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[linux/fpc-iii.git] / net / 9p / trans_virtio.c
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1 /*
2 * The Virtio 9p transport driver
4 * This is a block based transport driver based on the lguest block driver
5 * code.
7 * Copyright (C) 2007, 2008 Eric Van Hensbergen, IBM Corporation
9 * Based on virtio console driver
10 * Copyright (C) 2006, 2007 Rusty Russell, IBM Corporation
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.
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.
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
29 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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"
54 #define VIRTQUEUE_NUM 128
56 /* a single mutex to manage channel initialization and attachment */
57 static DEFINE_MUTEX(virtio_9p_lock);
58 static DECLARE_WAIT_QUEUE_HEAD(vp_wq);
59 static atomic_t vp_pinned = ATOMIC_INIT(0);
61 /**
62 * struct virtio_chan - per-instance transport information
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?)
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.
76 struct virtio_chan {
77 bool inuse;
79 spinlock_t lock;
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.
89 unsigned long p9_max_pages;
90 /* Scatterlist: can be too big for stack. */
91 struct scatterlist sg[VIRTQUEUE_NUM];
93 int tag_len;
95 * tag name to identify a mount Non-null terminated
97 char *tag;
99 struct list_head chan_list;
102 static struct list_head virtio_chan_list;
104 /* How many bytes left in this page. */
105 static unsigned int rest_of_page(void *data)
107 return PAGE_SIZE - offset_in_page(data);
111 * p9_virtio_close - reclaim resources of a channel
112 * @client: client instance
114 * This reclaims a channel by freeing its resources and
115 * reseting its inuse flag.
119 static void p9_virtio_close(struct p9_client *client)
121 struct virtio_chan *chan = client->trans;
123 mutex_lock(&virtio_9p_lock);
124 if (chan)
125 chan->inuse = false;
126 mutex_unlock(&virtio_9p_lock);
130 * req_done - callback which signals activity from the server
131 * @vq: virtio queue activity was received on
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.
138 * Bugs: could do with some additional sanity checking, but appears to work.
142 static void req_done(struct virtqueue *vq)
144 struct virtio_chan *chan = vq->vdev->priv;
145 unsigned int len;
146 struct p9_req_t *req;
147 unsigned long flags;
149 p9_debug(P9_DEBUG_TRANS, ": request done\n");
151 while (1) {
152 spin_lock_irqsave(&chan->lock, flags);
153 req = virtqueue_get_buf(chan->vq, &len);
154 if (req == NULL) {
155 spin_unlock_irqrestore(&chan->lock, flags);
156 break;
158 chan->ring_bufs_avail = 1;
159 spin_unlock_irqrestore(&chan->lock, flags);
160 /* Wakeup if anyone waiting for VirtIO ring space. */
161 wake_up(chan->vc_wq);
162 if (len)
163 p9_client_cb(chan->client, req, REQ_STATUS_RCVD);
168 * pack_sg_list - pack a scatter gather list from a linear buffer
169 * @sg: scatter/gather list to pack into
170 * @start: which segment of the sg_list to start at
171 * @limit: maximum segment to pack data to
172 * @data: data to pack into scatter/gather list
173 * @count: amount of data to pack into the scatter/gather list
175 * sg_lists have multiple segments of various sizes. This will pack
176 * arbitrary data into an existing scatter gather list, segmenting the
177 * data as necessary within constraints.
181 static int pack_sg_list(struct scatterlist *sg, int start,
182 int limit, char *data, int count)
184 int s;
185 int index = start;
187 while (count) {
188 s = rest_of_page(data);
189 if (s > count)
190 s = count;
191 BUG_ON(index >= limit);
192 /* Make sure we don't terminate early. */
193 sg_unmark_end(&sg[index]);
194 sg_set_buf(&sg[index++], data, s);
195 count -= s;
196 data += s;
198 if (index-start)
199 sg_mark_end(&sg[index - 1]);
200 return index-start;
203 /* We don't currently allow canceling of virtio requests */
204 static int p9_virtio_cancel(struct p9_client *client, struct p9_req_t *req)
206 return 1;
210 * pack_sg_list_p - Just like pack_sg_list. Instead of taking a buffer,
211 * this takes a list of pages.
