Version:  2.0.40 2.2.26 2.4.37 3.12 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

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         struct scatterlist sg[];
 60 };
 61 
 62 static inline int virtblk_result(struct virtblk_req *vbr)
 63 {
 64         switch (vbr->status) {
 65         case VIRTIO_BLK_S_OK:
 66                 return 0;
 67         case VIRTIO_BLK_S_UNSUPP:
 68                 return -ENOTTY;
 69         default:
 70                 return -EIO;
 71         }
 72 }
 73 
 74 static int __virtblk_add_req(struct virtqueue *vq,
 75                              struct virtblk_req *vbr,
 76                              struct scatterlist *data_sg,
 77                              bool have_data)
 78 {
 79         struct scatterlist hdr, status, cmd, sense, inhdr, *sgs[6];
 80         unsigned int num_out = 0, num_in = 0;
 81         __virtio32 type = vbr->out_hdr.type & ~cpu_to_virtio32(vq->vdev, VIRTIO_BLK_T_OUT);
 82 
 83         sg_init_one(&hdr, &vbr->out_hdr, sizeof(vbr->out_hdr));
 84         sgs[num_out++] = &hdr;
 85 
 86         /*
 87          * If this is a packet command we need a couple of additional headers.
 88          * Behind the normal outhdr we put a segment with the scsi command
 89          * block, and before the normal inhdr we put the sense data and the
 90          * inhdr with additional status information.
 91          */
 92         if (type == cpu_to_virtio32(vq->vdev, VIRTIO_BLK_T_SCSI_CMD)) {
 93                 sg_init_one(&cmd, vbr->req->cmd, vbr->req->cmd_len);
 94                 sgs[num_out++] = &cmd;
 95         }
 96 
 97         if (have_data) {
 98                 if (vbr->out_hdr.type & cpu_to_virtio32(vq->vdev, VIRTIO_BLK_T_OUT))
 99                         sgs[num_out++] = data_sg;
100                 else
101                         sgs[num_out + num_in++] = data_sg;
102         }
103 
104         if (type == cpu_to_virtio32(vq->vdev, VIRTIO_BLK_T_SCSI_CMD)) {
105                 sg_init_one(&sense, vbr->req->sense, SCSI_SENSE_BUFFERSIZE);
106                 sgs[num_out + num_in++] = &sense;
107                 sg_init_one(&inhdr, &vbr->in_hdr, sizeof(vbr->in_hdr));
108                 sgs[num_out + num_in++] = &inhdr;
109         }
110 
111         sg_init_one(&status, &vbr->status, sizeof(vbr->status));
112         sgs[num_out + num_in++] = &status;
113 
114         return virtqueue_add_sgs(vq, sgs, num_out, num_in, vbr, GFP_ATOMIC);
115 }
116 
117 static inline void virtblk_request_done(struct request *req)
118 {
119         struct virtblk_req *vbr = blk_mq_rq_to_pdu(req);
120         struct virtio_blk *vblk = req->q->queuedata;
121         int error = virtblk_result(vbr);
122 
123         if (req->cmd_type == REQ_TYPE_BLOCK_PC) {
124                 req->resid_len = virtio32_to_cpu(vblk->vdev, vbr->in_hdr.residual);
125                 req->sense_len = virtio32_to_cpu(vblk->vdev, vbr->in_hdr.sense_len);
126                 req->errors = virtio32_to_cpu(vblk->vdev, vbr->in_hdr.errors);
127         } else if (req->cmd_type == REQ_TYPE_DRV_PRIV) {
128                 req->errors = (error != 0);
129         }
130 
131         blk_mq_end_request(req, error);
132 }
133 
134 static void virtblk_done(struct virtqueue *vq)
135 {
136         struct virtio_blk *vblk = vq->vdev->priv;
137         bool req_done = false;
138         int qid = vq->index;
139         struct virtblk_req *vbr;
