drivers/block/nbd.c

   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, &current->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