1 /* 2 * Compressed rom filesystem for Linux. 3 * 4 * Copyright (C) 1999 Linus Torvalds. 5 * 6 * This file is released under the GPL. 7 */ 8 9 /* 10 * These are the VFS interfaces to the compressed rom filesystem. 11 * The actual compression is based on zlib, see the other files. 12 */ 13 14 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 15 16 #include <linux/module.h> 17 #include <linux/fs.h> 18 #include <linux/file.h> 19 #include <linux/pagemap.h> 20 #include <linux/pfn_t.h> 21 #include <linux/ramfs.h> 22 #include <linux/init.h> 23 #include <linux/string.h> 24 #include <linux/blkdev.h> 25 #include <linux/mtd/mtd.h> 26 #include <linux/mtd/super.h> 27 #include <linux/slab.h> 28 #include <linux/vfs.h> 29 #include <linux/mutex.h> 30 #include <uapi/linux/cramfs_fs.h> 31 #include <linux/uaccess.h> 32 33 #include "internal.h" 34 35 /* 36 * cramfs super-block data in memory 37 */ 38 struct cramfs_sb_info { 39 unsigned long magic; 40 unsigned long size; 41 unsigned long blocks; 42 unsigned long files; 43 unsigned long flags; 44 void *linear_virt_addr; 45 resource_size_t linear_phys_addr; 46 size_t mtd_point_size; 47 }; 48 49 static inline struct cramfs_sb_info *CRAMFS_SB(struct super_block *sb) 50 { 51 return sb->s_fs_info; 52 } 53 54 static const struct super_operations cramfs_ops; 55 static const struct inode_operations cramfs_dir_inode_operations; 56 static const struct file_operations cramfs_directory_operations; 57 static const struct file_operations cramfs_physmem_fops; 58 static const struct address_space_operations cramfs_aops; 59 60 static DEFINE_MUTEX(read_mutex); 61 62 63 /* These macros may change in future, to provide better st_ino semantics. */ 64 #define OFFSET(x) ((x)->i_ino) 65 66 static unsigned long cramino(const struct cramfs_inode *cino, unsigned int offset) 67 { 68 if (!cino->offset) 69 return offset + 1; 70 if (!cino->size) 71 return offset + 1; 72 73 /* 74 * The file mode test fixes buggy mkcramfs implementations where 75 * cramfs_inode->offset is set to a non zero value for entries 76 * which did not contain data, like devices node and fifos. 77 */ 78 switch (cino->mode & S_IFMT) { 79 case S_IFREG: 80 case S_IFDIR: 81 case S_IFLNK: 82 return cino->offset << 2; 83 default: 84 break; 85 } 86 return offset + 1; 87 } 88 89 static struct inode *get_cramfs_inode(struct super_block *sb, 90 const struct cramfs_inode *cramfs_inode, unsigned int offset) 91 { 92 struct inode *inode; 93 static struct timespec64 zerotime; 94 95 inode = iget_locked(sb, cramino(cramfs_inode, offset)); 96 if (!inode) 97 return ERR_PTR(-ENOMEM); 98 if (!(inode->i_state & I_NEW)) 99 return inode; 100 101 switch (cramfs_inode->mode & S_IFMT) { 102 case S_IFREG: 103 inode->i_fop = &generic_ro_fops; 104 inode->i_data.a_ops = &cramfs_aops; 105 if (IS_ENABLED(CONFIG_CRAMFS_MTD) && 106 CRAMFS_SB(sb)->flags & CRAMFS_FLAG_EXT_BLOCK_POINTERS && 107 CRAMFS_SB(sb)->linear_phys_addr) 108 inode->i_fop = &cramfs_physmem_fops; 109 break; 110 case S_IFDIR: 111 inode->i_op = &cramfs_dir_inode_operations; 112 inode->i_fop = &cramfs_directory_operations; 113 break; 114 case S_IFLNK: 115 inode->i_op = &page_symlink_inode_operations; 116 inode_nohighmem(inode); 117 inode->i_data.a_ops = &cramfs_aops; 118 break; 119 default: 120 init_special_inode(inode, cramfs_inode->mode, 121 old_decode_dev(cramfs_inode->size)); 122 } 123 124 inode->i_mode = cramfs_inode->mode; 125 i_uid_write(inode, cramfs_inode->uid); 126 i_gid_write(inode, cramfs_inode->gid); 127 128 /* if the lower 2 bits are zero, the inode contains data */ 129 if (!