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 <asm/unaligned.h>
   8 #include <linux/buffer_head.h>
   9
  10 #include "exfat_raw.h"
  11 #include "exfat_fs.h"
  12
  13 static int exfat_mirror_bh(struct super_block *sb, sector_t sec,
  14                 struct buffer_head *bh)
  15 {
  16         struct buffer_head *c_bh;
  17         struct exfat_sb_info *sbi = EXFAT_SB(sb);
  18         sector_t sec2;
  19         int err = 0;
  20
  21         if (sbi->FAT2_start_sector != sbi->FAT1_start_sector) {
  22                 sec2 = sec - sbi->FAT1_start_sector + sbi->FAT2_start_sector;
  23                 c_bh = sb_getblk(sb, sec2);
  24                 if (!c_bh)
  25                         return -ENOMEM;
  26                 memcpy(c_bh->b_data, bh->b_data, sb->s_blocksize);
  27                 set_buffer_uptodate(c_bh);
  28                 mark_buffer_dirty(c_bh);
  29                 if (sb->s_flags & SB_SYNCHRONOUS)
  30                         err = sync_dirty_buffer(c_bh);
  31                 brelse(c_bh);
  32         }
  33
  34         return err;
  35 }
  36
  37 static int __exfat_ent_get(struct super_block *sb, unsigned int loc,
  38                 unsigned int *content)
  39 {
  40         unsigned int off;
  41         sector_t sec;
  42         struct buffer_head *bh;
  43
  44         sec = FAT_ENT_OFFSET_SECTOR(sb, loc);
  45         off = FAT_ENT_OFFSET_BYTE_IN_SECTOR(sb, loc);
  46
  47         bh = sb_bread(sb, sec);
  48         if (!bh)
  49                 return -EIO;
  50
  51         *content = le32_to_cpu(*(__le32 *)(&bh->b_data[off]));
  52
  53         /* remap reserved clusters to simplify code */
  54         if (*content > EXFAT_BAD_CLUSTER)
  55                 *content = EXFAT_EOF_CLUSTER;
  56
  57         brelse(bh);
  58         return 0;
  59 }
  60
  61 int exfat_ent_set(struct super_block *sb, unsigned int loc,
  62                 unsigned int content)
  63 {
  64         unsigned int off;
  65         sector_t sec;
  66         __le32 *fat_entry;
  67         struct buffer_head *bh;
  68
  69         sec = FAT_ENT_OFFSET_SECTOR(sb, loc);
  70         off = FAT_ENT_OFFSET_BYTE_IN_SECTOR(sb, loc);
  71
  72         bh = sb_bread(sb, sec);
  73         if (!bh)
  74                 return -EIO;
  75
  76         fat_entry = (__le32 *)&(bh->b_data[off]);
  77         *fat_entry = cpu_to_le32(content);
  78         exfat_update_bh(bh, sb->s_flags & SB_SYNCHRONOUS);
  79         exfat_mirror_bh(sb, sec, bh);
  80         brelse(bh);
  81         return 0;
  82 }
  83
  84 static inline bool is_valid_cluster(struct exfat_sb_info *sbi,
  85                 unsigned int clus)
  86 {
  87         if (clus < EXFAT_FIRST_CLUSTER || sbi->num_clusters <= clus)
  88                 return false;
  89         return true;
  90 }
  91
  92 int exfat_ent_get(struct super_block *sb, unsigned int loc,
  93                 unsigned int *content)
  94 {
  95         struct exfat_sb_info *sbi = EXFAT_SB(sb);
  96         int err;
  97
  98         if (!is_valid_cluster(sbi, loc)) {
  99                 exfat_fs_error(sb, "invalid access to FAT (entry 0x%08x)",
 100                         loc);
 101                 return -EIO;
 102         }
 103
 104         err = __exfat_ent_get(sb, loc, content);
 105         if (err) {
 106                 exfat_fs_error(sb,
 107                         "failed to access to FAT (entry 0x%08x, err:%d)",
 108                         loc, err);
 109                 return err;
 110         }
 111
 112         if (*content == EXFAT_FREE_CLUSTER) {
 113                 exfat_fs_error(sb,
 114                         "invalid access to FAT free cluster (entry 0x%08x)",
 115                         loc);
 116                 return -EIO;
 117         }
 118
 119         if (*content == EXFAT_BAD_CLUSTER) {
 120                 exfat_fs_error(sb,
 121                         "invalid access to FAT bad cluster (entry 0x%08x)",
 122                         loc);
 123                 return -EIO;
 124         }
 125
 126         if (*content != EXFAT_EOF_CLUSTER && !is_valid_cluster(sbi, *content)) {
 127                 exfat_fs_error(sb,
 128                         "invalid access to FAT (entry 0x%08x) bogus content (0x%08x)",
 129                         loc, *content);
 130                 return -EIO;
 131         }
 132
 133         return 0;
 134 }
 135
 136 int exfat_chain_cont_cluster(struct super_block *sb, unsigned int chain,
