Loading...
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/fs_context.h>
28#include <linux/slab.h>
29#include <linux/vfs.h>
30#include <linux/mutex.h>
31#include <uapi/linux/cramfs_fs.h>
32#include <linux/uaccess.h>
33
34#include "internal.h"
35
36/*
37 * cramfs super-block data in memory
38 */
39struct cramfs_sb_info {
40 unsigned long magic;
41 unsigned long size;
42 unsigned long blocks;
43 unsigned long files;
44 unsigned long flags;
45 void *linear_virt_addr;
46 resource_size_t linear_phys_addr;
47 size_t mtd_point_size;
48};
49
50static inline struct cramfs_sb_info *CRAMFS_SB(struct super_block *sb)
51{
52 return sb->s_fs_info;
53}
54
55static const struct super_operations cramfs_ops;
56static const struct inode_operations cramfs_dir_inode_operations;
57static const struct file_operations cramfs_directory_operations;
58static const struct file_operations cramfs_physmem_fops;
59static const struct address_space_operations cramfs_aops;
60
61static DEFINE_MUTEX(read_mutex);
62
63
64/* These macros may change in future, to provide better st_ino semantics. */
65#define OFFSET(x) ((x)->i_ino)
66
67static unsigned long cramino(const struct cramfs_inode *cino, unsigned int offset)
68{
69 if (!cino->offset)
70 return offset + 1;
71 if (!cino->size)
72 return offset + 1;
73
74 /*
75 * The file mode test fixes buggy mkcramfs implementations where
76 * cramfs_inode->offset is set to a non zero value for entries
77 * which did not contain data, like devices node and fifos.
78 */
79 switch (cino->mode & S_IFMT) {
80 case S_IFREG:
81 case S_IFDIR:
82 case S_IFLNK:
83 return cino->offset << 2;
84 default:
85 break;
86 }
87 return offset + 1;
88}
89
90static struct inode *get_cramfs_inode(struct super_block *sb,
91 const struct cramfs_inode *cramfs_inode, unsigned int offset)
92{
93 struct inode *inode;
94 static struct timespec64 zerotime;
95
96 inode = iget_locked(sb, cramino(cramfs_inode, offset));
97 if (!inode)
98 return ERR_PTR(-ENOMEM);
99 if (!(inode->i_state & I_NEW))
100 return inode;
101
102 switch (cramfs_inode->mode & S_IFMT) {
103 case S_IFREG:
104 inode->i_fop = &generic_ro_fops;
105 inode->i_data.a_ops = &cramfs_aops;
106 if (IS_ENABLED(CONFIG_CRAMFS_MTD) &&
107 CRAMFS_SB(sb)->flags & CRAMFS_FLAG_EXT_BLOCK_POINTERS &&
108 CRAMFS_SB(sb)->linear_phys_addr)
109 inode->i_fop = &cramfs_physmem_fops;
110 break;
111 case S_IFDIR:
112 inode->i_op = &cramfs_dir_inode_operations;
113 inode->i_fop = &cramfs_directory_operations;
114 break;
115 case S_IFLNK:
116 inode->i_op = &page_symlink_inode_operations;
117 inode_nohighmem(inode);
118 inode->i_data.a_ops = &cramfs_aops;
119 break;
120 default:
121 init_special_inode(inode, cramfs_inode->mode,
122 old_decode_dev(cramfs_inode->size));
123 }
124
125 inode->i_mode = cramfs_inode->mode;
126 i_uid_write(inode, cramfs_inode->uid);
127 i_gid_write(inode, cramfs_inode->gid);
128
129 /* if the lower 2 bits are zero, the inode contains data */
130 if (!(inode->i_ino & 3)) {
131 inode->i_size = cramfs_inode->size;
132 inode->i_blocks = (cramfs_inode->size - 1) / 512 + 1;
133 }
134
135 /* Struct copy intentional */
136 inode->i_mtime = inode->i_atime = inode->i_ctime = zerotime;
137 /* inode->i_nlink is left 1 - arguably wrong for directories,
138 but it's the best we can do without reading the directory
139 contents. 1 yields the right result in GNU find, even
140 without -noleaf option. */
141
142 unlock_new_inode(inode);
143
144 return inode;
145}
146
147/*
148 * We have our own block cache: don't fill up the buffer cache
149 * with the rom-image, because the way the filesystem is set
150 * up the accesses should be fairly regular and cached in the
151 * page cache and dentry tree anyway..
152 *
153 * This also acts as a way to guarantee contiguous areas of up to
154 * BLKS_PER_BUF*PAGE_SIZE, so that the caller doesn't need to
155 * worry about end-of-buffer issues even when decompressing a full
156 * page cache.
157 *
158 * Note: This is all optimized away at compile time when
159 * CONFIG_CRAMFS_BLOCKDEV=n.
160 */
161#define READ_BUFFERS (2)
162/* NEXT_BUFFER(): Loop over [0..(READ_BUFFERS-1)]. */
163#define NEXT_BUFFER(_ix) ((_ix) ^ 1)
164
165/*
166 * BLKS_PER_BUF_SHIFT should be at least 2 to allow for "compressed"
167 * data that takes up more space than the original and with unlucky
168 * alignment.
169 */
170#define BLKS_PER_BUF_SHIFT (2)
171#define BLKS_PER_BUF (1 << BLKS_PER_BUF_SHIFT)
172#define BUFFER_SIZE (BLKS_PER_BUF*PAGE_SIZE)
173
174static unsigned char read_buffers[READ_BUFFERS][BUFFER_SIZE];
175static unsigned buffer_blocknr[READ_BUFFERS];
176static struct super_block *buffer_dev[READ_BUFFERS];
177static int next_buffer;
178
179/*
180 * Populate our block cache and return a pointer to it.
