1 //#define DEBUG
2 #include <linux/spinlock.h>
3 #include <linux/slab.h>
4 #include <linux/blkdev.h>
5 #include <linux/hdreg.h>
6 #include <linux/module.h>
7 #include <linux/mutex.h>
8 #include <linux/virtio.h>
9 #include <linux/virtio_blk.h>
10 #include <linux/scatterlist.h>
11 #include <linux/string_helpers.h>
12 #include <scsi/scsi_cmnd.h>
13 #include <linux/idr.h>
14
15 #define PART_BITS 4
16
17 static int major;
18 static DEFINE_IDA(vd_index_ida);
19
20 struct workqueue_struct *virtblk_wq;
21
22 struct virtio_blk
23 {
24 struct virtio_device *vdev;
25 struct virtqueue *vq;
26
27 /* The disk structure for the kernel. */
28 struct gendisk *disk;
29
30 mempool_t *pool;
31
32 /* Process context for config space updates */
33 struct work_struct config_work;
34
35 /* Lock for config space updates */
36 struct mutex config_lock;
37
38 /* enable config space updates */
39 bool config_enable;
40
41 /* What host tells us, plus 2 for header & tailer. */
42 unsigned int sg_elems;
43
44 /* Ida index - used to track minor number allocations. */
45 int index;
46
47 /* Scatterlist: can be too big for stack. */
48 struct scatterlist sg[/*sg_elems*/];
49 };
50
51 struct virtblk_req
52 {
53 struct request *req;
54 struct virtio_blk_outhdr out_hdr;
55 struct virtio_scsi_inhdr in_hdr;
56 u8 status;
57 };
58
blk_done(struct virtqueue * vq)59 static void blk_done(struct virtqueue *vq)
60 {
61 struct virtio_blk *vblk = vq->vdev->priv;
62 struct virtblk_req *vbr;
63 unsigned int len;
64 unsigned long flags;
65
66 spin_lock_irqsave(vblk->disk->queue->queue_lock, flags);
67 while ((vbr = virtqueue_get_buf(vblk->vq, &len)) != NULL) {
68 int error;
69
70 switch (vbr->status) {
71 case VIRTIO_BLK_S_OK:
72 error = 0;
73 break;
74 case VIRTIO_BLK_S_UNSUPP:
75 error = -ENOTTY;
76 break;
77 default:
78 error = -EIO;
79 break;
80 }
81
82 switch (vbr->req->cmd_type) {
83 case REQ_TYPE_BLOCK_PC:
84 vbr->req->resid_len = vbr->in_hdr.residual;
85 vbr->req->sense_len = vbr->in_hdr.sense_len;
86 vbr->req->errors = vbr->in_hdr.errors;
87 break;
88 case REQ_TYPE_SPECIAL:
89 vbr->req->errors = (error != 0);
90 break;
91 default:
92 break;
93 }
94
95 __blk_end_request_all(vbr->req, error);
96 mempool_free(vbr, vblk->pool);
97 }
98 /* In case queue is stopped waiting for more buffers. */
99 blk_start_queue(vblk->disk->queue);
100 spin_unlock_irqrestore(vblk->disk->queue->queue_lock, flags);
101 }
102
do_req(struct request_queue * q,struct virtio_blk * vblk,struct request * req)103 static bool do_req(struct request_queue *q, struct virtio_blk *vblk,
104 struct request *req)
105 {
106 unsigned long num, out = 0, in = 0;
107 struct virtblk_req *vbr;
108
109 vbr = mempool_alloc(vblk->pool, GFP_ATOMIC);
110 if (!vbr)
111 /* When another request finishes we'll try again. */
112 return false;
113
114 vbr->req = req;
115
116 if (req->cmd_flags & REQ_FLUSH) {
117 vbr->out_hdr.type = VIRTIO_BLK_T_FLUSH;
118 vbr->out_hdr.sector = 0;
119 vbr->out_hdr.ioprio = req_get_ioprio(vbr->req);
120 } else {
121 switch (req->cmd_type) {
122 case REQ_TYPE_FS:
123 vbr->out_hdr.type = 0;
124 vbr->out_hdr.sector = blk_rq_pos(vbr->req);
125 vbr->out_hdr.ioprio = req_get_ioprio(vbr->req);
126 break;
127 case REQ_TYPE_BLOCK_PC:
128 vbr->out_hdr.type = VIRTIO_BLK_T_SCSI_CMD;
129 vbr->out_hdr.sector = 0;
130 vbr->out_hdr.ioprio = req_get_ioprio(vbr->req);
131 break;
132 case REQ_TYPE_SPECIAL:
133 vbr->out_hdr.type = VIRTIO_BLK_T_GET_ID;
134 vbr->out_hdr.sector = 0;
135 vbr->out_hdr.ioprio = req_get_ioprio(vbr->req);
136 break;
137 default:
138 /* We don't put anything else in the queue. */
139 BUG();
140 }
141 }
142
143 sg_set_buf(&vblk->sg[out++], &vbr->out_hdr, sizeof(vbr->out_hdr));
144
145 /*
146 * If this is a packet command we need a couple of additional headers.
