Version:  2.0.40 2.2.26 2.4.37 3.13 3.14 3.15 3.16 3.17 3.18 3.19 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 4.10

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         struct virtio_device *vdev;
 33 
 34         /* The disk structure for the kernel. */
 35         struct gendisk *disk;
 36 
 37         /* Block layer tags. */
 38         struct blk_mq_tag_set tag_set;
 39 
 40         /* Process context for config space updates */
 41         struct work_struct config_work;
 42 
 43         /* What host tells us, plus 2 for header & tailer. */
 44         unsigned int sg_elems;
 45 
 46         /* Ida index - used to track minor number allocations. */
 47         int index;
 48 
 49         /* num of vqs */
 50         int num_vqs;
 51         struct virtio_blk_vq *vqs;
 52 };
 53 
 54 struct virtblk_req {
 55         struct request *req;
 56         struct virtio_blk_outhdr out_hdr;
 57         struct virtio_scsi_inhdr in_hdr;
 58         u8 status;
 59         u8 sense[SCSI_SENSE_BUFFERSIZE];
 60         struct scatterlist sg[];
 61 };
 62 
 63 static inline int virtblk_result(struct virtblk_req *vbr)
 64 {
 65         switch (vbr->status) {
 66         case VIRTIO_BLK_S_OK:
 67                 return 0;
 68         case VIRTIO_BLK_S_UNSUPP:
 69                 return -ENOTTY;
 70         default:
 71                 return -EIO;
 72         }
 73 }
 74 
 75 static int __virtblk_add_req(struct virtqueue *vq,
 76                              struct virtblk_req *vbr,
 77                              struct scatterlist *data_sg,
 78                              bool have_data)
 79 {
 80         struct scatterlist hdr, status, cmd, sense, inhdr, *sgs[6];
 81         unsigned int num_out = 0, num_in = 0;
 82         __virtio32 type = vbr->out_hdr.type & ~cpu_to_virtio32(vq->vdev, VIRTIO_BLK_T_OUT);
 83 
 84         sg_init_one(&hdr, &vbr->out_hdr, sizeof(vbr->out_hdr));
 85         sgs[num_out++] = &hdr;
 86 
 87         /*
 88          * If this is a packet command we need a couple of additional headers.
 89          * Behind the normal outhdr we put a segment with the scsi command
 90          * block, and before the normal inhdr we put the sense data and the
 91          * inhdr with additional status information.
 92          */
 93         if (type == cpu_to_virtio32(vq->vdev, VIRTIO_BLK_T_SCSI_CMD)) {
 94                 sg_init_one(&cmd, vbr->req->cmd, vbr->req->cmd_len);
 95                 sgs[num_out++] = &cmd;
 96         }
 97 
 98         if (have_data) {
 99                 if (vbr->out_hdr.type & cpu_to_virtio32(vq->vdev, VIRTIO_BLK_T_OUT))
100                         sgs[num_out++] = data_sg;
101                 else
102                         sgs[num_out + num_in++] = data_sg;
103         }
104 
105         if (type == cpu_to_virtio32(vq->vdev, VIRTIO_BLK_T_SCSI_CMD)) {
106                 memcpy(vbr->sense, vbr->req->sense, SCSI_SENSE_BUFFERSIZE);
107                 sg_init_one(&sense, vbr->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         struct virtio_blk *vblk = req->q->queuedata;
123         int error = virtblk_result(vbr);
124 
125         if (req->cmd_type == REQ_TYPE_BLOCK_PC) {
126                 req->resid_len = virtio32_to_cpu(vblk->vdev, vbr->in_hdr.residual);
127                 req->sense_len = virtio32_to_cpu(vblk->vdev, vbr->in_hdr.sense_len);
128                 req->errors = virtio32_to_cpu(vblk->vdev, vbr->in_hdr.errors);
129         } else if (req->cmd_type == REQ_TYPE_DRV_PRIV) {
130                 req->errors = (error != 0);
131         }
132 
133         blk_mq_end_request(req, error);
134 }
135 
136 static void virtblk_done(struct virtqueue *vq)
137 {
138         struct virtio_blk *vblk = vq->vdev->priv;
139         bool req_done = false;
140         int qid = vq->index;
141         struct virtblk_req *vbr;
142         unsigned long flags;
143         unsigned int len;
144 
145         spin_lock_irqsave(&vblk->vqs[qid].lock, flags);
