WIP Separate data connections

Prelimilary results:
- CPU usage drops significantly. For example, in T1Q8 128K write test against
  stub_uring_osd with 10G network and Athlon X4 860k CPU it drops from 100% to 30%
- Latency becomes slightly worse. In T1Q1 4K write test in the same environment
  latency increases from 56 to 63 us.
- Small write throughput also becomes slightly worse. In T1Q128 4K write test
  against stub iops decreases from 138k to ~110k (unstable, fluctuates 100k..120k).
  Note that this is without io_uring, of course.

src/fio_sec_osd.cpp

@@ -33,12 +33,18 @@
 #include "osd_ops.h"
 #include "fio_headers.h"
 
+struct op_buf_t
+{
+    osd_any_op_t buf;
+    io_u* fio_op;
+};
+
 struct sec_data
 {
     int connect_fd;
     /* block_size = 1 << block_order (128KB by default) */
     uint64_t block_order = 17, block_size = 1 << 17;
-    std::unordered_map<uint64_t, io_u*> queue;
+    std::unordered_map<uint64_t, op_buf_t*> queue;
     bool last_sync = false;
     /* The list of completed io_u structs. */
     std::vector<io_u*> completed;
@@ -53,6 +59,7 @@ struct sec_options
     int single_primary = 0;
     int trace = 0;
     int block_order = 17;
+    int zerocopy_send = 0;
 };
 
 static struct fio_option options[] = {
@@ -103,6 +110,16 @@ static struct fio_option options[] = {
         .category = FIO_OPT_C_ENGINE,
         .group  = FIO_OPT_G_FILENAME,
     },
+    {
+        .name   = "zerocopy_send",
+        .lname  = "Use zero-copy send",
+        .type   = FIO_OPT_BOOL,
+        .off1   = offsetof(struct sec_options, zerocopy_send),
+        .help   = "Use zero-copy send (MSG_ZEROCOPY)",
+        .def    = "0",
+        .category = FIO_OPT_C_ENGINE,
+        .group  = FIO_OPT_G_FILENAME,
+    },
     {
         .name = NULL,
     },
@@ -173,6 +190,14 @@ static int sec_init(struct thread_data *td)
     }
     int one = 1;
     setsockopt(bsd->connect_fd, SOL_TCP, TCP_NODELAY, &one, sizeof(one));
+    if (o->zerocopy_send)
+    {
+        if (setsockopt(bsd->connect_fd, SOL_SOCKET, SO_ZEROCOPY, &one, sizeof(one)) < 0)
+        {
+            perror("setsockopt zerocopy");
+            return 1;
+        }
+    }
 
     // FIXME: read config (block size) from OSD
 
@@ -193,7 +218,9 @@ static enum fio_q_status sec_queue(struct thread_data *td, struct io_u *io)
     }
 
     io->engine_data = bsd;
-    osd_any_op_t op = { 0 };
+    op_buf_t *op_buf = new op_buf_t;
+    op_buf->fio_op = io;
+    osd_any_op_t &op = op_buf->buf;
 
     op.hdr.magic = SECONDARY_OSD_OP_MAGIC;
     op.hdr.id = n;
@@ -269,19 +296,18 @@ static enum fio_q_status sec_queue(struct thread_data *td, struct io_u *io)
     io->error = 0;
     bsd->inflight++;
     bsd->op_n++;
-    bsd->queue[n] = io;
+    bsd->queue[n] = op_buf;
 
     iovec iov[2] = { { .iov_base = op.buf, .iov_len = OSD_PACKET_SIZE } };
     int iovcnt = 1, wtotal = OSD_PACKET_SIZE;
     if (io->ddir == DDIR_WRITE)
     {
-        iov[1] = { .iov_base = io->xfer_buf, .iov_len = io->xfer_buflen };
+        iov[iovcnt++] = { .iov_base = io->xfer_buf, .iov_len = io->xfer_buflen };
         wtotal += io->xfer_buflen;
-        iovcnt++;
     }
-    if (writev_blocking(bsd->connect_fd, iov, iovcnt) != wtotal)
+    if (sendv_blocking(bsd->connect_fd, iov, iovcnt, opt->zerocopy_send ? MSG_ZEROCOPY : 0) != wtotal)
     {
-        perror("writev");
+        perror("sendmsg");
         exit(1);
     }
 
