Version:  2.0.40 2.2.26 2.4.37 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 3.10 3.11 3.12 3.13 3.14 3.15 3.16 3.17 3.18

Linux/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 #include <linux/blk-mq.h>
 15 #include <linux/numa.h>
 16 
 17 #define PART_BITS 4
 18 #define VQ_NAME_LEN 16
 19 
 20 static int major;
 21 static DEFINE_IDA(vd_index_ida);
 22 
 23 static struct workqueue_struct *virtblk_wq;
 24 
 25 struct virtio_blk_vq {
 26         struct virtqueue *vq;
 27         spinlock_t lock;
 28         char name[VQ_NAME_LEN];
 29 } ____cacheline_aligned_in_smp;
 30 
 31 struct virtio_blk
 32 {
 33         struct virtio_device *vdev;
 34 
 35         /* The disk structure for the kernel. */
 36         struct gendisk *disk;
 37 
 38         /* Block layer tags. */
 39         struct blk_mq_tag_set tag_set;
 40 
 41         /* Process context for config space updates */
 42         struct work_struct config_work;
 43 
 44         /* What host tells us, plus 2 for header & tailer. */
 45         unsigned int sg_elems;
 46 
 47         /* Ida index - used to track minor number allocations. */
 48         int index;
 49 
 50         /* num of vqs */
 51         int num_vqs;
 52         struct virtio_blk_vq *vqs;
 53 };
 54 
 55 struct virtblk_req
 56 {
 57         struct request *req;
 58         struct virtio_blk_outhdr out_hdr;
 59         struct virtio_scsi_inhdr in_hdr;
 60         u8 status;
 61         struct scatterlist sg[];
 62 };
 63 
 64 static inline int virtblk_result(struct virtblk_req *vbr)
 65 {
 66         switch (vbr->status) {
 67         case VIRTIO_BLK_S_OK:
 68                 return 0;
 69         case VIRTIO_BLK_S_UNSUPP:
 70                 return -ENOTTY;
 71         default:
 72                 return -EIO;
 73         }
 74 }
 75 
 76 static int __virtblk_add_req(struct virtqueue *vq,
 77                              struct virtblk_req *vbr,
 78                              struct scatterlist *data_sg,
 79                              bool have_data)
 80 {
 81         struct scatterlist hdr, status, cmd, sense, inhdr, *sgs[6];
 82         unsigned int num_out = 0, num_in = 0;
 83         int type = vbr->out_hdr.type & ~VIRTIO_BLK_T_OUT;
 84 
 85         sg_init_one(&hdr, &vbr->out_hdr, sizeof(vbr->out_hdr));
 86         sgs[num_out++] = &hdr;
 87 
 88         /*
 89          * If this is a packet command we need a couple of additional headers.
 90          * Behind the normal outhdr we put a segment with the scsi command
 91          * block, and before the normal inhdr we put the sense data and the
 92          * inhdr with additional status information.
 93          */
 94         if (type == VIRTIO_BLK_T_SCSI_CMD) {
 95                 sg_init_one(&cmd, vbr->req->cmd, vbr->req->cmd_len);
 96                 sgs[num_out++] = &cmd;
 97         }
 98 
 99         if (have_data) {
100                 if (vbr->out_hdr.type & VIRTIO_BLK_T_OUT)
101                         sgs[num_out++] = data_sg;
102                 else
103                         sgs[num_out + num_in++] = data_sg;
104         }
105 
106         if (type == VIRTIO_BLK_T_SCSI_CMD) {
107                 sg_init_one(&sense, vbr->req->sense, SCSI_SENSE_BUFFERSIZE);
108                 sgs[num_out + num_in++] = &sense;
109                 sg_init_one(&inhdr, &vbr->in_hdr, sizeof(vbr->in_hdr));
110                 sgs[num_out + num_in++] = &inhdr;
111         }
112 
113         sg_init_one(&status, &vbr->status, sizeof(vbr->status));
114         sgs[num_out + num_in++] = &status;
115 
116         return virtqueue_add_sgs(vq, sgs, num_out, num_in, vbr, GFP_ATOMIC);
117 }
118 
119 static inline void virtblk_request_done(struct request *req)
120 {
121         struct virtblk_req *vbr = blk_mq_rq_to_pdu(req);
122         int error = virtblk_result(vbr);
123 
124         if (req->cmd_type == REQ_TYPE_BLOCK_PC) {
125                 req->resid_len = vbr->in_hdr.residual;
126                 req->sense_len = vbr->in_hdr.sense_len;
