1 /* 2 * QEMU Block driver for NBD 3 * 4 * Copyright (C) 2008 Bull S.A.S. 5 * Author: Laurent Vivier <Laurent.Vivier@bull.net> 6 * 7 * Some parts: 8 * Copyright (C) 2007 Anthony Liguori <anthony@codemonkey.ws> 9 * 10 * Permission is hereby granted, free of charge, to any person obtaining a copy 11 * of this software and associated documentation files (the "Software"), to deal 12 * in the Software without restriction, including without limitation the rights 13 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 14 * copies of the Software, and to permit persons to whom the Software is 15 * furnished to do so, subject to the following conditions: 16 * 17 * The above copyright notice and this permission notice shall be included in 18 * all copies or substantial portions of the Software. 19 * 20 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 21 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 22 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL 23 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 24 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 25 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN 26 * THE SOFTWARE. 27 */ 28 29 #include "qemu-common.h" 30 #include "nbd.h" 31 #include "block_int.h" 32 #include "module.h" 33 #include "qemu_socket.h" 34 35 #include <sys/types.h> 36 #include <unistd.h> 37 38 #define EN_OPTSTR ":exportname=" 39 40 /* #define DEBUG_NBD */ 41 42 #if defined(DEBUG_NBD) 43 #define logout(fmt, ...) \ 44 fprintf(stderr, "nbd\t%-24s" fmt, __func__, ##__VA_ARGS__) 45 #else 46 #define logout(fmt, ...) ((void)0) 47 #endif 48 49 typedef struct BDRVNBDState { 50 CoMutex lock; 51 int sock; 52 uint32_t nbdflags; 53 off_t size; 54 size_t blocksize; 55 char *export_name; /* An NBD server may export several devices */ 56 57 /* If it begins with '/', this is a UNIX domain socket. Otherwise, 58 * it's a string of the form <hostname|ip4|\[ip6\]>:port 59 */ 60 char *host_spec; 61 } BDRVNBDState; 62 63 static int nbd_config(BDRVNBDState *s, const char *filename, int flags) 64 { 65 char *file; 66 char *export_name; 67 const char *host_spec; 68 const char *unixpath; 69 int err = -EINVAL; 70 71 file = g_strdup(filename); 72 73 export_name = strstr(file, EN_OPTSTR); 74 if (export_name) { 75 if (export_name[strlen(EN_OPTSTR)] == 0) { 76 goto out; 77 } 78 export_name[0] = 0; /* truncate 'file' */ 79 export_name += strlen(EN_OPTSTR); 80 s->export_name = g_strdup(export_name); 81 } 82 83 /* extract the host_spec - fail if it's not nbd:... */ 84 if (!strstart(file, "nbd:", &host_spec)) { 85 goto out; 86 } 87 88 /* are we a UNIX or TCP socket? */ 89 if (strstart(host_spec, "unix:", &unixpath)) { 90 if (unixpath[0] != '/') { /* We demand an absolute path*/ 91 goto out; 92 } 93 s->host_spec = g_strdup(unixpath); 94 } else { 95 s->host_spec = g_strdup(host_spec); 96 } 97 98 err = 0; 99 100 out: 101 g_free(file); 102 if (err != 0) { 103 g_free(s->export_name); 104 g_free(s->host_spec); 105 } 106 return err; 107 } 108 109 static int nbd_establish_connection(BlockDriverState *bs) 110 { 111 BDRVNBDState *s = bs->opaque; 112 int sock; 113 int ret; 114 off_t size; 115 size_t blocksize; 116 117 if (s->host_spec[0] == '/') { 118 sock = unix_socket_outgoing(s->host_spec); 119 } else { 120 sock = tcp_socket_outgoing_spec(s->host_spec); 121 } 122 123 /* Failed to establish connection */ 124 if (sock == -1) { 125 logout("Failed to establish connection to NBD server\n"); 126 return -errno; 127 } 128 129 /* NBD handshake */ 130 ret = nbd_receive_negotiate(sock, s->export_name, &s->nbdflags, &size, 131 &blocksize); 132 if (ret == -1) { 133 logout("Failed to negotiate with the NBD server\n"); 134 closesocket(sock); 135 return -errno; 136 } 137 138 /* Now that we're connected, set the socket to be non-blocking */ 139 socket_set_nonblock(sock); 140 141 s->sock = sock; 142 s->size = size; 143 s->blocksize = blocksize; 144 145 logout("Established connection with NBD server\n"); 146 return 0; 147 } 148 149 static void nbd_teardown_connection(BlockDriverState *bs) 150 { 151 BDRVNBDState *s = bs->opaque; 152 struct nbd_request request; 153 154 request.type = NBD_CMD_DISC; 155 request.handle = (uint64_t)(intptr_t)bs; 156 request.from = 0; 157 request.len = 0; 158 nbd_send_request(s->sock, &request); 159 160 closesocket(s->sock); 161 } 162 163 static int nbd_open(BlockDriverState *bs, const char* filename, int flags) 164 { 165 BDRVNBDState *s = bs->opaque; 166 int result; 167 168 /* Pop the config into our state object. Exit if invalid. */ 169 result = nbd_config(s, filename, flags); 170 if (result != 0) { 171 return result; 172 } 173 174 /* establish TCP connection, return error if it fails 175 * TODO: Configurable retry-until-timeout behaviour. 176 */ 177 result = nbd_establish_connection(bs); 178 179 qemu_co_mutex_init(&s->lock); 180 return result; 181 } 182 183 static int nbd_read(BlockDriverState *bs, int64_t sector_num, 184 uint8_t *buf, int nb_sectors) 185 { 186 BDRVNBDState *s = bs->opaque; 187 struct nbd_request request; 188 struct nbd_reply reply; 189 190 request.type = NBD_CMD_READ; 191 request.handle = (uint64_t)(intptr_t)bs; 192 request.from = sector_num * 512;; 193 request.len = nb_sectors * 512; 194 195 if (nbd_send_request(s->sock, &request) == -1) 196 return -errno; 197 198 if (nbd_receive_reply(s->sock, &reply) == -1) 199 return -errno; 200 201 if (reply.error !=0) 202 return -reply.error; 203 204 if (reply.handle != request.handle) 205 return -EIO; 206 207 if (nbd_wr_sync(s->sock, buf, request.len, 1) != request.len) 208 return -EIO; 209 210 return 0; 211 } 212 213 static int nbd_write(BlockDriverState *bs, int64_t sector_num, 214 const uint8_t *buf, int nb_sectors) 215 { 216 BDRVNBDState *s = bs->opaque; 217 struct nbd_request request; 218 struct nbd_reply reply; 219 220 request.type = NBD_CMD_WRITE; 221 request.handle = (uint64_t)(intptr_t)bs; 222 request.from = sector_num * 512;; 223 request.len = nb_sectors * 512; 224 225 if (nbd_send_request(s->sock, &request) == -1) 226 return -errno; 227 228 if (nbd_wr_sync(s->sock, (uint8_t*)buf, request.len, 0) != request.len) 229 return -EIO; 230 231 if (nbd_receive_reply(s->sock, &reply) == -1) 232 return -errno; 233 234 if (reply.error !=0) 235 return -reply.error; 236 237 if (reply.handle != request.handle) 238 return -EIO; 239 240 return 0; 241 } 242 243 static coroutine_fn int nbd_co_read(BlockDriverState *bs, int64_t sector_num, 244 uint8_t *buf, int nb_sectors) 245 { 246 int ret; 247 BDRVNBDState *s = bs->opaque; 248 qemu_co_mutex_lock(&s->lock); 249 ret = nbd_read(bs, sector_num, buf, nb_sectors); 250 qemu_co_mutex_unlock(&s->lock); 251 return ret; 252 } 253 254 static coroutine_fn int nbd_co_write(BlockDriverState *bs, int64_t sector_num, 255 const uint8_t *buf, int nb_sectors) 256 { 257 int ret; 258 BDRVNBDState *s = bs->opaque; 259 qemu_co_mutex_lock(&s->lock); 260 ret = nbd_write(bs, sector_num, buf, nb_sectors); 261 qemu_co_mutex_unlock(&s->lock); 262 return ret; 263 } 264 265 static void nbd_close(BlockDriverState *bs) 266 { 267 BDRVNBDState *s = bs->opaque; 268 g_free(s->export_name); 269 g_free(s->host_spec); 270 271 nbd_teardown_connection(bs); 272 } 273 274 static int64_t nbd_getlength(BlockDriverState *bs) 275 { 276 BDRVNBDState *s = bs->opaque; 277 278 return s->size; 279 } 280 281 static BlockDriver bdrv_nbd = { 282 .format_name = "nbd", 283 .instance_size = sizeof(BDRVNBDState), 284 .bdrv_file_open = nbd_open, 285 .bdrv_read = nbd_co_read, 286 .bdrv_write = nbd_co_write, 287 .bdrv_close = nbd_close, 288 .bdrv_getlength = nbd_getlength, 289 .protocol_name = "nbd", 290 }; 291 292 static void bdrv_nbd_init(void) 293 { 294 bdrv_register(&bdrv_nbd); 295 } 296 297 block_init(bdrv_nbd_init); 298