linux/net/9p/trans_virtio.c
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   1/*
   2 * The Virtio 9p transport driver
   3 *
   4 * This is a block based transport driver based on the lguest block driver
   5 * code.
   6 *
   7 *  Copyright (C) 2007, 2008 Eric Van Hensbergen, IBM Corporation
   8 *
   9 *  Based on virtio console driver
  10 *  Copyright (C) 2006, 2007 Rusty Russell, IBM Corporation
  11 *
  12 *  This program is free software; you can redistribute it and/or modify
  13 *  it under the terms of the GNU General Public License version 2
  14 *  as published by the Free Software Foundation.
  15 *
  16 *  This program is distributed in the hope that it will be useful,
  17 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  18 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19 *  GNU General Public License for more details.
  20 *
  21 *  You should have received a copy of the GNU General Public License
  22 *  along with this program; if not, write to:
  23 *  Free Software Foundation
  24 *  51 Franklin Street, Fifth Floor
  25 *  Boston, MA  02111-1301  USA
  26 *
  27 */
  28
  29#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  30
  31#include <linux/in.h>
  32#include <linux/module.h>
  33#include <linux/net.h>
  34#include <linux/ipv6.h>
  35#include <linux/errno.h>
  36#include <linux/kernel.h>
  37#include <linux/un.h>
  38#include <linux/uaccess.h>
  39#include <linux/inet.h>
  40#include <linux/idr.h>
  41#include <linux/file.h>
  42#include <linux/highmem.h>
  43#include <linux/slab.h>
  44#include <net/9p/9p.h>
  45#include <linux/parser.h>
  46#include <net/9p/client.h>
  47#include <net/9p/transport.h>
  48#include <linux/scatterlist.h>
  49#include <linux/swap.h>
  50#include <linux/virtio.h>
  51#include <linux/virtio_9p.h>
  52#include "trans_common.h"
  53
  54#define VIRTQUEUE_NUM   128
  55
  56/* a single mutex to manage channel initialization and attachment */
  57static DEFINE_MUTEX(virtio_9p_lock);
  58static DECLARE_WAIT_QUEUE_HEAD(vp_wq);
  59static atomic_t vp_pinned = ATOMIC_INIT(0);
  60
  61/**
  62 * struct virtio_chan - per-instance transport information
  63 * @initialized: whether the channel is initialized
  64 * @inuse: whether the channel is in use
  65 * @lock: protects multiple elements within this structure
  66 * @client: client instance
  67 * @vdev: virtio dev associated with this channel
  68 * @vq: virtio queue associated with this channel
  69 * @sg: scatter gather list which is used to pack a request (protected?)
  70 *
  71 * We keep all per-channel information in a structure.
  72 * This structure is allocated within the devices dev->mem space.
  73 * A pointer to the structure will get put in the transport private.
  74 *
  75 */
  76
  77struct virtio_chan {
  78        bool inuse;
  79
  80        spinlock_t lock;
  81
  82        struct p9_client *client;
  83        struct virtio_device *vdev;
  84        struct virtqueue *vq;
  85        int ring_bufs_avail;
  86        wait_queue_head_t *vc_wq;
  87        /* This is global limit. Since we don't have a global structure,
  88         * will be placing it in each channel.
  89         */
  90        int p9_max_pages;
  91        /* Scatterlist: can be too big for stack. */
  92        struct scatterlist sg[VIRTQUEUE_NUM];
  93
  94        int tag_len;
  95        /*
  96         * tag name to identify a mount Non-null terminated
  97         */
  98        char *tag;
  99
 100        struct list_head chan_list;
 101};
 102
 103static struct list_head virtio_chan_list;
 104
 105/* How many bytes left in this page. */
 106static unsigned int rest_of_page(void *data)
 107{
 108        return PAGE_SIZE - ((unsigned long)data % PAGE_SIZE);
 109}
 110
 111/**
 112 * p9_virtio_close - reclaim resources of a channel
 113 * @client: client instance
 114 *
 115 * This reclaims a channel by freeing its resources and
 116 * reseting its inuse flag.
