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 */ 57static DEFINE_MUTEX(virtio_9p_lock); 58static DECLARE_WAIT_QUEUE_HEAD(vp_wq); 59static atomic_t vp_pinned = ATOMIC_INIT(0); 60 61/** 62 * struct virtio_chan - per-instance transport information 63 * @initialized: whether the channel is initialized 64 * @inuse: whether the channel is in use 65 * @lock: protects multiple elements within this structure 66 * @client: client instance 67 * @vdev: virtio dev associated with this channel 68 * @vq: virtio queue associated with this channel 69 * @sg: scatter gather list which is used to pack a request (protected?) 70 * 71 * We keep all per-channel information in a structure. 72 * This structure is allocated within the devices dev->mem space. 73 * A pointer to the structure will get put in the transport private. 74 * 75 */ 76 77struct virtio_chan { 78 bool inuse; 79 80 spinlock_t lock; 81 82 struct p9_client *client; 83 struct virtio_device *vdev; 84 struct virtqueue *vq; 85 int ring_bufs_avail; 86 wait_queue_head_t *vc_wq; 87 /* This is global limit. Since we don't have a global structure, 88 * will be placing it in each channel. 89 */ 90 unsigned long p9_max_pages; 91 /* Scatterlist: can be too big for stack. */ 92 struct scatterlist sg[VIRTQUEUE_NUM]; 93 94 int tag_len; 95 /* 96 * tag name to identify a mount Non-null terminated 97 */ 98 char *tag; 99 100 struct list_head chan_list; 101}; 102 103static struct list_head virtio_chan_list; 104 105/* How many bytes left in this page. */ 106static unsigned int rest_of_page(void *data) 107{ 108 return PAGE_SIZE - ((unsigned long)data % PAGE_SIZE); 109} 110 111/** 112 * p9_virtio_close - reclaim resources of a channel 113 * @client: client instance 114 * 115 * This reclaims a channel by freeing its resources and 116 * reseting its inuse flag. 117 * 118 */ 119 120static void p9_virtio_close(struct p9_client *client) 121{ 122 struct virtio_chan *chan = client->trans; 123 124 mutex_lock(&virtio_9p_lock); 125 if (chan) 126 chan->inuse = false; 127 mutex_unlock(&virtio_9p_lock); 128} 129 130/** 131 * req_done - callback which signals activity from the server 132 * @vq: virtio queue activity was received on 133 * 134 * This notifies us that the server has triggered some activity 135 * on the virtio channel - most likely a response to request we 136 * sent. Figure out which requests now have responses and wake up 137 * those threads. 138 * 139 * Bugs: could do with some additional sanity checking, but appears to work. 140 * 141 */ 142 143static void req_done(struct virtqueue *vq) 144{ 145 struct virtio_chan *chan = vq->vdev->priv; 146 struct p9_fcall *rc; 147 unsigned int len; 148 struct p9_req_t *req; 149 unsigned long flags; 150 151 p9_debug(P9_DEBUG_TRANS, ": request done\n"); 152 153 while (1) { 154 spin_lock_irqsave(&chan->lock, flags); 155 rc = virtqueue_get_buf(chan->vq, &len); 156 if (rc == NULL) { 157 spin_unlock_irqrestore(&chan->lock, flags); 158 break; 159 } 160 chan->ring_bufs_avail = 1; 161 spin_unlock_irqrestore(&chan->lock, flags); 162 /* Wakeup if anyone waiting for VirtIO ring space. */ 163 wake_up(chan->vc_wq); 164 p9_debug(P9_DEBUG_TRANS, ": rc %p\n", rc); 165 p9_debug(P9_DEBUG_TRANS, ": lookup