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e467cde2 RR |
1 | //#define DEBUG |
2 | #include <linux/spinlock.h> | |
3 | #include <linux/blkdev.h> | |
4 | #include <linux/hdreg.h> | |
5 | #include <linux/virtio.h> | |
6 | #include <linux/virtio_blk.h> | |
7 | #include <linux/virtio_blk.h> | |
8 | ||
9 | static unsigned char virtblk_index = 'a'; | |
10 | struct virtio_blk | |
11 | { | |
12 | spinlock_t lock; | |
13 | ||
14 | struct virtio_device *vdev; | |
15 | struct virtqueue *vq; | |
16 | ||
17 | /* The disk structure for the kernel. */ | |
18 | struct gendisk *disk; | |
19 | ||
20 | /* Request tracking. */ | |
21 | struct list_head reqs; | |
22 | ||
23 | mempool_t *pool; | |
24 | ||
25 | /* Scatterlist: can be too big for stack. */ | |
26 | struct scatterlist sg[3+MAX_PHYS_SEGMENTS]; | |
27 | }; | |
28 | ||
29 | struct virtblk_req | |
30 | { | |
31 | struct list_head list; | |
32 | struct request *req; | |
33 | struct virtio_blk_outhdr out_hdr; | |
34 | struct virtio_blk_inhdr in_hdr; | |
35 | }; | |
36 | ||
37 | static bool blk_done(struct virtqueue *vq) | |
38 | { | |
39 | struct virtio_blk *vblk = vq->vdev->priv; | |
40 | struct virtblk_req *vbr; | |
41 | unsigned int len; | |
42 | unsigned long flags; | |
43 | ||
44 | spin_lock_irqsave(&vblk->lock, flags); | |
45 | while ((vbr = vblk->vq->vq_ops->get_buf(vblk->vq, &len)) != NULL) { | |
46 | int uptodate; | |
47 | switch (vbr->in_hdr.status) { | |
48 | case VIRTIO_BLK_S_OK: | |
49 | uptodate = 1; | |
50 | break; | |
51 | case VIRTIO_BLK_S_UNSUPP: | |
52 | uptodate = -ENOTTY; | |
53 | break; | |
54 | default: | |
55 | uptodate = 0; | |
56 | break; | |
57 | } | |
58 | ||
59 | end_dequeued_request(vbr->req, uptodate); | |
60 | list_del(&vbr->list); | |
61 | mempool_free(vbr, vblk->pool); | |
62 | } | |
63 | /* In case queue is stopped waiting for more buffers. */ | |
64 | blk_start_queue(vblk->disk->queue); | |
65 | spin_unlock_irqrestore(&vblk->lock, flags); | |
66 | return true; | |
67 | } | |
68 | ||
69 | static bool do_req(struct request_queue *q, struct virtio_blk *vblk, | |
70 | struct request *req) | |
71 | { | |
72 | unsigned long num, out, in; | |
73 | struct virtblk_req *vbr; | |
74 | ||
75 | vbr = mempool_alloc(vblk->pool, GFP_ATOMIC); | |
76 | if (!vbr) | |
77 | /* When another request finishes we'll try again. */ | |
78 | return false; | |
79 | ||
80 | vbr->req = req; | |
81 | if (blk_fs_request(vbr->req)) { | |
82 | vbr->out_hdr.type = 0; | |
83 | vbr->out_hdr.sector = vbr->req->sector; | |
84 | vbr->out_hdr.ioprio = vbr->req->ioprio; | |
85 | } else if (blk_pc_request(vbr->req)) { | |
86 | vbr->out_hdr.type = VIRTIO_BLK_T_SCSI_CMD; | |
87 | vbr->out_hdr.sector = 0; | |
88 | vbr->out_hdr.ioprio = vbr->req->ioprio; | |
89 | } else { | |
90 | /* We don't put anything else in the queue. */ | |
91 | BUG(); | |
92 | } | |
93 | ||
94 | if (blk_barrier_rq(vbr->req)) | |
95 | vbr->out_hdr.type |= VIRTIO_BLK_T_BARRIER; | |
96 | ||
97 | /* We have to zero this, otherwise blk_rq_map_sg gets upset. */ | |
98 | memset(vblk->sg, 0, sizeof(vblk->sg)); | |
99 | sg_set_buf(&vblk->sg[0], &vbr->out_hdr, sizeof(vbr->out_hdr)); | |
100 | num = blk_rq_map_sg(q, vbr->req, vblk->sg+1); | |
101 | sg_set_buf(&vblk->sg[num+1], &vbr->in_hdr, sizeof(vbr->in_hdr)); | |
102 | ||
