaddr_un *) 0)->sun_path)) {
-			TRACE("Path to local socket is too long: %s", path);
-
-			ep->flags &= ~PCS_RPC_F_LOCAL;
-			goto fail;
-		}
-		memset(&ep->sh.sun, 0, sizeof(struct sockaddr_un));
-		ep->sh.sun.sun_family = AF_UNIX;
-		ep->sh.sa_len = sizeof(struct sockaddr_un);
-		strcpy(ep->sh.sun.sun_path, path);
-		connect_start = pcs_sockconnect_start;
-	} else {
-		/* TODO: print sock addr using pcs_format_netaddr() */
-		if (pcs_netaddr2sockaddr(&ep->addr, &ep->sh.sa, &ep->sh.sa_len)) {
-			TRACE("netaddr to sockaddr failed");
-			goto fail;
-		}
-		connect_start = ep->addr.type == PCS_ADDRTYPE_RDMA ?
-			pcs_rdmaconnect_start : pcs_sockconnect_start;
-	}
-	ep->state = PCS_RPC_CONNECT;
-	connect_start(ep); /* TODO: rewrite to use pcs_netconnect callback */
-	return;
-fail:
-	pcs_rpc_report_error(ep, PCS_RPC_ERR_CONNECT_ERROR);
-	pcs_rpc_reset(ep);
-	return;
-}
-
-static struct pcs_msg *cs_get_hdr(struct pcs_rpc *ep, struct pcs_rpc_hdr *h)
+struct pcs_msg *cs_get_hdr(struct pcs_rpc *ep, struct pcs_rpc_hdr *h)
 {
 	struct pcs_msg *msg, *resp;
 	struct pcs_rpc_hdr *req_h;
@@ -887,7 +828,7 @@ void pcs_cs_submit(struct pcs_cs *cs, struct pcs_int_request *ireq)
 	do_cs_submit(cs, ireq);
 }
 
-static void handle_congestion(struct pcs_cs *cs, struct pcs_rpc_hdr *h)
+void cs_handle_congestion(struct pcs_cs *cs, struct pcs_rpc_hdr *h)
 {
 	struct pcs_cs *who;
 
@@ -945,10 +886,10 @@ static int may_reroute(struct pcs_cs_list *csl, PCS_NODE_ID_T cs_id)
 	return legit;
 }
 
-static void cs_keep_waiting(struct pcs_rpc *ep, struct pcs_msg *req, struct pcs_msg *msg)
+void cs_keep_waiting(struct pcs_rpc *ep, struct pcs_msg *req, struct pcs_msg *msg)
 {
 	struct pcs_rpc_hdr *h = (struct pcs_rpc_hdr *)msg_inline_head(msg);
-	struct pcs_cs *cs = ep->private;
+	struct pcs_cs *cs = ep->clnt_cs;
 	struct pcs_cs *who;
 
 	/* Some CS reported it cannot complete local IO in time, close congestion window */
@@ -1003,21 +944,6 @@ static void cs_keep_waiting(struct pcs_rpc *ep, struct pcs_msg *req, struct pcs_
 
 }
 
-static int cs_input(struct pcs_rpc *ep, struct pcs_msg *msg)
-{
-	struct pcs_rpc_hdr *h = (struct pcs_rpc_hdr *)msg->_inline_buffer;
-
-	switch (h->type) {
-	case PCS_CS_CONG_NOTIFY:
-		handle_congestion(ep->private, h);
-		msg->done(msg);
-		return 0;
-	default:
-		FUSE_KLOG(cc_from_rpc(ep->eng)->fc, LOG_ERR, "Unsupported message type %u", h->type);
-		return PCS_ERR_PROTOCOL;
-	}
-}
-
 void pcs_cs_notify_error(struct pcs_cluster_core *cc, pcs_error_t *err)
 {
 	struct list_head queue;
@@ -1094,17 +1020,13 @@ static void pcs_cs_destroy(struct pcs_cs *cs)
 	BUG_ON(cs->csa_ctx);
 
 	if (cs->rpc) {
-		pcs_rpc_close(cs->rpc);
+		cs->rpc->clnt_cs = NULL;
+		pcs_rpc_clnt_close(cs->rpc);
 		cs->rpc = NULL;
 	}
 	call_rcu(&cs->rcu, cs_destroy_rcu);
 }
 
-void cs_aborting(struct pcs_rpc *ep, int error)
-{
-	pcs_rpc_reset(ep);
-}
-
 /* Latency is difficult value to use for any decisions.
  * It is sampled at random, we do not know what is happening while
  * we have no samples. For now we do the following: arriving samples
diff --git a/fs/fuse/kio/pcs/pcs_cs.h b/fs/fuse/kio/pcs/pcs_cs.h
index 61be99a54157..62b88f612b54 100644
--- a/fs/fuse/kio/pcs/pcs_cs.h
+++ b/fs/fuse/kio/pcs/pcs_cs.h
@@ -159,8 +159,6 @@ unsigned int cs_get_avg_in_flight(struct pcs_cs *cs);
 void pcs_csset_init(struct pcs_cs_set *css);
 void pcs_csset_fini(struct pcs_cs_set *css);
 
-struct pcs_cs *pcs_cs_alloc(struct pcs_cs_set *css, struct pcs_cluster_core *cc);
-
 void cs_log_io_times(struct pcs_int_request *ireq, struct pcs_msg *resp, unsigned int max_iolat);
 int pcs_cs_format_io_times(char *buf, int buflen, struct pcs_int_request *ireq, struct pcs_msg *resp);
 void cs_set_io_times_logger(void (*logger)(struct pcs_int_request *ireq, struct pcs_msg *resp, u32 max_iolat, void *ctx), void *ctx);
@@ -219,4 +217,7 @@ int pcs_csa_csl_write_submit_single(struct pcs_int_request * ireq, int idx);
 void pcs_csa_relay_iotimes(struct pcs_int_request * ireq,  struct pcs_cs_iohdr * h, PCS_NODE_ID_T cs_id);
 void pcs_csa_cs_detach(struct pcs_cs * cs);
 
+void cs_handle_congestion(struct pcs_cs *cs, struct pcs_rpc_hdr *h);
+struct pcs_msg *cs_get_hdr(struct pcs_rpc *ep, struct pcs_rpc_hdr *h);
+void cs_keep_waiting(struct pcs_rpc *ep, struct pcs_msg *req, struct pcs_msg *msg);
 #endif /* _PCS_CS_H_ */
diff --git a/fs/fuse/kio/pcs/pcs_fuse_kdirect.c b/fs/fuse/kio/pcs/pcs_fuse_kdirect.c
index 566dcb5f2f4c..a71cb7a9a0b6 100644
--- a/fs/fuse/kio/pcs/pcs_fuse_kdirect.c
+++ b/fs/fuse/kio/pcs/pcs_fuse_kdirect.c
@@ -37,6 +37,8 @@
 #include "fuse_ktrace.h"
 #include "fuse_prometheus.h"
 #include "pcs_net_addr.h"
+#include "pcs_mr.h"
+#include "pcs_krpc.h"
 
 unsigned int pcs_loglevel = LOG_TRACE;
 module_param(pcs_loglevel, uint, 0644);
@@ -71,6 +73,10 @@ unsigned int rdmaio_queue_depth = 8;
 module_param(rdmaio_queue_depth, uint, 0644);
 MODULE_PARM_DESC(rdmaio_queue_depth, "RDMA queue depth");
 
+bool pcs_krpc_support = true;
+module_param(pcs_krpc_support, bool, 0444);
+MODULE_PARM_DESC(pcs_krpc_support, "krpc support");
+
 void (*fuse_printk_plugin)(unsigned long, const char *, ...);
 EXPORT_SYMBOL(fuse_printk_plugin);
 
@@ -189,7 +195,7 @@ static void process_pcs_init_reply(struct fuse_mount *fm, struct fuse_args *args
 	fuse_ktrace_setup(fc);
 	fc->ktrace_level = LOG_TRACE;
 
-	printk("FUSE: kio_pcs: cl: " CLUSTER_ID_FMT ", clientid: " NODE_FMT "\n",
+	printk("FUSE: kio_pcs: cl: " CLUSTER_ID_FMT ", clientid: " NODE_FMT,
 	       CLUSTER_ID_ARGS(info->cluster_id), NODE_ARGS(info->node_id));
 
 	spin_lock(&fc->lock);
@@ -1864,6 +1870,84 @@ static int kpcs_ioctl(struct file *file, struct inode *inode, unsigned int cmd,
 	return res;
 }
 
