Commit de79bfc3 authored by Vladimir Sementsov-Ogievskiy's avatar Vladimir Sementsov-Ogievskiy Committed by Eric Blake
Browse files

nbd/server: simplify reply transmission 



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

Signed-off-by: default avatarVladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20171012095319.136610-8-vsementsov@virtuozzo.com>
[eblake: rebase to tweaks earlier in series]
Signed-off-by: default avatarEric Blake <eblake@redhat.com>
parent 978df1b6

nbd/server.c

+24 −25
Original line number Diff line number Diff line
@@ -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)

{
@@ -1203,35 +1220,17 @@ static int nbd_co_send_simple_reply(NBDClient *client, 
                                    size_t len,

                                    Error **errp)

{

    NBDSimpleReply simple_reply;

    NBDSimpleReply reply;

    int nbd_err = system_errno_to_nbd_errno(error);

    int ret;



    g_assert(qemu_in_coroutine());

    struct iovec iov[] = {

        {.iov_base = &reply, .iov_len = sizeof(reply)},

        {.iov_base = data, .iov_len = len}

    };



    trace_nbd_co_send_simple_reply(handle, nbd_err, len);

    set_be_simple_reply(&simple_reply, nbd_err, handle);



    qemu_co_mutex_lock(&client->send_lock);

    client->send_coroutine = qemu_coroutine_self();

    set_be_simple_reply(&reply, nbd_err, handle);



    if (!len) {

        ret = nbd_write(client->ioc, &simple_reply, sizeof(simple_reply), errp);

    } else {

        qio_channel_set_cork(client->ioc, true);

        ret = nbd_write(client->ioc, &simple_reply, sizeof(simple_reply), errp);

        if (ret == 0) {

            ret = nbd_write(client->ioc, data, len, errp);

            if (ret < 0) {

                ret = -EIO;

            }

        }

        qio_channel_set_cork(client->ioc, false);

    }



    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