drivers/block/nbd.c

   1 /*
   2  * Network block device - make block devices work over TCP
   3  *
   4  * Note that you can not swap over this thing, yet. Seems to work but
   5  * deadlocks sometimes - you can not swap over TCP in general.
   6  *
   7  * Copyright 1997-2000, 2008 Pavel Machek <pavel@ucw.cz>
   8  * Parts copyright 2001 Steven Whitehouse <steve@chygwyn.com>
   9  *
  10  * This file is released under GPLv2 or later.
  11  *
  12  * (part of code stolen from loop.c)
  13  */
  14
  15 #include <linux/major.h>
  16
  17 #include <linux/blkdev.h>
  18 #include <linux/module.h>
  19 #include <linux/init.h>
  20 #include <linux/sched.h>
  21 #include <linux/fs.h>
  22 #include <linux/bio.h>
  23 #include <linux/stat.h>
  24 #include <linux/errno.h>
  25 #include <linux/file.h>
  26 #include <linux/ioctl.h>
  27 #include <linux/mutex.h>
  28 #include <linux/compiler.h>
  29 #include <linux/err.h>
  30 #include <linux/kernel.h>
  31 #include <linux/slab.h>
  32 #include <net/sock.h>
  33 #include <linux/net.h>
  34 #include <linux/kthread.h>
  35
  36 #include <asm/uaccess.h>
  37 #include <asm/types.h>
  38
  39 #include <linux/nbd.h>
  40
  41 #define NBD_MAGIC 0x68797548
  42
  43 #ifdef NDEBUG
  44 #define dprintk(flags, fmt...)
  45 #else /* NDEBUG */
  46 #define dprintk(flags, fmt...) do { \
  47         if (debugflags & (flags)) printk(KERN_DEBUG fmt); \
  48 } while (0)
  49 #define DBG_IOCTL       0x0004
  50 #define DBG_INIT        0x0010
  51 #define DBG_EXIT        0x0020
  52 #define DBG_BLKDEV      0x0100
  53 #define DBG_RX          0x0200
  54 #define DBG_TX          0x0400
  55 static unsigned int debugflags;
  56 #endif /* NDEBUG */
  57
  58 static unsigned int nbds_max = 16;
  59 static struct nbd_device *nbd_dev;
  60 static int max_part;
  61
  62 /*
  63  * Use just one lock (or at most 1 per NIC). Two arguments for this:
  64  * 1. Each NIC is essentially a synchronization point for all servers
  65  *    accessed through that NIC so there's no need to have more locks
  66  *    than NICs anyway.
  67  * 2. More locks lead to more "Dirty cache line bouncing" which will slow
  68  *    down each lock to the point where they're actually slower than just
  69  *    a single lock.
  70  * Thanks go to Jens Axboe and Al Viro for their LKML emails explaining this!
  71  */
  72 static DEFINE_SPINLOCK(nbd_lock);
  73
  74 #ifndef NDEBUG
  75 static const char *ioctl_cmd_to_ascii(int cmd)
  76 {
  77         switch (cmd) {
  78         case NBD_SET_SOCK: return "set-sock";
  79         case NBD_SET_BLKSIZE: return "set-blksize";
  80         case NBD_SET_SIZE: return "set-size";
  81         case NBD_SET_TIMEOUT: return "set-timeout";
  82         case NBD_SET_FLAGS: return "set-flags";
  83         case NBD_DO_IT: return "do-it";
  84         case NBD_CLEAR_SOCK: return "clear-sock";
  85         case NBD_CLEAR_QUE: return "clear-que";
  86         case NBD_PRINT_DEBUG: return "print-debug";
  87         case NBD_SET_SIZE_BLOCKS: return "set-size-blocks";
  88         case NBD_DISCONNECT: return "disconnect";
  89         case BLKROSET: return "set-read-only";
  90         case BLKFLSBUF: return "flush-buffer-cache";
  91         }
  92         return "unknown";
  93 }
  94
  95 static const char *nbdcmd_to_ascii(int cmd)
  96 {
  97         switch (cmd) {
  98         case  NBD_CMD_READ: return "read";
  99         case NBD_CMD_WRITE: return "write";
 100         case  NBD_CMD_DISC: return "disconnect";
 101         case NBD_CMD_FLUSH: return "flush";
 102         case  NBD_CMD_TRIM: return "trim/discard";
 103         }
 104         return "invalid";
 105 }
 106 #endif /* NDEBUG */
 107
 108 static void nbd_end_request(struct request *req)
 109 {
 110         int error = req->errors ? -EIO : 0;
 111         struct request_queue *q = req->q;
 112         unsigned long flags;
 113
 114         dprintk(DBG_BLKDEV, "%s: request %p: %s\n", req->rq_disk->disk_name,
 115                         req, error ? "failed" : "done");
 116
 117         spin_lock_irqsave(q->queue_lock, flags);
 118         __blk_end_request_all(req, error);
 119         spin_unlock_irqrestore(q->queue_lock, flags);
 120 }
 121
 122 static void sock_shutdown(struct nbd_device *nbd, int lock)
 123 {
