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 36 #include <asm/uaccess.h> 37 #include <asm/types.h> 38 39 #include <linux/nbd.h> 40 41 #define NBD_MAGIC 0x68797548 42 43 #ifdef NDEBUG 44 #define dprintk(flags, fmt...) 45 #else /* NDEBUG */ 46 #define dprintk(flags, fmt...) do { \ 47 if (debugflags & (flags)) printk(KERN_DEBUG fmt); \ 48 } while (0) 49 #define DBG_IOCTL 0x0004 50 #define DBG_INIT 0x0010 51 #define DBG_EXIT 0x0020 52 #define DBG_BLKDEV 0x0100 53 #define DBG_RX 0x0200 54 #define DBG_TX 0x0400 55 static unsigned int debugflags; 56 #endif /* NDEBUG */ 57 58 static unsigned int nbds_max = 16; 59 static struct nbd_device *nbd_dev; 60 static int max_part; 61 62 /* 63 * Use just one lock (or at most 1 per NIC). Two arguments for this: 64 * 1. Each NIC is essentially a synchronization point for all servers 65 * accessed through that NIC so there's no need to have more locks 66 * than NICs anyway. 67 * 2. More locks lead to more "Dirty cache line bouncing" which will slow 68 * down each lock to the point where they're actually slower than just 69 * a single lock. 70 * Thanks go to Jens Axboe and Al Viro for their LKML emails explaining this! 71 */ 72 static DEFINE_SPINLOCK(nbd_lock); 73 74 #ifndef NDEBUG 75 static const char *ioctl_cmd_to_ascii(int cmd) 76 { 77 switch (cmd) { 78 case NBD_SET_SOCK: return "set-sock"; 79 case NBD_SET_BLKSIZE: return "set-blksize"; 80 case NBD_SET_SIZE: return "set-size"; 81 case NBD_SET_TIMEOUT: return "set-timeout"; 82 case NBD_SET_FLAGS: return "set-flags"; 83 case NBD_DO_IT: return "do-it"; 84 case NBD_CLEAR_SOCK: return "clear-sock"; 85 case NBD_CLEAR_QUE: return "clear-que"; 86 case NBD_PRINT_DEBUG: return "print-debug"; 87 case NBD_SET_SIZE_BLOCKS: return "set-size-blocks"; 88 case NBD_DISCONNECT: return "disconnect"; 89 case BLKROSET: return "set-read-only"; 90 case BLKFLSBUF: return "flush-buffer-cache"; 91 } 92 return "unknown"; 93 } 94 95 static const char *nbdcmd_to_ascii(int cmd) 96 { 97 switch (cmd) { 98 case NBD_CMD_READ: return "read"; 99 case NBD_CMD_WRITE: return "write"; 100 case NBD_CMD_DISC: return "disconnect"; 101 case NBD_CMD_TRIM: return "trim/discard"; 102 } 103 return "invalid"; 104 } 105 #endif /* NDEBUG */ 106 107 static void nbd_end_request(struct request *req) 108 { 109 int error = req->errors ? -EIO : 0; 110 struct request_queue *q = req->q; 111 unsigned long flags; 112 113 dprintk(DBG_BLKDEV, "%s: request %p: %s\n", req->rq_disk->disk_name, 114 req, error ? "failed" : "done"); 115 116 spin_lock_irqsave(q->queue_lock, flags); 117 __blk_end_request_all(req, error); 118 spin_unlock_irqrestore(q->queue_lock, flags); 119 } 120 121 static void sock_shutdown(struct nbd_device *nbd, int lock) 122 { 123 /* Forcibly shutdown the socket causing all listeners 124 * to error 125 * 126 * FIXME: This code is duplicated from sys_shutdown, but 127 * there should be a more generic