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         request.from = cpu_to_be64((u64)blk_rq_pos(req) << 9);
 251         request.len = htonl(size);
 252         memcpy(request.handle, &req, sizeof(req));
 253
 254         dprintk(DBG_TX, "%s: request %p: sending control (%s@%llu,%uB)\n",
 255                         lo->disk->disk_name, req,
 256                         nbdcmd_to_ascii(nbd_cmd(req)),
 257                         (unsigned long long)blk_rq_pos(req) << 9,
 258                         blk_rq_bytes(req));
 259         result = sock_xmit(lo, 1, &request, sizeof(request),
 260                         (nbd_cmd(req) == NBD_CMD_WRITE) ? MSG_MORE : 0);
 261         if (result <= 0) {
 262                 printk(KERN_ERR "%s: Send control failed (result %d)\n",
 263                                 lo->disk->disk_name, result);
 264                 goto error_out;
 265         }
 266
 267         if (nbd_cmd(req) == NBD_CMD_WRITE) {
 268                 struct req_iterator iter;
 269                 struct bio_vec *bvec;
 270                 /*
 271                  * we are really probing at internals to determine
 272                  * whether to set MSG_MORE or not...
 273                  */
 274                 rq_for_each_segment(bvec, req, iter) {
 275                         flags = 0;
 276                         if (!rq_iter_last(req, iter))
 277                                 flags = MSG_MORE;
 278                         dprintk(DBG_TX, "%s: request %p: sending %d bytes data\n",
 279                                         lo->disk->disk_name, req, bvec->bv_len);
 280                         result = sock_send_bvec(lo, bvec, flags);
 281                         if (result <= 0) {
 282                                 printk(KERN_ERR "%s: Send data failed (result %d)\n",
 283                                                 lo->disk->disk_name, result);
 284                                 goto error_out;
 285                         }
 286                 }
 287         }
 288         return 0;
 289
 290 error_out:
 291         return -EIO;
 292 }
 293
 294 static struct request *nbd_find_request(struct nbd_device *lo,
 295                                         struct request *xreq)
 296 {
 297         struct request *req, *tmp;
 298         int err;
 299
 300         err = wait_event_interruptible(lo->active_wq, lo->active_req != xreq);
 301         if (unlikely(err))
 302                 goto out;
 303
 304         spin_lock(&lo->queue_lock);
 305         list_for_each_entry_safe(req, tmp, &lo->queue_head, queuelist) {
 306                 if (req != xreq)
 307                         continue;
 308                 list_del_init(&req->queuelist);
 309                 spin_unlock(&lo->queue_lock);
 310                 return req;
 311         }
 312         spin_unlock(&lo->queue_lock);
 313
 314         err = -ENOENT;
 315
 316 out:
 317         return ERR_PTR(err);
 318 }
 319
 320 static inline int sock_recv_bvec(struct nbd_device *lo, struct bio_vec *bvec)
 321 {
 322         int result;
 323         void *kaddr = kmap(bvec->bv_page);
 324         result = sock_xmit(lo, 0, kaddr + bvec->bv_offset, bvec->bv_len,
 325                         MSG_WAITALL);
 326         kunmap(bvec->bv_page);
 327         return result;
 328 }
 329
 330 /* NULL returned = something went wrong, inform userspace */
 331 static struct request *nbd_read_stat(struct nbd_device *lo)
 332 {
 333         int result;
 334         struct nbd_reply reply;
 335         struct request *req;
 336
 337         reply.magic = 0;
 338         result = sock_xmit(lo, 0, &reply, sizeof(reply), MSG_WAITALL);
 339         if (result <= 0) {
 340                 printk(KERN_ERR "%s: Receive control failed (result %d)\n",
 341                                 lo->disk->disk_name, result);
 342                 goto harderror;
 343         }
 344
 345         if (ntohl(reply.magic) != NBD_REPLY_MAGIC) {
 346                 printk(KERN_ERR "%s: Wrong magic (0x%lx)\n",
 347                                 lo->disk->disk_name,
 348                                 (unsigned long)ntohl(reply.magic));
 349                 result = -EPROTO;
 350                 goto harderror;
 351         }
 352
 353         req = nbd_find_request(lo, *(struct request **)reply.handle);
 354         if (IS_ERR(req)) {
 355                 result = PTR_ERR(req);
 356                 if (result != -ENOENT)
 357                         goto harderror;
 358
 359                 printk(KERN_ERR "%s: Unexpected reply (%p)\n",
 360                                 lo->disk->disk_name, reply.handle);
