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nbd.c
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/*
* Copyright (C) 2005 Anthony Liguori <[email protected]>
*
* 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 "block/nbd.h"
#include "sysemu/block-backend.h"
#include "block/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/sockets.h"
#include "qemu/queue.h"
#include "qemu/main-loop.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.
*
* The most up-to-date documentation is available at:
* https://github.com/yoe/nbd/blob/master/doc/proto.txt
*/
#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_REP_MAGIC 0x3e889045565a9LL
#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)
#define NBD_OPT_ABORT (2)
#define NBD_OPT_LIST (3)
/* 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);
BlockBackend *blk;
char *name;
off_t dev_offset;
off_t size;
uint32_t nbdflags;
QTAILQ_HEAD(, NBDClient) clients;
QTAILQ_ENTRY(NBDExport) next;
AioContext *ctx;
};
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;
bool can_read;
QTAILQ_ENTRY(NBDClient) next;
int nb_requests;
bool closing;
};
/* That's all folks */
static void nbd_set_handlers(NBDClient *client);
static void nbd_unset_handlers(NBDClient *client);
static void nbd_update_can_read(NBDClient *client);
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 || err == EWOULDBLOCK))) {
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 drop_sync(int fd, size_t size)
{
ssize_t ret, dropped = size;
uint8_t *buffer = g_malloc(MIN(65536, size));
while (size > 0) {
ret = read_sync(fd, buffer, MIN(65536, size));
if (ret < 0) {
g_free(buffer);
return ret;
}
assert(ret <= size);
size -= ret;
}
g_free(buffer);
return dropped;
}
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;
}
/* 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_send_rep(int csock, uint32_t type, uint32_t opt)
{
uint64_t magic;
uint32_t len;
magic = cpu_to_be64(NBD_REP_MAGIC);
if (write_sync(csock, &magic, sizeof(magic)) != sizeof(magic)) {
LOG("write failed (rep magic)");
return -EINVAL;
}
opt = cpu_to_be32(opt);
if (write_sync(csock, &opt, sizeof(opt)) != sizeof(opt)) {
LOG("write failed (rep opt)");
return -EINVAL;
}
type = cpu_to_be32(type);
if (write_sync(csock, &type, sizeof(type)) != sizeof(type)) {
LOG("write failed (rep type)");
return -EINVAL;
}
len = cpu_to_be32(0);
if (write_sync(csock, &len, sizeof(len)) != sizeof(len)) {
LOG("write failed (rep data length)");
return -EINVAL;
}
return 0;
}
static int nbd_send_rep_list(int csock, NBDExport *exp)
{
uint64_t magic, name_len;
uint32_t opt, type, len;
name_len = strlen(exp->name);
magic = cpu_to_be64(NBD_REP_MAGIC);
if (write_sync(csock, &magic, sizeof(magic)) != sizeof(magic)) {
LOG("write failed (magic)");
return -EINVAL;
}
opt = cpu_to_be32(NBD_OPT_LIST);
if (write_sync(csock, &opt, sizeof(opt)) != sizeof(opt)) {
LOG("write failed (opt)");
return -EINVAL;
}
type = cpu_to_be32(NBD_REP_SERVER);
if (write_sync(csock, &type, sizeof(type)) != sizeof(type)) {
LOG("write failed (reply type)");
return -EINVAL;
}
len = cpu_to_be32(name_len + sizeof(len));
if (write_sync(csock, &len, sizeof(len)) != sizeof(len)) {
LOG("write failed (length)");
return -EINVAL;
}
len = cpu_to_be32(name_len);
if (write_sync(csock, &len, sizeof(len)) != sizeof(len)) {
LOG("write failed (length)");
return -EINVAL;
}
if (write_sync(csock, exp->name, name_len) != name_len) {
LOG("write failed (buffer)");
return -EINVAL;
}
return 0;
}
static int nbd_handle_list(NBDClient *client, uint32_t length)
{
int csock;
NBDExport *exp;
csock = client->sock;
if (length) {
if (drop_sync(csock, length) != length) {
return -EIO;
}
return nbd_send_rep(csock, NBD_REP_ERR_INVALID, NBD_OPT_LIST);
}
