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 PART_BITS 4 10 11 static int major, index; 12 13 struct virtio_blk 14 { 15 spinlock_t lock; 16 17 struct virtio_device *vdev; 18 struct virtqueue *vq; 19 20 /* The disk structure for the kernel. */ 21 struct gendisk *disk; 22 23 /* Request tracking. */ 24 struct list_head reqs; 25 26 mempool_t *pool; 27 28 /* What host tells us, plus 2 for header & tailer. */ 29 unsigned int sg_elems; 30 31 /* Scatterlist: can be too big for stack. */ 32 struct scatterlist sg[/*sg_elems*/]; 33 }; 34 35 struct virtblk_req 36 { 37 struct list_head list; 38 struct request *req; 39 struct virtio_blk_outhdr out_hdr; 40 u8 status; 41 }; 42 43 static void blk_done(struct virtqueue *vq) 44 { 45 struct virtio_blk *vblk = vq->vdev->priv; 46 struct virtblk_req *vbr; 47 unsigned int len; 48 unsigned long flags; 49 50 spin_lock_irqsave(&vblk->lock, flags); 51 while ((vbr = vblk->vq->vq_ops->get_buf(vblk->vq, &len)) != NULL) { 52 int error; 53 switch (vbr->status) { 54 case VIRTIO_BLK_S_OK: 55 error = 0; 56 break; 57 case VIRTIO_BLK_S_UNSUPP: 58 error = -ENOTTY; 59 break; 60 default: 61 error = -EIO; 62 break; 63 } 64 65 __blk_end_request(vbr->req, error, blk_rq_bytes(vbr->req)); 66 list_del(&vbr->list); 67 mempool_free(vbr, vblk->pool); 68 } 69 /* In case queue is stopped waiting for more buffers. */ 70 blk_start_queue(vblk->disk->queue); 71 spin_unlock_irqrestore(&vblk->lock, flags); 72 } 73 74 static bool do_req(struct request_queue *q, struct virtio_blk *vblk, 75 struct request *req) 76 { 77 unsigned long num, out, in; 78 struct virtblk_req *vbr; 79 80 vbr = mempool_alloc(vblk->pool, GFP_ATOMIC); 81 if (!vbr) 82 /* When another request finishes we'll try again. */ 83 return false; 84 85 vbr->req = req; 86 if (blk_fs_request(vbr->req)) { 87 vbr->out_hdr.type = 0; 88 vbr->out_hdr.sector = vbr->req->sector; 89 vbr->out_hdr.ioprio = req_get_ioprio(vbr->req); 90 } else if (blk_pc_request(vbr->req)) { 91 vbr->out_hdr.type = VIRTIO_BLK_T_SCSI_CMD; 92 vbr->out_hdr.sector = 0; 93 vbr->out_hdr.ioprio = req_get_ioprio(vbr->req); 94 } else { 95 /* We don't put anything else in the queue. */ 96 BUG(); 97 } 98 99 if (blk_barrier_rq(vbr->req)) 100 vbr->out_hdr.type |= VIRTIO_BLK_T_BARRIER; 101 102 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 + 2 > vblk->sg_elems); 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, sg_elems; 200 201 if (index_to_minor(index) >= 1 << MINORBITS) 202 return -ENOSPC; 203 204 /* We need to know how many segments before we allocate. */ 205 err = virtio_config_val(vdev, VIRTIO_BLK_F_SEG_MAX, 206 offsetof(struct virtio_blk_config, seg_max), 207 &sg_elems); 208 if (err) 209 sg_elems = 1; 210 211 /* We need an extra sg elements at head and tail. */ 212 sg_elems += 2; 213 vdev->priv = vblk = kmalloc(sizeof(*vblk) + 214 sizeof(vblk->sg[0]) * sg_elems, GFP_KERNEL); 215 if (!vblk) { 216 err = -ENOMEM; 217 goto out; 218 } 219 220 INIT_LIST_HEAD(&vblk->reqs); 221 spin_lock_init(&vblk->lock); 222 vblk->vdev = vdev; 223 vblk->sg_elems = sg_elems; 224 sg_init_table(vblk->sg, vblk->sg_elems); 225 226 /* We expect one virtqueue, for output. */ 227 vblk->vq = vdev->config->find_vq(vdev, 0, blk_done); 228 if (IS_ERR(vblk->vq)) { 229 err = PTR_ERR(vblk->vq); 230 goto out_free_vblk; 231 } 232 233 vblk->pool = mempool_create_kmalloc_pool(1,sizeof(struct virtblk_req)); 234 if (!vblk->pool) { 235 err = -ENOMEM; 236 goto out_free_vq; 237 } 238 239 /* FIXME: How many partitions? How long is a piece of string? */ 240 vblk->disk = alloc_disk(1 << PART_BITS); 241 if (!vblk->disk) { 242 err = -ENOMEM; 243 goto out_mempool; 244 } 245 246 vblk->disk->queue = blk_init_queue(do_virtblk_request, &vblk->lock); 247 if (!vblk->disk->queue) { 248 err = -ENOMEM; 249 goto out_put_disk; 250 } 251 252 queue_flag_set_unlocked(QUEUE_FLAG_VIRT, vblk->disk->queue); 253 254 if (index < 26) { 255 sprintf(vblk->disk->disk_name, "vd%c", 'a' + index % 26); 256 } else if (index < (26 + 1) * 26) { 257 