nbd: Split nbd.c

We have NBD server code and client code, all mixed in a file. Now split
them into separate files under nbd/, and update MAINTAINERS.

filter_nbd for iotest 083 is updated to keep the log filtered out.

Signed-off-by: Fam Zheng <famz@redhat.com>
Message-Id: <1452760863-25350-3-git-send-email-famz@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 0 insertions, 1499 deletions

diff --git a/nbd.c b/nbd.c
deleted file mode 100644
index f8d0221da1..0000000000
--- a/nbd.c
+++ /dev/null
@@ -1,1499 +0,0 @@
-/*
- *  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 "block/nbd.h"
-#include "sysemu/block-backend.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/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)
-
-/* NBD errors are based on errno numbers, so there is a 1:1 mapping,
- * but only a limited set of errno values is specified in the protocol.
- * Everything else is squashed to EINVAL.
- */
-#define NBD_SUCCESS    0
-#define NBD_EPERM      1
-#define NBD_EIO        5
-#define NBD_ENOMEM     12
-#define NBD_EINVAL     22
-#define NBD_ENOSPC     28
-
-static int system_errno_to_nbd_errno(int err)
-{
-    switch (err) {
-    case 0:
-        return NBD_SUCCESS;
-    case EPERM:
-        return NBD_EPERM;
-    case EIO:
-        return NBD_EIO;
-    case ENOMEM:
-        return NBD_ENOMEM;
-#ifdef EDQUOT
-    case EDQUOT:
-#endif
-    case EFBIG:
-    case ENOSPC:
-        return NBD_ENOSPC;
-    case EINVAL:
-    default:
-        return NBD_EINVAL;
-    }
-}
-
-static int nbd_errno_to_system_errno(int err)
-{
-    switch (err) {
-    case NBD_SUCCESS:
-        return 0;
-    case NBD_EPERM:
-        return EPERM;
-    case NBD_EIO:
-        return EIO;
-    case NBD_ENOMEM:
-        return ENOMEM;
-    case NBD_ENOSPC:
-        return ENOSPC;
-    case NBD_EINVAL:
-    default:
-        return EINVAL;
-    }
-}
-
-/* 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_t)(size / 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));
-
-    reply->error = nbd_errno_to_system_errno(reply->error);
-
-    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->error = system_errno_to_nbd_errno(reply->error);
-
-    /* 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_new0(NBDRequest, 1);
-    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_free(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 *),
-                          Error **errp)
-{
-    NBDExport *exp = g_malloc0(sizeof(NBDExport));
-    exp->refcount = 1;
-    QTAILQ_INIT(&exp->clients);
-    exp->blk = blk;
-    exp->dev_offset = dev_offset;
-    exp->nbdflags = nbdflags;
-    exp->size = size < 0 ? blk_getlength(blk) : size;
-    if (exp->size < 0) {
-        error_setg_errno(errp, -exp->size,
-                         "Failed to determine the NBD export's length");
-        goto fail;
-    }
-    exp->size -= exp->size % BDRV_SECTOR_SIZE;
-
-    exp->close = close;
-    exp->ctx = blk_get_aio_context(blk);
-    blk_ref(blk);
-    blk_add_aio_context_notifier(blk, blk_aio_attached, blk_aio_detach, exp);
-    /*
-     * NBD exports are used for non-shared storage migration.  Make sure
-     * that BDRV_O_INCOMING is cleared and the image is ready for write
-     * access since the export could be available before migration handover.
-     */
-    blk_invalidate_cache(blk, NULL);
-    return exp;
-
-fail:
-    g_free(exp);
-    return NULL;
-}
-
-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) {
-        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);
-        }
-
-        if (exp->blk) {
-            blk_remove_aio_context_notifier(exp->blk, blk_aio_attached,
-                                            blk_aio_detach, exp);
-            blk_unref(exp->blk);
-            exp->blk = NULL;
-        }
-
-        g_free(exp);
-    }
-}
-
-BlockBackend *nbd_export_get_blockdev(NBDExport *exp)
-{
-    return exp->blk;
-}
-
-void nbd_export_close_all(void)
-{
-    NBDExport *exp, *next;
-
-    QTAILQ_FOREACH_SAFE(exp, &exports, next, next) {
-        nbd_export_close(exp);
-    }
-}
-
-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);
-    client->send_coroutine = qemu_coroutine_self();
-    nbd_set_handlers(client);
-
-    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;
-    nbd_set_handlers(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;
-    uint32_t command;