146         do {
147                 virtqueue_disable_cb(vq);
148                 while ((vbr = virtqueue_get_buf(vblk->vqs[qid].vq, &len)) != NULL) {
149                         blk_mq_complete_request(vbr->req, vbr->req->errors);
150                         req_done = true;
151                 }
152                 if (unlikely(virtqueue_is_broken(vq)))
153                         break;
154         } while (!virtqueue_enable_cb(vq));
155 
156         /* In case queue is stopped waiting for more buffers. */
157         if (req_done)
158                 blk_mq_start_stopped_hw_queues(vblk->disk->queue, true);
159         spin_unlock_irqrestore(&vblk->vqs[qid].lock, flags);
160 }
161 
162 static int virtio_queue_rq(struct blk_mq_hw_ctx *hctx,
163                            const struct blk_mq_queue_data *bd)
164 {
165         struct virtio_blk *vblk = hctx->queue->queuedata;
166         struct request *req = bd->rq;
167         struct virtblk_req *vbr = blk_mq_rq_to_pdu(req);
168         unsigned long flags;
169         unsigned int num;
170         int qid = hctx->queue_num;
171         int err;
172         bool notify = false;
173 
174         BUG_ON(req->nr_phys_segments + 2 > vblk->sg_elems);
175 
176         vbr->req = req;
177         if (req_op(req) == REQ_OP_FLUSH) {
178                 vbr->out_hdr.type = cpu_to_virtio32(vblk->vdev, VIRTIO_BLK_T_FLUSH);
179                 vbr->out_hdr.sector = 0;
180                 vbr->out_hdr.ioprio = cpu_to_virtio32(vblk->vdev, req_get_ioprio(vbr->req));
181         } else {
182                 switch (req->cmd_type) {
183                 case REQ_TYPE_FS:
184                         vbr->out_hdr.type = 0;
185                         vbr->out_hdr.sector = cpu_to_virtio64(vblk->vdev, blk_rq_pos(vbr->req));
186                         vbr->out_hdr.ioprio = cpu_to_virtio32(vblk->vdev, req_get_ioprio(vbr->req));
187                         break;
188                 case REQ_TYPE_BLOCK_PC:
189                         vbr->out_hdr.type = cpu_to_virtio32(vblk->vdev, VIRTIO_BLK_T_SCSI_CMD);
190                         vbr->out_hdr.sector = 0;
191                         vbr->out_hdr.ioprio = cpu_to_virtio32(vblk->vdev, req_get_ioprio(vbr->req));
192                         break;
193                 case REQ_TYPE_DRV_PRIV:
194                         vbr->out_hdr.type = cpu_to_virtio32(vblk->vdev, VIRTIO_BLK_T_GET_ID);
195                         vbr->out_hdr.sector = 0;
196                         vbr->out_hdr.ioprio = cpu_to_virtio32(vblk->vdev, req_get_ioprio(vbr->req));
197                         break;
198                 default:
199                         /* We don't put anything else in the queue. */
200                         BUG();
201                 }
202         }
203 
204         blk_mq_start_request(req);
205 
206         num = blk_rq_map_sg(hctx->queue, vbr->req, vbr->sg);
207         if (num) {
208                 if (rq_data_dir(vbr->req) == WRITE)
209                         vbr->out_hdr.type |= cpu_to_virtio32(vblk->vdev, VIRTIO_BLK_T_OUT);
210                 else
211                         vbr->out_hdr.type |= cpu_to_virtio32(vblk->vdev, VIRTIO_BLK_T_IN);
212         }
213 
214         spin_lock_irqsave(&vblk->vqs[qid].lock, flags);
215         err = __virtblk_add_req(vblk->vqs[qid].vq, vbr, vbr->sg, num);
216         if (err) {
217                 virtqueue_kick(vblk->vqs[qid].vq);
218                 blk_mq_stop_hw_queue(hctx);
219                 spin_unlock_irqrestore(&vblk->vqs[qid].lock, flags);
220                 /* Out of mem doesn't actually happen, since we fall back
221                  * to direct descriptors */
222                 if (err == -ENOMEM || err == -ENOSPC)
223                         return BLK_MQ_RQ_QUEUE_BUSY;
224                 return BLK_MQ_RQ_QUEUE_ERROR;
225         }
226 
227         if (bd->last && virtqueue_kick_prepare(vblk->vqs[qid].vq))
228                 notify = true;
