1 /* 2 * Network block device - make block devices work over TCP 3 * 4 * Note that you can not swap over this thing, yet. Seems to work but 5 * deadlocks sometimes - you can not swap over TCP in general. 6 * 7 * Copyright 1997-2000 Pavel Machek <pavel@ucw.cz> 8 * Parts copyright 2001 Steven Whitehouse <steve@chygwyn.com> 9 * 10 * This file is released under GPLv2 or later. 11 * 12 * (part of code stolen from loop.c) 13 */ 14 15 #include <linux/major.h> 16 17 #include <linux/blkdev.h> 18 #include <linux/module.h> 19 #include <linux/init.h> 20 #include <linux/sched.h> 21 #include <linux/fs.h> 22 #include <linux/bio.h> 23 #include <linux/stat.h> 24 #include <linux/errno.h> 25 #include <linux/file.h> 26 #include <linux/ioctl.h> 27 #include <linux/compiler.h> 28 #include <linux/err.h> 29 #include <linux/kernel.h> 30 #include <net/sock.h> 31 #include <linux/net.h> 32 33 #include <asm/uaccess.h> 34 #include <asm/system.h> 35 #include <asm/types.h> 36 37 #include <linux/nbd.h> 38 39 #define LO_MAGIC 0x68797548 40 41 #ifdef NDEBUG 42 #define dprintk(flags, fmt...) 43 #else /* NDEBUG */ 44 #define dprintk(flags, fmt...) do { \ 45 if (debugflags & (flags)) printk(KERN_DEBUG fmt); \ 46 } while (0) 47 #define DBG_IOCTL 0x0004 48 #define DBG_INIT 0x0010 49 #define DBG_EXIT 0x0020 50 #define DBG_BLKDEV 0x0100 51 #define DBG_RX 0x0200 52 #define DBG_TX 0x0400 53 static unsigned int debugflags; 54 #endif /* NDEBUG */ 55 56 static unsigned int nbds_max = 16; 57 static struct nbd_device nbd_dev[MAX_NBD]; 58 59 /* 60 * Use just one lock (or at most 1 per NIC). Two arguments for this: 61 * 1. Each NIC is essentially a synchronization point for all servers 62 * accessed through that NIC so there's no need to have more locks 63 * than NICs anyway. 64 * 2. More locks lead to more "Dirty cache line bouncing" which will slow 65 * down each lock to the point where they're actually slower than just 66 * a single lock. 67 * Thanks go to Jens Axboe and Al Viro for their LKML emails explaining this! 68 */ 69 static DEFINE_SPINLOCK(nbd_lock); 70 71 #ifndef NDEBUG 72 static const char *ioctl_cmd_to_ascii(int cmd) 73 { 74 switch (cmd) { 75 case NBD_SET_SOCK: return "set-sock"; 76 case NBD_SET_BLKSIZE: return "set-blksize"; 77 case NBD_SET_SIZE: return "set-size"; 78 case NBD_DO_IT: return "do-it"; 79 case NBD_CLEAR_SOCK: return "clear-sock"; 80 case NBD_CLEAR_QUE: return "clear-que"; 81 case NBD_PRINT_DEBUG: return "print-debug"; 82 case NBD_SET_SIZE_BLOCKS: return "set-size-blocks"; 83 case NBD_DISCONNECT: return "disconnect"; 84 case BLKROSET: return "set-read-only"; 85 case BLKFLSBUF: return "flush-buffer-cache"; 86 } 87 return "unknown"; 88 } 89 90 static const char *nbdcmd_to_ascii(int cmd) 91 { 92 switch (cmd) { 93 case NBD_CMD_READ: return "read"; 94 case NBD_CMD_WRITE: return "write"; 95 case NBD_CMD_DISC: return "disconnect"; 96 } 97 return "invalid"; 98 } 99 #endif /* NDEBUG */ 100 101 static void nbd_end_request(struct request *req) 102 { 103 int uptodate = (req->errors == 0) ? 