fs/erofs/super.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2017-2018 HUAWEI, Inc.
   4  *             http://www.huawei.com/
   5  * Created by Gao Xiang <gaoxiang25@huawei.com>
   6  */
   7 #include <linux/module.h>
   8 #include <linux/buffer_head.h>
   9 #include <linux/statfs.h>
  10 #include <linux/parser.h>
  11 #include <linux/seq_file.h>
  12 #include <linux/crc32c.h>
  13 #include "xattr.h"
  14
  15 #define CREATE_TRACE_POINTS
  16 #include <trace/events/erofs.h>
  17
  18 static struct kmem_cache *erofs_inode_cachep __read_mostly;
  19
  20 void _erofs_err(struct super_block *sb, const char *function,
  21                 const char *fmt, ...)
  22 {
  23         struct va_format vaf;
  24         va_list args;
  25
  26         va_start(args, fmt);
  27
  28         vaf.fmt = fmt;
  29         vaf.va = &args;
  30
  31         pr_err("(device %s): %s: %pV", sb->s_id, function, &vaf);
  32         va_end(args);
  33 }
  34
  35 void _erofs_info(struct super_block *sb, const char *function,
  36                  const char *fmt, ...)
  37 {
  38         struct va_format vaf;
  39         va_list args;
  40
  41         va_start(args, fmt);
  42
  43         vaf.fmt = fmt;
  44         vaf.va = &args;
  45
  46         pr_info("(device %s): %pV", sb->s_id, &vaf);
  47         va_end(args);
  48 }
  49
  50 static int erofs_superblock_csum_verify(struct super_block *sb, void *sbdata)
  51 {
  52         struct erofs_super_block *dsb;
  53         u32 expected_crc, crc;
  54
  55         dsb = kmemdup(sbdata + EROFS_SUPER_OFFSET,
  56                       EROFS_BLKSIZ - EROFS_SUPER_OFFSET, GFP_KERNEL);
  57         if (!dsb)
  58                 return -ENOMEM;
  59
  60         expected_crc = le32_to_cpu(dsb->checksum);
  61         dsb->checksum = 0;
  62         /* to allow for x86 boot sectors and other oddities. */
  63         crc = crc32c(~0, dsb, EROFS_BLKSIZ - EROFS_SUPER_OFFSET);
  64         kfree(dsb);
  65
  66         if (crc != expected_crc) {
  67                 erofs_err(sb, "invalid checksum 0x%08x, 0x%08x expected",
  68                           crc, expected_crc);
  69                 return -EBADMSG;
  70         }
  71         return 0;
  72 }
  73
  74 static void erofs_inode_init_once(void *ptr)
  75 {
  76         struct erofs_inode *vi = ptr;
  77
  78         inode_init_once(&vi->vfs_inode);
  79 }
  80
  81 static struct inode *erofs_alloc_inode(struct super_block *sb)
  82 {
  83         struct erofs_inode *vi =
  84                 kmem_cache_alloc(erofs_inode_cachep, GFP_KERNEL);
  85
  86         if (!vi)
  87                 return NULL;
  88
  89         /* zero out everything except vfs_inode */
  90         memset(vi, 0, offsetof(struct erofs_inode, vfs_inode));
  91         return &vi->vfs_inode;
  92 }
  93
  94 static void erofs_free_inode(struct inode *inode)
  95 {
  96         struct erofs_inode *vi = EROFS_I(inode);
  97
  98         /* be careful of RCU symlink path */
  99         if (inode->i_op == &erofs_fast_symlink_iops)
 100                 kfree(inode->i_link);
 101         kfree(vi->xattr_shared_xattrs);
 102
 103         kmem_cache_free(erofs_inode_cachep, vi);
 104 }
 105
 106 static bool check_layout_compatibility(struct super_block *sb,
 107                                        struct erofs_super_block *dsb)
 108 {
 109         const unsigned int feature = le32_to_cpu(dsb->feature_incompat);
 110
 111         EROFS_SB(sb)->feature_incompat = feature;
 112
 113         /* check if current kernel meets all mandatory requirements */
 114         if (feature & (~EROFS_ALL_FEATURE_INCOMPAT)) {
