Root/drivers/block/virtio_blk.c

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
17static int major;
18static DEFINE_IDA(vd_index_ida);
19
20struct workqueue_struct *virtblk_wq;
21
22struct 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
51struct 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
59static 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
103static 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
183static 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 */
208static 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
233static 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 */
250static 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
274static const struct block_device_operations virtblk_fops = {
275    .ioctl = virtblk_ioctl,
276    .owner = THIS_MODULE,
277    .getgeo = virtblk_getgeo,
278};
279
280static int index_to_minor(int index)
281{
282    return index << PART_BITS;
283}
284
285static int minor_to_index(int minor)
286{
287    return minor >> PART_BITS;
288}
289
290static 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}
309DEVICE_ATTR(serial, S_IRUGO, virtblk_serial_show, NULL);
310
311static 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);
347done:
348    mutex_unlock(&vblk->config_lock);
349}
350
351static 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
358static 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 */
374static 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
398static int virtblk_get_cache_mode(struct virtio_device *vdev)
399{
400    u8 writeback;
401    int err;
402
403    err = virtio_config_val(vdev, VIRTIO_BLK_F_CONFIG_WCE,
404                offsetof(struct virtio_blk_config, wce),
405                &writeback);
406    if (err)
407        writeback = virtio_has_feature(vdev, VIRTIO_BLK_F_WCE);
408
409    return writeback;
410}
411
412static void virtblk_update_cache_mode(struct virtio_device *vdev)
413{
414    u8 writeback = virtblk_get_cache_mode(vdev);
415    struct virtio_blk *vblk = vdev->priv;
416
417    if (writeback)
418        blk_queue_flush(vblk->disk->queue, REQ_FLUSH);
419    else
420        blk_queue_flush(vblk->disk->queue, 0);
421
422    revalidate_disk(vblk->disk);
423}
424
425static const char *const virtblk_cache_types[] = {
426    "write through", "write back"
427};
428
429static ssize_t
430virtblk_cache_type_store(struct device *dev, struct device_attribute *attr,
431             const char *buf, size_t count)
432{
433    struct gendisk *disk = dev_to_disk(dev);
434    struct virtio_blk *vblk = disk->private_data;
435    struct virtio_device *vdev = vblk->vdev;
436    int i;
437    u8 writeback;
438
439    BUG_ON(!virtio_has_feature(vblk->vdev, VIRTIO_BLK_F_CONFIG_WCE));
440    for (i = ARRAY_SIZE(virtblk_cache_types); --i >= 0; )
441        if (sysfs_streq(buf, virtblk_cache_types[i]))
442            break;
443
444    if (i < 0)
445        return -EINVAL;
446
447    writeback = i;
448    vdev->config->set(vdev,
449              offsetof(struct virtio_blk_config, wce),
450              &writeback, sizeof(writeback));
451
452    virtblk_update_cache_mode(vdev);
453    return count;
454}
455
456static ssize_t
457virtblk_cache_type_show(struct device *dev, struct device_attribute *attr,
458             char *buf)
459{
460    struct gendisk *disk = dev_to_disk(dev);
461    struct virtio_blk *vblk = disk->private_data;
462    u8 writeback = virtblk_get_cache_mode(vblk->vdev);
463
