1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * The Virtio 9p transport driver
4 *
5 * This is a block based transport driver based on the lguest block driver
6 * code.
7 *
8 * Copyright (C) 2007, 2008 Eric Van Hensbergen, IBM Corporation
9 *
10 * Based on virtio console driver
11 * Copyright (C) 2006, 2007 Rusty Russell, IBM Corporation
12 */
13
14 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
15
16 #include <linux/in.h>
17 #include <linux/module.h>
18 #include <linux/net.h>
19 #include <linux/ipv6.h>
20 #include <linux/errno.h>
21 #include <linux/kernel.h>
22 #include <linux/un.h>
23 #include <linux/uaccess.h>
24 #include <linux/inet.h>
25 #include <linux/file.h>
26 #include <linux/highmem.h>
27 #include <linux/slab.h>
28 #include <net/9p/9p.h>
29 #include <linux/parser.h>
30 #include <net/9p/client.h>
31 #include <net/9p/transport.h>
32 #include <linux/scatterlist.h>
33 #include <linux/swap.h>
34 #include <linux/virtio.h>
35 #include <linux/virtio_9p.h>
36 #include "trans_common.h"
37
38 #define VIRTQUEUE_NUM 128
39
40 /* a single mutex to manage channel initialization and attachment */
41 static DEFINE_MUTEX(virtio_9p_lock);
42 static DECLARE_WAIT_QUEUE_HEAD(vp_wq);
43 static atomic_t vp_pinned = ATOMIC_INIT(0);
44
45 /**
46 * struct virtio_chan - per-instance transport information
47 * @inuse: whether the channel is in use
48 * @lock: protects multiple elements within this structure
49 * @client: client instance
50 * @vdev: virtio dev associated with this channel
51 * @vq: virtio queue associated with this channel
52 * @ring_bufs_avail: flag to indicate there is some available in the ring buf
53 * @vc_wq: wait queue for waiting for thing to be added to ring buf
54 * @p9_max_pages: maximum number of pinned pages
55 * @sg: scatter gather list which is used to pack a request (protected?)
56 * @chan_list: linked list of channels
57 *
58 * We keep all per-channel information in a structure.
59 * This structure is allocated within the devices dev->mem space.
60 * A pointer to the structure will get put in the transport private.
61 *
62 */
63
64 struct virtio_chan {
65 bool inuse;
66
67 spinlock_t lock;
68
69 struct p9_client *client;
70 struct virtio_device *vdev;
71 struct virtqueue *vq;
72 int ring_bufs_avail;
73 wait_queue_head_t *vc_wq;
74 /* This is global limit. Since we don't have a global structure,
75 * will be placing it in each channel.
76 */
77 unsigned long p9_max_pages;
78 /* Scatterlist: can be too big for stack. */
79 struct scatterlist sg[VIRTQUEUE_NUM];
80 /**
81 * @tag: name to identify a mount null terminated
82 */
83 char *tag;
84
85 struct list_head chan_list;
86 };
87
88 static struct list_head virtio_chan_list;
89
90 /* How many bytes left in this page. */
rest_of_page(void * data)91 static unsigned int rest_of_page(void *data)
92 {
93 return PAGE_SIZE - offset_in_page(data);
94 }
95
96 /**
97 * p9_virtio_close - reclaim resources of a channel
98 * @client: client instance
99 *
100 * This reclaims a channel by freeing its resources and
101 * resetting its inuse flag.
102 *
103 */
104
p9_virtio_close(struct p9_client * client)105 static void p9_virtio_close(struct p9_client *client)
106 {
107 struct virtio_chan *chan = client->trans;
108
109 mutex_lock(&virtio_9p_lock);
110 if (chan)
111 chan->inuse = false;
112 mutex_unlock(&virtio_9p_lock);
113 }
114
115 /**
116 * req_done - callback which signals activity from the server
117 * @vq: virtio queue activity was received on
118 *
119 * This notifies us that the server has triggered some activity
120 * on the virtio channel - most likely a response to request we
121 * sent. Figure out which requests now have responses and wake up
122 * those threads.
123 *
124 * Bugs: could do with some additional sanity checking, but appears to work.