181 */
182static void *cramfs_blkdev_read(struct super_block *sb, unsigned int offset,
183 unsigned int len)
184{
185 struct address_space *mapping = sb->s_bdev->bd_inode->i_mapping;
186 struct file_ra_state ra;
187 struct page *pages[BLKS_PER_BUF];
188 unsigned i, blocknr, buffer;
189 unsigned long devsize;
190 char *data;
191
192 if (!len)
193 return NULL;
194 blocknr = offset >> PAGE_SHIFT;
195 offset &= PAGE_SIZE - 1;
196
197 /* Check if an existing buffer already has the data.. */
198 for (i = 0; i < READ_BUFFERS; i++) {
199 unsigned int blk_offset;
200
201 if (buffer_dev[i] != sb)
202 continue;
203 if (blocknr < buffer_blocknr[i])
204 continue;
205 blk_offset = (blocknr - buffer_blocknr[i]) << PAGE_SHIFT;
206 blk_offset += offset;
207 if (blk_offset > BUFFER_SIZE ||
208 blk_offset + len > BUFFER_SIZE)
209 continue;
210 return read_buffers[i] + blk_offset;
211 }
212
213 devsize = bdev_nr_bytes(sb->s_bdev) >> PAGE_SHIFT;
214
215 /* Ok, read in BLKS_PER_BUF pages completely first. */
216 file_ra_state_init(&ra, mapping);
217 page_cache_sync_readahead(mapping, &ra, NULL, blocknr, BLKS_PER_BUF);
218
219 for (i = 0; i < BLKS_PER_BUF; i++) {
220 struct page *page = NULL;
221
222 if (blocknr + i < devsize) {
223 page = read_mapping_page(mapping, blocknr + i, NULL);
224 /* synchronous error? */
225 if (IS_ERR(page))
226 page = NULL;
227 }
228 pages[i] = page;
229 }
230
231 buffer = next_buffer;
232 next_buffer = NEXT_BUFFER(buffer);
233 buffer_blocknr[buffer] = blocknr;
234 buffer_dev[buffer] = sb;
235
236 data = read_buffers[buffer];
237 for (i = 0; i < BLKS_PER_BUF; i++) {
238 struct page *page = pages[i];
239
240 if (page) {
241 memcpy(data, kmap(page), PAGE_SIZE);
242 kunmap(page);
243 put_page(page);
244 } else
245 memset(data, 0, PAGE_SIZE);
246 data += PAGE_SIZE;
247 }
248 return read_buffers[buffer] + offset;
249}
250
251/*
252 * Return a pointer to the linearly addressed cramfs image in memory.
253 */
254static void *cramfs_direct_read(struct super_block *sb, unsigned int offset,
255 unsigned int len)
256{
257 struct cramfs_sb_info *sbi = CRAMFS_SB(sb);
258
259 if (!len)
260 return NULL;
261 if (len > sbi->size || offset > sbi->size - len)
262 return page_address(ZERO_PAGE(0));
263 return sbi->linear_virt_addr + offset;
264}
265
266/*
267 * Returns a pointer to a buffer containing at least LEN bytes of
268 * filesystem starting at byte offset OFFSET into the filesystem.
269 */
270static void *cramfs_read(struct super_block *sb, unsigned int offset,
271 unsigned int len)
272{
273 struct cramfs_sb_info *sbi = CRAMFS_SB(sb);
274
275 if (IS_ENABLED(CONFIG_CRAMFS_MTD) && sbi->linear_virt_addr)
276 return cramfs_direct_read(sb, offset, len);
277 else if (IS_ENABLED(CONFIG_CRAMFS_BLOCKDEV))
278 return cramfs_blkdev_read(sb, offset, len);
279 else
280 return NULL;
281}
282
283/*
284 * For a mapping to be possible, we need a range of uncompressed and
285 * contiguous blocks. Return the offset for the first block and number of
286 * valid blocks for which that is true, or zero otherwise.
287 */
288static u32 cramfs_get_block_range(struct inode *inode, u32 pgoff, u32 *pages)
289{
290 struct cramfs_sb_info *sbi = CRAMFS_SB(inode->i_sb);
291 int i;
292 u32 *blockptrs, first_block_addr;
293
294 /*
295 * We can dereference memory directly here as this code may be
296 * reached only when there is a direct filesystem image mapping
297 * available in memory.
298 */
299 blockptrs = (u32 *)(sbi->linear_virt_addr + OFFSET(inode) + pgoff * 4);
300 first_block_addr = blockptrs[0] & ~CRAMFS_BLK_FLAGS;
301 i = 0;
302 do {
303 u32 block_off = i * (PAGE_SIZE >> CRAMFS_BLK_DIRECT_PTR_SHIFT);
304 u32 expect = (first_block_addr + block_off) |
305 CRAMFS_BLK_FLAG_DIRECT_PTR |
306 CRAMFS_BLK_FLAG_UNCOMPRESSED;
307 if (blockptrs[i] != expect) {
308 pr_debug("range: block %d/%d got %#x expects %#x\n",
309 pgoff+i, pgoff + *pages - 1,
310 blockptrs[i], expect);
311 if (i == 0)
312 return 0;
313 break;
314 }
315 } while (++i < *pages);
316
317 *pages = i;
318 return first_block_addr << CRAMFS_BLK_DIRECT_PTR_SHIFT;
319}
320
321#ifdef CONFIG_MMU
322
323/*
324 * Return true if the last page of a file in the filesystem image contains
325 * some other data that doesn't belong to that file. It is assumed that the
326 * last block is CRAMFS_BLK_FLAG_DIRECT_PTR | CRAMFS_BLK_FLAG_UNCOMPRESSED
327 * (verified by cramfs_get_block_range() and directly accessible in memory.
328 */
329static bool cramfs_last_page_is_shared(struct inode *inode)
330{
331 struct cramfs_sb_info *sbi = CRAMFS_SB(inode->i_sb);
332 u32 partial, last_page, blockaddr, *blockptrs;
333 char *tail_data;
334
335 partial = offset_in_page(inode->i_size);
336 if (!partial)
337 return false;
338 last_page = inode->i_size >> PAGE_SHIFT;
339 blockptrs = (u32 *)(sbi->linear_virt_addr + OFFSET(inode));
340 blockaddr = blockptrs[last_page] & ~CRAMFS_BLK_FLAGS;
341 blockaddr <<= CRAMFS_BLK_DIRECT_PTR_SHIFT;
342 tail_data = sbi->linear_virt_addr + blockaddr + partial;
343 return memchr_inv(tail_data, 0, PAGE_SIZE - partial) ? true : false;
344}
345
346static int cramfs_physmem_mmap(struct file *file, struct vm_area_struct *vma)
347{
348 struct inode *inode = file_inode(file);
349 struct cramfs_sb_info *sbi = CRAMFS_SB(inode->i_sb);
350 unsigned int pages, max_pages, offset;
351 unsigned long address, pgoff = vma->vm_pgoff;
352 char *bailout_reason;
353 int ret;
354
355 ret = generic_file_readonly_mmap(file, vma);
356 if (ret)
357 return ret;
358
359 /*
360 * Now try to pre-populate ptes for this vma with a direct
361 * mapping avoiding memory allocation when possible.
