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[Qemu-devel] [PATCH 24/26] qemu-nbd: asynchronous operation
From: |
Paolo Bonzini |
Subject: |
[Qemu-devel] [PATCH 24/26] qemu-nbd: asynchronous operation |
Date: |
Fri, 23 Dec 2011 16:26:28 +0100 |
Using coroutines enable asynchronous operation on both the network and
the block side. Network can be owned by two coroutines at the same time,
one writing and one reading. On the send side, mutual exclusion is
guaranteed by a CoMutex. On the receive side, mutual exclusion is
guaranteed because new coroutines immediately start receiving data,
and no new coroutines are created as long as the previous one is receiving.
Between receive and send, qemu-nbd can have an arbitrary number of
in-flight block transfers. Throttling is implemented by the next
patch.
Signed-off-by: Paolo Bonzini <address@hidden>
---
nbd.c | 74 ++++++++++++++++++++++++++++++++++++++++++++++------------------
1 files changed, 53 insertions(+), 21 deletions(-)
diff --git a/nbd.c b/nbd.c
index ca18c10..6d7d1f8 100644
--- a/nbd.c
+++ b/nbd.c
@@ -20,6 +20,8 @@
#include "block.h"
#include "block_int.h"
+#include "qemu-coroutine.h"
+
#include <errno.h>
#include <string.h>
#ifndef _WIN32
@@ -607,6 +609,11 @@ struct NBDClient {
NBDExport *exp;
int sock;
+
+ Coroutine *recv_coroutine;
+
+ CoMutex send_lock;
+ Coroutine *send_coroutine;
};
static void nbd_client_get(NBDClient *client)
@@ -681,13 +688,20 @@ void nbd_export_close(NBDExport *exp)
g_free(exp);
}
-static int nbd_do_send_reply(NBDRequest *req, struct nbd_reply *reply,
+static void nbd_read(void *opaque);
+static void nbd_restart_write(void *opaque);
+
+static int nbd_co_send_reply(NBDRequest *req, struct nbd_reply *reply,
int len)
{
NBDClient *client = req->client;
int csock = client->sock;
int rc, ret;
+ qemu_co_mutex_lock(&client->send_lock);
+ qemu_set_fd_handler2(csock, NULL, nbd_read, nbd_restart_write, client);
+ client->send_coroutine = qemu_coroutine_self();
+
if (!len) {
rc = nbd_send_reply(csock, reply);
if (rc == -1) {
@@ -697,7 +711,7 @@ static int nbd_do_send_reply(NBDRequest *req, struct
nbd_reply *reply,
socket_set_cork(csock, 1);
rc = nbd_send_reply(csock, reply);
if (rc != -1) {
- ret = write_sync(csock, req->data, len);
+ ret = qemu_co_send(csock, req->data, len);
if (ret != len) {
errno = EIO;
rc = -1;
@@ -708,15 +722,20 @@ static int nbd_do_send_reply(NBDRequest *req, struct
nbd_reply *reply,
}
socket_set_cork(csock, 0);
}
+
+ client->send_coroutine = NULL;
+ qemu_set_fd_handler2(csock, NULL, nbd_read, NULL, client);
+ qemu_co_mutex_unlock(&client->send_lock);
return rc;
}
-static int nbd_do_receive_request(NBDRequest *req, struct nbd_request *request)
+static int nbd_co_receive_request(NBDRequest *req, struct nbd_request *request)
{
NBDClient *client = req->client;
int csock = client->sock;
int rc;
+ client->recv_coroutine = qemu_coroutine_self();
if (nbd_receive_request(csock, request) == -1) {
rc = -EIO;
goto out;
@@ -741,7 +760,7 @@ static int nbd_do_receive_request(NBDRequest *req, struct
nbd_request *request)
if ((request->type & NBD_CMD_MASK_COMMAND) == NBD_CMD_WRITE) {
TRACE("Reading %u byte(s)", request->len);
- if (read_sync(csock, req->data, request->len) != request->len) {
+ if (qemu_co_recv(csock, req->data, request->len) != request->len) {
LOG("reading from socket failed");
rc = -EIO;
goto out;
@@ -750,21 +769,22 @@ static int nbd_do_receive_request(NBDRequest *req, struct
nbd_request *request)
rc = 0;
out:
+ client->recv_coroutine = NULL;
return rc;
}
-static int nbd_trip(NBDClient *client)
+static void nbd_trip(void *opaque)
{
+ NBDClient *client = opaque;
NBDRequest *req = nbd_request_get(client);
NBDExport *exp = client->exp;
struct nbd_request request;
struct nbd_reply reply;
- int rc = -1;
int ret;
TRACE("Reading request.");
- ret = nbd_do_receive_request(req, &request);
+ ret = nbd_co_receive_request(req, &request);
if (ret == -EIO) {
goto out;
}
@@ -799,7 +819,7 @@ static int nbd_trip(NBDClient *client)
