target/linux/generic/patches-3.14/040-UBI-R-O-block-driver-on-top-of-UBI-volumes.patch

   1 From 9d54c8a33eec78289b1b3f6e10874719c27ce0a7 Mon Sep 17 00:00:00 2001
   2 From: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
   3 Date: Tue, 25 Feb 2014 13:25:22 -0300
   4 Subject: [PATCH] UBI: R/O block driver on top of UBI volumes
   5
   6 This commit introduces read-only block device emulation on top of UBI volumes.
   7
   8 Given UBI takes care of wear leveling and bad block management it's possible
   9 to add a thin layer to enable block device access to UBI volumes.
  10 This allows to use a block-oriented filesystem on a flash device.
  11
  12 The UBI block devices are meant to be used in conjunction with any
  13 regular, block-oriented file system (e.g. ext4), although it's primarily
  14 targeted at read-only file systems, such as squashfs.
  15
  16 Block devices are created upon user request through new ioctls:
  17 UBI_IOCVOLATTBLK to attach and UBI_IOCVOLDETBLK to detach.
  18 Also, a new UBI module parameter is added 'ubi.block'. This parameter is
  19 needed in order to attach a block device on boot-up time, allowing to
  20 mount the rootfs on a ubiblock device.
  21 For instance, you could have these kernel parameters:
  22
  23   ubi.mtd=5 ubi.block=0,0 root=/dev/ubiblock0_0
  24
  25 Or, if you compile ubi as a module:
  26
  27   $ modprobe ubi mtd=/dev/mtd5 block=/dev/ubi0_0
  28
  29 Artem: amend commentaries and massage the patch a little bit.
  30
  31 Signed-off-by: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
  32 Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
  33 ---
  34  drivers/mtd/ubi/Kconfig     |  15 +
  35  drivers/mtd/ubi/Makefile    |   1 +
  36  drivers/mtd/ubi/block.c     | 646 ++++++++++++++++++++++++++++++++++++++++++++
  37  drivers/mtd/ubi/build.c     |  11 +
  38  drivers/mtd/ubi/cdev.c      |  20 ++
  39  drivers/mtd/ubi/ubi.h       |  14 +
  40  include/uapi/mtd/ubi-user.h |  11 +
  41  7 files changed, 718 insertions(+)
  42  create mode 100644 drivers/mtd/ubi/block.c
  43
  44 --- a/drivers/mtd/ubi/Kconfig
  45 +++ b/drivers/mtd/ubi/Kconfig
  46 @@ -87,4 +87,19 @@ config MTD_UBI_GLUEBI
  47            work on top of UBI. Do not enable this unless you use legacy
  48            software.
  49
  50 +config MTD_UBI_BLOCK
  51 +       bool "Read-only block devices on top of UBI volumes"
  52 +       default n
  53 +       help
  54 +          This option enables read-only UBI block devices support. UBI block
  55 +          devices will be layered on top of UBI volumes, which means that the
  56 +          UBI driver will transparently handle things like bad eraseblocks and
  57 +          bit-flips. You can put any block-oriented file system on top of UBI
  58 +          volumes in read-only mode (e.g., ext4), but it is probably most
  59 +          practical for read-only file systems, like squashfs.
  60 +
  61 +          When selected, this feature will be built in the UBI driver.
  62 +
  63 +          If in doubt, say "N".
  64 +
  65  endif # MTD_UBI
  66 --- a/drivers/mtd/ubi/Makefile
  67 +++ b/drivers/mtd/ubi/Makefile
  68 @@ -3,5 +3,6 @@ obj-$(CONFIG_MTD_UBI) += ubi.o
  69  ubi-y += vtbl.o vmt.o upd.o build.o cdev.o kapi.o eba.o io.o wl.o attach.o
  70  ubi-y += misc.o debug.o
  71  ubi-$(CONFIG_MTD_UBI_FASTMAP) += fastmap.o
  72 +ubi-$(CONFIG_MTD_UBI_BLOCK) += block.o
  73
  74  obj-$(CONFIG_MTD_UBI_GLUEBI) += gluebi.o
  75 --- /dev/null
  76 +++ b/drivers/mtd/ubi/block.c
  77 @@ -0,0 +1,646 @@
  78 +/*
  79 + * Copyright (c) 2014 Ezequiel Garcia
  80 + * Copyright (c) 2011 Free Electrons
  81 + *
  82 + * Driver parameter handling strongly based on drivers/mtd/ubi/build.c
  83 + *   Copyright (c) International Business Machines Corp., 2006
  84 + *   Copyright (c) Nokia Corporation, 2007
  85 + *   Authors: Artem Bityutskiy, Frank Haverkamp
  86 + *
  87 + * This program is free software; you can redistribute it and/or modify
  88 + * it under the terms of the GNU General Public License as published by
  89 + * the Free Software Foundation, version 2.
