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|
//#define DEBUG
#include <linux/spinlock.h>
#include <linux/slab.h>
#include <linux/blkdev.h>
#include <linux/hdreg.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/virtio.h>
#include <linux/virtio_blk.h>
#include <linux/scatterlist.h>
#include <linux/string_helpers.h>
#include <scsi/scsi_cmnd.h>
#include <linux/idr.h>
#include <linux/blk-mq.h>
#include <linux/numa.h>
#define PART_BITS 4
static int major;
static DEFINE_IDA(vd_index_ida);
static struct workqueue_struct *virtblk_wq;
struct virtio_blk
{
struct virtio_device *vdev;
struct virtqueue *vq;
spinlock_t vq_lock;
/* The disk structure for the kernel. */
struct gendisk *disk;
/* Process context for config space updates */
struct work_struct config_work;
/* Lock for config space updates */
struct mutex config_lock;
/* enable config space updates */
bool config_enable;
/* What host tells us, plus 2 for header & tailer. */
unsigned int sg_elems;
/* Ida index - used to track minor number allocations. */
int index;
};
struct virtblk_req
{
struct request *req;
struct virtio_blk_outhdr out_hdr;
struct virtio_scsi_inhdr in_hdr;
u8 status;
struct scatterlist sg[];
};
static inline int virtblk_result(struct virtblk_req *vbr)
{
switch (vbr->status) {
case VIRTIO_BLK_S_OK:
return 0;
case VIRTIO_BLK_S_UNSUPP:
return -ENOTTY;
default:
return -EIO;
}
}
static int __virtblk_add_req(struct virtqueue *vq,
struct virtblk_req *vbr,
struct scatterlist *data_sg,
bool have_data)
{
struct scatterlist hdr, status, cmd, sense, inhdr, *sgs[6];
unsigned int num_out = 0, num_in = 0;
int type = vbr->out_hdr.type & ~VIRTIO_BLK_T_OUT;
sg_init_one(&hdr, &vbr->out_hdr, sizeof(vbr->out_hdr));
sgs[num_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.
*/
if (type == VIRTIO_BLK_T_SCSI_CMD) {
sg_init_one(&cmd, vbr->req->cmd, vbr->req->cmd_len);
sgs[num_out++] = &cmd;
}
if (have_data) {
if (vbr->out_hdr.type & VIRTIO_BLK_T_OUT)
sgs[num_out++] = data_sg;
else
sgs[num_out + num_in++] = data_sg;
}
if (type == VIRTIO_BLK_T_SCSI_CMD) {
sg_init_one(&sense, vbr->req->sense, SCSI_SENSE_BUFFERSIZE);
sgs[num_out + num_in++] = &sense;
sg_init_one(&inhdr, &vbr->in_hdr, sizeof(vbr->in_hdr));
sgs[num_out + num_in++] = &inhdr;
}
sg_init_one(&status, &vbr->status, sizeof(vbr->status));
sgs[num_out + num_in++] = &status;
return virtqueue_add_sgs(vq, sgs, num_out, num_in, vbr, GFP_ATOMIC);
}
static inline void virtblk_request_done(struct virtblk_req *vbr)
{
struct request *req = vbr->req;
int error = virtblk_result(vbr);
if (req->cmd_type == REQ_TYPE_BLOCK_PC) {
req->resid_len = vbr->in_hdr.residual;
req->sense_len = vbr->in_hdr.sense_len;
req->errors = vbr->in_hdr.errors;
} else if (req->cmd_type == REQ_TYPE_SPECIAL) {
req->errors = (error != 0);
}
blk_mq_end_io(req, error);
}
static void virtblk_done(struct virtqueue *vq)
{
struct virtio_blk *vblk = vq->vdev->priv;
bool req_done = false;
struct virtblk_req *vbr;
unsigned long flags;
unsigned int len;
spin_lock_irqsave(&vblk->vq_lock, flags);
do {
virtqueue_disable_cb(vq);
while ((vbr = virtqueue_get_buf(vblk->vq, &len)) != NULL) {
virtblk_request_done(vbr);
req_done = true;
}
} while (!virtqueue_enable_cb(vq));
spin_unlock_irqrestore(&vblk->vq_lock, flags);
/* In case queue is stopped waiting for more buffers. */
if (req_done)
blk_mq_start_stopped_hw_queues(vblk->disk->queue);
}
