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![Fam Zheng](/assets/img/avatar_default.png)
So we could distinguish it from internal used fds, thus avoid handling unwanted events in nested aio polls. Signed-off-by: Fam Zheng <famz@redhat.com> Reviewed-by: Jeff Cody <jcody@redhat.com> Reviewed-by: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
1501 lines
37 KiB
C
1501 lines
37 KiB
C
/*
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* Copyright (C) 2005 Anthony Liguori <anthony@codemonkey.ws>
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*
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* Network Block Device
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; under version 2 of the License.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, see <http://www.gnu.org/licenses/>.
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*/
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#include "block/nbd.h"
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#include "sysemu/block-backend.h"
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#include "qemu/coroutine.h"
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#include <errno.h>
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#include <string.h>
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#ifndef _WIN32
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#include <sys/ioctl.h>
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#endif
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#if defined(__sun__) || defined(__HAIKU__)
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#include <sys/ioccom.h>
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#endif
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#include <ctype.h>
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#include <inttypes.h>
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#ifdef __linux__
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#include <linux/fs.h>
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#endif
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#include "qemu/sockets.h"
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#include "qemu/queue.h"
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#include "qemu/main-loop.h"
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//#define DEBUG_NBD
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#ifdef DEBUG_NBD
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#define TRACE(msg, ...) do { \
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LOG(msg, ## __VA_ARGS__); \
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} while(0)
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#else
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#define TRACE(msg, ...) \
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do { } while (0)
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#endif
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#define LOG(msg, ...) do { \
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fprintf(stderr, "%s:%s():L%d: " msg "\n", \
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__FILE__, __FUNCTION__, __LINE__, ## __VA_ARGS__); \
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} while(0)
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/* This is all part of the "official" NBD API.
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*
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* The most up-to-date documentation is available at:
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* https://github.com/yoe/nbd/blob/master/doc/proto.txt
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*/
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#define NBD_REQUEST_SIZE (4 + 4 + 8 + 8 + 4)
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#define NBD_REPLY_SIZE (4 + 4 + 8)
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#define NBD_REQUEST_MAGIC 0x25609513
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#define NBD_REPLY_MAGIC 0x67446698
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#define NBD_OPTS_MAGIC 0x49484156454F5054LL
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#define NBD_CLIENT_MAGIC 0x0000420281861253LL
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#define NBD_REP_MAGIC 0x3e889045565a9LL
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#define NBD_SET_SOCK _IO(0xab, 0)
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#define NBD_SET_BLKSIZE _IO(0xab, 1)
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#define NBD_SET_SIZE _IO(0xab, 2)
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#define NBD_DO_IT _IO(0xab, 3)
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#define NBD_CLEAR_SOCK _IO(0xab, 4)
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#define NBD_CLEAR_QUE _IO(0xab, 5)
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#define NBD_PRINT_DEBUG _IO(0xab, 6)
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#define NBD_SET_SIZE_BLOCKS _IO(0xab, 7)
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#define NBD_DISCONNECT _IO(0xab, 8)
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#define NBD_SET_TIMEOUT _IO(0xab, 9)
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#define NBD_SET_FLAGS _IO(0xab, 10)
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#define NBD_OPT_EXPORT_NAME (1)
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#define NBD_OPT_ABORT (2)
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#define NBD_OPT_LIST (3)
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/* NBD errors are based on errno numbers, so there is a 1:1 mapping,
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* but only a limited set of errno values is specified in the protocol.
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* Everything else is squashed to EINVAL.
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*/
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#define NBD_SUCCESS 0
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#define NBD_EPERM 1
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#define NBD_EIO 5
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#define NBD_ENOMEM 12
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#define NBD_EINVAL 22
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#define NBD_ENOSPC 28
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static int system_errno_to_nbd_errno(int err)
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{
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switch (err) {
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case 0:
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return NBD_SUCCESS;
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case EPERM:
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return NBD_EPERM;
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case EIO:
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return NBD_EIO;
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case ENOMEM:
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return NBD_ENOMEM;
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#ifdef EDQUOT
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case EDQUOT:
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#endif
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case EFBIG:
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case ENOSPC:
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return NBD_ENOSPC;
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case EINVAL:
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default:
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return NBD_EINVAL;
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}
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}
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static int nbd_errno_to_system_errno(int err)
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{
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switch (err) {
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case NBD_SUCCESS:
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return 0;
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case NBD_EPERM:
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return EPERM;
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case NBD_EIO:
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return EIO;
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case NBD_ENOMEM:
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return ENOMEM;
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case NBD_ENOSPC:
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return ENOSPC;
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case NBD_EINVAL:
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default:
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return EINVAL;
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}
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}
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/* Definitions for opaque data types */
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typedef struct NBDRequest NBDRequest;
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struct NBDRequest {
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QSIMPLEQ_ENTRY(NBDRequest) entry;
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NBDClient *client;
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uint8_t *data;
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};
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struct NBDExport {
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int refcount;
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void (*close)(NBDExport *exp);
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BlockBackend *blk;
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char *name;
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off_t dev_offset;
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off_t size;
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uint32_t nbdflags;
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QTAILQ_HEAD(, NBDClient) clients;
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QTAILQ_ENTRY(NBDExport) next;
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AioContext *ctx;
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};
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static QTAILQ_HEAD(, NBDExport) exports = QTAILQ_HEAD_INITIALIZER(exports);
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struct NBDClient {