@@ -310,7 +336,8 @@ static int sec_getevents(struct thread_data *td, unsigned int min, unsigned int
             fprintf(stderr, "bad reply: op id %lx missing in local queue\n", reply.hdr.id);
             exit(1);
         }
-        io_u* io = it->second;
+        io_u* io = it->second->fio_op;
+        delete it->second;
         bsd->queue.erase(it);
         if (io->ddir == DDIR_READ)
         {
@@ -319,7 +346,23 @@ static int sec_getevents(struct thread_data *td, unsigned int min, unsigned int
                 fprintf(stderr, "Short read: retval = %ld instead of %llu\n", reply.hdr.retval, io->xfer_buflen);
                 exit(1);
             }
-            read_blocking(bsd->connect_fd, io->xfer_buf, io->xfer_buflen);
+            // Support bitmap
+            uint64_t bitmap = 0;
+            int iovcnt = 0;
+            iovec iov[2];
+            if (reply.sec_rw.attr_len > 0)
+            {
+                if (reply.sec_rw.attr_len <= 8)
+                    iov[iovcnt++] = { .iov_base = &bitmap, .iov_len = reply.sec_rw.attr_len };
+                else
+                    iov[iovcnt++] = { .iov_base = (void*)(bitmap = (uint64_t)malloc(reply.sec_rw.attr_len)), .iov_len = reply.sec_rw.attr_len };
+            }
+            iov[iovcnt++] = { .iov_base = io->xfer_buf, .iov_len = io->xfer_buflen };
+            readv_blocking(bsd->connect_fd, iov, iovcnt);
+            if (reply.sec_rw.attr_len > 8)
+            {
+                free((void*)bitmap);
+            }
         }
         else if (io->ddir == DDIR_WRITE)
         {

src/messenger.cpp

@@ -4,10 +4,12 @@
 #include <unistd.h>
 #include <fcntl.h>
 #include <sys/socket.h>
+#include <sys/random.h>
 #include <sys/epoll.h>
 #include <netinet/tcp.h>
 #include <stdexcept>
 
+#include "base64.h"
 #include "addr_util.h"
 #include "messenger.h"
 
@@ -194,7 +196,7 @@ void osd_messenger_t::connect_peer(uint64_t peer_osd, json11::Json peer_state)
     try_connect_peer(peer_osd);
 }
 
-void osd_messenger_t::try_connect_peer(uint64_t peer_osd)
+void osd_messenger_t::try_connect_peer(osd_num_t peer_osd)
 {
     auto wp_it = wanted_peers.find(peer_osd);
     if (wp_it == wanted_peers.end() || wp_it->second.connecting ||
@@ -215,40 +217,75 @@ void osd_messenger_t::try_connect_peer(uint64_t peer_osd)
     wp.cur_addr = wp.address_list[wp.address_index].string_value();
     wp.cur_port = wp.port;
     wp.connecting = true;
-    try_connect_peer_addr(peer_osd, wp.cur_addr.c_str(), wp.cur_port);
+    try_connect_peer_addr(peer_osd, wp.cur_addr.c_str(), wp.cur_port, NULL, [this](osd_num_t peer_osd, int peer_fd)
+    {
+        if (peer_fd >= 0)
+            osd_peer_fds[peer_osd] = peer_fd;
+        on_connect_peer(peer_osd, peer_fd);
+    });
 }
 