125 *
126 */
127
req_done(struct virtqueue * vq)128 static void req_done(struct virtqueue *vq)
129 {
130 struct virtio_chan *chan = vq->vdev->priv;
131 unsigned int len;
132 struct p9_req_t *req;
133 bool need_wakeup = false;
134 unsigned long flags;
135
136 p9_debug(P9_DEBUG_TRANS, ": request done\n");
137
138 spin_lock_irqsave(&chan->lock, flags);
139 while ((req = virtqueue_get_buf(chan->vq, &len)) != NULL) {
140 if (!chan->ring_bufs_avail) {
141 chan->ring_bufs_avail = 1;
142 need_wakeup = true;
143 }
144
145 if (len) {
146 req->rc.size = len;
147 p9_client_cb(chan->client, req, REQ_STATUS_RCVD);
148 }
149 }
150 spin_unlock_irqrestore(&chan->lock, flags);
151 /* Wakeup if anyone waiting for VirtIO ring space. */
152 if (need_wakeup)
153 wake_up(chan->vc_wq);
154 }
155
156 /**
157 * pack_sg_list - pack a scatter gather list from a linear buffer
158 * @sg: scatter/gather list to pack into
159 * @start: which segment of the sg_list to start at
160 * @limit: maximum segment to pack data to
161 * @data: data to pack into scatter/gather list
162 * @count: amount of data to pack into the scatter/gather list
163 *
164 * sg_lists have multiple segments of various sizes. This will pack
165 * arbitrary data into an existing scatter gather list, segmenting the
166 * data as necessary within constraints.
167 *
168 */
169
pack_sg_list(struct scatterlist * sg,int start,int limit,char * data,int count)170 static int pack_sg_list(struct scatterlist *sg, int start,
171 int limit, char *data, int count)
172 {
173 int s;
174 int index = start;
175
176 while (count) {
177 s = rest_of_page(data);
178 if (s > count)
179 s = count;
180 BUG_ON(index >= limit);
181 /* Make sure we don't terminate early. */
182 sg_unmark_end(&sg[index]);
183 sg_set_buf(&sg[index++], data, s);
184 count -= s;
185 data += s;
186 }
187 if (index-start)
188 sg_mark_end(&sg[index - 1]);
189 return index-start;
190 }
191
192 /* We don't currently allow canceling of virtio requests */
p9_virtio_cancel(struct p9_client * client,struct p9_req_t * req)193 static int p9_virtio_cancel(struct p9_client *client, struct p9_req_t *req)
194 {
195 return 1;
196 }
197
198 /* Reply won't come, so drop req ref */
p9_virtio_cancelled(struct p9_client * client,struct p9_req_t * req)199 static int p9_virtio_cancelled(struct p9_client *client, struct p9_req_t *req)
200 {
201 p9_req_put(client, req);
202 return 0;
203 }
204
205 /**
206 * pack_sg_list_p - Just like pack_sg_list. Instead of taking a buffer,
207 * this takes a list of pages.
208 * @sg: scatter/gather list to pack into
209 * @start: which segment of the sg_list to start at
210 * @limit: maximum number of pages in sg list.
211 * @pdata: a list of pages to add into sg.
212 * @nr_pages: number of pages to pack into the scatter/gather list
213 * @offs: amount of data in the beginning of first page _not_ to pack
214 * @count: amount of data to pack into the scatter/gather list
215 */
216 static int
pack_sg_list_p(struct scatterlist * sg,int start,int limit,struct page ** pdata,int nr_pages,size_t offs,int count)217 pack_sg_list_p(struct scatterlist *sg, int start, int limit,
218 struct page **pdata, int nr_pages, size_t offs, int count)
219 {
220 int i = 0, s;
221 int data_off = offs;
222 int index = start;
223
224 BUG_ON(nr_pages > (limit - start));
225 /*
226 * if the first page doesn't start at
227 * page boundary find the offset
228 */
229 while (nr_pages) {
230 s = PAGE_SIZE - data_off;
231 if (s > count)
232 s = count;
233 BUG_ON(index >= limit);
234 /* Make sure we don't terminate early. */
235 sg_unmark_end(&sg[index]);
236 sg_set_page(&sg[index++], pdata[i++], s, data_off);
237 data_off = 0;
238 count -= s;
239 nr_pages--;
240 }
241
242 if (index-start)
243 sg_mark_end(&sg[index - 1]);
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
