2 #include <linux/spinlock.h>
3 #include <linux/slab.h>
4 #include <linux/blkdev.h>
5 #include <linux/smp_lock.h>
6 #include <linux/hdreg.h>
7 #include <linux/virtio.h>
8 #include <linux/virtio_blk.h>
9 #include <linux/scatterlist.h>
13 static int major, index;
19 struct virtio_device *vdev;
22 /* The disk structure for the kernel. */
25 /* Request tracking. */
26 struct list_head reqs;
30 /* What host tells us, plus 2 for header & tailer. */
31 unsigned int sg_elems;
33 /* Scatterlist: can be too big for stack. */
34 struct scatterlist sg[/*sg_elems*/];
39 struct list_head list;
41 struct virtio_blk_outhdr out_hdr;
42 struct virtio_scsi_inhdr in_hdr;
46 static void blk_done(struct virtqueue *vq)
48 struct virtio_blk *vblk = vq->vdev->priv;
49 struct virtblk_req *vbr;
53 spin_lock_irqsave(&vblk->lock, flags);
54 while ((vbr = virtqueue_get_buf(vblk->vq, &len)) != NULL) {
57 switch (vbr->status) {
61 case VIRTIO_BLK_S_UNSUPP:
69 switch (vbr->req->cmd_type) {
70 case REQ_TYPE_BLOCK_PC:
71 vbr->req->resid_len = vbr->in_hdr.residual;
72 vbr->req->sense_len = vbr->in_hdr.sense_len;
73 vbr->req->errors = vbr->in_hdr.errors;
75 case REQ_TYPE_SPECIAL:
76 vbr->req->errors = (error != 0);
82 __blk_end_request_all(vbr->req, error);
84 mempool_free(vbr, vblk->pool);
86 /* In case queue is stopped waiting for more buffers. */
87 blk_start_queue(vblk->disk->queue);
88 spin_unlock_irqrestore(&vblk->lock, flags);
91 static bool do_req(struct request_queue *q, struct virtio_blk *vblk,
94 unsigned long num, out = 0, in = 0;
95 struct virtblk_req *vbr;
97 vbr = mempool_alloc(vblk->pool, GFP_ATOMIC);
99 /* When another request finishes we'll try again. */
104 if (req->cmd_flags & REQ_FLUSH) {
105 vbr->out_hdr.type = VIRTIO_BLK_T_FLUSH;
106 vbr->out_hdr.sector = 0;
107 vbr->out_hdr.ioprio = req_get_ioprio(vbr->req);
109 switch (req->cmd_type) {
111 vbr->out_hdr.type = 0;
112 vbr->out_hdr.sector = blk_rq_pos(vbr->req);
113 vbr->out_hdr.ioprio = req_get_ioprio(vbr->req);
115 case REQ_TYPE_BLOCK_PC:
116 vbr->out_hdr.type = VIRTIO_BLK_T_SCSI_CMD;
117 vbr->out_hdr.sector = 0;
118 vbr->out_hdr.ioprio = req_get_ioprio(vbr->req);
120 case REQ_TYPE_SPECIAL:
121 vbr->out_hdr.type = VIRTIO_BLK_T_GET_ID;
122 vbr->out_hdr.sector = 0;
123 vbr->out_hdr.ioprio = req_get_ioprio(vbr->req);
126 /* We don't put anything else in the queue. */
131 if (vbr->req->cmd_flags & REQ_HARDBARRIER)
132 vbr->out_hdr.type |= VIRTIO_BLK_T_BARRIER;
134 sg_set_buf(&vblk->sg[out++], &vbr->out_hdr, sizeof(vbr->out_hdr));
137 * If this is a packet command we need a couple of additional headers.
138 * Behind the normal outhdr we put a segment with the scsi command
139 * block, and before the normal inhdr we put the sense data and the
140 * inhdr with additional status information before the normal inhdr.
