1 /* 2 * $Id: mtd_blkdevs.c,v 1.27 2005/11/07 11:14:20 gleixner Exp $ 3 * 4 * (C) 2003 David Woodhouse <dwmw2@infradead.org> 5 * 6 * Interface to Linux 2.5 block layer for MTD 'translation layers'. 7 * 8 */ 9 10 #include <linux/kernel.h> 11 #include <linux/slab.h> 12 #include <linux/module.h> 13 #include <linux/list.h> 14 #include <linux/fs.h> 15 #include <linux/mtd/blktrans.h> 16 #include <linux/mtd/mtd.h> 17 #include <linux/blkdev.h> 18 #include <linux/blkpg.h> 19 #include <linux/spinlock.h> 20 #include <linux/hdreg.h> 21 #include <linux/init.h> 22 #include <linux/mutex.h> 23 #include <asm/uaccess.h> 24 25 static LIST_HEAD(blktrans_majors); 26 27 extern struct mutex mtd_table_mutex; 28 extern struct mtd_info *mtd_table[]; 29 30 struct mtd_blkcore_priv { 31 struct completion thread_dead; 32 int exiting; 33 wait_queue_head_t thread_wq; 34 struct request_queue *rq; 35 spinlock_t queue_lock; 36 }; 37 38 static int do_blktrans_request(struct mtd_blktrans_ops *tr, 39 struct mtd_blktrans_dev *dev, 40 struct request *req) 41 { 42 unsigned long block, nsect; 43 char *buf; 44 45 block = req->sector << 9 >> tr->blkshift; 46 nsect = req->current_nr_sectors << 9 >> tr->blkshift; 47 48 buf = req->buffer; 49 50 if (!blk_fs_request(req)) 51 return 0; 52 53 if (req->sector + req->current_nr_sectors > get_capacity(req->rq_disk)) 54 return 0; 55 56 switch(rq_data_dir(req)) { 57 case READ: 58 for (; nsect > 0; nsect--, block++, buf += tr->blksize) 59 if (tr->readsect(dev, block, buf)) 60 return 0; 61 return 1; 62 63 case WRITE: 64 if (!tr->writesect) 65 return 0; 66 67 for (; nsect > 0; nsect--, block++, buf += tr->blksize) 68 if (tr->writesect(dev, block, buf)) 69 return 0; 70 return 1; 71 72 default: 73 printk(KERN_NOTICE "Unknown request %u\n", rq_data_dir(req)); 74 return 0; 75 } 76 } 77 78 static int mtd_blktrans_thread(void *arg) 79 { 80 struct mtd_blktrans_ops *tr = arg; 81 struct request_queue *rq = tr->blkcore_priv->rq; 82 83 /* we might get involved when memory gets low, so use PF_MEMALLOC */ 84 current->flags |= PF_MEMALLOC | PF_NOFREEZE; 85 86 daemonize("%sd", tr->name); 87 88 /* daemonize() doesn't do this for us since some kernel threads 89 actually want to deal with signals. We can't just call 90 exit_sighand() since that'll cause an oops when we finally 91 do exit. */ 92 spin_lock_irq(¤t->sighand->siglock); 93 sigfillset(¤t->blocked); 94 recalc_sigpending(); 95 spin_unlock_irq(¤t->sighand->siglock); 96 97 spin_lock_irq(rq->queue_lock); 98 99 while (!tr->blkcore_priv->exiting) { 100 struct request *req; 101 struct mtd_blktrans_dev *dev; 102 int res = 0; 103 DECLARE_WAITQUEUE(wait, current); 104 105 req = elv_next_request(rq); 106 107 if (!req) { 108 add_wait_queue(&tr->blkcore_priv->thread_wq, &wait); 109 set_current_state(TASK_INTERRUPTIBLE); 110 111 spin_unlock_irq(rq->queue_lock); 112 113 schedule(); 114 remove_wait_queue(&tr->blkcore_priv->thread_wq, &wait); 115 116 spin_lock_irq(rq->queue_lock); 117 118 continue; 119 } 120 121 dev = req->rq_disk->private_data; 122 tr = dev->tr; 123 124 spin_unlock_irq(rq->queue_lock); 