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/system.h>
  38 #include <asm/types.h>
  39
  40 #ifdef NBD_OUTOFTREE
  41 #include "nbd.h"
  42 #else
  43 #include <linux/nbd.h>
  44 #endif
  45
  46 #define LO_MAGIC 0x68797548
  47
  48 #ifdef NDEBUG
  49 #define dprintk(flags, fmt...)
  50 #else /* NDEBUG */
  51 #define dprintk(flags, fmt...) do { \
  52         if (debugflags & (flags)) printk(KERN_DEBUG fmt); \
  53 } while (0)
  54 #define DBG_IOCTL       0x0004
  55 #define DBG_INIT        0x0010
  56 #define DBG_EXIT        0x0020
  57 #define DBG_BLKDEV      0x0100
  58 #define DBG_RX          0x0200
  59 #define DBG_TX          0x0400
  60 static unsigned int debugflags;
  61 #endif /* NDEBUG */
  62
  63 static unsigned int nbds_max = 16;
  64 static struct nbd_device *nbd_dev;
  65 static int max_part;
  66
  67 /*
  68  * Use just one lock (or at most 1 per NIC). Two arguments for this:
  69  * 1. Each NIC is essentially a synchronization point for all servers
  70  *    accessed through that NIC so there's no need to have more locks
  71  *    than NICs anyway.
  72  * 2. More locks lead to more "Dirty cache line bouncing" which will slow
  73  *    down each lock to the point where they're actually slower than just
  74  *    a single lock.
  75  * Thanks go to Jens Axboe and Al Viro for their LKML emails explaining this!
  76  */
  77 static DEFINE_SPINLOCK(nbd_lock);
  78
  79 #ifndef NDEBUG
  80 static const char *ioctl_cmd_to_ascii(int cmd)
  81 {
  82         switch (cmd) {
  83         case NBD_SET_SOCK: return "set-sock";
  84         case NBD_SET_BLKSIZE: return "set-blksize";
  85         case NBD_SET_SIZE: return "set-size";
  86         case NBD_DO_IT: return "do-it";
  87         case NBD_CLEAR_SOCK: return "clear-sock";
  88         case NBD_CLEAR_QUE: return "clear-que";
  89         case NBD_PRINT_DEBUG: return "print-debug";
  90         case NBD_SET_SIZE_BLOCKS: return "set-size-blocks";
  91         case NBD_DISCONNECT: return "disconnect";
  92         case NBD_SET_TIMEOUT: return "set-timeout";
  93         case NBD_SET_FLAGS: return "set-flags";
  94         case BLKROSET: return "set-read-only";
  95         case BLKFLSBUF: return "flush-buffer-cache";
  96         }
  97         return "unknown";
  98 }
  99
 100 static const char *nbdcmd_to_ascii(int cmd)
 101 {
 102         switch (cmd) {
 103         case NBD_CMD_READ: return "read";
 104         case NBD_CMD_WRITE: return "write";
 105         case NBD_CMD_DISC: return "disconnect";
 106         case NBD_CMD_FLUSH: return "flush";
 107         }
 108         return "invalid";
 109 }
 110 #endif /* NDEBUG */
 111
 112 static void nbd_end_request(struct request *req)
 113 {
 114         int error = req->errors ? -EIO : 0;
 115         struct request_queue *q = req->q;
 116         unsigned long flags;
 117
 118         dprintk(DBG_BLKDEV, "%s: request %p: %s\n", req->rq_disk->disk_name,
 119                         req, error ? "failed" : "done");
 120
 121         spin_lock_irqsave(q->queue_lock, flags);
 122         __blk_end_request_all(req, error);
 123         spin_unlock_irqrestore(q->queue_lock, flags);
 124 }
 125
 126 static void sock_shutdown(struct nbd_device *lo, int lock)
 127 {
 128         /* Forcibly shutdown the socket causing all listeners
 129          * to error
 130          *
 131          * FIXME: This code is duplicated from sys_shutdown, but
 132          * there should be a more generic interface rather than
 133          * calling socket ops directly here */
 134         if (lock)
 135                 mutex_lock(&lo->tx_lock);
 136         if (lo->sock) {
 137                 printk(KERN_WARNING "%s: shutting down socket\n",
 138                         lo->disk->disk_name);
 139                 kernel_sock_shutdown(lo->sock, SHUT_RDWR);
 140                 lo->sock = NULL;
 141         }
 142         if (lock)
 143                 mutex_unlock(&lo->tx_lock);
 144 }
 145
 146 static void nbd_xmit_timeout(unsigned long arg)
 147 {
 148         struct task_struct *task = (struct task_struct *)arg;
 149
 150         printk(KERN_WARNING "nbd: killing hung xmit (%s, pid: %d)\n",
 151                 task->comm, task->pid);
 152         force_sig(SIGKILL, task);
 153 }
 154
 155 /*
 156  *  Send or receive packet.