142 if (vbr->req->cmd_type == REQ_TYPE_BLOCK_PC)
143 sg_set_buf(&vblk->sg[out++], vbr->req->cmd, vbr->req->cmd_len);
145 num = blk_rq_map_sg(q, vbr->req, vblk->sg + out);
147 if (vbr->req->cmd_type == REQ_TYPE_BLOCK_PC) {
148 sg_set_buf(&vblk->sg[num + out + in++], vbr->req->sense, 96);
149 sg_set_buf(&vblk->sg[num + out + in++], &vbr->in_hdr,
150 sizeof(vbr->in_hdr));
153 sg_set_buf(&vblk->sg[num + out + in++], &vbr->status,
154 sizeof(vbr->status));
157 if (rq_data_dir(vbr->req) == WRITE) {
158 vbr->out_hdr.type |= VIRTIO_BLK_T_OUT;
161 vbr->out_hdr.type |= VIRTIO_BLK_T_IN;
166 if (virtqueue_add_buf(vblk->vq, vblk->sg, out, in, vbr) < 0) {
167 mempool_free(vbr, vblk->pool);
171 list_add_tail(&vbr->list, &vblk->reqs);
175 static void do_virtblk_request(struct request_queue *q)
177 struct virtio_blk *vblk = q->queuedata;
179 unsigned int issued = 0;
181 while ((req = blk_peek_request(q)) != NULL) {
182 BUG_ON(req->nr_phys_segments + 2 > vblk->sg_elems);
184 /* If this request fails, stop queue and wait for something to
185 finish to restart it. */
186 if (!do_req(q, vblk, req)) {
190 blk_start_request(req);
195 virtqueue_kick(vblk->vq);
198 /* return id (s/n) string for *disk to *id_str
200 static int virtblk_get_id(struct gendisk *disk, char *id_str)
202 struct virtio_blk *vblk = disk->private_data;
206 bio = bio_map_kern(vblk->disk->queue, id_str, VIRTIO_BLK_ID_BYTES,
211 req = blk_make_request(vblk->disk->queue, bio, GFP_KERNEL);
217 req->cmd_type = REQ_TYPE_SPECIAL;
218 return blk_execute_rq(vblk->disk->queue, vblk->disk, req, false);
221 static int virtblk_locked_ioctl(struct block_device *bdev, fmode_t mode,
222 unsigned cmd, unsigned long data)
224 struct gendisk *disk = bdev->bd_disk;
225 struct virtio_blk *vblk = disk->private_data;
228 * Only allow the generic SCSI ioctls if the host can support it.
230 if (!virtio_has_feature(vblk->vdev, VIRTIO_BLK_F_SCSI))
233 return scsi_cmd_ioctl(disk->queue, disk, mode, cmd,
234 (void __user *)data);
237 static int virtblk_ioctl(struct block_device *bdev, fmode_t mode,
238 unsigned int cmd, unsigned long param)
243 ret = virtblk_locked_ioctl(bdev, mode, cmd, param);
249 /* We provide getgeo only to please some old bootloader/partitioning tools */
250 static int virtblk_getgeo(struct block_device *bd, struct hd_geometry *geo)
252 struct virtio_blk *vblk = bd->bd_disk->private_data;
253 struct virtio_blk_geometry vgeo;
256 /* see if the host passed in geometry config */
257 err = virtio_config_val(vblk->vdev, VIRTIO_BLK_F_GEOMETRY,
258 offsetof(struct virtio_blk_config, geometry),
262 geo->heads = vgeo.heads;
263 geo->sectors = vgeo.sectors;
264 geo->cylinders = vgeo.cylinders;
266 /* some standard values, similar to sd */
268 geo->sectors = 1 << 5;
269 geo->cylinders = get_capacity(bd->bd_disk) >> 11;
274 static const struct block_device_operations virtblk_fops = {
275 .ioctl = virtblk_ioctl,
276 .owner = THIS_MODULE,
277 .getgeo = virtblk_getgeo,
280 static int index_to_minor(int index)
282 return index << PART_BITS;
285 static ssize_t virtblk_serial_show(struct device *dev,
286 struct device_attribute *attr, char *buf)