212 * @sg: scatter/gather list to pack into
213 * @start: which segment of the sg_list to start at
214 * @pdata: a list of pages to add into sg.
215 * @nr_pages: number of pages to pack into the scatter/gather list
216 * @offs: amount of data in the beginning of first page _not_ to pack
217 * @count: amount of data to pack into the scatter/gather list
219 static int
220 pack_sg_list_p(struct scatterlist *sg, int start, int limit,
221 struct page **pdata, int nr_pages, size_t offs, int count)
223 int i = 0, s;
224 int data_off = offs;
225 int index = start;
227 BUG_ON(nr_pages > (limit - start));
229 * if the first page doesn't start at
230 * page boundary find the offset
232 while (nr_pages) {
233 s = PAGE_SIZE - data_off;
234 if (s > count)
235 s = count;
236 BUG_ON(index >= limit);
237 /* Make sure we don't terminate early. */
238 sg_unmark_end(&sg[index]);
239 sg_set_page(&sg[index++], pdata[i++], s, data_off);
240 data_off = 0;
241 count -= s;
242 nr_pages--;
245 if (index-start)
246 sg_mark_end(&sg[index - 1]);
247 return index - start;
251 * p9_virtio_request - issue a request
252 * @client: client instance issuing the request
253 * @req: request to be issued
257 static int
258 p9_virtio_request(struct p9_client *client, struct p9_req_t *req)
260 int err;
261 int in, out, out_sgs, in_sgs;
262 unsigned long flags;
263 struct virtio_chan *chan = client->trans;
264 struct scatterlist *sgs[2];
266 p9_debug(P9_DEBUG_TRANS, "9p debug: virtio request\n");
268 req->status = REQ_STATUS_SENT;
269 req_retry:
270 spin_lock_irqsave(&chan->lock, flags);
272 out_sgs = in_sgs = 0;
273 /* Handle out VirtIO ring buffers */
274 out = pack_sg_list(chan->sg, 0,
275 VIRTQUEUE_NUM, req->tc->sdata, req->tc->size);
276 if (out)
277 sgs[out_sgs++] = chan->sg;
279 in = pack_sg_list(chan->sg, out,
280 VIRTQUEUE_NUM, req->rc->sdata, req->rc->capacity);
281 if (in)
282 sgs[out_sgs + in_sgs++] = chan->sg + out;
284 err = virtqueue_add_sgs(chan->vq, sgs, out_sgs, in_sgs, req,
285 GFP_ATOMIC);
286 if (err < 0) {
287 if (err == -ENOSPC) {
288 chan->ring_bufs_avail = 0;
289 spin_unlock_irqrestore(&chan->lock, flags);
290 err = wait_event_killable(*chan->vc_wq,
291 chan->ring_bufs_avail);
292 if (err == -ERESTARTSYS)
293 return err;
295 p9_debug(P9_DEBUG_TRANS, "Retry virtio request\n");
296 goto req_retry;
297 } else {
298 spin_unlock_irqrestore(&chan->lock, flags);
299 p9_debug(P9_DEBUG_TRANS,
300 "virtio rpc add_sgs returned failure\n");
301 return -EIO;
304 virtqueue_kick(chan->vq);
305 spin_unlock_irqrestore(&chan->lock, flags);
307 p9_debug(P9_DEBUG_TRANS, "virtio request kicked\n");
308 return 0;
311 static int p9_get_mapped_pages(struct virtio_chan *chan,
312 struct page ***pages,
313 struct iov_iter *data,
314 int count,
315 size_t *offs,
316 int *need_drop)
318 int nr_pages;
319 int err;
321 if (!iov_iter_count(data))