140         unsigned long flags;
141         unsigned int len;
142 
143         spin_lock_irqsave(&vblk->vqs[qid].lock, flags);
144         do {
145                 virtqueue_disable_cb(vq);
146                 while ((vbr = virtqueue_get_buf(vblk->vqs[qid].vq, &len)) != NULL) {
147                         blk_mq_complete_request(vbr->req, vbr->req->errors);
148                         req_done = true;
149                 }
150                 if (unlikely(virtqueue_is_broken(vq)))
151                         break;
152         } while (!virtqueue_enable_cb(vq));
153 
154         /* In case queue is stopped waiting for more buffers. */
155         if (req_done)
156                 blk_mq_start_stopped_hw_queues(vblk->disk->queue, true);
157         spin_unlock_irqrestore(&vblk->vqs[qid].lock, flags);
158 }
159 
160 static int virtio_queue_rq(struct blk_mq_hw_ctx *hctx,
161                            const struct blk_mq_queue_data *bd)
162 {
163         struct virtio_blk *vblk = hctx->queue->queuedata;
164         struct request *req = bd->rq;
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_op(req) == REQ_OP_FLUSH) {
176                 vbr->out_hdr.type = cpu_to_virtio32(vblk->vdev, VIRTIO_BLK_T_FLUSH);
177                 vbr->out_hdr.sector = 0;
178                 vbr->out_hdr.ioprio = cpu_to_virtio32(vblk->vdev, 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 = cpu_to_virtio64(vblk->vdev, blk_rq_pos(vbr->req));
184                         vbr->out_hdr.ioprio = cpu_to_virtio32(vblk->vdev, req_get_ioprio(vbr->req));
185                         break;
186                 case REQ_TYPE_BLOCK_PC:
187                         vbr->out_hdr.type = cpu_to_virtio32(vblk->vdev, VIRTIO_BLK_T_SCSI_CMD);
188                         vbr->out_hdr.sector = 0;
189                         vbr->out_hdr.ioprio = cpu_to_virtio32(vblk->vdev, req_get_ioprio(vbr->req));
190                         break;
191                 case REQ_TYPE_DRV_PRIV:
192                         vbr->out_hdr.type = cpu_to_virtio32(vblk->vdev, VIRTIO_BLK_T_GET_ID);
193                         vbr->out_hdr.sector = 0;
194                         vbr->out_hdr.ioprio = cpu_to_virtio32(vblk->vdev, 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 |= cpu_to_virtio32(vblk->vdev, VIRTIO_BLK_T_OUT);
208                 else
209                         vbr->out_hdr.type |= cpu_to_virtio32(vblk->vdev, 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 (bd->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_queue *q = vblk->disk->queue;
240         struct request *req;
241         int err;
242 
243         req = blk_get_request(q, READ, GFP_KERNEL);
244         if (IS_ERR(req))
245                 return PTR_ERR(req);
246         req->cmd_type = REQ_TYPE_DRV_PRIV;
247 
248         err = blk_rq_map_kern(q, req, id_str, VIRTIO_BLK_ID_BYTES, GFP_KERNEL);
249         if (err)
250                 goto out;
251 
252         err = blk_execute_rq(vblk->disk->queue, vblk->disk, req, false);
253 out:
254         blk_put_request(req);
255         return err;
256 }
257 
258 static int virtblk_ioctl(struct block_device *bdev, fmode_t mode,
259                              unsigned int cmd, unsigned long data)
260 {
261         struct gendisk *disk = bdev->bd_disk;
262         struct virtio_blk *vblk = disk->private_data;
263 
264         /*
265          * Only allow the generic SCSI ioctls if the host can support it.
