//#define DEBUG
#include <linux/spinlock.h>
#include <linux/blkdev.h>
#include <linux/hdreg.h>
#include <linux/virtio.h>
#include <linux/virtio_blk.h>
#include <linux/scatterlist.h>
#define PART_BITS 4
static int major, index;
struct virtio_blk
{
spinlock_t lock;
struct virtio_device *vdev;
struct virtqueue *vq;
/* The disk structure for the kernel. */
struct gendisk *disk;
/* Request tracking. */
struct list_head reqs;
mempool_t *pool;
/* What host tells us, plus 2 for header & tailer. */
unsigned int sg_elems;
/* Scatterlist: can be too big for stack. */
struct scatterlist sg[/*sg_elems*/];
};
struct virtblk_req
{
struct list_head list;
struct request *req;
struct virtio_blk_outhdr out_hdr;
struct virtio_scsi_inhdr in_hdr;
u8 status;
};
static void blk_done(struct virtqueue *vq)
{
struct virtio_blk *vblk = vq->vdev->priv;
struct virtblk_req *vbr;
unsigned int len;
unsigned long flags;
spin_lock_irqsave(&vblk->lock, flags);
while ((vbr = vblk->vq->vq_ops->get_buf(vblk->vq, &len)) != NULL) {
int error;
switch (vbr->status) {
case VIRTIO_BLK_S_OK:
error = 0;
break;
case VIRTIO_BLK_S_UNSUPP:
error = -ENOTTY;
break;
default:
error = -EIO;
break;
}
if (blk_pc_request(vbr->req)) {
vbr->req->resid_len = vbr->in_hdr.residual;
vbr->req->sense_len = vbr->in_hdr.sense_len;
vbr->req->errors = vbr->in_hdr.errors;
}
__blk_end_request_all(vbr->req, error);
list_del(&vbr->list);
mempool_free(vbr, vblk->pool);
}
/* In case queue is stopped waiting for more buffers. */
blk_start_queue(vblk->disk->queue);
spin_unlock_irqrestore(&vblk->lock, flags);
}
static bool do_req(struct request_queue *q, struct virtio_blk *vblk,
struct request *req)
{
unsigned long num, out = 0, in = 0;
struct virtblk_req *vbr;
vbr = mempool_alloc(vblk->pool, GFP_ATOMIC);
if (!vbr)
/* When another request finishes we'll try again. */
return false;
vbr->req = req;
switch (req->cmd_type) {
case REQ_TYPE_FS:
vbr->out_hdr.type = 0;
vbr->out_hdr.sector = blk_rq_pos(vbr->req);
vbr->out_hdr.ioprio = req_get_ioprio(vbr->req);
break;
case REQ_TYPE_BLOCK_PC:
vbr->out_hdr.type = VIRTIO_BLK_T_SCSI_CMD;
vbr->out_hdr.sector = 0;
vbr->out_hdr.ioprio = req_get_ioprio(vbr->req);
break;
case REQ_TYPE_LINUX_BLOCK:
if (req->cmd[0] == REQ_LB_OP_FLUSH) {
vbr->out_hdr.type = VIRTIO_BLK_T_FLUSH;
vbr->out_hdr.sector = 0;
vbr->out_hdr.ioprio = req_get_ioprio(vbr->req);
break;
}
/*FALLTHRU*/
default:
/* We don't put anything else in the queue. */
BUG();
}
if (blk_barrier_rq(vbr->req))
vbr->out_hdr.type |= VIRTIO_BLK_T_BARRIER;
sg_set_buf(&vblk->sg[out++], &vbr->out_hdr, sizeof(vbr->out_hdr));
/*
* If this is a packet command we need a couple of additional headers.
* Behind the normal outhdr we put a segment with the scsi command
* block, and before the normal inhdr we put the sense data and the
* inhdr with additional status information before the normal inhdr.
