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/idr.h>
26 #include <linux/file.h>
27 #include <linux/highmem.h>
28 #include <linux/slab.h>
29 #include <net/9p/9p.h>
30 #include <linux/parser.h>
31 #include <net/9p/client.h>
32 #include <net/9p/transport.h>
33 #include <linux/scatterlist.h>
34 #include <linux/swap.h>
35 #include <linux/virtio.h>
36 #include <linux/virtio_9p.h>
37 #include "trans_common.h"
38
39 #define VIRTQUEUE_NUM 128
40
41 /* a single mutex to manage channel initialization and attachment */
42 static DEFINE_MUTEX(virtio_9p_lock);
43 static DECLARE_WAIT_QUEUE_HEAD(vp_wq);
44 static atomic_t vp_pinned = ATOMIC_INIT(0);
45
46 /**
47 * struct virtio_chan - per-instance transport information
48 * @inuse: whether the channel is in use
49 * @lock: protects multiple elements within this structure
50 * @client: client instance
51 * @vdev: virtio dev associated with this channel
52 * @vq: virtio queue associated with this channel
53 * @ring_bufs_avail: flag to indicate there is some available in the ring buf
54 * @vc_wq: wait queue for waiting for thing to be added to ring buf
55 * @p9_max_pages: maximum number of pinned pages
56 * @sg: scatter gather list which is used to pack a request (protected?)
57 * @chan_list: linked list of channels
58 *
59 * We keep all per-channel information in a structure.
60 * This structure is allocated within the devices dev->mem space.
61 * A pointer to the structure will get put in the transport private.
62 *
63 */
64
65 struct virtio_chan {
66 bool inuse;
67
68 spinlock_t lock;
69
70 struct p9_client *client;
71 struct virtio_device *vdev;
72 struct virtqueue *vq;
73 int ring_bufs_avail;
74 wait_queue_head_t *vc_wq;
75 /* This is global limit. Since we don't have a global structure,
76 * will be placing it in each channel.
77 */
78 unsigned long p9_max_pages;
79 /* Scatterlist: can be too big for stack. */
80 struct scatterlist sg[VIRTQUEUE_NUM];
81 /**
82 * @tag: name to identify a mount null terminated
83 */
84 char *tag;
85
86 struct list_head chan_list;
87 };
88
89 static struct list_head virtio_chan_list;
90
91 /* How many bytes left in this page. */
rest_of_page(void * data)92 static unsigned int rest_of_page(void *data)
93 {
94 return PAGE_SIZE - offset_in_page(data);
95 }
96
97 /**
98 * p9_virtio_close - reclaim resources of a channel
99 * @client: client instance
100 *
101 * This reclaims a channel by freeing its resources and
102 * resetting its inuse flag.
103 *
104 */
105
p9_virtio_close(struct p9_client * client)106 static void p9_virtio_close(struct p9_client *client)
107 {
108 struct virtio_chan *chan = client->trans;
109
110 mutex_lock(&virtio_9p_lock);
111 if (chan)
112 chan->inuse = false;
113 mutex_unlock(&virtio_9p_lock);
114 }
115
116 /**
117 * req_done - callback which signals activity from the server
118 * @vq: virtio queue activity was received on
119 *
120 * This notifies us that the server has triggered some activity
121 * on the virtio channel - most likely a response to request we
122 * sent. Figure out which requests now have responses and wake up
123 * those threads.
124 *
125 * Bugs: could do with some additional sanity checking, but appears to work.
126 *
127 */
128
req_done(struct virtqueue * vq)129 static void req_done(struct virtqueue *vq)
130 {
131 struct virtio_chan *chan = vq->vdev->priv;
132 unsigned int len;
133 struct p9_req_t *req;
134 bool need_wakeup = false;
135 unsigned long flags;
136
137 p9_debug(P9_DEBUG_TRANS, ": request done\n");
138
139 spin_lock_irqsave(&chan->lock, flags);
140 while ((req = virtqueue_get_buf(chan->vq, &len)) != NULL) {
141 if (!chan->ring_bufs_avail) {
142 chan->ring_bufs_avail = 1;
143 need_wakeup = true;
144 }
145
146 if (len) {
147 req->rc.size = len;
148 p9_client_cb(chan->client, req, REQ_STATUS_RCVD);
149 }
150 }
151 spin_unlock_irqrestore(&chan->lock, flags);
152 /* Wakeup if anyone waiting for VirtIO ring space. */
153 if (need_wakeup)
154 wake_up(chan->vc_wq);
155 }
156
157 /**
158 * pack_sg_list - pack a scatter gather list from a linear buffer
159 * @sg: scatter/gather list to pack into
160 * @start: which segment of the sg_list to start at
161 * @limit: maximum segment to pack data to
162 * @data: data to pack into scatter/gather list
163 * @count: amount of data to pack into the scatter/gather list
164 *
165 * sg_lists have multiple segments of various sizes. This will pack
166 * arbitrary data into an existing scatter gather list, segmenting the
167 * data as necessary within constraints.