266          */
267         if (!virtio_has_feature(vblk->vdev, VIRTIO_BLK_F_SCSI))
268                 return -ENOTTY;
269 
270         return scsi_cmd_blk_ioctl(bdev, mode, cmd,
271                                   (void __user *)data);
272 }
273 
274 /* We provide getgeo only to please some old bootloader/partitioning tools */
275 static int virtblk_getgeo(struct block_device *bd, struct hd_geometry *geo)
276 {
277         struct virtio_blk *vblk = bd->bd_disk->private_data;
278 
279         /* see if the host passed in geometry config */
280         if (virtio_has_feature(vblk->vdev, VIRTIO_BLK_F_GEOMETRY)) {
281                 virtio_cread(vblk->vdev, struct virtio_blk_config,
282                              geometry.cylinders, &geo->cylinders);
283                 virtio_cread(vblk->vdev, struct virtio_blk_config,
284                              geometry.heads, &geo->heads);
285                 virtio_cread(vblk->vdev, struct virtio_blk_config,
286                              geometry.sectors, &geo->sectors);
287         } else {
288                 /* some standard values, similar to sd */
289                 geo->heads = 1 << 6;
290                 geo->sectors = 1 << 5;
291                 geo->cylinders = get_capacity(bd->bd_disk) >> 11;
292         }
293         return 0;
294 }
295 
296 static const struct block_device_operations virtblk_fops = {
297         .ioctl  = virtblk_ioctl,
298         .owner  = THIS_MODULE,
299         .getgeo = virtblk_getgeo,
300 };
301 
302 static int index_to_minor(int index)
303 {
304         return index << PART_BITS;
305 }
306 
307 static int minor_to_index(int minor)
308 {
309         return minor >> PART_BITS;
310 }
311 
312 static ssize_t virtblk_serial_show(struct device *dev,
313                                 struct device_attribute *attr, char *buf)
314 {
315         struct gendisk *disk = dev_to_disk(dev);
316         int err;
317 
318         /* sysfs gives us a PAGE_SIZE buffer */
319         BUILD_BUG_ON(PAGE_SIZE < VIRTIO_BLK_ID_BYTES);
320 
321         buf[VIRTIO_BLK_ID_BYTES] = '\0';
322         err = virtblk_get_id(disk, buf);
323         if (!err)
324                 return strlen(buf);
325 
326         if (err == -EIO) /* Unsupported? Make it empty. */
327                 return 0;
328 
329         return err;
330 }
331 
332 static DEVICE_ATTR(serial, S_IRUGO, virtblk_serial_show, NULL);
333 
334 static void virtblk_config_changed_work(struct work_struct *work)
335 {
336         struct virtio_blk *vblk =
337                 container_of(work, struct virtio_blk, config_work);
338         struct virtio_device *vdev = vblk->vdev;
339         struct request_queue *q = vblk->disk->queue;
340         char cap_str_2[10], cap_str_10[10];
341         char *envp[] = { "RESIZE=1", NULL };
342         u64 capacity;
343 
344         /* Host must always specify the capacity. */
345         virtio_cread(vdev, struct virtio_blk_config, capacity, &capacity);
346 
347         /* If capacity is too big, truncate with warning. */
348         if ((sector_t)capacity != capacity) {
349                 dev_warn(&vdev->dev, "Capacity %llu too large: truncating\n",
350                          (unsigned long long)capacity);
351                 capacity = (sector_t)-1;
352         }
353 
354         string_get_size(capacity, queue_logical_block_size(q),
355                         STRING_UNITS_2, cap_str_2, sizeof(cap_str_2));
356         string_get_size(capacity, queue_logical_block_size(q),
357                         STRING_UNITS_10, cap_str_10, sizeof(cap_str_10));
358 
359         dev_notice(&vdev->dev,
360                   "new size: %llu %d-byte logical blocks (%s/%s)\n",
361                   (unsigned long long)capacity,
