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@suse.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/compiler.h>
  28 #include <linux/err.h>
  29 #include <linux/kernel.h>
  30 #include <linux/slab.h>
  31 #include <net/sock.h>
  32 #include <linux/net.h>
  33 #include <linux/kthread.h>
  34
  35 #include <asm/uaccess.h>
  36 #include <asm/system.h>
  37 #include <asm/types.h>
  38
  39 #include <linux/nbd.h>
  40
  41 #define LO_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_DO_IT: return "do-it";
  82         case NBD_CLEAR_SOCK: return "clear-sock";
  83         case NBD_CLEAR_QUE: return "clear-que";
  84         case NBD_PRINT_DEBUG: return "print-debug";
  85         case NBD_SET_SIZE_BLOCKS: return "set-size-blocks";
  86         case NBD_DISCONNECT: return "disconnect";
  87         case BLKROSET: return "set-read-only";
  88         case BLKFLSBUF: return "flush-buffer-cache";
  89         }
  90         return "unknown";
  91 }
  92
  93 static const char *nbdcmd_to_ascii(int cmd)
  94 {
  95         switch (cmd) {
  96         case  NBD_CMD_READ: return "read";
  97         case NBD_CMD_WRITE: return "write";
  98         case  NBD_CMD_DISC: return "disconnect";
  99         }
 100         return "invalid";
 101 }
 102 #endif /* NDEBUG */
 103
 104 static void nbd_end_request(struct request *req)
 105 {
 106         int error = req->errors ? -EIO : 0;
 107         struct request_queue *q = req->q;
 108         unsigned long flags;
 109
 110         dprintk(DBG_BLKDEV, "%s: request %p: %s\n", req->rq_disk->disk_name,
 111                         req, error ? "failed" : "done");
 112
 113         spin_lock_irqsave(q->queue_lock, flags);
 114         __blk_end_request_all(req, error);
 115         spin_unlock_irqrestore(q->queue_lock, flags);
 116 }
 117
 118 static void sock_shutdown(struct nbd_device *lo, int lock)
 119 {
 120         /* Forcibly shutdown the socket causing all listeners
 121          * to error
 122          *
 123          * FIXME: This code is duplicated from sys_shutdown, but
 124          * there should be a more generic interface rather than
 125          * calling socket ops directly here */
 126         if (lock)
 127                 mutex_lock(&lo->tx_lock);
 128         if (lo->sock) {
 129                 printk(KERN_WARNING "%s: shutting down socket\n",
 130                         lo->disk->disk_name);
 131                 kernel_sock_shutdown(lo->sock, SHUT_RDWR);
 132                 lo->sock = NULL;
 133         }
 134         if (lock)
 135                 mutex_unlock(&lo->tx_lock);
 136 }
 137
 138 static void nbd_xmit_timeout(unsigned long arg)
 139 {
 140         struct task_struct *task = (struct task_struct *)arg;
 141
 142         printk(KERN_WARNING "nbd: killing hung xmit (%s, pid: %d)\n",
 143                 task->comm, task->pid);
 144         force_sig(SIGKILL, task);
 145 }
 146
 147 /*
 148  *  Send or receive packet.
