1 /* 2 * The Virtio 9p transport driver 3 * 4 * This is a block based transport driver based on the lguest block driver 5 * code. 6 * 7 * Copyright (C) 2007, 2008 Eric Van Hensbergen, IBM Corporation 8 * 9 * Based on virtio console driver 10 * Copyright (C) 2006, 2007 Rusty Russell, IBM Corporation 11 * 12 * This program is free software; you can redistribute it and/or modify 13 * it under the terms of the GNU General Public License version 2 14 * as published by the Free Software Foundation. 15 * 16 * This program is distributed in the hope that it will be useful, 17 * but WITHOUT ANY WARRANTY; without even the implied warranty of 18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 19 * GNU General Public License for more details. 20 * 21 * You should have received a copy of the GNU General Public License 22 * along with this program; if not, write to: 23 * Free Software Foundation 24 * 51 Franklin Street, Fifth Floor 25 * Boston, MA 02111-1301 USA 26 * 27 */ 28 29 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 30 31 #include <linux/in.h> 32 #include <linux/module.h> 33 #include <linux/net.h> 34 #include <linux/ipv6.h> 35 #include <linux/errno.h> 36 #include <linux/kernel.h> 37 #include <linux/un.h> 38 #include <linux/uaccess.h> 39 #include <linux/inet.h> 40 #include <linux/idr.h> 41 #include <linux/file.h> 42 #include <linux/highmem.h> 43 #include <linux/slab.h> 44 #include <net/9p/9p.h> 45 #include <linux/parser.h> 46 #include <net/9p/client.h> 47 #include <net/9p/transport.h> 48 #include <linux/scatterlist.h> 49 #include <linux/swap.h> 50 #include <linux/virtio.h> 51 #include <linux/virtio_9p.h> 52 #include "trans_common.h" 53 54 #define VIRTQUEUE_NUM 128 55 56 /* a single mutex to manage channel initialization and attachment */ 57 static DEFINE_MUTEX(virtio_9p_lock); 58 static DECLARE_WAIT_QUEUE_HEAD(vp_wq); 59 static atomic_t vp_pinned = ATOMIC_INIT(0); 60 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?) 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 76 struct 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 unsigned long 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 }; 101 102 static struct list_head virtio_chan_list; 103 104 /* How many bytes left in this page. */ 105 static unsigned int rest_of_page(void *data) 106 { 107 return PAGE_SIZE - offset_in_page(data); 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 */ 118 119 static 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 */ 141 142 static void req_done(struct virtqueue *vq) 143 { 144 struct virtio_chan *chan = vq->vdev->priv; 145 unsigned int len; 146 struct p9_req_t *req; 147 unsigned long flags; 148 149 p9_debug(P9_DEBUG_TRANS, ": request done\n"); 150 151 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; 157 } 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); 164 } 165 } 166 167 /** 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 174 * 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. 178 * 179 */ 180 181 static int pack_sg_list(struct scatterlist *sg, int start, 182 int limit, char *data, int count) 183 { 184 int s; 185 int index = start; 186 187 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; 197 } 198 if (index-start) 199 sg_mark_end(&sg[index - 1]); 200 return index-start; 201 } 202 203 /* We don't currently allow canceling of virtio requests */ 204 static int p9_virtio_cancel(struct p9_client *client, struct p9_req_t *req) 205 { 206 return 1; 207 } 208 209 /** 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 218 */ 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) 222 { 223 int i = 0, s; 224 int data_off = offs; 225 int index = start; 226 227 BUG_ON(nr_pages > (limit - start)); 228 /* 229 * if the first page doesn't start at 230 * page boundary find the offset 231 */ 232 while (nr_pages) { 233 s = PAGE_SIZE - data_off; 234 if (s > count) 235 s = count; 236 /* Make sure we don't terminate early. */ 237 sg_unmark_end(&sg[index]); 238 sg_set_page(&sg[index++], pdata[i++], s, data_off); 239 data_off = 0; 240 count -= s; 241 nr_pages--; 242 } 243 244 if (index-start) 245 sg_mark_end(&sg[index - 1]); 246 return index - start; 247 } 248 249 /** 250 * p9_virtio_request - issue a request 251 * @client: client instance issuing the request 252 * @req: request to be issued 253 * 254 */ 255 256 static int 257 p9_virtio_request(struct p9_client *client, struct p9_req_t *req) 258 { 259 int err; 260 int in, out, out_sgs, in_sgs; 261 unsigned long flags; 262 struct virtio_chan *chan = client->trans; 263 struct scatterlist *sgs[2]; 264 265 p9_debug(P9_DEBUG_TRANS, "9p debug: virtio request\n"); 266 267 req->status = REQ_STATUS_SENT; 268 req_retry: 269 spin_lock_irqsave(&chan->lock, flags); 270 271 out_sgs = in_sgs = 0; 272 /* Handle out VirtIO ring buffers */ 273 out = pack_sg_list(chan->sg, 0, 274 VIRTQUEUE_NUM, req->tc->sdata, req->tc->size); 275 if (out) 276 sgs[out_sgs++] = chan->sg; 277 278 in = pack_sg_list(chan->sg, out, 279 VIRTQUEUE_NUM, req->rc->sdata, req->rc->capacity); 280 if (in) 281 sgs[out_sgs + in_sgs++] = chan->sg + out; 282 283 err = virtqueue_add_sgs(chan->vq, sgs, out_sgs, in_sgs, req, 284 GFP_ATOMIC); 285 if (err < 0) { 286 if (err == -ENOSPC) { 287 chan->ring_bufs_avail = 0; 288 spin_unlock_irqrestore(&chan->lock, flags); 289 err = wait_event_killable(*chan->vc_wq, 290 chan->ring_bufs_avail); 291 if (err == -ERESTARTSYS) 292 return err; 293 294 p9_debug(P9_DEBUG_TRANS, "Retry virtio request\n"); 295 goto req_retry; 296 } else { 297 spin_unlock_irqrestore(&chan->lock, flags); 298 p9_debug(P9_DEBUG_TRANS, 299 "virtio rpc add_sgs returned failure\n"); 300 return -EIO; 301 } 302 } 303 virtqueue_kick(chan->vq); 304 spin_unlock_irqrestore(&chan->lock, flags); 305 306 p9_debug(P9_DEBUG_TRANS, "virtio request kicked\n"); 307 return 0; 308 } 309 310 static int p9_get_mapped_pages(struct virtio_chan *chan, 311 struct page ***pages, 312 struct iov_iter *data, 313 int count, 314 size_t *offs, 315 int *need_drop) 316 { 317 int nr_pages; 318 int err; 319 320 if (!iov_iter_count(data)) 321 return 0; 322 323 if (!(data->type & ITER_KVEC)) { 324 int n; 325 /* 326 * We allow only p9_max_pages pinned. We wait for the 327 * Other zc request to finish here 328 */ 329 if (atomic_read(&vp_pinned) >= chan->p9_max_pages) { 330 err = wait_event_killable(vp_wq, 331 (atomic_read(&vp_pinned) < chan->p9_max_pages)); 332 if (err == -ERESTARTSYS) 333 return err; 334 } 335 n = iov_iter_get_pages_alloc(data, pages, count, offs); 336 if (n < 0) 337 return n; 338 *need_drop = 1; 339 nr_pages = DIV_ROUND_UP(n + *offs, PAGE_SIZE); 340 atomic_add(nr_pages, &vp_pinned); 341 return n; 342 } else { 343 /* kernel buffer, no need to pin pages */ 344 int index; 345 size_t len; 346 void *p; 347 348 /* we'd already checked that it's non-empty */ 349 while (1) { 350 len = iov_iter_single_seg_count(data); 351 if (likely(len)) { 352 p = data->kvec->iov_base + data->iov_offset; 353 break; 354 } 355 iov_iter_advance(data, 0); 356 } 357 if (len > count) 358 len = count; 359 360 nr_pages = DIV_ROUND_UP((unsigned long)p + len, PAGE_SIZE) - 361 (unsigned long)p / PAGE_SIZE; 362 363 *pages = kmalloc_array(nr_pages, sizeof(struct page *), 364 GFP_NOFS); 365 if (!