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 int exfat_free_cluster(struct inode *inode, struct exfat_chain *p_chain)
 155 {
 156         unsigned int num_clusters = 0;
 157         unsigned int clu;
 158         struct super_block *sb = inode->i_sb;
 159         struct exfat_sb_info *sbi = EXFAT_SB(sb);
 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         if (p_chain->flags == ALLOC_NO_FAT_CHAIN) {
 180                 do {
 181                         exfat_clear_bitmap(inode, clu);
 182                         clu++;
 183
 184                         num_clusters++;
 185                 } while (num_clusters < p_chain->size);
 186         } else {
 187                 do {
 188                         exfat_clear_bitmap(inode, clu);
 189
 190                         if (exfat_get_next_cluster(sb, &clu))
 191                                 goto dec_used_clus;
 192
 193                         num_clusters++;
 194                 } while (clu != EXFAT_EOF_CLUSTER);
 195         }
 196
 197 dec_used_clus:
 198         sbi->used_clusters -= num_clusters;
 199         return 0;
 200 }
 201
 202 int exfat_find_last_cluster(struct super_block *sb, struct exfat_chain *p_chain,
 203                 unsigned int *ret_clu)
 204 {
 205         unsigned int clu, next;
 206         unsigned int count = 0;
 207
 208         next = p_chain->dir;
 209         if (p_chain->flags == ALLOC_NO_FAT_CHAIN) {
 210                 *ret_clu = next + p_chain->size - 1;
 211                 return 0;
 212         }
 213
 214         do {
 215                 count++;
 216                 clu = next;
 217                 if (exfat_ent_get(sb, clu, &next))
 218                         return -EIO;
 219         } while (next != EXFAT_EOF_CLUSTER);
 220
 221         if (p_chain->size != count) {
 222                 exfat_fs_error(sb,
 223                         "bogus directory size (clus : ondisk(%d) != counted(%d))",
 224                         p_chain->size, count);
 225                 return -EIO;
 226         }
 227
 228         *ret_clu = clu;
 229         return 0;
 230 }
 231
 232 int exfat_zeroed_cluster(struct inode *dir, unsigned int clu)
 233 {
 234         struct super_block *sb = dir->i_sb;
 235         struct exfat_sb_info *sbi = EXFAT_SB(sb);
 236         struct buffer_head *bhs[MAX_BUF_PER_PAGE];
 237         int nr_bhs = MAX_BUF_PER_PAGE;
 238         sector_t blknr, last_blknr;
 239         int err, i, n;
 240
 241         blknr = exfat_cluster_to_sector(sbi, clu);
 242         last_blknr = blknr + sbi->sect_per_clus;
 243
 244         if (last_blknr > sbi->num_sectors && sbi->num_sectors > 0) {
 245                 exfat_fs_error_ratelimit(sb,
 246                         "%s: out of range(sect:%llu len:%u)",
 247                         __func__, (unsigned long long)blknr,
 248                         sbi->sect_per_clus);
 249                 return -EIO;
 250         }
 251
 252         /* Zeroing the unused blocks on this cluster */
 253         while (blknr < last_blknr) {
 254                 for (n = 0; n < nr_bhs && blknr < last_blknr; n++, blknr++) {
 255                         bhs[n] = sb_getblk(sb, blknr);
 256                         if (!bhs[n]) {
 257                                 err = -ENOMEM;
 258                                 goto release_bhs;
 259                         }
 260                         memset(bhs[n]->b_data, 0, sb->s_blocksize);
 261                 }
 262
 263                 err = exfat_update_bhs(bhs, n, IS_DIRSYNC(dir));
 264                 if (err)
 265                         goto release_bhs;
 266
 267                 for (i = 0; i < n; i++)
 268                         brelse(bhs[i]);
 269         }
 270         return 0;
 271
 272 release_bhs:
 273         exfat_err(sb, "failed zeroed sect %llu\n", (unsigned long long)blknr);
 274         for (i = 0; i < n; i++)
 275                 bforget(bhs[i]);
 276         return err;
 277 }
 278
 279 int exfat_alloc_cluster(struct inode *inode, unsigned int num_alloc,
 280                 struct exfat_chain *p_chain)
 281 {
 282         int ret = -ENOSPC;
 283         unsigned int num_clusters = 0, total_cnt;
 284         unsigned int hint_clu, new_clu, last_clu = EXFAT_EOF_CLUSTER;
 285         struct super_block *sb = inode->i_sb;
 286         struct exfat_sb_info *sbi = EXFAT_SB(sb);
 287
 288         total_cnt = EXFAT_DATA_CLUSTER_COUNT(sbi);
 289
 290         if (unlikely(total_cnt < sbi->used_clusters)) {
 291                 exfat_fs_error_ratelimit(sb,
 292                         "%s: invalid used clusters(t:%u,u:%u)\n",
 293                         __func__, total_cnt, sbi->used_clusters);
 294                 return -EIO;
 295         }
 296