(inode->i_ino & 3)) { 130 inode->i_size = cramfs_inode->size; 131 inode->i_blocks = (cramfs_inode->size - 1) / 512 + 1; 132 } 133 134 /* Struct copy intentional */ 135 inode->i_mtime = inode->i_atime = inode->i_ctime = zerotime; 136 /* inode->i_nlink is left 1 - arguably wrong for directories, 137 but it's the best we can do without reading the directory 138 contents. 1 yields the right result in GNU find, even 139 without -noleaf option. */ 140 141 unlock_new_inode(inode); 142 143 return inode; 144 } 145 146 /* 147 * We have our own block cache: don't fill up the buffer cache 148 * with the rom-image, because the way the filesystem is set 149 * up the accesses should be fairly regular and cached in the 150 * page cache and dentry tree anyway.. 151 * 152 * This also acts as a way to guarantee contiguous areas of up to 153 * BLKS_PER_BUF*PAGE_SIZE, so that the caller doesn't need to 154 * worry about end-of-buffer issues even when decompressing a full 155 * page cache. 156 * 157 * Note: This is all optimized away at compile time when 158 * CONFIG_CRAMFS_BLOCKDEV=n. 159 */ 160 #define READ_BUFFERS (2) 161 /* NEXT_BUFFER(): Loop over [0..(READ_BUFFERS-1)]. */ 162 #define NEXT_BUFFER(_ix) ((_ix) ^ 1) 163 164 /* 165 * BLKS_PER_BUF_SHIFT should be at least 2 to allow for "compressed" 166 * data that takes up more space than the original and with unlucky 167 * alignment. 168 */ 169 #define BLKS_PER_BUF_SHIFT (2) 170 #define BLKS_PER_BUF (1 << BLKS_PER_BUF_SHIFT) 171 #define BUFFER_SIZE (BLKS_PER_BUF*PAGE_SIZE) 172 173 static unsigned char read_buffers[READ_BUFFERS][BUFFER_SIZE]; 174 static unsigned buffer_blocknr[READ_BUFFERS]; 175 static struct super_block *buffer_dev[READ_BUFFERS]; 176 static int next_buffer; 177 178 /* 179 * Populate our block cache and return a pointer to it. 180 */ 181 static void *cramfs_blkdev_read(struct super_block *sb, unsigned int offset, 182 unsigned int len) 183 { 184 struct address_space *mapping = sb->s_bdev->bd_inode->i_mapping; 185 struct page *pages[BLKS_PER_BUF]; 186 unsigned i, blocknr, buffer; 187 unsigned long devsize; 188 char *data; 189 190 if (!len) 191 return NULL; 192 blocknr = offset >> PAGE_SHIFT; 193 offset &= PAGE_SIZE - 1; 194 195 /* Check if an existing buffer already has the data.. */ 196 for (i = 0; i < READ_BUFFERS; i++) { 197 unsigned int blk_offset; 198 199 if (buffer_dev[i] != sb) 200 continue; 201 if (blocknr < buffer_blocknr[i]) 202 continue; 203 blk_offset = (blocknr - buffer_blocknr[i]) << PAGE_SHIFT; 204 blk_offset += offset; 205 if (blk_offset > BUFFER_SIZE || 206 blk_offset + len > BUFFER_SIZE) 207 continue; 208 return read_buffers[i] + blk_offset; 209 } 210 211 devsize = mapping->host->i_size >> PAGE_SHIFT; 212 213 /* Ok, read in BLKS_PER_BUF pages completely first. */ 214 for (i = 0; i < BLKS_PER_BUF; i++) { 215 struct page *page = NULL; 216 217 if (blocknr + i < devsize) { 218 page = read_mapping_page(mapping, blocknr + i, NULL); 219 /* synchronous error? */ 220 if (IS_ERR(page)) 221 page = NULL; 222 } 223 pages[i] = page; 224 } 225 226 for (i = 0; i < BLKS_PER_BUF; i++) { 227 struct page *page = pages[i]; 228 229 if (page) { 230 wait_on_page_locked(page); 231 if (!PageUptodate(page)) { 232 /* asynchronous error */ 233 put_page(page); 234 pages[i] = NULL; 235 } 236 } 237 } 238 239 buffer = next_buffer; 240 next_buffer = NEXT_BUFFER(buffer); 241 buffer_blocknr[buffer] = blocknr; 242 buffer_dev[buffer] = sb; 243 244 data = read_buffers[buffer]; 245 for (i = 0; i < BLKS_PER_BUF; i++) { 246 struct page *page = pages[i]; 247 248 if (page) { 249 memcpy(data, kmap(page), PAGE_SIZE); 250 kunmap(page); 251 put_page(page); 252 } else 253 memset(data, 0, PAGE_SIZE); 254 data += PAGE_SIZE; 255 } 256 return read_buffers[buffer] + offset; 257 } 258 259 /* 260 * Return a pointer to the linearly addressed cramfs image in memory. 