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_FLUSH: return "flush"; 102 case NBD_CMD_TRIM: return "trim/discard"; 103 } 104 return "invalid"; 105 } 106 #endif /* NDEBUG */ 107 108 static void nbd_end_request(struct request *req) 109 { 110 int error = req->errors ? -EIO : 0; 111 struct request_queue *q = req->q; 112 unsigned long flags; 113 114 dprintk(DBG_BLKDEV, "%s: request %p: %s\n", req->rq_disk->disk_name, 115 req, error ? "failed" : "done"); 116 117 spin_lock_irqsave(q->queue_lock, flags); 118 __blk_end_request_all(req, error); 119 spin_unlock_irqrestore(q->queue_lock, flags); 120 } 121 122 static void sock_shutdown(struct nbd_device *nbd, int lock) 123 { 124 /* Forcibly shutdown the socket causing all listeners 125 * to error 126 * 127 * FIXME: This code is duplicated from sys_shutdown, but 128 * there should be a more generic interface rather than 129 * calling socket ops directly here */ 130 if (lock) 131 mutex_lock(&nbd->tx_lock); 132 if (nbd->sock) { 133 dev_warn(disk_to_dev(nbd->disk), "shutting down socket\n"); 134 kernel_sock_shutdown(nbd->sock, SHUT_RDWR); 135 nbd->sock = NULL; 136 } 137 if (lock) 138 mutex_unlock(&nbd->tx_lock); 139 } 140 141 static void nbd_xmit_timeout(unsigned long arg) 142 { 143 struct task_struct *task = (struct task_struct *)arg; 144 145 printk(KERN_WARNING "nbd: killing hung xmit (%s, pid: %d)\n", 146 task->comm, task->pid); 147 force_sig(SIGKILL, task); 148 } 149 150 /* 151 * Send or receive packet. 152 */ 153 static int sock_xmit(struct nbd_device *nbd, int send, void *buf, int size, 154 int msg_flags) 155 { 156 struct socket *sock = nbd->sock; 157 int result; 158 struct msghdr msg; 159 struct kvec iov; 160 sigset_t blocked, oldset; 161 unsigned long pflags = current->flags; 162 163 if (unlikely(!sock)) { 164 dev_err(disk_to_dev(nbd->disk), 165 "Attempted %s on closed socket in sock_xmit\n", 166 (send ? "send" : "recv")); 167 return -EINVAL; 168 } 169 170 /* Allow interception of SIGKILL only 171 * Don't allow other signals to interrupt the transmission */ 172 siginitsetinv(&blocked, sigmask(SIGKILL)); 173 sigprocmask(SIG_SETMASK, &blocked, &oldset); 174 175 current->flags |= PF_MEMALLOC; 176 do { 177 sock->sk->sk_allocation = GFP_NOIO | __GFP_MEMALLOC; 178 iov.iov_base = buf; 179 iov.iov_len = size; 180 msg.msg_name = NULL; 181 msg.msg_namelen = 0; 182 msg.msg_control = NULL; 183 msg.msg_controllen = 0; 184 msg.msg_flags = msg_flags | MSG_NOSIGNAL; 185 186 if (send) { 187 struct timer_list ti; 188 189 if (nbd->xmit_timeout) { 190 init_timer(&ti); 191 ti.function = nbd_xmit_timeout; 192 ti.data = (unsigned long)current; 193 ti.expires = jiffies + nbd->xmit_timeout; 194 add_timer(&ti); 195 } 196 result = kernel_sendmsg(sock, &msg, &iov, 1, size); 197 if (nbd->xmit_timeout) 198 del_timer_sync(&ti); 199 } else 200 result = kernel_recvmsg(sock, &msg, &iov, 1, size, 201 msg.msg_flags); 202 203 if (signal_pending(current)) { 204 siginfo_t info; 205 printk(KERN_WARNING "nbd (pid %d: %s) got signal %d\n", 206 task_pid_nr(current), current->comm, 207 dequeue_signal_lock(current, ¤t->blocked, &info)); 208 result = -EINTR; 209 sock_shutdown(nbd, !send); 210 break; 211 } 212 213 