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, 2008 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/mutex.h> 28 #include <linux/compiler.h> 29 #include <linux/err.h> 30 #include <linux/kernel.h> 31 #include <linux/slab.h> 32 #include <net/sock.h> 33 #include <linux/net.h> 34 #include <linux/kthread.h> 35 #include <linux/types.h> 36 37 #include <asm/uaccess.h> 38 #include <asm/types.h> 39 40 #include <linux/nbd.h> 41 42 struct nbd_device { 43 int flags; 44 int harderror; /* Code of hard error */ 45 struct socket * sock; /* If == NULL, device is not ready, yet */ 46 int magic; 47 48 spinlock_t queue_lock; 49 struct list_head queue_head; /* Requests waiting result */ 50 struct request *active_req; 51 wait_queue_head_t active_wq; 52 struct list_head waiting_queue; /* Requests to be sent */ 53 wait_queue_head_t waiting_wq; 54 55 struct mutex tx_lock; 56 struct gendisk *disk; 57 int blksize; 58 loff_t bytesize; 59 pid_t pid; /* pid of nbd-client, if attached */ 60 int xmit_timeout; 61 int disconnect; /* a disconnect has been requested by user */ 62 }; 63 64 #define NBD_MAGIC 0x68797548 65 66 static unsigned int nbds_max = 16; 67 static struct nbd_device *nbd_dev; 68 static int max_part; 69 70 /* 71 * Use just one lock (or at most 1 per NIC). Two arguments for this: 72 * 1. Each NIC is essentially a synchronization point for all servers 73 * accessed through that NIC so there's no need to have more locks 74 * than NICs anyway. 75 * 2. More locks lead to more "Dirty cache line bouncing" which will slow 76 * down each lock to the point where they're actually slower than just 77 * a single lock. 78 * Thanks go to Jens Axboe and Al Viro for their LKML emails explaining this! 79 */ 80 static DEFINE_SPINLOCK(nbd_lock); 81 82 static inline struct device *nbd_to_dev(struct nbd_device *nbd) 83 { 84 return disk_to_dev(nbd->disk); 85 } 86 87 static const char *nbdcmd_to_ascii(int cmd) 88 { 89 switch (cmd) { 90 case NBD_CMD_READ: return "read"; 91 case NBD_CMD_WRITE: return "write"; 92 case NBD_CMD_DISC: return "disconnect"; 93 case NBD_CMD_FLUSH: return "flush"; 94 case NBD_CMD_TRIM: return "trim/discard"; 95 } 96 return "invalid"; 97 } 98 99 static void nbd_end_request(struct nbd_device *nbd, struct request *req) 100 { 101 int error = req->errors ? -EIO : 0; 102 struct request_queue *q = req->q; 103 unsigned long flags; 104 105 dev_dbg(nbd_to_dev(nbd), "request %p: %s\n", req, 106 error ? "failed" : "done"); 107 108 spin_lock_irqsave(q->queue_lock, flags); 109 __blk_end_request_all(req, error); 110 spin_unlock_irqrestore(q->queue_lock, flags); 111 } 112 113 /* 114 * Forcibly shutdown the socket causing all listeners to error 115 */ 116 static void sock_shutdown(struct nbd_device *nbd, int lock) 117 { 118 if (lock) 119 mutex_lock(&nbd->tx_lock); 120 if (nbd->sock) { 121 dev_warn(disk_to_dev(nbd->disk), "shutting down socket\n"); 122 kernel_sock_shutdown(nbd->sock, SHUT_RDWR); 123 nbd->sock = NULL; 124 } 125 if (lock) 126 mutex_unlock(&nbd->tx_lock); 127 } 128 129 static void nbd_xmit_timeout(unsigned long arg) 130 { 131 struct task_struct *task = (struct task_struct *)arg; 132 133 printk(KERN_WARNING "nbd: killing hung xmit (%s, pid: %d)\n", 134 task->comm, task->pid); 135 force_sig(SIGKILL, task); 136 } 137 138 /* 139 * Send or receive packet. 