linux/drivers/mtd/mtd_blkdevs.c
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   1/*
   2 * Interface to Linux block layer for MTD 'translation layers'.
   3 *
   4 * Copyright © 2003-2010 David Woodhouse <dwmw2@infradead.org>
   5 *
   6 * This program is free software; you can redistribute it and/or modify
   7 * it under the terms of the GNU General Public License as published by
   8 * the Free Software Foundation; either version 2 of the License, or
   9 * (at your option) any later version.
  10 *
  11 * This program is distributed in the hope that it will be useful,
  12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 * GNU General Public License for more details.
  15 *
  16 * You should have received a copy of the GNU General Public License
  17 * along with this program; if not, write to the Free Software
  18 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  19 *
  20 */
  21
  22#include <linux/kernel.h>
  23#include <linux/slab.h>
  24#include <linux/module.h>
  25#include <linux/list.h>
  26#include <linux/fs.h>
  27#include <linux/mtd/blktrans.h>
  28#include <linux/mtd/mtd.h>
  29#include <linux/blkdev.h>
  30#include <linux/blkpg.h>
  31#include <linux/spinlock.h>
  32#include <linux/hdreg.h>
  33#include <linux/init.h>
  34#include <linux/mutex.h>
  35#include <asm/uaccess.h>
  36
  37#include "mtdcore.h"
  38
  39static LIST_HEAD(blktrans_majors);
  40static DEFINE_MUTEX(blktrans_ref_mutex);
  41
  42static void blktrans_dev_release(struct kref *kref)
  43{
  44        struct mtd_blktrans_dev *dev =
  45                container_of(kref, struct mtd_blktrans_dev, ref);
  46
  47        dev->disk->private_data = NULL;
  48        blk_cleanup_queue(dev->rq);
  49        put_disk(dev->disk);
  50        list_del(&dev->list);
  51        kfree(dev);
  52}
  53
  54static struct mtd_blktrans_dev *blktrans_dev_get(struct gendisk *disk)
  55{
  56        struct mtd_blktrans_dev *dev;
  57
  58        mutex_lock(&blktrans_ref_mutex);
  59        dev = disk->private_data;
  60
  61        if (!dev)
  62                goto unlock;
  63        kref_get(&dev->ref);
  64unlock:
  65        mutex_unlock(&blktrans_ref_mutex);
  66        return dev;
  67}
  68
  69static void blktrans_dev_put(struct mtd_blktrans_dev *dev)
  70{
  71        mutex_lock(&blktrans_ref_mutex);
  72        kref_put(&dev->ref, blktrans_dev_release);
  73        mutex_unlock(&blktrans_ref_mutex);
  74}
  75
  76
  77static int do_blktrans_request(struct mtd_blktrans_ops *tr,
  78                               struct mtd_blktrans_dev *dev,
  79                               struct request *req)
  80{
  81        unsigned long block, nsect;
  82        char *buf;
  83
  84        block = blk_rq_pos(req) << 9 >> tr->blkshift;
  85        nsect = blk_rq_cur_bytes(req) >> tr->blkshift;
  86
  87        buf = req->buffer;
  88
  89        if (req->cmd_type != REQ_TYPE_FS)
  90                return -EIO;
  91
  92        if (blk_rq_pos(req) + blk_rq_cur_sectors(req) >
  93            get_capacity(req->rq_disk))
  94                return -EIO;
  95
  96        if (req->cmd_flags & REQ_DISCARD)
  97                return tr->discard(dev, block, nsect);
  98
  99        switch(rq_data_dir(req)) {
 100        case READ:
 101                for (; nsect > 0; nsect--, block++, buf += tr->blksize)
 102                        if (tr->readsect(dev, block, buf))
 103                                return -EIO;
 104                rq_flush_dcache_pages(req);
 105                return 0;
 106        case WRITE:
 107                if (!tr->writesect)
 108                        return -EIO;
 109
 110                rq_flush_dcache_pages(req);
 111                for (; nsect > 0; nsect--, block++, buf += tr->blksize)
 112                        if (tr->writesect(dev, block, buf))
 113                                return -EIO;
 114                return 0;
 115        default:
 116                printk(KERN_NOTICE "Unknown request %u\n", rq_data_dir(req));