if (result <= 0) { 214 if (result == 0) 215 result = -EPIPE; /* short read */ 216 break; 217 } 218 size -= result; 219 buf += result; 220 } while (size > 0); 221 222 sigprocmask(SIG_SETMASK, &oldset, NULL); 223 tsk_restore_flags(current, pflags, PF_MEMALLOC); 224 225 return result; 226 } 227 228 static inline int sock_send_bvec(struct nbd_device *nbd, struct bio_vec *bvec, 229 int flags) 230 { 231 int result; 232 void *kaddr = kmap(bvec->bv_page); 233 result = sock_xmit(nbd, 1, kaddr + bvec->bv_offset, 234 bvec->bv_len, flags); 235 kunmap(bvec->bv_page); 236 return result; 237 } 238 239 /* always call with the tx_lock held */ 240 static int nbd_send_req(struct nbd_device *nbd, struct request *req) 241 { 242 int result, flags; 243 struct nbd_request request; 244 unsigned long size = blk_rq_bytes(req); 245 246 request.magic = htonl(NBD_REQUEST_MAGIC); 247 request.type = htonl(nbd_cmd(req)); 248 249 if (nbd_cmd(req) == NBD_CMD_FLUSH) { 250 /* Other values are reserved for FLUSH requests. */ 251 request.from = 0; 252 request.len = 0; 253 } else { 254 request.from = cpu_to_be64((u64)blk_rq_pos(req) << 9); 255 request.len = htonl(size); 256 } 257 memcpy(request.handle, &req, sizeof(req)); 258 259 dprintk(DBG_TX, "%s: request %p: sending control (%s@%llu,%uB)\n", 260 nbd->disk->disk_name, req, 261 nbdcmd_to_ascii(nbd_cmd(req)), 262 (unsigned long long)blk_rq_pos(req) << 9, 263 blk_rq_bytes(req)); 264 result = sock_xmit(nbd, 1, &request, sizeof(request), 265 (nbd_cmd(req) == NBD_CMD_WRITE) ? MSG_MORE : 0); 266 if (result <= 0) { 267 dev_err(disk_to_dev(nbd->disk), 268 "Send control failed (result %d)\n", result); 269 goto error_out; 270 } 271 272 if (nbd_cmd(req) == NBD_CMD_WRITE) { 273 struct req_iterator iter; 274 struct bio_vec bvec; 275 /* 276 * we are really probing at internals to determine 277 * whether to set MSG_MORE or not... 278 */ 279 rq_for_each_segment(bvec, req, iter) { 280 flags = 0; 281 if (!rq_iter_last(bvec, iter)) 282 flags = MSG_MORE; 283 dprintk(DBG_TX, "%s: request %p: sending %d bytes data\n", 284 nbd->disk->disk_name, req, bvec.bv_len); 285 result = sock_send_bvec(nbd, &bvec, flags); 286 if (result <= 0) { 287 dev_err(disk_to_dev(nbd->disk), 288 "Send data failed (result %d)\n", 289 result); 290 goto error_out; 291 } 292 } 293 } 294 return 0; 295 296 error_out: 297 return -EIO; 298 } 299 300 static struct request *nbd_find_request(struct nbd_device *nbd, 301 struct request *xreq) 302 { 303 struct request *req, *tmp; 304 int err; 305 306 err = wait_event_interruptible(nbd->active_wq, nbd->active_req != xreq); 307 if (unlikely(err)) 308 goto out; 309 310 spin_lock(&nbd->queue_lock); 311 list_for_each_entry_safe(req, tmp, &nbd->queue_head, queuelist) { 312 if (req != xreq) 313 continue; 314 list_del_init(&req->queuelist); 315 spin_unlock(&nbd->queue_lock); 316 return req; 317 } 318 spin_unlock(&nbd->queue_lock); 319 320 err = -ENOENT; 321 322 out: 323 return ERR_PTR(err); 324 } 325 326 static inline int sock_recv_bvec(struct nbd_device *nbd, struct bio_vec *bvec) 327 { 328 int result; 329 void *kaddr = kmap(bvec->bv_page); 330 result = sock_xmit(nbd, 0, kaddr + bvec->bv_offset, bvec->bv_len, 331 MSG_WAITALL); 