168 *
169 */
170
pack_sg_list(struct scatterlist * sg,int start,int limit,char * data,int count)171 static int pack_sg_list(struct scatterlist *sg, int start,
172 int limit, char *data, int count)
173 {
174 int s;
175 int index = start;
176
177 while (count) {
178 s = rest_of_page(data);
179 if (s > count)
180 s = count;
181 BUG_ON(index >= limit);
182 /* Make sure we don't terminate early. */
183 sg_unmark_end(&sg[index]);
184 sg_set_buf(&sg[index++], data, s);
185 count -= s;
186 data += s;
187 }
188 if (index-start)
189 sg_mark_end(&sg[index - 1]);
190 return index-start;
191 }
192
193 /* We don't currently allow canceling of virtio requests */
p9_virtio_cancel(struct p9_client * client,struct p9_req_t * req)194 static int p9_virtio_cancel(struct p9_client *client, struct p9_req_t *req)
195 {
196 return 1;
197 }
198
199 /* Reply won't come, so drop req ref */
p9_virtio_cancelled(struct p9_client * client,struct p9_req_t * req)200 static int p9_virtio_cancelled(struct p9_client *client, struct p9_req_t *req)
201 {
202 p9_req_put(client, req);
203 return 0;
204 }
205
206 /**
207 * pack_sg_list_p - Just like pack_sg_list. Instead of taking a buffer,
208 * this takes a list of pages.
209 * @sg: scatter/gather list to pack into
210 * @start: which segment of the sg_list to start at
211 * @limit: maximum number of pages in sg list.
212 * @pdata: a list of pages to add into sg.
213 * @nr_pages: number of pages to pack into the scatter/gather list
214 * @offs: amount of data in the beginning of first page _not_ to pack
215 * @count: amount of data to pack into the scatter/gather list
216 */
217 static int
pack_sg_list_p(struct scatterlist * sg,int start,int limit,struct page ** pdata,int nr_pages,size_t offs,int count)218 pack_sg_list_p(struct scatterlist *sg, int start, int limit,
219 struct page **pdata, int nr_pages, size_t offs, int count)
220 {
221 int i = 0, s;
222 int data_off = offs;
223 int index = start;
224
225 BUG_ON(nr_pages > (limit - start));
226 /*
227 * if the first page doesn't start at
228 * page boundary find the offset
229 */
230 while (nr_pages) {
231 s = PAGE_SIZE - data_off;
232 if (s > count)
233 s = count;
234 BUG_ON(index >= limit);
235 /* Make sure we don't terminate early. */
236 sg_unmark_end(&sg[index]);
237 sg_set_page(&sg[index++], pdata[i++], s, data_off);
238 data_off = 0;
239 count -= s;
240 nr_pages--;
241 }
242
243 if (index-start)
244 sg_mark_end(&sg[index - 1]);
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
255 static int
p9_virtio_request(struct p9_client * client,struct p9_req_t * req)256 p9_virtio_request(struct p9_client *client, struct p9_req_t *req)
257 {
258 int err;
259 int in, out, out_sgs, in_sgs;
260 unsigned long flags;
261 struct virtio_chan *chan = client->trans;
262 struct scatterlist *sgs[2];
263
264 p9_debug(P9_DEBUG_TRANS, "9p debug: virtio request\n");
265
266 req->status = REQ_STATUS_SENT;
267 req_retry:
268 spin_lock_irqsave(&chan->lock, flags);
269
270 out_sgs = in_sgs = 0;
271 /* Handle out VirtIO ring buffers */
272 out = pack_sg_list(chan->sg, 0,
273 VIRTQUEUE_NUM, req->tc.sdata, req->tc.size);
274 if (out)
275 sgs[out_sgs++] = chan->sg;
276
277 in = pack_sg_list(chan->sg, out,
278 VIRTQUEUE_NUM, req->rc.sdata, req->rc.capacity);
279 if (in)
