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qemu/qemu-nbd.c

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/*
* 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 "sysemu/block-backend.h"
#include "block/block_int.h"
#include "block/nbd.h"
#include "qemu/main-loop.h"
#include "qemu/sockets.h"
#include "qemu/error-report.h"
#include "block/snapshot.h"
#include "qapi/util.h"
#include "qapi/qmp/qstring.h"
#include <stdarg.h>
#include <stdio.h>
#include <getopt.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 QEMU_NBD_OPT_CACHE 1
#define QEMU_NBD_OPT_AIO 2
#define QEMU_NBD_OPT_DISCARD 3
#define QEMU_NBD_OPT_DETECT_ZEROES 4
static NBDExport *exp;
static int verbose;
static char *srcpath;
static SocketAddress *saddr;
static int persistent = 0;
static enum { RUNNING, TERMINATE, TERMINATING, TERMINATED } state;
static int shared = 1;
static int nb_fds;
static int server_fd;
static void usage(const char *name)
{
(printf) (
"Usage: %s [OPTIONS] FILE\n"
"QEMU Disk Network Block Device Server\n"
"\n"
" -h, --help display this help and exit\n"
" -V, --version output version information and exit\n"
"\n"
"Connection properties:\n"
" -p, --port=PORT port to listen on (default `%d')\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"
" -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"
"\n"
"Exposing part of the image:\n"
" -o, --offset=OFFSET offset into the image\n"
" -P, --partition=NUM only expose partition NUM\n"
"\n"
#ifdef __linux__
"Kernel NBD client support:\n"
" -c, --connect=DEV connect FILE to the local NBD device DEV\n"
" -d, --disconnect disconnect the specified device\n"
"\n"
#endif
"\n"
"Block device options:\n"
" -f, --format=FORMAT set image format (raw, qcow2, ...)\n"
" -r, --read-only export read-only\n"
" -s, --snapshot use FILE as an external snapshot, create a temporary\n"
" file with backing_file=FILE, redirect the write to\n"
" the temporary one\n"
" -l, --load-snapshot=SNAPSHOT_PARAM\n"
" load an internal snapshot inside FILE and export it\n"
" as an read-only device, SNAPSHOT_PARAM format is\n"
" 'snapshot.id=[ID],snapshot.name=[NAME]', or\n"
" '[ID_OR_NAME]'\n"
" -n, --nocache disable host cache\n"
" --cache=MODE set cache mode (none, writeback, ...)\n"
" --aio=MODE set AIO mode (native or threads)\n"
" --discard=MODE set discard mode (ignore, unmap)\n"
" --detect-zeroes=MODE set detect-zeroes mode (off, on, unmap)\n"
"\n"
"Report bugs to <qemu-devel@nongnu.org>\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 = le32_to_cpup((uint32_t *)(p + 8));
r->nb_sectors_abs = le32_to_cpup((uint32_t *)(p + 12));
}
static int find_partition(BlockBackend *blk, 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 = blk_read(blk, 0, data, 1)) < 0) {
error_report("error while reading: %s", strerror(-ret));
exit(EXIT_FAILURE);
}
if (data[510] != 0x55 || data[511] != 0xaa) {
return -EINVAL;
}
for (i = 0; i < 4; i++) {
read_partition(&data[446 + 16 * i], &mbr[i]);
if (!mbr[i].system || !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 = blk_read(blk, mbr[i].start_sector_abs, data1, 1)) < 0) {
error_report("error while reading: %s", strerror(-ret));
exit(EXIT_FAILURE);
}
for (j = 0; j < 4; j++) {
read_partition(&data1[446 + 16 * j], &ext[j]);
if (!ext[j].system || !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;
}
}
return -ENOENT;
}
static void termsig_handler(int signum)
{
state = TERMINATE;
qemu_notify_event();
}
static void *show_parts(void *arg)
{
char *device = 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 >= 0) {
close(nbd);
}
return NULL;
}
static void *nbd_client_thread(void *arg)
{
char *device = arg;
off_t size;
uint32_t nbdflags;
int fd, sock;
int ret;
pthread_t show_parts_thread;
Error *local_error = NULL;
sock = socket_connect(saddr, &local_error, NULL, NULL);
if (sock < 0) {
error_report_err(local_error);