332 kunmap(bvec->bv_page); 333 return result; 334 } 335 336 /* NULL returned = something went wrong, inform userspace */ 337 static struct request *nbd_read_stat(struct nbd_device *nbd) 338 { 339 int result; 340 struct nbd_reply reply; 341 struct request *req; 342 343 reply.magic = 0; 344 result = sock_xmit(nbd, 0, &reply, sizeof(reply), MSG_WAITALL); 345 if (result <= 0) { 346 dev_err(disk_to_dev(nbd->disk), 347 "Receive control failed (result %d)\n", result); 348 goto harderror; 349 } 350 351 if (ntohl(reply.magic) != NBD_REPLY_MAGIC) { 352 dev_err(disk_to_dev(nbd->disk), "Wrong magic (0x%lx)\n", 353 (unsigned long)ntohl(reply.magic)); 354 result = -EPROTO; 355 goto harderror; 356 } 357 358 req = nbd_find_request(nbd, *(struct request **)reply.handle); 359 if (IS_ERR(req)) { 360 result = PTR_ERR(req); 361 if (result != -ENOENT) 362 goto harderror; 363 364 dev_err(disk_to_dev(nbd->disk), "Unexpected reply (%p)\n", 365 reply.handle); 366 result = -EBADR; 367 goto harderror; 368 } 369 370 if (ntohl(reply.error)) { 371 dev_err(disk_to_dev(nbd->disk), "Other side returned error (%d)\n", 372 ntohl(reply.error)); 373 req->errors++; 374 return req; 375 } 376 377 dprintk(DBG_RX, "%s: request %p: got reply\n", 378 nbd->disk->disk_name, req); 379 if (nbd_cmd(req) == NBD_CMD_READ) { 380 struct req_iterator iter; 381 struct bio_vec bvec; 382 383 rq_for_each_segment(bvec, req, iter) { 384 result = sock_recv_bvec(nbd, &bvec); 385 if (result <= 0) { 386 dev_err(disk_to_dev(nbd->disk), "Receive data failed (result %d)\n", 387 result); 388 req->errors++; 389 return req; 390 } 391 dprintk(DBG_RX, "%s: request %p: got %d bytes data\n", 392 nbd->disk->disk_name, req, bvec.bv_len); 393 } 394 } 395 return req; 396 harderror: 397 nbd->harderror = result; 398 return NULL; 399 } 400 401 static ssize_t pid_show(struct device *dev, 402 struct device_attribute *attr, char *buf) 403 { 404 struct gendisk *disk = dev_to_disk(dev); 405 406 return sprintf(buf, "%ld\n", 407 (long) ((struct nbd_device *)disk->private_data)->pid); 408 } 409 410 static struct device_attribute pid_attr = { 411 .attr = { .name = "pid", .mode = S_IRUGO}, 412 .show = pid_show, 413 }; 414 415 static int nbd_do_it(struct nbd_device *nbd) 416 { 417 struct request *req; 418 int ret; 419 420 BUG_ON(nbd->magic != NBD_MAGIC); 421 422 sk_set_memalloc(nbd->sock->sk); 423 nbd->pid = task_pid_nr(current); 424 ret = device_create_file(disk_to_dev(nbd->disk), &pid_attr); 425 if (ret) { 426 dev_err(disk_to_dev(nbd->disk), "device_create_file failed!\n"); 427 nbd->pid = 0; 428 return ret; 429 } 430 431 while ((req = nbd_read_stat(nbd)) != NULL) 432 nbd_end_request(req); 433 434 device_remove_file(disk_to_dev(nbd->disk), &pid_attr); 435 nbd->pid = 0; 436 return 0; 437 } 438 439 static void nbd_clear_que(struct nbd_device *nbd) 440 { 441 struct request *req; 442 443 BUG_ON(nbd->magic != NBD_MAGIC); 444 445 /* 446 * Because we have set nbd->sock to NULL under the tx_lock, all 447 * modifications to the list must have completed by now. For 448 * the same reason, the active_req must be NULL. 449 * 450 * As a consequence, we don't need to take the spin lock while 451 * purging the list