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/smp_lock.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 static DEFINE_MUTEX(blktrans_ref_mutex);
  29
  30 void blktrans_dev_release(struct kref *kref)
  31 {
  32         struct mtd_blktrans_dev *dev =
  33                 container_of(kref, struct mtd_blktrans_dev, ref);
  34
  35         dev->disk->private_data = NULL;
  36         blk_cleanup_queue(dev->rq);
  37         put_disk(dev->disk);
  38         list_del(&dev->list);
  39         kfree(dev);
  40 }
  41
  42 static struct mtd_blktrans_dev *blktrans_dev_get(struct gendisk *disk)
  43 {
  44         struct mtd_blktrans_dev *dev;
  45
  46         mutex_lock(&blktrans_ref_mutex);
  47         dev = disk->private_data;
  48
  49         if (!dev)
  50                 goto unlock;
  51         kref_get(&dev->ref);
  52 unlock:
  53         mutex_unlock(&blktrans_ref_mutex);
  54         return dev;
  55 }
  56
  57 void blktrans_dev_put(struct mtd_blktrans_dev *dev)
  58 {
  59         mutex_lock(&blktrans_ref_mutex);
  60         kref_put(&dev->ref, blktrans_dev_release);
  61         mutex_unlock(&blktrans_ref_mutex);
  62 }
  63
  64
  65 static int do_blktrans_request(struct mtd_blktrans_ops *tr,
  66                                struct mtd_blktrans_dev *dev,
  67                                struct request *req)
  68 {
  69         unsigned long block, nsect;
  70         char *buf;
  71
  72         block = blk_rq_pos(req) << 9 >> tr->blkshift;
  73         nsect = blk_rq_cur_bytes(req) >> tr->blkshift;
  74
  75         buf = req->buffer;
  76
  77         if (req->cmd_type != REQ_TYPE_FS)
  78                 return -EIO;
  79
  80         if (blk_rq_pos(req) + blk_rq_cur_sectors(req) >
  81             get_capacity(req->rq_disk))
  82                 return -EIO;
  83
  84         if (req->cmd_flags & REQ_DISCARD)
  85                 return tr->discard(dev, block, nsect);
  86
  87         switch(rq_data_dir(req)) {
  88         case READ:
  89                 for (; nsect > 0; nsect--, block++, buf += tr->blksize)
  90                         if (tr->readsect(dev, block, buf))
  91                                 return -EIO;
  92                 rq_flush_dcache_pages(req);
  93                 return 0;
  94         case WRITE:
  95                 if (!tr->writesect)
  96                         return -EIO;
  97
  98                 rq_flush_dcache_pages(req);
  99                 for (; nsect > 0; nsect--, block++, buf += tr->blksize)
 100                         if (tr->writesect(dev, block, buf))
 101                                 return -EIO;
 102                 return 0;
 103         default:
 104                 printk(KERN_NOTICE "Unknown request %u\n", rq_data_dir(req));
 105                 return -EIO;
 106         }
 107 }
 108
 109 static int mtd_blktrans_thread(void *arg)
 110 {
 111         struct mtd_blktrans_dev *dev = arg;
 112         struct request_queue *rq = dev->rq;
 113         struct request *req = NULL;
 114
 115         spin_lock_irq(rq->queue_lock);
 116
 117         while (!kthread_should_stop()) {
 118                 int res;
 119
 120                 if (!req && !(req = blk_fetch_request(rq))) {
 121                         set_current_state(TASK_INTERRUPTIBLE);
 122                         spin_unlock_irq(rq->queue_lock);
 123                         schedule();
 124                         spin_lock_irq(rq->queue_lock);
 125                         continue;
 126                 }
 127
 128                 spin_unlock_irq(rq->queue_lock);
 129
 130                 mutex_lock(&dev->lock);
 131                 res = do_blktrans_request(dev->tr, dev, req);
 132                 mutex_unlock(&dev->lock);
 133
 134                 spin_lock_irq(rq->queue_lock);
 135
 136                 if (!__blk_end_request_cur(req, res))
 137                         req = NULL;
 138         }
 139
 140         if (req)
 141                 __blk_end_request_all(req, -EIO);
 142
 143         spin_unlock_irq(rq->queue_lock);
 144
 145         return 0;
 146 }
 147
 148 static void mtd_blktrans_request(struct request_queue *rq)
 149 {
 150         struct mtd_blktrans_dev *dev;
 151         struct request *req = NULL;
 152
 153         dev = rq->queuedata;
 154
 155         if (!dev)
 156                 while ((req = blk_fetch_request(rq)) != NULL)
 157                         __blk_end_request_all(req, -ENODEV);