  90 + *
  91 + * This program is distributed in the hope that it will be useful,
  92 + * but WITHOUT ANY WARRANTY; without even the implied warranty of
  93 + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
  94 + * the GNU General Public License for more details.
  95 + */
  96 +
  97 +/*
  98 + * Read-only block devices on top of UBI volumes
  99 + *
 100 + * A simple implementation to allow a block device to be layered on top of a
 101 + * UBI volume. The implementation is provided by creating a static 1-to-1
 102 + * mapping between the block device and the UBI volume.
 103 + *
 104 + * The addressed byte is obtained from the addressed block sector, which is
 105 + * mapped linearly into the corresponding LEB:
 106 + *
 107 + *   LEB number = addressed byte / LEB size
 108 + *
 109 + * This feature is compiled in the UBI core, and adds a new 'block' parameter
 110 + * to allow early block device attaching. Runtime  block attach/detach for UBI
 111 + * volumes is provided through two new UBI ioctls: UBI_IOCVOLATTBLK and
 112 + * UBI_IOCVOLDETBLK.
 113 + */
 114 +
 115 +#include <linux/module.h>
 116 +#include <linux/init.h>
 117 +#include <linux/err.h>
 118 +#include <linux/kernel.h>
 119 +#include <linux/list.h>
 120 +#include <linux/mutex.h>
 121 +#include <linux/slab.h>
 122 +#include <linux/vmalloc.h>
 123 +#include <linux/mtd/ubi.h>
 124 +#include <linux/workqueue.h>
 125 +#include <linux/blkdev.h>
 126 +#include <linux/hdreg.h>
 127 +#include <asm/div64.h>
 128 +
 129 +#include "ubi-media.h"
 130 +#include "ubi.h"
 131 +
 132 +/* Maximum number of supported devices */
 133 +#define UBIBLOCK_MAX_DEVICES 32
 134 +
 135 +/* Maximum length of the 'block=' parameter */
 136 +#define UBIBLOCK_PARAM_LEN 63
 137 +
 138 +/* Maximum number of comma-separated items in the 'block=' parameter */
 139 +#define UBIBLOCK_PARAM_COUNT 2
 140 +
 141 +struct ubiblock_param {
 142 +       int ubi_num;
 143 +       int vol_id;
 144 +       char name[UBIBLOCK_PARAM_LEN+1];
 145 +};
 146 +
 147 +/* Numbers of elements set in the @ubiblock_param array */
 148 +static int ubiblock_devs __initdata;
 149 +
 150 +/* MTD devices specification parameters */
 151 +static struct ubiblock_param ubiblock_param[UBIBLOCK_MAX_DEVICES] __initdata;
 152 +
 153 +struct ubiblock {
 154 +       struct ubi_volume_desc *desc;
 155 +       int ubi_num;
 156 +       int vol_id;
 157 +       int refcnt;
 158 +       int leb_size;
 159 +
 160 +       struct gendisk *gd;
 161 +       struct request_queue *rq;
 162 +
 163 +       struct workqueue_struct *wq;
 164 +       struct work_struct work;
 165 +
 166 +       struct mutex dev_mutex;
 167 +       spinlock_t queue_lock;
 168 +       struct list_head list;
 169 +};
 170 +
 171 +/* Linked list of all ubiblock instances */
 172 +static LIST_HEAD(ubiblock_devices);
 173 +static DEFINE_MUTEX(devices_mutex);
 174 +static int ubiblock_major;
 175 +
 176 +static int __init ubiblock_set_param(const char *val,
 177 +                                    const struct kernel_param *kp)
 178 +{
 179 +       int i, ret;
 180 +       size_t len;
 181 +       struct ubiblock_param *param;
 182 +       char buf[UBIBLOCK_PARAM_LEN];
 183 +       char *pbuf = &buf[0];
 184 +       char *tokens[UBIBLOCK_PARAM_COUNT];
 185 +
 186 +       if (!val)
 187 +               return -EINVAL;
 188 +
 189 +       len = strnlen(val, UBIBLOCK_PARAM_LEN);
 190 +       if (len == 0) {
 191 +               ubi_warn("block: empty 'block=' parameter - ignored\n");
 192 +               return 0;
 193 +       }
 194 +
 195 +       if (len == UBIBLOCK_PARAM_LEN) {
 196 +               ubi_err("block: parameter \"%s\" is too long, max. is %d\n",
