drivers/mtd/ubi/upd.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Copyright (c) International Business Machines Corp., 2006
   4  * Copyright (c) Nokia Corporation, 2006
   5  *
   6  * Author: Artem Bityutskiy (Битюцкий Артём)
   7  *
   8  * Jan 2007: Alexander Schmidt, hacked per-volume update.
   9  */
  10
  11 /*
  12  * This file contains implementation of the volume update and atomic LEB change
  13  * functionality.
  14  *
  15  * The update operation is based on the per-volume update marker which is
  16  * stored in the volume table. The update marker is set before the update
  17  * starts, and removed after the update has been finished. So if the update was
  18  * interrupted by an unclean re-boot or due to some other reasons, the update
  19  * marker stays on the flash media and UBI finds it when it attaches the MTD
  20  * device next time. If the update marker is set for a volume, the volume is
  21  * treated as damaged and most I/O operations are prohibited. Only a new update
  22  * operation is allowed.
  23  *
  24  * Note, in general it is possible to implement the update operation as a
  25  * transaction with a roll-back capability.
  26  */
  27
  28 #include <linux/err.h>
  29 #include <linux/uaccess.h>
  30 #include <linux/math64.h>
  31 #include "ubi.h"
  32
  33 /**
  34  * set_update_marker - set update marker.
  35  * @ubi: UBI device description object
  36  * @vol: volume description object
  37  *
  38  * This function sets the update marker flag for volume @vol. Returns zero
  39  * in case of success and a negative error code in case of failure.
  40  */
  41 static int set_update_marker(struct ubi_device *ubi, struct ubi_volume *vol)
  42 {
  43         int err;
  44         struct ubi_vtbl_record vtbl_rec;
  45
  46         dbg_gen("set update marker for volume %d", vol->vol_id);
  47
  48         if (vol->upd_marker) {
  49                 ubi_assert(ubi->vtbl[vol->vol_id].upd_marker);
  50                 dbg_gen("already set");
  51                 return 0;
  52         }
  53
  54         vtbl_rec = ubi->vtbl[vol->vol_id];
  55         vtbl_rec.upd_marker = 1;
  56
  57         mutex_lock(&ubi->device_mutex);
  58         err = ubi_change_vtbl_record(ubi, vol->vol_id, &vtbl_rec);
  59         vol->upd_marker = 1;
  60         mutex_unlock(&ubi->device_mutex);
  61         return err;
  62 }
  63
  64 /**
  65  * clear_update_marker - clear update marker.
  66  * @ubi: UBI device description object
  67  * @vol: volume description object
  68  * @bytes: new data size in bytes
  69  *
  70  * This function clears the update marker for volume @vol, sets new volume
  71  * data size and clears the "corrupted" flag (static volumes only). Returns
  72  * zero in case of success and a negative error code in case of failure.
  73  */
  74 static int clear_update_marker(struct ubi_device *ubi, struct ubi_volume *vol,
  75                                long long bytes)
  76 {
  77         int err;
  78         struct ubi_vtbl_record vtbl_rec;
  79
  80         dbg_gen("clear update marker for volume %d", vol->vol_id);
  81
  82         vtbl_rec = ubi->vtbl[vol->vol_id];
  83         ubi_assert(vol->upd_marker && vtbl_rec.upd_marker);
  84         vtbl_rec.upd_marker = 0;
  85
  86         if (vol->vol_type == UBI_STATIC_VOLUME) {
  87                 vol->corrupted = 0;
  88                 vol->used_bytes = bytes;
  89                 vol->used_ebs = div_u64_rem(bytes, vol->usable_leb_size,
  90                                             &vol->last_eb_bytes);
  91                 if (vol->last_eb_bytes)
  92                         vol->used_ebs += 1;
  93                 else
  94                         vol->last_eb_bytes = vol->usable_leb_size;
  95         }
  96
  97         mutex_lock(&ubi->device_mutex);
  98         err = ubi_change_vtbl_record(ubi, vol->vol_id, &vtbl_rec);
  99         vol->upd_marker = 0;
 100         mutex_unlock(&ubi->device_mutex);
 101         return err;
 102 }
 103
 104 /**
 105  * ubi_start_update - start volume update.