here. 452 */ 453 BUG_ON(nbd->sock); 454 BUG_ON(nbd->active_req); 455 456 while (!list_empty(&nbd->queue_head)) { 457 req = list_entry(nbd->queue_head.next, struct request, 458 queuelist); 459 list_del_init(&req->queuelist); 460 req->errors++; 461 nbd_end_request(req); 462 } 463 464 while (!list_empty(&nbd->waiting_queue)) { 465 req = list_entry(nbd->waiting_queue.next, struct request, 466 queuelist); 467 list_del_init(&req->queuelist); 468 req->errors++; 469 nbd_end_request(req); 470 } 471 } 472 473 474 static void nbd_handle_req(struct nbd_device *nbd, struct request *req) 475 { 476 if (req->cmd_type != REQ_TYPE_FS) 477 goto error_out; 478 479 nbd_cmd(req) = NBD_CMD_READ; 480 if (rq_data_dir(req) == WRITE) { 481 if ((req->cmd_flags & REQ_DISCARD)) { 482 WARN_ON(!(nbd->flags & NBD_FLAG_SEND_TRIM)); 483 nbd_cmd(req) = NBD_CMD_TRIM; 484 } else 485 nbd_cmd(req) = NBD_CMD_WRITE; 486 if (nbd->flags & NBD_FLAG_READ_ONLY) { 487 dev_err(disk_to_dev(nbd->disk), 488 "Write on read-only\n"); 489 goto error_out; 490 } 491 } 492 493 if (req->cmd_flags & REQ_FLUSH) { 494 BUG_ON(unlikely(blk_rq_sectors(req))); 495 nbd_cmd(req) = NBD_CMD_FLUSH; 496 } 497 498 req->errors = 0; 499 500 mutex_lock(&nbd->tx_lock); 501 if (unlikely(!nbd->sock)) { 502 mutex_unlock(&nbd->tx_lock); 503 dev_err(disk_to_dev(nbd->disk), 504 "Attempted send on closed socket\n"); 505 goto error_out; 506 } 507 508 nbd->active_req = req; 509 510 if (nbd_send_req(nbd, req) != 0) { 511 dev_err(disk_to_dev(nbd->disk), "Request send failed\n"); 512 req->errors++; 513 nbd_end_request(req); 514 } else { 515 spin_lock(&nbd->queue_lock); 516 list_add_tail(&req->queuelist, &nbd->queue_head); 517 spin_unlock(&nbd->queue_lock); 518 } 519 520 nbd->active_req = NULL; 521 mutex_unlock(&nbd->tx_lock); 522 wake_up_all(&nbd->active_wq); 523 524 return; 525 526 error_out: 527 req->errors++; 528 nbd_end_request(req); 529 } 530 531 static int nbd_thread(void *data) 532 { 533 struct nbd_device *nbd = data; 534 struct request *req; 535 536 set_user_nice(current, -20); 537 while (!kthread_should_stop() || !list_empty(&nbd->waiting_queue)) { 538 /* wait for something to do */ 539 wait_event_interruptible(nbd->waiting_wq, 540 kthread_should_stop() || 541 !list_empty(&nbd->waiting_queue)); 542 543 /* extract request */ 544 if (list_empty(&nbd->waiting_queue)) 545 continue; 546 547 spin_lock_irq(&nbd->queue_lock); 548 req = list_entry(nbd->waiting_queue.next, struct request, 549 queuelist); 550 list_del_init(&req->queuelist); 551 spin_unlock_irq(&nbd->queue_lock); 552 553 /* handle request */ 554 nbd_handle_req(nbd, req); 555 } 556 return 0; 557 } 558 559 /* 560 * We always wait for result of write, for now. It would be nice to make it optional 561 * in future 562 * if ((rq_data_dir(req) == WRITE) && (nbd->flags & NBD_WRITE_NOCHK)) 563 * { printk( "Warning: Ignoring result!