tag %d\n", rc->tag); 166 req = p9_tag_lookup(chan->client, rc->tag); 167 p9_client_cb(chan->client, req, REQ_STATUS_RCVD); 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 /* Make sure we don't terminate early. */ 197 sg_unmark_end(&sg[index]); 198 sg_set_buf(&sg[index++], data, s); 199 count -= s; 200 data += s; 201 } 202 if (index-start) 203 sg_mark_end(&sg[index - 1]); 204 return index-start; 205} 206 207/* We don't currently allow canceling of virtio requests */ 208static int p9_virtio_cancel(struct p9_client *client, struct p9_req_t *req) 209{ 210 return 1; 211} 212 213/** 214 * pack_sg_list_p - Just like pack_sg_list. Instead of taking a buffer, 215 * this takes a list of pages. 216 * @sg: scatter/gather list to pack into 217 * @start: which segment of the sg_list to start at 218 * @pdata: a list of pages to add into sg. 219 * @nr_pages: number of pages to pack into the scatter/gather list 220 * @offs: amount of data in the beginning of first page _not_ to pack 221 * @count: amount of data to pack into the scatter/gather list 222 */ 223static int 224pack_sg_list_p(struct scatterlist *sg, int start, int limit, 225 struct page **pdata, int nr_pages, size_t offs, int count) 226{ 227 int i = 0, s; 228 int data_off = offs; 229 int index = start; 230 231 BUG_ON(nr_pages > (limit - start)); 232 /* 233 * if the first page doesn't start at 234 * page boundary find the offset 235 */ 236 while (nr_pages) { 237 s = PAGE_SIZE - data_off; 238 if (s > count) 239 s = count; 240 /* Make sure we don't terminate early. */ 241 sg_unmark_end(&sg[index]); 242 sg_set_page(&sg[index++], pdata[i++], s, data_off); 243 data_off = 0; 244 count -= s; 245 nr_pages--; 246 } 247 248 if (index-start) 249 sg_mark_end(&sg[index - 1]); 250 return index - start; 251} 252 253/** 254 * p9_virtio_request - issue a request 255 * @client: client instance issuing the request 256 * @req: request to be issued 257 * 258 */ 259 260static int 261p9_virtio_request(struct p9_client *client, struct p9_req_t *req) 262{ 263 int err; 264 int in, out, out_sgs, in_sgs; 265 unsigned long flags; 266 struct virtio_chan *chan = client->trans; 267 struct scatterlist *sgs[2]; 268 269 p9_debug(P9_DEBUG_TRANS, "9p debug: virtio request\n"); 270 271 req->status = REQ_STATUS_SENT; 272req_retry: 273 spin_lock_irqsave(&chan->lock, flags); 274 275 out_sgs = in_sgs = 0; 276 /* Handle out VirtIO ring buffers */ 277 out = pack_sg_list(chan->sg, 0, 278 VIRTQUEUE_NUM, req->tc->sdata, req->tc->size); 279 if (out) 280 sgs[out_sgs++] = chan->sg; 281 282 in = pack_sg_list(chan->sg, out, 283 VIRTQUEUE_NUM, req->rc->sdata, req->rc->capacity); 284 if (in) 285 sgs[out_sgs + in_sgs++] = chan->sg + out; 286 287 err = virtqueue_add_sgs(chan->vq, sgs, out_sgs, in_sgs, req->tc, 288 GFP_ATOMIC); 289 if (err < 0) { 290 if (err == -ENOSPC) { 291 chan->ring_bufs_avail = 0; 292 spin_unlock_irqrestore(&chan->lock, flags); 293 err = wait_event_interruptible(*chan->vc_wq, 294 chan->ring_bufs_avail); 295 if (err == -ERESTARTSYS) 296 return err; 297 298 p9_debug(P9_DEBUG_TRANS, "Retry virtio request\n"); 299 goto req_retry; 300 } else { 301 spin_unlock_irqrestore(&chan->lock, flags); 302 p9_debug(P9_DEBUG_TRANS, 