1 : 0; 104 struct request_queue *q = req->q; 105 unsigned long flags; 106 107 dprintk(DBG_BLKDEV, "%s: request %p: %s\n", req->rq_disk->disk_name, 108 req, uptodate? "done": "failed"); 109 110 spin_lock_irqsave(q->queue_lock, flags); 111 if (!end_that_request_first(req, uptodate, req->nr_sectors)) { 112 end_that_request_last(req, uptodate); 113 } 114 spin_unlock_irqrestore(q->queue_lock, flags); 115 } 116 117 static void sock_shutdown(struct nbd_device *lo, int lock) 118 { 119 /* Forcibly shutdown the socket causing all listeners 120 * to error 121 * 122 * FIXME: This code is duplicated from sys_shutdown, but 123 * there should be a more generic interface rather than 124 * calling socket ops directly here */ 125 if (lock) 126 mutex_lock(&lo->tx_lock); 127 if (lo->sock) { 128 printk(KERN_WARNING "%s: shutting down socket\n", 129 lo->disk->disk_name); 130 kernel_sock_shutdown(lo->sock, SHUT_RDWR); 131 lo->sock = NULL; 132 } 133 if (lock) 134 mutex_unlock(&lo->tx_lock); 135 } 136 137 static void nbd_xmit_timeout(unsigned long arg) 138 { 139 struct task_struct *task = (struct task_struct *)arg; 140 141 printk(KERN_WARNING "nbd: killing hung xmit (%s, pid: %d)\n", 142 task->comm, task->pid); 143 force_sig(SIGKILL, task); 144 } 145 146 /* 147 * Send or receive packet. 148 */ 149 static int sock_xmit(struct nbd_device *lo, int send, void *buf, int size, 150 int msg_flags) 151 { 152 struct socket *sock = lo->sock; 153 int result; 154 struct msghdr msg; 155 struct kvec iov; 156 sigset_t blocked, oldset; 157 158 /* Allow interception of SIGKILL only 159 * Don't allow other signals to interrupt the transmission */ 160 siginitsetinv(&blocked, sigmask(SIGKILL)); 161 sigprocmask(SIG_SETMASK, &blocked, &oldset); 162 163 do { 164 sock->sk->sk_allocation = GFP_NOIO; 165 iov.iov_base = buf; 166 iov.iov_len = size; 167 msg.msg_name = NULL; 168 msg.msg_namelen = 0; 169 msg.msg_control = NULL; 170 msg.msg_controllen = 0; 171 msg.msg_flags = msg_flags | MSG_NOSIGNAL; 172 173 if (send) { 174 struct timer_list ti; 175 176 if (lo->xmit_timeout) { 177 init_timer(&ti); 178 ti.function = nbd_xmit_timeout; 179 ti.data = (unsigned long)current; 180 ti.expires = jiffies + lo->xmit_timeout; 181 add_timer(&ti); 182 } 183 result = kernel_sendmsg(sock, &msg, &iov, 1, size); 184 if (lo->xmit_timeout) 185 del_timer_sync(&ti); 186 } else 187 result = kernel_recvmsg(sock, &msg, &iov, 1, size, 0); 188 189 if (signal_pending(current)) { 190 siginfo_t info; 191 printk(KERN_WARNING "nbd (pid %d: %s) got signal %d\n", 192 task_pid_nr(current), current->comm, 193 dequeue_signal_lock(current, ¤t->blocked, &info)); 194 result = -EINTR; 195 sock_shutdown(lo, !send); 196 break; 197 } 198 199 if (result <= 0) { 200 if (result == 0) 201 result = -EPIPE; /* short