147 * Behind the normal outhdr we put a segment with the scsi command
148 * block, and before the normal inhdr we put the sense data and the
149 * inhdr with additional status information before the normal inhdr.
150 */
151 if (vbr->req->cmd_type == REQ_TYPE_BLOCK_PC)
152 sg_set_buf(&vblk->sg[out++], vbr->req->cmd, vbr->req->cmd_len);
153
154 num = blk_rq_map_sg(q, vbr->req, vblk->sg + out);
155
156 if (vbr->req->cmd_type == REQ_TYPE_BLOCK_PC) {
157 sg_set_buf(&vblk->sg[num + out + in++], vbr->req->sense, SCSI_SENSE_BUFFERSIZE);
158 sg_set_buf(&vblk->sg[num + out + in++], &vbr->in_hdr,
159 sizeof(vbr->in_hdr));
160 }
161
162 sg_set_buf(&vblk->sg[num + out + in++], &vbr->status,
163 sizeof(vbr->status));
164
165 if (num) {
166 if (rq_data_dir(vbr->req) == WRITE) {
167 vbr->out_hdr.type |= VIRTIO_BLK_T_OUT;
168 out += num;
169 } else {
170 vbr->out_hdr.type |= VIRTIO_BLK_T_IN;
171 in += num;
172 }
173 }
174
175 if (virtqueue_add_buf(vblk->vq, vblk->sg, out, in, vbr, GFP_ATOMIC)<0) {
176 mempool_free(vbr, vblk->pool);
177 return false;
178 }
179
180 return true;
181 }
182
do_virtblk_request(struct request_queue * q)183 static void do_virtblk_request(struct request_queue *q)
184 {
185 struct virtio_blk *vblk = q->queuedata;
186 struct request *req;
187 unsigned int issued = 0;
188
189 while ((req = blk_peek_request(q)) != NULL) {
190 BUG_ON(req->nr_phys_segments + 2 > vblk->sg_elems);
191
192 /* If this request fails, stop queue and wait for something to
193 finish to restart it. */
194 if (!do_req(q, vblk, req)) {
195 blk_stop_queue(q);
196 break;
197 }
198 blk_start_request(req);
199 issued++;
200 }
201
202 if (issued)
203 virtqueue_kick(vblk->vq);
204 }
205
206 /* return id (s/n) string for *disk to *id_str
207 */
virtblk_get_id(struct gendisk * disk,char * id_str)208 static int virtblk_get_id(struct gendisk *disk, char *id_str)
209 {
210 struct virtio_blk *vblk = disk->private_data;
211 struct request *req;
212 struct bio *bio;
213 int err;
214
215 bio = bio_map_kern(vblk->disk->queue, id_str, VIRTIO_BLK_ID_BYTES,
216 GFP_KERNEL);
217 if (IS_ERR(bio))
218 return PTR_ERR(bio);
219
220 req = blk_make_request(vblk->disk->queue, bio, GFP_KERNEL);
221 if (IS_ERR(req)) {
222 bio_put(bio);
223 return PTR_ERR(req);
224 }
225
226 req->cmd_type = REQ_TYPE_SPECIAL;
227 err = blk_execute_rq(vblk->disk->queue, vblk->disk, req, false);
228 blk_put_request(req);
229
230 return err;
231 }
232
virtblk_ioctl(struct block_device * bdev,fmode_t mode,unsigned int cmd,unsigned long data)233 static int virtblk_ioctl(struct block_device *bdev, fmode_t mode,
234 unsigned int cmd, unsigned long data)
235 {
236 struct gendisk *disk = bdev->bd_disk;
237 struct virtio_blk *vblk = disk->private_data;
238
239 /*
240 * Only allow the generic SCSI ioctls if the host can support it.