 197 +                       val, UBIBLOCK_PARAM_LEN);
 198 +               return -EINVAL;
 199 +       }
 200 +
 201 +       strcpy(buf, val);
 202 +
 203 +       /* Get rid of the final newline */
 204 +       if (buf[len - 1] == '\n')
 205 +               buf[len - 1] = '\0';
 206 +
 207 +       for (i = 0; i < UBIBLOCK_PARAM_COUNT; i++)
 208 +               tokens[i] = strsep(&pbuf, ",");
 209 +
 210 +       param = &ubiblock_param[ubiblock_devs];
 211 +       if (tokens[1]) {
 212 +               /* Two parameters: can be 'ubi, vol_id' or 'ubi, vol_name' */
 213 +               ret = kstrtoint(tokens[0], 10, &param->ubi_num);
 214 +               if (ret < 0)
 215 +                       return -EINVAL;
 216 +
 217 +               /* Second param can be a number or a name */
 218 +               ret = kstrtoint(tokens[1], 10, &param->vol_id);
 219 +               if (ret < 0) {
 220 +                       param->vol_id = -1;
 221 +                       strcpy(param->name, tokens[1]);
 222 +               }
 223 +
 224 +       } else {
 225 +               /* One parameter: must be device path */
 226 +               strcpy(param->name, tokens[0]);
 227 +               param->ubi_num = -1;
 228 +               param->vol_id = -1;
 229 +       }
 230 +
 231 +       ubiblock_devs++;
 232 +
 233 +       return 0;
 234 +}
 235 +
 236 +static const struct kernel_param_ops ubiblock_param_ops = {
 237 +       .set    = ubiblock_set_param,
 238 +};
 239 +module_param_cb(block, &ubiblock_param_ops, NULL, 0);
 240 +MODULE_PARM_DESC(block, "Attach block devices to UBI volumes. Parameter format: block=<path|dev,num|dev,name>.\n"
 241 +                       "Multiple \"block\" parameters may be specified.\n"
 242 +                       "UBI volumes may be specified by their number, name, or path to the device node.\n"
 243 +                       "Examples\n"
 244 +                       "Using the UBI volume path:\n"
 245 +                       "ubi.block=/dev/ubi0_0\n"
 246 +                       "Using the UBI device, and the volume name:\n"
 247 +                       "ubi.block=0,rootfs\n"
 248 +                       "Using both UBI device number and UBI volume number:\n"
 249 +                       "ubi.block=0,0\n");
 250 +
 251 +static struct ubiblock *find_dev_nolock(int ubi_num, int vol_id)
 252 +{
 253 +       struct ubiblock *dev;
 254 +
 255 +       list_for_each_entry(dev, &ubiblock_devices, list)
 256 +               if (dev->ubi_num == ubi_num && dev->vol_id == vol_id)
 257 +                       return dev;
 258 +       return NULL;
 259 +}
 260 +
 261 +static int ubiblock_read_to_buf(struct ubiblock *dev, char *buffer,
 262 +                               int leb, int offset, int len)
 263 +{
 264 +       int ret;
 265 +
 266 +       ret = ubi_read(dev->desc, leb, buffer, offset, len);
 267 +       if (ret) {
 268 +               ubi_err("%s ubi_read error %d",
 269 +                       dev->gd->disk_name, ret);
 270 +               return ret;
 271 +       }
 272 +       return 0;
 273 +}
 274 +
 275 +static int ubiblock_read(struct ubiblock *dev, char *buffer,
 276 +                        sector_t sec, int len)
 277 +{
 278 +       int ret, leb, offset;
 279 +       int bytes_left = len;
 280 +       int to_read = len;
 281 +       loff_t pos = sec << 9;
 282 +
 283 +       /* Get LEB:offset address to read from */
 284 +       offset = do_div(pos, dev->leb_size);
 285 +       leb = pos;
 286 +
 287 +       while (bytes_left) {
 288 +               /*
 289 +                * We can only read one LEB at a time. Therefore if the read
 290 +                * length is larger than one LEB size, we split the operation.
