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