 361                 result = -EBADR;
 362                 goto harderror;
 363         }
 364
 365         if (ntohl(reply.error)) {
 366                 printk(KERN_ERR "%s: Other side returned error (%d)\n",
 367                                 lo->disk->disk_name, ntohl(reply.error));
 368                 req->errors++;
 369                 return req;
 370         }
 371
 372         dprintk(DBG_RX, "%s: request %p: got reply\n",
 373                         lo->disk->disk_name, req);
 374         if (nbd_cmd(req) == NBD_CMD_READ) {
 375                 struct req_iterator iter;
 376                 struct bio_vec *bvec;
 377
 378                 rq_for_each_segment(bvec, req, iter) {
 379                         result = sock_recv_bvec(lo, bvec);
 380                         if (result <= 0) {
 381                                 printk(KERN_ERR "%s: Receive data failed (result %d)\n",
 382                                                 lo->disk->disk_name, result);
 383                                 req->errors++;
 384                                 return req;
 385                         }
 386                         dprintk(DBG_RX, "%s: request %p: got %d bytes data\n",
 387                                 lo->disk->disk_name, req, bvec->bv_len);
 388                 }
 389         }
 390         return req;
 391 harderror:
 392         lo->harderror = result;
 393         return NULL;
 394 }
 395
 396 static ssize_t pid_show(struct device *dev,
 397                         struct device_attribute *attr, char *buf)
 398 {
 399         struct gendisk *disk = dev_to_disk(dev);
 400
 401         return sprintf(buf, "%ld\n",
 402                 (long) ((struct nbd_device *)disk->private_data)->pid);
 403 }
 404
 405 static struct device_attribute pid_attr = {
 406         .attr = { .name = "pid", .mode = S_IRUGO},
 407         .show = pid_show,
 408 };
 409
 410 static int nbd_do_it(struct nbd_device *lo)
 411 {
 412         struct request *req;
 413         int ret;
 414
 415         BUG_ON(lo->magic != LO_MAGIC);
 416
 417         lo->pid = current->pid;
 418         ret = sysfs_create_file(&disk_to_dev(lo->disk)->kobj, &pid_attr.attr);
 419         if (ret) {
 420                 printk(KERN_ERR "nbd: sysfs_create_file failed!");
 421                 lo->pid = 0;
 422                 return ret;
 423         }
 424
 425         while ((req = nbd_read_stat(lo)) != NULL)
 426                 nbd_end_request(req);
 427
 428         sysfs_remove_file(&disk_to_dev(lo->disk)->kobj, &pid_attr.attr);
 429         lo->pid = 0;
 430         return 0;
 431 }
 432
 433 static void nbd_clear_que(struct nbd_device *lo)
 434 {
 435         struct request *req;
 436
 437         BUG_ON(lo->magic != LO_MAGIC);
 438
 439         /*
 440          * Because we have set lo->sock to NULL under the tx_lock, all
 441          * modifications to the list must have completed by now.  For
 442          * the same reason, the active_req must be NULL.
 443          *
 444          * As a consequence, we don't need to take the spin lock while
 445          * purging the list here.
 446          */
 447         BUG_ON(lo->sock);
 448         BUG_ON(lo->active_req);
 449
 450         while (!list_empty(&lo->queue_head)) {
 451                 req = list_entry(lo->queue_head.next, struct request,
 452                                  queuelist);
 453                 list_del_init(&req->queuelist);
 454                 req->errors++;
 455                 nbd_end_request(req);
 456         }
 457 }
 458
 459
 460 static void nbd_handle_req(struct nbd_device *lo, struct request *req)
 461 {
 462         if (req->cmd_type != REQ_TYPE_FS)
 463                 goto error_out;
 464
 465         nbd_cmd(req) = NBD_CMD_READ;
 466         if (rq_data_dir(req) == WRITE) {
 467                 nbd_cmd(req) = NBD_CMD_WRITE;
 468                 if (lo->flags & NBD_FLAG_READ_ONLY) {
 469                         printk(KERN_ERR "%s: Write on read-only\n",
 470                                         lo->disk->disk_name);
 471                         goto error_out;
 472                 }
 473         }
 474
 475         if (req->cmd_flags & REQ_FLUSH) {
 476                 if (unlikely(blk_rq_sectors(req))) {
 477                         /* Elevator is meant to guarantee that a request with REQ_FLUSH
 478                          * set is broken into an empty request with REQ_FLUSH set then
 479                          * the rest of the content (if any). If this doesn't happen,
 480                          * whinge, then proceed to do the content without a flush.
