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