static int virtio_queue_rq(struct blk_mq_hw_ctx *hctx, struct request *req)
{
struct virtio_blk *vblk = hctx->queue->queuedata;
struct virtblk_req *vbr = req->special;
unsigned long flags;
unsigned int num;
const bool last = (req->cmd_flags & REQ_END) != 0;
BUG_ON(req->nr_phys_segments + 2 > vblk->sg_elems);
vbr->req = req;
if (req->cmd_flags & REQ_FLUSH) {
vbr->out_hdr.type = VIRTIO_BLK_T_FLUSH;
vbr->out_hdr.sector = 0;
vbr->out_hdr.ioprio = req_get_ioprio(vbr->req);
} else {
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_SPECIAL:
vbr->out_hdr.type = VIRTIO_BLK_T_GET_ID;
vbr->out_hdr.sector = 0;
vbr->out_hdr.ioprio = req_get_ioprio(vbr->req);
break;
default:
/* We don't put anything else in the queue. */
BUG();
}
}
num = blk_rq_map_sg(hctx->queue, vbr->req, vbr->sg);
if (num) {
if (rq_data_dir(vbr->req) == WRITE)
vbr->out_hdr.type |= VIRTIO_BLK_T_OUT;
else
vbr->out_hdr.type |= VIRTIO_BLK_T_IN;
}
spin_lock_irqsave(&vblk->vq_lock, flags);
if (__virtblk_add_req(vblk->vq, vbr, vbr->sg, num) < 0) {
spin_unlock_irqrestore(&vblk->vq_lock, flags);
blk_mq_stop_hw_queue(hctx);
virtqueue_kick(vblk->vq);
return BLK_MQ_RQ_QUEUE_BUSY;
}
spin_unlock_irqrestore(&vblk->vq_lock, flags);
if (last)
virtqueue_kick(vblk->vq);
return BLK_MQ_RQ_QUEUE_OK;
}
/* return id (s/n) string for *disk to *id_str
*/
static int virtblk_get_id(struct gendisk *disk, char *id_str)
{
struct virtio_blk *vblk = disk->private_data;
struct request *req;
struct bio *bio;
int err;
bio = bio_map_kern(vblk->disk->queue, id_str, VIRTIO_BLK_ID_BYTES,
GFP_KERNEL);
if (IS_ERR(bio))
return PTR_ERR(bio);
req = blk_make_request(vblk->disk->queue, bio, GFP_KERNEL);
if (IS_ERR(req)) {
bio_put(bio);
return PTR_ERR(req);
}
req->cmd_type = REQ_TYPE_SPECIAL;
err = blk_execute_rq(vblk->disk->queue, vblk->disk, req, false);
blk_put_request(req);
return err;
}
static int virtblk_ioctl(struct block_device *bdev, fmode_t mode,
unsigned int 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_blk_ioctl(bdev, 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 = {
.ioctl = virtblk_ioctl,
.owner = THIS_MODULE,
.getgeo = virtblk_getgeo,
};
static int index_to_minor(int index)
{
return index << PART_BITS;
}
static int minor_to_index(int minor)
{
return minor >> PART_BITS;
}
static ssize_t virtblk_serial_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct gendisk *disk = dev_to_disk(dev);
int err;
/* sysfs gives us a PAGE_SIZE buffer */
BUILD_BUG_ON(PAGE_SIZE < VIRTIO_BLK_ID_BYTES);
buf[VIRTIO_BLK_ID_BYTES] = '\0';
err = virtblk_get_id(disk, buf);
if (!err)
return strlen(buf);
if (err == -EIO) /* Unsupported? Make it empty. */
return 0;
return err;
}
DEVICE_ATTR(serial, S_IRUGO, virtblk_serial_show, NULL);
static void virtblk_config_changed_work(struct work_struct *work)
{
struct virtio_blk *vblk =
container_of(work, struct virtio_blk, config_work);
struct virtio_device *vdev = vblk->vdev;
struct request_queue *q = vblk->disk->queue;
char cap_str_2[10], cap_str_10[10];
char *envp[] = { "RESIZE=1", NULL };
u64 capacity, size;
mutex_lock(&vblk->config_lock);
if (!vblk->config_enable)
goto done;
/* Host must always specify the capacity. */
vdev->config->get(vdev, offsetof(struct virtio_blk_config, capacity),
&capacity, sizeof(capacity));
/* If capacity is too big, truncate with warning. */
if ((sector_t)capacity != capacity) {
dev_warn(&vdev->dev, "Capacity %llu too large: truncating\n",
