nbd: convert to use qio_channel_yield
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:
parent
c4c497d27f
commit
ff82911cd3
@ -33,8 +33,9 @@
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#define HANDLE_TO_INDEX(bs, handle) ((handle) ^ ((uint64_t)(intptr_t)bs))
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#define INDEX_TO_HANDLE(bs, index) ((index) ^ ((uint64_t)(intptr_t)bs))
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static void nbd_recv_coroutines_enter_all(NBDClientSession *s)
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static void nbd_recv_coroutines_enter_all(BlockDriverState *bs)
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{
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NBDClientSession *s = nbd_get_client_session(bs);
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int i;
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for (i = 0; i < MAX_NBD_REQUESTS; i++) {
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@ -42,6 +43,7 @@ static void nbd_recv_coroutines_enter_all(NBDClientSession *s)
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qemu_coroutine_enter(s->recv_coroutine[i]);
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}
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}
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BDRV_POLL_WHILE(bs, s->read_reply_co);
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}
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static void nbd_teardown_connection(BlockDriverState *bs)
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@ -56,7 +58,7 @@ static void nbd_teardown_connection(BlockDriverState *bs)
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qio_channel_shutdown(client->ioc,
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QIO_CHANNEL_SHUTDOWN_BOTH,
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NULL);
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nbd_recv_coroutines_enter_all(client);
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nbd_recv_coroutines_enter_all(bs);
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nbd_client_detach_aio_context(bs);
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object_unref(OBJECT(client->sioc));
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@ -65,54 +67,43 @@ static void nbd_teardown_connection(BlockDriverState *bs)
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client->ioc = NULL;
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}
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static void nbd_reply_ready(void *opaque)
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static coroutine_fn void nbd_read_reply_entry(void *opaque)
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{
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BlockDriverState *bs = opaque;
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NBDClientSession *s = nbd_get_client_session(bs);
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NBDClientSession *s = opaque;
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uint64_t i;
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int ret;
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if (!s->ioc) { /* Already closed */
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return;
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}
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if (s->reply.handle == 0) {
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/* No reply already in flight. Fetch a header. It is possible
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* that another thread has done the same thing in parallel, so
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* the socket is not readable anymore.
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*/
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for (;;) {
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assert(s->reply.handle == 0);
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ret = nbd_receive_reply(s->ioc, &s->reply);
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if (ret == -EAGAIN) {
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return;
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}
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if (ret < 0) {
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s->reply.handle = 0;
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goto fail;
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}
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break;
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}
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/* There's no need for a mutex on the receive side, because the
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* handler acts as a synchronization point and ensures that only
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* one coroutine is called until the reply finishes. */
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* one coroutine is called until the reply finishes.
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*/
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i = HANDLE_TO_INDEX(s, s->reply.handle);
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if (i >= MAX_NBD_REQUESTS) {
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goto fail;
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if (i >= MAX_NBD_REQUESTS || !s->recv_coroutine[i]) {
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break;
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}
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if (s->recv_coroutine[i]) {
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qemu_coroutine_enter(s->recv_coroutine[i]);
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return;
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/* We're woken up by the recv_coroutine itself. Note that there
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* is no race between yielding and reentering read_reply_co. This
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* is because:
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*
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* - if recv_coroutine[i] runs on the same AioContext, it is only
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* entered after we yield
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*
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* - if recv_coroutine[i] runs on a different AioContext, reentering
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* read_reply_co happens through a bottom half, which can only
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* run after we yield.