229         spin_unlock_irqrestore(&vblk->vqs[qid].lock, flags);
230 
231         if (notify)
232                 virtqueue_notify(vblk->vqs[qid].vq);
233         return BLK_MQ_RQ_QUEUE_OK;
234 }
235 
236 /* return id (s/n) string for *disk to *id_str
237  */
238 static int virtblk_get_id(struct gendisk *disk, char *id_str)
239 {
240         struct virtio_blk *vblk = disk->private_data;
241         struct request_queue *q = vblk->disk->queue;
242         struct request *req;
243         int err;
244 
245         req = blk_get_request(q, READ, GFP_KERNEL);
246         if (IS_ERR(req))
247                 return PTR_ERR(req);
248         req->cmd_type = REQ_TYPE_DRV_PRIV;
249 
250         err = blk_rq_map_kern(q, req, id_str, VIRTIO_BLK_ID_BYTES, GFP_KERNEL);
251         if (err)
252                 goto out;
253 
254         err = blk_execute_rq(vblk->disk->queue, vblk->disk, req, false);
255 out:
256         blk_put_request(req);
257         return err;
258 }
259 
260 static int virtblk_ioctl(struct block_device *bdev, fmode_t mode,
261                              unsigned int cmd, unsigned long data)
262 {
263         struct gendisk *disk = bdev->bd_disk;
264         struct virtio_blk *vblk = disk->private_data;
265 
266         /*
267          * Only allow the generic SCSI ioctls if the host can support it.
268          */
269         if (!virtio_has_feature(vblk->vdev, VIRTIO_BLK_F_SCSI))
270                 return -ENOTTY;
271 
272         return scsi_cmd_blk_ioctl(bdev, mode, cmd,
273                                   (void __user *)data);
274 }
275 
276 /* We provide getgeo only to please some old bootloader/partitioning tools */
277 static int virtblk_getgeo(struct block_device *bd, struct hd_geometry *geo)
278 {
279         struct virtio_blk *vblk = bd->bd_disk->private_data;
280 
281         /* see if the host passed in geometry config */
282         if (virtio_has_feature(vblk->vdev, VIRTIO_BLK_F_GEOMETRY)) {
283                 virtio_cread(vblk->vdev, struct virtio_blk_config,
284                              geometry.cylinders, &geo->cylinders);
285                 virtio_cread(vblk->vdev, struct virtio_blk_config,
286                              geometry.heads, &geo->heads);
287                 virtio_cread(vblk->vdev, struct virtio_blk_config,
288                              geometry.sectors, &geo->sectors);
289         } else {
290                 /* some standard values, similar to sd */
291                 geo->heads = 1 << 6;
292                 geo->sectors = 1 << 5;
293                 geo->cylinders = get_capacity(bd->bd_disk) >> 11;
294         }
295         return 0;
296 }
297 
298 static const struct block_device_operations virtblk_fops = {
299         .ioctl  = virtblk_ioctl,
300         .owner  = THIS_MODULE,
301         .getgeo = virtblk_getgeo,
302 };
303 
304 static int index_to_minor(int index)
305 {
306         return index << PART_BITS;
307 }
308 
309 static int minor_to_index(int minor)
310 {
311         return minor >> PART_BITS;
312 }
313 
314 static ssize_t virtblk_serial_show(struct device *dev,
315                                 struct device_attribute *attr, char *buf)
316 {
317         struct gendisk *disk = dev_to_disk(dev);
318         int err;
319 
320         /* sysfs gives us a PAGE_SIZE buffer */
321         BUILD_BUG_ON(PAGE_SIZE < VIRTIO_BLK_ID_BYTES);
322 
323         buf[VIRTIO_BLK_ID_BYTES] = '\0';
324         err = virtblk_get_id(disk, buf);
325         if (!err)
326                 return strlen(buf);
327 
328         if (err == -EIO) /* Unsupported? Make it empty. */
329                 return 0;
330 
331         return err;
332 }
333 
334 static 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;
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         string_get_size(capacity, queue_logical_block_size(q),
357                         STRING_UNITS_2, cap_str_2, sizeof(cap_str_2));
358         string_get_size(capacity, queue_logical_block_size(q),
