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