 115                 erofs_err(sb,
 116                           "unidentified incompatible feature %x, please upgrade kernel version",
 117                            feature & ~EROFS_ALL_FEATURE_INCOMPAT);
 118                 return false;
 119         }
 120         return true;
 121 }
 122
 123 static int erofs_read_superblock(struct super_block *sb)
 124 {
 125         struct erofs_sb_info *sbi;
 126         struct page *page;
 127         struct erofs_super_block *dsb;
 128         unsigned int blkszbits;
 129         void *data;
 130         int ret;
 131
 132         page = read_mapping_page(sb->s_bdev->bd_inode->i_mapping, 0, NULL);
 133         if (IS_ERR(page)) {
 134                 erofs_err(sb, "cannot read erofs superblock");
 135                 return PTR_ERR(page);
 136         }
 137
 138         sbi = EROFS_SB(sb);
 139
 140         data = kmap(page);
 141         dsb = (struct erofs_super_block *)(data + EROFS_SUPER_OFFSET);
 142
 143         ret = -EINVAL;
 144         if (le32_to_cpu(dsb->magic) != EROFS_SUPER_MAGIC_V1) {
 145                 erofs_err(sb, "cannot find valid erofs superblock");
 146                 goto out;
 147         }
 148
 149         sbi->feature_compat = le32_to_cpu(dsb->feature_compat);
 150         if (sbi->feature_compat & EROFS_FEATURE_COMPAT_SB_CHKSUM) {
 151                 ret = erofs_superblock_csum_verify(sb, data);
 152                 if (ret)
 153                         goto out;
 154         }
 155
 156         blkszbits = dsb->blkszbits;
 157         /* 9(512 bytes) + LOG_SECTORS_PER_BLOCK == LOG_BLOCK_SIZE */
 158         if (blkszbits != LOG_BLOCK_SIZE) {
 159                 erofs_err(sb, "blksize %u isn't supported on this platform",
 160                           1 << blkszbits);
 161                 goto out;
 162         }
 163
 164         if (!check_layout_compatibility(sb, dsb))
 165                 goto out;
 166
 167         sbi->blocks = le32_to_cpu(dsb->blocks);
 168         sbi->meta_blkaddr = le32_to_cpu(dsb->meta_blkaddr);
 169 #ifdef CONFIG_EROFS_FS_XATTR
 170         sbi->xattr_blkaddr = le32_to_cpu(dsb->xattr_blkaddr);
 171 #endif
 172         sbi->islotbits = ilog2(sizeof(struct erofs_inode_compact));
 173         sbi->root_nid = le16_to_cpu(dsb->root_nid);
 174         sbi->inos = le64_to_cpu(dsb->inos);
 175
 176         sbi->build_time = le64_to_cpu(dsb->build_time);
 177         sbi->build_time_nsec = le32_to_cpu(dsb->build_time_nsec);
 178
 179         memcpy(&sb->s_uuid, dsb->uuid, sizeof(dsb->uuid));
 180
 181         ret = strscpy(sbi->volume_name, dsb->volume_name,
 182                       sizeof(dsb->volume_name));
 183         if (ret < 0) {  /* -E2BIG */
 184                 erofs_err(sb, "bad volume name without NIL terminator");
 185                 ret = -EFSCORRUPTED;
 186                 goto out;
 187         }
 188         ret = 0;
 189 out:
 190         kunmap(page);
 191         put_page(page);
 192         return ret;
 193 }
 194
 195 #ifdef CONFIG_EROFS_FS_ZIP
 196 static int erofs_build_cache_strategy(struct super_block *sb,
 197                                       substring_t *args)
 198 {
 199         struct erofs_sb_info *sbi = EROFS_SB(sb);
 200         const char *cs = match_strdup(args);
 201         int err = 0;
 202
 203         if (!cs) {
 204                 erofs_err(sb, "Not enough memory to store cache strategy");
 205                 return -ENOMEM;
 206         }
 207
 208         if (!strcmp(cs, "disabled")) {
 209                 sbi->cache_strategy = EROFS_ZIP_CACHE_DISABLED;
 210         } else if (!strcmp(cs, "readahead")) {
 211                 sbi->cache_strategy = EROFS_ZIP_CACHE_READAHEAD;