+static int kpcs_dev_ioctl(struct fuse_conn *fc, unsigned int cmd, unsigned long arg, int len)
+{
+	struct pcs_fuse_cluster *pfc = fc->kio.ctx;
+	struct pcs_cluster_core *cc = &pfc->cc;
+	int res;
+
+	switch (cmd) {
+	case PCS_IOC_KRPC_CREATE:
+	{
+		struct pcs_ioc_krpc_create req;
+
+		if (copy_from_user(&req, (void __user *)arg, sizeof(req)))
+			return -EFAULT;
+
+		if (pcs_krpc_lookup(&cc->krpcs, &req.id))
+			return -EEXIST;
+
+		res = pcs_krpc_create(&cc->krpcs, &req.id, &req.addr, req.cs_flags);
+		break;
+	}
+	case PCS_IOC_KRPC_UPDATE_ADDR:
+	{
+		struct pcs_ioc_krpc_create req;
+
+		if (copy_from_user(&req, (void __user *)arg, sizeof(req)))
+			return -EFAULT;
+
+		res = pcs_krpc_update_addr(&cc->krpcs, &req.id, &req.addr, req.cs_flags);
+		break;
+	}
+
+	case PCS_IOC_KRPC_CONNECT:
+	{
+		struct pcs_ioc_krpc_connect req;
+
+		if (copy_from_user(&req, (void __user *)arg, sizeof(req)))
+			return -EFAULT;
+
+		res = pcs_krpc_connect(&cc->krpcs, &req.id);
+		break;
+	}
+	case PCS_IOC_KRPC_DESTROY:
+	{
+		struct pcs_ioc_krpc_destroy req;
+
+		if (copy_from_user(&req, (void __user *)arg, sizeof(req)))
+			return -EFAULT;
+
+		res = pcs_krpc_destroy(&cc->krpcs, &req.id);
+		break;
+	}
+	case PCS_IOC_REG_MR:
+	{
+		struct pcs_ioc_reg_mr req;
+
+		if (copy_from_user(&req, (void __user *)arg, sizeof(req)))
+			return -EFAULT;
+
+		res = pcs_reg_mr(&cc->mrs, req.start, req.len);
+		break;
+	}
+	case PCS_IOC_DEREG_MR:
+	{
+		struct pcs_ioc_dereg_mr req;
+
+		if (copy_from_user(&req, (void __user *)arg, sizeof(req)))
+			return -EFAULT;
+
+		res = pcs_dereg_mr(&cc->mrs, req.id);
+		break;
+	}
+	default:
+		res = -ENOIOCTLCMD;
+		break;
+	}
+	return res;
+}
+
 static struct fuse_kio_ops kio_pcs_ops = {
 	.name		= "pcs",
 	.owner		= THIS_MODULE,
@@ -1880,6 +1964,7 @@ static struct fuse_kio_ops kio_pcs_ops = {
 	.inode_release	= kpcs_inode_release,
 	.kill_requests	= kpcs_kill_requests,
 	.ioctl		= kpcs_ioctl,
+	.dev_ioctl  = kpcs_dev_ioctl,
 };
 
 
@@ -1920,10 +2005,13 @@ static int __init kpcs_mod_init(void)
 	if (pcs_csa_init())
 		goto free_cleanup_wq;
 
+	if (pcs_krpc_init())
+		goto free_csa;
+
 	fast_path_version = PCS_FAST_PATH_VERSION.full;
 
 	if (fuse_register_kio(&kio_pcs_ops))
-		goto free_csa;
+		goto free_krpc;
 
 	/* Clone relay_file_operations to set ownership */
 	ktrace_file_operations = relay_file_operations;
@@ -1935,10 +2023,13 @@ static int __init kpcs_mod_init(void)
 	if (IS_ERR(crc_tfm))
 		crc_tfm = NULL;
 
+
 	printk("%s fuse_c:%p ireq_c:%p pcs_wq:%p\n", __FUNCTION__,
 	       pcs_fuse_req_cachep, pcs_ireq_cachep, pcs_wq);
 
 	return 0;
+free_krpc:
+	pcs_krpc_fini();
 free_csa:
 	pcs_csa_fini();
 free_cleanup_wq:
@@ -1968,6 +2059,7 @@ static void __exit kpcs_mod_exit(void)
 	kmem_cache_destroy(pcs_ireq_cachep);
 	kmem_cache_destroy(pcs_fuse_req_cachep);
 	pcs_csa_fini();
+	pcs_krpc_fini();
 }
 
 module_init(kpcs_mod_init);
diff --git a/fs/fuse/kio/pcs/pcs_ioctl.h b/fs/fuse/kio/pcs/pcs_ioctl.h
index 8e55be02c654..3c000373745b 100644
--- a/fs/fuse/kio/pcs/pcs_ioctl.h
+++ b/fs/fuse/kio/pcs/pcs_ioctl.h
@@ -123,4 +123,33 @@ struct pcs_csa_setmap
 #define PCS_CSA_IOC_SETMAP	_IOR('V',38, struct pcs_csa_setmap)
 #define PCS_KIO_CALL_REG	_IOR('V',39, struct fuse_pcs_ioc_register)
 