303 "virtio rpc add_sgs returned failure\n"); 304 return -EIO; 305 } 306 } 307 virtqueue_kick(chan->vq); 308 spin_unlock_irqrestore(&chan->lock, flags); 309 310 p9_debug(P9_DEBUG_TRANS, "virtio request kicked\n"); 311 return 0; 312} 313 314static int p9_get_mapped_pages(struct virtio_chan *chan, 315 struct page ***pages, 316 struct iov_iter *data, 317 int count, 318 size_t *offs, 319 int *need_drop) 320{ 321 int nr_pages; 322 int err; 323 324 if (!iov_iter_count(data)) 325 return 0; 326 327 if (!(data->type & ITER_KVEC)) { 328 int n; 329 /* 330 * We allow only p9_max_pages pinned. We wait for the 331 * Other zc request to finish here 332 */ 333 if (atomic_read(&vp_pinned) >= chan->p9_max_pages) { 334 err = wait_event_interruptible(vp_wq, 335 (atomic_read(&vp_pinned) < chan->p9_max_pages)); 336 if (err == -ERESTARTSYS) 337 return err; 338 } 339 n = iov_iter_get_pages_alloc(data, pages, count, offs); 340 if (n < 0) 341 return n; 342 *need_drop = 1; 343 nr_pages = DIV_ROUND_UP(n + *offs, PAGE_SIZE); 344 atomic_add(nr_pages, &vp_pinned); 345 return n; 346 } else { 347 /* kernel buffer, no need to pin pages */ 348 int index; 349 size_t len; 350 void *p; 351 352 /* we'd already checked that it's non-empty */ 353 while (1) { 354 len = iov_iter_single_seg_count(data); 355 if (likely(len)) { 356 p = data->kvec->iov_base + data->iov_offset; 357 break; 358 } 359 iov_iter_advance(data, 0); 360 } 361 if (len > count) 362 len = count; 363 364 nr_pages = DIV_ROUND_UP((unsigned long)p + len, PAGE_SIZE) - 365 (unsigned long)p / PAGE_SIZE; 366 367 *pages = kmalloc(sizeof(struct page *) * nr_pages, GFP_NOFS); 368 if (!*pages) 369 return -ENOMEM; 370 371 *need_drop = 0; 372 p -= (*offs = (unsigned long)p % PAGE_SIZE); 373 for (index = 0; index < nr_pages; index++) { 374 if (is_vmalloc_addr(p)) 375 (*pages)[index] = vmalloc_to_page(p); 376 else 377 (*pages)[index] = kmap_to_page(p); 378 p += PAGE_SIZE; 379 } 380 return len; 381 } 382} 383 384/** 385 * p9_virtio_zc_request - issue a zero copy request 386 * @client: client instance issuing the request 387 * @req: request to be issued 388 * @uidata: user bffer that should be ued for zero copy read 389 * @uodata: user buffer that shoud be user for zero copy write 390 * @inlen: read buffer size 391 * @olen: write buffer size 392 * @hdrlen: reader header size, This is the size of response protocol data 393 * 394 */ 395static int 396p9_virtio_zc_request(struct p9_client *client, struct p9_req_t *req, 397 struct iov_iter *uidata, struct iov_iter *uodata, 398 int inlen, int outlen, int in_hdr_len) 399{ 400 int in, out, err, out_sgs, in_sgs; 401 unsigned long flags; 402 int in_nr_pages = 0, out_nr_pages = 0; 403 struct page **in_pages = NULL, **out_pages = NULL; 404 struct virtio_chan *chan = client->trans; 405 struct scatterlist *sgs[4]; 406 size_t offs; 407 int need_drop = 0; 408 409 p9_debug(P9_DEBUG_TRANS, "virtio request\n"); 410 411 if (uodata) { 412 int n = p9_get_mapped_pages(chan, &out_pages, uodata, 413 outlen, &offs, &need_drop); 414 if (n < 0) 415 return n; 416 out_nr_pages = DIV_ROUND_UP(n + offs, PAGE_SIZE); 417 if (n != outlen) { 418 __le32 v = cpu_to_le32(n); 419 memcpy(&req->tc->sdata[req->tc->size - 