 157  */
 158 static int sock_xmit(struct nbd_device *lo, int send, void *buf, int size,
 159                 int msg_flags)
 160 {
 161         struct socket *sock = lo->sock;
 162         int result;
 163         struct msghdr msg;
 164         struct kvec iov;
 165         sigset_t blocked, oldset;
 166
 167         if (unlikely(!sock)) {
 168                 printk(KERN_ERR "%s: Attempted %s on closed socket in sock_xmit\n",
 169                        lo->disk->disk_name, (send ? "send" : "recv"));
 170                 return -EINVAL;
 171         }
 172
 173         /* Allow interception of SIGKILL only
 174          * Don't allow other signals to interrupt the transmission */
 175         siginitsetinv(&blocked, sigmask(SIGKILL));
 176         sigprocmask(SIG_SETMASK, &blocked, &oldset);
 177
 178         do {
 179                 sock->sk->sk_allocation = GFP_NOIO;
 180                 iov.iov_base = buf;
 181                 iov.iov_len = size;
 182                 msg.msg_name = NULL;
 183                 msg.msg_namelen = 0;
 184                 msg.msg_control = NULL;
 185                 msg.msg_controllen = 0;
 186                 msg.msg_flags = msg_flags | MSG_NOSIGNAL;
 187
 188                 if (send) {
 189                         struct timer_list ti;
 190
 191                         if (lo->xmit_timeout) {
 192                                 init_timer(&ti);
 193                                 ti.function = nbd_xmit_timeout;
 194                                 ti.data = (unsigned long)current;
 195                                 ti.expires = jiffies + lo->xmit_timeout;
 196                                 add_timer(&ti);
 197                         }
 198                         result = kernel_sendmsg(sock, &msg, &iov, 1, size);
 199                         if (lo->xmit_timeout)
 200                                 del_timer_sync(&ti);
 201                 } else
 202                         result = kernel_recvmsg(sock, &msg, &iov, 1, size, 0);
 203
 204                 if (signal_pending(current)) {
 205                         siginfo_t info;
 206                         printk(KERN_WARNING "nbd (pid %d: %s) got signal %d\n",
 207                                 task_pid_nr(current), current->comm,
 208                                 dequeue_signal_lock(current, &current->blocked, &info));
 209                         result = -EINTR;
 210                         sock_shutdown(lo, !send);
 211                         break;
 212                 }
 213
 214                 if (result <= 0) {
 215                         if (result == 0)
 216                                 result = -EPIPE; /* short read */
 217                         break;
 218                 }
 219                 size -= result;
 220                 buf += result;
 221         } while (size > 0);
 222
 223         sigprocmask(SIG_SETMASK, &oldset, NULL);
 224
 225         return result;
 226 }
 227
 228 static inline int sock_send_bvec(struct nbd_device *lo, struct bio_vec *bvec,
 229                 int flags)
 230 {
 231         int result;
 232         void *kaddr = kmap(bvec->bv_page);
 233         result = sock_xmit(lo, 1, kaddr + bvec->bv_offset, bvec->bv_len, flags);
 234         kunmap(bvec->bv_page);
 235         return result;
 236 }
 237
 238 /* always call with the tx_lock held */
 239 static int nbd_send_req(struct nbd_device *lo, struct request *req)
 240 {
 241         int result, flags;
 242         struct nbd_request request;
 243         unsigned long size = blk_rq_bytes(req);
 244
 245         request.magic = htonl(NBD_REQUEST_MAGIC);
 246         /* If FUA is set in the request, and we are told to send FUA, then OR in NBD_CMD_FLAG_FUA */
 247         request.type = htonl(nbd_cmd(req) |
 248                              (( (req->cmd_flags & REQ_FUA) && (lo->flags & NBD_FLAG_SEND_FUA)) ?