261 */ 262 static void *cramfs_direct_read(struct super_block *sb, unsigned int offset, 263 unsigned int len) 264 { 265 struct cramfs_sb_info *sbi = CRAMFS_SB(sb); 266 267 if (!len) 268 return NULL; 269 if (len > sbi->size || offset > sbi->size - len) 270 return page_address(ZERO_PAGE(0)); 271 return sbi->linear_virt_addr + offset; 272 } 273 274 /* 275 * Returns a pointer to a buffer containing at least LEN bytes of 276 * filesystem starting at byte offset OFFSET into the filesystem. 277 */ 278 static void *cramfs_read(struct super_block *sb, unsigned int offset, 279 unsigned int len) 280 { 281 struct cramfs_sb_info *sbi = CRAMFS_SB(sb); 282 283 if (IS_ENABLED(CONFIG_CRAMFS_MTD) && sbi->linear_virt_addr) 284 return cramfs_direct_read(sb, offset, len); 285 else if (IS_ENABLED(CONFIG_CRAMFS_BLOCKDEV)) 286 return cramfs_blkdev_read(sb, offset, len); 287 else 288 return NULL; 289 } 290 291 /* 292 * For a mapping to be possible, we need a range of uncompressed and 293 * contiguous blocks. Return the offset for the first block and number of 294 * valid blocks for which that is true, or zero otherwise. 295 */ 296 static u32 cramfs_get_block_range(struct inode *inode, u32 pgoff, u32 *pages) 297 { 298 struct cramfs_sb_info *sbi = CRAMFS_SB(inode->i_sb); 299 int i; 300 u32 *blockptrs, first_block_addr; 301 302 /* 303 * We can dereference memory directly here as this code may be 304 * reached only when there is a direct filesystem image mapping 305 * available in memory. 306 */ 307 blockptrs = (u32 *)(sbi->linear_virt_addr + OFFSET(inode) + pgoff * 4); 308 first_block_addr = blockptrs[0] & ~CRAMFS_BLK_FLAGS; 309 i = 0; 310 do { 311 u32 block_off = i * (PAGE_SIZE >> CRAMFS_BLK_DIRECT_PTR_SHIFT); 312 u32 expect = (first_block_addr + block_off) | 313 CRAMFS_BLK_FLAG_DIRECT_PTR | 314 CRAMFS_BLK_FLAG_UNCOMPRESSED; 315 if (blockptrs[i] != expect) { 316 pr_debug("range: block %d/%d got %#x expects %#x\n", 317 pgoff+i, pgoff + *pages - 1, 318 blockptrs[i], expect); 319 if (i == 0) 320 return 0; 321 break; 322 } 323 } while (++i < *pages); 324 325 *pages = i; 326 return first_block_addr << CRAMFS_BLK_DIRECT_PTR_SHIFT; 327 } 328 329 #ifdef CONFIG_MMU 330 331 /* 332 * Return true if the last page of a file in the filesystem image contains 333 * some other data that doesn't belong to that file. It is assumed that the 334 * last block is CRAMFS_BLK_FLAG_DIRECT_PTR | CRAMFS_BLK_FLAG_UNCOMPRESSED 335 * (verified by cramfs_get_block_range() and directly accessible in memory. 336 */ 337 static bool cramfs_last_page_is_shared(struct inode *inode) 338 { 339 struct cramfs_sb_info *sbi = CRAMFS_SB(inode->i_sb); 340 u32 partial, last_page, blockaddr, *blockptrs; 341 char *tail_data; 342 343 partial = offset_in_page(inode->i_size); 344 if (!partial) 345 return false; 346 last_page = inode->i_size >> PAGE_SHIFT; 347 blockptrs = (u32 *)(sbi->linear_virt_addr + OFFSET(inode)); 348 blockaddr = blockptrs[last_page] & ~CRAMFS_BLK_FLAGS; 349 blockaddr <<= CRAMFS_BLK_DIRECT_PTR_SHIFT; 350 tail_data = sbi->linear_virt_addr + blockaddr + partial; 351 return memchr_inv(tail_data, 0, PAGE_SIZE - partial) ? true : false; 352 } 353 354 static int cramfs_physmem_mmap(struct file *file, struct vm_area_struct *vma) 355 { 356 struct inode *inode = file_inode(file); 357 struct cramfs_sb_info *sbi = CRAMFS_SB(inode->i_sb); 358 unsigned int pages, max_pages, offset; 359 unsigned long address, pgoff = vma->vm_pgoff; 360 char *bailout_reason; 361 int ret; 362 363 ret = generic_file_readonly_mmap(file, vma); 364 if (ret) 365 return ret; 366 367 /* 368 * Now try to pre-populate ptes for this vma with a direct 369 * mapping avoiding memory allocation when possible. 