(unsigned long long)capacity);
capacity = (sector_t)-1;
}
size = capacity * queue_logical_block_size(q);
string_get_size(size, STRING_UNITS_2, cap_str_2, sizeof(cap_str_2));
string_get_size(size, STRING_UNITS_10, cap_str_10, sizeof(cap_str_10));
dev_notice(&vdev->dev,
"new size: %llu %d-byte logical blocks (%s/%s)\n",
(unsigned long long)capacity,
queue_logical_block_size(q),
cap_str_10, cap_str_2);
set_capacity(vblk->disk, capacity);
revalidate_disk(vblk->disk);
kobject_uevent_env(&disk_to_dev(vblk->disk)->kobj, KOBJ_CHANGE, envp);
done:
mutex_unlock(&vblk->config_lock);
}
static void virtblk_config_changed(struct virtio_device *vdev)
{
struct virtio_blk *vblk = vdev->priv;
queue_work(virtblk_wq, &vblk->config_work);
}
static int init_vq(struct virtio_blk *vblk)
{
int err = 0;
/* We expect one virtqueue, for output. */
vblk->vq = virtio_find_single_vq(vblk->vdev, virtblk_done, "requests");
if (IS_ERR(vblk->vq))
err = PTR_ERR(vblk->vq);
return err;
}
/*
* Legacy naming scheme used for virtio devices. We are stuck with it for
* virtio blk but don't ever use it for any new driver.
*/
static int virtblk_name_format(char *prefix, int index, char *buf, int buflen)
{
const int base = 'z' - 'a' + 1;
char *begin = buf + strlen(prefix);
char *end = buf + buflen;
char *p;
int unit;
p = end - 1;
*p = '\0';
unit = base;
do {
if (p == begin)
return -EINVAL;
*--p = 'a' + (index % unit);
index = (index / unit) - 1;
} while (index >= 0);
memmove(begin, p, end - p);
memcpy(buf, prefix, strlen(prefix));
return 0;
}
static int virtblk_get_cache_mode(struct virtio_device *vdev)
{
u8 writeback;
int err;
err = virtio_config_val(vdev, VIRTIO_BLK_F_CONFIG_WCE,
offsetof(struct virtio_blk_config, wce),
&writeback);
if (err)
writeback = virtio_has_feature(vdev, VIRTIO_BLK_F_WCE);
return writeback;
}
static void virtblk_update_cache_mode(struct virtio_device *vdev)
{
u8 writeback = virtblk_get_cache_mode(vdev);
struct virtio_blk *vblk = vdev->priv;
if (writeback)
blk_queue_flush(vblk->disk->queue, REQ_FLUSH);
else
blk_queue_flush(vblk->disk->queue, 0);
revalidate_disk(vblk->disk);
}
static const char *const virtblk_cache_types[] = {
"write through", "write back"
};
static ssize_t
virtblk_cache_type_store(struct device *dev, struct device_attribute *attr,
const char *buf, size_t count)
{
struct gendisk *disk = dev_to_disk(dev);
struct virtio_blk *vblk = disk->private_data;
struct virtio_device *vdev = vblk->vdev;
int i;
u8 writeback;
BUG_ON(!virtio_has_feature(vblk->vdev, VIRTIO_BLK_F_CONFIG_WCE));
for (i = ARRAY_SIZE(virtblk_cache_types); --i >= 0; )
if (sysfs_streq(buf, virtblk_cache_types[i]))
break;
if (i < 0)
return -EINVAL;
writeback = i;
vdev->config->set(vdev,
offsetof(struct virtio_blk_config, wce),
&writeback, sizeof(writeback));
virtblk_update_cache_mode(vdev);
return count;
}
static ssize_t
virtblk_cache_type_show(struct device *dev, struct device_attribute *attr,
char *buf)
{
struct gendisk *disk = dev_to_disk(dev);
struct virtio_blk *vblk = disk->private_data;
u8 writeback = virtblk_get_cache_mode(vblk->vdev);
BUG_ON(writeback >= ARRAY_SIZE(virtblk_cache_types));
return snprintf(buf, 40, "%s\n", virtblk_cache_types[writeback]);
}
static const struct device_attribute dev_attr_cache_type_ro =
__ATTR(cache_type, S_IRUGO,
virtblk_cache_type_show, NULL);
static const struct device_attribute dev_attr_cache_type_rw =
