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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 "nbd.h"
#include "block.h"
#include "qemu-coroutine.h"
#include <errno.h>
#include <string.h>
#ifndef _WIN32
#include <sys/ioctl.h>
#endif
#if defined(__sun__) || defined(__HAIKU__)
#include <sys/ioccom.h>
#endif
#include <ctype.h>
#include <inttypes.h>
#ifdef __linux__
#include <linux/fs.h>
#endif
#include "qemu_socket.h"
#include "qemu-queue.h"
//#define DEBUG_NBD
#ifdef DEBUG_NBD
#define TRACE(msg, ...) do { \
LOG(msg, ## __VA_ARGS__); \
} while(0)
#else
#define TRACE(msg, ...) \
do { } while (0)
#endif
#define LOG(msg, ...) do { \
fprintf(stderr, "%s:%s():L%d: " msg "\n", \
__FILE__, __FUNCTION__, __LINE__, ## __VA_ARGS__); \
} while(0)
/* This is all part of the "official" NBD API */
#define NBD_REQUEST_SIZE (4 + 4 + 8 + 8 + 4)
#define NBD_REPLY_SIZE (4 + 4 + 8)
#define NBD_REQUEST_MAGIC 0x25609513
#define NBD_REPLY_MAGIC 0x67446698
#define NBD_OPTS_MAGIC 0x49484156454F5054LL
#define NBD_CLIENT_MAGIC 0x0000420281861253LL
#define NBD_SET_SOCK _IO(0xab, 0)
#define NBD_SET_BLKSIZE _IO(0xab, 1)
#define NBD_SET_SIZE _IO(0xab, 2)
#define NBD_DO_IT _IO(0xab, 3)
#define NBD_CLEAR_SOCK _IO(0xab, 4)
#define NBD_CLEAR_QUE _IO(0xab, 5)
#define NBD_PRINT_DEBUG _IO(0xab, 6)
#define NBD_SET_SIZE_BLOCKS _IO(0xab, 7)
#define NBD_DISCONNECT _IO(0xab, 8)
#define NBD_SET_TIMEOUT _IO(0xab, 9)
#define NBD_SET_FLAGS _IO(0xab, 10)
#define NBD_OPT_EXPORT_NAME (1 << 0)
/* Definitions for opaque data types */
typedef struct NBDRequest NBDRequest;
struct NBDRequest {
QSIMPLEQ_ENTRY(NBDRequest) entry;
NBDClient *client;
uint8_t *data;
};
struct NBDExport {
int refcount;
void (*close)(NBDExport *exp);
BlockDriverState *bs;
char *name;
off_t dev_offset;
off_t size;
uint32_t nbdflags;
QTAILQ_HEAD(, NBDClient) clients;
QSIMPLEQ_HEAD(, NBDRequest) requests;
QTAILQ_ENTRY(NBDExport) next;
};
static QTAILQ_HEAD(, NBDExport) exports = QTAILQ_HEAD_INITIALIZER(exports);
struct NBDClient {
int refcount;
void (*close)(NBDClient *client);
NBDExport *exp;
int sock;
Coroutine *recv_coroutine;
CoMutex send_lock;
Coroutine *send_coroutine;
QTAILQ_ENTRY(NBDClient) next;
int nb_requests;
bool closing;
};
/* That's all folks */
ssize_t nbd_wr_sync(int fd, void *buffer, size_t size, bool do_read)
{
size_t offset = 0;
int err;
if (qemu_in_coroutine()) {
if (do_read) {
return qemu_co_recv(fd, buffer, size);
} else {
return qemu_co_send(fd, buffer, size);
}
}
while (offset < size) {
ssize_t len;
if (do_read) {
len = qemu_recv(fd, buffer + offset, size - offset, 0);
} else {
len = send(fd, buffer + offset, size - offset, 0);
}
if (len < 0) {
err = socket_error();
/* recoverable error */
if (err == EINTR || (offset > 0 && err == EAGAIN)) {
continue;
}
/* unrecoverable error */
return -err;
}
/* eof */
if (len == 0) {
break;
}
offset += len;
}
return offset;
}
static ssize_t read_sync(int fd, void *buffer, size_t size)
{
/* Sockets are kept in blocking mode in the negotiation phase. After
* that, a non-readable socket simply means that another thread stole
* our request/reply. Synchronization is done with recv_coroutine, so
* that this is coroutine-safe.