 291 +                */
 292 +               if (offset + to_read > dev->leb_size)
 293 +                       to_read = dev->leb_size - offset;
 294 +
 295 +               ret = ubiblock_read_to_buf(dev, buffer, leb, offset, to_read);
 296 +               if (ret)
 297 +                       return ret;
 298 +
 299 +               buffer += to_read;
 300 +               bytes_left -= to_read;
 301 +               to_read = bytes_left;
 302 +               leb += 1;
 303 +               offset = 0;
 304 +       }
 305 +       return 0;
 306 +}
 307 +
 308 +static int do_ubiblock_request(struct ubiblock *dev, struct request *req)
 309 +{
 310 +       int len, ret;
 311 +       sector_t sec;
 312 +
 313 +       if (req->cmd_type != REQ_TYPE_FS)
 314 +               return -EIO;
 315 +
 316 +       if (blk_rq_pos(req) + blk_rq_cur_sectors(req) >
 317 +           get_capacity(req->rq_disk))
 318 +               return -EIO;
 319 +
 320 +       if (rq_data_dir(req) != READ)
 321 +               return -ENOSYS; /* Write not implemented */
 322 +
 323 +       sec = blk_rq_pos(req);
 324 +       len = blk_rq_cur_bytes(req);
 325 +
 326 +       /*
 327 +        * Let's prevent the device from being removed while we're doing I/O
 328 +        * work. Notice that this means we serialize all the I/O operations,
 329 +        * but it's probably of no impact given the NAND core serializes
 330 +        * flash access anyway.
 331 +        */
 332 +       mutex_lock(&dev->dev_mutex);
 333 +       ret = ubiblock_read(dev, req->buffer, sec, len);
 334 +       mutex_unlock(&dev->dev_mutex);
 335 +
 336 +       return ret;
 337 +}
 338 +
 339 +static void ubiblock_do_work(struct work_struct *work)
 340 +{
 341 +       struct ubiblock *dev =
 342 +               container_of(work, struct ubiblock, work);
 343 +       struct request_queue *rq = dev->rq;
 344 +       struct request *req;
 345 +       int res;
 346 +
 347 +       spin_lock_irq(rq->queue_lock);
 348 +
 349 +       req = blk_fetch_request(rq);
 350 +       while (req) {
 351 +
 352 +               spin_unlock_irq(rq->queue_lock);
 353 +               res = do_ubiblock_request(dev, req);
 354 +               spin_lock_irq(rq->queue_lock);
 355 +
 356 +               /*
 357 +                * If we're done with this request,
 358 +                * we need to fetch a new one
 359 +                */
 360 +               if (!__blk_end_request_cur(req, res))
 361 +                       req = blk_fetch_request(rq);
 362 +       }
 363 +
 364 +       spin_unlock_irq(rq->queue_lock);
 365 +}
 366 +
 367 +static void ubiblock_request(struct request_queue *rq)
 368 +{
 369 +       struct ubiblock *dev;
 370 +       struct request *req;
 371 +
 372 +       dev = rq->queuedata;
 373 +
 374 +       if (!dev)
 375 +               while ((req = blk_fetch_request(rq)) != NULL)
 376 +                       __blk_end_request_all(req, -ENODEV);
 377 +       else
 378 +               queue_work(dev->wq, &dev->work);
 379 +}
 380 +
 381 +static int ubiblock_open(struct block_device *bdev, fmode_t mode)
 382 +{
 383 +       struct ubiblock *dev = bdev->bd_disk->private_data;
 384 +       int ret;
 385 +
 386 +       mutex_lock(&dev->dev_mutex);
 387 +       if (dev->refcnt > 0) {
 388 +               /*
 389 +                * The volume is already open, just increase the reference
 390 +                * counter.
 391 +                */
 392 +               goto out_done;
 393 +       }
 394 +
 395 +       /*
 396 +        * We want users to be aware they should only mount us as read-only.
 397 +        * It's just a paranoid check, as write requests will get rejected
 398 +        * in any case.