103 | if (rq_data_dir(vbr->req) == WRITE) { | |
104 | vbr->out_hdr.type |= VIRTIO_BLK_T_OUT; | |
105 | out = 1 + num; | |
106 | in = 1; | |
107 | } else { | |
108 | vbr->out_hdr.type |= VIRTIO_BLK_T_IN; | |
109 | out = 1; | |
110 | in = 1 + num; | |
111 | } | |
112 | ||
113 | if (vblk->vq->vq_ops->add_buf(vblk->vq, vblk->sg, out, in, vbr)) { | |
114 | mempool_free(vbr, vblk->pool); | |
115 | return false; | |
116 | } | |
117 | ||
118 | list_add_tail(&vbr->list, &vblk->reqs); | |
119 | return true; | |
120 | } | |
121 | ||
122 | static void do_virtblk_request(struct request_queue *q) | |
123 | { | |
124 | struct virtio_blk *vblk = NULL; | |
125 | struct request *req; | |
126 | unsigned int issued = 0; | |
127 | ||
128 | while ((req = elv_next_request(q)) != NULL) { | |
129 | vblk = req->rq_disk->private_data; | |
130 | BUG_ON(req->nr_phys_segments > ARRAY_SIZE(vblk->sg)); | |
131 | ||
132 | /* If this request fails, stop queue and wait for something to | |
133 | finish to restart it. */ | |
134 | if (!do_req(q, vblk, req)) { | |
135 | blk_stop_queue(q); | |
136 | break; | |
137 | } | |
138 | blkdev_dequeue_request(req); | |
139 | issued++; | |
140 | } | |
141 | ||
142 | if (issued) | |
143 | vblk->vq->vq_ops->kick(vblk->vq); | |
144 | } | |
145 | ||
146 | static int virtblk_ioctl(struct inode *inode, struct file *filp, | |
147 | unsigned cmd, unsigned long data) | |
148 | { | |
149 | return scsi_cmd_ioctl(filp, inode->i_bdev->bd_disk->queue, | |
150 | inode->i_bdev->bd_disk, cmd, | |
151 | (void __user *)data); | |
152 | } | |
153 | ||
154 | static struct block_device_operations virtblk_fops = { | |
155 | .ioctl = virtblk_ioctl, | |
156 | .owner = THIS_MODULE, | |
157 | }; | |
158 | ||
159 | static int virtblk_probe(struct virtio_device *vdev) | |
160 | { | |
161 | struct virtio_blk *vblk; | |
162 | int err, major; | |
163 | void *token; | |
164 | unsigned int len; | |
165 | u64 cap; | |
166 | u32 v; | |
167 | ||
168 | vdev->priv = vblk = kmalloc(sizeof(*vblk), GFP_KERNEL); | |
169 | if (!vblk) { | |
170 | err = -ENOMEM; | |
171 | goto out; | |
172 | } | |
173 | ||
174 | INIT_LIST_HEAD(&vblk->reqs); | |
175 | spin_lock_init(&vblk->lock); | |
176 | vblk->vdev = vdev; | |
177 | ||
178 | /* We expect one virtqueue, for output. */ | |
179 | vblk->vq = vdev->config->find_vq(vdev, blk_done); | |
180 | if (IS_ERR(vblk->vq)) { | |
181 | err = PTR_ERR(vblk->vq); | |
182 | goto out_free_vblk; | |
183 | } | |
184 | ||
185 | vblk->pool = mempool_create_kmalloc_pool(1,sizeof(struct virtblk_req)); | |
186 | if (!vblk->pool) { | |
187 | err = -ENOMEM; | |
188 | goto out_free_vq; | |
189 | } | |
190 | ||
191 | major = register_blkdev(0, "virtblk"); | |
192 | if (major < 0) { | |
193 | err = major; | |
194 | goto out_mempool; | |
195 | } | |
196 | ||
197 | /* FIXME: How many partitions? How long is a piece of string? */ | |
198 | vblk->disk = alloc_disk(1 << 4); | |
199 | if (!vblk->disk) { | |
200 | err = -ENOMEM; | |
201 | goto out_unregister_blkdev; | |
202 | } | |
203 | ||
204 | vblk->disk->queue = blk_init_queue(do_virtblk_request, &vblk->lock); | |
205 | if (!vblk->disk->queue) { | |
206 | err = -ENOMEM; | |
207 | goto out_put_disk; | |
208 | } | |
209 | ||
210 | sprintf(vblk->disk->disk_name, "vd%c", virtblk_index++); | |