370 */ 371 372 /* Could COW work here? */ 373 bailout_reason = "vma is writable"; 374 if (vma->vm_flags & VM_WRITE) 375 goto bailout; 376 377 max_pages = (inode->i_size + PAGE_SIZE - 1) >> PAGE_SHIFT; 378 bailout_reason = "beyond file limit"; 379 if (pgoff >= max_pages) 380 goto bailout; 381 pages = min(vma_pages(vma), max_pages - pgoff); 382 383 offset = cramfs_get_block_range(inode, pgoff, &pages); 384 bailout_reason = "unsuitable block layout"; 385 if (!offset) 386 goto bailout; 387 address = sbi->linear_phys_addr + offset; 388 bailout_reason = "data is not page aligned"; 389 if (!PAGE_ALIGNED(address)) 390 goto bailout; 391 392 /* Don't map the last page if it contains some other data */ 393 if (pgoff + pages == max_pages && cramfs_last_page_is_shared(inode)) { 394 pr_debug("mmap: %s: last page is shared\n", 395 file_dentry(file)->d_name.name); 396 pages--; 397 } 398 399 if (!pages) { 400 bailout_reason = "no suitable block remaining"; 401 goto bailout; 402 } 403 404 if (pages == vma_pages(vma)) { 405 /* 406 * The entire vma is mappable. remap_pfn_range() will 407 * make it distinguishable from a non-direct mapping 408 * in /proc/<pid>/maps by substituting the file offset 409 * with the actual physical address. 410 */ 411 ret = remap_pfn_range(vma, vma->vm_start, address >> PAGE_SHIFT, 412 pages * PAGE_SIZE, vma->vm_page_prot); 413 } else { 414 /* 415 * Let's create a mixed map if we can't map it all. 416 * The normal paging machinery will take care of the 417 * unpopulated ptes via cramfs_readpage(). 418 */ 419 int i; 420 vma->vm_flags |= VM_MIXEDMAP; 421 for (i = 0; i < pages && !ret; i++) { 422 vm_fault_t vmf; 423 unsigned long off = i * PAGE_SIZE; 424 pfn_t pfn = phys_to_pfn_t(address + off, PFN_DEV); 425 vmf = vmf_insert_mixed(vma, vma->vm_start + off, pfn); 426 if (vmf & VM_FAULT_ERROR) 427 ret = vm_fault_to_errno(vmf, 0); 428 } 429 } 430 431 if (!ret) 432 pr_debug("mapped %s[%lu] at 0x%08lx (%u/%lu pages) " 433 "to vma 0x%08lx, page_prot 0x%llx\n", 434 file_dentry(file)->d_name.name, pgoff, 435 address, pages, vma_pages(vma), vma->vm_start, 436 (unsigned long long)pgprot_val(vma->vm_page_prot)); 437 return ret; 438 439 bailout: 440 pr_debug("%s[%lu]: direct mmap impossible: %s\n", 441 file_dentry(file)->d_name.name, pgoff, bailout_reason); 442 /* Didn't manage any direct map, but normal paging is still possible */ 443 return 0; 444 } 445 446 #else /* CONFIG_MMU */ 447 448 static int cramfs_physmem_mmap(struct file *file, struct vm_area_struct *vma) 449 { 450 return vma->vm_flags & (VM_SHARED | VM_MAYSHARE) ? 0 : -ENOSYS; 451 } 452 453 static unsigned long cramfs_physmem_get_unmapped_area(struct file *file, 454 unsigned long addr, unsigned long len, 455 unsigned long pgoff, unsigned long flags) 456 { 457 struct inode *inode = file_inode(file); 458 struct super_block *sb = inode->i_sb; 459 struct cramfs_sb_info *sbi = CRAMFS_SB(sb); 460 unsigned int pages, block_pages, max_pages, offset; 461 462 pages = (len + PAGE_SIZE - 1) >> PAGE_SHIFT; 463 max_pages = (inode->i_size + PAGE_SIZE - 1) >> PAGE_SHIFT; 464 if (pgoff >= max_pages || pages > max_pages - pgoff) 465 return -EINVAL; 466 block_pages = pages; 467 offset = cramfs_get_block_range(inode, pgoff, &block_pages); 468 if (!offset || block_pages != pages) 469 return -ENOSYS; 470 addr = sbi->linear_phys_addr + offset; 471 pr_debug("get_unmapped for %s ofs %#lx siz %lu at 0x%08lx\n", 472 