 149  */
 150 static int sock_xmit(struct nbd_device *lo, int send, void *buf, int size,
 151                 int msg_flags)
 152 {
 153         struct socket *sock = lo->sock;
 154         int result;
 155         struct msghdr msg;
 156         struct kvec iov;
 157         sigset_t blocked, oldset;
 158
 159         if (unlikely(!sock)) {
 160                 printk(KERN_ERR "%s: Attempted %s on closed socket in sock_xmit\n",
 161                        lo->disk->disk_name, (send ? "send" : "recv"));
 162                 return -EINVAL;
 163         }
 164
 165         /* Allow interception of SIGKILL only
 166          * Don't allow other signals to interrupt the transmission */
 167         siginitsetinv(&blocked, sigmask(SIGKILL));
 168         sigprocmask(SIG_SETMASK, &blocked, &oldset);
 169
 170         do {
 171                 sock->sk->sk_allocation = GFP_NOIO;
 172                 iov.iov_base = buf;
 173                 iov.iov_len = size;
 174                 msg.msg_name = NULL;
 175                 msg.msg_namelen = 0;
 176                 msg.msg_control = NULL;
 177                 msg.msg_controllen = 0;
 178                 msg.msg_flags = msg_flags | MSG_NOSIGNAL;
 179
 180                 if (send) {
 181                         struct timer_list ti;
 182
 183                         if (lo->xmit_timeout) {
 184                                 init_timer(&ti);
 185                                 ti.function = nbd_xmit_timeout;
 186                                 ti.data = (unsigned long)current;
 187                                 ti.expires = jiffies + lo->xmit_timeout;
 188                                 add_timer(&ti);
 189                         }
 190                         result = kernel_sendmsg(sock, &msg, &iov, 1, size);
 191                         if (lo->xmit_timeout)
 192                                 del_timer_sync(&ti);
 193                 } else
 194                         result = kernel_recvmsg(sock, &msg, &iov, 1, size, 0);
 195
 196                 if (signal_pending(current)) {
 197                         siginfo_t info;
 198                         printk(KERN_WARNING "nbd (pid %d: %s) got signal %d\n",
 199                                 task_pid_nr(current), current->comm,
 200                                 dequeue_signal_lock(current, &current->blocked, &info));
 201                         result = -EINTR;
 202                         sock_shutdown(lo, !send);
 203                         break;
 204                 }
 205
 206                 if (result <= 0) {
 207                         if (result == 0)
 208                                 result = -EPIPE; /* short read */
 209                         break;
 210                 }
 211                 size -= result;
 212                 buf += result;
 213         } while (size > 0);
 214
 215         sigprocmask(SIG_SETMASK, &oldset, NULL);
 216
 217         return result;
 218 }
 219
 220 static inline int sock_send_bvec(struct nbd_device *lo, struct bio_vec *bvec,
 221                 int flags)
 222 {
 223         int result;
 224         void *kaddr = kmap(bvec->bv_page);
 225         result = sock_xmit(lo, 1, kaddr + bvec->bv_offset, bvec->bv_len, flags);
 226         kunmap(bvec->bv_page);
 227         return result;
 228 }
 229
 230 /* always call with the tx_lock held */
 231 static int nbd_send_req(struct nbd_device *lo, struct request *req)
 232 {
 233         int result, flags;
 234         struct nbd_request request;
 235         unsigned long size = blk_rq_bytes(req);
 236
 237         request.magic = htonl(NBD_REQUEST_MAGIC);
 238         request.type = htonl(nbd_cmd(req));
 239         request.from = cpu_to_be64((u64)blk_rq_pos(req) << 9);
 240         request.len = htonl(size);
 241         memcpy(request.handle, &req, sizeof(req));
 242
 243         dprintk(DBG_TX, "%s: request %p: sending control (%s@%llu,%uB)\n",
 244                         lo->disk->disk_name, req,
 245                         nbdcmd_to_ascii(nbd_cmd(req)),
 246                         (unsigned long long)blk_rq_pos(req) << 9,
 247                         blk_rq_bytes(req));
 248         result = sock_xmit(lo, 1, &request, sizeof(request),
 249                         (nbd_cmd(req) == NBD_CMD_WRITE) ? MSG_MORE : 0);
 250         if (result <= 0) {
 251                 printk(KERN_ERR "%s: Send control failed (result %d)\n",
 252                                 lo->disk->disk_name, result);
 253                 goto error_out;
 254         }
 255
 256         if (nbd_cmd(req) == NBD_CMD_WRITE) {
 257                 struct req_iterator iter;
 258                 struct bio_vec *bvec;
 259                 /*
 260                  * we are really probing at internals to determine
 261                  * whether to set MSG_MORE or not...