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*/
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aio_co_wake(s->recv_coroutine[i]);
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qemu_coroutine_yield();
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}
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fail:
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nbd_teardown_connection(bs);
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}
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static void nbd_restart_write(void *opaque)
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{
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BlockDriverState *bs = opaque;
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qemu_coroutine_enter(nbd_get_client_session(bs)->send_coroutine);
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s->read_reply_co = NULL;
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}
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static int nbd_co_send_request(BlockDriverState *bs,
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@ -120,7 +111,6 @@ static int nbd_co_send_request(BlockDriverState *bs,
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QEMUIOVector *qiov)
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{
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NBDClientSession *s = nbd_get_client_session(bs);
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AioContext *aio_context;
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int rc, ret, i;
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qemu_co_mutex_lock(&s->send_mutex);
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@ -141,11 +131,6 @@ static int nbd_co_send_request(BlockDriverState *bs,
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return -EPIPE;
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}
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s->send_coroutine = qemu_coroutine_self();
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aio_context = bdrv_get_aio_context(bs);
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aio_set_fd_handler(aio_context, s->sioc->fd, false,
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nbd_reply_ready, nbd_restart_write, NULL, bs);
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if (qiov) {
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qio_channel_set_cork(s->ioc, true);
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rc = nbd_send_request(s->ioc, request);
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@ -160,9 +145,6 @@ static int nbd_co_send_request(BlockDriverState *bs,
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} else {
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rc = nbd_send_request(s->ioc, request);
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}
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aio_set_fd_handler(aio_context, s->sioc->fd, false,
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nbd_reply_ready, NULL, NULL, bs);
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s->send_coroutine = NULL;
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qemu_co_mutex_unlock(&s->send_mutex);
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return rc;
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}
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@ -174,8 +156,7 @@ static void nbd_co_receive_reply(NBDClientSession *s,
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{
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int ret;
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/* Wait until we're woken up by the read handler. TODO: perhaps
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* peek at the next reply and avoid yielding if it's ours? */
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/* Wait until we're woken up by nbd_read_reply_entry. */
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qemu_coroutine_yield();
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*reply = s->reply;
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if (reply->handle != request->handle ||
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@ -209,13 +190,19 @@ static void nbd_coroutine_start(NBDClientSession *s,
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/* s->recv_coroutine[i] is set as soon as we get the send_lock. */
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}
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static void nbd_coroutine_end(NBDClientSession *s,
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static void nbd_coroutine_end(BlockDriverState *bs,
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NBDRequest *request)
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{
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NBDClientSession *s = nbd_get_client_session(bs);
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int i = HANDLE_TO_INDEX(s, request->handle);
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s->recv_coroutine[i] = NULL;
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if (s->in_flight-- == MAX_NBD_REQUESTS) {
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s->in_flight--;
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qemu_co_queue_next(&s->free_sema);
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/* Kick the read_reply_co to get the next reply. */
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if (s->read_reply_co) {
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aio_co_wake(s->read_reply_co);
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}
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}
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@ -241,7 +228,7 @@ int nbd_client_co_preadv(BlockDriverState *bs, uint64_t offset,
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} else {
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nbd_co_receive_reply(client, &request, &reply, qiov);
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}
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nbd_coroutine_end(client, &request);
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nbd_coroutine_end(bs, &request);
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return -reply.error;
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}
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@ -271,7 +258,7 @@ int nbd_client_co_pwritev(BlockDriverState *bs, uint64_t offset,
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} else {
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nbd_co_receive_reply(client, &request, &reply, NULL);
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}
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nbd_coroutine_end(client, &request);
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nbd_coroutine_end(bs, &request);
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return -reply.error;
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}
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@ -306,7 +293,7 @@ int nbd_client_co_pwrite_zeroes(BlockDriverState *bs, int64_t offset,
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} else {
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nbd_co_receive_reply(client, &request, &reply, NULL);
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}
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nbd_coroutine_end(client, &request);
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nbd_coroutine_end(bs, &request);
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return -reply.error;
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}
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@ -331,7 +318,7 @@ int nbd_client_co_flush(BlockDriverState *bs)
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} else {
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nbd_co_receive_reply(client, &request, &reply, NULL);
