qemu/block/nbd.c

273 lines
6.9 KiB
C

/*
* QEMU Block driver for NBD
*
* Copyright (C) 2008 Bull S.A.S.
* Author: Laurent Vivier <Laurent.Vivier@bull.net>
*
* Some parts:
* Copyright (C) 2007 Anthony Liguori <anthony@codemonkey.ws>
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include "qemu-common.h"
#include "nbd.h"
#include "module.h"
#include "qemu_socket.h"
#include <sys/types.h>
#include <unistd.h>
#define EN_OPTSTR ":exportname="
/* #define DEBUG_NBD */
#if defined(DEBUG_NBD)
#define logout(fmt, ...) \
fprintf(stderr, "nbd\t%-24s" fmt, __func__, ##__VA_ARGS__)
#else
#define logout(fmt, ...) ((void)0)
#endif
typedef struct BDRVNBDState {
int sock;
off_t size;
size_t blocksize;
char *export_name; /* An NBD server may export several devices */
/* If it begins with '/', this is a UNIX domain socket. Otherwise,
* it's a string of the form <hostname|ip4|\[ip6\]>:port
*/
char *host_spec;
} BDRVNBDState;
static int nbd_config(BDRVNBDState *s, const char *filename, int flags)
{
char *file;
char *export_name;
const char *host_spec;
const char *unixpath;
int err = -EINVAL;
file = qemu_strdup(filename);
export_name = strstr(file, EN_OPTSTR);
if (export_name) {
if (export_name[strlen(EN_OPTSTR)] == 0) {
goto out;
}
export_name[0] = 0; /* truncate 'file' */
export_name += strlen(EN_OPTSTR);
s->export_name = qemu_strdup(export_name);
}
/* extract the host_spec - fail if it's not nbd:... */
if (!strstart(file, "nbd:", &host_spec)) {
goto out;
}
/* are we a UNIX or TCP socket? */
if (strstart(host_spec, "unix:", &unixpath)) {
if (unixpath[0] != '/') { /* We demand an absolute path*/
goto out;
}
s->host_spec = qemu_strdup(unixpath);
} else {
s->host_spec = qemu_strdup(host_spec);
}
err = 0;
out:
qemu_free(file);
if (err != 0) {
qemu_free(s->export_name);
qemu_free(s->host_spec);
}
return err;
}
static int nbd_establish_connection(BlockDriverState *bs)
{
BDRVNBDState *s = bs->opaque;
int sock;
int ret;
off_t size;
size_t blocksize;
uint32_t nbdflags;
if (s->host_spec[0] == '/') {
sock = unix_socket_outgoing(s->host_spec);
} else {
sock = tcp_socket_outgoing_spec(s->host_spec);
}
/* Failed to establish connection */
if (sock == -1) {
logout("Failed to establish connection to NBD server\n");
return -errno;
}
/* NBD handshake */
ret = nbd_receive_negotiate(sock, s->export_name, &nbdflags, &size,
&blocksize);
if (ret == -1) {
logout("Failed to negotiate with the NBD server\n");
closesocket(sock);
return -errno;
}
/* Now that we're connected, set the socket to be non-blocking */
socket_set_nonblock(sock);
s->sock = sock;
s->size = size;
s->blocksize = blocksize;
logout("Established connection with NBD server\n");
return 0;
}
static void nbd_teardown_connection(BlockDriverState *bs)
{
BDRVNBDState *s = bs->opaque;
struct nbd_request request;
request.type = NBD_CMD_DISC;
request.handle = (uint64_t)(intptr_t)bs;
request.from = 0;
request.len = 0;
nbd_send_request(s->sock, &request);
closesocket(s->sock);
}
static int nbd_open(BlockDriverState *bs, const char* filename, int flags)
{
BDRVNBDState *s = bs->opaque;
int result;
/* Pop the config into our state object. Exit if invalid. */
result = nbd_config(s, filename, flags);
if (result != 0) {
return result;
}
/* establish TCP connection, return error if it fails
* TODO: Configurable retry-until-timeout behaviour.
*/
result = nbd_establish_connection(bs);
return result;
}
static int nbd_read(BlockDriverState *bs, int64_t sector_num,
uint8_t *buf, int nb_sectors)
{
BDRVNBDState *s = bs->opaque;
struct nbd_request request;
struct nbd_reply reply;
request.type = NBD_CMD_READ;
request.handle = (uint64_t)(intptr_t)bs;
request.from = sector_num * 512;;
request.len = nb_sectors * 512;
if (nbd_send_request(s->sock, &request) == -1)
return -errno;
if (nbd_receive_reply(s->sock, &reply) == -1)
return -errno;
if (reply.error !=0)
return -reply.error;
if (reply.handle != request.handle)
return -EIO;
if (nbd_wr_sync(s->sock, buf, request.len, 1) != request.len)
return -EIO;
return 0;
}
static int nbd_write(BlockDriverState *bs, int64_t sector_num,
const uint8_t *buf, int nb_sectors)
{
BDRVNBDState *s = bs->opaque;
struct nbd_request request;
struct nbd_reply reply;
request.type = NBD_CMD_WRITE;
request.handle = (uint64_t)(intptr_t)bs;
request.from = sector_num * 512;;
request.len = nb_sectors * 512;
if (nbd_send_request(s->sock, &request) == -1)
return -errno;
if (nbd_wr_sync(s->sock, (uint8_t*)buf, request.len, 0) != request.len)
return -EIO;
if (nbd_receive_reply(s->sock, &reply) == -1)
return -errno;
if (reply.error !=0)
return -reply.error;
if (reply.handle != request.handle)
return -EIO;
return 0;
}
static void nbd_close(BlockDriverState *bs)
{
BDRVNBDState *s = bs->opaque;
qemu_free(s->export_name);
qemu_free(s->host_spec);
nbd_teardown_connection(bs);
}
static int64_t nbd_getlength(BlockDriverState *bs)
{
BDRVNBDState *s = bs->opaque;
return s->size;
}
static BlockDriver bdrv_nbd = {
.format_name = "nbd",
.instance_size = sizeof(BDRVNBDState),
.bdrv_file_open = nbd_open,
.bdrv_read = nbd_read,
.bdrv_write = nbd_write,
.bdrv_close = nbd_close,
.bdrv_getlength = nbd_getlength,
.protocol_name = "nbd",
};
static void bdrv_nbd_init(void)
{
bdrv_register(&bdrv_nbd);
}
block_init(bdrv_nbd_init);