 212         } else if (!strcmp(cs, "readaround")) {
 213                 sbi->cache_strategy = EROFS_ZIP_CACHE_READAROUND;
 214         } else {
 215                 erofs_err(sb, "Unrecognized cache strategy \"%s\"", cs);
 216                 err = -EINVAL;
 217         }
 218         kfree(cs);
 219         return err;
 220 }
 221 #else
 222 static int erofs_build_cache_strategy(struct super_block *sb,
 223                                       substring_t *args)
 224 {
 225         erofs_info(sb, "EROFS compression is disabled, so cache strategy is ignored");
 226         return 0;
 227 }
 228 #endif
 229
 230 /* set up default EROFS parameters */
 231 static void erofs_default_options(struct erofs_sb_info *sbi)
 232 {
 233 #ifdef CONFIG_EROFS_FS_ZIP
 234         sbi->cache_strategy = EROFS_ZIP_CACHE_READAROUND;
 235         sbi->max_sync_decompress_pages = 3;
 236 #endif
 237 #ifdef CONFIG_EROFS_FS_XATTR
 238         set_opt(sbi, XATTR_USER);
 239 #endif
 240 #ifdef CONFIG_EROFS_FS_POSIX_ACL
 241         set_opt(sbi, POSIX_ACL);
 242 #endif
 243 }
 244
 245 enum {
 246         Opt_user_xattr,
 247         Opt_nouser_xattr,
 248         Opt_acl,
 249         Opt_noacl,
 250         Opt_cache_strategy,
 251         Opt_err
 252 };
 253
 254 static match_table_t erofs_tokens = {
 255         {Opt_user_xattr, "user_xattr"},
 256         {Opt_nouser_xattr, "nouser_xattr"},
 257         {Opt_acl, "acl"},
 258         {Opt_noacl, "noacl"},
 259         {Opt_cache_strategy, "cache_strategy=%s"},
 260         {Opt_err, NULL}
 261 };
 262
 263 static int erofs_parse_options(struct super_block *sb, char *options)
 264 {
 265         substring_t args[MAX_OPT_ARGS];
 266         char *p;
 267         int err;
 268
 269         if (!options)
 270                 return 0;
 271
 272         while ((p = strsep(&options, ","))) {
 273                 int token;
 274
 275                 if (!*p)
 276                         continue;
 277
 278                 args[0].to = args[0].from = NULL;
 279                 token = match_token(p, erofs_tokens, args);
 280
 281                 switch (token) {
 282 #ifdef CONFIG_EROFS_FS_XATTR
 283                 case Opt_user_xattr:
 284                         set_opt(EROFS_SB(sb), XATTR_USER);
 285                         break;
 286                 case Opt_nouser_xattr:
 287                         clear_opt(EROFS_SB(sb), XATTR_USER);
 288                         break;
 289 #else
 290                 case Opt_user_xattr:
 291                         erofs_info(sb, "user_xattr options not supported");
 292                         break;
 293                 case Opt_nouser_xattr:
 294                         erofs_info(sb, "nouser_xattr options not supported");
 295                         break;
 296 #endif
 297 #ifdef CONFIG_EROFS_FS_POSIX_ACL
 298                 case Opt_acl:
 299                         set_opt(EROFS_SB(sb), POSIX_ACL);
 300                         break;
 301                 case Opt_noacl:
 302                         clear_opt(EROFS_SB(sb), POSIX_ACL);
 303                         break;
 304 #else
 305                 case Opt_acl:
 306                         erofs_info(sb, "acl options not supported");
 307                         break;
 308                 case Opt_noacl:
 309                         erofs_info(sb, "noacl options not supported");
 310                         break;
 311 #endif
 312                 case Opt_cache_strategy:
 313                         err = erofs_build_cache_strategy(sb, args);
 314                         if (err)
 315                                 return err;