+struct pcs_ioc_reg_mr {
+	u64	start;
+	u64	len;
+};
+#define PCS_IOC_REG_MR  _IOR('V', 40, struct pcs_ioc_reg_mr)
+
+struct pcs_ioc_dereg_mr {
+	u32 id;
+};
+#define PCS_IOC_DEREG_MR  _IOR('V', 41, struct pcs_ioc_dereg_mr)
+
+struct pcs_ioc_krpc_create {
+	PCS_NODE_ID_T	id;
+	PCS_NET_ADDR_T	addr;
+	int				cs_flags;
+};
+#define PCS_IOC_KRPC_CREATE	_IOR('V', 42, struct pcs_ioc_krpc_create)
+#define PCS_IOC_KRPC_UPDATE_ADDR _IOR('V', 43, struct pcs_ioc_krpc_create)
+
+struct pcs_ioc_krpc_connect {
+	PCS_NODE_ID_T	id;
+};
+#define PCS_IOC_KRPC_CONNECT _IOR('V', 44, struct pcs_ioc_krpc_connect)
+
+struct pcs_ioc_krpc_destroy {
+	PCS_NODE_ID_T	id;
+};
+#define PCS_IOC_KRPC_DESTROY _IOR('V', 45, struct pcs_ioc_krpc_destroy)
+
 #endif /* _PCS_IOCTL_H_ */
diff --git a/fs/fuse/kio/pcs/pcs_krpc.c b/fs/fuse/kio/pcs/pcs_krpc.c
new file mode 100644
index 000000000000..0e49dc227dca
--- /dev/null
+++ b/fs/fuse/kio/pcs/pcs_krpc.c
@@ -0,0 +1,794 @@
+/*
+ *  fs/fuse/kio/pcs/pcs_krpc.c
+ *
+ *  Copyright (c) 2018-2021 Virtuozzo International GmbH. All rights reserved.
+ *
+ */
+
+#include <linux/types.h>
+#include <linux/list.h>
+#include <linux/rbtree.h>
+#include <linux/refcount.h>
+#include <linux/file.h>
+#include <linux/anon_inodes.h>
+
+#include "pcs_types.h"
+#include "pcs_cluster.h"
+#include "pcs_cs_prot.h"
+#include "pcs_req.h"
+#include "pcs_krpc.h"
+
+struct kmem_cache *krpc_req_cachep;
+
+static int krpc_completion_post(struct pcs_krpc *krpc, struct krpc_completion *comp)
+__releases(krpc->lock)
+{
+	/* post complete only when connected */
+	if (krpc->state != PCS_KRPC_STATE_CONNECTED) {
+		spin_unlock(&krpc->lock);
+		return -1;
+	}
+	list_add_tail(&comp->link, &krpc->completion_queue);
+	krpc->nr_completion++;
+	spin_unlock(&krpc->lock);
+
+	wake_up_poll(&krpc->poll_wait, EPOLLIN);
+	return 0;
+}
+
+static struct krpc_req *krpc_req_alloc(void)
+{
+	struct krpc_req *kreq;
+
+	kreq = kmem_cache_alloc(krpc_req_cachep, GFP_NOIO);
+	if (!kreq)
+		return NULL;
+
+	spin_lock_init(&kreq->lock);
+	kreq->flags = 0;
+	memset(&kreq->completion, 0, sizeof(struct krpc_completion));
+
+	return kreq;
+}
+
+static void krpc_req_free(struct krpc_req *kreq)
+{
+	kmem_cache_free(krpc_req_cachep, kreq);
+}
+
+static void krpc_completion_free(struct krpc_completion *comp)
+{
+	if (comp->private)
+		krpc_req_free((struct krpc_req *)comp->private);
+	else
+		kfree(comp);
+}
+
+static void krpc_req_complete(struct krpc_req *kreq, int error)
+{
+	struct krpc_completion *comp = &kreq->completion;
+	struct pcs_krpc *krpc = kreq->krpc;
+	int i;
+
+	BUG_ON(!comp->xid);
+
+	comp->result = error;
+
+	/* kunmap(kreq->hdr_buf); */
+	pcs_mr_put(kreq->hdr_chunk.mr);
+
+	for (i = 0; i < kreq->nr_data_chunks; i++) {
+		struct krpc_chunk *chunk;
+
+		chunk = &kreq->data_chunks[i];
+		if (chunk->type == KRPC_CHUNK_TYPE_UMEM)
+			pcs_umem_release(chunk->umem);
+		else
+			pcs_mr_put(chunk->mr);
+	}
+
+	if (kreq->data_chunks != &kreq->inline_data_chunks[0])
+		kfree(kreq->data_chunks);
+
+	spin_lock(&krpc->lock);
+	list_del(&kreq->link);
+
+	if (kreq->flags & KRPC_REQ_F_ABORTED) {
+		krpc_req_free(kreq);
+		spin_unlock(&krpc->lock);
+	} else if (krpc_completion_post(krpc, comp))
+		krpc_req_free(kreq);
+
+	pcs_krpc_put(krpc);
+}
+
+static void krpc_msg_get_response_iter(struct pcs_msg *msg, int offset,
+			struct iov_iter *it, unsigned int direction)
+{
+	struct pcs_msg *req = msg->private;
+	struct krpc_req *kreq = req->private2;
+
+	/* No data payload*/
+	if (!(kreq->flags & KRPC_REQ_F_RESP_BUFF)) {
+		/* No data payload */
+		BUG_ON(msg->size > PAGE_SIZE);
+
+		kreq->hdr_kv.iov_base = (void *)kreq->hdr_buf;
+		kreq->hdr_kv.iov_len = msg->size;
+
+		iov_iter_kvec(it, direction, &kreq->hdr_kv, 1, msg->size);
+		iov_iter_advance(it, offset);
+	} else {
+	/* With Data payload */
+		int hdr_size = sizeof(struct pcs_cs_iohdr);
+
+		if (offset < hdr_size) {
+			kreq->hdr_kv.iov_base = (void *)kreq->hdr_buf;
+			kreq->hdr_kv.iov_len = hdr_size;
+			iov_iter_kvec(it, direction, &kreq->hdr_kv, 1, hdr_size);
+			iov_iter_advance(it, offset);
+		} else {
+			//offset -= (unsigned int) sizeof(struct pcs_cs_iohdr);
+			BUG_ON((offset - hdr_size) > kreq->data_len);
+			BUG_ON(msg->size - hdr_size > kreq->data_len);
+
+			iov_iter_bvec(it, direction, &kreq->data_bvecs[0],
+						kreq->nr_data_bvecs, kreq->data_len);
+			iov_iter_truncate(it, msg->size - hdr_size);
+			iov_iter_advance(it, offset - hdr_size);
+		}
+	}
+}
+
+struct pcs_msg *krpc_get_hdr(struct pcs_rpc *ep, struct pcs_rpc_hdr *h)
+{
+	struct pcs_msg *msg, *resp;
+	struct pcs_rpc_hdr *req_h;
+	struct krpc_req *kreq;
+
+	if (!RPC_IS_RESPONSE(h->type))
+		return NULL;
+
+	msg = pcs_rpc_lookup_xid(ep, &h->xid);
+	if (msg == NULL)
+		return NULL;
+
+	req_h = (struct pcs_rpc_hdr *)msg_inline_head(msg);
+	if (req_h->type != (h->type & ~PCS_RPC_DIRECTION))
+		return NULL;
+
+	kreq = msg->private2;
+
+	resp = pcs_rpc_alloc_input_msg(ep, sizeof(struct pcs_rpc_hdr));
+	if (!resp)
+		return NULL;
+
+	memcpy(resp->_inline_buffer, h, sizeof(struct pcs_rpc_hdr));
+	memcpy(kreq->hdr_buf, h, sizeof(struct pcs_rpc_hdr));
+	resp->size = h->len;
+	resp->private = msg;
+	resp->get_iter = krpc_msg_get_response_iter;
+	resp->done = rpc_work_input;
+	pcs_msg_del_calendar(msg);
+
+	return resp;
+}
+
+/*
+ * All request type message from cs are forwarded to userspace directly. The PCS KRPC
+ * layer cannot process these request on its own.
+ */
+static void krpc_handle_request(struct pcs_krpc *krpc, struct pcs_msg *msg)
+{
+	struct krpc_completion *comp;
+
+	if (krpc->state != PCS_KRPC_STATE_CONNECTED)
+		return;
+
+	comp = kzalloc(sizeof(*comp) + msg->size, GFP_NOIO);
+	if (!comp) {
+		/* Error ?*/
+		return;
+	}
+
+	memcpy(comp->_data_buf, msg->_inline_buffer, msg->size);
+	comp->data_len = msg->size;
+
+	spin_lock(&krpc->lock);
+	if (krpc_completion_post(krpc, comp))
+		kfree(comp);
+}
+
+/*
+ * Let userspace to handle cs_congestion_notify request.
+ */
+void krpc_handle_congestion(struct pcs_rpc *ep, struct pcs_msg *msg)
+{
+	krpc_handle_request(ep->clnt_krpc, msg);
+}
+
+/*
+ * Let userspace to handle the keep_waiting request.
+ */
+void krpc_keep_waiting(struct pcs_rpc *ep, struct pcs_msg *req, struct pcs_msg *msg)
+{
+	krpc_handle_request(ep->clnt_krpc, msg);
+}
+