288 struct gendisk *disk = dev_to_disk(dev);
291 /* sysfs gives us a PAGE_SIZE buffer */
292 BUILD_BUG_ON(PAGE_SIZE < VIRTIO_BLK_ID_BYTES);
294 buf[VIRTIO_BLK_ID_BYTES] = '\0';
295 err = virtblk_get_id(disk, buf);
299 if (err == -EIO) /* Unsupported? Make it empty. */
304 DEVICE_ATTR(serial, S_IRUGO, virtblk_serial_show, NULL);
306 static int __devinit virtblk_probe(struct virtio_device *vdev)
308 struct virtio_blk *vblk;
309 struct request_queue *q;
312 u32 v, blk_size, sg_elems, opt_io_size;
314 u8 physical_block_exp, alignment_offset;
316 if (index_to_minor(index) >= 1 << MINORBITS)
319 /* We need to know how many segments before we allocate. */
320 err = virtio_config_val(vdev, VIRTIO_BLK_F_SEG_MAX,
321 offsetof(struct virtio_blk_config, seg_max),
324 /* We need at least one SG element, whatever they say. */
325 if (err || !sg_elems)
328 /* We need an extra sg elements at head and tail. */
330 vdev->priv = vblk = kmalloc(sizeof(*vblk) +
331 sizeof(vblk->sg[0]) * sg_elems, GFP_KERNEL);
337 INIT_LIST_HEAD(&vblk->reqs);
338 spin_lock_init(&vblk->lock);
340 vblk->sg_elems = sg_elems;
341 sg_init_table(vblk->sg, vblk->sg_elems);
343 /* We expect one virtqueue, for output. */
344 vblk->vq = virtio_find_single_vq(vdev, blk_done, "requests");
345 if (IS_ERR(vblk->vq)) {
346 err = PTR_ERR(vblk->vq);
350 vblk->pool = mempool_create_kmalloc_pool(1,sizeof(struct virtblk_req));
356 /* FIXME: How many partitions? How long is a piece of string? */
357 vblk->disk = alloc_disk(1 << PART_BITS);
363 q = vblk->disk->queue = blk_init_queue(do_virtblk_request, &vblk->lock);
372 sprintf(vblk->disk->disk_name, "vd%c", 'a' + index % 26);
373 } else if (index < (26 + 1) * 26) {
374 sprintf(vblk->disk->disk_name, "vd%c%c",
375 'a' + index / 26 - 1, 'a' + index % 26);
377 const unsigned int m1 = (index / 26 - 1) / 26 - 1;
378 const unsigned int m2 = (index / 26 - 1) % 26;
379 const unsigned int m3 = index % 26;
380 sprintf(vblk->disk->disk_name, "vd%c%c%c",
381 'a' + m1, 'a' + m2, 'a' + m3);
384 vblk->disk->major = major;
385 vblk->disk->first_minor = index_to_minor(index);
386 vblk->disk->private_data = vblk;
387 vblk->disk->fops = &virtblk_fops;
388 vblk->disk->driverfs_dev = &vdev->dev;
391 if (virtio_has_feature(vdev, VIRTIO_BLK_F_FLUSH)) {
393 * If the FLUSH feature is supported we do have support for
394 * flushing a volatile write cache on the host. Use that
395 * to implement write barrier support.
397 blk_queue_ordered(q, QUEUE_ORDERED_DRAIN_FLUSH);
398 } else if (virtio_has_feature(vdev, VIRTIO_BLK_F_BARRIER)) {
400 * If the BARRIER feature is supported the host expects us
401 * to order request by tags. This implies there is not
402 * volatile write cache on the host, and that the host
403 * never re-orders outstanding I/O. This feature is not
404 * useful for real life scenarious and deprecated.
406 blk_queue_ordered(q, QUEUE_ORDERED_TAG);
409 * If the FLUSH feature is not supported we must assume that
410 * the host does not perform any kind of volatile write
411 * caching. We still need to drain the queue to provider
412 * proper barrier semantics.
