Version:  2.0.40 2.2.26 2.4.37 3.6 3.7 3.8 3.9 3.10 3.11 3.12 3.13 3.14 3.15 3.16 3.17 3.18 3.19 4.0 4.1 4.2

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);
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->cmd_flags & REQ_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 *req;
240         struct bio *bio;
241         int err;
242 
243         bio = bio_map_kern(vblk->disk->queue, id_str, VIRTIO_BLK_ID_BYTES,
244                            GFP_KERNEL);
245         if (IS_ERR(bio))
246                 return PTR_ERR(bio);
247 
248         req = blk_make_request(vblk->disk->queue, bio, GFP_KERNEL);
249         if (IS_ERR(req)) {
250                 bio_put(bio);
251                 return PTR_ERR(req);
252         }
253 
254         req->cmd_type = REQ_TYPE_DRV_PRIV;
255         err = blk_execute_rq(vblk->disk->queue, vblk->disk, req, false);
256         blk_put_request(req);
257 
258         return err;
259 }
260 
261 static int virtblk_ioctl(struct block_device *bdev, fmode_t mode,
262                              unsigned int cmd, unsigned long data)
263 {
264         struct gendisk *disk = bdev->bd_disk;
265         struct virtio_blk *vblk = disk->private_data;
266 
267         /*
268          * Only allow the generic SCSI ioctls if the host can support it.
269          */
270         if (!virtio_has_feature(vblk->vdev, VIRTIO_BLK_F_SCSI))
271                 return -ENOTTY;
272 
273         return scsi_cmd_blk_ioctl(bdev, mode, cmd,
274                                   (void __user *)data);
275 }
276 
277 /* We provide getgeo only to please some old bootloader/partitioning tools */
278 static int virtblk_getgeo(struct block_device *bd, struct hd_geometry *geo)
279 {
280         struct virtio_blk *vblk = bd->bd_disk->private_data;
281 
282         /* see if the host passed in geometry config */
283         if (virtio_has_feature(vblk->vdev, VIRTIO_BLK_F_GEOMETRY)) {
284                 virtio_cread(vblk->vdev, struct virtio_blk_config,
285                              geometry.cylinders, &geo->cylinders);
286                 virtio_cread(vblk->vdev, struct virtio_blk_config,
287                              geometry.heads, &geo->heads);
288                 virtio_cread(vblk->vdev, struct virtio_blk_config,
289                              geometry.sectors, &geo->sectors);
290         } else {
291                 /* some standard values, similar to sd */
292                 geo->heads = 1 << 6;
293                 geo->sectors = 1 << 5;
294                 geo->cylinders = get_capacity(bd->bd_disk) >> 11;
295         }
296         return 0;
297 }
298 
299 static const struct block_device_operations virtblk_fops = {
300         .ioctl  = virtblk_ioctl,
301         .owner  = THIS_MODULE,
302         .getgeo = virtblk_getgeo,
303 };
304 
305 static int index_to_minor(int index)
306 {
307         return index << PART_BITS;
308 }
309 
310 static int minor_to_index(int minor)
311 {
312         return minor >> PART_BITS;
313 }
314 
315 static ssize_t virtblk_serial_show(struct device *dev,
316                                 struct device_attribute *attr, char *buf)
317 {
318         struct gendisk *disk = dev_to_disk(dev);
319         int err;
320 
321         /* sysfs gives us a PAGE_SIZE buffer */
322         BUILD_BUG_ON(PAGE_SIZE < VIRTIO_BLK_ID_BYTES);
323 
324         buf[VIRTIO_BLK_ID_BYTES] = '\0';
325         err = virtblk_get_id(disk, buf);
326         if (!err)
327                 return strlen(buf);
328 
329         if (err == -EIO) /* Unsupported? Make it empty. */
330                 return 0;
331 
332         return err;
333 }
334 
335 static DEVICE_ATTR(serial, S_IRUGO, virtblk_serial_show, NULL);
336 
337 static void virtblk_config_changed_work(struct work_struct *work)
338 {
339         struct virtio_blk *vblk =
340                 container_of(work, struct virtio_blk, config_work);
