drivers/mtd/mtd_blkdevs.c

   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/spinlock.h>
  18 #include <linux/hdreg.h>
  19 #include <linux/init.h>
  20 #include <linux/mutex.h>
  21 #include <linux/kthread.h>
  22 #include <asm/uaccess.h>
  23
  24 #include "mtdcore.h"
  25
  26 static LIST_HEAD(blktrans_majors);
  27 static DEFINE_MUTEX(blktrans_ref_mutex);
  28
  29 void blktrans_dev_release(struct kref *kref)
  30 {
  31         struct mtd_blktrans_dev *dev =
  32                 container_of(kref, struct mtd_blktrans_dev, ref);
  33
  34         dev->disk->private_data = NULL;
  35         blk_cleanup_queue(dev->rq);
  36         put_disk(dev->disk);
  37         list_del(&dev->list);
  38         kfree(dev);
  39 }
  40
  41 static struct mtd_blktrans_dev *blktrans_dev_get(struct gendisk *disk)
  42 {
  43         struct mtd_blktrans_dev *dev;
  44
  45         mutex_lock(&blktrans_ref_mutex);
  46         dev = disk->private_data;
  47
  48         if (!dev)
  49                 goto unlock;
  50         kref_get(&dev->ref);
  51 unlock:
  52         mutex_unlock(&blktrans_ref_mutex);
  53         return dev;
  54 }
  55
  56 void blktrans_dev_put(struct mtd_blktrans_dev *dev)
  57 {
  58         mutex_lock(&blktrans_ref_mutex);
  59         kref_put(&dev->ref, blktrans_dev_release);
  60         mutex_unlock(&blktrans_ref_mutex);
  61 }
  62
  63
  64 static int do_blktrans_request(struct mtd_blktrans_ops *tr,
  65                                struct mtd_blktrans_dev *dev,
  66                                struct request *req)
  67 {
  68         unsigned long block, nsect;
  69         char *buf;
  70
  71         block = blk_rq_pos(req) << 9 >> tr->blkshift;
  72         nsect = blk_rq_cur_bytes(req) >> tr->blkshift;
  73
  74         buf = req->buffer;
  75
  76         if (!blk_fs_request(req))
  77                 return -EIO;
  78
  79         if (blk_rq_pos(req) + blk_rq_cur_sectors(req) >
  80             get_capacity(req->rq_disk))
  81                 return -EIO;
  82
  83         if (blk_discard_rq(req))
  84                 return tr->discard(dev, block, nsect);
  85
  86         switch(rq_data_dir(req)) {
  87         case READ:
  88                 for (; nsect > 0; nsect--, block++, buf += tr->blksize)
  89                         if (tr->readsect(dev, block, buf))
  90                                 return -EIO;
  91                 rq_flush_dcache_pages(req);
  92                 return 0;
  93         case WRITE:
  94                 if (!tr->writesect)
  95                         return -EIO;
  96
  97                 rq_flush_dcache_pages(req);
  98                 for (; nsect > 0; nsect--, block++, buf += tr->blksize)
  99                         if (tr->writesect(dev, block, buf))
 100                                 return -EIO;
 101                 return 0;
 102         default:
 103                 printk(KERN_NOTICE "Unknown request %u\n", rq_data_dir(req));
 104                 return -EIO;
 105         }
 106 }
 107
 108 static int mtd_blktrans_thread(void *arg)
 109 {
 110         struct mtd_blktrans_dev *dev = arg;
 111         struct request_queue *rq = dev->rq;
 112         struct request *req = NULL;
 113
 114         spin_lock_irq(rq->queue_lock);
 115
 116         while (!kthread_should_stop()) {
 117                 int res;
 118
 119                 if (!req && !(req = blk_fetch_request(rq))) {
 120                         set_current_state(TASK_INTERRUPTIBLE);
 121                         spin_unlock_irq(rq->queue_lock);
 122                         schedule();
 123                         spin_lock_irq(rq->queue_lock);
 124                         continue;
 125                 }
 126
 127                 spin_unlock_irq(rq->queue_lock);
 128
 129                 mutex_lock(&dev->lock);
 130                 res = do_blktrans_request(dev->tr, dev, req);
 131                 mutex_unlock(&dev->lock);
 132
 133                 spin_lock_irq(rq->queue_lock);
 134
 135                 if (!__blk_end_request_cur(req, res))
 136                         req = NULL;
 137         }
 138
 139         if (req)
 140                 __blk_end_request_all(req, -EIO);
 141
 142         spin_unlock_irq(rq->queue_lock);
 143
 144         return 0;
 145 }
 146
 147 static void mtd_blktrans_request(struct request_queue *rq)
 148 {
 149         struct mtd_blktrans_dev *dev;
 150         struct request *req = NULL;