 117                return -EIO;
 118        }
 119}
 120
 121int mtd_blktrans_cease_background(struct mtd_blktrans_dev *dev)
 122{
 123        return dev->bg_stop;
 124}
 125EXPORT_SYMBOL_GPL(mtd_blktrans_cease_background);
 126
 127static void mtd_blktrans_work(struct work_struct *work)
 128{
 129        struct mtd_blktrans_dev *dev =
 130                container_of(work, struct mtd_blktrans_dev, work);
 131        struct mtd_blktrans_ops *tr = dev->tr;
 132        struct request_queue *rq = dev->rq;
 133        struct request *req = NULL;
 134        int background_done = 0;
 135
 136        spin_lock_irq(rq->queue_lock);
 137
 138        while (1) {
 139                int res;
 140
 141                dev->bg_stop = false;
 142                if (!req && !(req = blk_fetch_request(rq))) {
 143                        if (tr->background && !background_done) {
 144                                spin_unlock_irq(rq->queue_lock);
 145                                mutex_lock(&dev->lock);
 146                                tr->background(dev);
 147                                mutex_unlock(&dev->lock);
 148                                spin_lock_irq(rq->queue_lock);
 149                                /*
 150                                 * Do background processing just once per idle
 151                                 * period.
 152                                 */
 153                                background_done = !dev->bg_stop;
 154                                continue;
 155                        }
 156                        break;
 157                }
 158
 159                spin_unlock_irq(rq->queue_lock);
 160
 161                mutex_lock(&dev->lock);
 162                res = do_blktrans_request(dev->tr, dev, req);
 163                mutex_unlock(&dev->lock);
 164
 165                spin_lock_irq(rq->queue_lock);
 166
 167                if (!__blk_end_request_cur(req, res))
 168                        req = NULL;
 169
 170                background_done = 0;
 171        }
 172
 173        if (req)
 174                __blk_end_request_all(req, -EIO);
 175
 176        spin_unlock_irq(rq->queue_lock);
 177}
 178
 179static void mtd_blktrans_request(struct request_queue *rq)
 180{
 181        struct mtd_blktrans_dev *dev;
 182        struct request *req = NULL;
 183
 184        dev = rq->queuedata;
 185
 186        if (!dev)
 187                while ((req = blk_fetch_request(rq)) != NULL)
 188                        __blk_end_request_all(req, -ENODEV);
 189        else
 190                queue_work(dev->wq, &dev->work);
 191}
 192
 193static int blktrans_open(struct block_device *bdev, fmode_t mode)
 194{
 195        struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
 196        int ret = 0;
 197
 198        if (!dev)
 199                return -ERESTARTSYS; /* FIXME: busy loop! -arnd*/
 200
 201        mutex_lock(&dev->lock);
 202
 203        if (dev->open)
 204                goto unlock;
 205
 206        kref_get(&dev->ref);
 207        __module_get(dev->tr->owner);
 208
 209        if (!dev->mtd)
 210                goto unlock;
 211
 212        if (dev->tr->open) {
 213                ret = dev->tr->open(dev);
 214                if (ret)
 215                        goto error_put;
 216        }
 217
 218        ret = __get_mtd_device(dev->mtd);
 219        if (ret)
 220                goto error_release;
 221        dev->file_mode = mode;
 222
 223unlock:
 224        dev->open++;
 225        mutex_unlock(&dev->lock);
 226        blktrans_dev_put(dev);
 227        return ret;
 228
 229error_release:
 230        if (dev->tr->release)
 231                dev->tr->release(dev);
 232error_put:
 233        module_put(dev->tr->owner);
 234        kref_put(&dev->ref, blktrans_dev_release);
 235        mutex_unlock(&dev->lock);
 236        blktrans_dev_put(dev);
 237        return ret;
 238}
 239
 240static int blktrans_release(struct gendisk *disk, fmode_t mode)
