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/scatterlist.h> 8 9 #define VIRTIO_MAX_SG (3+MAX_PHYS_SEGMENTS) 10 #define PART_BITS 4 11 12 static int major, index; 13 14 struct virtio_blk 15 { 16 spinlock_t lock; 17 18 struct virtio_device *vdev; 19 struct virtqueue *vq; 20 21 /* The disk structure for the kernel. */ 22 struct gendisk *disk; 23 24 /* Request tracking. */ 25 struct list_head reqs; 26 27 mempool_t *pool; 28 29 /* Scatterlist: can be too big for stack. */ 30 struct scatterlist sg[VIRTIO_MAX_SG]; 31 }; 32 33 struct virtblk_req 34 { 35 struct list_head list; 36 struct request *req; 37 struct virtio_blk_outhdr out_hdr; 38 u8 status; 39 }; 40 41 static void blk_done(struct virtqueue *vq) 42 { 43 struct virtio_blk *vblk = vq->vdev->priv; 44 struct virtblk_req *vbr; 45 unsigned int len; 46 unsigned long flags; 47 48 spin_lock_irqsave(&vblk->lock, flags); 49 while ((vbr = vblk->vq->vq_ops->get_buf(vblk->vq, &len)) != NULL) { 50 int error; 51 switch (vbr->status) { 52 case VIRTIO_BLK_S_OK: 53 error = 0; 54 break; 55 case VIRTIO_BLK_S_UNSUPP: 56 error = -ENOTTY; 57 break; 58 default: 59 error = -EIO; 60 break; 61 } 62 63 __blk_end_request(vbr->req, error, blk_rq_bytes(vbr->req)); 64 list_del(&vbr->list); 65 mempool_free(vbr, vblk->pool); 66 } 67 /* In case queue is stopped waiting for more buffers. */ 68 blk_start_queue(vblk->disk->queue); 69 spin_unlock_irqrestore(&vblk->lock, flags); 70 } 71 72 static bool do_req(struct request_queue *q, struct virtio_blk *vblk, 73 struct request *req) 74 { 75 unsigned long num, out, in; 76 struct virtblk_req *vbr; 77 78 vbr = mempool_alloc(vblk->pool, GFP_ATOMIC); 79 if (!vbr) 80 /* When another request finishes we'll try again. */ 81 return false; 82 83 vbr->req = req; 84 if (blk_fs_request(vbr->req)) { 85 vbr->out_hdr.type = 0; 86 vbr->out_hdr.sector = vbr->req->sector; 87 vbr->out_hdr.ioprio = req_get_ioprio(vbr->req); 88 } else if (blk_pc_request(vbr->req)) { 89 vbr->out_hdr.type = VIRTIO_BLK_T_SCSI_CMD; 90 vbr->out_hdr.sector = 0; 91 vbr->out_hdr.ioprio = req_get_ioprio(vbr->req); 92 } else { 93 /* We don't put anything else in the queue. */ 94 BUG(); 95 } 96 97 if (blk_barrier_rq(vbr->req)) 98 vbr->out_hdr.type |= VIRTIO_BLK_T_BARRIER; 99 100 /* This init could be done at vblk creation time */ 101 sg_init_table(vblk->sg, VIRTIO_MAX_SG); 102 sg_set_buf(&vblk->sg[0], &vbr->out_hdr, sizeof(vbr->out_hdr)); 103 num = blk_rq_map_sg(q, vbr->req, vblk->sg+1); 104 sg_set_buf(&vblk->sg[num+1], &vbr->status, sizeof(vbr->status)); 105 106 if (rq_data_dir(vbr->req) == WRITE) { 107 vbr->out_hdr.type |= VIRTIO_BLK_T_OUT; 108 out = 1 + num; 109 in = 1; 110 } else { 111 vbr->out_hdr.type |= VIRTIO_BLK_T_IN; 112 out = 1; 113 in = 1 + num; 114 } 115 116 if (vblk->vq->vq_ops->add_buf(vblk->vq, vblk->sg, out, in, vbr)) { 117 mempool_free(vbr, vblk->pool); 118 return false; 119 } 120 121 list_add_tail(&vbr->list, &vblk->reqs); 122 return true; 123 } 124 125 static void do_virtblk_request(struct request_queue *q) 126 { 127 struct virtio_blk *vblk = NULL; 128 struct request *req; 129 unsigned int issued = 0; 130 131 while ((req = elv_next_request(q)) != NULL) { 132 vblk = req->rq_disk->private_data; 133 BUG_ON(req->nr_phys_segments > ARRAY_SIZE(vblk->sg)); 134 135 /* If this request fails, stop queue and