 316                         break;
 317                 default:
 318                         erofs_err(sb, "Unrecognized mount option \"%s\" or missing value", p);
 319                         return -EINVAL;
 320                 }
 321         }
 322         return 0;
 323 }
 324
 325 #ifdef CONFIG_EROFS_FS_ZIP
 326 static const struct address_space_operations managed_cache_aops;
 327
 328 static int erofs_managed_cache_releasepage(struct page *page, gfp_t gfp_mask)
 329 {
 330         int ret = 1;    /* 0 - busy */
 331         struct address_space *const mapping = page->mapping;
 332
 333         DBG_BUGON(!PageLocked(page));
 334         DBG_BUGON(mapping->a_ops != &managed_cache_aops);
 335
 336         if (PagePrivate(page))
 337                 ret = erofs_try_to_free_cached_page(mapping, page);
 338
 339         return ret;
 340 }
 341
 342 static void erofs_managed_cache_invalidatepage(struct page *page,
 343                                                unsigned int offset,
 344                                                unsigned int length)
 345 {
 346         const unsigned int stop = length + offset;
 347
 348         DBG_BUGON(!PageLocked(page));
 349
 350         /* Check for potential overflow in debug mode */
 351         DBG_BUGON(stop > PAGE_SIZE || stop < length);
 352
 353         if (offset == 0 && stop == PAGE_SIZE)
 354                 while (!erofs_managed_cache_releasepage(page, GFP_NOFS))
 355                         cond_resched();
 356 }
 357
 358 static const struct address_space_operations managed_cache_aops = {
 359         .releasepage = erofs_managed_cache_releasepage,
 360         .invalidatepage = erofs_managed_cache_invalidatepage,
 361 };
 362
 363 static int erofs_init_managed_cache(struct super_block *sb)
 364 {
 365         struct erofs_sb_info *const sbi = EROFS_SB(sb);
 366         struct inode *const inode = new_inode(sb);
 367
 368         if (!inode)
 369                 return -ENOMEM;
 370
 371         set_nlink(inode, 1);
 372         inode->i_size = OFFSET_MAX;
 373
 374         inode->i_mapping->a_ops = &managed_cache_aops;
 375         mapping_set_gfp_mask(inode->i_mapping,
 376                              GFP_NOFS | __GFP_HIGHMEM | __GFP_MOVABLE);
 377         sbi->managed_cache = inode;
 378         return 0;
 379 }
 380 #else
 381 static int erofs_init_managed_cache(struct super_block *sb) { return 0; }
 382 #endif
 383
 384 static int erofs_fill_super(struct super_block *sb, void *data, int silent)
 385 {
 386         struct inode *inode;
 387         struct erofs_sb_info *sbi;
 388         int err;
 389
 390         sb->s_magic = EROFS_SUPER_MAGIC;
 391
 392         if (!sb_set_blocksize(sb, EROFS_BLKSIZ)) {
 393                 erofs_err(sb, "failed to set erofs blksize");
 394                 return -EINVAL;
 395         }
 396
 397         sbi = kzalloc(sizeof(*sbi), GFP_KERNEL);
 398         if (!sbi)
 399                 return -ENOMEM;
 400
 401         sb->s_fs_info = sbi;
 402         err = erofs_read_superblock(sb);
 403         if (err)
 404                 return err;
 405
 406         sb->s_flags |= SB_RDONLY | SB_NOATIME;
 407         sb->s_maxbytes = MAX_LFS_FILESIZE;
 408         sb->s_time_gran = 1;
 409
 410         sb->s_op = &erofs_sops;
 411
 412 #ifdef CONFIG_EROFS_FS_XATTR
 413         sb->s_xattr = erofs_xattr_handlers;
 414 #endif
 415         /* set erofs default mount options */
 416         erofs_default_options(sbi);
 417
 418         err = erofs_parse_options(sb, data);
 419         if (err)
 420                 return err;
 421
 422         if (test_opt(sbi, POSIX_ACL))