211 | vblk->disk->major = major; | |
212 | vblk->disk->first_minor = 0; | |
213 | vblk->disk->private_data = vblk; | |
214 | vblk->disk->fops = &virtblk_fops; | |
215 | ||
216 | /* If barriers are supported, tell block layer that queue is ordered */ | |
217 | token = vdev->config->find(vdev, VIRTIO_CONFIG_BLK_F, &len); | |
218 | if (virtio_use_bit(vdev, token, len, VIRTIO_BLK_F_BARRIER)) | |
219 | blk_queue_ordered(vblk->disk->queue, QUEUE_ORDERED_TAG, NULL); | |
220 | ||
221 | err = virtio_config_val(vdev, VIRTIO_CONFIG_BLK_F_CAPACITY, &cap); | |
222 | if (err) { | |
223 | dev_err(&vdev->dev, "Bad/missing capacity in config\n"); | |
224 | goto out_put_disk; | |
225 | } | |
226 | ||
227 | /* If capacity is too big, truncate with warning. */ | |
228 | if ((sector_t)cap != cap) { | |
229 | dev_warn(&vdev->dev, "Capacity %llu too large: truncating\n", | |
230 | (unsigned long long)cap); | |
231 | cap = (sector_t)-1; | |
232 | } | |
233 | set_capacity(vblk->disk, cap); | |
234 | ||
235 | err = virtio_config_val(vdev, VIRTIO_CONFIG_BLK_F_SIZE_MAX, &v); | |
236 | if (!err) | |
237 | blk_queue_max_segment_size(vblk->disk->queue, v); | |
238 | else if (err != -ENOENT) { | |
239 | dev_err(&vdev->dev, "Bad SIZE_MAX in config\n"); | |
240 | goto out_put_disk; | |
241 | } | |
242 | ||
243 | err = virtio_config_val(vdev, VIRTIO_CONFIG_BLK_F_SEG_MAX, &v); | |
244 | if (!err) | |
245 | blk_queue_max_hw_segments(vblk->disk->queue, v); | |
246 | else if (err != -ENOENT) { | |
247 | dev_err(&vdev->dev, "Bad SEG_MAX in config\n"); | |
248 | goto out_put_disk; | |
249 | } | |
250 | ||
251 | add_disk(vblk->disk); | |
252 | return 0; | |
253 | ||
254 | out_put_disk: | |
255 | put_disk(vblk->disk); | |
256 | out_unregister_blkdev: | |
257 | unregister_blkdev(major, "virtblk"); | |
258 | out_mempool: | |
259 | mempool_destroy(vblk->pool); | |
260 | out_free_vq: | |
261 | vdev->config->del_vq(vblk->vq); | |
262 | out_free_vblk: | |
263 | kfree(vblk); | |
264 | out: | |
265 | return err; | |
266 | } | |
267 | ||
268 | static void virtblk_remove(struct virtio_device *vdev) | |
269 | { | |
270 | struct virtio_blk *vblk = vdev->priv; | |
271 | int major = vblk->disk->major; | |
272 | ||
273 | BUG_ON(!list_empty(&vblk->reqs)); | |
274 | blk_cleanup_queue(vblk->disk->queue); | |
275 | put_disk(vblk->disk); | |
276 | unregister_blkdev(major, "virtblk"); | |
277 | mempool_destroy(vblk->pool); | |
278 | kfree(vblk); | |
279 | } | |
280 | ||
281 | static struct virtio_device_id id_table[] = { | |
282 | { VIRTIO_ID_BLOCK, VIRTIO_DEV_ANY_ID }, | |
283 | { 0 }, | |
284 | }; | |
285 | ||
286 | static struct virtio_driver virtio_blk = { | |
287 | .driver.name = KBUILD_MODNAME, | |
288 | .driver.owner = THIS_MODULE, | |
289 | .id_table = id_table, | |
290 | .probe = virtblk_probe, | |
291 | .remove = __devexit_p(virtblk_remove), | |
292 | }; | |
293 | ||
294 | static int __init init(void) | |
295 | { | |
296 | return register_virtio_driver(&virtio_blk); | |
297 | } | |
298 | ||
299 | static void __exit fini(void) | |
300 | { | |
301 | unregister_virtio_driver(&virtio_blk); | |
302 | } | |
303 | module_init(init); | |
304 | module_exit(fini); | |
305 | ||
306 | MODULE_DEVICE_TABLE(virtio, id_table); | |
307 | MODULE_DESCRIPTION("Virtio block driver"); | |
308 | MODULE_LICENSE("GPL"); |