 249                               NBD_CMD_FLAG_FUA : 0));
 250         /* Send from & len as zero on FLUSH - other values reserved per protocol */
 251         if (nbd_cmd(req) == NBD_CMD_FLUSH) {
 252                 request.from = 0;
 253                 request.len = 0;
 254         } else {
 255                 request.from = cpu_to_be64((u64)blk_rq_pos(req) << 9);
 256                 request.len = htonl(size);
 257         }
 258         memcpy(request.handle, &req, sizeof(req));
 259
 260         dprintk(DBG_TX, "%s: request %p: sending control (%s@%llu,%uB)\n",
 261                         lo->disk->disk_name, req,
 262                         nbdcmd_to_ascii(nbd_cmd(req)),
 263                         (unsigned long long)blk_rq_pos(req) << 9,
 264                         blk_rq_bytes(req));
 265         result = sock_xmit(lo, 1, &request, sizeof(request),
 266                         (nbd_cmd(req) == NBD_CMD_WRITE) ? MSG_MORE : 0);
 267         if (result <= 0) {
 268                 printk(KERN_ERR "%s: Send control failed (result %d)\n",
 269                                 lo->disk->disk_name, result);
 270                 goto error_out;
 271         }
 272
 273         if (nbd_cmd(req) == NBD_CMD_WRITE) {
 274                 struct req_iterator iter;
 275                 struct bio_vec *bvec;
 276                 /*
 277                  * we are really probing at internals to determine
 278                  * whether to set MSG_MORE or not...
 279                  */
 280                 rq_for_each_segment(bvec, req, iter) {
 281                         flags = 0;
 282                         if (!rq_iter_last(req, iter))
 283                                 flags = MSG_MORE;
 284                         dprintk(DBG_TX, "%s: request %p: sending %d bytes data\n",
 285                                         lo->disk->disk_name, req, bvec->bv_len);
 286                         result = sock_send_bvec(lo, bvec, flags);
 287                         if (result <= 0) {
 288                                 printk(KERN_ERR "%s: Send data failed (result %d)\n",
 289                                                 lo->disk->disk_name, 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 *lo,
 301                                         struct request *xreq)
 302 {
 303         struct request *req, *tmp;
 304         int err;
 305
 306         err = wait_event_interruptible(lo->active_wq, lo->active_req != xreq);
 307         if (unlikely(err))
 308                 goto out;
 309
 310         spin_lock(&lo->queue_lock);
 311         list_for_each_entry_safe(req, tmp, &lo->queue_head, queuelist) {
 312                 if (req != xreq)
 313                         continue;
 314                 list_del_init(&req->queuelist);
 315                 spin_unlock(&lo->queue_lock);
 316                 return req;
 317         }
 318         spin_unlock(&lo->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 *lo, struct bio_vec *bvec)
 327 {
 328         int result;
 329         void *kaddr = kmap(bvec->bv_page);
 330         result = sock_xmit(lo, 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 *lo)
 338 {
 339         int result;
 340         struct nbd_reply reply;
 341         struct request *req;
 342
 343         reply.magic = 0;
 344         result = sock_xmit(lo, 0, &reply, sizeof(reply), MSG_WAITALL);
 345         if (result <= 0) {
 346                 printk(KERN_ERR "%s: Receive control failed (result %d)\n",
 347                                 lo->disk->disk_name, result);
 348                 goto harderror;
 349         }
 350
 351         if (ntohl(reply.magic) != NBD_REPLY_MAGIC) {
 352                 printk(KERN_ERR "%s: Wrong magic (0x%lx)\n",
 353                                 lo->disk->disk_name,
 354                                 (unsigned long)ntohl(reply.magic));
 355                 result = -EPROTO;
 356                 goto harderror;
 357         }
 358
 359         req = nbd_find_request(lo, *(struct request **)reply.handle);
 360         if (IS_ERR(req)) {
 361                 result = PTR_ERR(req);
 362                 if (result != -ENOENT)
 363                         goto harderror;
 364
 365                 printk(KERN_ERR "%s: Unexpected reply (%p)\n",
 366                                 lo->disk->disk_name, reply.handle);