362 */
363
364 /* Could COW work here? */
365 bailout_reason = "vma is writable";
366 if (vma->vm_flags & VM_WRITE)
367 goto bailout;
368
369 max_pages = (inode->i_size + PAGE_SIZE - 1) >> PAGE_SHIFT;
370 bailout_reason = "beyond file limit";
371 if (pgoff >= max_pages)
372 goto bailout;
373 pages = min(vma_pages(vma), max_pages - pgoff);
374
375 offset = cramfs_get_block_range(inode, pgoff, &pages);
376 bailout_reason = "unsuitable block layout";
377 if (!offset)
378 goto bailout;
379 address = sbi->linear_phys_addr + offset;
380 bailout_reason = "data is not page aligned";
381 if (!PAGE_ALIGNED(address))
382 goto bailout;
383
384 /* Don't map the last page if it contains some other data */
385 if (pgoff + pages == max_pages && cramfs_last_page_is_shared(inode)) {
386 pr_debug("mmap: %pD: last page is shared\n", file);
387 pages--;
388 }
389
390 if (!pages) {
391 bailout_reason = "no suitable block remaining";
392 goto bailout;
393 }
394
395 if (pages == vma_pages(vma)) {
396 /*
397 * The entire vma is mappable. remap_pfn_range() will
398 * make it distinguishable from a non-direct mapping
399 * in /proc/<pid>/maps by substituting the file offset
400 * with the actual physical address.
401 */
402 ret = remap_pfn_range(vma, vma->vm_start, address >> PAGE_SHIFT,
403 pages * PAGE_SIZE, vma->vm_page_prot);
404 } else {
405 /*
406 * Let's create a mixed map if we can't map it all.
407 * The normal paging machinery will take care of the
408 * unpopulated ptes via cramfs_read_folio().
409 */
410 int i;
411 vma->vm_flags |= VM_MIXEDMAP;
412 for (i = 0; i < pages && !ret; i++) {
413 vm_fault_t vmf;
414 unsigned long off = i * PAGE_SIZE;
415 pfn_t pfn = phys_to_pfn_t(address + off, PFN_DEV);
416 vmf = vmf_insert_mixed(vma, vma->vm_start + off, pfn);
417 if (vmf & VM_FAULT_ERROR)
418 ret = vm_fault_to_errno(vmf, 0);
419 }
420 }
421
422 if (!ret)
423 pr_debug("mapped %pD[%lu] at 0x%08lx (%u/%lu pages) "
424 "to vma 0x%08lx, page_prot 0x%llx\n", file,
425 pgoff, address, pages, vma_pages(vma), vma->vm_start,
426 (unsigned long long)pgprot_val(vma->vm_page_prot));
427 return ret;
428
429bailout:
430 pr_debug("%pD[%lu]: direct mmap impossible: %s\n",
431 file, pgoff, bailout_reason);
432 /* Didn't manage any direct map, but normal paging is still possible */
433 return 0;
434}
435
436#else /* CONFIG_MMU */
437
438static int cramfs_physmem_mmap(struct file *file, struct vm_area_struct *vma)
439{
440 return vma->vm_flags & (VM_SHARED | VM_MAYSHARE) ? 0 : -ENOSYS;
441}
442
443static unsigned long cramfs_physmem_get_unmapped_area(struct file *file,
444 unsigned long addr, unsigned long len,
445 unsigned long pgoff, unsigned long flags)
446{
447 struct inode *inode = file_inode(file);
448 struct super_block *sb = inode->i_sb;
449 struct cramfs_sb_info *sbi = CRAMFS_SB(sb);
450 unsigned int pages, block_pages, max_pages, offset;
451
452 pages = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
453 max_pages = (inode->i_size + PAGE_SIZE - 1) >> PAGE_SHIFT;
454 if (pgoff >= max_pages || pages > max_pages - pgoff)
455 return -EINVAL;
456 block_pages = pages;
457 offset = cramfs_get_block_range(inode, pgoff, &block_pages);
458 if (!offset || block_pages != pages)
459 return -ENOSYS;
460 addr = sbi->linear_phys_addr + offset;
461 pr_debug("get_unmapped for %pD ofs %#lx siz %lu at 0x%08lx\n",
462 file, pgoff*PAGE_SIZE, len, addr);
463 return addr;
464}
465
466static unsigned int cramfs_physmem_mmap_capabilities(struct file *file)
467{
468 return NOMMU_MAP_COPY | NOMMU_MAP_DIRECT |
469 NOMMU_MAP_READ | NOMMU_MAP_EXEC;
470}
471
472#endif /* CONFIG_MMU */
473
474static const struct file_operations cramfs_physmem_fops = {
475 .llseek = generic_file_llseek,
476 .read_iter = generic_file_read_iter,
477 .splice_read = generic_file_splice_read,
478 .mmap = cramfs_physmem_mmap,
479#ifndef CONFIG_MMU
480 .get_unmapped_area = cramfs_physmem_get_unmapped_area,
481 .mmap_capabilities = cramfs_physmem_mmap_capabilities,
482#endif
483};
484
485static void cramfs_kill_sb(struct super_block *sb)
486{
487 struct cramfs_sb_info *sbi = CRAMFS_SB(sb);
488
489 if (IS_ENABLED(CONFIG_CRAMFS_MTD) && sb->s_mtd) {
490 if (sbi && sbi->mtd_point_size)
491 mtd_unpoint(sb->s_mtd, 0, sbi->mtd_point_size);
492 kill_mtd_super(sb);
493 } else if (IS_ENABLED(CONFIG_CRAMFS_BLOCKDEV) && sb->s_bdev) {
494 kill_block_super(sb);
495 }
496 kfree(sbi);
497}
498
499static int cramfs_reconfigure(struct fs_context *fc)
500{
501 sync_filesystem(fc->root->d_sb);
502 fc->sb_flags |= SB_RDONLY;
503 return 0;
504}
505
506static int cramfs_read_super(struct super_block *sb, struct fs_context *fc,
507 struct cramfs_super *super)
508{
509 struct cramfs_sb_info *sbi = CRAMFS_SB(sb);
510 unsigned long root_offset;
511 bool silent = fc->sb_flags & SB_SILENT;
512
513 /* We don't know the real size yet */
514 sbi->size = PAGE_SIZE;
515
516 /* Read the first block and get the superblock from it */
517 mutex_lock(&read_mutex);