/* For each export, send a NBD_REP_SERVER reply. */
QTAILQ_FOREACH(exp, &exports, next) {
if (nbd_send_rep_list(csock, exp)) {
return -EINVAL;
}
}
/* Finish with a NBD_REP_ACK. */
return nbd_send_rep(csock, NBD_REP_ACK, NBD_OPT_LIST);
}
static int nbd_handle_export_name(NBDClient *client, uint32_t length)
{
int rc = -EINVAL, csock = client->sock;
char name[256];
/* Client sends:
[20 .. xx] export name (length bytes)
*/
TRACE("Checking 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);
rc = 0;
fail:
return rc;
}
static int nbd_receive_options(NBDClient *client)
{
int csock = client->sock;
uint32_t flags;
/* Client sends:
[ 0 .. 3] client flags
[ 0 .. 7] NBD_OPTS_MAGIC
[ 8 .. 11] NBD option
[12 .. 15] Data length
... Rest of request
[ 0 .. 7] NBD_OPTS_MAGIC
[ 8 .. 11] Second NBD option
[12 .. 15] Data length
... Rest of request
*/
if (read_sync(csock, &flags, sizeof(flags)) != sizeof(flags)) {
LOG("read failed");
return -EIO;
}
TRACE("Checking client flags");
be32_to_cpus(&flags);
if (flags != 0 && flags != NBD_FLAG_C_FIXED_NEWSTYLE) {
LOG("Bad client flags received");
return -EIO;
}
while (1) {
int ret;
uint32_t tmp, length;
uint64_t magic;
if (read_sync(csock, &magic, sizeof(magic)) != sizeof(magic)) {
LOG("read failed");
return -EINVAL;
}
TRACE("Checking opts magic");
if (magic != be64_to_cpu(NBD_OPTS_MAGIC)) {
LOG("Bad magic received");
return -EINVAL;
}
if (read_sync(csock, &tmp, sizeof(tmp)) != sizeof(tmp)) {
LOG("read failed");
return -EINVAL;
}
if (read_sync(csock, &length, sizeof(length)) != sizeof(length)) {
LOG("read failed");
return -EINVAL;
}
length = be32_to_cpu(length);
TRACE("Checking option");
switch (be32_to_cpu(tmp)) {
case NBD_OPT_LIST:
ret = nbd_handle_list(client, length);
if (ret < 0) {
return ret;
}
break;
case NBD_OPT_ABORT:
return -EINVAL;
case NBD_OPT_EXPORT_NAME:
return nbd_handle_export_name(client, length);
default:
tmp = be32_to_cpu(tmp);
LOG("Unsupported option 0x%x", tmp);
nbd_send_rep(client->sock, NBD_REP_ERR_UNSUP, tmp);
return -EINVAL;
}
}
}
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)
[26 .. 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)
*/
qemu_set_block(csock);
rc = -EINVAL;
TRACE("Beginning negotiation.");
memset(buf, 0, sizeof(buf));
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);
cpu_to_be16w((uint16_t *)(buf + 16), NBD_FLAG_FIXED_NEWSTYLE);
}
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:
qemu_set_nonblock(csock);
return rc;
}
int nbd_receive_negotiate(int csock, const char *name, uint32_t *flags,
off_t *size, Error **errp)
{
char buf[256];
uint64_t magic, s;
uint16_t tmp;
int rc;
TRACE("Receiving negotiation.");
rc = -EINVAL;
if (read_sync(csock, buf, 8) != 8) {
error_setg(errp, "Failed to read data");
goto fail;
}
buf[8] = '\0';
if (strlen(buf) == 0) {
error_setg(errp, "Server connection closed unexpectedly");
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) {
error_setg(errp, "Invalid magic received");
goto fail;
}
if (read_sync(csock, &magic, sizeof(magic)) != sizeof(magic)) {
error_setg(errp, "Failed to read magic");
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) {
if (magic == NBD_CLIENT_MAGIC) {
error_setg(errp, "Server does not support export names");
} else {
error_setg(errp, "Bad magic received");
}
goto fail;
}
if (read_sync(csock, &tmp, sizeof(tmp)) != sizeof(tmp)) {
error_setg(errp, "Failed to read server flags");
goto fail;
}
*flags = be16_to_cpu(tmp) << 16;
/* reserved for future use */
if (write_sync(csock, &reserved, sizeof(reserved)) !=
sizeof(reserved)) {
error_setg(errp, "Failed to read reserved field");
goto fail;
}
/* write the export name */
magic = cpu_to_be64(magic);
if (write_sync(csock, &magic, sizeof(magic)) != sizeof(magic)) {