 124         /* Forcibly shutdown the socket causing all listeners
 125          * to error
 126          *
 127          * FIXME: This code is duplicated from sys_shutdown, but
 128          * there should be a more generic interface rather than
 129          * calling socket ops directly here */
 130         if (lock)
 131                 mutex_lock(&nbd->tx_lock);
 132         if (nbd->sock) {
 133                 dev_warn(disk_to_dev(nbd->disk), "shutting down socket\n");
 134                 kernel_sock_shutdown(nbd->sock, SHUT_RDWR);
 135                 nbd->sock = NULL;
 136         }
 137         if (lock)
 138                 mutex_unlock(&nbd->tx_lock);
 139 }
 140
 141 static void nbd_xmit_timeout(unsigned long arg)
 142 {
 143         struct task_struct *task = (struct task_struct *)arg;
 144
 145         printk(KERN_WARNING "nbd: killing hung xmit (%s, pid: %d)\n",
 146                 task->comm, task->pid);
 147         force_sig(SIGKILL, task);
 148 }
 149
 150 /*
 151  *  Send or receive packet.
 152  */
 153 static int sock_xmit(struct nbd_device *nbd, int send, void *buf, int size,
 154                 int msg_flags)
 155 {
 156         struct socket *sock = nbd->sock;
 157         int result;
 158         struct msghdr msg;
 159         struct kvec iov;
 160         sigset_t blocked, oldset;
 161         unsigned long pflags = current->flags;
 162
 163         if (unlikely(!sock)) {
 164                 dev_err(disk_to_dev(nbd->disk),
 165                         "Attempted %s on closed socket in sock_xmit\n",
 166                         (send ? "send" : "recv"));
 167                 return -EINVAL;
 168         }
 169
 170         /* Allow interception of SIGKILL only
 171          * Don't allow other signals to interrupt the transmission */
 172         siginitsetinv(&blocked, sigmask(SIGKILL));
 173         sigprocmask(SIG_SETMASK, &blocked, &oldset);
 174
 175         current->flags |= PF_MEMALLOC;
 176         do {
 177                 sock->sk->sk_allocation = GFP_NOIO | __GFP_MEMALLOC;
 178                 iov.iov_base = buf;
 179                 iov.iov_len = size;
 180                 msg.msg_name = NULL;
 181                 msg.msg_namelen = 0;
 182                 msg.msg_control = NULL;
 183                 msg.msg_controllen = 0;
 184                 msg.msg_flags = msg_flags | MSG_NOSIGNAL;
 185
 186                 if (send) {
 187                         struct timer_list ti;
 188
 189                         if (nbd->xmit_timeout) {
 190                                 init_timer(&ti);
 191                                 ti.function = nbd_xmit_timeout;
 192                                 ti.data = (unsigned long)current;
 193                                 ti.expires = jiffies + nbd->xmit_timeout;
 194                                 add_timer(&ti);
 195                         }
 196                         result = kernel_sendmsg(sock, &msg, &iov, 1, size);
 197                         if (nbd->xmit_timeout)
 198                                 del_timer_sync(&ti);
 199                 } else
 200                         result = kernel_recvmsg(sock, &msg, &iov, 1, size,
 201                                                 msg.msg_flags);
 202
 203                 if (signal_pending(current)) {
 204                         siginfo_t info;
 205                         printk(KERN_WARNING "nbd (pid %d: %s) got signal %d\n",
 206                                 task_pid_nr(current), current->comm,
 207                                 dequeue_signal_lock(current, &current->blocked, &info));
 208                         result = -EINTR;
 209                         sock_shutdown(nbd, !send);
 210                         break;
 211                 }
 212
 213                 if (result <= 0) {
 214                         if (result == 0)
 215                                 result = -EPIPE; /* short read */
 216                         break;
 217                 }
 218                 size -= result;
 219                 buf += result;
 220         } while (size > 0);
 221
 222         sigprocmask(SIG_SETMASK, &oldset, NULL);
 223         tsk_restore_flags(current, pflags, PF_MEMALLOC);
 224
 225         return result;
 226 }
 227