*/
return nbd_wr_sync(fd, buffer, size, true);
}
static ssize_t write_sync(int fd, void *buffer, size_t size)
{
int ret;
do {
/* For writes, we do expect the socket to be writable. */
ret = nbd_wr_sync(fd, buffer, size, false);
} while (ret == -EAGAIN);
return ret;
}
static void combine_addr(char *buf, size_t len, const char* address,
uint16_t port)
{
/* If the address-part contains a colon, it's an IPv6 IP so needs [] */
if (strstr(address, ":")) {
snprintf(buf, len, "[%s]:%u", address, port);
} else {
snprintf(buf, len, "%s:%u", address, port);
}
}
int tcp_socket_outgoing(const char *address, uint16_t port)
{
char address_and_port[128];
combine_addr(address_and_port, 128, address, port);
return tcp_socket_outgoing_spec(address_and_port);
}
int tcp_socket_outgoing_spec(const char *address_and_port)
{
return inet_connect(address_and_port, true, NULL, NULL);
}
int tcp_socket_incoming(const char *address, uint16_t port)
{
char address_and_port[128];
combine_addr(address_and_port, 128, address, port);
return tcp_socket_incoming_spec(address_and_port);
}
int tcp_socket_incoming_spec(const char *address_and_port)
{
char *ostr = NULL;
int olen = 0;
return inet_listen(address_and_port, ostr, olen, SOCK_STREAM, 0, NULL);
}
int unix_socket_incoming(const char *path)
{
char *ostr = NULL;
int olen = 0;
return unix_listen(path, ostr, olen);
}
int unix_socket_outgoing(const char *path)
{
return unix_connect(path);
}
/* Basic flow for negotiation
Server Client
Negotiate
or
Server Client
Negotiate #1
Option
Negotiate #2
----
followed by
Server Client
Request
Response
Request
Response
...
...
Request (type == 2)
*/
static int nbd_receive_options(NBDClient *client)
{
int csock = client->sock;
char name[256];
uint32_t tmp, length;
uint64_t magic;
int rc;
/* Client sends:
[ 0 .. 3] reserved (0)
[ 4 .. 11] NBD_OPTS_MAGIC
[12 .. 15] NBD_OPT_EXPORT_NAME
[16 .. 19] length
[20 .. xx] export name (length bytes)
*/
rc = -EINVAL;
if (read_sync(csock, &tmp, sizeof(tmp)) != sizeof(tmp)) {
LOG("read failed");
goto fail;
}
TRACE("Checking reserved");
if (tmp != 0) {
LOG("Bad reserved received");
goto fail;
}
if (read_sync(csock, &magic, sizeof(magic)) != sizeof(magic)) {
LOG("read failed");
goto fail;
}
TRACE("Checking reserved");
if (magic != be64_to_cpu(NBD_OPTS_MAGIC)) {
LOG("Bad magic received");
goto fail;
}
if (read_sync(csock, &tmp, sizeof(tmp)) != sizeof(tmp)) {
LOG("read failed");
goto fail;
}
TRACE("Checking option");
if (tmp != be32_to_cpu(NBD_OPT_EXPORT_NAME)) {
LOG("Bad option received");
goto fail;
}
if (read_sync(csock, &length, sizeof(length)) != sizeof(length)) {
LOG("read failed");
goto fail;
}
TRACE("Checking length");
length = be32_to_cpu(length);
if (length > 255) {
LOG("Bad length received");
goto fail;
}
if (read_sync(csock, name, length) != length) {
LOG("read failed");
goto fail;
}
name[length] = '\0';
client->exp = nbd_export_find(name);
if (!client->exp) {
LOG("export not found");
goto fail;
}
QTAILQ_INSERT_TAIL(&client->exp->clients, client, next);