 262                  */
 263                 rq_for_each_segment(bvec, req, iter) {
 264                         flags = 0;
 265                         if (!rq_iter_last(req, iter))
 266                                 flags = MSG_MORE;
 267                         dprintk(DBG_TX, "%s: request %p: sending %d bytes data\n",
 268                                         lo->disk->disk_name, req, bvec->bv_len);
 269                         result = sock_send_bvec(lo, bvec, flags);
 270                         if (result <= 0) {
 271                                 printk(KERN_ERR "%s: Send data failed (result %d)\n",
 272                                                 lo->disk->disk_name, result);
 273                                 goto error_out;
 274                         }
 275                 }
 276         }
 277         return 0;
 278
 279 error_out:
 280         return -EIO;
 281 }
 282
 283 static struct request *nbd_find_request(struct nbd_device *lo,
 284                                         struct request *xreq)
 285 {
 286         struct request *req, *tmp;
 287         int err;
 288
 289         err = wait_event_interruptible(lo->active_wq, lo->active_req != xreq);
 290         if (unlikely(err))
 291                 goto out;
 292
 293         spin_lock(&lo->queue_lock);
 294         list_for_each_entry_safe(req, tmp, &lo->queue_head, queuelist) {
 295                 if (req != xreq)
 296                         continue;
 297                 list_del_init(&req->queuelist);
 298                 spin_unlock(&lo->queue_lock);
 299                 return req;
 300         }
 301         spin_unlock(&lo->queue_lock);
 302
 303         err = -ENOENT;
 304
 305 out:
 306         return ERR_PTR(err);
 307 }
 308
 309 static inline int sock_recv_bvec(struct nbd_device *lo, struct bio_vec *bvec)
 310 {
 311         int result;
 312         void *kaddr = kmap(bvec->bv_page);
 313         result = sock_xmit(lo, 0, kaddr + bvec->bv_offset, bvec->bv_len,
 314                         MSG_WAITALL);
 315         kunmap(bvec->bv_page);
 316         return result;
 317 }
 318
 319 /* NULL returned = something went wrong, inform userspace */
 320 static struct request *nbd_read_stat(struct nbd_device *lo)
 321 {
 322         int result;
 323         struct nbd_reply reply;
 324         struct request *req;
 325
 326         reply.magic = 0;
 327         result = sock_xmit(lo, 0, &reply, sizeof(reply), MSG_WAITALL);
 328         if (result <= 0) {
 329                 printk(KERN_ERR "%s: Receive control failed (result %d)\n",
 330                                 lo->disk->disk_name, result);
 331                 goto harderror;
 332         }
 333
 334         if (ntohl(reply.magic) != NBD_REPLY_MAGIC) {
 335                 printk(KERN_ERR "%s: Wrong magic (0x%lx)\n",
 336                                 lo->disk->disk_name,
 337                                 (unsigned long)ntohl(reply.magic));
 338                 result = -EPROTO;
 339                 goto harderror;
 340         }
 341
 342         req = nbd_find_request(lo, *(struct request **)reply.handle);
 343         if (IS_ERR(req)) {
 344                 result = PTR_ERR(req);
 345                 if (result != -ENOENT)
 346                         goto harderror;
 347
 348                 printk(KERN_ERR "%s: Unexpected reply (%p)\n",
 349                                 lo->disk->disk_name, reply.handle);
 350                 result = -EBADR;
 351                 goto harderror;
 352         }
 353
 354         if (ntohl(reply.error)) {
 355                 printk(KERN_ERR "%s: Other side returned error (%d)\n",
 356                                 lo->disk->disk_name, ntohl(reply.error));
 357                 req->errors++;
 358                 return req;
 359         }
 360
 361         dprintk(DBG_RX, "%s: request %p: got reply\n",
 362                         lo->disk->disk_name, req);
 363         if (nbd_cmd(req) == NBD_CMD_READ) {
 364                 struct req_iterator iter;
 365                 struct bio_vec *bvec;
 366
 367                 rq_for_each_segment(bvec, req, iter) {
 368                         result = sock_recv_bvec(lo, bvec);
 369                         if (result <= 0) {
 370                                 printk(KERN_ERR "%s: Receive data failed (result %d)\n",
 371                                                 lo->disk->disk_name, result);
 372                                 req->errors++;
 373                                 return req;
 374                         }
 375                         dprintk(DBG_RX, "%s: request %p: got %d bytes data\n",
 376                                 lo->disk->disk_name, req, bvec->bv_len);
 377                 }
 378         }
 379         return req;
 380 harderror:
 381         lo->harderror = result;
 382         return NULL;
 383 }
 384
 385 static ssize_t pid_show(struct device *dev,
 386                         struct device_attribute *attr, char *buf)
 387 {
 388         struct gendisk *disk = dev_to_disk(dev);
 389
 390         return sprintf(buf, "%ld\n",
 391                 (long) ((struct nbd_device *)disk->private_data)->pid);
 392 }
 393
 394 static struct device_attribute pid_attr = {
 395         .attr = { .name = "pid", .mode = S_IRUGO},
 396         .show = pid_show,
 397 };
 398
 399 static int nbd_do_it(struct nbd_device *lo)
 400 {
 401         struct request *req;
 402         int ret;
 403
 404         BUG_ON(lo->magic != LO_MAGIC);
 405
 406         lo->pid = current->pid;
 407         ret = sysfs_create_file(&disk_to_dev(lo->disk)->kobj, &pid_attr.attr);
 408         if (ret) {
 409                 printk(KERN_ERR "nbd: sysfs_create_file failed!");
 410                 lo->pid = 0;
 411                 return ret;
 412         }
 413
 414         while ((req = nbd_read_stat(lo)) != NULL)
 415                 nbd_end_request(req);
 416
 417         sysfs_remove_file(&disk_to_dev(lo->disk)->kobj, &pid_attr.attr);
 418         lo->pid = 0;
 419         return 0;
 420 }
 421
 422 static void nbd_clear_que(struct nbd_device *lo)
 423 {
 424         struct request *req;
 425
 426         BUG_ON(lo->magic != LO_MAGIC);
 427
 428         /*
 429          * Because we have set lo->sock to NULL under the tx_lock, all
 430          * modifications to the list must have completed by now.  For
 431          * the same reason, the active_req must be NULL.