 481                          */
 482                         printk(KERN_ERR "%s: nbd passed non-empty flush request\n",
 483                                lo->disk->disk_name);
 484
 485                 } else {
 486                         if (lo->flags & NBD_FLAG_SEND_FLUSH)
 487                                 nbd_cmd(req) = NBD_CMD_FLUSH;
 488                         else {
 489                                 /* Ignore flush that we don't need */
 490                                 nbd_end_request(req);
 491                                 return;
 492                         }
 493                 }
 494         }
 495
 496         req->errors = 0;
 497
 498         mutex_lock(&lo->tx_lock);
 499         if (unlikely(!lo->sock)) {
 500                 mutex_unlock(&lo->tx_lock);
 501                 printk(KERN_ERR "%s: Attempted send on closed socket\n",
 502                        lo->disk->disk_name);
 503                 goto error_out;
 504         }
 505
 506         lo->active_req = req;
 507
 508         if (nbd_send_req(lo, req) != 0) {
 509                 printk(KERN_ERR "%s: Request send failed\n",
 510                                 lo->disk->disk_name);
 511                 req->errors++;
 512                 nbd_end_request(req);
 513         } else {
 514                 spin_lock(&lo->queue_lock);
 515                 list_add(&req->queuelist, &lo->queue_head);
 516                 spin_unlock(&lo->queue_lock);
 517         }
 518
 519         lo->active_req = NULL;
 520         mutex_unlock(&lo->tx_lock);
 521         wake_up_all(&lo->active_wq);
 522
 523         return;
 524
 525 error_out:
 526         req->errors++;
 527         nbd_end_request(req);
 528 }
 529
 530 static int nbd_thread(void *data)
 531 {
 532         struct nbd_device *lo = data;
 533         struct request *req;
 534
 535         set_user_nice(current, -20);
 536         while (!kthread_should_stop() || !list_empty(&lo->waiting_queue)) {
 537                 /* wait for something to do */
 538                 wait_event_interruptible(lo->waiting_wq,
 539                                          kthread_should_stop() ||
 540                                          !list_empty(&lo->waiting_queue));
 541
 542                 /* extract request */
 543                 if (list_empty(&lo->waiting_queue))
 544                         continue;
 545
 546                 spin_lock_irq(&lo->queue_lock);
 547                 req = list_entry(lo->waiting_queue.next, struct request,
 548                                  queuelist);
 549                 list_del_init(&req->queuelist);
 550                 spin_unlock_irq(&lo->queue_lock);
 551
 552                 /* handle request */
 553                 nbd_handle_req(lo, req);
 554         }
 555         return 0;
 556 }
 557
 558 /*
 559  * We always wait for result of write, for now. It would be nice to make it optional
 560  * in future
 561  * if ((rq_data_dir(req) == WRITE) && (lo->flags & NBD_WRITE_NOCHK))
 562  *   { printk( "Warning: Ignoring result!\n"); nbd_end_request( req ); }
 563  */
 564
 565 static void do_nbd_request(struct request_queue *q)
 566 {
 567         struct request *req;
 568
 569         while ((req = blk_fetch_request(q)) != NULL) {
 570                 struct nbd_device *lo;
 571
 572                 spin_unlock_irq(q->queue_lock);
 573
 574                 dprintk(DBG_BLKDEV, "%s: request %p: dequeued (flags=%x)\n",
 575                                 req->rq_disk->disk_name, req, req->cmd_type);
 576
 577                 lo = req->rq_disk->private_data;
 578
 579                 BUG_ON(lo->magic != LO_MAGIC);
 580
 581                 if (unlikely(!lo->sock)) {
 582                         printk(KERN_ERR "%s: Attempted send on closed socket\n",
 583                                 lo->disk->disk_name);
 584                         req->errors++;
 585                         nbd_end_request(req);
 586                         spin_lock_irq(q->queue_lock);
 587                         continue;
 588                 }
 589