nbd_export_get(client->exp);
TRACE("Option negotiation succeeded.");
rc = 0;
fail:
return rc;
}
static int nbd_send_negotiate(NBDClient *client)
{
int csock = client->sock;
char buf[8 + 8 + 8 + 128];
int rc;
const int myflags = (NBD_FLAG_HAS_FLAGS | NBD_FLAG_SEND_TRIM |
NBD_FLAG_SEND_FLUSH | NBD_FLAG_SEND_FUA);
/* Negotiation header without options:
[ 0 .. 7] passwd ("NBDMAGIC")
[ 8 .. 15] magic (NBD_CLIENT_MAGIC)
[16 .. 23] size
[24 .. 25] server flags (0)
[24 .. 27] export flags
[28 .. 151] reserved (0)
Negotiation header with options, part 1:
[ 0 .. 7] passwd ("NBDMAGIC")
[ 8 .. 15] magic (NBD_OPTS_MAGIC)
[16 .. 17] server flags (0)
part 2 (after options are sent):
[18 .. 25] size
[26 .. 27] export flags
[28 .. 151] reserved (0)
*/
socket_set_block(csock);
rc = -EINVAL;
TRACE("Beginning negotiation.");
memcpy(buf, "NBDMAGIC", 8);
if (client->exp) {
assert ((client->exp->nbdflags & ~65535) == 0);
cpu_to_be64w((uint64_t*)(buf + 8), NBD_CLIENT_MAGIC);
cpu_to_be64w((uint64_t*)(buf + 16), client->exp->size);
cpu_to_be16w((uint16_t*)(buf + 26), client->exp->nbdflags | myflags);
} else {
cpu_to_be64w((uint64_t*)(buf + 8), NBD_OPTS_MAGIC);
}
memset(buf + 28, 0, 124);
if (client->exp) {
if (write_sync(csock, buf, sizeof(buf)) != sizeof(buf)) {
LOG("write failed");
goto fail;
}
} else {
if (write_sync(csock, buf, 18) != 18) {
LOG("write failed");
goto fail;
}
rc = nbd_receive_options(client);
if (rc < 0) {
LOG("option negotiation failed");
goto fail;
}
assert ((client->exp->nbdflags & ~65535) == 0);
cpu_to_be64w((uint64_t*)(buf + 18), client->exp->size);
cpu_to_be16w((uint16_t*)(buf + 26), client->exp->nbdflags | myflags);
if (write_sync(csock, buf + 18, sizeof(buf) - 18) != sizeof(buf) - 18) {
LOG("write failed");
goto fail;
}
}
TRACE("Negotiation succeeded.");
rc = 0;
fail:
socket_set_nonblock(csock);
return rc;
}
int nbd_receive_negotiate(int csock, const char *name, uint32_t *flags,
off_t *size, size_t *blocksize)
{
char buf[256];
uint64_t magic, s;
uint16_t tmp;
int rc;
TRACE("Receiving negotiation.");
socket_set_block(csock);
rc = -EINVAL;
if (read_sync(csock, buf, 8) != 8) {
LOG("read failed");
goto fail;
}
buf[8] = '\0';
if (strlen(buf) == 0) {
LOG("server connection closed");
goto fail;
}
TRACE("Magic is %c%c%c%c%c%c%c%c",
qemu_isprint(buf[0]) ? buf[0] : '.',
qemu_isprint(buf[1]) ? buf[1] : '.',
qemu_isprint(buf[2]) ? buf[2] : '.',
qemu_isprint(buf[3]) ? buf[3] : '.',
qemu_isprint(buf[4]) ? buf[4] : '.',
qemu_isprint(buf[5]) ? buf[5] : '.',
qemu_isprint(buf[6]) ? buf[6] : '.',
qemu_isprint(buf[7]) ? buf[7] : '.');
if (memcmp(buf, "NBDMAGIC", 8) != 0) {
LOG("Invalid magic received");
goto fail;
}
if (read_sync(csock, &magic, sizeof(magic)) != sizeof(magic)) {
LOG("read failed");
goto fail;
}
magic = be64_to_cpu(magic);
TRACE("Magic is 0x%" PRIx64, magic);
if (name) {
uint32_t reserved = 0;
uint32_t opt;
uint32_t namesize;
TRACE("Checking magic (opts_magic)");
if (magic != NBD_OPTS_MAGIC) {
LOG("Bad magic received");