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int refcount;
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void (*close)(NBDClient *client);
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NBDExport *exp;
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int sock;
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Coroutine *recv_coroutine;
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CoMutex send_lock;
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Coroutine *send_coroutine;
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bool can_read;
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QTAILQ_ENTRY(NBDClient) next;
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int nb_requests;
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bool closing;
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};
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/* That's all folks */
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static void nbd_set_handlers(NBDClient *client);
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static void nbd_unset_handlers(NBDClient *client);
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static void nbd_update_can_read(NBDClient *client);
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ssize_t nbd_wr_sync(int fd, void *buffer, size_t size, bool do_read)
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{
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size_t offset = 0;
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int err;
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if (qemu_in_coroutine()) {
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if (do_read) {
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return qemu_co_recv(fd, buffer, size);
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} else {
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return qemu_co_send(fd, buffer, size);
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}
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}
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while (offset < size) {
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ssize_t len;
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if (do_read) {
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len = qemu_recv(fd, buffer + offset, size - offset, 0);
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} else {
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len = send(fd, buffer + offset, size - offset, 0);
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}
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if (len < 0) {
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err = socket_error();
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/* recoverable error */
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if (err == EINTR || (offset > 0 && (err == EAGAIN || err == EWOULDBLOCK))) {
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continue;
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}
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/* unrecoverable error */
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return -err;
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}
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/* eof */
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if (len == 0) {
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break;
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}
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offset += len;
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}
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return offset;
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}
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static ssize_t read_sync(int fd, void *buffer, size_t size)
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{
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/* Sockets are kept in blocking mode in the negotiation phase. After
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* that, a non-readable socket simply means that another thread stole
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* our request/reply. Synchronization is done with recv_coroutine, so
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* that this is coroutine-safe.
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*/
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return nbd_wr_sync(fd, buffer, size, true);
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}
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static ssize_t drop_sync(int fd, size_t size)
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{
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ssize_t ret, dropped = size;
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uint8_t *buffer = g_malloc(MIN(65536, size));
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while (size > 0) {
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ret = read_sync(fd, buffer, MIN(65536, size));
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if (ret < 0) {
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g_free(buffer);
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return ret;
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}
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assert(ret <= size);
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size -= ret;
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}
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g_free(buffer);
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return dropped;
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}
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static ssize_t write_sync(int fd, void *buffer, size_t size)
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{
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int ret;
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do {
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/* For writes, we do expect the socket to be writable. */
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ret = nbd_wr_sync(fd, buffer, size, false);
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} while (ret == -EAGAIN);
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return ret;
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}
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/* Basic flow for negotiation
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Server Client
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Negotiate
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or
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Server Client
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Negotiate #1
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Option
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Negotiate #2
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----
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followed by
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Server Client
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Request
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Response
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Request
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Response
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...
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...
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Request (type == 2)
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*/
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static int nbd_send_rep(int csock, uint32_t type, uint32_t opt)
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{
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uint64_t magic;
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uint32_t len;
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magic = cpu_to_be64(NBD_REP_MAGIC);
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if (write_sync(csock, &magic, sizeof(magic)) != sizeof(magic)) {
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LOG("write failed (rep magic)");
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return -EINVAL;
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}
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opt = cpu_to_be32(opt);
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if (write_sync(csock, &opt, sizeof(opt)) != sizeof(opt)) {
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LOG("write failed (rep opt)");
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return -EINVAL;
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}
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type = cpu_to_be32(type);
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if (write_sync(csock, &type, sizeof(type)) != sizeof(type)) {
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LOG("write failed (rep type)");
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return -EINVAL;
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}
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len = cpu_to_be32(0);
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if (write_sync(csock, &len, sizeof(len)) != sizeof(len)) {
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LOG("write failed (rep data length)");
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return -EINVAL;
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}
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return 0;
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}
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static int nbd_send_rep_list(int csock, NBDExport *exp)
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{
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uint64_t magic, name_len;
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uint32_t opt, type, len;
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name_len = strlen(exp->name);
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magic = cpu_to_be64(NBD_REP_MAGIC);
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if (write_sync(csock, &magic, sizeof(magic)) != sizeof(magic)) {
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LOG("write failed (magic)");
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return -EINVAL;
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}
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opt = cpu_to_be32(NBD_OPT_LIST);
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if (write_sync(csock, &opt, sizeof(opt)) != sizeof(opt)) {