 297         if (num_alloc > total_cnt - sbi->used_clusters)
 298                 return -ENOSPC;
 299
 300         hint_clu = p_chain->dir;
 301         /* find new cluster */
 302         if (hint_clu == EXFAT_EOF_CLUSTER) {
 303                 if (sbi->clu_srch_ptr < EXFAT_FIRST_CLUSTER) {
 304                         exfat_err(sb, "sbi->clu_srch_ptr is invalid (%u)\n",
 305                                   sbi->clu_srch_ptr);
 306                         sbi->clu_srch_ptr = EXFAT_FIRST_CLUSTER;
 307                 }
 308
 309                 hint_clu = exfat_find_free_bitmap(sb, sbi->clu_srch_ptr);
 310                 if (hint_clu == EXFAT_EOF_CLUSTER)
 311                         return -ENOSPC;
 312         }
 313
 314         /* check cluster validation */
 315         if (!is_valid_cluster(sbi, hint_clu)) {
 316                 exfat_err(sb, "hint_cluster is invalid (%u)",
 317                         hint_clu);
 318                 hint_clu = EXFAT_FIRST_CLUSTER;
 319                 if (p_chain->flags == ALLOC_NO_FAT_CHAIN) {
 320                         if (exfat_chain_cont_cluster(sb, p_chain->dir,
 321                                         num_clusters))
 322                                 return -EIO;
 323                         p_chain->flags = ALLOC_FAT_CHAIN;
 324                 }
 325         }
 326
 327         p_chain->dir = EXFAT_EOF_CLUSTER;
 328
 329         while ((new_clu = exfat_find_free_bitmap(sb, hint_clu)) !=
 330                EXFAT_EOF_CLUSTER) {
 331                 if (new_clu != hint_clu &&
 332                     p_chain->flags == ALLOC_NO_FAT_CHAIN) {
 333                         if (exfat_chain_cont_cluster(sb, p_chain->dir,
 334                                         num_clusters)) {
 335                                 ret = -EIO;
 336                                 goto free_cluster;
 337                         }
 338                         p_chain->flags = ALLOC_FAT_CHAIN;
 339                 }
 340
 341                 /* update allocation bitmap */
 342                 if (exfat_set_bitmap(inode, new_clu)) {
 343                         ret = -EIO;
 344                         goto free_cluster;
 345                 }
 346
 347                 num_clusters++;
 348
 349                 /* update FAT table */
 350                 if (p_chain->flags == ALLOC_FAT_CHAIN) {
 351                         if (exfat_ent_set(sb, new_clu, EXFAT_EOF_CLUSTER)) {
 352                                 ret = -EIO;
 353                                 goto free_cluster;
 354                         }
 355                 }
 356
 357                 if (p_chain->dir == EXFAT_EOF_CLUSTER) {
 358                         p_chain->dir = new_clu;
 359                 } else if (p_chain->flags == ALLOC_FAT_CHAIN) {
 360                         if (exfat_ent_set(sb, last_clu, new_clu)) {
 361                                 ret = -EIO;
 362                                 goto free_cluster;
 363                         }
 364                 }
 365                 last_clu = new_clu;
 366
 367                 if (--num_alloc == 0) {
 368                         sbi->clu_srch_ptr = hint_clu;
 369                         sbi->used_clusters += num_clusters;
 370
 371                         p_chain->size += num_clusters;
 372                         return 0;
 373                 }
 374
 375                 hint_clu = new_clu + 1;
 376                 if (hint_clu >= sbi->num_clusters) {
 377                         hint_clu = EXFAT_FIRST_CLUSTER;
 378
 379                         if (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         }
 389 free_cluster:
 390         if (num_clusters)
 391                 exfat_free_cluster(inode, p_chain);
 392         return ret;
 393 }
 394
 395 int exfat_count_num_clusters(struct super_block *sb,
 396                 struct exfat_chain *p_chain, unsigned int *ret_count)
 397 {
 398         unsigned int i, count;
 399         unsigned int clu;
 400         struct exfat_sb_info *sbi = EXFAT_SB(sb);
 401
 402         if (!p_chain->dir || p_chain->dir == EXFAT_EOF_CLUSTER) {
 403                 *ret_count = 0;
 404                 return 0;
 405         }
 406
 407         if (p_chain->flags == ALLOC_NO_FAT_CHAIN) {
 408                 *ret_count = p_chain->size;
 409                 return 0;
 410         }
 411
 412         clu = p_chain->dir;
 413         count = 0;
 414         for (i = EXFAT_FIRST_CLUSTER; i < sbi->num_clusters; i++) {
 415                 count++;
 416                 if (exfat_ent_get(sb, clu, &clu))
 417                         return -EIO;
 418                 if (clu == EXFAT_EOF_CLUSTER)
 419                         break;
 420         }
 421
 422         *ret_count = count;
 423         return 0;
 424 }