 367                 result = -EBADR;
 368                 goto harderror;
 369         }
 370
 371         if (ntohl(reply.error)) {
 372                 printk(KERN_ERR "%s: Other side returned error (%d)\n",
 373                                 lo->disk->disk_name, ntohl(reply.error));
 374                 req->errors++;
 375                 return req;
 376         }
 377
 378         dprintk(DBG_RX, "%s: request %p: got reply\n",
 379                         lo->disk->disk_name, req);
 380         if (nbd_cmd(req) == NBD_CMD_READ) {
 381                 struct req_iterator iter;
 382                 struct bio_vec *bvec;
 383
 384                 rq_for_each_segment(bvec, req, iter) {
 385                         result = sock_recv_bvec(lo, bvec);
 386                         if (result <= 0) {
 387                                 printk(KERN_ERR "%s: Receive data failed (result %d)\n",
 388                                                 lo->disk->disk_name, result);
 389                                 req->errors++;
 390                                 return req;
 391                         }
 392                         dprintk(DBG_RX, "%s: request %p: got %d bytes data\n",
 393                                 lo->disk->disk_name, req, bvec->bv_len);
 394                 }
 395         }
 396         return req;
 397 harderror:
 398         lo->harderror = result;
 399         return NULL;
 400 }
 401
 402 static ssize_t pid_show(struct device *dev,
 403                         struct device_attribute *attr, char *buf)
 404 {
 405         struct gendisk *disk = dev_to_disk(dev);
 406
 407         return sprintf(buf, "%ld\n",
 408                 (long) ((struct nbd_device *)disk->private_data)->pid);
 409 }
 410
 411 static struct device_attribute pid_attr = {
 412         .attr = { .name = "pid", .mode = S_IRUGO},
 413         .show = pid_show,
 414 };
 415
 416 static int nbd_do_it(struct nbd_device *lo)
 417 {
 418         struct request *req;
 419         int ret;
 420
 421         BUG_ON(lo->magic != LO_MAGIC);
 422
 423         lo->pid = current->pid;
 424         ret = sysfs_create_file(&disk_to_dev(lo->disk)->kobj, &pid_attr.attr);
 425         if (ret) {
 426                 printk(KERN_ERR "nbd: sysfs_create_file failed!");
 427                 lo->pid = 0;
 428                 return ret;
 429         }
 430
 431         while ((req = nbd_read_stat(lo)) != NULL)
 432                 nbd_end_request(req);
 433
 434         sysfs_remove_file(&disk_to_dev(lo->disk)->kobj, &pid_attr.attr);
 435         lo->pid = 0;
 436         return 0;
 437 }
 438
 439 static void nbd_clear_que(struct nbd_device *lo)
 440 {
 441         struct request *req;
 442
 443         BUG_ON(lo->magic != LO_MAGIC);
 444
 445         /*
 446          * Because we have set lo->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(lo->sock);
 454         BUG_ON(lo->active_req);
 455
 456         while (!list_empty(&lo->queue_head)) {
 457                 req = list_entry(lo->queue_head.next, struct request,
 458                                  queuelist);
 459                 list_del_init(&req->queuelist);
 460                 req->errors++;
 461                 nbd_end_request(req);
 462         }
 463 }
 464
 465
 466 static void nbd_handle_req(struct nbd_device *lo, struct request *req)
 467 {
 468         if (req->cmd_type != REQ_TYPE_FS)
 469                 goto error_out;
 470
 471         nbd_cmd(req) = NBD_CMD_READ;
 472         if (rq_data_dir(req) == WRITE) {
 473                 nbd_cmd(req) = NBD_CMD_WRITE;
 474                 if (lo->flags & NBD_FLAG_READ_ONLY) {
 475                         printk(KERN_ERR "%s: Write on read-only\n",
 476                                         lo->disk->disk_name);
 477                         goto error_out;
 478                 }
 479         }
 480
 481         if (req->cmd_flags & REQ_FLUSH) {
 482                 if (unlikely(blk_rq_sectors(req))) {
 483                         /* Elevator is meant to guarantee that a request with REQ_FLUSH
 484                          * set is broken into an empty request with REQ_FLUSH set then
 485                          * the rest of the content (if any). If this doesn't happen,
 486                          * whinge, then proceed to do the content without a flush.