 228 static inline int sock_send_bvec(struct nbd_device *nbd, struct bio_vec *bvec,
 229                 int flags)
 230 {
 231         int result;
 232         void *kaddr = kmap(bvec->bv_page);
 233         result = sock_xmit(nbd, 1, kaddr + bvec->bv_offset,
 234                            bvec->bv_len, flags);
 235         kunmap(bvec->bv_page);
 236         return result;
 237 }
 238
 239 /* always call with the tx_lock held */
 240 static int nbd_send_req(struct nbd_device *nbd, struct request *req)
 241 {
 242         int result, flags;
 243         struct nbd_request request;
 244         unsigned long size = blk_rq_bytes(req);
 245
 246         memset(&request, 0, sizeof(request));
 247         request.magic = htonl(NBD_REQUEST_MAGIC);
 248         request.type = htonl(nbd_cmd(req));
 249
 250         if (nbd_cmd(req) != NBD_CMD_FLUSH && nbd_cmd(req) != NBD_CMD_DISC) {
 251                 request.from = cpu_to_be64((u64)blk_rq_pos(req) << 9);
 252                 request.len = htonl(size);
 253         }
 254         memcpy(request.handle, &req, sizeof(req));
 255
 256         dprintk(DBG_TX, "%s: request %p: sending control (%s@%llu,%uB)\n",
 257                         nbd->disk->disk_name, req,
 258                         nbdcmd_to_ascii(nbd_cmd(req)),
 259                         (unsigned long long)blk_rq_pos(req) << 9,
 260                         blk_rq_bytes(req));
 261         result = sock_xmit(nbd, 1, &request, sizeof(request),
 262                         (nbd_cmd(req) == NBD_CMD_WRITE) ? MSG_MORE : 0);
 263         if (result <= 0) {
 264                 dev_err(disk_to_dev(nbd->disk),
 265                         "Send control failed (result %d)\n", result);
 266                 goto error_out;
 267         }
 268
 269         if (nbd_cmd(req) == NBD_CMD_WRITE) {
 270                 struct req_iterator iter;
 271                 struct bio_vec bvec;
 272                 /*
 273                  * we are really probing at internals to determine
 274                  * whether to set MSG_MORE or not...
 275                  */
 276                 rq_for_each_segment(bvec, req, iter) {
 277                         flags = 0;
 278                         if (!rq_iter_last(bvec, iter))
 279                                 flags = MSG_MORE;
 280                         dprintk(DBG_TX, "%s: request %p: sending %d bytes data\n",
 281                                         nbd->disk->disk_name, req, bvec.bv_len);
 282                         result = sock_send_bvec(nbd, &bvec, flags);
 283                         if (result <= 0) {
 284                                 dev_err(disk_to_dev(nbd->disk),
 285                                         "Send data failed (result %d)\n",
 286                                         result);
 287                                 goto error_out;
 288                         }
 289                 }
 290         }
 291         return 0;
 292
 293 error_out:
 294         return -EIO;
 295 }
 296
 297 static struct request *nbd_find_request(struct nbd_device *nbd,
 298                                         struct request *xreq)
 299 {
 300         struct request *req, *tmp;
 301         int err;
 302
 303         err = wait_event_interruptible(nbd->active_wq, nbd->active_req != xreq);
 304         if (unlikely(err))
 305                 goto out;
 306
 307         spin_lock(&nbd->queue_lock);
 308         list_for_each_entry_safe(req, tmp, &nbd->queue_head, queuelist) {
 309                 if (req != xreq)
 310                         continue;
 311                 list_del_init(&req->queuelist);
 312                 spin_unlock(&nbd->queue_lock);
 313                 return req;
 314         }
 315         spin_unlock(&nbd->queue_lock);
 316
 317         err = -ENOENT;
 318
 319 out:
 320         return ERR_PTR(err);
 321 }
 322
 323 static inline int sock_recv_bvec(struct nbd_device *nbd, struct bio_vec *bvec)
 324 {
 325         int result;
 326         void *kaddr = kmap(bvec->bv_page);
 327         result = sock_xmit(nbd, 0, kaddr + bvec->bv_offset, bvec->bv_len,
 328                         MSG_WAITALL);
 329         kunmap(bvec->bv_page);
 330         return result;
 331 }
 332
 333 /* NULL returned = something went wrong, inform userspace */
 334 static struct request *nbd_read_stat(struct nbd_device *nbd)