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LOG("write failed (opt)");
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return -EINVAL;
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}
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type = cpu_to_be32(NBD_REP_SERVER);
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if (write_sync(csock, &type, sizeof(type)) != sizeof(type)) {
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LOG("write failed (reply type)");
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return -EINVAL;
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}
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len = cpu_to_be32(name_len + sizeof(len));
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if (write_sync(csock, &len, sizeof(len)) != sizeof(len)) {
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LOG("write failed (length)");
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return -EINVAL;
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}
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len = cpu_to_be32(name_len);
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if (write_sync(csock, &len, sizeof(len)) != sizeof(len)) {
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LOG("write failed (length)");
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return -EINVAL;
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}
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if (write_sync(csock, exp->name, name_len) != name_len) {
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LOG("write failed (buffer)");
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return -EINVAL;
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}
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return 0;
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}
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static int nbd_handle_list(NBDClient *client, uint32_t length)
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{
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int csock;
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NBDExport *exp;
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csock = client->sock;
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if (length) {
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if (drop_sync(csock, length) != length) {
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return -EIO;
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}
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return nbd_send_rep(csock, NBD_REP_ERR_INVALID, NBD_OPT_LIST);
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}
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/* For each export, send a NBD_REP_SERVER reply. */
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QTAILQ_FOREACH(exp, &exports, next) {
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if (nbd_send_rep_list(csock, exp)) {
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return -EINVAL;
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}
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}
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/* Finish with a NBD_REP_ACK. */
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return nbd_send_rep(csock, NBD_REP_ACK, NBD_OPT_LIST);
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}
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static int nbd_handle_export_name(NBDClient *client, uint32_t length)
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{
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int rc = -EINVAL, csock = client->sock;
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char name[256];
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/* Client sends:
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[20 .. xx] export name (length bytes)
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*/
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TRACE("Checking length");
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if (length > 255) {
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LOG("Bad length received");
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goto fail;
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}
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if (read_sync(csock, name, length) != length) {
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LOG("read failed");
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goto fail;
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}
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name[length] = '\0';
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client->exp = nbd_export_find(name);
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if (!client->exp) {
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LOG("export not found");
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goto fail;
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}
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QTAILQ_INSERT_TAIL(&client->exp->clients, client, next);
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nbd_export_get(client->exp);
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rc = 0;
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fail:
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return rc;
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}
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static int nbd_receive_options(NBDClient *client)
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{
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int csock = client->sock;
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uint32_t flags;
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/* Client sends:
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[ 0 .. 3] client flags
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[ 0 .. 7] NBD_OPTS_MAGIC
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[ 8 .. 11] NBD option
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[12 .. 15] Data length
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... Rest of request
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[ 0 .. 7] NBD_OPTS_MAGIC
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[ 8 .. 11] Second NBD option
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[12 .. 15] Data length
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... Rest of request
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*/
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if (read_sync(csock, &flags, sizeof(flags)) != sizeof(flags)) {
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LOG("read failed");
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return -EIO;
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}
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TRACE("Checking client flags");
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be32_to_cpus(&flags);
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if (flags != 0 && flags != NBD_FLAG_C_FIXED_NEWSTYLE) {
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LOG("Bad client flags received");
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return -EIO;
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}
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while (1) {
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int ret;
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uint32_t tmp, length;
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uint64_t magic;
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|
|
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if (read_sync(csock, &magic, sizeof(magic)) != sizeof(magic)) {
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LOG("read failed");
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return -EINVAL;
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}
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TRACE("Checking opts magic");
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if (magic != be64_to_cpu(NBD_OPTS_MAGIC)) {
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LOG("Bad magic received");
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return -EINVAL;
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}
|
|
|
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if (read_sync(csock, &tmp, sizeof(tmp)) != sizeof(tmp)) {
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LOG("read failed");
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return -EINVAL;
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}
|
|
|
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if (read_sync(csock, &length, sizeof(length)) != sizeof(length)) {
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LOG("read failed");
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return -EINVAL;
|
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}
|
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length = be32_to_cpu(length);
|
|
|
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TRACE("Checking option");
|
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switch (be32_to_cpu(tmp)) {
|
|
case NBD_OPT_LIST:
|
|
ret = nbd_handle_list(client, length);
|
|
if (ret < 0) {
|
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return ret;
|
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}
|
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break;
|
|
|
|
case NBD_OPT_ABORT:
|
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return -EINVAL;
|
|
|
|
case NBD_OPT_EXPORT_NAME:
|
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return nbd_handle_export_name(client, length);
|
|
|
|
default:
|
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tmp = be32_to_cpu(tmp);
|
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LOG("Unsupported option 0x%x", tmp);
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nbd_send_rep(client->sock, NBD_REP_ERR_UNSUP, tmp);
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return -EINVAL;
|
|
}
|
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}
|
|
}
|
|
|
|
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 */
|
|
}
|
|
}
|
|
|
|
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;
|
|
client->can_read = true;
|
|
if (nbd_send_negotiate(client)) {
|
|
g_free(client);
|
|
return NULL;
|
|
}
|
|
client->close = close;
|
|
qemu_co_mutex_init(&client->send_lock);
|
|
nbd_set_handlers(client);
|
|
|
|
if (exp) {
|
|
QTAILQ_INSERT_TAIL(&exp->clients, client, next);
|
|
nbd_export_get(exp);
|
|
}
|
|
return client;
|
|
}
|