 117 *
 118 */
 119
 120static void p9_virtio_close(struct p9_client *client)
 121{
 122        struct virtio_chan *chan = client->trans;
 123
 124        mutex_lock(&virtio_9p_lock);
 125        if (chan)
 126                chan->inuse = false;
 127        mutex_unlock(&virtio_9p_lock);
 128}
 129
 130/**
 131 * req_done - callback which signals activity from the server
 132 * @vq: virtio queue activity was received on
 133 *
 134 * This notifies us that the server has triggered some activity
 135 * on the virtio channel - most likely a response to request we
 136 * sent.  Figure out which requests now have responses and wake up
 137 * those threads.
 138 *
 139 * Bugs: could do with some additional sanity checking, but appears to work.
 140 *
 141 */
 142
 143static void req_done(struct virtqueue *vq)
 144{
 145        struct virtio_chan *chan = vq->vdev->priv;
 146        struct p9_fcall *rc;
 147        unsigned int len;
 148        struct p9_req_t *req;
 149        unsigned long flags;
 150
 151        p9_debug(P9_DEBUG_TRANS, ": request done\n");
 152
 153        while (1) {
 154                spin_lock_irqsave(&chan->lock, flags);
 155                rc = virtqueue_get_buf(chan->vq, &len);
 156                if (rc == NULL) {
 157                        spin_unlock_irqrestore(&chan->lock, flags);
 158                        break;
 159                }
 160                chan->ring_bufs_avail = 1;
 161                spin_unlock_irqrestore(&chan->lock, flags);
 162                /* Wakeup if anyone waiting for VirtIO ring space. */
 163                wake_up(chan->vc_wq);
 164                p9_debug(P9_DEBUG_TRANS, ": rc %p\n", rc);
 165                p9_debug(P9_DEBUG_TRANS, ": lookup tag %d\n", rc->tag);
 166                req = p9_tag_lookup(chan->client, rc->tag);
 167                req->status = REQ_STATUS_RCVD;
 168                p9_client_cb(chan->client, req);
 169        }
 170}
 171
 172/**
 173 * pack_sg_list - pack a scatter gather list from a linear buffer
 174 * @sg: scatter/gather list to pack into
 175 * @start: which segment of the sg_list to start at
 176 * @limit: maximum segment to pack data to
 177 * @data: data to pack into scatter/gather list
 178 * @count: amount of data to pack into the scatter/gather list
 179 *
 180 * sg_lists have multiple segments of various sizes.  This will pack
 181 * arbitrary data into an existing scatter gather list, segmenting the
 182 * data as necessary within constraints.
 183 *
 184 */
 185
 186static int pack_sg_list(struct scatterlist *sg, int start,
 187                        int limit, char *data, int count)
 188{
 189        int s;
 190        int index = start;
 191
 192        while (count) {
 193                s = rest_of_page(data);
 194                if (s > count)
 195                        s = count;
 196                BUG_ON(index > limit);
 197                sg_set_buf(&sg[index++], data, s);
 198                count -= s;
 199                data += s;
 200        }
 201
 202        return index-start;
 203}
 204
 205/* We don't currently allow canceling of virtio requests */
 206static int p9_virtio_cancel(struct p9_client *client, struct p9_req_t *req)
 207{
 208        return 1;
 209}
 210
 211/**
 212 * pack_sg_list_p - Just like pack_sg_list. Instead of taking a buffer,
 213 * this takes a list of pages.
 214 * @sg: scatter/gather list to pack into
 215 * @start: which segment of the sg_list to start at
 216 * @pdata: a list of pages to add into sg.