 399 +        */
 400 +       if (mode & FMODE_WRITE) {
 401 +               ret = -EPERM;
 402 +               goto out_unlock;
 403 +       }
 404 +
 405 +       dev->desc = ubi_open_volume(dev->ubi_num, dev->vol_id, UBI_READONLY);
 406 +       if (IS_ERR(dev->desc)) {
 407 +               ubi_err("%s failed to open ubi volume %d_%d",
 408 +                       dev->gd->disk_name, dev->ubi_num, dev->vol_id);
 409 +               ret = PTR_ERR(dev->desc);
 410 +               dev->desc = NULL;
 411 +               goto out_unlock;
 412 +       }
 413 +
 414 +out_done:
 415 +       dev->refcnt++;
 416 +       mutex_unlock(&dev->dev_mutex);
 417 +       return 0;
 418 +
 419 +out_unlock:
 420 +       mutex_unlock(&dev->dev_mutex);
 421 +       return ret;
 422 +}
 423 +
 424 +static void ubiblock_release(struct gendisk *gd, fmode_t mode)
 425 +{
 426 +       struct ubiblock *dev = gd->private_data;
 427 +
 428 +       mutex_lock(&dev->dev_mutex);
 429 +       dev->refcnt--;
 430 +       if (dev->refcnt == 0) {
 431 +               ubi_close_volume(dev->desc);
 432 +               dev->desc = NULL;
 433 +       }
 434 +       mutex_unlock(&dev->dev_mutex);
 435 +}
 436 +
 437 +static int ubiblock_getgeo(struct block_device *bdev, struct hd_geometry *geo)
 438 +{
 439 +       /* Some tools might require this information */
 440 +       geo->heads = 1;
 441 +       geo->cylinders = 1;
 442 +       geo->sectors = get_capacity(bdev->bd_disk);
 443 +       geo->start = 0;
 444 +       return 0;
 445 +}
 446 +
 447 +static const struct block_device_operations ubiblock_ops = {
 448 +       .owner = THIS_MODULE,
 449 +       .open = ubiblock_open,
 450 +       .release = ubiblock_release,
 451 +       .getgeo = ubiblock_getgeo,
 452 +};
 453 +
 454 +int ubiblock_add(struct ubi_volume_info *vi)
 455 +{
 456 +       struct ubiblock *dev;
 457 +       struct gendisk *gd;
 458 +       int disk_capacity;
 459 +       int ret;
 460 +
 461 +       /* Check that the volume isn't already handled */
 462 +       mutex_lock(&devices_mutex);
 463 +       if (find_dev_nolock(vi->ubi_num, vi->vol_id)) {
 464 +               mutex_unlock(&devices_mutex);
 465 +               return -EEXIST;
 466 +       }
 467 +       mutex_unlock(&devices_mutex);
 468 +
 469 +       dev = kzalloc(sizeof(struct ubiblock), GFP_KERNEL);
 470 +       if (!dev)
 471 +               return -ENOMEM;
 472 +
 473 +       mutex_init(&dev->dev_mutex);
 474 +
 475 +       dev->ubi_num = vi->ubi_num;
 476 +       dev->vol_id = vi->vol_id;
 477 +       dev->leb_size = vi->usable_leb_size;
 478 +
 479 +       /* Initialize the gendisk of this ubiblock device */
 480 +       gd = alloc_disk(1);
 481 +       if (!gd) {
 482 +               ubi_err("block: alloc_disk failed");
 483 +               ret = -ENODEV;
 484 +               goto out_free_dev;
 485 +       }
 486 +
 487 +       gd->fops = &ubiblock_ops;
 488 +       gd->major = ubiblock_major;
 489 +       gd->first_minor = dev->ubi_num * UBI_MAX_VOLUMES + dev->vol_id;
 490 +       gd->private_data = dev;
 491 +       sprintf(gd->disk_name, "ubiblock%d_%d", dev->ubi_num, dev->vol_id);
 492 +       disk_capacity = (vi->size * vi->usable_leb_size) >> 9;
 493 +       set_capacity(gd, disk_capacity);
 494 +       dev->gd = gd;
 495 +
 496 +       spin_lock_init(&dev->queue_lock);
 497 +       dev->rq = blk_init_queue(ubiblock_request, &dev->queue_lock);
 498 +       if (!dev->rq) {
 499 +               ubi_err("block: blk_init_queue failed");
 500 +               ret = -ENODEV;
 501 +               goto out_put_disk;
 502 +       }
 503 +
 504 +       dev->rq->queuedata = dev;
 505 +       dev->gd->queue = dev->rq;
 506 +
 507 +       /*
 508 +        * Create one workqueue per volume (per registered block device).
 509 +        * Rembember workqueues are cheap, they're not threads.