 151
 152         dev = rq->queuedata;
 153
 154         if (!dev)
 155                 while ((req = blk_fetch_request(rq)) != NULL)
 156                         __blk_end_request_all(req, -ENODEV);
 157         else
 158                 wake_up_process(dev->thread);
 159 }
 160
 161 static int blktrans_open(struct block_device *bdev, fmode_t mode)
 162 {
 163         struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
 164         int ret;
 165
 166         if (!dev)
 167                 return -ERESTARTSYS;
 168
 169         mutex_lock(&dev->lock);
 170
 171         if (!dev->mtd) {
 172                 ret = -ENXIO;
 173                 goto unlock;
 174         }
 175
 176         ret = !dev->open++ && dev->tr->open ? dev->tr->open(dev) : 0;
 177
 178         /* Take another reference on the device so it won't go away till
 179                 last release */
 180         if (!ret)
 181                 kref_get(&dev->ref);
 182 unlock:
 183         mutex_unlock(&dev->lock);
 184         blktrans_dev_put(dev);
 185         return ret;
 186 }
 187
 188 static int blktrans_release(struct gendisk *disk, fmode_t mode)
 189 {
 190         struct mtd_blktrans_dev *dev = blktrans_dev_get(disk);
 191         int ret = -ENXIO;
 192
 193         if (!dev)
 194                 return ret;
 195
 196         mutex_lock(&dev->lock);
 197
 198         /* Release one reference, we sure its not the last one here*/
 199         kref_put(&dev->ref, blktrans_dev_release);
 200
 201         if (!dev->mtd)
 202                 goto unlock;
 203
 204         ret = !--dev->open && dev->tr->release ? dev->tr->release(dev) : 0;
 205 unlock:
 206         mutex_unlock(&dev->lock);
 207         blktrans_dev_put(dev);
 208         return ret;
 209 }
 210
 211 static int blktrans_getgeo(struct block_device *bdev, struct hd_geometry *geo)
 212 {
 213         struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
 214         int ret = -ENXIO;
 215
 216         if (!dev)
 217                 return ret;
 218
 219         mutex_lock(&dev->lock);
 220
 221         if (!dev->mtd)
 222                 goto unlock;
 223
 224         ret = dev->tr->getgeo ? dev->tr->getgeo(dev, geo) : 0;
 225 unlock:
 226         mutex_unlock(&dev->lock);
 227         blktrans_dev_put(dev);
 228         return ret;
 229 }
 230
 231 static int blktrans_ioctl(struct block_device *bdev, fmode_t mode,
 232                               unsigned int cmd, unsigned long arg)
 233 {
 234         struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
 235         int ret = -ENXIO;
 236
 237         if (!dev)
 238                 return ret;
 239
 240         mutex_lock(&dev->lock);
 241
 242         if (!dev->mtd)
 243                 goto unlock;
 244
 245         switch (cmd) {
 246         case BLKFLSBUF:
 247                 ret = dev->tr->flush ? dev->tr->flush(dev) : 0;
 248         default:
 249                 ret = -ENOTTY;
 250         }
 251 unlock:
 252         mutex_unlock(&dev->lock);
 253         blktrans_dev_put(dev);
 254         return ret;
 255 }
 256
 257 static const struct block_device_operations mtd_blktrans_ops = {
 258         .owner          = THIS_MODULE,
 259         .open           = blktrans_open,
 260         .release        = blktrans_release,
 261         .locked_ioctl   = blktrans_ioctl,
 262         .getgeo         = blktrans_getgeo,
 263 };
 264
 265 int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
 266 {
 267         struct mtd_blktrans_ops *tr = new->tr;
 268         struct mtd_blktrans_dev *d;
 269         int last_devnum = -1;
 270         struct gendisk *gd;
 271         int ret;
 272
 273         if (mutex_trylock(&mtd_table_mutex)) {
 274                 mutex_unlock(&mtd_table_mutex);
 275                 BUG();
 276         }
 277
 278         mutex_lock(&blktrans_ref_mutex);
 279         list_for_each_entry(d, &tr->devs, list) {
 280                 if (new->devnum == -1) {
 281                         /* Use first free number */
 282                         if (d->devnum != last_devnum+1) {
 283                                 /* Found a free devnum. Plug it in here */
 284                                 new->devnum = last_devnum+1;
 285                                 list_add_tail(&new->list, &d->list);
 286                                 goto added;
 287                         }
 288                 } else if (d->devnum == new->devnum) {