 217 * @nr_pages: number of pages to pack into the scatter/gather list
 218 * @data: data to pack into scatter/gather list
 219 * @count: amount of data to pack into the scatter/gather list
 220 */
 221static int
 222pack_sg_list_p(struct scatterlist *sg, int start, int limit,
 223               struct page **pdata, int nr_pages, char *data, int count)
 224{
 225        int i = 0, s;
 226        int data_off;
 227        int index = start;
 228
 229        BUG_ON(nr_pages > (limit - start));
 230        /*
 231         * if the first page doesn't start at
 232         * page boundary find the offset
 233         */
 234        data_off = offset_in_page(data);
 235        while (nr_pages) {
 236                s = rest_of_page(data);
 237                if (s > count)
 238                        s = count;
 239                sg_set_page(&sg[index++], pdata[i++], s, data_off);
 240                data_off = 0;
 241                data += s;
 242                count -= s;
 243                nr_pages--;
 244        }
 245        return index - start;
 246}
 247
 248/**
 249 * p9_virtio_request - issue a request
 250 * @client: client instance issuing the request
 251 * @req: request to be issued
 252 *
 253 */
 254
 255static int
 256p9_virtio_request(struct p9_client *client, struct p9_req_t *req)
 257{
 258        int err;
 259        int in, out;
 260        unsigned long flags;
 261        struct virtio_chan *chan = client->trans;
 262
 263        p9_debug(P9_DEBUG_TRANS, "9p debug: virtio request\n");
 264
 265        req->status = REQ_STATUS_SENT;
 266req_retry:
 267        spin_lock_irqsave(&chan->lock, flags);
 268
 269        /* Handle out VirtIO ring buffers */
 270        out = pack_sg_list(chan->sg, 0,
 271                           VIRTQUEUE_NUM, req->tc->sdata, req->tc->size);
 272
 273        in = pack_sg_list(chan->sg, out,
 274                          VIRTQUEUE_NUM, req->rc->sdata, req->rc->capacity);
 275
 276        err = virtqueue_add_buf(chan->vq, chan->sg, out, in, req->tc,
 277                                GFP_ATOMIC);
 278        if (err < 0) {
 279                if (err == -ENOSPC) {
 280                        chan->ring_bufs_avail = 0;
 281                        spin_unlock_irqrestore(&chan->lock, flags);
 282                        err = wait_event_interruptible(*chan->vc_wq,
 283                                                        chan->ring_bufs_avail);
 284                        if (err  == -ERESTARTSYS)
 285                                return err;
 286
 287                        p9_debug(P9_DEBUG_TRANS, "Retry virtio request\n");
 288                        goto req_retry;
 289                } else {
 290                        spin_unlock_irqrestore(&chan->lock, flags);
 291                        p9_debug(P9_DEBUG_TRANS,
 292                                 "virtio rpc add_buf returned failure\n");
 293                        return -EIO;
 294                }
 295        }
 296        virtqueue_kick(chan->vq);
 297        spin_unlock_irqrestore(&chan->lock, flags);
 298
 299        p9_debug(P9_DEBUG_TRANS, "virtio request kicked\n");
 300        return 0;
 301}
 302
 303static int p9_get_mapped_pages(struct virtio_chan *chan,
 304                               struct page **pages, char *data,
 305                               int nr_pages, int write, int kern_buf)
 306{
 307        int err;
 308        if (!kern_buf) {
 309                /*
 310                 * We allow only p9_max_pages pinned. We wait for the
 311                 * Other zc request to finish here
 312                 */
 313                if (atomic_read(&vp_pinned) >= chan->p9_max_pages) {
 314                        err = wait_event_interruptible(vp_wq,
 315                              (atomic_read(&vp_pinned) < chan->p9_max_pages));
 316                        if (err == -ERESTARTSYS)
 317                                return err;
 318                }
 319                err = p9_payload_gup(data, &nr_pages, pages, write);
 320                if (err < 0)
 321                        return err;
 322                atomic_add(nr_pages, &vp_pinned);
 323        } else {
 324                /* kernel buffer, no need to pin pages */
 325                int s, index = 0;
 326                int count = nr_pages;
 327                while (nr_pages) {
 328                        s = rest_of_page(data);
 329                        pages[index++] = kmap_to_page(data);
 330                        data += s;
 331                        nr_pages--;
 332                }
 333                nr_pages = count;
 334        }
 335        return nr_pages;
 336}
 337
 338/**
 339 * p9_virtio_zc_request - issue a zero copy request
 340 * @client: client instance issuing the request
 341 * @req: request to be issued
 342 * @uidata: user bffer that should be ued for zero copy read
 343 * @uodata: user buffer that shoud be user for zero copy write
 344 * @inlen: read buffer size
 345 * @olen: write buffer size
 346 * @hdrlen: reader header size, This is the size of response protocol data
 347 *
 348 */
 349static int
 350p9_virtio_zc_request(struct p9_client *client, struct p9_req_t *req,
 351                     char *uidata, char *uodata, int inlen,
 352                     int outlen, int in_hdr_len, int kern_buf)
 353{
 354        int in, out, err;
 355        unsigned long flags;
 356        int in_nr_pages = 0, out_nr_pages = 0;
 357        struct page **in_pages = NULL, **out_pages = NULL;
