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