interface rather than 128 * calling socket ops directly here */ 129 if (lock) 130 mutex_lock(&nbd->tx_lock); 131 if (nbd->sock) { 132 dev_warn(disk_to_dev(nbd->disk), "shutting down socket\n"); 133 kernel_sock_shutdown(nbd->sock, SHUT_RDWR); 134 nbd->sock = NULL; 135 } 136 if (lock) 137 mutex_unlock(&nbd->tx_lock); 138 } 139 140 static void nbd_xmit_timeout(unsigned long arg) 141 { 142 struct task_struct *task = (struct task_struct *)arg; 143 144 printk(KERN_WARNING "nbd: killing hung xmit (%s, pid: %d)\n", 145 task->comm, task->pid); 146 force_sig(SIGKILL, task); 147 } 148 149 /* 150 * Send or receive packet. 151 */ 152 static int sock_xmit(struct nbd_device *nbd, int send, void *buf, int size, 153 int msg_flags) 154 { 155 struct socket *sock = nbd->sock; 156 int result; 157 struct msghdr msg; 158 struct kvec iov; 159 sigset_t blocked, oldset; 160 unsigned long pflags = current->flags; 161 162 if (unlikely(!sock)) { 163 dev_err(disk_to_dev(nbd->disk), 164 "Attempted %s on closed socket in sock_xmit\n", 165 (send ? "send" : "recv")); 166 return -EINVAL; 167 } 168 169 /* Allow interception of SIGKILL only 170 * Don't allow other signals to interrupt the transmission */ 171 siginitsetinv(&blocked, sigmask(SIGKILL)); 172 sigprocmask(SIG_SETMASK, &blocked, &oldset); 173 174 current->flags |= PF_MEMALLOC; 175 do { 176 sock->sk->sk_allocation = GFP_NOIO | __GFP_MEMALLOC; 177 iov.iov_base = buf; 178 iov.iov_len = size; 179 msg.msg_name = NULL; 180 msg.msg_namelen = 0; 181 msg.msg_control = NULL; 182 msg.msg_controllen = 0; 183 msg.msg_flags = msg_flags | MSG_NOSIGNAL; 184 185 if (send) { 186 struct timer_list ti; 187 188 if (nbd->xmit_timeout) { 189 init_timer(&ti); 190 ti.function = nbd_xmit_timeout; 191 ti.data = (unsigned long)current; 192 ti.expires = jiffies + nbd->xmit_timeout; 193 add_timer(&ti); 194 } 195 result = kernel_sendmsg(sock, &msg, &iov, 1, size); 196 if (nbd->xmit_timeout) 197 del_timer_sync(&ti); 198 } else 199 result = kernel_recvmsg(sock, &msg, &iov, 1, size, 200 msg.msg_flags); 201 202 if (signal_pending(current)) { 203 siginfo_t info; 204 printk(KERN_WARNING "nbd (pid %d: %s) got signal %d\n", 205 task_pid_nr(current), current->comm, 206 dequeue_signal_lock(current, ¤t->blocked, &info)); 207 result = -EINTR; 208 sock_shutdown(nbd, !send); 209 break; 210 } 211 212 if (result <= 0) { 213 if (result == 0) 214 result = -EPIPE; /* short read */ 215 break; 216 } 217 size -= result; 218 buf += result; 219 } while (size > 0); 220 221 sigprocmask(SIG_SETMASK, &oldset, NULL); 222 tsk_restore_flags(current, pflags, PF_MEMALLOC); 223 224 return result; 225 } 226 227 static inline int sock_send_bvec(struct nbd_device *nbd, struct bio_vec *bvec, 228 int flags) 229 { 230 int result; 231 void *kaddr = kmap(bvec->bv_page); 232 result = sock_xmit(nbd, 1, kaddr + bvec->bv_offset, 233 bvec->bv_len, flags); 234 kunmap(bvec->bv_page); 235 