Version:  2.0.40 2.2.26 2.4.37 3.1 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

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         /* Lock for config space updates */
 45         struct mutex config_lock;
 46 
 47         /* enable config space updates */
 48         bool config_enable;
 49 
 50         /* What host tells us, plus 2 for header & tailer. */
 51         unsigned int sg_elems;
 52 
 53         /* Ida index - used to track minor number allocations. */
 54         int index;
 55 
 56         /* num of vqs */
 57         int num_vqs;
 58         struct virtio_blk_vq *vqs;
 59 };
 60 
 61 struct virtblk_req
 62 {
 63         struct request *req;
 64         struct virtio_blk_outhdr out_hdr;
 65         struct virtio_scsi_inhdr in_hdr;
 66         u8 status;
 67         struct scatterlist sg[];
 68 };
 69 
 70 static inline int virtblk_result(struct virtblk_req *vbr)
 71 {
 72         switch (vbr->status) {
 73         case VIRTIO_BLK_S_OK:
 74                 return 0;
 75         case VIRTIO_BLK_S_UNSUPP:
 76                 return -ENOTTY;
 77         default:
 78                 return -EIO;
 79         }
 80 }
 81 
 82 static int __virtblk_add_req(struct virtqueue *vq,
 83                              struct virtblk_req *vbr,
 84                              struct scatterlist *data_sg,
 85                              bool have_data)
 86 {
 87         struct scatterlist hdr, status, cmd, sense, inhdr, *sgs[6];
 88         unsigned int num_out = 0, num_in = 0;
 89         int type = vbr->out_hdr.type & ~VIRTIO_BLK_T_OUT;
 90 
 91         sg_init_one(&hdr, &vbr->out_hdr, sizeof(vbr->out_hdr));
 92         sgs[num_out++] = &hdr;
 93 
 94         /*
 95          * If this is a packet command we need a couple of additional headers.
 96          * Behind the normal outhdr we put a segment with the scsi command
 97          * block, and before the normal inhdr we put the sense data and the
 98          * inhdr with additional status information.
 99          */
100         if (type == VIRTIO_BLK_T_SCSI_CMD) {
101                 sg_init_one(&cmd, vbr->req->cmd, vbr->req->cmd_len);
102                 sgs[num_out++] = &cmd;
103         }
104 
105         if (have_data) {
106                 if (vbr->out_hdr.type & VIRTIO_BLK_T_OUT)
107                         sgs[num_out++] = data_sg;
108                 else
109                         sgs[num_out + num_in++] = data_sg;
110         }
111 
112         if (type == VIRTIO_BLK_T_SCSI_CMD) {
113                 sg_init_one(&sense, vbr->req->sense, SCSI_SENSE_BUFFERSIZE);
114                 sgs[num_out + num_in++] = &sense;
115                 sg_init_one(&inhdr, &vbr->in_hdr, sizeof(vbr->in_hdr));
116                 sgs[num_out + num_in++] = &inhdr;
117         }
118 
119         sg_init_one(&status, &vbr->status, sizeof(vbr->status));
120         sgs[num_out + num_in++] = &status;
121 
122         return virtqueue_add_sgs(vq, sgs, num_out, num_in, vbr, GFP_ATOMIC);
123 }
124 
125 static inline void virtblk_request_done(struct request *req)
126 {
127         struct virtblk_req *vbr = blk_mq_rq_to_pdu(req);
128         int error = virtblk_result(vbr);
129 
130         if (req->cmd_type == REQ_TYPE_BLOCK_PC) {
131                 req->resid_len = vbr->in_hdr.residual;
132                 req->sense_len = vbr->in_hdr.sense_len;
133                 req->errors = vbr->in_hdr.errors;
134         } else if (req->cmd_type == REQ_TYPE_SPECIAL) {
135                 req->errors = (error != 0);
136         }
137 
138         blk_mq_end_io(req, error);
139 }
140 
141 static void virtblk_done(struct virtqueue *vq)
142 {
143         struct virtio_blk *vblk = vq->vdev->priv;
144         bool req_done = false;
145         int qid = vq->index;
146         struct virtblk_req *vbr;
147         unsigned long flags;
148         unsigned int len;