*pages) 366 return -ENOMEM; 367 368 *need_drop = 0; 369 p -= (*offs = offset_in_page(p)); 370 for (index = 0; index < nr_pages; index++) { 371 if (is_vmalloc_addr(p)) 372 (*pages)[index] = vmalloc_to_page(p); 373 else 374 (*pages)[index] = kmap_to_page(p); 375 p += PAGE_SIZE; 376 } 377 return len; 378 } 379 } 380 381 /** 382 * p9_virtio_zc_request - issue a zero copy request 383 * @client: client instance issuing the request 384 * @req: request to be issued 385 * @uidata: user bffer that should be ued for zero copy read 386 * @uodata: user buffer that shoud be user for zero copy write 387 * @inlen: read buffer size 388 * @outlen: write buffer size 389 * @in_hdr_len: reader header size, This is the size of response protocol data 390 * 391 */ 392 static int 393 p9_virtio_zc_request(struct p9_client *client, struct p9_req_t *req, 394 struct iov_iter *uidata, struct iov_iter *uodata, 395 int inlen, int outlen, int in_hdr_len) 396 { 397 int in, out, err, out_sgs, in_sgs; 398 unsigned long flags; 399 int in_nr_pages = 0, out_nr_pages = 0; 400 struct page **in_pages = NULL, **out_pages = NULL; 401 struct virtio_chan *chan = client->trans; 402 struct scatterlist *sgs[4]; 403 size_t offs; 404 int need_drop = 0; 405 406 p9_debug(P9_DEBUG_TRANS, "virtio request\n"); 407 408 if (uodata) { 409 int n = p9_get_mapped_pages(chan, &out_pages, uodata, 410 outlen, &offs, &need_drop); 411 if (n < 0) 412 return n; 413 out_nr_pages = DIV_ROUND_UP(n + offs, PAGE_SIZE); 414 if (n != outlen) { 415 __le32 v = cpu_to_le32(n); 416 memcpy(&req->tc->sdata[req->tc->size - 4], &v, 4); 417 outlen = n; 418 } 419 } else if (uidata) { 420 int n = p9_get_mapped_pages(chan, &in_pages, uidata, 421 inlen, &offs, &need_drop); 422 if (n < 0) 423 return n; 424 in_nr_pages = DIV_ROUND_UP(n + offs, PAGE_SIZE); 425 if (n != inlen) { 426 __le32 v = cpu_to_le32(n); 427 memcpy(&req->tc->sdata[req->tc->size - 4], &v, 4); 428 inlen = n; 429 } 430 } 431 req->status = REQ_STATUS_SENT; 432 req_retry_pinned: 433 spin_lock_irqsave(&chan->lock, flags); 434 435 out_sgs = in_sgs = 0; 436 437 /* out data */ 438 out = pack_sg_list(chan->sg, 0, 439 VIRTQUEUE_NUM, req->tc->sdata, req->tc->size); 440 441 if (out) 442 sgs[out_sgs++] = chan->sg; 443 444 if (out_pages) { 445 sgs[out_sgs++] = chan->sg + out; 446 out += pack_sg_list_p(chan->sg, out, VIRTQUEUE_NUM, 447 out_pages, out_nr_pages, offs, outlen); 448 } 449 450 /* 451 * Take care of in data 452 * For example TREAD have 11. 453 * 11 is the read/write header = PDU Header(7) + IO Size (4). 454 * Arrange in such a way that server places header in the 455 * alloced memory and payload onto the user buffer. 456 */ 457 in = pack_sg_list(chan->sg, out, 458 VIRTQUEUE_NUM, req->rc->sdata, in_hdr_len); 459 if (in) 460 sgs[out_sgs + in_sgs++] = chan->sg + out; 461 462 if (in_pages) { 463 sgs[out_sgs + in_sgs++] = chan->sg + out + in; 464 in += pack_sg_list_p(chan->sg, out + in, VIRTQUEUE_NUM, 465 in_pages, in_nr_pages, offs, inlen); 466 } 467 468 BUG_ON(out_sgs + in_sgs > ARRAY_SIZE(sgs)); 469 err = virtqueue_add_sgs(chan->vq, sgs, out_sgs, in_sgs, req, 470 GFP_ATOMIC); 471 if (err < 0) { 472 if (err == -ENOSPC) { 473 chan->ring_bufs_avail = 0; 474 spin_unlock_irqrestore(&chan->lock, flags); 475 err = wait_event_killable(*chan->vc_wq, 476 chan->ring_bufs_avail); 477 if (err == -ERESTARTSYS) 478 goto err_out; 479 480 p9_debug(P9_DEBUG_TRANS, "Retry virtio request\n"); 481 goto req_retry_pinned; 482 } else { 483 spin_unlock_irqrestore(&chan->lock, flags); 484 p9_debug(P9_DEBUG_TRANS, 485 "virtio rpc add_sgs returned failure\n"); 486 err = -EIO; 487 goto err_out; 488 } 489 } 490 virtqueue_kick(chan->vq); 491 spin_unlock_irqrestore(&chan->lock, flags); 492 p9_debug(P9_DEBUG_TRANS, "virtio request kicked\n"); 493 err = wait_event_killable(*req->wq, req->status >= REQ_STATUS_RCVD); 494 /* 495 * Non kernel buffers are