read */ 202 break; 203 } 204 size -= result; 205 buf += result; 206 } while (size > 0); 207 208 sigprocmask(SIG_SETMASK, &oldset, NULL); 209 210 return result; 211 } 212 213 static inline int sock_send_bvec(struct nbd_device *lo, struct bio_vec *bvec, 214 int flags) 215 { 216 int result; 217 void *kaddr = kmap(bvec->bv_page); 218 result = sock_xmit(lo, 1, kaddr + bvec->bv_offset, bvec->bv_len, flags); 219 kunmap(bvec->bv_page); 220 return result; 221 } 222 223 /* always call with the tx_lock held */ 224 static int nbd_send_req(struct nbd_device *lo, struct request *req) 225 { 226 int result, flags; 227 struct nbd_request request; 228 unsigned long size = req->nr_sectors << 9; 229 230 request.magic = htonl(NBD_REQUEST_MAGIC); 231 request.type = htonl(nbd_cmd(req)); 232 request.from = cpu_to_be64((u64) req->sector << 9); 233 request.len = htonl(size); 234 memcpy(request.handle, &req, sizeof(req)); 235 236 dprintk(DBG_TX, "%s: request %p: sending control (%s@%llu,%luB)\n", 237 lo->disk->disk_name, req, 238 nbdcmd_to_ascii(nbd_cmd(req)), 239 (unsigned long long)req->sector << 9, 240 req->nr_sectors << 9); 241 result = sock_xmit(lo, 1, &request, sizeof(request), 242 (nbd_cmd(req) == NBD_CMD_WRITE) ? MSG_MORE : 0); 243 if (result <= 0) { 244 printk(KERN_ERR "%s: Send control failed (result %d)\n", 245 lo->disk->disk_name, result); 246 goto error_out; 247 } 248 249 if (nbd_cmd(req) == NBD_CMD_WRITE) { 250 struct req_iterator iter; 251 struct bio_vec *bvec; 252 /* 253 * we are really probing at internals to determine 254 * whether to set MSG_MORE or not... 255 */ 256 rq_for_each_segment(bvec, req, iter) { 257 flags = 0; 258 if (!rq_iter_last(req, iter)) 259 flags = MSG_MORE; 260 dprintk(DBG_TX, "%s: request %p: sending %d bytes data\n", 261 lo->disk->disk_name, req, bvec->bv_len); 262 result = sock_send_bvec(lo, bvec, flags); 263 if (result <= 0) { 264 printk(KERN_ERR "%s: Send data failed (result %d)\n", 265 lo->disk->disk_name, result); 266 goto error_out; 267 } 268 } 269 } 270 return 0; 271 272 error_out: 273 return 1; 274 } 275 276 static struct request *nbd_find_request(struct nbd_device *lo, 277 struct request *xreq) 278 { 279 struct request *req, *tmp; 280 int err; 281 282 err = wait_event_interruptible(lo->active_wq, lo->active_req != xreq); 283 if (unlikely(err)) 284 goto out; 285 286 spin_lock(&lo->queue_lock); 287 list_for_each_entry_safe(req, tmp, &lo->queue_head, queuelist) { 288 if (req != xreq) 289 continue; 290 list_del_init(&req->queuelist); 291 spin_unlock(&lo->queue_lock); 292 return req; 293 } 294 spin_unlock(&lo->queue_lock); 295 296 err = -ENOENT; 297 298 out: 299 return ERR_PTR(err); 300 } 301 302 static inline int sock_recv_bvec(struct nbd_device *lo, struct bio_vec *bvec) 303 { 304 int result; 305 void *kaddr = kmap(bvec->bv_page); 306 result = sock_xmit(lo, 0, kaddr + bvec->bv_offset, bvec->bv_len, 307 MSG_WAITALL); 