149 
150         spin_lock_irqsave(&vblk->vqs[qid].lock, flags);
151         do {
152                 virtqueue_disable_cb(vq);
153                 while ((vbr = virtqueue_get_buf(vblk->vqs[qid].vq, &len)) != NULL) {
154                         blk_mq_complete_request(vbr->req);
155                         req_done = true;
156                 }
157                 if (unlikely(virtqueue_is_broken(vq)))
158                         break;
159         } while (!virtqueue_enable_cb(vq));
160 
161         /* In case queue is stopped waiting for more buffers. */
162         if (req_done)
163                 blk_mq_start_stopped_hw_queues(vblk->disk->queue, true);
164         spin_unlock_irqrestore(&vblk->vqs[qid].lock, flags);
165 }
166 
167 static int virtio_queue_rq(struct blk_mq_hw_ctx *hctx, struct request *req)
168 {
169         struct virtio_blk *vblk = hctx->queue->queuedata;
170         struct virtblk_req *vbr = blk_mq_rq_to_pdu(req);
171         unsigned long flags;
172         unsigned int num;
173         int qid = hctx->queue_num;
174         const bool last = (req->cmd_flags & REQ_END) != 0;
175         int err;
176         bool notify = false;
177 
178         BUG_ON(req->nr_phys_segments + 2 > vblk->sg_elems);
179 
180         vbr->req = req;
181         if (req->cmd_flags & REQ_FLUSH) {
182                 vbr->out_hdr.type = VIRTIO_BLK_T_FLUSH;
183                 vbr->out_hdr.sector = 0;
184                 vbr->out_hdr.ioprio = req_get_ioprio(vbr->req);
185         } else {
186                 switch (req->cmd_type) {
187                 case REQ_TYPE_FS:
188                         vbr->out_hdr.type = 0;
189                         vbr->out_hdr.sector = blk_rq_pos(vbr->req);
190                         vbr->out_hdr.ioprio = req_get_ioprio(vbr->req);
191                         break;
192                 case REQ_TYPE_BLOCK_PC:
193                         vbr->out_hdr.type = VIRTIO_BLK_T_SCSI_CMD;
194                         vbr->out_hdr.sector = 0;
195                         vbr->out_hdr.ioprio = req_get_ioprio(vbr->req);
196                         break;
197                 case REQ_TYPE_SPECIAL:
198                         vbr->out_hdr.type = VIRTIO_BLK_T_GET_ID;
199                         vbr->out_hdr.sector = 0;
200                         vbr->out_hdr.ioprio = req_get_ioprio(vbr->req);
201                         break;
202                 default:
203                         /* We don't put anything else in the queue. */
204                         BUG();
205                 }
206         }
207 
208         num = blk_rq_map_sg(hctx->queue, vbr->req, vbr->sg);
209         if (num) {
210                 if (rq_data_dir(vbr->req) == WRITE)
211                         vbr->out_hdr.type |= VIRTIO_BLK_T_OUT;
212                 else
213                         vbr->out_hdr.type |= VIRTIO_BLK_T_IN;
214         }
215 
216         spin_lock_irqsave(&vblk->vqs[qid].lock, flags);
217         err = __virtblk_add_req(vblk->vqs[qid].vq, vbr, vbr->sg, num);
218         if (err) {
219                 virtqueue_kick(vblk->vqs[qid].vq);
220                 blk_mq_stop_hw_queue(hctx);
221                 spin_unlock_irqrestore(&vblk->vqs[qid].lock, flags);
222                 /* Out of mem doesn't actually happen, since we fall back
223                  * to direct descriptors */
224                 if (err == -ENOMEM || err == -ENOSPC)
225                         return BLK_MQ_RQ_QUEUE_BUSY;
226                 return BLK_MQ_RQ_QUEUE_ERROR;
227         }
228 
229         if (last && virtqueue_kick_prepare(vblk->vqs[qid].vq))
230                 notify = true;
231         spin_unlock_irqrestore(&vblk->vqs[qid].lock, flags);
232 
233         if (notify)
234                 virtqueue_notify(vblk->vqs[qid].vq);
235         return BLK_MQ_RQ_QUEUE_OK;
236 }
237 
238 /* return id (s/n) string for *disk to *id_str