464    BUG_ON(writeback >= ARRAY_SIZE(virtblk_cache_types));
465    return snprintf(buf, 40, "%s\n", virtblk_cache_types[writeback]);
466}
467
468static const struct device_attribute dev_attr_cache_type_ro =
469    __ATTR(cache_type, S_IRUGO,
470           virtblk_cache_type_show, NULL);
471static const struct device_attribute dev_attr_cache_type_rw =
472    __ATTR(cache_type, S_IRUGO|S_IWUSR,
473           virtblk_cache_type_show, virtblk_cache_type_store);
474
475static int __devinit virtblk_probe(struct virtio_device *vdev)
476{
477    struct virtio_blk *vblk;
478    struct request_queue *q;
479    int err, index;
480    u64 cap;
481    u32 v, blk_size, sg_elems, opt_io_size;
482    u16 min_io_size;
483    u8 physical_block_exp, alignment_offset;
484
485    err = ida_simple_get(&vd_index_ida, 0, minor_to_index(1 << MINORBITS),
486                 GFP_KERNEL);
487    if (err < 0)
488        goto out;
489    index = err;
490
491    /* We need to know how many segments before we allocate. */
492    err = virtio_config_val(vdev, VIRTIO_BLK_F_SEG_MAX,
493                offsetof(struct virtio_blk_config, seg_max),
494                &sg_elems);
495
496    /* We need at least one SG element, whatever they say. */
497    if (err || !sg_elems)
498        sg_elems = 1;
499
500    /* We need an extra sg elements at head and tail. */
501    sg_elems += 2;
502    vdev->priv = vblk = kmalloc(sizeof(*vblk) +
503                    sizeof(vblk->sg[0]) * sg_elems, GFP_KERNEL);
504    if (!vblk) {
505        err = -ENOMEM;
506        goto out_free_index;
507    }
508
509    vblk->vdev = vdev;
510    vblk->sg_elems = sg_elems;
511    sg_init_table(vblk->sg, vblk->sg_elems);
512    mutex_init(&vblk->config_lock);
513    INIT_WORK(&vblk->config_work, virtblk_config_changed_work);
514    vblk->config_enable = true;
515
516    err = init_vq(vblk);
517    if (err)
518        goto out_free_vblk;
519
520    vblk->pool = mempool_create_kmalloc_pool(1,sizeof(struct virtblk_req));
521    if (!vblk->pool) {
522        err = -ENOMEM;
523        goto out_free_vq;
524    }
525
526    /* FIXME: How many partitions? How long is a piece of string? */
527    vblk->disk = alloc_disk(1 << PART_BITS);
528    if (!vblk->disk) {
529        err = -ENOMEM;
530        goto out_mempool;
531    }
532
533    q = vblk->disk->queue = blk_init_queue(do_virtblk_request, NULL);
534    if (!q) {
535        err = -ENOMEM;
536        goto out_put_disk;
537    }
538
539    q->queuedata = vblk;
540
541    virtblk_name_format("vd", index, vblk->disk->disk_name, DISK_NAME_LEN);
542
543    vblk->disk->major = major;
544    vblk->disk->first_minor = index_to_minor(index);
545    vblk->disk->private_data = vblk;
546    vblk->disk->fops = &virtblk_fops;
547    vblk->disk->driverfs_dev = &vdev->dev;
548    vblk->index = index;
549
550    /* configure queue flush support */
551    virtblk_update_cache_mode(vdev);
552
553    /* If disk is read-only in the host, the guest should obey */
554    if (virtio_has_feature(vdev, VIRTIO_BLK_F_RO))
555        set_disk_ro(vblk->disk, 1);
556
557    /* Host must always specify the capacity. */
558    vdev->config->get(vdev, offsetof(struct virtio_blk_config, capacity),
559              &cap, sizeof(cap));
560
561    /* If capacity is too big, truncate with warning. */
562    if ((sector_t)cap != cap) {
563        dev_warn(&vdev->dev, "Capacity %llu too large: truncating\n",
564             (unsigned long long)cap);
565        cap = (sector_t)-1;
566    }
567    set_capacity(vblk->disk, cap);
