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nbd: convert to use qio_channel_yield

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In the client, read the reply headers from a coroutine, switching the
read side between the "read header" coroutine and the I/O coroutine that
reads the body of the reply.

In the server, if the server can read more requests it will create a new
"read request" coroutine as soon as a request has been read.  Otherwise,
the new coroutine is created in nbd_request_put.

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Daniel P. Berrange <berrange@redhat.com>
Message-id: 20170213135235.12274-8-pbonzini@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Paolo Bonzini 2017-02-13 14:52:24 +01:00 • committed by Stefan Hajnoczi
parent c4c497d27f
commit ff82911cd3
5 changed files with 85 additions and 143 deletions
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94
nbd/server.c
View file

@ -95,8 +95,6 @@ struct NBDClient {
CoMutex send_lock;
Coroutine *send_coroutine;
bool can_read;
QTAILQ_ENTRY(NBDClient) next;
int nb_requests;
bool closing;
@ -104,9 +102,7 @@ struct NBDClient {
/* That's all folks */
static void nbd_set_handlers(NBDClient *client);
static void nbd_unset_handlers(NBDClient *client);
static void nbd_update_can_read(NBDClient *client);
static void nbd_client_receive_next_request(NBDClient *client);
static gboolean nbd_negotiate_continue(QIOChannel *ioc,
GIOCondition condition,
@ -785,7 +781,7 @@ void nbd_client_put(NBDClient *client)
*/
assert(client->closing);
nbd_unset_handlers(client);
qio_channel_detach_aio_context(client->ioc);
object_unref(OBJECT(client->sioc));
object_unref(OBJECT(client->ioc));
if (client->tlscreds) {
@ -826,7 +822,6 @@ static NBDRequestData *nbd_request_get(NBDClient *client)
assert(client->nb_requests <= MAX_NBD_REQUESTS - 1);
client->nb_requests++;
nbd_update_can_read(client);
req = g_new0(NBDRequestData, 1);
nbd_client_get(client);
@ -844,7 +839,8 @@ static void nbd_request_put(NBDRequestData *req)
g_free(req);
client->nb_requests--;
nbd_update_can_read(client);
nbd_client_receive_next_request(client);
nbd_client_put(client);
}
@ -858,7 +854,13 @@ static void blk_aio_attached(AioContext *ctx, void *opaque)
exp->ctx = ctx;
QTAILQ_FOREACH(client, &exp->clients, next) {
nbd_set_handlers(client);
qio_channel_attach_aio_context(client->ioc, ctx);
if (client->recv_coroutine) {
aio_co_schedule(ctx, client->recv_coroutine);
}
if (client->send_coroutine) {
aio_co_schedule(ctx, client->send_coroutine);
}
}
}
@ -870,7 +872,7 @@ static void blk_aio_detach(void *opaque)
TRACE("Export %s: Detaching clients from AIO context %p\n", exp->name, exp->ctx);
QTAILQ_FOREACH(client, &exp->clients, next) {
nbd_unset_handlers(client);
qio_channel_detach_aio_context(client->ioc);
}
exp->ctx = NULL;
@ -1045,7 +1047,6 @@ static ssize_t nbd_co_send_reply(NBDRequestData *req, NBDReply *reply,
g_assert(qemu_in_coroutine());
qemu_co_mutex_lock(&client->send_lock);
client->send_coroutine = qemu_coroutine_self();
nbd_set_handlers(client);
if (!len) {
rc = nbd_send_reply(client->ioc, reply);
@ -1062,7 +1063,6 @@ static ssize_t nbd_co_send_reply(NBDRequestData *req, NBDReply *reply,
}
client->send_coroutine = NULL;
nbd_set_handlers(client);
qemu_co_mutex_unlock(&client->send_lock);
return rc;
}
@ -1079,9 +1079,7 @@ static ssize_t nbd_co_receive_request(NBDRequestData *req,
ssize_t rc;
g_assert(qemu_in_coroutine());
client->recv_coroutine = qemu_coroutine_self();
nbd_update_can_read(client);
assert(client->recv_coroutine == qemu_coroutine_self());
rc = nbd_receive_request(client->ioc, request);
if (rc < 0) {
if (rc != -EAGAIN) {
@ -1163,23 +1161,25 @@ static ssize_t nbd_co_receive_request(NBDRequestData *req,
out:
client->recv_coroutine = NULL;
nbd_update_can_read(client);
nbd_client_receive_next_request(client);
return rc;
}
static void nbd_trip(void *opaque)
/* Owns a reference to the NBDClient passed as opaque. */
static coroutine_fn void nbd_trip(void *opaque)
{
NBDClient *client = opaque;
NBDExport *exp = client->exp;
NBDRequestData *req;
NBDRequest request;
NBDRequest request = { 0 }; /* GCC thinks it can be used uninitialized */
NBDReply reply;
ssize_t ret;
int flags;
TRACE("Reading request.");
if (client->closing) {
nbd_client_put(client);
return;
}
@ -1338,60 +1338,21 @@ static void nbd_trip(void *opaque)
done:
nbd_request_put(req);
nbd_client_put(client);
return;
out:
nbd_request_put(req);
client_close(client);
nbd_client_put(client);
}
static void nbd_read(void *opaque)
static void nbd_client_receive_next_request(NBDClient *client)
{
NBDClient *client = opaque;
if (client->recv_coroutine) {
qemu_coroutine_enter(client->recv_coroutine);
} else {
qemu_coroutine_enter(qemu_coroutine_create(nbd_trip, client));
}
}
static void nbd_restart_write(void *opaque)
{
NBDClient *client = opaque;
qemu_coroutine_enter(client->send_coroutine);
}
static void nbd_set_handlers(NBDClient *client)
{
if (client->exp && client->exp->ctx) {
aio_set_fd_handler(client->exp->ctx, client->sioc->fd, true,
client->can_read ? nbd_read : NULL,
client->send_coroutine ? nbd_restart_write : NULL,
NULL, client);
}
}
static void nbd_unset_handlers(NBDClient *client)
{
if (client->exp && client->exp->ctx) {
aio_set_fd_handler(client->exp->ctx, client->sioc->fd, true, NULL,
NULL, NULL, NULL);
}
}
static void nbd_update_can_read(NBDClient *client)
{
bool can_read = client->recv_coroutine ||
client->nb_requests < MAX_NBD_REQUESTS;
if (can_read != client->can_read) {
client->can_read = can_read;
nbd_set_handlers(client);
/* There is no need to invoke aio_notify(), since aio_set_fd_handler()
* in nbd_set_handlers() will have taken care of that */
if (!client->recv_coroutine && client->nb_requests < MAX_NBD_REQUESTS) {
nbd_client_get(client);
client->recv_coroutine = qemu_coroutine_create(nbd_trip, client);
aio_co_schedule(client->exp->ctx, client->recv_coroutine);
}
}
@ -1409,11 +1370,13 @@ static coroutine_fn void nbd_co_client_start(void *opaque)
goto out;
}
qemu_co_mutex_init(&client->send_lock);
nbd_set_handlers(client);
if (exp) {
QTAILQ_INSERT_TAIL(&exp->clients, client, next);
}
nbd_client_receive_next_request(client);
out:
g_free(data);
}
@ -1439,7 +1402,6 @@ void nbd_client_new(NBDExport *exp,
object_ref(OBJECT(client->sioc));
client->ioc = QIO_CHANNEL(sioc);
object_ref(OBJECT(client->ioc));
client->can_read = true;
client->close = close_fn;
data->client = client;