 432          *
 433          * As a consequence, we don't need to take the spin lock while
 434          * purging the list here.
 435          */
 436         BUG_ON(lo->sock);
 437         BUG_ON(lo->active_req);
 438
 439         while (!list_empty(&lo->queue_head)) {
 440                 req = list_entry(lo->queue_head.next, struct request,
 441                                  queuelist);
 442                 list_del_init(&req->queuelist);
 443                 req->errors++;
 444                 nbd_end_request(req);
 445         }
 446 }
 447
 448
 449 static void nbd_handle_req(struct nbd_device *lo, struct request *req)
 450 {
 451         if (!blk_fs_request(req))
 452                 goto error_out;
 453
 454         nbd_cmd(req) = NBD_CMD_READ;
 455         if (rq_data_dir(req) == WRITE) {
 456                 nbd_cmd(req) = NBD_CMD_WRITE;
 457                 if (lo->flags & NBD_READ_ONLY) {
 458                         printk(KERN_ERR "%s: Write on read-only\n",
 459                                         lo->disk->disk_name);
 460                         goto error_out;
 461                 }
 462         }
 463
 464         req->errors = 0;
 465
 466         mutex_lock(&lo->tx_lock);
 467         if (unlikely(!lo->sock)) {
 468                 mutex_unlock(&lo->tx_lock);
 469                 printk(KERN_ERR "%s: Attempted send on closed socket\n",
 470                        lo->disk->disk_name);
 471                 goto error_out;
 472         }
 473
 474         lo->active_req = req;
 475
 476         if (nbd_send_req(lo, req) != 0) {
 477                 printk(KERN_ERR "%s: Request send failed\n",
 478                                 lo->disk->disk_name);
 479                 req->errors++;
 480                 nbd_end_request(req);
 481         } else {
 482                 spin_lock(&lo->queue_lock);
 483                 list_add(&req->queuelist, &lo->queue_head);
 484                 spin_unlock(&lo->queue_lock);
 485         }
 486
 487         lo->active_req = NULL;
 488         mutex_unlock(&lo->tx_lock);
 489         wake_up_all(&lo->active_wq);
 490
 491         return;
 492
 493 error_out:
 494         req->errors++;
 495         nbd_end_request(req);
 496 }
 497
 498 static int nbd_thread(void *data)
 499 {
 500         struct nbd_device *lo = data;
 501         struct request *req;
 502
 503         set_user_nice(current, -20);
 504         while (!kthread_should_stop() || !list_empty(&lo->waiting_queue)) {
 505                 /* wait for something to do */
 506                 wait_event_interruptible(lo->waiting_wq,
 507                                          kthread_should_stop() ||
 508                                          !list_empty(&lo->waiting_queue));
 509
 510                 /* extract request */
 511                 if (list_empty(&lo->waiting_queue))
 512                         continue;
 513
 514                 spin_lock_irq(&lo->queue_lock);
 515                 req = list_entry(lo->waiting_queue.next, struct request,
 516                                  queuelist);
 517                 list_del_init(&req->queuelist);
 518                 spin_unlock_irq(&lo->queue_lock);
 519
 520                 /* handle request */
 521                 nbd_handle_req(lo, req);
 522         }
 523         return 0;
 524 }
 525
 526 /*
 527  * We always wait for result of write, for now. It would be nice to make it optional
 528  * in future
 529  * if ((rq_data_dir(req) == WRITE) && (lo->flags & NBD_WRITE_NOCHK))
 530  *   { printk( "Warning: Ignoring result!\n"); nbd_end_request( req ); }
 531  */
 532
 533 static void do_nbd_request(struct request_queue *q)
 534 {
 535         struct request *req;
 536
 537         while ((req = blk_fetch_request(q)) != NULL) {
 538                 struct nbd_device *lo;
 539
 540                 spin_unlock_irq(q->queue_lock);
 541
 542                 dprintk(DBG_BLKDEV, "%s: request %p: dequeued (flags=%x)\n",
 543                                 req->rq_disk->disk_name, req, req->cmd_type);
 544
 545                 lo = req->rq_disk->private_data;