414 blk_queue_ordered(q, QUEUE_ORDERED_DRAIN);
417 /* If disk is read-only in the host, the guest should obey */
418 if (virtio_has_feature(vdev, VIRTIO_BLK_F_RO))
419 set_disk_ro(vblk->disk, 1);
421 /* Host must always specify the capacity. */
422 vdev->config->get(vdev, offsetof(struct virtio_blk_config, capacity),
425 /* If capacity is too big, truncate with warning. */
426 if ((sector_t)cap != cap) {
427 dev_warn(&vdev->dev, "Capacity %llu too large: truncating\n",
428 (unsigned long long)cap);
431 set_capacity(vblk->disk, cap);
433 /* We can handle whatever the host told us to handle. */
434 blk_queue_max_segments(q, vblk->sg_elems-2);
436 /* No need to bounce any requests */
437 blk_queue_bounce_limit(q, BLK_BOUNCE_ANY);
439 /* No real sector limit. */
440 blk_queue_max_hw_sectors(q, -1U);
442 /* Host can optionally specify maximum segment size and number of
444 err = virtio_config_val(vdev, VIRTIO_BLK_F_SIZE_MAX,
445 offsetof(struct virtio_blk_config, size_max),
448 blk_queue_max_segment_size(q, v);
450 blk_queue_max_segment_size(q, -1U);
452 /* Host can optionally specify the block size of the device */
453 err = virtio_config_val(vdev, VIRTIO_BLK_F_BLK_SIZE,
454 offsetof(struct virtio_blk_config, blk_size),
457 blk_queue_logical_block_size(q, blk_size);
459 blk_size = queue_logical_block_size(q);
461 /* Use topology information if available */
462 err = virtio_config_val(vdev, VIRTIO_BLK_F_TOPOLOGY,
463 offsetof(struct virtio_blk_config, physical_block_exp),
464 &physical_block_exp);
465 if (!err && physical_block_exp)
466 blk_queue_physical_block_size(q,
467 blk_size * (1 << physical_block_exp));
469 err = virtio_config_val(vdev, VIRTIO_BLK_F_TOPOLOGY,
470 offsetof(struct virtio_blk_config, alignment_offset),
472 if (!err && alignment_offset)
473 blk_queue_alignment_offset(q, blk_size * alignment_offset);
475 err = virtio_config_val(vdev, VIRTIO_BLK_F_TOPOLOGY,
476 offsetof(struct virtio_blk_config, min_io_size),
478 if (!err && min_io_size)
479 blk_queue_io_min(q, blk_size * min_io_size);
481 err = virtio_config_val(vdev, VIRTIO_BLK_F_TOPOLOGY,
482 offsetof(struct virtio_blk_config, opt_io_size),
484 if (!err && opt_io_size)
485 blk_queue_io_opt(q, blk_size * opt_io_size);
488 add_disk(vblk->disk);
489 err = device_create_file(disk_to_dev(vblk->disk), &dev_attr_serial);
496 del_gendisk(vblk->disk);
497 blk_cleanup_queue(vblk->disk->queue);
499 put_disk(vblk->disk);
501 mempool_destroy(vblk->pool);
503 vdev->config->del_vqs(vdev);
510 static void __devexit virtblk_remove(struct virtio_device *vdev)
512 struct virtio_blk *vblk = vdev->priv;
514 /* Nothing should be pending. */
515 BUG_ON(!list_empty(&vblk->reqs));
517 /* Stop all the virtqueues. */
518 vdev->config->reset(vdev);
520 del_gendisk(vblk->disk);
521 blk_cleanup_queue(vblk->disk->queue);
522 put_disk(vblk->disk);
523 mempool_destroy(vblk->pool);
524 vdev->config->del_vqs(vdev);
528 static const struct virtio_device_id id_table[] = {
529 { VIRTIO_ID_BLOCK, VIRTIO_DEV_ANY_ID },
533 static unsigned int features[] = {
534 VIRTIO_BLK_F_BARRIER, VIRTIO_BLK_F_SEG_MAX, VIRTIO_BLK_F_SIZE_MAX,
535 VIRTIO_BLK_F_GEOMETRY, VIRTIO_BLK_F_RO, VIRTIO_BLK_F_BLK_SIZE,
536 VIRTIO_BLK_F_SCSI, VIRTIO_BLK_F_FLUSH, VIRTIO_BLK_F_TOPOLOGY
540 * virtio_blk causes spurious section mismatch warning by
541 * simultaneously referring to a __devinit and a __devexit function.
542 * Use __refdata to avoid this warning.
544 static struct virtio_driver __refdata virtio_blk = {
545 .feature_table = features,
546 .feature_table_size = ARRAY_SIZE(features),
547 .driver.name = KBUILD_MODNAME,
548 .driver.owner = THIS_MODULE,
549 .id_table = id_table,
550 .probe = virtblk_probe,
551 .remove = __devexit_p(virtblk_remove),
554 static int __init init(void)
556 major = register_blkdev(0, "virtblk");
559 return register_virtio_driver(&virtio_blk);
562 static void __exit fini(void)
564 unregister_blkdev(major, "virtblk");
565 unregister_virtio_driver(&virtio_blk);
570 MODULE_DEVICE_TABLE(virtio, id_table);
571 MODULE_DESCRIPTION("Virtio block driver");
572 MODULE_LICENSE("GPL");