mirrors/qemu
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity
a517e88baa
qemu/qemu-nbd.c
Paolo Bonzini a517e88baa qemu-nbd: move client to a thread 
This avoids that qemu-nbd uses both forking and threads, which do
not behave well together.

qemu-nbd is already Unix only, and there is no qemu_thread_join,
so for now use pthreads.

Since the parent and child no longer have separate file descriptors,
we can open the NBD device before daemonizing, instead of checking
with access(2) and restricting the open to the client only.

Reported-by: Pierre Riteau <pierre.riteau@irisa.fr>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2011-11-11 14:02:58 +01:00

535 lines
15 KiB
C
Raw Blame History

/*
* Copyright (C) 2005 Anthony Liguori <anthony@codemonkey.ws>
*
* Network Block Device
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; under version 2 of the License.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, see <http://www.gnu.org/licenses/>.
*/
#include "qemu-common.h"
#include "block_int.h"
#include "nbd.h"
#include <stdarg.h>
#include <stdio.h>
#include <getopt.h>
#include <err.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netinet/tcp.h>
#include <arpa/inet.h>
#include <signal.h>
#include <libgen.h>
#include <pthread.h>
#define SOCKET_PATH "/var/lock/qemu-nbd-%s"
#define NBD_BUFFER_SIZE (1024*1024)
static int sigterm_wfd;
static int verbose;
static char *device;
static char *srcpath;
static char *sockpath;
static void usage(const char *name)
{
printf(
"Usage: %s [OPTIONS] FILE\n"
"QEMU Disk Network Block Device Server\n"
"\n"
" -p, --port=PORT port to listen on (default `%d')\n"
" -o, --offset=OFFSET offset into the image\n"
" -b, --bind=IFACE interface to bind to (default `0.0.0.0')\n"
" -k, --socket=PATH path to the unix socket\n"
" (default '"SOCKET_PATH"')\n"
" -r, --read-only export read-only\n"
" -P, --partition=NUM only expose partition NUM\n"
" -s, --snapshot use snapshot file\n"
" -n, --nocache disable host cache\n"
" -c, --connect=DEV connect FILE to the local NBD device DEV\n"
" -d, --disconnect disconnect the specified device\n"
" -e, --shared=NUM device can be shared by NUM clients (default '1')\n"
" -t, --persistent don't exit on the last connection\n"
" -v, --verbose display extra debugging information\n"
" -h, --help display this help and exit\n"
" -V, --version output version information and exit\n"
"\n"
"Report bugs to <anthony@codemonkey.ws>\n"
, name, NBD_DEFAULT_PORT, "DEVICE");
}
static void version(const char *name)
{
printf(
"%s version 0.0.1\n"
"Written by Anthony Liguori.\n"
"\n"
"Copyright (C) 2006 Anthony Liguori <anthony@codemonkey.ws>.\n"
"This is free software; see the source for copying conditions. There is NO\n"
"warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.\n"
, name);
}
struct partition_record
{
uint8_t bootable;
uint8_t start_head;
uint32_t start_cylinder;
uint8_t start_sector;
uint8_t system;
uint8_t end_head;
uint8_t end_cylinder;
uint8_t end_sector;
uint32_t start_sector_abs;
uint32_t nb_sectors_abs;
};
static void read_partition(uint8_t *p, struct partition_record *r)
{
r->bootable = p[0];
r->start_head = p[1];
r->start_cylinder = p[3] | ((p[2] << 2) & 0x0300);
r->start_sector = p[2] & 0x3f;
r->system = p[4];
r->end_head = p[5];
r->end_cylinder = p[7] | ((p[6] << 2) & 0x300);
r->end_sector = p[6] & 0x3f;
r->start_sector_abs = p[8] | p[9] << 8 | p[10] << 16 | p[11] << 24;
r->nb_sectors_abs = p[12] | p[13] << 8 | p[14] << 16 | p[15] << 24;
}
static int find_partition(BlockDriverState *bs, int partition,
off_t *offset, off_t *size)