 546
 547                 BUG_ON(lo->magic != LO_MAGIC);
 548
 549                 if (unlikely(!lo->sock)) {
 550                         printk(KERN_ERR "%s: Attempted send on closed socket\n",
 551                                 lo->disk->disk_name);
 552                         req->errors++;
 553                         nbd_end_request(req);
 554                         spin_lock_irq(q->queue_lock);
 555                         continue;
 556                 }
 557
 558                 spin_lock_irq(&lo->queue_lock);
 559                 list_add_tail(&req->queuelist, &lo->waiting_queue);
 560                 spin_unlock_irq(&lo->queue_lock);
 561
 562                 wake_up(&lo->waiting_wq);
 563
 564                 spin_lock_irq(q->queue_lock);
 565         }
 566 }
 567
 568 /* Must be called with tx_lock held */
 569
 570 static int __nbd_ioctl(struct block_device *bdev, struct nbd_device *lo,
 571                        unsigned int cmd, unsigned long arg)
 572 {
 573         switch (cmd) {
 574         case NBD_DISCONNECT: {
 575                 struct request sreq;
 576
 577                 printk(KERN_INFO "%s: NBD_DISCONNECT\n", lo->disk->disk_name);
 578
 579                 blk_rq_init(NULL, &sreq);
 580                 sreq.cmd_type = REQ_TYPE_SPECIAL;
 581                 nbd_cmd(&sreq) = NBD_CMD_DISC;
 582                 if (!lo->sock)
 583                         return -EINVAL;
 584                 nbd_send_req(lo, &sreq);
 585                 return 0;
 586         }
 587
 588         case NBD_CLEAR_SOCK: {
 589                 struct file *file;
 590
 591                 lo->sock = NULL;
 592                 file = lo->file;
 593                 lo->file = NULL;
 594                 nbd_clear_que(lo);
 595                 BUG_ON(!list_empty(&lo->queue_head));
 596                 if (file)
 597                         fput(file);
 598                 return 0;
 599         }
 600
 601         case NBD_SET_SOCK: {
 602                 struct file *file;
 603                 if (lo->file)
 604                         return -EBUSY;
 605                 file = fget(arg);
 606                 if (file) {
 607                         struct inode *inode = file->f_path.dentry->d_inode;
 608                         if (S_ISSOCK(inode->i_mode)) {
 609                                 lo->file = file;
 610                                 lo->sock = SOCKET_I(inode);
 611                                 if (max_part > 0)
 612                                         bdev->bd_invalidated = 1;
 613                                 return 0;
 614                         } else {
 615                                 fput(file);
 616                         }
 617                 }
 618                 return -EINVAL;
 619         }
 620
 621         case NBD_SET_BLKSIZE:
 622                 lo->blksize = arg;
 623                 lo->bytesize &= ~(lo->blksize-1);
 624                 bdev->bd_inode->i_size = lo->bytesize;
 625                 set_blocksize(bdev, lo->blksize);
 626                 set_capacity(lo->disk, lo->bytesize >> 9);
 627                 return 0;
 628
 629         case NBD_SET_SIZE:
 630                 lo->bytesize = arg & ~(lo->blksize-1);
 631                 bdev->bd_inode->i_size = lo->bytesize;
 632                 set_blocksize(bdev, lo->blksize);
 633                 set_capacity(lo->disk, lo->bytesize >> 9);
 634                 return 0;
 635
 636         case NBD_SET_TIMEOUT:
 637                 lo->xmit_timeout = arg * HZ;
 638                 return 0;
 639
 640         case NBD_SET_SIZE_BLOCKS:
 641                 lo->bytesize = ((u64) arg) * lo->blksize;
 642                 bdev->bd_inode->i_size = lo->bytesize;
 643                 set_blocksize(bdev, lo->blksize);
 644                 set_capacity(lo->disk, lo->bytesize >> 9);
 645                 return 0;
 646
 647         case NBD_DO_IT: {
 648                 struct task_struct *thread;
 649                 struct file *file;
 650                 int error;
 651
 652                 if (lo->pid)
