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