362                   queue_logical_block_size(q),
363                   cap_str_10, cap_str_2);
364 
365         set_capacity(vblk->disk, capacity);
366         revalidate_disk(vblk->disk);
367         kobject_uevent_env(&disk_to_dev(vblk->disk)->kobj, KOBJ_CHANGE, envp);
368 }
369 
370 static void virtblk_config_changed(struct virtio_device *vdev)
371 {
372         struct virtio_blk *vblk = vdev->priv;
373 
374         queue_work(virtblk_wq, &vblk->config_work);
375 }
376 
377 static int init_vq(struct virtio_blk *vblk)
378 {
379         int err;
380         int i;
381         vq_callback_t **callbacks;
382         const char **names;
383         struct virtqueue **vqs;
384         unsigned short num_vqs;
385         struct virtio_device *vdev = vblk->vdev;
386 
387         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_MQ,
388                                    struct virtio_blk_config, num_queues,
389                                    &num_vqs);
390         if (err)
391                 num_vqs = 1;
392 
393         vblk->vqs = kmalloc_array(num_vqs, sizeof(*vblk->vqs), GFP_KERNEL);
394         if (!vblk->vqs)
395                 return -ENOMEM;
396 
397         names = kmalloc_array(num_vqs, sizeof(*names), GFP_KERNEL);
398         callbacks = kmalloc_array(num_vqs, sizeof(*callbacks), GFP_KERNEL);
399         vqs = kmalloc_array(num_vqs, sizeof(*vqs), GFP_KERNEL);
400         if (!names || !callbacks || !vqs) {
401                 err = -ENOMEM;
402                 goto out;
403         }
404 
405         for (i = 0; i < num_vqs; i++) {
406                 callbacks[i] = virtblk_done;
407                 snprintf(vblk->vqs[i].name, VQ_NAME_LEN, "req.%d", i);
408                 names[i] = vblk->vqs[i].name;
409         }
410 
411         /* Discover virtqueues and write information to configuration.  */
412         err = vdev->config->find_vqs(vdev, num_vqs, vqs, callbacks, names);
413         if (err)
414                 goto out;
415 
416         for (i = 0; i < num_vqs; i++) {
417                 spin_lock_init(&vblk->vqs[i].lock);
418                 vblk->vqs[i].vq = vqs[i];
419         }
420         vblk->num_vqs = num_vqs;
421 
422 out:
423         kfree(vqs);
424         kfree(callbacks);
425         kfree(names);
426         if (err)
427                 kfree(vblk->vqs);
428         return err;
429 }
430 
431 /*
432  * Legacy naming scheme used for virtio devices.  We are stuck with it for
433  * virtio blk but don't ever use it for any new driver.
434  */
435 static int virtblk_name_format(char *prefix, int index, char *buf, int buflen)
436 {
437         const int base = 'z' - 'a' + 1;
438         char *begin = buf + strlen(prefix);
439         char *end = buf + buflen;
440         char *p;
441         int unit;
442 
443         p = end - 1;
444         *p = '\0';
445         unit = base;
446         do {
447                 if (p == begin)
448                         return -EINVAL;
449                 *--p = 'a' + (index % unit);
450                 index = (index / unit) - 1;
451         } while (index >= 0);
452 
453         memmove(begin, p, end - p);
454         memcpy(buf, prefix, strlen(prefix));
455 
456         return 0;
457 }
458 
459 static int virtblk_get_cache_mode(struct virtio_device *vdev)
460 {
461         u8 writeback;
462         int err;
463 
464         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_CONFIG_WCE,
465                                    struct virtio_blk_config, wce,
466                                    &writeback);
467 
468         /*
469          * If WCE is not configurable and flush is not available,
470          * assume no writeback cache is in use.