goto fail;
}
if (read_sync(csock, &tmp, sizeof(tmp)) != sizeof(tmp)) {
LOG("flags read failed");
goto fail;
}
*flags = be16_to_cpu(tmp) << 16;
/* reserved for future use */
if (write_sync(csock, &reserved, sizeof(reserved)) !=
sizeof(reserved)) {
LOG("write failed (reserved)");
goto fail;
}
/* write the export name */
magic = cpu_to_be64(magic);
if (write_sync(csock, &magic, sizeof(magic)) != sizeof(magic)) {
LOG("write failed (magic)");
goto fail;
}
opt = cpu_to_be32(NBD_OPT_EXPORT_NAME);
if (write_sync(csock, &opt, sizeof(opt)) != sizeof(opt)) {
LOG("write failed (opt)");
goto fail;
}
namesize = cpu_to_be32(strlen(name));
if (write_sync(csock, &namesize, sizeof(namesize)) !=
sizeof(namesize)) {
LOG("write failed (namesize)");
goto fail;
}
if (write_sync(csock, (char*)name, strlen(name)) != strlen(name)) {
LOG("write failed (name)");
goto fail;
}
} else {
TRACE("Checking magic (cli_magic)");
if (magic != NBD_CLIENT_MAGIC) {
LOG("Bad magic received");
goto fail;
}
}
if (read_sync(csock, &s, sizeof(s)) != sizeof(s)) {
LOG("read failed");
goto fail;
}
*size = be64_to_cpu(s);
*blocksize = 1024;
TRACE("Size is %" PRIu64, *size);
if (!name) {
if (read_sync(csock, flags, sizeof(*flags)) != sizeof(*flags)) {
LOG("read failed (flags)");
goto fail;
}
*flags = be32_to_cpup(flags);
} else {
if (read_sync(csock, &tmp, sizeof(tmp)) != sizeof(tmp)) {
LOG("read failed (tmp)");
goto fail;
}
*flags |= be32_to_cpu(tmp);
}
if (read_sync(csock, &buf, 124) != 124) {
LOG("read failed (buf)");
goto fail;
}
rc = 0;
fail:
socket_set_nonblock(csock);
return rc;
}
#ifdef __linux__
int nbd_init(int fd, int csock, uint32_t flags, off_t size, size_t blocksize)
{
TRACE("Setting NBD socket");
if (ioctl(fd, NBD_SET_SOCK, csock) < 0) {
int serrno = errno;
LOG("Failed to set NBD socket");
return -serrno;
}
TRACE("Setting block size to %lu", (unsigned long)blocksize);
if (ioctl(fd, NBD_SET_BLKSIZE, blocksize) < 0) {
int serrno = errno;
LOG("Failed setting NBD block size");
return -serrno;
}
TRACE("Setting size to %zd block(s)", (size_t)(size / blocksize));
if (ioctl(fd, NBD_SET_SIZE_BLOCKS, size / blocksize) < 0) {
int serrno = errno;
LOG("Failed setting size (in blocks)");
return -serrno;
}
if (flags & NBD_FLAG_READ_ONLY) {
int read_only = 1;
TRACE("Setting readonly attribute");
if (ioctl(fd, BLKROSET, (unsigned long) &read_only) < 0) {
int serrno = errno;
LOG("Failed setting read-only attribute");
return -serrno;
}
}
if (ioctl(fd, NBD_SET_FLAGS, flags) < 0
&& errno != ENOTTY) {
int serrno = errno;
LOG("Failed setting flags");
return -serrno;
}
TRACE("Negotiation ended");
return 0;
}
int nbd_disconnect(int fd)
{
ioctl(fd, NBD_CLEAR_QUE);
ioctl(fd, NBD_DISCONNECT);
ioctl(fd, NBD_CLEAR_SOCK);
return 0;
}
int nbd_client(int fd)
{
int ret;
int serrno;
TRACE("Doing NBD loop");
ret = ioctl(fd, NBD_DO_IT);
if (ret < 0 && errno == EPIPE) {
/* NBD_DO_IT normally returns EPIPE when someone has disconnected
* the socket via NBD_DISCONNECT. We do not want to return 1 in
* that case.
