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