241 */
242 if (!virtio_has_feature(vblk->vdev, VIRTIO_BLK_F_SCSI))
243 return -ENOTTY;
244
245 return scsi_cmd_blk_ioctl(bdev, mode, cmd,
246 (void __user *)data);
247 }
248
249 /* We provide getgeo only to please some old bootloader/partitioning tools */
virtblk_getgeo(struct block_device * bd,struct hd_geometry * geo)250 static int virtblk_getgeo(struct block_device *bd, struct hd_geometry *geo)
251 {
252 struct virtio_blk *vblk = bd->bd_disk->private_data;
253 struct virtio_blk_geometry vgeo;
254 int err;
255
256 /* see if the host passed in geometry config */
257 err = virtio_config_val(vblk->vdev, VIRTIO_BLK_F_GEOMETRY,
258 offsetof(struct virtio_blk_config, geometry),
259 &vgeo);
260
261 if (!err) {
262 geo->heads = vgeo.heads;
263 geo->sectors = vgeo.sectors;
264 geo->cylinders = vgeo.cylinders;
265 } else {
266 /* some standard values, similar to sd */
267 geo->heads = 1 << 6;
268 geo->sectors = 1 << 5;
269 geo->cylinders = get_capacity(bd->bd_disk) >> 11;
270 }
271 return 0;
272 }
273
274 static const struct block_device_operations virtblk_fops = {
275 .ioctl = virtblk_ioctl,
276 .owner = THIS_MODULE,
277 .getgeo = virtblk_getgeo,
278 };
279
index_to_minor(int index)280 static int index_to_minor(int index)
281 {
282 return index << PART_BITS;
283 }
284
minor_to_index(int minor)285 static int minor_to_index(int minor)
286 {
287 return minor >> PART_BITS;
288 }
289
virtblk_serial_show(struct device * dev,struct device_attribute * attr,char * buf)290 static ssize_t virtblk_serial_show(struct device *dev,
291 struct device_attribute *attr, char *buf)
292 {
293 struct gendisk *disk = dev_to_disk(dev);
294 int err;
295
296 /* sysfs gives us a PAGE_SIZE buffer */
297 BUILD_BUG_ON(PAGE_SIZE < VIRTIO_BLK_ID_BYTES);
298
299 buf[VIRTIO_BLK_ID_BYTES] = '\0';
300 err = virtblk_get_id(disk, buf);
301 if (!err)
302 return strlen(buf);
303
304 if (err == -EIO) /* Unsupported? Make it empty. */
305 return 0;
306
307 return err;
308 }
309 DEVICE_ATTR(serial, S_IRUGO, virtblk_serial_show, NULL);
310
virtblk_config_changed_work(struct work_struct * work)311 static void virtblk_config_changed_work(struct work_struct *work)
312 {
313 struct virtio_blk *vblk =
314 container_of(work, struct virtio_blk, config_work);
315 struct virtio_device *vdev = vblk->vdev;
316 struct request_queue *q = vblk->disk->queue;
317 char cap_str_2[10], cap_str_10[10];
318 u64 capacity, size;
319
320 mutex_lock(&vblk->config_lock);
321 if (!vblk->config_enable)
322 goto done;
323
324 /* Host must always specify the capacity. */
325 vdev->config->get(vdev, offsetof(struct virtio_blk_config, capacity),
326 &capacity, sizeof(capacity));
327
328 /* If capacity is too big, truncate with warning. */
329 if ((sector_t)capacity != capacity) {
330 dev_warn(&vdev->dev, "Capacity %llu too large: truncating\n",
331 (unsigned long long)capacity);
332 capacity = (sector_t)-1;
333 }
334
335 size = capacity * queue_logical_block_size(q);
336 string_get_size(size, STRING_UNITS_2, cap_str_2, sizeof(cap_str_2));
337 string_get_size(size, STRING_UNITS_10, cap_str_10, sizeof(cap_str_10));
338
339 dev_notice(&vdev->dev,
340 "new size: %llu %d-byte logical blocks (%s/%s)\n",
341 (unsigned long long)capacity,
342 queue_logical_block_size(q),
343 cap_str_10, cap_str_2);
344
345 set_capacity(vblk->disk, capacity);
346 revalidate_disk(vblk->disk);
347 done:
348 mutex_unlock(&vblk->config_lock);
349 }
350
virtblk_config_changed(struct virtio_device * vdev)351 static void virtblk_config_changed(struct virtio_device *vdev)
352 {
353 struct virtio_blk *vblk = vdev->priv;
354
355 queue_work(virtblk_wq, &vblk->config_work);
356 }
357
init_vq(struct virtio_blk * vblk)358 static int init_vq(struct virtio_blk *vblk)
359 {
360 int err = 0;
361
362 /* We expect one virtqueue, for output. */
363 vblk->vq = virtio_find_single_vq(vblk->vdev, blk_done, "requests");
364 if (IS_ERR(vblk->vq))
365 err = PTR_ERR(vblk->vq);
366
367 return err;
368 }
369
370 /*
371 * Legacy naming scheme used for virtio devices. We are stuck with it for
372 * virtio blk but don't ever use it for any new driver.