-void osd_messenger_t::try_connect_peer_addr(osd_num_t peer_osd, const char *peer_host, int peer_port)
+static std::string urandom_str(int bytes)
+{
+    std::string str;
+    str.resize(bytes);
+    char *buf = (char*)str.data();
+    while (bytes > 0)
+    {
+        int r = getrandom(buf, bytes, 0);
+        if (r < 0)
+            throw std::runtime_error(std::string("getrandom: ") + strerror(errno));
+        buf += r;
+        bytes -= r;
+    }
+    return str;
+}
+
+void osd_messenger_t::try_connect_peer_addr(osd_num_t peer_osd, const char *peer_host, int peer_port,
+    osd_client_t *meta_cl, std::function<void(osd_num_t, int)> connect_callback)
 {
     assert(peer_osd != this->osd_num);
     struct sockaddr addr;
-    if (!string_to_addr(peer_host, 0, peer_port, &addr))
+    if (!meta_cl)
     {
-        on_connect_peer(peer_osd, -EINVAL);
+        if (!string_to_addr(peer_host, 0, peer_port, &addr))
-        return;
+        {
+            connect_callback(peer_osd, -EINVAL);
+            return;
+        }
+    }
+    else
+    {
+        addr = meta_cl->peer_addr;
     }
     int peer_fd = socket(addr.sa_family, SOCK_STREAM, 0);
+    if (peer_fd >= 0)
+    {
+        fcntl(peer_fd, F_SETFL, fcntl(peer_fd, F_GETFL, 0) | O_NONBLOCK);
+        int r = connect(peer_fd, (sockaddr*)&addr, sizeof(addr));
+        if (r < 0 && errno != EINPROGRESS)
+        {
+            close(peer_fd);
+            peer_fd = -1;
+        }
+    }
     if (peer_fd < 0)
     {
-        on_connect_peer(peer_osd, -errno);
+        connect_callback(peer_osd, -errno);
-        return;
-    }
-    fcntl(peer_fd, F_SETFL, fcntl(peer_fd, F_GETFL, 0) | O_NONBLOCK);
-    int r = connect(peer_fd, (sockaddr*)&addr, sizeof(addr));
-    if (r < 0 && errno != EINPROGRESS)
-    {
-        close(peer_fd);
-        on_connect_peer(peer_osd, -errno);
         return;
     }
     clients[peer_fd] = new osd_client_t();
     clients[peer_fd]->peer_addr = addr;
-    clients[peer_fd]->peer_port = peer_port;
+    clients[peer_fd]->peer_port = ((struct sockaddr_in*)&addr)->sin_port;
     clients[peer_fd]->peer_fd = peer_fd;
     clients[peer_fd]->peer_state = PEER_CONNECTING;
     clients[peer_fd]->connect_timeout_id = -1;
+    clients[peer_fd]->connect_callback = connect_callback;
     clients[peer_fd]->osd_num = peer_osd;
     clients[peer_fd]->in_buf = malloc_or_die(receive_buffer_size);
+    clients[peer_fd]->data_for = meta_cl ? addr_to_string(meta_cl->peer_addr) : "";
+    clients[peer_fd]->data_connection_cookie = meta_cl
+        ? meta_cl->data_connection_cookie : base64_encode(urandom_str(12));
     tfd->set_fd_handler(peer_fd, true, [this](int peer_fd, int epoll_events)
     {
         // Either OUT (connected) or HUP
@@ -258,10 +295,12 @@ void osd_messenger_t::try_connect_peer_addr(osd_num_t peer_osd, const char *peer
     {
         clients[peer_fd]->connect_timeout_id = tfd->set_timer(1000*peer_connect_timeout, false, [this, peer_fd](int timer_id)
         {
-            osd_num_t peer_osd = clients.at(peer_fd)->osd_num;
+            auto cl = clients.at(peer_fd);
+            auto connect_callback = cl->connect_callback;
+            cl->connect_callback = NULL;
+            osd_num_t peer_osd = cl->osd_num;
             stop_client(peer_fd, true);
-            on_connect_peer(peer_osd, -EPIPE);
+            connect_callback(peer_osd, -EPIPE);
-            return;
         });
     }
 }
@@ -283,8 +322,10 @@ void osd_messenger_t::handle_connect_epoll(int peer_fd)
     }
     if (result != 0)
     {
+        auto connect_callback = cl->connect_callback;
+        cl->connect_callback = NULL;
         stop_client(peer_fd, true);
-        on_connect_peer(peer_osd, -result);
+        connect_callback(peer_osd, -result);
         return;
     }
     int one = 1;
@@ -364,6 +405,11 @@ void osd_messenger_t::on_connect_peer(osd_num_t peer_osd, int peer_fd)
 