471          */
472         if (err)
473                 writeback = virtio_has_feature(vdev, VIRTIO_BLK_F_FLUSH);
474 
475         return writeback;
476 }
477 
478 static void virtblk_update_cache_mode(struct virtio_device *vdev)
479 {
480         u8 writeback = virtblk_get_cache_mode(vdev);
481         struct virtio_blk *vblk = vdev->priv;
482 
483         blk_queue_write_cache(vblk->disk->queue, writeback, false);
484         revalidate_disk(vblk->disk);
485 }
486 
487 static const char *const virtblk_cache_types[] = {
488         "write through", "write back"
489 };
490 
491 static ssize_t
492 virtblk_cache_type_store(struct device *dev, struct device_attribute *attr,
493                          const char *buf, size_t count)
494 {
495         struct gendisk *disk = dev_to_disk(dev);
496         struct virtio_blk *vblk = disk->private_data;
497         struct virtio_device *vdev = vblk->vdev;
498         int i;
499 
500         BUG_ON(!virtio_has_feature(vblk->vdev, VIRTIO_BLK_F_CONFIG_WCE));
501         for (i = ARRAY_SIZE(virtblk_cache_types); --i >= 0; )
502                 if (sysfs_streq(buf, virtblk_cache_types[i]))
503                         break;
504 
505         if (i < 0)
506                 return -EINVAL;
507 
508         virtio_cwrite8(vdev, offsetof(struct virtio_blk_config, wce), i);
509         virtblk_update_cache_mode(vdev);
510         return count;
511 }
512 
513 static ssize_t
514 virtblk_cache_type_show(struct device *dev, struct device_attribute *attr,
515                          char *buf)
516 {
517         struct gendisk *disk = dev_to_disk(dev);
518         struct virtio_blk *vblk = disk->private_data;
519         u8 writeback = virtblk_get_cache_mode(vblk->vdev);
520 
521         BUG_ON(writeback >= ARRAY_SIZE(virtblk_cache_types));
522         return snprintf(buf, 40, "%s\n", virtblk_cache_types[writeback]);
523 }
524 
525 static const struct device_attribute dev_attr_cache_type_ro =
526         __ATTR(cache_type, S_IRUGO,
527                virtblk_cache_type_show, NULL);
528 static const struct device_attribute dev_attr_cache_type_rw =
529         __ATTR(cache_type, S_IRUGO|S_IWUSR,
530                virtblk_cache_type_show, virtblk_cache_type_store);
531 
532 static int virtblk_init_request(void *data, struct request *rq,
533                 unsigned int hctx_idx, unsigned int request_idx,
534                 unsigned int numa_node)
535 {
536         struct virtio_blk *vblk = data;
537         struct virtblk_req *vbr = blk_mq_rq_to_pdu(rq);
538 
539         sg_init_table(vbr->sg, vblk->sg_elems);
540         return 0;
541 }
542 
543 static struct blk_mq_ops virtio_mq_ops = {
544         .queue_rq       = virtio_queue_rq,
545         .complete       = virtblk_request_done,
546         .init_request   = virtblk_init_request,
547 };
548 
549 static unsigned int virtblk_queue_depth;
550 module_param_named(queue_depth, virtblk_queue_depth, uint, 0444);
551 
552 static int virtblk_probe(struct virtio_device *vdev)
553 {
554         struct virtio_blk *vblk;
555         struct request_queue *q;
556         int err, index;
557 
558         u64 cap;
559         u32 v, blk_size, sg_elems, opt_io_size;
560         u16 min_io_size;
561         u8 physical_block_exp, alignment_offset;
562 
563         if (!vdev->config->get) {
564                 dev_err(&vdev->dev, "%s failure: config access disabled\n",
565                         __func__);
566                 return -EINVAL;
567         }
568 
569         err = ida_simple_get(&vd_index_ida, 0, minor_to_index(1 << MINORBITS),
570                              GFP_KERNEL);
571         if (err < 0)
572                 goto out;
573         index = err;
574 
575         /* We need to know how many segments before we allocate. */
576         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_SEG_MAX,
577                                    struct virtio_blk_config, seg_max,