359                         STRING_UNITS_10, cap_str_10, sizeof(cap_str_10));
360 
361         dev_notice(&vdev->dev,
362                   "new size: %llu %d-byte logical blocks (%s/%s)\n",
363                   (unsigned long long)capacity,
364                   queue_logical_block_size(q),
365                   cap_str_10, cap_str_2);
366 
367         set_capacity(vblk->disk, capacity);
368         revalidate_disk(vblk->disk);
369         kobject_uevent_env(&disk_to_dev(vblk->disk)->kobj, KOBJ_CHANGE, envp);
370 }
371 
372 static void virtblk_config_changed(struct virtio_device *vdev)
373 {
374         struct virtio_blk *vblk = vdev->priv;
375 
376         queue_work(virtblk_wq, &vblk->config_work);
377 }
378 
379 static int init_vq(struct virtio_blk *vblk)
380 {
381         int err;
382         int i;
383         vq_callback_t **callbacks;
384         const char **names;
385         struct virtqueue **vqs;
386         unsigned short num_vqs;
387         struct virtio_device *vdev = vblk->vdev;
388 
389         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_MQ,
390                                    struct virtio_blk_config, num_queues,
391                                    &num_vqs);
392         if (err)
393                 num_vqs = 1;
394 
395         vblk->vqs = kmalloc_array(num_vqs, sizeof(*vblk->vqs), GFP_KERNEL);
396         if (!vblk->vqs)
397                 return -ENOMEM;
398 
399         names = kmalloc_array(num_vqs, sizeof(*names), GFP_KERNEL);
400         callbacks = kmalloc_array(num_vqs, sizeof(*callbacks), GFP_KERNEL);
401         vqs = kmalloc_array(num_vqs, sizeof(*vqs), GFP_KERNEL);
402         if (!names || !callbacks || !vqs) {
403                 err = -ENOMEM;
404                 goto out;
405         }
406 
407         for (i = 0; i < num_vqs; i++) {
408                 callbacks[i] = virtblk_done;
409                 snprintf(vblk->vqs[i].name, VQ_NAME_LEN, "req.%d", i);
410                 names[i] = vblk->vqs[i].name;
411         }
412 
413         /* Discover virtqueues and write information to configuration.  */
414         err = vdev->config->find_vqs(vdev, num_vqs, vqs, callbacks, names);
415         if (err)
416                 goto out;
417 
418         for (i = 0; i < num_vqs; i++) {
419                 spin_lock_init(&vblk->vqs[i].lock);
420                 vblk->vqs[i].vq = vqs[i];
421         }
422         vblk->num_vqs = num_vqs;
423 
424 out:
425         kfree(vqs);
426         kfree(callbacks);
427         kfree(names);
428         if (err)
429                 kfree(vblk->vqs);
430         return err;
431 }
432 
433 /*
434  * Legacy naming scheme used for virtio devices.  We are stuck with it for
435  * virtio blk but don't ever use it for any new driver.
436  */
437 static int virtblk_name_format(char *prefix, int index, char *buf, int buflen)
438 {
439         const int base = 'z' - 'a' + 1;
440         char *begin = buf + strlen(prefix);
441         char *end = buf + buflen;
442         char *p;
443         int unit;
444 
445         p = end - 1;
446         *p = '\0';
447         unit = base;
448         do {
449                 if (p == begin)
450                         return -EINVAL;
451                 *--p = 'a' + (index % unit);
452                 index = (index / unit) - 1;
453         } while (index >= 0);
454 
455         memmove(begin, p, end - p);
456         memcpy(buf, prefix, strlen(prefix));
457 
458         return 0;
459 }
460 
461 static int virtblk_get_cache_mode(struct virtio_device *vdev)
462 {
463         u8 writeback;
464         int err;
465 
466         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_CONFIG_WCE,
467                                    struct virtio_blk_config, wce,
468                                    &writeback);
469 
470         /*
471          * If WCE is not configurable and flush is not available,
472          * assume no writeback cache is in use.