127                 req->errors = vbr->in_hdr.errors;
128         } else if (req->cmd_type == REQ_TYPE_SPECIAL) {
129                 req->errors = (error != 0);
130         }
131 
132         blk_mq_end_request(req, error);
133 }
134 
135 static void virtblk_done(struct virtqueue *vq)
136 {
137         struct virtio_blk *vblk = vq->vdev->priv;
138         bool req_done = false;
139         int qid = vq->index;
140         struct virtblk_req *vbr;
141         unsigned long flags;
142         unsigned int len;
143 
144         spin_lock_irqsave(&vblk->vqs[qid].lock, flags);
145         do {
146                 virtqueue_disable_cb(vq);
147                 while ((vbr = virtqueue_get_buf(vblk->vqs[qid].vq, &len)) != NULL) {
148                         blk_mq_complete_request(vbr->req);
149                         req_done = true;
150                 }
151                 if (unlikely(virtqueue_is_broken(vq)))
152                         break;
153         } while (!virtqueue_enable_cb(vq));
154 
155         /* In case queue is stopped waiting for more buffers. */
156         if (req_done)
157                 blk_mq_start_stopped_hw_queues(vblk->disk->queue, true);
158         spin_unlock_irqrestore(&vblk->vqs[qid].lock, flags);
159 }
160 
161 static int virtio_queue_rq(struct blk_mq_hw_ctx *hctx, struct request *req,
162                 bool last)
163 {
164         struct virtio_blk *vblk = hctx->queue->queuedata;
165         struct virtblk_req *vbr = blk_mq_rq_to_pdu(req);
166         unsigned long flags;
167         unsigned int num;
168         int qid = hctx->queue_num;
169         int err;
170         bool notify = false;
171 
172         BUG_ON(req->nr_phys_segments + 2 > vblk->sg_elems);
173 
174         vbr->req = req;
175         if (req->cmd_flags & REQ_FLUSH) {
176                 vbr->out_hdr.type = VIRTIO_BLK_T_FLUSH;
177                 vbr->out_hdr.sector = 0;
178                 vbr->out_hdr.ioprio = req_get_ioprio(vbr->req);
179         } else {
180                 switch (req->cmd_type) {
181                 case REQ_TYPE_FS:
182                         vbr->out_hdr.type = 0;
183                         vbr->out_hdr.sector = blk_rq_pos(vbr->req);
184                         vbr->out_hdr.ioprio = req_get_ioprio(vbr->req);
185                         break;
186                 case REQ_TYPE_BLOCK_PC:
187                         vbr->out_hdr.type = VIRTIO_BLK_T_SCSI_CMD;
188                         vbr->out_hdr.sector = 0;
189                         vbr->out_hdr.ioprio = req_get_ioprio(vbr->req);
190                         break;
191                 case REQ_TYPE_SPECIAL:
192                         vbr->out_hdr.type = VIRTIO_BLK_T_GET_ID;
193                         vbr->out_hdr.sector = 0;
194                         vbr->out_hdr.ioprio = req_get_ioprio(vbr->req);
195                         break;
196                 default:
197                         /* We don't put anything else in the queue. */
198                         BUG();
199                 }
200         }
201 
202         blk_mq_start_request(req);
203 
204         num = blk_rq_map_sg(hctx->queue, vbr->req, vbr->sg);
205         if (num) {
206                 if (rq_data_dir(vbr->req) == WRITE)
207                         vbr->out_hdr.type |= VIRTIO_BLK_T_OUT;
208                 else
209                         vbr->out_hdr.type |= VIRTIO_BLK_T_IN;
210         }
211 
212         spin_lock_irqsave(&vblk->vqs[qid].lock, flags);
213         err = __virtblk_add_req(vblk->vqs[qid].vq, vbr, vbr->sg, num);
214         if (err) {
215                 virtqueue_kick(vblk->vqs[qid].vq);
216                 blk_mq_stop_hw_queue(hctx);
217                 spin_unlock_irqrestore(&vblk->vqs[qid].lock, flags);
218                 /* Out of mem doesn't actually happen, since we fall back
219                  * to direct descriptors */
220                 if (err == -ENOMEM || err == -ENOSPC)
221                         return BLK_MQ_RQ_QUEUE_BUSY;