4], &v, 4); 420 outlen = n; 421 } 422 } else if (uidata) { 423 int n = p9_get_mapped_pages(chan, &in_pages, uidata, 424 inlen, &offs, &need_drop); 425 if (n < 0) 426 return n; 427 in_nr_pages = DIV_ROUND_UP(n + offs, PAGE_SIZE); 428 if (n != inlen) { 429 __le32 v = cpu_to_le32(n); 430 memcpy(&req->tc->sdata[req->tc->size - 4], &v, 4); 431 inlen = n; 432 } 433 } 434 req->status = REQ_STATUS_SENT; 435req_retry_pinned: 436 spin_lock_irqsave(&chan->lock, flags); 437 438 out_sgs = in_sgs = 0; 439 440 /* out data */ 441 out = pack_sg_list(chan->sg, 0, 442 VIRTQUEUE_NUM, req->tc->sdata, req->tc->size); 443 444 if (out) 445 sgs[out_sgs++] = chan->sg; 446 447 if (out_pages) { 448 sgs[out_sgs++] = chan->sg + out; 449 out += pack_sg_list_p(chan->sg, out, VIRTQUEUE_NUM, 450 out_pages, out_nr_pages, offs, outlen); 451 } 452 453 /* 454 * Take care of in data 455 * For example TREAD have 11. 456 * 11 is the read/write header = PDU Header(7) + IO Size (4). 457 * Arrange in such a way that server places header in the 458 * alloced memory and payload onto the user buffer. 459 */ 460 in = pack_sg_list(chan->sg, out, 461 VIRTQUEUE_NUM, req->rc->sdata, in_hdr_len); 462 if (in) 463 sgs[out_sgs + in_sgs++] = chan->sg + out; 464 465 if (in_pages) { 466 sgs[out_sgs + in_sgs++] = chan->sg + out + in; 467 in += pack_sg_list_p(chan->sg, out + in, VIRTQUEUE_NUM, 468 in_pages, in_nr_pages, offs, inlen); 469 } 470 471 BUG_ON(out_sgs + in_sgs > ARRAY_SIZE(sgs)); 472 err = virtqueue_add_sgs(chan->vq, sgs, out_sgs, in_sgs, req->tc, 473 GFP_ATOMIC); 474 if (err < 0) { 475 if (err == -ENOSPC) { 476 chan->ring_bufs_avail = 0; 477 spin_unlock_irqrestore(&chan->lock, flags); 478 err = wait_event_interruptible(*chan->vc_wq, 479 chan->ring_bufs_avail); 480 if (err == -ERESTARTSYS) 481 goto err_out; 482 483 p9_debug(P9_DEBUG_TRANS, "Retry virtio request\n"); 484 goto req_retry_pinned; 485 } else { 486 spin_unlock_irqrestore(&chan->lock, flags); 487 p9_debug(P9_DEBUG_TRANS, 488 "virtio rpc add_sgs returned failure\n"); 489 err = -EIO; 490 goto err_out; 491 } 492 } 493 virtqueue_kick(chan->vq); 494 spin_unlock_irqrestore(&chan->lock, flags); 495 p9_debug(P9_DEBUG_TRANS, "virtio request kicked\n"); 496 err = wait_event_interruptible(*req->wq, 497 req->status >= REQ_STATUS_RCVD); 498 /* 499 * Non kernel buffers are pinned, unpin them 500 */ 501err_out: 502 if (need_drop) { 503 if (in_pages) { 504 p9_release_pages(in_pages, in_nr_pages); 505 atomic_sub(in_nr_pages, &vp_pinned); 506 } 507 if (out_pages) { 508 p9_release_pages(out_pages, out_nr_pages); 509 atomic_sub(out_nr_pages, &vp_pinned); 510 } 511 /* wakeup anybody waiting for slots to pin pages */ 512 wake_up(&vp_wq); 513 } 514 kfree(in_pages); 515 kfree(out_pages); 516 return err; 517} 518 519static ssize_t p9_mount_tag_show(struct device *dev, 520 struct device_attribute *attr, char *buf) 521{ 522 struct virtio_chan *chan; 523 struct virtio_device *vdev; 524 525 vdev = dev_to_virtio(dev); 526 chan = vdev->priv; 527 528 memcpy(buf, chan->tag, chan->tag_len); 529 buf[chan->tag_len] = 0; 530 531 return chan->tag_len + 1; 532} 533 534static DEVICE_ATTR(mount_tag, 0444, p9_mount_tag_show, NULL); 535 536/** 537 * p9_virtio_probe - probe for existence of 9P virtio channels 538 * @vdev: virtio device to probe 539 * 540 * This probes for existing virtio channels. 