518 memcpy(super, cramfs_read(sb, 0, sizeof(*super)), sizeof(*super));
519 mutex_unlock(&read_mutex);
520
521 /* Do sanity checks on the superblock */
522 if (super->magic != CRAMFS_MAGIC) {
523 /* check for wrong endianness */
524 if (super->magic == CRAMFS_MAGIC_WEND) {
525 if (!silent)
526 errorfc(fc, "wrong endianness");
527 return -EINVAL;
528 }
529
530 /* check at 512 byte offset */
531 mutex_lock(&read_mutex);
532 memcpy(super,
533 cramfs_read(sb, 512, sizeof(*super)),
534 sizeof(*super));
535 mutex_unlock(&read_mutex);
536 if (super->magic != CRAMFS_MAGIC) {
537 if (super->magic == CRAMFS_MAGIC_WEND && !silent)
538 errorfc(fc, "wrong endianness");
539 else if (!silent)
540 errorfc(fc, "wrong magic");
541 return -EINVAL;
542 }
543 }
544
545 /* get feature flags first */
546 if (super->flags & ~CRAMFS_SUPPORTED_FLAGS) {
547 errorfc(fc, "unsupported filesystem features");
548 return -EINVAL;
549 }
550
551 /* Check that the root inode is in a sane state */
552 if (!S_ISDIR(super->root.mode)) {
553 errorfc(fc, "root is not a directory");
554 return -EINVAL;
555 }
556 /* correct strange, hard-coded permissions of mkcramfs */
557 super->root.mode |= 0555;
558
559 root_offset = super->root.offset << 2;
560 if (super->flags & CRAMFS_FLAG_FSID_VERSION_2) {
561 sbi->size = super->size;
562 sbi->blocks = super->fsid.blocks;
563 sbi->files = super->fsid.files;
564 } else {
565 sbi->size = 1<<28;
566 sbi->blocks = 0;
567 sbi->files = 0;
568 }
569 sbi->magic = super->magic;
570 sbi->flags = super->flags;
571 if (root_offset == 0)
572 infofc(fc, "empty filesystem");
573 else if (!(super->flags & CRAMFS_FLAG_SHIFTED_ROOT_OFFSET) &&
574 ((root_offset != sizeof(struct cramfs_super)) &&
575 (root_offset != 512 + sizeof(struct cramfs_super))))
576 {
577 errorfc(fc, "bad root offset %lu", root_offset);
578 return -EINVAL;
579 }
580
581 return 0;
582}
583
584static int cramfs_finalize_super(struct super_block *sb,
585 struct cramfs_inode *cramfs_root)
586{
587 struct inode *root;
588
589 /* Set it all up.. */
590 sb->s_flags |= SB_RDONLY;
591 sb->s_time_min = 0;
592 sb->s_time_max = 0;
593 sb->s_op = &cramfs_ops;
594 root = get_cramfs_inode(sb, cramfs_root, 0);
595 if (IS_ERR(root))
596 return PTR_ERR(root);
597 sb->s_root = d_make_root(root);
598 if (!sb->s_root)
599 return -ENOMEM;
600 return 0;
601}
602
603static int cramfs_blkdev_fill_super(struct super_block *sb, struct fs_context *fc)
604{
605 struct cramfs_sb_info *sbi;
606 struct cramfs_super super;
607 int i, err;
608
609 sbi = kzalloc(sizeof(struct cramfs_sb_info), GFP_KERNEL);
610 if (!sbi)
611 return -ENOMEM;
612 sb->s_fs_info = sbi;
613
614 /* Invalidate the read buffers on mount: think disk change.. */
615 for (i = 0; i < READ_BUFFERS; i++)
616 buffer_blocknr[i] = -1;
617
618 err = cramfs_read_super(sb, fc, &super);
619 if (err)
620 return err;
621 return cramfs_finalize_super(sb, &super.root);
622}
623
624static int cramfs_mtd_fill_super(struct super_block *sb, struct fs_context *fc)
625{
626 struct cramfs_sb_info *sbi;
627 struct cramfs_super super;
628 int err;
629
630 sbi = kzalloc(sizeof(struct cramfs_sb_info), GFP_KERNEL);
631 if (!sbi)
632 return -ENOMEM;
633 sb->s_fs_info = sbi;
634
635 /* Map only one page for now. Will remap it when fs size is known. */
636 err = mtd_point(sb->s_mtd, 0, PAGE_SIZE, &sbi->mtd_point_size,
637 &sbi->linear_virt_addr, &sbi->linear_phys_addr);
638 if (err || sbi->mtd_point_size != PAGE_SIZE) {
639 pr_err("unable to get direct memory access to mtd:%s\n",
640 sb->s_mtd->name);
641 return err ? : -ENODATA;
642 }
643
644 pr_info("checking physical address %pap for linear cramfs image\n",
645 &sbi->linear_phys_addr);
646 err = cramfs_read_super(sb, fc, &super);
647 if (err)
648 return err;
649
650 /* Remap the whole filesystem now */
651 pr_info("linear cramfs image on mtd:%s appears to be %lu KB in size\n",
652 sb->s_mtd->name, sbi->size/1024);
653 mtd_unpoint(sb->s_mtd, 0, PAGE_SIZE);
654 err = mtd_point(sb->s_mtd, 0, sbi->size, &sbi->mtd_point_size,
655 &sbi->linear_virt_addr, &sbi->linear_phys_addr);
656 if (err || sbi->mtd_point_size != sbi->size) {
657 pr_err("unable to get direct memory access to mtd:%s\n",
658 sb->s_mtd->name);
659 return err ? : -ENODATA;
660 }
661
662 return cramfs_finalize_super(sb, &super.root);
663}
664
665static int cramfs_statfs(struct dentry *dentry, struct kstatfs *buf)
666{
667 struct super_block *sb = dentry->d_sb;
668 u64 id = 0;
669
670 if (sb->s_bdev)
671 id = huge_encode_dev(sb->s_bdev->bd_dev);
672 else if (sb->s_dev)
673 id = huge_encode_dev(sb->s_dev);
674
675 buf->f_type = CRAMFS_MAGIC;
676 buf->f_bsize = PAGE_SIZE;
677 buf->f_blocks = CRAMFS_SB(sb)->blocks;
678 buf->f_bfree = 0;
679 buf->f_bavail = 0;
680 buf->f_files = CRAMFS_SB(sb)->files;
681 buf->f_ffree = 0;
682 buf->f_fsid = u64_to_fsid(id);
683 buf->f_namelen = CRAMFS_MAXPATHLEN;
684 return 0;
685}
686
687/*
688 * Read a cramfs directory entry.
