Since an NBD server may be long-living, serving clients that
repeatedly connect and disconnect, it can be more efficient to clean
up after each client disconnects, rather than storing a list of
resources to clean up when the server exits. Rewrite the list of
known clients to be double-linked so that we can get O(1) deletion to
keep the list pruned to size as clients exit. This in turn requires
each client to track an opaque pointer of owner information (although
qemu-nbd doesn't need to refer to it).
Signed-off-by: Eric Blake <ebl...@redhat.com>
---
include/block/nbd.h | 4 +++-
blockdev-nbd.c | 27 ++++++++++++++++-----------
nbd/server.c | 15 ++++++++++++---
qemu-nbd.c | 2 +-
4 files changed, 32 insertions(+), 16 deletions(-)
diff --git a/include/block/nbd.h b/include/block/nbd.h
index 4e7bd6342f9..7dce9b9c35b 100644
--- a/include/block/nbd.h
+++ b/include/block/nbd.h
@@ -405,7 +405,9 @@ NBDExport *nbd_export_find(const char *name);
void nbd_client_new(QIOChannelSocket *sioc,
QCryptoTLSCreds *tlscreds,
const char *tlsauthz,
- void (*close_fn)(NBDClient *, bool));
+ void (*close_fn)(NBDClient *, bool),
+ void *owner);
+void *nbd_client_owner(NBDClient *client);
void nbd_client_get(NBDClient *client);
void nbd_client_put(NBDClient *client);
diff --git a/blockdev-nbd.c b/blockdev-nbd.c
index b8f00f402c6..660f89d881e 100644
--- a/blockdev-nbd.c
+++ b/blockdev-nbd.c
@@ -23,7 +23,7 @@
typedef struct NBDConn {
QIOChannelSocket *cioc;
- QSLIST_ENTRY(NBDConn) next;
+ QLIST_ENTRY(NBDConn) next;
} NBDConn;
typedef struct NBDServerData {
@@ -32,10 +32,11 @@ typedef struct NBDServerData {
char *tlsauthz;
uint32_t max_connections;
uint32_t connections;
- QSLIST_HEAD(, NBDConn) conns;
+ QLIST_HEAD(, NBDConn) conns;
} NBDServerData;
static NBDServerData *nbd_server;
+static uint32_t nbd_cookie; /* Generation count of nbd_server */
static int qemu_nbd_connections = -1; /* Non-negative if this is qemu-nbd */
static void nbd_update_server_watch(NBDServerData *s);
@@ -57,10 +58,16 @@ int nbd_server_max_connections(void)
static void nbd_blockdev_client_closed(NBDClient *client, bool ignored)
{
+ NBDConn *conn = nbd_client_owner(client);
+
assert(qemu_in_main_thread() && nbd_server);
+ object_unref(OBJECT(conn->cioc));
+ QLIST_REMOVE(conn, next);
+ g_free(conn);
+
nbd_client_put(client);
- assert(nbd_server->connections > 0);
+ assert(nbd_server && nbd_server->connections > 0);
nbd_server->connections--;
nbd_update_server_watch(nbd_server);
}
@@ -74,12 +81,12 @@ static void nbd_accept(QIONetListener *listener,
QIOChannelSocket *cioc,
nbd_server->connections++;
object_ref(OBJECT(cioc));
conn->cioc = cioc;
- QSLIST_INSERT_HEAD(&nbd_server->conns, conn, next);
+ QLIST_INSERT_HEAD(&nbd_server->conns, conn, next);
nbd_update_server_watch(nbd_server);
qio_channel_set_name(QIO_CHANNEL(cioc), "nbd-server");
nbd_client_new(cioc, nbd_server->tlscreds, nbd_server->tlsauthz,
- nbd_blockdev_client_closed);
+ nbd_blockdev_client_closed, conn);
}
static void nbd_update_server_watch(NBDServerData *s)
@@ -93,6 +100,8 @@ static void nbd_update_server_watch(NBDServerData *s)
static void nbd_server_free(NBDServerData *server)
{
+ NBDConn *conn, *tmp;
+
if (!server) {
return;
}
@@ -103,14 +112,9 @@ static void nbd_server_free(NBDServerData *server)
*/
qio_net_listener_disconnect(server->listener);
object_unref(OBJECT(server->listener));
- while (!QSLIST_EMPTY(&server->conns)) {
- NBDConn *conn = QSLIST_FIRST(&server->conns);
-
+ QLIST_FOREACH_SAFE(conn, &server->conns, next, tmp) {
qio_channel_shutdown(QIO_CHANNEL(conn->cioc),
QIO_CHANNEL_SHUTDOWN_BOTH,
NULL);
- object_unref(OBJECT(conn->cioc));
- QSLIST_REMOVE_HEAD(&server->conns, next);
- g_free(conn);
}
AIO_WAIT_WHILE_UNLOCKED(NULL, server->connections > 0);
@@ -119,6 +123,7 @@ static void nbd_server_free(NBDServerData *server)
object_unref(OBJECT(server->tlscreds));
}
g_free(server->tlsauthz);
+ nbd_cookie++;
g_free(server);
}
diff --git a/nbd/server.c b/nbd/server.c
index 892797bb111..90f48b42a47 100644
--- a/nbd/server.c
+++ b/nbd/server.c
@@ -124,6 +124,7 @@ struct NBDMetaContexts {
struct NBDClient {
int refcount; /* atomic */
void (*close_fn)(NBDClient *client, bool negotiated);
+ void *owner;
QemuMutex lock;
@@ -3205,14 +3206,15 @@ static coroutine_fn void nbd_co_client_start(void
*opaque)
}
/*
- * Create a new client listener using the given channel @sioc.
+ * Create a new client listener using the given channel @sioc and @owner.
* Begin servicing it in a coroutine. When the connection closes, call
- * @close_fn with an indication of whether the client completed negotiation.
+ * @close_fn and an indication of whether the client completed negotiation.
*/
void nbd_client_new(QIOChannelSocket *sioc,
QCryptoTLSCreds *tlscreds,
const char *tlsauthz,
- void (*close_fn)(NBDClient *, bool))
+ void (*close_fn)(NBDClient *, bool),
+ void *owner)
{
NBDClient *client;
Coroutine *co;
@@ -3231,7 +3233,14 @@ void nbd_client_new(QIOChannelSocket *sioc,
client->ioc = QIO_CHANNEL(sioc);
object_ref(OBJECT(client->ioc));
client->close_fn = close_fn;
+ client->owner = owner;
co = qemu_coroutine_create(nbd_co_client_start, client);
qemu_coroutine_enter(co);
}
+
+void *
+nbd_client_owner(NBDClient *client)
+{
+ return client->owner;
+}
diff --git a/qemu-nbd.c b/qemu-nbd.c
index d7b3ccab21c..da6e36a2a34 100644
--- a/qemu-nbd.c
+++ b/qemu-nbd.c
@@ -390,7 +390,7 @@ static void nbd_accept(QIONetListener *listener,
QIOChannelSocket *cioc,
nb_fds++;
nbd_update_server_watch();
- nbd_client_new(cioc, tlscreds, tlsauthz, nbd_client_closed);
+ nbd_client_new(cioc, tlscreds, tlsauthz, nbd_client_closed, NULL);
}
static void nbd_update_server_watch(void)
--
2.45.2