 653                         return -EBUSY;
 654                 if (!lo->file)
 655                         return -EINVAL;
 656
 657                 mutex_unlock(&lo->tx_lock);
 658
 659                 thread = kthread_create(nbd_thread, lo, lo->disk->disk_name);
 660                 if (IS_ERR(thread)) {
 661                         mutex_lock(&lo->tx_lock);
 662                         return PTR_ERR(thread);
 663                 }
 664                 wake_up_process(thread);
 665                 error = nbd_do_it(lo);
 666                 kthread_stop(thread);
 667
 668                 mutex_lock(&lo->tx_lock);
 669                 if (error)
 670                         return error;
 671                 sock_shutdown(lo, 0);
 672                 file = lo->file;
 673                 lo->file = NULL;
 674                 nbd_clear_que(lo);
 675                 printk(KERN_WARNING "%s: queue cleared\n", lo->disk->disk_name);
 676                 if (file)
 677                         fput(file);
 678                 lo->bytesize = 0;
 679                 bdev->bd_inode->i_size = 0;
 680                 set_capacity(lo->disk, 0);
 681                 if (max_part > 0)
 682                         ioctl_by_bdev(bdev, BLKRRPART, 0);
 683                 return lo->harderror;
 684         }
 685
 686         case NBD_CLEAR_QUE:
 687                 /*
 688                  * This is for compatibility only.  The queue is always cleared
 689                  * by NBD_DO_IT or NBD_CLEAR_SOCK.
 690                  */
 691                 BUG_ON(!lo->sock && !list_empty(&lo->queue_head));
 692                 return 0;
 693
 694         case NBD_PRINT_DEBUG:
 695                 printk(KERN_INFO "%s: next = %p, prev = %p, head = %p\n",
 696                         bdev->bd_disk->disk_name,
 697                         lo->queue_head.next, lo->queue_head.prev,
 698                         &lo->queue_head);
 699                 return 0;
 700         }
 701         return -ENOTTY;
 702 }
 703
 704 static int nbd_ioctl(struct block_device *bdev, fmode_t mode,
 705                      unsigned int cmd, unsigned long arg)
 706 {
 707         struct nbd_device *lo = bdev->bd_disk->private_data;
 708         int error;
 709
 710         if (!capable(CAP_SYS_ADMIN))
 711                 return -EPERM;
 712
 713         BUG_ON(lo->magic != LO_MAGIC);
 714
 715         /* Anyone capable of this syscall can do *real bad* things */
 716         dprintk(DBG_IOCTL, "%s: nbd_ioctl cmd=%s(0x%x) arg=%lu\n",
 717                         lo->disk->disk_name, ioctl_cmd_to_ascii(cmd), cmd, arg);
 718
 719         mutex_lock(&lo->tx_lock);
 720         error = __nbd_ioctl(bdev, lo, cmd, arg);
 721         mutex_unlock(&lo->tx_lock);
 722
 723         return error;
 724 }
 725
 726 static const struct block_device_operations nbd_fops =
 727 {
 728         .owner =        THIS_MODULE,
 729         .locked_ioctl = nbd_ioctl,
 730 };
 731
 732 /*
 733  * And here should be modules and kernel interface
 734  *  (Just smiley confuses emacs :-)
 735  */
 736
 737 static int __init nbd_init(void)
 738 {
 739         int err = -ENOMEM;
 740         int i;
 741         int part_shift;
 742
 743         BUILD_BUG_ON(sizeof(struct nbd_request) != 28);
 744
 745         if (max_part < 0) {
 746                 printk(KERN_CRIT "nbd: max_part must be >= 0\n");
 747                 return -EINVAL;
 748         }
 749
 750         nbd_dev = kcalloc(nbds_max, sizeof(*nbd_dev), GFP_KERNEL);
 751         if (!nbd_dev)
 752                 return -ENOMEM;
 753
 754         part_shift = 0;
 755         if (max_part > 0)
 756                 part_shift = fls(max_part);
 757
 758         for (i = 0; i < nbds_max; i++) {
 759                 struct gendisk *disk = alloc_disk(1 << part_shift);
 760                 if (!disk)
 761                         goto out;
 762                 nbd_dev[i].disk = disk;
 763                 /*
 764                  * The new linux 2.5 block layer implementation requires
 765                  * every gendisk to have its very own request_queue struct.