322 return 0;
324 if (!(data->type & ITER_KVEC)) {
325 int n;
327 * We allow only p9_max_pages pinned. We wait for the
328 * Other zc request to finish here
330 if (atomic_read(&vp_pinned) >= chan->p9_max_pages) {
331 err = wait_event_killable(vp_wq,
332 (atomic_read(&vp_pinned) < chan->p9_max_pages));
333 if (err == -ERESTARTSYS)
334 return err;
336 n = iov_iter_get_pages_alloc(data, pages, count, offs);
337 if (n < 0)
338 return n;
339 *need_drop = 1;
340 nr_pages = DIV_ROUND_UP(n + *offs, PAGE_SIZE);
341 atomic_add(nr_pages, &vp_pinned);
342 return n;
343 } else {
344 /* kernel buffer, no need to pin pages */
345 int index;
346 size_t len;
347 void *p;
349 /* we'd already checked that it's non-empty */
350 while (1) {
351 len = iov_iter_single_seg_count(data);
352 if (likely(len)) {
353 p = data->kvec->iov_base + data->iov_offset;
354 break;
356 iov_iter_advance(data, 0);
358 if (len > count)
359 len = count;
361 nr_pages = DIV_ROUND_UP((unsigned long)p + len, PAGE_SIZE) -
362 (unsigned long)p / PAGE_SIZE;
364 *pages = kmalloc_array(nr_pages, sizeof(struct page *),
365 GFP_NOFS);
366 if (!*pages)
367 return -ENOMEM;
369 *need_drop = 0;
370 p -= (*offs = offset_in_page(p));
371 for (index = 0; index < nr_pages; index++) {
372 if (is_vmalloc_addr(p))
373 (*pages)[index] = vmalloc_to_page(p);
374 else
375 (*pages)[index] = kmap_to_page(p);
376 p += PAGE_SIZE;
378 return len;
383 * p9_virtio_zc_request - issue a zero copy request
384 * @client: client instance issuing the request
385 * @req: request to be issued
386 * @uidata: user bffer that should be ued for zero copy read
387 * @uodata: user buffer that shoud be user for zero copy write
388 * @inlen: read buffer size
389 * @outlen: write buffer size
390 * @in_hdr_len: reader header size, This is the size of response protocol data
393 static int
394 p9_virtio_zc_request(struct p9_client *client, struct p9_req_t *req,
395 struct iov_iter *uidata, struct iov_iter *uodata,
396 int inlen, int outlen, int in_hdr_len)
398 int in, out, err, out_sgs, in_sgs;
399 unsigned long flags;
400 int in_nr_pages = 0, out_nr_pages = 0;
401 struct page **in_pages = NULL, **out_pages = NULL;
402 struct virtio_chan *chan = client->trans;
403 struct scatterlist *sgs[4];
404 size_t offs;
405 int need_drop = 0;
407 p9_debug(P9_DEBUG_TRANS, "virtio request\n");
409 if (uodata) {
410 __le32 sz;
411 int n = p9_get_mapped_pages(chan, &out_pages, uodata,
412 outlen, &offs, &need_drop);
413 if (n < 0)
414 return n;
415 out_nr_pages = DIV_ROUND_UP(n + offs, PAGE_SIZE);
416 if (n != outlen) {
417 __le32 v = cpu_to_le32(n);
418 memcpy(&req->tc->sdata[req->tc->size - 4], &v, 4);
419 outlen = n;
421 /* The size field of the message must include the length of the
422 * header and the length of the data. We didn't actually know
423 * the length of the data until this point so add it in now.
