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 u32 type; 234 235 if (req->cmd_type == REQ_TYPE_DRV_PRIV) 236 type = NBD_CMD_DISC; 237 else if (req->cmd_flags & REQ_DISCARD) 238 type = NBD_CMD_TRIM; 239 else if (req->cmd_flags & REQ_FLUSH) 240 type = NBD_CMD_FLUSH; 241 else if (rq_data_dir(req) == WRITE) 242 type = NBD_CMD_WRITE; 243 else 244 type = NBD_CMD_READ; 245 246 memset(&request, 0, sizeof(request)); 247 request.magic = htonl(NBD_REQUEST_MAGIC); 248 request.type = htonl(type); 249 if (type != NBD_CMD_FLUSH && type != NBD_CMD_DISC) { 250 request.from = cpu_to_be64((u64)blk_rq_pos(req) << 9); 251 request.len = htonl(size); 252 } 253 memcpy(request.handle, &req, sizeof(req)); 254 255 dev_dbg(nbd_to_dev(nbd), "request %p: sending control (%s@%llu,%uB)\n", 256 req, nbdcmd_to_ascii(type), 257 (unsigned long long)blk_rq_pos(req) << 9, blk_rq_bytes(req)); 258 result = sock_xmit(nbd, 1, &request, sizeof(request), 259 (type == NBD_CMD_WRITE) ? MSG_MORE : 0); 260 if (result <= 0) { 261 dev_err(disk_to_dev(nbd->disk), 262 "Send control failed (result %d)\n", result); 263 return -EIO; 264 } 265 266 if (type == NBD_CMD_WRITE) { 267 struct req_iterator iter; 268 struct bio_vec bvec; 269 /* 270 * we are really probing at internals to determine 271 * whether to set MSG_MORE or not... 272 */ 273 rq_for_each_segment(bvec, req, iter) { 274 flags = 0; 275 if (!rq_iter_last(bvec, iter)) 276 flags = MSG_MORE; 277 dev_dbg(nbd_to_dev(nbd), "request %p: sending %d bytes data\n", 278 req, bvec.bv_len); 279 result = sock_send_bvec(nbd, &bvec, flags); 280 if (result <= 0) { 281 dev_err(disk_to_dev(nbd->disk), 282 "Send data failed (result %d)\n", 283 result); 284 return -EIO; 285 } 286 } 287 } 288 return 0; 289 } 290 291 static struct request *nbd_find_request(struct nbd_device *nbd, 292 struct request *xreq) 293 { 294 struct request *req, *tmp; 295 int err; 296 297 err = wait_event_interruptible(nbd->active_wq, nbd->active_req != xreq); 298 if (unlikely(err)) 299 return ERR_PTR(err); 300 301 spin_lock(&nbd->queue_lock); 302 list_for_each_entry_safe(req, tmp, &nbd->queue_head, queuelist) { 303 if (req != xreq) 304 continue; 305 list_del_init(&req->queuelist); 306 spin_unlock(&nbd->queue_lock); 307 return req; 308 } 309 spin_unlock(&nbd->queue_lock); 310 311 return ERR_PTR(-ENOENT); 312 } 313 314 static inline int sock_recv_bvec(struct nbd_device *nbd, struct bio_vec *bvec) 315 { 316 int result; 317 void *kaddr = kmap(bvec->bv_page); 318 result = sock_xmit(nbd, 0, kaddr + bvec->bv_offset, bvec->bv_len, 319 MSG_WAITALL); 320 kunmap(bvec->bv_page); 321 return result; 322 } 323 324 /* NULL returned = something went wrong, inform userspace */ 325 static struct request *nbd_read_stat(struct nbd_device *nbd) 326 { 327 int result; 328 struct nbd_reply reply; 329 struct request *req; 330 331 reply.magic = 0; 332 result = sock_xmit(nbd, 0, &reply, sizeof(reply), MSG_WAITALL); 333 if (result <= 0) { 334 dev_err(disk_to_dev(nbd->disk), 335 "Receive control failed (result %d)\n", result); 336 goto harderror; 337 } 338 339 if (ntohl(reply.magic) != NBD_REPLY_MAGIC) { 340 dev_err(disk_to_dev(nbd->disk), "Wrong magic (0x%lx)\n", 341 (unsigned long)ntohl(reply.magic)); 342 result = -EPROTO; 343 goto harderror; 344 } 345 346 req = nbd_find_request(nbd, *(struct request **)reply.handle); 347 if (IS_ERR(req)) { 348 result = PTR_ERR(req); 349 if (result != -ENOENT) 350 goto harderror; 351 352 dev_err(disk_to_dev(nbd->disk), "Unexpected reply (%p)\n", 353 reply.handle); 354 result = -EBADR; 355 goto harderror; 356 } 357 358 if (ntohl(reply.error)) { 359 dev_err(disk_to_dev(nbd->disk), "Other side returned error (%d)\n", 360 ntohl(reply.error)); 361 req->errors++; 362 return req; 363 } 364 365 dev_dbg(nbd_to_dev(nbd), "request %p: got reply\n", req); 366 if (rq_data_dir(req) != WRITE) { 367 struct req_iterator iter; 368 struct bio_vec bvec; 369 370 rq_for_each_segment(bvec, req, iter) { 371 result = sock_recv_bvec(nbd, &bvec); 372 if (result <= 0) { 373 dev_err(disk_to_dev(nbd->disk), "Receive data failed (result %d)\n", 374 result); 375 req->errors++; 376 return req; 377 } 378 dev_dbg(nbd_to_dev(nbd), "request %p: got %d bytes data\n", 379 req, bvec.bv_len); 380 } 381 } 382 return req; 383 harderror: 384 nbd->harderror = result; 385 return NULL; 386 } 387 388 static ssize_t pid_show(struct device *dev, 389 struct device_attribute *attr, char *buf) 390 { 391 struct gendisk *disk = dev_to_disk(dev); 392 393 return sprintf(buf, "%ld\n", 394 (long) ((struct nbd_device *)disk->private_data)->pid); 395 } 396 397 static struct device_attribute pid_attr = { 398 .attr = { .name = "pid", .mode = S_IRUGO}, 399 .show = pid_show, 400 }; 401 402 static int nbd_do_it(struct nbd_device *nbd) 403 { 404 struct request *req; 405 int ret; 406 407 BUG_ON(nbd->magic != NBD_MAGIC); 408 409 sk_set_memalloc(nbd->sock->sk); 410 nbd->pid = task_pid_nr(current); 411 ret = device_create_file(disk_to_dev(nbd->disk), &pid_attr); 412 if (ret) { 413 dev_err(disk_to_dev(nbd->disk), "device_create_file failed!\n"); 414 nbd->pid = 0; 415 return ret; 416 } 417 418 while ((req = nbd_read_stat(nbd)) != NULL) 419 nbd_end_request(nbd, req); 420 421 device_remove_file(disk_to_dev(nbd->disk), &pid_attr); 422 nbd->pid = 0; 423 return 0; 424 } 425 426 static void nbd_clear_que(struct nbd_device *nbd) 427 { 428 struct request *req; 429 430 BUG_ON(nbd->magic != NBD_MAGIC); 431 432 /* 433 * Because we have set nbd->sock to NULL under the tx_lock, all 434 * modifications to the list must have completed by now. For 435 * the same reason, the active_req must be NULL. 436 * 437 * As a consequence, we don't need to take the spin lock while 438 * purging the list here. 439 */ 440 BUG_ON(nbd->sock); 441 BUG_ON(nbd->active_req); 442 443 while (!list_empty(&nbd->queue_head)) { 444 req = list_entry(nbd->queue_head.next, struct request, 445 queuelist); 446 list_del_init(&req->queuelist); 447 req->errors++; 448 nbd_end_request(nbd, req); 449 } 450 451 while (!list_empty(&nbd->waiting_queue)) { 452 req = list_entry(nbd->waiting_queue.next, struct request, 453 queuelist); 454 list_del_init(&req->queuelist); 455 req->errors++; 456 nbd_end_request(nbd, req); 457 } 458 } 459 460 461 static void nbd_handle_req(struct nbd_device *nbd, struct request *req) 462 { 463 if (req->cmd_type != REQ_TYPE_FS) 464 goto error_out; 465 466 if (rq_data_dir(req) == WRITE && 467 (nbd->flags & NBD_FLAG_READ_ONLY)) { 468 dev_err(disk_to_dev(nbd->disk), 469 "Write on read-only\n"); 470 goto error_out; 471 } 472 473 req->errors = 0; 474 475 mutex_lock(&nbd->tx_lock); 476 if (unlikely(!nbd->sock)) { 477 mutex_unlock(&nbd->tx_lock); 478 dev_err(disk_to_dev(nbd->disk), 479 "Attempted send on closed socket\n"); 480 goto error_out; 481 } 482 483 nbd->active_req = req; 484 485 if (nbd_send_req(nbd, req) != 0) { 486 dev_err(disk_to_dev(nbd->disk), "Request send failed\n"); 487 req->errors++; 488 nbd_end_request(nbd, req); 489 } else { 490 spin_lock(&nbd->queue_lock); 491 list_add_tail(&req->queuelist, &nbd->queue_head); 492 spin_unlock(&nbd->queue_lock); 493 } 494 495 nbd->active_req = NULL; 496 mutex_unlock(&nbd->tx_lock); 497 wake_up_all(&nbd->active_wq); 498 499 return; 500 501 error_out: 502 req->errors++; 503 nbd_end_request(nbd, req); 504 } 505 506 static int nbd_thread(void *data) 507 { 508 struct nbd_device *nbd = data; 509 struct request *req; 510 511 set_user_nice(current, MIN_NICE); 512 while (!kthread_should_stop() || !list_empty(&nbd->waiting_queue)) { 513 /* wait for something to do */ 514 wait_event_interruptible(nbd->waiting_wq, 515 kthread_should_stop() || 516 !list_empty(&nbd->waiting_queue)); 517 518 /* extract request */ 519 if (list_empty(&nbd->waiting_queue)) 520 continue; 521 522 spin_lock_irq(&nbd->queue_lock); 523 req = list_entry(nbd->waiting_queue.next, struct request, 524 queuelist); 525 list_del_init(&req->queuelist); 526 spin_unlock_irq(&nbd->queue_lock); 527 528 /* handle request */ 529 nbd_handle_req(nbd, req); 530 } 531 return 0; 532 } 533 534 /* 535 * We always wait for result of write, for now. It would be nice to make it optional 536 * in future 537 * if ((rq_data_dir(req) == WRITE) && (nbd->flags & NBD_WRITE_NOCHK)) 538 * { printk( "Warning: Ignoring result!\n"); nbd_end_request( req ); } 539 */ 540 541 static void do_nbd_request(struct request_queue *q) 542 __releases(q->queue_lock) __acquires(q->queue_lock) 543 { 544 struct request *req; 545 546 while ((req = blk_fetch_request(q)) != NULL) { 547 struct nbd_device *nbd; 548 549 spin_unlock_irq(q->queue_lock); 550 551 nbd = req->rq_disk->private_data; 552 553 BUG_ON(nbd->magic != NBD_MAGIC); 554 555 dev_dbg(nbd_to_dev(nbd), "request %p: dequeued (flags=%x)\n", 556 req, req->cmd_type); 557 558 if (unlikely(!nbd->sock)) { 559 dev_err(disk_to_dev(nbd->disk), 560 "Attempted send on closed socket\n"); 561 req->errors++; 562 nbd_end_request(nbd, req); 563 spin_lock_irq(q->queue_lock); 564 continue; 565 } 566 567 spin_lock_irq(&nbd->queue_lock); 568 list_add_tail(&req->queuelist, &nbd->waiting_queue); 569 spin_unlock_irq(&nbd->queue_lock); 570 571 wake_up(&nbd->waiting_wq); 572 573 spin_lock_irq(q->queue_lock); 574 } 575 } 576 577 /* Must be called with tx_lock held */ 578 579 static int __nbd_ioctl(struct block_device *bdev, struct nbd_device *nbd, 580 unsigned int cmd, unsigned long arg) 581 { 582 switch (cmd) { 583 case NBD_DISCONNECT: { 584 struct request sreq; 585 586 dev_info(disk_to_dev(nbd->disk), "NBD_DISCONNECT\n"); 587 if (!nbd->sock) 588 return -EINVAL; 589 590 mutex_unlock(&nbd->tx_lock); 591 fsync_bdev(bdev); 592 mutex_lock(&nbd->tx_lock); 593 blk_rq_init(NULL, &sreq); 594 sreq.cmd_type = REQ_TYPE_DRV_PRIV; 595 596 /* Check again after getting mutex back. */ 597 if (!nbd->sock) 598 return -EINVAL; 599 600 nbd->disconnect = 1; 601 602 nbd_send_req(nbd, &sreq); 603 return 0; 604 } 605 606 case NBD_CLEAR_SOCK: { 607 struct socket *sock = nbd->sock; 608 nbd->sock = NULL; 609 nbd_clear_que(nbd); 610 BUG_ON(!list_empty(&nbd->queue_head)); 611 BUG_ON(!list_empty(&nbd->waiting_queue)); 612 kill_bdev(bdev); 613 if (sock) 614 sockfd_put(sock); 615 return 0; 616 } 617 618 case NBD_SET_SOCK: { 619 struct socket *sock; 620 int err; 621 if (nbd->sock) 622 return -EBUSY; 623 sock = sockfd_lookup(arg, &err); 624 if (sock) { 625 nbd->sock = sock; 626 if (max_part > 0) 627 bdev->bd_invalidated = 1; 628 nbd->disconnect = 0; /* we're connected now */ 629 return 0; 630 } 631 return -EINVAL; 632 } 633 634 case NBD_SET_BLKSIZE: 635 nbd->blksize = arg; 636 nbd->bytesize &= ~(nbd->blksize-1); 637 bdev->bd_inode->i_size = nbd->bytesize; 638 set_blocksize(bdev, nbd->blksize); 639 set_capacity(nbd->disk, nbd->bytesize >> 9); 640 return 0; 641 642 case NBD_SET_SIZE: 643 nbd->bytesize = arg & ~(nbd->blksize-1); 644 bdev->bd_inode->i_size = nbd->bytesize; 645 set_blocksize(bdev, nbd->blksize); 646 set_capacity(nbd->disk, nbd->bytesize >> 9); 647 return 0; 648 649 case NBD_SET_TIMEOUT: 650 nbd->xmit_timeout = arg * HZ; 651 return 0; 652 653 case NBD_SET_FLAGS: 654 nbd->flags = arg; 655 return 0; 656 657 case NBD_SET_SIZE_BLOCKS: 658 nbd->bytesize = ((u64) arg) * nbd->blksize; 659 bdev->bd_inode->i_size = nbd->bytesize; 660 set_blocksize(bdev, nbd->blksize); 661 set_capacity(nbd->disk, nbd->bytesize >> 9); 662 return 0; 663 664 case NBD_DO_IT: { 665 struct task_struct *thread; 666 struct socket *sock; 667 int error; 668 669 if (nbd->pid) 670 return -EBUSY; 671 if (!nbd->sock) 672 return -EINVAL; 673 674 mutex_unlock(&nbd->tx_lock); 675 676 if (nbd->flags & NBD_FLAG_READ_ONLY) 677 set_device_ro(bdev, true); 678 if (nbd->flags & NBD_FLAG_SEND_TRIM) 679 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, 