blob: 6143337527e729e9441ff84aa4c1e94a3090b407 [file] [log] [blame]
Rusty Russelle467cde2007-10-22 11:03:38 +10001//#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>
Jens Axboe3d1266c2007-10-24 13:21:21 +02007#include <linux/scatterlist.h>
8
9#define VIRTIO_MAX_SG (3+MAX_PHYS_SEGMENTS)
Rusty Russelle467cde2007-10-22 11:03:38 +100010
11static unsigned char virtblk_index = 'a';
12struct virtio_blk
13{
14 spinlock_t lock;
15
16 struct virtio_device *vdev;
17 struct virtqueue *vq;
18
19 /* The disk structure for the kernel. */
20 struct gendisk *disk;
21
22 /* Request tracking. */
23 struct list_head reqs;
24
25 mempool_t *pool;
26
27 /* Scatterlist: can be too big for stack. */
Jens Axboe3d1266c2007-10-24 13:21:21 +020028 struct scatterlist sg[VIRTIO_MAX_SG];
Rusty Russelle467cde2007-10-22 11:03:38 +100029};
30
31struct virtblk_req
32{
33 struct list_head list;
34 struct request *req;
35 struct virtio_blk_outhdr out_hdr;
36 struct virtio_blk_inhdr in_hdr;
37};
38
Rusty Russell18445c42008-02-04 23:49:57 -050039static void blk_done(struct virtqueue *vq)
Rusty Russelle467cde2007-10-22 11:03:38 +100040{
41 struct virtio_blk *vblk = vq->vdev->priv;
42 struct virtblk_req *vbr;
43 unsigned int len;
44 unsigned long flags;
45
46 spin_lock_irqsave(&vblk->lock, flags);
47 while ((vbr = vblk->vq->vq_ops->get_buf(vblk->vq, &len)) != NULL) {
48 int uptodate;
49 switch (vbr->in_hdr.status) {
50 case VIRTIO_BLK_S_OK:
51 uptodate = 1;
52 break;
53 case VIRTIO_BLK_S_UNSUPP:
54 uptodate = -ENOTTY;
55 break;
56 default:
57 uptodate = 0;
58 break;
59 }
60
61 end_dequeued_request(vbr->req, uptodate);
62 list_del(&vbr->list);
63 mempool_free(vbr, vblk->pool);
64 }
65 /* In case queue is stopped waiting for more buffers. */
66 blk_start_queue(vblk->disk->queue);
67 spin_unlock_irqrestore(&vblk->lock, flags);
Rusty Russelle467cde2007-10-22 11:03:38 +100068}
69
70static bool do_req(struct request_queue *q, struct virtio_blk *vblk,
71 struct request *req)
72{
73 unsigned long num, out, in;
74 struct virtblk_req *vbr;
75
76 vbr = mempool_alloc(vblk->pool, GFP_ATOMIC);
77 if (!vbr)
78 /* When another request finishes we'll try again. */
79 return false;
80
81 vbr->req = req;
82 if (blk_fs_request(vbr->req)) {
83 vbr->out_hdr.type = 0;
84 vbr->out_hdr.sector = vbr->req->sector;
85 vbr->out_hdr.ioprio = vbr->req->ioprio;
86 } else if (blk_pc_request(vbr->req)) {
87 vbr->out_hdr.type = VIRTIO_BLK_T_SCSI_CMD;
88 vbr->out_hdr.sector = 0;
89 vbr->out_hdr.ioprio = vbr->req->ioprio;
90 } else {
91 /* We don't put anything else in the queue. */
92 BUG();
93 }
94
95 if (blk_barrier_rq(vbr->req))
96 vbr->out_hdr.type |= VIRTIO_BLK_T_BARRIER;
97
Jens Axboe3d1266c2007-10-24 13:21:21 +020098 /* This init could be done at vblk creation time */
99 sg_init_table(vblk->sg, VIRTIO_MAX_SG);
Rusty Russelle467cde2007-10-22 11:03:38 +1000100 sg_set_buf(&vblk->sg[0], &vbr->out_hdr, sizeof(vbr->out_hdr));
101 num = blk_rq_map_sg(q, vbr->req, vblk->sg+1);
102 sg_set_buf(&vblk->sg[num+1], &vbr->in_hdr, sizeof(vbr->in_hdr));