 241{
 242        struct mtd_blktrans_dev *dev = blktrans_dev_get(disk);
 243        int ret = 0;
 244
 245        if (!dev)
 246                return ret;
 247
 248        mutex_lock(&dev->lock);
 249
 250        if (--dev->open)
 251                goto unlock;
 252
 253        kref_put(&dev->ref, blktrans_dev_release);
 254        module_put(dev->tr->owner);
 255
 256        if (dev->mtd) {
 257                ret = dev->tr->release ? dev->tr->release(dev) : 0;
 258                __put_mtd_device(dev->mtd);
 259        }
 260unlock:
 261        mutex_unlock(&dev->lock);
 262        blktrans_dev_put(dev);
 263        return ret;
 264}
 265
 266static int blktrans_getgeo(struct block_device *bdev, struct hd_geometry *geo)
 267{
 268        struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
 269        int ret = -ENXIO;
 270
 271        if (!dev)
 272                return ret;
 273
 274        mutex_lock(&dev->lock);
 275
 276        if (!dev->mtd)
 277                goto unlock;
 278
 279        ret = dev->tr->getgeo ? dev->tr->getgeo(dev, geo) : 0;
 280unlock:
 281        mutex_unlock(&dev->lock);
 282        blktrans_dev_put(dev);
 283        return ret;
 284}
 285
 286static int blktrans_ioctl(struct block_device *bdev, fmode_t mode,
 287                              unsigned int cmd, unsigned long arg)
 288{
 289        struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
 290        int ret = -ENXIO;
 291
 292        if (!dev)
 293                return ret;
 294
 295        mutex_lock(&dev->lock);
 296
 297        if (!dev->mtd)
 298                goto unlock;
 299
 300        switch (cmd) {
 301        case BLKFLSBUF:
 302                ret = dev->tr->flush ? dev->tr->flush(dev) : 0;
 303                break;
 304        default:
 305                ret = -ENOTTY;
 306        }
 307unlock:
 308        mutex_unlock(&dev->lock);
 309        blktrans_dev_put(dev);
 310        return ret;
 311}
 312
 313static const struct block_device_operations mtd_block_ops = {
 314        .owner          = THIS_MODULE,
 315        .open           = blktrans_open,
 316        .release        = blktrans_release,
 317        .ioctl          = blktrans_ioctl,
 318        .getgeo         = blktrans_getgeo,
 319};
 320
 321int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
 322{
 323        struct mtd_blktrans_ops *tr = new->tr;
 324        struct mtd_blktrans_dev *d;
 325        int last_devnum = -1;
 326        struct gendisk *gd;
 327        int ret;
 328
 329        if (mutex_trylock(&mtd_table_mutex)) {
 330                mutex_unlock(&mtd_table_mutex);
 331                BUG();
 332        }
 333
 334        mutex_lock(&blktrans_ref_mutex);
 335        list_for_each_entry(d, &tr->devs, list) {
 336                if (new->devnum == -1) {
 337                        /* Use first free number */
 338                        if (d->devnum != last_devnum+1) {
 339                                /* Found a free devnum. Plug it in here */
 340                                new->devnum = last_devnum+1;
 341                                list_add_tail(&new->list, &d->list);
 342                                goto added;
 343                        }
 344                } else if (d->devnum == new->devnum) {
 345                        /* Required number taken */
 346                        mutex_unlock(&blktrans_ref_mutex);
 347                        return -EBUSY;
 348                } else if (d->devnum > new->devnum) {
 349                        /* Required number was free */
 350                        list_add_tail(&new->list, &d->list);
 351                        goto added;
 352                }
 353                last_devnum = d->devnum;
 354        }
 355
 356        ret = -EBUSY;
 357        if (new->devnum == -1)
 358                new->devnum = last_devnum+1;
 359
 360        /* Check that the device and any partitions will get valid