file_dentry(file)->d_name.name, pgoff*PAGE_SIZE, len, addr); 473 return addr; 474 } 475 476 static unsigned int cramfs_physmem_mmap_capabilities(struct file *file) 477 { 478 return NOMMU_MAP_COPY | NOMMU_MAP_DIRECT | 479 NOMMU_MAP_READ | NOMMU_MAP_EXEC; 480 } 481 482 #endif /* CONFIG_MMU */ 483 484 static const struct file_operations cramfs_physmem_fops = { 485 .llseek = generic_file_llseek, 486 .read_iter = generic_file_read_iter, 487 .splice_read = generic_file_splice_read, 488 .mmap = cramfs_physmem_mmap, 489 #ifndef CONFIG_MMU 490 .get_unmapped_area = cramfs_physmem_get_unmapped_area, 491 .mmap_capabilities = cramfs_physmem_mmap_capabilities, 492 #endif 493 }; 494 495 static void cramfs_kill_sb(struct super_block *sb) 496 { 497 struct cramfs_sb_info *sbi = CRAMFS_SB(sb); 498 499 if (IS_ENABLED(CONFIG_CRAMFS_MTD) && sb->s_mtd) { 500 if (sbi && sbi->mtd_point_size) 501 mtd_unpoint(sb->s_mtd, 0, sbi->mtd_point_size); 502 kill_mtd_super(sb); 503 } else if (IS_ENABLED(CONFIG_CRAMFS_BLOCKDEV) && sb->s_bdev) { 504 kill_block_super(sb); 505 } 506 kfree(sbi); 507 } 508 509 static int cramfs_remount(struct super_block *sb, int *flags, char *data) 510 { 511 sync_filesystem(sb); 512 *flags |= SB_RDONLY; 513 return 0; 514 } 515 516 static int cramfs_read_super(struct super_block *sb, 517 struct cramfs_super *super, int silent) 518 { 519 struct cramfs_sb_info *sbi = CRAMFS_SB(sb); 520 unsigned long root_offset; 521 522 /* We don't know the real size yet */ 523 sbi->size = PAGE_SIZE; 524 525 /* Read the first block and get the superblock from it */ 526 mutex_lock(&read_mutex); 527 memcpy(super, cramfs_read(sb, 0, sizeof(*super)), sizeof(*super)); 528 mutex_unlock(&read_mutex); 529 530 /* Do sanity checks on the superblock */ 531 if (super->magic != CRAMFS_MAGIC) { 532 /* check for wrong endianness */ 533 if (super->magic == CRAMFS_MAGIC_WEND) { 534 if (!silent) 535 pr_err("wrong endianness\n"); 536 return -EINVAL; 537 } 538 539 /* check at 512 byte offset */ 540 mutex_lock(&read_mutex); 541 memcpy(super, 542 cramfs_read(sb, 512, sizeof(*super)), 543 sizeof(*super)); 544 mutex_unlock(&read_mutex); 545 if (super->magic != CRAMFS_MAGIC) { 546 if (super->magic == CRAMFS_MAGIC_WEND && !silent) 547 pr_err("wrong endianness\n"); 548 else if (!silent) 549 pr_err("wrong magic\n"); 550 return -EINVAL; 551 } 552 } 553 554 /* get feature flags first */ 555 if (super->flags & ~CRAMFS_SUPPORTED_FLAGS) { 556 pr_err("unsupported filesystem features\n"); 557 return -EINVAL; 558 } 559 560 /* Check that the root inode is in a sane state */ 561 if (!S_ISDIR(super->root.mode)) { 562 pr_err("root is not a directory\n"); 563 return -EINVAL; 564 } 565 /* correct strange, hard-coded permissions of mkcramfs */ 566 super->root.mode |= 0555; 567 568 root_offset = super->root.offset << 2; 569 if (super->flags & CRAMFS_FLAG_FSID_VERSION_2) { 570 sbi->size = super->size; 571 sbi->blocks = super->fsid.blocks; 572 sbi->files = super->fsid.files; 573 } else { 574 sbi->size = 1<<28; 575 sbi->blocks = 0; 576 sbi->files = 0; 577 } 578 sbi->magic = super->magic; 579 sbi->flags = super->flags; 580 if (root_offset == 0) 581 pr_info("empty filesystem"); 582 else if (!