-    ssize_t rc;
-
-    client->recv_coroutine = qemu_coroutine_self();
-    nbd_update_can_read(client);
-
-    rc = nbd_receive_request(csock, request);
-    if (rc < 0) {
-        if (rc != -EAGAIN) {
-            rc = -EIO;
-        }
-        goto out;
-    }
-
-    if (request->len > NBD_MAX_BUFFER_SIZE) {
-        LOG("len (%u) is larger than max len (%u)",
-            request->len, NBD_MAX_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");
-
-    command = request->type & NBD_CMD_MASK_COMMAND;
-    if (command == NBD_CMD_READ || command == NBD_CMD_WRITE) {
-        req->data = blk_blockalign(client->exp->blk, request->len);
-    }
-    if (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;
-    nbd_update_can_read(client);
-
-    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;
-    uint32_t command;
-
-    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;
-    }
-    command = request.type & NBD_CMD_MASK_COMMAND;
-    if (command != NBD_CMD_DISC && (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;
-    }
-
-    if (client->closing) {
-        /*
-         * The client may be closed when we are blocked in
-         * nbd_co_receive_request()
-         */
-        goto done;
-    }
-
-    switch (command) {
-    case NBD_CMD_READ:
-        TRACE("Request type is READ");
-
-        if (request.type & NBD_CMD_FLAG_FUA) {
-            ret = blk_co_flush(exp->blk);
-            if (ret < 0) {
-                LOG("flush failed");
-                reply.error = -ret;
-                goto error_reply;
-            }
-        }
-
-        ret = blk_read(exp->blk,
-                       (request.from + exp->dev_offset) / BDRV_SECTOR_SIZE,
-                       req->data, request.len / BDRV_SECTOR_SIZE);
-        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 = blk_write(exp->blk,
-                        (request.from + exp->dev_offset) / BDRV_SECTOR_SIZE,
-                        req->data, request.len / BDRV_SECTOR_SIZE);
-        if (ret < 0) {
-            LOG("writing to file failed");
-            reply.error = -ret;
-            goto error_reply;
-        }
-
-        if (request.type & NBD_CMD_FLAG_FUA) {
-            ret = blk_co_flush(exp->blk);
-            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 = blk_co_flush(exp->blk);
-        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 = blk_co_discard(exp->blk, (request.from + exp->dev_offset)
-                                       / BDRV_SECTOR_SIZE,
-                             request.len / BDRV_SECTOR_SIZE);
-        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);
-    client_close(client);
-}
-
-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);
-}
-
-static void nbd_set_handlers(NBDClient *client)
-{
-    if (client->exp && client->exp->ctx) {
-        aio_set_fd_handler(client->exp->ctx, client->sock,
-                           true,
-                           client->can_read ? nbd_read : NULL,
-                           client->send_coroutine ? nbd_restart_write : NULL,
-                           client);
-    }
-}
-
-static void nbd_unset_handlers(NBDClient *client)
-{
-    if (client->exp && client->exp->ctx) {
-        aio_set_fd_handler(client->exp->ctx, client->sock,
-                           true, NULL, NULL, NULL);
-    }
-}
-
-static void nbd_update_can_read(NBDClient *client)
-{
-    bool can_read = client->recv_coroutine ||
-                    client->nb_requests < MAX_NBD_REQUESTS;
-
-    if (can_read != client->can_read) {
-        client->can_read = can_read;
-        nbd_set_handlers(client);
-
-        /* There is no need to invoke aio_notify(), since aio_set_fd_handler()
-         * in nbd_set_handlers() will have taken care of that */
-    }
-}
-
-void nbd_client_new(NBDExport *exp, int csock, void (*close_fn)(NBDClient *))
-{
-    NBDClient *client;
-    client = g_malloc0(sizeof(NBDClient));
-    client->refcount = 1;
-    client->exp = exp;
-    client->sock = csock;
-    client->can_read = true;
-    if (nbd_send_negotiate(client)) {
-        shutdown(client->sock, 2);
-        close_fn(client);
-        return;
-    }
-    client->close = close_fn;
-    qemu_co_mutex_init(&client->send_lock);
-    nbd_set_handlers(client);
-
-    if (exp) {
-        QTAILQ_INSERT_TAIL(&exp->clients, client, next);
-        nbd_export_get(exp);
-    }
-}