373 */
virtblk_name_format(char * prefix,int index,char * buf,int buflen)374 static int virtblk_name_format(char *prefix, int index, char *buf, int buflen)
375 {
376 const int base = 'z' - 'a' + 1;
377 char *begin = buf + strlen(prefix);
378 char *end = buf + buflen;
379 char *p;
380 int unit;
381
382 p = end - 1;
383 *p = '\0';
384 unit = base;
385 do {
386 if (p == begin)
387 return -EINVAL;
388 *--p = 'a' + (index % unit);
389 index = (index / unit) - 1;
390 } while (index >= 0);
391
392 memmove(begin, p, end - p);
393 memcpy(buf, prefix, strlen(prefix));
394
395 return 0;
396 }
397
virtblk_probe(struct virtio_device * vdev)398 static int __devinit virtblk_probe(struct virtio_device *vdev)
399 {
400 struct virtio_blk *vblk;
401 struct request_queue *q;
402 int err, index;
403 u64 cap;
404 u32 v, blk_size, sg_elems, opt_io_size;
405 u16 min_io_size;
406 u8 physical_block_exp, alignment_offset;
407
408 err = ida_simple_get(&vd_index_ida, 0, minor_to_index(1 << MINORBITS),
409 GFP_KERNEL);
410 if (err < 0)
411 goto out;
412 index = err;
413
414 /* We need to know how many segments before we allocate. */
415 err = virtio_config_val(vdev, VIRTIO_BLK_F_SEG_MAX,
416 offsetof(struct virtio_blk_config, seg_max),
417 &sg_elems);
418
419 /* We need at least one SG element, whatever they say. */
420 if (err || !sg_elems)
421 sg_elems = 1;
422
423 /* We need an extra sg elements at head and tail. */
424 sg_elems += 2;
425 vdev->priv = vblk = kmalloc(sizeof(*vblk) +
426 sizeof(vblk->sg[0]) * sg_elems, GFP_KERNEL);
427 if (!vblk) {
428 err = -ENOMEM;
429 goto out_free_index;
430 }
431
432 vblk->vdev = vdev;
433 vblk->sg_elems = sg_elems;
434 sg_init_table(vblk->sg, vblk->sg_elems);
435 mutex_init(&vblk->config_lock);
436 INIT_WORK(&vblk->config_work, virtblk_config_changed_work);
437 vblk->config_enable = true;
438
439 err = init_vq(vblk);
440 if (err)
441 goto out_free_vblk;
442
443 vblk->pool = mempool_create_kmalloc_pool(1,sizeof(struct virtblk_req));
444 if (!vblk->pool) {
445 err = -ENOMEM;
446 goto out_free_vq;
447 }
448
449 /* FIXME: How many partitions? How long is a piece of string? */
450 vblk->disk = alloc_disk(1 << PART_BITS);
451 if (!vblk->disk) {
452 err = -ENOMEM;
453 goto out_mempool;
454 }
455
456 q = vblk->disk->queue = blk_init_queue(do_virtblk_request, NULL);
457 if (!q) {
458 err = -ENOMEM;
459 goto out_put_disk;
460 }
461
462 q->queuedata = vblk;
463
464 virtblk_name_format("vd", index, vblk->disk->disk_name, DISK_NAME_LEN);
465
466 vblk->disk->major = major;
467 vblk->disk->first_minor = index_to_minor(index);
468 vblk->disk->private_data = vblk;
469 vblk->disk->fops = &virtblk_fops;
470 vblk->disk->driverfs_dev = &vdev->dev;
471 vblk->index = index;
472
473 /* configure queue flush support */
474 if (virtio_has_feature(vdev, VIRTIO_BLK_F_FLUSH))
475 blk_queue_flush(q, REQ_FLUSH);
476
477 /* If disk is read-only in the host, the guest should obey */
478 if (virtio_has_feature(vdev, VIRTIO_BLK_F_RO))
479 set_disk_ro(vblk->disk, 1);
480
481 /* Host must always specify the capacity. */
482 vdev->config->get(vdev, offsetof(struct virtio_blk_config, capacity),
483 &cap, sizeof(cap));
484
485 /* If capacity is too big, truncate with warning. */
486 if ((sector_t)cap != cap) {