pinned, unpin them 496 */ 497 err_out: 498 if (need_drop) { 499 if (in_pages) { 500 p9_release_pages(in_pages, in_nr_pages); 501 atomic_sub(in_nr_pages, &vp_pinned); 502 } 503 if (out_pages) { 504 p9_release_pages(out_pages, out_nr_pages); 505 atomic_sub(out_nr_pages, &vp_pinned); 506 } 507 /* wakeup anybody waiting for slots to pin pages */ 508 wake_up(&vp_wq); 509 } 510 kvfree(in_pages); 511 kvfree(out_pages); 512 return err; 513 } 514 515 static ssize_t p9_mount_tag_show(struct device *dev, 516 struct device_attribute *attr, char *buf) 517 { 518 struct virtio_chan *chan; 519 struct virtio_device *vdev; 520 521 vdev = dev_to_virtio(dev); 522 chan = vdev->priv; 523 524 memcpy(buf, chan->tag, chan->tag_len); 525 buf[chan->tag_len] = 0; 526 527 return chan->tag_len + 1; 528 } 529 530 static DEVICE_ATTR(mount_tag, 0444, p9_mount_tag_show, NULL); 531 532 /** 533 * p9_virtio_probe - probe for existence of 9P virtio channels 534 * @vdev: virtio device to probe 535 * 536 * This probes for existing virtio channels. 537 * 538 */ 539 540 static int p9_virtio_probe(struct virtio_device *vdev) 541 { 542 __u16 tag_len; 543 char *tag; 544 int err; 545 struct virtio_chan *chan; 546 547 if (!vdev->config->get) { 548 dev_err(&vdev->dev, "%s failure: config access disabled\n", 549 __func__); 550 return -EINVAL; 551 } 552 553 chan = kmalloc(sizeof(struct virtio_chan), GFP_KERNEL); 554 if (!chan) { 555 pr_err("Failed to allocate virtio 9P channel\n"); 556 err = -ENOMEM; 557 goto fail; 558 } 559 560 chan->vdev = vdev; 561 562 /* We expect one virtqueue, for requests. */ 563 chan->vq = virtio_find_single_vq(vdev, req_done, "requests"); 564 if (IS_ERR(chan->vq)) { 565 err = PTR_ERR(chan->vq); 566 goto out_free_vq; 567 } 568 chan->vq->vdev->priv = chan; 569 spin_lock_init(&chan->lock); 570 571 sg_init_table(chan->sg, VIRTQUEUE_NUM); 572 573 chan->inuse = false; 574 if (virtio_has_feature(vdev, VIRTIO_9P_MOUNT_TAG)) { 575 virtio_cread(vdev, struct virtio_9p_config, tag_len, &tag_len); 576 } else { 577 err = -EINVAL; 578 goto out_free_vq; 579 } 580 tag = kmalloc(tag_len, GFP_KERNEL); 581 if (!tag) { 582 err = -ENOMEM; 583 goto out_free_vq; 584 } 585 586 virtio_cread_bytes(vdev, offsetof(struct virtio_9p_config, tag), 587 tag, tag_len); 588 chan->tag = tag; 589 chan->tag_len = tag_len; 590 err = sysfs_create_file(&(vdev->dev.kobj), &dev_attr_mount_tag.attr); 591 if (err) { 592 goto out_free_tag; 593 } 594 chan->vc_wq = kmalloc(sizeof(wait_queue_head_t), GFP_KERNEL); 595 if (!chan->vc_wq) { 596 err = -ENOMEM; 597 goto out_free_tag; 598 } 599 init_waitqueue_head(chan->vc_wq); 600 chan->ring_bufs_avail = 1; 601 /* Ceiling limit to avoid denial of service attacks */ 602 chan->p9_max_pages = nr_free_buffer_pages()/4; 603 604 virtio_device_ready(vdev); 605 606 mutex_lock(&virtio_9p_lock); 607 list_add_tail(&chan->chan_list, &virtio_chan_list); 608 mutex_unlock(&virtio_9p_lock); 609 610 /* Let udev rules use the new mount_tag attribute. */ 611 kobject_uevent(&(vdev->dev.kobj), KOBJ_CHANGE); 612 613 return 0; 614 615 out_free_tag: 616 kfree(tag); 617 out_free_vq: 618 vdev->config->del_vqs(vdev); 619 kfree(chan); 620 fail: 621 return err; 622 } 623 624 625 /** 626 * p9_virtio_create - allocate a new virtio channel 627 * @client: client instance invoking this transport 628 * @devname: string identifying the channel to connect to (unused) 629 * @args: args passed from sys_mount() for per-transport options (unused) 630 * 631 * This sets up a transport channel for 9p communication. Right now 632 * we only match the first available channel, but eventually we couldlook up 633 * alternate channels by matching devname versus a virtio_config entry. 