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