239  */
240 static int virtblk_get_id(struct gendisk *disk, char *id_str)
241 {
242         struct virtio_blk *vblk = disk->private_data;
243         struct request *req;
244         struct bio *bio;
245         int err;
246 
247         bio = bio_map_kern(vblk->disk->queue, id_str, VIRTIO_BLK_ID_BYTES,
248                            GFP_KERNEL);
249         if (IS_ERR(bio))
250                 return PTR_ERR(bio);
251 
252         req = blk_make_request(vblk->disk->queue, bio, GFP_KERNEL);
253         if (IS_ERR(req)) {
254                 bio_put(bio);
255                 return PTR_ERR(req);
256         }
257 
258         req->cmd_type = REQ_TYPE_SPECIAL;
259         err = blk_execute_rq(vblk->disk->queue, vblk->disk, req, false);
260         blk_put_request(req);
261 
262         return err;
263 }
264 
265 static int virtblk_ioctl(struct block_device *bdev, fmode_t mode,
266                              unsigned int cmd, unsigned long data)
267 {
268         struct gendisk *disk = bdev->bd_disk;
269         struct virtio_blk *vblk = disk->private_data;
270 
271         /*
272          * Only allow the generic SCSI ioctls if the host can support it.
273          */
274         if (!virtio_has_feature(vblk->vdev, VIRTIO_BLK_F_SCSI))
275                 return -ENOTTY;
276 
277         return scsi_cmd_blk_ioctl(bdev, mode, cmd,
278                                   (void __user *)data);
279 }
280 
281 /* We provide getgeo only to please some old bootloader/partitioning tools */
282 static int virtblk_getgeo(struct block_device *bd, struct hd_geometry *geo)
283 {
284         struct virtio_blk *vblk = bd->bd_disk->private_data;
285 
286         /* see if the host passed in geometry config */
287         if (virtio_has_feature(vblk->vdev, VIRTIO_BLK_F_GEOMETRY)) {
288                 virtio_cread(vblk->vdev, struct virtio_blk_config,
289                              geometry.cylinders, &geo->cylinders);
290                 virtio_cread(vblk->vdev, struct virtio_blk_config,
291                              geometry.heads, &geo->heads);
292                 virtio_cread(vblk->vdev, struct virtio_blk_config,
293                              geometry.sectors, &geo->sectors);
294         } else {
295                 /* some standard values, similar to sd */
296                 geo->heads = 1 << 6;
297                 geo->sectors = 1 << 5;
298                 geo->cylinders = get_capacity(bd->bd_disk) >> 11;
299         }
300         return 0;
301 }
302 
303 static const struct block_device_operations virtblk_fops = {
304         .ioctl  = virtblk_ioctl,
305         .owner  = THIS_MODULE,
306         .getgeo = virtblk_getgeo,
307 };
308 
309 static int index_to_minor(int index)
310 {
311         return index << PART_BITS;
312 }
313 
314 static int minor_to_index(int minor)
315 {
316         return minor >> PART_BITS;
317 }
318 
319 static ssize_t virtblk_serial_show(struct device *dev,
320                                 struct device_attribute *attr, char *buf)
321 {
322         struct gendisk *disk = dev_to_disk(dev);
323         int err;
324 
325         /* sysfs gives us a PAGE_SIZE buffer */
326         BUILD_BUG_ON(PAGE_SIZE < VIRTIO_BLK_ID_BYTES);
327 
328         buf[VIRTIO_BLK_ID_BYTES] = '\0';
329         err = virtblk_get_id(disk, buf);
330         if (!err)
331                 return strlen(buf);
332 
333         if (err == -EIO) /* Unsupported? Make it empty. */
334                 return 0;
335 
336         return err;
337 }
338 DEVICE_ATTR(serial, S_IRUGO, virtblk_serial_show, NULL);
339 
340 static void virtblk_config_changed_work(struct work_struct *work)
341 {
342         struct virtio_blk *vblk =
343                 container_of(work, struct virtio_blk, config_work);
344         struct virtio_device *vdev = vblk->vdev;
345         struct request_queue *q = vblk->disk->queue;