{
struct partition_record mbr[4];
uint8_t data[512];
int i;
int ext_partnum = 4;
int ret;
if ((ret = bdrv_read(bs, 0, data, 1)) < 0) {
errno = -ret;
err(EXIT_FAILURE, "error while reading");
}
if (data[510] != 0x55 || data[511] != 0xaa) {
errno = -EINVAL;
return -1;
}
for (i = 0; i < 4; i++) {
read_partition(&data[446 + 16 * i], &mbr[i]);
if (!mbr[i].nb_sectors_abs)
continue;
if (mbr[i].system == 0xF || mbr[i].system == 0x5) {
struct partition_record ext[4];
uint8_t data1[512];
int j;
if ((ret = bdrv_read(bs, mbr[i].start_sector_abs, data1, 1)) < 0) {
errno = -ret;
err(EXIT_FAILURE, "error while reading");
}
for (j = 0; j < 4; j++) {
read_partition(&data1[446 + 16 * j], &ext[j]);
if (!ext[j].nb_sectors_abs)
continue;
if ((ext_partnum + j + 1) == partition) {
*offset = (uint64_t)ext[j].start_sector_abs << 9;
*size = (uint64_t)ext[j].nb_sectors_abs << 9;
return 0;
}
}
ext_partnum += 4;
} else if ((i + 1) == partition) {
*offset = (uint64_t)mbr[i].start_sector_abs << 9;
*size = (uint64_t)mbr[i].nb_sectors_abs << 9;
return 0;
}
}
errno = -ENOENT;
return -1;
}
static void termsig_handler(int signum)
{
static int sigterm_reported;
if (!sigterm_reported) {
sigterm_reported = (write(sigterm_wfd, "", 1) == 1);
}
}
static void *show_parts(void *arg)
{
int nbd;
/* linux just needs an open() to trigger
* the partition table update
* but remember to load the module with max_part != 0 :
* modprobe nbd max_part=63
*/
nbd = open(device, O_RDWR);
if (nbd != -1) {
close(nbd);
}
return NULL;
}
static void *nbd_client_thread(void *arg)
{
int fd = *(int *)arg;
off_t size;
size_t blocksize;
uint32_t nbdflags;
int sock;
int ret;
pthread_t show_parts_thread;
do {
sock = unix_socket_outgoing(sockpath);
if (sock == -1) {
if (errno != ENOENT && errno != ECONNREFUSED) {
goto out;
}
sleep(1); /* wait parent */
}
} while (sock == -1);
ret = nbd_receive_negotiate(sock, NULL, &nbdflags,
&size, &blocksize);
if (ret == -1) {
goto out;
}
ret = nbd_init(fd, sock, nbdflags, size, blocksize);
if (ret == -1) {
goto out;
}
/* update partition table */
pthread_create(&show_parts_thread, NULL, show_parts, NULL);
fprintf(stderr, "NBD device %s is now connected to %s\n",
device, srcpath);
ret = nbd_client(fd);
if (ret) {
goto out;
}
close(fd);
kill(getpid(), SIGTERM);
return (void *) EXIT_SUCCESS;
out:
kill(getpid(), SIGTERM);
return (void *) EXIT_FAILURE;
}
int main(int argc, char **argv)
{
BlockDriverState *bs;
off_t dev_offset = 0;
off_t offset = 0;
uint32_t nbdflags = 0;
bool disconnect = false;
const char *bindto = "0.0.0.0";
int port = NBD_DEFAULT_PORT;
struct sockaddr_in addr;
socklen_t addr_len = sizeof(addr);
off_t fd_size;
const char *sopt = "hVb:o:p:rsnP:c:dvk:e:t";
struct option lopt[] = {
{ "help", 0, NULL, 'h' },
{ "version", 0, NULL, 'V' },
{ "bind", 1, NULL, 'b' },
{ "port", 1, NULL, 'p' },
{ "socket", 1, NULL, 'k' },
{ "offset", 1, NULL, 'o' },
{ "read-only", 0, NULL, 'r' },
{ "partition", 1, NULL, 'P' },
{ "connect", 1, NULL, 'c' },
{ "disconnect", 0, NULL, 'd' },
{ "snapshot", 0, NULL, 's' },
{ "nocache", 0, NULL, 'n' },
{ "shared", 1, NULL, 'e' },
{ "persistent", 0, NULL, 't' },
{ "verbose", 0, NULL, 'v' },
{ NULL, 0, NULL, 0 }
};
int ch;
int opt_ind = 0;
int li;
char *end;
int flags = BDRV_O_RDWR;
int partition = -1;
int ret;
int shared = 1;
uint8_t *data;
fd_set fds;
int *sharing_fds;
int fd;
int i;
int nb_fds = 0;
int max_fd;
int persistent = 0;
pthread_t client_thread;
/* The client thread uses SIGTERM to interrupt the server. A signal
* handler ensures that "qemu-nbd -v -c" exits with a nice status code.