\n"); nbd_end_request( req ); } 564 */ 565 566 static void do_nbd_request(struct request_queue *q) 567 __releases(q->queue_lock) __acquires(q->queue_lock) 568 { 569 struct request *req; 570 571 while ((req = blk_fetch_request(q)) != NULL) { 572 struct nbd_device *nbd; 573 574 spin_unlock_irq(q->queue_lock); 575 576 dprintk(DBG_BLKDEV, "%s: request %p: dequeued (flags=%x)\n", 577 req->rq_disk->disk_name, req, req->cmd_type); 578 579 nbd = req->rq_disk->private_data; 580 581 BUG_ON(nbd->magic != NBD_MAGIC); 582 583 if (unlikely(!nbd->sock)) { 584 dev_err(disk_to_dev(nbd->disk), 585 "Attempted send on closed socket\n"); 586 req->errors++; 587 nbd_end_request(req); 588 spin_lock_irq(q->queue_lock); 589 continue; 590 } 591 592 spin_lock_irq(&nbd->queue_lock); 593 list_add_tail(&req->queuelist, &nbd->waiting_queue); 594 spin_unlock_irq(&nbd->queue_lock); 595 596 wake_up(&nbd->waiting_wq); 597 598 spin_lock_irq(q->queue_lock); 599 } 600 } 601 602 /* Must be called with tx_lock held */ 603 604 static int __nbd_ioctl(struct block_device *bdev, struct nbd_device *nbd, 605 unsigned int cmd, unsigned long arg) 606 { 607 switch (cmd) { 608 case NBD_DISCONNECT: { 609 struct request sreq; 610 611 dev_info(disk_to_dev(nbd->disk), "NBD_DISCONNECT\n"); 612 if (!nbd->sock) 613 return -EINVAL; 614 615 mutex_unlock(&nbd->tx_lock); 616 fsync_bdev(bdev); 617 mutex_lock(&nbd->tx_lock); 618 blk_rq_init(NULL, &sreq); 619 sreq.cmd_type = REQ_TYPE_SPECIAL; 620 nbd_cmd(&sreq) = NBD_CMD_DISC; 621 622 /* Check again after getting mutex back. */ 623 if (!nbd->sock) 624 return -EINVAL; 625 626 nbd->disconnect = 1; 627 628 nbd_send_req(nbd, &sreq); 629 return 0; 630 } 631 632 case NBD_CLEAR_SOCK: { 633 struct file *file; 634 635 nbd->sock = NULL; 636 file = nbd->file; 637 nbd->file = NULL; 638 nbd_clear_que(nbd); 639 BUG_ON(!list_empty(&nbd->queue_head)); 640 BUG_ON(!list_empty(&nbd->waiting_queue)); 641 kill_bdev(bdev); 642 if (file) 643 fput(file); 644 return 0; 645 } 646 647 case NBD_SET_SOCK: { 648 struct file *file; 649 if (nbd->file) 650 return -EBUSY; 651 file = fget(arg); 652 if (file) { 653 struct inode *inode = file_inode(file); 654 if (S_ISSOCK(inode->i_mode)) { 655 nbd->file = file; 656 nbd->sock = SOCKET_I(inode); 657 if (max_part > 0) 658 bdev->bd_invalidated = 1; 659 nbd->disconnect = 0; /* we're connected now */ 660 return 0; 661 } else { 662 fput(file); 663 } 664 } 665 return -EINVAL; 666 } 667 668 case NBD_SET_BLKSIZE: 669 nbd->blksize = arg; 670 nbd->bytesize &= ~(nbd->blksize-1); 671 bdev->bd_inode->i_size = nbd->bytesize; 672 set_blocksize(bdev, nbd->blksize); 673 set_capacity(nbd->disk, nbd->bytesize >> 9); 674 return 0; 675 676 case NBD_SET_SIZE: 677 nbd->bytesize = arg & ~(nbd->blksize-1); 678 bdev->bd_inode->i_size = nbd->bytesize; 679 set_blocksize(bdev, nbd->blksize); 680 set_capacity(nbd->disk, nbd->bytesize >> 9); 681 return 0; 682 683 case NBD_SET_TIMEOUT: 684 nbd->xmit_timeout = arg * HZ; 685 return 0; 686 687 case NBD_SET_FLAGS: 688 nbd->flags = arg; 689 return 0; 690 691 case NBD_SET_SIZE_BLOCKS: 692 nbd->bytesize = ((u64) arg) * nbd->blksize; 693 bdev->bd_inode->i_size = nbd->bytesize; 694 set_blocksize(bdev, nbd->blksize); 695 set_capacity(nbd->disk, nbd->bytesize >> 9); 696 return 0; 697 698 case NBD_DO_IT: { 699 struct task_struct *thread; 700 struct file *file; 701 int error; 702 703 if (nbd->pid) 704 return -EBUSY; 705 if (!nbd->file) 706 return -EINVAL; 707 708 mutex_unlock(&nbd->tx_lock); 709 710 if (nbd->flags & NBD_FLAG_READ_ONLY) 