103
104 if (rq_data_dir(vbr->req) == WRITE) {
105 vbr->out_hdr.type |= VIRTIO_BLK_T_OUT;
106 out = 1 + num;
107 in = 1;
108 } else {
109 vbr->out_hdr.type |= VIRTIO_BLK_T_IN;
110 out = 1;
111 in = 1 + num;
112 }
113
114 if (vblk->vq->vq_ops->add_buf(vblk->vq, vblk->sg, out, in, vbr)) {
115 mempool_free(vbr, vblk->pool);
116 return false;
117 }
118
119 list_add_tail(&vbr->list, &vblk->reqs);
120 return true;
121}
122
123static void do_virtblk_request(struct request_queue *q)
124{
125 struct virtio_blk *vblk = NULL;
126 struct request *req;
127 unsigned int issued = 0;
128
129 while ((req = elv_next_request(q)) != NULL) {
130 vblk = req->rq_disk->private_data;
131 BUG_ON(req->nr_phys_segments > ARRAY_SIZE(vblk->sg));
132
133 /* If this request fails, stop queue and wait for something to
134 finish to restart it. */
135 if (!do_req(q, vblk, req)) {
136 blk_stop_queue(q);
137 break;
138 }
139 blkdev_dequeue_request(req);
140 issued++;
141 }
142
143 if (issued)
144 vblk->vq->vq_ops->kick(vblk->vq);
145}
146
147static int virtblk_ioctl(struct inode *inode, struct file *filp,
148 unsigned cmd, unsigned long data)
149{
150 return scsi_cmd_ioctl(filp, inode->i_bdev->bd_disk->queue,
151 inode->i_bdev->bd_disk, cmd,
152 (void __user *)data);
153}
154
155static struct block_device_operations virtblk_fops = {
156 .ioctl = virtblk_ioctl,
157 .owner = THIS_MODULE,
158};
159
160static int virtblk_probe(struct virtio_device *vdev)
161{
162 struct virtio_blk *vblk;
163 int err, major;
Rusty Russelle467cde2007-10-22 11:03:38 +1000164 u64 cap;
165 u32 v;
166
167 vdev->priv = vblk = kmalloc(sizeof(*vblk), GFP_KERNEL);
168 if (!vblk) {
169 err = -ENOMEM;
170 goto out;
171 }
172
173 INIT_LIST_HEAD(&vblk->reqs);
174 spin_lock_init(&vblk->lock);
175 vblk->vdev = vdev;
176
177 /* We expect one virtqueue, for output. */
Rusty Russella586d4f2008-02-04 23:49:56 -0500178 vblk->vq = vdev->config->find_vq(vdev, 0, blk_done);
Rusty Russelle467cde2007-10-22 11:03:38 +1000179 if (IS_ERR(vblk->vq)) {
180 err = PTR_ERR(vblk->vq);
181 goto out_free_vblk;
182 }
183
184 vblk->pool = mempool_create_kmalloc_pool(1,sizeof(struct virtblk_req));
185 if (!vblk->pool) {
186 err = -ENOMEM;
187 goto out_free_vq;
188 }
189
190 major = register_blkdev(0, "virtblk");
191 if (major < 0) {
192 err = major;
193 goto out_mempool;
194 }
195
196 /* FIXME: How many partitions? How long is a piece of string? */
197 vblk->disk = alloc_disk(1 << 4);
198 if (!vblk->disk) {
199 err = -ENOMEM;
200 goto out_unregister_blkdev;
201 }
202
203 vblk->disk->queue = blk_init_queue(do_virtblk_request, &vblk->lock);
204 if (!vblk->disk->queue) {
205 err = -ENOMEM;
206 goto out_put_disk;
207 }
208
209 sprintf(vblk->disk->disk_name, "vd%c", virtblk_index++);
210 vblk->disk->major = major;
211 vblk->disk->first_minor = 0;
212 vblk->disk->private_data = vblk;
213 vblk->disk->fops = &virtblk_fops;
214
215 /* If barriers are supported, tell block layer that queue is ordered */