541 * 542 */ 543 544static int p9_virtio_probe(struct virtio_device *vdev) 545{ 546 __u16 tag_len; 547 char *tag; 548 int err; 549 struct virtio_chan *chan; 550 551 if (!vdev->config->get) { 552 dev_err(&vdev->dev, "%s failure: config access disabled\n", 553 __func__); 554 return -EINVAL; 555 } 556 557 chan = kmalloc(sizeof(struct virtio_chan), GFP_KERNEL); 558 if (!chan) { 559 pr_err("Failed to allocate virtio 9P channel\n"); 560 err = -ENOMEM; 561 goto fail; 562 } 563 564 chan->vdev = vdev; 565 566 /* We expect one virtqueue, for requests. */ 567 chan->vq = virtio_find_single_vq(vdev, req_done, "requests"); 568 if (IS_ERR(chan->vq)) { 569 err = PTR_ERR(chan->vq); 570 goto out_free_vq; 571 } 572 chan->vq->vdev->priv = chan; 573 spin_lock_init(&chan->lock); 574 575 sg_init_table(chan->sg, VIRTQUEUE_NUM); 576 577 chan->inuse = false; 578 if (virtio_has_feature(vdev, VIRTIO_9P_MOUNT_TAG)) { 579 virtio_cread(vdev, struct virtio_9p_config, tag_len, &tag_len); 580 } else { 581 err = -EINVAL; 582 goto out_free_vq; 583 } 584 tag = kmalloc(tag_len, GFP_KERNEL); 585 if (!tag) { 586 err = -ENOMEM; 587 goto out_free_vq; 588 } 589 590 virtio_cread_bytes(vdev, offsetof(struct virtio_9p_config, tag), 591 tag, tag_len); 592 chan->tag = tag; 593 chan->tag_len = tag_len; 594 err = sysfs_create_file(&(vdev->dev.kobj), &dev_attr_mount_tag.attr); 595 if (err) { 596 goto out_free_tag; 597 } 598 chan->vc_wq = kmalloc(sizeof(wait_queue_head_t), GFP_KERNEL); 599 if (!chan->vc_wq) { 600 err = -ENOMEM; 601 goto out_free_tag; 602 } 603 init_waitqueue_head(chan->vc_wq); 604 chan->ring_bufs_avail = 1; 605 /* Ceiling limit to avoid denial of service attacks */ 606 chan->p9_max_pages = nr_free_buffer_pages()/4; 607 608 virtio_device_ready(vdev); 609 610 mutex_lock(&virtio_9p_lock); 611 list_add_tail(&chan->chan_list, &virtio_chan_list); 612 mutex_unlock(&virtio_9p_lock); 613 614 /* Let udev rules use the new mount_tag attribute. */ 615 kobject_uevent(&(vdev->dev.kobj), KOBJ_CHANGE); 616 617 return 0; 618 619out_free_tag: 620 kfree(tag); 621out_free_vq: 622 vdev->config->del_vqs(vdev); 623 kfree(chan); 624fail: 625 return err; 626} 627 628 629/** 630 * p9_virtio_create - allocate a new virtio channel 631 * @client: client instance invoking this transport 632 * @devname: string identifying the channel to connect to (unused) 633 * @args: args passed from sys_mount() for per-transport options (unused) 634 * 635 * This sets up a transport channel for 9p communication. Right now 636 * we only match the first available channel, but eventually we couldlook up 637 * alternate channels by matching devname versus a virtio_config entry. 