689 */
690static int cramfs_readdir(struct file *file, struct dir_context *ctx)
691{
692 struct inode *inode = file_inode(file);
693 struct super_block *sb = inode->i_sb;
694 char *buf;
695 unsigned int offset;
696
697 /* Offset within the thing. */
698 if (ctx->pos >= inode->i_size)
699 return 0;
700 offset = ctx->pos;
701 /* Directory entries are always 4-byte aligned */
702 if (offset & 3)
703 return -EINVAL;
704
705 buf = kmalloc(CRAMFS_MAXPATHLEN, GFP_KERNEL);
706 if (!buf)
707 return -ENOMEM;
708
709 while (offset < inode->i_size) {
710 struct cramfs_inode *de;
711 unsigned long nextoffset;
712 char *name;
713 ino_t ino;
714 umode_t mode;
715 int namelen;
716
717 mutex_lock(&read_mutex);
718 de = cramfs_read(sb, OFFSET(inode) + offset, sizeof(*de)+CRAMFS_MAXPATHLEN);
719 name = (char *)(de+1);
720
721 /*
722 * Namelengths on disk are shifted by two
723 * and the name padded out to 4-byte boundaries
724 * with zeroes.
725 */
726 namelen = de->namelen << 2;
727 memcpy(buf, name, namelen);
728 ino = cramino(de, OFFSET(inode) + offset);
729 mode = de->mode;
730 mutex_unlock(&read_mutex);
731 nextoffset = offset + sizeof(*de) + namelen;
732 for (;;) {
733 if (!namelen) {
734 kfree(buf);
735 return -EIO;
736 }
737 if (buf[namelen-1])
738 break;
739 namelen--;
740 }
741 if (!dir_emit(ctx, buf, namelen, ino, mode >> 12))
742 break;
743
744 ctx->pos = offset = nextoffset;
745 }
746 kfree(buf);
747 return 0;
748}
749
750/*
751 * Lookup and fill in the inode data..
752 */
753static struct dentry *cramfs_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
754{
755 unsigned int offset = 0;
756 struct inode *inode = NULL;
757 int sorted;
758
759 mutex_lock(&read_mutex);
760 sorted = CRAMFS_SB(dir->i_sb)->flags & CRAMFS_FLAG_SORTED_DIRS;
761 while (offset < dir->i_size) {
762 struct cramfs_inode *de;
763 char *name;
764 int namelen, retval;
765 int dir_off = OFFSET(dir) + offset;
766
767 de = cramfs_read(dir->i_sb, dir_off, sizeof(*de)+CRAMFS_MAXPATHLEN);
768 name = (char *)(de+1);
769
770 /* Try to take advantage of sorted directories */
771 if (sorted && (dentry->d_name.name[0] < name[0]))
772 break;
773
774 namelen = de->namelen << 2;
775 offset += sizeof(*de) + namelen;
776
777 /* Quick check that the name is roughly the right length */
778 if (((dentry->d_name.len + 3) & ~3) != namelen)
779 continue;
780
781 for (;;) {
782 if (!namelen) {
783 inode = ERR_PTR(-EIO);
784 goto out;
785 }
786 if (name[namelen-1])
787 break;
788 namelen--;
789 }
790 if (namelen != dentry->d_name.len)
791 continue;
792 retval = memcmp(dentry->d_name.name, name, namelen);
793 if (retval > 0)
794 continue;
795 if (!retval) {
796 inode = get_cramfs_inode(dir->i_sb, de, dir_off);
797 break;
798 }
799 /* else (retval < 0) */
800 if (sorted)
801 break;
802 }
803out:
804 mutex_unlock(&read_mutex);
805 return d_splice_alias(inode, dentry);
806}
807
808static int cramfs_read_folio(struct file *file, struct folio *folio)
809{
810 struct page *page = &folio->page;
811 struct inode *inode = page->mapping->host;
812 u32 maxblock;
813 int bytes_filled;
814 void *pgdata;
815
816 maxblock = (inode->i_size + PAGE_SIZE - 1) >> PAGE_SHIFT;
817 bytes_filled = 0;
818 pgdata = kmap(page);
819
820 if (page->index < maxblock) {
821 struct super_block *sb = inode->i_sb;
822 u32 blkptr_offset = OFFSET(inode) + page->index * 4;
823 u32 block_ptr, block_start, block_len;
824 bool uncompressed, direct;
825
826 mutex_lock(&read_mutex);
827 block_ptr = *(u32 *) cramfs_read(sb, blkptr_offset, 4);
828 uncompressed = (block_ptr & CRAMFS_BLK_FLAG_UNCOMPRESSED);
829 direct = (block_ptr & CRAMFS_BLK_FLAG_DIRECT_PTR);
830 block_ptr &= ~CRAMFS_BLK_FLAGS;
831
832 if (direct) {
833 /*
834 * The block pointer is an absolute start pointer,
835 * shifted by 2 bits. The size is included in the
836 * first 2 bytes of the data block when compressed,
837 * or PAGE_SIZE otherwise.
838 */
839 block_start = block_ptr << CRAMFS_BLK_DIRECT_PTR_SHIFT;
840 if (uncompressed) {
841 block_len = PAGE_SIZE;
842 /* if last block: cap to file length */
843 if (page->index == maxblock - 1)
844 block_len =
845 offset_in_page(inode->i_size);
846 } else {
847 block_len = *(u16 *)
848 cramfs_read(sb, block_start, 2);
849 block_start += 2;
850 }
851 } else {
852 /*
853 * The block pointer indicates one past the end of
854 * the current block (start of next block). If this
855 * is the first block then it starts where the block
856 * pointer table ends, otherwise its start comes
857 * from the previous block's pointer.