+unsigned int pcs_krpc_hash(PCS_NODE_ID_T *id)
+{
+	return *(unsigned int *)id % PCS_KRPC_HASH_SIZE;
+}
+
+static void krpc_msg_get_data(struct pcs_msg *msg, int offset,
+		struct iov_iter *it, unsigned int direction)
+{
+	struct krpc_req *kreq = msg->private2;
+	int hdr_size = pcs_krpc_msg_size(kreq->hdr_chunk.len, kreq->flags);
+	int data_size = pcs_krpc_msg_size(kreq->data_len, kreq->flags);
+	struct pcs_krpc *krpc = kreq->krpc;
+
+	if (offset < kreq->hdr_chunk.len) {
+		iov_iter_kvec(it, direction, &kreq->hdr_kv, 1, kreq->hdr_chunk.len);
+		iov_iter_advance(it, offset);
+		return;
+	}
+
+	if (offset < hdr_size) {
+		iov_iter_kvec(it, direction, &(cc_from_krpcset(krpc->krpcs))->nilbuffer_kv,
+						 1, hdr_size - offset);
+		return;
+	}
+
+	if (offset < hdr_size + kreq->data_len) {
+		iov_iter_bvec(it, direction, &kreq->data_bvecs[0],
+				kreq->nr_data_bvecs, kreq->data_len);
+		iov_iter_advance(it, offset - hdr_size);
+		return;
+	}
+
+	BUG_ON(offset >= hdr_size + data_size);
+
+	iov_iter_kvec(it, direction, &(cc_from_krpcset(krpc->krpcs))->nilbuffer_kv,
+					1, (hdr_size + data_size - offset));
+}
+
+static void pcs_krpc_response_done(struct pcs_msg *msg)
+{
+	struct krpc_req *kreq = msg->private2;
+
+	if (msg->rpc) {
+		pcs_rpc_put(msg->rpc);
+		msg->rpc = NULL;
+	}
+
+	krpc_req_complete(kreq, msg->error.value);
+}
+
+static void pcs_krpc_msg_sent(struct pcs_msg *msg)
+{
+	msg->done = pcs_krpc_response_done;
+	if (pcs_if_error(&msg->error)) {
+		msg->done(msg);
+		return;
+	}
+	pcs_rpc_sent(msg);
+}
+
+static int pcs_krpc_ioctl_recv_msg(struct pcs_krpc *krpc, struct pcs_krpc_ioc_recvmsg *iocmsg)
+{
+	struct krpc_completion *comp;
+	int res = 0;
+
+	spin_lock(&krpc->lock);
+	if (list_empty(&krpc->completion_queue)) {
+		spin_unlock(&krpc->lock);
+		return 0;
+	}
+
+	comp = list_first_entry(&krpc->completion_queue, struct krpc_completion, link);
+	list_del(&comp->link);
+	krpc->nr_completion--;
+	spin_unlock(&krpc->lock);
+
+	if (comp->result) {
+		res -=  comp->result;
+		goto out;
+	}
+
+	res = 1;
+	iocmsg->xid = comp->xid;
+	if (comp->xid == 0) {
+		BUG_ON(!comp->data_len);
+		BUG_ON(iocmsg->buf.len < comp->data_len);
+		if (copy_to_user((void __user *)iocmsg->buf.addr, comp->_data_buf, comp->data_len))
+			res = -EFAULT;
+	}
+
+out:
+	krpc_completion_free(comp);
+	return res;
+}
+
+static int pcs_krpc_ioctl_send_msg(struct pcs_krpc *krpc, struct pcs_krpc_ioc_sendmsg *iocmsg)
+{
+	struct krpc_req *kreq;
+	struct pcs_msg *msg;
+	struct pcs_krpc_buf_desc *chunk_bd;
+	struct krpc_chunk *chunk;
+	int res, i;
+	struct bio_vec *bvec;
+
+	kreq = krpc_req_alloc();
+	if (!kreq)
+		return -ENOMEM;
+
+	if (iocmsg->nr_data_chunks > NR_KRPC_DATA_CHUNKS_INLINE) {
+		kreq->data_chunks = kzalloc(iocmsg->nr_data_chunks, GFP_NOIO);
+		if (!kreq->data_chunks) {
+			res = -ENOMEM;
+			goto err_free_kreq;
+		}
+	} else
+		kreq->data_chunks = &kreq->inline_data_chunks[0];
+
+	/*
+	 * Header buff is exactly one page, used for staging message header. Will be used for
+	 * receiving header of response message as well.
+	 */
+	BUG_ON(iocmsg->hdr_chunk.addr & (PAGE_SIZE - 1));
+
+	chunk_bd = &iocmsg->hdr_chunk;
+	chunk = &kreq->hdr_chunk;
+
+	chunk->addr = chunk_bd->addr;
+	chunk->len = chunk_bd->len;
+	chunk->type = KRPC_CHUNK_TYPE_MR;
+
+	chunk->mr = pcs_mr_get(&cc_from_krpc(krpc)->mrs, iocmsg->hdr_chunk.mr_id);
+	BUG_ON(!chunk->mr);
+
+	kreq->hdr_buf = (char *) kmap(pcs_umem_page(chunk->mr->umem, chunk->addr));
+	kreq->hdr_kv.iov_base = kreq->hdr_buf;
+	kreq->hdr_kv.iov_len = chunk->len;
+
+	/* data chunk buf descriptors are placed at end of header buf, grow backwards */
+	kreq->data_len = 0;
+	kreq->nr_data_chunks  = 0;
+	kreq->nr_data_bvecs  = 0;
+
+	chunk_bd = (struct pcs_krpc_buf_desc *)(kreq->hdr_buf + PAGE_SIZE) - 1;
+	chunk = kreq->data_chunks;
+	bvec = &kreq->data_bvecs[0];
+
+	for (i = 0; i < iocmsg->nr_data_chunks; i++) {
+		struct page *page;
+		u64 addr;
+		int offset, len;
+
+		chunk->addr = chunk_bd->addr;
+		chunk->len = chunk_bd->len;
+		if (chunk_bd->mr_id) {
+			chunk->mr = pcs_mr_get(&cc_from_krpc(krpc)->mrs, chunk_bd->mr_id);
+			chunk->type = KRPC_CHUNK_TYPE_MR;
+			if (!chunk->mr) {
+				res = -ENXIO;
+				goto err_free_data_chunk;
+			}
+		} else {
+			/* unregistered memory buf */
+			chunk->umem = pcs_umem_get(chunk->addr, chunk->len);
+			if (IS_ERR(chunk->umem)) {
+				res = PTR_ERR(chunk->umem);
+				goto err_free_data_chunk;
+			}
+
+			chunk->type = KRPC_CHUNK_TYPE_UMEM;
+		}
+
+		/* build the bvecs for the data chunk*/
+		addr = chunk->addr;
+		len = chunk->len;
+
+		while (len) {
+			/* data bvec array overflow? */
+			BUG_ON(kreq->nr_data_bvecs >= KRPC_MAX_DATA_PAGES);
+
+			if (chunk->type == KRPC_CHUNK_TYPE_MR)
+				page = pcs_umem_page(chunk->mr->umem, addr);
+			else
+				page = pcs_umem_page(chunk->umem, addr);
+
+			BUG_ON(!page);
+
+			offset = addr & (PAGE_SIZE - 1);
+
+			bvec->bv_page = page;
+			bvec->bv_offset =  offset;
+
+			bvec->bv_len = len < (PAGE_SIZE - offset) ? len : (PAGE_SIZE - offset);
+
+			addr += bvec->bv_len;
+			len -= bvec->bv_len;
+			bvec++;
+			kreq->nr_data_bvecs++;
+		}
+		BUG_ON(len != 0);
+
+		kreq->data_len += chunk->len;
+		chunk++;
+		chunk_bd--;
+		kreq->nr_data_chunks++;
+	}
+
+	kreq->completion.xid = iocmsg->xid;
+	kreq->completion.private = kreq;
+
+	kreq->flags = iocmsg->flags;
+
+	msg = &kreq->msg;
+	msg->private = krpc;
+	msg->private2 = kreq;
+
+	INIT_HLIST_NODE(&msg->kill_link);
+	pcs_clear_error(&msg->error);
+
+	msg->size = iocmsg->msg_size;
+	msg->timeout = iocmsg->timeout;
+
+	msg->rpc = NULL;
+	msg->done = pcs_krpc_msg_sent;
+	msg->get_iter = krpc_msg_get_data;
+
+	spin_lock(&krpc->lock);
+	kreq->krpc = pcs_krpc_get(krpc);
+	list_add_tail(&kreq->link, &krpc->pending_queue);
+	spin_unlock(&krpc->lock);
+	/* DTRACE to be added */
+	pcs_rpc_queue(krpc->rpc, msg);
+
+	return 0;
+
+err_free_data_chunk:
+	for (i = 0; i < kreq->nr_data_chunks; i++) {
+		chunk = &kreq->data_chunks[i];
+		if (chunk->type == KRPC_CHUNK_TYPE_UMEM)
+			pcs_umem_release(chunk->umem);
+		else
+			pcs_mr_put(chunk->mr);
+	}
+	pcs_mr_put(kreq->hdr_chunk.mr);
+
+err_free_kreq:
+	if (kreq->data_chunks != &kreq->inline_data_chunks[0])
+		kfree(kreq->data_chunks);
+	krpc_req_free(kreq);
+	return res;
+}
+