return result; 236 } 237 238 /* always call with the tx_lock held */ 239 static int nbd_send_req(struct nbd_device *nbd, struct request *req) 240 { 241 int result, flags; 242 struct nbd_request request; 243 unsigned long size = blk_rq_bytes(req); 244 245 request.magic = htonl(NBD_REQUEST_MAGIC); 246 request.type = htonl(nbd_cmd(req)); 247 request.from = cpu_to_be64((u64)blk_rq_pos(req) << 9); 248 request.len = htonl(size); 249 memcpy(request.handle, &req, sizeof(req)); 250 251 dprintk(DBG_TX, "%s: request %p: sending control (%s@%llu,%uB)\n", 252 nbd->disk->disk_name, req, 253 nbdcmd_to_ascii(nbd_cmd(req)), 254 (unsigned long long)blk_rq_pos(req) << 9, 255 blk_rq_bytes(req)); 256 result = sock_xmit(nbd, 1, &request, sizeof(request), 257 (nbd_cmd(req) == NBD_CMD_WRITE) ? MSG_MORE : 0); 258 if (result <= 0) { 259 dev_err(disk_to_dev(nbd->disk), 260 "Send control failed (result %d)\n", result); 261 goto error_out; 262 } 263 264 if (nbd_cmd(req) == NBD_CMD_WRITE) { 265 struct req_iterator iter; 266 struct bio_vec *bvec; 267 /* 268 * we are really probing at internals to determine 269 * whether to set MSG_MORE or not... 270 */ 271 rq_for_each_segment(bvec, req, iter) { 272 flags = 0; 273 if (!rq_iter_last(req, iter)) 274 flags = MSG_MORE; 275 dprintk(DBG_TX, "%s: request %p: sending %d bytes data\n", 276 nbd->disk->disk_name, req, bvec->bv_len); 277 result = sock_send_bvec(nbd, bvec, flags); 278 if (result <= 0) { 279 dev_err(disk_to_dev(nbd->disk), 280 "Send data failed (result %d)\n", 281 result); 282 goto error_out; 283 } 284 } 285 } 286 return 0; 287 288 error_out: 289 return -EIO; 290 } 291 292 static struct request *nbd_find_request(struct nbd_device *nbd, 293 struct request *xreq) 294 { 295 struct request *req, *tmp; 296 int err; 297 298 err = wait_event_interruptible(nbd->active_wq, nbd->active_req != xreq); 299 if (unlikely(err)) 300 goto out; 301 302 spin_lock(&nbd->queue_lock); 303 list_for_each_entry_safe(req, tmp, &nbd->queue_head, queuelist) { 304 if (req != xreq) 305 continue; 306 list_del_init(&req->queuelist); 307 spin_unlock(&nbd->queue_lock); 308 return req; 309 } 310 spin_unlock(&nbd->queue_lock); 311 312 err = -ENOENT; 313 314 out: 315 return ERR_PTR(err); 316 } 317 318 static inline int sock_recv_bvec(struct nbd_device *nbd, struct bio_vec *bvec) 319 { 320 int result; 321 void *kaddr = kmap(bvec->bv_page); 322 result = sock_xmit(nbd, 0, kaddr + bvec->bv_offset, bvec->bv_len, 323 MSG_WAITALL); 324 kunmap(bvec->bv_page); 325 return result; 326 } 327 328 /* NULL returned = something went wrong, inform userspace */ 329 static struct request *nbd_read_stat(struct nbd_device *nbd) 330 { 331 int result; 332 struct nbd_reply reply; 333 struct request *req; 334 335 reply.magic = 0; 336 result = sock_xmit(nbd, 0, &reply, sizeof(reply), MSG_WAITALL); 337 if (result <= 0) { 338 dev_err(disk_to_dev(nbd->disk), 339 "Receive control failed (result %d)\n", result); 340 goto harderror; 341 } 342 343 if (ntohl(reply.magic) != NBD_REPLY_MAGIC) { 344 dev_err(disk_to_dev(nbd->disk), "Wrong magic (0x%lx)\n", 345 (unsigned long)ntohl(reply.magic)); 346 result = -EPROTO; 347 goto harderror; 348 } 349 350 req = nbd_find_request(nbd, *(struct request **)reply.handle); 351 if (IS_ERR(req)) { 352 result = PTR_ERR(req); 353 if (result != -ENOENT) 354 goto harderror; 355 356 dev_err(disk_to_dev(nbd->disk), "Unexpected reply (%p)\n", 357 reply.handle); 358 result = -EBADR; 359 goto harderror; 360 } 361 362 if (ntohl(reply.error)) { 363 dev_err(disk_to_dev(nbd->disk), "Other side returned error (%d)\n", 364 ntohl(reply.error)); 365 req->errors++; 366 return req; 367 } 368 369 dprintk(DBG_RX, "%s: request %p: got reply\n", 370 nbd->disk->disk_name, req); 371 if (nbd_cmd(req) == NBD_CMD_READ) { 372 struct req_iterator iter; 373 struct bio_vec *bvec; 374 375 rq_for_each_segment(bvec, req, iter) { 376 result = sock_recv_bvec(nbd, bvec); 377 if (result <= 0) { 378 dev_err(disk_to_dev(nbd->disk), "Receive data failed (result %d)\n", 379 result); 380 req->errors++; 381 return req; 382 } 383 dprintk(DBG_RX, "%s: request %p: got %d bytes data\n", 384 nbd->disk->disk_name, req, bvec->bv_len); 385 } 386 } 387 return req; 388 harderror: 389 nbd->harderror = result; 390 return NULL; 391 } 392 393 static ssize_t pid_show(struct device *dev, 394 struct device_attribute *attr, char *buf) 395 { 396 struct gendisk *disk = dev_to_disk(dev); 397 398 return sprintf(buf, "%ld\n", 399 (long) ((struct nbd_device *)disk->private_data)->pid); 400 } 401 402 static struct device_attribute pid_attr = { 403 .attr = { .name = "pid", .mode = S_IRUGO}, 404 .show = pid_show, 405 }; 406 407 static int nbd_do_it(struct nbd_device *nbd) 408 { 409 struct request *req; 410 int ret; 411 412 BUG_ON(nbd->magic != NBD_MAGIC); 413 414 sk_set_memalloc(nbd->sock->sk); 415 nbd->pid = task_pid_nr(current); 416 ret = device_create_file(disk_to_dev(nbd->disk), &pid_attr); 417 if (ret) { 418 dev_err(disk_to_dev(nbd->disk), "device_create_file failed!\n"); 419 nbd->pid = 0; 420 return ret; 421 } 422 423 while ((req = nbd_read_stat(nbd)) != NULL) 424 nbd_end_request(req); 425 426 device_remove_file(disk_to_dev(nbd->disk), &pid_attr); 427 nbd->pid = 0; 428 return 0; 429 } 430 431 static void nbd_clear_que(struct nbd_device *nbd) 432 { 433 struct request *req; 434 435 BUG_ON(nbd->magic != NBD_MAGIC); 436 437 /* 438 * Because we have set nbd->sock to NULL under the tx_lock, all 439 * modifications to the list must have completed by now. For 440 * the same reason, the active_req must be NULL. 441 * 442 * As a consequence, we don't need to take the spin lock while 443 * purging the list here. 444 */ 445 BUG_ON(nbd->sock); 446 BUG_ON(nbd->active_req); 447 448 while (!list_empty(&nbd->queue_head)) { 449 req = list_entry(nbd->queue_head.next, struct