sprintf(vblk->disk->disk_name, "vd%c%c", 258 'a' + index / 26 - 1, 'a' + index % 26); 259 } else { 260 const unsigned int m1 = (index / 26 - 1) / 26 - 1; 261 const unsigned int m2 = (index / 26 - 1) % 26; 262 const unsigned int m3 = index % 26; 263 sprintf(vblk->disk->disk_name, "vd%c%c%c", 264 'a' + m1, 'a' + m2, 'a' + m3); 265 } 266 267 vblk->disk->major = major; 268 vblk->disk->first_minor = index_to_minor(index); 269 vblk->disk->private_data = vblk; 270 vblk->disk->fops = &virtblk_fops; 271 vblk->disk->driverfs_dev = &vdev->dev; 272 index++; 273 274 /* If barriers are supported, tell block layer that queue is ordered */ 275 if (virtio_has_feature(vdev, VIRTIO_BLK_F_BARRIER)) 276 blk_queue_ordered(vblk->disk->queue, QUEUE_ORDERED_TAG, NULL); 277 278 /* If disk is read-only in the host, the guest should obey */ 279 if (virtio_has_feature(vdev, VIRTIO_BLK_F_RO)) 280 set_disk_ro(vblk->disk, 1); 281 282 /* Host must always specify the capacity. */ 283 vdev->config->get(vdev, offsetof(struct virtio_blk_config, capacity), 284 &cap, sizeof(cap)); 285 286 /* If capacity is too big, truncate with warning. */ 287 if ((sector_t)cap != cap) { 288 dev_warn(&vdev->dev, "Capacity %llu too large: truncating\n", 289 (unsigned long long)cap); 290 cap = (sector_t)-1; 291 } 292 set_capacity(vblk->disk, cap); 293 294 /* We can handle whatever the host told us to handle. */ 295 blk_queue_max_phys_segments(vblk->disk->queue, vblk->sg_elems-2); 296 blk_queue_max_hw_segments(vblk->disk->queue, vblk->sg_elems-2); 297 298 /* No real sector limit. */ 299 blk_queue_max_sectors(vblk->disk->queue, -1U); 300 301 /* Host can optionally specify maximum segment size and number of 302 * segments. */ 303 err = virtio_config_val(vdev, VIRTIO_BLK_F_SIZE_MAX, 304 offsetof(struct virtio_blk_config, size_max), 305 &v); 306 if (!err) 307 blk_queue_max_segment_size(vblk->disk->queue, v); 308 else 309 blk_queue_max_segment_size(vblk->disk->queue, -1U); 310 311 /* Host can optionally specify the block size of the device */ 312 err = virtio_config_val(vdev, VIRTIO_BLK_F_BLK_SIZE, 313 offsetof(struct virtio_blk_config, blk_size), 314 &blk_size); 315 if (!err) 316 blk_queue_hardsect_size(vblk->disk->queue, blk_size); 317 318 add_disk(vblk->disk); 319 return 0; 320 321 out_put_disk: 322 put_disk(vblk->disk); 323 out_mempool: 324 mempool_destroy(vblk->pool); 325 out_free_vq: 326 vdev->config->del_vq(vblk->vq); 327 out_free_vblk: 328 kfree(vblk); 329 out: 330 return err; 331 } 332 333 static void virtblk_remove(struct virtio_device *vdev) 334 { 335 struct virtio_blk *vblk = vdev->priv; 336 337 /* Nothing should be pending. */ 338 BUG_ON(!list_empty(&vblk->reqs)); 339 340 /* Stop all the virtqueues. */ 341 vdev->config->reset(vdev); 342 343 del_gendisk(vblk->disk); 344 blk_cleanup_queue(vblk->disk->queue); 345 put_disk(vblk->disk); 346 mempool_destroy(vblk->pool); 347 vdev->config->del_vq(vblk->vq); 348 kfree(vblk); 349 } 350 351 static struct virtio_device_id id_table[] = { 352 { VIRTIO_ID_BLOCK, VIRTIO_DEV_ANY_ID }, 353 { 0 }, 354 }; 355 356 static unsigned int features[] = { 357 VIRTIO_BLK_F_BARRIER, VIRTIO_BLK_F_SEG_MAX, VIRTIO_BLK_F_SIZE_MAX, 358 VIRTIO_BLK_F_GEOMETRY, VIRTIO_BLK_F_RO, VIRTIO_BLK_F_BLK_SIZE, 359 }; 360 361 static struct virtio_driver virtio_blk = { 362 .feature_table = features, 363 .feature_table_size = ARRAY_SIZE(features), 364 .driver.name = KBUILD_MODNAME, 365 .driver.owner = THIS_MODULE, 366 .id_table = id_table, 367 .probe = virtblk_probe, 368 .remove = __devexit_p(virtblk_remove), 369 }; 370 371 static int __init init(void) 372 { 373 major = register_blkdev(0, "virtblk"); 374 if (major < 0) 375 return major; 376 return register_virtio_driver(&virtio_blk); 377 } 378 379 static void __exit fini(void) 380 { 381 unregister_blkdev(major, "virtblk"); 382 unregister_virtio_driver(&virtio_blk); 383 } 384 module_init(init); 385 module_exit(fini); 386 387 MODULE_DEVICE_TABLE(virtio, id_table); 388 MODULE_DESCRIPTION("Virtio block driver"); 389 MODULE_LICENSE("GPL"); 390