341         struct virtio_device *vdev = vblk->vdev;
342         struct request_queue *q = vblk->disk->queue;
343         char cap_str_2[10], cap_str_10[10];
344         char *envp[] = { "RESIZE=1", NULL };
345         u64 capacity;
346 
347         /* Host must always specify the capacity. */
348         virtio_cread(vdev, struct virtio_blk_config, capacity, &capacity);
349 
350         /* If capacity is too big, truncate with warning. */
351         if ((sector_t)capacity != capacity) {
352                 dev_warn(&vdev->dev, "Capacity %llu too large: truncating\n",
353                          (unsigned long long)capacity);
354                 capacity = (sector_t)-1;
355         }
356 
357         string_get_size(capacity, queue_logical_block_size(q),
358                         STRING_UNITS_2, cap_str_2, sizeof(cap_str_2));
359         string_get_size(capacity, queue_logical_block_size(q),
360                         STRING_UNITS_10, cap_str_10, sizeof(cap_str_10));
361 
362         dev_notice(&vdev->dev,
363                   "new size: %llu %d-byte logical blocks (%s/%s)\n",
364                   (unsigned long long)capacity,
365                   queue_logical_block_size(q),
366                   cap_str_10, cap_str_2);
367 
368         set_capacity(vblk->disk, capacity);
369         revalidate_disk(vblk->disk);
370         kobject_uevent_env(&disk_to_dev(vblk->disk)->kobj, KOBJ_CHANGE, envp);
371 }
372 
373 static void virtblk_config_changed(struct virtio_device *vdev)
374 {
375         struct virtio_blk *vblk = vdev->priv;
376 
377         queue_work(virtblk_wq, &vblk->config_work);
378 }
379 
380 static int init_vq(struct virtio_blk *vblk)
381 {
382         int err = 0;
383         int i;
384         vq_callback_t **callbacks;
385         const char **names;
386         struct virtqueue **vqs;
387         unsigned short num_vqs;
388         struct virtio_device *vdev = vblk->vdev;
389 
390         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_MQ,
391                                    struct virtio_blk_config, num_queues,
392                                    &num_vqs);
393         if (err)
394                 num_vqs = 1;
395 
396         vblk->vqs = kmalloc(sizeof(*vblk->vqs) * num_vqs, GFP_KERNEL);
397         if (!vblk->vqs) {
398                 err = -ENOMEM;
399                 goto out;
400         }
401 
402         names = kmalloc(sizeof(*names) * num_vqs, GFP_KERNEL);
403         if (!names)
404                 goto err_names;
405 
406         callbacks = kmalloc(sizeof(*callbacks) * num_vqs, GFP_KERNEL);
407         if (!callbacks)
408                 goto err_callbacks;
409 
410         vqs = kmalloc(sizeof(*vqs) * num_vqs, GFP_KERNEL);
411         if (!vqs)
412                 goto err_vqs;
413 
414         for (i = 0; i < num_vqs; i++) {
415                 callbacks[i] = virtblk_done;
416                 snprintf(vblk->vqs[i].name, VQ_NAME_LEN, "req.%d", i);
417                 names[i] = vblk->vqs[i].name;
418         }
419 
420         /* Discover virtqueues and write information to configuration.  */
421         err = vdev->config->find_vqs(vdev, num_vqs, vqs, callbacks, names);
422         if (err)
423                 goto err_find_vqs;
424 
425         for (i = 0; i < num_vqs; i++) {
426                 spin_lock_init(&vblk->vqs[i].lock);
427                 vblk->vqs[i].vq = vqs[i];
428         }
429         vblk->num_vqs = num_vqs;
430 
431  err_find_vqs:
432         kfree(vqs);
433  err_vqs:
434         kfree(callbacks);
435  err_callbacks:
436         kfree(names);
437  err_names:
438         if (err)
439                 kfree(vblk->vqs);
440  out:
441         return err;
442 }
443 
444 /*
445  * Legacy naming scheme used for virtio devices.  We are stuck with it for
446  * virtio blk but don't ever use it for any new driver.