 487                          */
 488                         printk(KERN_ERR "%s: nbd passed non-empty flush request\n",
 489                                lo->disk->disk_name);
 490
 491                 } else {
 492                         if (lo->flags & NBD_FLAG_SEND_FLUSH)
 493                                 nbd_cmd(req) = NBD_CMD_FLUSH;
 494                         else {
 495                                 /* Ignore flush that we don't need */
 496                                 nbd_end_request(req);
 497                                 return;
 498                         }
 499                 }
 500         }
 501
 502         req->errors = 0;
 503
 504         mutex_lock(&lo->tx_lock);
 505         if (unlikely(!lo->sock)) {
 506                 mutex_unlock(&lo->tx_lock);
 507                 printk(KERN_ERR "%s: Attempted send on closed socket\n",
 508                        lo->disk->disk_name);
 509                 goto error_out;
 510         }
 511
 512         lo->active_req = req;
 513
 514         if (nbd_send_req(lo, req) != 0) {
 515                 printk(KERN_ERR "%s: Request send failed\n",
 516                                 lo->disk->disk_name);
 517                 req->errors++;
 518                 nbd_end_request(req);
 519         } else {
 520                 spin_lock(&lo->queue_lock);
 521                 list_add(&req->queuelist, &lo->queue_head);
 522                 spin_unlock(&lo->queue_lock);
 523         }
 524
 525         lo->active_req = NULL;
 526         mutex_unlock(&lo->tx_lock);
 527         wake_up_all(&lo->active_wq);
 528
 529         return;
 530
 531 error_out:
 532         req->errors++;
 533         nbd_end_request(req);
 534 }
 535
 536 static int nbd_thread(void *data)
 537 {
 538         struct nbd_device *lo = data;
 539         struct request *req;
 540
 541         set_user_nice(current, -20);
 542         while (!kthread_should_stop() || !list_empty(&lo->waiting_queue)) {
 543                 /* wait for something to do */
 544                 wait_event_interruptible(lo->waiting_wq,
 545                                          kthread_should_stop() ||
 546                                          !list_empty(&lo->waiting_queue));
 547
 548                 /* extract request */
 549                 if (list_empty(&lo->waiting_queue))
 550                         continue;
 551
 552                 spin_lock_irq(&lo->queue_lock);
 553                 req = list_entry(lo->waiting_queue.next, struct request,
 554                                  queuelist);
 555                 list_del_init(&req->queuelist);
 556                 spin_unlock_irq(&lo->queue_lock);
 557
 558                 /* handle request */
 559                 nbd_handle_req(lo, req);
 560         }
 561         return 0;
 562 }
 563
 564 /*
 565  * We always wait for result of write, for now. It would be nice to make it optional
 566  * in future
 567  * if ((rq_data_dir(req) == WRITE) && (lo->flags & NBD_WRITE_NOCHK))
 568  *   { printk( "Warning: Ignoring result!\n"); nbd_end_request( req ); }
 569  */
 570
 571 static void do_nbd_request(struct request_queue *q)
 572 {
 573         struct request *req;
 574
 575         while ((req = blk_fetch_request(q)) != NULL) {
 576                 struct nbd_device *lo;
 577
 578                 spin_unlock_irq(q->queue_lock);
 579
 580                 dprintk(DBG_BLKDEV, "%s: request %p: dequeued (flags=%x)\n",
 581                                 req->rq_disk->disk_name, req, req->cmd_type);
 582
 583                 lo = req->rq_disk->private_data;
 584
 585                 BUG_ON(lo->magic != LO_MAGIC);
 586
 587                 if (unlikely(!lo->sock)) {
 588                         printk(KERN_ERR "%s: Attempted send on closed socket\n",
 589                                 lo->disk->disk_name);
 590                         req->errors++;
 591                         nbd_end_request(req);
 592                         spin_lock_irq(q->queue_lock);
 593                         continue;
 594                 }
 595