 361         * minor numbers and that the disk naming code below can cope
 362         * with this number. */
 363        if (new->devnum > (MINORMASK >> tr->part_bits) ||
 364            (tr->part_bits && new->devnum >= 27 * 26)) {
 365                mutex_unlock(&blktrans_ref_mutex);
 366                goto error1;
 367        }
 368
 369        list_add_tail(&new->list, &tr->devs);
 370 added:
 371        mutex_unlock(&blktrans_ref_mutex);
 372
 373        mutex_init(&new->lock);
 374        kref_init(&new->ref);
 375        if (!tr->writesect)
 376                new->readonly = 1;
 377
 378        /* Create gendisk */
 379        ret = -ENOMEM;
 380        gd = alloc_disk(1 << tr->part_bits);
 381
 382        if (!gd)
 383                goto error2;
 384
 385        new->disk = gd;
 386        gd->private_data = new;
 387        gd->major = tr->major;
 388        gd->first_minor = (new->devnum) << tr->part_bits;
 389        gd->fops = &mtd_block_ops;
 390
 391        if (tr->part_bits)
 392                if (new->devnum < 26)
 393                        snprintf(gd->disk_name, sizeof(gd->disk_name),
 394                                 "%s%c", tr->name, 'a' + new->devnum);
 395                else
 396                        snprintf(gd->disk_name, sizeof(gd->disk_name),
 397                                 "%s%c%c", tr->name,
 398                                 'a' - 1 + new->devnum / 26,
 399                                 'a' + new->devnum % 26);
 400        else
 401                snprintf(gd->disk_name, sizeof(gd->disk_name),
 402                         "%s%d", tr->name, new->devnum);
 403
 404        set_capacity(gd, (new->size * tr->blksize) >> 9);
 405
 406        /* Create the request queue */
 407        spin_lock_init(&new->queue_lock);
 408        new->rq = blk_init_queue(mtd_blktrans_request, &new->queue_lock);
 409
 410        if (!new->rq)
 411                goto error3;
 412
 413        new->rq->queuedata = new;
 414        blk_queue_logical_block_size(new->rq, tr->blksize);
 415
 416        queue_flag_set_unlocked(QUEUE_FLAG_NONROT, new->rq);
 417
 418        if (tr->discard) {
 419                queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, new->rq);
 420                new->rq->limits.max_discard_sectors = UINT_MAX;
 421        }
 422
 423        gd->queue = new->rq;
 424
 425        /* Create processing workqueue */
 426        new->wq = alloc_workqueue("%s%d", 0, 0,
 427                                  tr->name, new->mtd->index);
 428        if (!new->wq)
 429                goto error4;
 430        INIT_WORK(&new->work, mtd_blktrans_work);
 431
 432        gd->driverfs_dev = &new->mtd->dev;
 433
 434        if (new->readonly)
 435                set_disk_ro(gd, 1);
 436
 437        add_disk(gd);
 438
 439        if (new->disk_attributes) {
 440                ret = sysfs_create_group(&disk_to_dev(gd)->kobj,
 441                                        new->disk_attributes);
 442                WARN_ON(ret);
 443        }
 444        return 0;
 445error4:
 446        blk_cleanup_queue(new->rq);
 447error3:
 448        put_disk(new->disk);
 449error2:
 450        list_del(&new->list);
 451error1:
 452        return ret;
 453}
 454
 455int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old)
 456{
 457        unsigned long flags;
 458
 459        if (mutex_trylock(&mtd_table_mutex)) {
 460                mutex_unlock(&mtd_table_mutex);
 461                BUG();
 462        }
 463
 464        if (old->disk_attributes)
 465                sysfs_remove_group(&disk_to_dev(old->disk)->kobj,
 466                                                old->disk_attributes);
 467
 468        /* Stop new requests to arrive */
 469        del_gendisk(old->disk);
 470
 471        /* Stop workqueue. This will perform any pending request. */
 472        destroy_workqueue(old->wq);
 473
 474        /* Kill current requests */
 475        spin_lock_irqsave(&old->queue_lock, flags);
 476        old->rq->queuedata = NULL;