goto out;
}
ret = nbd_receive_negotiate(sock, NULL, &nbdflags,
&size, &local_error);
if (ret < 0) {
if (local_error) {
error_report_err(local_error);
}
goto out_socket;
}
fd = open(device, O_RDWR);
if (fd < 0) {
/* Linux-only, we can use %m in printf. */
error_report("Failed to open %s: %m", device);
goto out_socket;
}
ret = nbd_init(fd, sock, nbdflags, size);
if (ret < 0) {
goto out_fd;
}
/* update partition table */
pthread_create(&show_parts_thread, NULL, show_parts, device);
if (verbose) {
fprintf(stderr, "NBD device %s is now connected to %s\n",
device, srcpath);
} else {
/* Close stderr so that the qemu-nbd process exits. */
dup2(STDOUT_FILENO, STDERR_FILENO);
}
ret = nbd_client(fd);
if (ret) {
goto out_fd;
}
close(fd);
kill(getpid(), SIGTERM);
return (void *) EXIT_SUCCESS;
out_fd:
close(fd);
out_socket:
closesocket(sock);
out:
kill(getpid(), SIGTERM);
return (void *) EXIT_FAILURE;
}
static int nbd_can_accept(void)
{
return nb_fds < shared;
}
static void nbd_export_closed(NBDExport *exp)
{
assert(state == TERMINATING);
state = TERMINATED;
}
static void nbd_update_server_fd_handler(int fd);
static void nbd_client_closed(NBDClient *client)
{
nb_fds--;
if (nb_fds == 0 && !persistent && state == RUNNING) {
state = TERMINATE;
}
nbd_update_server_fd_handler(server_fd);
nbd_client_put(client);
}
static void nbd_accept(void *opaque)
{
struct sockaddr_in addr;
socklen_t addr_len = sizeof(addr);
int fd = accept(server_fd, (struct sockaddr *)&addr, &addr_len);
if (fd < 0) {
perror("accept");
return;
}
if (state >= TERMINATE) {
close(fd);
return;
}
nb_fds++;
nbd_update_server_fd_handler(server_fd);
nbd_client_new(exp, fd, nbd_client_closed);
}
static void nbd_update_server_fd_handler(int fd)
{
if (nbd_can_accept()) {
qemu_set_fd_handler(fd, nbd_accept, NULL, (void *)(uintptr_t)fd);
} else {
qemu_set_fd_handler(fd, NULL, NULL, NULL);
}
}
static SocketAddress *nbd_build_socket_address(const char *sockpath,
const char *bindto,
const char *port)
{
SocketAddress *saddr;
saddr = g_new0(SocketAddress, 1);
if (sockpath) {
saddr->type = SOCKET_ADDRESS_KIND_UNIX;
saddr->u.q_unix = g_new0(UnixSocketAddress, 1);
saddr->u.q_unix->path = g_strdup(sockpath);
} else {
saddr->type = SOCKET_ADDRESS_KIND_INET;
saddr->u.inet = g_new0(InetSocketAddress, 1);
saddr->u.inet->host = g_strdup(bindto);
if (port) {
saddr->u.inet->port = g_strdup(port);
} else {
saddr->u.inet->port = g_strdup_printf("%d", NBD_DEFAULT_PORT);
}
}
return saddr;
}
int main(int argc, char **argv)
{
BlockBackend *blk;
BlockDriverState *bs;
off_t dev_offset = 0;
uint32_t nbdflags = 0;
bool disconnect = false;
const char *bindto = "0.0.0.0";
const char *port = NULL;
char *sockpath = NULL;
char *device = NULL;
off_t fd_size;
QemuOpts *sn_opts = NULL;
const char *sn_id_or_name = NULL;
const char *sopt = "hVb:o:p:rsnP:c:dvk:e:f:tl:";
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' },
{ "load-snapshot", 1, NULL, 'l' },
{ "nocache", 0, NULL, 'n' },
{ "cache", 1, NULL, QEMU_NBD_OPT_CACHE },
{ "aio", 1, NULL, QEMU_NBD_OPT_AIO },
{ "discard", 1, NULL, QEMU_NBD_OPT_DISCARD },
{ "detect-zeroes", 1, NULL, QEMU_NBD_OPT_DETECT_ZEROES },
{ "shared", 1, NULL, 'e' },
{ "format", 1, NULL, 'f' },
{ "persistent", 0, NULL, 't' },
{ "verbose", 0, NULL, 'v' },
{ NULL, 0, NULL, 0 }
};
int ch;
int opt_ind = 0;
char *end;
int flags = BDRV_O_RDWR;
int partition = -1;
int ret = 0;
int fd;
bool seen_cache = false;
bool seen_discard = false;
bool seen_aio = false;
pthread_t client_thread;
const char *fmt = NULL;
Error *local_err = NULL;
BlockdevDetectZeroesOptions detect_zeroes = BLOCKDEV_DETECT_ZEROES_OPTIONS_OFF;
QDict *options = NULL;
/* 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;
memset(&sa_sigterm, 0, sizeof(sa_sigterm));
sa_sigterm.sa_handler = termsig_handler;
sigaction(SIGTERM, &sa_sigterm, NULL);
qemu_init_exec_dir(argv[0]);