473          */
474         if (err)
475                 writeback = virtio_has_feature(vdev, VIRTIO_BLK_F_FLUSH);
476 
477         return writeback;
478 }
479 
480 static void virtblk_update_cache_mode(struct virtio_device *vdev)
481 {
482         u8 writeback = virtblk_get_cache_mode(vdev);
483         struct virtio_blk *vblk = vdev->priv;
484 
485         blk_queue_write_cache(vblk->disk->queue, writeback, false);
486         revalidate_disk(vblk->disk);
487 }
488 
489 static const char *const virtblk_cache_types[] = {
490         "write through", "write back"
491 };
492 
493 static ssize_t
494 virtblk_cache_type_store(struct device *dev, struct device_attribute *attr,
495                          const char *buf, size_t count)
496 {
497         struct gendisk *disk = dev_to_disk(dev);
498         struct virtio_blk *vblk = disk->private_data;
499         struct virtio_device *vdev = vblk->vdev;
500         int i;
501 
502         BUG_ON(!virtio_has_feature(vblk->vdev, VIRTIO_BLK_F_CONFIG_WCE));
503         for (i = ARRAY_SIZE(virtblk_cache_types); --i >= 0; )
504                 if (sysfs_streq(buf, virtblk_cache_types[i]))
505                         break;
506 
507         if (i < 0)
508                 return -EINVAL;
509 
510         virtio_cwrite8(vdev, offsetof(struct virtio_blk_config, wce), i);
511         virtblk_update_cache_mode(vdev);
512         return count;
513 }
514 
515 static ssize_t
516 virtblk_cache_type_show(struct device *dev, struct device_attribute *attr,
517                          char *buf)
518 {
519         struct gendisk *disk = dev_to_disk(dev);
520         struct virtio_blk *vblk = disk->private_data;
521         u8 writeback = virtblk_get_cache_mode(vblk->vdev);
522 
523         BUG_ON(writeback >= ARRAY_SIZE(virtblk_cache_types));
524         return snprintf(buf, 40, "%s\n", virtblk_cache_types[writeback]);
525 }
526 
527 static const struct device_attribute dev_attr_cache_type_ro =
528         __ATTR(cache_type, S_IRUGO,
529                virtblk_cache_type_show, NULL);
530 static const struct device_attribute dev_attr_cache_type_rw =
531         __ATTR(cache_type, S_IRUGO|S_IWUSR,
532                virtblk_cache_type_show, virtblk_cache_type_store);
533 
534 static int virtblk_init_request(void *data, struct request *rq,
535                 unsigned int hctx_idx, unsigned int request_idx,
536                 unsigned int numa_node)
537 {
538         struct virtio_blk *vblk = data;
539         struct virtblk_req *vbr = blk_mq_rq_to_pdu(rq);
540 
541         sg_init_table(vbr->sg, vblk->sg_elems);
542         return 0;
543 }
544 
545 static struct blk_mq_ops virtio_mq_ops = {
546         .queue_rq       = virtio_queue_rq,
547         .complete       = virtblk_request_done,
548         .init_request   = virtblk_init_request,
549 };
550 
551 static unsigned int virtblk_queue_depth;
552 module_param_named(queue_depth, virtblk_queue_depth, uint, 0444);
553 
554 static int virtblk_probe(struct virtio_device *vdev)
555 {
556         struct virtio_blk *vblk;
557         struct request_queue *q;
558         int err, index;
559 
560         u64 cap;
561         u32 v, blk_size, sg_elems, opt_io_size;
562         u16 min_io_size;
563         u8 physical_block_exp, alignment_offset;
564 
565         if (!vdev->config->get) {
566                 dev_err(&vdev->dev, "%s failure: config access disabled\n",
567                         __func__);
568                 return -EINVAL;
569         }
570 
571         err = ida_simple_get(&vd_index_ida, 0, minor_to_index(1 << MINORBITS),
572                              GFP_KERNEL);
573         if (err < 0)
574                 goto out;
575         index = err;
576 
577         /* We need to know how many segments before we allocate. */
578         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_SEG_MAX,
579                                    struct virtio_blk_config, seg_max,