447  */
448 static int virtblk_name_format(char *prefix, int index, char *buf, int buflen)
449 {
450         const int base = 'z' - 'a' + 1;
451         char *begin = buf + strlen(prefix);
452         char *end = buf + buflen;
453         char *p;
454         int unit;
455 
456         p = end - 1;
457         *p = '\0';
458         unit = base;
459         do {
460                 if (p == begin)
461                         return -EINVAL;
462                 *--p = 'a' + (index % unit);
463                 index = (index / unit) - 1;
464         } while (index >= 0);
465 
466         memmove(begin, p, end - p);
467         memcpy(buf, prefix, strlen(prefix));
468 
469         return 0;
470 }
471 
472 static int virtblk_get_cache_mode(struct virtio_device *vdev)
473 {
474         u8 writeback;
475         int err;
476 
477         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_CONFIG_WCE,
478                                    struct virtio_blk_config, wce,
479                                    &writeback);
480         if (err)
481                 writeback = virtio_has_feature(vdev, VIRTIO_BLK_F_WCE) ||
482                             virtio_has_feature(vdev, VIRTIO_F_VERSION_1);
483 
484         return writeback;
485 }
486 
487 static void virtblk_update_cache_mode(struct virtio_device *vdev)
488 {
489         u8 writeback = virtblk_get_cache_mode(vdev);
490         struct virtio_blk *vblk = vdev->priv;
491 
492         if (writeback)
493                 blk_queue_flush(vblk->disk->queue, REQ_FLUSH);
494         else
495                 blk_queue_flush(vblk->disk->queue, 0);
496 
497         revalidate_disk(vblk->disk);
498 }
499 
500 static const char *const virtblk_cache_types[] = {
501         "write through", "write back"
502 };
503 
504 static ssize_t
505 virtblk_cache_type_store(struct device *dev, struct device_attribute *attr,
506                          const char *buf, size_t count)
507 {
508         struct gendisk *disk = dev_to_disk(dev);
509         struct virtio_blk *vblk = disk->private_data;
510         struct virtio_device *vdev = vblk->vdev;
511         int i;
512 
513         BUG_ON(!virtio_has_feature(vblk->vdev, VIRTIO_BLK_F_CONFIG_WCE));
514         for (i = ARRAY_SIZE(virtblk_cache_types); --i >= 0; )
515                 if (sysfs_streq(buf, virtblk_cache_types[i]))
516                         break;
517 
518         if (i < 0)
519                 return -EINVAL;
520 
521         virtio_cwrite8(vdev, offsetof(struct virtio_blk_config, wce), i);
522         virtblk_update_cache_mode(vdev);
523         return count;
524 }
525 
526 static ssize_t
527 virtblk_cache_type_show(struct device *dev, struct device_attribute *attr,
528                          char *buf)
529 {
530         struct gendisk *disk = dev_to_disk(dev);
531         struct virtio_blk *vblk = disk->private_data;
532         u8 writeback = virtblk_get_cache_mode(vblk->vdev);
533 
534         BUG_ON(writeback >= ARRAY_SIZE(virtblk_cache_types));
535         return snprintf(buf, 40, "%s\n", virtblk_cache_types[writeback]);
536 }
537 
538 static const struct device_attribute dev_attr_cache_type_ro =
539         __ATTR(cache_type, S_IRUGO,
540                virtblk_cache_type_show, NULL);
541 static const struct device_attribute dev_attr_cache_type_rw =
542         __ATTR(cache_type, S_IRUGO|S_IWUSR,
543                virtblk_cache_type_show, virtblk_cache_type_store);
544 
545 static int virtblk_init_request(void *data, struct request *rq,
546                 unsigned int hctx_idx, unsigned int request_idx,
547                 unsigned int numa_node)
548 {
549         struct virtio_blk *vblk = data;
550         struct virtblk_req *vbr = blk_mq_rq_to_pdu(rq);
551 
552         sg_init_table(vbr->sg, vblk->sg_elems);
553         return 0;
554 }
555 
556 static struct blk_mq_ops virtio_mq_ops = {
557         .queue_rq       = virtio_queue_rq,
558         .map_queue      = blk_mq_map_queue,
559         .complete       = virtblk_request_done,
560         .init_request   = virtblk_init_request,
561 };
562 
563 static unsigned int virtblk_queue_depth;