140 */ 141 static int sock_xmit(struct nbd_device *nbd, int send, void *buf, int size, 142 int msg_flags) 143 { 144 struct socket *sock = nbd->sock; 145 int result; 146 struct msghdr msg; 147 struct kvec iov; 148 sigset_t blocked, oldset; 149 unsigned long pflags = current->flags; 150 151 if (unlikely(!sock)) { 152 dev_err(disk_to_dev(nbd->disk), 153 "Attempted %s on closed socket in sock_xmit\n", 154 (send ? "send" : "recv")); 155 return -EINVAL; 156 } 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 current->flags |= PF_MEMALLOC; 164 do { 165 sock->sk->sk_allocation = GFP_NOIO | __GFP_MEMALLOC; 166 iov.iov_base = buf; 167 iov.iov_len = size; 168 msg.msg_name = NULL; 169 msg.msg_namelen = 0; 170 msg.msg_control = NULL; 171 msg.msg_controllen = 0; 172 msg.msg_flags = msg_flags | MSG_NOSIGNAL; 173 174 if (send) { 175 struct timer_list ti; 176 177 if (nbd->xmit_timeout) { 178 init_timer(&ti); 179 ti.function = nbd_xmit_timeout; 180 ti.data = (unsigned long)current; 181 ti.expires = jiffies + nbd->xmit_timeout; 182 add_timer(&ti); 183 } 184 result = kernel_sendmsg(sock, &msg, &iov, 1, size); 185 if (nbd->xmit_timeout) 186 del_timer_sync(&ti); 187 } else 188 result = kernel_recvmsg(sock, &msg, &iov, 1, size, 189 msg.msg_flags); 190 191 if (signal_pending(current)) { 192 siginfo_t info; 193 printk(KERN_WARNING "nbd (pid %d: %s) got signal %d\n", 194 task_pid_nr(current), current->comm, 195 dequeue_signal_lock(current, ¤t->blocked, &info)); 196 result = -EINTR; 197 sock_shutdown(nbd, !send); 198 break; 199 } 200 201 if (result <= 0) { 202 if (result == 0) 203 result = -EPIPE; /* short read */ 204 break; 205 } 206 size -= result; 207 buf += result; 208 } while (size > 0); 209 210 sigprocmask(SIG_SETMASK, &oldset, NULL); 211 tsk_restore_flags(current, pflags, PF_MEMALLOC); 212 213 return result; 214 } 215 216 static inline int sock_send_bvec(struct nbd_device *nbd, struct bio_vec *bvec, 217 int flags) 218 { 219 int result; 220 void *kaddr = kmap(bvec->bv_page); 221 result = sock_xmit(nbd, 1, kaddr + bvec->bv_offset, 222 bvec->bv_len, flags); 223 kunmap(bvec->bv_page); 224 return result; 225 } 226 227 /* always call with the tx_lock held */ 228 static int nbd_send_req(struct nbd_device *nbd, struct request *req) 229 { 230 int result, flags; 231 struct nbd_request request; 232 unsigned long size = blk_rq_bytes(req); 233 234 memset(&request, 0, sizeof(request)); 235 request.magic = htonl(NBD_REQUEST_MAGIC); 236 request.type = htonl(nbd_cmd(req)); 237 238 