346         char cap_str_2[10], cap_str_10[10];
347         char *envp[] = { "RESIZE=1", NULL };
348         u64 capacity, size;
349 
350         mutex_lock(&vblk->config_lock);
351         if (!vblk->config_enable)
352                 goto done;
353 
354         /* Host must always specify the capacity. */
355         virtio_cread(vdev, struct virtio_blk_config, capacity, &capacity);
356 
357         /* If capacity is too big, truncate with warning. */
358         if ((sector_t)capacity != capacity) {
359                 dev_warn(&vdev->dev, "Capacity %llu too large: truncating\n",
360                          (unsigned long long)capacity);
361                 capacity = (sector_t)-1;
362         }
363 
364         size = capacity * queue_logical_block_size(q);
365         string_get_size(size, STRING_UNITS_2, cap_str_2, sizeof(cap_str_2));
366         string_get_size(size, STRING_UNITS_10, cap_str_10, sizeof(cap_str_10));
367 
368         dev_notice(&vdev->dev,
369                   "new size: %llu %d-byte logical blocks (%s/%s)\n",
370                   (unsigned long long)capacity,
371                   queue_logical_block_size(q),
372                   cap_str_10, cap_str_2);
373 
374         set_capacity(vblk->disk, capacity);
375         revalidate_disk(vblk->disk);
376         kobject_uevent_env(&disk_to_dev(vblk->disk)->kobj, KOBJ_CHANGE, envp);
377 done:
378         mutex_unlock(&vblk->config_lock);
379 }
380 
381 static void virtblk_config_changed(struct virtio_device *vdev)
382 {
383         struct virtio_blk *vblk = vdev->priv;
384 
385         queue_work(virtblk_wq, &vblk->config_work);
386 }
387 
388 static int init_vq(struct virtio_blk *vblk)
389 {
390         int err = 0;
391         int i;
392         vq_callback_t **callbacks;
393         const char **names;
394         struct virtqueue **vqs;
395         unsigned short num_vqs;
396         struct virtio_device *vdev = vblk->vdev;
397 
398         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_MQ,
399                                    struct virtio_blk_config, num_queues,
400                                    &num_vqs);
401         if (err)
402                 num_vqs = 1;
403 
404         vblk->vqs = kmalloc(sizeof(*vblk->vqs) * num_vqs, GFP_KERNEL);
405         if (!vblk->vqs) {
406                 err = -ENOMEM;
407                 goto out;
408         }
409 
410         names = kmalloc(sizeof(*names) * num_vqs, GFP_KERNEL);
411         if (!names)
412                 goto err_names;
413 
414         callbacks = kmalloc(sizeof(*callbacks) * num_vqs, GFP_KERNEL);
415         if (!callbacks)
416                 goto err_callbacks;
417 
418         vqs = kmalloc(sizeof(*vqs) * num_vqs, GFP_KERNEL);
419         if (!vqs)
420                 goto err_vqs;
421 
422         for (i = 0; i < num_vqs; i++) {
423                 callbacks[i] = virtblk_done;
424                 snprintf(vblk->vqs[i].name, VQ_NAME_LEN, "req.%d", i);
425                 names[i] = vblk->vqs[i].name;
426         }
427 
428         /* Discover virtqueues and write information to configuration.  */
429         err = vdev->config->find_vqs(vdev, num_vqs, vqs, callbacks, names);
430         if (err)
431                 goto err_find_vqs;
432 
433         for (i = 0; i < num_vqs; i++) {
434                 spin_lock_init(&vblk->vqs[i].lock);
435                 vblk->vqs[i].vq = vqs[i];
436         }
437         vblk->num_vqs = num_vqs;
438 
439  err_find_vqs:
440         kfree(vqs);
441  err_vqs:
442         kfree(callbacks);
443  err_callbacks:
444         kfree(names);
445  err_names:
446         if (err)
447                 kfree(vblk->vqs);
448  out:
449         return err;
450 }
451 
452 /*
453  * Legacy naming scheme used for virtio devices.  We are stuck with it for
454  * virtio blk but don't ever use it for any new driver.