564 module_param_named(queue_depth, virtblk_queue_depth, uint, 0444);
565 
566 static int virtblk_probe(struct virtio_device *vdev)
567 {
568         struct virtio_blk *vblk;
569         struct request_queue *q;
570         int err, index;
571 
572         u64 cap;
573         u32 v, blk_size, sg_elems, opt_io_size;
574         u16 min_io_size;
575         u8 physical_block_exp, alignment_offset;
576 
577         if (!vdev->config->get) {
578                 dev_err(&vdev->dev, "%s failure: config access disabled\n",
579                         __func__);
580                 return -EINVAL;
581         }
582 
583         err = ida_simple_get(&vd_index_ida, 0, minor_to_index(1 << MINORBITS),
584                              GFP_KERNEL);
585         if (err < 0)
586                 goto out;
587         index = err;
588 
589         /* We need to know how many segments before we allocate. */
590         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_SEG_MAX,
591                                    struct virtio_blk_config, seg_max,
592                                    &sg_elems);
593 
594         /* We need at least one SG element, whatever they say. */
595         if (err || !sg_elems)
596                 sg_elems = 1;
597 
598         /* We need an extra sg elements at head and tail. */
599         sg_elems += 2;
600         vdev->priv = vblk = kmalloc(sizeof(*vblk), GFP_KERNEL);
601         if (!vblk) {
602                 err = -ENOMEM;
603                 goto out_free_index;
604         }
605 
606         vblk->vdev = vdev;
607         vblk->sg_elems = sg_elems;
608 
609         INIT_WORK(&vblk->config_work, virtblk_config_changed_work);
610 
611         err = init_vq(vblk);
612         if (err)
613                 goto out_free_vblk;
614 
615         /* FIXME: How many partitions?  How long is a piece of string? */
616         vblk->disk = alloc_disk(1 << PART_BITS);
617         if (!vblk->disk) {
618                 err = -ENOMEM;
619                 goto out_free_vq;
620         }
621 
622         /* Default queue sizing is to fill the ring. */
623         if (!virtblk_queue_depth) {
624                 virtblk_queue_depth = vblk->vqs[0].vq->num_free;
625                 /* ... but without indirect descs, we use 2 descs per req */
626                 if (!virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC))
627                         virtblk_queue_depth /= 2;
628         }
629 
630         memset(&vblk->tag_set, 0, sizeof(vblk->tag_set));
631         vblk->tag_set.ops = &virtio_mq_ops;
632         vblk->tag_set.queue_depth = virtblk_queue_depth;
633         vblk->tag_set.numa_node = NUMA_NO_NODE;
634         vblk->tag_set.flags = BLK_MQ_F_SHOULD_MERGE;
635         vblk->tag_set.cmd_size =
636                 sizeof(struct virtblk_req) +
637                 sizeof(struct scatterlist) * sg_elems;
638         vblk->tag_set.driver_data = vblk;
639         vblk->tag_set.nr_hw_queues = vblk->num_vqs;
640 
641         err = blk_mq_alloc_tag_set(&vblk->tag_set);
642         if (err)
643                 goto out_put_disk;
644 
645         q = vblk->disk->queue = blk_mq_init_queue(&vblk->tag_set);
646         if (IS_ERR(q)) {
647                 err = -ENOMEM;
648                 goto out_free_tags;
649         }
650 
651         q->queuedata = vblk;
652 
653         virtblk_name_format("vd", index, vblk->disk->disk_name, DISK_NAME_LEN);
654 
655         vblk->disk->major = major;
656         vblk->disk->first_minor = index_to_minor(index);
657         vblk->disk->private_data = vblk;
658         vblk->disk->fops = &virtblk_fops;
659         vblk->disk->driverfs_dev = &vdev->dev;
660         vblk->index = index;
661 
662         /* configure queue flush support */
663         virtblk_update_cache_mode(vdev);
664 
665         /* If disk is read-only in the host, the guest should obey */
666         if (virtio_has_feature(vdev, VIRTIO_BLK_F_RO))
667                 set_disk_ro(vblk->disk, 1);
668 
669         /* Host must always specify the capacity. */
670         virtio_cread(vdev, struct virtio_blk_config, capacity, &cap);
671 
