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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 | #include <linux/in.h> | |
30 | #include <linux/module.h> | |
31 | #include <linux/net.h> | |
32 | #include <linux/ipv6.h> | |
33 | #include <linux/errno.h> | |
34 | #include <linux/kernel.h> | |
35 | #include <linux/un.h> | |
36 | #include <linux/uaccess.h> | |
37 | #include <linux/inet.h> | |
38 | #include <linux/idr.h> | |
39 | #include <linux/file.h> | |
40 | #include <linux/slab.h> | |
41 | #include <net/9p/9p.h> | |
42 | #include <linux/parser.h> | |
43 | #include <net/9p/client.h> | |
44 | #include <net/9p/transport.h> | |
45 | #include <linux/scatterlist.h> | |
46 | #include <linux/virtio.h> | |
47 | #include <linux/virtio_9p.h> | |
48 | ||
49 | #define VIRTQUEUE_NUM 128 | |
50 | ||
51 | /* a single mutex to manage channel initialization and attachment */ | |
52 | static DEFINE_MUTEX(virtio_9p_lock); | |
53 | ||
54 | /** | |
55 | * struct virtio_chan - per-instance transport information | |
56 | * @initialized: whether the channel is initialized | |
57 | * @inuse: whether the channel is in use | |
58 | * @lock: protects multiple elements within this structure | |
59 | * @client: client instance | |
60 | * @vdev: virtio dev associated with this channel | |
61 | * @vq: virtio queue associated with this channel | |
62 | * @sg: scatter gather list which is used to pack a request (protected?) | |
63 | * | |
64 | * We keep all per-channel information in a structure. | |
65 | * This structure is allocated within the devices dev->mem space. | |
66 | * A pointer to the structure will get put in the transport private. | |
67 | * | |
68 | */ | |
69 | ||
70 | struct virtio_chan { | |
71 | bool inuse; | |
72 | ||
73 | spinlock_t lock; | |
74 | ||
75 | struct p9_client *client; | |
76 | struct virtio_device *vdev; | |
77 | struct virtqueue *vq; | |
78 | ||
79 | /* Scatterlist: can be too big for stack. */ | |
80 | struct scatterlist sg[VIRTQUEUE_NUM]; | |
81 | ||
82 | int tag_len; | |
83 | /* | |
84 | * tag name to identify a mount Non-null terminated | |
85 | */ | |
86 | char *tag; | |
87 | ||
88 | struct list_head chan_list; | |
89 | }; | |
90 | ||
91 | static struct list_head virtio_chan_list; | |
92 | ||
93 | /* How many bytes left in this page. */ | |
94 | static unsigned int rest_of_page(void *data) | |
95 | { | |
96 | return PAGE_SIZE - ((unsigned long)data % PAGE_SIZE); | |
97 | } | |
98 | ||
99 | /** | |
100 | * p9_virtio_close - reclaim resources of a channel | |
101 | * @client: client instance | |
102 | * | |
103 | * This reclaims a channel by freeing its resources and | |
104 | * reseting its inuse flag. | |
105 | * | |
106 | */ | |
107 | ||
108 | static void p9_virtio_close(struct p9_client *client) | |
109 | { | |
110 | struct virtio_chan *chan = client->trans; | |
111 | ||
112 | mutex_lock(&virtio_9p_lock); | |
113 | if (chan) | |
114 | chan->inuse = false; | |
115 | mutex_unlock(&virtio_9p_lock); | |
116 | } | |
117 | ||
118 | /** | |
119 | * req_done - callback which signals activity from the server | |
120 | * @vq: virtio queue activity was received on | |
121 | * | |
122 | * This notifies us that the server has triggered some activity | |
123 | * on the virtio channel - most likely a response to request we | |
124 | * sent. Figure out which requests now have responses and wake up | |
