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 #include <linux/debugfs.h> 37 #include <linux/blk-mq.h> 38 39 #include <asm/uaccess.h> 40 #include <asm/types.h> 41 42 #include <linux/nbd.h> 43 44 #define NBD_TIMEDOUT 0 45 #define NBD_DISCONNECT_REQUESTED 1 46 47 struct nbd_device { 48 u32 flags; 49 unsigned long runtime_flags; 50 struct socket * sock; /* If == NULL, device is not ready, yet */ 51 int magic; 52 53 struct blk_mq_tag_set tag_set; 54 55 struct mutex tx_lock; 56 struct gendisk *disk; 57 int blksize; 58 loff_t bytesize; 59 60 /* protects initialization and shutdown of the socket */ 61 spinlock_t sock_lock; 62 struct task_struct *task_recv; 63 struct task_struct *task_send; 64 65 #if IS_ENABLED(CONFIG_DEBUG_FS) 66 struct dentry *dbg_dir; 67 #endif 68 }; 69 70 struct nbd_cmd { 71 struct nbd_device *nbd; 72 struct list_head list; 73 }; 74 75 #if IS_ENABLED(CONFIG_DEBUG_FS) 76 static struct dentry *nbd_dbg_dir; 77 #endif 78 79 #define nbd_name(nbd) ((nbd)->disk->disk_name) 80 81 #define NBD_MAGIC 0x68797548 82 83 static unsigned int nbds_max = 16; 84 static struct nbd_device *nbd_dev; 85 static int max_part; 86 87 static inline struct device *nbd_to_dev(struct nbd_device *nbd) 88 { 89 return disk_to_dev(nbd->disk); 90 } 91 92 static bool nbd_is_connected(struct nbd_device *nbd) 93 { 94 return !!nbd->task_recv; 95 } 96 97 static const char *nbdcmd_to_ascii(int cmd) 98 { 99 switch (cmd) { 100 case NBD_CMD_READ: return "read"; 101 case NBD_CMD_WRITE: return "write"; 102 case NBD_CMD_DISC: return "disconnect"; 103 case NBD_CMD_FLUSH: return "flush"; 104 case NBD_CMD_TRIM: return "trim/discard"; 105 } 106 return "invalid"; 107 } 108 109 static int nbd_size_clear(struct nbd_device *nbd, struct block_device *bdev) 110 { 111 bdev->bd_inode->i_size = 0; 112 set_capacity(nbd->disk, 0); 113 kobject_uevent(&nbd_to_dev(nbd)->kobj, KOBJ_CHANGE); 114 115 return 0; 116 } 117 118 static void nbd_size_update(struct nbd_device *nbd, struct block_device *bdev) 119 { 120 if (!nbd_is_connected(nbd)) 121 return; 122 123 bdev->bd_inode->i_size = nbd->bytesize; 124 set_capacity(nbd->disk, nbd->bytesize >> 9); 125 kobject_uevent(&nbd_to_dev(nbd)->kobj, KOBJ_CHANGE); 126 } 127 128 static int nbd_size_set(struct nbd_device *nbd, struct block_device *bdev, 129 int blocksize, int nr_blocks) 130 { 131 int ret; 132 133 ret = set_blocksize(bdev, blocksize); 134 if (ret) 135 return ret; 136 137 nbd->blksize = blocksize; 138 nbd->bytesize = (loff_t)blocksize * (loff_t)nr_blocks; 139 140 nbd_size_update(nbd, bdev); 141 142 return 0; 143 } 144 145 static void nbd_end_request(struct nbd_cmd *cmd) 146 { 147 struct nbd_device *nbd = cmd->nbd; 148 struct request *req = blk_mq_rq_from_pdu(cmd); 149 int error = req->errors ? -EIO : 0; 150 151 dev_dbg(nbd_to_dev(nbd), "request %p: %s\n", cmd, 152 error ? "failed" : "done"); 153 154 blk_mq_complete_request(req, error); 155 } 156 157 /* 158 * Forcibly shutdown the socket causing all listeners to error 159 */ 160 static void sock_shutdown(struct nbd_device *nbd) 161 { 162 struct socket *sock; 163 164 spin_lock(&nbd->sock_lock); 165 166 if (!nbd->sock) { 167 