 158         else
 159                 wake_up_process(dev->thread);
 160 }
 161
 162 static int blktrans_open(struct block_device *bdev, fmode_t mode)
 163 {
 164         struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
 165         int ret;
 166
 167         if (!dev)
 168                 return -ERESTARTSYS; /* FIXME: busy loop! -arnd*/
 169
 170         lock_kernel();
 171         mutex_lock(&dev->lock);
 172
 173         if (!dev->mtd) {
 174                 ret = -ENXIO;
 175                 goto unlock;
 176         }
 177
 178         ret = !dev->open++ && dev->tr->open ? dev->tr->open(dev) : 0;
 179
 180         /* Take another reference on the device so it won't go away till
 181                 last release */
 182         if (!ret)
 183                 kref_get(&dev->ref);
 184 unlock:
 185         mutex_unlock(&dev->lock);
 186         blktrans_dev_put(dev);
 187         unlock_kernel();
 188         return ret;
 189 }
 190
 191 static int blktrans_release(struct gendisk *disk, fmode_t mode)
 192 {
 193         struct mtd_blktrans_dev *dev = blktrans_dev_get(disk);
 194         int ret = -ENXIO;
 195
 196         if (!dev)
 197                 return ret;
 198
 199         lock_kernel();
 200         mutex_lock(&dev->lock);
 201
 202         /* Release one reference, we sure its not the last one here*/
 203         kref_put(&dev->ref, blktrans_dev_release);
 204
 205         if (!dev->mtd)
 206                 goto unlock;
 207
 208         ret = !--dev->open && dev->tr->release ? dev->tr->release(dev) : 0;
 209 unlock:
 210         mutex_unlock(&dev->lock);
 211         blktrans_dev_put(dev);
 212         unlock_kernel();
 213         return ret;
 214 }
 215
 216 static int blktrans_getgeo(struct block_device *bdev, struct hd_geometry *geo)
 217 {
 218         struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
 219         int ret = -ENXIO;
 220
 221         if (!dev)
 222                 return ret;
 223
 224         mutex_lock(&dev->lock);
 225
 226         if (!dev->mtd)
 227                 goto unlock;
 228
 229         ret = dev->tr->getgeo ? dev->tr->getgeo(dev, geo) : 0;
 230 unlock:
 231         mutex_unlock(&dev->lock);
 232         blktrans_dev_put(dev);
 233         return ret;
 234 }
 235
 236 static int blktrans_ioctl(struct block_device *bdev, fmode_t mode,
 237                               unsigned int cmd, unsigned long arg)
 238 {
 239         struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
 240         int ret = -ENXIO;
 241
 242         if (!dev)
 243                 return ret;
 244
 245         lock_kernel();
 246         mutex_lock(&dev->lock);
 247
 248         if (!dev->mtd)
 249                 goto unlock;
 250
 251         switch (cmd) {
 252         case BLKFLSBUF:
 253                 ret = dev->tr->flush ? dev->tr->flush(dev) : 0;
 254         default:
 255                 ret = -ENOTTY;
 256         }
 257 unlock:
 258         mutex_unlock(&dev->lock);
 259         unlock_kernel();
 260         blktrans_dev_put(dev);
 261         return ret;
 262 }
 263
 264 static const struct block_device_operations mtd_blktrans_ops = {
 265         .owner          = THIS_MODULE,
 266         .open           = blktrans_open,
 267         .release        = blktrans_release,
 268         .ioctl          = blktrans_ioctl,
 269         .getgeo         = blktrans_getgeo,
 270 };
 271
 272 int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
 273 {
 274         struct mtd_blktrans_ops *tr = new->tr;
 275         struct mtd_blktrans_dev *d;
 276         int last_devnum = -1;
 277         struct gendisk *gd;
 278         int ret;
 279
 280         if (mutex_trylock(&mtd_table_mutex)) {
 281                 mutex_unlock(&mtd_table_mutex);
 282                 BUG();
 283         }
 284
 285         mutex_lock(&blktrans_ref_mutex);
 286         list_for_each_entry(d, &tr->devs, list) {
 287                 if (new->devnum == -1) {
 288                         /* Use first free number */
 289                         if (d->devnum != last_devnum+1) {
 290                                 /* Found a free devnum. Plug it in here */
 291                                 new->devnum = last_devnum+1;
 292                                 list_add_tail(&new->list, &d->list);
 293                                 goto added;
 294                         }
 295                 } else if (d->devnum == new->devnum) {