 766                  * These structs are big so we dynamically allocate them.
 767                  */
 768                 disk->queue = blk_init_queue(do_nbd_request, &nbd_lock);
 769                 if (!disk->queue) {
 770                         put_disk(disk);
 771                         goto out;
 772                 }
 773                 /*
 774                  * Tell the block layer that we are not a rotational device
 775                  */
 776                 queue_flag_set_unlocked(QUEUE_FLAG_NONROT, disk->queue);
 777         }
 778
 779         if (register_blkdev(NBD_MAJOR, "nbd")) {
 780                 err = -EIO;
 781                 goto out;
 782         }
 783
 784         printk(KERN_INFO "nbd: registered device at major %d\n", NBD_MAJOR);
 785         dprintk(DBG_INIT, "nbd: debugflags=0x%x\n", debugflags);
 786
 787         for (i = 0; i < nbds_max; i++) {
 788                 struct gendisk *disk = nbd_dev[i].disk;
 789                 nbd_dev[i].file = NULL;
 790                 nbd_dev[i].magic = LO_MAGIC;
 791                 nbd_dev[i].flags = 0;
 792                 INIT_LIST_HEAD(&nbd_dev[i].waiting_queue);
 793                 spin_lock_init(&nbd_dev[i].queue_lock);
 794                 INIT_LIST_HEAD(&nbd_dev[i].queue_head);
 795                 mutex_init(&nbd_dev[i].tx_lock);
 796                 init_waitqueue_head(&nbd_dev[i].active_wq);
 797                 init_waitqueue_head(&nbd_dev[i].waiting_wq);
 798                 nbd_dev[i].blksize = 1024;
 799                 nbd_dev[i].bytesize = 0;
 800                 disk->major = NBD_MAJOR;
 801                 disk->first_minor = i << part_shift;
 802                 disk->fops = &nbd_fops;
 803                 disk->private_data = &nbd_dev[i];
 804                 sprintf(disk->disk_name, "nbd%d", i);
 805                 set_capacity(disk, 0);
 806                 add_disk(disk);
 807         }
 808
 809         return 0;
 810 out:
 811         while (i--) {
 812                 blk_cleanup_queue(nbd_dev[i].disk->queue);
 813                 put_disk(nbd_dev[i].disk);
 814         }
 815         kfree(nbd_dev);
 816         return err;
 817 }
 818
 819 static void __exit nbd_cleanup(void)
 820 {
 821         int i;
 822         for (i = 0; i < nbds_max; i++) {
 823                 struct gendisk *disk = nbd_dev[i].disk;
 824                 nbd_dev[i].magic = 0;
 825                 if (disk) {
 826                         del_gendisk(disk);
 827                         blk_cleanup_queue(disk->queue);
 828                         put_disk(disk);
 829                 }
 830         }
 831         unregister_blkdev(NBD_MAJOR, "nbd");
 832         kfree(nbd_dev);
 833         printk(KERN_INFO "nbd: unregistered device at major %d\n", NBD_MAJOR);
 834 }
 835
 836 module_init(nbd_init);
 837 module_exit(nbd_cleanup);
 838
 839 MODULE_DESCRIPTION("Network Block Device");
 840 MODULE_LICENSE("GPL");
 841
 842 module_param(nbds_max, int, 0444);
 843 MODULE_PARM_DESC(nbds_max, "number of network block devices to initialize (default: 16)");
 844 module_param(max_part, int, 0444);
 845 MODULE_PARM_DESC(max_part, "number of partitions per device (default: 0)");
 846 #ifndef NDEBUG
 847 module_param(debugflags, int, 0644);
 848 MODULE_PARM_DESC(debugflags, "flags for controlling debug output");
 849 #endif