--- /dev/null
+//#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/virtio_blk.h>
+
+static unsigned char virtblk_index = 'a';
+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;
+
+ /* Scatterlist: can be too big for stack. */
+ struct scatterlist sg[3+MAX_PHYS_SEGMENTS];
+};
+
+struct virtblk_req
+{
+ struct list_head list;
+ struct request *req;
+ struct virtio_blk_outhdr out_hdr;
+ struct virtio_blk_inhdr in_hdr;
+};
+
+static bool 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 uptodate;
+ switch (vbr->in_hdr.status) {
+ case VIRTIO_BLK_S_OK:
+ uptodate = 1;
+ break;
+ case VIRTIO_BLK_S_UNSUPP:
+ uptodate = -ENOTTY;
+ break;
+ default:
+ uptodate = 0;
+ break;
+ }
+
+ end_dequeued_request(vbr->req, uptodate);
+ 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);
+ return true;
+}
+
+static bool do_req(struct request_queue *q, struct virtio_blk *vblk,
+ struct request *req)
+{
+ unsigned long num, out, in;
+ 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;
+ if (blk_fs_request(vbr->req)) {
+ vbr->out_hdr.type = 0;
+ vbr->out_hdr.sector = vbr->req->sector;
+ vbr->out_hdr.ioprio = vbr->req->ioprio;
+ } else if (blk_pc_request(vbr->req)) {
+ vbr->out_hdr.type = VIRTIO_BLK_T_SCSI_CMD;
+ vbr->out_hdr.sector = 0;
+ vbr->out_hdr.ioprio = vbr->req->ioprio;
+ } else {
+ /* We don't put anything else in the queue. */
+ BUG();
+ }
+
+ if (blk_barrier_rq(vbr->req))
+ vbr->out_hdr.type |= VIRTIO_BLK_T_BARRIER;
+
+ /* We have to zero this, otherwise blk_rq_map_sg gets upset. */
+ memset(vblk->sg, 0, sizeof(vblk->sg));
+ sg_set_buf(&vblk->sg[0], &vbr->out_hdr, sizeof(vbr->out_hdr));
+ num = blk_rq_map_sg(q, vbr->req, vblk->sg+1);
+ sg_set_buf(&vblk->sg[num+1], &vbr->in_hdr, sizeof(vbr->in_hdr));
+
+ if (rq_data_dir(vbr->req) == WRITE) {
+ vbr->out_hdr.type |= VIRTIO_BLK_T_OUT;
+ out = 1 + num;
+ in = 1;
+ } else {
+ vbr->out_hdr.type |= VIRTIO_BLK_T_IN;
+ out = 1;
+ in = 1 + num;
+ }
+
+ if (vblk->vq->vq_ops->add_buf(vblk->vq, vblk->sg, out, in, vbr)) {
+ 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 = NULL;
+ struct request *req;
+ unsigned int issued = 0;
+
+ while ((req = elv_next_request(q)) != NULL) {
+ vblk = req->rq_disk->private_data;
+ BUG_ON(req->nr_phys_segments > ARRAY_SIZE(vblk->sg));
+
+ /* 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;
+ }
+ blkdev_dequeue_request(req);
+ issued++;
+ }
+
+ if (issued)
+ vblk->vq->vq_ops->kick(vblk->vq);
+}
+
+static int virtblk_ioctl(struct inode *inode, struct file *filp,
+ unsigned cmd, unsigned long data)
+{
+ return scsi_cmd_ioctl(filp, inode->i_bdev->bd_disk->queue,
+ inode->i_bdev->bd_disk, cmd,
+ (void __user *)data);
+}
+
+static struct block_device_operations virtblk_fops = {
+ .ioctl = virtblk_ioctl,
+ .owner = THIS_MODULE,
+};
+
+static int virtblk_probe(struct virtio_device *vdev)
+{
+ struct virtio_blk *vblk;
+ int err, major;
+ void *token;
+ unsigned int len;
+ u64 cap;
+ u32 v;
+