*/
if (blk_pc_request(vbr->req))
sg_set_buf(&vblk->sg[out++], vbr->req->cmd, vbr->req->cmd_len);
num = blk_rq_map_sg(q, vbr->req, vblk->sg + out);
if (blk_pc_request(vbr->req)) {
sg_set_buf(&vblk->sg[num + out + in++], vbr->req->sense, 96);
sg_set_buf(&vblk->sg[num + out + in++], &vbr->in_hdr,
sizeof(vbr->in_hdr));
}
sg_set_buf(&vblk->sg[num + out + in++], &vbr->status,
sizeof(vbr->status));
if (num) {
if (rq_data_dir(vbr->req) == WRITE) {
vbr->out_hdr.type |= VIRTIO_BLK_T_OUT;
out += num;
} else {
vbr->out_hdr.type |= VIRTIO_BLK_T_IN;
in += num;
}
}
if (vblk->vq->vq_ops->add_buf(vblk->vq, vblk->sg, out, in, vbr) < 0) {
mempool_free(vbr, vblk->pool);
return false;
}
list_add_tail(&vbr->list, &vblk->reqs);
return true;
}
static void do_virtblk_request(struct request_queue *q)
{
struct virtio_blk *vblk = q->queuedata;
struct request *req;
unsigned int issued = 0;
while ((req = blk_peek_request(q)) != NULL) {
BUG_ON(req->nr_phys_segments + 2 > vblk->sg_elems);
/* If this request fails, stop queue and wait for something to
finish to restart it. */
if (!do_req(q, vblk, req)) {
blk_stop_queue(q);
break;
}
blk_start_request(req);
issued++;
}
if (issued)
vblk->vq->vq_ops->kick(vblk->vq);
}
static void virtblk_prepare_flush(struct request_queue *q, struct request *req)
{
req->cmd_type = REQ_TYPE_LINUX_BLOCK;
req->cmd[0] = REQ_LB_OP_FLUSH;
}
static int virtblk_ioctl(struct block_device *bdev, fmode_t mode,
unsigned cmd, unsigned long data)
{
struct gendisk *disk = bdev->bd_disk;
struct virtio_blk *vblk = disk->private_data;
/*
* Only allow the generic SCSI ioctls if the host can support it.
*/
if (!virtio_has_feature(vblk->vdev, VIRTIO_BLK_F_SCSI))
return -ENOTTY;
return scsi_cmd_ioctl(disk->queue, disk, mode, cmd,
(void __user *)data);
}
/* We provide getgeo only to please some old bootloader/partitioning tools */
static int virtblk_getgeo(struct block_device *bd, struct hd_geometry *geo)
{
struct virtio_blk *vblk = bd->bd_disk->private_data;
struct virtio_blk_geometry vgeo;
int err;
/* see if the host passed in geometry config */
err = virtio_config_val(vblk->vdev, VIRTIO_BLK_F_GEOMETRY,
offsetof(struct virtio_blk_config, geometry),
&vgeo);
if (!err) {
geo->heads = vgeo.heads;
geo->sectors = vgeo.sectors;
geo->cylinders = vgeo.cylinders;
} else {
/* some standard values, similar to sd */
geo->heads = 1 << 6;
geo->sectors = 1 << 5;
geo->cylinders = get_capacity(bd->bd_disk) >> 11;
}
return 0;
}
static const struct block_device_operations virtblk_fops = {
.locked_ioctl = virtblk_ioctl,
.owner = THIS_MODULE,
.getgeo = virtblk_getgeo,
};
static int index_to_minor(int index)
{
return index << PART_BITS;
}
static int __devinit virtblk_probe(struct virtio_device *vdev)
{
struct virtio_blk *vblk;
int err;
u64 cap;
u32 v;
u32 blk_size, sg_elems;
if (index_to_minor(index) >= 1 << MINORBITS)
return -ENOSPC;
/* We need to know how many segments before we allocate. */
err = virtio_config_val(vdev, VIRTIO_BLK_F_SEG_MAX,
offsetof(struct virtio_blk_config, seg_max),
&sg_elems);
if (err)
sg_elems = 1;
/* We need an extra sg elements at head and tail. */
sg_elems += 2;
vdev->priv = vblk = kmalloc(sizeof(*vblk) +
sizeof(vblk->sg[0]) * sg_elems, GFP_KERNEL);
if (!vblk) {
err = -ENOMEM;
goto out;
}
INIT_LIST_HEAD(&vblk->reqs);
spin_lock_init(&vblk->lock);
vblk->vdev = vdev;
vblk->sg_elems = sg_elems;
sg_init_table(vblk->sg, vblk->sg_elems);
/* We expect one virtqueue, for output. */
vblk->vq = virtio_find_single_vq(vdev, blk_done, "requests");
if (IS_ERR(vblk->vq)) {
err = PTR_ERR(vblk->vq);
goto out_free_vblk;
}
vblk->pool = mempool_create_kmalloc_pool(1,sizeof(struct virtblk_req));
if (!vblk->pool) {
err = -ENOMEM;
goto out_free_vq;
}
/* FIXME: How many partitions? How long is a piece of string? */
vblk->disk = alloc_disk(1 << PART_BITS);
if (!vblk->disk) {
err = -ENOMEM;
goto out_mempool;
}
vblk->disk->queue = blk_init_queue(do_virtblk_request, &vblk->lock);
if (!vblk->disk->queue) {
err = -ENOMEM;
goto out_put_disk;
}
vblk->disk->queue->queuedata = vblk;
if (index < 26) {