(super->flags & CRAMFS_FLAG_SHIFTED_ROOT_OFFSET) && 583 ((root_offset != sizeof(struct cramfs_super)) && 584 (root_offset != 512 + sizeof(struct cramfs_super)))) 585 { 586 pr_err("bad root offset %lu\n", root_offset); 587 return -EINVAL; 588 } 589 590 return 0; 591 } 592 593 static int cramfs_finalize_super(struct super_block *sb, 594 struct cramfs_inode *cramfs_root) 595 { 596 struct inode *root; 597 598 /* Set it all up.. */ 599 sb->s_flags |= SB_RDONLY; 600 sb->s_op = &cramfs_ops; 601 root = get_cramfs_inode(sb, cramfs_root, 0); 602 if (IS_ERR(root)) 603 return PTR_ERR(root); 604 sb->s_root = d_make_root(root); 605 if (!sb->s_root) 606 return -ENOMEM; 607 return 0; 608 } 609 610 static int cramfs_blkdev_fill_super(struct super_block *sb, void *data, 611 int silent) 612 { 613 struct cramfs_sb_info *sbi; 614 struct cramfs_super super; 615 int i, err; 616 617 sbi = kzalloc(sizeof(struct cramfs_sb_info), GFP_KERNEL); 618 if (!sbi) 619 return -ENOMEM; 620 sb->s_fs_info = sbi; 621 622 /* Invalidate the read buffers on mount: think disk change.. */ 623 for (i = 0; i < READ_BUFFERS; i++) 624 buffer_blocknr[i] = -1; 625 626 err = cramfs_read_super(sb, &super, silent); 627 if (err) 628 return err; 629 return cramfs_finalize_super(sb, &super.root); 630 } 631 632 static int cramfs_mtd_fill_super(struct super_block *sb, void *data, 633 int silent) 634 { 635 struct cramfs_sb_info *sbi; 636 struct cramfs_super super; 637 int err; 638 639 sbi = kzalloc(sizeof(struct cramfs_sb_info), GFP_KERNEL); 640 if (!sbi) 641 return -ENOMEM; 642 sb->s_fs_info = sbi; 643 644 /* Map only one page for now. Will remap it when fs size is known. */ 645 err = mtd_point(sb->s_mtd, 0, PAGE_SIZE, &sbi->mtd_point_size, 646 &sbi->linear_virt_addr, &sbi->linear_phys_addr); 647 if (err || sbi->mtd_point_size != PAGE_SIZE) { 648 pr_err("unable to get direct memory access to mtd:%s\n", 649 sb->s_mtd->name); 650 return err ? : -ENODATA; 651 } 652 653 pr_info("checking physical address %pap for linear cramfs image\n", 654 &sbi->linear_phys_addr); 655 err = cramfs_read_super(sb, &super, silent); 656 if (err) 657 return err; 658 659 /* Remap the whole filesystem now */ 660 pr_info("linear cramfs image on mtd:%s appears to be %lu KB in size\n", 661 sb->s_mtd->name, sbi->size/1024); 662 mtd_unpoint(sb->s_mtd, 0, PAGE_SIZE); 663 err = mtd_point(sb->s_mtd, 0, sbi->size, &sbi->mtd_point_size, 664 &sbi->linear_virt_addr, &sbi->linear_phys_addr); 665 if (err || sbi->mtd_point_size != sbi->size) { 666 pr_err("unable to get direct memory access to mtd:%s\n", 667 sb->s_mtd->name); 668 return err ? : -ENODATA; 669 } 670 671 return cramfs_finalize_super(sb, &super.root); 672 } 673 674 static int cramfs_statfs(struct dentry *dentry, struct kstatfs *buf) 675 { 676 struct super_block *sb = dentry->d_sb; 677 u64 id = 0; 678 679 if (sb->s_bdev) 680 id = huge_encode_dev(sb->s_bdev->bd_dev); 681 else if (sb->s_dev) 682 id = huge_encode_dev(sb->s_dev); 683 684 buf->f_type = CRAMFS_MAGIC; 685 buf->f_bsize = PAGE_SIZE; 686 buf->f_blocks = CRAMFS_SB(sb)->blocks; 687 buf->f_bfree = 0; 688 buf->f_bavail = 0; 689 buf->f_files = CRAMFS_SB(sb)->files; 690 buf->f_ffree = 0; 691 buf->f_fsid.val[0] = (u32)id; 692 buf->f_fsid.val[1] = (u32)(id >> 32); 693 buf->f_namelen = CRAMFS_MAXPATHLEN; 694 return 0; 695 } 696 697 /* 698 * Read a cramfs directory entry. 699 */ 700 static int cramfs_readdir(struct file *file, struct dir_context *ctx) 701 { 702 struct inode *inode = file_inode(file); 703 struct super_block *sb = inode->i_sb; 704 char *buf; 705 unsigned int offset; 706 707 /* Offset within the thing. */ 708 if (ctx->pos >= inode->i_size) 709 return 0; 710 offset = ctx->pos; 711 /* Directory entries are always 4-byte aligned */ 712 if (offset & 3) 713 return -EINVAL; 714 715 buf = kmalloc(CRAMFS_MAXPATHLEN, GFP_KERNEL); 716 if (!buf) 717 return -ENOMEM; 718 719 while (offset < inode->i_size) { 720 struct cramfs_inode *de; 721 unsigned long nextoffset; 722 char *name; 723 ino_t ino; 724 umode_t mode; 725 int namelen; 726 727 mutex_lock(&read_mutex); 728 de = cramfs_read(sb, OFFSET(inode) + offset, sizeof(*de)+CRAMFS_MAXPATHLEN); 729 name = (char *)(de+1); 730 731 /* 732 * Namelengths on disk are shifted by two 733 * and the name padded out to 4-byte boundaries 734 * with zeroes. 