spin_unlock(&nbd->sock_lock); 168 return; 169 } 170 171 sock = nbd->sock; 172 dev_warn(disk_to_dev(nbd->disk), "shutting down socket\n"); 173 nbd->sock = NULL; 174 spin_unlock(&nbd->sock_lock); 175 176 kernel_sock_shutdown(sock, SHUT_RDWR); 177 sockfd_put(sock); 178 } 179 180 static enum blk_eh_timer_return nbd_xmit_timeout(struct request *req, 181 bool reserved) 182 { 183 struct nbd_cmd *cmd = blk_mq_rq_to_pdu(req); 184 struct nbd_device *nbd = cmd->nbd; 185 struct socket *sock = NULL; 186 187 spin_lock(&nbd->sock_lock); 188 189 set_bit(NBD_TIMEDOUT, &nbd->runtime_flags); 190 191 if (nbd->sock) { 192 sock = nbd->sock; 193 get_file(sock->file); 194 } 195 196 spin_unlock(&nbd->sock_lock); 197 if (sock) { 198 kernel_sock_shutdown(sock, SHUT_RDWR); 199 sockfd_put(sock); 200 } 201 202 req->errors++; 203 dev_err(nbd_to_dev(nbd), "Connection timed out, shutting down connection\n"); 204 return BLK_EH_HANDLED; 205 } 206 207 /* 208 * Send or receive packet. 209 */ 210 static int sock_xmit(struct nbd_device *nbd, int send, void *buf, int size, 211 int msg_flags) 212 { 213 struct socket *sock = nbd->sock; 214 int result; 215 struct msghdr msg; 216 struct kvec iov; 217 unsigned long pflags = current->flags; 218 219 if (unlikely(!sock)) { 220 dev_err(disk_to_dev(nbd->disk), 221 "Attempted %s on closed socket in sock_xmit\n", 222 (send ? "send" : "recv")); 223 return -EINVAL; 224 } 225 226 current->flags |= PF_MEMALLOC; 227 do { 228 sock->sk->sk_allocation = GFP_NOIO | __GFP_MEMALLOC; 229 iov.iov_base = buf; 230 iov.iov_len = size; 231 msg.msg_name = NULL; 232 msg.msg_namelen = 0; 233 msg.msg_control = NULL; 234 msg.msg_controllen = 0; 235 msg.msg_flags = msg_flags | MSG_NOSIGNAL; 236 237 if (send) 238 result = kernel_sendmsg(sock, &msg, &iov, 1, size); 239 else 240 result = kernel_recvmsg(sock, &msg, &iov, 1, size, 241 msg.msg_flags); 242 243 if (result <= 0) { 244 if (result == 0) 245 result = -EPIPE; /* short read */ 246 break; 247 } 248 size -= result; 249 buf += result; 250 } while (size > 0); 251 252 tsk_restore_flags(current, pflags, PF_MEMALLOC); 253 254 return result; 255 } 256 257 static inline int sock_send_bvec(struct nbd_device *nbd, struct bio_vec *bvec, 258 int flags) 259 { 260 int result; 261 void *kaddr = kmap(bvec->bv_page); 262 result = sock_xmit(nbd, 1, kaddr + bvec->bv_offset, 263 bvec->bv_len, flags); 264 kunmap(bvec->bv_page); 265 return result; 266 } 267 268 /* always call with the tx_lock held */ 269 static int nbd_send_cmd(struct nbd_device *nbd, struct nbd_cmd *cmd) 270 { 271 struct request *req = blk_mq_rq_from_pdu(cmd); 272 int result, flags; 273 struct nbd_request request; 274 unsigned long size = blk_rq_bytes(req); 275 u32 type; 276 277 if (req->cmd_type == REQ_TYPE_DRV_PRIV) 278 type = NBD_CMD_DISC; 279 else if (req_op(req) == REQ_OP_DISCARD) 280 type = NBD_CMD_TRIM; 281 else if (req_op(req) == REQ_OP_FLUSH) 282 type = NBD_CMD_FLUSH; 283 else if (rq_data_dir(req) == WRITE) 284 type = NBD_CMD_WRITE; 285 else 286 type = NBD_CMD_READ; 287 288 memset(&request, 0, sizeof(request)); 289 request.magic = htonl(NBD_REQUEST_MAGIC); 290 request.type = htonl(type); 