 296                         /* Required number taken */
 297                         mutex_unlock(&blktrans_ref_mutex);
 298                         return -EBUSY;
 299                 } else if (d->devnum > new->devnum) {
 300                         /* Required number was free */
 301                         list_add_tail(&new->list, &d->list);
 302                         goto added;
 303                 }
 304                 last_devnum = d->devnum;
 305         }
 306
 307         ret = -EBUSY;
 308         if (new->devnum == -1)
 309                 new->devnum = last_devnum+1;
 310
 311         /* Check that the device and any partitions will get valid
 312          * minor numbers and that the disk naming code below can cope
 313          * with this number. */
 314         if (new->devnum > (MINORMASK >> tr->part_bits) ||
 315             (tr->part_bits && new->devnum >= 27 * 26)) {
 316                 mutex_unlock(&blktrans_ref_mutex);
 317                 goto error1;
 318         }
 319
 320         list_add_tail(&new->list, &tr->devs);
 321  added:
 322         mutex_unlock(&blktrans_ref_mutex);
 323
 324         mutex_init(&new->lock);
 325         kref_init(&new->ref);
 326         if (!tr->writesect)
 327                 new->readonly = 1;
 328
 329         /* Create gendisk */
 330         ret = -ENOMEM;
 331         gd = alloc_disk(1 << tr->part_bits);
 332
 333         if (!gd)
 334                 goto error2;
 335
 336         new->disk = gd;
 337         gd->private_data = new;
 338         gd->major = tr->major;
 339         gd->first_minor = (new->devnum) << tr->part_bits;
 340         gd->fops = &mtd_blktrans_ops;
 341
 342         if (tr->part_bits)
 343                 if (new->devnum < 26)
 344                         snprintf(gd->disk_name, sizeof(gd->disk_name),
 345                                  "%s%c", tr->name, 'a' + new->devnum);
 346                 else
 347                         snprintf(gd->disk_name, sizeof(gd->disk_name),
 348                                  "%s%c%c", tr->name,
 349                                  'a' - 1 + new->devnum / 26,
 350                                  'a' + new->devnum % 26);
 351         else
 352                 snprintf(gd->disk_name, sizeof(gd->disk_name),
 353                          "%s%d", tr->name, new->devnum);
 354
 355         set_capacity(gd, (new->size * tr->blksize) >> 9);
 356
 357         /* Create the request queue */
 358         spin_lock_init(&new->queue_lock);
 359         new->rq = blk_init_queue(mtd_blktrans_request, &new->queue_lock);
 360
 361         if (!new->rq)
 362                 goto error3;
 363
 364         new->rq->queuedata = new;
 365         blk_queue_logical_block_size(new->rq, tr->blksize);
 366
 367         if (tr->discard)
 368                 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD,
 369                                         new->rq);
 370
 371         gd->queue = new->rq;
 372
 373         __get_mtd_device(new->mtd);
 374         __module_get(tr->owner);
 375
 376         /* Create processing thread */
 377         /* TODO: workqueue ? */
 378         new->thread = kthread_run(mtd_blktrans_thread, new,
 379                         "%s%d", tr->name, new->mtd->index);
 380         if (IS_ERR(new->thread)) {
 381                 ret = PTR_ERR(new->thread);
 382                 goto error4;
 383         }
 384         gd->driverfs_dev = &new->mtd->dev;
 385
 386         if (new->readonly)
 387                 set_disk_ro(gd, 1);
 388
 389         add_disk(gd);
 390
 391         if (new->disk_attributes) {
 392                 ret = sysfs_create_group(&disk_to_dev(gd)->kobj,
 393                                         new->disk_attributes);
 394                 WARN_ON(ret);
 395         }
 396         return 0;
 397 error4:
 398         module_put(tr->owner);
 399         __put_mtd_device(new->mtd);
 400         blk_cleanup_queue(new->rq);
 401 error3:
 402         put_disk(new->disk);
 403 error2:
 404         list_del(&new->list);
 405 error1:
 406         kfree(new);
 407         return ret;
 408 }
 409
 410 int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old)
 411 {
 412         unsigned long flags;
 413
 414         if (mutex_trylock(&mtd_table_mutex)) {
 415                 mutex_unlock(&mtd_table_mutex);
 416                 BUG();
 417         }
 418
 419         /* Stop new requests to arrive */
