fs/exfat/fatent.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Copyright (C) 2012-2013 Samsung Electronics Co., Ltd.
   4  */
   5
   6 #include <linux/slab.h>
   7 #include <linux/unaligned.h>
   8 #include <linux/buffer_head.h>
   9 #include <linux/blkdev.h>
  10
  11 #include "exfat_raw.h"
  12 #include "exfat_fs.h"
  13
  14 static int exfat_mirror_bh(struct super_block *sb, sector_t sec,
  15                 struct buffer_head *bh)
  16 {
  17         struct buffer_head *c_bh;
  18         struct exfat_sb_info *sbi = EXFAT_SB(sb);
  19         sector_t sec2;
  20         int err = 0;
  21
  22         if (sbi->FAT2_start_sector != sbi->FAT1_start_sector) {
  23                 sec2 = sec - sbi->FAT1_start_sector + sbi->FAT2_start_sector;
  24                 c_bh = sb_getblk(sb, sec2);
  25                 if (!c_bh)
  26                         return -ENOMEM;
  27                 memcpy(c_bh->b_data, bh->b_data, sb->s_blocksize);
  28                 set_buffer_uptodate(c_bh);
  29                 mark_buffer_dirty(c_bh);
  30                 if (sb->s_flags & SB_SYNCHRONOUS)
  31                         err = sync_dirty_buffer(c_bh);
  32                 brelse(c_bh);
  33         }
  34
  35         return err;
  36 }
  37
  38 static int __exfat_ent_get(struct super_block *sb, unsigned int loc,
  39                 unsigned int *content)
  40 {
  41         unsigned int off;
  42         sector_t sec;
  43         struct buffer_head *bh;
  44
  45         sec = FAT_ENT_OFFSET_SECTOR(sb, loc);
  46         off = FAT_ENT_OFFSET_BYTE_IN_SECTOR(sb, loc);
  47
  48         bh = sb_bread(sb, sec);
  49         if (!bh)
  50                 return -EIO;
  51
  52         *content = le32_to_cpu(*(__le32 *)(&bh->b_data[off]));
  53
  54         /* remap reserved clusters to simplify code */
  55         if (*content > EXFAT_BAD_CLUSTER)
  56                 *content = EXFAT_EOF_CLUSTER;
  57
  58         brelse(bh);
  59         return 0;
  60 }
  61
  62 int exfat_ent_set(struct super_block *sb, unsigned int loc,
  63                 unsigned int content)
  64 {
  65         unsigned int off;
  66         sector_t sec;
  67         __le32 *fat_entry;
  68         struct buffer_head *bh;
  69
  70         sec = FAT_ENT_OFFSET_SECTOR(sb, loc);
  71         off = FAT_ENT_OFFSET_BYTE_IN_SECTOR(sb, loc);
  72
  73         bh = sb_bread(sb, sec);
  74         if (!bh)
  75                 return -EIO;
  76
  77         fat_entry = (__le32 *)&(bh->b_data[off]);
  78         *fat_entry = cpu_to_le32(content);
  79         exfat_update_bh(bh, sb->s_flags & SB_SYNCHRONOUS);
  80         exfat_mirror_bh(sb, sec, bh);
  81         brelse(bh);
  82         return 0;
  83 }
  84
  85 int exfat_ent_get(struct super_block *sb, unsigned int loc,
  86                 unsigned int *content)
  87 {
  88         struct exfat_sb_info *sbi = EXFAT_SB(sb);
  89         int err;
  90
  91         if (!is_valid_cluster(sbi, loc)) {
  92                 exfat_fs_error(sb, "invalid access to FAT (entry 0x%08x)",
  93                         loc);
  94                 return -EIO;
  95         }
  96
  97         err = __exfat_ent_get(sb, loc, content);
  98         if (err) {
  99                 exfat_fs_error(sb,
 100                         "failed to access to FAT (entry 0x%08x, err:%d)",
 101                         loc, err);
 102                 return err;
 103         }
 104
 105         if (*content == EXFAT_FREE_CLUSTER) {
 106                 exfat_fs_error(sb,
 107                         "invalid access to FAT free cluster (entry 0x%08x)",
 108                         loc);
 109                 return -EIO;
 110         }
 111
 112         if (*content == EXFAT_BAD_CLUSTER) {
 113                 exfat_fs_error(sb,
 114                         "invalid access to FAT bad cluster (entry 0x%08x)",
 115                         loc);
 116                 return -EIO;
 117         }
 118
 119         if (*content != EXFAT_EOF_CLUSTER && !is_valid_cluster(sbi, *content)) {
 120                 exfat_fs_error(sb,
 121                         "invalid access to FAT (entry 0x%08x) bogus content (0x%08x)",