291 if (type != NBD_CMD_FLUSH && type != NBD_CMD_DISC) { 292 request.from = cpu_to_be64((u64)blk_rq_pos(req) << 9); 293 request.len = htonl(size); 294 } 295 memcpy(request.handle, &req->tag, sizeof(req->tag)); 296 297 dev_dbg(nbd_to_dev(nbd), "request %p: sending control (%s@%llu,%uB)\n", 298 cmd, nbdcmd_to_ascii(type), 299 (unsigned long long)blk_rq_pos(req) << 9, blk_rq_bytes(req)); 300 result = sock_xmit(nbd, 1, &request, sizeof(request), 301 (type == NBD_CMD_WRITE) ? MSG_MORE : 0); 302 if (result <= 0) { 303 dev_err(disk_to_dev(nbd->disk), 304 "Send control failed (result %d)\n", result); 305 return -EIO; 306 } 307 308 if (type == NBD_CMD_WRITE) { 309 struct req_iterator iter; 310 struct bio_vec bvec; 311 /* 312 * we are really probing at internals to determine 313 * whether to set MSG_MORE or not... 314 */ 315 rq_for_each_segment(bvec, req, iter) { 316 flags = 0; 317 if (!rq_iter_last(bvec, iter)) 318 flags = MSG_MORE; 319 dev_dbg(nbd_to_dev(nbd), "request %p: sending %d bytes data\n", 320 cmd, bvec.bv_len); 321 result = sock_send_bvec(nbd, &bvec, flags); 322 if (result <= 0) { 323 dev_err(disk_to_dev(nbd->disk), 324 "Send data failed (result %d)\n", 325 result); 326 return -EIO; 327 } 328 } 329 } 330 return 0; 331 } 332 333 static inline int sock_recv_bvec(struct nbd_device *nbd, struct bio_vec *bvec) 334 { 335 int result; 336 void *kaddr = kmap(bvec->bv_page); 337 result = sock_xmit(nbd, 0, kaddr + bvec->bv_offset, bvec->bv_len, 338 MSG_WAITALL); 339 kunmap(bvec->bv_page); 340 return result; 341 } 342 343 /* NULL returned = something went wrong, inform userspace */ 344 static struct nbd_cmd *nbd_read_stat(struct nbd_device *nbd) 345 { 346 int result; 347 struct nbd_reply reply; 348 struct nbd_cmd *cmd; 349 struct request *req = NULL; 350 u16 hwq; 351 int tag; 352 353 reply.magic = 0; 354 result = sock_xmit(nbd, 0, &reply, sizeof(reply), MSG_WAITALL); 355 if (result <= 0) { 356 dev_err(disk_to_dev(nbd->disk), 357 "Receive control failed (result %d)\n", result); 358 return ERR_PTR(result); 359 } 360 361 if (ntohl(reply.magic) != NBD_REPLY_MAGIC) { 362 dev_err(disk_to_dev(nbd->disk), "Wrong magic (0x%lx)\n", 363 (unsigned long)ntohl(reply.magic)); 364 return ERR_PTR(-EPROTO); 365 } 366 367 memcpy(&tag, reply.handle, sizeof(int)); 368 369 hwq = blk_mq_unique_tag_to_hwq(tag); 370 if (hwq < nbd->tag_set.nr_hw_queues) 371 req = blk_mq_tag_to_rq(nbd->tag_set.tags[hwq], 372 blk_mq_unique_tag_to_tag(tag)); 373 if (!req || !blk_mq_request_started(req)) { 374 dev_err(disk_to_dev(nbd->disk), "Unexpected reply (%d) %p\n", 375 tag, req); 376 return ERR_PTR(-ENOENT); 377 } 378 cmd = blk_mq_rq_to_pdu(req); 379 380 if (ntohl(reply.error)) { 381 dev_err(disk_to_dev(nbd->disk), "Other side returned error (%d)\n", 382 ntohl(reply.error)); 383 req->errors++; 384 return cmd; 385 } 386 387 dev_dbg(nbd_to_dev(nbd), "request %p: got reply\n", cmd); 388 if (rq_data_dir(req) != WRITE) { 389 struct req_iterator iter; 390 struct bio_vec bvec; 391 392 rq_for_each_segment(bvec, req, iter) { 393 result = sock_recv_bvec(nbd, &bvec); 394 if (result <= 0) { 395 dev_err(disk_to_dev(nbd->disk), "Receive