request, 450 queuelist); 451 list_del_init(&req->queuelist); 452 req->errors++; 453 nbd_end_request(req); 454 } 455 456 while (!list_empty(&nbd->waiting_queue)) { 457 req = list_entry(nbd->waiting_queue.next, struct request, 458 queuelist); 459 list_del_init(&req->queuelist); 460 req->errors++; 461 nbd_end_request(req); 462 } 463 } 464 465 466 static void nbd_handle_req(struct nbd_device *nbd, struct request *req) 467 { 468 if (req->cmd_type != REQ_TYPE_FS) 469 goto error_out; 470 471 nbd_cmd(req) = NBD_CMD_READ; 472 if (rq_data_dir(req) == WRITE) { 473 if ((req->cmd_flags & REQ_DISCARD)) { 474 WARN_ON(!(nbd->flags & NBD_FLAG_SEND_TRIM)); 475 nbd_cmd(req) = NBD_CMD_TRIM; 476 } else 477 nbd_cmd(req) = NBD_CMD_WRITE; 478 if (nbd->flags & NBD_FLAG_READ_ONLY) { 479 dev_err(disk_to_dev(nbd->disk), 480 "Write on read-only\n"); 481 goto error_out; 482 } 483 } 484 485 req->errors = 0; 486 487 mutex_lock(&nbd->tx_lock); 488 if (unlikely(!nbd->sock)) { 489 mutex_unlock(&nbd->tx_lock); 490 dev_err(disk_to_dev(nbd->disk), 491 "Attempted send on closed socket\n"); 492 goto error_out; 493 } 494 495 nbd->active_req = req; 496 497 if (nbd_send_req(nbd, req) != 0) { 498 dev_err(disk_to_dev(nbd->disk), "Request send failed\n"); 499 req->errors++; 500 nbd_end_request(req); 501 } else { 502 spin_lock(&nbd->queue_lock); 503 list_add_tail(&req->queuelist, &nbd->queue_head); 504 spin_unlock(&nbd->queue_lock); 505 } 506 507 nbd->active_req = NULL; 508 mutex_unlock(&nbd->tx_lock); 509 wake_up_all(&nbd->active_wq); 510 511 return; 512 513 error_out: 514 req->errors++; 515 nbd_end_request(req); 516 } 517 518 static int nbd_thread(void *data) 519 { 520 struct nbd_device *nbd = data; 521 struct request *req; 522 523 set_user_nice(current, -20); 524 while (!kthread_should_stop() || !list_empty(&nbd->waiting_queue)) { 525 /* wait for something to do */ 526 wait_event_interruptible(nbd->waiting_wq, 527 kthread_should_stop() || 528 !list_empty(&nbd->waiting_queue)); 529 530 /* extract request */ 531 if (list_empty(&nbd->waiting_queue)) 532 continue; 533 534 spin_lock_irq(&nbd->queue_lock); 535 req = list_entry(nbd->waiting_queue.next, struct request, 536 queuelist); 537 list_del_init(&req->queuelist); 538 spin_unlock_irq(&nbd->queue_lock); 539 540 /* handle request */ 541 nbd_handle_req(nbd, req); 542 } 543 return 0; 544 } 545 546 /* 547 * We always wait for result of write, for now. It would be nice to make it optional 548 * in future 549 * if ((rq_data_dir(req) == WRITE) && (nbd->flags & NBD_WRITE_NOCHK)) 550 * { printk( "Warning: Ignoring result!