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