if (nbd_cmd(req) != NBD_CMD_FLUSH && nbd_cmd(req) != NBD_CMD_DISC) { 239 request.from = cpu_to_be64((u64)blk_rq_pos(req) << 9); 240 request.len = htonl(size); 241 } 242 memcpy(request.handle, &req, sizeof(req)); 243 244 dev_dbg(nbd_to_dev(nbd), "request %p: sending control (%s@%llu,%uB)\n", 245 req, nbdcmd_to_ascii(nbd_cmd(req)), 246 (unsigned long long)blk_rq_pos(req) << 9, blk_rq_bytes(req)); 247 result = sock_xmit(nbd, 1, &request, sizeof(request), 248 (nbd_cmd(req) == NBD_CMD_WRITE) ? MSG_MORE : 0); 249 if (result <= 0) { 250 dev_err(disk_to_dev(nbd->disk), 251 "Send control failed (result %d)\n", result); 252 return -EIO; 253 } 254 255 if (nbd_cmd(req) == NBD_CMD_WRITE) { 256 struct req_iterator iter; 257 struct bio_vec bvec; 258 /* 259 * we are really probing at internals to determine 260 * whether to set MSG_MORE or not... 261 */ 262 rq_for_each_segment(bvec, req, iter) { 263 flags = 0; 264 if (!rq_iter_last(bvec, iter)) 265 flags = MSG_MORE; 266 dev_dbg(nbd_to_dev(nbd), "request %p: sending %d bytes data\n", 267 req, bvec.bv_len); 268 result = sock_send_bvec(nbd, &bvec, flags); 269 if (result <= 0) { 270 dev_err(disk_to_dev(nbd->disk), 271 "Send data failed (result %d)\n", 272 result); 273 return -EIO; 274 } 275 } 276 } 277 return 0; 278 } 279 280 static struct request *nbd_find_request(struct nbd_device *nbd, 281 struct request *xreq) 282 { 283 struct request *req, *tmp; 284 int err; 285 286 err = wait_event_interruptible(nbd->active_wq, nbd->active_req != xreq); 287 if (unlikely(err)) 288 return ERR_PTR(err); 289 290 spin_lock(&nbd->queue_lock); 291 list_for_each_entry_safe(req, tmp, &nbd->queue_head, queuelist) { 292 if (req != xreq) 293 continue; 294 list_del_init(&req->queuelist); 295 spin_unlock(&nbd->queue_lock); 296 return req; 297 } 298 spin_unlock(&nbd->queue_lock); 299 300 return ERR_PTR(-ENOENT); 301 } 302 303 static inline int sock_recv_bvec(struct nbd_device *nbd, struct bio_vec *bvec) 304 { 305 int result; 306 void *kaddr = kmap(bvec->bv_page); 307 result = sock_xmit(nbd, 0, kaddr + bvec->bv_offset, bvec->bv_len, 308 MSG_WAITALL); 309 kunmap(bvec->bv_page); 310 return result; 311 } 312 313 /* NULL returned = something went wrong, inform userspace */ 314 static struct request *nbd_read_stat(struct nbd_device *nbd) 315 { 316 int result; 317 struct nbd_reply reply; 318 struct request *req; 319 320 reply.magic = 0; 321 result = sock_xmit(nbd, 0, &reply, sizeof(reply), MSG_WAITALL); 322 if (result <= 0) { 323 dev_err(disk_to_dev(nbd->disk), 324 "Receive control failed (result %d)\n", result); 325 goto harderror; 326 } 327 328 if (ntohl(reply.magic) != NBD_REPLY_MAGIC) { 329 dev_err(disk_to_dev(nbd->disk), "Wrong magic (0x%lx)\n", 330 (unsigned long)ntohl(reply.magic)); 331 result = -EPROTO; 332 goto harderror; 333 } 334 335 req = nbd_find_request(nbd, *(struct request **)reply.handle); 336 if (IS_ERR(req)) { 337 result = PTR_ERR(req); 