280 sgs[out_sgs + in_sgs++] = chan->sg + out;
281
282 err = virtqueue_add_sgs(chan->vq, sgs, out_sgs, in_sgs, req,
283 GFP_ATOMIC);
284 if (err < 0) {
285 if (err == -ENOSPC) {
286 chan->ring_bufs_avail = 0;
287 spin_unlock_irqrestore(&chan->lock, flags);
288 err = wait_event_killable(*chan->vc_wq,
289 chan->ring_bufs_avail);
290 if (err == -ERESTARTSYS)
291 return err;
292
293 p9_debug(P9_DEBUG_TRANS, "Retry virtio request\n");
294 goto req_retry;
295 } else {
296 spin_unlock_irqrestore(&chan->lock, flags);
297 p9_debug(P9_DEBUG_TRANS,
298 "virtio rpc add_sgs returned failure\n");
299 return -EIO;
300 }
301 }
302 virtqueue_kick(chan->vq);
303 spin_unlock_irqrestore(&chan->lock, flags);
304
305 p9_debug(P9_DEBUG_TRANS, "virtio request kicked\n");
306 return 0;
307 }
308
p9_get_mapped_pages(struct virtio_chan * chan,struct page *** pages,struct iov_iter * data,int count,size_t * offs,int * need_drop)309 static int p9_get_mapped_pages(struct virtio_chan *chan,
310 struct page ***pages,
311 struct iov_iter *data,
312 int count,
313 size_t *offs,
314 int *need_drop)
315 {
316 int nr_pages;
317 int err;
318
319 if (!iov_iter_count(data))
320 return 0;
321
322 if (!iov_iter_is_kvec(data)) {
323 int n;
324 /*
325 * We allow only p9_max_pages pinned. We wait for the
326 * Other zc request to finish here
327 */
328 if (atomic_read(&vp_pinned) >= chan->p9_max_pages) {
329 err = wait_event_killable(vp_wq,
330 (atomic_read(&vp_pinned) < chan->p9_max_pages));
331 if (err == -ERESTARTSYS)
332 return err;
333 }
334 n = iov_iter_get_pages_alloc2(data, pages, count, offs);
335 if (n < 0)
336 return n;
337 *need_drop = 1;
338 nr_pages = DIV_ROUND_UP(n + *offs, PAGE_SIZE);
339 atomic_add(nr_pages, &vp_pinned);
340 return n;
341 } else {
342 /* kernel buffer, no need to pin pages */
343 int index;
344 size_t len;
345 void *p;
346
347 /* we'd already checked that it's non-empty */
348 while (1) {
349 len = iov_iter_single_seg_count(data);
350 if (likely(len)) {
351 p = data->kvec->iov_base + data->iov_offset;
352 break;
353 }
354 iov_iter_advance(data, 0);
355 }
356 if (len > count)
357 len = count;
358
359 nr_pages = DIV_ROUND_UP((unsigned long)p + len, PAGE_SIZE) -
360 (unsigned long)p / PAGE_SIZE;
361
362 *pages = kmalloc_array(nr_pages, sizeof(struct page *),
363 GFP_NOFS);
364 if (!*pages)
365 return -ENOMEM;
366
367 *need_drop = 0;
368 p -= (*offs = offset_in_page(p));
369 for (index = 0; index < nr_pages; index++) {
370 if (is_vmalloc_addr(p))
371 (*pages)[index] = vmalloc_to_page(p);
372 else
373 (*pages)[index] = kmap_to_page(p);
374 p += PAGE_SIZE;
375 }
376 iov_iter_advance(data, len);
377 return len;
378 }
379 }
380
handle_rerror(struct p9_req_t * req,int in_hdr_len,size_t offs,struct page ** pages)381 static void handle_rerror(struct p9_req_t *req, int in_hdr_len,
382 size_t offs, struct page **pages)
383 {
384 unsigned size, n;
385 void *to = req->rc.sdata + in_hdr_len;
386
387 // Fits entirely into the static data? Nothing to do.
388 if (req->rc.size < in_hdr_len)
389 return;
390
391 // Really long error message? Tough, truncate the reply. Might get
392 // rejected (we can't be arsed to adjust the size encoded in header,
393 // or string size for that matter), but it wouldn't be anything valid
394 // anyway.
