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