 477        blk_start_queue(old->rq);
 478        spin_unlock_irqrestore(&old->queue_lock, flags);
 479
 480        /* If the device is currently open, tell trans driver to close it,
 481                then put mtd device, and don't touch it again */
 482        mutex_lock(&old->lock);
 483        if (old->open) {
 484                if (old->tr->release)
 485                        old->tr->release(old);
 486                __put_mtd_device(old->mtd);
 487        }
 488
 489        old->mtd = NULL;
 490
 491        mutex_unlock(&old->lock);
 492        blktrans_dev_put(old);
 493        return 0;
 494}
 495
 496static void blktrans_notify_remove(struct mtd_info *mtd)
 497{
 498        struct mtd_blktrans_ops *tr;
 499        struct mtd_blktrans_dev *dev, *next;
 500
 501        list_for_each_entry(tr, &blktrans_majors, list)
 502                list_for_each_entry_safe(dev, next, &tr->devs, list)
 503                        if (dev->mtd == mtd)
 504                                tr->remove_dev(dev);
 505}
 506
 507static void blktrans_notify_add(struct mtd_info *mtd)
 508{
 509        struct mtd_blktrans_ops *tr;
 510
 511        if (mtd->type == MTD_ABSENT)
 512                return;
 513
 514        list_for_each_entry(tr, &blktrans_majors, list)
 515                tr->add_mtd(tr, mtd);
 516}
 517
 518static struct mtd_notifier blktrans_notifier = {
 519        .add = blktrans_notify_add,
 520        .remove = blktrans_notify_remove,
 521};
 522
 523int register_mtd_blktrans(struct mtd_blktrans_ops *tr)
 524{
 525        struct mtd_info *mtd;
 526        int ret;
 527
 528        /* Register the notifier if/when the first device type is
 529           registered, to prevent the link/init ordering from fucking
 530           us over. */
 531        if (!blktrans_notifier.list.next)
 532                register_mtd_user(&blktrans_notifier);
 533
 534
 535        mutex_lock(&mtd_table_mutex);
 536
 537        ret = register_blkdev(tr->major, tr->name);
 538        if (ret < 0) {
 539                printk(KERN_WARNING "Unable to register %s block device on major %d: %d\n",
 540                       tr->name, tr->major, ret);
 541                mutex_unlock(&mtd_table_mutex);
 542                return ret;
 543        }
 544
 545        if (ret)
 546                tr->major = ret;
 547
 548        tr->blkshift = ffs(tr->blksize) - 1;
 549
 550        INIT_LIST_HEAD(&tr->devs);
 551        list_add(&tr->list, &blktrans_majors);
 552
 553        mtd_for_each_device(mtd)
 554                if (mtd->type != MTD_ABSENT)
 555                        tr->add_mtd(tr, mtd);
 556
 557        mutex_unlock(&mtd_table_mutex);
 558        return 0;
 559}
 560
 561int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr)
 562{
 563        struct mtd_blktrans_dev *dev, *next;
 564
 565        mutex_lock(&mtd_table_mutex);
 566
 567        /* Remove it from the list of active majors */
 568        list_del(&tr->list);
 569
 570        list_for_each_entry_safe(dev, next, &tr->devs, list)
 571                tr->remove_dev(dev);
 572
 573        unregister_blkdev(tr->major, tr->name);
 574        mutex_unlock(&mtd_table_mutex);
 575
 576        BUG_ON(!list_empty(&tr->devs));
 577        return 0;
 578}
 579
 580static void __exit mtd_blktrans_exit(void)
 581{
 582        /* No race here -- if someone's currently in register_mtd_blktrans
 583           we're screwed anyway. */
 584        if (blktrans_notifier.list.next)
 585                unregister_mtd_user(&blktrans_notifier);
 586}
 587
 588module_exit(mtd_blktrans_exit);
 589
 590EXPORT_SYMBOL_GPL(register_mtd_blktrans);
 591EXPORT_SYMBOL_GPL(deregister_mtd_blktrans);
 592EXPORT_SYMBOL_GPL(add_mtd_blktrans_dev);
 593EXPORT_SYMBOL_GPL(del_mtd_blktrans_dev);
 594
 595MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
 596MODULE_LICENSE("GPL");
 597MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'");
 598
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