Commit 4a41a2d6 authored by Stefan Hajnoczi's avatar Stefan Hajnoczi
Browse files

nbd: close socket if connection breaks 



nbd_receive_reply() is called by the event loop whenever data is
available or the socket has been closed by the remote side.

This patch closes the socket when an error occurs to prevent the
nbd_receive_reply() handler from being called indefinitely after the
connection has failed.

Note that we were already correctly returning EIO for pending requests
but leaving the nbd_receive_reply() handler registered resulted in high
CPU consumption and a flood of error messages.

Reuse nbd_teardown_connection() to close the socket.

Reported-by: default avatarZhifeng Cai <bluewindow@h3c.com>
Signed-off-by: default avatarStefan Hajnoczi <stefanha@redhat.com>
parent 62e466e8

block/nbd-client.c

+18 −15
Original line number Diff line number Diff line
@@ -43,6 +43,17 @@ static void nbd_recv_coroutines_enter_all(NbdClientSession *s) 
    }

}



static void nbd_teardown_connection(NbdClientSession *client)

{

    /* finish any pending coroutines */

    shutdown(client->sock, 2);

    nbd_recv_coroutines_enter_all(client);



    qemu_aio_set_fd_handler(client->sock, NULL, NULL, NULL);

    closesocket(client->sock);

    client->sock = -1;

}



static void nbd_reply_ready(void *opaque)

{

    NbdClientSession *s = opaque;
@@ -78,7 +89,7 @@ static void nbd_reply_ready(void *opaque) 
    }



fail:

    nbd_recv_coroutines_enter_all(s);

    nbd_teardown_connection(s);

}



static void nbd_restart_write(void *opaque)
@@ -324,7 +335,7 @@ int nbd_client_session_co_discard(NbdClientSession *client, int64_t sector_num, 


}



static void nbd_teardown_connection(NbdClientSession *client)

void nbd_client_session_close(NbdClientSession *client)

{

    struct nbd_request request = {

        .type = NBD_CMD_DISC,
@@ -332,22 +343,14 @@ static void nbd_teardown_connection(NbdClientSession *client) 
        .len = 0

    };



    nbd_send_request(client->sock, &request);



    /* finish any pending coroutines */

    shutdown(client->sock, 2);

    nbd_recv_coroutines_enter_all(client);



    qemu_aio_set_fd_handler(client->sock, NULL, NULL, NULL);

    closesocket(client->sock);

    client->sock = -1;

}



void nbd_client_session_close(NbdClientSession *client)

{

    if (!client->bs) {

        return;

    }

    if (client->sock == -1) {

        return;

    }



    nbd_send_request(client->sock, &request);



    nbd_teardown_connection(client);

    client->bs = NULL;