338 if (result != -ENOENT) 339 goto harderror; 340 341 dev_err(disk_to_dev(nbd->disk), "Unexpected reply (%p)\n", 342 reply.handle); 343 result = -EBADR; 344 goto harderror; 345 } 346 347 if (ntohl(reply.error)) { 348 dev_err(disk_to_dev(nbd->disk), "Other side returned error (%d)\n", 349 ntohl(reply.error)); 350 req->errors++; 351 return req; 352 } 353 354 dev_dbg(nbd_to_dev(nbd), "request %p: got reply\n", req); 355 if (nbd_cmd(req) == NBD_CMD_READ) { 356 struct req_iterator iter; 357 struct bio_vec bvec; 358 359 rq_for_each_segment(bvec, req, iter) { 360 result = sock_recv_bvec(nbd, &bvec); 361 if (result <= 0) { 362 dev_err(disk_to_dev(nbd->disk), "Receive data failed (result %d)\n", 363 result); 364 req->errors++; 365 return req; 366 } 367 dev_dbg(nbd_to_dev(nbd), "request %p: got %d bytes data\n", 368 req, bvec.bv_len); 369 } 370 } 371 return req; 372 harderror: 373 nbd->harderror = result; 374 return NULL; 375 } 376 377 static ssize_t pid_show(struct device *dev, 378 struct device_attribute *attr, char *buf) 379 { 380 struct gendisk *disk = dev_to_disk(dev); 381 382 return sprintf(buf, "%ld\n", 383 (long) ((struct nbd_device *)disk->private_data)->pid); 384 } 385 386 static struct device_attribute pid_attr = { 387 .attr = { .name = "pid", .mode = S_IRUGO}, 388 .show = pid_show, 389 }; 390 391 static int nbd_do_it(struct nbd_device *nbd) 392 { 393 struct request *req; 394 int ret; 395 396 BUG_ON(nbd->magic != NBD_MAGIC); 397 398 sk_set_memalloc(nbd->sock->sk); 399 nbd->pid = task_pid_nr(current); 400 ret = device_create_file(disk_to_dev(nbd->disk), &pid_attr); 401 if (ret) { 402 dev_err(disk_to_dev(nbd->disk), "device_create_file failed!\n"); 403 nbd->pid = 0; 404 return ret; 405 } 406 407 while ((req = nbd_read_stat(nbd)) != NULL) 408 nbd_end_request(nbd, req); 409 410 device_remove_file(disk_to_dev(nbd->disk), &pid_attr); 411 nbd->pid = 0; 412 return 0; 413 } 414 415 static void nbd_clear_que(struct nbd_device *nbd) 416 { 417 struct request *req; 418 419 BUG_ON(nbd->magic != NBD_MAGIC); 420 421 /* 422 * Because we have set nbd->sock to NULL under the tx_lock, all 423 * modifications to the list must have completed by now. For 424 * the same reason, the active_req must be NULL. 425 * 426 * As a consequence, we don't need to take the spin lock while 427 * purging the list here. 428 */ 429 BUG_ON(nbd->sock); 430 BUG_ON(nbd->active_req); 431 432 while (!list_empty(&nbd->queue_head)) { 433 req = list_entry(nbd->queue_head.next, struct request, 434 queuelist); 435 list_del_init(&req->queuelist); 436 req->errors++; 437 nbd_end_request(nbd, req); 438 } 439 440 while (!list_empty(&nbd->waiting_queue)) { 441 req = list_entry(nbd->waiting_queue.next, struct request, 442 queuelist); 443 list_del_init(&req->queuelist); 444 req->errors++; 445 nbd_end_request(nbd, req); 446 } 447 } 448 449 450 static void nbd_handle_req(struct nbd_device *nbd, struct request *req) 451 { 452 if (req->cmd_type != REQ_TYPE_FS) 453 goto error_out; 454 455 nbd_cmd(req) = NBD_CMD_READ; 456 if (rq_data_dir(req) == WRITE) { 457 if ((req->cmd_flags & REQ_DISCARD)) { 458 WARN_ON(!