578                                    &sg_elems);
579 
580         /* We need at least one SG element, whatever they say. */
581         if (err || !sg_elems)
582                 sg_elems = 1;
583 
584         /* We need an extra sg elements at head and tail. */
585         sg_elems += 2;
586         vdev->priv = vblk = kmalloc(sizeof(*vblk), GFP_KERNEL);
587         if (!vblk) {
588                 err = -ENOMEM;
589                 goto out_free_index;
590         }
591 
592         vblk->vdev = vdev;
593         vblk->sg_elems = sg_elems;
594 
595         INIT_WORK(&vblk->config_work, virtblk_config_changed_work);
596 
597         err = init_vq(vblk);
598         if (err)
599                 goto out_free_vblk;
600 
601         /* FIXME: How many partitions?  How long is a piece of string? */
602         vblk->disk = alloc_disk(1 << PART_BITS);
603         if (!vblk->disk) {
604                 err = -ENOMEM;
605                 goto out_free_vq;
606         }
607 
608         /* Default queue sizing is to fill the ring. */
609         if (!virtblk_queue_depth) {
610                 virtblk_queue_depth = vblk->vqs[0].vq->num_free;
611                 /* ... but without indirect descs, we use 2 descs per req */
612                 if (!virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC))
613                         virtblk_queue_depth /= 2;
614         }
615 
616         memset(&vblk->tag_set, 0, sizeof(vblk->tag_set));
617         vblk->tag_set.ops = &virtio_mq_ops;
618         vblk->tag_set.queue_depth = virtblk_queue_depth;
619         vblk->tag_set.numa_node = NUMA_NO_NODE;
620         vblk->tag_set.flags = BLK_MQ_F_SHOULD_MERGE;
621         vblk->tag_set.cmd_size =
622                 sizeof(struct virtblk_req) +
623                 sizeof(struct scatterlist) * sg_elems;
624         vblk->tag_set.driver_data = vblk;
625         vblk->tag_set.nr_hw_queues = vblk->num_vqs;
626 
627         err = blk_mq_alloc_tag_set(&vblk->tag_set);
628         if (err)
629                 goto out_put_disk;
630 
631         q = vblk->disk->queue = blk_mq_init_queue(&vblk->tag_set);
632         if (IS_ERR(q)) {
633                 err = -ENOMEM;
634                 goto out_free_tags;
635         }
636 
637         q->queuedata = vblk;
638 
639         virtblk_name_format("vd", index, vblk->disk->disk_name, DISK_NAME_LEN);
640 
641         vblk->disk->major = major;
642         vblk->disk->first_minor = index_to_minor(index);
643         vblk->disk->private_data = vblk;
644         vblk->disk->fops = &virtblk_fops;
645         vblk->disk->flags |= GENHD_FL_EXT_DEVT;
646         vblk->index = index;
647 
648         /* configure queue flush support */
649         virtblk_update_cache_mode(vdev);
650 
651         /* If disk is read-only in the host, the guest should obey */
652         if (virtio_has_feature(vdev, VIRTIO_BLK_F_RO))
653                 set_disk_ro(vblk->disk, 1);
654 
655         /* Host must always specify the capacity. */
656         virtio_cread(vdev, struct virtio_blk_config, capacity, &cap);
657 
658         /* If capacity is too big, truncate with warning. */
659         if ((sector_t)cap != cap) {
660                 dev_warn(&vdev->dev, "Capacity %llu too large: truncating\n",
661                          (unsigned long long)cap);
662                 cap = (sector_t)-1;
663         }
664         set_capacity(vblk->disk, cap);
665 
666         /* We can handle whatever the host told us to handle. */
667         blk_queue_max_segments(q, vblk->sg_elems-2);
668 
669         /* No need to bounce any requests */
670         blk_queue_bounce_limit(q, BLK_BOUNCE_ANY);
671 
672         /* No real sector limit. */
673         blk_queue_max_hw_sectors(q, -1U);
674 
675         /* Host can optionally specify maximum segment size and number of
676          * segments. */
677         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_SIZE_MAX,