222                 return BLK_MQ_RQ_QUEUE_ERROR;
223         }
224 
225         if (last && virtqueue_kick_prepare(vblk->vqs[qid].vq))
226                 notify = true;
227         spin_unlock_irqrestore(&vblk->vqs[qid].lock, flags);
228 
229         if (notify)
230                 virtqueue_notify(vblk->vqs[qid].vq);
231         return BLK_MQ_RQ_QUEUE_OK;
232 }
233 
234 /* return id (s/n) string for *disk to *id_str
235  */
236 static int virtblk_get_id(struct gendisk *disk, char *id_str)
237 {
238         struct virtio_blk *vblk = disk->private_data;
239         struct request *req;
240         struct bio *bio;
241         int err;
242 
243         bio = bio_map_kern(vblk->disk->queue, id_str, VIRTIO_BLK_ID_BYTES,
244                            GFP_KERNEL);
245         if (IS_ERR(bio))
246                 return PTR_ERR(bio);
247 
248         req = blk_make_request(vblk->disk->queue, bio, GFP_KERNEL);
249         if (IS_ERR(req)) {
250                 bio_put(bio);
251                 return PTR_ERR(req);
252         }
253 
254         req->cmd_type = REQ_TYPE_SPECIAL;
255         err = blk_execute_rq(vblk->disk->queue, vblk->disk, req, false);
256         blk_put_request(req);
257 
258         return err;
259 }
260 
261 static int virtblk_ioctl(struct block_device *bdev, fmode_t mode,
262                              unsigned int cmd, unsigned long data)
263 {
264         struct gendisk *disk = bdev->bd_disk;
265         struct virtio_blk *vblk = disk->private_data;
266 
267         /*
268          * Only allow the generic SCSI ioctls if the host can support it.
269          */
270         if (!virtio_has_feature(vblk->vdev, VIRTIO_BLK_F_SCSI))
271                 return -ENOTTY;
272 
273         return scsi_cmd_blk_ioctl(bdev, mode, cmd,
274                                   (void __user *)data);
275 }
276 
277 /* We provide getgeo only to please some old bootloader/partitioning tools */
278 static int virtblk_getgeo(struct block_device *bd, struct hd_geometry *geo)
279 {
280         struct virtio_blk *vblk = bd->bd_disk->private_data;
281 
282         /* see if the host passed in geometry config */
283         if (virtio_has_feature(vblk->vdev, VIRTIO_BLK_F_GEOMETRY)) {
284                 virtio_cread(vblk->vdev, struct virtio_blk_config,
285                              geometry.cylinders, &geo->cylinders);
286                 virtio_cread(vblk->vdev, struct virtio_blk_config,
287                              geometry.heads, &geo->heads);
288                 virtio_cread(vblk->vdev, struct virtio_blk_config,
289                              geometry.sectors, &geo->sectors);
290         } else {
291                 /* some standard values, similar to sd */
292                 geo->heads = 1 << 6;
293                 geo->sectors = 1 << 5;
294                 geo->cylinders = get_capacity(bd->bd_disk) >> 11;
295         }
296         return 0;
297 }
298 
299 static const struct block_device_operations virtblk_fops = {
300         .ioctl  = virtblk_ioctl,
301         .owner  = THIS_MODULE,
302         .getgeo = virtblk_getgeo,
303 };
304 
305 static int index_to_minor(int index)
306 {
307         return index << PART_BITS;
308 }
309 
310 static int minor_to_index(int minor)
311 {
312         return minor >> PART_BITS;
313 }
314 
315 static ssize_t virtblk_serial_show(struct device *dev,
316                                 struct device_attribute *attr, char *buf)
317 {
318         struct gendisk *disk = dev_to_disk(dev);
319         int err;
320 
321         /* sysfs gives us a PAGE_SIZE buffer */
322         BUILD_BUG_ON(PAGE_SIZE < VIRTIO_BLK_ID_BYTES);
323 
324         buf[VIRTIO_BLK_ID_BYTES] = '\0';
325         err = virtblk_get_id(disk, buf);
326         if (!err)
327                 return strlen(buf);
328 
329         if (err == -EIO) /* Unsupported? Make it empty. */
330                 return 0;
331 
332         return err;
333 }
334 DEVICE_ATTR(serial, S_IRUGO, virtblk_serial_show, NULL);
