drivers/block/virtio_blk.c

   1 //#define DEBUG
   2 #include <linux/spinlock.h>
   3 #include <linux/blkdev.h>
   4 #include <linux/hdreg.h>
   5 #include <linux/virtio.h>
   6 #include <linux/virtio_blk.h>
   7 #include <linux/virtio_blk.h>
   8
   9 static unsigned char virtblk_index = 'a';
  10 struct virtio_blk
  11 {
  12         spinlock_t lock;
  13
  14         struct virtio_device *vdev;
  15         struct virtqueue *vq;
  16
  17         /* The disk structure for the kernel. */
  18         struct gendisk *disk;
  19
  20         /* Request tracking. */
  21         struct list_head reqs;
  22
  23         mempool_t *pool;
  24
  25         /* Scatterlist: can be too big for stack. */
  26         struct scatterlist sg[3+MAX_PHYS_SEGMENTS];
  27 };
  28
  29 struct virtblk_req
  30 {
  31         struct list_head list;
  32         struct request *req;
  33         struct virtio_blk_outhdr out_hdr;
  34         struct virtio_blk_inhdr in_hdr;
  35 };
  36
  37 static bool blk_done(struct virtqueue *vq)
  38 {
  39         struct virtio_blk *vblk = vq->vdev->priv;
  40         struct virtblk_req *vbr;
  41         unsigned int len;
  42         unsigned long flags;
  43
  44         spin_lock_irqsave(&vblk->lock, flags);
  45         while ((vbr = vblk->vq->vq_ops->get_buf(vblk->vq, &len)) != NULL) {
  46                 int uptodate;
  47                 switch (vbr->in_hdr.status) {
  48                 case VIRTIO_BLK_S_OK:
  49                         uptodate = 1;
  50                         break;
  51                 case VIRTIO_BLK_S_UNSUPP:
  52                         uptodate = -ENOTTY;
  53                         break;
  54                 default:
  55                         uptodate = 0;
  56                         break;
  57                 }
  58
  59                 end_dequeued_request(vbr->req, uptodate);
  60                 list_del(&vbr->list);
  61                 mempool_free(vbr, vblk->pool);
  62         }
  63         /* In case queue is stopped waiting for more buffers. */
  64         blk_start_queue(vblk->disk->queue);
  65         spin_unlock_irqrestore(&vblk->lock, flags);
  66         return true;
  67 }
  68
  69 static bool do_req(struct request_queue *q, struct virtio_blk *vblk,
  70                    struct request *req)
  71 {
  72         unsigned long num, out, in;
  73         struct virtblk_req *vbr;
  74
  75         vbr = mempool_alloc(vblk->pool, GFP_ATOMIC);
  76         if (!vbr)
  77                 /* When another request finishes we'll try again. */
  78                 return false;
  79
  80         vbr->req = req;
  81         if (blk_fs_request(vbr->req)) {
  82                 vbr->out_hdr.type = 0;
  83                 vbr->out_hdr.sector = vbr->req->sector;
  84                 vbr->out_hdr.ioprio = vbr->req->ioprio;
  85         } else if (blk_pc_request(vbr->req)) {
  86                 vbr->out_hdr.type = VIRTIO_BLK_T_SCSI_CMD;
  87                 vbr->out_hdr.sector = 0;
  88                 vbr->out_hdr.ioprio = vbr->req->ioprio;
  89         } else {
  90                 /* We don't put anything else in the queue. */
  91                 BUG();
  92         }
  93
  94         if (blk_barrier_rq(vbr->req))
  95                 vbr->out_hdr.type |= VIRTIO_BLK_T_BARRIER;
  96
  97         /* We have to zero this, otherwise blk_rq_map_sg gets upset. */
  98         memset(vblk->sg, 0, sizeof(vblk->sg));
  99         sg_set_buf(&vblk->sg[0], &vbr->out_hdr, sizeof(vbr->out_hdr));
 100         num = blk_rq_map_sg(q, vbr->req, vblk->sg+1);