254 static int
p9_virtio_request(struct p9_client * client,struct p9_req_t * req)255 p9_virtio_request(struct p9_client *client, struct p9_req_t *req)
256 {
257 int err;
258 int in, out, out_sgs, in_sgs;
259 unsigned long flags;
260 struct virtio_chan *chan = client->trans;
261 struct scatterlist *sgs[2];
262
263 p9_debug(P9_DEBUG_TRANS, "9p debug: virtio request\n");
264
265 WRITE_ONCE(req->status, REQ_STATUS_SENT);
266 req_retry:
267 spin_lock_irqsave(&chan->lock, flags);
268
269 out_sgs = in_sgs = 0;
270 /* Handle out VirtIO ring buffers */
271 out = pack_sg_list(chan->sg, 0,
272 VIRTQUEUE_NUM, req->tc.sdata, req->tc.size);
273 if (out)
274 sgs[out_sgs++] = chan->sg;
275
276 in = pack_sg_list(chan->sg, out,
277 VIRTQUEUE_NUM, req->rc.sdata, req->rc.capacity);
278 if (in)
279 sgs[out_sgs + in_sgs++] = chan->sg + out;
280
281 err = virtqueue_add_sgs(chan->vq, sgs, out_sgs, in_sgs, req,
282 GFP_ATOMIC);
283 if (err < 0) {
284 if (err == -ENOSPC) {
285 chan->ring_bufs_avail = 0;
286 spin_unlock_irqrestore(&chan->lock, flags);
287 err = wait_event_killable(*chan->vc_wq,
288 chan->ring_bufs_avail);
289 if (err == -ERESTARTSYS)
290 return err;
291
292 p9_debug(P9_DEBUG_TRANS, "Retry virtio request\n");
293 goto req_retry;
294 } else {
295 spin_unlock_irqrestore(&chan->lock, flags);
296 p9_debug(P9_DEBUG_TRANS,
297 "virtio rpc add_sgs returned failure\n");
298 return -EIO;
299 }
300 }
301 virtqueue_kick(chan->vq);
302 spin_unlock_irqrestore(&chan->lock, flags);
303
304 p9_debug(P9_DEBUG_TRANS, "virtio request kicked\n");
305 return 0;
306 }
307
p9_get_mapped_pages(struct virtio_chan * chan,struct page *** pages,struct iov_iter * data,int count,size_t * offs,int * need_drop)308 static int p9_get_mapped_pages(struct virtio_chan *chan,
309 struct page ***pages,
310 struct iov_iter *data,
311 int count,
312 size_t *offs,
313 int *need_drop)
314 {
315 int nr_pages;
316 int err;
317
318 if (!iov_iter_count(data))
319 return 0;
320
321 if (!iov_iter_is_kvec(data)) {
322 int n;
323 /*
324 * We allow only p9_max_pages pinned. We wait for the
325 * Other zc request to finish here
326 */
327 if (atomic_read(&vp_pinned) >= chan->p9_max_pages) {
328 err = wait_event_killable(vp_wq,
329 (atomic_read(&vp_pinned) < chan->p9_max_pages));
330 if (err == -ERESTARTSYS)
331 return err;
332 }
333 n = iov_iter_get_pages_alloc2(data, pages, count, offs);
334 if (n < 0)
335 return n;
336 *need_drop = 1;
337 nr_pages = DIV_ROUND_UP(n + *offs, PAGE_SIZE);
338 atomic_add(nr_pages, &vp_pinned);
339 return n;
340 } else {
341 /* kernel buffer, no need to pin pages */
342 int index;
343 size_t len;
344 void *p;
345
346 /* we'd already checked that it's non-empty */
347 while (1) {
348 len = iov_iter_single_seg_count(data);
349 if (likely(len)) {
350 p = data->kvec->iov_base + data->iov_offset;
351 break;
352 }
353 iov_iter_advance(data, 0);
354 }
355 if (len > count)
356 len = count;
357
358 nr_pages = DIV_ROUND_UP((unsigned long)p + len, PAGE_SIZE) -
359 (unsigned long)p / PAGE_SIZE;
360
361 *pages = kmalloc_array(nr_pages, sizeof(struct page *),
362 GFP_NOFS);
363 if (!*pages)
364 return -ENOMEM;
365
366 *need_drop = 0;
367 p -= (*offs = offset_in_page(p));
368 for (index = 0; index < nr_pages; index++) {
369 if (is_vmalloc_addr(p))
370 (*pages)[index] = vmalloc_to_page(p);
371 else
372 (*pages)[index] = kmap_to_page(p);
373 p += PAGE_SIZE;
374 }
375 iov_iter_advance(data, len);
376 return len;
377 }
378 }
379
handle_rerror(struct p9_req_t * req,int in_hdr_len,size_t offs,struct page ** pages)380 static void handle_rerror(struct p9_req_t *req, int in_hdr_len,
381 size_t offs, struct page **pages)
382 {
383 unsigned size, n;
384 void *to = req->rc.sdata + in_hdr_len;
385
386 // Fits entirely into the static data? Nothing to do.