125 | * those threads. | |
126 | * | |
127 | * Bugs: could do with some additional sanity checking, but appears to work. | |
128 | * | |
129 | */ | |
130 | ||
131 | static void req_done(struct virtqueue *vq) | |
132 | { | |
133 | struct virtio_chan *chan = vq->vdev->priv; | |
134 | struct p9_fcall *rc; | |
135 | unsigned int len; | |
136 | struct p9_req_t *req; | |
137 | ||
138 | P9_DPRINTK(P9_DEBUG_TRANS, ": request done\n"); | |
139 | ||
140 | while ((rc = virtqueue_get_buf(chan->vq, &len)) != NULL) { | |
141 | P9_DPRINTK(P9_DEBUG_TRANS, ": rc %p\n", rc); | |
142 | P9_DPRINTK(P9_DEBUG_TRANS, ": lookup tag %d\n", rc->tag); | |
143 | req = p9_tag_lookup(chan->client, rc->tag); | |
144 | req->status = REQ_STATUS_RCVD; | |
145 | p9_client_cb(chan->client, req); | |
146 | } | |
147 | } | |
148 | ||
149 | /** | |
150 | * pack_sg_list - pack a scatter gather list from a linear buffer | |
151 | * @sg: scatter/gather list to pack into | |
152 | * @start: which segment of the sg_list to start at | |
153 | * @limit: maximum segment to pack data to | |
154 | * @data: data to pack into scatter/gather list | |
155 | * @count: amount of data to pack into the scatter/gather list | |
156 | * | |
157 | * sg_lists have multiple segments of various sizes. This will pack | |
158 | * arbitrary data into an existing scatter gather list, segmenting the | |
159 | * data as necessary within constraints. | |
160 | * | |
161 | */ | |
162 | ||
163 | static int | |
164 | pack_sg_list(struct scatterlist *sg, int start, int limit, char *data, | |
165 | int count) | |
166 | { | |
167 | int s; | |
168 | int index = start; | |
169 | ||
170 | while (count) { | |
171 | s = rest_of_page(data); | |
172 | if (s > count) | |
173 | s = count; | |
174 | sg_set_buf(&sg[index++], data, s); | |
175 | count -= s; | |
176 | data += s; | |
177 | BUG_ON(index > limit); | |
178 | } | |
179 | ||
180 | return index-start; | |
181 | } | |
182 | ||
183 | /* We don't currently allow canceling of virtio requests */ | |
184 | static int p9_virtio_cancel(struct p9_client *client, struct p9_req_t *req) | |
185 | { | |
186 | return 1; | |
187 | } | |
188 | ||
189 | /** | |
190 | * p9_virtio_request - issue a request | |
191 | * @client: client instance issuing the request | |
192 | * @req: request to be issued | |
193 | * | |
194 | */ | |
195 | ||
196 | static int | |
197 | p9_virtio_request(struct p9_client *client, struct p9_req_t *req) | |
198 | { | |
199 | int in, out; | |
200 | struct virtio_chan *chan = client->trans; | |
201 | char *rdata = (char *)req->rc+sizeof(struct p9_fcall); | |
202 | ||
203 | P9_DPRINTK(P9_DEBUG_TRANS, "9p debug: virtio request\n"); | |
204 | ||
205 | out = pack_sg_list(chan->sg, 0, VIRTQUEUE_NUM, req->tc->sdata, | |
206 | req->tc->size); | |
207 | in = pack_sg_list(chan->sg, out, VIRTQUEUE_NUM-out, rdata, | |
208 | client->msize); | |
209 | ||
210 | req->status = REQ_STATUS_SENT; | |
211 | ||
212 | if (virtqueue_add_buf(chan->vq, chan->sg, out, in, req->tc) < 0) { | |
213 | P9_DPRINTK(P9_DEBUG_TRANS, | |
214 | "9p debug: virtio rpc add_buf returned failure"); | |
215 | return -EIO; | |
216 | } | |
217 | ||
218 | virtqueue_kick(chan->vq); | |
219 | ||
220 | P9_DPRINTK(P9_DEBUG_TRANS, "9p debug: virtio request kicked\n"); | |
221 | return 0; | |
222 | } | |
223 | ||