711 set_device_ro(bdev, true); 712 if (nbd->flags & NBD_FLAG_SEND_TRIM) 713 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, 714 nbd->disk->queue); 715 if (nbd->flags & NBD_FLAG_SEND_FLUSH) 716 blk_queue_flush(nbd->disk->queue, REQ_FLUSH); 717 else 718 blk_queue_flush(nbd->disk->queue, 0); 719 720 thread = kthread_create(nbd_thread, nbd, "%s", 721 nbd->disk->disk_name); 722 if (IS_ERR(thread)) { 723 mutex_lock(&nbd->tx_lock); 724 return PTR_ERR(thread); 725 } 726 wake_up_process(thread); 727 error = nbd_do_it(nbd); 728 kthread_stop(thread); 729 730 mutex_lock(&nbd->tx_lock); 731 if (error) 732 return error; 733 sock_shutdown(nbd, 0); 734 file = nbd->file; 735 nbd->file = NULL; 736 nbd_clear_que(nbd); 737 dev_warn(disk_to_dev(nbd->disk), "queue cleared\n"); 738 kill_bdev(bdev); 739 queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, nbd->disk->queue); 740 set_device_ro(bdev, false); 741 if (file) 742 fput(file); 743 nbd->flags = 0; 744 nbd->bytesize = 0; 745 bdev->bd_inode->i_size = 0; 746 set_capacity(nbd->disk, 0); 747 if (max_part > 0) 748 ioctl_by_bdev(bdev, BLKRRPART, 0); 749 if (nbd->disconnect) /* user requested, ignore socket errors */ 750 return 0; 751 return nbd->harderror; 752 } 753 754 case NBD_CLEAR_QUE: 755 /* 756 * This is for compatibility only. The queue is always cleared 757 * by NBD_DO_IT or NBD_CLEAR_SOCK. 758 */ 759 return 0; 760 761 case NBD_PRINT_DEBUG: 762 dev_info(disk_to_dev(nbd->disk), 763 "next = %p, prev = %p, head = %p\n", 764 nbd->queue_head.next, nbd->queue_head.prev, 765 &nbd->queue_head); 766 return 0; 767 } 768 return -ENOTTY; 769 } 770 771 static int nbd_ioctl(struct block_device *bdev, fmode_t mode, 772 unsigned int cmd, unsigned long arg) 773 { 774 struct nbd_device *nbd = bdev->bd_disk->private_data; 775 int error; 776 777 if (!capable(CAP_SYS_ADMIN)) 778 return -EPERM; 779 780 BUG_ON(nbd->magic != NBD_MAGIC); 781 782 /* Anyone capable of this syscall can do *real bad* things */ 783 dprintk(DBG_IOCTL, "%s: nbd_ioctl cmd=%s(0x%x) arg=%lu\n", 784 nbd->disk->disk_name, ioctl_cmd_to_ascii(cmd), cmd, arg); 785 786 mutex_lock(&nbd->tx_lock); 787 error = __nbd_ioctl(bdev, nbd, cmd, arg); 788 mutex_unlock(&nbd->tx_lock); 789 790 return error; 791 } 792 793 static const struct block_device_operations nbd_fops = 794 { 795 .owner = THIS_MODULE, 796 .ioctl = nbd_ioctl, 797 }; 798 799 /* 800 * And here should be modules and kernel interface 801 * (Just smiley confuses emacs :-) 802 */ 803 804 static int __init nbd_init(void) 805 { 806 int err = -ENOMEM; 807 int i; 808 int part_shift; 809 810 BUILD_BUG_ON(sizeof(struct nbd_request) != 28); 811 812 if (max_part < 0) { 813 printk(KERN_ERR "nbd: max_part must be >= 0\n"); 814 return -EINVAL; 815 } 816 817 nbd_dev = kcalloc(nbds_max, sizeof(*nbd_dev), GFP_KERNEL); 818 if (!nbd_dev) 819 return -ENOMEM; 820 821 part_shift = 0; 822 if (max_part > 0) { 823 part_shift = fls(max_part); 824 825 /* 826 * Adjust max_part according to part_shift as it is exported 827 * to user space so that user can know the max number of 828 * partition kernel should be able to manage. 