 101         sg_set_buf(&vblk->sg[num+1], &vbr->in_hdr, sizeof(vbr->in_hdr));
 102
 103         if (rq_data_dir(vbr->req) == WRITE) {
 104                 vbr->out_hdr.type |= VIRTIO_BLK_T_OUT;
 105                 out = 1 + num;
 106                 in = 1;
 107         } else {
 108                 vbr->out_hdr.type |= VIRTIO_BLK_T_IN;
 109                 out = 1;
 110                 in = 1 + num;
 111         }
 112
 113         if (vblk->vq->vq_ops->add_buf(vblk->vq, vblk->sg, out, in, vbr)) {
 114                 mempool_free(vbr, vblk->pool);
 115                 return false;
 116         }
 117
 118         list_add_tail(&vbr->list, &vblk->reqs);
 119         return true;
 120 }
 121
 122 static void do_virtblk_request(struct request_queue *q)
 123 {
 124         struct virtio_blk *vblk = NULL;
 125         struct request *req;
 126         unsigned int issued = 0;
 127
 128         while ((req = elv_next_request(q)) != NULL) {
 129                 vblk = req->rq_disk->private_data;
 130                 BUG_ON(req->nr_phys_segments > ARRAY_SIZE(vblk->sg));
 131
 132                 /* If this request fails, stop queue and wait for something to
 133                    finish to restart it. */
 134                 if (!do_req(q, vblk, req)) {
 135                         blk_stop_queue(q);
 136                         break;
 137                 }
 138                 blkdev_dequeue_request(req);
 139                 issued++;
 140         }
 141
 142         if (issued)
 143                 vblk->vq->vq_ops->kick(vblk->vq);
 144 }
 145
 146 static int virtblk_ioctl(struct inode *inode, struct file *filp,
 147                          unsigned cmd, unsigned long data)
 148 {
 149         return scsi_cmd_ioctl(filp, inode->i_bdev->bd_disk->queue,
 150                               inode->i_bdev->bd_disk, cmd,
 151                               (void __user *)data);
 152 }
 153
 154 static struct block_device_operations virtblk_fops = {
 155         .ioctl = virtblk_ioctl,
 156         .owner = THIS_MODULE,
 157 };
 158
 159 static int virtblk_probe(struct virtio_device *vdev)
 160 {
 161         struct virtio_blk *vblk;
 162         int err, major;
 163         void *token;
 164         unsigned int len;
 165         u64 cap;
 166         u32 v;
 167
 168         vdev->priv = vblk = kmalloc(sizeof(*vblk), GFP_KERNEL);
 169         if (!vblk) {
 170                 err = -ENOMEM;
 171                 goto out;
 172         }
 173
 174         INIT_LIST_HEAD(&vblk->reqs);
 175         spin_lock_init(&vblk->lock);
 176         vblk->vdev = vdev;
 177
 178         /* We expect one virtqueue, for output. */
 179         vblk->vq = vdev->config->find_vq(vdev, blk_done);
 180         if (IS_ERR(vblk->vq)) {
 181                 err = PTR_ERR(vblk->vq);
 182                 goto out_free_vblk;
 183         }
 184
 185         vblk->pool = mempool_create_kmalloc_pool(1,sizeof(struct virtblk_req));
 186         if (!vblk->pool) {
 187                 err = -ENOMEM;
 188                 goto out_free_vq;
 189         }
 190
 191         major = register_blkdev(0, "virtblk");
 192         if (major < 0) {
 193                 err = major;
 194                 goto out_mempool;
 195         }
 196
 197         /* FIXME: How many partitions?  How long is a piece of string? */
 198         vblk->disk = alloc_disk(1 << 4);
 199         if (!vblk->disk) {
 200                 err = -ENOMEM;
 201                 goto out_unregister_blkdev;
 202         }
 203
 204         vblk->disk->queue = blk_init_queue(do_virtblk_request, &vblk->lock);
 205         if (!vblk->disk->queue) {