data failed (result %d)\n", 396 result); 397 req->errors++; 398 return cmd; 399 } 400 dev_dbg(nbd_to_dev(nbd), "request %p: got %d bytes data\n", 401 cmd, bvec.bv_len); 402 } 403 } 404 return cmd; 405 } 406 407 static ssize_t pid_show(struct device *dev, 408 struct device_attribute *attr, char *buf) 409 { 410 struct gendisk *disk = dev_to_disk(dev); 411 struct nbd_device *nbd = (struct nbd_device *)disk->private_data; 412 413 return sprintf(buf, "%d\n", task_pid_nr(nbd->task_recv)); 414 } 415 416 static struct device_attribute pid_attr = { 417 .attr = { .name = "pid", .mode = S_IRUGO}, 418 .show = pid_show, 419 }; 420 421 static int nbd_thread_recv(struct nbd_device *nbd, struct block_device *bdev) 422 { 423 struct nbd_cmd *cmd; 424 int ret; 425 426 BUG_ON(nbd->magic != NBD_MAGIC); 427 428 sk_set_memalloc(nbd->sock->sk); 429 430 ret = device_create_file(disk_to_dev(nbd->disk), &pid_attr); 431 if (ret) { 432 dev_err(disk_to_dev(nbd->disk), "device_create_file failed!\n"); 433 return ret; 434 } 435 436 nbd_size_update(nbd, bdev); 437 438 while (1) { 439 cmd = nbd_read_stat(nbd); 440 if (IS_ERR(cmd)) { 441 ret = PTR_ERR(cmd); 442 break; 443 } 444 445 nbd_end_request(cmd); 446 } 447 448 nbd_size_clear(nbd, bdev); 449 450 device_remove_file(disk_to_dev(nbd->disk), &pid_attr); 451 return ret; 452 } 453 454 static void nbd_clear_req(struct request *req, void *data, bool reserved) 455 { 456 struct nbd_cmd *cmd; 457 458 if (!blk_mq_request_started(req)) 459 return; 460 cmd = blk_mq_rq_to_pdu(req); 461 req->errors++; 462 nbd_end_request(cmd); 463 } 464 465 static void nbd_clear_que(struct nbd_device *nbd) 466 { 467 BUG_ON(nbd->magic != NBD_MAGIC); 468 469 /* 470 * Because we have set nbd->sock to NULL under the tx_lock, all 471 * modifications to the list must have completed by now. 472 */ 473 BUG_ON(nbd->sock); 474 475 blk_mq_tagset_busy_iter(&nbd->tag_set, nbd_clear_req, NULL); 476 dev_dbg(disk_to_dev(nbd->disk), "queue cleared\n"); 477 } 478 479 480 static void nbd_handle_cmd(struct nbd_cmd *cmd) 481 { 482 struct request *req = blk_mq_rq_from_pdu(cmd); 483 struct nbd_device *nbd = cmd->nbd; 484 485 if (req->cmd_type != REQ_TYPE_FS) 486 goto error_out; 487 488 if (rq_data_dir(req) == WRITE && 489 (nbd->flags & NBD_FLAG_READ_ONLY)) { 490 dev_err(disk_to_dev(nbd->disk), 491 "Write on read-only\n"); 492 goto error_out; 493 } 494 495 req->errors = 0; 496 497 mutex_lock(&nbd->tx_lock); 498 nbd->task_send = current; 499 if (unlikely(!nbd->sock)) { 500 mutex_unlock(&nbd->tx_lock); 501 dev_err(disk_to_dev(nbd->disk), 502 "Attempted send on closed socket\n"); 503 goto error_out; 504 } 505 506 if (nbd_send_cmd(nbd, cmd) != 0) { 507 dev_err(disk_to_dev(nbd->disk), "Request send failed\n"); 508 req->errors++; 509 nbd_end_request(cmd); 510 } 511 512 nbd->task_send = NULL; 513 mutex_unlock(&nbd->tx_lock); 514 515 return; 516 517 error_out: 518 req->errors++; 519 nbd_end_request(cmd); 520 } 521 522 static int nbd_queue_rq(struct blk_mq_hw_ctx *hctx, 523 const struct blk_mq_queue_data *bd) 524 { 525 struct nbd_cmd *cmd = blk_mq_rq_to_pdu(bd->rq); 526 527 blk_mq_start_request(bd->rq); 528 