sprintf(vblk->disk->disk_name, "vd%c", 'a' + index % 26);
} else if (index < (26 + 1) * 26) {
sprintf(vblk->disk->disk_name, "vd%c%c",
'a' + index / 26 - 1, 'a' + index % 26);
} else {
const unsigned int m1 = (index / 26 - 1) / 26 - 1;
const unsigned int m2 = (index / 26 - 1) % 26;
const unsigned int m3 = index % 26;
sprintf(vblk->disk->disk_name, "vd%c%c%c",
'a' + m1, 'a' + m2, 'a' + m3);
}
vblk->disk->major = major;
vblk->disk->first_minor = index_to_minor(index);
vblk->disk->private_data = vblk;
vblk->disk->fops = &virtblk_fops;
vblk->disk->driverfs_dev = &vdev->dev;
index++;
/* If barriers are supported, tell block layer that queue is ordered */
if (virtio_has_feature(vdev, VIRTIO_BLK_F_FLUSH))
blk_queue_ordered(vblk->disk->queue, QUEUE_ORDERED_DRAIN_FLUSH,
virtblk_prepare_flush);
else if (virtio_has_feature(vdev, VIRTIO_BLK_F_BARRIER))
blk_queue_ordered(vblk->disk->queue, QUEUE_ORDERED_TAG, NULL);
/* If disk is read-only in the host, the guest should obey */
if (virtio_has_feature(vdev, VIRTIO_BLK_F_RO))
set_disk_ro(vblk->disk, 1);
/* Host must always specify the capacity. */
vdev->config->get(vdev, offsetof(struct virtio_blk_config, capacity),
&cap, sizeof(cap));
/* If capacity is too big, truncate with warning. */
if ((sector_t)cap != cap) {
dev_warn(&vdev->dev, "Capacity %llu too large: truncating\n",
(unsigned long long)cap);
cap = (sector_t)-1;
}
set_capacity(vblk->disk, cap);
/* We can handle whatever the host told us to handle. */
blk_queue_max_phys_segments(vblk->disk->queue, vblk->sg_elems-2);
blk_queue_max_hw_segments(vblk->disk->queue, vblk->sg_elems-2);
/* No need to bounce any requests */
blk_queue_bounce_limit(vblk->disk->queue, BLK_BOUNCE_ANY);
/* No real sector limit. */
blk_queue_max_sectors(vblk->disk->queue, -1U);
/* Host can optionally specify maximum segment size and number of
* segments. */
err = virtio_config_val(vdev, VIRTIO_BLK_F_SIZE_MAX,
offsetof(struct virtio_blk_config, size_max),
&v);
if (!err)
blk_queue_max_segment_size(vblk->disk->queue, v);
else
blk_queue_max_segment_size(vblk->disk->queue, -1U);
/* Host can optionally specify the block size of the device */
err = virtio_config_val(vdev, VIRTIO_BLK_F_BLK_SIZE,
offsetof(struct virtio_blk_config, blk_size),
&blk_size);
if (!err)
blk_queue_logical_block_size(vblk->disk->queue, blk_size);
add_disk(vblk->disk);
return 0;
out_put_disk:
put_disk(vblk->disk);
out_mempool:
mempool_destroy(vblk->pool);
out_free_vq:
vdev->config->del_vqs(vdev);
out_free_vblk:
kfree(vblk);
out:
return err;
}
static void __devexit virtblk_remove(struct virtio_device *vdev)
{
struct virtio_blk *vblk = vdev->priv;
/* Nothing should be pending. */
BUG_ON(!list_empty(&vblk->reqs));
/* Stop all the virtqueues. */
vdev->config->reset(vdev);
del_gendisk(vblk->disk);
blk_cleanup_queue(vblk->disk->queue);
put_disk(vblk->disk);
mempool_destroy(vblk->pool);
vdev->config->del_vqs(vdev);
kfree(vblk);
}
static struct virtio_device_id id_table[] = {
{ VIRTIO_ID_BLOCK, VIRTIO_DEV_ANY_ID },
{ 0 },
};
static unsigned int features[] = {
VIRTIO_BLK_F_BARRIER, VIRTIO_BLK_F_SEG_MAX, VIRTIO_BLK_F_SIZE_MAX,
VIRTIO_BLK_F_GEOMETRY, VIRTIO_BLK_F_RO, VIRTIO_BLK_F_BLK_SIZE,
VIRTIO_BLK_F_SCSI, VIRTIO_BLK_F_FLUSH
};
/*
* virtio_blk causes spurious section mismatch warning by
* simultaneously referring to a __devinit and a __devexit function.
* Use __refdata to avoid this warning.
*/
static struct virtio_driver __refdata virtio_blk = {
.feature_table = features,
.feature_table_size = ARRAY_SIZE(features),
.driver.name = KBUILD_MODNAME,
.driver.owner = THIS_MODULE,
.id_table = id_table,
.probe = virtblk_probe,
.remove = __devexit_p(virtblk_remove),
};
static int __init init(void)
{
major = register_blkdev(0, "virtblk");
if (major < 0)
return major;
return register_virtio_driver(&virtio_blk);
}
static void __exit fini(void)
{
unregister_blkdev(major, "virtblk");
unregister_virtio_driver(&virtio_blk);
}
module_init(init);
module_exit(fini);
MODULE_DEVICE_TABLE(virtio, id_table);
MODULE_DESCRIPTION("Virtio block driver");
MODULE_LICENSE("GPL");