+static int pcs_krpc_abort(struct pcs_krpc *krpc)
+{
+	struct list_head dispose_list;
+	struct krpc_req *kreq;
+	struct krpc_completion *comp;
+
+	INIT_LIST_HEAD(&dispose_list);
+
+	spin_lock(&krpc->lock);
+
+	if (krpc->state != PCS_KRPC_STATE_CONNECTED) {
+		spin_unlock(&krpc->lock);
+		return 0;
+	}
+
+	krpc->state = PCS_KRPC_STATE_ABORTED;
+
+	/* abort incompleted requests */
+	list_splice_tail_init(&krpc->pending_queue, &dispose_list);
+	while (!list_empty(&dispose_list)) {
+		kreq = list_first_entry(&dispose_list, struct krpc_req, link);
+		kreq->flags |= KRPC_REQ_F_ABORTED;
+	}
+
+	list_splice_tail_init(&krpc->completion_queue, &dispose_list);
+	krpc->nr_completion = 0;
+
+	/* dispose all unprocessed completions */
+	while (!list_empty(&dispose_list)) {
+		comp = list_first_entry(&dispose_list, struct krpc_completion, link);
+		list_del(&comp->link);
+		krpc_completion_free(comp);
+	}
+
+	spin_unlock(&krpc->lock);
+
+	return 0;
+}
+
+static long pcs_krpc_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+	struct pcs_krpc *krpc = file->private_data;
+	int res = 0;
+
+	switch (cmd) {
+	case PCS_KRPC_IOC_SEND_MSG: {
+		struct pcs_krpc_ioc_sendmsg req;
+
+		if (copy_from_user(&req, (void __user *)arg, sizeof(req)))
+			return -EFAULT;
+
+		res = pcs_krpc_ioctl_send_msg(krpc, &req);
+		break;
+	}
+	case PCS_KRPC_IOC_RECV_MSG: {
+		struct pcs_krpc_ioc_recvmsg  req;
+
+		res = pcs_krpc_ioctl_recv_msg(krpc, &req);
+
+		if (copy_to_user((void __user *)arg, &req, sizeof(req)))
+			return -EFAULT;
+		break;
+	}
+	case PCS_KRPC_IOC_ABORT:
+		res = pcs_krpc_abort(krpc);
+		break;
+	default:
+		res = -ENOTTY;
+		break;
+	}
+
+	return res;
+}
+
+static __poll_t pcs_krpc_poll(struct file *file, poll_table *wait)
+{
+	struct pcs_krpc *krpc = file->private_data;
+	__poll_t pollflags = 0;
+
+	poll_wait(file, &krpc->poll_wait, wait);
+
+	spin_lock(&krpc->lock);
+	/* EPOLLERR? */
+	if (krpc->state == PCS_KRPC_STATE_ABORTED)
+		pollflags |= EPOLLERR;
+	else if (krpc->state == PCS_KRPC_STATE_CONNECTED) {
+		pollflags |= EPOLLOUT;
+		if (!list_empty(&krpc->completion_queue))
+			pollflags |= EPOLLIN;
+	}
+
+	spin_unlock(&krpc->lock);
+
+	return pollflags;
+}
+
+/*
+ * Reset to initial state -- PCS_KRPC_STATE_UNCONN
+ */
+static int pcs_krpc_release(struct inode *inode, struct file *file)
+{
+	struct pcs_krpc *krpc = file->private_data;
+
+	/* Just abort all pending requests and disconnect from the krpc */
+	pcs_krpc_abort(krpc);
+
+	spin_lock(&krpc->lock);
+	if (krpc->state == PCS_KRPC_STATE_ABORTED)
+		krpc->state = PCS_KRPC_STATE_UNCONN;
+	spin_unlock(&krpc->lock);
+
+	return 0;
+}
+
+static const struct file_operations pcs_krpc_fops = {
+	.owner = THIS_MODULE,
+	.release = pcs_krpc_release,
+	.poll	= pcs_krpc_poll,
+	.unlocked_ioctl = pcs_krpc_ioctl,
+	.llseek		= no_llseek,
+};
+
+struct pcs_krpc *pcs_krpc_lookup(struct pcs_krpc_set *krpcs, PCS_NODE_ID_T *id)
+{
+	struct pcs_krpc *krpc;
+
+	hlist_for_each_entry(krpc, &krpcs->ht[pcs_krpc_hash(id)], hlist) {
+		if (memcmp(&krpc->id, id, sizeof(krpc->id)) == 0)
+			return krpc;
+	}
+	return NULL;
+}
+
+struct pcs_krpc *pcs_krpc_get(struct pcs_krpc *krpc)
+{
+	refcount_inc(&krpc->refcnt);
+	return krpc;
+}
+
+void pcs_krpc_put(struct pcs_krpc *krpc)
+{
+	if (refcount_dec_and_test(&krpc->refcnt))
+		kfree(krpc);
+}
+
+/*
+ * Create a new pcs_krpc
+ */
+int pcs_krpc_create(struct pcs_krpc_set *krpcs, PCS_NODE_ID_T *id,
+		PCS_NET_ADDR_T *addr, int cs_flags)
+{
+	struct pcs_krpc *krpc;
+
+	krpc = kzalloc(sizeof(struct pcs_krpc), GFP_NOIO);
+	if (!krpc)
+		return -ENOMEM;
+
+	INIT_HLIST_NODE(&krpc->hlist);
+	INIT_LIST_HEAD(&krpc->link);
+	spin_lock_init(&krpc->lock);
+	refcount_set(&krpc->refcnt, 1);
+	INIT_LIST_HEAD(&krpc->pending_queue);
+	INIT_LIST_HEAD(&krpc->completion_queue);
+	init_waitqueue_head(&krpc->poll_wait);
+
+	krpc->krpcs = krpcs;
+	krpc->id = *id;
+	krpc->state = PCS_KRPC_STATE_UNCONN;
+
+	krpc->rpc = pcs_rpc_clnt_create(&cc_from_krpcset(krpcs)->eng, id, addr, cs_flags);
+	if (!krpc->rpc) {
+		kfree(krpc);
+		return -ENOMEM;
+	}
+
+	krpc->rpc->clnt_krpc = krpc;
+
+	spin_lock(&krpc->lock);
+	spin_lock(&krpcs->lock);
+	hlist_add_head(&krpc->hlist, &krpcs->ht[pcs_krpc_hash(&krpc->id)]);
+	list_add_tail(&krpc->link, &krpcs->list);
+	krpcs->nkrpc++;
+	spin_unlock(&krpcs->lock);
+	spin_unlock(&krpc->lock);
+
+	return 0;
+}
+
+int pcs_krpc_update_addr(struct pcs_krpc_set *krpcs, PCS_NODE_ID_T *id,
+		PCS_NET_ADDR_T *addr, int flags)
+{
+	struct pcs_krpc *krpc;
+
+	krpc = pcs_krpc_lookup(krpcs, id);
+	if (!krpc)
+		return -ENXIO;
+
+	pcs_rpc_set_address(krpc->rpc, addr);
+
+	if (flags & CS_FL_LOCAL_SOCK)
+		krpc->rpc->flags |= PCS_RPC_F_LOCAL;
+	else
+		krpc->rpc->flags &= ~PCS_RPC_F_LOCAL;
+
+	return 0;
+}
+/*
+ * Connect to a pcs_krpc, return a valid fd on success.
+ */
+int pcs_krpc_connect(struct pcs_krpc_set *krpcs, PCS_NODE_ID_T *id)
+{
+	struct pcs_krpc *krpc;
+	int fd;
+	struct file *file;
+
+	krpc = pcs_krpc_lookup(krpcs, id);
+	if (!krpc)
+		return -ENXIO;
+
+	WARN_ON(krpc->state != PCS_KRPC_STATE_UNCONN);
+	if (krpc->state != PCS_KRPC_STATE_UNCONN)
+		return -EPERM;
+
+	fd = get_unused_fd_flags(O_CLOEXEC);
+	if (fd < 0)
+		return fd;
+
+	file = anon_inode_getfile("[pcs_krpc]", &pcs_krpc_fops, krpc, 0);
+	if (IS_ERR(file)) {
+		put_unused_fd(fd);
+		fd = PTR_ERR(file);
+		return fd;
+	}
+
+	fd_install(fd, file);
+
+	/*
+	 * the krpc should always be connected regardless state of
+	 * underlying RPC
+	 */
+	krpc->state = PCS_KRPC_STATE_CONNECTED;
+	return fd;
+}
+
+static void __pcs_krpc_destroy(struct pcs_krpc *krpc)
+{
+	spin_lock(&krpc->lock);
+
+	krpc->state = PCS_KRPC_STATE_DESTROYED;
+
+	/*Remove from krpc set*/
+	spin_lock(&krpc->krpcs->lock);
+	hlist_del(&krpc->hlist);
+	list_del(&krpc->link);
+	krpc->krpcs->nkrpc--;
+	spin_unlock(&krpc->krpcs->lock);
+
+	spin_unlock(&krpc->lock);
+
+	if (krpc->rpc) {
+		krpc->rpc->clnt_krpc = NULL;
+		pcs_rpc_clnt_close(krpc->rpc);
+		krpc->rpc = NULL;
+	}
+	pcs_krpc_put(krpc);
+}
+
+int pcs_krpc_destroy(struct pcs_krpc_set *krpcs, PCS_NODE_ID_T *id)
+{
+	struct pcs_krpc *krpc;
+
+	krpc = pcs_krpc_lookup(krpcs, id);
+	BUG_ON(!krpc);
+	BUG_ON(krpc->state != PCS_KRPC_STATE_UNCONN);
+
+	__pcs_krpc_destroy(krpc);
+	return 0;
+}
+
+void pcs_krpcset_init(struct pcs_krpc_set *krpcs)
+{
+	unsigned int i;