335 
336 static void virtblk_config_changed_work(struct work_struct *work)
337 {
338         struct virtio_blk *vblk =
339                 container_of(work, struct virtio_blk, config_work);
340         struct virtio_device *vdev = vblk->vdev;
341         struct request_queue *q = vblk->disk->queue;
342         char cap_str_2[10], cap_str_10[10];
343         char *envp[] = { "RESIZE=1", NULL };
344         u64 capacity, size;
345 
346         /* Host must always specify the capacity. */
347         virtio_cread(vdev, struct virtio_blk_config, capacity, &capacity);
348 
349         /* If capacity is too big, truncate with warning. */
350         if ((sector_t)capacity != capacity) {
351                 dev_warn(&vdev->dev, "Capacity %llu too large: truncating\n",
352                          (unsigned long long)capacity);
353                 capacity = (sector_t)-1;
354         }
355 
356         size = capacity * queue_logical_block_size(q);
357         string_get_size(size, STRING_UNITS_2, cap_str_2, sizeof(cap_str_2));
358         string_get_size(size, STRING_UNITS_10, cap_str_10, sizeof(cap_str_10));
359 
360         dev_notice(&vdev->dev,
361                   "new size: %llu %d-byte logical blocks (%s/%s)\n",
362                   (unsigned long long)capacity,
363                   queue_logical_block_size(q),
364                   cap_str_10, cap_str_2);
365 
366         set_capacity(vblk->disk, capacity);
367         revalidate_disk(vblk->disk);
368         kobject_uevent_env(&disk_to_dev(vblk->disk)->kobj, KOBJ_CHANGE, envp);
369 }
370 
371 static void virtblk_config_changed(struct virtio_device *vdev)
372 {
373         struct virtio_blk *vblk = vdev->priv;
374 
375         queue_work(virtblk_wq, &vblk->config_work);
376 }
377 
378 static int init_vq(struct virtio_blk *vblk)
379 {
380         int err = 0;
381         int i;
382         vq_callback_t **callbacks;
383         const char **names;
384         struct virtqueue **vqs;
385         unsigned short num_vqs;
386         struct virtio_device *vdev = vblk->vdev;
387 
388         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_MQ,
389                                    struct virtio_blk_config, num_queues,
390                                    &num_vqs);
391         if (err)
392                 num_vqs = 1;
393 
394         vblk->vqs = kmalloc(sizeof(*vblk->vqs) * num_vqs, GFP_KERNEL);
395         if (!vblk->vqs) {
396                 err = -ENOMEM;
397                 goto out;
398         }
399 
400         names = kmalloc(sizeof(*names) * num_vqs, GFP_KERNEL);
401         if (!names)
402                 goto err_names;
403 
404         callbacks = kmalloc(sizeof(*callbacks) * num_vqs, GFP_KERNEL);
405         if (!callbacks)
406                 goto err_callbacks;
407 
408         vqs = kmalloc(sizeof(*vqs) * num_vqs, GFP_KERNEL);
409         if (!vqs)
410                 goto err_vqs;
411 
412         for (i = 0; i < num_vqs; i++) {
413                 callbacks[i] = virtblk_done;
414                 snprintf(vblk->vqs[i].name, VQ_NAME_LEN, "req.%d", i);
415                 names[i] = vblk->vqs[i].name;
416         }
417 
418         /* Discover virtqueues and write information to configuration.  */
419         err = vdev->config->find_vqs(vdev, num_vqs, vqs, callbacks, names);
420         if (err)
421                 goto err_find_vqs;
422 
423         for (i = 0; i < num_vqs; i++) {
424                 spin_lock_init(&vblk->vqs[i].lock);
425                 vblk->vqs[i].vq = vqs[i];
426         }
427         vblk->num_vqs = num_vqs;
428 
429  err_find_vqs:
430         kfree(vqs);
431  err_vqs:
432         kfree(callbacks);
433  err_callbacks:
434         kfree(names);
435  err_names:
436         if (err)
437                 kfree(vblk->vqs);
438  out:
439         return err;
440 }
441 
442 /*
443  * Legacy naming scheme used for virtio devices.  We are stuck with it for
444  * virtio blk but don't ever use it for any new driver.