672         /* If capacity is too big, truncate with warning. */
673         if ((sector_t)cap != cap) {
674                 dev_warn(&vdev->dev, "Capacity %llu too large: truncating\n",
675                          (unsigned long long)cap);
676                 cap = (sector_t)-1;
677         }
678         set_capacity(vblk->disk, cap);
679 
680         /* We can handle whatever the host told us to handle. */
681         blk_queue_max_segments(q, vblk->sg_elems-2);
682 
683         /* No need to bounce any requests */
684         blk_queue_bounce_limit(q, BLK_BOUNCE_ANY);
685 
686         /* No real sector limit. */
687         blk_queue_max_hw_sectors(q, -1U);
688 
689         /* Host can optionally specify maximum segment size and number of
690          * segments. */
691         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_SIZE_MAX,
692                                    struct virtio_blk_config, size_max, &v);
693         if (!err)
694                 blk_queue_max_segment_size(q, v);
695         else
696                 blk_queue_max_segment_size(q, -1U);
697 
698         /* Host can optionally specify the block size of the device */
699         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_BLK_SIZE,
700                                    struct virtio_blk_config, blk_size,
701                                    &blk_size);
702         if (!err)
703                 blk_queue_logical_block_size(q, blk_size);
704         else
705                 blk_size = queue_logical_block_size(q);
706 
707         /* Use topology information if available */
708         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_TOPOLOGY,
709                                    struct virtio_blk_config, physical_block_exp,
710                                    &physical_block_exp);
711         if (!err && physical_block_exp)
712                 blk_queue_physical_block_size(q,
713                                 blk_size * (1 << physical_block_exp));
714 
715         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_TOPOLOGY,
716                                    struct virtio_blk_config, alignment_offset,
717                                    &alignment_offset);
718         if (!err && alignment_offset)
719                 blk_queue_alignment_offset(q, blk_size * alignment_offset);
720 
721         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_TOPOLOGY,
722                                    struct virtio_blk_config, min_io_size,
723                                    &min_io_size);
724         if (!err && min_io_size)
725                 blk_queue_io_min(q, blk_size * min_io_size);
726 
727         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_TOPOLOGY,
728                                    struct virtio_blk_config, opt_io_size,
729                                    &opt_io_size);
730         if (!err && opt_io_size)
731                 blk_queue_io_opt(q, blk_size * opt_io_size);
732 
733         virtio_device_ready(vdev);
734 
735         add_disk(vblk->disk);
736         err = device_create_file(disk_to_dev(vblk->disk), &dev_attr_serial);
737         if (err)
738                 goto out_del_disk;
739 
740         if (virtio_has_feature(vdev, VIRTIO_BLK_F_CONFIG_WCE))
741                 err = device_create_file(disk_to_dev(vblk->disk),
742                                          &dev_attr_cache_type_rw);
743         else
744                 err = device_create_file(disk_to_dev(vblk->disk),
745                                          &dev_attr_cache_type_ro);
746         if (err)
747                 goto out_del_disk;
748         return 0;
749 
750 out_del_disk:
751         del_gendisk(vblk->disk);
752         blk_cleanup_queue(vblk->disk->queue);
753 out_free_tags:
754         blk_mq_free_tag_set(&vblk->tag_set);
755 out_put_disk:
756         put_disk(vblk->disk);
757 out_free_vq:
758         vdev->config->del_vqs(vdev);
759 out_free_vblk:
760         kfree(vblk);
761 out_free_index:
762         ida_simple_remove(&vd_index_ida, index);
763 out:
764         return err;
765 }
766 
767 static void virtblk_remove(struct virtio_device *vdev)
768 {
