1 /* 2 * Serving QEMU block devices via NBD 3 * 4 * Copyright (c) 2012 Red Hat, Inc. 5 * 6 * Author: Paolo Bonzini <pbonzini@redhat.com> 7 * 8 * This work is licensed under the terms of the GNU GPL, version 2 or 9 * later. See the COPYING file in the top-level directory. 10 */ 11 12 #include "qemu/osdep.h" 13 #include "sysemu/blockdev.h" 14 #include "sysemu/block-backend.h" 15 #include "hw/block/block.h" 16 #include "qapi/qmp/qerror.h" 17 #include "sysemu/sysemu.h" 18 #include "qmp-commands.h" 19 #include "trace.h" 20 #include "block/nbd.h" 21 #include "qemu/sockets.h" 22 23 static int server_fd = -1; 24 25 static void nbd_accept(void *opaque) 26 { 27 struct sockaddr_in addr; 28 socklen_t addr_len = sizeof(addr); 29 30 int fd = accept(server_fd, (struct sockaddr *)&addr, &addr_len); 31 if (fd >= 0) { 32 nbd_client_new(NULL, fd, nbd_client_put); 33 } 34 } 35 36 void qmp_nbd_server_start(SocketAddress *addr, Error **errp) 37 { 38 if (server_fd != -1) { 39 error_setg(errp, "NBD server already running"); 40 return; 41 } 42 43 server_fd = socket_listen(addr, errp); 44 if (server_fd != -1) { 45 qemu_set_fd_handler(server_fd, nbd_accept, NULL, NULL); 46 } 47 } 48 49 void qmp_nbd_server_add(const char *device, bool has_writable, bool writable, 50 Error **errp) 51 { 52 BlockBackend *blk; 53 NBDExport *exp; 54 55 if (server_fd == -1) { 56 error_setg(errp, "NBD server not running"); 57 return; 58 } 59 60 if (nbd_export_find(device)) { 61 error_setg(errp, "NBD server already exporting device '%s'", device); 62 return; 63 } 64 65 blk = blk_by_name(device); 66 if (!blk) { 67 error_set(errp, ERROR_CLASS_DEVICE_NOT_FOUND, 68 "Device '%s' not found", device); 69 return; 70 } 71 if (!blk_is_inserted(blk)) { 72 error_setg(errp, QERR_DEVICE_HAS_NO_MEDIUM, device); 73 return; 74 } 75 76 if (!has_writable) { 77 writable = false; 78 } 79 if (blk_is_read_only(blk)) { 80 writable = false; 81 } 82 83 exp = nbd_export_new(blk, 0, -1, writable ? 0 : NBD_FLAG_READ_ONLY, NULL, 84 errp); 85 if (!exp) { 86 return; 87 } 88 89 nbd_export_set_name(exp, device); 90 91 /* The list of named exports has a strong reference to this export now and 92 * our only way of accessing it is through nbd_export_find(), so we can drop 93 * the strong reference that is @exp. */ 94 nbd_export_put(exp); 95 } 96 97 void qmp_nbd_server_stop(Error **errp) 98 { 99 nbd_export_close_all(); 100 101 if (server_fd != -1) { 102 qemu_set_fd_handler(server_fd, NULL, NULL, NULL); 103 close(server_fd); 104 server_fd = -1; 105 } 106 } 107