 335 {
 336         int result;
 337         struct nbd_reply reply;
 338         struct request *req;
 339
 340         reply.magic = 0;
 341         result = sock_xmit(nbd, 0, &reply, sizeof(reply), MSG_WAITALL);
 342         if (result <= 0) {
 343                 dev_err(disk_to_dev(nbd->disk),
 344                         "Receive control failed (result %d)\n", result);
 345                 goto harderror;
 346         }
 347
 348         if (ntohl(reply.magic) != NBD_REPLY_MAGIC) {
 349                 dev_err(disk_to_dev(nbd->disk), "Wrong magic (0x%lx)\n",
 350                                 (unsigned long)ntohl(reply.magic));
 351                 result = -EPROTO;
 352                 goto harderror;
 353         }
 354
 355         req = nbd_find_request(nbd, *(struct request **)reply.handle);
 356         if (IS_ERR(req)) {
 357                 result = PTR_ERR(req);
 358                 if (result != -ENOENT)
 359                         goto harderror;
 360
 361                 dev_err(disk_to_dev(nbd->disk), "Unexpected reply (%p)\n",
 362                         reply.handle);
 363                 result = -EBADR;
 364                 goto harderror;
 365         }
 366
 367         if (ntohl(reply.error)) {
 368                 dev_err(disk_to_dev(nbd->disk), "Other side returned error (%d)\n",
 369                         ntohl(reply.error));
 370                 req->errors++;
 371                 return req;
 372         }
 373
 374         dprintk(DBG_RX, "%s: request %p: got reply\n",
 375                         nbd->disk->disk_name, req);
 376         if (nbd_cmd(req) == NBD_CMD_READ) {
 377                 struct req_iterator iter;
 378                 struct bio_vec bvec;
 379
 380                 rq_for_each_segment(bvec, req, iter) {
 381                         result = sock_recv_bvec(nbd, &bvec);
 382                         if (result <= 0) {
 383                                 dev_err(disk_to_dev(nbd->disk), "Receive data failed (result %d)\n",
 384                                         result);
 385                                 req->errors++;
 386                                 return req;
 387                         }
 388                         dprintk(DBG_RX, "%s: request %p: got %d bytes data\n",
 389                                 nbd->disk->disk_name, req, bvec.bv_len);
 390                 }
 391         }
 392         return req;
 393 harderror:
 394         nbd->harderror = result;
 395         return NULL;
 396 }
 397
 398 static ssize_t pid_show(struct device *dev,
 399                         struct device_attribute *attr, char *buf)
 400 {
 401         struct gendisk *disk = dev_to_disk(dev);
 402
 403         return sprintf(buf, "%ld\n",
 404                 (long) ((struct nbd_device *)disk->private_data)->pid);
 405 }
 406
 407 static struct device_attribute pid_attr = {
 408         .attr = { .name = "pid", .mode = S_IRUGO},
 409         .show = pid_show,
 410 };
 411
 412 static int nbd_do_it(struct nbd_device *nbd)
 413 {
 414         struct request *req;
 415         int ret;
 416
 417         BUG_ON(nbd->magic != NBD_MAGIC);
 418
 419         sk_set_memalloc(nbd->sock->sk);
 420         nbd->pid = task_pid_nr(current);
 421         ret = device_create_file(disk_to_dev(nbd->disk), &pid_attr);
 422         if (ret) {
 423                 dev_err(disk_to_dev(nbd->disk), "device_create_file failed!\n");
 424                 nbd->pid = 0;
 425                 return ret;
 426         }
 427
 428         while ((req = nbd_read_stat(nbd)) != NULL)
 429                 nbd_end_request(req);
 430
 431         device_remove_file(disk_to_dev(nbd->disk), &pid_attr);
 432         nbd->pid = 0;
 433         return 0;
 434 }
 435
 436 static void nbd_clear_que(struct nbd_device *nbd)
 437 {
 438         struct request *req;
 439
 440         BUG_ON(nbd->magic != NBD_MAGIC);
 441
 442         /*
 443          * Because we have set nbd->sock to NULL under the tx_lock, all
 444          * modifications to the list must have completed by now.  For
 445          * the same reason, the active_req must be NULL.
 446          *
 447          * As a consequence, we don't need to take the spin lock while
 448          * purging the list here.