\n"); nbd_end_request( req ); } 551 */ 552 553 static void do_nbd_request(struct request_queue *q) 554 { 555 struct request *req; 556 557 while ((req = blk_fetch_request(q)) != NULL) { 558 struct nbd_device *nbd; 559 560 spin_unlock_irq(q->queue_lock); 561 562 dprintk(DBG_BLKDEV, "%s: request %p: dequeued (flags=%x)\n", 563 req->rq_disk->disk_name, req, req->cmd_type); 564 565 nbd = req->rq_disk->private_data; 566 567 BUG_ON(nbd->magic != NBD_MAGIC); 568 569 if (unlikely(!nbd->sock)) { 570 dev_err(disk_to_dev(nbd->disk), 571 "Attempted send on closed socket\n"); 572 req->errors++; 573 nbd_end_request(req); 574 spin_lock_irq(q->queue_lock); 575 continue; 576 } 577 578 spin_lock_irq(&nbd->queue_lock); 579 list_add_tail(&req->queuelist, &nbd->waiting_queue); 580 spin_unlock_irq(&nbd->queue_lock); 581 582 wake_up(&nbd->waiting_wq); 583 584 spin_lock_irq(q->queue_lock); 585 } 586 } 587 588 /* Must be called with tx_lock held */ 589 590 static int __nbd_ioctl(struct block_device *bdev, struct nbd_device *nbd, 591 unsigned int cmd, unsigned long arg) 592 { 593 switch (cmd) { 594 case NBD_DISCONNECT: { 595 struct request sreq; 596 597 dev_info(disk_to_dev(nbd->disk), "NBD_DISCONNECT\n"); 598 599 blk_rq_init(NULL, &sreq); 600 sreq.cmd_type = REQ_TYPE_SPECIAL; 601 nbd_cmd(&sreq) = NBD_CMD_DISC; 602 if (!nbd->sock) 603 return -EINVAL; 604 nbd_send_req(nbd, &sreq); 605 return 0; 606 } 607 608 case NBD_CLEAR_SOCK: { 609 struct file *file; 610 611 nbd->sock = NULL; 612 file = nbd->file; 613 nbd->file = NULL; 614 nbd_clear_que(nbd); 615 BUG_ON(!list_empty(&nbd->queue_head)); 616 BUG_ON(!list_empty(&nbd->waiting_queue)); 617 if (file) 618 fput(file); 619 return 0; 620 } 621 622 case NBD_SET_SOCK: { 623 struct file *file; 624 if (nbd->file) 625 return -EBUSY; 626 file = fget(arg); 627 if (file) { 628 struct inode *inode = file->f_path.dentry->d_inode; 629 if (S_ISSOCK(inode->i_mode)) { 630 nbd->file = file; 631 nbd->sock = SOCKET_I(inode); 632 if (max_part > 0) 633 bdev->bd_invalidated = 1; 634 return 0; 635 } else { 636 fput(file); 637 } 638 } 639 return -EINVAL; 640 } 641 642 case NBD_SET_BLKSIZE: 643 nbd->blksize = arg; 644 nbd->bytesize &= ~(nbd->blksize-1); 645 bdev->bd_inode->i_size = nbd->bytesize; 646 set_blocksize(bdev, nbd->blksize); 647 set_capacity(nbd->disk, nbd->bytesize >> 9); 648 return 0; 649 650 case NBD_SET_SIZE: 651 nbd->bytesize = arg & ~(nbd->blksize-1); 652 bdev->bd_inode->i_size = nbd->bytesize; 653 set_blocksize(bdev, nbd->blksize); 654 set_capacity(nbd->disk, nbd->bytesize >> 9); 655 return 0; 656 657 case NBD_SET_TIMEOUT: 658 nbd->xmit_timeout = arg * HZ; 659 return 0; 660 661 case NBD_SET_FLAGS: 662 nbd->flags = arg; 663 return 0; 664 665 case NBD_SET_SIZE_BLOCKS: 666 nbd->bytesize = ((u64) arg) * nbd->blksize; 667 bdev->bd_inode->i_size = nbd->bytesize; 668 set_blocksize(bdev, nbd->blksize); 669 set_capacity(nbd->disk, nbd->bytesize >> 9); 670 return 0; 671 672 case NBD_DO_IT: { 673 struct task_struct *thread; 674 struct file *file; 675 int error; 676 677 if (nbd->pid) 678 return -EBUSY; 679 if (!nbd->file) 680 return -EINVAL; 681 682 mutex_unlock(&nbd->tx_lock); 683 684 if (nbd->flags & NBD_FLAG_SEND_TRIM) 685 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, 