nbd_handle_cmd(cmd); 529 return BLK_MQ_RQ_QUEUE_OK; 530 } 531 532 static int nbd_set_socket(struct nbd_device *nbd, struct socket *sock) 533 { 534 int ret = 0; 535 536 spin_lock_irq(&nbd->sock_lock); 537 538 if (nbd->sock) { 539 ret = -EBUSY; 540 goto out; 541 } 542 543 nbd->sock = sock; 544 545 out: 546 spin_unlock_irq(&nbd->sock_lock); 547 548 return ret; 549 } 550 551 /* Reset all properties of an NBD device */ 552 static void nbd_reset(struct nbd_device *nbd) 553 { 554 nbd->runtime_flags = 0; 555 nbd->blksize = 1024; 556 nbd->bytesize = 0; 557 set_capacity(nbd->disk, 0); 558 nbd->flags = 0; 559 nbd->tag_set.timeout = 0; 560 queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, nbd->disk->queue); 561 } 562 563 static void nbd_bdev_reset(struct block_device *bdev) 564 { 565 set_device_ro(bdev, false); 566 bdev->bd_inode->i_size = 0; 567 if (max_part > 0) { 568 blkdev_reread_part(bdev); 569 bdev->bd_invalidated = 1; 570 } 571 } 572 573 static void nbd_parse_flags(struct nbd_device *nbd, struct block_device *bdev) 574 { 575 if (nbd->flags & NBD_FLAG_READ_ONLY) 576 set_device_ro(bdev, true); 577 if (nbd->flags & NBD_FLAG_SEND_TRIM) 578 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, nbd->disk->queue); 579 if (nbd->flags & NBD_FLAG_SEND_FLUSH) 580 blk_queue_write_cache(nbd->disk->queue, true, false); 581 else 582 blk_queue_write_cache(nbd->disk->queue, false, false); 583 } 584 585 static int nbd_dev_dbg_init(struct nbd_device *nbd); 586 static void nbd_dev_dbg_close(struct nbd_device *nbd); 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 if (!nbd->sock) 599 return -EINVAL; 600 601 sreq = blk_mq_alloc_request(bdev_get_queue(bdev), WRITE, 0); 602 if (!sreq) 603 return -ENOMEM; 604 605 mutex_unlock(&nbd->tx_lock); 606 fsync_bdev(bdev); 607 mutex_lock(&nbd->tx_lock); 608 sreq->cmd_type = REQ_TYPE_DRV_PRIV; 609 610 /* Check again after getting mutex back. */ 611 if (!nbd->sock) { 612 blk_mq_free_request(sreq); 613 return -EINVAL; 614 } 615 616 set_bit(NBD_DISCONNECT_REQUESTED, &nbd->runtime_flags); 617 618 nbd_send_cmd(nbd, blk_mq_rq_to_pdu(sreq)); 619 blk_mq_free_request(sreq); 620 return 0; 621 } 622 623 case NBD_CLEAR_SOCK: 624 sock_shutdown(nbd); 625 nbd_clear_que(nbd); 626 kill_bdev(bdev); 627 return 0; 628 629 case NBD_SET_SOCK: { 630 int err; 631 struct socket *sock = sockfd_lookup(arg, &err); 632 633 if (!sock) 634 return err; 635 636 err = nbd_set_socket(nbd, sock); 637 if (!err && max_part) 638 bdev->bd_invalidated = 1; 639 640 return err; 641 } 642 643 case NBD_SET_BLKSIZE: { 644 loff_t bsize = div_s64(nbd->bytesize, arg); 645 646 return nbd_size_set(nbd, bdev, arg, bsize); 647 } 648 649 case NBD_SET_SIZE: 650 return nbd_size_set(nbd, bdev, nbd->blksize, 651 arg / nbd->blksize); 652 653 case NBD_SET_SIZE_BLOCKS: 654 return nbd_size_set(nbd, bdev, nbd->blksize, arg); 655 656 case NBD_SET_TIMEOUT: 657 nbd->tag_set.timeout = arg * HZ; 658 return 0; 659 660 case NBD_SET_FLAGS: 661 nbd->flags = arg; 662 return 0; 663 664 case NBD_DO_IT: { 665 int error; 666 667 if (nbd->task_recv) 668 return -EBUSY; 669 if (!nbd->sock) 670 return -EINVAL; 671 672 /* We have to claim