678                                    struct virtio_blk_config, size_max, &v);
679         if (!err)
680                 blk_queue_max_segment_size(q, v);
681         else
682                 blk_queue_max_segment_size(q, -1U);
683 
684         /* Host can optionally specify the block size of the device */
685         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_BLK_SIZE,
686                                    struct virtio_blk_config, blk_size,
687                                    &blk_size);
688         if (!err)
689                 blk_queue_logical_block_size(q, blk_size);
690         else
691                 blk_size = queue_logical_block_size(q);
692 
693         /* Use topology information if available */
694         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_TOPOLOGY,
695                                    struct virtio_blk_config, physical_block_exp,
696                                    &physical_block_exp);
697         if (!err && physical_block_exp)
698                 blk_queue_physical_block_size(q,
699                                 blk_size * (1 << physical_block_exp));
700 
701         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_TOPOLOGY,
702                                    struct virtio_blk_config, alignment_offset,
703                                    &alignment_offset);
704         if (!err && alignment_offset)
705                 blk_queue_alignment_offset(q, blk_size * alignment_offset);
706 
707         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_TOPOLOGY,
708                                    struct virtio_blk_config, min_io_size,
709                                    &min_io_size);
710         if (!err && min_io_size)
711                 blk_queue_io_min(q, blk_size * min_io_size);
712 
713         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_TOPOLOGY,
714                                    struct virtio_blk_config, opt_io_size,
715                                    &opt_io_size);
716         if (!err && opt_io_size)
717                 blk_queue_io_opt(q, blk_size * opt_io_size);
718 
719         virtio_device_ready(vdev);
720 
721         device_add_disk(&vdev->dev, vblk->disk);
722         err = device_create_file(disk_to_dev(vblk->disk), &dev_attr_serial);
723         if (err)
724                 goto out_del_disk;
725 
726         if (virtio_has_feature(vdev, VIRTIO_BLK_F_CONFIG_WCE))
727                 err = device_create_file(disk_to_dev(vblk->disk),
728                                          &dev_attr_cache_type_rw);
729         else
730                 err = device_create_file(disk_to_dev(vblk->disk),
731                                          &dev_attr_cache_type_ro);
732         if (err)
733                 goto out_del_disk;
734         return 0;
735 
736 out_del_disk:
737         del_gendisk(vblk->disk);
738         blk_cleanup_queue(vblk->disk->queue);
739 out_free_tags:
740         blk_mq_free_tag_set(&vblk->tag_set);
741 out_put_disk:
742         put_disk(vblk->disk);
743 out_free_vq:
744         vdev->config->del_vqs(vdev);
745 out_free_vblk:
746         kfree(vblk);
747 out_free_index:
748         ida_simple_remove(&vd_index_ida, index);
749 out:
750         return err;
751 }
752 
753 static void virtblk_remove(struct virtio_device *vdev)
754 {
755         struct virtio_blk *vblk = vdev->priv;
756         int index = vblk->index;
757         int refc;
758 
759         /* Make sure no work handler is accessing the device. */
760         flush_work(&vblk->config_work);
761 
762         del_gendisk(vblk->disk);
763         blk_cleanup_queue(vblk->disk->queue);
764 
765         blk_mq_free_tag_set(&vblk->tag_set);
766 
767         /* Stop all the virtqueues. */
768         vdev->config->reset(vdev);
769 
770         refc = atomic_read(&disk_to_dev(vblk->disk)->kobj.kref.refcount);
771         put_disk(vblk->disk);