 void osd_messenger_t::check_peer_config(osd_client_t *cl)
 {
+    json11::Json::object payload;
+    if (cl->data_connection_cookie != "")
+    {
+        payload["data_cookie"] = cl->data_connection_cookie;
+    }
     osd_op_t *op = new osd_op_t();
     op->op_type = OSD_OP_OUT;
     op->peer_fd = cl->peer_fd;
@@ -376,24 +422,33 @@ void osd_messenger_t::check_peer_config(osd_client_t *cl)
             },
         },
     };
-#ifdef WITH_RDMA
+    if (cl->data_for == "")
-    if (rdma_context)
     {
-        cl->rdma_conn = msgr_rdma_connection_t::create(rdma_context, rdma_max_send, rdma_max_recv, rdma_max_sge, rdma_max_msg);
+#ifdef WITH_RDMA
-        if (cl->rdma_conn)
+        if (rdma_context)
         {
-            json11::Json payload = json11::Json::object {
+            cl->rdma_conn = msgr_rdma_connection_t::create(rdma_context, rdma_max_send, rdma_max_recv, rdma_max_sge, rdma_max_msg);
-                { "connect_rdma", cl->rdma_conn->addr.to_string() },
+            if (cl->rdma_conn)
-                { "rdma_max_msg", cl->rdma_conn->max_msg },
+            {
-            };
+                payload["connect_rdma"] = cl->rdma_conn->addr.to_string();
-            std::string payload_str = payload.dump();
+                payload["rdma_max_msg"] = cl->rdma_conn->max_msg;
-            op->req.show_conf.json_len = payload_str.size();
+            }
-            op->buf = malloc_or_die(payload_str.size());
-            op->iov.push_back(op->buf, payload_str.size());
-            memcpy(op->buf, payload_str.c_str(), payload_str.size());
         }
-    }
 #endif
+    }
+    else
+    {
+        // Mark it as a data connection
+        payload["data_for"] = cl->data_for;
+    }
+    if (payload.size())
+    {
+        std::string payload_str = json11::Json(payload).dump();
+        op->req.show_conf.json_len = payload_str.size();
+        op->buf = malloc_or_die(payload_str.size());
+        op->iov.push_back(op->buf, payload_str.size());
+        memcpy(op->buf, payload_str.c_str(), payload_str.size());
+    }
     op->callback = [this, cl](osd_op_t *op)
     {
         std::string json_err;
@@ -426,18 +481,30 @@ void osd_messenger_t::check_peer_config(osd_client_t *cl)
                     cl->osd_num, config["protocol_version"].uint64_value(), OSD_PROTOCOL_VERSION
                 );
             }
+            else if (cl->data_for != "" && config["data_for"] != cl->data_for)
+            {
+                err = true;
+                fprintf(
+                    stderr, "OSD %lu does not support separate data connections."
+                    " Proceeding with a single connection\n", cl->osd_num
+                );
+            }
         }
         if (err)
         {
             osd_num_t peer_osd = cl->osd_num;
+            auto connect_callback = cl->connect_callback;
+            cl->connect_callback = NULL;
             stop_client(op->peer_fd);
-            on_connect_peer(peer_osd, -1);
+            connect_callback(peer_osd, -EINVAL);
             delete op;
             return;
         }
 #ifdef WITH_RDMA
-        if (config["rdma_address"].is_string())
+        if (rdma_context && cl->rdma_conn && config["rdma_address"].is_string())
         {
+            // Prevent creating data connection - we are trying RDMA
+            cl->data_connection_cookie = "";
             msgr_rdma_address_t addr;
             if (!msgr_rdma_address_t::from_string(config["rdma_address"].string_value().c_str(), &addr) ||
                 cl->rdma_conn->connect(&addr) != 0)
@@ -450,8 +517,10 @@ void osd_messenger_t::check_peer_config(osd_client_t *cl)
                 cl->rdma_conn = NULL;
                 // FIXME: Keep TCP connection in this case
                 osd_num_t peer_osd = cl->osd_num;
+                auto connect_callback = cl->connect_callback;
+                cl->connect_callback = NULL;
                 stop_client(cl->peer_fd);
-                on_connect_peer(peer_osd, -1);
+                connect_callback(peer_osd, -EPIPE);
                 delete op;
                 return;
             }
@@ -473,8 +542,37 @@ void osd_messenger_t::check_peer_config(osd_client_t *cl)
             }
         }
 #endif
-        osd_peer_fds[cl->osd_num] = cl->peer_fd;
+        if (cl->data_connection_cookie != "")
-        on_connect_peer(cl->osd_num, cl->peer_fd);
+        {
+            // Try to open second connection to the same address
+            try_connect_peer_addr(cl->osd_num, NULL, 0, cl, [this, peer_fd = cl->peer_fd](osd_num_t data_peer, int data_peer_fd)
+            {
+                auto cl_it = clients.find(peer_fd);
+                if (cl_it != clients.end())
+                {
+                    // Proceed with or without the data connection
+                    auto cl = cl_it->second;
+                    if (data_peer_fd >= 0)
+                    {
+                        cl->data_connection_fd = data_peer_fd;
+                        auto data_cl = clients.at(data_peer_fd);
+                        data_cl->meta_connection_fd = cl->peer_fd;
+                    }
+                    osd_peer_fds[cl->osd_num] = cl->peer_fd;
+                    on_connect_peer(cl->osd_num, cl->peer_fd);
+                }
+                else if (data_peer_fd >= 0)
+                {
+                    stop_client(data_peer_fd);
+                }
+            });
+        }
+        else
+        {
+            auto connect_callback = cl->connect_callback;
+            cl->connect_callback = NULL;
+            connect_callback(cl->osd_num, cl->peer_fd);
+        }
         delete op;
     };
     outbox_push(op);
@@ -500,6 +598,7 @@ void osd_messenger_t::accept_connections(int listen_fd)
         clients[peer_fd]->peer_fd = peer_fd;
         clients[peer_fd]->peer_state = PEER_CONNECTED;
         clients[peer_fd]->in_buf = malloc_or_die(receive_buffer_size);
+        clients_by_addr[addr_to_string(addr)] = peer_fd;
         // Add FD to epoll
         tfd->set_fd_handler(peer_fd, false, [this](int peer_fd, int epoll_events)
         {