 449          */
 450         BUG_ON(nbd->sock);
 451         BUG_ON(nbd->active_req);
 452
 453         while (!list_empty(&nbd->queue_head)) {
 454                 req = list_entry(nbd->queue_head.next, struct request,
 455                                  queuelist);
 456                 list_del_init(&req->queuelist);
 457                 req->errors++;
 458                 nbd_end_request(req);
 459         }
 460
 461         while (!list_empty(&nbd->waiting_queue)) {
 462                 req = list_entry(nbd->waiting_queue.next, struct request,
 463                                  queuelist);
 464                 list_del_init(&req->queuelist);
 465                 req->errors++;
 466                 nbd_end_request(req);
 467         }
 468 }
 469
 470
 471 static void nbd_handle_req(struct nbd_device *nbd, struct request *req)
 472 {
 473         if (req->cmd_type != REQ_TYPE_FS)
 474                 goto error_out;
 475
 476         nbd_cmd(req) = NBD_CMD_READ;
 477         if (rq_data_dir(req) == WRITE) {
 478                 if ((req->cmd_flags & REQ_DISCARD)) {
 479                         WARN_ON(!(nbd->flags & NBD_FLAG_SEND_TRIM));
 480                         nbd_cmd(req) = NBD_CMD_TRIM;
 481                 } else
 482                         nbd_cmd(req) = NBD_CMD_WRITE;
 483                 if (nbd->flags & NBD_FLAG_READ_ONLY) {
 484                         dev_err(disk_to_dev(nbd->disk),
 485                                 "Write on read-only\n");
 486                         goto error_out;
 487                 }
 488         }
 489
 490         if (req->cmd_flags & REQ_FLUSH) {
 491                 BUG_ON(unlikely(blk_rq_sectors(req)));
 492                 nbd_cmd(req) = NBD_CMD_FLUSH;
 493         }
 494
 495         req->errors = 0;
 496
 497         mutex_lock(&nbd->tx_lock);
 498         if (unlikely(!nbd->sock)) {
 499                 mutex_unlock(&nbd->tx_lock);
 500                 dev_err(disk_to_dev(nbd->disk),
 501                         "Attempted send on closed socket\n");
 502                 goto error_out;
 503         }
 504
 505         nbd->active_req = req;
 506
 507         if (nbd_send_req(nbd, req) != 0) {
 508                 dev_err(disk_to_dev(nbd->disk), "Request send failed\n");
 509                 req->errors++;
 510                 nbd_end_request(req);
 511         } else {
 512                 spin_lock(&nbd->queue_lock);
 513                 list_add_tail(&req->queuelist, &nbd->queue_head);
 514                 spin_unlock(&nbd->queue_lock);
 515         }
 516
 517         nbd->active_req = NULL;
 518         mutex_unlock(&nbd->tx_lock);
 519         wake_up_all(&nbd->active_wq);
 520
 521         return;
 522
 523 error_out:
 524         req->errors++;
 525         nbd_end_request(req);
 526 }
 527
 528 static int nbd_thread(void *data)
 529 {
 530         struct nbd_device *nbd = data;
 531         struct request *req;
 532
 533         set_user_nice(current, MIN_NICE);
 534         while (!kthread_should_stop() || !list_empty(&nbd->waiting_queue)) {
 535                 /* wait for something to do */
 536                 wait_event_interruptible(nbd->waiting_wq,
 537                                          kthread_should_stop() ||
 538                                          !list_empty(&nbd->waiting_queue));
 539
 540                 /* extract request */
 541                 if (list_empty(&nbd->waiting_queue))
 542                         continue;
 543
 544                 spin_lock_irq(&nbd->queue_lock);
 545                 req = list_entry(nbd->waiting_queue.next, struct request,
 546                                  queuelist);
 547                 list_del_init(&req->queuelist);
 548                 spin_unlock_irq(&nbd->queue_lock);
 549
 550                 /* handle request */
 551                 nbd_handle_req(nbd, req);
 552         }
 553         return 0;
 554 }
 555
 556 /*
 557  * We always wait for result of write, for now. It would be nice to make it optional
 558  * in future
 559  * if ((rq_data_dir(req) == WRITE) && (nbd->flags & NBD_WRITE_NOCHK))
 560  *   { printk( "Warning: Ignoring result!\n"); nbd_end_request( req ); }
 561  */
 562
 563 static void do_nbd_request(struct request_queue *q)
 564                 __releases(q->queue_lock) __acquires(q->queue_lock)
 565 {
 566         struct request *req;
 567
 568         while ((req = blk_fetch_request(q)) != NULL) {
 569                 struct nbd_device *nbd;
 570
 571                 spin_unlock_irq(q->queue_lock);
 572
 573                 dprintk(DBG_BLKDEV, "%s: request %p: dequeued (flags=%x)\n",
 574                                 req->rq_disk->disk_name, req, req->cmd_type);
