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