the device under the lock */ 673 nbd->task_recv = current; 674 mutex_unlock(&nbd->tx_lock); 675 676 nbd_parse_flags(nbd, bdev); 677 678 nbd_dev_dbg_init(nbd); 679 error = nbd_thread_recv(nbd, bdev); 680 nbd_dev_dbg_close(nbd); 681 682 mutex_lock(&nbd->tx_lock); 683 nbd->task_recv = NULL; 684 685 sock_shutdown(nbd); 686 nbd_clear_que(nbd); 687 kill_bdev(bdev); 688 nbd_bdev_reset(bdev); 689 690 /* user requested, ignore socket errors */ 691 if (test_bit(NBD_DISCONNECT_REQUESTED, &nbd->runtime_flags)) 692 error = 0; 693 if (test_bit(NBD_TIMEDOUT, &nbd->runtime_flags)) 694 error = -ETIMEDOUT; 695 696 nbd_reset(nbd); 697 698 return error; 699 } 700 701 case NBD_CLEAR_QUE: 702 /* 703 * This is for compatibility only. The queue is always cleared 704 * by NBD_DO_IT or NBD_CLEAR_SOCK. 705 */ 706 return 0; 707 708 case NBD_PRINT_DEBUG: 709 /* 710 * For compatibility only, we no longer keep a list of 711 * outstanding requests. 712 */ 713 return 0; 714 } 715 return -ENOTTY; 716 } 717 718 static int nbd_ioctl(struct block_device *bdev, fmode_t mode, 719 unsigned int cmd, unsigned long arg) 720 { 721 struct nbd_device *nbd = bdev->bd_disk->private_data; 722 int error; 723 724 if (!capable(CAP_SYS_ADMIN)) 725 return -EPERM; 726 727 BUG_ON(nbd->magic != NBD_MAGIC); 728 729 mutex_lock(&nbd->tx_lock); 730 error = __nbd_ioctl(bdev, nbd, cmd, arg); 731 mutex_unlock(&nbd->tx_lock); 732 733 return error; 734 } 735 736 static const struct block_device_operations nbd_fops = 737 { 738 .owner = THIS_MODULE, 739 .ioctl = nbd_ioctl, 740 .compat_ioctl = nbd_ioctl, 741 }; 742 743 #if IS_ENABLED(CONFIG_DEBUG_FS) 744 745 static int nbd_dbg_tasks_show(struct seq_file *s, void *unused) 746 { 747 struct nbd_device *nbd = s->private; 748 749 if (nbd->task_recv) 750 seq_printf(s, "recv: %d\n", task_pid_nr(nbd->task_recv)); 751 if (nbd->task_send) 752 seq_printf(s, "send: %d\n", task_pid_nr(nbd->task_send)); 753 754 return 0; 755 } 756 757 static int nbd_dbg_tasks_open(struct inode *inode, struct file *file) 758 { 759 return single_open(file, nbd_dbg_tasks_show, inode->i_private); 760 } 761 762 static const struct file_operations nbd_dbg_tasks_ops = { 763 .open = nbd_dbg_tasks_open, 764 .read = seq_read, 765 .llseek = seq_lseek, 766 .release = single_release, 767 }; 768 769 static int nbd_dbg_flags_show(struct seq_file *s, void *unused) 770 { 771 struct nbd_device *nbd = s->private; 772 u32 flags = nbd->flags; 773 774 seq_printf(s, "Hex: 0x%08x\n\n", flags); 775 776 seq_puts(s, "Known flags:\n"); 777 778 if (flags & NBD_FLAG_HAS_FLAGS) 779 seq_puts(s, "NBD_FLAG_HAS_FLAGS\n"); 780 if (flags & NBD_FLAG_READ_ONLY) 781 seq_puts(s, "NBD_FLAG_READ_ONLY\n"); 782 if (flags & NBD_FLAG_SEND_FLUSH) 783 seq_puts(s, "NBD_FLAG_SEND_FLUSH\n"); 784 if (flags & NBD_FLAG_SEND_TRIM) 785 seq_puts(s, "NBD_FLAG_SEND_TRIM\n"); 786 787 return 0; 788 } 789 790 static int nbd_dbg_flags_open(struct inode *inode, struct file *file) 791 { 792 return single_open(file, nbd_dbg_flags_show, inode->i_private); 793 } 794 795 static const struct file_operations nbd_dbg_flags_ops = { 796 .open = nbd_dbg_flags_open, 797 .read = seq_read, 798 .llseek = seq_lseek, 799 .release = single_release, 800 }; 801 802 static int nbd_dev_dbg_init(struct nbd_device *nbd) 803 { 804 struct dentry *dir; 805 806 if (!nbd_dbg_dir) 807 return -EIO; 808 809 dir = debugfs_create_dir(nbd_name(nbd), nbd_dbg_dir); 810 if (!dir) { 811 dev_err(nbd_to_dev(nbd), "Failed to create debugfs dir for '%s'\n", 812 nbd_name(nbd)); 813 return -EIO; 814 } 815 nbd->dbg_dir = dir; 816 817 debugfs_create_file("tasks", 0444, dir, nbd, &nbd_dbg_tasks_ops); 818 debugfs_create_u64("size_bytes", 0444, dir, &nbd->bytesize); 819 debugfs_create_u32("timeout", 0444, dir, &nbd->tag_set.timeout); 820 debugfs_create_u32("blocksize", 0444, dir, &nbd->blksize); 821 debugfs_create_file("flags", 0444, dir, nbd, &nbd_dbg_flags_ops); 822 823 return 0; 824 } 825 826 static void nbd_dev_dbg_close(struct nbd_device *nbd) 827 { 828 debugfs_remove_recursive(nbd->dbg_dir); 829 } 830 831 static int nbd_dbg_init(void) 832 { 833 struct dentry *dbg_dir; 834 835 dbg_dir = debugfs_create_dir("nbd", NULL); 836 if (!dbg_dir) 837 return -EIO; 838 839 nbd_dbg_dir = dbg_dir; 840 841 return 0; 842 } 843 844 static void nbd_dbg_close(void) 845 { 846 debugfs_remove_recursive(nbd_dbg_dir); 847 } 848 849 #else /* IS_ENABLED(CONFIG_DEBUG_FS) */ 850 851 static int nbd_dev_dbg_init(struct nbd_device *nbd) 852 { 853 return 0; 854 } 855 856 static void nbd_dev_dbg_close(struct nbd_device *nbd) 857 { 858 } 859 860 static int nbd_dbg_init(void) 861 { 862 return 0; 863 } 864 865 static void nbd_dbg_close(void) 866 { 867 } 868 869 #endif 870 871 static int nbd_init_request(void *data, struct request *rq, 872 unsigned int hctx_idx, unsigned int request_idx, 873 unsigned int numa_node) 874 { 875 struct nbd_cmd *cmd = blk_mq_rq_to_pdu(rq); 876 877 cmd->nbd = data; 878 INIT_LIST_HEAD(&cmd->list); 879 return 0; 880 } 881 882 static struct blk_mq_ops nbd_mq_ops = { 883 .queue_rq = nbd_queue_rq, 884 .init_request = nbd_init_request, 885 .timeout = nbd_xmit_timeout, 886 }; 887 888 /* 889 * And here should be modules and kernel interface 890 * (Just smiley confuses emacs :-) 891 */ 892 893 static int __init nbd_init(void) 894 { 895 int err = -ENOMEM; 896 int i; 897 int part_shift; 898 899 BUILD_BUG_ON(sizeof(struct nbd_request) != 28); 900 901 if (max_part < 0) { 902 printk(KERN_ERR "nbd: max_part must be >= 0\n"); 903 return -EINVAL; 904 } 905 906 part_shift = 0; 907 if (max_part > 0) { 908 part_shift = fls(max_part); 909 910 /* 911 * Adjust max_part according to part_shift as it is exported 912 * to user space so that user can know the max number of 913 * partition kernel should be able to manage. 914 * 915 * Note that -1 is required because partition 0 is reserved 916 * for the whole disk. 917 */ 918 max_part = (1UL << part_shift) - 1; 919 } 920 921 if ((1UL << part_shift) > DISK_MAX_PARTS) 922 return -EINVAL; 923 924 if (nbds_max > 1UL << (MINORBITS - part_shift)) 925 return -EINVAL; 926 927 nbd_dev = kcalloc(nbds_max, sizeof(*nbd_dev), GFP_KERNEL); 928 if (!nbd_dev) 929 return -ENOMEM; 930 931 for (i = 0; i < nbds_max; i++) { 932 struct gendisk *disk = alloc_disk(1 << part_shift); 933 if (!disk) 934 goto out; 