 122                         loc, *content);
 123                 return -EIO;
 124         }
 125
 126         return 0;
 127 }
 128
 129 int exfat_chain_cont_cluster(struct super_block *sb, unsigned int chain,
 130                 unsigned int len)
 131 {
 132         if (!len)
 133                 return 0;
 134
 135         while (len > 1) {
 136                 if (exfat_ent_set(sb, chain, chain + 1))
 137                         return -EIO;
 138                 chain++;
 139                 len--;
 140         }
 141
 142         if (exfat_ent_set(sb, chain, EXFAT_EOF_CLUSTER))
 143                 return -EIO;
 144         return 0;
 145 }
 146
 147 /* This function must be called with bitmap_lock held */
 148 static int __exfat_free_cluster(struct inode *inode, struct exfat_chain *p_chain)
 149 {
 150         struct super_block *sb = inode->i_sb;
 151         struct exfat_sb_info *sbi = EXFAT_SB(sb);
 152         int cur_cmap_i, next_cmap_i;
 153         unsigned int num_clusters = 0;
 154         unsigned int clu;
 155
 156         /* invalid cluster number */
 157         if (p_chain->dir == EXFAT_FREE_CLUSTER ||
 158             p_chain->dir == EXFAT_EOF_CLUSTER ||
 159             p_chain->dir < EXFAT_FIRST_CLUSTER)
 160                 return 0;
 161
 162         /* no cluster to truncate */
 163         if (p_chain->size == 0)
 164                 return 0;
 165
 166         /* check cluster validation */
 167         if (!is_valid_cluster(sbi, p_chain->dir)) {
 168                 exfat_err(sb, "invalid start cluster (%u)", p_chain->dir);
 169                 return -EIO;
 170         }
 171
 172         clu = p_chain->dir;
 173
 174         cur_cmap_i = next_cmap_i =
 175                 BITMAP_OFFSET_SECTOR_INDEX(sb, CLUSTER_TO_BITMAP_ENT(clu));
 176
 177         if (p_chain->flags == ALLOC_NO_FAT_CHAIN) {
 178                 unsigned int last_cluster = p_chain->dir + p_chain->size - 1;
 179                 do {
 180                         bool sync = false;
 181
 182                         if (clu < last_cluster)
 183                                 next_cmap_i =
 184                                   BITMAP_OFFSET_SECTOR_INDEX(sb, CLUSTER_TO_BITMAP_ENT(clu+1));
 185
 186                         /* flush bitmap only if index would be changed or for last cluster */
 187                         if (clu == last_cluster || cur_cmap_i != next_cmap_i) {
 188                                 sync = true;
 189                                 cur_cmap_i = next_cmap_i;
 190                         }
 191
 192                         exfat_clear_bitmap(inode, clu, (sync && IS_DIRSYNC(inode)));
 193                         clu++;
 194                         num_clusters++;
 195                 } while (num_clusters < p_chain->size);
 196         } else {
 197                 do {
 198                         bool sync = false;
 199                         unsigned int n_clu = clu;
 200                         int err = exfat_get_next_cluster(sb, &n_clu);
 201
 202                         if (err || n_clu == EXFAT_EOF_CLUSTER)
 203                                 sync = true;
 204                         else
 205                                 next_cmap_i =
 206                                   BITMAP_OFFSET_SECTOR_INDEX(sb, CLUSTER_TO_BITMAP_ENT(n_clu));
 207
 208                         if (cur_cmap_i != next_cmap_i) {
 209                                 sync = true;
 210                                 cur_cmap_i = next_cmap_i;
 211                         }
 212
 213                         exfat_clear_bitmap(inode, clu, (sync && IS_DIRSYNC(inode)));
 214                         clu = n_clu;
 215                         num_clusters++;
 216
 217                         if (err)
 218                                 goto dec_used_clus;
 219
 220                         if (num_clusters >= sbi->num_clusters - EXFAT_FIRST_CLUSTER) {
 221                                 /*
 222                                  * The cluster chain includes a loop, scan the
 223                                  * bitmap to get the number of used clusters.