 137                 unsigned int len)
 138 {
 139         if (!len)
 140                 return 0;
 141
 142         while (len > 1) {
 143                 if (exfat_ent_set(sb, chain, chain + 1))
 144                         return -EIO;
 145                 chain++;
 146                 len--;
 147         }
 148
 149         if (exfat_ent_set(sb, chain, EXFAT_EOF_CLUSTER))
 150                 return -EIO;
 151         return 0;
 152 }
 153
 154 /* This function must be called with bitmap_lock held */
 155 static int __exfat_free_cluster(struct inode *inode, struct exfat_chain *p_chain)
 156 {
 157         struct super_block *sb = inode->i_sb;
 158         struct exfat_sb_info *sbi = EXFAT_SB(sb);
 159         int cur_cmap_i, next_cmap_i;
 160         unsigned int num_clusters = 0;
 161         unsigned int clu;
 162
 163         /* invalid cluster number */
 164         if (p_chain->dir == EXFAT_FREE_CLUSTER ||
 165             p_chain->dir == EXFAT_EOF_CLUSTER ||
 166             p_chain->dir < EXFAT_FIRST_CLUSTER)
 167                 return 0;
 168
 169         /* no cluster to truncate */
 170         if (p_chain->size == 0)
 171                 return 0;
 172
 173         /* check cluster validation */
 174         if (!is_valid_cluster(sbi, p_chain->dir)) {
 175                 exfat_err(sb, "invalid start cluster (%u)", p_chain->dir);
 176                 return -EIO;
 177         }
 178
 179         clu = p_chain->dir;
 180
 181         cur_cmap_i = next_cmap_i =
 182                 BITMAP_OFFSET_SECTOR_INDEX(sb, CLUSTER_TO_BITMAP_ENT(clu));
 183
 184         if (p_chain->flags == ALLOC_NO_FAT_CHAIN) {
 185                 unsigned int last_cluster = p_chain->dir + p_chain->size - 1;
 186                 do {
 187                         bool sync = false;
 188
 189                         if (clu < last_cluster)
 190                                 next_cmap_i =
 191                                   BITMAP_OFFSET_SECTOR_INDEX(sb, CLUSTER_TO_BITMAP_ENT(clu+1));
 192
 193                         /* flush bitmap only if index would be changed or for last cluster */
 194                         if (clu == last_cluster || cur_cmap_i != next_cmap_i) {
 195                                 sync = true;
 196                                 cur_cmap_i = next_cmap_i;
 197                         }
 198
 199                         exfat_clear_bitmap(inode, clu, (sync && IS_DIRSYNC(inode)));
 200                         clu++;
 201                         num_clusters++;
 202                 } while (num_clusters < p_chain->size);
 203         } else {
 204                 do {
 205                         bool sync = false;
 206                         unsigned int n_clu = clu;
 207                         int err = exfat_get_next_cluster(sb, &n_clu);
 208
 209                         if (err || n_clu == EXFAT_EOF_CLUSTER)
 210                                 sync = true;
 211                         else
 212                                 next_cmap_i =
 213                                   BITMAP_OFFSET_SECTOR_INDEX(sb, CLUSTER_TO_BITMAP_ENT(n_clu));
 214
 215                         if (cur_cmap_i != next_cmap_i) {
 216                                 sync = true;
 217                                 cur_cmap_i = next_cmap_i;
 218                         }
 219
 220                         exfat_clear_bitmap(inode, clu, (sync && IS_DIRSYNC(inode)));
 221                         clu = n_clu;
 222                         num_clusters++;
 223
 224                         if (err)
 225                                 goto dec_used_clus;
 226                 } while (clu != EXFAT_EOF_CLUSTER);
 227         }
 228
 229 dec_used_clus:
 230         sbi->used_clusters -= num_clusters;
 231         return 0;
 232 }
 233
 234 int exfat_free_cluster(struct inode *inode, struct exfat_chain *p_chain)
 235 {
 236         int ret = 0;
 237
 238         mutex_lock(&EXFAT_SB(inode->i_sb)->bitmap_lock);
 239         ret = __exfat_free_cluster(inode, p_chain);
 240         mutex_unlock(&EXFAT_SB(inode->i_sb)->bitmap_lock);
 241
 242         return ret;
 243 }
 244
 245 int exfat_find_last_cluster(struct super_block *sb, struct exfat_chain *p_chain,
 246                 unsigned int *ret_clu)
 247 {
 248         unsigned int clu, next;
 249         unsigned int count = 0;
 250
 251         next = p_chain->dir;
 252         if (p_chain->flags == ALLOC_NO_FAT_CHAIN) {