387 if (req->rc.size < in_hdr_len || !pages)
388 return;
389
390 // Really long error message? Tough, truncate the reply. Might get
391 // rejected (we can't be arsed to adjust the size encoded in header,
392 // or string size for that matter), but it wouldn't be anything valid
393 // anyway.
394 if (unlikely(req->rc.size > P9_ZC_HDR_SZ))
395 req->rc.size = P9_ZC_HDR_SZ;
396
397 // data won't span more than two pages
398 size = req->rc.size - in_hdr_len;
399 n = PAGE_SIZE - offs;
400 if (size > n) {
401 memcpy_from_page(to, *pages++, offs, n);
402 offs = 0;
403 to += n;
404 size -= n;
405 }
406 memcpy_from_page(to, *pages, offs, size);
407 }
408
409 /**
410 * p9_virtio_zc_request - issue a zero copy request
411 * @client: client instance issuing the request
412 * @req: request to be issued
413 * @uidata: user buffer that should be used for zero copy read
414 * @uodata: user buffer that should be used for zero copy write
415 * @inlen: read buffer size
416 * @outlen: write buffer size
417 * @in_hdr_len: reader header size, This is the size of response protocol data
418 *
419 */
420 static int
p9_virtio_zc_request(struct p9_client * client,struct p9_req_t * req,struct iov_iter * uidata,struct iov_iter * uodata,int inlen,int outlen,int in_hdr_len)421 p9_virtio_zc_request(struct p9_client *client, struct p9_req_t *req,
422 struct iov_iter *uidata, struct iov_iter *uodata,
423 int inlen, int outlen, int in_hdr_len)
424 {
425 int in, out, err, out_sgs, in_sgs;
426 unsigned long flags;
427 int in_nr_pages = 0, out_nr_pages = 0;
428 struct page **in_pages = NULL, **out_pages = NULL;
429 struct virtio_chan *chan = client->trans;
430 struct scatterlist *sgs[4];
431 size_t offs = 0;
432 int need_drop = 0;
433 int kicked = 0;
434
435 p9_debug(P9_DEBUG_TRANS, "virtio request\n");
436
437 if (uodata) {
438 __le32 sz;
439 int n = p9_get_mapped_pages(chan, &out_pages, uodata,
440 outlen, &offs, &need_drop);
441 if (n < 0) {
442 err = n;
443 goto err_out;
444 }
445 out_nr_pages = DIV_ROUND_UP(n + offs, PAGE_SIZE);
446 if (n != outlen) {
447 __le32 v = cpu_to_le32(n);
448 memcpy(&req->tc.sdata[req->tc.size - 4], &v, 4);
449 outlen = n;
450 }
451 /* The size field of the message must include the length of the
452 * header and the length of the data. We didn't actually know
453 * the length of the data until this point so add it in now.
454 */
455 sz = cpu_to_le32(req->tc.size + outlen);
456 memcpy(&req->tc.sdata[0], &sz, sizeof(sz));
457 } else if (uidata) {
458 int n = p9_get_mapped_pages(chan, &in_pages, uidata,
459 inlen, &offs, &need_drop);
460 if (n < 0) {
461 err = n;
462 goto err_out;
463 }
464 in_nr_pages = DIV_ROUND_UP(n + offs, PAGE_SIZE);
465 if (n != inlen) {
466 __le32 v = cpu_to_le32(n);
467 memcpy(&req->tc.sdata[req->tc.size - 4], &v, 4);
468 inlen = n;
469 }
470 }
471 WRITE_ONCE(req->status, REQ_STATUS_SENT);
472 req_retry_pinned:
473 spin_lock_irqsave(&chan->lock, flags);
474
475 out_sgs = in_sgs = 0;
476
477 /* out data */
478 out = pack_sg_list(chan->sg, 0,
479 VIRTQUEUE_NUM, req->tc.sdata, req->tc.size);
480
481 if (out)
482 sgs[out_sgs++] = chan->sg;
483
484 if (out_pages) {
485 sgs[out_sgs++] = chan->sg + out;
486 out += pack_sg_list_p(chan->sg, out, VIRTQUEUE_NUM,
487 out_pages, out_nr_pages, offs, outlen);
488 }
489
490 /*
491 * Take care of in data
492 * For example TREAD have 11.