680 nbd->disk->queue); 681 if (nbd->flags & NBD_FLAG_SEND_FLUSH) 682 blk_queue_flush(nbd->disk->queue, REQ_FLUSH); 683 else 684 blk_queue_flush(nbd->disk->queue, 0); 685 686 thread = kthread_run(nbd_thread, nbd, "%s", 687 nbd->disk->disk_name); 688 if (IS_ERR(thread)) { 689 mutex_lock(&nbd->tx_lock); 690 return PTR_ERR(thread); 691 } 692 693 error = nbd_do_it(nbd); 694 kthread_stop(thread); 695 696 mutex_lock(&nbd->tx_lock); 697 if (error) 698 return error; 699 sock_shutdown(nbd, 0); 700 sock = nbd->sock; 701 nbd->sock = NULL; 702 nbd_clear_que(nbd); 703 dev_warn(disk_to_dev(nbd->disk), "queue cleared\n"); 704 kill_bdev(bdev); 705 queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, nbd->disk->queue); 706 set_device_ro(bdev, false); 707 if (sock) 708 sockfd_put(sock); 709 nbd->flags = 0; 710 nbd->bytesize = 0; 711 bdev->bd_inode->i_size = 0; 712 set_capacity(nbd->disk, 0); 713 if (max_part > 0) 714 blkdev_reread_part(bdev); 715 if (nbd->disconnect) /* user requested, ignore socket errors */ 716 return 0; 717 return nbd->harderror; 718 } 719 720 case NBD_CLEAR_QUE: 721 /* 722 * This is for compatibility only. The queue is always cleared 723 * by NBD_DO_IT or NBD_CLEAR_SOCK. 724 */ 725 return 0; 726 727 case NBD_PRINT_DEBUG: 728 dev_info(disk_to_dev(nbd->disk), 729 "next = %p, prev = %p, head = %p\n", 730 nbd->queue_head.next, nbd->queue_head.prev, 731 &nbd->queue_head); 732 return 0; 733 } 734 return -ENOTTY; 735 } 736 737 static int nbd_ioctl(struct block_device *bdev, fmode_t mode, 738 unsigned int cmd, unsigned long arg) 739 { 740 struct nbd_device *nbd = bdev->bd_disk->private_data; 741 int error; 742 743 if (!capable(CAP_SYS_ADMIN)) 744 return -EPERM; 745 746 BUG_ON(nbd->magic != NBD_MAGIC); 747 748 mutex_lock(&nbd->tx_lock); 749 error = __nbd_ioctl(bdev, nbd, cmd, arg); 750 mutex_unlock(&nbd->tx_lock); 751 752 return error; 753 } 754 755 static const struct block_device_operations nbd_fops = 756 { 757 .owner = THIS_MODULE, 758 .ioctl = nbd_ioctl, 759 }; 760 761 /* 762 * And here should be modules and kernel interface 763 * (Just smiley confuses emacs :-) 764 */ 765 766 static int __init nbd_init(void) 767 { 768 int err = -ENOMEM; 769 int i; 770 int part_shift; 771 772 BUILD_BUG_ON(sizeof(struct nbd_request) != 28); 773 774 if (max_part < 0) { 775 printk(KERN_ERR "nbd: max_part must be >= 0\n"); 776 return -EINVAL; 777 } 778 779 part_shift = 0; 780 if (max_part > 0) { 781 part_shift = fls(max_part); 782 783 /* 784 * Adjust max_part according to part_shift as it is exported 785 * to user space so that user can know the max number of 786 * partition kernel should be able to manage. 