 289                         /* Required number taken */
 290                         mutex_unlock(&blktrans_ref_mutex);
 291                         return -EBUSY;
 292                 } else if (d->devnum > new->devnum) {
 293                         /* Required number was free */
 294                         list_add_tail(&new->list, &d->list);
 295                         goto added;
 296                 }
 297                 last_devnum = d->devnum;
 298         }
 299
 300         ret = -EBUSY;
 301         if (new->devnum == -1)
 302                 new->devnum = last_devnum+1;
 303
 304         /* Check that the device and any partitions will get valid
 305          * minor numbers and that the disk naming code below can cope
 306          * with this number. */
 307         if (new->devnum > (MINORMASK >> tr->part_bits) ||
 308             (tr->part_bits && new->devnum >= 27 * 26)) {
 309                 mutex_unlock(&blktrans_ref_mutex);
 310                 goto error1;
 311         }
 312
 313         list_add_tail(&new->list, &tr->devs);
 314  added:
 315         mutex_unlock(&blktrans_ref_mutex);
 316
 317         mutex_init(&new->lock);
 318         kref_init(&new->ref);
 319         if (!tr->writesect)
 320                 new->readonly = 1;
 321
 322         /* Create gendisk */
 323         ret = -ENOMEM;
 324         gd = alloc_disk(1 << tr->part_bits);
 325
 326         if (!gd)
 327                 goto error2;
 328
 329         new->disk = gd;
 330         gd->private_data = new;
 331         gd->major = tr->major;
 332         gd->first_minor = (new->devnum) << tr->part_bits;
 333         gd->fops = &mtd_blktrans_ops;
 334
 335         if (tr->part_bits)
 336                 if (new->devnum < 26)
 337                         snprintf(gd->disk_name, sizeof(gd->disk_name),
 338                                  "%s%c", tr->name, 'a' + new->devnum);
 339                 else
 340                         snprintf(gd->disk_name, sizeof(gd->disk_name),
 341                                  "%s%c%c", tr->name,
 342                                  'a' - 1 + new->devnum / 26,
 343                                  'a' + new->devnum % 26);
 344         else
 345                 snprintf(gd->disk_name, sizeof(gd->disk_name),
 346                          "%s%d", tr->name, new->devnum);
 347
 348         set_capacity(gd, (new->size * tr->blksize) >> 9);
 349
 350         /* Create the request queue */
 351         spin_lock_init(&new->queue_lock);
 352         new->rq = blk_init_queue(mtd_blktrans_request, &new->queue_lock);
 353
 354         if (!new->rq)
 355                 goto error3;
 356
 357         new->rq->queuedata = new;
 358         blk_queue_logical_block_size(new->rq, tr->blksize);
 359
 360         if (tr->discard)
 361                 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD,
 362                                         new->rq);
 363
 364         gd->queue = new->rq;
 365
 366         __get_mtd_device(new->mtd);
 367         __module_get(tr->owner);
 368
 369         /* Create processing thread */
 370         /* TODO: workqueue ? */
 371         new->thread = kthread_run(mtd_blktrans_thread, new,
 372                         "%s%d", tr->name, new->mtd->index);
 373         if (IS_ERR(new->thread)) {
 374                 ret = PTR_ERR(new->thread);
 375                 goto error4;
 376         }
 377         gd->driverfs_dev = &new->mtd->dev;
 378
 379         if (new->readonly)
 380                 set_disk_ro(gd, 1);
 381
 382         add_disk(gd);
 383
 384         if (new->disk_attributes) {
 385                 ret = sysfs_create_group(&disk_to_dev(gd)->kobj,
 386                                         new->disk_attributes);
 387                 WARN_ON(ret);
 388         }
 389         return 0;
 390 error4:
 391         module_put(tr->owner);
 392         __put_mtd_device(new->mtd);
 393         blk_cleanup_queue(new->rq);
 394 error3:
 395         put_disk(new->disk);
 396 error2:
 397         list_del(&new->list);
 398 error1:
 399         kfree(new);
 400         return ret;
 401 }
 402
 403 int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old)
 404 {
 405         unsigned long flags;
 406
 407         if (mutex_trylock(&mtd_table_mutex)) {
 408                 mutex_unlock(&mtd_table_mutex);
 409                 BUG();
 410         }
 411
 412         /* Stop new requests to arrive */