634 * We use a simple reference count mechanism to ensure that only a single 635 * mount has a channel open at a time. 636 * 637 */ 638 639 static int 640 p9_virtio_create(struct p9_client *client, const char *devname, char *args) 641 { 642 struct virtio_chan *chan; 643 int ret = -ENOENT; 644 int found = 0; 645 646 mutex_lock(&virtio_9p_lock); 647 list_for_each_entry(chan, &virtio_chan_list, chan_list) { 648 if (!strncmp(devname, chan->tag, chan->tag_len) && 649 strlen(devname) == chan->tag_len) { 650 if (!chan->inuse) { 651 chan->inuse = true; 652 found = 1; 653 break; 654 } 655 ret = -EBUSY; 656 } 657 } 658 mutex_unlock(&virtio_9p_lock); 659 660 if (!found) { 661 pr_err("no channels available for device %s\n", devname); 662 return ret; 663 } 664 665 client->trans = (void *)chan; 666 client->status = Connected; 667 chan->client = client; 668 669 return 0; 670 } 671 672 /** 673 * p9_virtio_remove - clean up resources associated with a virtio device 674 * @vdev: virtio device to remove 675 * 676 */ 677 678 static void p9_virtio_remove(struct virtio_device *vdev) 679 { 680 struct virtio_chan *chan = vdev->priv; 681 unsigned long warning_time; 682 683 mutex_lock(&virtio_9p_lock); 684 685 /* Remove self from list so we don't get new users. */ 686 list_del(&chan->chan_list); 687 warning_time = jiffies; 688 689 /* Wait for existing users to close. */ 690 while (chan->inuse) { 691 mutex_unlock(&virtio_9p_lock); 692 msleep(250); 693 if (time_after(jiffies, warning_time + 10 * HZ)) { 694 dev_emerg(&vdev->dev, 695 "p9_virtio_remove: waiting for device in use.\n"); 696 warning_time = jiffies; 697 } 698 mutex_lock(&virtio_9p_lock); 699 } 700 701 mutex_unlock(&virtio_9p_lock); 702 703 vdev->config->reset(vdev); 704 vdev->config->del_vqs(vdev); 705 706 sysfs_remove_file(&(vdev->dev.kobj), &dev_attr_mount_tag.attr); 707 kobject_uevent(&(vdev->dev.kobj), KOBJ_CHANGE); 708 kfree(chan->tag); 709 kfree(chan->vc_wq); 710 kfree(chan); 711 712 } 713 714 static struct virtio_device_id id_table[] = { 715 { VIRTIO_ID_9P, VIRTIO_DEV_ANY_ID }, 716 { 0 }, 717 }; 718 719 static unsigned int features[] = { 720 VIRTIO_9P_MOUNT_TAG, 721 }; 722 723 /* The standard "struct lguest_driver": */ 724 static struct virtio_driver p9_virtio_drv = { 725 .feature_table = features, 726 .feature_table_size = ARRAY_SIZE(features), 727 .driver.name = KBUILD_MODNAME, 728 .driver.owner = THIS_MODULE, 729 .id_table = id_table, 730 .probe = p9_virtio_probe, 731 .remove = p9_virtio_remove, 732 }; 733 734 static struct p9_trans_module p9_virtio_trans = { 735 .name = "virtio", 736 .create = p9_virtio_create, 737 .close = p9_virtio_close, 738 .request = p9_virtio_request, 739 .zc_request = p9_virtio_zc_request, 740 .cancel = p9_virtio_cancel, 741 /* 742 * We leave one entry for input and one entry for response 743 * headers. We also skip one more entry to accomodate, address 744 * that are not at page boundary, that can result in an extra 745 * page in zero copy. 746 */ 747 .maxsize = PAGE_SIZE * (VIRTQUEUE_NUM - 3), 748 .def = 1, 749 .owner = THIS_MODULE, 750 }; 751 752 /* The standard init function */ 753 static int __init p9_virtio_init(void) 754 { 755 INIT_LIST_HEAD(&virtio_chan_list); 756 757 v9fs_register_trans(&p9_virtio_trans); 758 return register_virtio_driver(&p9_virtio_drv); 759 } 760 761 static void __exit p9_virtio_cleanup(void) 762 { 763 unregister_virtio_driver(&p9_virtio_drv); 764 v9fs_unregister_trans(&p9_virtio_trans); 765 } 766 767 module_init(p9_virtio_init); 768 module_exit(p9_virtio_cleanup); 769 770 MODULE_DEVICE_TABLE(virtio, id_table); 771 MODULE_AUTHOR("Eric Van Hensbergen <ericvh@gmail.com>"); 772 MODULE_DESCRIPTION("Virtio 9p Transport"); 773 MODULE_LICENSE("GPL"); 774