493 * 11 is the read/write header = PDU Header(7) + IO Size (4).
494 * Arrange in such a way that server places header in the
495 * allocated memory and payload onto the user buffer.
496 */
497 in = pack_sg_list(chan->sg, out,
498 VIRTQUEUE_NUM, req->rc.sdata, in_hdr_len);
499 if (in)
500 sgs[out_sgs + in_sgs++] = chan->sg + out;
501
502 if (in_pages) {
503 sgs[out_sgs + in_sgs++] = chan->sg + out + in;
504 pack_sg_list_p(chan->sg, out + in, VIRTQUEUE_NUM,
505 in_pages, in_nr_pages, offs, inlen);
506 }
507
508 BUG_ON(out_sgs + in_sgs > ARRAY_SIZE(sgs));
509 err = virtqueue_add_sgs(chan->vq, sgs, out_sgs, in_sgs, req,
510 GFP_ATOMIC);
511 if (err < 0) {
512 if (err == -ENOSPC) {
513 chan->ring_bufs_avail = 0;
514 spin_unlock_irqrestore(&chan->lock, flags);
515 err = wait_event_killable(*chan->vc_wq,
516 chan->ring_bufs_avail);
517 if (err == -ERESTARTSYS)
518 goto err_out;
519
520 p9_debug(P9_DEBUG_TRANS, "Retry virtio request\n");
521 goto req_retry_pinned;
522 } else {
523 spin_unlock_irqrestore(&chan->lock, flags);
524 p9_debug(P9_DEBUG_TRANS,
525 "virtio rpc add_sgs returned failure\n");
526 err = -EIO;
527 goto err_out;
528 }
529 }
530 virtqueue_kick(chan->vq);
531 spin_unlock_irqrestore(&chan->lock, flags);
532 kicked = 1;
533 p9_debug(P9_DEBUG_TRANS, "virtio request kicked\n");
534 err = wait_event_killable(req->wq,
535 READ_ONCE(req->status) >= REQ_STATUS_RCVD);
536 // RERROR needs reply (== error string) in static data
537 if (READ_ONCE(req->status) == REQ_STATUS_RCVD &&
538 unlikely(req->rc.sdata[4] == P9_RERROR))
539 handle_rerror(req, in_hdr_len, offs, in_pages);
540
541 /*
542 * Non kernel buffers are pinned, unpin them
543 */
544 err_out:
545 if (need_drop) {
546 if (in_pages) {
547 p9_release_pages(in_pages, in_nr_pages);
548 atomic_sub(in_nr_pages, &vp_pinned);
549 }
550 if (out_pages) {
551 p9_release_pages(out_pages, out_nr_pages);
552 atomic_sub(out_nr_pages, &vp_pinned);
553 }
554 /* wakeup anybody waiting for slots to pin pages */
555 wake_up(&vp_wq);
556 }
557 kvfree(in_pages);
558 kvfree(out_pages);
559 if (!kicked) {
560 /* reply won't come */
561 p9_req_put(client, req);
562 }
563 return err;
564 }
565
p9_mount_tag_show(struct device * dev,struct device_attribute * attr,char * buf)566 static ssize_t p9_mount_tag_show(struct device *dev,
567 struct device_attribute *attr, char *buf)
568 {
569 struct virtio_chan *chan;
570 struct virtio_device *vdev;
571 int tag_len;
572
573 vdev = dev_to_virtio(dev);
574 chan = vdev->priv;
575 tag_len = strlen(chan->tag);
576
577 memcpy(buf, chan->tag, tag_len + 1);
578
579 return tag_len + 1;
580 }
581
582 static DEVICE_ATTR(mount_tag, 0444, p9_mount_tag_show, NULL);
583
584 /**
585 * p9_virtio_probe - probe for existence of 9P virtio channels
586 * @vdev: virtio device to probe
587 *
588 * This probes for existing virtio channels.