*/
ret = 0;
}
serrno = errno;
TRACE("NBD loop returned %d: %s", ret, strerror(serrno));
TRACE("Clearing NBD queue");
ioctl(fd, NBD_CLEAR_QUE);
TRACE("Clearing NBD socket");
ioctl(fd, NBD_CLEAR_SOCK);
errno = serrno;
return ret;
}
#else
int nbd_init(int fd, int csock, uint32_t flags, off_t size, size_t blocksize)
{
return -ENOTSUP;
}
int nbd_disconnect(int fd)
{
return -ENOTSUP;
}
int nbd_client(int fd)
{
return -ENOTSUP;
}
#endif
ssize_t nbd_send_request(int csock, struct nbd_request *request)
{
uint8_t buf[NBD_REQUEST_SIZE];
ssize_t ret;
cpu_to_be32w((uint32_t*)buf, NBD_REQUEST_MAGIC);
cpu_to_be32w((uint32_t*)(buf + 4), request->type);
cpu_to_be64w((uint64_t*)(buf + 8), request->handle);
cpu_to_be64w((uint64_t*)(buf + 16), request->from);
cpu_to_be32w((uint32_t*)(buf + 24), request->len);
TRACE("Sending request to client: "
"{ .from = %" PRIu64", .len = %u, .handle = %" PRIu64", .type=%i}",
request->from, request->len, request->handle, request->type);
ret = write_sync(csock, buf, sizeof(buf));
if (ret < 0) {
return ret;
}
if (ret != sizeof(buf)) {
LOG("writing to socket failed");
return -EINVAL;
}
return 0;
}
static ssize_t nbd_receive_request(int csock, struct nbd_request *request)
{
uint8_t buf[NBD_REQUEST_SIZE];
uint32_t magic;
ssize_t ret;
ret = read_sync(csock, buf, sizeof(buf));
if (ret < 0) {
return ret;
}
if (ret != sizeof(buf)) {
LOG("read failed");
return -EINVAL;
}
/* Request
[ 0 .. 3] magic (NBD_REQUEST_MAGIC)
[ 4 .. 7] type (0 == READ, 1 == WRITE)
[ 8 .. 15] handle
[16 .. 23] from
[24 .. 27] len
*/
magic = be32_to_cpup((uint32_t*)buf);
request->type = be32_to_cpup((uint32_t*)(buf + 4));
request->handle = be64_to_cpup((uint64_t*)(buf + 8));
request->from = be64_to_cpup((uint64_t*)(buf + 16));
request->len = be32_to_cpup((uint32_t*)(buf + 24));
TRACE("Got request: "
"{ magic = 0x%x, .type = %d, from = %" PRIu64" , len = %u }",
magic, request->type, request->from, request->len);
if (magic != NBD_REQUEST_MAGIC) {
LOG("invalid magic (got 0x%x)", magic);
return -EINVAL;
}
return 0;
}
ssize_t nbd_receive_reply(int csock, struct nbd_reply *reply)
{
uint8_t buf[NBD_REPLY_SIZE];
uint32_t magic;
ssize_t ret;
ret = read_sync(csock, buf, sizeof(buf));
if (ret < 0) {
return ret;
}
if (ret != sizeof(buf)) {
LOG("read failed");
return -EINVAL;
}
/* Reply
[ 0 .. 3] magic (NBD_REPLY_MAGIC)
[ 4 .. 7] error (0 == no error)
[ 7 .. 15] handle
*/
magic = be32_to_cpup((uint32_t*)buf);
reply->error = be32_to_cpup((uint32_t*)(buf + 4));
reply->handle = be64_to_cpup((uint64_t*)(buf + 8));
TRACE("Got reply: "
"{ magic = 0x%x, .error = %d, handle = %" PRIu64" }",
magic, reply->error, reply->handle);
if (magic != NBD_REPLY_MAGIC) {
LOG("invalid magic (got 0x%x)", magic);
return -EINVAL;
}
return 0;
}
static ssize_t nbd_send_reply(int csock, struct nbd_reply *reply)
{
uint8_t buf[NBD_REPLY_SIZE];
ssize_t ret;
/* Reply
[ 0 .. 3] magic (NBD_REPLY_MAGIC)
[ 4 .. 7] error (0 == no error)
[ 7 .. 15] handle
*/
cpu_to_be32w((uint32_t*)buf, NBD_REPLY_MAGIC);