 413         del_gendisk(old->disk);
 414
 415         if (old->disk_attributes)
 416                 sysfs_remove_group(&disk_to_dev(old->disk)->kobj,
 417                                                 old->disk_attributes);
 418
 419         /* Stop the thread */
 420         kthread_stop(old->thread);
 421
 422         /* Kill current requests */
 423         spin_lock_irqsave(&old->queue_lock, flags);
 424         old->rq->queuedata = NULL;
 425         blk_start_queue(old->rq);
 426         spin_unlock_irqrestore(&old->queue_lock, flags);
 427
 428         /* Ask trans driver for release to the mtd device */
 429         mutex_lock(&old->lock);
 430         if (old->open && old->tr->release) {
 431                 old->tr->release(old);
 432                 old->open = 0;
 433         }
 434
 435         __put_mtd_device(old->mtd);
 436         module_put(old->tr->owner);
 437
 438         /* At that point, we don't touch the mtd anymore */
 439         old->mtd = NULL;
 440
 441         mutex_unlock(&old->lock);
 442         blktrans_dev_put(old);
 443         return 0;
 444 }
 445
 446 static void blktrans_notify_remove(struct mtd_info *mtd)
 447 {
 448         struct mtd_blktrans_ops *tr;
 449         struct mtd_blktrans_dev *dev, *next;
 450
 451         list_for_each_entry(tr, &blktrans_majors, list)
 452                 list_for_each_entry_safe(dev, next, &tr->devs, list)
 453                         if (dev->mtd == mtd)
 454                                 tr->remove_dev(dev);
 455 }
 456
 457 static void blktrans_notify_add(struct mtd_info *mtd)
 458 {
 459         struct mtd_blktrans_ops *tr;
 460
 461         if (mtd->type == MTD_ABSENT)
 462                 return;
 463
 464         list_for_each_entry(tr, &blktrans_majors, list)
 465                 tr->add_mtd(tr, mtd);
 466 }
 467
 468 static struct mtd_notifier blktrans_notifier = {
 469         .add = blktrans_notify_add,
 470         .remove = blktrans_notify_remove,
 471 };
 472
 473 int register_mtd_blktrans(struct mtd_blktrans_ops *tr)
 474 {
 475         struct mtd_info *mtd;
 476         int ret;
 477
 478         /* Register the notifier if/when the first device type is
 479            registered, to prevent the link/init ordering from fucking
 480            us over. */
 481         if (!blktrans_notifier.list.next)
 482                 register_mtd_user(&blktrans_notifier);
 483
 484
 485         mutex_lock(&mtd_table_mutex);
 486
 487         ret = register_blkdev(tr->major, tr->name);
 488         if (ret) {
 489                 printk(KERN_WARNING "Unable to register %s block device on major %d: %d\n",
 490                        tr->name, tr->major, ret);
 491                 mutex_unlock(&mtd_table_mutex);
 492                 return ret;
 493         }
 494
 495         tr->blkshift = ffs(tr->blksize) - 1;
 496
 497         INIT_LIST_HEAD(&tr->devs);
 498         list_add(&tr->list, &blktrans_majors);
 499
 500         mtd_for_each_device(mtd)
 501                 if (mtd->type != MTD_ABSENT)
 502                         tr->add_mtd(tr, mtd);
 503
 504         mutex_unlock(&mtd_table_mutex);
 505         return 0;
 506 }
 507
 508 int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr)
 509 {
 510         struct mtd_blktrans_dev *dev, *next;
 511
 512         mutex_lock(&mtd_table_mutex);
 513
 514         /* Remove it from the list of active majors */
 515         list_del(&tr->list);
 516
 517         list_for_each_entry_safe(dev, next, &tr->devs, list)
 518                 tr->remove_dev(dev);
 519
 520         unregister_blkdev(tr->major, tr->name);
 521         mutex_unlock(&mtd_table_mutex);
 522
 523         BUG_ON(!list_empty(&tr->devs));
 524         return 0;
 525 }
 526
 527 static void __exit mtd_blktrans_exit(void)
 528 {
 529         /* No race here -- if someone's currently in register_mtd_blktrans
 530            we're screwed anyway. */
 531         if (blktrans_notifier.list.next)
 532                 unregister_mtd_user(&blktrans_notifier);
 533 }
 534
 535 module_exit(mtd_blktrans_exit);
 536
 537 EXPORT_SYMBOL_GPL(register_mtd_blktrans);
 538 EXPORT_SYMBOL_GPL(deregister_mtd_blktrans);
 539 EXPORT_SYMBOL_GPL(add_mtd_blktrans_dev);
 540 EXPORT_SYMBOL_GPL(del_mtd_blktrans_dev);
 541
 542 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
 543 MODULE_LICENSE("GPL");
 544 MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'");