580                                    &sg_elems);
581 
582         /* We need at least one SG element, whatever they say. */
583         if (err || !sg_elems)
584                 sg_elems = 1;
585 
586         /* We need an extra sg elements at head and tail. */
587         sg_elems += 2;
588         vdev->priv = vblk = kmalloc(sizeof(*vblk), GFP_KERNEL);
589         if (!vblk) {
590                 err = -ENOMEM;
591                 goto out_free_index;
592         }
593 
594         vblk->vdev = vdev;
595         vblk->sg_elems = sg_elems;
596 
597         INIT_WORK(&vblk->config_work, virtblk_config_changed_work);
598 
599         err = init_vq(vblk);
600         if (err)
601                 goto out_free_vblk;
602 
603         /* FIXME: How many partitions?  How long is a piece of string? */
604         vblk->disk = alloc_disk(1 << PART_BITS);
605         if (!vblk->disk) {
606                 err = -ENOMEM;
607                 goto out_free_vq;
608         }
609 
610         /* Default queue sizing is to fill the ring. */
611         if (!virtblk_queue_depth) {
612                 virtblk_queue_depth = vblk->vqs[0].vq->num_free;
613                 /* ... but without indirect descs, we use 2 descs per req */
614                 if (!virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC))
615                         virtblk_queue_depth /= 2;
616         }
617 
618         memset(&vblk->tag_set, 0, sizeof(vblk->tag_set));
619         vblk->tag_set.ops = &virtio_mq_ops;
620         vblk->tag_set.queue_depth = virtblk_queue_depth;
621         vblk->tag_set.numa_node = NUMA_NO_NODE;
622         vblk->tag_set.flags = BLK_MQ_F_SHOULD_MERGE;
623         vblk->tag_set.cmd_size =
624                 sizeof(struct virtblk_req) +
625                 sizeof(struct scatterlist) * sg_elems;
626         vblk->tag_set.driver_data = vblk;
627         vblk->tag_set.nr_hw_queues = vblk->num_vqs;
628 
629         err = blk_mq_alloc_tag_set(&vblk->tag_set);
630         if (err)
631                 goto out_put_disk;
632 
633         q = blk_mq_init_queue(&vblk->tag_set);
634         if (IS_ERR(q)) {
635                 err = -ENOMEM;
636                 goto out_free_tags;
637         }
638         vblk->disk->queue = q;
639 
640         q->queuedata = vblk;
641 
642         virtblk_name_format("vd", index, vblk->disk->disk_name, DISK_NAME_LEN);
643 
644         vblk->disk->major = major;
645         vblk->disk->first_minor = index_to_minor(index);
646         vblk->disk->private_data = vblk;
647         vblk->disk->fops = &virtblk_fops;
648         vblk->disk->flags |= GENHD_FL_EXT_DEVT;
649         vblk->index = index;
650 
651         /* configure queue flush support */
652         virtblk_update_cache_mode(vdev);
653 
654         /* If disk is read-only in the host, the guest should obey */
655         if (virtio_has_feature(vdev, VIRTIO_BLK_F_RO))
656                 set_disk_ro(vblk->disk, 1);
657 
658         /* Host must always specify the capacity. */
659         virtio_cread(vdev, struct virtio_blk_config, capacity, &cap);
660 
661         /* If capacity is too big, truncate with warning. */
662         if ((sector_t)cap != cap) {
663                 dev_warn(&vdev->dev, "Capacity %llu too large: truncating\n",
664                          (unsigned long long)cap);
665                 cap = (sector_t)-1;
666         }
667         set_capacity(vblk->disk, cap);
668 
669         /* We can handle whatever the host told us to handle. */
670         blk_queue_max_segments(q, vblk->sg_elems-2);
671 
672         /* No need to bounce any requests */
673         blk_queue_bounce_limit(q, BLK_BOUNCE_ANY);
674 
675         /* No real sector limit. */
676         blk_queue_max_hw_sectors(q, -1U);
677 
678         /* Host can optionally specify maximum segment size and number of
679          * segments. */
680         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_SIZE_MAX,