__ATTR(cache_type, S_IRUGO|S_IWUSR,
virtblk_cache_type_show, virtblk_cache_type_store);
static struct blk_mq_ops virtio_mq_ops = {
.queue_rq = virtio_queue_rq,
.map_queue = blk_mq_map_queue,
.alloc_hctx = blk_mq_alloc_single_hw_queue,
.free_hctx = blk_mq_free_single_hw_queue,
};
static struct blk_mq_reg virtio_mq_reg = {
.ops = &virtio_mq_ops,
.nr_hw_queues = 1,
.queue_depth = 64,
.numa_node = NUMA_NO_NODE,
.flags = BLK_MQ_F_SHOULD_MERGE,
};
static void virtblk_init_vbr(void *data, struct blk_mq_hw_ctx *hctx,
struct request *rq, unsigned int nr)
{
struct virtio_blk *vblk = data;
struct virtblk_req *vbr = rq->special;
sg_init_table(vbr->sg, vblk->sg_elems);
}
static int virtblk_probe(struct virtio_device *vdev)
{
struct virtio_blk *vblk;
struct request_queue *q;
int err, index;
u64 cap;
u32 v, blk_size, sg_elems, opt_io_size;
u16 min_io_size;
u8 physical_block_exp, alignment_offset;
err = ida_simple_get(&vd_index_ida, 0, minor_to_index(1 << MINORBITS),
GFP_KERNEL);
if (err < 0)
goto out;
index = err;
/* 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);
/* We need at least one SG element, whatever they say. */
if (err || !sg_elems)
sg_elems = 1;
/* We need an extra sg elements at head and tail. */
sg_elems += 2;
vdev->priv = vblk = kmalloc(sizeof(*vblk), GFP_KERNEL);
if (!vblk) {
err = -ENOMEM;
goto out_free_index;
}
vblk->vdev = vdev;
vblk->sg_elems = sg_elems;
mutex_init(&vblk->config_lock);
INIT_WORK(&vblk->config_work, virtblk_config_changed_work);
vblk->config_enable = true;
err = init_vq(vblk);
if (err)
goto out_free_vblk;
spin_lock_init(&vblk->vq_lock);
/* 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_free_vq;
}
virtio_mq_reg.cmd_size =
sizeof(struct virtblk_req) +
sizeof(struct scatterlist) * sg_elems;
q = vblk->disk->queue = blk_mq_init_queue(&virtio_mq_reg, vblk);
if (!q) {
err = -ENOMEM;
goto out_put_disk;
}
blk_mq_init_commands(q, virtblk_init_vbr, vblk);
q->queuedata = vblk;
virtblk_name_format("vd", index, vblk->disk->disk_name, DISK_NAME_LEN);
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;
vblk->index = index;
/* configure queue flush support */
virtblk_update_cache_mode(vdev);
/* 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_segments(q, vblk->sg_elems-2);
/* No need to bounce any requests */
blk_queue_bounce_limit(q, BLK_BOUNCE_ANY);
/* No real sector limit. */
blk_queue_max_hw_sectors(q, -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(q, v);
else
blk_queue_max_segment_size(q, -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(q, blk_size);
else
blk_size = queue_logical_block_size(q);
/* Use topology information if available */
err = virtio_config_val(vdev, VIRTIO_BLK_F_TOPOLOGY,
offsetof(struct virtio_blk_config, physical_block_exp),
&physical_block_exp);
if (!err && physical_block_exp)
blk_queue_physical_block_size(q,
blk_size * (1 << physical_block_exp));
err = virtio_config_val(vdev, VIRTIO_BLK_F_TOPOLOGY,
offsetof(struct virtio_blk_config, alignment_offset),
&alignment_offset);
if (!err && alignment_offset)
blk_queue_alignment_offset(q, blk_size * alignment_offset);
err = virtio_config_val(vdev, VIRTIO_BLK_F_TOPOLOGY,
offsetof(struct virtio_blk_config, min_io_size),
&min_io_size);
if (!err && min_io_size)
blk_queue_io_min(q, blk_size * min_io_size);
err = virtio_config_val(vdev, VIRTIO_BLK_F_TOPOLOGY,
offsetof(struct virtio_blk_config, opt_io_size),