589 *
590 */
591
p9_virtio_probe(struct virtio_device * vdev)592 static int p9_virtio_probe(struct virtio_device *vdev)
593 {
594 __u16 tag_len;
595 char *tag;
596 int err;
597 struct virtio_chan *chan;
598
599 if (!vdev->config->get) {
600 dev_err(&vdev->dev, "%s failure: config access disabled\n",
601 __func__);
602 return -EINVAL;
603 }
604
605 chan = kmalloc(sizeof(struct virtio_chan), GFP_KERNEL);
606 if (!chan) {
607 pr_err("Failed to allocate virtio 9P channel\n");
608 err = -ENOMEM;
609 goto fail;
610 }
611
612 chan->vdev = vdev;
613
614 /* We expect one virtqueue, for requests. */
615 chan->vq = virtio_find_single_vq(vdev, req_done, "requests");
616 if (IS_ERR(chan->vq)) {
617 err = PTR_ERR(chan->vq);
618 goto out_free_chan;
619 }
620 chan->vq->vdev->priv = chan;
621 spin_lock_init(&chan->lock);
622
623 sg_init_table(chan->sg, VIRTQUEUE_NUM);
624
625 chan->inuse = false;
626 if (virtio_has_feature(vdev, VIRTIO_9P_MOUNT_TAG)) {
627 virtio_cread(vdev, struct virtio_9p_config, tag_len, &tag_len);
628 } else {
629 err = -EINVAL;
630 goto out_free_vq;
631 }
632 tag = kzalloc(tag_len + 1, GFP_KERNEL);
633 if (!tag) {
634 err = -ENOMEM;
635 goto out_free_vq;
636 }
637
638 virtio_cread_bytes(vdev, offsetof(struct virtio_9p_config, tag),
639 tag, tag_len);
640 chan->tag = tag;
641 err = sysfs_create_file(&(vdev->dev.kobj), &dev_attr_mount_tag.attr);
642 if (err) {
643 goto out_free_tag;
644 }
645 chan->vc_wq = kmalloc(sizeof(wait_queue_head_t), GFP_KERNEL);
646 if (!chan->vc_wq) {
647 err = -ENOMEM;
648 goto out_remove_file;
649 }
650 init_waitqueue_head(chan->vc_wq);
651 chan->ring_bufs_avail = 1;
652 /* Ceiling limit to avoid denial of service attacks */
653 chan->p9_max_pages = nr_free_buffer_pages()/4;
654
655 virtio_device_ready(vdev);
656
657 mutex_lock(&virtio_9p_lock);
658 list_add_tail(&chan->chan_list, &virtio_chan_list);
659 mutex_unlock(&virtio_9p_lock);
660
661 /* Let udev rules use the new mount_tag attribute. */
662 kobject_uevent(&(vdev->dev.kobj), KOBJ_CHANGE);
663
664 return 0;
665
666 out_remove_file:
667 sysfs_remove_file(&vdev->dev.kobj, &dev_attr_mount_tag.attr);
668 out_free_tag:
669 kfree(tag);
670 out_free_vq:
671 vdev->config->del_vqs(vdev);
672 out_free_chan:
673 kfree(chan);
674 fail:
675 return err;
676 }
677
678
679 /**
680 * p9_virtio_create - allocate a new virtio channel
681 * @client: client instance invoking this transport
682 * @devname: string identifying the channel to connect to (unused)
683 * @args: args passed from sys_mount() for per-transport options (unused)
684 *
685 * This sets up a transport channel for 9p communication. Right now
686 * we only match the first available channel, but eventually we could look up
687 * alternate channels by matching devname versus a virtio_config entry.
688 * We use a simple reference count mechanism to ensure that only a single
689 * mount has a channel open at a time.