Rusty Russella586d4f2008-02-04 23:49:56 -0500216 if (vdev->config->feature(vdev, VIRTIO_BLK_F_BARRIER))
Rusty Russelle467cde2007-10-22 11:03:38 +1000217 blk_queue_ordered(vblk->disk->queue, QUEUE_ORDERED_TAG, NULL);
218
Rusty Russella586d4f2008-02-04 23:49:56 -0500219 /* Host must always specify the capacity. */
220 __virtio_config_val(vdev, offsetof(struct virtio_blk_config, capacity),
221 &cap);
Rusty Russelle467cde2007-10-22 11:03:38 +1000222
223 /* If capacity is too big, truncate with warning. */
224 if ((sector_t)cap != cap) {
225 dev_warn(&vdev->dev, "Capacity %llu too large: truncating\n",
226 (unsigned long long)cap);
227 cap = (sector_t)-1;
228 }
229 set_capacity(vblk->disk, cap);
230
Rusty Russella586d4f2008-02-04 23:49:56 -0500231 /* Host can optionally specify maximum segment size and number of
232 * segments. */
233 err = virtio_config_val(vdev, VIRTIO_BLK_F_SIZE_MAX,
234 offsetof(struct virtio_blk_config, size_max),
235 &v);
Rusty Russelle467cde2007-10-22 11:03:38 +1000236 if (!err)
237 blk_queue_max_segment_size(vblk->disk->queue, v);
Rusty Russelle467cde2007-10-22 11:03:38 +1000238
Rusty Russella586d4f2008-02-04 23:49:56 -0500239 err = virtio_config_val(vdev, VIRTIO_BLK_F_SEG_MAX,
240 offsetof(struct virtio_blk_config, seg_max),
241 &v);
Rusty Russelle467cde2007-10-22 11:03:38 +1000242 if (!err)
243 blk_queue_max_hw_segments(vblk->disk->queue, v);
Rusty Russelle467cde2007-10-22 11:03:38 +1000244
245 add_disk(vblk->disk);
246 return 0;
247
248out_put_disk:
249 put_disk(vblk->disk);
250out_unregister_blkdev:
251 unregister_blkdev(major, "virtblk");
252out_mempool:
253 mempool_destroy(vblk->pool);
254out_free_vq:
255 vdev->config->del_vq(vblk->vq);
256out_free_vblk:
257 kfree(vblk);
258out:
259 return err;
260}
261
262static void virtblk_remove(struct virtio_device *vdev)
263{
264 struct virtio_blk *vblk = vdev->priv;
265 int major = vblk->disk->major;
266
Rusty Russell6e5aa7e2008-02-04 23:50:03 -0500267 /* Nothing should be pending. */
Rusty Russelle467cde2007-10-22 11:03:38 +1000268 BUG_ON(!list_empty(&vblk->reqs));
Rusty Russell6e5aa7e2008-02-04 23:50:03 -0500269
270 /* Stop all the virtqueues. */
271 vdev->config->reset(vdev);
272
Rusty Russelle467cde2007-10-22 11:03:38 +1000273 blk_cleanup_queue(vblk->disk->queue);
274 put_disk(vblk->disk);
275 unregister_blkdev(major, "virtblk");
276 mempool_destroy(vblk->pool);
Rusty Russell74b25532007-11-19 11:20:42 -0500277 vdev->config->del_vq(vblk->vq);
Rusty Russelle467cde2007-10-22 11:03:38 +1000278 kfree(vblk);
279}
280
281static struct virtio_device_id id_table[] = {
282 { VIRTIO_ID_BLOCK, VIRTIO_DEV_ANY_ID },
283 { 0 },
284};
285
286static 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
294static int __init init(void)
295{
296 return register_virtio_driver(&virtio_blk);
297}
298
299static void __exit fini(void)
300{
301 unregister_virtio_driver(&virtio_blk);
302}
303module_init(init);
304module_exit(fini);
305
306MODULE_DEVICE_TABLE(virtio, id_table);
307MODULE_DESCRIPTION("Virtio block driver");
308MODULE_LICENSE("GPL");