455  */
456 static int virtblk_name_format(char *prefix, int index, char *buf, int buflen)
457 {
458         const int base = 'z' - 'a' + 1;
459         char *begin = buf + strlen(prefix);
460         char *end = buf + buflen;
461         char *p;
462         int unit;
463 
464         p = end - 1;
465         *p = '\0';
466         unit = base;
467         do {
468                 if (p == begin)
469                         return -EINVAL;
470                 *--p = 'a' + (index % unit);
471                 index = (index / unit) - 1;
472         } while (index >= 0);
473 
474         memmove(begin, p, end - p);
475         memcpy(buf, prefix, strlen(prefix));
476 
477         return 0;
478 }
479 
480 static int virtblk_get_cache_mode(struct virtio_device *vdev)
481 {
482         u8 writeback;
483         int err;
484 
485         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_CONFIG_WCE,
486                                    struct virtio_blk_config, wce,
487                                    &writeback);
488         if (err)
489                 writeback = virtio_has_feature(vdev, VIRTIO_BLK_F_WCE);
490 
491         return writeback;
492 }
493 
494 static void virtblk_update_cache_mode(struct virtio_device *vdev)
495 {
496         u8 writeback = virtblk_get_cache_mode(vdev);
497         struct virtio_blk *vblk = vdev->priv;
498 
499         if (writeback)
500                 blk_queue_flush(vblk->disk->queue, REQ_FLUSH);
501         else
502                 blk_queue_flush(vblk->disk->queue, 0);
503 
504         revalidate_disk(vblk->disk);
505 }
506 
507 static const char *const virtblk_cache_types[] = {
508         "write through", "write back"
509 };
510 
511 static ssize_t
512 virtblk_cache_type_store(struct device *dev, struct device_attribute *attr,
513                          const char *buf, size_t count)
514 {
515         struct gendisk *disk = dev_to_disk(dev);
516         struct virtio_blk *vblk = disk->private_data;
517         struct virtio_device *vdev = vblk->vdev;
518         int i;
519 
520         BUG_ON(!virtio_has_feature(vblk->vdev, VIRTIO_BLK_F_CONFIG_WCE));
521         for (i = ARRAY_SIZE(virtblk_cache_types); --i >= 0; )
522                 if (sysfs_streq(buf, virtblk_cache_types[i]))
523                         break;
524 
525         if (i < 0)
526                 return -EINVAL;
527 
528         virtio_cwrite8(vdev, offsetof(struct virtio_blk_config, wce), i);
529         virtblk_update_cache_mode(vdev);
530         return count;
531 }
532 
533 static ssize_t
534 virtblk_cache_type_show(struct device *dev, struct device_attribute *attr,
535                          char *buf)
536 {
537         struct gendisk *disk = dev_to_disk(dev);
538         struct virtio_blk *vblk = disk->private_data;
539         u8 writeback = virtblk_get_cache_mode(vblk->vdev);
540 
541         BUG_ON(writeback >= ARRAY_SIZE(virtblk_cache_types));
542         return snprintf(buf, 40, "%s\n", virtblk_cache_types[writeback]);
543 }
544 
545 static const struct device_attribute dev_attr_cache_type_ro =
546         __ATTR(cache_type, S_IRUGO,
547                virtblk_cache_type_show, NULL);
548 static const struct device_attribute dev_attr_cache_type_rw =
549         __ATTR(cache_type, S_IRUGO|S_IWUSR,
550                virtblk_cache_type_show, virtblk_cache_type_store);
551 
552 static int virtblk_init_request(void *data, struct request *rq,
553                 unsigned int hctx_idx, unsigned int request_idx,
554                 unsigned int numa_node)
555 {
556         struct virtio_blk *vblk = data;
557         struct virtblk_req *vbr = blk_mq_rq_to_pdu(rq);
558 
559         sg_init_table(vbr->sg, vblk->sg_elems);
560         return 0;
561 }
562 
563 static struct blk_mq_ops virtio_mq_ops = {
564         .queue_rq       = virtio_queue_rq,
565         .map_queue      = blk_mq_map_queue,
566         .complete       = virtblk_request_done,
567         .init_request   = virtblk_init_request,
568 };
569 
570 static unsigned int virtblk_queue_depth;
571 module_param_named(queue_depth, virtblk_queue_depth, uint, 0444);