 253                 *ret_clu = next + p_chain->size - 1;
 254                 return 0;
 255         }
 256
 257         do {
 258                 count++;
 259                 clu = next;
 260                 if (exfat_ent_get(sb, clu, &next))
 261                         return -EIO;
 262         } while (next != EXFAT_EOF_CLUSTER);
 263
 264         if (p_chain->size != count) {
 265                 exfat_fs_error(sb,
 266                         "bogus directory size (clus : ondisk(%d) != counted(%d))",
 267                         p_chain->size, count);
 268                 return -EIO;
 269         }
 270
 271         *ret_clu = clu;
 272         return 0;
 273 }
 274
 275 int exfat_zeroed_cluster(struct inode *dir, unsigned int clu)
 276 {
 277         struct super_block *sb = dir->i_sb;
 278         struct exfat_sb_info *sbi = EXFAT_SB(sb);
 279         struct buffer_head *bhs[MAX_BUF_PER_PAGE];
 280         int nr_bhs = MAX_BUF_PER_PAGE;
 281         sector_t blknr, last_blknr;
 282         int err, i, n;
 283
 284         blknr = exfat_cluster_to_sector(sbi, clu);
 285         last_blknr = blknr + sbi->sect_per_clus;
 286
 287         if (last_blknr > sbi->num_sectors && sbi->num_sectors > 0) {
 288                 exfat_fs_error_ratelimit(sb,
 289                         "%s: out of range(sect:%llu len:%u)",
 290                         __func__, (unsigned long long)blknr,
 291                         sbi->sect_per_clus);
 292                 return -EIO;
 293         }
 294
 295         /* Zeroing the unused blocks on this cluster */
 296         while (blknr < last_blknr) {
 297                 for (n = 0; n < nr_bhs && blknr < last_blknr; n++, blknr++) {
 298                         bhs[n] = sb_getblk(sb, blknr);
 299                         if (!bhs[n]) {
 300                                 err = -ENOMEM;
 301                                 goto release_bhs;
 302                         }
 303                         memset(bhs[n]->b_data, 0, sb->s_blocksize);
 304                 }
 305
 306                 err = exfat_update_bhs(bhs, n, IS_DIRSYNC(dir));
 307                 if (err)
 308                         goto release_bhs;
 309
 310                 for (i = 0; i < n; i++)
 311                         brelse(bhs[i]);
 312         }
 313         return 0;
 314
 315 release_bhs:
 316         exfat_err(sb, "failed zeroed sect %llu\n", (unsigned long long)blknr);
 317         for (i = 0; i < n; i++)
 318                 bforget(bhs[i]);
 319         return err;
 320 }
 321
 322 int exfat_alloc_cluster(struct inode *inode, unsigned int num_alloc,
 323                 struct exfat_chain *p_chain, bool sync_bmap)
 324 {
 325         int ret = -ENOSPC;
 326         unsigned int num_clusters = 0, total_cnt;
 327         unsigned int hint_clu, new_clu, last_clu = EXFAT_EOF_CLUSTER;
 328         struct super_block *sb = inode->i_sb;
 329         struct exfat_sb_info *sbi = EXFAT_SB(sb);
 330
 331         total_cnt = EXFAT_DATA_CLUSTER_COUNT(sbi);
 332
 333         if (unlikely(total_cnt < sbi->used_clusters)) {
 334                 exfat_fs_error_ratelimit(sb,
 335                         "%s: invalid used clusters(t:%u,u:%u)\n",
 336                         __func__, total_cnt, sbi->used_clusters);
 337                 return -EIO;
 338         }
 339
 340         if (num_alloc > total_cnt - sbi->used_clusters)
 341                 return -ENOSPC;
 342
 343         mutex_lock(&sbi->bitmap_lock);
 344
 345         hint_clu = p_chain->dir;
 346         /* find new cluster */
 347         if (hint_clu == EXFAT_EOF_CLUSTER) {
 348                 if (sbi->clu_srch_ptr < EXFAT_FIRST_CLUSTER) {
 349                         exfat_err(sb, "sbi->clu_srch_ptr is invalid (%u)\n",
 350                                   sbi->clu_srch_ptr);
 351                         sbi->clu_srch_ptr = EXFAT_FIRST_CLUSTER;
 352                 }
 353
 354                 hint_clu = exfat_find_free_bitmap(sb, sbi->clu_srch_ptr);
 355                 if (hint_clu == EXFAT_EOF_CLUSTER) {
 356                         ret = -ENOSPC;
 357                         goto unlock;
 358                 }
 359         }
 360
 361         /* check cluster validation */
 362         if (!is_valid_cluster(sbi, hint_clu)) {
 363                 exfat_err(sb, "hint_cluster is invalid (%u)",
 364                         hint_clu);
 365                 hint_clu = EXFAT_FIRST_CLUSTER;