445  */
446 static int virtblk_name_format(char *prefix, int index, char *buf, int buflen)
447 {
448         const int base = 'z' - 'a' + 1;
449         char *begin = buf + strlen(prefix);
450         char *end = buf + buflen;
451         char *p;
452         int unit;
453 
454         p = end - 1;
455         *p = '\0';
456         unit = base;
457         do {
458                 if (p == begin)
459                         return -EINVAL;
460                 *--p = 'a' + (index % unit);
461                 index = (index / unit) - 1;
462         } while (index >= 0);
463 
464         memmove(begin, p, end - p);
465         memcpy(buf, prefix, strlen(prefix));
466 
467         return 0;
468 }
469 
470 static int virtblk_get_cache_mode(struct virtio_device *vdev)
471 {
472         u8 writeback;
473         int err;
474 
475         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_CONFIG_WCE,
476                                    struct virtio_blk_config, wce,
477                                    &writeback);
478         if (err)
479                 writeback = virtio_has_feature(vdev, VIRTIO_BLK_F_WCE);
480 
481         return writeback;
482 }
483 
484 static void virtblk_update_cache_mode(struct virtio_device *vdev)
485 {
486         u8 writeback = virtblk_get_cache_mode(vdev);
487         struct virtio_blk *vblk = vdev->priv;
488 
489         if (writeback)
490                 blk_queue_flush(vblk->disk->queue, REQ_FLUSH);
491         else
492                 blk_queue_flush(vblk->disk->queue, 0);
493 
494         revalidate_disk(vblk->disk);
495 }
496 
497 static const char *const virtblk_cache_types[] = {
498         "write through", "write back"
499 };
500 
501 static ssize_t
502 virtblk_cache_type_store(struct device *dev, struct device_attribute *attr,
503                          const char *buf, size_t count)
504 {
505         struct gendisk *disk = dev_to_disk(dev);
506         struct virtio_blk *vblk = disk->private_data;
507         struct virtio_device *vdev = vblk->vdev;
508         int i;
509 
510         BUG_ON(!virtio_has_feature(vblk->vdev, VIRTIO_BLK_F_CONFIG_WCE));
511         for (i = ARRAY_SIZE(virtblk_cache_types); --i >= 0; )
512                 if (sysfs_streq(buf, virtblk_cache_types[i]))
513                         break;
514 
515         if (i < 0)
516                 return -EINVAL;
517 
518         virtio_cwrite8(vdev, offsetof(struct virtio_blk_config, wce), i);
519         virtblk_update_cache_mode(vdev);
520         return count;
521 }
522 
523 static ssize_t
524 virtblk_cache_type_show(struct device *dev, struct device_attribute *attr,
525                          char *buf)
526 {
527         struct gendisk *disk = dev_to_disk(dev);
528         struct virtio_blk *vblk = disk->private_data;
529         u8 writeback = virtblk_get_cache_mode(vblk->vdev);
530 
531         BUG_ON(writeback >= ARRAY_SIZE(virtblk_cache_types));
532         return snprintf(buf, 40, "%s\n", virtblk_cache_types[writeback]);
533 }
534 
535 static const struct device_attribute dev_attr_cache_type_ro =
536         __ATTR(cache_type, S_IRUGO,
537                virtblk_cache_type_show, NULL);
538 static const struct device_attribute dev_attr_cache_type_rw =
539         __ATTR(cache_type, S_IRUGO|S_IWUSR,
540                virtblk_cache_type_show, virtblk_cache_type_store);
541 
542 static int virtblk_init_request(void *data, struct request *rq,
543                 unsigned int hctx_idx, unsigned int request_idx,
544                 unsigned int numa_node)
545 {
546         struct virtio_blk *vblk = data;
547         struct virtblk_req *vbr = blk_mq_rq_to_pdu(rq);
548 
549         sg_init_table(vbr->sg, vblk->sg_elems);
550         return 0;
551 }
552 
553 static struct blk_mq_ops virtio_mq_ops = {
554         .queue_rq       = virtio_queue_rq,
555         .map_queue      = blk_mq_map_queue,
556         .complete       = virtblk_request_done,
557         .init_request   = virtblk_init_request,
558 };
559 