572 
573 static int virtblk_probe(struct virtio_device *vdev)
574 {
575         struct virtio_blk *vblk;
576         struct request_queue *q;
577         int err, index;
578 
579         u64 cap;
580         u32 v, blk_size, sg_elems, opt_io_size;
581         u16 min_io_size;
582         u8 physical_block_exp, alignment_offset;
583 
584         err = ida_simple_get(&vd_index_ida, 0, minor_to_index(1 << MINORBITS),
585                              GFP_KERNEL);
586         if (err < 0)
587                 goto out;
588         index = err;
589 
590         /* We need to know how many segments before we allocate. */
591         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_SEG_MAX,
592                                    struct virtio_blk_config, seg_max,
593                                    &sg_elems);
594 
595         /* We need at least one SG element, whatever they say. */
596         if (err || !sg_elems)
597                 sg_elems = 1;
598 
599         /* We need an extra sg elements at head and tail. */
600         sg_elems += 2;
601         vdev->priv = vblk = kmalloc(sizeof(*vblk), GFP_KERNEL);
602         if (!vblk) {
603                 err = -ENOMEM;
604                 goto out_free_index;
605         }
606 
607         vblk->vdev = vdev;
608         vblk->sg_elems = sg_elems;
609         mutex_init(&vblk->config_lock);
610 
611         INIT_WORK(&vblk->config_work, virtblk_config_changed_work);
612         vblk->config_enable = true;
613 
614         err = init_vq(vblk);
615         if (err)
616                 goto out_free_vblk;
617 
618         /* FIXME: How many partitions?  How long is a piece of string? */
619         vblk->disk = alloc_disk(1 << PART_BITS);
620         if (!vblk->disk) {
621                 err = -ENOMEM;
622                 goto out_free_vq;
623         }
624 
625         /* Default queue sizing is to fill the ring. */
626         if (!virtblk_queue_depth) {
627                 virtblk_queue_depth = vblk->vqs[0].vq->num_free;
628                 /* ... but without indirect descs, we use 2 descs per req */
629                 if (!virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC))
630                         virtblk_queue_depth /= 2;
631         }
632 
633         memset(&vblk->tag_set, 0, sizeof(vblk->tag_set));
634         vblk->tag_set.ops = &virtio_mq_ops;
635         vblk->tag_set.queue_depth = virtblk_queue_depth;
636         vblk->tag_set.numa_node = NUMA_NO_NODE;
637         vblk->tag_set.flags = BLK_MQ_F_SHOULD_MERGE;
638         vblk->tag_set.cmd_size =
639                 sizeof(struct virtblk_req) +
640                 sizeof(struct scatterlist) * sg_elems;
641         vblk->tag_set.driver_data = vblk;
642         vblk->tag_set.nr_hw_queues = vblk->num_vqs;
643 
644         err = blk_mq_alloc_tag_set(&vblk->tag_set);
645         if (err)
646                 goto out_put_disk;
647 
648         q = vblk->disk->queue = blk_mq_init_queue(&vblk->tag_set);
649         if (!q) {
650                 err = -ENOMEM;
651                 goto out_free_tags;
652         }
653 
654         q->queuedata = vblk;
655 
656         virtblk_name_format("vd", index, vblk->disk->disk_name, DISK_NAME_LEN);
657 
658         vblk->disk->major = major;
659         vblk->disk->first_minor = index_to_minor(index);
660         vblk->disk->private_data = vblk;
661         vblk->disk->fops = &virtblk_fops;
662         vblk->disk->driverfs_dev = &vdev->dev;
663         vblk->index = index;
664 
665         /* configure queue flush support */
666         virtblk_update_cache_mode(vdev);
667 
668         /* If disk is read-only in the host, the guest should obey */
669         if (virtio_has_feature(vdev, VIRTIO_BLK_F_RO))
670                 set_disk_ro(vblk->disk, 1);
671 
672         /* Host must always specify the capacity. */
673         virtio_cread(vdev, struct virtio_blk_config, capacity, &cap);
674 
675         /* If capacity is too big, truncate with warning. */
676         if ((sector_t)cap != cap) {
677                 dev_warn(&vdev->dev, "Capacity %llu too large: truncating\n",