686 nbd->disk->queue); 687 688 thread = kthread_create(nbd_thread, nbd, nbd->disk->disk_name); 689 if (IS_ERR(thread)) { 690 mutex_lock(&nbd->tx_lock); 691 return PTR_ERR(thread); 692 } 693 wake_up_process(thread); 694 error = nbd_do_it(nbd); 695 kthread_stop(thread); 696 697 mutex_lock(&nbd->tx_lock); 698 if (error) 699 return error; 700 sock_shutdown(nbd, 0); 701 file = nbd->file; 702 nbd->file = NULL; 703 nbd_clear_que(nbd); 704 dev_warn(disk_to_dev(nbd->disk), "queue cleared\n"); 705 queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, nbd->disk->queue); 706 if (file) 707 fput(file); 708 nbd->bytesize = 0; 709 bdev->bd_inode->i_size = 0; 710 set_capacity(nbd->disk, 0); 711 if (max_part > 0) 712 ioctl_by_bdev(bdev, BLKRRPART, 0); 713 return nbd->harderror; 714 } 715 716 case NBD_CLEAR_QUE: 717 /* 718 * This is for compatibility only. The queue is always cleared 719 * by NBD_DO_IT or NBD_CLEAR_SOCK. 720 */ 721 BUG_ON(!nbd->sock && !list_empty(&nbd->queue_head)); 722 return 0; 723 724 case NBD_PRINT_DEBUG: 725 dev_info(disk_to_dev(nbd->disk), 726 "next = %p, prev = %p, head = %p\n", 727 nbd->queue_head.next, nbd->queue_head.prev, 728 &nbd->queue_head); 729 return 0; 730 } 731 return -ENOTTY; 732 } 733 734 static int nbd_ioctl(struct block_device *bdev, fmode_t mode, 735 unsigned int cmd, unsigned long arg) 736 { 737 struct nbd_device *nbd = bdev->bd_disk->private_data; 738 int error; 739 740 if (!capable(CAP_SYS_ADMIN)) 741 return -EPERM; 742 743 BUG_ON(nbd->magic != NBD_MAGIC); 744 745 /* Anyone capable of this syscall can do *real bad* things */ 746 dprintk(DBG_IOCTL, "%s: nbd_ioctl cmd=%s(0x%x) arg=%lu\n", 747 nbd->disk->disk_name, ioctl_cmd_to_ascii(cmd), cmd, arg); 748 749 mutex_lock(&nbd->tx_lock); 750 error = __nbd_ioctl(bdev, nbd, cmd, arg); 751 mutex_unlock(&nbd->tx_lock); 752 753 return error; 754 } 755 756 static const struct block_device_operations nbd_fops = 757 { 758 .owner = THIS_MODULE, 759 .ioctl = nbd_ioctl, 760 }; 761 762 /* 763 * And here should be modules and kernel interface 764 * (Just smiley confuses emacs :-) 765 */ 766 767 static int __init nbd_init(void) 768 { 769 int err = -ENOMEM; 770 int i; 771 int part_shift; 772 773 BUILD_BUG_ON(sizeof(struct nbd_request) != 28); 774 775 if (max_part < 0) { 776 printk(KERN_ERR "nbd: max_part must be >= 0\n"); 777 return -EINVAL; 778 } 779 780 nbd_dev = kcalloc(nbds_max, sizeof(*nbd_dev), GFP_KERNEL); 781 if (!nbd_dev) 782 return -ENOMEM; 783 784 part_shift = 0; 785 if (max_part > 0) { 786 part_shift = fls(max_part); 787 788 /* 789 * Adjust max_part according to part_shift as it is exported 790 * to user space so that user can know the max number of 791 * partition kernel should be able to manage. 