308 kunmap(bvec->bv_page); 309 return result; 310 } 311 312 /* NULL returned = something went wrong, inform userspace */ 313 static struct request *nbd_read_stat(struct nbd_device *lo) 314 { 315 int result; 316 struct nbd_reply reply; 317 struct request *req; 318 319 reply.magic = 0; 320 result = sock_xmit(lo, 0, &reply, sizeof(reply), MSG_WAITALL); 321 if (result <= 0) { 322 printk(KERN_ERR "%s: Receive control failed (result %d)\n", 323 lo->disk->disk_name, result); 324 goto harderror; 325 } 326 327 if (ntohl(reply.magic) != NBD_REPLY_MAGIC) { 328 printk(KERN_ERR "%s: Wrong magic (0x%lx)\n", 329 lo->disk->disk_name, 330 (unsigned long)ntohl(reply.magic)); 331 result = -EPROTO; 332 goto harderror; 333 } 334 335 req = nbd_find_request(lo, *(struct request **)reply.handle); 336 if (unlikely(IS_ERR(req))) { 337 result = PTR_ERR(req); 338 if (result != -ENOENT) 339 goto harderror; 340 341 printk(KERN_ERR "%s: Unexpected reply (%p)\n", 342 lo->disk->disk_name, reply.handle); 343 result = -EBADR; 344 goto harderror; 345 } 346 347 if (ntohl(reply.error)) { 348 printk(KERN_ERR "%s: Other side returned error (%d)\n", 349 lo->disk->disk_name, ntohl(reply.error)); 350 req->errors++; 351 return req; 352 } 353 354 dprintk(DBG_RX, "%s: request %p: got reply\n", 355 lo->disk->disk_name, req); 356 if (nbd_cmd(req) == NBD_CMD_READ) { 357 struct req_iterator iter; 358 struct bio_vec *bvec; 359 360 rq_for_each_segment(bvec, req, iter) { 361 result = sock_recv_bvec(lo, bvec); 362 if (result <= 0) { 363 printk(KERN_ERR "%s: Receive data failed (result %d)\n", 364 lo->disk->disk_name, result); 365 req->errors++; 366 return req; 367 } 368 dprintk(DBG_RX, "%s: request %p: got %d bytes data\n", 369 lo->disk->disk_name, req, bvec->bv_len); 370 } 371 } 372 return req; 373 harderror: 374 lo->harderror = result; 375 return NULL; 376 } 377 378 static ssize_t pid_show(struct device *dev, 379 struct device_attribute *attr, char *buf) 380 { 381 struct gendisk *disk = dev_to_disk(dev); 382 383 return sprintf(buf, "%ld\n", 384 (long) ((struct nbd_device *)disk->private_data)->pid); 385 } 386 387 static struct device_attribute pid_attr = { 388 .attr = { .name = "pid", .mode = S_IRUGO, .owner = THIS_MODULE }, 389 .show = pid_show, 390 }; 391 392 static int nbd_do_it(struct nbd_device *lo) 393 { 394 struct request *req; 395 int ret; 396 397 BUG_ON(lo->magic != LO_MAGIC); 398 399 lo->pid = current->pid; 400 ret = sysfs_create_file(&lo->disk->dev.kobj, &pid_attr.attr); 401 if (ret) { 402 printk(KERN_ERR "nbd: sysfs_create_file failed!"); 403 return ret; 404 } 405 406 while ((req = nbd_read_stat(lo)) != NULL) 407 nbd_end_request(req); 408 409 sysfs_remove_file(&lo->disk->dev.kobj, &pid_attr.attr); 410 return 0; 411 } 412 413 static void nbd_clear_que(struct nbd_device *lo) 414 { 415 struct request *req; 416 417 BUG_ON(lo->magic != LO_MAGIC); 418 419 /* 420 * Because we