125 126 mutex_lock(&dev->lock); 127 res = do_blktrans_request(tr, dev, req); 128 mutex_unlock(&dev->lock); 129 130 spin_lock_irq(rq->queue_lock); 131 132 end_request(req, res); 133 } 134 spin_unlock_irq(rq->queue_lock); 135 136 complete_and_exit(&tr->blkcore_priv->thread_dead, 0); 137 } 138 139 static void mtd_blktrans_request(struct request_queue *rq) 140 { 141 struct mtd_blktrans_ops *tr = rq->queuedata; 142 wake_up(&tr->blkcore_priv->thread_wq); 143 } 144 145 146 static int blktrans_open(struct inode *i, struct file *f) 147 { 148 struct mtd_blktrans_dev *dev; 149 struct mtd_blktrans_ops *tr; 150 int ret = -ENODEV; 151 152 dev = i->i_bdev->bd_disk->private_data; 153 tr = dev->tr; 154 155 if (!try_module_get(dev->mtd->owner)) 156 goto out; 157 158 if (!try_module_get(tr->owner)) 159 goto out_tr; 160 161 /* FIXME: Locking. A hot pluggable device can go away 162 (del_mtd_device can be called for it) without its module 163 being unloaded. */ 164 dev->mtd->usecount++; 165 166 ret = 0; 167 if (tr->open && (ret = tr->open(dev))) { 168 dev->mtd->usecount--; 169 module_put(dev->mtd->owner); 170 out_tr: 171 module_put(tr->owner); 172 } 173 out: 174 return ret; 175 } 176 177 static int blktrans_release(struct inode *i, struct file *f) 178 { 179 struct mtd_blktrans_dev *dev; 180 struct mtd_blktrans_ops *tr; 181 int ret = 0; 182 183 dev = i->i_bdev->bd_disk->private_data; 184 tr = dev->tr; 185 186 if (tr->release) 187 ret = tr->release(dev); 188 189 if (!ret) { 190 dev->mtd->usecount--; 191 module_put(dev->mtd->owner); 192 module_put(tr->owner); 193 } 194 195 return ret; 196 } 197 198 static int blktrans_getgeo(struct block_device *bdev, struct hd_geometry *geo) 199 { 200 struct mtd_blktrans_dev *dev = bdev->bd_disk->private_data; 201 202 if (dev->tr->getgeo) 203 return dev->tr->getgeo(dev, geo); 204 return -ENOTTY; 205 } 206 207 static int blktrans_ioctl(struct inode *inode, struct file *file, 208 unsigned int cmd, unsigned long arg) 209 { 210 struct mtd_blktrans_dev *dev = inode->i_bdev->bd_disk->private_data; 211 struct mtd_blktrans_ops *tr = dev->tr; 212 213 switch (cmd) { 214 case BLKFLSBUF: 215 if (tr->flush) 216 return tr->flush(dev); 217 /* The core code did the work, we had nothing to do. */ 218 return 0; 219 default: 220 return -ENOTTY; 221 } 222 } 223 224 struct block_device_operations mtd_blktrans_ops = { 225 .owner = THIS_MODULE, 226 .open = blktrans_open, 227 .release = blktrans_release, 228 .ioctl = blktrans_ioctl, 229 .getgeo = blktrans_getgeo, 230 }; 231 232 int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new) 233 { 234 struct mtd_blktrans_ops *tr = new->tr; 235 struct list_head *this; 236 int last_devnum = -1; 237 struct gendisk *gd; 238 239 if (!!mutex_trylock(&mtd_table_mutex)) { 240 mutex_unlock(&mtd_table_mutex); 241 BUG(); 242 } 243 244 list_for_each(this, &tr->devs) { 245 struct mtd_blktrans_dev *d = list_entry(this, struct mtd_blktrans_dev, list); 246 if (new->devnum == -1) { 247 /* Use first free number */ 248 if (d->devnum != last_devnum+1) { 249 /* Found a free devnum. Plug it