src/messenger.h

@@ -57,6 +57,10 @@ struct osd_client_t
     int ping_time_remaining = 0;
     int idle_time_remaining = 0;
     osd_num_t osd_num = 0;
+    std::function<void(osd_num_t, int)> connect_callback;
+
+    int data_connection_fd = -1, meta_connection_fd = -1;
+    std::string data_connection_cookie, data_for;
 
     void *in_buf = NULL;
 
@@ -148,6 +152,7 @@ public:
     osd_num_t osd_num;
     uint64_t next_subop_id = 1;
     std::map<int, osd_client_t*> clients;
+    std::map<std::string, int> clients_by_addr;
     std::map<osd_num_t, osd_wanted_peer_t> wanted_peers;
     std::map<uint64_t, int> osd_peer_fds;
     // op statistics
@@ -157,6 +162,7 @@ public:
     void parse_config(const json11::Json & config);
     void connect_peer(uint64_t osd_num, json11::Json peer_state);
     void stop_client(int peer_fd, bool force = false, bool force_delete = false);
+    void break_data_client_pair(osd_client_t *cl);
     void outbox_push(osd_op_t *cur_op);
     std::function<void(osd_op_t*)> exec_op;
     std::function<void(osd_num_t)> repeer_pgs;
@@ -174,7 +180,8 @@ public:
 
 protected:
     void try_connect_peer(uint64_t osd_num);
-    void try_connect_peer_addr(osd_num_t peer_osd, const char *peer_host, int peer_port);
+    void try_connect_peer_addr(osd_num_t peer_osd, const char *peer_host, int peer_port,
+        osd_client_t *meta_cl, std::function<void(osd_num_t, int)> connect_callback);
     void handle_peer_epoll(int peer_fd, int epoll_events);
     void handle_connect_epoll(int peer_fd);
     void on_connect_peer(osd_num_t peer_osd, int peer_fd);

src/msgr_stop.cpp

@@ -4,6 +4,7 @@
 #include <unistd.h>
 #include <assert.h>
 
+#include "addr_util.h"
 #include "messenger.h"
 