+
+	for (i = 0; i < PCS_KRPC_HASH_SIZE; i++)
+		INIT_HLIST_HEAD(&krpcs->ht[i]);
+
+	INIT_LIST_HEAD(&krpcs->list);
+	krpcs->nkrpc = 0;
+
+	spin_lock_init(&krpcs->lock);
+}
+
+void pcs_krpcset_fini(struct pcs_krpc_set *krpcs)
+{
+	spin_lock(&krpcs->lock);
+	while (!list_empty(&krpcs->list)) {
+		struct pcs_krpc *krpc;
+
+		krpc = list_first_entry(&krpcs->list, struct pcs_krpc, link);
+		spin_unlock(&krpcs->lock);
+		pcs_krpc_abort(krpc);
+		__pcs_krpc_destroy(krpc);
+		spin_lock(&krpcs->lock);
+	}
+	spin_unlock(&krpcs->lock);
+
+	BUG_ON(!list_empty(&krpcs->list));
+	BUG_ON(krpcs->nkrpc != 0);
+}
+
+int __init pcs_krpc_init(void)
+{
+	krpc_req_cachep = kmem_cache_create("pcs_krpc_req",
+							sizeof(struct krpc_req), 0,
+							SLAB_RECLAIM_ACCOUNT|SLAB_ACCOUNT, NULL);
+
+	if (!krpc_req_cachep)
+		return -ENOMEM;
+
+	return 0;
+}
+
+void pcs_krpc_fini(void)
+{
+	kmem_cache_destroy(krpc_req_cachep);
+}
diff --git a/fs/fuse/kio/pcs/pcs_krpc.h b/fs/fuse/kio/pcs/pcs_krpc.h
new file mode 100644
index 000000000000..6a257ba80208
--- /dev/null
+++ b/fs/fuse/kio/pcs/pcs_krpc.h
@@ -0,0 +1,140 @@
+/*
+ *  fs/fuse/kio/pcs/pcs_krpc.h
+ *
+ *  Copyright (c) 2018-2021 Virtuozzo International GmbH. All rights reserved.
+ *
+ */
+#ifndef _PCS_KRPC_H_
+#define _PCS_KRPC_H_ 1
+#include <linux/types.h>
+#include <linux/bvec.h>
+
+#include "pcs_prot_types.h"
+#include "pcs_perfcounters.h"
+#include "pcs_rpc_clnt.h"
+#include "pcs_krpc_prot.h"
+#include "pcs_mr.h"
+
+struct krpc_chunk {
+	u64		addr;
+	u32		len;
+	u32		type;
+#define KRPC_CHUNK_TYPE_MR		0
+#define KRPC_CHUNK_TYPE_UMEM	1
+	union {
+		struct pcs_mr *mr;
+		struct pcs_umem *umem;
+	};
+};
+
+#define PCS_KRPC_HASH_SIZE	1024
+struct pcs_krpc_set {
+	/* Set of krpcs */
+	struct hlist_head		ht[PCS_KRPC_HASH_SIZE];
+	struct list_head		list;
+	unsigned int			nkrpc;
+
+	spinlock_t				lock;
+};
+
+enum {
+	PCS_KRPC_STATE_UNCONN,
+	PCS_KRPC_STATE_CONNECTED,
+	PCS_KRPC_STATE_ABORTED,
+	PCS_KRPC_STATE_DESTROYED,
+};
+
+struct pcs_krpc {
+	struct hlist_node		hlist;
+	struct list_head		link;
+	spinlock_t				lock;
+	refcount_t				refcnt;
+
+	struct pcs_rpc			*rpc;
+
+	struct pcs_krpc_set		*krpcs;
+
+	PCS_NODE_ID_T			id;
+
+	int state;
+
+	struct list_head		pending_queue;
+	struct list_head		completion_queue;
+	int nr_completion;
+
+	/** Wait queue head for poll */
+	wait_queue_head_t		poll_wait;
+};
+
+/*
+ * Completion message to be received by userspace
+ */
+struct krpc_completion {
+	struct list_head	link;		/* in krpc->completion_queue */
+
+	u64			xid;
+	int			result;
+
+	void		*private;
+	int			data_len;
+	u8			_data_buf[0];
+};
+
+#define KRPC_MAX_DATA_PAGES			256
+#define NR_KRPC_DATA_CHUNKS_INLINE	4
+struct krpc_req {
+	struct list_head	link;
+	spinlock_t			lock;
+	struct pcs_krpc		*krpc;
+
+#define KRPC_REQ_F_ALIGNMENT	PCS_KRPC_MSG_F_ALIGNMENT
+#define KRPC_REQ_F_RESP_BUFF	PCS_KRPC_MSG_F_RESP_BUFF	/* data buff is for read response */
+#define KRPC_REQ_F_ABORTED		0x10000
+	int flags;
+
+	struct pcs_msg		msg;
+
+	char				*hdr_buf;
+	struct kvec			hdr_kv;
+	struct krpc_chunk	hdr_chunk;
+
+	int					nr_data_chunks;
+	struct krpc_chunk	*data_chunks;
+	struct krpc_chunk	inline_data_chunks[NR_KRPC_DATA_CHUNKS_INLINE];
+
+	int data_len;
+	int nr_data_bvecs;
+	struct bio_vec data_bvecs[KRPC_MAX_DATA_PAGES];
+
+	struct krpc_completion completion;
+};
+
+static inline u32 pcs_krpc_msg_size(u32 size, u8 flags)
+{
+	if (flags & PCS_KRPC_MSG_F_ALIGNMENT)
+		size = ALIGN(size, PCS_KRPC_MSG_ALIGNMENT);
+
+	return size;
+}
+
+int pcs_krpc_init(void);
+void pcs_krpc_fini(void);
+
+void pcs_krpcset_init(struct pcs_krpc_set *krpcs);
+void pcs_krpcset_fini(struct pcs_krpc_set *krpcs);
+
+struct pcs_krpc *pcs_krpc_lookup(struct pcs_krpc_set *krpcs, PCS_NODE_ID_T *id);
+int pcs_krpc_create(struct pcs_krpc_set *krpcs, PCS_NODE_ID_T *id,
+		PCS_NET_ADDR_T *addr, int cs_flags);
+int pcs_krpc_update_addr(struct pcs_krpc_set *krpcs, PCS_NODE_ID_T *id,
+		PCS_NET_ADDR_T *addr, int flags);
+int pcs_krpc_connect(struct pcs_krpc_set *krpcs, PCS_NODE_ID_T *id);
+int pcs_krpc_destroy(struct pcs_krpc_set *krpcs, PCS_NODE_ID_T *id);
+
+void pcs_krpc_put(struct pcs_krpc *krpc);
+struct pcs_krpc *pcs_krpc_get(struct pcs_krpc *krpc);
+
+struct pcs_msg *krpc_get_hdr(struct pcs_rpc *ep, struct pcs_rpc_hdr *h);
+void krpc_keep_waiting(struct pcs_rpc *ep, struct pcs_msg *req, struct pcs_msg *msg);
+void krpc_handle_congestion(struct pcs_rpc *ep, struct pcs_msg *msg);
+#endif
diff --git a/fs/fuse/kio/pcs/pcs_krpc_prot.h b/fs/fuse/kio/pcs/pcs_krpc_prot.h
new file mode 100644
index 000000000000..525f4e04d2cc
--- /dev/null
+++ b/fs/fuse/kio/pcs/pcs_krpc_prot.h
@@ -0,0 +1,44 @@
+#ifndef _PCS_KRPC_PROT_H_
+#define _PCS_KRPC_PROT_H_
+#include <linux/ioctl.h>
+
+#include "pcs_prot_types.h"
+
+/*Device ioctls: */
+#define PCS_KRPC_IOC_MAGIC  255
+
+/* ioctl cmds supported by the '[pcs_krpc]' anonymous inode */
+#define PCS_KRPC_IOC_SEND_MSG		_IO(PCS_KRPC_IOC_MAGIC, 10)
+#define PCS_KRPC_IOC_RECV_MSG		_IO(PCS_KRPC_IOC_MAGIC, 11)
+#define PCS_KRPC_IOC_ABORT			_IO(PCS_KRPC_IOC_MAGIC, 12)
+
+struct pcs_krpc_buf_desc {
+	u64  addr;		/* buf address in userspace. */
+	u32  len;		/* size of the buf */
+	u32  mr_id;		/* mr id */
+};
+
+#define PCS_KRPC_MSG_ALIGNMENT		(512ULL)
+
+#define PCS_KRPC_MSG_F_ALIGNMENT	0x01
+#define PCS_KRPC_MSG_F_RESP_BUFF	0x02
+/*
+ * To avoid copying, a msg is sent to kernel in an array of buffer descriptor.
+ * Each buffer descriptor points to a buf contains a chunk of the msg. And all
+ * chunk buffers are from registered MRs
+ */
+struct pcs_krpc_ioc_sendmsg {
+	u64		xid;				/* context id */
+	u32		msg_size;			/* total size of the msg */
+	u16		timeout;			/* timeout */
+	u8		flags;				/* alignment,  */
+	u8		nr_data_chunks;		/* total number of data chunks */
+	struct pcs_krpc_buf_desc hdr_chunk;	/* the buf holding msg header */
+};
+
+struct pcs_krpc_ioc_recvmsg {
+	u64		xid;	/* context id */
+	struct pcs_krpc_buf_desc buf;	/* for cs congestion notification and rpc keep waiting msg.*/
+};
+
+#endif
diff --git a/fs/fuse/kio/pcs/pcs_mr.c b/fs/fuse/kio/pcs/pcs_mr.c
index ad55b0cbad8b..c2a2c072ba9e 100644
--- a/fs/fuse/kio/pcs/pcs_mr.c
+++ b/fs/fuse/kio/pcs/pcs_mr.c
@@ -126,8 +126,10 @@ int pcs_reg_mr(struct pcs_mr_set *mrs, u64 start, u64 len)
 	}
 