 596                 spin_lock_irq(&lo->queue_lock);
 597                 list_add_tail(&req->queuelist, &lo->waiting_queue);
 598                 spin_unlock_irq(&lo->queue_lock);
 599
 600                 wake_up(&lo->waiting_wq);
 601
 602                 spin_lock_irq(q->queue_lock);
 603         }
 604 }
 605
 606 /* Must be called with tx_lock held */
 607
 608 static int __nbd_ioctl(struct block_device *bdev, struct nbd_device *lo,
 609                        unsigned int cmd, unsigned long arg)
 610 {
 611         switch (cmd) {
 612         case NBD_DISCONNECT: {
 613                 struct request sreq;
 614
 615                 printk(KERN_INFO "%s: NBD_DISCONNECT\n", lo->disk->disk_name);
 616
 617                 blk_rq_init(NULL, &sreq);
 618                 sreq.cmd_type = REQ_TYPE_SPECIAL;
 619                 nbd_cmd(&sreq) = NBD_CMD_DISC;
 620                 if (!lo->sock)
 621                         return -EINVAL;
 622                 nbd_send_req(lo, &sreq);
 623                 return 0;
 624         }
 625
 626         case NBD_CLEAR_SOCK: {
 627                 struct file *file;
 628
 629                 lo->sock = NULL;
 630                 file = lo->file;
 631                 lo->file = NULL;
 632                 nbd_clear_que(lo);
 633                 BUG_ON(!list_empty(&lo->queue_head));
 634                 if (file)
 635                         fput(file);
 636                 return 0;
 637         }
 638
 639         case NBD_SET_SOCK: {
 640                 struct file *file;
 641                 if (lo->file)
 642                         return -EBUSY;
 643                 file = fget(arg);
 644                 if (file) {
 645                         struct inode *inode = file->f_path.dentry->d_inode;
 646                         if (S_ISSOCK(inode->i_mode)) {
 647                                 lo->file = file;
 648                                 lo->sock = SOCKET_I(inode);
 649                                 if (max_part > 0)
 650                                         bdev->bd_invalidated = 1;
 651                                 return 0;
 652                         } else {
 653                                 fput(file);
 654                         }
 655                 }
 656                 return -EINVAL;
 657         }
 658
 659         case NBD_SET_BLKSIZE:
 660                 lo->blksize = arg;
 661                 lo->bytesize &= ~(lo->blksize-1);
 662                 bdev->bd_inode->i_size = lo->bytesize;
 663                 set_blocksize(bdev, lo->blksize);
 664                 set_capacity(lo->disk, lo->bytesize >> 9);
 665                 return 0;
 666
 667         case NBD_SET_SIZE:
 668                 lo->bytesize = arg & ~(lo->blksize-1);
 669                 bdev->bd_inode->i_size = lo->bytesize;
 670                 set_blocksize(bdev, lo->blksize);
 671                 set_capacity(lo->disk, lo->bytesize >> 9);
 672                 return 0;
 673
 674         case NBD_SET_TIMEOUT:
 675                 lo->xmit_timeout = arg * HZ;
 676                 return 0;
 677
 678         case NBD_SET_FLAGS:
 679                 lo->flags = arg;
 680                 if (lo->disk)
 681                 {
 682                         if (lo->flags & NBD_FLAG_ROTATIONAL)
 683                                 queue_flag_clear_unlocked(QUEUE_FLAG_NONROT, lo->disk->queue);
 684                         else
 685                                 queue_flag_set_unlocked(QUEUE_FLAG_NONROT, lo->disk->queue);
 686
 687                 }
 688                 return 0;
 689
 690         case NBD_SET_SIZE_BLOCKS:
 691                 lo->bytesize = ((u64) arg) * lo->blksize;
 692                 bdev->bd_inode->i_size = lo->bytesize;
 693                 set_blocksize(bdev, lo->blksize);
 694                 set_capacity(lo->disk, lo->bytesize >> 9);
 695                 return 0;
 696
 697         case NBD_DO_IT: {
 698                 struct task_struct *thread;
 699                 struct file *file;
 700                 int error;
 701
 702                 if (lo->pid)
 703                         return -EBUSY;