 206                 err = -ENOMEM;
 207                 goto out_put_disk;
 208         }
 209
 210         sprintf(vblk->disk->disk_name, "vd%c", virtblk_index++);
 211         vblk->disk->major = major;
 212         vblk->disk->first_minor = 0;
 213         vblk->disk->private_data = vblk;
 214         vblk->disk->fops = &virtblk_fops;
 215
 216         /* If barriers are supported, tell block layer that queue is ordered */
 217         token = vdev->config->find(vdev, VIRTIO_CONFIG_BLK_F, &len);
 218         if (virtio_use_bit(vdev, token, len, VIRTIO_BLK_F_BARRIER))
 219                 blk_queue_ordered(vblk->disk->queue, QUEUE_ORDERED_TAG, NULL);
 220
 221         err = virtio_config_val(vdev, VIRTIO_CONFIG_BLK_F_CAPACITY, &cap);
 222         if (err) {
 223                 dev_err(&vdev->dev, "Bad/missing capacity in config\n");
 224                 goto out_put_disk;
 225         }
 226
 227         /* If capacity is too big, truncate with warning. */
 228         if ((sector_t)cap != cap) {
 229                 dev_warn(&vdev->dev, "Capacity %llu too large: truncating\n",
 230                          (unsigned long long)cap);
 231                 cap = (sector_t)-1;
 232         }
 233         set_capacity(vblk->disk, cap);
 234
 235         err = virtio_config_val(vdev, VIRTIO_CONFIG_BLK_F_SIZE_MAX, &v);
 236         if (!err)
 237                 blk_queue_max_segment_size(vblk->disk->queue, v);
 238         else if (err != -ENOENT) {
 239                 dev_err(&vdev->dev, "Bad SIZE_MAX in config\n");
 240                 goto out_put_disk;
 241         }
 242
 243         err = virtio_config_val(vdev, VIRTIO_CONFIG_BLK_F_SEG_MAX, &v);
 244         if (!err)
 245                 blk_queue_max_hw_segments(vblk->disk->queue, v);
 246         else if (err != -ENOENT) {
 247                 dev_err(&vdev->dev, "Bad SEG_MAX in config\n");
 248                 goto out_put_disk;
 249         }
 250
 251         add_disk(vblk->disk);
 252         return 0;
 253
 254 out_put_disk:
 255         put_disk(vblk->disk);
 256 out_unregister_blkdev:
 257         unregister_blkdev(major, "virtblk");
 258 out_mempool:
 259         mempool_destroy(vblk->pool);
 260 out_free_vq:
 261         vdev->config->del_vq(vblk->vq);
 262 out_free_vblk:
 263         kfree(vblk);
 264 out:
 265         return err;
 266 }
 267
 268 static void virtblk_remove(struct virtio_device *vdev)
 269 {
 270         struct virtio_blk *vblk = vdev->priv;
 271         int major = vblk->disk->major;
 272
 273         BUG_ON(!list_empty(&vblk->reqs));
 274         blk_cleanup_queue(vblk->disk->queue);
 275         put_disk(vblk->disk);
 276         unregister_blkdev(major, "virtblk");
 277         mempool_destroy(vblk->pool);
 278         kfree(vblk);
 279 }
 280
 281 static struct virtio_device_id id_table[] = {
 282         { VIRTIO_ID_BLOCK, VIRTIO_DEV_ANY_ID },
 283         { 0 },
 284 };
 285
 286 static struct virtio_driver virtio_blk = {
 287         .driver.name =  KBUILD_MODNAME,
 288         .driver.owner = THIS_MODULE,
 289         .id_table =     id_table,
 290         .probe =        virtblk_probe,
 291         .remove =       __devexit_p(virtblk_remove),
 292 };
 293
 294 static int __init init(void)
 295 {
 296         return register_virtio_driver(&virtio_blk);
 297 }
 298
 299 static void __exit fini(void)
 300 {
 301         unregister_virtio_driver(&virtio_blk);
 302 }
 303 module_init(init);
 304 module_exit(fini);
 305
 306 MODULE_DEVICE_TABLE(virtio, id_table);
 307 MODULE_DESCRIPTION("Virtio block driver");
 308 MODULE_LICENSE("GPL");