 	umem = pcs_umem_get(start, len);
-	if (IS_ERR(umem))
+	if (IS_ERR(umem)) {
+		atomic_dec(&mrs->mr_num);
 		return PTR_ERR(umem);
+	}
 
 	mr = kzalloc(sizeof(*mr), GFP_KERNEL);
 	if (!mr) {
diff --git a/fs/fuse/kio/pcs/pcs_req.h b/fs/fuse/kio/pcs/pcs_req.h
index cdf1c9754803..b88e56d2b9a2 100644
--- a/fs/fuse/kio/pcs/pcs_req.h
+++ b/fs/fuse/kio/pcs/pcs_req.h
@@ -18,6 +18,8 @@
 #include "fuse_ktrace_prot.h"
 #include "fuse_stat.h"
 #include "../../fuse_i.h"
+#include "pcs_mr.h"
+#include "pcs_krpc.h"
 
 ///////////////////////////
 
@@ -168,7 +170,7 @@ struct pcs_int_request
 	union {
 		struct {
 			struct pcs_map_entry	*map;
-			//// Temproraly disable flow
+			/* Temproraly disable flow */
 			struct pcs_flow_node	*flow;
 			u8			cmd;
 			u8			role;
@@ -253,7 +255,7 @@ struct pcs_int_request
 	};
 };
 
-// FROM pcs_cluste_core.h
+/* FROM pcs_cluste_core.h */
 
 struct pcs_clnt_config
 {
@@ -284,9 +286,15 @@ struct pcs_cluster_core
 	struct pcs_map_set	maps;		/* Global map data */
 	struct pcs_rpc_engine	eng;		/* RPC engine */
 	struct workqueue_struct *wq;
-////	struct pcs_ratelimit	rlim;		/* Rate limiter */
-////	struct pcs_rng		rng;
+#if 0
+	struct pcs_ratelimit	rlim;		/* Rate limiter */
+	struct pcs_rng		rng;
+#endif
 	/* <SKIP */
+
+	struct pcs_mr_set	mrs;		/* Table of all MRs*/
+	struct pcs_krpc_set	krpcs;		/* Table of all KRPCs */
+
 	struct pcs_fuse_stat	stat;
 
 	struct {
@@ -337,10 +345,20 @@ static inline struct pcs_cluster_core *cc_from_maps(struct pcs_map_set *maps)
 	return container_of(maps, struct pcs_cluster_core, maps);
 }
 
+static inline struct pcs_cluster_core *cc_from_krpcset(struct pcs_krpc_set *krpcs)
+{
+	return container_of(krpcs, struct pcs_cluster_core, krpcs);
+}
+
+static inline struct pcs_cluster_core *cc_from_krpc(struct pcs_krpc *krpc)
+{
+	return cc_from_krpcset(krpc->krpcs);
+}
+
 void pcs_cc_submit(struct pcs_cluster_core *cc, struct pcs_int_request* ireq);
 void pcs_cc_requeue(struct pcs_cluster_core *cc, struct list_head * q);
 void pcs_cc_update_storage_versions(struct pcs_cluster_core *cc, int version);
-////// FROM pcs_cluster.h
+/* FROM pcs_cluster.h */
 static inline void pcs_sreq_attach(struct pcs_int_request * sreq, struct pcs_int_request * parent)
 {
 	sreq->completion_data.parent = parent;
@@ -421,4 +439,6 @@ typedef void (*kio_req_itr)(struct fuse_file *ff, struct fuse_req *req,
 void pcs_kio_req_list(struct fuse_conn *fc, kio_req_itr kreq_cb, void *ctx);
 extern struct crypto_shash *crc_tfm;
 
+
+
 #endif /* _PCS_REQ_H_ */
diff --git a/fs/fuse/kio/pcs/pcs_rpc.c b/fs/fuse/kio/pcs/pcs_rpc.c
index 3b763cea9c01..deebc1dddf1b 100644
--- a/fs/fuse/kio/pcs/pcs_rpc.c
+++ b/fs/fuse/kio/pcs/pcs_rpc.c
@@ -292,7 +292,8 @@ void pcs_rpc_attach_new_ep(struct pcs_rpc * ep, struct pcs_rpc_engine * eng)
 	ep->peer_flags = 0;
 	ep->peer_version = ~0U;
 	ep->conn = NULL;
-	ep->private = NULL;
+	ep->clnt_cs = NULL;
+	ep->clnt_krpc = NULL;
 	INIT_LIST_HEAD(&ep->pending_queue);
 	INIT_LIST_HEAD(&ep->state_queue);
 	INIT_LIST_HEAD(&ep->input_queue);
diff --git a/fs/fuse/kio/pcs/pcs_rpc.h b/fs/fuse/kio/pcs/pcs_rpc.h
index ef4ab26b9d44..f7df01ef9a49 100644
--- a/fs/fuse/kio/pcs/pcs_rpc.h
+++ b/fs/fuse/kio/pcs/pcs_rpc.h
@@ -153,7 +153,9 @@ struct pcs_rpc
 	struct hlist_head	kill_calendar[RPC_MAX_CALENDAR];
 	struct llist_node	cleanup_node;
 