395 if (unlikely(req->rc.size > P9_ZC_HDR_SZ))
396 req->rc.size = P9_ZC_HDR_SZ;
397
398 // data won't span more than two pages
399 size = req->rc.size - in_hdr_len;
400 n = PAGE_SIZE - offs;
401 if (size > n) {
402 memcpy_from_page(to, *pages++, offs, n);
403 offs = 0;
404 to += n;
405 size -= n;
406 }
407 memcpy_from_page(to, *pages, offs, size);
408 }
409
410 /**
411 * p9_virtio_zc_request - issue a zero copy request
412 * @client: client instance issuing the request
413 * @req: request to be issued
414 * @uidata: user buffer that should be used for zero copy read
415 * @uodata: user buffer that should be used for zero copy write
416 * @inlen: read buffer size
417 * @outlen: write buffer size
418 * @in_hdr_len: reader header size, This is the size of response protocol data
419 *
420 */
421 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)422 p9_virtio_zc_request(struct p9_client *client, struct p9_req_t *req,
423 struct iov_iter *uidata, struct iov_iter *uodata,
424 int inlen, int outlen, int in_hdr_len)
425 {
426 int in, out, err, out_sgs, in_sgs;
427 unsigned long flags;
428 int in_nr_pages = 0, out_nr_pages = 0;
429 struct page **in_pages = NULL, **out_pages = NULL;
430 struct virtio_chan *chan = client->trans;
431 struct scatterlist *sgs[4];
432 size_t offs;
433 int need_drop = 0;
434 int kicked = 0;
435
436 p9_debug(P9_DEBUG_TRANS, "virtio request\n");
437
438 if (uodata) {
439 __le32 sz;
440 int n = p9_get_mapped_pages(chan, &out_pages, uodata,
441 outlen, &offs, &need_drop);
442 if (n < 0) {
443 err = n;
444 goto err_out;
445 }
446 out_nr_pages = DIV_ROUND_UP(n + offs, PAGE_SIZE);
447 if (n != outlen) {
448 __le32 v = cpu_to_le32(n);
449 memcpy(&req->tc.sdata[req->tc.size - 4], &v, 4);
450 outlen = n;
451 }
452 /* The size field of the message must include the length of the
453 * header and the length of the data. We didn't actually know
454 * the length of the data until this point so add it in now.
455 */
456 sz = cpu_to_le32(req->tc.size + outlen);
457 memcpy(&req->tc.sdata[0], &sz, sizeof(sz));
458 } else if (uidata) {
459 int n = p9_get_mapped_pages(chan, &in_pages, uidata,
460 inlen, &offs, &need_drop);
461 if (n < 0) {
462 err = n;
463 goto err_out;
464 }
465 in_nr_pages = DIV_ROUND_UP(n + offs, PAGE_SIZE);
466 if (n != inlen) {
467 __le32 v = cpu_to_le32(n);
468 memcpy(&req->tc.sdata[req->tc.size - 4], &v, 4);
469 inlen = n;
470 }
471 }
472 req->status = REQ_STATUS_SENT;
473 req_retry_pinned:
474 spin_lock_irqsave(&chan->lock, flags);
475
476 out_sgs = in_sgs = 0;
477
478 /* out data */
479 out = pack_sg_list(chan->sg, 0,
480 VIRTQUEUE_NUM, req->tc.sdata, req->tc.size);
481
482 if (out)
483 sgs[out_sgs++] = chan->sg;
484
485 if (out_pages) {
486 sgs[out_sgs++] = chan->sg + out;
487 out += pack_sg_list_p(chan->sg, out, VIRTQUEUE_NUM,
488 out_pages, out_nr_pages, offs, outlen);
489 }
490
491 /*
492 * Take care of in data
493 * For example TREAD have 11.
494 * 11 is the read/write header = PDU Header(7) + IO Size (4).
495 * Arrange in such a way that server places header in the
496 * allocated memory and payload onto the user buffer.
497 */
498 in = pack_sg_list(chan->sg, out,
499 VIRTQUEUE_NUM, req->rc.sdata, in_hdr_len);
500 if (in)
501 sgs[out_sgs + in_sgs++] = chan->sg + out;
502
503 if (in_pages) {
504 sgs[out_sgs + in_sgs++] = chan->sg + out + in;
505 in += pack_sg_list_p(chan->sg, out + in, VIRTQUEUE_NUM,
506 in_pages, in_nr_pages, offs, inlen);
507 }
508
509 BUG_ON(out_sgs + in_sgs > ARRAY_SIZE(sgs));
510 err = virtqueue_add_sgs(chan->vq, sgs, out_sgs, in_sgs, req,
511 GFP_ATOMIC);
512 if (err < 0) {
513 if (err == -ENOSPC) {
514 chan->ring_bufs_avail = 0;
515 spin_unlock_irqrestore(&chan->lock, flags);
516 err = wait_event_killable(*chan->vc_wq,
517 chan->ring_bufs_avail);
518 if (err == -ERESTARTSYS)
519 goto err_out;
520
521 p9_debug(P9_DEBUG_TRANS, "Retry virtio request\n");
522 goto req_retry_pinned;
523 } else {
524 spin_unlock_irqrestore(&chan->lock, flags);
525 p9_debug(P9_DEBUG_TRANS,
526 "virtio rpc add_sgs returned failure\n");
527 err = -EIO;
528 goto err_out;
529 }
530 }
531 virtqueue_kick(chan->vq);
532 spin_unlock_irqrestore(&chan->lock, flags);
533 kicked = 1;
534 p9_debug(P9_DEBUG_TRANS, "virtio request kicked\n");
535 err = wait_event_killable(req->wq, req->status >= REQ_STATUS_RCVD);
536 // RERROR needs reply (== error string) in static data
537 if (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
