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[Qemu-devel] [PATCH v3 07/13] nbd-server: simplify reply transmission


From: Vladimir Sementsov-Ogievskiy
Subject: [Qemu-devel] [PATCH v3 07/13] nbd-server: simplify reply transmission
Date: Thu, 12 Oct 2017 12:53:13 +0300

Send qiov via qio_channel_writev_all instead of calling nbd_write twice
with a cork.

Signed-off-by: Vladimir Sementsov-Ogievskiy <address@hidden>
---
 nbd/server.c | 50 ++++++++++++++++++++++++--------------------------
 1 file changed, 24 insertions(+), 26 deletions(-)

diff --git a/nbd/server.c b/nbd/server.c
index afc127bbd9..c1bbe8d2d1 100644
--- a/nbd/server.c
+++ b/nbd/server.c
@@ -1188,6 +1188,23 @@ void nbd_export_close_all(void)
     }
 }
 
+static int coroutine_fn nbd_co_send_iov(NBDClient *client, struct iovec *iov,
+                                        unsigned niov, Error **errp)
+{
+    int ret;
+
+    g_assert(qemu_in_coroutine());
+    qemu_co_mutex_lock(&client->send_lock);
+    client->send_coroutine = qemu_coroutine_self();
+
+    ret = qio_channel_writev_all(client->ioc, iov, niov, errp) < 0 ? -EIO : 0;
+
+    client->send_coroutine = NULL;
+    qemu_co_mutex_unlock(&client->send_lock);
+
+    return ret;
+}
+
 static inline void set_be_simple_reply(NBDSimpleReply *reply, uint64_t error,
                                        uint64_t handle)
 {
@@ -1203,36 +1220,17 @@ static int nbd_co_send_simple_reply(NBDClient *client,
                                     size_t len,
                                     Error **errp)
 {
-    NBDSimpleReply simple_reply;
-    int ret;
-
-    g_assert(qemu_in_coroutine());
+    NBDSimpleReply reply;
+    struct iovec iov[] = {
+        {.iov_base = &reply, .iov_len = sizeof(reply)},
+        {.iov_base = data, .iov_len = len}
+    };
 
     trace_nbd_co_send_simple_reply(handle, error, len);
 
-    set_be_simple_reply(&simple_reply, system_errno_to_nbd_errno(error),
-                        handle);
-
-    qemu_co_mutex_lock(&client->send_lock);
-    client->send_coroutine = qemu_coroutine_self();
-
-    if (!len) {
-        ret = nbd_write(client->ioc, &simple_reply, sizeof(simple_reply), 
NULL);
-    } else {
-        qio_channel_set_cork(client->ioc, true);
-        ret = nbd_write(client->ioc, &simple_reply, sizeof(simple_reply), 
NULL);
-        if (ret == 0) {
-            ret = nbd_write(client->ioc, data, len, errp);
-            if (ret < 0) {
-                ret = -EIO;
-            }
-        }
-        qio_channel_set_cork(client->ioc, false);
-    }
+    set_be_simple_reply(&reply, system_errno_to_nbd_errno(error), handle);
 
-    client->send_coroutine = NULL;
-    qemu_co_mutex_unlock(&client->send_lock);
-    return ret;
+    return nbd_co_send_iov(client, iov, len ? 2 : 1, errp);
 }
 
 /* nbd_co_receive_request
-- 
2.11.1




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