678                          (unsigned long long)cap);
679                 cap = (sector_t)-1;
680         }
681         set_capacity(vblk->disk, cap);
682 
683         /* We can handle whatever the host told us to handle. */
684         blk_queue_max_segments(q, vblk->sg_elems-2);
685 
686         /* No need to bounce any requests */
687         blk_queue_bounce_limit(q, BLK_BOUNCE_ANY);
688 
689         /* No real sector limit. */
690         blk_queue_max_hw_sectors(q, -1U);
691 
692         /* Host can optionally specify maximum segment size and number of
693          * segments. */
694         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_SIZE_MAX,
695                                    struct virtio_blk_config, size_max, &v);
696         if (!err)
697                 blk_queue_max_segment_size(q, v);
698         else
699                 blk_queue_max_segment_size(q, -1U);
700 
701         /* Host can optionally specify the block size of the device */
702         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_BLK_SIZE,
703                                    struct virtio_blk_config, blk_size,
704                                    &blk_size);
705         if (!err)
706                 blk_queue_logical_block_size(q, blk_size);
707         else
708                 blk_size = queue_logical_block_size(q);
709 
710         /* Use topology information if available */
711         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_TOPOLOGY,
712                                    struct virtio_blk_config, physical_block_exp,
713                                    &physical_block_exp);
714         if (!err && physical_block_exp)
715                 blk_queue_physical_block_size(q,
716                                 blk_size * (1 << physical_block_exp));
717 
718         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_TOPOLOGY,
719                                    struct virtio_blk_config, alignment_offset,
720                                    &alignment_offset);
721         if (!err && alignment_offset)
722                 blk_queue_alignment_offset(q, blk_size * alignment_offset);
723 
724         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_TOPOLOGY,
725                                    struct virtio_blk_config, min_io_size,
726                                    &min_io_size);
727         if (!err && min_io_size)
728                 blk_queue_io_min(q, blk_size * min_io_size);
729 
730         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_TOPOLOGY,
731                                    struct virtio_blk_config, opt_io_size,
732                                    &opt_io_size);
733         if (!err && opt_io_size)
734                 blk_queue_io_opt(q, blk_size * opt_io_size);
735 
736         add_disk(vblk->disk);
737         err = device_create_file(disk_to_dev(vblk->disk), &dev_attr_serial);
738         if (err)
739                 goto out_del_disk;
740 
741         if (virtio_has_feature(vdev, VIRTIO_BLK_F_CONFIG_WCE))
742                 err = device_create_file(disk_to_dev(vblk->disk),
743                                          &dev_attr_cache_type_rw);
744         else
745                 err = device_create_file(disk_to_dev(vblk->disk),
746                                          &dev_attr_cache_type_ro);
747         if (err)
748                 goto out_del_disk;
749         return 0;
750 
751 out_del_disk:
752         del_gendisk(vblk->disk);
753         blk_cleanup_queue(vblk->disk->queue);
754 out_free_tags:
755         blk_mq_free_tag_set(&vblk->tag_set);
756 out_put_disk:
757         put_disk(vblk->disk);
758 out_free_vq:
759         vdev->config->del_vqs(vdev);
760 out_free_vblk:
761         kfree(vblk);
762 out_free_index:
763         ida_simple_remove(&vd_index_ida, index);
764 out:
765         return err;
766 }
767 
768 static void virtblk_remove(struct virtio_device *vdev)
769 {
770         struct virtio_blk *vblk = vdev->priv;
771         int index = vblk->index;
772         int refc;
773 