 590                 spin_lock_irq(&lo->queue_lock);
 591                 list_add_tail(&req->queuelist, &lo->waiting_queue);
 592                 spin_unlock_irq(&lo->queue_lock);
 593
 594                 wake_up(&lo->waiting_wq);
 595
 596                 spin_lock_irq(q->queue_lock);
 597         }
 598 }
 599
 600 /* Must be called with tx_lock held */
 601
 602 static int __nbd_ioctl(struct block_device *bdev, struct nbd_device *lo,
 603                        unsigned int cmd, unsigned long arg)
 604 {
 605         switch (cmd) {
 606         case NBD_DISCONNECT: {
 607                 struct request sreq;
 608
 609                 printk(KERN_INFO "%s: NBD_DISCONNECT\n", lo->disk->disk_name);
 610
 611                 blk_rq_init(NULL, &sreq);
 612                 sreq.cmd_type = REQ_TYPE_SPECIAL;
 613                 nbd_cmd(&sreq) = NBD_CMD_DISC;
 614                 if (!lo->sock)
 615                         return -EINVAL;
 616                 nbd_send_req(lo, &sreq);
 617                 return 0;
 618         }
 619
 620         case NBD_CLEAR_SOCK: {
 621                 struct file *file;
 622
 623                 lo->sock = NULL;
 624                 file = lo->file;
 625                 lo->file = NULL;
 626                 nbd_clear_que(lo);
 627                 BUG_ON(!list_empty(&lo->queue_head));
 628                 if (file)
 629                         fput(file);
 630                 return 0;
 631         }
 632
 633         case NBD_SET_SOCK: {
 634                 struct file *file;
 635                 if (lo->file)
 636                         return -EBUSY;
 637                 file = fget(arg);
 638                 if (file) {
 639                         struct inode *inode = file->f_path.dentry->d_inode;
 640                         if (S_ISSOCK(inode->i_mode)) {
 641                                 lo->file = file;
 642                                 lo->sock = SOCKET_I(inode);
 643                                 if (max_part > 0)
 644                                         bdev->bd_invalidated = 1;
 645                                 return 0;
 646                         } else {
 647                                 fput(file);
 648                         }
 649                 }
 650                 return -EINVAL;
 651         }
 652
 653         case NBD_SET_BLKSIZE:
 654                 lo->blksize = arg;
 655                 lo->bytesize &= ~(lo->blksize-1);
 656                 bdev->bd_inode->i_size = lo->bytesize;
 657                 set_blocksize(bdev, lo->blksize);
 658                 set_capacity(lo->disk, lo->bytesize >> 9);
 659                 return 0;
 660
 661         case NBD_SET_SIZE:
 662                 lo->bytesize = arg & ~(lo->blksize-1);
 663                 bdev->bd_inode->i_size = lo->bytesize;
 664                 set_blocksize(bdev, lo->blksize);
 665                 set_capacity(lo->disk, lo->bytesize >> 9);
 666                 return 0;
 667
 668         case NBD_SET_TIMEOUT:
 669                 lo->xmit_timeout = arg * HZ;
 670                 return 0;
 671
 672         case NBD_SET_FLAGS:
 673                 lo->flags = arg;
 674                 if (lo->disk)
 675                 {
 676                         if (lo->flags & NBD_FLAG_ROTATIONAL)
 677                                 queue_flag_clear_unlocked(QUEUE_FLAG_NONROT, lo->disk->queue);
 678                         else
 679                                 queue_flag_set_unlocked(QUEUE_FLAG_NONROT, lo->disk->queue);
 680
 681                 }
 682                 return 0;
 683
 684         case NBD_SET_SIZE_BLOCKS:
 685                 lo->bytesize = ((u64) arg) * lo->blksize;
 686                 bdev->bd_inode->i_size = lo->bytesize;
 687                 set_blocksize(bdev, lo->blksize);
 688                 set_capacity(lo->disk, lo->bytesize >> 9);
 689                 return 0;
 690
 691         case NBD_DO_IT: {
 692                 struct task_struct *thread;
 693                 struct file *file;
 694                 int error;
 695
 696                 if (lo->pid)
 697                         return -EBUSY;