 575
 576                 nbd = req->rq_disk->private_data;
 577
 578                 BUG_ON(nbd->magic != NBD_MAGIC);
 579
 580                 if (unlikely(!nbd->sock)) {
 581                         dev_err(disk_to_dev(nbd->disk),
 582                                 "Attempted send on closed socket\n");
 583                         req->errors++;
 584                         nbd_end_request(req);
 585                         spin_lock_irq(q->queue_lock);
 586                         continue;
 587                 }
 588
 589                 spin_lock_irq(&nbd->queue_lock);
 590                 list_add_tail(&req->queuelist, &nbd->waiting_queue);
 591                 spin_unlock_irq(&nbd->queue_lock);
 592
 593                 wake_up(&nbd->waiting_wq);
 594
 595                 spin_lock_irq(q->queue_lock);
 596         }
 597 }
 598
 599 /* Must be called with tx_lock held */
 600
 601 static int __nbd_ioctl(struct block_device *bdev, struct nbd_device *nbd,
 602                        unsigned int cmd, unsigned long arg)
 603 {
 604         switch (cmd) {
 605         case NBD_DISCONNECT: {
 606                 struct request sreq;
 607
 608                 dev_info(disk_to_dev(nbd->disk), "NBD_DISCONNECT\n");
 609                 if (!nbd->sock)
 610                         return -EINVAL;
 611
 612                 mutex_unlock(&nbd->tx_lock);
 613                 fsync_bdev(bdev);
 614                 mutex_lock(&nbd->tx_lock);
 615                 blk_rq_init(NULL, &sreq);
 616                 sreq.cmd_type = REQ_TYPE_SPECIAL;
 617                 nbd_cmd(&sreq) = NBD_CMD_DISC;
 618
 619                 /* Check again after getting mutex back.  */
 620                 if (!nbd->sock)
 621                         return -EINVAL;
 622
 623                 nbd->disconnect = 1;
 624
 625                 nbd_send_req(nbd, &sreq);
 626                 return 0;
 627         }
 628
 629         case NBD_CLEAR_SOCK: {
 630                 struct socket *sock = nbd->sock;
 631                 nbd->sock = NULL;
 632                 nbd_clear_que(nbd);
 633                 BUG_ON(!list_empty(&nbd->queue_head));
 634                 BUG_ON(!list_empty(&nbd->waiting_queue));
 635                 kill_bdev(bdev);
 636                 if (sock)
 637                         sockfd_put(sock);
 638                 return 0;
 639         }
 640
 641         case NBD_SET_SOCK: {
 642                 struct socket *sock;
 643                 int err;
 644                 if (nbd->sock)
 645                         return -EBUSY;
 646                 sock = sockfd_lookup(arg, &err);
 647                 if (sock) {
 648                         nbd->sock = sock;
 649                         if (max_part > 0)
 650                                 bdev->bd_invalidated = 1;
 651                         nbd->disconnect = 0; /* we're connected now */
 652                         return 0;
 653                 }
 654                 return -EINVAL;
 655         }
 656
 657         case NBD_SET_BLKSIZE:
 658                 nbd->blksize = arg;
 659                 nbd->bytesize &= ~(nbd->blksize-1);
 660                 bdev->bd_inode->i_size = nbd->bytesize;
 661                 set_blocksize(bdev, nbd->blksize);
 662                 set_capacity(nbd->disk, nbd->bytesize >> 9);
 663                 return 0;
 664
 665         case NBD_SET_SIZE:
 666                 nbd->bytesize = arg & ~(nbd->blksize-1);
 667                 bdev->bd_inode->i_size = nbd->bytesize;
 668                 set_blocksize(bdev, nbd->blksize);
 669                 set_capacity(nbd->disk, nbd->bytesize >> 9);
 670                 return 0;
 671
 672         case NBD_SET_TIMEOUT:
 673                 nbd->xmit_timeout = arg * HZ;
 674                 return 0;
 675
 676         case NBD_SET_FLAGS:
 677                 nbd->flags = arg;
 678                 return 0;
 679
 680         case NBD_SET_SIZE_BLOCKS:
 681                 nbd->bytesize = ((u64) arg) * nbd->blksize;
 682                 bdev->bd_inode->i_size = nbd->bytesize;
 683                 set_blocksize(bdev, nbd->blksize);
 684                 set_capacity(nbd->disk, nbd->bytesize >> 9);
 685                 return 0;
 686
 687         case NBD_DO_IT: {
 688                 struct task_struct *thread;
 689                 struct socket *sock;
 690                 int error;
 691
 692                 if (nbd->pid)
 693                         return -EBUSY;
 694                 if (!nbd->sock)
 695                         return -EINVAL;
 696
 697                 mutex_unlock(&nbd->tx_lock);
 698
 699                 if (nbd->flags & NBD_FLAG_READ_ONLY)