560 static unsigned int virtblk_queue_depth;
561 module_param_named(queue_depth, virtblk_queue_depth, uint, 0444);
562 
563 static int virtblk_probe(struct virtio_device *vdev)
564 {
565         struct virtio_blk *vblk;
566         struct request_queue *q;
567         int err, index;
568 
569         u64 cap;
570         u32 v, blk_size, sg_elems, opt_io_size;
571         u16 min_io_size;
572         u8 physical_block_exp, alignment_offset;
573 
574         err = ida_simple_get(&vd_index_ida, 0, minor_to_index(1 << MINORBITS),
575                              GFP_KERNEL);
576         if (err < 0)
577                 goto out;
578         index = err;
579 
580         /* We need to know how many segments before we allocate. */
581         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_SEG_MAX,
582                                    struct virtio_blk_config, seg_max,
583                                    &sg_elems);
584 
585         /* We need at least one SG element, whatever they say. */
586         if (err || !sg_elems)
587                 sg_elems = 1;
588 
589         /* We need an extra sg elements at head and tail. */
590         sg_elems += 2;
591         vdev->priv = vblk = kmalloc(sizeof(*vblk), GFP_KERNEL);
592         if (!vblk) {
593                 err = -ENOMEM;
594                 goto out_free_index;
595         }
596 
597         vblk->vdev = vdev;
598         vblk->sg_elems = sg_elems;
599 
600         INIT_WORK(&vblk->config_work, virtblk_config_changed_work);
601 
602         err = init_vq(vblk);
603         if (err)
604                 goto out_free_vblk;
605 
606         /* FIXME: How many partitions?  How long is a piece of string? */
607         vblk->disk = alloc_disk(1 << PART_BITS);
608         if (!vblk->disk) {
609                 err = -ENOMEM;
610                 goto out_free_vq;
611         }
612 
613         /* Default queue sizing is to fill the ring. */
614         if (!virtblk_queue_depth) {
615                 virtblk_queue_depth = vblk->vqs[0].vq->num_free;
616                 /* ... but without indirect descs, we use 2 descs per req */
617                 if (!virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC))
618                         virtblk_queue_depth /= 2;
619         }
620 
621         memset(&vblk->tag_set, 0, sizeof(vblk->tag_set));
622         vblk->tag_set.ops = &virtio_mq_ops;
623         vblk->tag_set.queue_depth = virtblk_queue_depth;
624         vblk->tag_set.numa_node = NUMA_NO_NODE;
625         vblk->tag_set.flags = BLK_MQ_F_SHOULD_MERGE;
626         vblk->tag_set.cmd_size =
627                 sizeof(struct virtblk_req) +
628                 sizeof(struct scatterlist) * sg_elems;
629         vblk->tag_set.driver_data = vblk;
630         vblk->tag_set.nr_hw_queues = vblk->num_vqs;
631 
632         err = blk_mq_alloc_tag_set(&vblk->tag_set);
633         if (err)
634                 goto out_put_disk;
635 
636         q = vblk->disk->queue = blk_mq_init_queue(&vblk->tag_set);
637         if (!q) {
638                 err = -ENOMEM;
639                 goto out_free_tags;
640         }
641 
642         q->queuedata = vblk;
643 
644         virtblk_name_format("vd", index, vblk->disk->disk_name, DISK_NAME_LEN);
645 
646         vblk->disk->major = major;
647         vblk->disk->first_minor = index_to_minor(index);
648         vblk->disk->private_data = vblk;
649         vblk->disk->fops = &virtblk_fops;
650         vblk->disk->driverfs_dev = &vdev->dev;
651         vblk->index = index;
652 
653         /* configure queue flush support */
654         virtblk_update_cache_mode(vdev);
655 
656         /* If disk is read-only in the host, the guest should obey */
657         if (virtio_has_feature(vdev, VIRTIO_BLK_F_RO))
658                 set_disk_ro(vblk->disk, 1);
659 
660         /* Host must always specify the capacity. */
661         virtio_cread(vdev, struct virtio_blk_config, capacity, &cap);
662 
663         /* If capacity is too big, truncate with warning. */
664         if ((sector_t)cap != cap) {