 420         del_gendisk(old->disk);
 421
 422         if (old->disk_attributes)
 423                 sysfs_remove_group(&disk_to_dev(old->disk)->kobj,
 424                                                 old->disk_attributes);
 425
 426         /* Stop the thread */
 427         kthread_stop(old->thread);
 428
 429         /* Kill current requests */
 430         spin_lock_irqsave(&old->queue_lock, flags);
 431         old->rq->queuedata = NULL;
 432         blk_start_queue(old->rq);
 433         spin_unlock_irqrestore(&old->queue_lock, flags);
 434
 435         /* Ask trans driver for release to the mtd device */
 436         mutex_lock(&old->lock);
 437         if (old->open && old->tr->release) {
 438                 old->tr->release(old);
 439                 old->open = 0;
 440         }
 441
 442         __put_mtd_device(old->mtd);
 443         module_put(old->tr->owner);
 444
 445         /* At that point, we don't touch the mtd anymore */
 446         old->mtd = NULL;
 447
 448         mutex_unlock(&old->lock);
 449         blktrans_dev_put(old);
 450         return 0;
 451 }
 452
 453 static void blktrans_notify_remove(struct mtd_info *mtd)
 454 {
 455         struct mtd_blktrans_ops *tr;
 456         struct mtd_blktrans_dev *dev, *next;
 457
 458         list_for_each_entry(tr, &blktrans_majors, list)
 459                 list_for_each_entry_safe(dev, next, &tr->devs, list)
 460                         if (dev->mtd == mtd)
 461                                 tr->remove_dev(dev);
 462 }
 463
 464 static void blktrans_notify_add(struct mtd_info *mtd)
 465 {
 466         struct mtd_blktrans_ops *tr;
 467
 468         if (mtd->type == MTD_ABSENT)
 469                 return;
 470
 471         list_for_each_entry(tr, &blktrans_majors, list)
 472                 tr->add_mtd(tr, mtd);
 473 }
 474
 475 static struct mtd_notifier blktrans_notifier = {
 476         .add = blktrans_notify_add,
 477         .remove = blktrans_notify_remove,
 478 };
 479
 480 int register_mtd_blktrans(struct mtd_blktrans_ops *tr)
 481 {
 482         struct mtd_info *mtd;
 483         int ret;
 484
 485         /* Register the notifier if/when the first device type is
 486            registered, to prevent the link/init ordering from fucking
 487            us over. */
 488         if (!blktrans_notifier.list.next)
 489                 register_mtd_user(&blktrans_notifier);
 490
 491
 492         mutex_lock(&mtd_table_mutex);
 493
 494         ret = register_blkdev(tr->major, tr->name);
 495         if (ret) {
 496                 printk(KERN_WARNING "Unable to register %s block device on major %d: %d\n",
 497                        tr->name, tr->major, ret);
 498                 mutex_unlock(&mtd_table_mutex);
 499                 return ret;
 500         }
 501
 502         tr->blkshift = ffs(tr->blksize) - 1;
 503
 504         INIT_LIST_HEAD(&tr->devs);
 505         list_add(&tr->list, &blktrans_majors);
 506
 507         mtd_for_each_device(mtd)
 508                 if (mtd->type != MTD_ABSENT)
 509                         tr->add_mtd(tr, mtd);
 510
 511         mutex_unlock(&mtd_table_mutex);
 512         return 0;
 513 }
 514
 515 int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr)
 516 {
 517         struct mtd_blktrans_dev *dev, *next;
 518
 519         mutex_lock(&mtd_table_mutex);
 520
 521         /* Remove it from the list of active majors */
 522         list_del(&tr->list);
 523
 524         list_for_each_entry_safe(dev, next, &tr->devs, list)
 525                 tr->remove_dev(dev);
 526
 527         unregister_blkdev(tr->major, tr->name);
 528         mutex_unlock(&mtd_table_mutex);
 529
 530         BUG_ON(!list_empty(&tr->devs));
 531         return 0;
 532 }
 533
 534 static void __exit mtd_blktrans_exit(void)
 535 {
 536         /* No race here -- if someone's currently in register_mtd_blktrans
 537            we're screwed anyway. */
 538         if (blktrans_notifier.list.next)
 539                 unregister_mtd_user(&blktrans_notifier);
 540 }
 541
 542 module_exit(mtd_blktrans_exit);
 543
 544 EXPORT_SYMBOL_GPL(register_mtd_blktrans);
 545 EXPORT_SYMBOL_GPL(deregister_mtd_blktrans);
 546 EXPORT_SYMBOL_GPL(add_mtd_blktrans_dev);
 547 EXPORT_SYMBOL_GPL(del_mtd_blktrans_dev);
 548
 549 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
 550 MODULE_LICENSE("GPL");
 551 MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'");