 423                 sb->s_flags |= SB_POSIXACL;
 424         else
 425                 sb->s_flags &= ~SB_POSIXACL;
 426
 427 #ifdef CONFIG_EROFS_FS_ZIP
 428         INIT_RADIX_TREE(&sbi->workstn_tree, GFP_ATOMIC);
 429 #endif
 430
 431         /* get the root inode */
 432         inode = erofs_iget(sb, ROOT_NID(sbi), true);
 433         if (IS_ERR(inode))
 434                 return PTR_ERR(inode);
 435
 436         if (!S_ISDIR(inode->i_mode)) {
 437                 erofs_err(sb, "rootino(nid %llu) is not a directory(i_mode %o)",
 438                           ROOT_NID(sbi), inode->i_mode);
 439                 iput(inode);
 440                 return -EINVAL;
 441         }
 442
 443         sb->s_root = d_make_root(inode);
 444         if (!sb->s_root)
 445                 return -ENOMEM;
 446
 447         erofs_shrinker_register(sb);
 448         /* sb->s_umount is already locked, SB_ACTIVE and SB_BORN are not set */
 449         err = erofs_init_managed_cache(sb);
 450         if (err)
 451                 return err;
 452
 453         erofs_info(sb, "mounted with opts: %s, root inode @ nid %llu.",
 454                    (char *)data, ROOT_NID(sbi));
 455         return 0;
 456 }
 457
 458 static struct dentry *erofs_mount(struct file_system_type *fs_type, int flags,
 459                                   const char *dev_name, void *data)
 460 {
 461         return mount_bdev(fs_type, flags, dev_name, data, erofs_fill_super);
 462 }
 463
 464 /*
 465  * could be triggered after deactivate_locked_super()
 466  * is called, thus including umount and failed to initialize.
 467  */
 468 static void erofs_kill_sb(struct super_block *sb)
 469 {
 470         struct erofs_sb_info *sbi;
 471
 472         WARN_ON(sb->s_magic != EROFS_SUPER_MAGIC);
 473
 474         kill_block_super(sb);
 475
 476         sbi = EROFS_SB(sb);
 477         if (!sbi)
 478                 return;
 479         kfree(sbi);
 480         sb->s_fs_info = NULL;
 481 }
 482
 483 /* called when ->s_root is non-NULL */
 484 static void erofs_put_super(struct super_block *sb)
 485 {
 486         struct erofs_sb_info *const sbi = EROFS_SB(sb);
 487
 488         DBG_BUGON(!sbi);
 489
 490         erofs_shrinker_unregister(sb);
 491 #ifdef CONFIG_EROFS_FS_ZIP
 492         iput(sbi->managed_cache);
 493         sbi->managed_cache = NULL;
 494 #endif
 495 }
 496
 497 static struct file_system_type erofs_fs_type = {
 498         .owner          = THIS_MODULE,
 499         .name           = "erofs",
 500         .mount          = erofs_mount,
 501         .kill_sb        = erofs_kill_sb,
 502         .fs_flags       = FS_REQUIRES_DEV,
 503 };
 504 MODULE_ALIAS_FS("erofs");
 505
 506 static int __init erofs_module_init(void)
 507 {
 508         int err;
 509
 510         erofs_check_ondisk_layout_definitions();
 511
 512         erofs_inode_cachep = kmem_cache_create("erofs_inode",
 513                                                sizeof(struct erofs_inode), 0,
 514                                                SLAB_RECLAIM_ACCOUNT,
 515                                                erofs_inode_init_once);
 516         if (!erofs_inode_cachep) {
 517                 err = -ENOMEM;
 518                 goto icache_err;
 519         }
 520
 521         err = erofs_init_shrinker();
 522         if (err)
 523                 goto shrinker_err;
 524
 525         err = z_erofs_init_zip_subsystem();
 526         if (err)
 527                 goto zip_err;
 528
 529         err = register_filesystem(&erofs_fs_type);
 530         if (err)
 531                 goto fs_err;
 532
 533         return 0;
 534
 535 fs_err:
 536         z_erofs_exit_zip_subsystem();
 537 zip_err:
 538         erofs_exit_shrinker();
 539 shrinker_err:
 540         kmem_cache_destroy(erofs_inode_cachep);
 541 icache_err:
 542         return err;
 543 }
 544
 545 static void __exit erofs_module_exit(void)
 546 {
 547         unregister_filesystem(&erofs_fs_type);
 548         z_erofs_exit_zip_subsystem();
 549         erofs_exit_shrinker();
 550
 551         /* Ensure all RCU free inodes are safe before cache is destroyed. */
 552         rcu_barrier();
 553         kmem_cache_destroy(erofs_inode_cachep);
 554 }
 555
 556 /* get filesystem statistics */
 557 static int erofs_statfs(struct dentry *dentry, struct kstatfs *buf)
 558 {
 559         struct super_block *sb = dentry->d_sb;
 560         struct erofs_sb_info *sbi = EROFS_SB(sb);
 561         u64 id = huge_encode_dev(sb->s_bdev->bd_dev);
 562
 563         buf->f_type = sb->s_magic;
 564         buf->f_bsize = EROFS_BLKSIZ;
 565         buf->f_blocks = sbi->blocks;
 566         buf->f_bfree = buf->f_bavail = 0;
 567
 568         buf->f_files = ULLONG_MAX;
 569         buf->f_ffree = ULLONG_MAX - sbi->inos;
 570
 571         buf->f_namelen = EROFS_NAME_LEN;
 572
 573         buf->f_fsid.val[0] = (u32)id;
 574         buf->f_fsid.val[1] = (u32)(id >> 32);
 575         return 0;
 576 }
 577
 578 static int erofs_show_options(struct seq_file *seq, struct dentry *root)
 579 {
 580         struct erofs_sb_info *sbi __maybe_unused = EROFS_SB(root->d_sb);
 581
 582 #ifdef CONFIG_EROFS_FS_XATTR
 583         if (test_opt(sbi, XATTR_USER))
 584                 seq_puts(seq, ",user_xattr");
 585         else
 586                 seq_puts(seq, ",nouser_xattr");
 587 #endif
 588 #ifdef CONFIG_EROFS_FS_POSIX_ACL
 589         if (test_opt(sbi, POSIX_ACL))
 590                 seq_puts(seq, ",acl");
 591         else
 592                 seq_puts(seq, ",noacl");
 593 #endif
 594 #ifdef CONFIG_EROFS_FS_ZIP
 595         if (sbi->cache_strategy == EROFS_ZIP_CACHE_DISABLED) {
 596                 seq_puts(seq, ",cache_strategy=disabled");
 597         } else if (sbi->cache_strategy == EROFS_ZIP_CACHE_READAHEAD) {
 598                 seq_puts(seq, ",cache_strategy=readahead");
 599         } else if (sbi->cache_strategy == EROFS_ZIP_CACHE_READAROUND) {
 600                 seq_puts(seq, ",cache_strategy=readaround");
 601         }
 602 #endif
 603         return 0;
 604 }
 605
 606 static int erofs_remount(struct super_block *sb, int *flags, char *data)
 607 {
 608         struct erofs_sb_info *sbi = EROFS_SB(sb);
 609         unsigned int org_mnt_opt = sbi->mount_opt;
 610         int err;
 611
 612         DBG_BUGON(!sb_rdonly(sb));
 613         err = erofs_parse_options(sb, data);
 614         if (err)
 615                 goto out;
 616
 617         if (test_opt(sbi, POSIX_ACL))
 618                 sb->s_flags |= SB_POSIXACL;
 619         else
 620                 sb->s_flags &= ~SB_POSIXACL;
 621
 622         *flags |= SB_RDONLY;
 623         return 0;
 624 out:
 625         sbi->mount_opt = org_mnt_opt;
 626         return err;
 627 }
 628
 629 const struct super_operations erofs_sops = {
 630         .put_super = erofs_put_super,
 631         .alloc_inode = erofs_alloc_inode,
 632         .free_inode = erofs_free_inode,
 633         .statfs = erofs_statfs,
 634         .show_options = erofs_show_options,
 635         .remount_fs = erofs_remount,
 636 };
 637
 638 module_init(erofs_module_init);
 639 module_exit(erofs_module_exit);
 640
 641 MODULE_DESCRIPTION("Enhanced ROM File System");
 642 MODULE_AUTHOR("Gao Xiang, Chao Yu, Miao Xie, CONSUMER BG, HUAWEI Inc.");
 643 MODULE_LICENSE("GPL");
 644