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 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'");