568
569    /* We can handle whatever the host told us to handle. */
570    blk_queue_max_segments(q, vblk->sg_elems-2);
571
572    /* No need to bounce any requests */
573    blk_queue_bounce_limit(q, BLK_BOUNCE_ANY);
574
575    /* No real sector limit. */
576    blk_queue_max_hw_sectors(q, -1U);
577
578    /* Host can optionally specify maximum segment size and number of
579     * segments. */
580    err = virtio_config_val(vdev, VIRTIO_BLK_F_SIZE_MAX,
581                offsetof(struct virtio_blk_config, size_max),
582                &v);
583    if (!err)
584        blk_queue_max_segment_size(q, v);
585    else
586        blk_queue_max_segment_size(q, -1U);
587
588    /* Host can optionally specify the block size of the device */
589    err = virtio_config_val(vdev, VIRTIO_BLK_F_BLK_SIZE,
590                offsetof(struct virtio_blk_config, blk_size),
591                &blk_size);
592    if (!err)
593        blk_queue_logical_block_size(q, blk_size);
594    else
595        blk_size = queue_logical_block_size(q);
596
597    /* Use topology information if available */
598    err = virtio_config_val(vdev, VIRTIO_BLK_F_TOPOLOGY,
599            offsetof(struct virtio_blk_config, physical_block_exp),
600            &physical_block_exp);
601    if (!err && physical_block_exp)
602        blk_queue_physical_block_size(q,
603                blk_size * (1 << physical_block_exp));
604
605    err = virtio_config_val(vdev, VIRTIO_BLK_F_TOPOLOGY,
606            offsetof(struct virtio_blk_config, alignment_offset),
607            &alignment_offset);
608    if (!err && alignment_offset)
609        blk_queue_alignment_offset(q, blk_size * alignment_offset);
610
611    err = virtio_config_val(vdev, VIRTIO_BLK_F_TOPOLOGY,
612            offsetof(struct virtio_blk_config, min_io_size),
613            &min_io_size);
614    if (!err && min_io_size)
615        blk_queue_io_min(q, blk_size * min_io_size);
616
617    err = virtio_config_val(vdev, VIRTIO_BLK_F_TOPOLOGY,
618            offsetof(struct virtio_blk_config, opt_io_size),
619            &opt_io_size);
620    if (!err && opt_io_size)
621        blk_queue_io_opt(q, blk_size * opt_io_size);
622
623
624    add_disk(vblk->disk);
625    err = device_create_file(disk_to_dev(vblk->disk), &dev_attr_serial);
626    if (err)
627        goto out_del_disk;
628
629    if (virtio_has_feature(vdev, VIRTIO_BLK_F_CONFIG_WCE))
630        err = device_create_file(disk_to_dev(vblk->disk),
631                     &dev_attr_cache_type_rw);
632    else
633        err = device_create_file(disk_to_dev(vblk->disk),
634                     &dev_attr_cache_type_ro);
635    if (err)
636        goto out_del_disk;
637    return 0;
638
639out_del_disk:
640    del_gendisk(vblk->disk);
641    blk_cleanup_queue(vblk->disk->queue);
642out_put_disk:
643    put_disk(vblk->disk);
644out_mempool:
645    mempool_destroy(vblk->pool);
646out_free_vq:
647    vdev->config->del_vqs(vdev);
648out_free_vblk:
649    kfree(vblk);
650out_free_index:
651    ida_simple_remove(&vd_index_ida, index);
652out:
653    return err;
654}
655
656static void __devexit virtblk_remove(struct virtio_device *vdev)
657{
658    struct virtio_blk *vblk = vdev->priv;
659    int index = vblk->index;
660
661    /* Prevent config work handler from accessing the device. */
662    mutex_lock(&vblk->config_lock);
663    vblk->config_enable = false;
664    mutex_unlock(&vblk->config_lock);
665
666    del_gendisk(vblk->disk);
667    blk_cleanup_queue(vblk->disk->queue);