cpu_to_be32w((uint32_t*)(buf + 4), reply->error);
cpu_to_be64w((uint64_t*)(buf + 8), reply->handle);
TRACE("Sending response to client");
ret = write_sync(csock, buf, sizeof(buf));
if (ret < 0) {
return ret;
}
if (ret != sizeof(buf)) {
LOG("writing to socket failed");
return -EINVAL;
}
return 0;
}
#define MAX_NBD_REQUESTS 16
void nbd_client_get(NBDClient *client)
{
client->refcount++;
}
void nbd_client_put(NBDClient *client)
{
if (--client->refcount == 0) {
/* The last reference should be dropped by client->close,
* which is called by nbd_client_close.
*/
assert(client->closing);
qemu_set_fd_handler2(client->sock, NULL, NULL, NULL, NULL);
close(client->sock);
client->sock = -1;
if (client->exp) {
QTAILQ_REMOVE(&client->exp->clients, client, next);
nbd_export_put(client->exp);
}
g_free(client);
}
}
void nbd_client_close(NBDClient *client)
{
if (client->closing) {
return;
}
client->closing = true;
/* Force requests to finish. They will drop their own references,
* then we'll close the socket and free the NBDClient.
*/
shutdown(client->sock, 2);
/* Also tell the client, so that they release their reference. */
if (client->close) {
client->close(client);
}
}
static NBDRequest *nbd_request_get(NBDClient *client)
{
NBDRequest *req;
NBDExport *exp = client->exp;
assert(client->nb_requests <= MAX_NBD_REQUESTS - 1);
client->nb_requests++;
if (QSIMPLEQ_EMPTY(&exp->requests)) {
req = g_malloc0(sizeof(NBDRequest));
req->data = qemu_blockalign(exp->bs, NBD_BUFFER_SIZE);
} else {
req = QSIMPLEQ_FIRST(&exp->requests);
QSIMPLEQ_REMOVE_HEAD(&exp->requests, entry);
}
nbd_client_get(client);
req->client = client;
return req;
}
static void nbd_request_put(NBDRequest *req)
{
NBDClient *client = req->client;
QSIMPLEQ_INSERT_HEAD(&client->exp->requests, req, entry);
if (client->nb_requests-- == MAX_NBD_REQUESTS) {
qemu_notify_event();
}
nbd_client_put(client);
}
NBDExport *nbd_export_new(BlockDriverState *bs, off_t dev_offset,
off_t size, uint32_t nbdflags,
void (*close)(NBDExport *))
{
NBDExport *exp = g_malloc0(sizeof(NBDExport));
QSIMPLEQ_INIT(&exp->requests);
exp->refcount = 1;
QTAILQ_INIT(&exp->clients);
exp->bs = bs;
exp->dev_offset = dev_offset;
exp->nbdflags = nbdflags;
exp->size = size == -1 ? bdrv_getlength(bs) : size;
exp->close = close;
return exp;
}
NBDExport *nbd_export_find(const char *name)
{
NBDExport *exp;
QTAILQ_FOREACH(exp, &exports, next) {
if (strcmp(name, exp->name) == 0) {
return exp;
}
}
return NULL;
}
void nbd_export_set_name(NBDExport *exp, const char *name)
{
if (exp->name == name) {
return;
}
nbd_export_get(exp);
if (exp->name != NULL) {
g_free(exp->name);
exp->name = NULL;
QTAILQ_REMOVE(&exports, exp, next);
nbd_export_put(exp);
}
if (name != NULL) {
nbd_export_get(exp);
exp->name = g_strdup(name);
QTAILQ_INSERT_TAIL(&exports, exp, next);
}
nbd_export_put(exp);
}
void nbd_export_close(NBDExport *exp)
{
NBDClient *client, *next;
nbd_export_get(exp);
QTAILQ_FOREACH_SAFE(client, &exp->clients, next, next) {