858 */
859 block_start = OFFSET(inode) + maxblock * 4;
860 if (page->index)
861 block_start = *(u32 *)
862 cramfs_read(sb, blkptr_offset - 4, 4);
863 /* Beware... previous ptr might be a direct ptr */
864 if (unlikely(block_start & CRAMFS_BLK_FLAG_DIRECT_PTR)) {
865 /* See comments on earlier code. */
866 u32 prev_start = block_start;
867 block_start = prev_start & ~CRAMFS_BLK_FLAGS;
868 block_start <<= CRAMFS_BLK_DIRECT_PTR_SHIFT;
869 if (prev_start & CRAMFS_BLK_FLAG_UNCOMPRESSED) {
870 block_start += PAGE_SIZE;
871 } else {
872 block_len = *(u16 *)
873 cramfs_read(sb, block_start, 2);
874 block_start += 2 + block_len;
875 }
876 }
877 block_start &= ~CRAMFS_BLK_FLAGS;
878 block_len = block_ptr - block_start;
879 }
880
881 if (block_len == 0)
882 ; /* hole */
883 else if (unlikely(block_len > 2*PAGE_SIZE ||
884 (uncompressed && block_len > PAGE_SIZE))) {
885 mutex_unlock(&read_mutex);
886 pr_err("bad data blocksize %u\n", block_len);
887 goto err;
888 } else if (uncompressed) {
889 memcpy(pgdata,
890 cramfs_read(sb, block_start, block_len),
891 block_len);
892 bytes_filled = block_len;
893 } else {
894 bytes_filled = cramfs_uncompress_block(pgdata,
895 PAGE_SIZE,
896 cramfs_read(sb, block_start, block_len),
897 block_len);
898 }
899 mutex_unlock(&read_mutex);
900 if (unlikely(bytes_filled < 0))
901 goto err;
902 }
903
904 memset(pgdata + bytes_filled, 0, PAGE_SIZE - bytes_filled);
905 flush_dcache_page(page);
906 kunmap(page);
907 SetPageUptodate(page);
908 unlock_page(page);
909 return 0;
910
911err:
912 kunmap(page);
913 ClearPageUptodate(page);
914 SetPageError(page);
915 unlock_page(page);
916 return 0;
917}
918
919static const struct address_space_operations cramfs_aops = {
920 .read_folio = cramfs_read_folio
921};
922
923/*
924 * Our operations:
925 */
926
927/*
928 * A directory can only readdir
929 */
930static const struct file_operations cramfs_directory_operations = {
931 .llseek = generic_file_llseek,
932 .read = generic_read_dir,
933 .iterate_shared = cramfs_readdir,
934};
935
936static const struct inode_operations cramfs_dir_inode_operations = {
937 .lookup = cramfs_lookup,
938};
939
940static const struct super_operations cramfs_ops = {
941 .statfs = cramfs_statfs,
942};
943
944static int cramfs_get_tree(struct fs_context *fc)
945{
946 int ret = -ENOPROTOOPT;
947
948 if (IS_ENABLED(CONFIG_CRAMFS_MTD)) {
949 ret = get_tree_mtd(fc, cramfs_mtd_fill_super);
950 if (!ret)
951 return 0;
952 }
953 if (IS_ENABLED(CONFIG_CRAMFS_BLOCKDEV))
954 ret = get_tree_bdev(fc, cramfs_blkdev_fill_super);
955 return ret;
956}
957
958static const struct fs_context_operations cramfs_context_ops = {
959 .get_tree = cramfs_get_tree,
960 .reconfigure = cramfs_reconfigure,
961};
962
963/*
964 * Set up the filesystem mount context.
965 */
966static int cramfs_init_fs_context(struct fs_context *fc)
967{
968 fc->ops = &cramfs_context_ops;
969 return 0;
970}
971
972static struct file_system_type cramfs_fs_type = {
973 .owner = THIS_MODULE,
974 .name = "cramfs",
975 .init_fs_context = cramfs_init_fs_context,
976 .kill_sb = cramfs_kill_sb,
977 .fs_flags = FS_REQUIRES_DEV,
978};
979MODULE_ALIAS_FS("cramfs");
980
981static 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
994static void __exit exit_cramfs_fs(void)
995{
996 cramfs_uncompress_exit();
997 unregister_filesystem(&cramfs_fs_type);
998}
999
1000module_init(init_cramfs_fs)
1001module_exit(exit_cramfs_fs)
1002MODULE_LICENSE("GPL");
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#include <linux/module.h>
15#include <linux/fs.h>
16#include <linux/pagemap.h>
17#include <linux/init.h>
18#include <linux/string.h>
19#include <linux/blkdev.h>
20#include <linux/cramfs_fs.h>
21#include <linux/slab.h>
22#include <linux/cramfs_fs_sb.h>
23#include <linux/vfs.h>
24#include <linux/mutex.h>
25
26#include <asm/uaccess.h>
27
28static const struct super_operations cramfs_ops;
29static const struct inode_operations cramfs_dir_inode_operations;
30static const struct file_operations cramfs_directory_operations;
31static const struct address_space_operations cramfs_aops;
32
33static DEFINE_MUTEX(read_mutex);
34
35
36/* These macros may change in future, to provide better st_ino semantics. */
37#define OFFSET(x) ((x)->i_ino)
38
39static unsigned long cramino(const struct cramfs_inode *cino, unsigned int offset)
40{
41 if (!cino->offset)
42 return offset + 1;
43 if (!cino->size)
44 return offset + 1;
45
46 /*
47 * The file mode test fixes buggy mkcramfs implementations where
48 * cramfs_inode->offset is set to a non zero value for entries
49 * which did not contain data, like devices node and fifos.