}
TRACE("Read %u byte(s)", request.len);
- if (nbd_do_send_reply(req, &reply, request.len) < 0)
+ if (nbd_co_send_reply(req, &reply, request.len) < 0)
goto out;
break;
case NBD_CMD_WRITE:
@@ -822,7 +842,7 @@ static int nbd_trip(NBDClient *client)
}
if (request.type & NBD_CMD_FLAG_FUA) {
- ret = bdrv_flush(exp->bs);
+ ret = bdrv_co_flush(exp->bs);
if (ret < 0) {
LOG("flush failed");
reply.error = -ret;
@@ -830,34 +850,34 @@ static int nbd_trip(NBDClient *client)
}
}
- if (nbd_do_send_reply(req, &reply, 0) < 0)
+ if (nbd_co_send_reply(req, &reply, 0) < 0)
goto out;
break;
case NBD_CMD_DISC:
TRACE("Request type is DISCONNECT");
errno = 0;
- return 1;
+ goto out;
case NBD_CMD_FLUSH:
TRACE("Request type is FLUSH");
- ret = bdrv_flush(exp->bs);
+ ret = bdrv_co_flush(exp->bs);
if (ret < 0) {
LOG("flush failed");
reply.error = -ret;
}
- if (nbd_do_send_reply(req, &reply, 0) < 0)
+ if (nbd_co_send_reply(req, &reply, 0) < 0)
goto out;
break;
case NBD_CMD_TRIM:
TRACE("Request type is TRIM");
- ret = bdrv_discard(exp->bs, (request.from + exp->dev_offset) / 512,
- request.len / 512);
+ ret = bdrv_co_discard(exp->bs, (request.from + exp->dev_offset) / 512,
+ request.len / 512);
if (ret < 0) {
LOG("discard failed");
reply.error = -ret;
}
- if (nbd_do_send_reply(req, &reply, 0) < 0)
+ if (nbd_co_send_reply(req, &reply, 0) < 0)
goto out;
break;
default:
@@ -865,28 +885,39 @@ static int nbd_trip(NBDClient *client)
invalid_request:
reply.error = -EINVAL;
error_reply:
- if (nbd_do_send_reply(req, &reply, 0) == -1)
+ if (nbd_co_send_reply(req, &reply, 0) == -1)
goto out;
break;
}
TRACE("Request/Reply complete");
- rc = 0;
+ nbd_request_put(req);
+ return;
+
out:
nbd_request_put(req);
- return rc;
+ nbd_client_close(client);
}
static void nbd_read(void *opaque)
{
NBDClient *client = opaque;
- if (nbd_trip(client) != 0) {
- nbd_client_close(client);
+ if (client->recv_coroutine) {
+ qemu_coroutine_enter(client->recv_coroutine, NULL);
+ } 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, NULL);
+}
+
NBDClient *nbd_client_new(NBDExport *exp, int csock,
void (*close)(NBDClient *))
{
@@ -899,6 +930,7 @@ NBDClient *nbd_client_new(NBDExport *exp, int csock,
client->exp = exp;
client->sock = csock;
client->close = close;
+ qemu_co_mutex_init(&client->send_lock);
qemu_set_fd_handler2(csock, NULL, nbd_read, NULL, client);
return client;
}
--
1.7.7.1
- [Qemu-devel] [PATCH 15/26] qemu-nbd: introduce nbd_do_send_reply, (continued)
- [Qemu-devel] [PATCH 15/26] qemu-nbd: introduce nbd_do_send_reply, Paolo Bonzini, 2011/12/23
- [Qemu-devel] [PATCH 16/26] qemu-nbd: more robust handling of invalid requests, Paolo Bonzini, 2011/12/23
- [Qemu-devel] [PATCH 19/26] qemu-nbd: introduce NBDRequest, Paolo Bonzini, 2011/12/23
- [Qemu-devel] [PATCH 20/26] link the main loop and its dependencies into the tools, Paolo Bonzini, 2011/12/23
- [Qemu-devel] [PATCH 22/26] qemu-nbd: move client handling to nbd.c, Paolo Bonzini, 2011/12/23
- [Qemu-devel] [PATCH 21/26] qemu-nbd: use common main loop, Paolo Bonzini, 2011/12/23
- [Qemu-devel] [PATCH 25/26] qemu-nbd: throttle requests, Paolo Bonzini, 2011/12/23
- [Qemu-devel] [PATCH 26/26] nbd: add myself as maintainer, Paolo Bonzini, 2011/12/23
- [Qemu-devel] [PATCH 07/26] nbd: add support for NBD_CMD_FLAG_FUA, Paolo Bonzini, 2011/12/23
- [Qemu-devel] [PATCH 09/26] nbd: add support for NBD_CMD_TRIM, Paolo Bonzini, 2011/12/23
- [Qemu-devel] [PATCH 24/26] qemu-nbd: asynchronous operation,
Paolo Bonzini <=
- [Qemu-devel] [PATCH 11/26] qemu-nbd: remove offset argument to nbd_trip, Paolo Bonzini, 2011/12/23
- [Qemu-devel] [PATCH 17/26] qemu-nbd: introduce nbd_do_receive_request, Paolo Bonzini, 2011/12/23
- [Qemu-devel] [PATCH 23/26] qemu-nbd: add client pointer to NBDRequest, Paolo Bonzini, 2011/12/23
- [Qemu-devel] [PATCH 18/26] qemu-nbd: introduce NBDExport, Paolo Bonzini, 2011/12/23
- Re: [Qemu-devel] [PULL 00/26] nbd refactoring, fully asynchronous operation, flushing, fixes, Anthony Liguori, 2011/12/27