690 *
691 */
692
693 static int
p9_virtio_create(struct p9_client * client,const char * devname,char * args)694 p9_virtio_create(struct p9_client *client, const char *devname, char *args)
695 {
696 struct virtio_chan *chan;
697 int ret = -ENOENT;
698 int found = 0;
699
700 if (devname == NULL)
701 return -EINVAL;
702
703 mutex_lock(&virtio_9p_lock);
704 list_for_each_entry(chan, &virtio_chan_list, chan_list) {
705 if (!strcmp(devname, chan->tag)) {
706 if (!chan->inuse) {
707 chan->inuse = true;
708 found = 1;
709 break;
710 }
711 ret = -EBUSY;
712 }
713 }
714 mutex_unlock(&virtio_9p_lock);
715
716 if (!found) {
717 pr_err("no channels available for device %s\n", devname);
718 return ret;
719 }
720
721 client->trans = (void *)chan;
722 client->status = Connected;
723 chan->client = client;
724
725 return 0;
726 }
727
728 /**
729 * p9_virtio_remove - clean up resources associated with a virtio device
730 * @vdev: virtio device to remove
731 *
732 */
733
p9_virtio_remove(struct virtio_device * vdev)734 static void p9_virtio_remove(struct virtio_device *vdev)
735 {
736 struct virtio_chan *chan = vdev->priv;
737 unsigned long warning_time;
738
739 mutex_lock(&virtio_9p_lock);
740
741 /* Remove self from list so we don't get new users. */
742 list_del(&chan->chan_list);
743 warning_time = jiffies;
744
745 /* Wait for existing users to close. */
746 while (chan->inuse) {
747 mutex_unlock(&virtio_9p_lock);
748 msleep(250);
749 if (time_after(jiffies, warning_time + 10 * HZ)) {
750 dev_emerg(&vdev->dev,
751 "p9_virtio_remove: waiting for device in use.\n");
752 warning_time = jiffies;
753 }
754 mutex_lock(&virtio_9p_lock);
755 }
756
757 mutex_unlock(&virtio_9p_lock);
758
759 virtio_reset_device(vdev);
760 vdev->config->del_vqs(vdev);
761
762 sysfs_remove_file(&(vdev->dev.kobj), &dev_attr_mount_tag.attr);
763 kobject_uevent(&(vdev->dev.kobj), KOBJ_CHANGE);
764 kfree(chan->tag);
765 kfree(chan->vc_wq);
766 kfree(chan);
767
768 }
769
770 static struct virtio_device_id id_table[] = {
771 { VIRTIO_ID_9P, VIRTIO_DEV_ANY_ID },
772 { 0 },
773 };
774
775 static unsigned int features[] = {
776 VIRTIO_9P_MOUNT_TAG,
777 };
778
779 /* The standard "struct lguest_driver": */
780 static struct virtio_driver p9_virtio_drv = {
781 .feature_table = features,
782 .feature_table_size = ARRAY_SIZE(features),
783 .driver.name = KBUILD_MODNAME,
784 .driver.owner = THIS_MODULE,
785 .id_table = id_table,
786 .probe = p9_virtio_probe,
787 .remove = p9_virtio_remove,
788 };
789
790 static struct p9_trans_module p9_virtio_trans = {
791 .name = "virtio",
792 .create = p9_virtio_create,
793 .close = p9_virtio_close,
794 .request = p9_virtio_request,
795 .zc_request = p9_virtio_zc_request,
796 .cancel = p9_virtio_cancel,
797 .cancelled = p9_virtio_cancelled,
798 /*
799 * We leave one entry for input and one entry for response
800 * headers. We also skip one more entry to accommodate, address
801 * that are not at page boundary, that can result in an extra
802 * page in zero copy.
803 */
804 .maxsize = PAGE_SIZE * (VIRTQUEUE_NUM - 3),
805 .pooled_rbuffers = false,
806 .def = 1,
807 .owner = THIS_MODULE,
808 };
809
810 /* The standard init function */
p9_virtio_init(void)811 static int __init p9_virtio_init(void)
812 {
813 int rc;
814
815 INIT_LIST_HEAD(&virtio_chan_list);
816
817 v9fs_register_trans(&p9_virtio_trans);
818 rc = register_virtio_driver(&p9_virtio_drv);
819 if (rc)
820 v9fs_unregister_trans(&p9_virtio_trans);
821
822 return rc;
823 }
824
p9_virtio_cleanup(void)825 static void __exit p9_virtio_cleanup(void)
826 {
827 unregister_virtio_driver(&p9_virtio_drv);
828 v9fs_unregister_trans(&p9_virtio_trans);
829 }
830
831 module_init(p9_virtio_init);
832 module_exit(p9_virtio_cleanup);
833 MODULE_ALIAS_9P("virtio");
834
835 MODULE_DEVICE_TABLE(virtio, id_table);
836 MODULE_AUTHOR("Eric Van Hensbergen <ericvh@gmail.com>");
837 MODULE_DESCRIPTION("Virtio 9p Transport");
838 MODULE_LICENSE("GPL");
839