nbd_client_close(client);
}
nbd_export_set_name(exp, NULL);
nbd_export_put(exp);
}
void nbd_export_get(NBDExport *exp)
{
assert(exp->refcount > 0);
exp->refcount++;
}
void nbd_export_put(NBDExport *exp)
{
assert(exp->refcount > 0);
if (exp->refcount == 1) {
nbd_export_close(exp);
}
if (--exp->refcount == 0) {
assert(exp->name == NULL);
if (exp->close) {
exp->close(exp);
}
while (!QSIMPLEQ_EMPTY(&exp->requests)) {
NBDRequest *first = QSIMPLEQ_FIRST(&exp->requests);
QSIMPLEQ_REMOVE_HEAD(&exp->requests, entry);
qemu_vfree(first->data);
g_free(first);
}
g_free(exp);
}
}
BlockDriverState *nbd_export_get_blockdev(NBDExport *exp)
{
return exp->bs;
}
void nbd_export_close_all(void)
{
NBDExport *exp, *next;
QTAILQ_FOREACH_SAFE(exp, &exports, next, next) {
nbd_export_close(exp);
}
}
static int nbd_can_read(void *opaque);
static void nbd_read(void *opaque);
static void nbd_restart_write(void *opaque);
static ssize_t nbd_co_send_reply(NBDRequest *req, struct nbd_reply *reply,
int len)
{
NBDClient *client = req->client;
int csock = client->sock;
ssize_t rc, ret;
qemu_co_mutex_lock(&client->send_lock);
qemu_set_fd_handler2(csock, nbd_can_read, nbd_read,
nbd_restart_write, client);
client->send_coroutine = qemu_coroutine_self();
if (!len) {
rc = nbd_send_reply(csock, reply);
} else {
socket_set_cork(csock, 1);
rc = nbd_send_reply(csock, reply);
if (rc >= 0) {
ret = qemu_co_send(csock, req->data, len);
if (ret != len) {
rc = -EIO;
}
}
socket_set_cork(csock, 0);
}
client->send_coroutine = NULL;
qemu_set_fd_handler2(csock, nbd_can_read, nbd_read, NULL, client);
qemu_co_mutex_unlock(&client->send_lock);
return rc;
}
static ssize_t nbd_co_receive_request(NBDRequest *req, struct nbd_request *request)
{
NBDClient *client = req->client;
int csock = client->sock;
ssize_t rc;
client->recv_coroutine = qemu_coroutine_self();
rc = nbd_receive_request(csock, request);
if (rc < 0) {
if (rc != -EAGAIN) {
rc = -EIO;
}
goto out;
}
if (request->len > NBD_BUFFER_SIZE) {
LOG("len (%u) is larger than max len (%u)",
request->len, NBD_BUFFER_SIZE);
rc = -EINVAL;
goto out;
}
if ((request->from + request->len) < request->from) {
LOG("integer overflow detected! "
"you're probably being attacked");
rc = -EINVAL;
goto out;
}
TRACE("Decoding type");
if ((request->type & NBD_CMD_MASK_COMMAND) == NBD_CMD_WRITE) {
TRACE("Reading %u byte(s)", request->len);
if (qemu_co_recv(csock, req->data, request->len) != request->len) {
LOG("reading from socket failed");
rc = -EIO;
goto out;
}
}
rc = 0;
out:
client->recv_coroutine = NULL;
return rc;
}
static void nbd_trip(void *opaque)
{
NBDClient *client = opaque;
NBDExport *exp = client->exp;
NBDRequest *req;
struct nbd_request request;
struct nbd_reply reply;
ssize_t ret;
TRACE("Reading request.");
if (client->closing) {
return;
}
req = nbd_request_get(client);
ret = nbd_co_receive_request(req, &request);
if (ret == -EAGAIN) {
goto done;
}
if (ret == -EIO) {
goto out;
}
reply.handle = request.handle;