error_setg(errp, "Failed to send export name magic");
goto fail;
}
opt = cpu_to_be32(NBD_OPT_EXPORT_NAME);
if (write_sync(csock, &opt, sizeof(opt)) != sizeof(opt)) {
error_setg(errp, "Failed to send export name option number");
goto fail;
}
namesize = cpu_to_be32(strlen(name));
if (write_sync(csock, &namesize, sizeof(namesize)) !=
sizeof(namesize)) {
error_setg(errp, "Failed to send export name length");
goto fail;
}
if (write_sync(csock, (char*)name, strlen(name)) != strlen(name)) {
error_setg(errp, "Failed to send export name");
goto fail;
}
} else {
TRACE("Checking magic (cli_magic)");
if (magic != NBD_CLIENT_MAGIC) {
if (magic == NBD_OPTS_MAGIC) {
error_setg(errp, "Server requires an export name");
} else {
error_setg(errp, "Bad magic received");
}
goto fail;
}
}
if (read_sync(csock, &s, sizeof(s)) != sizeof(s)) {
error_setg(errp, "Failed to read export length");
goto fail;
}
*size = be64_to_cpu(s);
TRACE("Size is %" PRIu64, *size);
if (!name) {
if (read_sync(csock, flags, sizeof(*flags)) != sizeof(*flags)) {
error_setg(errp, "Failed to read export flags");
goto fail;
}
*flags = be32_to_cpup(flags);
} else {
if (read_sync(csock, &tmp, sizeof(tmp)) != sizeof(tmp)) {
error_setg(errp, "Failed to read export flags");
goto fail;
}
*flags |= be16_to_cpu(tmp);
}
if (read_sync(csock, &buf, 124) != 124) {
error_setg(errp, "Failed to read reserved block");
goto fail;
}
rc = 0;
fail:
return rc;
}
#ifdef __linux__
int nbd_init(int fd, int csock, uint32_t flags, off_t size)
{
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)BDRV_SECTOR_SIZE);
if (ioctl(fd, NBD_SET_BLKSIZE, (size_t)BDRV_SECTOR_SIZE) < 0) {
int serrno = errno;
LOG("Failed setting NBD block size");
return -serrno;
}
TRACE("Setting size to %zd block(s)", (size_t)(size / BDRV_SECTOR_SIZE));
if (ioctl(fd, NBD_SET_SIZE_BLOCKS, size / (size_t)BDRV_SECTOR_SIZE) < 0) {
int serrno = errno;
LOG("Failed setting size (in blocks)");
return -serrno;
}
if (ioctl(fd, NBD_SET_FLAGS, flags) < 0) {
if (errno == ENOTTY) {
int read_only = (flags & NBD_FLAG_READ_ONLY) != 0;
TRACE("Setting readonly attribute");
if (ioctl(fd, BLKROSET, (unsigned long) &read_only) < 0) {
int serrno = errno;
LOG("Failed setting read-only attribute");
return -serrno;
}
} else {
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)
{
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 client_close.
*/
assert(client->closing);
nbd_unset_handlers(client);
close(client->sock);
client->sock = -1;
if (client->exp) {
QTAILQ_REMOVE(&client->exp->clients, client, next);
nbd_export_put(client->exp);
}
g_free(client);
}
}
static void 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;
assert(client->nb_requests <= MAX_NBD_REQUESTS - 1);
client->nb_requests++;
nbd_update_can_read(client);
req = g_slice_new0(NBDRequest);
nbd_client_get(client);
req->client = client;
return req;
}
static void nbd_request_put(NBDRequest *req)
{
NBDClient *client = req->client;
if (req->data) {
qemu_vfree(req->data);
}
g_slice_free(NBDRequest, req);
client->nb_requests--;
nbd_update_can_read(client);
nbd_client_put(client);
}
static void blk_aio_attached(AioContext *ctx, void *opaque)
{
NBDExport *exp = opaque;
NBDClient *client;
TRACE("Export %s: Attaching clients to AIO context %p\n", exp->name, ctx);
exp->ctx = ctx;
QTAILQ_FOREACH(client, &exp->clients, next) {
nbd_set_handlers(client);
}
}
static void blk_aio_detach(void *opaque)
{
NBDExport *exp = opaque;
NBDClient *client;
TRACE("Export %s: Detaching clients from AIO context %p\n", exp->name, exp->ctx);
QTAILQ_FOREACH(client, &exp->clients, next) {
nbd_unset_handlers(client);
}
exp->ctx = NULL;
}
NBDExport *nbd_export_new(BlockBackend *blk, off_t dev_offset, off_t size,
uint32_t nbdflags, void (*close)(NBDExport *),