774         /* Prevent config work handler from accessing the device. */
775         mutex_lock(&vblk->config_lock);
776         vblk->config_enable = false;
777         mutex_unlock(&vblk->config_lock);
778 
779         del_gendisk(vblk->disk);
780         blk_cleanup_queue(vblk->disk->queue);
781 
782         blk_mq_free_tag_set(&vblk->tag_set);
783 
784         /* Stop all the virtqueues. */
785         vdev->config->reset(vdev);
786 
787         flush_work(&vblk->config_work);
788 
789         refc = atomic_read(&disk_to_dev(vblk->disk)->kobj.kref.refcount);
790         put_disk(vblk->disk);
791         vdev->config->del_vqs(vdev);
792         kfree(vblk->vqs);
793         kfree(vblk);
794 
795         /* Only free device id if we don't have any users */
796         if (refc == 1)
797                 ida_simple_remove(&vd_index_ida, index);
798 }
799 
800 #ifdef CONFIG_PM_SLEEP
801 static int virtblk_freeze(struct virtio_device *vdev)
802 {
803         struct virtio_blk *vblk = vdev->priv;
804 
805         /* Ensure we don't receive any more interrupts */
806         vdev->config->reset(vdev);
807 
808         /* Prevent config work handler from accessing the device. */
809         mutex_lock(&vblk->config_lock);
810         vblk->config_enable = false;
811         mutex_unlock(&vblk->config_lock);
812 
813         flush_work(&vblk->config_work);
814 
815         blk_mq_stop_hw_queues(vblk->disk->queue);
816 
817         vdev->config->del_vqs(vdev);
818         return 0;
819 }
820 
821 static int virtblk_restore(struct virtio_device *vdev)
822 {
823         struct virtio_blk *vblk = vdev->priv;
824         int ret;
825 
826         vblk->config_enable = true;
827         ret = init_vq(vdev->priv);
828         if (!ret)
829                 blk_mq_start_stopped_hw_queues(vblk->disk->queue, true);
830 
831         return ret;
832 }
833 #endif
834 
835 static const struct virtio_device_id id_table[] = {
836         { VIRTIO_ID_BLOCK, VIRTIO_DEV_ANY_ID },
837         { 0 },
838 };
839 
840 static unsigned int features[] = {
841         VIRTIO_BLK_F_SEG_MAX, VIRTIO_BLK_F_SIZE_MAX, VIRTIO_BLK_F_GEOMETRY,
842         VIRTIO_BLK_F_RO, VIRTIO_BLK_F_BLK_SIZE, VIRTIO_BLK_F_SCSI,
843         VIRTIO_BLK_F_WCE, VIRTIO_BLK_F_TOPOLOGY, VIRTIO_BLK_F_CONFIG_WCE,
844         VIRTIO_BLK_F_MQ,
845 };
846 
847 static struct virtio_driver virtio_blk = {
848         .feature_table          = features,
849         .feature_table_size     = ARRAY_SIZE(features),
850         .driver.name            = KBUILD_MODNAME,
851         .driver.owner           = THIS_MODULE,
852         .id_table               = id_table,
853         .probe                  = virtblk_probe,
854         .remove                 = virtblk_remove,
855         .config_changed         = virtblk_config_changed,
856 #ifdef CONFIG_PM_SLEEP
857         .freeze                 = virtblk_freeze,
858         .restore                = virtblk_restore,
859 #endif
860 };
861 
862 static int __init init(void)
863 {
864         int error;
865 
866         virtblk_wq = alloc_workqueue("virtio-blk", 0, 0);
867         if (!virtblk_wq)
868                 return -ENOMEM;
869 
870         major = register_blkdev(0, "virtblk");
871         if (major < 0) {
872                 error = major;
873                 goto out_destroy_workqueue;
874         }
875 
876         error = register_virtio_driver(&virtio_blk);
877         if (error)
878                 goto out_unregister_blkdev;
879         return 0;
880 
881 out_unregister_blkdev:
882         unregister_blkdev(major, "virtblk");
883 out_destroy_workqueue:
884         destroy_workqueue(virtblk_wq);
885         return error;
886 }
887 
888 static void __exit fini(void)
889 {
890         unregister_blkdev(major, "virtblk");
891         unregister_virtio_driver(&virtio_blk);
892         destroy_workqueue(virtblk_wq);
893 }
894 module_init(init);
895 module_exit(fini);
896 
897 MODULE_DEVICE_TABLE(virtio, id_table);
898 MODULE_DESCRIPTION("Virtio block driver");
899 MODULE_LICENSE("GPL");
900 

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