 106  * @ubi: UBI device description object
 107  * @vol: volume description object
 108  * @bytes: update bytes
 109  *
 110  * This function starts volume update operation. If @bytes is zero, the volume
 111  * is just wiped out. Returns zero in case of success and a negative error code
 112  * in case of failure.
 113  */
 114 int ubi_start_update(struct ubi_device *ubi, struct ubi_volume *vol,
 115                      long long bytes)
 116 {
 117         int i, err;
 118
 119         dbg_gen("start update of volume %d, %llu bytes", vol->vol_id, bytes);
 120         ubi_assert(!vol->updating && !vol->changing_leb);
 121         vol->updating = 1;
 122
 123         vol->upd_buf = vmalloc(ubi->leb_size);
 124         if (!vol->upd_buf)
 125                 return -ENOMEM;
 126
 127         err = set_update_marker(ubi, vol);
 128         if (err)
 129                 return err;
 130
 131         /* Before updating - wipe out the volume */
 132         for (i = 0; i < vol->reserved_pebs; i++) {
 133                 err = ubi_eba_unmap_leb(ubi, vol, i);
 134                 if (err)
 135                         return err;
 136         }
 137
 138         err = ubi_wl_flush(ubi, UBI_ALL, UBI_ALL);
 139         if (err)
 140                 return err;
 141
 142         if (bytes == 0) {
 143                 err = clear_update_marker(ubi, vol, 0);
 144                 if (err)
 145                         return err;
 146
 147                 vfree(vol->upd_buf);
 148                 vol->updating = 0;
 149                 return 0;
 150         }
 151
 152         vol->upd_ebs = div_u64(bytes + vol->usable_leb_size - 1,
 153                                vol->usable_leb_size);
 154         vol->upd_bytes = bytes;
 155         vol->upd_received = 0;
 156         return 0;
 157 }
 158
 159 /**
 160  * ubi_start_leb_change - start atomic LEB change.
 161  * @ubi: UBI device description object
 162  * @vol: volume description object
 163  * @req: operation request
 164  *
 165  * This function starts atomic LEB change operation. Returns zero in case of
 166  * success and a negative error code in case of failure.
 167  */
 168 int ubi_start_leb_change(struct ubi_device *ubi, struct ubi_volume *vol,
 169                          const struct ubi_leb_change_req *req)
 170 {
 171         ubi_assert(!vol->updating && !vol->changing_leb);
 172
 173         dbg_gen("start changing LEB %d:%d, %u bytes",
 174                 vol->vol_id, req->lnum, req->bytes);
 175         if (req->bytes == 0)
 176                 return ubi_eba_atomic_leb_change(ubi, vol, req->lnum, NULL, 0);
 177
 178         vol->upd_bytes = req->bytes;
 179         vol->upd_received = 0;
 180         vol->changing_leb = 1;
 181         vol->ch_lnum = req->lnum;
 182
 183         vol->upd_buf = vmalloc(ALIGN((int)req->bytes, ubi->min_io_size));
 184         if (!vol->upd_buf)
 185                 return -ENOMEM;
 186
 187         return 0;
 188 }
 189
 190 /**
 191  * write_leb - write update data.
 192  * @ubi: UBI device description object
 193  * @vol: volume description object
 194  * @lnum: logical eraseblock number
 195  * @buf: data to write
 196  * @len: data size
 197  * @used_ebs: how many logical eraseblocks will this volume contain (static
 198  * volumes only)
 199  *
 200  * This function writes update data to corresponding logical eraseblock. In
 201  * case of dynamic volume, this function checks if the data contains 0xFF bytes
 202  * at the end. If yes, the 0xFF bytes are cut and not written. So if the whole
 203  * buffer contains only 0xFF bytes, the LEB is left unmapped.
 204  *
 205  * The reason why we skip the trailing 0xFF bytes in case of dynamic volume is
 206  * that we want to make sure that more data may be appended to the logical
 207  * eraseblock in future. Indeed, writing 0xFF bytes may have side effects and
 208  * this PEB won't be writable anymore. So if one writes the file-system image
 209  * to the UBI volume where 0xFFs mean free space - UBI makes sure this free
 210  * space is writable after the update.