487 dev_warn(&vdev->dev, "Capacity %llu too large: truncating\n",
488 (unsigned long long)cap);
489 cap = (sector_t)-1;
490 }
491 set_capacity(vblk->disk, cap);
492
493 /* We can handle whatever the host told us to handle. */
494 blk_queue_max_segments(q, vblk->sg_elems-2);
495
496 /* No need to bounce any requests */
497 blk_queue_bounce_limit(q, BLK_BOUNCE_ANY);
498
499 /* No real sector limit. */
500 blk_queue_max_hw_sectors(q, -1U);
501
502 /* Host can optionally specify maximum segment size and number of
503 * segments. */
504 err = virtio_config_val(vdev, VIRTIO_BLK_F_SIZE_MAX,
505 offsetof(struct virtio_blk_config, size_max),
506 &v);
507 if (!err)
508 blk_queue_max_segment_size(q, v);
509 else
510 blk_queue_max_segment_size(q, -1U);
511
512 /* Host can optionally specify the block size of the device */
513 err = virtio_config_val(vdev, VIRTIO_BLK_F_BLK_SIZE,
514 offsetof(struct virtio_blk_config, blk_size),
515 &blk_size);
516 if (!err)
517 blk_queue_logical_block_size(q, blk_size);
518 else
519 blk_size = queue_logical_block_size(q);
520
521 /* Use topology information if available */
522 err = virtio_config_val(vdev, VIRTIO_BLK_F_TOPOLOGY,
523 offsetof(struct virtio_blk_config, physical_block_exp),
524 &physical_block_exp);
525 if (!err && physical_block_exp)
526 blk_queue_physical_block_size(q,
527 blk_size * (1 << physical_block_exp));
528
529 err = virtio_config_val(vdev, VIRTIO_BLK_F_TOPOLOGY,
530 offsetof(struct virtio_blk_config, alignment_offset),
531 &alignment_offset);
532 if (!err && alignment_offset)
533 blk_queue_alignment_offset(q, blk_size * alignment_offset);
534
535 err = virtio_config_val(vdev, VIRTIO_BLK_F_TOPOLOGY,
536 offsetof(struct virtio_blk_config, min_io_size),
537 &min_io_size);
538 if (!err && min_io_size)
539 blk_queue_io_min(q, blk_size * min_io_size);
540
541 err = virtio_config_val(vdev, VIRTIO_BLK_F_TOPOLOGY,
542 offsetof(struct virtio_blk_config, opt_io_size),
543 &opt_io_size);
544 if (!err && opt_io_size)
545 blk_queue_io_opt(q, blk_size * opt_io_size);
546
547
548 add_disk(vblk->disk);
549 err = device_create_file(disk_to_dev(vblk->disk), &dev_attr_serial);
550 if (err)
551 goto out_del_disk;
552
553 return 0;
554
555 out_del_disk:
556 del_gendisk(vblk->disk);
557 blk_cleanup_queue(vblk->disk->queue);
558 out_put_disk:
559 put_disk(vblk->disk);
560 out_mempool:
561 mempool_destroy(vblk->pool);
562 out_free_vq:
563 vdev->config->del_vqs(vdev);
564 out_free_vblk:
565 kfree(vblk);
566 out_free_index:
567 ida_simple_remove(&vd_index_ida, index);
568 out:
569 return err;
570 }
571
virtblk_remove(struct virtio_device * vdev)572 static void __devexit virtblk_remove(struct virtio_device *vdev)
573 {
574 struct virtio_blk *vblk = vdev->priv;
575 int index = vblk->index;
576 int refc;
577
578 /* Prevent config work handler from accessing the device. */
579 mutex_lock(&vblk->config_lock);
580 vblk->config_enable = false;
581 mutex_unlock(&vblk->config_lock);
582
583 del_gendisk(vblk->disk);
584 blk_cleanup_queue(vblk->disk->queue);
585
586 /* Stop all the virtqueues. */
587 vdev->config->reset(vdev);
588
589 flush_work(&vblk->config_work);
590
591 refc = atomic_read(&disk_to_dev(vblk->disk)->kobj.kref.refcount);
592 put_disk(vblk->disk);
593 mempool_destroy(vblk->pool);