 704                 if (!lo->file)
 705                         return -EINVAL;
 706
 707                 mutex_unlock(&lo->tx_lock);
 708
 709                 thread = kthread_create(nbd_thread, lo, lo->disk->disk_name);
 710                 if (IS_ERR(thread)) {
 711                         mutex_lock(&lo->tx_lock);
 712                         return PTR_ERR(thread);
 713                 }
 714                 wake_up_process(thread);
 715                 error = nbd_do_it(lo);
 716                 kthread_stop(thread);
 717
 718                 mutex_lock(&lo->tx_lock);
 719                 if (error)
 720                         return error;
 721                 sock_shutdown(lo, 0);
 722                 file = lo->file;
 723                 lo->file = NULL;
 724                 nbd_clear_que(lo);
 725                 printk(KERN_WARNING "%s: queue cleared\n", lo->disk->disk_name);
 726                 if (file)
 727                         fput(file);
 728                 lo->bytesize = 0;
 729                 bdev->bd_inode->i_size = 0;
 730                 set_capacity(lo->disk, 0);
 731                 if (max_part > 0)
 732                         ioctl_by_bdev(bdev, BLKRRPART, 0);
 733                 return lo->harderror;
 734         }
 735
 736         case NBD_CLEAR_QUE:
 737                 /*
 738                  * This is for compatibility only.  The queue is always cleared
 739                  * by NBD_DO_IT or NBD_CLEAR_SOCK.
 740                  */
 741                 BUG_ON(!lo->sock && !list_empty(&lo->queue_head));
 742                 return 0;
 743
 744         case NBD_PRINT_DEBUG:
 745                 printk(KERN_INFO "%s: next = %p, prev = %p, head = %p\n",
 746                         bdev->bd_disk->disk_name,
 747                         lo->queue_head.next, lo->queue_head.prev,
 748                         &lo->queue_head);
 749                 return 0;
 750         }
 751         return -ENOTTY;
 752 }
 753
 754 static int nbd_ioctl(struct block_device *bdev, fmode_t mode,
 755                      unsigned int cmd, unsigned long arg)
 756 {
 757         struct nbd_device *lo = bdev->bd_disk->private_data;
 758         int error;
 759
 760         if (!capable(CAP_SYS_ADMIN))
 761                 return -EPERM;
 762
 763         BUG_ON(lo->magic != LO_MAGIC);
 764
 765         /* Anyone capable of this syscall can do *real bad* things */
 766         dprintk(DBG_IOCTL, "%s: nbd_ioctl cmd=%s(0x%x) arg=%lu\n",
 767                         lo->disk->disk_name, ioctl_cmd_to_ascii(cmd), cmd, arg);
 768
 769         mutex_lock(&lo->tx_lock);
 770         error = __nbd_ioctl(bdev, lo, cmd, arg);
 771         mutex_unlock(&lo->tx_lock);
 772
 773         return error;
 774 }
 775
 776 static const struct block_device_operations nbd_fops =
 777 {
 778         .owner =        THIS_MODULE,
 779         .ioctl =        nbd_ioctl,
 780 };
 781
 782 /*
 783  * And here should be modules and kernel interface
 784  *  (Just smiley confuses emacs :-)
 785  */
 786
 787 static int __init nbd_init(void)
 788 {
 789         int err = -ENOMEM;
 790         int i;
 791         int part_shift;
 792
 793         BUILD_BUG_ON(sizeof(struct nbd_request) != 28);
 794
 795         if (max_part < 0) {
 796                 printk(KERN_CRIT "nbd: max_part must be >= 0\n");
 797                 return -EINVAL;
 798         }
 799
 800         nbd_dev = kcalloc(nbds_max, sizeof(*nbd_dev), GFP_KERNEL);
 801         if (!nbd_dev)
 802                 return -ENOMEM;
 803
 804         part_shift = 0;
 805         if (max_part > 0)
 806                 part_shift = fls(max_part);
 807
 808         for (i = 0; i < nbds_max; i++) {
 809                 struct gendisk *disk = alloc_disk(1 << part_shift);
 810                 if (!disk)
 811                         goto out;
 812                 nbd_dev[i].disk = disk;
 813                 /*
 814                  * The new linux 2.5 block layer implementation requires
 815                  * every gendisk to have its very own request_queue struct.