935 nbd_dev[i].disk = disk; 936 937 nbd_dev[i].tag_set.ops = &nbd_mq_ops; 938 nbd_dev[i].tag_set.nr_hw_queues = 1; 939 nbd_dev[i].tag_set.queue_depth = 128; 940 nbd_dev[i].tag_set.numa_node = NUMA_NO_NODE; 941 nbd_dev[i].tag_set.cmd_size = sizeof(struct nbd_cmd); 942 nbd_dev[i].tag_set.flags = BLK_MQ_F_SHOULD_MERGE | 943 BLK_MQ_F_SG_MERGE | BLK_MQ_F_BLOCKING; 944 nbd_dev[i].tag_set.driver_data = &nbd_dev[i]; 945 946 err = blk_mq_alloc_tag_set(&nbd_dev[i].tag_set); 947 if (err) { 948 put_disk(disk); 949 goto out; 950 } 951 952 /* 953 * The new linux 2.5 block layer implementation requires 954 * every gendisk to have its very own request_queue struct. 955 * These structs are big so we dynamically allocate them. 956 */ 957 disk->queue = blk_mq_init_queue(&nbd_dev[i].tag_set); 958 if (!disk->queue) { 959 blk_mq_free_tag_set(&nbd_dev[i].tag_set); 960 put_disk(disk); 961 goto out; 962 } 963 964 /* 965 * Tell the block layer that we are not a rotational device 966 */ 967 queue_flag_set_unlocked(QUEUE_FLAG_NONROT, disk->queue); 968 queue_flag_clear_unlocked(QUEUE_FLAG_ADD_RANDOM, disk->queue); 969 disk->queue->limits.discard_granularity = 512; 970 blk_queue_max_discard_sectors(disk->queue, UINT_MAX); 971 disk->queue->limits.discard_zeroes_data = 0; 972 blk_queue_max_hw_sectors(disk->queue, 65536); 973 disk->queue->limits.max_sectors = 256; 974 } 975 976 if (register_blkdev(NBD_MAJOR, "nbd")) { 977 err = -EIO; 978 goto out; 979 } 980 981 printk(KERN_INFO "nbd: registered device at major %d\n", NBD_MAJOR); 982 983 nbd_dbg_init(); 984 985 for (i = 0; i < nbds_max; i++) { 986 struct gendisk *disk = nbd_dev[i].disk; 987 nbd_dev[i].magic = NBD_MAGIC; 988 spin_lock_init(&nbd_dev[i].sock_lock); 989 mutex_init(&nbd_dev[i].tx_lock); 990 disk->major = NBD_MAJOR; 991 disk->first_minor = i << part_shift; 992 disk->fops = &nbd_fops; 993 disk->private_data = &nbd_dev[i]; 994 sprintf(disk->disk_name, "nbd%d", i); 995 nbd_reset(&nbd_dev[i]); 996 add_disk(disk); 997 } 998 999 return 0; 1000 out: 1001 while (i--) { 1002 blk_mq_free_tag_set(&nbd_dev[i].tag_set); 1003 blk_cleanup_queue(nbd_dev[i].disk->queue); 1004 put_disk(nbd_dev[i].disk); 1005 } 1006 kfree(nbd_dev); 1007 return err; 1008 } 1009 1010 static void __exit nbd_cleanup(void) 1011 { 1012 int i; 1013 1014 nbd_dbg_close(); 1015 1016 for (i = 0; i < nbds_max; i++) { 1017 struct gendisk *disk = nbd_dev[i].disk; 1018 nbd_dev[i].magic = 0; 1019 if (disk) { 1020 del_gendisk(disk); 1021 blk_cleanup_queue(disk->queue); 1022 blk_mq_free_tag_set(&nbd_dev[i].tag_set); 1023 put_disk(disk); 1024 } 1025 } 1026 unregister_blkdev(NBD_MAJOR, "nbd"); 1027 kfree(nbd_dev); 1028 printk(KERN_INFO "nbd: unregistered device at major %d\n", NBD_MAJOR); 1029 } 1030 1031 module_init(nbd_init); 1032 module_exit(nbd_cleanup); 1033 1034 MODULE_DESCRIPTION("Network Block Device"); 1035 MODULE_LICENSE("GPL"); 1036 1037 module_param(nbds_max, int, 0444); 1038 MODULE_PARM_DESC(nbds_max, "number of network block devices to initialize (default: 16)"); 1039 module_param(max_part, int, 0444); 1040 MODULE_PARM_DESC(max_part, "number of partitions per device (default: 0)"); 1041