(nbd->flags & NBD_FLAG_SEND_TRIM)); 459 nbd_cmd(req) = NBD_CMD_TRIM; 460 } else 461 nbd_cmd(req) = NBD_CMD_WRITE; 462 if (nbd->flags & NBD_FLAG_READ_ONLY) { 463 dev_err(disk_to_dev(nbd->disk), 464 "Write on read-only\n"); 465 goto error_out; 466 } 467 } 468 469 if (req->cmd_flags & REQ_FLUSH) { 470 BUG_ON(unlikely(blk_rq_sectors(req))); 471 nbd_cmd(req) = NBD_CMD_FLUSH; 472 } 473 474 req->errors = 0; 475 476 mutex_lock(&nbd->tx_lock); 477 if (unlikely(!nbd->sock)) { 478 mutex_unlock(&nbd->tx_lock); 479 dev_err(disk_to_dev(nbd->disk), 480 "Attempted send on closed socket\n"); 481 goto error_out; 482 } 483 484 nbd->active_req = req; 485 486 if (nbd_send_req(nbd, req) != 0) { 487 dev_err(disk_to_dev(nbd->disk), "Request send failed\n"); 488 req->errors++; 489 nbd_end_request(nbd, req); 490 } else { 491 spin_lock(&nbd->queue_lock); 492 list_add_tail(&req->queuelist, &nbd->queue_head); 493 spin_unlock(&nbd->queue_lock); 494 } 495 496 nbd->active_req = NULL; 497 mutex_unlock(&nbd->tx_lock); 498 wake_up_all(&nbd->active_wq); 499 500 return; 501 502 error_out: 503 req->errors++; 504 nbd_end_request(nbd, req); 505 } 506 507 static int nbd_thread(void *data) 508 { 509 struct nbd_device *nbd = data; 510 struct request *req; 511 512 set_user_nice(current, MIN_NICE); 513 while (!kthread_should_stop() || !list_empty(&nbd->waiting_queue)) { 514 /* wait for something to do */ 515 wait_event_interruptible(nbd->waiting_wq, 516 kthread_should_stop() || 517 !list_empty(&nbd->waiting_queue)); 518 519 /* extract request */ 520 if (list_empty(&nbd->waiting_queue)) 521 continue; 522 523 spin_lock_irq(&nbd->queue_lock); 524 req = list_entry(nbd->waiting_queue.next, struct request, 525 queuelist); 526 list_del_init(&req->queuelist); 527 spin_unlock_irq(&nbd->queue_lock); 528 529 /* handle request */ 530 nbd_handle_req(nbd, req); 531 } 532 return 0; 533 } 534 535 /* 536 * We always wait for result of write, for now. It would be nice to make it optional 537 * in future 538 * if ((rq_data_dir(req) == WRITE) && (nbd->flags & NBD_WRITE_NOCHK)) 539 * { printk( "Warning: Ignoring result!\n"); nbd_end_request( req ); } 540 */ 541 542 static void do_nbd_request(struct request_queue *q) 543 __releases(q->queue_lock) __acquires(q->queue_lock) 544 { 545 struct request *req; 546 547 while ((req = blk_fetch_request(q)) != NULL) { 548 struct nbd_device *nbd; 549 550 spin_unlock_irq(q->queue_lock); 551 552 nbd = req->rq_disk->private_data; 553 554 BUG_ON(nbd->magic != NBD_MAGIC); 555 556 dev_dbg(nbd_to_dev(nbd), "request %p: dequeued (flags=%x)\n", 557 req, req->cmd_type); 558 559 if (unlikely(!nbd->sock)) { 560 dev_err(disk_to_dev(nbd->disk), 561 "Attempted send on closed