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}
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nbd_coroutine_end(client, &request);
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nbd_coroutine_end(bs, &request);
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return -reply.error;
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}
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@ -357,23 +344,23 @@ int nbd_client_co_pdiscard(BlockDriverState *bs, int64_t offset, int count)
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} else {
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nbd_co_receive_reply(client, &request, &reply, NULL);
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}
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nbd_coroutine_end(client, &request);
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nbd_coroutine_end(bs, &request);
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return -reply.error;
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}
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void nbd_client_detach_aio_context(BlockDriverState *bs)
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{
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aio_set_fd_handler(bdrv_get_aio_context(bs),
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nbd_get_client_session(bs)->sioc->fd,
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false, NULL, NULL, NULL, NULL);
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NBDClientSession *client = nbd_get_client_session(bs);
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qio_channel_detach_aio_context(QIO_CHANNEL(client->sioc));
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}
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void nbd_client_attach_aio_context(BlockDriverState *bs,
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AioContext *new_context)
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{
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aio_set_fd_handler(new_context, nbd_get_client_session(bs)->sioc->fd,
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false, nbd_reply_ready, NULL, NULL, bs);
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NBDClientSession *client = nbd_get_client_session(bs);
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qio_channel_attach_aio_context(QIO_CHANNEL(client->sioc), new_context);
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aio_co_schedule(new_context, client->read_reply_co);
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}
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void nbd_client_close(BlockDriverState *bs)
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@ -434,7 +421,7 @@ int nbd_client_init(BlockDriverState *bs,
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/* Now that we're connected, set the socket to be non-blocking and
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* kick the reply mechanism. */
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qio_channel_set_blocking(QIO_CHANNEL(sioc), false, NULL);
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client->read_reply_co = qemu_coroutine_create(nbd_read_reply_entry, client);
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nbd_client_attach_aio_context(bs, bdrv_get_aio_context(bs));
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logout("Established connection with NBD server\n");
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@ -25,7 +25,7 @@ typedef struct NBDClientSession {
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CoMutex send_mutex;
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CoQueue free_sema;
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Coroutine *send_coroutine;
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Coroutine *read_reply_co;
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int in_flight;
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Coroutine *recv_coroutine[MAX_NBD_REQUESTS];
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@ -778,7 +778,7 @@ ssize_t nbd_receive_reply(QIOChannel *ioc, NBDReply *reply)
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ssize_t ret;
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ret = read_sync(ioc, buf, sizeof(buf));
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if (ret < 0) {
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if (ret <= 0) {
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return ret;
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}
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@ -43,14 +43,7 @@ ssize_t nbd_wr_syncv(QIOChannel *ioc,
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}
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if (len == QIO_CHANNEL_ERR_BLOCK) {
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if (qemu_in_coroutine()) {
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/* XXX figure out if we can create a variant on
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* qio_channel_yield() that works with AIO contexts
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* and consider using that in this branch */
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qemu_coroutine_yield();
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} else if (done) {
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/* XXX this is needed by nbd_reply_ready. */
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qio_channel_wait(ioc,
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do_read ? G_IO_IN : G_IO_OUT);
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qio_channel_yield(ioc, do_read ? G_IO_IN : G_IO_OUT);
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} else {
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return -EAGAIN;
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}
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nbd/server.c
94
nbd/server.c
@ -95,8 +95,6 @@ struct NBDClient {
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CoMutex send_lock;
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Coroutine *send_coroutine;
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bool can_read;
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QTAILQ_ENTRY(NBDClient) next;
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int nb_requests;
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bool closing;
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@ -104,9 +102,7 @@ struct NBDClient {
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/* That's all folks */
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static void nbd_set_handlers(NBDClient *client);
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static void nbd_unset_handlers(NBDClient *client);
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static void nbd_update_can_read(NBDClient *client);
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static void nbd_client_receive_next_request(NBDClient *client);
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static gboolean nbd_negotiate_continue(QIOChannel *ioc,
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GIOCondition condition,
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@ -785,7 +781,7 @@ void nbd_client_put(NBDClient *client)
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*/
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assert(client->closing);
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nbd_unset_handlers(client);
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qio_channel_detach_aio_context(client->ioc);
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object_unref(OBJECT(client->sioc));
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object_unref(OBJECT(client->ioc));
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if (client->tlscreds) {