&opt_io_size);
if (!err && opt_io_size)
blk_queue_io_opt(q, blk_size * opt_io_size);
add_disk(vblk->disk);
err = device_create_file(disk_to_dev(vblk->disk), &dev_attr_serial);
if (err)
goto out_del_disk;
if (virtio_has_feature(vdev, VIRTIO_BLK_F_CONFIG_WCE))
err = device_create_file(disk_to_dev(vblk->disk),
&dev_attr_cache_type_rw);
else
err = device_create_file(disk_to_dev(vblk->disk),
&dev_attr_cache_type_ro);
if (err)
goto out_del_disk;
return 0;
out_del_disk:
del_gendisk(vblk->disk);
blk_cleanup_queue(vblk->disk->queue);
out_put_disk:
put_disk(vblk->disk);
out_free_vq:
vdev->config->del_vqs(vdev);
out_free_vblk:
kfree(vblk);
out_free_index:
ida_simple_remove(&vd_index_ida, index);
out:
return err;
}
static void virtblk_remove(struct virtio_device *vdev)
{
struct virtio_blk *vblk = vdev->priv;
int index = vblk->index;
int refc;
/* Prevent config work handler from accessing the device. */
mutex_lock(&vblk->config_lock);
vblk->config_enable = false;
mutex_unlock(&vblk->config_lock);
del_gendisk(vblk->disk);
blk_cleanup_queue(vblk->disk->queue);
/* Stop all the virtqueues. */
vdev->config->reset(vdev);
flush_work(&vblk->config_work);
refc = atomic_read(&disk_to_dev(vblk->disk)->kobj.kref.refcount);
put_disk(vblk->disk);
vdev->config->del_vqs(vdev);
kfree(vblk);
/* Only free device id if we don't have any users */
if (refc == 1)
ida_simple_remove(&vd_index_ida, index);
}
#ifdef CONFIG_PM
static int virtblk_freeze(struct virtio_device *vdev)
{
struct virtio_blk *vblk = vdev->priv;
/* Ensure we don't receive any more interrupts */
vdev->config->reset(vdev);
/* Prevent config work handler from accessing the device. */
mutex_lock(&vblk->config_lock);
vblk->config_enable = false;
mutex_unlock(&vblk->config_lock);
flush_work(&vblk->config_work);
blk_mq_stop_hw_queues(vblk->disk->queue);
vdev->config->del_vqs(vdev);
return 0;
}
static int virtblk_restore(struct virtio_device *vdev)
{
struct virtio_blk *vblk = vdev->priv;
int ret;
vblk->config_enable = true;
ret = init_vq(vdev->priv);
if (!ret)
blk_mq_start_stopped_hw_queues(vblk->disk->queue);
return ret;
}
#endif
static const struct virtio_device_id id_table[] = {
{ VIRTIO_ID_BLOCK, VIRTIO_DEV_ANY_ID },
{ 0 },
};
static unsigned int features[] = {
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_WCE, VIRTIO_BLK_F_TOPOLOGY, VIRTIO_BLK_F_CONFIG_WCE
};
static struct virtio_driver 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 = virtblk_remove,
.config_changed = virtblk_config_changed,
#ifdef CONFIG_PM
.freeze = virtblk_freeze,
.restore = virtblk_restore,
#endif
};
static int __init init(void)
{
int error;
virtblk_wq = alloc_workqueue("virtio-blk", 0, 0);
if (!virtblk_wq)
return -ENOMEM;
major = register_blkdev(0, "virtblk");
if (major < 0) {
error = major;
goto out_destroy_workqueue;
}
error = register_virtio_driver(&virtio_blk);
if (error)
goto out_unregister_blkdev;
return 0;
out_unregister_blkdev:
unregister_blkdev(major, "virtblk");
out_destroy_workqueue:
destroy_workqueue(virtblk_wq);
return error;
}
static void __exit fini(void)
{
unregister_blkdev(major, "virtblk");
unregister_virtio_driver(&virtio_blk);
destroy_workqueue(virtblk_wq);
}
module_init(init);
module_exit(fini);
MODULE_DEVICE_TABLE(virtio, id_table);
MODULE_DESCRIPTION("Virtio block driver");
MODULE_LICENSE("GPL");
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