 816                  * These structs are big so we dynamically allocate them.
 817                  */
 818                 disk->queue = blk_init_queue(do_nbd_request, &nbd_lock);
 819                 if (!disk->queue) {
 820                         put_disk(disk);
 821                         goto out;
 822                 }
 823                 /* In order not to confuse the elevator, say we always
 824                  * want FLUSH and FUA. We won't send them to the server
 825                  * unless the relevant flag bit is set
 826                  */
 827                 blk_queue_flush(disk->queue, REQ_FLUSH | REQ_FUA);
 828                 /*
 829                  * Tell the block layer that we are not a rotational device
 830                  */
 831                 queue_flag_set_unlocked(QUEUE_FLAG_NONROT, disk->queue);
 832         }
 833
 834         if (register_blkdev(NBD_MAJOR, "nbd")) {
 835                 err = -EIO;
 836                 goto out;
 837         }
 838
 839         printk(KERN_INFO "nbd: registered device at major %d\n", NBD_MAJOR);
 840         dprintk(DBG_INIT, "nbd: debugflags=0x%x\n", debugflags);
 841
 842         for (i = 0; i < nbds_max; i++) {
 843                 struct gendisk *disk = nbd_dev[i].disk;
 844                 nbd_dev[i].file = NULL;
 845                 nbd_dev[i].magic = LO_MAGIC;
 846                 nbd_dev[i].flags = 0;
 847                 INIT_LIST_HEAD(&nbd_dev[i].waiting_queue);
 848                 spin_lock_init(&nbd_dev[i].queue_lock);
 849                 INIT_LIST_HEAD(&nbd_dev[i].queue_head);
 850                 mutex_init(&nbd_dev[i].tx_lock);
 851                 init_waitqueue_head(&nbd_dev[i].active_wq);
 852                 init_waitqueue_head(&nbd_dev[i].waiting_wq);
 853                 nbd_dev[i].blksize = 1024;
 854                 nbd_dev[i].bytesize = 0;
 855                 disk->major = NBD_MAJOR;
 856                 disk->first_minor = i << part_shift;
 857                 disk->fops = &nbd_fops;
 858                 disk->private_data = &nbd_dev[i];
 859                 sprintf(disk->disk_name, "nbd%d", i);
 860                 set_capacity(disk, 0);
 861                 add_disk(disk);
 862         }
 863
 864         return 0;
 865 out:
 866         while (i--) {
 867                 blk_cleanup_queue(nbd_dev[i].disk->queue);
 868                 put_disk(nbd_dev[i].disk);
 869         }
 870         kfree(nbd_dev);
 871         return err;
 872 }
 873
 874 static void __exit nbd_cleanup(void)
 875 {
 876         int i;
 877         for (i = 0; i < nbds_max; i++) {
 878                 struct gendisk *disk = nbd_dev[i].disk;
 879                 nbd_dev[i].magic = 0;
 880                 if (disk) {
 881                         del_gendisk(disk);
 882                         blk_cleanup_queue(disk->queue);
 883                         put_disk(disk);
 884                 }
 885         }
 886         unregister_blkdev(NBD_MAJOR, "nbd");
 887         kfree(nbd_dev);
 888         printk(KERN_INFO "nbd: unregistered device at major %d\n", NBD_MAJOR);
 889 }
 890
 891 module_init(nbd_init);
 892 module_exit(nbd_cleanup);
 893
 894 MODULE_DESCRIPTION("Network Block Device");
 895 MODULE_LICENSE("GPL");
 896
 897 module_param(nbds_max, int, 0444);
 898 MODULE_PARM_DESC(nbds_max, "number of network block devices to initialize (default: 16)");
 899 module_param(max_part, int, 0444);
 900 MODULE_PARM_DESC(max_part, "number of partitions per device (default: 0)");
 901 #ifndef NDEBUG
 902 module_param(debugflags, int, 0644);
 903 MODULE_PARM_DESC(debugflags, "flags for controlling debug output");
 904 #endif