224 | static ssize_t p9_mount_tag_show(struct device *dev, | |
225 | struct device_attribute *attr, char *buf) | |
226 | { | |
227 | struct virtio_chan *chan; | |
228 | struct virtio_device *vdev; | |
229 | ||
230 | vdev = dev_to_virtio(dev); | |
231 | chan = vdev->priv; | |
232 | ||
233 | return snprintf(buf, chan->tag_len + 1, "%s", chan->tag); | |
234 | } | |
235 | ||
236 | static DEVICE_ATTR(mount_tag, 0444, p9_mount_tag_show, NULL); | |
237 | ||
238 | /** | |
239 | * p9_virtio_probe - probe for existence of 9P virtio channels | |
240 | * @vdev: virtio device to probe | |
241 | * | |
242 | * This probes for existing virtio channels. | |
243 | * | |
244 | */ | |
245 | ||
246 | static int p9_virtio_probe(struct virtio_device *vdev) | |
247 | { | |
248 | __u16 tag_len; | |
249 | char *tag; | |
250 | int err; | |
251 | struct virtio_chan *chan; | |
252 | ||
253 | chan = kmalloc(sizeof(struct virtio_chan), GFP_KERNEL); | |
254 | if (!chan) { | |
255 | printk(KERN_ERR "9p: Failed to allocate virtio 9P channel\n"); | |
256 | err = -ENOMEM; | |
257 | goto fail; | |
258 | } | |
259 | ||
260 | chan->vdev = vdev; | |
261 | ||
262 | /* We expect one virtqueue, for requests. */ | |
263 | chan->vq = virtio_find_single_vq(vdev, req_done, "requests"); | |
264 | if (IS_ERR(chan->vq)) { | |
265 | err = PTR_ERR(chan->vq); | |
266 | goto out_free_vq; | |
267 | } | |
268 | chan->vq->vdev->priv = chan; | |
269 | spin_lock_init(&chan->lock); | |
270 | ||
271 | sg_init_table(chan->sg, VIRTQUEUE_NUM); | |
272 | ||
273 | chan->inuse = false; | |
274 | if (virtio_has_feature(vdev, VIRTIO_9P_MOUNT_TAG)) { | |
275 | vdev->config->get(vdev, | |
276 | offsetof(struct virtio_9p_config, tag_len), | |
277 | &tag_len, sizeof(tag_len)); | |
278 | } else { | |
279 | err = -EINVAL; | |
280 | goto out_free_vq; | |
281 | } | |
282 | tag = kmalloc(tag_len, GFP_KERNEL); | |
283 | if (!tag) { | |
284 | err = -ENOMEM; | |
285 | goto out_free_vq; | |
286 | } | |
287 | vdev->config->get(vdev, offsetof(struct virtio_9p_config, tag), | |
288 | tag, tag_len); | |
289 | chan->tag = tag; | |
290 | chan->tag_len = tag_len; | |
291 | err = sysfs_create_file(&(vdev->dev.kobj), &dev_attr_mount_tag.attr); | |
292 | if (err) { | |
293 | kfree(tag); | |
294 | goto out_free_vq; | |
295 | } | |
296 | mutex_lock(&virtio_9p_lock); | |
297 | list_add_tail(&chan->chan_list, &virtio_chan_list); | |
298 | mutex_unlock(&virtio_9p_lock); | |
299 | return 0; | |
300 | ||
301 | out_free_vq: | |
302 | vdev->config->del_vqs(vdev); | |
303 | kfree(chan); | |
304 | fail: | |
305 | return err; | |
306 | } | |
307 | ||
308 | ||
309 | /** | |
310 | * p9_virtio_create - allocate a new virtio channel | |
311 | * @client: client instance invoking this transport | |
312 | * @devname: string identifying the channel to connect to (unused) | |
313 | * @args: args passed from sys_mount() for per-transport options (unused) | |
314 | * | |
315 | * This sets up a transport channel for 9p communication. Right now | |
316 | * we only match the first available channel, but eventually we couldlook up | |
317 | * alternate channels by matching devname versus a virtio_config entry. | |
318 | * We use a simple reference count mechanism to ensure that only a single | |
319 | * mount has a channel open at a time. | |
320 | * | |
321 | */ | |
322 | ||
323 | static int | |