 510 +        */
 511 +       dev->wq = alloc_workqueue(gd->disk_name, 0, 0);
 512 +       if (!dev->wq)
 513 +               goto out_free_queue;
 514 +       INIT_WORK(&dev->work, ubiblock_do_work);
 515 +
 516 +       mutex_lock(&devices_mutex);
 517 +       list_add_tail(&dev->list, &ubiblock_devices);
 518 +       mutex_unlock(&devices_mutex);
 519 +
 520 +       /* Must be the last step: anyone can call file ops from now on */
 521 +       add_disk(dev->gd);
 522 +       ubi_msg("%s created from ubi%d:%d(%s)",
 523 +               dev->gd->disk_name, dev->ubi_num, dev->vol_id, vi->name);
 524 +       return 0;
 525 +
 526 +out_free_queue:
 527 +       blk_cleanup_queue(dev->rq);
 528 +out_put_disk:
 529 +       put_disk(dev->gd);
 530 +out_free_dev:
 531 +       kfree(dev);
 532 +
 533 +       return ret;
 534 +}
 535 +
 536 +static void ubiblock_cleanup(struct ubiblock *dev)
 537 +{
 538 +       del_gendisk(dev->gd);
 539 +       blk_cleanup_queue(dev->rq);
 540 +       ubi_msg("%s released", dev->gd->disk_name);
 541 +       put_disk(dev->gd);
 542 +}
 543 +
 544 +int ubiblock_del(struct ubi_volume_info *vi)
 545 +{
 546 +       struct ubiblock *dev;
 547 +
 548 +       mutex_lock(&devices_mutex);
 549 +       dev = find_dev_nolock(vi->ubi_num, vi->vol_id);
 550 +       if (!dev) {
 551 +               mutex_unlock(&devices_mutex);
 552 +               return -ENODEV;
 553 +       }
 554 +
 555 +       /* Found a device, let's lock it so we can check if it's busy */
 556 +       mutex_lock(&dev->dev_mutex);
 557 +       if (dev->refcnt > 0) {
 558 +               mutex_unlock(&dev->dev_mutex);
 559 +               mutex_unlock(&devices_mutex);
 560 +               return -EBUSY;
 561 +       }
 562 +
 563 +       /* Remove from device list */
 564 +       list_del(&dev->list);
 565 +       mutex_unlock(&devices_mutex);
 566 +
 567 +       /* Flush pending work and stop this workqueue */
 568 +       destroy_workqueue(dev->wq);
 569 +
 570 +       ubiblock_cleanup(dev);
 571 +       mutex_unlock(&dev->dev_mutex);
 572 +       kfree(dev);
 573 +       return 0;
 574 +}
 575 +
 576 +static void ubiblock_resize(struct ubi_volume_info *vi)
 577 +{
 578 +       struct ubiblock *dev;
 579 +       int disk_capacity;
 580 +
 581 +       /*
 582 +        * Need to lock the device list until we stop using the device,
 583 +        * otherwise the device struct might get released in 'ubiblock_del()'.
 584 +        */
 585 +       mutex_lock(&devices_mutex);
 586 +       dev = find_dev_nolock(vi->ubi_num, vi->vol_id);
 587 +       if (!dev) {
 588 +               mutex_unlock(&devices_mutex);
 589 +               return;
 590 +       }
 591 +
 592 +       mutex_lock(&dev->dev_mutex);
 593 +       disk_capacity = (vi->size * vi->usable_leb_size) >> 9;
 594 +       set_capacity(dev->gd, disk_capacity);
 595 +       ubi_msg("%s resized to %d LEBs", dev->gd->disk_name, vi->size);
 596 +       mutex_unlock(&dev->dev_mutex);
 597 +       mutex_unlock(&devices_mutex);
 598 +}
 599 +
 600 +static int ubiblock_notify(struct notifier_block *nb,
 601 +                        unsigned long notification_type, void *ns_ptr)
 602 +{
 603 +       struct ubi_notification *nt = ns_ptr;
 604 +
 605 +       switch (notification_type) {
 606 +       case UBI_VOLUME_ADDED:
 607 +               /*
 608 +                * We want to enforce explicit block device attaching for
 609 +                * volumes, so when a volume is added we do nothing.