829 * 830 * Note that -1 is required because partition 0 is reserved 831 * for the whole disk. 832 */ 833 max_part = (1UL << part_shift) - 1; 834 } 835 836 if ((1UL << part_shift) > DISK_MAX_PARTS) 837 return -EINVAL; 838 839 if (nbds_max > 1UL << (MINORBITS - part_shift)) 840 return -EINVAL; 841 842 for (i = 0; i < nbds_max; i++) { 843 struct gendisk *disk = alloc_disk(1 << part_shift); 844 if (!disk) 845 goto out; 846 nbd_dev[i].disk = disk; 847 /* 848 * The new linux 2.5 block layer implementation requires 849 * every gendisk to have its very own request_queue struct. 850 * These structs are big so we dynamically allocate them. 851 */ 852 disk->queue = blk_init_queue(do_nbd_request, &nbd_lock); 853 if (!disk->queue) { 854 put_disk(disk); 855 goto out; 856 } 857 /* 858 * Tell the block layer that we are not a rotational device 859 */ 860 queue_flag_set_unlocked(QUEUE_FLAG_NONROT, disk->queue); 861 disk->queue->limits.discard_granularity = 512; 862 disk->queue->limits.max_discard_sectors = UINT_MAX; 863 disk->queue->limits.discard_zeroes_data = 0; 864 blk_queue_max_hw_sectors(disk->queue, 65536); 865 disk->queue->limits.max_sectors = 256; 866 } 867 868 if (register_blkdev(NBD_MAJOR, "nbd")) { 869 err = -EIO; 870 goto out; 871 } 872 873 printk(KERN_INFO "nbd: registered device at major %d\n", NBD_MAJOR); 874 dprintk(DBG_INIT, "nbd: debugflags=0x%x\n", debugflags); 875 876 for (i = 0; i < nbds_max; i++) { 877 struct gendisk *disk = nbd_dev[i].disk; 878 nbd_dev[i].file = NULL; 879 nbd_dev[i].magic = NBD_MAGIC; 880 nbd_dev[i].flags = 0; 881 INIT_LIST_HEAD(&nbd_dev[i].waiting_queue); 882 spin_lock_init(&nbd_dev[i].queue_lock); 883 INIT_LIST_HEAD(&nbd_dev[i].queue_head); 884 mutex_init(&nbd_dev[i].tx_lock); 885 init_waitqueue_head(&nbd_dev[i].active_wq); 886 init_waitqueue_head(&nbd_dev[i].waiting_wq); 887 nbd_dev[i].blksize = 1024; 888 nbd_dev[i].bytesize = 0; 889 disk->major = NBD_MAJOR; 890 disk->first_minor = i << part_shift; 891 disk->fops = &nbd_fops; 892 disk->private_data = &nbd_dev[i]; 893 sprintf(disk->disk_name, "nbd%d", i); 894 set_capacity(disk, 0); 895 add_disk(disk); 896 } 897 898 return 0; 899 out: 900 while (i--) { 901 blk_cleanup_queue(nbd_dev[i].disk->queue); 902 put_disk(nbd_dev[i].disk); 903 } 904 kfree(nbd_dev); 905 return err; 906 } 907 908 static void __exit nbd_cleanup(void) 909 { 910 int i; 911 for (i = 0; i < nbds_max; i++) { 912 struct gendisk *disk = nbd_dev[i].disk; 913 nbd_dev[i].magic = 0; 914 if (disk) { 915 del_gendisk(disk); 916 blk_cleanup_queue(disk->queue); 917 put_disk(disk); 918 } 919 } 920 unregister_blkdev(NBD_MAJOR, "nbd"); 921 kfree(nbd_dev); 922 printk(KERN_INFO "nbd: unregistered device at major %d\n", NBD_MAJOR); 923 } 924 925 module_init(nbd_init); 926 module_exit(nbd_cleanup); 927 928 MODULE_DESCRIPTION("Network Block Device"); 929 MODULE_LICENSE("GPL"); 930 931 module_param(nbds_max, int, 0444); 932 MODULE_PARM_DESC(nbds_max, "number of network block devices to initialize (default: 16)"); 933 module_param(max_part, int, 0444); 934 MODULE_PARM_DESC(max_part, "number of partitions per device (default: 0)"); 935 #ifndef NDEBUG 936 module_param(debugflags, int, 0644); 937 MODULE_PARM_DESC(debugflags, "flags for controlling debug output"); 938 #endif 939