668
669    /* Stop all the virtqueues. */
670    vdev->config->reset(vdev);
671
672    flush_work(&vblk->config_work);
673
674    put_disk(vblk->disk);
675    mempool_destroy(vblk->pool);
676    vdev->config->del_vqs(vdev);
677    kfree(vblk);
678    ida_simple_remove(&vd_index_ida, index);
679}
680
681#ifdef CONFIG_PM
682static int virtblk_freeze(struct virtio_device *vdev)
683{
684    struct virtio_blk *vblk = vdev->priv;
685
686    /* Ensure we don't receive any more interrupts */
687    vdev->config->reset(vdev);
688
689    /* Prevent config work handler from accessing the device. */
690    mutex_lock(&vblk->config_lock);
691    vblk->config_enable = false;
692    mutex_unlock(&vblk->config_lock);
693
694    flush_work(&vblk->config_work);
695
696    spin_lock_irq(vblk->disk->queue->queue_lock);
697    blk_stop_queue(vblk->disk->queue);
698    spin_unlock_irq(vblk->disk->queue->queue_lock);
699    blk_sync_queue(vblk->disk->queue);
700
701    vdev->config->del_vqs(vdev);
702    return 0;
703}
704
705static int virtblk_restore(struct virtio_device *vdev)
706{
707    struct virtio_blk *vblk = vdev->priv;
708    int ret;
709
710    vblk->config_enable = true;
711    ret = init_vq(vdev->priv);
712    if (!ret) {
713        spin_lock_irq(vblk->disk->queue->queue_lock);
714        blk_start_queue(vblk->disk->queue);
715        spin_unlock_irq(vblk->disk->queue->queue_lock);
716    }
717    return ret;
718}
719#endif
720
721static const struct virtio_device_id id_table[] = {
722    { VIRTIO_ID_BLOCK, VIRTIO_DEV_ANY_ID },
723    { 0 },
724};
725
726static unsigned int features[] = {
727    VIRTIO_BLK_F_SEG_MAX, VIRTIO_BLK_F_SIZE_MAX, VIRTIO_BLK_F_GEOMETRY,
728    VIRTIO_BLK_F_RO, VIRTIO_BLK_F_BLK_SIZE, VIRTIO_BLK_F_SCSI,
729    VIRTIO_BLK_F_WCE, VIRTIO_BLK_F_TOPOLOGY, VIRTIO_BLK_F_CONFIG_WCE
730};
731
732/*
733 * virtio_blk causes spurious section mismatch warning by
734 * simultaneously referring to a __devinit and a __devexit function.
735 * Use __refdata to avoid this warning.
736 */
737static struct virtio_driver __refdata virtio_blk = {
738    .feature_table = features,
739    .feature_table_size = ARRAY_SIZE(features),
740    .driver.name = KBUILD_MODNAME,
741    .driver.owner = THIS_MODULE,
742    .id_table = id_table,
743    .probe = virtblk_probe,
744    .remove = __devexit_p(virtblk_remove),
745    .config_changed = virtblk_config_changed,
746#ifdef CONFIG_PM
747    .freeze = virtblk_freeze,
748    .restore = virtblk_restore,
749#endif
750};
751
752static int __init init(void)
753{
754    int error;
755
756    virtblk_wq = alloc_workqueue("virtio-blk", 0, 0);
757    if (!virtblk_wq)
758        return -ENOMEM;
759
760    major = register_blkdev(0, "virtblk");
761    if (major < 0) {
762        error = major;
763        goto out_destroy_workqueue;
764    }
765
766    error = register_virtio_driver(&virtio_blk);
767    if (error)
768        goto out_unregister_blkdev;
769    return 0;
770
771out_unregister_blkdev:
772    unregister_blkdev(major, "virtblk");
773out_destroy_workqueue:
774    destroy_workqueue(virtblk_wq);
775    return error;
776}
777
778static void __exit fini(void)
779{
780    unregister_blkdev(major, "virtblk");
781    unregister_virtio_driver(&virtio_blk);
782    destroy_workqueue(virtblk_wq);
783}
784module_init(init);
785module_exit(fini);
786
787MODULE_DEVICE_TABLE(virtio, id_table);
788MODULE_DESCRIPTION("Virtio block driver");
789MODULE_LICENSE("GPL");
790

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