 366                 if (p_chain->flags == ALLOC_NO_FAT_CHAIN) {
 367                         if (exfat_chain_cont_cluster(sb, p_chain->dir,
 368                                         num_clusters)) {
 369                                 ret = -EIO;
 370                                 goto unlock;
 371                         }
 372                         p_chain->flags = ALLOC_FAT_CHAIN;
 373                 }
 374         }
 375
 376         p_chain->dir = EXFAT_EOF_CLUSTER;
 377
 378         while ((new_clu = exfat_find_free_bitmap(sb, hint_clu)) !=
 379                EXFAT_EOF_CLUSTER) {
 380                 if (new_clu != hint_clu &&
 381                     p_chain->flags == ALLOC_NO_FAT_CHAIN) {
 382                         if (exfat_chain_cont_cluster(sb, p_chain->dir,
 383                                         num_clusters)) {
 384                                 ret = -EIO;
 385                                 goto free_cluster;
 386                         }
 387                         p_chain->flags = ALLOC_FAT_CHAIN;
 388                 }
 389
 390                 /* update allocation bitmap */
 391                 if (exfat_set_bitmap(inode, new_clu, sync_bmap)) {
 392                         ret = -EIO;
 393                         goto free_cluster;
 394                 }
 395
 396                 num_clusters++;
 397
 398                 /* update FAT table */
 399                 if (p_chain->flags == ALLOC_FAT_CHAIN) {
 400                         if (exfat_ent_set(sb, new_clu, EXFAT_EOF_CLUSTER)) {
 401                                 ret = -EIO;
 402                                 goto free_cluster;
 403                         }
 404                 }
 405
 406                 if (p_chain->dir == EXFAT_EOF_CLUSTER) {
 407                         p_chain->dir = new_clu;
 408                 } else if (p_chain->flags == ALLOC_FAT_CHAIN) {
 409                         if (exfat_ent_set(sb, last_clu, new_clu)) {
 410                                 ret = -EIO;
 411                                 goto free_cluster;
 412                         }
 413                 }
 414                 last_clu = new_clu;
 415
 416                 if (--num_alloc == 0) {
 417                         sbi->clu_srch_ptr = hint_clu;
 418                         sbi->used_clusters += num_clusters;
 419
 420                         p_chain->size += num_clusters;
 421                         mutex_unlock(&sbi->bitmap_lock);
 422                         return 0;
 423                 }
 424
 425                 hint_clu = new_clu + 1;
 426                 if (hint_clu >= sbi->num_clusters) {
 427                         hint_clu = EXFAT_FIRST_CLUSTER;
 428
 429                         if (p_chain->flags == ALLOC_NO_FAT_CHAIN) {
 430                                 if (exfat_chain_cont_cluster(sb, p_chain->dir,
 431                                                 num_clusters)) {
 432                                         ret = -EIO;
 433                                         goto free_cluster;
 434                                 }
 435                                 p_chain->flags = ALLOC_FAT_CHAIN;
 436                         }
 437                 }
 438         }
 439 free_cluster:
 440         if (num_clusters)
 441                 __exfat_free_cluster(inode, p_chain);
 442 unlock:
 443         mutex_unlock(&sbi->bitmap_lock);
 444         return ret;
 445 }
 446
 447 int exfat_count_num_clusters(struct super_block *sb,
 448                 struct exfat_chain *p_chain, unsigned int *ret_count)
 449 {
 450         unsigned int i, count;
 451         unsigned int clu;
 452         struct exfat_sb_info *sbi = EXFAT_SB(sb);
 453
 454         if (!p_chain->dir || p_chain->dir == EXFAT_EOF_CLUSTER) {
 455                 *ret_count = 0;
 456                 return 0;
 457         }
 458
 459         if (p_chain->flags == ALLOC_NO_FAT_CHAIN) {
 460                 *ret_count = p_chain->size;
 461                 return 0;
 462         }
 463
 464         clu = p_chain->dir;
 465         count = 0;
 466         for (i = EXFAT_FIRST_CLUSTER; i < sbi->num_clusters; i++) {
 467                 count++;
 468                 if (exfat_ent_get(sb, clu, &clu))
 469                         return -EIO;
 470                 if (clu == EXFAT_EOF_CLUSTER)
 471                         break;
 472         }
 473
 474         *ret_count = count;
 475         return 0;
 476 }