in here */ 250 new->devnum = last_devnum+1; 251 list_add_tail(&new->list, &d->list); 252 goto added; 253 } 254 } else if (d->devnum == new->devnum) { 255 /* Required number taken */ 256 return -EBUSY; 257 } else if (d->devnum > new->devnum) { 258 /* Required number was free */ 259 list_add_tail(&new->list, &d->list); 260 goto added; 261 } 262 last_devnum = d->devnum; 263 } 264 if (new->devnum == -1) 265 new->devnum = last_devnum+1; 266 267 if ((new->devnum << tr->part_bits) > 256) { 268 return -EBUSY; 269 } 270 271 mutex_init(&new->lock); 272 list_add_tail(&new->list, &tr->devs); 273 added: 274 if (!tr->writesect) 275 new->readonly = 1; 276 277 gd = alloc_disk(1 << tr->part_bits); 278 if (!gd) { 279 list_del(&new->list); 280 return -ENOMEM; 281 } 282 gd->major = tr->major; 283 gd->first_minor = (new->devnum) << tr->part_bits; 284 gd->fops = &mtd_blktrans_ops; 285 286 if (tr->part_bits) 287 if (new->devnum < 26) 288 snprintf(gd->disk_name, sizeof(gd->disk_name), 289 "%s%c", tr->name, 'a' + new->devnum); 290 else 291 snprintf(gd->disk_name, sizeof(gd->disk_name), 292 "%s%c%c", tr->name, 293 'a' - 1 + new->devnum / 26, 294 'a' + new->devnum % 26); 295 else 296 snprintf(gd->disk_name, sizeof(gd->disk_name), 297 "%s%d", tr->name, new->devnum); 298 299 /* 2.5 has capacity in units of 512 bytes while still 300 having BLOCK_SIZE_BITS set to 10. Just to keep us amused. */ 301 set_capacity(gd, (new->size * tr->blksize) >> 9); 302 303 gd->private_data = new; 304 new->blkcore_priv = gd; 305 gd->queue = tr->blkcore_priv->rq; 306 307 if (new->readonly) 308 set_disk_ro(gd, 1); 309 310 add_disk(gd); 311 312 return 0; 313 } 314 315 int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old) 316 { 317 if (!!mutex_trylock(&mtd_table_mutex)) { 318 mutex_unlock(&mtd_table_mutex); 319 BUG(); 320 } 321 322 list_del(&old->list); 323 324 del_gendisk(old->blkcore_priv); 325 put_disk(old->blkcore_priv); 326 327 return 0; 328 } 329 330 static void blktrans_notify_remove(struct mtd_info *mtd) 331 { 332 struct list_head *this, *this2, *next; 333 334 list_for_each(this, &blktrans_majors) { 335 struct mtd_blktrans_ops *tr = list_entry(this, struct mtd_blktrans_ops, list); 336 337 list_for_each_safe(this2, next, &tr->devs) { 338 struct mtd_blktrans_dev *dev = list_entry(this2, struct mtd_blktrans_dev, list); 339 340 if (dev->mtd == mtd) 341 tr->remove_dev(dev); 342 } 343 } 344 } 345 346 static void blktrans_notify_add(struct mtd_info *mtd) 347 { 348 struct list_head *this; 349 350 if (mtd->type == MTD_ABSENT) 351 return; 352 353 list_for_each(this, &blktrans_majors) { 354 struct mtd_blktrans_ops *tr = list_entry(this, struct mtd_blktrans_ops, list); 355 356 tr->add_mtd(tr, mtd); 357 } 358 359 } 360 361 static struct mtd_notifier blktrans_notifier = { 362 .add = blktrans_notify_add, 363 .remove = blktrans_notify_remove, 364 }; 365 366 int register_mtd_blktrans(struct mtd_blktrans_ops *tr) 367 { 368 int ret, i; 369 370 /* Register the notifier if/when the first device type is 371 registered, to prevent the link/init ordering from fucking 372 us