 610 +                */
 611 +               break;
 612 +       case UBI_VOLUME_REMOVED:
 613 +               ubiblock_del(&nt->vi);
 614 +               break;
 615 +       case UBI_VOLUME_RESIZED:
 616 +               ubiblock_resize(&nt->vi);
 617 +               break;
 618 +       default:
 619 +               break;
 620 +       }
 621 +       return NOTIFY_OK;
 622 +}
 623 +
 624 +static struct notifier_block ubiblock_notifier = {
 625 +       .notifier_call = ubiblock_notify,
 626 +};
 627 +
 628 +static struct ubi_volume_desc * __init
 629 +open_volume_desc(const char *name, int ubi_num, int vol_id)
 630 +{
 631 +       if (ubi_num == -1)
 632 +               /* No ubi num, name must be a vol device path */
 633 +               return ubi_open_volume_path(name, UBI_READONLY);
 634 +       else if (vol_id == -1)
 635 +               /* No vol_id, must be vol_name */
 636 +               return ubi_open_volume_nm(ubi_num, name, UBI_READONLY);
 637 +       else
 638 +               return ubi_open_volume(ubi_num, vol_id, UBI_READONLY);
 639 +}
 640 +
 641 +static int __init ubiblock_attach_from_param(void)
 642 +{
 643 +       int i, ret;
 644 +       struct ubiblock_param *p;
 645 +       struct ubi_volume_desc *desc;
 646 +       struct ubi_volume_info vi;
 647 +
 648 +       for (i = 0; i < ubiblock_devs; i++) {
 649 +               p = &ubiblock_param[i];
 650 +
 651 +               desc = open_volume_desc(p->name, p->ubi_num, p->vol_id);
 652 +               if (IS_ERR(desc)) {
 653 +                       ubi_err("block: can't open volume, err=%ld\n",
 654 +                               PTR_ERR(desc));
 655 +                       ret = PTR_ERR(desc);
 656 +                       break;
 657 +               }
 658 +
 659 +               ubi_get_volume_info(desc, &vi);
 660 +               ubi_close_volume(desc);
 661 +
 662 +               ret = ubiblock_add(&vi);
 663 +               if (ret) {
 664 +                       ubi_err("block: can't add '%s' volume, err=%d\n",
 665 +                               vi.name, ret);
 666 +                       break;
 667 +               }
 668 +       }
 669 +       return ret;
 670 +}
 671 +
 672 +static void ubiblock_detach_all(void)
 673 +{
 674 +       struct ubiblock *next;
 675 +       struct ubiblock *dev;
 676 +
 677 +       list_for_each_entry_safe(dev, next, &ubiblock_devices, list) {
 678 +               /* Flush pending work and stop workqueue */
 679 +               destroy_workqueue(dev->wq);
 680 +               /* The module is being forcefully removed */
 681 +               WARN_ON(dev->desc);
 682 +               /* Remove from device list */
 683 +               list_del(&dev->list);
 684 +               ubiblock_cleanup(dev);
 685 +               kfree(dev);
 686 +       }
 687 +}
 688 +
 689 +int __init ubiblock_init(void)
 690 +{
 691 +       int ret;
 692 +
 693 +       ubiblock_major = register_blkdev(0, "ubiblock");
 694 +       if (ubiblock_major < 0)
 695 +               return ubiblock_major;
 696 +
 697 +       /* Attach block devices from 'block=' module param */
 698 +       ret = ubiblock_attach_from_param();
 699 +       if (ret)
 700 +               goto err_detach;
 701 +
 702 +       /*
 703 +        * Block devices needs to be attached to volumes explicitly
 704 +        * upon user request. So we ignore existing volumes.