 211  *
 212  * We do not do this for static volumes because they are read-only. But this
 213  * also cannot be done because we have to store per-LEB CRC and the correct
 214  * data length.
 215  *
 216  * This function returns zero in case of success and a negative error code in
 217  * case of failure.
 218  */
 219 static int write_leb(struct ubi_device *ubi, struct ubi_volume *vol, int lnum,
 220                      void *buf, int len, int used_ebs)
 221 {
 222         int err;
 223
 224         if (vol->vol_type == UBI_DYNAMIC_VOLUME) {
 225                 int l = ALIGN(len, ubi->min_io_size);
 226
 227                 memset(buf + len, 0xFF, l - len);
 228                 len = ubi_calc_data_len(ubi, buf, l);
 229                 if (len == 0) {
 230                         dbg_gen("all %d bytes contain 0xFF - skip", len);
 231                         return 0;
 232                 }
 233
 234                 err = ubi_eba_write_leb(ubi, vol, lnum, buf, 0, len);
 235         } else {
 236                 /*
 237                  * When writing static volume, and this is the last logical
 238                  * eraseblock, the length (@len) does not have to be aligned to
 239                  * the minimal flash I/O unit. The 'ubi_eba_write_leb_st()'
 240                  * function accepts exact (unaligned) length and stores it in
 241                  * the VID header. And it takes care of proper alignment by
 242                  * padding the buffer. Here we just make sure the padding will
 243                  * contain zeros, not random trash.
 244                  */
 245                 memset(buf + len, 0, vol->usable_leb_size - len);
 246                 err = ubi_eba_write_leb_st(ubi, vol, lnum, buf, len, used_ebs);
 247         }
 248
 249         return err;
 250 }
 251
 252 /**
 253  * ubi_more_update_data - write more update data.
 254  * @ubi: UBI device description object
 255  * @vol: volume description object
 256  * @buf: write data (user-space memory buffer)
 257  * @count: how much bytes to write
 258  *
 259  * This function writes more data to the volume which is being updated. It may
 260  * be called arbitrary number of times until all the update data arriveis. This
 261  * function returns %0 in case of success, number of bytes written during the
 262  * last call if the whole volume update has been successfully finished, and a
 263  * negative error code in case of failure.
 264  */
 265 int ubi_more_update_data(struct ubi_device *ubi, struct ubi_volume *vol,
 266                          const void __user *buf, int count)
 267 {
 268         int lnum, offs, err = 0, len, to_write = count;
 269
 270         dbg_gen("write %d of %lld bytes, %lld already passed",
 271                 count, vol->upd_bytes, vol->upd_received);
 272
 273         if (ubi->ro_mode)
 274                 return -EROFS;
 275
 276         lnum = div_u64_rem(vol->upd_received,  vol->usable_leb_size, &offs);
 277         if (vol->upd_received + count > vol->upd_bytes)
 278                 to_write = count = vol->upd_bytes - vol->upd_received;
 279
 280         /*
 281          * When updating volumes, we accumulate whole logical eraseblock of
 282          * data and write it at once.
 283          */
 284         if (offs != 0) {
 285                 /*
 286                  * This is a write to the middle of the logical eraseblock. We
 287                  * copy the data to our update buffer and wait for more data or
 288                  * flush it if the whole eraseblock is written or the update
 289                  * is finished.
 290                  */
 291
 292                 len = vol->usable_leb_size - offs;
 293                 if (len > count)
 294                         len = count;
 295
 296                 err = copy_from_user(vol->upd_buf + offs, buf, len);
 297                 if (err)
 298                         return -EFAULT;
 299
 300                 if (offs + len == vol->usable_leb_size ||
 301                     vol->upd_received + len == vol->upd_bytes) {
 302                         int flush_len = offs + len;
 303
 304                         /*
 305                          * OK, we gathered either the whole eraseblock or this
 306                          * is the last chunk, it's time to flush the buffer.
