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 <asm/semaphore.h> 23 #include <asm/uaccess.h> 24 25 static LIST_HEAD(blktrans_majors); 26 27 extern struct semaphore 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; 46 nsect = req->current_nr_sectors; 47 buf = req->buffer; 48 49 if (!(req->flags & REQ_CMD)) 50 return 0; 51 52 if (block + nsect > get_capacity(req->rq_disk)) 53 return 0; 54 55 switch(rq_data_dir(req)) { 56 case READ: 57 for (; nsect > 0; nsect--, block++, buf += 512) 58 if (tr->readsect(dev, block, buf)) 59 return 0; 60 return 1; 61 62 case WRITE: 63 if (!tr->writesect) 64 return 0; 65 66 for (; nsect > 0; nsect--, block++, buf += 512) 67 if (tr->writesect(dev, block, buf)) 68 return 0; 69 return 1; 70 71 default: 72 printk(KERN_NOTICE "Unknown request %ld\n", rq_data_dir(req)); 73 return 0; 74 } 75 } 76 77 static int mtd_blktrans_thread(void *arg) 78 { 79 struct mtd_blktrans_ops *tr = arg; 80 struct request_queue *rq = tr->blkcore_priv->rq; 81 82 /* we might get involved when memory gets low, so use PF_MEMALLOC */ 83 current->flags |= PF_MEMALLOC | PF_NOFREEZE; 84 85 daemonize("%sd", tr->name); 86 87 /* daemonize() doesn't do this for us since some kernel threads 88 actually want to deal with signals. We can't just call 89 exit_sighand() since that'll cause an oops when we finally 90 do exit. */ 91 spin_lock_irq(¤t->sighand->siglock); 92 sigfillset(¤t->blocked); 93 recalc_sigpending(); 94 spin_unlock_irq(¤t->sighand->siglock); 95 96 spin_lock_irq(rq->queue_lock); 97 98 while (!tr->blkcore_priv->exiting) { 99 struct request *req; 100 struct mtd_blktrans_dev *dev; 101 int res = 0; 102 DECLARE_WAITQUEUE(wait, current); 103 104 req = elv_next_request(rq); 105 106 if (!req) { 107 add_wait_queue(&tr->blkcore_priv->thread_wq, &wait); 108 set_current_state(TASK_INTERRUPTIBLE); 109 110 spin_unlock_irq(rq->queue_lock); 111 112 schedule(); 113 remove_wait_queue(&tr->blkcore_priv->thread_wq, &wait); 114 115 spin_lock_irq(rq->queue_lock); 116 117 continue; 118 } 119 120 dev = req->rq_disk->private_data; 121 tr = dev->tr; 122 123 spin_unlock_irq(rq->queue_lock); 124 125 down(&dev->sem); 126 res = do_blktrans_request(tr, dev, req); 127 up(&dev->sem); 128 129 spin_lock_irq(rq->queue_lock); 130 131 end_request(req, res); 132 } 133 spin_unlock_irq(rq->queue_lock); 134 135 complete_and_exit(&tr->blkcore_priv->thread_dead, 0); 136 } 137 138 static void mtd_blktrans_request(struct request_queue *rq) 139 { 140 struct mtd_blktrans_ops *tr = rq->queuedata; 141 wake_up(&tr->blkcore_priv->thread_wq); 142 } 143 144 145 static int blktrans_open(struct inode *i, struct file *f) 146 { 147 struct mtd_blktrans_dev *dev; 148 struct mtd_blktrans_ops *tr; 149 int ret = -ENODEV; 150 151 dev = i->i_bdev->bd_disk->private_data; 152 tr = dev->tr; 153 154 if (!try_module_get(dev->mtd->owner)) 155 goto out; 156 157 if (!try_module_get(tr->owner)) 158 goto out_tr; 159 160 /* FIXME: Locking. A hot pluggable device can go away 161 (del_mtd_device can be called for it) without its module 162 being unloaded. */ 163 dev->mtd->usecount++; 164 165 ret = 0; 166 if (tr->open && (ret = tr->open(dev))) { 167 dev->mtd->usecount--; 168 module_put(dev->mtd->owner); 169 out_tr: 170 module_put(tr->owner); 171 } 172 out: 173 return ret; 174 } 175 176 static int blktrans_release(struct inode *i, struct file *f) 177 { 178 struct mtd_blktrans_dev *dev; 179 struct mtd_blktrans_ops *tr; 180 int ret = 0; 181 182 dev = i->i_bdev->bd_disk->private_data; 183 tr = dev->tr; 184 185 if (tr->release) 186 ret = tr->release(dev); 187 188 if (!ret) { 189 dev->mtd->usecount--; 190 module_put(dev->mtd->owner); 191 module_put(tr->owner); 192 } 193 194 return ret; 195 } 196 197 198 static int blktrans_ioctl(struct inode *inode, struct file *file, 199 unsigned int cmd, unsigned long arg) 200 { 201 struct mtd_blktrans_dev *dev = inode->i_bdev->bd_disk->private_data; 202 struct mtd_blktrans_ops *tr = dev->tr; 203 204 switch (cmd) { 205 case BLKFLSBUF: 206 if (tr->flush) 207 return tr->flush(dev); 208 /* The core code did the work, we had nothing to do. */ 209 return 0; 210 211 case HDIO_GETGEO: 212 if (tr->getgeo) { 213 struct hd_geometry g; 214 int ret; 215 216 memset(&g, 0, sizeof(g)); 217 ret = tr->getgeo(dev, &g); 218 if (ret) 219 return ret; 220 221 g.start = get_start_sect(inode->i_bdev); 222 if (copy_to_user((void __user *)arg, &g, sizeof(g))) 223 return -EFAULT; 224 return 0; 225 } /* else */ 226 default: 227 return -ENOTTY; 228 } 229 } 230 231 struct block_device_operations mtd_blktrans_ops = { 232 .owner = THIS_MODULE, 233 .open = blktrans_open, 234 .release = blktrans_release, 235 .ioctl = blktrans_ioctl, 236 }; 237 238 int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new) 239 { 240 struct mtd_blktrans_ops *tr = new->tr; 241 struct list_head *this; 242 int last_devnum = -1; 243 struct gendisk *gd; 244 245 if (!down_trylock(&mtd_table_mutex)) { 246 up(&mtd_table_mutex); 247 BUG(); 248 } 249 250 list_for_each(this, &tr->devs) { 251 struct mtd_blktrans_dev *d = list_entry(this, struct mtd_blktrans_dev, list); 252 if (new->devnum == -1) { 253 /* Use first free number */ 254 if (d->devnum != last_devnum+1) { 255 /* Found a free devnum. Plug it in here */ 256 new->devnum = last_devnum+1; 257 list_add_tail(&new->list, &d->list); 258 goto added; 259 } 260 } else if (d->devnum == new->devnum) { 261 /* Required number taken */ 262 return -EBUSY; 263 } else if (d->devnum > new->devnum) { 264 /* Required number was free */ 265 list_add_tail(&new->list, &d->list); 266 goto added; 267 } 268 last_devnum = d->devnum; 269 } 270 if (new->devnum == -1) 271 new->devnum = last_devnum+1; 272 273 if ((new->devnum << tr->part_bits) > 256) { 274 return -EBUSY; 275 } 276 277 init_MUTEX(&new->sem); 278 list_add_tail(&new->list, &tr->devs); 279 added: 280 if (!tr->writesect) 281 new->readonly = 1; 282 283 gd = alloc_disk(1 << tr->part_bits); 284 if (!gd) { 285 list_del(&new->list); 286 return -ENOMEM; 287 } 288 gd->major = tr->major; 289 gd->first_minor = (new->devnum) << tr->part_bits; 290 gd->fops = &mtd_blktrans_ops; 291 292 if (tr->part_bits) 293 if (new->devnum < 26) 294 snprintf(gd->disk_name, sizeof(gd->disk_name), 295 "%s%c", tr->name, 'a' + new->devnum); 296 else 297 snprintf(gd->disk_name, sizeof(gd->disk_name), 298 "%s%c%c", tr->name, 299 'a' - 1 + new->devnum / 26, 300 'a' + new->devnum % 26); 301 else 302 snprintf(gd->disk_name, sizeof(gd->disk_name), 303 "%s%d", tr->name, new->devnum); 304 305 /* 2.5 has capacity in units of 512 bytes while still 306 having BLOCK_SIZE_BITS set to 10. Just to keep us amused. */ 307 set_capacity(gd, (new->size * new->blksize) >> 9); 308 309 gd->private_data = new; 310 new->blkcore_priv = gd; 311 gd->queue = tr->blkcore_priv->rq; 312 313 if (new->readonly) 314 set_disk_ro(gd, 1); 315 316 add_disk(gd); 317 318 return 0; 319 } 320 321 int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old) 322 { 323 if (!down_trylock(&mtd_table_mutex)) { 324 up(&mtd_table_mutex); 325 BUG(); 326 } 327 328 list_del(&old->list); 329 330 del_gendisk(old->blkcore_priv); 331 put_disk(old->blkcore_priv); 332 333 return 0; 334 } 335 336 static void blktrans_notify_remove(struct mtd_info *mtd) 337 { 338 struct list_head *this, *this2, *next; 339 340 list_for_each(this, &blktrans_majors) { 341 struct mtd_blktrans_ops *tr = list_entry(this, struct mtd_blktrans_ops, list); 342 343 list_for_each_safe(this2, next, &tr->devs) { 344 struct mtd_blktrans_dev *dev = list_entry(this2, struct