787 * 788 * Note that -1 is required because partition 0 is reserved 789 * for the whole disk. 790 */ 791 max_part = (1UL << part_shift) - 1; 792 } 793 794 if ((1UL << part_shift) > DISK_MAX_PARTS) 795 return -EINVAL; 796 797 if (nbds_max > 1UL << (MINORBITS - part_shift)) 798 return -EINVAL; 799 800 nbd_dev = kcalloc(nbds_max, sizeof(*nbd_dev), GFP_KERNEL); 801 if (!nbd_dev) 802 return -ENOMEM; 803 804 for (i = 0; i < nbds_max; i++) { 805 struct gendisk *disk = alloc_disk(1 << part_shift); 806 if (!disk) 807 goto out; 808 nbd_dev[i].disk = disk; 809 /* 810 * The new linux 2.5 block layer implementation requires 811 * every gendisk to have its very own request_queue struct. 812 * These structs are big so we dynamically allocate them. 813 */ 814 disk->queue = blk_init_queue(do_nbd_request, &nbd_lock); 815 if (!disk->queue) { 816 put_disk(disk); 817 goto out; 818 } 819 /* 820 * Tell the block layer that we are not a rotational device 821 */ 822 queue_flag_set_unlocked(QUEUE_FLAG_NONROT, disk->queue); 823 queue_flag_clear_unlocked(QUEUE_FLAG_ADD_RANDOM, disk->queue); 824 disk->queue->limits.discard_granularity = 512; 825 disk->queue->limits.max_discard_sectors = UINT_MAX; 826 disk->queue->limits.discard_zeroes_data = 0; 827 blk_queue_max_hw_sectors(disk->queue, 65536); 828 disk->queue->limits.max_sectors = 256; 829 } 830 831 if (register_blkdev(NBD_MAJOR, "nbd")) { 832 err = -EIO; 833 goto out; 834 } 835 836 printk(KERN_INFO "nbd: registered device at major %d\n", NBD_MAJOR); 837 838 for (i = 0; i < nbds_max; i++) { 839 struct gendisk *disk = nbd_dev[i].disk; 840 nbd_dev[i].magic = NBD_MAGIC; 841 INIT_LIST_HEAD(&nbd_dev[i].waiting_queue); 842 spin_lock_init(&nbd_dev[i].queue_lock); 843 INIT_LIST_HEAD(&nbd_dev[i].queue_head); 844 mutex_init(&nbd_dev[i].tx_lock); 845 init_waitqueue_head(&nbd_dev[i].active_wq); 846 init_waitqueue_head(&nbd_dev[i].waiting_wq); 847 nbd_dev[i].blksize = 1024; 848 nbd_dev[i].bytesize = 0; 849 disk->major = NBD_MAJOR; 850 disk->first_minor = i << part_shift; 851 disk->fops = &nbd_fops; 852 disk->private_data = &nbd_dev[i]; 853 sprintf(disk->disk_name, "nbd%d", i); 854 set_capacity(disk, 0); 855 add_disk(disk); 856 } 857 858 return 0; 859 out: 860 while (i--) { 861 blk_cleanup_queue(nbd_dev[i].disk->queue); 862 put_disk(nbd_dev[i].disk); 863 } 864 kfree(nbd_dev); 865 return err; 866 } 867 868 static void __exit nbd_cleanup(void) 869 { 870 int i; 871 for (i = 0; i < nbds_max; i++) { 872 struct gendisk *disk = nbd_dev[i].disk; 873 nbd_dev[i].magic = 0; 874 if (disk) { 875 del_gendisk(disk); 876 blk_cleanup_queue(disk->queue); 877 put_disk(disk); 878 } 879 } 880 unregister_blkdev(NBD_MAJOR, "nbd"); 881 kfree(nbd_dev); 882 printk(KERN_INFO "nbd: unregistered device at major %d\n", NBD_MAJOR); 883 } 884 885 module_init(nbd_init); 886 module_exit(nbd_cleanup); 887 888 MODULE_DESCRIPTION("Network Block Device"); 889 MODULE_LICENSE("GPL"); 890 891 module_param(nbds_max, int, 0444); 892 MODULE_PARM_DESC(nbds_max, "number of network block devices to initialize (default: 16)"); 893 module_param(max_part, int, 0444); 894 MODULE_PARM_DESC(max_part, "number of partitions per device (default: 0)"); 895