1 /* 2 * (C) 2003 David Woodhouse <dwmw2@infradead.org> 3 * 4 * Interface to Linux 2.5 block layer for MTD 'translation layers'. 5 * 6 */ 7 8 #include <linux/kernel.h> 9 #include <linux/slab.h> 10 #include <linux/module.h> 11 #include <linux/list.h> 12 #include <linux/fs.h> 13 #include <linux/mtd/blktrans.h> 14 #include <linux/mtd/mtd.h> 15 #include <linux/blkdev.h> 16 #include <linux/blkpg.h> 17 #include <linux/freezer.h> 18 #include <linux/spinlock.h> 19 #include <linux/hdreg.h> 20 #include <linux/init.h> 21 #include <linux/mutex.h> 22 #include <linux/kthread.h> 23 #include <asm/uaccess.h> 24 25 #include "mtdcore.h" 26 27 static LIST_HEAD(blktrans_majors); 28 29 struct mtd_blkcore_priv { 30 struct task_struct *thread; 31 struct request_queue *rq; 32 spinlock_t queue_lock; 33 }; 34 35 static int do_blktrans_request(struct mtd_blktrans_ops *tr, 36 struct mtd_blktrans_dev *dev, 37 struct request *req) 38 { 39 unsigned long block, nsect; 40 char *buf; 41 42 block = blk_rq_pos(req) << 9 >> tr->blkshift; 43 nsect = blk_rq_cur_bytes(req) >> tr->blkshift; 44 45 buf = req->buffer; 46 47 if (!blk_fs_request(req)) 48 return -EIO; 49 50 if (blk_rq_pos(req) + blk_rq_cur_sectors(req) > 51 get_capacity(req->rq_disk)) 52 return -EIO; 53 54 if (blk_discard_rq(req)) 55 return tr->discard(dev, block, nsect); 56 57 switch(rq_data_dir(req)) { 58 case READ: 59 for (; nsect > 0; nsect--, block++, buf += tr->blksize) 60 if (tr->readsect(dev, block, buf)) 61 return -EIO; 62 return 0; 63 64 case WRITE: 65 if (!tr->writesect) 66 return -EIO; 67 68 for (; nsect > 0; nsect--, block++, buf += tr->blksize) 69 if (tr->writesect(dev, block, buf)) 70 return -EIO; 71 return 0; 72 73 default: 74 printk(KERN_NOTICE "Unknown request %u\n", rq_data_dir(req)); 75 return -EIO; 76 } 77 } 78 79 static int mtd_blktrans_thread(void *arg) 80 { 81 struct mtd_blktrans_ops *tr = arg; 82 struct request_queue *rq = tr->blkcore_priv->rq; 83 struct request *req = NULL; 84 85 /* we might get involved when memory gets low, so use PF_MEMALLOC */ 86 current->flags |= PF_MEMALLOC; 87 88 spin_lock_irq(rq->queue_lock); 89 90 while (!kthread_should_stop()) { 91 struct mtd_blktrans_dev *dev; 92 int res; 93 94 if (!req && !(req = blk_fetch_request(rq))) { 95 set_current_state(TASK_INTERRUPTIBLE); 96 spin_unlock_irq(rq->queue_lock); 97 schedule(); 98 spin_lock_irq(rq->queue_lock); 99 continue; 100 } 101 102 dev = req->rq_disk->private_data; 103 tr = dev->tr; 104 105 spin_unlock_irq(rq->queue_lock); 106 107 mutex_lock(&dev->lock); 108 res = do_blktrans_request(tr, dev, req); 109 mutex_unlock(&dev->lock); 110 111 spin_lock_irq(rq->queue_lock); 112 113 if (!__blk_end_request_cur(req, res)) 114 req = NULL; 115 } 116 117 if (req) 118 __blk_end_request_all(req, -EIO); 119 120 spin_unlock_irq(rq->queue_lock); 121 122 return 0; 123 } 124 125 static void mtd_blktrans_request(struct request_queue *rq) 126 { 127 struct mtd_blktrans_ops *tr = rq->queuedata; 128 wake_up_process(tr->blkcore_priv->thread); 129 } 130 131 132 static int blktrans_open(struct block_device *bdev, fmode_t mode) 133 { 134 struct mtd_blktrans_dev *dev = bdev->bd_disk->private_data; 135 struct mtd_blktrans_ops *tr = dev->tr; 136 int ret = -ENODEV; 137 138 if (!get_mtd_device(NULL, dev->mtd->index)) 139 goto out; 140 141 if (!try_module_get(tr->owner)) 142 goto out_tr; 143 144 /* FIXME: Locking. A hot pluggable device can go away 145 (del_mtd_device can be called for it) without its module 146 being unloaded. */ 147 dev->mtd->usecount++; 148 149 ret = 0; 150 if (tr->open && (ret = tr->open(dev))) { 151 dev->mtd->usecount--; 152 put_mtd_device(dev->mtd); 153 out_tr: 154 module_put(tr->owner); 155 } 156 out: 157 return ret; 158 } 159 160 static int blktrans_release(struct gendisk *disk, fmode_t mode) 161 { 162 struct