50 */
51 switch (cino->mode & S_IFMT) {
52 case S_IFREG:
53 case S_IFDIR:
54 case S_IFLNK:
55 return cino->offset << 2;
56 default:
57 break;
58 }
59 return offset + 1;
60}
61
62static struct inode *get_cramfs_inode(struct super_block *sb,
63 const struct cramfs_inode *cramfs_inode, unsigned int offset)
64{
65 struct inode *inode;
66 static struct timespec zerotime;
67
68 inode = iget_locked(sb, cramino(cramfs_inode, offset));
69 if (!inode)
70 return ERR_PTR(-ENOMEM);
71 if (!(inode->i_state & I_NEW))
72 return inode;
73
74 switch (cramfs_inode->mode & S_IFMT) {
75 case S_IFREG:
76 inode->i_fop = &generic_ro_fops;
77 inode->i_data.a_ops = &cramfs_aops;
78 break;
79 case S_IFDIR:
80 inode->i_op = &cramfs_dir_inode_operations;
81 inode->i_fop = &cramfs_directory_operations;
82 break;
83 case S_IFLNK:
84 inode->i_op = &page_symlink_inode_operations;
85 inode->i_data.a_ops = &cramfs_aops;
86 break;
87 default:
88 init_special_inode(inode, cramfs_inode->mode,
89 old_decode_dev(cramfs_inode->size));
90 }
91
92 inode->i_mode = cramfs_inode->mode;
93 inode->i_uid = cramfs_inode->uid;
94 inode->i_gid = cramfs_inode->gid;
95
96 /* if the lower 2 bits are zero, the inode contains data */
97 if (!(inode->i_ino & 3)) {
98 inode->i_size = cramfs_inode->size;
99 inode->i_blocks = (cramfs_inode->size - 1) / 512 + 1;
100 }
101
102 /* Struct copy intentional */
103 inode->i_mtime = inode->i_atime = inode->i_ctime = zerotime;
104 /* inode->i_nlink is left 1 - arguably wrong for directories,
105 but it's the best we can do without reading the directory
106 contents. 1 yields the right result in GNU find, even
107 without -noleaf option. */
108
109 unlock_new_inode(inode);
110
111 return inode;
112}
113
114/*
115 * We have our own block cache: don't fill up the buffer cache
116 * with the rom-image, because the way the filesystem is set
117 * up the accesses should be fairly regular and cached in the
118 * page cache and dentry tree anyway..
119 *
120 * This also acts as a way to guarantee contiguous areas of up to
121 * BLKS_PER_BUF*PAGE_CACHE_SIZE, so that the caller doesn't need to
122 * worry about end-of-buffer issues even when decompressing a full
123 * page cache.
124 */
125#define READ_BUFFERS (2)
126/* NEXT_BUFFER(): Loop over [0..(READ_BUFFERS-1)]. */
127#define NEXT_BUFFER(_ix) ((_ix) ^ 1)
128
129/*
130 * BLKS_PER_BUF_SHIFT should be at least 2 to allow for "compressed"
131 * data that takes up more space than the original and with unlucky
132 * alignment.
133 */
134#define BLKS_PER_BUF_SHIFT (2)
135#define BLKS_PER_BUF (1 << BLKS_PER_BUF_SHIFT)
136#define BUFFER_SIZE (BLKS_PER_BUF*PAGE_CACHE_SIZE)
137
138static unsigned char read_buffers[READ_BUFFERS][BUFFER_SIZE];
139static unsigned buffer_blocknr[READ_BUFFERS];
140static struct super_block * buffer_dev[READ_BUFFERS];
141static int next_buffer;
142
143/*
144 * Returns a pointer to a buffer containing at least LEN bytes of
145 * filesystem starting at byte offset OFFSET into the filesystem.
146 */
147static void *cramfs_read(struct super_block *sb, unsigned int offset, unsigned int len)
148{
149 struct address_space *mapping = sb->s_bdev->bd_inode->i_mapping;
150 struct page *pages[BLKS_PER_BUF];
151 unsigned i, blocknr, buffer;
152 unsigned long devsize;
153 char *data;
154
155 if (!len)
156 return NULL;
157 blocknr = offset >> PAGE_CACHE_SHIFT;
158 offset &= PAGE_CACHE_SIZE - 1;
159
160 /* Check if an existing buffer already has the data.. */
161 for (i = 0; i < READ_BUFFERS; i++) {
162 unsigned int blk_offset;
163
164 if (buffer_dev[i] != sb)
165 continue;
166 if (blocknr < buffer_blocknr[i])
167 continue;
168 blk_offset = (blocknr - buffer_blocknr[i]) << PAGE_CACHE_SHIFT;
169 blk_offset += offset;
170 if (blk_offset + len > BUFFER_SIZE)
171 continue;
172 return read_buffers[i] + blk_offset;
173 }
174
175 devsize = mapping->host->i_size >> PAGE_CACHE_SHIFT;
176
177 /* Ok, read in BLKS_PER_BUF pages completely first. */
178 for (i = 0; i < BLKS_PER_BUF; i++) {
179 struct page *page = NULL;
180
181 if (blocknr + i < devsize) {
182 page = read_mapping_page_async(mapping, blocknr + i,
183 NULL);
184 /* synchronous error? */
185 if (IS_ERR(page))
186 page = NULL;
187 }
188 pages[i] = page;
189 }
190
191 for (i = 0; i < BLKS_PER_BUF; i++) {
192 struct page *page = pages[i];
193 if (page) {
194 wait_on_page_locked(page);
195 if (!PageUptodate(page)) {
196 /* asynchronous error */
197 page_cache_release(page);
198 pages[i] = NULL;
199 }
200 }
201 }
202
203 buffer = next_buffer;
204 next_buffer = NEXT_BUFFER(buffer);
205 buffer_blocknr[buffer] = blocknr;
206 buffer_dev[buffer] = sb;
207
208 data = read_buffers[buffer];
209 for (i = 0; i < BLKS_PER_BUF; i++) {
210 struct page *page = pages[i];
211 if (page) {
212 memcpy(data, kmap(page), PAGE_CACHE_SIZE);
213 kunmap(page);
214 page_cache_release(page);
215 } else
216 memset(data, 0, PAGE_CACHE_SIZE);
217 data += PAGE_CACHE_SIZE;
218 }
219 return read_buffers[buffer] + offset;
220}
221
222static void cramfs_put_super(struct super_block *sb)
223{
224 kfree(sb->s_fs_info);
225 sb->s_fs_info = NULL;
226}
227
228static int cramfs_remount(struct super_block *sb, int *flags, char *data)
229{
230 *flags |= MS_RDONLY;
231 return 0;