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@ -826,7 +822,6 @@ static NBDRequestData *nbd_request_get(NBDClient *client)
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assert(client->nb_requests <= MAX_NBD_REQUESTS - 1);
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client->nb_requests++;
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nbd_update_can_read(client);
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req = g_new0(NBDRequestData, 1);
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nbd_client_get(client);
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@ -844,7 +839,8 @@ static void nbd_request_put(NBDRequestData *req)
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g_free(req);
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client->nb_requests--;
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nbd_update_can_read(client);
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nbd_client_receive_next_request(client);
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nbd_client_put(client);
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}
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@ -858,7 +854,13 @@ static void blk_aio_attached(AioContext *ctx, void *opaque)
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exp->ctx = ctx;
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QTAILQ_FOREACH(client, &exp->clients, next) {
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nbd_set_handlers(client);
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qio_channel_attach_aio_context(client->ioc, ctx);
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if (client->recv_coroutine) {
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aio_co_schedule(ctx, client->recv_coroutine);
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}
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if (client->send_coroutine) {
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aio_co_schedule(ctx, client->send_coroutine);
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}
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}
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}
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@ -870,7 +872,7 @@ static void blk_aio_detach(void *opaque)
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TRACE("Export %s: Detaching clients from AIO context %p\n", exp->name, exp->ctx);
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QTAILQ_FOREACH(client, &exp->clients, next) {
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nbd_unset_handlers(client);
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qio_channel_detach_aio_context(client->ioc);
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}
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exp->ctx = NULL;
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@ -1045,7 +1047,6 @@ static ssize_t nbd_co_send_reply(NBDRequestData *req, NBDReply *reply,
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g_assert(qemu_in_coroutine());
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qemu_co_mutex_lock(&client->send_lock);
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client->send_coroutine = qemu_coroutine_self();
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nbd_set_handlers(client);
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if (!len) {
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rc = nbd_send_reply(client->ioc, reply);
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@ -1062,7 +1063,6 @@ static ssize_t nbd_co_send_reply(NBDRequestData *req, NBDReply *reply,
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}
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client->send_coroutine = NULL;
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nbd_set_handlers(client);
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qemu_co_mutex_unlock(&client->send_lock);
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return rc;
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}
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@ -1079,9 +1079,7 @@ static ssize_t nbd_co_receive_request(NBDRequestData *req,
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ssize_t rc;
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g_assert(qemu_in_coroutine());
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client->recv_coroutine = qemu_coroutine_self();
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nbd_update_can_read(client);
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assert(client->recv_coroutine == qemu_coroutine_self());
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rc = nbd_receive_request(client->ioc, request);
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if (rc < 0) {
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if (rc != -EAGAIN) {
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@ -1163,23 +1161,25 @@ static ssize_t nbd_co_receive_request(NBDRequestData *req,
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out:
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client->recv_coroutine = NULL;
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nbd_update_can_read(client);
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nbd_client_receive_next_request(client);
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return rc;
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}
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static void nbd_trip(void *opaque)
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/* Owns a reference to the NBDClient passed as opaque. */
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static coroutine_fn void nbd_trip(void *opaque)
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{
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NBDClient *client = opaque;
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NBDExport *exp = client->exp;
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NBDRequestData *req;
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NBDRequest request;
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NBDRequest request = { 0 }; /* GCC thinks it can be used uninitialized */
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NBDReply reply;
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ssize_t ret;
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int flags;
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TRACE("Reading request.");
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if (client->closing) {
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nbd_client_put(client);
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return;
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}
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@ -1338,60 +1338,21 @@ static void nbd_trip(void *opaque)
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done:
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nbd_request_put(req);
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nbd_client_put(client);
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return;
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out:
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nbd_request_put(req);
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client_close(client);
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nbd_client_put(client);
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}
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static void nbd_read(void *opaque)
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static void nbd_client_receive_next_request(NBDClient *client)
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{
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NBDClient *client = opaque;
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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;
|
||||
|
Loading…
Reference in New Issue
Block a user