socket\n"); 562 req->errors++; 563 nbd_end_request(nbd, req); 564 spin_lock_irq(q->queue_lock); 565 continue; 566 } 567 568 spin_lock_irq(&nbd->queue_lock); 569 list_add_tail(&req->queuelist, &nbd->waiting_queue); 570 spin_unlock_irq(&nbd->queue_lock); 571 572 wake_up(&nbd->waiting_wq); 573 574 spin_lock_irq(q->queue_lock); 575 } 576 } 577 578 /* Must be called with tx_lock held */ 579 580 static int __nbd_ioctl(struct block_device *bdev, struct nbd_device *nbd, 581 unsigned int cmd, unsigned long arg) 582 { 583 switch (cmd) { 584 case NBD_DISCONNECT: { 585 struct request sreq; 586 587 dev_info(disk_to_dev(nbd->disk), "NBD_DISCONNECT\n"); 588 if (!nbd->sock) 589 return -EINVAL; 590 591 mutex_unlock(&nbd->tx_lock); 592 fsync_bdev(bdev); 593 mutex_lock(&nbd->tx_lock); 594 blk_rq_init(NULL, &sreq); 595 sreq.cmd_type = REQ_TYPE_SPECIAL; 596 nbd_cmd(&sreq) = NBD_CMD_DISC; 597 598 /* Check again after getting mutex back. */ 599 if (!nbd->sock) 600 return -EINVAL; 601 602 nbd->disconnect = 1; 603 604 nbd_send_req(nbd, &sreq); 605 return 0; 606 } 607 608 case NBD_CLEAR_SOCK: { 609 struct socket *sock = nbd->sock; 610 nbd->sock = NULL; 611 nbd_clear_que(nbd); 612 BUG_ON(!list_empty(&nbd->queue_head)); 613 BUG_ON(!list_empty(&nbd->waiting_queue)); 614 kill_bdev(bdev); 615 if (sock) 616 sockfd_put(sock); 617 return 0; 618 } 619 620 case NBD_SET_SOCK: { 621 struct socket *sock; 622 int err; 623 if (nbd->sock) 624 return -EBUSY; 625 sock = sockfd_lookup(arg, &err); 626 if (sock) { 627 nbd->sock = sock; 628 if (max_part > 0) 629 bdev->bd_invalidated = 1; 630 nbd->disconnect = 0; /* we're connected now */ 631 return 0; 632 } 633 return -EINVAL; 634 } 635 636 case NBD_SET_BLKSIZE: 637 nbd->blksize = arg; 638 nbd->bytesize &= ~(nbd->blksize-1); 639 bdev->bd_inode->i_size = nbd->bytesize; 640 set_blocksize(bdev, nbd->blksize); 641 set_capacity(nbd->disk, nbd->bytesize >> 9); 642 return 0; 643 644 case NBD_SET_SIZE: 645 nbd->bytesize = arg & ~(nbd->blksize-1); 646 bdev->bd_inode->i_size = nbd->bytesize; 647 set_blocksize(bdev, nbd->blksize); 648 set_capacity(nbd->disk, nbd->bytesize >> 9); 649 return 0; 650 651 case NBD_SET_TIMEOUT: 652 nbd->xmit_timeout = arg * HZ; 653 return 0; 654 655 case NBD_SET_FLAGS: 656 nbd->flags = arg; 657 return 0; 658 659 case NBD_SET_SIZE_BLOCKS: 660 nbd->bytesize = ((u64) arg) * nbd->blksize; 661 bdev->bd_inode->i_size = nbd->bytesize; 662 set_blocksize(bdev, nbd->blksize); 663 set_capacity(nbd->disk, nbd->bytesize >> 9); 664 return 0; 665 666 case NBD_DO_IT: { 667 struct task_struct *thread; 668 struct socket *sock; 669 int error; 670 671 if (nbd->pid) 672 return -EBUSY; 673 if (!nbd->sock) 674 return -EINVAL; 675 676 mutex_unlock(&nbd->tx_lock); 677 678 if (nbd->flags & NBD_FLAG_READ_ONLY) 679 set_device_ro(bdev, true); 680 if (nbd->flags & NBD_FLAG_SEND_TRIM) 681 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, 682 nbd->disk->queue); 