 358        struct virtio_chan *chan = client->trans;
 359
 360        p9_debug(P9_DEBUG_TRANS, "virtio request\n");
 361
 362        if (uodata) {
 363                out_nr_pages = p9_nr_pages(uodata, outlen);
 364                out_pages = kmalloc(sizeof(struct page *) * out_nr_pages,
 365                                    GFP_NOFS);
 366                if (!out_pages) {
 367                        err = -ENOMEM;
 368                        goto err_out;
 369                }
 370                out_nr_pages = p9_get_mapped_pages(chan, out_pages, uodata,
 371                                                   out_nr_pages, 0, kern_buf);
 372                if (out_nr_pages < 0) {
 373                        err = out_nr_pages;
 374                        kfree(out_pages);
 375                        out_pages = NULL;
 376                        goto err_out;
 377                }
 378        }
 379        if (uidata) {
 380                in_nr_pages = p9_nr_pages(uidata, inlen);
 381                in_pages = kmalloc(sizeof(struct page *) * in_nr_pages,
 382                                   GFP_NOFS);
 383                if (!in_pages) {
 384                        err = -ENOMEM;
 385                        goto err_out;
 386                }
 387                in_nr_pages = p9_get_mapped_pages(chan, in_pages, uidata,
 388                                                  in_nr_pages, 1, kern_buf);
 389                if (in_nr_pages < 0) {
 390                        err = in_nr_pages;
 391                        kfree(in_pages);
 392                        in_pages = NULL;
 393                        goto err_out;
 394                }
 395        }
 396        req->status = REQ_STATUS_SENT;
 397req_retry_pinned:
 398        spin_lock_irqsave(&chan->lock, flags);
 399        /* out data */
 400        out = pack_sg_list(chan->sg, 0,
 401                           VIRTQUEUE_NUM, req->tc->sdata, req->tc->size);
 402
 403        if (out_pages)
 404                out += pack_sg_list_p(chan->sg, out, VIRTQUEUE_NUM,
 405                                      out_pages, out_nr_pages, uodata, outlen);
 406        /*
 407         * Take care of in data
 408         * For example TREAD have 11.
 409         * 11 is the read/write header = PDU Header(7) + IO Size (4).
 410         * Arrange in such a way that server places header in the
 411         * alloced memory and payload onto the user buffer.
 412         */
 413        in = pack_sg_list(chan->sg, out,
 414                          VIRTQUEUE_NUM, req->rc->sdata, in_hdr_len);
 415        if (in_pages)
 416                in += pack_sg_list_p(chan->sg, out + in, VIRTQUEUE_NUM,
 417                                     in_pages, in_nr_pages, uidata, inlen);
 418
 419        err = virtqueue_add_buf(chan->vq, chan->sg, out, in, req->tc,
 420                                GFP_ATOMIC);
 421        if (err < 0) {
 422                if (err == -ENOSPC) {
 423                        chan->ring_bufs_avail = 0;
 424                        spin_unlock_irqrestore(&chan->lock, flags);
 425                        err = wait_event_interruptible(*chan->vc_wq,
 426                                                       chan->ring_bufs_avail);
 427                        if (err  == -ERESTARTSYS)
 428                                goto err_out;
 429
 430                        p9_debug(P9_DEBUG_TRANS, "Retry virtio request\n");
 431                        goto req_retry_pinned;
 432                } else {
 433                        spin_unlock_irqrestore(&chan->lock, flags);
 434                        p9_debug(P9_DEBUG_TRANS,
 435                                 "virtio rpc add_buf returned failure\n");
 436                        err = -EIO;
 437                        goto err_out;
 438                }
 439        }
 440        virtqueue_kick(chan->vq);
 441        spin_unlock_irqrestore(&chan->lock, flags);
 442        p9_debug(P9_DEBUG_TRANS, "virtio request kicked\n");
 443        err = wait_event_interruptible(*req->wq,
 444                                       req->status >= REQ_STATUS_RCVD);
 445        /*
 446         * Non kernel buffers are pinned, unpin them
 447         */
 448err_out:
 449        if (!kern_buf) {
 450                if (in_pages) {
 451                        p9_release_pages(in_pages, in_nr_pages);
 452                        atomic_sub(in_nr_pages, &vp_pinned);
 453                }
 454                if (out_pages) {
 455                        p9_release_pages(out_pages, out_nr_pages);
 456                        atomic_sub(out_nr_pages, &vp_pinned);
 457                }
 458                /* wakeup anybody waiting for slots to pin pages */
 459                wake_up(&vp_wq);
 460        }
 461        kfree(in_pages);
 462        kfree(out_pages);
 463        return err;
 464}
 465
 466static ssize_t p9_mount_tag_show(struct device *dev,
 467                                struct device_attribute *attr, char *buf)
 468{
 469        struct virtio_chan *chan;
 470        struct virtio_device *vdev;
 471
 472        vdev = dev_to_virtio(dev);
 473        chan = vdev->priv;
 474
 475        return snprintf(buf, chan->tag_len + 1, "%s", chan->tag);
 476}
 477
 478static DEVICE_ATTR(mount_tag, 0444, p9_mount_tag_show, NULL);
 479
 480/**
 481 * p9_virtio_probe - probe for existence of 9P virtio channels
 482 * @vdev: virtio device to probe
 483 *
 484 * This probes for existing virtio channels.