 307                          */
 308                         ubi_assert(flush_len <= vol->usable_leb_size);
 309                         err = write_leb(ubi, vol, lnum, vol->upd_buf, flush_len,
 310                                         vol->upd_ebs);
 311                         if (err)
 312                                 return err;
 313                 }
 314
 315                 vol->upd_received += len;
 316                 count -= len;
 317                 buf += len;
 318                 lnum += 1;
 319         }
 320
 321         /*
 322          * If we've got more to write, let's continue. At this point we know we
 323          * are starting from the beginning of an eraseblock.
 324          */
 325         while (count) {
 326                 if (count > vol->usable_leb_size)
 327                         len = vol->usable_leb_size;
 328                 else
 329                         len = count;
 330
 331                 err = copy_from_user(vol->upd_buf, buf, len);
 332                 if (err)
 333                         return -EFAULT;
 334
 335                 if (len == vol->usable_leb_size ||
 336                     vol->upd_received + len == vol->upd_bytes) {
 337                         err = write_leb(ubi, vol, lnum, vol->upd_buf,
 338                                         len, vol->upd_ebs);
 339                         if (err)
 340                                 break;
 341                 }
 342
 343                 vol->upd_received += len;
 344                 count -= len;
 345                 lnum += 1;
 346                 buf += len;
 347         }
 348
 349         ubi_assert(vol->upd_received <= vol->upd_bytes);
 350         if (vol->upd_received == vol->upd_bytes) {
 351                 err = ubi_wl_flush(ubi, UBI_ALL, UBI_ALL);
 352                 if (err)
 353                         return err;
 354                 /* The update is finished, clear the update marker */
 355                 err = clear_update_marker(ubi, vol, vol->upd_bytes);
 356                 if (err)
 357                         return err;
 358                 vol->updating = 0;
 359                 err = to_write;
 360                 vfree(vol->upd_buf);
 361         }
 362
 363         return err;
 364 }
 365
 366 /**
 367  * ubi_more_leb_change_data - accept more data for atomic LEB change.
 368  * @ubi: UBI device description object
 369  * @vol: volume description object
 370  * @buf: write data (user-space memory buffer)
 371  * @count: how much bytes to write
 372  *
 373  * This function accepts more data to the volume which is being under the
 374  * "atomic LEB change" operation. It may be called arbitrary number of times
 375  * until all data arrives. This function returns %0 in case of success, number
 376  * of bytes written during the last call if the whole "atomic LEB change"
 377  * operation has been successfully finished, and a negative error code in case
 378  * of failure.
 379  */
 380 int ubi_more_leb_change_data(struct ubi_device *ubi, struct ubi_volume *vol,
 381                              const void __user *buf, int count)
 382 {
 383         int err;
 384
 385         dbg_gen("write %d of %lld bytes, %lld already passed",
 386                 count, vol->upd_bytes, vol->upd_received);
 387
 388         if (ubi->ro_mode)
 389                 return -EROFS;
 390
 391         if (vol->upd_received + count > vol->upd_bytes)
 392                 count = vol->upd_bytes - vol->upd_received;
 393
 394         err = copy_from_user(vol->upd_buf + vol->upd_received, buf, count);
 395         if (err)
 396                 return -EFAULT;
 397
 398         vol->upd_received += count;
 399
 400         if (vol->upd_received == vol->upd_bytes) {
 401                 int len = ALIGN((int)vol->upd_bytes, ubi->min_io_size);
 402
 403                 memset(vol->upd_buf + vol->upd_bytes, 0xFF,
 404                        len - vol->upd_bytes);
 405                 len = ubi_calc_data_len(ubi, vol->upd_buf, len);
 406                 err = ubi_eba_atomic_leb_change(ubi, vol, vol->ch_lnum,
 407                                                 vol->upd_buf, len);
 408                 if (err)
 409                         return err;
 410         }
 411
 412         ubi_assert(vol->upd_received <= vol->upd_bytes);
 413         if (vol->upd_received == vol->upd_bytes) {
 414                 vol->changing_leb = 0;
 415                 err = count;
 416                 vfree(vol->upd_buf);
 417         }
 418
 419         return err;
 420 }