 224                                  */
 225                                 exfat_count_used_clusters(sb, &sbi->used_clusters);
 226
 227                                 return 0;
 228                         }
 229                 } while (clu != EXFAT_EOF_CLUSTER);
 230         }
 231
 232 dec_used_clus:
 233         sbi->used_clusters -= num_clusters;
 234         return 0;
 235 }
 236
 237 int exfat_free_cluster(struct inode *inode, struct exfat_chain *p_chain)
 238 {
 239         int ret = 0;
 240
 241         mutex_lock(&EXFAT_SB(inode->i_sb)->bitmap_lock);
 242         ret = __exfat_free_cluster(inode, p_chain);
 243         mutex_unlock(&EXFAT_SB(inode->i_sb)->bitmap_lock);
 244
 245         return ret;
 246 }
 247
 248 int exfat_find_last_cluster(struct super_block *sb, struct exfat_chain *p_chain,
 249                 unsigned int *ret_clu)
 250 {
 251         unsigned int clu, next;
 252         unsigned int count = 0;
 253
 254         next = p_chain->dir;
 255         if (p_chain->flags == ALLOC_NO_FAT_CHAIN) {
 256                 *ret_clu = next + p_chain->size - 1;
 257                 return 0;
 258         }
 259
 260         do {
 261                 count++;
 262                 clu = next;
 263                 if (exfat_ent_get(sb, clu, &next))
 264                         return -EIO;
 265         } while (next != EXFAT_EOF_CLUSTER);
 266
 267         if (p_chain->size != count) {
 268                 exfat_fs_error(sb,
 269                         "bogus directory size (clus : ondisk(%d) != counted(%d))",
 270                         p_chain->size, count);
 271                 return -EIO;
 272         }
 273
 274         *ret_clu = clu;
 275         return 0;
 276 }
 277
 278 int exfat_zeroed_cluster(struct inode *dir, unsigned int clu)
 279 {
 280         struct super_block *sb = dir->i_sb;
 281         struct exfat_sb_info *sbi = EXFAT_SB(sb);
 282         struct buffer_head *bh;
 283         sector_t blknr, last_blknr, i;
 284
 285         blknr = exfat_cluster_to_sector(sbi, clu);
 286         last_blknr = blknr + sbi->sect_per_clus;
 287
 288         if (last_blknr > sbi->num_sectors && sbi->num_sectors > 0) {
 289                 exfat_fs_error_ratelimit(sb,
 290                         "%s: out of range(sect:%llu len:%u)",
 291                         __func__, (unsigned long long)blknr,
 292                         sbi->sect_per_clus);
 293                 return -EIO;
 294         }
 295
 296         /* Zeroing the unused blocks on this cluster */
 297         for (i = blknr; i < last_blknr; i++) {
 298                 bh = sb_getblk(sb, i);
 299                 if (!bh)
 300                         return -ENOMEM;
 301
 302                 memset(bh->b_data, 0, sb->s_blocksize);
 303                 set_buffer_uptodate(bh);
 304                 mark_buffer_dirty(bh);
 305                 brelse(bh);
 306         }
 307
 308         if (IS_DIRSYNC(dir))
 309                 return sync_blockdev_range(sb->s_bdev,
 310                                 EXFAT_BLK_TO_B(blknr, sb),
 311                                 EXFAT_BLK_TO_B(last_blknr, sb) - 1);
 312
 313         return 0;
 314 }
 315
 316 int exfat_alloc_cluster(struct inode *inode, unsigned int num_alloc,
 317                 struct exfat_chain *p_chain, bool sync_bmap)
 318 {
 319         int ret = -ENOSPC;
 320         unsigned int total_cnt;
 321         unsigned int hint_clu, new_clu, last_clu = EXFAT_EOF_CLUSTER;
 322         struct super_block *sb = inode->i_sb;
 323         struct exfat_sb_info *sbi = EXFAT_SB(sb);
 324
 325         total_cnt = EXFAT_DATA_CLUSTER_COUNT(sbi);
 326
 327         if (unlikely(total_cnt < sbi->used_clusters)) {
 328                 exfat_fs_error_ratelimit(sb,
 329                         "%s: invalid used clusters(t:%u,u:%u)\n",
 330                         __func__, total_cnt, sbi->used_clusters);
 331                 return -EIO;
 332         }
 333
 334         if (num_alloc > total_cnt - sbi->used_clusters)
 335                 return -ENOSPC;
 336
 337         mutex_lock(&sbi->bitmap_lock);
 338
 339         hint_clu = p_chain->dir;
 340         /* find new cluster */
 341         if (hint_clu == EXFAT_EOF_CLUSTER) {
 342                 if (sbi->clu_srch_ptr < EXFAT_FIRST_CLUSTER) {
 343                         exfat_err(sb, "sbi->clu_srch_ptr is invalid (%u)",
 344                                   sbi->clu_srch_ptr);
 345                         sbi->clu_srch_ptr = EXFAT_FIRST_CLUSTER;
 346                 }
 347
 348                 hint_clu = exfat_find_free_bitmap(sb, sbi->clu_srch_ptr);