 705 +        */
 706 +       ret = ubi_register_volume_notifier(&ubiblock_notifier, 1);
 707 +       if (ret)
 708 +               goto err_unreg;
 709 +       return 0;
 710 +
 711 +err_unreg:
 712 +       unregister_blkdev(ubiblock_major, "ubiblock");
 713 +err_detach:
 714 +       ubiblock_detach_all();
 715 +       return ret;
 716 +}
 717 +
 718 +void __exit ubiblock_exit(void)
 719 +{
 720 +       ubi_unregister_volume_notifier(&ubiblock_notifier);
 721 +       ubiblock_detach_all();
 722 +       unregister_blkdev(ubiblock_major, "ubiblock");
 723 +}
 724 --- a/drivers/mtd/ubi/build.c
 725 +++ b/drivers/mtd/ubi/build.c
 726 @@ -1298,6 +1298,15 @@ static int __init ubi_init(void)
 727                 }
 728         }
 729
 730 +       err = ubiblock_init();
 731 +       if (err) {
 732 +               ubi_err("block: cannot initialize, error %d", err);
 733 +
 734 +               /* See comment above re-ubi_is_module(). */
 735 +               if (ubi_is_module())
 736 +                       goto out_detach;
 737 +       }
 738 +
 739         return 0;
 740
 741  out_detach:
 742 @@ -1326,6 +1335,8 @@ static void __exit ubi_exit(void)
 743  {
 744         int i;
 745
 746 +       ubiblock_exit();
 747 +
 748         for (i = 0; i < UBI_MAX_DEVICES; i++)
 749                 if (ubi_devices[i]) {
 750                         mutex_lock(&ubi_devices_mutex);
 751 --- a/drivers/mtd/ubi/cdev.c
 752 +++ b/drivers/mtd/ubi/cdev.c
 753 @@ -561,6 +561,26 @@ static long vol_cdev_ioctl(struct file *
 754                 break;
 755         }
 756
 757 +       /* Attach a block device to an UBI volume */
 758 +       case UBI_IOCVOLATTBLK:
 759 +       {
 760 +               struct ubi_volume_info vi;
 761 +
 762 +               ubi_get_volume_info(desc, &vi);
 763 +               err = ubiblock_add(&vi);
 764 +               break;
 765 +       }
 766 +
 767 +       /* Dettach a block device from an UBI volume */
 768 +       case UBI_IOCVOLDETBLK:
 769 +       {
 770 +               struct ubi_volume_info vi;
 771 +
 772 +               ubi_get_volume_info(desc, &vi);
 773 +               err = ubiblock_del(&vi);
 774 +               break;
 775 +       }
 776 +
 777         default:
 778                 err = -ENOTTY;
 779                 break;
 780 --- a/drivers/mtd/ubi/ubi.h
 781 +++ b/drivers/mtd/ubi/ubi.h
 782 @@ -864,6 +864,20 @@ int ubi_update_fastmap(struct ubi_device
 783  int ubi_scan_fastmap(struct ubi_device *ubi, struct ubi_attach_info *ai,
 784                      int fm_anchor);
 785
 786 +/* block.c */
 787 +#ifdef CONFIG_MTD_UBI_BLOCK
 788 +int ubiblock_init(void);
 789 +void ubiblock_exit(void);
 790 +int ubiblock_add(struct ubi_volume_info *vi);
 791 +int ubiblock_del(struct ubi_volume_info *vi);
 792 +#else
 793 +static inline int ubiblock_init(void) { return 0; }
 794 +static inline void ubiblock_exit(void) {}
 795 +static inline int ubiblock_add(struct ubi_volume_info *vi) { return -ENOTTY; }
 796 +static inline int ubiblock_del(struct ubi_volume_info *vi) { return -ENOTTY; }
 797 +#endif
 798 +
 799 +
 800  /*
 801   * ubi_rb_for_each_entry - walk an RB-tree.
 802   * @rb: a pointer to type 'struct rb_node' to use as a loop counter
 803 --- a/include/uapi/mtd/ubi-user.h
 804 +++ b/include/uapi/mtd/ubi-user.h
 805 @@ -134,6 +134,13 @@
 806   * used. A pointer to a &struct ubi_set_vol_prop_req object is expected to be
 807   * passed. The object describes which property should be set, and to which value
 808   * it should be set.
 809 + *
 810 + * Block devices on UBI volumes
 811 + * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 812 + *
 813 + * To attach or detach a block device from an UBI volume the %UBI_IOCVOLATTBLK
 814 + * and %UBI_IOCVOLDETBLK ioctl commands should be used, respectively.
 815 + * These commands take no arguments.
 816   */
 817
 818  /*
 819 @@ -191,6 +198,10 @@
 820  /* Set an UBI volume property */
 821  #define UBI_IOCSETVOLPROP _IOW(UBI_VOL_IOC_MAGIC, 6, \
 822                                struct ubi_set_vol_prop_req)
 823 +/* Attach a block device to an UBI volume */
 824 +#define UBI_IOCVOLATTBLK _IO(UBI_VOL_IOC_MAGIC, 7)
 825 +/* Detach a block device from an UBI volume */
 826 +#define UBI_IOCVOLDETBLK _IO(UBI_VOL_IOC_MAGIC, 8)
 827
 828  /* Maximum MTD device name length supported by UBI */
 829  #define MAX_UBI_MTD_NAME_LEN 127