From 6a3b58ac04f70089d2a96a874d7213f63d808093 Mon Sep 17 00:00:00 2001 From: Kevin Wolf Date: Thu, 24 Sep 2020 17:26:54 +0200 Subject: [PATCH 3/8] nbd: Add max-connections to nbd-server-start This is a QMP equivalent of qemu-nbd's --shared option, limiting the maximum number of clients that can attach at the same time. Signed-off-by: Kevin Wolf Reviewed-by: Max Reitz Reviewed-by: Eric Blake Message-Id: <20200924152717.287415-9-kwolf@redhat.com> Acked-by: Stefan Hajnoczi Signed-off-by: Kevin Wolf Signed-off-by: liuxiangdong --- blockdev-nbd.c | 30 ++++++++++++++++++++++++------ include/block/nbd.h | 3 ++- monitor/hmp-cmds.c | 2 +- qapi/block.json | 5 ++++- 4 files changed, 31 insertions(+), 9 deletions(-) diff --git a/blockdev-nbd.c b/blockdev-nbd.c index 0c14f033d2..c73a39fae9 100644 --- a/blockdev-nbd.c +++ b/blockdev-nbd.c @@ -24,18 +24,28 @@ typedef struct NBDServerData { QIONetListener *listener; QCryptoTLSCreds *tlscreds; char *tlsauthz; + uint32_t max_connections; + uint32_t connections; } NBDServerData; static NBDServerData *nbd_server; +static void nbd_update_server_watch(NBDServerData *s); + static void nbd_blockdev_client_closed(NBDClient *client, bool ignored) { nbd_client_put(client); + assert(nbd_server->connections > 0); + nbd_server->connections--; + nbd_update_server_watch(nbd_server); } static void nbd_accept(QIONetListener *listener, QIOChannelSocket *cioc, gpointer opaque) { + nbd_server->connections++; + nbd_update_server_watch(nbd_server); + qio_channel_set_name(QIO_CHANNEL(cioc), "nbd-server"); /* TODO - expose handshake timeout as QMP option */ nbd_client_new(cioc, NBD_DEFAULT_HANDSHAKE_MAX_SECS, @@ -43,6 +53,14 @@ static void nbd_accept(QIONetListener *listener, QIOChannelSocket *cioc, nbd_blockdev_client_closed, NULL); } +static void nbd_update_server_watch(NBDServerData *s) +{ + if (!s->max_connections || s->connections < s->max_connections) { + qio_net_listener_set_client_func(s->listener, nbd_accept, NULL, NULL); + } else { + qio_net_listener_set_client_func(s->listener, NULL, NULL, NULL); + } +} static void nbd_server_free(NBDServerData *server) { @@ -91,7 +109,8 @@ static QCryptoTLSCreds *nbd_get_tls_creds(const char *id, Error **errp) void nbd_server_start(SocketAddress *addr, const char *tls_creds, - const char *tls_authz, Error **errp) + const char *tls_authz, uint32_t max_connections, + Error **errp) { if (nbd_server) { error_setg(errp, "NBD server already running"); @@ -99,6 +118,7 @@ void nbd_server_start(SocketAddress *addr, const char *tls_creds, } nbd_server = g_new0(NBDServerData, 1); + nbd_server->max_connections = max_connections; nbd_server->listener = qio_net_listener_new(); qio_net_listener_set_name(nbd_server->listener, @@ -123,10 +143,7 @@ void nbd_server_start(SocketAddress *addr, const char *tls_creds, nbd_server->tlsauthz = g_strdup(tls_authz); - qio_net_listener_set_client_func(nbd_server->listener, - nbd_accept, - NULL, - NULL); + nbd_update_server_watch(nbd_server); return; @@ -138,11 +155,12 @@ void nbd_server_start(SocketAddress *addr, const char *tls_creds, void qmp_nbd_server_start(SocketAddressLegacy *addr, bool has_tls_creds, const char *tls_creds, bool has_tls_authz, const char *tls_authz, + bool has_max_connections, uint32_t max_connections, Error **errp) { SocketAddress *addr_flat = socket_address_flatten(addr); - nbd_server_start(addr_flat, tls_creds, tls_authz, errp); + nbd_server_start(addr_flat, tls_creds, tls_authz, max_connections, errp); qapi_free_SocketAddress(addr_flat); } diff --git a/include/block/nbd.h b/include/block/nbd.h index 68667c31c8..d6fd188546 100644 --- a/include/block/nbd.h +++ b/include/block/nbd.h @@ -355,7 +355,8 @@ void nbd_client_get(NBDClient *client); void nbd_client_put(NBDClient *client); void nbd_server_start(SocketAddress *addr, const char *tls_creds, - const char *tls_authz, Error **errp); + const char *tls_authz, uint32_t max_connections, + Error **errp); /* nbd_read * Reads @size bytes from @ioc. Returns 0 on success. diff --git a/monitor/hmp-cmds.c b/monitor/hmp-cmds.c index 5ca3ebe942..bf468fe8eb 100644 --- a/monitor/hmp-cmds.c +++ b/monitor/hmp-cmds.c @@ -2365,7 +2365,7 @@ void hmp_nbd_server_start(Monitor *mon, const QDict *qdict) goto exit; } - nbd_server_start(addr, NULL, NULL, &local_err); + nbd_server_start(addr, NULL, NULL, 0, &local_err); qapi_free_SocketAddress(addr); if (local_err != NULL) { goto exit; diff --git a/qapi/block.json b/qapi/block.json index 145c268bb6..e25a2a75a4 100644 --- a/qapi/block.json +++ b/qapi/block.json @@ -230,6 +230,8 @@ # is only resolved at time of use, so can be deleted and # recreated on the fly while the NBD server is active. # If missing, it will default to denying access (since 4.0). +# @max-connections: The maximum number of connections to allow at the same +# time, 0 for unlimited. (since 5.2; default: 0) # # Returns: error if the server is already running. # @@ -238,7 +240,8 @@ { 'command': 'nbd-server-start', 'data': { 'addr': 'SocketAddressLegacy', '*tls-creds': 'str', - '*tls-authz': 'str'} } + '*tls-authz': 'str', + '*max-connections': 'uint32' } } ## # @nbd-server-add: -- 2.45.1.windows.1