wait for something to 136 finish to restart it. */ 137 if (!do_req(q, vblk, req)) { 138 blk_stop_queue(q); 139 break; 140 } 141 blkdev_dequeue_request(req); 142 issued++; 143 } 144 145 if (issued) 146 vblk->vq->vq_ops->kick(vblk->vq); 147 } 148 149 static int virtblk_ioctl(struct block_device *bdev, fmode_t mode, 150 unsigned cmd, unsigned long data) 151 { 152 return scsi_cmd_ioctl(bdev->bd_disk->queue, 153 bdev->bd_disk, mode, cmd, 154 (void __user *)data); 155 } 156 157 /* We provide getgeo only to please some old bootloader/partitioning tools */ 158 static int virtblk_getgeo(struct block_device *bd, struct hd_geometry *geo) 159 { 160 struct virtio_blk *vblk = bd->bd_disk->private_data; 161 struct virtio_blk_geometry vgeo; 162 int err; 163 164 /* see if the host passed in geometry config */ 165 err = virtio_config_val(vblk->vdev, VIRTIO_BLK_F_GEOMETRY, 166 offsetof(struct virtio_blk_config, geometry), 167 &vgeo); 168 169 if (!err) { 170 geo->heads = vgeo.heads; 171 geo->sectors = vgeo.sectors; 172 geo->cylinders = vgeo.cylinders; 173 } else { 174 /* some standard values, similar to sd */ 175 geo->heads = 1 << 6; 176 geo->sectors = 1 << 5; 177 geo->cylinders = get_capacity(bd->bd_disk) >> 11; 178 } 179 return 0; 180 } 181 182 static struct block_device_operations virtblk_fops = { 183 .locked_ioctl = virtblk_ioctl, 184 .owner = THIS_MODULE, 185 .getgeo = virtblk_getgeo, 186 }; 187 188 static int index_to_minor(int index) 189 { 190 return index << PART_BITS; 191 } 192 193 static int virtblk_probe(struct virtio_device *vdev) 194 { 195 struct virtio_blk *vblk; 196 int err; 197 u64 cap; 198 u32 v; 199 u32 blk_size; 200 201 if (index_to_minor(index) >= 1 << MINORBITS) 202 return -ENOSPC; 203 204 vdev->priv = vblk = kmalloc(sizeof(*vblk), GFP_KERNEL); 205 if (!vblk) { 206 err = -ENOMEM; 207 goto out; 208 } 209 210 INIT_LIST_HEAD(&vblk->reqs); 211 spin_lock_init(&vblk->lock); 212 vblk->vdev = vdev; 213 214 /* We expect one virtqueue, for output. */ 215 vblk->vq = vdev->config->find_vq(vdev, 0, blk_done); 216 if (IS_ERR(vblk->vq)) { 217 err = PTR_ERR(vblk->vq); 218 goto out_free_vblk; 219 } 220 221 vblk->pool = mempool_create_kmalloc_pool(1,sizeof(struct virtblk_req)); 222 if (!vblk->pool) { 223 err = -ENOMEM; 224 goto out_free_vq; 225 } 226 227 /* FIXME: How many partitions? How long is a piece of string? */ 228 vblk->disk = alloc_disk(1 << PART_BITS); 229 if (!vblk->disk) { 230 err = -ENOMEM; 231 goto out_mempool; 232 } 233 234 vblk->disk->queue = blk_init_queue(do_virtblk_request, &vblk->lock); 235 if (!vblk->disk->queue) { 236 err = -ENOMEM; 237 goto out_put_disk; 238 } 239 240 if (index < 26) { 241 sprintf(vblk->disk->disk_name, "vd%c", 'a' + index % 26); 242 } else if (index < (26 + 1) * 26) { 243 sprintf(vblk->disk->disk_name, "vd%c%c", 244 'a' + index / 26 - 1, 'a' + index % 26); 245 } else { 246 const unsigned int m1 = (index / 26 - 1) / 26 - 1; 247 const unsigned int m2 = (index / 26 - 1) % 26; 248 const unsigned int m3 = index % 26; 249 sprintf(vblk->disk->disk_name, "vd%c%c%c", 250 'a' + m1, 'a' + m2, 'a' + m3); 251 } 252 253 vblk->disk->major = major; 254 vblk->disk->first_minor = index_to_minor(index); 255 vblk->disk->private_data = vblk; 256 vblk->disk->fops = &virtblk_fops; 257 vblk->disk->driverfs_dev = &vdev->dev; 258 index++; 