*/
struct sigaction sa_sigterm;
int sigterm_fd[2];
if (qemu_pipe(sigterm_fd) == -1) {
err(EXIT_FAILURE, "Error setting up communication pipe");
}
sigterm_wfd = sigterm_fd[1];
memset(&sa_sigterm, 0, sizeof(sa_sigterm));
sa_sigterm.sa_handler = termsig_handler;
sigaction(SIGTERM, &sa_sigterm, NULL);
while ((ch = getopt_long(argc, argv, sopt, lopt, &opt_ind)) != -1) {
switch (ch) {
case 's':
flags |= BDRV_O_SNAPSHOT;
break;
case 'n':
flags |= BDRV_O_NOCACHE | BDRV_O_CACHE_WB;
break;
case 'b':
bindto = optarg;
break;
case 'p':
li = strtol(optarg, &end, 0);
if (*end) {
errx(EXIT_FAILURE, "Invalid port `%s'", optarg);
}
if (li < 1 || li > 65535) {
errx(EXIT_FAILURE, "Port out of range `%s'", optarg);
}
port = (uint16_t)li;
break;
case 'o':
dev_offset = strtoll (optarg, &end, 0);
if (*end) {
errx(EXIT_FAILURE, "Invalid offset `%s'", optarg);
}
if (dev_offset < 0) {
errx(EXIT_FAILURE, "Offset must be positive `%s'", optarg);
}
break;
case 'r':
nbdflags |= NBD_FLAG_READ_ONLY;
flags &= ~BDRV_O_RDWR;
break;
case 'P':
partition = strtol(optarg, &end, 0);
if (*end)
errx(EXIT_FAILURE, "Invalid partition `%s'", optarg);
if (partition < 1 || partition > 8)
errx(EXIT_FAILURE, "Invalid partition %d", partition);
break;
case 'k':
sockpath = optarg;
if (sockpath[0] != '/')
errx(EXIT_FAILURE, "socket path must be absolute\n");
break;
case 'd':
disconnect = true;
break;
case 'c':
device = optarg;
break;
case 'e':
shared = strtol(optarg, &end, 0);
if (*end) {
errx(EXIT_FAILURE, "Invalid shared device number '%s'", optarg);
}
if (shared < 1) {
errx(EXIT_FAILURE, "Shared device number must be greater than 0\n");
}
break;
case 't':
persistent = 1;
break;
case 'v':
verbose = 1;
break;
case 'V':
version(argv[0]);
exit(0);
break;
case 'h':
usage(argv[0]);
exit(0);
break;
case '?':
errx(EXIT_FAILURE, "Try `%s --help' for more information.",
argv[0]);
}
}
if ((argc - optind) != 1) {
errx(EXIT_FAILURE, "Invalid number of argument.\n"
"Try `%s --help' for more information.",
argv[0]);
}
if (disconnect) {
fd = open(argv[optind], O_RDWR);
if (fd == -1)
err(EXIT_FAILURE, "Cannot open %s", argv[optind]);
nbd_disconnect(fd);
close(fd);
printf("%s disconnected\n", argv[optind]);
return 0;
}
bdrv_init();
bs = bdrv_new("hda");
srcpath = argv[optind];
if ((ret = bdrv_open(bs, srcpath, flags, NULL)) < 0) {
errno = -ret;
err(EXIT_FAILURE, "Failed to bdrv_open '%s'", srcpath);
}
fd_size = bs->total_sectors * 512;
if (partition != -1 &&
find_partition(bs, partition, &dev_offset, &fd_size))
err(EXIT_FAILURE, "Could not find partition %d", partition);
if (device) {
int ret;
/* Open before spawning new threads. In the future, we may
* drop privileges after opening.