mtd_blktrans_dev *dev = disk->private_data; 163 struct mtd_blktrans_ops *tr = dev->tr; 164 int ret = 0; 165 166 if (tr->release) 167 ret = tr->release(dev); 168 169 if (!ret) { 170 dev->mtd->usecount--; 171 put_mtd_device(dev->mtd); 172 module_put(tr->owner); 173 } 174 175 return ret; 176 } 177 178 static int blktrans_getgeo(struct block_device *bdev, struct hd_geometry *geo) 179 { 180 struct mtd_blktrans_dev *dev = bdev->bd_disk->private_data; 181 182 if (dev->tr->getgeo) 183 return dev->tr->getgeo(dev, geo); 184 return -ENOTTY; 185 } 186 187 static int blktrans_ioctl(struct block_device *bdev, fmode_t mode, 188 unsigned int cmd, unsigned long arg) 189 { 190 struct mtd_blktrans_dev *dev = bdev->bd_disk->private_data; 191 struct mtd_blktrans_ops *tr = dev->tr; 192 193 switch (cmd) { 194 case BLKFLSBUF: 195 if (tr->flush) 196 return tr->flush(dev); 197 /* The core code did the work, we had nothing to do. */ 198 return 0; 199 default: 200 return -ENOTTY; 201 } 202 } 203 204 static const struct block_device_operations mtd_blktrans_ops = { 205 .owner = THIS_MODULE, 206 .open = blktrans_open, 207 .release = blktrans_release, 208 .locked_ioctl = blktrans_ioctl, 209 .getgeo = blktrans_getgeo, 210 }; 211 212 int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new) 213 { 214 struct mtd_blktrans_ops *tr = new->tr; 215 struct mtd_blktrans_dev *d; 216 int last_devnum = -1; 217 struct gendisk *gd; 218 219 if (mutex_trylock(&mtd_table_mutex)) { 220 mutex_unlock(&mtd_table_mutex); 221 BUG(); 222 } 223 224 list_for_each_entry(d, &tr->devs, list) { 225 if (new->devnum == -1) { 226 /* Use first free number */ 227 if (d->devnum != last_devnum+1) { 228 /* Found a free devnum. Plug it in here */ 229 new->devnum = last_devnum+1; 230 list_add_tail(&new->list, &d->list); 231 goto added; 232 } 233 } else if (d->devnum == new->devnum) { 234 /* Required number taken */ 235 return -EBUSY; 236 } else if (d->devnum > new->devnum) { 237 /* Required number was free */ 238 list_add_tail(&new->list, &d->list); 239 goto added; 240 } 241 last_devnum = d->devnum; 242 } 243 if (new->devnum == -1) 244 new->devnum = last_devnum+1; 245 246 if ((new->devnum << tr->part_bits) > 256) { 247 return -EBUSY; 248 } 249 250 list_add_tail(&new->list, &tr->devs); 251 added: 252 mutex_init(&new->lock); 253 if (!tr->writesect) 254 new->readonly = 1; 255 256 gd = alloc_disk(1 << tr->part_bits); 257 if (!gd) { 258 list_del(&new->list); 259 return -ENOMEM; 260 } 261 gd->major = tr->major; 262 gd->first_minor = (new->devnum) << tr->part_bits; 263 gd->fops = &mtd_blktrans_ops; 264 265 if (tr->part_bits) 266 if (new->devnum < 26) 267 snprintf(gd->disk_name, sizeof(gd->disk_name), 268 "%s%c", tr->name, 'a' + new->devnum); 269 else 270 snprintf(gd->disk_name, sizeof(gd->disk_name), 271 "%s%c%c", tr->name, 272 'a' - 1 + new->devnum / 26, 273 'a' + new->devnum % 26); 274 else 275 snprintf(gd->disk_name, sizeof(gd->disk_name), 276 "%s%d", tr->name, new->devnum); 277 278 /* 2.5 has capacity in units of 512 bytes while still 279 having BLOCK_SIZE_BITS set to 10. Just to keep us amused. */ 280 set_capacity(gd, (new->size * tr->blksize) >> 9); 281 282 gd->private_data = new; 283 new->blkcore_priv = gd; 284 gd->queue = tr->blkcore_priv->rq; 285 gd->driverfs_dev = &new->mtd->dev; 286 287 if (new->readonly) 288 set_disk_ro(gd, 1); 289 290 add_disk(gd); 291 292 return 0; 293 } 294 295 int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old) 296 { 297 if (mutex_trylock(&mtd_table_mutex)) { 298 mutex_unlock(&mtd_table_mutex); 299 BUG(); 300 } 301 302 list_del(&old->list); 303 304 del_gendisk(old->blkcore_priv); 305 put_disk(old->blkcore_priv); 306 307 return 0; 308 } 309 310 static void blktrans_notify_remove(struct mtd_info *mtd) 311 { 312 struct mtd_blktrans_ops *tr; 313 struct mtd_blktrans_dev *dev, *next; 314 315 list_for_each_entry(tr, &blktrans_majors, list) 316 list_for_each_entry_safe(dev, next, &tr->devs, list) 317 if (dev->mtd == mtd) 318 tr->remove_dev(dev); 319 } 320 321 static void blktrans_notify_add(struct mtd_info *mtd) 322 { 323 struct mtd_blktrans_ops *tr; 324 325 if (mtd->type == MTD_ABSENT) 326 return; 327 328 list_for_each_entry(tr, &blktrans_majors, list) 329 tr->add_mtd(tr, mtd); 330 } 331 332 static struct mtd_notifier blktrans_notifier = { 333 .add = blktrans_notify_add, 334 .remove = blktrans_notify_remove, 335 }; 336 337 int register_mtd_blktrans(struct mtd_blktrans_ops *tr) 338 { 339 int ret, i; 340 341 /* Register the notifier if/when the first device type is 342 registered, to prevent the link/init ordering from fucking 343 us over. */ 344 if (!blktrans_notifier.list.next) 345 register_mtd_user(&blktrans_notifier); 346 347 tr->blkcore_priv = kzalloc(sizeof(*tr->blkcore_priv), GFP_KERNEL); 348 if (!tr->blkcore_priv) 349 return -ENOMEM; 350 351 mutex_lock(&mtd_table_mutex); 352 353 ret = register_blkdev(tr->major, tr->name); 354 if (ret) { 355 printk(KERN_WARNING "Unable to register %s block device on major %d: %d\n", 356 tr->name, tr->major, ret); 357 kfree(tr->blkcore_priv); 358 mutex_unlock(&mtd_table_mutex); 359 return ret; 360 } 361 spin_lock_init(&tr->blkcore_priv->queue_lock); 362 363 tr->blkcore_priv->rq = blk_init_queue(mtd_blktrans_request, &tr->blkcore_priv->queue_lock); 364 if (!tr->blkcore_priv->rq) { 365 unregister_blkdev(tr->major, tr->name); 366 kfree(tr->blkcore_priv); 367 mutex_unlock(&mtd_table_mutex); 368 return -ENOMEM; 369 } 370 371 tr->blkcore_priv->rq->queuedata = tr; 372 blk_queue_logical_block_size(tr->blkcore_priv->rq, tr->blksize); 373 if (tr->discard) 374 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, 375 tr->blkcore_priv->rq); 376 377 tr->blkshift = ffs(tr->blksize) - 1; 378 379 tr->blkcore_priv->thread = kthread_run(mtd_blktrans_thread, tr, 380 "%sd", tr->name); 381 if (IS_ERR(tr->blkcore_priv->thread)) { 382 int ret = PTR_ERR(tr->blkcore_priv->thread); 383 blk_cleanup_queue(tr->blkcore_priv->rq); 384 unregister_blkdev(tr->major, tr->name); 385 kfree(tr->blkcore_priv); 386 mutex_unlock(&mtd_table_mutex); 387 return ret; 388 } 389 390 INIT_LIST_HEAD(&tr->devs); 391 list_add(&tr->list, &blktrans_majors); 392 393 for (i=0; i<MAX_MTD_DEVICES; i++) { 394 if (mtd_table[i] && mtd_table[i]->type != MTD_ABSENT) 395 tr->add_mtd(tr, mtd_table[i]); 396 } 397 398 mutex_unlock(&mtd_table_mutex); 399 400 return 0; 401 } 402 403 int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr) 404 { 405 struct mtd_blktrans_dev *dev, *next; 406 407 mutex_lock(&mtd_table_mutex); 408 409 /* Clean up the kernel thread */ 410 kthread_stop(tr->blkcore_priv->thread); 411 412 /* Remove it from the list of active majors */ 413 list_del(&tr->list); 414 415 list_for_each_entry_safe(dev, next, &tr->devs, list) 416 tr->remove_dev(dev); 417 418 blk_cleanup_queue(tr->blkcore_priv->rq); 419 unregister_blkdev(tr->major, tr->name); 420 421 mutex_unlock(&mtd_table_mutex); 422 423 kfree(tr->blkcore_priv); 424 425 BUG_ON(!list_empty(&tr->devs)); 426 return 0; 427 } 428 429 static void __exit mtd_blktrans_exit(void) 430 { 431 /* No race here -- if someone's currently in register_mtd_blktrans 432 we're screwed anyway. */ 433 if (blktrans_notifier.list.next) 434 unregister_mtd_user(&blktrans_notifier); 435 } 436 437 module_exit(mtd_blktrans_exit); 438 439 EXPORT_SYMBOL_GPL(register_mtd_blktrans); 440 EXPORT_SYMBOL_GPL(deregister_mtd_blktrans); 441 EXPORT_SYMBOL_GPL(add_mtd_blktrans_dev); 442 EXPORT_SYMBOL_GPL(del_mtd_blktrans_dev); 443 444 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>"); 445 MODULE_LICENSE("GPL"); 446 MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'"); 447