 void osd_messenger_t::cancel_osd_ops(osd_client_t *cl)
@@ -58,7 +59,8 @@ void osd_messenger_t::stop_client(int peer_fd, bool force, bool force_delete)
     {
         if (cl->osd_num)
         {
-            fprintf(stderr, "[OSD %lu] Stopping client %d (OSD peer %lu)\n", osd_num, peer_fd, cl->osd_num);
+            fprintf(stderr, "[OSD %lu] Stopping client %d (OSD %speer %lu)\n",
+                osd_num, peer_fd, cl->meta_connection_fd >= 0 ? " data" : "", cl->osd_num);
         }
         else
         {
@@ -68,7 +70,7 @@ void osd_messenger_t::stop_client(int peer_fd, bool force, bool force_delete)
     // First set state to STOPPED so another stop_client() call doesn't try to free it again
     cl->refs++;
     cl->peer_state = PEER_STOPPED;
-    if (cl->osd_num)
+    if (cl->osd_num && cl->meta_connection_fd < 0)
     {
         // ...and forget OSD peer
         osd_peer_fds.erase(cl->osd_num);
@@ -100,9 +102,17 @@ void osd_messenger_t::stop_client(int peer_fd, bool force, bool force_delete)
 #endif
     if (cl->osd_num)
     {
-        // Then repeer PGs because cancel_op() callbacks can try to perform
+        if (cl->meta_connection_fd < 0)
-        // some actions and we need correct PG states to not do something silly
+        {
-        repeer_pgs(cl->osd_num);
+            // Then repeer PGs because cancel_op() callbacks can try to perform
+            // some actions and we need correct PG states to not do something silly
+            repeer_pgs(cl->osd_num);
+        }
+        else
+        {
+            // FIXME Try to re-establish data connection
+            // Only when the connection is outbound, but here it's always outbound
+        }
     }
     // Then cancel all operations
     if (cl->read_op)
@@ -128,6 +138,7 @@ void osd_messenger_t::stop_client(int peer_fd, bool force, bool force_delete)
         delete cl->rdma_conn;
     }
 #endif
+    clients_by_addr.erase(addr_to_string(cl->peer_addr));
 #endif
     // Find the item again because it can be invalidated at this point
     it = clients.find(peer_fd);
@@ -135,9 +146,40 @@ void osd_messenger_t::stop_client(int peer_fd, bool force, bool force_delete)
     {
         clients.erase(it);
     }
+    // Break metadata/data connection pair
+    if (cl->data_connection_fd >= 0)
+    {
+        // No sense to keep data connection when metadata connection is stopped
+        auto dc_it = clients.find(cl->data_connection_fd);
+        cl->data_connection_fd = -1;
+        if (dc_it != clients.end() && dc_it->second->meta_connection_fd == cl->peer_fd)
+        {
+            stop_client(dc_it->second->peer_fd);
+        }
+    }
+    break_data_client_pair(cl);
+    // Refcount and delete
     cl->refs--;
     if (cl->refs <= 0 || force_delete)
     {
         delete cl;
     }
 }
+
+void osd_messenger_t::break_data_client_pair(osd_client_t *cl)
+{
+    if (cl->meta_connection_fd >= 0)
+    {
+        auto dc_it = clients.find(cl->meta_connection_fd);
+        if (dc_it != clients.end() && dc_it->second->data_connection_fd == cl->peer_fd)
+            dc_it->second->data_connection_fd = -1;
+        cl->meta_connection_fd = -1;
+    }
+    if (cl->data_connection_fd >= 0)
+    {
+        auto dc_it = clients.find(cl->data_connection_fd);
+        if (dc_it != clients.end() && dc_it->second->meta_connection_fd == cl->peer_fd)
+            dc_it->second->meta_connection_fd = -1;
+        cl->data_connection_fd = -1;
+    }
+}

src/osd_secondary.cpp

@@ -178,6 +178,37 @@ void osd_t::exec_show_config(osd_op_t *cur_op)
             }
         }
     }
+    else
+    {
+#endif
+        if (req_json["data_for"].is_string())
+        {
+            auto cli = msgr.clients.at(cur_op->peer_fd);
+            auto md_it = msgr.clients_by_addr.find(req_json["data_for"].string_value());
+            if (md_it != msgr.clients_by_addr.end())
+            {
+                int md_peer_fd = md_it->second;
+                auto md_it = msgr.clients.find(md_peer_fd);
+                if (md_it != msgr.clients.end() && md_it->second->data_connection_cookie != "" &&
+                    req_json["data_cookie"].string_value() == md_it->second->data_connection_cookie)
+                {
+                    // Break previous metadata/data connections for both FDs, if present
+                    msgr.break_data_client_pair(cli);
+                    msgr.break_data_client_pair(md_it->second);
+                    // And setup the new pair
+                    cli->meta_connection_fd = md_it->second->peer_fd;
+                    md_it->second->data_connection_fd = cli->peer_fd;
+                    wire_config["data_for"] = req_json["data_for"];
+                }
+            }
+        }
+        else if (req_json["data_cookie"].is_string())
+        {
+            auto cli = msgr.clients.at(cur_op->peer_fd);
+            cli->data_connection_cookie = req_json["data_cookie"].string_value();
+        }
+#ifdef WITH_RDMA
+    }
 #endif
     if (cur_op->buf)
         free(cur_op->buf);

src/rw_blocking.cpp

@@ -4,6 +4,8 @@
 #include <errno.h>
 #include <stdlib.h>
 #include <stdio.h>
+#include <sys/types.h>
+#include <sys/socket.h>
 