 698                 if (!lo->file)
 699                         return -EINVAL;
 700
 701                 mutex_unlock(&lo->tx_lock);
 702
 703                 thread = kthread_create(nbd_thread, lo, lo->disk->disk_name);
 704                 if (IS_ERR(thread)) {
 705                         mutex_lock(&lo->tx_lock);
 706                         return PTR_ERR(thread);
 707                 }
 708                 wake_up_process(thread);
 709                 error = nbd_do_it(lo);
 710                 kthread_stop(thread);
 711
 712                 mutex_lock(&lo->tx_lock);
 713                 if (error)
 714                         return error;
 715                 sock_shutdown(lo, 0);
 716                 file = lo->file;
 717                 lo->file = NULL;
 718                 nbd_clear_que(lo);
 719                 printk(KERN_WARNING "%s: queue cleared\n", lo->disk->disk_name);
 720                 if (file)
 721                         fput(file);
 722                 lo->bytesize = 0;
 723                 bdev->bd_inode->i_size = 0;
 724                 set_capacity(lo->disk, 0);
 725                 if (max_part > 0)
 726                         ioctl_by_bdev(bdev, BLKRRPART, 0);
 727                 return lo->harderror;
 728         }
 729
 730         case NBD_CLEAR_QUE:
 731                 /*
 732                  * This is for compatibility only.  The queue is always cleared
 733                  * by NBD_DO_IT or NBD_CLEAR_SOCK.
 734                  */
 735                 BUG_ON(!lo->sock && !list_empty(&lo->queue_head));
 736                 return 0;
 737
 738         case NBD_PRINT_DEBUG:
 739                 printk(KERN_INFO "%s: next = %p, prev = %p, head = %p\n",
 740                         bdev->bd_disk->disk_name,
 741                         lo->queue_head.next, lo->queue_head.prev,
 742                         &lo->queue_head);
 743                 return 0;
 744         }
 745         return -ENOTTY;
 746 }
 747
 748 static int nbd_ioctl(struct block_device *bdev, fmode_t mode,
 749                      unsigned int cmd, unsigned long arg)
 750 {
 751         struct nbd_device *lo = bdev->bd_disk->private_data;
 752         int error;
 753
 754         if (!capable(CAP_SYS_ADMIN))
 755                 return -EPERM;
 756
 757         BUG_ON(lo->magic != LO_MAGIC);
 758
 759         /* Anyone capable of this syscall can do *real bad* things */
 760         dprintk(DBG_IOCTL, "%s: nbd_ioctl cmd=%s(0x%x) arg=%lu\n",
 761                         lo->disk->disk_name, ioctl_cmd_to_ascii(cmd), cmd, arg);
 762
 763         mutex_lock(&lo->tx_lock);
 764         error = __nbd_ioctl(bdev, lo, cmd, arg);
 765         mutex_unlock(&lo->tx_lock);
 766
 767         return error;
 768 }
 769
 770 static const struct block_device_operations nbd_fops =
 771 {
 772         .owner =        THIS_MODULE,
 773         .ioctl =        nbd_ioctl,
 774 };
 775
 776 /*
 777  * And here should be modules and kernel interface
 778  *  (Just smiley confuses emacs :-)
 779  */
 780
 781 static int __init nbd_init(void)
 782 {
 783         int err = -ENOMEM;
 784         int i;
 785         int part_shift;
 786
 787         BUILD_BUG_ON(sizeof(struct nbd_request) != 28);
 788
 789         if (max_part < 0) {
 790                 printk(KERN_CRIT "nbd: max_part must be >= 0\n");
 791                 return -EINVAL;
 792         }
 793
 794         nbd_dev = kcalloc(nbds_max, sizeof(*nbd_dev), GFP_KERNEL);
 795         if (!nbd_dev)
 796                 return -ENOMEM;
 797
 798         part_shift = 0;
 799         if (max_part > 0)
 800                 part_shift = fls(max_part);
 801
 802         for (i = 0; i < nbds_max; i++) {
 803                 struct gendisk *disk = alloc_disk(1 << part_shift);
 804                 if (!disk)
 805                         goto out;
 806                 nbd_dev[i].disk = disk;
 807                 /*
 808                  * The new linux 2.5 block layer implementation requires
 809                  * every gendisk to have its very own request_queue struct.