665                 dev_warn(&vdev->dev, "Capacity %llu too large: truncating\n",
666                          (unsigned long long)cap);
667                 cap = (sector_t)-1;
668         }
669         set_capacity(vblk->disk, cap);
670 
671         /* We can handle whatever the host told us to handle. */
672         blk_queue_max_segments(q, vblk->sg_elems-2);
673 
674         /* No need to bounce any requests */
675         blk_queue_bounce_limit(q, BLK_BOUNCE_ANY);
676 
677         /* No real sector limit. */
678         blk_queue_max_hw_sectors(q, -1U);
679 
680         /* Host can optionally specify maximum segment size and number of
681          * segments. */
682         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_SIZE_MAX,
683                                    struct virtio_blk_config, size_max, &v);
684         if (!err)
685                 blk_queue_max_segment_size(q, v);
686         else
687                 blk_queue_max_segment_size(q, -1U);
688 
689         /* Host can optionally specify the block size of the device */
690         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_BLK_SIZE,
691                                    struct virtio_blk_config, blk_size,
692                                    &blk_size);
693         if (!err)
694                 blk_queue_logical_block_size(q, blk_size);
695         else
696                 blk_size = queue_logical_block_size(q);
697 
698         /* Use topology information if available */
699         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_TOPOLOGY,
700                                    struct virtio_blk_config, physical_block_exp,
701                                    &physical_block_exp);
702         if (!err && physical_block_exp)
703                 blk_queue_physical_block_size(q,
704                                 blk_size * (1 << physical_block_exp));
705 
706         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_TOPOLOGY,
707                                    struct virtio_blk_config, alignment_offset,
708                                    &alignment_offset);
709         if (!err && alignment_offset)
710                 blk_queue_alignment_offset(q, blk_size * alignment_offset);
711 
712         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_TOPOLOGY,
713                                    struct virtio_blk_config, min_io_size,
714                                    &min_io_size);
715         if (!err && min_io_size)
716                 blk_queue_io_min(q, blk_size * min_io_size);
717 
718         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_TOPOLOGY,
719                                    struct virtio_blk_config, opt_io_size,
720                                    &opt_io_size);
721         if (!err && opt_io_size)
722                 blk_queue_io_opt(q, blk_size * opt_io_size);
723 
724         virtio_device_ready(vdev);
725 
726         add_disk(vblk->disk);
727         err = device_create_file(disk_to_dev(vblk->disk), &dev_attr_serial);
728         if (err)
729                 goto out_del_disk;
730 
731         if (virtio_has_feature(vdev, VIRTIO_BLK_F_CONFIG_WCE))
732                 err = device_create_file(disk_to_dev(vblk->disk),
733                                          &dev_attr_cache_type_rw);
734         else
735                 err = device_create_file(disk_to_dev(vblk->disk),
736                                          &dev_attr_cache_type_ro);
737         if (err)
738                 goto out_del_disk;
739         return 0;
740 
741 out_del_disk:
742         del_gendisk(vblk->disk);
743         blk_cleanup_queue(vblk->disk->queue);
744 out_free_tags:
745         blk_mq_free_tag_set(&vblk->tag_set);
746 out_put_disk:
747         put_disk(vblk->disk);
748 out_free_vq:
749         vdev->config->del_vqs(vdev);
750 out_free_vblk:
751         kfree(vblk);
752 out_free_index:
753         ida_simple_remove(&vd_index_ida, index);
754 out:
755         return err;
756 }
757 