 349                 if (hint_clu == EXFAT_EOF_CLUSTER) {
 350                         ret = -ENOSPC;
 351                         goto unlock;
 352                 }
 353         }
 354
 355         /* check cluster validation */
 356         if (!is_valid_cluster(sbi, hint_clu)) {
 357                 if (hint_clu != sbi->num_clusters)
 358                         exfat_err(sb, "hint_cluster is invalid (%u), rewind to the first cluster",
 359                                         hint_clu);
 360                 hint_clu = EXFAT_FIRST_CLUSTER;
 361                 p_chain->flags = ALLOC_FAT_CHAIN;
 362         }
 363
 364         p_chain->dir = EXFAT_EOF_CLUSTER;
 365
 366         while ((new_clu = exfat_find_free_bitmap(sb, hint_clu)) !=
 367                EXFAT_EOF_CLUSTER) {
 368                 if (new_clu != hint_clu &&
 369                     p_chain->flags == ALLOC_NO_FAT_CHAIN) {
 370                         if (exfat_chain_cont_cluster(sb, p_chain->dir,
 371                                         p_chain->size)) {
 372                                 ret = -EIO;
 373                                 goto free_cluster;
 374                         }
 375                         p_chain->flags = ALLOC_FAT_CHAIN;
 376                 }
 377
 378                 /* update allocation bitmap */
 379                 if (exfat_set_bitmap(inode, new_clu, sync_bmap)) {
 380                         ret = -EIO;
 381                         goto free_cluster;
 382                 }
 383
 384                 /* update FAT table */
 385                 if (p_chain->flags == ALLOC_FAT_CHAIN) {
 386                         if (exfat_ent_set(sb, new_clu, EXFAT_EOF_CLUSTER)) {
 387                                 ret = -EIO;
 388                                 goto free_cluster;
 389                         }
 390                 }
 391
 392                 if (p_chain->dir == EXFAT_EOF_CLUSTER) {
 393                         p_chain->dir = new_clu;
 394                 } else if (p_chain->flags == ALLOC_FAT_CHAIN) {
 395                         if (exfat_ent_set(sb, last_clu, new_clu)) {
 396                                 ret = -EIO;
 397                                 goto free_cluster;
 398                         }
 399                 }
 400                 p_chain->size++;
 401
 402                 last_clu = new_clu;
 403
 404                 if (p_chain->size == num_alloc) {
 405                         sbi->clu_srch_ptr = hint_clu;
 406                         sbi->used_clusters += num_alloc;
 407
 408                         mutex_unlock(&sbi->bitmap_lock);
 409                         return 0;
 410                 }
 411
 412                 hint_clu = new_clu + 1;
 413                 if (hint_clu >= sbi->num_clusters) {
 414                         hint_clu = EXFAT_FIRST_CLUSTER;
 415
 416                         if (p_chain->flags == ALLOC_NO_FAT_CHAIN) {
 417                                 if (exfat_chain_cont_cluster(sb, p_chain->dir,
 418                                                 p_chain->size)) {
 419                                         ret = -EIO;
 420                                         goto free_cluster;
 421                                 }
 422                                 p_chain->flags = ALLOC_FAT_CHAIN;
 423                         }
 424                 }
 425         }
 426 free_cluster:
 427         __exfat_free_cluster(inode, p_chain);
 428 unlock:
 429         mutex_unlock(&sbi->bitmap_lock);
 430         return ret;
 431 }
 432
 433 int exfat_count_num_clusters(struct super_block *sb,
 434                 struct exfat_chain *p_chain, unsigned int *ret_count)
 435 {
 436         unsigned int i, count;
 437         unsigned int clu;
 438         struct exfat_sb_info *sbi = EXFAT_SB(sb);
 439
 440         if (!p_chain->dir || p_chain->dir == EXFAT_EOF_CLUSTER) {
 441                 *ret_count = 0;
 442                 return 0;
 443         }
 444
 445         if (p_chain->flags == ALLOC_NO_FAT_CHAIN) {
 446                 *ret_count = p_chain->size;
 447                 return 0;
 448         }
 449
 450         clu = p_chain->dir;
 451         count = 0;
 452         for (i = EXFAT_FIRST_CLUSTER; i < sbi->num_clusters; i++) {
 453                 count++;
 454                 if (exfat_ent_get(sb, clu, &clu))
 455                         return -EIO;
 456                 if (clu == EXFAT_EOF_CLUSTER)
 457                         break;
 458         }
 459
 460         *ret_count = count;
 461         return 0;
 462 }