683 if (nbd->flags & NBD_FLAG_SEND_FLUSH) 684 blk_queue_flush(nbd->disk->queue, REQ_FLUSH); 685 else 686 blk_queue_flush(nbd->disk->queue, 0); 687 688 thread = kthread_run(nbd_thread, nbd, "%s", 689 nbd->disk->disk_name); 690 if (IS_ERR(thread)) { 691 mutex_lock(&nbd->tx_lock); 692 return PTR_ERR(thread); 693 } 694 695 error = nbd_do_it(nbd); 696 kthread_stop(thread); 697 698 mutex_lock(&nbd->tx_lock); 699 if (error) 700 return error; 701 sock_shutdown(nbd, 0); 702 sock = nbd->sock; 703 nbd->sock = NULL; 704 nbd_clear_que(nbd); 705 dev_warn(disk_to_dev(nbd->disk), "queue cleared\n"); 706 kill_bdev(bdev); 707 queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, nbd->disk->queue); 708 set_device_ro(bdev, false); 709 if (sock) 710 sockfd_put(sock); 711 nbd->flags = 0; 712 nbd->bytesize = 0; 713 bdev->bd_inode->i_size = 0; 714 set_capacity(nbd->disk, 0); 715 if (max_part > 0) 716 ioctl_by_bdev(bdev, BLKRRPART, 0); 717 if (nbd->disconnect) /* user requested, ignore socket errors */ 718 return 0; 719 return nbd->harderror; 720 } 721 722 case NBD_CLEAR_QUE: 723 /* 724 * This is for compatibility only. The queue is always cleared 725 * by NBD_DO_IT or NBD_CLEAR_SOCK. 726 */ 727 return 0; 728 729 case NBD_PRINT_DEBUG: 730 dev_info(disk_to_dev(nbd->disk), 731 "next = %p, prev = %p, head = %p\n", 732 nbd->queue_head.next, nbd->queue_head.prev, 733 &nbd->queue_head); 734 return 0; 735 } 736 return -ENOTTY; 737 } 738 739 static int nbd_ioctl(struct block_device *bdev, fmode_t mode, 740 unsigned int cmd, unsigned long arg) 741 { 742 struct nbd_device *nbd = bdev->bd_disk->private_data; 743 int error; 744 745 if (!capable(CAP_SYS_ADMIN)) 746 return -EPERM; 747 748 BUG_ON(nbd->magic != NBD_MAGIC); 749 750 mutex_lock(&nbd->tx_lock); 751 error = __nbd_ioctl(bdev, nbd, cmd, arg); 752 mutex_unlock(&nbd->tx_lock); 753 754 return error; 755 } 756 757 static const struct block_device_operations nbd_fops = 758 { 759 .owner = THIS_MODULE, 760 .ioctl = nbd_ioctl, 761 }; 762 763 /* 764 * And here should be modules and kernel interface 765 * (Just smiley confuses emacs :-) 766 */ 767 768 static int __init nbd_init(void) 769 { 770 int err = -ENOMEM; 771 int i; 772 int part_shift; 773 774 BUILD_BUG_ON(sizeof(struct nbd_request) != 28); 775 776 if (max_part < 0) { 777 printk(KERN_ERR "nbd: max_part must be >= 0\n"); 778 return -EINVAL; 779 } 780 781 part_shift = 0; 782 if (max_part > 0) { 783 part_shift = fls(max_part); 784 785 /* 786 * Adjust max_part according to part_shift as it is exported 787 * to user space so that user can know the max number of 788 * partition kernel should be able to manage. 