-	struct pcs_cs *		private;
+	struct pcs_cs	*clnt_cs;
+	struct pcs_krpc	*clnt_krpc;
+	int nr_clnts;
 };
 
 struct pcs_rpc_engine
diff --git a/fs/fuse/kio/pcs/pcs_rpc_clnt.c b/fs/fuse/kio/pcs/pcs_rpc_clnt.c
new file mode 100644
index 000000000000..11b7c3175bf5
--- /dev/null
+++ b/fs/fuse/kio/pcs/pcs_rpc_clnt.c
@@ -0,0 +1,188 @@
+/*
+ *  fs/fuse/kio/pcs/pcs_rpc_clnt.c
+ *
+ *  Copyright (c) 2018-2024 Virtuozzo International GmbH. All rights reserved.
+ *
+ */
+
+#include <linux/types.h>
+
+#include "pcs_types.h"
+#include "pcs_rpc.h"
+#include "pcs_cluster.h"
+#include "pcs_sock_io.h"
+#include "pcs_sock_conn.h"
+#include "pcs_rdma_conn.h"
+#include "pcs_net_addr.h"
+#include "log.h"
+#include "fuse_ktrace.h"
+#include "pcs_cs.h"
+#include "pcs_krpc.h"
+
+static int clnt_input(struct pcs_rpc *ep, struct pcs_msg *msg)
+{
+	struct pcs_rpc_hdr *h = (struct pcs_rpc_hdr *)msg->_inline_buffer;
+
+	switch (h->type) {
+	case PCS_CS_CONG_NOTIFY:
+		if (ep->clnt_cs)
+			cs_handle_congestion(ep->clnt_cs, h);
+
+		if (ep->clnt_krpc)
+			krpc_handle_congestion(ep, msg);
+		return 0;
+	default:
+		FUSE_KLOG(cc_from_rpc(ep->eng)->fc, LOG_ERR, "Unsupported message type %u", h->type);
+		return PCS_ERR_PROTOCOL;
+	}
+}
+
+
+static struct pcs_msg *clnt_get_hdr(struct pcs_rpc *ep, struct pcs_rpc_hdr *h)
+{
+	if (h->xid.origin.val & PCS_NODE_ALT_MASK)
+		return cs_get_hdr(ep, h);
+	else
+		return krpc_get_hdr(ep, h);
+}
+
+void clnt_aborting(struct pcs_rpc *ep, int error)
+{
+	pcs_rpc_reset(ep);
+}
+
+static void clnt_keep_waiting(struct pcs_rpc *ep, struct pcs_msg *req, struct pcs_msg *msg)
+{
+	struct pcs_rpc_hdr *req_h = (struct pcs_rpc_hdr *)msg_inline_head(req);
+
+	if (req_h->xid.origin.val & PCS_NODE_ALT_MASK)
+		cs_keep_waiting(ep, req, msg);
+	else
+		krpc_keep_waiting(ep, req, msg);
+}
+
+static void clnt_connect(struct pcs_rpc *ep)
+{
+	void (*connect_start)(struct pcs_rpc *);
+
+	if (ep->flags & PCS_RPC_F_LOCAL) {
+		char path[128];
+
+		snprintf(path, sizeof(path)-1, PCS_SHM_DIR "/%llu_" CLUSTER_ID_FMT,
+			 (unsigned long long)ep->peer_id.val, CLUSTER_ID_ARGS(ep->eng->cluster_id));
+
+		if ((strlen(path) + 1) > sizeof(((struct sockaddr_un *) 0)->sun_path)) {
+			TRACE("Path to local socket is too long: %s", path);
+
+			ep->flags &= ~PCS_RPC_F_LOCAL;
+			goto fail;
+		}
+		memset(&ep->sh.sun, 0, sizeof(struct sockaddr_un));
+		ep->sh.sun.sun_family = AF_UNIX;
+		ep->sh.sa_len = sizeof(struct sockaddr_un);
+		strcpy(ep->sh.sun.sun_path, path);
+		connect_start = pcs_sockconnect_start;
+	} else {
+		/* TODO: print sock addr using pcs_format_netaddr() */
+		if (pcs_netaddr2sockaddr(&ep->addr, &ep->sh.sa, &ep->sh.sa_len)) {
+			TRACE("netaddr to sockaddr failed");
+			goto fail;
+		}
+		connect_start = ep->addr.type == PCS_ADDRTYPE_RDMA ?
+			pcs_rdmaconnect_start : pcs_sockconnect_start;
+	}
+	ep->state = PCS_RPC_CONNECT;
+	connect_start(ep); /* TODO: rewrite to use pcs_netconnect callback */
+	return;
+
+fail:
+	pcs_rpc_report_error(ep, PCS_RPC_ERR_CONNECT_ERROR);
+	pcs_rpc_reset(ep);
+}
+
+struct pcs_rpc_params clnt_rpc_params = {
+	.alloc_hdr_size		= sizeof(struct pcs_rpc_hdr),
+	.max_msg_size		= PCS_CS_MSG_MAX_SIZE,
+	.holddown_timeout	= HZ,
+	.connect_timeout	= 5*HZ,
+	.response_timeout	= 30*HZ,
+	.max_conn_retry		= 3,
+	.flags			= 0,
+};
+
+struct pcs_rpc_ops clnt_rpc_ops = {
+	.demux_request		= clnt_input,
+	.get_hdr			= clnt_get_hdr,
+	.state_change		= clnt_aborting,
+	.connect			= clnt_connect,
+	.keep_waiting		= clnt_keep_waiting,
+};
+
+
+struct pcs_rpc *pcs_rpc_clnt_create(struct pcs_rpc_engine *eng, PCS_NODE_ID_T *peer_id,
+				PCS_NET_ADDR_T *peer_addr, int flags)
+{
+	struct pcs_rpc *ep = NULL;
+
+	/*
+	 * It's not expected this function to be called frequently,
+	 * slow version of search is acceptable here.
+	 */
+	spin_lock(&eng->lock);
+	hlist_for_each_entry(ep, &eng->unhashed, link) {
+		if (memcmp(&ep->peer_id, peer_id, sizeof(ep->peer_id)) == 0) {
+			pcs_rpc_get(ep);
+			break;
+		}
+	}
+	spin_unlock(&eng->lock);
+
+	if (ep) {
+		mutex_lock(&ep->mutex);
+		if (ep->state != PCS_RPC_DESTROY)
+			goto found;
+
+		mutex_unlock(&ep->mutex);
+	}
+
+	/* create a new pcs_rpc instance if found one had been closed by its last owner */
+	ep = pcs_rpc_alloc_ep();
+	if (!ep)
+		return NULL;
+
+	pcs_rpc_attach_new_ep(ep, eng);
+	pcs_rpc_configure_new_ep(ep, &clnt_rpc_params, &clnt_rpc_ops);
+
+	pcs_rpc_set_peer_id(ep, peer_id, PCS_NODE_ROLE_CS);
+	pcs_rpc_set_address(ep, peer_addr);
+
+	if (flags & CS_FL_LOCAL_SOCK)
+		ep->flags |= PCS_RPC_F_LOCAL;
+	else
+		ep->flags &= ~PCS_RPC_F_LOCAL;
+
+	mutex_lock(&ep->mutex);
+found:
+	ep->nr_clnts++;
+	mutex_unlock(&ep->mutex);
+
+	return ep;
+}
+
+void pcs_rpc_clnt_close(struct pcs_rpc *ep)
+{
+	mutex_lock(&ep->mutex);
+	BUG_ON(ep->flags & PCS_RPC_F_DEAD);
+	BUG_ON(ep->flags & PCS_RPC_F_PASSIVE);
+
+	ep->nr_clnts--;
+	if (!ep->nr_clnts) {
+		/* close the rpc if we're the last rpc client */
+		ep->flags |= PCS_RPC_F_DEAD;
+		rpc_abort(ep, 1, PCS_ERR_NET_ABORT);
+		ep->state = PCS_RPC_DESTROY;
+	}
+	mutex_unlock(&ep->mutex);
+
+	pcs_rpc_put(ep);
+}
diff --git a/fs/fuse/kio/pcs/pcs_rpc_clnt.h b/fs/fuse/kio/pcs/pcs_rpc_clnt.h
new file mode 100644
index 000000000000..7afe59e9c992
--- /dev/null
+++ b/fs/fuse/kio/pcs/pcs_rpc_clnt.h
@@ -0,0 +1,16 @@
+/*
+ *  fs/fuse/kio/pcs/pcs_rpc_clnt.h
+ *
+ *  Copyright (c) 2018-2024 Virtuozzo International GmbH. All rights reserved.
+ *
+ */
+
+#ifndef _PCS_RPC_CLNT_H_
+#define _PCS_RPC_CLNT_H_ 1
+#include "pcs_rpc.h"
+
+struct pcs_rpc *pcs_rpc_clnt_create(struct pcs_rpc_engine *eng,
+		PCS_NODE_ID_T *peer_id, PCS_NET_ADDR_T *peer_addr, int flags);
+void pcs_rpc_clnt_close(struct pcs_rpc *ep);
+
+#endif
-- 
2.39.3 (Apple Git-146)



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