 700                         set_device_ro(bdev, true);
 701                 if (nbd->flags & NBD_FLAG_SEND_TRIM)
 702                         queue_flag_set_unlocked(QUEUE_FLAG_DISCARD,
 703                                 nbd->disk->queue);
 704                 if (nbd->flags & NBD_FLAG_SEND_FLUSH)
 705                         blk_queue_flush(nbd->disk->queue, REQ_FLUSH);
 706                 else
 707                         blk_queue_flush(nbd->disk->queue, 0);
 708
 709                 thread = kthread_create(nbd_thread, nbd, "%s",
 710                                         nbd->disk->disk_name);
 711                 if (IS_ERR(thread)) {
 712                         mutex_lock(&nbd->tx_lock);
 713                         return PTR_ERR(thread);
 714                 }
 715                 wake_up_process(thread);
 716                 error = nbd_do_it(nbd);
 717                 kthread_stop(thread);
 718
 719                 mutex_lock(&nbd->tx_lock);
 720                 if (error)
 721                         return error;
 722                 sock_shutdown(nbd, 0);
 723                 sock = nbd->sock;
 724                 nbd->sock = NULL;
 725                 nbd_clear_que(nbd);
 726                 dev_warn(disk_to_dev(nbd->disk), "queue cleared\n");
 727                 kill_bdev(bdev);
 728                 queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, nbd->disk->queue);
 729                 set_device_ro(bdev, false);
 730                 if (sock)
 731                         sockfd_put(sock);
 732                 nbd->flags = 0;
 733                 nbd->bytesize = 0;
 734                 bdev->bd_inode->i_size = 0;
 735                 set_capacity(nbd->disk, 0);
 736                 if (max_part > 0)
 737                         ioctl_by_bdev(bdev, BLKRRPART, 0);
 738                 if (nbd->disconnect) /* user requested, ignore socket errors */
 739                         return 0;
 740                 return nbd->harderror;
 741         }
 742
 743         case NBD_CLEAR_QUE:
 744                 /*
 745                  * This is for compatibility only.  The queue is always cleared
 746                  * by NBD_DO_IT or NBD_CLEAR_SOCK.
 747                  */
 748                 return 0;
 749
 750         case NBD_PRINT_DEBUG:
 751                 dev_info(disk_to_dev(nbd->disk),
 752                         "next = %p, prev = %p, head = %p\n",
 753                         nbd->queue_head.next, nbd->queue_head.prev,
 754                         &nbd->queue_head);
 755                 return 0;
 756         }
 757         return -ENOTTY;
 758 }
 759
 760 static int nbd_ioctl(struct block_device *bdev, fmode_t mode,
 761                      unsigned int cmd, unsigned long arg)
 762 {
 763         struct nbd_device *nbd = bdev->bd_disk->private_data;
 764         int error;
 765
 766         if (!capable(CAP_SYS_ADMIN))
 767                 return -EPERM;
 768
 769         BUG_ON(nbd->magic != NBD_MAGIC);
 770
 771         /* Anyone capable of this syscall can do *real bad* things */
 772         dprintk(DBG_IOCTL, "%s: nbd_ioctl cmd=%s(0x%x) arg=%lu\n",
 773                 nbd->disk->disk_name, ioctl_cmd_to_ascii(cmd), cmd, arg);
 774
 775         mutex_lock(&nbd->tx_lock);
 776         error = __nbd_ioctl(bdev, nbd, cmd, arg);
 777         mutex_unlock(&nbd->tx_lock);
 778
 779         return error;
 780 }
 781
 782 static const struct block_device_operations nbd_fops =
 783 {
 784         .owner =        THIS_MODULE,
 785         .ioctl =        nbd_ioctl,
 786 };
 787
 788 /*
 789  * And here should be modules and kernel interface
 790  *  (Just smiley confuses emacs :-)
 791  */
 792
 793 static int __init nbd_init(void)
 794 {
 795         int err = -ENOMEM;
 796         int i;
 797         int part_shift;
 798
 799         BUILD_BUG_ON(sizeof(struct nbd_request) != 28);
 800
 801         if (max_part < 0) {
 802                 printk(KERN_ERR "nbd: max_part must be >= 0\n");
 803                 return -EINVAL;
 804         }
 805
 806         nbd_dev = kcalloc(nbds_max, sizeof(*nbd_dev), GFP_KERNEL);
 807         if (!nbd_dev)
 808                 return -ENOMEM;
 809
 810         part_shift = 0;
 811         if (max_part > 0) {
 812                 part_shift = fls(max_part);
 813
 814                 /*
 815                  * Adjust max_part according to part_shift as it is exported
 816                  * to user space so that user can know the max number of
 817                  * partition kernel should be able to manage.
 818                  *
 819                  * Note that -1 is required because partition 0 is reserved
 820                  * for the whole disk.