425 sz = cpu_to_le32(req->tc->size + outlen);
426 memcpy(&req->tc->sdata[0], &sz, sizeof(sz));
427 } else if (uidata) {
428 int n = p9_get_mapped_pages(chan, &in_pages, uidata,
429 inlen, &offs, &need_drop);
430 if (n < 0)
431 return n;
432 in_nr_pages = DIV_ROUND_UP(n + offs, PAGE_SIZE);
433 if (n != inlen) {
434 __le32 v = cpu_to_le32(n);
435 memcpy(&req->tc->sdata[req->tc->size - 4], &v, 4);
436 inlen = n;
439 req->status = REQ_STATUS_SENT;
440 req_retry_pinned:
441 spin_lock_irqsave(&chan->lock, flags);
443 out_sgs = in_sgs = 0;
445 /* out data */
446 out = pack_sg_list(chan->sg, 0,
447 VIRTQUEUE_NUM, req->tc->sdata, req->tc->size);
449 if (out)
450 sgs[out_sgs++] = chan->sg;
452 if (out_pages) {
453 sgs[out_sgs++] = chan->sg + out;
454 out += pack_sg_list_p(chan->sg, out, VIRTQUEUE_NUM,
455 out_pages, out_nr_pages, offs, outlen);
459 * Take care of in data
460 * For example TREAD have 11.
461 * 11 is the read/write header = PDU Header(7) + IO Size (4).
462 * Arrange in such a way that server places header in the
463 * alloced memory and payload onto the user buffer.
465 in = pack_sg_list(chan->sg, out,
466 VIRTQUEUE_NUM, req->rc->sdata, in_hdr_len);
467 if (in)
468 sgs[out_sgs + in_sgs++] = chan->sg + out;
470 if (in_pages) {
471 sgs[out_sgs + in_sgs++] = chan->sg + out + in;
472 in += pack_sg_list_p(chan->sg, out + in, VIRTQUEUE_NUM,
473 in_pages, in_nr_pages, offs, inlen);
476 BUG_ON(out_sgs + in_sgs > ARRAY_SIZE(sgs));
477 err = virtqueue_add_sgs(chan->vq, sgs, out_sgs, in_sgs, req,
478 GFP_ATOMIC);
479 if (err < 0) {
480 if (err == -ENOSPC) {
481 chan->ring_bufs_avail = 0;
482 spin_unlock_irqrestore(&chan->lock, flags);
483 err = wait_event_killable(*chan->vc_wq,
484 chan->ring_bufs_avail);
485 if (err == -ERESTARTSYS)
486 goto err_out;
488 p9_debug(P9_DEBUG_TRANS, "Retry virtio request\n");
489 goto req_retry_pinned;
490 } else {
491 spin_unlock_irqrestore(&chan->lock, flags);
492 p9_debug(P9_DEBUG_TRANS,
493 "virtio rpc add_sgs returned failure\n");
494 err = -EIO;
495 goto err_out;
498 virtqueue_kick(chan->vq);
499 spin_unlock_irqrestore(&chan->lock, flags);
500 p9_debug(P9_DEBUG_TRANS, "virtio request kicked\n");
501 err = wait_event_killable(*req->wq, req->status >= REQ_STATUS_RCVD);
503 * Non kernel buffers are pinned, unpin them
505 err_out:
506 if (need_drop) {
507 if (in_pages) {
508 p9_release_pages(in_pages, in_nr_pages);
509 atomic_sub(in_nr_pages, &vp_pinned);
511 if (out_pages) {
512 p9_release_pages(out_pages, out_nr_pages);
513 atomic_sub(out_nr_pages, &vp_pinned);
515 /* wakeup anybody waiting for slots to pin pages */
516 wake_up(&vp_wq);
518 kvfree(in_pages);
519 kvfree(out_pages);
520 return err;
523 static ssize_t p9_mount_tag_show(struct device *dev,
524 struct device_attribute *attr, char *buf)
526 struct virtio_chan *chan;
527 struct virtio_device *vdev;
529 vdev = dev_to_virtio(dev);
530 chan = vdev->priv;
532 memcpy(buf, chan->tag, chan->tag_len);
533 buf[chan->tag_len] = 0;
535 return chan->tag_len + 1;
538 static DEVICE_ATTR(mount_tag, 0444, p9_mount_tag_show, NULL);
541 * p9_virtio_probe - probe for existence of 9P virtio channels
542 * @vdev: virtio device to probe
544 * This probes for existing virtio channels.