681                                    struct virtio_blk_config, size_max, &v);
682         if (!err)
683                 blk_queue_max_segment_size(q, v);
684         else
685                 blk_queue_max_segment_size(q, -1U);
686 
687         /* Host can optionally specify the block size of the device */
688         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_BLK_SIZE,
689                                    struct virtio_blk_config, blk_size,
690                                    &blk_size);
691         if (!err)
692                 blk_queue_logical_block_size(q, blk_size);
693         else
694                 blk_size = queue_logical_block_size(q);
695 
696         /* Use topology information if available */
697         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_TOPOLOGY,
698                                    struct virtio_blk_config, physical_block_exp,
699                                    &physical_block_exp);
700         if (!err && physical_block_exp)
701                 blk_queue_physical_block_size(q,
702                                 blk_size * (1 << physical_block_exp));
703 
704         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_TOPOLOGY,
705                                    struct virtio_blk_config, alignment_offset,
706                                    &alignment_offset);
707         if (!err && alignment_offset)
708                 blk_queue_alignment_offset(q, blk_size * alignment_offset);
709 
710         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_TOPOLOGY,
711                                    struct virtio_blk_config, min_io_size,
712                                    &min_io_size);
713         if (!err && min_io_size)
714                 blk_queue_io_min(q, blk_size * min_io_size);
715 
716         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_TOPOLOGY,
717                                    struct virtio_blk_config, opt_io_size,
718                                    &opt_io_size);
719         if (!err && opt_io_size)
720                 blk_queue_io_opt(q, blk_size * opt_io_size);
721 
722         virtio_device_ready(vdev);
723 
724         device_add_disk(&vdev->dev, vblk->disk);
725         err = device_create_file(disk_to_dev(vblk->disk), &dev_attr_serial);
726         if (err)
727                 goto out_del_disk;
728 
729         if (virtio_has_feature(vdev, VIRTIO_BLK_F_CONFIG_WCE))
730                 err = device_create_file(disk_to_dev(vblk->disk),
731                                          &dev_attr_cache_type_rw);
732         else
733                 err = device_create_file(disk_to_dev(vblk->disk),
734                                          &dev_attr_cache_type_ro);
735         if (err)
736                 goto out_del_disk;
737         return 0;
738 
739 out_del_disk:
740         del_gendisk(vblk->disk);
741         blk_cleanup_queue(vblk->disk->queue);
742 out_free_tags:
743         blk_mq_free_tag_set(&vblk->tag_set);
744 out_put_disk:
745         put_disk(vblk->disk);
746 out_free_vq:
747         vdev->config->del_vqs(vdev);
748 out_free_vblk:
749         kfree(vblk);
750 out_free_index:
751         ida_simple_remove(&vd_index_ida, index);
752 out:
753         return err;
754 }
755 
756 static void virtblk_remove(struct virtio_device *vdev)
757 {
758         struct virtio_blk *vblk = vdev->priv;
759         int index = vblk->index;
760         int refc;
761 
762         /* Make sure no work handler is accessing the device. */
763         flush_work(&vblk->config_work);
764 
765         del_gendisk(vblk->disk);
766         blk_cleanup_queue(vblk->disk->queue);
767 
768         blk_mq_free_tag_set(&vblk->tag_set);
769 
770         /* Stop all the virtqueues. */
771         vdev->config->reset(vdev);
772 
773         refc = atomic_read(&disk_to_dev(vblk->disk)->kobj.kref.refcount);
774         put_disk(vblk->disk);
