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