259 260 /* If barriers are supported, tell block layer that queue is ordered */ 261 if (virtio_has_feature(vdev, VIRTIO_BLK_F_BARRIER)) 262 blk_queue_ordered(vblk->disk->queue, QUEUE_ORDERED_TAG, NULL); 263 264 /* If disk is read-only in the host, the guest should obey */ 265 if (virtio_has_feature(vdev, VIRTIO_BLK_F_RO)) 266 set_disk_ro(vblk->disk, 1); 267 268 /* Host must always specify the capacity. */ 269 vdev->config->get(vdev, offsetof(struct virtio_blk_config, capacity), 270 &cap, sizeof(cap)); 271 272 /* If capacity is too big, truncate with warning. */ 273 if ((sector_t)cap != cap) { 274 dev_warn(&vdev->dev, "Capacity %llu too large: truncating\n", 275 (unsigned long long)cap); 276 cap = (sector_t)-1; 277 } 278 set_capacity(vblk->disk, cap); 279 280 /* Host can optionally specify maximum segment size and number of 281 * segments. */ 282 err = virtio_config_val(vdev, VIRTIO_BLK_F_SIZE_MAX, 283 offsetof(struct virtio_blk_config, size_max), 284 &v); 285 if (!err) 286 blk_queue_max_segment_size(vblk->disk->queue, v); 287 288 err = virtio_config_val(vdev, VIRTIO_BLK_F_SEG_MAX, 289 offsetof(struct virtio_blk_config, seg_max), 290 &v); 291 if (!err) 292 blk_queue_max_hw_segments(vblk->disk->queue, v); 293 294 /* Host can optionally specify the block size of the device */ 295 err = virtio_config_val(vdev, VIRTIO_BLK_F_BLK_SIZE, 296 offsetof(struct virtio_blk_config, blk_size), 297 &blk_size); 298 if (!err) 299 blk_queue_hardsect_size(vblk->disk->queue, blk_size); 300 301 add_disk(vblk->disk); 302 return 0; 303 304 out_put_disk: 305 put_disk(vblk->disk); 306 out_mempool: 307 mempool_destroy(vblk->pool); 308 out_free_vq: 309 vdev->config->del_vq(vblk->vq); 310 out_free_vblk: 311 kfree(vblk); 312 out: 313 return err; 314 } 315 316 static void virtblk_remove(struct virtio_device *vdev) 317 { 318 struct virtio_blk *vblk = vdev->priv; 319 320 /* Nothing should be pending. */ 321 BUG_ON(!list_empty(&vblk->reqs)); 322 323 /* Stop all the virtqueues. */ 324 vdev->config->reset(vdev); 325 326 del_gendisk(vblk->disk); 327 blk_cleanup_queue(vblk->disk->queue); 328 put_disk(vblk->disk); 329 mempool_destroy(vblk->pool); 330 vdev->config->del_vq(vblk->vq); 331 kfree(vblk); 332 } 333 334 static struct virtio_device_id id_table[] = { 335 { VIRTIO_ID_BLOCK, VIRTIO_DEV_ANY_ID }, 336 { 0 }, 337 }; 338 339 static unsigned int features[] = { 340 VIRTIO_BLK_F_BARRIER, VIRTIO_BLK_F_SEG_MAX, VIRTIO_BLK_F_SIZE_MAX, 341 VIRTIO_BLK_F_GEOMETRY, VIRTIO_BLK_F_RO, VIRTIO_BLK_F_BLK_SIZE, 342 }; 343 344 static struct virtio_driver virtio_blk = { 345 .feature_table = features, 346 .feature_table_size = ARRAY_SIZE(features), 347 .driver.name = KBUILD_MODNAME, 348 .driver.owner = THIS_MODULE, 349 .id_table = id_table, 350 .probe = virtblk_probe, 351 .remove = __devexit_p(virtblk_remove), 352 }; 353 354 static int __init init(void) 355 { 356 major = register_blkdev(0, "virtblk"); 357 if (major < 0) 358 return major; 359 return register_virtio_driver(&virtio_blk); 360 } 361 362 static void __exit fini(void) 363 { 364 unregister_blkdev(major, "virtblk"); 365 unregister_virtio_driver(&virtio_blk); 366 } 367 module_init(init); 368 module_exit(fini); 369 370 MODULE_DEVICE_TABLE(virtio, id_table); 371 MODULE_DESCRIPTION("Virtio block driver"); 372 MODULE_LICENSE("GPL"); 373