324 | p9_virtio_create(struct p9_client *client, const char *devname, char *args) | |
325 | { | |
326 | struct virtio_chan *chan; | |
327 | int ret = -ENOENT; | |
328 | int found = 0; | |
329 | ||
330 | mutex_lock(&virtio_9p_lock); | |
331 | list_for_each_entry(chan, &virtio_chan_list, chan_list) { | |
332 | if (!strncmp(devname, chan->tag, chan->tag_len) && | |
333 | strlen(devname) == chan->tag_len) { | |
334 | if (!chan->inuse) { | |
335 | chan->inuse = true; | |
336 | found = 1; | |
337 | break; | |
338 | } | |
339 | ret = -EBUSY; | |
340 | } | |
341 | } | |
342 | mutex_unlock(&virtio_9p_lock); | |
343 | ||
344 | if (!found) { | |
345 | printk(KERN_ERR "9p: no channels available\n"); | |
346 | return ret; | |
347 | } | |
348 | ||
349 | client->trans = (void *)chan; | |
350 | client->status = Connected; | |
351 | chan->client = client; | |
352 | ||
353 | return 0; | |
354 | } | |
355 | ||
356 | /** | |
357 | * p9_virtio_remove - clean up resources associated with a virtio device | |
358 | * @vdev: virtio device to remove | |
359 | * | |
360 | */ | |
361 | ||
362 | static void p9_virtio_remove(struct virtio_device *vdev) | |
363 | { | |
364 | struct virtio_chan *chan = vdev->priv; | |
365 | ||
366 | BUG_ON(chan->inuse); | |
367 | vdev->config->del_vqs(vdev); | |
368 | ||
369 | mutex_lock(&virtio_9p_lock); | |
370 | list_del(&chan->chan_list); | |
371 | mutex_unlock(&virtio_9p_lock); | |
372 | sysfs_remove_file(&(vdev->dev.kobj), &dev_attr_mount_tag.attr); | |
373 | kfree(chan->tag); | |
374 | kfree(chan); | |
375 | ||
376 | } | |
377 | ||
378 | static struct virtio_device_id id_table[] = { | |
379 | { VIRTIO_ID_9P, VIRTIO_DEV_ANY_ID }, | |
380 | { 0 }, | |
381 | }; | |
382 | ||
383 | static unsigned int features[] = { | |
384 | VIRTIO_9P_MOUNT_TAG, | |
385 | }; | |
386 | ||
387 | /* The standard "struct lguest_driver": */ | |
388 | static struct virtio_driver p9_virtio_drv = { | |
389 | .feature_table = features, | |
390 | .feature_table_size = ARRAY_SIZE(features), | |
391 | .driver.name = KBUILD_MODNAME, | |
392 | .driver.owner = THIS_MODULE, | |
393 | .id_table = id_table, | |
394 | .probe = p9_virtio_probe, | |
395 | .remove = p9_virtio_remove, | |
396 | }; | |
397 | ||
398 | static struct p9_trans_module p9_virtio_trans = { | |
399 | .name = "virtio", | |
400 | .create = p9_virtio_create, | |
401 | .close = p9_virtio_close, | |
402 | .request = p9_virtio_request, | |
403 | .cancel = p9_virtio_cancel, | |
404 | .maxsize = PAGE_SIZE*16, | |
405 | .def = 0, | |
406 | .owner = THIS_MODULE, | |
407 | }; | |
408 | ||
409 | /* The standard init function */ | |
410 | static int __init p9_virtio_init(void) | |
411 | { | |
412 | INIT_LIST_HEAD(&virtio_chan_list); | |
413 | ||
414 | v9fs_register_trans(&p9_virtio_trans); | |
415 | return register_virtio_driver(&p9_virtio_drv); | |
416 | } | |
417 | ||
418 | static void __exit p9_virtio_cleanup(void) | |
419 | { | |
420 | unregister_virtio_driver(&p9_virtio_drv); | |
421 | v9fs_unregister_trans(&p9_virtio_trans); | |
422 | } | |
423 | ||
424 | module_init(p9_virtio_init); | |
425 | module_exit(p9_virtio_cleanup); | |
426 | ||
427 | MODULE_DEVICE_TABLE(virtio, id_table); | |
428 | MODULE_AUTHOR("Eric Van Hensbergen <ericvh@gmail.com>"); | |
429 | MODULE_DESCRIPTION("Virtio 9p Transport"); | |
430 | MODULE_LICENSE("GPL"); |