735 */ 736 namelen = de->namelen << 2; 737 memcpy(buf, name, namelen); 738 ino = cramino(de, OFFSET(inode) + offset); 739 mode = de->mode; 740 mutex_unlock(&read_mutex); 741 nextoffset = offset + sizeof(*de) + namelen; 742 for (;;) { 743 if (!namelen) { 744 kfree(buf); 745 return -EIO; 746 } 747 if (buf[namelen-1]) 748 break; 749 namelen--; 750 } 751 if (!dir_emit(ctx, buf, namelen, ino, mode >> 12)) 752 break; 753 754 ctx->pos = offset = nextoffset; 755 } 756 kfree(buf); 757 return 0; 758 } 759 760 /* 761 * Lookup and fill in the inode data.. 762 */ 763 static struct dentry *cramfs_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags) 764 { 765 unsigned int offset = 0; 766 struct inode *inode = NULL; 767 int sorted; 768 769 mutex_lock(&read_mutex); 770 sorted = CRAMFS_SB(dir->i_sb)->flags & CRAMFS_FLAG_SORTED_DIRS; 771 while (offset < dir->i_size) { 772 struct cramfs_inode *de; 773 char *name; 774 int namelen, retval; 775 int dir_off = OFFSET(dir) + offset; 776 777 de = cramfs_read(dir->i_sb, dir_off, sizeof(*de)+CRAMFS_MAXPATHLEN); 778 name = (char *)(de+1); 779 780 /* Try to take advantage of sorted directories */ 781 if (sorted && (dentry->d_name.name[0] < name[0])) 782 break; 783 784 namelen = de->namelen << 2; 785 offset += sizeof(*de) + namelen; 786 787 /* Quick check that the name is roughly the right length */ 788 if (((dentry->d_name.len + 3) & ~3) != namelen) 789 continue; 790 791 for (;;) { 792 if (!namelen) { 793 inode = ERR_PTR(-EIO); 794 goto out; 795 } 796 if (name[namelen-1]) 797 break; 798 namelen--; 799 } 800 if (namelen != dentry->d_name.len) 801 continue; 802 retval = memcmp(dentry->d_name.name, name, namelen); 803 if (retval > 0) 804 continue; 805 if (!retval) { 806 inode = get_cramfs_inode(dir->i_sb, de, dir_off); 807 break; 808 } 809 /* else (retval < 0) */ 810 if (sorted) 811 break; 812 } 813 out: 814 mutex_unlock(&read_mutex); 815 return d_splice_alias(inode, dentry); 816 } 817 818 static int cramfs_readpage(struct file *file, struct page *page) 819 { 820 struct inode *inode = page->mapping->host; 821 u32 maxblock; 822 int bytes_filled; 823 void *pgdata; 824 825 maxblock = (inode->i_size + PAGE_SIZE - 1) >> PAGE_SHIFT; 826 bytes_filled = 0; 827 pgdata = kmap(page); 828 829 if (page->index < maxblock) { 830 struct super_block *sb = inode->i_sb; 831 u32 blkptr_offset = OFFSET(inode) + page->index * 4; 832 u32 block_ptr, block_start, block_len; 833 bool uncompressed, direct; 834 835 mutex_lock(&read_mutex); 836 block_ptr = *(u32 *) cramfs_read(sb, blkptr_offset, 4); 837 uncompressed = (block_ptr & CRAMFS_BLK_FLAG_UNCOMPRESSED); 838 direct = (block_ptr & CRAMFS_BLK_FLAG_DIRECT_PTR); 839 block_ptr &= ~CRAMFS_BLK_FLAGS; 840 841 if (direct) { 842 /* 843 * The block pointer is an absolute start pointer, 844 * shifted by 2 bits. The size is included in the 845 * first 2 bytes of the data block when compressed, 846 * or PAGE_SIZE otherwise. 847 */ 848 block_start = block_ptr << CRAMFS_BLK_DIRECT_PTR_SHIFT; 849 if (uncompressed) { 850 block_len = PAGE_SIZE; 851 /* if last block: cap to file length */ 852 if (page->index == maxblock - 1) 853 block_len = 854 offset_in_page(inode->i_size); 855 } else { 856 block_len = *(u16 *) 857 cramfs_read(sb, block_start, 2); 858 block_start += 2; 859 } 860 } else { 861 /* 862 * The block pointer indicates one past the end of 863 * the current block (start of next block). If this 864 * is the first block then it starts where the block 865 * pointer table ends, otherwise its start comes 866 * from the previous block's pointer. 