 810                  * These structs are big so we dynamically allocate them.
 811                  */
 812                 disk->queue = blk_init_queue(do_nbd_request, &nbd_lock);
 813                 if (!disk->queue) {
 814                         put_disk(disk);
 815                         goto out;
 816                 }
 817                 /* In order not to confuse the elevator, say we always
 818                  * want FLUSH and FUA. We won't send them to the server
 819                  * unless the relevant flag bit is set
 820                  */
 821                 blk_queue_flush(disk->queue, REQ_FLUSH | REQ_FUA);
 822                 /*
 823                  * Tell the block layer that we are not a rotational device
 824                  */
 825                 queue_flag_set_unlocked(QUEUE_FLAG_NONROT, disk->queue);
 826         }
 827
 828         if (register_blkdev(NBD_MAJOR, "nbd")) {
 829                 err = -EIO;
 830                 goto out;
 831         }
 832
 833         printk(KERN_INFO "nbd: registered device at major %d\n", NBD_MAJOR);
 834         dprintk(DBG_INIT, "nbd: debugflags=0x%x\n", debugflags);
 835
 836         for (i = 0; i < nbds_max; i++) {
 837                 struct gendisk *disk = nbd_dev[i].disk;
 838                 nbd_dev[i].file = NULL;
 839                 nbd_dev[i].magic = LO_MAGIC;
 840                 nbd_dev[i].flags = 0;
 841                 INIT_LIST_HEAD(&nbd_dev[i].waiting_queue);
 842                 spin_lock_init(&nbd_dev[i].queue_lock);
 843                 INIT_LIST_HEAD(&nbd_dev[i].queue_head);
 844                 mutex_init(&nbd_dev[i].tx_lock);
 845                 init_waitqueue_head(&nbd_dev[i].active_wq);
 846                 init_waitqueue_head(&nbd_dev[i].waiting_wq);
 847                 nbd_dev[i].blksize = 1024;
 848                 nbd_dev[i].bytesize = 0;
 849                 disk->major = NBD_MAJOR;
 850                 disk->first_minor = i << part_shift;
 851                 disk->fops = &nbd_fops;
 852                 disk->private_data = &nbd_dev[i];
 853                 sprintf(disk->disk_name, "nbd%d", i);
 854                 set_capacity(disk, 0);
 855                 add_disk(disk);
 856         }
 857
 858         return 0;
 859 out:
 860         while (i--) {
 861                 blk_cleanup_queue(nbd_dev[i].disk->queue);
 862                 put_disk(nbd_dev[i].disk);
 863         }
 864         kfree(nbd_dev);
 865         return err;
 866 }
 867
 868 static void __exit nbd_cleanup(void)
 869 {
 870         int i;
 871         for (i = 0; i < nbds_max; i++) {
 872                 struct gendisk *disk = nbd_dev[i].disk;
 873                 nbd_dev[i].magic = 0;
 874                 if (disk) {
 875                         del_gendisk(disk);
 876                         blk_cleanup_queue(disk->queue);
 877                         put_disk(disk);
 878                 }
 879         }
 880         unregister_blkdev(NBD_MAJOR, "nbd");
 881         kfree(nbd_dev);
 882         printk(KERN_INFO "nbd: unregistered device at major %d\n", NBD_MAJOR);
 883 }
 884
 885 module_init(nbd_init);
 886 module_exit(nbd_cleanup);
 887
 888 MODULE_DESCRIPTION("Network Block Device");
 889 MODULE_LICENSE("GPL");
 890
 891 module_param(nbds_max, int, 0444);
 892 MODULE_PARM_DESC(nbds_max, "number of network block devices to initialize (default: 16)");
 893 module_param(max_part, int, 0444);
 894 MODULE_PARM_DESC(max_part, "number of partitions per device (default: 0)");
 895 #ifndef NDEBUG
 896 module_param(debugflags, int, 0644);
 897 MODULE_PARM_DESC(debugflags, "flags for controlling debug output");
 898 #endif