 #include "rw_blocking.h"
 
@@ -123,3 +125,41 @@ int writev_blocking(int fd, iovec *iov, int iovcnt)
     }
     return done;
 }
+
+int sendv_blocking(int fd, iovec *iov, int iovcnt, int flags)
+{
+    struct msghdr msg = { 0 };
+    int v = 0;
+    int done = 0;
+    while (v < iovcnt)
+    {
+        msg.msg_iov = iov+v;
+        msg.msg_iovlen = iovcnt-v;
+        ssize_t r = sendmsg(fd, &msg, flags);
+        if (r < 0)
+        {
+            if (errno != EAGAIN && errno != EPIPE)
+            {
+                perror("sendmsg");
+                exit(1);
+            }
+            continue;
+        }
+        done += r;
+        while (v < iovcnt)
+        {
+            if (iov[v].iov_len > r)
+            {
+                iov[v].iov_len -= r;
+                iov[v].iov_base += r;
+                break;
+            }
+            else
+            {
+                r -= iov[v].iov_len;
+                v++;
+            }
+        }
+    }
+    return done;
+}

src/rw_blocking.h

@@ -10,3 +10,4 @@ int read_blocking(int fd, void *read_buf, size_t remaining);
 int write_blocking(int fd, void *write_buf, size_t remaining);
 int readv_blocking(int fd, iovec *iov, int iovcnt);
 int writev_blocking(int fd, iovec *iov, int iovcnt);
+int sendv_blocking(int fd, iovec *iov, int iovcnt, int flags);

tests/run_3osds.sh

@@ -5,6 +5,7 @@
 OSD_SIZE=${OSD_SIZE:-1024}
 PG_COUNT=${PG_COUNT:-1}
 PG_SIZE=${PG_SIZE:-3}
+PG_MINSIZE=${PG_MINSIZE:-2}
 OSD_COUNT=${OSD_COUNT:-3}
 SCHEME=${SCHEME:-ec}
 
@@ -25,9 +26,9 @@ if [ -n "$GLOBAL_CONF" ]; then
 fi
 
 if [ "$SCHEME" = "replicated" ]; then
-    $ETCDCTL put /vitastor/config/pools '{"1":{"name":"testpool","scheme":"replicated","pg_size":'$PG_SIZE',"pg_minsize":'$((PG_SIZE-1))',"pg_count":'$PG_COUNT',"failure_domain":"osd"}}'
+    $ETCDCTL put /vitastor/config/pools '{"1":{"name":"testpool","scheme":"replicated","pg_size":'$PG_SIZE',"pg_minsize":'$PG_MINSIZE',"pg_count":'$PG_COUNT',"failure_domain":"osd"}}'
 else
-    $ETCDCTL put /vitastor/config/pools '{"1":{"name":"testpool","scheme":"xor","pg_size":'$PG_SIZE',"pg_minsize":'$((PG_SIZE-1))',"parity_chunks":1,"pg_count":'$PG_COUNT',"failure_domain":"osd"}}'
+    $ETCDCTL put /vitastor/config/pools '{"1":{"name":"testpool","scheme":"xor","pg_size":'$PG_SIZE',"pg_minsize":'$PG_MINSIZE',"parity_chunks":1,"pg_count":'$PG_COUNT',"failure_domain":"osd"}}'
 fi
 
 sleep 2

tests/test_minsize_1.sh

@@ -0,0 +1,17 @@
+#!/bin/bash -ex
+
+PG_MINSIZE=1
+SCHEME=replicated
+
+. `dirname $0`/run_3osds.sh
+
+kill -INT $OSD1_PID
+kill -INT $OSD2_PID
+
+sleep 5
+
+if ! ($ETCDCTL get /vitastor/pg/state/1/ --prefix --print-value-only | jq -s -e '[ .[] | select(.state == ["active", "degraded"]) ] | length == '$PG_COUNT); then
+    format_error "FAILED: $PG_COUNT PG(s) NOT ACTIVE+DEGRADED"
+fi
+
+format_green OK