 485 *
 486 */
 487
 488static int p9_virtio_probe(struct virtio_device *vdev)
 489{
 490        __u16 tag_len;
 491        char *tag;
 492        int err;
 493        struct virtio_chan *chan;
 494
 495        chan = kmalloc(sizeof(struct virtio_chan), GFP_KERNEL);
 496        if (!chan) {
 497                pr_err("Failed to allocate virtio 9P channel\n");
 498                err = -ENOMEM;
 499                goto fail;
 500        }
 501
 502        chan->vdev = vdev;
 503
 504        /* We expect one virtqueue, for requests. */
 505        chan->vq = virtio_find_single_vq(vdev, req_done, "requests");
 506        if (IS_ERR(chan->vq)) {
 507                err = PTR_ERR(chan->vq);
 508                goto out_free_vq;
 509        }
 510        chan->vq->vdev->priv = chan;
 511        spin_lock_init(&chan->lock);
 512
 513        sg_init_table(chan->sg, VIRTQUEUE_NUM);
 514
 515        chan->inuse = false;
 516        if (virtio_has_feature(vdev, VIRTIO_9P_MOUNT_TAG)) {
 517                vdev->config->get(vdev,
 518                                offsetof(struct virtio_9p_config, tag_len),
 519                                &tag_len, sizeof(tag_len));
 520        } else {
 521                err = -EINVAL;
 522                goto out_free_vq;
 523        }
 524        tag = kmalloc(tag_len, GFP_KERNEL);
 525        if (!tag) {
 526                err = -ENOMEM;
 527                goto out_free_vq;
 528        }
 529        vdev->config->get(vdev, offsetof(struct virtio_9p_config, tag),
 530                        tag, tag_len);
 531        chan->tag = tag;
 532        chan->tag_len = tag_len;
 533        err = sysfs_create_file(&(vdev->dev.kobj), &dev_attr_mount_tag.attr);
 534        if (err) {
 535                goto out_free_tag;
 536        }
 537        chan->vc_wq = kmalloc(sizeof(wait_queue_head_t), GFP_KERNEL);
 538        if (!chan->vc_wq) {
 539                err = -ENOMEM;
 540                goto out_free_tag;
 541        }
 542        init_waitqueue_head(chan->vc_wq);
 543        chan->ring_bufs_avail = 1;
 544        /* Ceiling limit to avoid denial of service attacks */
 545        chan->p9_max_pages = nr_free_buffer_pages()/4;
 546
 547        mutex_lock(&virtio_9p_lock);
 548        list_add_tail(&chan->chan_list, &virtio_chan_list);
 549        mutex_unlock(&virtio_9p_lock);
 550        return 0;
 551
 552out_free_tag:
 553        kfree(tag);
 554out_free_vq:
 555        vdev->config->del_vqs(vdev);
 556        kfree(chan);
 557fail:
 558        return err;
 559}
 560
 561
 562/**
 563 * p9_virtio_create - allocate a new virtio channel
 564 * @client: client instance invoking this transport
 565 * @devname: string identifying the channel to connect to (unused)
 566 * @args: args passed from sys_mount() for per-transport options (unused)
 567 *
 568 * This sets up a transport channel for 9p communication.  Right now
 569 * we only match the first available channel, but eventually we couldlook up
 570 * alternate channels by matching devname versus a virtio_config entry.