while ((ch = getopt_long(argc, argv, sopt, lopt, &opt_ind)) != -1) {
switch (ch) {
case 's':
flags |= BDRV_O_SNAPSHOT;
break;
case 'n':
optarg = (char *) "none";
/* fallthrough */
case QEMU_NBD_OPT_CACHE:
if (seen_cache) {
error_report("-n and --cache can only be specified once");
exit(EXIT_FAILURE);
}
seen_cache = true;
if (bdrv_parse_cache_flags(optarg, &flags) == -1) {
error_report("Invalid cache mode `%s'", optarg);
exit(EXIT_FAILURE);
}
break;
case QEMU_NBD_OPT_AIO:
if (seen_aio) {
error_report("--aio can only be specified once");
exit(EXIT_FAILURE);
}
seen_aio = true;
if (!strcmp(optarg, "native")) {
flags |= BDRV_O_NATIVE_AIO;
} else if (!strcmp(optarg, "threads")) {
/* this is the default */
} else {
error_report("invalid aio mode `%s'", optarg);
exit(EXIT_FAILURE);
}
break;
case QEMU_NBD_OPT_DISCARD:
if (seen_discard) {
error_report("--discard can only be specified once");
exit(EXIT_FAILURE);
}
seen_discard = true;
if (bdrv_parse_discard_flags(optarg, &flags) == -1) {
error_report("Invalid discard mode `%s'", optarg);
exit(EXIT_FAILURE);
}
break;
case QEMU_NBD_OPT_DETECT_ZEROES:
detect_zeroes =
qapi_enum_parse(BlockdevDetectZeroesOptions_lookup,
optarg,
BLOCKDEV_DETECT_ZEROES_OPTIONS__MAX,
BLOCKDEV_DETECT_ZEROES_OPTIONS_OFF,
&local_err);
if (local_err) {
error_reportf_err(local_err,
"Failed to parse detect_zeroes mode: ");
exit(EXIT_FAILURE);
}
if (detect_zeroes == BLOCKDEV_DETECT_ZEROES_OPTIONS_UNMAP &&
!(flags & BDRV_O_UNMAP)) {
error_report("setting detect-zeroes to unmap is not allowed "
"without setting discard operation to unmap");
exit(EXIT_FAILURE);
}
break;
case 'b':
bindto = optarg;
break;
case 'p':
port = optarg;
break;
case 'o':
dev_offset = strtoll (optarg, &end, 0);
if (*end) {
error_report("Invalid offset `%s'", optarg);
exit(EXIT_FAILURE);
}
if (dev_offset < 0) {
error_report("Offset must be positive `%s'", optarg);
exit(EXIT_FAILURE);
}
break;
case 'l':
if (strstart(optarg, SNAPSHOT_OPT_BASE, NULL)) {
sn_opts = qemu_opts_parse_noisily(&internal_snapshot_opts,
optarg, false);
if (!sn_opts) {
error_report("Failed in parsing snapshot param `%s'",
optarg);
exit(EXIT_FAILURE);
}
} else {
sn_id_or_name = optarg;
}
/* fall through */
case 'r':
nbdflags |= NBD_FLAG_READ_ONLY;
flags &= ~BDRV_O_RDWR;
break;
case 'P':
partition = strtol(optarg, &end, 0);
if (*end) {
error_report("Invalid partition `%s'", optarg);
exit(EXIT_FAILURE);
}
if (partition < 1 || partition > 8) {
error_report("Invalid partition %d", partition);
exit(EXIT_FAILURE);
}
break;
case 'k':
sockpath = optarg;
if (sockpath[0] != '/') {
error_report("socket path must be absolute");
exit(EXIT_FAILURE);
}
break;
case 'd':
disconnect = true;
break;
case 'c':
device = optarg;
break;
case 'e':
shared = strtol(optarg, &end, 0);
if (*end) {
error_report("Invalid shared device number '%s'", optarg);
exit(EXIT_FAILURE);
}
if (shared < 1) {
error_report("Shared device number must be greater than 0");
exit(EXIT_FAILURE);
}
break;
case 'f':
fmt = optarg;
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 '?':
error_report("Try `%s --help' for more information.", argv[0]);
exit(EXIT_FAILURE);
}
}
if ((argc - optind) != 1) {
error_report("Invalid number of arguments");
error_printf("Try `%s --help' for more information.\n", argv[0]);
exit(EXIT_FAILURE);
}
if (disconnect) {
fd = open(argv[optind], O_RDWR);
if (fd < 0) {
error_report("Cannot open %s: %s", argv[optind],
strerror(errno));
exit(EXIT_FAILURE);
}
nbd_disconnect(fd);
close(fd);
printf("%s disconnected\n", argv[optind]);
return 0;
}
if (device && !verbose) {
int stderr_fd[2];
pid_t pid;
int ret;
if (qemu_pipe(stderr_fd) < 0) {
error_report("Error setting up communication pipe: %s",
strerror(errno));
exit(EXIT_FAILURE);
}
/* Now daemonize, but keep a communication channel open to
* print errors and exit with the proper status code.