789 * 790 * Note that -1 is required because partition 0 is reserved 791 * for the whole disk. 792 */ 793 max_part = (1UL << part_shift) - 1; 794 } 795 796 if ((1UL << part_shift) > DISK_MAX_PARTS) 797 return -EINVAL; 798 799 if (nbds_max > 1UL << (MINORBITS - part_shift)) 800 return -EINVAL; 801 802 nbd_dev = kcalloc(nbds_max, sizeof(*nbd_dev), GFP_KERNEL); 803 if (!nbd_dev) 804 return -ENOMEM; 805 806 for (i = 0; i < nbds_max; i++) { 807 struct gendisk *disk = alloc_disk(1 << part_shift); 808 if (!disk) 809 goto out; 810 nbd_dev[i].disk = disk; 811 /* 812 * The new linux 2.5 block layer implementation requires 813 * every gendisk to have its very own request_queue struct. 814 * These structs are big so we dynamically allocate them. 815 */ 816 disk->queue = blk_init_queue(do_nbd_request, &nbd_lock); 817 if (!disk->queue) { 818 put_disk(disk); 819 goto out; 820 } 821 /* 822 * Tell the block layer that we are not a rotational device 823 */ 824 queue_flag_set_unlocked(QUEUE_FLAG_NONROT, disk->queue); 825 queue_flag_clear_unlocked(QUEUE_FLAG_ADD_RANDOM, disk->queue); 826 disk->queue->limits.discard_granularity = 512; 827 disk->queue->limits.max_discard_sectors = UINT_MAX; 828 disk->queue->limits.discard_zeroes_data = 0; 829 blk_queue_max_hw_sectors(disk->queue, 65536); 830 disk->queue->limits.max_sectors = 256; 831 } 832 833 if (register_blkdev(NBD_MAJOR, "nbd")) { 834 err = -EIO; 835 goto out; 836 } 837 838 printk(KERN_INFO "nbd: registered device at major %d\n", NBD_MAJOR); 839 840 for (i = 0; i < nbds_max; i++) { 841 struct gendisk *disk = nbd_dev[i].disk; 842 nbd_dev[i].magic = NBD_MAGIC; 843 INIT_LIST_HEAD(&nbd_dev[i].waiting_queue); 844 spin_lock_init(&nbd_dev[i].queue_lock); 845 INIT_LIST_HEAD(&nbd_dev[i].queue_head); 846 mutex_init(&nbd_dev[i].tx_lock); 847 init_waitqueue_head(&nbd_dev[i].active_wq); 848 init_waitqueue_head(&nbd_dev[i].waiting_wq); 849 nbd_dev[i].blksize = 1024; 850 nbd_dev[i].bytesize = 0; 851 disk->major = NBD_MAJOR; 852 disk->first_minor = i << part_shift; 853 disk->fops = &nbd_fops; 854 disk->private_data = &nbd_dev[i]; 855 sprintf(disk->disk_name, "nbd%d", i); 856 set_capacity(disk, 0); 857 add_disk(disk); 858 } 859 860 return 0; 861 out: 862 while (i--) { 863 blk_cleanup_queue(nbd_dev[i].disk->queue); 864 put_disk(nbd_dev[i].disk); 865 } 866 kfree(nbd_dev); 867 return err; 868 } 869 870 static void __exit nbd_cleanup(void) 871 { 872 int i; 873 for (i = 0; i < nbds_max; i++) { 874 struct gendisk *disk = nbd_dev[i].disk; 875 nbd_dev[i].magic = 0; 876 if (disk) { 877 del_gendisk(disk); 878 blk_cleanup_queue(disk->queue); 879 put_disk(disk); 880 } 881 } 882 unregister_blkdev(NBD_MAJOR, "nbd"); 883 kfree(nbd_dev); 884 printk(KERN_INFO "nbd: unregistered device at major %d\n", NBD_MAJOR); 885 } 886 887 module_init(nbd_init); 888 module_exit(nbd_cleanup); 889 890 MODULE_DESCRIPTION("Network Block Device"); 891 MODULE_LICENSE("GPL"); 892 893 module_param(nbds_max, int, 0444); 894 MODULE_PARM_DESC(nbds_max, "number of network block devices to initialize (default: 16)"); 895 module_param(max_part, int, 0444); 896 MODULE_PARM_DESC(max_part, "number of partitions per device (default: 0)"); 897