+ vdev->priv = vblk = kmalloc(sizeof(*vblk), GFP_KERNEL);
+ if (!vblk) {
+ err = -ENOMEM;
+ goto out;
+ }
+
+ INIT_LIST_HEAD(&vblk->reqs);
+ spin_lock_init(&vblk->lock);
+ vblk->vdev = vdev;
+
+ /* We expect one virtqueue, for output. */
+ vblk->vq = vdev->config->find_vq(vdev, blk_done);
+ 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;
+ }
+
+ major = register_blkdev(0, "virtblk");
+ if (major < 0) {
+ err = major;
+ goto out_mempool;
+ }
+
+ /* FIXME: How many partitions? How long is a piece of string? */
+ vblk->disk = alloc_disk(1 << 4);
+ if (!vblk->disk) {
+ err = -ENOMEM;
+ goto out_unregister_blkdev;
+ }
+
+ vblk->disk->queue = blk_init_queue(do_virtblk_request, &vblk->lock);
+ if (!vblk->disk->queue) {
+ err = -ENOMEM;
+ goto out_put_disk;
+ }
+
+ sprintf(vblk->disk->disk_name, "vd%c", virtblk_index++);
+ vblk->disk->major = major;
+ vblk->disk->first_minor = 0;
+ vblk->disk->private_data = vblk;
+ vblk->disk->fops = &virtblk_fops;
+
+ /* If barriers are supported, tell block layer that queue is ordered */
+ token = vdev->config->find(vdev, VIRTIO_CONFIG_BLK_F, &len);
+ if (virtio_use_bit(vdev, token, len, VIRTIO_BLK_F_BARRIER))
+ blk_queue_ordered(vblk->disk->queue, QUEUE_ORDERED_TAG, NULL);
+
+ err = virtio_config_val(vdev, VIRTIO_CONFIG_BLK_F_CAPACITY, &cap);
+ if (err) {
+ dev_err(&vdev->dev, "Bad/missing capacity in config\n");
+ goto out_put_disk;
+ }
+
+ /* 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);
+
+ err = virtio_config_val(vdev, VIRTIO_CONFIG_BLK_F_SIZE_MAX, &v);
+ if (!err)
+ blk_queue_max_segment_size(vblk->disk->queue, v);
+ else if (err != -ENOENT) {
+ dev_err(&vdev->dev, "Bad SIZE_MAX in config\n");
+ goto out_put_disk;
+ }
+
+ err = virtio_config_val(vdev, VIRTIO_CONFIG_BLK_F_SEG_MAX, &v);
+ if (!err)
+ blk_queue_max_hw_segments(vblk->disk->queue, v);
+ else if (err != -ENOENT) {
+ dev_err(&vdev->dev, "Bad SEG_MAX in config\n");
+ goto out_put_disk;
+ }
+
+ add_disk(vblk->disk);
+ return 0;
+
+out_put_disk:
+ put_disk(vblk->disk);
+out_unregister_blkdev:
+ unregister_blkdev(major, "virtblk");
+out_mempool:
+ mempool_destroy(vblk->pool);
+out_free_vq:
+ vdev->config->del_vq(vblk->vq);
+out_free_vblk:
+ kfree(vblk);
+out:
+ return err;
+}
+
+static void virtblk_remove(struct virtio_device *vdev)
+{
+ struct virtio_blk *vblk = vdev->priv;
+ int major = vblk->disk->major;
+
+ BUG_ON(!list_empty(&vblk->reqs));
+ blk_cleanup_queue(vblk->disk->queue);
+ put_disk(vblk->disk);
+ unregister_blkdev(major, "virtblk");
+ mempool_destroy(vblk->pool);
+ kfree(vblk);
+}
+
+static struct virtio_device_id id_table[] = {
+ { VIRTIO_ID_BLOCK, VIRTIO_DEV_ANY_ID },
+ { 0 },
+};
+
+static struct virtio_driver virtio_blk = {
+ .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)
+{
+ return register_virtio_driver(&virtio_blk);
+}
+
+static void __exit fini(void)
+{
+ 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");
projects / linux-2.6 / commitdiff