638 * We use a simple reference count mechanism to ensure that only a single 639 * mount has a channel open at a time. 640 * 641 */ 642 643static int 644p9_virtio_create(struct p9_client *client, const char *devname, char *args) 645{ 646 struct virtio_chan *chan; 647 int ret = -ENOENT; 648 int found = 0; 649 650 mutex_lock(&virtio_9p_lock); 651 list_for_each_entry(chan, &virtio_chan_list, chan_list) { 652 if (!strncmp(devname, chan->tag, chan->tag_len) && 653 strlen(devname) == chan->tag_len) { 654 if (!chan->inuse) { 655 chan->inuse = true; 656 found = 1; 657 break; 658 } 659 ret = -EBUSY; 660 } 661 } 662 mutex_unlock(&virtio_9p_lock); 663 664 if (!found) { 665 pr_err("no channels available\n"); 666 return ret; 667 } 668 669 client->trans = (void *)chan; 670 client->status = Connected; 671 chan->client = client; 672 673 return 0; 674} 675 676/** 677 * p9_virtio_remove - clean up resources associated with a virtio device 678 * @vdev: virtio device to remove 679 * 680 */ 681 682static void p9_virtio_remove(struct virtio_device *vdev) 683{ 684 struct virtio_chan *chan = vdev->priv; 685 unsigned long warning_time; 686 687 mutex_lock(&virtio_9p_lock); 688 689 /* Remove self from list so we don't get new users. */ 690 list_del(&chan->chan_list); 691 warning_time = jiffies; 692 693 /* Wait for existing users to close. */ 694 while (chan->inuse) { 695 mutex_unlock(&virtio_9p_lock); 696 msleep(250); 697 if (time_after(jiffies, warning_time + 10 * HZ)) { 698 dev_emerg(&vdev->dev, 699 "p9_virtio_remove: waiting for device in use.\n"); 700 warning_time = jiffies; 701 } 702 mutex_lock(&virtio_9p_lock); 703 } 704 705 mutex_unlock(&virtio_9p_lock); 706 707 vdev->config->del_vqs(vdev); 708 709 sysfs_remove_file(&(vdev->dev.kobj), &dev_attr_mount_tag.attr); 710 kobject_uevent(&(vdev->dev.kobj), KOBJ_CHANGE); 711 kfree(chan->tag); 712 kfree(chan->vc_wq); 713 kfree(chan); 714 715} 716 717static struct virtio_device_id id_table[] = { 718 { VIRTIO_ID_9P, VIRTIO_DEV_ANY_ID }, 719 { 0 }, 720}; 721 722static unsigned int features[] = { 723 VIRTIO_9P_MOUNT_TAG, 724}; 725 726/* The standard "struct lguest_driver": */ 727static struct virtio_driver p9_virtio_drv = { 728 .feature_table = features, 729 .feature_table_size = ARRAY_SIZE(features), 730 .driver.name = KBUILD_MODNAME, 731 .driver.owner = THIS_MODULE, 732 .id_table = id_table, 733 .probe = p9_virtio_probe, 734 .remove = p9_virtio_remove, 735}; 736 737static struct p9_trans_module p9_virtio_trans = { 738 .name = "virtio", 739 .create = p9_virtio_create, 740 .close = p9_virtio_close, 741 .request = p9_virtio_request, 742 .zc_request = p9_virtio_zc_request, 743 .cancel = p9_virtio_cancel, 744 /* 745 * We leave one entry for input and one entry for response 746 * headers. We also skip one more entry to accomodate, address 747 * that are not at page boundary, that can result in an extra 748 * page in zero copy. 749 */ 750 .maxsize = PAGE_SIZE * (VIRTQUEUE_NUM - 3), 751 .def = 1, 752 .owner = THIS_MODULE, 753}; 754 755/* The standard init function */ 756static int __init p9_virtio_init(void) 757{ 758 INIT_LIST_HEAD(&virtio_chan_list); 759 760 v9fs_register_trans(&p9_virtio_trans); 761 return register_virtio_driver(&p9_virtio_drv); 762} 763 764static void __exit p9_virtio_cleanup(void) 765{ 766 unregister_virtio_driver(&p9_virtio_drv); 767 v9fs_unregister_trans(&p9_virtio_trans); 768} 769 770module_init(p9_virtio_init); 771module_exit(p9_virtio_cleanup); 772 773MODULE_DEVICE_TABLE(virtio, id_table); 774MODULE_AUTHOR("Eric Van Hensbergen <ericvh@gmail.com>"); 775MODULE_DESCRIPTION("Virtio 9p Transport"); 776MODULE_LICENSE("GPL"); 777