769         struct virtio_blk *vblk = vdev->priv;
770         int index = vblk->index;
771         int refc;
772 
773         /* Make sure no work handler is accessing the device. */
774         flush_work(&vblk->config_work);
775 
776         del_gendisk(vblk->disk);
777         blk_cleanup_queue(vblk->disk->queue);
778 
779         blk_mq_free_tag_set(&vblk->tag_set);
780 
781         /* Stop all the virtqueues. */
782         vdev->config->reset(vdev);
783 
784         refc = atomic_read(&disk_to_dev(vblk->disk)->kobj.kref.refcount);
785         put_disk(vblk->disk);
786         vdev->config->del_vqs(vdev);
787         kfree(vblk->vqs);
788         kfree(vblk);
789 
790         /* Only free device id if we don't have any users */
791         if (refc == 1)
792                 ida_simple_remove(&vd_index_ida, index);
793 }
794 
795 #ifdef CONFIG_PM_SLEEP
796 static int virtblk_freeze(struct virtio_device *vdev)
797 {
798         struct virtio_blk *vblk = vdev->priv;
799 
800         /* Ensure we don't receive any more interrupts */
801         vdev->config->reset(vdev);
802 
803         /* Make sure no work handler is accessing the device. */
804         flush_work(&vblk->config_work);
805 
806         blk_mq_stop_hw_queues(vblk->disk->queue);
807 
808         vdev->config->del_vqs(vdev);
809         return 0;
810 }
811 
812 static int virtblk_restore(struct virtio_device *vdev)
813 {
814         struct virtio_blk *vblk = vdev->priv;
815         int ret;
816 
817         ret = init_vq(vdev->priv);
818         if (ret)
819                 return ret;
820 
821         virtio_device_ready(vdev);
822 
823         blk_mq_start_stopped_hw_queues(vblk->disk->queue, true);
824         return 0;
825 }
826 #endif
827 
828 static const struct virtio_device_id id_table[] = {
829         { VIRTIO_ID_BLOCK, VIRTIO_DEV_ANY_ID },
830         { 0 },
831 };
832 
833 static unsigned int features_legacy[] = {
834         VIRTIO_BLK_F_SEG_MAX, VIRTIO_BLK_F_SIZE_MAX, VIRTIO_BLK_F_GEOMETRY,
835         VIRTIO_BLK_F_RO, VIRTIO_BLK_F_BLK_SIZE, VIRTIO_BLK_F_SCSI,
836         VIRTIO_BLK_F_WCE, VIRTIO_BLK_F_TOPOLOGY, VIRTIO_BLK_F_CONFIG_WCE,
837         VIRTIO_BLK_F_MQ,
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,
843         VIRTIO_BLK_F_TOPOLOGY,
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         .feature_table_legacy           = features_legacy,
851         .feature_table_size_legacy      = ARRAY_SIZE(features_legacy),
852         .driver.name                    = KBUILD_MODNAME,
853         .driver.owner                   = THIS_MODULE,
854         .id_table                       = id_table,
855         .probe                          = virtblk_probe,
856         .remove                         = virtblk_remove,
857         .config_changed                 = virtblk_config_changed,
858 #ifdef CONFIG_PM_SLEEP
859         .freeze                         = virtblk_freeze,
860         .restore                        = virtblk_restore,
861 #endif
862 };
863 
864 static int __init init(void)
865 {
866         int error;
867 
868         virtblk_wq = alloc_workqueue("virtio-blk", 0, 0);
869         if (!virtblk_wq)
870                 return -ENOMEM;
871 
872         major = register_blkdev(0, "virtblk");
873         if (major < 0) {
874                 error = major;
875                 goto out_destroy_workqueue;
876         }
877 
878         error = register_virtio_driver(&virtio_blk);
879         if (error)
880                 goto out_unregister_blkdev;
881         return 0;
882 
883 out_unregister_blkdev:
884         unregister_blkdev(major, "virtblk");
885 out_destroy_workqueue:
886         destroy_workqueue(virtblk_wq);
887         return error;
888 }
889 
890 static void __exit fini(void)
891 {
892         unregister_virtio_driver(&virtio_blk);
893         unregister_blkdev(major, "virtblk");
894         destroy_workqueue(virtblk_wq);
895 }
896 module_init(init);
897 module_exit(fini);
898 
899 MODULE_DEVICE_TABLE(virtio, id_table);
900 MODULE_DESCRIPTION("Virtio block driver");
901 MODULE_LICENSE("GPL");
902 

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