594 vdev->config->del_vqs(vdev);
595 kfree(vblk);
596
597 /* Only free device id if we don't have any users */
598 if (refc == 1)
599 ida_simple_remove(&vd_index_ida, index);
600 }
601
602 #ifdef CONFIG_PM
virtblk_freeze(struct virtio_device * vdev)603 static int virtblk_freeze(struct virtio_device *vdev)
604 {
605 struct virtio_blk *vblk = vdev->priv;
606
607 /* Ensure we don't receive any more interrupts */
608 vdev->config->reset(vdev);
609
610 /* Prevent config work handler from accessing the device. */
611 mutex_lock(&vblk->config_lock);
612 vblk->config_enable = false;
613 mutex_unlock(&vblk->config_lock);
614
615 flush_work(&vblk->config_work);
616
617 spin_lock_irq(vblk->disk->queue->queue_lock);
618 blk_stop_queue(vblk->disk->queue);
619 spin_unlock_irq(vblk->disk->queue->queue_lock);
620 blk_sync_queue(vblk->disk->queue);
621
622 vdev->config->del_vqs(vdev);
623 return 0;
624 }
625
virtblk_restore(struct virtio_device * vdev)626 static int virtblk_restore(struct virtio_device *vdev)
627 {
628 struct virtio_blk *vblk = vdev->priv;
629 int ret;
630
631 vblk->config_enable = true;
632 ret = init_vq(vdev->priv);
633 if (!ret) {
634 spin_lock_irq(vblk->disk->queue->queue_lock);
635 blk_start_queue(vblk->disk->queue);
636 spin_unlock_irq(vblk->disk->queue->queue_lock);
637 }
638 return ret;
639 }
640 #endif
641
642 static const struct virtio_device_id id_table[] = {
643 { VIRTIO_ID_BLOCK, VIRTIO_DEV_ANY_ID },
644 { 0 },
645 };
646
647 static unsigned int features[] = {
648 VIRTIO_BLK_F_SEG_MAX, VIRTIO_BLK_F_SIZE_MAX, VIRTIO_BLK_F_GEOMETRY,
649 VIRTIO_BLK_F_RO, VIRTIO_BLK_F_BLK_SIZE, VIRTIO_BLK_F_SCSI,
650 VIRTIO_BLK_F_FLUSH, VIRTIO_BLK_F_TOPOLOGY
651 };
652
653 /*
654 * virtio_blk causes spurious section mismatch warning by
655 * simultaneously referring to a __devinit and a __devexit function.
656 * Use __refdata to avoid this warning.
657 */
658 static struct virtio_driver __refdata virtio_blk = {
659 .feature_table = features,
660 .feature_table_size = ARRAY_SIZE(features),
661 .driver.name = KBUILD_MODNAME,
662 .driver.owner = THIS_MODULE,
663 .id_table = id_table,
664 .probe = virtblk_probe,
665 .remove = __devexit_p(virtblk_remove),
666 .config_changed = virtblk_config_changed,
667 #ifdef CONFIG_PM
668 .freeze = virtblk_freeze,
669 .restore = virtblk_restore,
670 #endif
671 };
672
init(void)673 static int __init init(void)
674 {
675 int error;
676
677 virtblk_wq = alloc_workqueue("virtio-blk", 0, 0);
678 if (!virtblk_wq)
679 return -ENOMEM;
680
681 major = register_blkdev(0, "virtblk");
682 if (major < 0) {
683 error = major;
684 goto out_destroy_workqueue;
685 }
686
687 error = register_virtio_driver(&virtio_blk);
688 if (error)
689 goto out_unregister_blkdev;
690 return 0;
691
692 out_unregister_blkdev:
693 unregister_blkdev(major, "virtblk");
694 out_destroy_workqueue:
695 destroy_workqueue(virtblk_wq);
696 return error;
697 }
698
fini(void)699 static void __exit fini(void)
700 {
701 unregister_blkdev(major, "virtblk");
702 unregister_virtio_driver(&virtio_blk);
703 destroy_workqueue(virtblk_wq);
704 }
705 module_init(init);
706 module_exit(fini);
707
708 MODULE_DEVICE_TABLE(virtio, id_table);
709 MODULE_DESCRIPTION("Virtio block driver");
710 MODULE_LICENSE("GPL");
711