over. */ 373 if (!blktrans_notifier.list.next) 374 register_mtd_user(&blktrans_notifier); 375 376 tr->blkcore_priv = kzalloc(sizeof(*tr->blkcore_priv), GFP_KERNEL); 377 if (!tr->blkcore_priv) 378 return -ENOMEM; 379 380 mutex_lock(&mtd_table_mutex); 381 382 ret = register_blkdev(tr->major, tr->name); 383 if (ret) { 384 printk(KERN_WARNING "Unable to register %s block device on major %d: %d\n", 385 tr->name, tr->major, ret); 386 kfree(tr->blkcore_priv); 387 mutex_unlock(&mtd_table_mutex); 388 return ret; 389 } 390 spin_lock_init(&tr->blkcore_priv->queue_lock); 391 init_completion(&tr->blkcore_priv->thread_dead); 392 init_waitqueue_head(&tr->blkcore_priv->thread_wq); 393 394 tr->blkcore_priv->rq = blk_init_queue(mtd_blktrans_request, &tr->blkcore_priv->queue_lock); 395 if (!tr->blkcore_priv->rq) { 396 unregister_blkdev(tr->major, tr->name); 397 kfree(tr->blkcore_priv); 398 mutex_unlock(&mtd_table_mutex); 399 return -ENOMEM; 400 } 401 402 tr->blkcore_priv->rq->queuedata = tr; 403 blk_queue_hardsect_size(tr->blkcore_priv->rq, tr->blksize); 404 tr->blkshift = ffs(tr->blksize) - 1; 405 406 ret = kernel_thread(mtd_blktrans_thread, tr, CLONE_KERNEL); 407 if (ret < 0) { 408 blk_cleanup_queue(tr->blkcore_priv->rq); 409 unregister_blkdev(tr->major, tr->name); 410 kfree(tr->blkcore_priv); 411 mutex_unlock(&mtd_table_mutex); 412 return ret; 413 } 414 415 INIT_LIST_HEAD(&tr->devs); 416 list_add(&tr->list, &blktrans_majors); 417 418 for (i=0; i<MAX_MTD_DEVICES; i++) { 419 if (mtd_table[i] && mtd_table[i]->type != MTD_ABSENT) 420 tr->add_mtd(tr, mtd_table[i]); 421 } 422 423 mutex_unlock(&mtd_table_mutex); 424 425 return 0; 426 } 427 428 int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr) 429 { 430 struct list_head *this, *next; 431 432 mutex_lock(&mtd_table_mutex); 433 434 /* Clean up the kernel thread */ 435 tr->blkcore_priv->exiting = 1; 436 wake_up(&tr->blkcore_priv->thread_wq); 437 wait_for_completion(&tr->blkcore_priv->thread_dead); 438 439 /* Remove it from the list of active majors */ 440 list_del(&tr->list); 441 442 list_for_each_safe(this, next, &tr->devs) { 443 struct mtd_blktrans_dev *dev = list_entry(this, struct mtd_blktrans_dev, list); 444 tr->remove_dev(dev); 445 } 446 447 blk_cleanup_queue(tr->blkcore_priv->rq); 448 unregister_blkdev(tr->major, tr->name); 449 450 mutex_unlock(&mtd_table_mutex); 451 452 kfree(tr->blkcore_priv); 453 454 BUG_ON(!list_empty(&tr->devs)); 455 return 0; 456 } 457 458 static void __exit mtd_blktrans_exit(void) 459 { 460 /* No race here -- if someone's currently in register_mtd_blktrans 461 we're screwed anyway. */ 462 if (blktrans_notifier.list.next) 463 unregister_mtd_user(&blktrans_notifier); 464 } 465 466 module_exit(mtd_blktrans_exit); 467 468 EXPORT_SYMBOL_GPL(register_mtd_blktrans); 469 EXPORT_SYMBOL_GPL(deregister_mtd_blktrans); 470 EXPORT_SYMBOL_GPL(add_mtd_blktrans_dev); 471 EXPORT_SYMBOL_GPL(del_mtd_blktrans_dev); 472 473 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>"); 474 MODULE_LICENSE("GPL"); 475 MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'"); 476