548 static int p9_virtio_probe(struct virtio_device *vdev)
550 __u16 tag_len;
551 char *tag;
552 int err;
553 struct virtio_chan *chan;
555 if (!vdev->config->get) {
556 dev_err(&vdev->dev, "%s failure: config access disabled\n",
557 __func__);
558 return -EINVAL;
561 chan = kmalloc(sizeof(struct virtio_chan), GFP_KERNEL);
562 if (!chan) {
563 pr_err("Failed to allocate virtio 9P channel\n");
564 err = -ENOMEM;
565 goto fail;
568 chan->vdev = vdev;
570 /* We expect one virtqueue, for requests. */
571 chan->vq = virtio_find_single_vq(vdev, req_done, "requests");
572 if (IS_ERR(chan->vq)) {
573 err = PTR_ERR(chan->vq);
574 goto out_free_chan;
576 chan->vq->vdev->priv = chan;
577 spin_lock_init(&chan->lock);
579 sg_init_table(chan->sg, VIRTQUEUE_NUM);
581 chan->inuse = false;
582 if (virtio_has_feature(vdev, VIRTIO_9P_MOUNT_TAG)) {
583 virtio_cread(vdev, struct virtio_9p_config, tag_len, &tag_len);
584 } else {
585 err = -EINVAL;
586 goto out_free_vq;
588 tag = kmalloc(tag_len, GFP_KERNEL);
589 if (!tag) {
590 err = -ENOMEM;
591 goto out_free_vq;
594 virtio_cread_bytes(vdev, offsetof(struct virtio_9p_config, tag),
595 tag, tag_len);
596 chan->tag = tag;
597 chan->tag_len = tag_len;
598 err = sysfs_create_file(&(vdev->dev.kobj), &dev_attr_mount_tag.attr);
599 if (err) {
600 goto out_free_tag;
602 chan->vc_wq = kmalloc(sizeof(wait_queue_head_t), GFP_KERNEL);
603 if (!chan->vc_wq) {
604 err = -ENOMEM;
605 goto out_free_tag;
607 init_waitqueue_head(chan->vc_wq);
608 chan->ring_bufs_avail = 1;
609 /* Ceiling limit to avoid denial of service attacks */
610 chan->p9_max_pages = nr_free_buffer_pages()/4;
612 virtio_device_ready(vdev);
614 mutex_lock(&virtio_9p_lock);
615 list_add_tail(&chan->chan_list, &virtio_chan_list);
616 mutex_unlock(&virtio_9p_lock);
618 /* Let udev rules use the new mount_tag attribute. */
619 kobject_uevent(&(vdev->dev.kobj), KOBJ_CHANGE);
621 return 0;
623 out_free_tag:
624 kfree(tag);
625 out_free_vq:
626 vdev->config->del_vqs(vdev);
627 out_free_chan:
628 kfree(chan);
629 fail:
630 return err;
635 * p9_virtio_create - allocate a new virtio channel
636 * @client: client instance invoking this transport
637 * @devname: string identifying the channel to connect to (unused)
638 * @args: args passed from sys_mount() for per-transport options (unused)
640 * This sets up a transport channel for 9p communication. Right now
641 * we only match the first available channel, but eventually we couldlook up
642 * alternate channels by matching devname versus a virtio_config entry.
643 * We use a simple reference count mechanism to ensure that only a single
644 * mount has a channel open at a time.