772         vdev->config->del_vqs(vdev);
773         kfree(vblk->vqs);
774         kfree(vblk);
775 
776         /* Only free device id if we don't have any users */
777         if (refc == 1)
778                 ida_simple_remove(&vd_index_ida, index);
779 }
780 
781 #ifdef CONFIG_PM_SLEEP
782 static int virtblk_freeze(struct virtio_device *vdev)
783 {
784         struct virtio_blk *vblk = vdev->priv;
785 
786         /* Ensure we don't receive any more interrupts */
787         vdev->config->reset(vdev);
788 
789         /* Make sure no work handler is accessing the device. */
790         flush_work(&vblk->config_work);
791 
792         blk_mq_stop_hw_queues(vblk->disk->queue);
793 
794         vdev->config->del_vqs(vdev);
795         return 0;
796 }
797 
798 static int virtblk_restore(struct virtio_device *vdev)
799 {
800         struct virtio_blk *vblk = vdev->priv;
801         int ret;
802 
803         ret = init_vq(vdev->priv);
804         if (ret)
805                 return ret;
806 
807         virtio_device_ready(vdev);
808 
809         blk_mq_start_stopped_hw_queues(vblk->disk->queue, true);
810         return 0;
811 }
812 #endif
813 
814 static const struct virtio_device_id id_table[] = {
815         { VIRTIO_ID_BLOCK, VIRTIO_DEV_ANY_ID },
816         { 0 },
817 };
818 
819 static unsigned int features_legacy[] = {
820         VIRTIO_BLK_F_SEG_MAX, VIRTIO_BLK_F_SIZE_MAX, VIRTIO_BLK_F_GEOMETRY,
821         VIRTIO_BLK_F_RO, VIRTIO_BLK_F_BLK_SIZE, VIRTIO_BLK_F_SCSI,
822         VIRTIO_BLK_F_FLUSH, VIRTIO_BLK_F_TOPOLOGY, VIRTIO_BLK_F_CONFIG_WCE,
823         VIRTIO_BLK_F_MQ,
824 }
825 ;
826 static unsigned int features[] = {
827         VIRTIO_BLK_F_SEG_MAX, VIRTIO_BLK_F_SIZE_MAX, VIRTIO_BLK_F_GEOMETRY,
828         VIRTIO_BLK_F_RO, VIRTIO_BLK_F_BLK_SIZE,
829         VIRTIO_BLK_F_FLUSH, VIRTIO_BLK_F_TOPOLOGY, VIRTIO_BLK_F_CONFIG_WCE,
830         VIRTIO_BLK_F_MQ,
831 };
832 
833 static struct virtio_driver virtio_blk = {
834         .feature_table                  = features,
835         .feature_table_size             = ARRAY_SIZE(features),
836         .feature_table_legacy           = features_legacy,
837         .feature_table_size_legacy      = ARRAY_SIZE(features_legacy),
838         .driver.name                    = KBUILD_MODNAME,
839         .driver.owner                   = THIS_MODULE,
840         .id_table                       = id_table,
841         .probe                          = virtblk_probe,
842         .remove                         = virtblk_remove,
843         .config_changed                 = virtblk_config_changed,
844 #ifdef CONFIG_PM_SLEEP
845         .freeze                         = virtblk_freeze,
846         .restore                        = virtblk_restore,
847 #endif
848 };
849 
850 static int __init init(void)
851 {
852         int error;
853 
854         virtblk_wq = alloc_workqueue("virtio-blk", 0, 0);
855         if (!virtblk_wq)
856                 return -ENOMEM;
857 
858         major = register_blkdev(0, "virtblk");
859         if (major < 0) {
860                 error = major;
861                 goto out_destroy_workqueue;
862         }
863 
864         error = register_virtio_driver(&virtio_blk);
865         if (error)
866                 goto out_unregister_blkdev;
867         return 0;
868 
869 out_unregister_blkdev:
870         unregister_blkdev(major, "virtblk");
871 out_destroy_workqueue:
872         destroy_workqueue(virtblk_wq);
873         return error;
874 }
875 
876 static void __exit fini(void)
877 {
878         unregister_virtio_driver(&virtio_blk);
879         unregister_blkdev(major, "virtblk");
880         destroy_workqueue(virtblk_wq);
881 }
882 module_init(init);
883 module_exit(fini);
884 
885 MODULE_DEVICE_TABLE(virtio, id_table);
886 MODULE_DESCRIPTION("Virtio block driver");
887 MODULE_LICENSE("GPL");
888 

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