reply.error = 0;
if (ret < 0) {
reply.error = -ret;
goto error_reply;
}
if ((request.from + request.len) > exp->size) {
LOG("From: %" PRIu64 ", Len: %u, Size: %" PRIu64
", Offset: %" PRIu64 "\n",
request.from, request.len,
(uint64_t)exp->size, (uint64_t)exp->dev_offset);
LOG("requested operation past EOF--bad client?");
goto invalid_request;
}
switch (request.type & NBD_CMD_MASK_COMMAND) {
case NBD_CMD_READ:
TRACE("Request type is READ");
if (request.type & NBD_CMD_FLAG_FUA) {
ret = bdrv_co_flush(exp->bs);
if (ret < 0) {
LOG("flush failed");
reply.error = -ret;
goto error_reply;
}
}
ret = bdrv_read(exp->bs, (request.from + exp->dev_offset) / 512,
req->data, request.len / 512);
if (ret < 0) {
LOG("reading from file failed");
reply.error = -ret;
goto error_reply;
}
TRACE("Read %u byte(s)", request.len);
if (nbd_co_send_reply(req, &reply, request.len) < 0)
goto out;
break;
case NBD_CMD_WRITE:
TRACE("Request type is WRITE");
if (exp->nbdflags & NBD_FLAG_READ_ONLY) {
TRACE("Server is read-only, return error");
reply.error = EROFS;
goto error_reply;
}
TRACE("Writing to device");
ret = bdrv_write(exp->bs, (request.from + exp->dev_offset) / 512,
req->data, request.len / 512);
if (ret < 0) {
LOG("writing to file failed");
reply.error = -ret;
goto error_reply;
}
if (request.type & NBD_CMD_FLAG_FUA) {
ret = bdrv_co_flush(exp->bs);
if (ret < 0) {
LOG("flush failed");
reply.error = -ret;
goto error_reply;
}
}
if (nbd_co_send_reply(req, &reply, 0) < 0) {
goto out;
}
break;
case NBD_CMD_DISC:
TRACE("Request type is DISCONNECT");
errno = 0;
goto out;
case NBD_CMD_FLUSH:
TRACE("Request type is FLUSH");
ret = bdrv_co_flush(exp->bs);
if (ret < 0) {
LOG("flush failed");
reply.error = -ret;
}
if (nbd_co_send_reply(req, &reply, 0) < 0) {
goto out;
}
break;
case NBD_CMD_TRIM:
TRACE("Request type is TRIM");
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_co_send_reply(req, &reply, 0) < 0) {
goto out;
}
break;
default:
LOG("invalid request type (%u) received", request.type);
invalid_request:
reply.error = -EINVAL;
error_reply:
if (nbd_co_send_reply(req, &reply, 0) < 0) {
goto out;
}
break;
}
TRACE("Request/Reply complete");
done:
nbd_request_put(req);
return;
out:
nbd_request_put(req);
nbd_client_close(client);
}
static int nbd_can_read(void *opaque)
{
NBDClient *client = opaque;
return client->recv_coroutine || client->nb_requests < MAX_NBD_REQUESTS;
}
static void nbd_read(void *opaque)
{
NBDClient *client = opaque;
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 *))
{
NBDClient *client;
client = g_malloc0(sizeof(NBDClient));
client->refcount = 1;
client->exp = exp;
client->sock = csock;
if (nbd_send_negotiate(client) < 0) {
g_free(client);
return NULL;
}
client->close = close;
qemu_co_mutex_init(&client->send_lock);
qemu_set_fd_handler2(csock, nbd_can_read, nbd_read, NULL, client);
if (exp) {
QTAILQ_INSERT_TAIL(&exp->clients, client, next);
nbd_export_get(exp);
}
return client;
}
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