775         vdev->config->del_vqs(vdev);
776         kfree(vblk->vqs);
777         kfree(vblk);
778 
779         /* Only free device id if we don't have any users */
780         if (refc == 1)
781                 ida_simple_remove(&vd_index_ida, index);
782 }
783 
784 #ifdef CONFIG_PM_SLEEP
785 static int virtblk_freeze(struct virtio_device *vdev)
786 {
787         struct virtio_blk *vblk = vdev->priv;
788 
789         /* Ensure we don't receive any more interrupts */
790         vdev->config->reset(vdev);
791 
792         /* Make sure no work handler is accessing the device. */
793         flush_work(&vblk->config_work);
794 
795         blk_mq_stop_hw_queues(vblk->disk->queue);
796 
797         vdev->config->del_vqs(vdev);
798         return 0;
799 }
800 
801 static int virtblk_restore(struct virtio_device *vdev)
802 {
803         struct virtio_blk *vblk = vdev->priv;
804         int ret;
805 
806         ret = init_vq(vdev->priv);
807         if (ret)
808                 return ret;
809 
810         virtio_device_ready(vdev);
811 
812         blk_mq_start_stopped_hw_queues(vblk->disk->queue, true);
813         return 0;
814 }
815 #endif
816 
817 static const struct virtio_device_id id_table[] = {
818         { VIRTIO_ID_BLOCK, VIRTIO_DEV_ANY_ID },
819         { 0 },
820 };
821 
822 static unsigned int features_legacy[] = {
823         VIRTIO_BLK_F_SEG_MAX, VIRTIO_BLK_F_SIZE_MAX, VIRTIO_BLK_F_GEOMETRY,
824         VIRTIO_BLK_F_RO, VIRTIO_BLK_F_BLK_SIZE, VIRTIO_BLK_F_SCSI,
825         VIRTIO_BLK_F_FLUSH, VIRTIO_BLK_F_TOPOLOGY, VIRTIO_BLK_F_CONFIG_WCE,
826         VIRTIO_BLK_F_MQ,
827 }
828 ;
829 static unsigned int features[] = {
830         VIRTIO_BLK_F_SEG_MAX, VIRTIO_BLK_F_SIZE_MAX, VIRTIO_BLK_F_GEOMETRY,
831         VIRTIO_BLK_F_RO, VIRTIO_BLK_F_BLK_SIZE,
832         VIRTIO_BLK_F_FLUSH, VIRTIO_BLK_F_TOPOLOGY, VIRTIO_BLK_F_CONFIG_WCE,
833         VIRTIO_BLK_F_MQ,
834 };
835 
836 static struct virtio_driver virtio_blk = {
837         .feature_table                  = features,
838         .feature_table_size             = ARRAY_SIZE(features),
839         .feature_table_legacy           = features_legacy,
840         .feature_table_size_legacy      = ARRAY_SIZE(features_legacy),
841         .driver.name                    = KBUILD_MODNAME,
842         .driver.owner                   = THIS_MODULE,
843         .id_table                       = id_table,
844         .probe                          = virtblk_probe,
845         .remove                         = virtblk_remove,
846         .config_changed                 = virtblk_config_changed,
847 #ifdef CONFIG_PM_SLEEP
848         .freeze                         = virtblk_freeze,
849         .restore                        = virtblk_restore,
850 #endif
851 };
852 
853 static int __init init(void)
854 {
855         int error;
856 
857         virtblk_wq = alloc_workqueue("virtio-blk", 0, 0);
858         if (!virtblk_wq)
859                 return -ENOMEM;
860 
861         major = register_blkdev(0, "virtblk");
862         if (major < 0) {
863                 error = major;
864                 goto out_destroy_workqueue;
865         }
866 
867         error = register_virtio_driver(&virtio_blk);
868         if (error)
869                 goto out_unregister_blkdev;
870         return 0;
871 
872 out_unregister_blkdev:
873         unregister_blkdev(major, "virtblk");
874 out_destroy_workqueue:
875         destroy_workqueue(virtblk_wq);
876         return error;
877 }
878 
879 static void __exit fini(void)
880 {
881         unregister_virtio_driver(&virtio_blk);
882         unregister_blkdev(major, "virtblk");
883         destroy_workqueue(virtblk_wq);
884 }
885 module_init(init);
886 module_exit(fini);
887 
888 MODULE_DEVICE_TABLE(virtio, id_table);
889 MODULE_DESCRIPTION("Virtio block driver");
890 MODULE_LICENSE("GPL");
891 

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