867 */ 868 block_start = OFFSET(inode) + maxblock * 4; 869 if (page->index) 870 block_start = *(u32 *) 871 cramfs_read(sb, blkptr_offset - 4, 4); 872 /* Beware... previous ptr might be a direct ptr */ 873 if (unlikely(block_start & CRAMFS_BLK_FLAG_DIRECT_PTR)) { 874 /* See comments on earlier code. */ 875 u32 prev_start = block_start; 876 block_start = prev_start & ~CRAMFS_BLK_FLAGS; 877 block_start <<= CRAMFS_BLK_DIRECT_PTR_SHIFT; 878 if (prev_start & CRAMFS_BLK_FLAG_UNCOMPRESSED) { 879 block_start += PAGE_SIZE; 880 } else { 881 block_len = *(u16 *) 882 cramfs_read(sb, block_start, 2); 883 block_start += 2 + block_len; 884 } 885 } 886 block_start &= ~CRAMFS_BLK_FLAGS; 887 block_len = block_ptr - block_start; 888 } 889 890 if (block_len == 0) 891 ; /* hole */ 892 else if (unlikely(block_len > 2*PAGE_SIZE || 893 (uncompressed && block_len > PAGE_SIZE))) { 894 mutex_unlock(&read_mutex); 895 pr_err("bad data blocksize %u\n", block_len); 896 goto err; 897 } else if (uncompressed) { 898 memcpy(pgdata, 899 cramfs_read(sb, block_start, block_len), 900 block_len); 901 bytes_filled = block_len; 902 } else { 903 bytes_filled = cramfs_uncompress_block(pgdata, 904 PAGE_SIZE, 905 cramfs_read(sb, block_start, block_len), 906 block_len); 907 } 908 mutex_unlock(&read_mutex); 909 if (unlikely(bytes_filled < 0)) 910 goto err; 911 } 912 913 memset(pgdata + bytes_filled, 0, PAGE_SIZE - bytes_filled); 914 flush_dcache_page(page); 915 kunmap(page); 916 SetPageUptodate(page); 917 unlock_page(page); 918 return 0; 919 920 err: 921 kunmap(page); 922 ClearPageUptodate(page); 923 SetPageError(page); 924 unlock_page(page); 925 return 0; 926 } 927 928 static const struct address_space_operations cramfs_aops = { 929 .readpage = cramfs_readpage 930 }; 931 932 /* 933 * Our operations: 934 */ 935 936 /* 937 * A directory can only readdir 938 */ 939 static const struct file_operations cramfs_directory_operations = { 940 .llseek = generic_file_llseek, 941 .read = generic_read_dir, 942 .iterate_shared = cramfs_readdir, 943 }; 944 945 static const struct inode_operations cramfs_dir_inode_operations = { 946 .lookup = cramfs_lookup, 947 }; 948 949 static const struct super_operations cramfs_ops = { 950 .remount_fs = cramfs_remount, 951 .statfs = cramfs_statfs, 952 }; 953 954 static struct dentry *cramfs_mount(struct file_system_type *fs_type, int flags, 955 const char *dev_name, void *data) 956 { 957 struct dentry *ret = ERR_PTR(-ENOPROTOOPT); 958 959 if (IS_ENABLED(CONFIG_CRAMFS_MTD)) { 960 ret = mount_mtd(fs_type, flags, dev_name, data, 961 cramfs_mtd_fill_super); 962 if (!IS_ERR(ret)) 963 return ret; 964 } 965 if (IS_ENABLED(CONFIG_CRAMFS_BLOCKDEV)) { 966 ret = mount_bdev(fs_type, flags, dev_name, data, 967 cramfs_blkdev_fill_super); 968 } 969 return ret; 970 } 971 972 static struct file_system_type cramfs_fs_type = { 973 .owner = THIS_MODULE, 974 .name = "cramfs", 975 .mount = cramfs_mount, 976 .kill_sb = cramfs_kill_sb, 977 .fs_flags = FS_REQUIRES_DEV, 978 }; 979 MODULE_ALIAS_FS("cramfs"); 980 981 static int __init init_cramfs_fs(void) 982 { 983 int rv; 984 985 rv = cramfs_uncompress_init(); 986 if (rv < 0) 987 return rv; 988 rv = register_filesystem(&cramfs_fs_type); 989 if (rv < 0) 990 cramfs_uncompress_exit(); 991 return rv; 992 } 993 994 static void __exit exit_cramfs_fs(void) 995 { 996 cramfs_uncompress_exit(); 997 unregister_filesystem(&cramfs_fs_type); 998 } 999 1000 module_init(init_cramfs_fs) 1001 module_exit(exit_cramfs_fs) 1002 MODULE_LICENSE("GPL"); 1003