mtd_blktrans_dev, list); 345 346 if (dev->mtd == mtd) 347 tr->remove_dev(dev); 348 } 349 } 350 } 351 352 static void blktrans_notify_add(struct mtd_info *mtd) 353 { 354 struct list_head *this; 355 356 if (mtd->type == MTD_ABSENT) 357 return; 358 359 list_for_each(this, &blktrans_majors) { 360 struct mtd_blktrans_ops *tr = list_entry(this, struct mtd_blktrans_ops, list); 361 362 tr->add_mtd(tr, mtd); 363 } 364 365 } 366 367 static struct mtd_notifier blktrans_notifier = { 368 .add = blktrans_notify_add, 369 .remove = blktrans_notify_remove, 370 }; 371 372 int register_mtd_blktrans(struct mtd_blktrans_ops *tr) 373 { 374 int ret, i; 375 376 /* Register the notifier if/when the first device type is 377 registered, to prevent the link/init ordering from fucking 378 us over. */ 379 if (!blktrans_notifier.list.next) 380 register_mtd_user(&blktrans_notifier); 381 382 tr->blkcore_priv = kmalloc(sizeof(*tr->blkcore_priv), GFP_KERNEL); 383 if (!tr->blkcore_priv) 384 return -ENOMEM; 385 386 memset(tr->blkcore_priv, 0, sizeof(*tr->blkcore_priv)); 387 388 down(&mtd_table_mutex); 389 390 ret = register_blkdev(tr->major, tr->name); 391 if (ret) { 392 printk(KERN_WARNING "Unable to register %s block device on major %d: %d\n", 393 tr->name, tr->major, ret); 394 kfree(tr->blkcore_priv); 395 up(&mtd_table_mutex); 396 return ret; 397 } 398 spin_lock_init(&tr->blkcore_priv->queue_lock); 399 init_completion(&tr->blkcore_priv->thread_dead); 400 init_waitqueue_head(&tr->blkcore_priv->thread_wq); 401 402 tr->blkcore_priv->rq = blk_init_queue(mtd_blktrans_request, &tr->blkcore_priv->queue_lock); 403 if (!tr->blkcore_priv->rq) { 404 unregister_blkdev(tr->major, tr->name); 405 kfree(tr->blkcore_priv); 406 up(&mtd_table_mutex); 407 return -ENOMEM; 408 } 409 410 tr->blkcore_priv->rq->queuedata = tr; 411 412 ret = kernel_thread(mtd_blktrans_thread, tr, CLONE_KERNEL); 413 if (ret < 0) { 414 blk_cleanup_queue(tr->blkcore_priv->rq); 415 unregister_blkdev(tr->major, tr->name); 416 kfree(tr->blkcore_priv); 417 up(&mtd_table_mutex); 418 return ret; 419 } 420 421 INIT_LIST_HEAD(&tr->devs); 422 list_add(&tr->list, &blktrans_majors); 423 424 for (i=0; i<MAX_MTD_DEVICES; i++) { 425 if (mtd_table[i] && mtd_table[i]->type != MTD_ABSENT) 426 tr->add_mtd(tr, mtd_table[i]); 427 } 428 429 up(&mtd_table_mutex); 430 431 return 0; 432 } 433 434 int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr) 435 { 436 struct list_head *this, *next; 437 438 down(&mtd_table_mutex); 439 440 /* Clean up the kernel thread */ 441 tr->blkcore_priv->exiting = 1; 442 wake_up(&tr->blkcore_priv->thread_wq); 443 wait_for_completion(&tr->blkcore_priv->thread_dead); 444 445 /* Remove it from the list of active majors */ 446 list_del(&tr->list); 447 448 list_for_each_safe(this, next, &tr->devs) { 449 struct mtd_blktrans_dev *dev = list_entry(this, struct mtd_blktrans_dev, list); 450 tr->remove_dev(dev); 451 } 452 453 blk_cleanup_queue(tr->blkcore_priv->rq); 454 unregister_blkdev(tr->major, tr->name); 455 456 up(&mtd_table_mutex); 457 458 kfree(tr->blkcore_priv); 459 460 if (!list_empty(&tr->devs)) 461 BUG(); 462 return 0; 463 } 464 465 static void __exit mtd_blktrans_exit(void) 466 { 467 /* No race here -- if someone's currently in register_mtd_blktrans 468 we're screwed anyway. */ 469 if (blktrans_notifier.list.next) 470 unregister_mtd_user(&blktrans_notifier); 471 } 472 473 module_exit(mtd_blktrans_exit); 474 475 EXPORT_SYMBOL_GPL(register_mtd_blktrans); 476 EXPORT_SYMBOL_GPL(deregister_mtd_blktrans); 477 EXPORT_SYMBOL_GPL(add_mtd_blktrans_dev); 478 EXPORT_SYMBOL_GPL(del_mtd_blktrans_dev); 479 480 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>"); 481 MODULE_LICENSE("GPL"); 482 MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'"); 483