 571 * We use a simple reference count mechanism to ensure that only a single
 572 * mount has a channel open at a time.
 573 *
 574 */
 575
 576static int
 577p9_virtio_create(struct p9_client *client, const char *devname, char *args)
 578{
 579        struct virtio_chan *chan;
 580        int ret = -ENOENT;
 581        int found = 0;
 582
 583        mutex_lock(&virtio_9p_lock);
 584        list_for_each_entry(chan, &virtio_chan_list, chan_list) {
 585                if (!strncmp(devname, chan->tag, chan->tag_len) &&
 586                    strlen(devname) == chan->tag_len) {
 587                        if (!chan->inuse) {
 588                                chan->inuse = true;
 589                                found = 1;
 590                                break;
 591                        }
 592                        ret = -EBUSY;
 593                }
 594        }
 595        mutex_unlock(&virtio_9p_lock);
 596
 597        if (!found) {
 598                pr_err("no channels available\n");
 599                return ret;
 600        }
 601
 602        client->trans = (void *)chan;
 603        client->status = Connected;
 604        chan->client = client;
 605
 606        return 0;
 607}
 608
 609/**
 610 * p9_virtio_remove - clean up resources associated with a virtio device
 611 * @vdev: virtio device to remove
 612 *
 613 */
 614
 615static void p9_virtio_remove(struct virtio_device *vdev)
 616{
 617        struct virtio_chan *chan = vdev->priv;
 618
 619        if (chan->inuse)
 620                p9_virtio_close(chan->client);
 621        vdev->config->del_vqs(vdev);
 622
 623        mutex_lock(&virtio_9p_lock);
 624        list_del(&chan->chan_list);
 625        mutex_unlock(&virtio_9p_lock);
 626        sysfs_remove_file(&(vdev->dev.kobj), &dev_attr_mount_tag.attr);
 627        kfree(chan->tag);
 628        kfree(chan->vc_wq);
 629        kfree(chan);
 630
 631}
 632
 633static struct virtio_device_id id_table[] = {
 634        { VIRTIO_ID_9P, VIRTIO_DEV_ANY_ID },
 635        { 0 },
 636};
 637
 638static unsigned int features[] = {
 639        VIRTIO_9P_MOUNT_TAG,
 640};
 641
 642/* The standard "struct lguest_driver": */
 643static struct virtio_driver p9_virtio_drv = {
 644        .feature_table  = features,
 645        .feature_table_size = ARRAY_SIZE(features),
 646        .driver.name    = KBUILD_MODNAME,
 647        .driver.owner   = THIS_MODULE,
 648        .id_table       = id_table,
 649        .probe          = p9_virtio_probe,
 650        .remove         = p9_virtio_remove,
 651};
 652
 653static struct p9_trans_module p9_virtio_trans = {
 654        .name = "virtio",
 655        .create = p9_virtio_create,
 656        .close = p9_virtio_close,
 657        .request = p9_virtio_request,
 658        .zc_request = p9_virtio_zc_request,
 659        .cancel = p9_virtio_cancel,
 660        /*
 661         * We leave one entry for input and one entry for response
 662         * headers. We also skip one more entry to accomodate, address
 663         * that are not at page boundary, that can result in an extra
 664         * page in zero copy.
 665         */
 666        .maxsize = PAGE_SIZE * (VIRTQUEUE_NUM - 3),
 667        .def = 0,
 668        .owner = THIS_MODULE,
 669};
 670
 671/* The standard init function */
 672static int __init p9_virtio_init(void)
 673{
 674        INIT_LIST_HEAD(&virtio_chan_list);
 675
 676        v9fs_register_trans(&p9_virtio_trans);
 677        return register_virtio_driver(&p9_virtio_drv);
 678}
 679
 680static void __exit p9_virtio_cleanup(void)
 681{
 682        unregister_virtio_driver(&p9_virtio_drv);
 683        v9fs_unregister_trans(&p9_virtio_trans);
 684}
 685
 686module_init(p9_virtio_init);
 687module_exit(p9_virtio_cleanup);
 688
 689MODULE_DEVICE_TABLE(virtio, id_table);
 690MODULE_AUTHOR("Eric Van Hensbergen <ericvh@gmail.com>");
 691MODULE_DESCRIPTION("Virtio 9p Transport");
 692MODULE_LICENSE("GPL");
 693
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