*/
pid = fork();
if (pid < 0) {
error_report("Failed to fork: %s", strerror(errno));
exit(EXIT_FAILURE);
} else if (pid == 0) {
close(stderr_fd[0]);
ret = qemu_daemon(1, 0);
/* Temporarily redirect stderr to the parent's pipe... */
dup2(stderr_fd[1], STDERR_FILENO);
if (ret < 0) {
error_report("Failed to daemonize: %s", strerror(errno));
exit(EXIT_FAILURE);
}
/* ... close the descriptor we inherited and go on. */
close(stderr_fd[1]);
} else {
bool errors = false;
char *buf;
/* In the parent. Print error messages from the child until
* it closes the pipe.
*/
close(stderr_fd[1]);
buf = g_malloc(1024);
while ((ret = read(stderr_fd[0], buf, 1024)) > 0) {
errors = true;
ret = qemu_write_full(STDERR_FILENO, buf, ret);
if (ret < 0) {
exit(EXIT_FAILURE);
}
}
if (ret < 0) {
error_report("Cannot read from daemon: %s",
strerror(errno));
exit(EXIT_FAILURE);
}
/* Usually the daemon should not print any message.
* Exit with zero status in that case.
*/
exit(errors);
}
}
if (device != NULL && sockpath == NULL) {
sockpath = g_malloc(128);
snprintf(sockpath, 128, SOCKET_PATH, basename(device));
}
saddr = nbd_build_socket_address(sockpath, bindto, port);
if (qemu_init_main_loop(&local_err)) {
error_report_err(local_err);
exit(EXIT_FAILURE);
}
bdrv_init();
atexit(bdrv_close_all);
if (fmt) {
options = qdict_new();
qdict_put(options, "driver", qstring_from_str(fmt));
}
srcpath = argv[optind];
blk = blk_new_open("hda", srcpath, NULL, options, flags, &local_err);
if (!blk) {
error_reportf_err(local_err, "Failed to blk_new_open '%s': ",
argv[optind]);
exit(EXIT_FAILURE);
}
bs = blk_bs(blk);
if (sn_opts) {
ret = bdrv_snapshot_load_tmp(bs,
qemu_opt_get(sn_opts, SNAPSHOT_OPT_ID),
qemu_opt_get(sn_opts, SNAPSHOT_OPT_NAME),
&local_err);
} else if (sn_id_or_name) {
ret = bdrv_snapshot_load_tmp_by_id_or_name(bs, sn_id_or_name,
&local_err);
}
if (ret < 0) {
error_reportf_err(local_err, "Failed to load snapshot: ");
exit(EXIT_FAILURE);
}
bs->detect_zeroes = detect_zeroes;
fd_size = blk_getlength(blk);
if (fd_size < 0) {
error_report("Failed to determine the image length: %s",
strerror(-fd_size));
exit(EXIT_FAILURE);
}
if (partition != -1) {
ret = find_partition(blk, partition, &dev_offset, &fd_size);
if (ret < 0) {
error_report("Could not find partition %d: %s", partition,
strerror(-ret));
exit(EXIT_FAILURE);
}
}
exp = nbd_export_new(blk, dev_offset, fd_size, nbdflags, nbd_export_closed,
&local_err);
if (!exp) {
error_report_err(local_err);
exit(EXIT_FAILURE);
}
fd = socket_listen(saddr, &local_err);
if (fd < 0) {
error_report_err(local_err);
return 1;
}
if (device) {
int ret;
ret = pthread_create(&client_thread, NULL, nbd_client_thread, device);
if (ret != 0) {
error_report("Failed to create client thread: %s", strerror(ret));
exit(EXIT_FAILURE);
}
} else {
/* Shut up GCC warnings. */
memset(&client_thread, 0, sizeof(client_thread));
}
server_fd = fd;
nbd_update_server_fd_handler(fd);
/* now when the initialization is (almost) complete, chdir("/")
* to free any busy filesystems */
if (chdir("/") < 0) {
error_report("Could not chdir to root directory: %s",
strerror(errno));
exit(EXIT_FAILURE);
}
state = RUNNING;
do {
main_loop_wait(false);
if (state == TERMINATE) {
state = TERMINATING;
nbd_export_close(exp);
nbd_export_put(exp);
exp = NULL;
}
} while (state != TERMINATED);
blk_unref(blk);
if (sockpath) {
unlink(sockpath);
}
qemu_opts_del(sn_opts);
if (device) {
void *ret;
pthread_join(client_thread, &ret);
exit(ret != NULL);
} else {
exit(EXIT_SUCCESS);
}
}
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