have set lo->sock to NULL under the tx_lock, all 421 * modifications to the list must have completed by now. For 422 * the same reason, the active_req must be NULL. 423 * 424 * As a consequence, we don't need to take the spin lock while 425 * purging the list here. 426 */ 427 BUG_ON(lo->sock); 428 BUG_ON(lo->active_req); 429 430 while (!list_empty(&lo->queue_head)) { 431 req = list_entry(lo->queue_head.next, struct request, 432 queuelist); 433 list_del_init(&req->queuelist); 434 req->errors++; 435 nbd_end_request(req); 436 } 437 } 438 439 440 /* 441 * We always wait for result of write, for now. It would be nice to make it optional 442 * in future 443 * if ((rq_data_dir(req) == WRITE) && (lo->flags & NBD_WRITE_NOCHK)) 444 * { printk( "Warning: Ignoring result!\n"); nbd_end_request( req ); } 445 */ 446 447 static void do_nbd_request(struct request_queue * q) 448 { 449 struct request *req; 450 451 while ((req = elv_next_request(q)) != NULL) { 452 struct nbd_device *lo; 453 454 blkdev_dequeue_request(req); 455 dprintk(DBG_BLKDEV, "%s: request %p: dequeued (flags=%x)\n", 456 req->rq_disk->disk_name, req, req->cmd_type); 457 458 if (!blk_fs_request(req)) 459 goto error_out; 460 461 lo = req->rq_disk->private_data; 462 463 BUG_ON(lo->magic != LO_MAGIC); 464 465 nbd_cmd(req) = NBD_CMD_READ; 466 if (rq_data_dir(req) == WRITE) { 467 nbd_cmd(req) = NBD_CMD_WRITE; 468 if (lo->flags & NBD_READ_ONLY) { 469 printk(KERN_ERR "%s: Write on read-only\n", 470 lo->disk->disk_name); 471 goto error_out; 472 } 473 } 474 475 req->errors = 0; 476 spin_unlock_irq(q->queue_lock); 477 478 mutex_lock(&lo->tx_lock); 479 if (unlikely(!lo->sock)) { 480 mutex_unlock(&lo->tx_lock); 481 printk(KERN_ERR "%s: Attempted send on closed socket\n", 482 lo->disk->disk_name); 483 req->errors++; 484 nbd_end_request(req); 485 spin_lock_irq(q->queue_lock); 486 continue; 487 } 488 489 lo->active_req = req; 490 491 if (nbd_send_req(lo, req) != 0) { 492 printk(KERN_ERR "%s: Request send failed\n", 493 lo->disk->disk_name); 494 req->errors++; 495 nbd_end_request(req); 496 } else { 497 spin_lock(&lo->queue_lock); 498 list_add(&req->queuelist, &lo->queue_head); 499 spin_unlock(&lo->queue_lock); 500 } 501 502 lo->active_req = NULL; 503 mutex_unlock(&lo->tx_lock); 504 wake_up_all(&lo->active_wq); 505 506 spin_lock_irq(q->queue_lock); 507 continue; 508 509 error_out: 510 req->errors++; 511 spin_unlock(q->queue_lock); 512 nbd_end_request(req); 513 spin_lock(q->queue_lock); 514 } 515 } 516 517 static int nbd_ioctl(struct inode *inode, struct file *file, 518 unsigned int cmd, unsigned long arg) 519 { 520 struct nbd_device *lo = inode->i_bdev->bd_disk->private_data; 521 int error; 522 struct request sreq ; 523 524 if (!capable(CAP_SYS_ADMIN)) 525 return -EPERM; 526 527 BUG_ON(lo->magic != LO_MAGIC); 528 529 /* Anyone capable of this syscall can do *real bad* things */ 530 dprintk(DBG_IOCTL, "%s: nbd_ioctl cmd=%s(0x%x) arg=%lu\n", 531 lo->disk->disk_name, ioctl_cmd_to_ascii(cmd), cmd, arg); 532 533 switch (cmd) { 534 case NBD_DISCONNECT: 535 printk(KERN_INFO "%s: NBD_DISCONNECT\n", lo->disk->disk_name); 536 sreq.cmd_type = REQ_TYPE_SPECIAL; 537 nbd_cmd(&sreq) = NBD_CMD_DISC; 538 /* 539 * Set these to sane values in case server implementation 540 * fails to check the request type first and also to keep 541 * debugging output cleaner. 542 */ 543 sreq.sector = 0; 544 sreq.nr_sectors = 0; 545 if (!lo->sock) 546 return -EINVAL; 547 mutex_lock(&lo->tx_lock); 548 nbd_send_req(lo, &sreq); 549 mutex_unlock(&lo->tx_lock); 550 return 0; 551 552 case NBD_CLEAR_SOCK: 553 error = 0; 554 mutex_lock(&lo->tx_lock); 555 lo->sock = NULL; 556 mutex_unlock(&lo->tx_lock); 557 file = lo->file; 558 lo->file = NULL; 559 nbd_clear_que(lo); 560 BUG_ON(!list_empty(&lo->queue_head)); 561 if (file) 562 fput(file); 563 return error; 564 case NBD_SET_SOCK: 565 if (lo->file) 566 return -EBUSY; 567 error = -EINVAL; 568 file = fget(arg); 569 if (file) { 570 inode = file->f_path.dentry->d_inode; 571 if (S_ISSOCK(inode->i_mode)) { 572 lo->file = file; 573 lo->sock = SOCKET_I(inode); 574 error = 0; 575 } else { 576 fput(file); 577 } 578 } 579 return error; 580 case NBD_SET_BLKSIZE: 581 lo->blksize = arg; 582 lo->bytesize &= ~(lo->blksize-1); 583 inode->i_bdev->bd_inode->i_size = lo->bytesize; 584 set_blocksize(inode->i_bdev, lo->blksize); 585 set_capacity(lo->disk, lo->bytesize >> 9); 586 return 0; 587 case NBD_SET_SIZE: 588 lo->bytesize = arg & ~(lo->blksize-1); 589 inode->i_bdev->bd_inode->i_size = lo->bytesize; 590 set_blocksize(inode->i_bdev, lo->blksize); 591 set_capacity(lo->disk, lo->bytesize >> 9); 592 return 0; 593 case NBD_SET_TIMEOUT: 594 lo->xmit_timeout = arg * HZ; 595 return 0; 596 case NBD_SET_SIZE_BLOCKS: 597 lo->bytesize = ((u64) arg) * lo->blksize; 598 inode->i_bdev->bd_inode->i_size = lo->bytesize; 599 set_blocksize(inode->i_bdev, lo->blksize); 600 set_capacity(lo->disk, lo->bytesize >> 9); 601 return 0; 602 case NBD_DO_IT: 603 if (!lo->file) 604 return -EINVAL; 605 error = nbd_do_it(lo); 606 if (error) 607 return error; 608 sock_shutdown(lo, 1); 609 file = lo->file; 610 lo->file = NULL; 611 nbd_clear_que(lo); 612 printk(KERN_WARNING "%s: queue cleared\n", lo->disk->disk_name); 613 if (file) 614 fput(file); 615 lo->bytesize = 0; 616 inode->i_bdev->bd_inode->i_size = 0; 617 set_capacity(lo->disk, 0); 618 return lo->harderror; 619 case NBD_CLEAR_QUE: 620 /* 621 * This is for compatibility only. The queue is always cleared 622 * by NBD_DO_IT or NBD_CLEAR_SOCK. 623 */ 624 BUG_ON(!lo->sock && !list_empty(&lo->queue_head)); 625 return 0; 626 case NBD_PRINT_DEBUG: 627 printk(KERN_INFO "%s: next = %p, prev = %p, head = %p\n", 628 inode->i_bdev->bd_disk->disk_name, 629 lo->queue_head.next, lo->queue_head.prev, 630 &lo->queue_head); 631 return 0; 632 } 633 return -EINVAL; 634 } 635 636 static struct block_device_operations nbd_fops = 637 { 638 .owner = THIS_MODULE, 639 .ioctl = nbd_ioctl, 640 }; 641 642 /* 643 * And here should be modules and kernel interface 644 * (Just smiley confuses emacs :-) 645 */ 646 647 static int __init nbd_init(void) 648 { 649 int err = -ENOMEM; 650 int i; 651 652 BUILD_BUG_ON(sizeof(struct nbd_request) != 28); 653 654 if (nbds_max > MAX_NBD) { 655 printk(KERN_CRIT "nbd: cannot allocate more than %u nbds; %u requested.\n", MAX_NBD, 656 nbds_max); 657 return -EINVAL; 658 } 659 660 for (i = 0; i < nbds_max; i++) { 661 struct gendisk *disk = alloc_disk(1); 662 if (!disk) 663 goto out; 664 nbd_dev[i].disk = disk; 665 /* 666 * The new linux 2.5 block layer implementation requires 667 * every gendisk to have its very own request_queue struct. 668 * These structs are big so we dynamically allocate them. 669 */ 670 disk->queue = blk_init_queue(do_nbd_request, &nbd_lock); 671 if (!disk->queue) { 672 put_disk(disk); 673 goto out; 674 } 675 } 676 677 if (register_blkdev(NBD_MAJOR, "nbd")) { 678 err = -EIO; 679 goto out; 680 } 681 682 printk(KERN_INFO "nbd: registered device at major %d\n", NBD_MAJOR); 683 dprintk(DBG_INIT, "nbd: debugflags=0x%x\n", debugflags); 684 685 for (i = 0; i < nbds_max; i++) { 686 struct gendisk *disk = nbd_dev[i].disk; 687 nbd_dev[i].file = NULL; 688 nbd_dev[i].magic = LO_MAGIC; 689 nbd_dev[i].flags = 0; 690 spin_lock_init(&nbd_dev[i].queue_lock); 691 INIT_LIST_HEAD(&nbd_dev[i].queue_head); 692 mutex_init(&nbd_dev[i].tx_lock); 693 init_waitqueue_head(&nbd_dev[i].active_wq); 694 nbd_dev[i].blksize = 1024; 695 nbd_dev[i].bytesize = 0; 696 disk->major = NBD_MAJOR; 697 disk->first_minor = i; 698 disk->fops = &nbd_fops; 699 disk->private_data = &nbd_dev[i]; 700 disk->flags |= GENHD_FL_SUPPRESS_PARTITION_INFO; 701 sprintf(disk->disk_name, "nbd%d", i); 702 set_capacity(disk, 0); 703 add_disk(disk); 704 } 705 706 return 0; 707 out: 708 while (i--) { 709 blk_cleanup_queue(nbd_dev[i].disk->queue); 710 put_disk(nbd_dev[i].disk); 711 } 712 return err; 713 } 714 715 static void __exit nbd_cleanup(void) 716 { 717 int i; 718 for (i = 0; i < nbds_max; i++) { 719 struct gendisk *disk = nbd_dev[i].disk; 720 nbd_dev[i].magic = 0; 721 if (disk) { 722 del_gendisk(disk); 723 blk_cleanup_queue(disk->queue); 724 put_disk(disk); 725 } 726 } 727 unregister_blkdev(NBD_MAJOR, "nbd"); 728 printk(KERN_INFO "nbd: unregistered device at major %d\n", NBD_MAJOR); 729 } 730 731 module_init(nbd_init); 732 module_exit(nbd_cleanup); 733 734 MODULE_DESCRIPTION("Network Block Device"); 735 MODULE_LICENSE("GPL"); 736 737 module_param(nbds_max, int, 0444); 738 MODULE_PARM_DESC(nbds_max, "How many network block devices to initialize."); 739 #ifndef NDEBUG 740 module_param(debugflags, int, 0644); 741 MODULE_PARM_DESC(debugflags, "flags for controlling debug output"); 742 #endif 743