*/
fd = open(device, O_RDWR);
if (fd == -1) {
err(EXIT_FAILURE, "Failed to open %s", device);
}
if (!verbose) {
/* detach client and server */
if (qemu_daemon(0, 0) == -1) {
err(EXIT_FAILURE, "Failed to daemonize");
}
}
if (sockpath == NULL) {
sockpath = g_malloc(128);
snprintf(sockpath, 128, SOCKET_PATH, basename(device));
}
ret = pthread_create(&client_thread, NULL, nbd_client_thread, &fd);
if (ret != 0) {
errx(EXIT_FAILURE, "Failed to create client thread: %s",
strerror(ret));
}
} else {
/* Shut up GCC warnings. */
memset(&client_thread, 0, sizeof(client_thread));
}
sharing_fds = g_malloc((shared + 1) * sizeof(int));
if (sockpath) {
sharing_fds[0] = unix_socket_incoming(sockpath);
} else {
sharing_fds[0] = tcp_socket_incoming(bindto, port);
}
if (sharing_fds[0] == -1)
return 1;
max_fd = sharing_fds[0];
nb_fds++;
data = qemu_blockalign(bs, NBD_BUFFER_SIZE);
if (data == NULL) {
errx(EXIT_FAILURE, "Cannot allocate data buffer");
}
do {
FD_ZERO(&fds);
FD_SET(sigterm_fd[0], &fds);
for (i = 0; i < nb_fds; i++)
FD_SET(sharing_fds[i], &fds);
do {
ret = select(max_fd + 1, &fds, NULL, NULL, NULL);
} while (ret == -1 && errno == EINTR);
if (ret == -1 || FD_ISSET(sigterm_fd[0], &fds)) {
break;
}
if (FD_ISSET(sharing_fds[0], &fds))
ret--;
for (i = 1; i < nb_fds && ret; i++) {
if (FD_ISSET(sharing_fds[i], &fds)) {
if (nbd_trip(bs, sharing_fds[i], fd_size, dev_offset,
&offset, nbdflags, data, NBD_BUFFER_SIZE) != 0) {
close(sharing_fds[i]);
nb_fds--;
sharing_fds[i] = sharing_fds[nb_fds];
i--;
}
ret--;
}
}
/* new connection ? */
if (FD_ISSET(sharing_fds[0], &fds)) {
if (nb_fds < shared + 1) {
sharing_fds[nb_fds] = accept(sharing_fds[0],
(struct sockaddr *)&addr,
&addr_len);
if (sharing_fds[nb_fds] != -1 &&
nbd_negotiate(sharing_fds[nb_fds], fd_size, nbdflags) != -1) {
if (sharing_fds[nb_fds] > max_fd)
max_fd = sharing_fds[nb_fds];
nb_fds++;
}
}
}
} while (persistent || nb_fds > 1);
qemu_vfree(data);
close(sharing_fds[0]);
bdrv_close(bs);
g_free(sharing_fds);
if (sockpath) {
unlink(sockpath);
}
if (device) {
void *ret;
pthread_join(client_thread, &ret);
exit(ret != NULL);
} else {
exit(EXIT_SUCCESS);
}
}
Reference in New Issue View Git Blame Copy Permalink