758 static void virtblk_remove(struct virtio_device *vdev)
759 {
760         struct virtio_blk *vblk = vdev->priv;
761         int index = vblk->index;
762         int refc;
763 
764         /* Make sure no work handler is accessing the device. */
765         flush_work(&vblk->config_work);
766 
767         del_gendisk(vblk->disk);
768         blk_cleanup_queue(vblk->disk->queue);
769 
770         blk_mq_free_tag_set(&vblk->tag_set);
771 
772         /* Stop all the virtqueues. */
773         vdev->config->reset(vdev);
774 
775         refc = atomic_read(&disk_to_dev(vblk->disk)->kobj.kref.refcount);
776         put_disk(vblk->disk);
777         vdev->config->del_vqs(vdev);
778         kfree(vblk->vqs);
779         kfree(vblk);
780 
781         /* Only free device id if we don't have any users */
782         if (refc == 1)
783                 ida_simple_remove(&vd_index_ida, index);
784 }
785 
786 #ifdef CONFIG_PM_SLEEP
787 static int virtblk_freeze(struct virtio_device *vdev)
788 {
789         struct virtio_blk *vblk = vdev->priv;
790 
791         /* Ensure we don't receive any more interrupts */
792         vdev->config->reset(vdev);
793 
794         /* Make sure no work handler is accessing the device. */
795         flush_work(&vblk->config_work);
796 
797         blk_mq_stop_hw_queues(vblk->disk->queue);
798 
799         vdev->config->del_vqs(vdev);
800         return 0;
801 }
802 
803 static int virtblk_restore(struct virtio_device *vdev)
804 {
805         struct virtio_blk *vblk = vdev->priv;
806         int ret;
807 
808         ret = init_vq(vdev->priv);
809         if (ret)
810                 return ret;
811 
812         virtio_device_ready(vdev);
813 
814         blk_mq_start_stopped_hw_queues(vblk->disk->queue, true);
815         return 0;
816 }
817 #endif
818 
819 static const struct virtio_device_id id_table[] = {
820         { VIRTIO_ID_BLOCK, VIRTIO_DEV_ANY_ID },
821         { 0 },
822 };
823 
824 static unsigned int features[] = {
825         VIRTIO_BLK_F_SEG_MAX, VIRTIO_BLK_F_SIZE_MAX, VIRTIO_BLK_F_GEOMETRY,
826         VIRTIO_BLK_F_RO, VIRTIO_BLK_F_BLK_SIZE, VIRTIO_BLK_F_SCSI,
827         VIRTIO_BLK_F_WCE, VIRTIO_BLK_F_TOPOLOGY, VIRTIO_BLK_F_CONFIG_WCE,
828         VIRTIO_BLK_F_MQ,
829 };
830 
831 static struct virtio_driver virtio_blk = {
832         .feature_table          = features,
833         .feature_table_size     = ARRAY_SIZE(features),
834         .driver.name            = KBUILD_MODNAME,
835         .driver.owner           = THIS_MODULE,
836         .id_table               = id_table,
837         .probe                  = virtblk_probe,
838         .remove                 = virtblk_remove,
839         .config_changed         = virtblk_config_changed,
840 #ifdef CONFIG_PM_SLEEP
841         .freeze                 = virtblk_freeze,
842         .restore                = virtblk_restore,
843 #endif
844 };
845 
846 static int __init init(void)
847 {
848         int error;
849 
850         virtblk_wq = alloc_workqueue("virtio-blk", 0, 0);
851         if (!virtblk_wq)
852                 return -ENOMEM;
853 
854         major = register_blkdev(0, "virtblk");
855         if (major < 0) {
856                 error = major;
857                 goto out_destroy_workqueue;
858         }
859 
860         error = register_virtio_driver(&virtio_blk);
861         if (error)
862                 goto out_unregister_blkdev;
863         return 0;
864 
865 out_unregister_blkdev:
866         unregister_blkdev(major, "virtblk");
867 out_destroy_workqueue:
868         destroy_workqueue(virtblk_wq);
869         return error;
870 }
871 
872 static void __exit fini(void)
873 {
874         unregister_blkdev(major, "virtblk");
875         unregister_virtio_driver(&virtio_blk);
876         destroy_workqueue(virtblk_wq);
877 }
878 module_init(init);
879 module_exit(fini);
880 
881 MODULE_DEVICE_TABLE(virtio, id_table);
882 MODULE_DESCRIPTION("Virtio block driver");
883 MODULE_LICENSE("GPL");
884 

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