 821                  */
 822                 max_part = (1UL << part_shift) - 1;
 823         }
 824
 825         if ((1UL << part_shift) > DISK_MAX_PARTS)
 826                 return -EINVAL;
 827
 828         if (nbds_max > 1UL << (MINORBITS - part_shift))
 829                 return -EINVAL;
 830
 831         for (i = 0; i < nbds_max; i++) {
 832                 struct gendisk *disk = alloc_disk(1 << part_shift);
 833                 if (!disk)
 834                         goto out;
 835                 nbd_dev[i].disk = disk;
 836                 /*
 837                  * The new linux 2.5 block layer implementation requires
 838                  * every gendisk to have its very own request_queue struct.
 839                  * These structs are big so we dynamically allocate them.
 840                  */
 841                 disk->queue = blk_init_queue(do_nbd_request, &nbd_lock);
 842                 if (!disk->queue) {
 843                         put_disk(disk);
 844                         goto out;
 845                 }
 846                 /*
 847                  * Tell the block layer that we are not a rotational device
 848                  */
 849                 queue_flag_set_unlocked(QUEUE_FLAG_NONROT, disk->queue);
 850                 disk->queue->limits.discard_granularity = 512;
 851                 disk->queue->limits.max_discard_sectors = UINT_MAX;
 852                 disk->queue->limits.discard_zeroes_data = 0;
 853                 blk_queue_max_hw_sectors(disk->queue, 65536);
 854                 disk->queue->limits.max_sectors = 256;
 855         }
 856
 857         if (register_blkdev(NBD_MAJOR, "nbd")) {
 858                 err = -EIO;
 859                 goto out;
 860         }
 861
 862         printk(KERN_INFO "nbd: registered device at major %d\n", NBD_MAJOR);
 863         dprintk(DBG_INIT, "nbd: debugflags=0x%x\n", debugflags);
 864
 865         for (i = 0; i < nbds_max; i++) {
 866                 struct gendisk *disk = nbd_dev[i].disk;
 867                 nbd_dev[i].magic = NBD_MAGIC;
 868                 INIT_LIST_HEAD(&nbd_dev[i].waiting_queue);
 869                 spin_lock_init(&nbd_dev[i].queue_lock);
 870                 INIT_LIST_HEAD(&nbd_dev[i].queue_head);
 871                 mutex_init(&nbd_dev[i].tx_lock);
 872                 init_waitqueue_head(&nbd_dev[i].active_wq);
 873                 init_waitqueue_head(&nbd_dev[i].waiting_wq);
 874                 nbd_dev[i].blksize = 1024;
 875                 nbd_dev[i].bytesize = 0;
 876                 disk->major = NBD_MAJOR;
 877                 disk->first_minor = i << part_shift;
 878                 disk->fops = &nbd_fops;
 879                 disk->private_data = &nbd_dev[i];
 880                 sprintf(disk->disk_name, "nbd%d", i);
 881                 set_capacity(disk, 0);
 882                 add_disk(disk);
 883         }
 884
 885         return 0;
 886 out:
 887         while (i--) {
 888                 blk_cleanup_queue(nbd_dev[i].disk->queue);
 889                 put_disk(nbd_dev[i].disk);
 890         }
 891         kfree(nbd_dev);
 892         return err;
 893 }
 894
 895 static void __exit nbd_cleanup(void)
 896 {
 897         int i;
 898         for (i = 0; i < nbds_max; i++) {
 899                 struct gendisk *disk = nbd_dev[i].disk;
 900                 nbd_dev[i].magic = 0;
 901                 if (disk) {
 902                         del_gendisk(disk);
 903                         blk_cleanup_queue(disk->queue);
 904                         put_disk(disk);
 905                 }
 906         }
 907         unregister_blkdev(NBD_MAJOR, "nbd");
 908         kfree(nbd_dev);
 909         printk(KERN_INFO "nbd: unregistered device at major %d\n", NBD_MAJOR);
 910 }
 911
 912 module_init(nbd_init);
 913 module_exit(nbd_cleanup);
 914
 915 MODULE_DESCRIPTION("Network Block Device");
 916 MODULE_LICENSE("GPL");
 917
 918 module_param(nbds_max, int, 0444);
 919 MODULE_PARM_DESC(nbds_max, "number of network block devices to initialize (default: 16)");
 920 module_param(max_part, int, 0444);
 921 MODULE_PARM_DESC(max_part, "number of partitions per device (default: 0)");
 922 #ifndef NDEBUG
 923 module_param(debugflags, int, 0644);
 924 MODULE_PARM_DESC(debugflags, "flags for controlling debug output");
 925 #endif