648 static int
649 p9_virtio_create(struct p9_client *client, const char *devname, char *args)
651 struct virtio_chan *chan;
652 int ret = -ENOENT;
653 int found = 0;
655 if (devname == NULL)
656 return -EINVAL;
658 mutex_lock(&virtio_9p_lock);
659 list_for_each_entry(chan, &virtio_chan_list, chan_list) {
660 if (!strncmp(devname, chan->tag, chan->tag_len) &&
661 strlen(devname) == chan->tag_len) {
662 if (!chan->inuse) {
663 chan->inuse = true;
664 found = 1;
665 break;
667 ret = -EBUSY;
670 mutex_unlock(&virtio_9p_lock);
672 if (!found) {
673 pr_err("no channels available for device %s\n", devname);
674 return ret;
677 client->trans = (void *)chan;
678 client->status = Connected;
679 chan->client = client;
681 return 0;
685 * p9_virtio_remove - clean up resources associated with a virtio device
686 * @vdev: virtio device to remove
690 static void p9_virtio_remove(struct virtio_device *vdev)
692 struct virtio_chan *chan = vdev->priv;
693 unsigned long warning_time;
695 mutex_lock(&virtio_9p_lock);
697 /* Remove self from list so we don't get new users. */
698 list_del(&chan->chan_list);
699 warning_time = jiffies;
701 /* Wait for existing users to close. */
702 while (chan->inuse) {
703 mutex_unlock(&virtio_9p_lock);
704 msleep(250);
705 if (time_after(jiffies, warning_time + 10 * HZ)) {
706 dev_emerg(&vdev->dev,
707 "p9_virtio_remove: waiting for device in use.\n");
708 warning_time = jiffies;
710 mutex_lock(&virtio_9p_lock);
713 mutex_unlock(&virtio_9p_lock);
715 vdev->config->reset(vdev);
716 vdev->config->del_vqs(vdev);
718 sysfs_remove_file(&(vdev->dev.kobj), &dev_attr_mount_tag.attr);
719 kobject_uevent(&(vdev->dev.kobj), KOBJ_CHANGE);
720 kfree(chan->tag);
721 kfree(chan->vc_wq);
722 kfree(chan);
726 static struct virtio_device_id id_table[] = {
727 { VIRTIO_ID_9P, VIRTIO_DEV_ANY_ID },
728 { 0 },
731 static unsigned int features[] = {
732 VIRTIO_9P_MOUNT_TAG,
735 /* The standard "struct lguest_driver": */
736 static struct virtio_driver p9_virtio_drv = {
737 .feature_table = features,
738 .feature_table_size = ARRAY_SIZE(features),
739 .driver.name = KBUILD_MODNAME,
740 .driver.owner = THIS_MODULE,
741 .id_table = id_table,
742 .probe = p9_virtio_probe,
743 .remove = p9_virtio_remove,
746 static struct p9_trans_module p9_virtio_trans = {
747 .name = "virtio",
748 .create = p9_virtio_create,
749 .close = p9_virtio_close,
750 .request = p9_virtio_request,
751 .zc_request = p9_virtio_zc_request,
752 .cancel = p9_virtio_cancel,
754 * We leave one entry for input and one entry for response
755 * headers. We also skip one more entry to accomodate, address
756 * that are not at page boundary, that can result in an extra
757 * page in zero copy.
759 .maxsize = PAGE_SIZE * (VIRTQUEUE_NUM - 3),
760 .def = 1,
761 .owner = THIS_MODULE,
764 /* The standard init function */
765 static int __init p9_virtio_init(void)
767 INIT_LIST_HEAD(&virtio_chan_list);
769 v9fs_register_trans(&p9_virtio_trans);
770 return register_virtio_driver(&p9_virtio_drv);
773 static void __exit p9_virtio_cleanup(void)
775 unregister_virtio_driver(&p9_virtio_drv);
776 v9fs_unregister_trans(&p9_virtio_trans);
779 module_init(p9_virtio_init);
780 module_exit(p9_virtio_cleanup);
782 MODULE_DEVICE_TABLE(virtio, id_table);
783 MODULE_AUTHOR("Eric Van Hensbergen <ericvh@gmail.com>");
784 MODULE_DESCRIPTION("Virtio 9p Transport");
785 MODULE_LICENSE("GPL");