792 * 793 * Note that -1 is required because partition 0 is reserved 794 * for the whole disk. 795 */ 796 max_part = (1UL << part_shift) - 1; 797 } 798 799 if ((1UL << part_shift) > DISK_MAX_PARTS) 800 return -EINVAL; 801 802 if (nbds_max > 1UL << (MINORBITS - part_shift)) 803 return -EINVAL; 804 805 for (i = 0; i < nbds_max; i++) { 806 struct gendisk *disk = alloc_disk(1 << part_shift); 807 if (!disk) 808 goto out; 809 nbd_dev[i].disk = disk; 810 /* 811 * The new linux 2.5 block layer implementation requires 812 * every gendisk to have its very own request_queue struct. 813 * These structs are big so we dynamically allocate them. 814 */ 815 disk->queue = blk_init_queue(do_nbd_request, &nbd_lock); 816 if (!disk->queue) { 817 put_disk(disk); 818 goto out; 819 } 820 /* 821 * Tell the block layer that we are not a rotational device 822 */ 823 queue_flag_set_unlocked(QUEUE_FLAG_NONROT, 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 } 828 829 if (register_blkdev(NBD_MAJOR, "nbd")) { 830 err = -EIO; 831 goto out; 832 } 833 834 printk(KERN_INFO "nbd: registered device at major %d\n", NBD_MAJOR); 835 dprintk(DBG_INIT, "nbd: debugflags=0x%x\n", debugflags); 836 837 for (i = 0; i < nbds_max; i++) { 838 struct gendisk *disk = nbd_dev[i].disk; 839 nbd_dev[i].file = NULL; 840 nbd_dev[i].magic = NBD_MAGIC; 841 nbd_dev[i].flags = 0; 842 INIT_LIST_HEAD(&nbd_dev[i].waiting_queue); 843 spin_lock_init(&nbd_dev[i].queue_lock); 844 INIT_LIST_HEAD(&nbd_dev[i].queue_head); 845 mutex_init(&nbd_dev[i].tx_lock); 846 init_waitqueue_head(&nbd_dev[i].active_wq); 847 init_waitqueue_head(&nbd_dev[i].waiting_wq); 848 nbd_dev[i].blksize = 1024; 849 nbd_dev[i].bytesize = 0; 850 disk->major = NBD_MAJOR; 851 disk->first_minor = i << part_shift; 852 disk->fops = &nbd_fops; 853 disk->private_data = &nbd_dev[i]; 854 sprintf(disk->disk_name, "nbd%d", i); 855 set_capacity(disk, 0); 856 add_disk(disk); 857 } 858 859 return 0; 860 out: 861 while (i--) { 862 blk_cleanup_queue(nbd_dev[i].disk->queue); 863 put_disk(nbd_dev[i].disk); 864 } 865 kfree(nbd_dev); 866 return err; 867 } 868 869 static void __exit nbd_cleanup(void) 870 { 871 int i; 872 for (i = 0; i < nbds_max; i++) { 873 struct gendisk *disk = nbd_dev[i].disk; 874 nbd_dev[i].magic = 0; 875 if (disk) { 876 del_gendisk(disk); 877 blk_cleanup_queue(disk->queue); 878 put_disk(disk); 879 } 880 } 881 unregister_blkdev(NBD_MAJOR, "nbd"); 882 kfree(nbd_dev); 883 printk(KERN_INFO "nbd: unregistered device at major %d\n", NBD_MAJOR); 884 } 885 886 module_init(nbd_init); 887 module_exit(nbd_cleanup); 888 889 MODULE_DESCRIPTION("Network Block Device"); 890 MODULE_LICENSE("GPL"); 891 892 module_param(nbds_max, int, 0444); 893 MODULE_PARM_DESC(nbds_max, "number of network block devices to initialize (default: 16)"); 894 module_param(max_part, int, 0444); 895 MODULE_PARM_DESC(max_part, "number of partitions per device (default: 0)"); 896 #ifndef NDEBUG 897 module_param(debugflags, int, 0644); 898 MODULE_PARM_DESC(debugflags, "flags for controlling debug output"); 899 #endif 900