232}
233
234static int cramfs_fill_super(struct super_block *sb, void *data, int silent)
235{
236 int i;
237 struct cramfs_super super;
238 unsigned long root_offset;
239 struct cramfs_sb_info *sbi;
240 struct inode *root;
241
242 sb->s_flags |= MS_RDONLY;
243
244 sbi = kzalloc(sizeof(struct cramfs_sb_info), GFP_KERNEL);
245 if (!sbi)
246 return -ENOMEM;
247 sb->s_fs_info = sbi;
248
249 /* Invalidate the read buffers on mount: think disk change.. */
250 mutex_lock(&read_mutex);
251 for (i = 0; i < READ_BUFFERS; i++)
252 buffer_blocknr[i] = -1;
253
254 /* Read the first block and get the superblock from it */
255 memcpy(&super, cramfs_read(sb, 0, sizeof(super)), sizeof(super));
256 mutex_unlock(&read_mutex);
257
258 /* Do sanity checks on the superblock */
259 if (super.magic != CRAMFS_MAGIC) {
260 /* check for wrong endianness */
261 if (super.magic == CRAMFS_MAGIC_WEND) {
262 if (!silent)
263 printk(KERN_ERR "cramfs: wrong endianness\n");
264 goto out;
265 }
266
267 /* check at 512 byte offset */
268 mutex_lock(&read_mutex);
269 memcpy(&super, cramfs_read(sb, 512, sizeof(super)), sizeof(super));
270 mutex_unlock(&read_mutex);
271 if (super.magic != CRAMFS_MAGIC) {
272 if (super.magic == CRAMFS_MAGIC_WEND && !silent)
273 printk(KERN_ERR "cramfs: wrong endianness\n");
274 else if (!silent)
275 printk(KERN_ERR "cramfs: wrong magic\n");
276 goto out;
277 }
278 }
279
280 /* get feature flags first */
281 if (super.flags & ~CRAMFS_SUPPORTED_FLAGS) {
282 printk(KERN_ERR "cramfs: unsupported filesystem features\n");
283 goto out;
284 }
285
286 /* Check that the root inode is in a sane state */
287 if (!S_ISDIR(super.root.mode)) {
288 printk(KERN_ERR "cramfs: root is not a directory\n");
289 goto out;
290 }
291 /* correct strange, hard-coded permissions of mkcramfs */
292 super.root.mode |= (S_IRUSR | S_IXUSR | S_IRGRP | S_IXGRP | S_IROTH | S_IXOTH);
293
294 root_offset = super.root.offset << 2;
295 if (super.flags & CRAMFS_FLAG_FSID_VERSION_2) {
296 sbi->size=super.size;
297 sbi->blocks=super.fsid.blocks;
298 sbi->files=super.fsid.files;
299 } else {
300 sbi->size=1<<28;
301 sbi->blocks=0;
302 sbi->files=0;
303 }
304 sbi->magic=super.magic;
305 sbi->flags=super.flags;
306 if (root_offset == 0)
307 printk(KERN_INFO "cramfs: empty filesystem");
308 else if (!(super.flags & CRAMFS_FLAG_SHIFTED_ROOT_OFFSET) &&
309 ((root_offset != sizeof(struct cramfs_super)) &&
310 (root_offset != 512 + sizeof(struct cramfs_super))))
311 {
312 printk(KERN_ERR "cramfs: bad root offset %lu\n", root_offset);
313 goto out;
314 }
315
316 /* Set it all up.. */
317 sb->s_op = &cramfs_ops;
318 root = get_cramfs_inode(sb, &super.root, 0);
319 if (IS_ERR(root))
320 goto out;
321 sb->s_root = d_make_root(root);
322 if (!sb->s_root)
323 goto out;
324 return 0;
325out:
326 kfree(sbi);
327 sb->s_fs_info = NULL;
328 return -EINVAL;
329}
330
331static int cramfs_statfs(struct dentry *dentry, struct kstatfs *buf)
332{
333 struct super_block *sb = dentry->d_sb;
334 u64 id = huge_encode_dev(sb->s_bdev->bd_dev);
335
336 buf->f_type = CRAMFS_MAGIC;
337 buf->f_bsize = PAGE_CACHE_SIZE;
338 buf->f_blocks = CRAMFS_SB(sb)->blocks;
339 buf->f_bfree = 0;
340 buf->f_bavail = 0;
341 buf->f_files = CRAMFS_SB(sb)->files;
342 buf->f_ffree = 0;
343 buf->f_fsid.val[0] = (u32)id;
344 buf->f_fsid.val[1] = (u32)(id >> 32);
345 buf->f_namelen = CRAMFS_MAXPATHLEN;
346 return 0;
347}
348
349/*
350 * Read a cramfs directory entry.
351 */
352static int cramfs_readdir(struct file *filp, void *dirent, filldir_t filldir)
353{
354 struct inode *inode = filp->f_path.dentry->d_inode;
355 struct super_block *sb = inode->i_sb;
356 char *buf;
357 unsigned int offset;
358 int copied;
359
360 /* Offset within the thing. */
361 offset = filp->f_pos;
362 if (offset >= inode->i_size)
363 return 0;
364 /* Directory entries are always 4-byte aligned */
365 if (offset & 3)
366 return -EINVAL;
367
368 buf = kmalloc(CRAMFS_MAXPATHLEN, GFP_KERNEL);
369 if (!buf)
370 return -ENOMEM;
371
372 copied = 0;
373 while (offset < inode->i_size) {
374 struct cramfs_inode *de;
375 unsigned long nextoffset;
376 char *name;
377 ino_t ino;
378 umode_t mode;
379 int namelen, error;
380
381 mutex_lock(&read_mutex);
382 de = cramfs_read(sb, OFFSET(inode) + offset, sizeof(*de)+CRAMFS_MAXPATHLEN);
383 name = (char *)(de+1);
384
385 /*
386 * Namelengths on disk are shifted by two
387 * and the name padded out to 4-byte boundaries
388 * with zeroes.
389 */
390 namelen = de->namelen << 2;
391 memcpy(buf, name, namelen);
392 ino = cramino(de, OFFSET(inode) + offset);
393 mode = de->mode;
394 mutex_unlock(&read_mutex);
395 nextoffset = offset + sizeof(*de) + namelen;
396 for (;;) {
397 if (!namelen) {
398 kfree(buf);
399 return -EIO;
400 }
401 if (buf[namelen-1])
402 break;
403 namelen--;
404 }
405 error = filldir(dirent, buf, namelen, offset, ino, mode >> 12);
406 if (error)
407 break;
408
409 offset = nextoffset;
410 filp->f_pos = offset;
411 copied++;
412 }
413 kfree(buf);
414 return 0;
415}
416
417/*
418 * Lookup and fill in the inode data..
419 */
420static struct dentry * cramfs_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
421{
422 unsigned int offset = 0;
423 struct inode *inode = NULL;
424 int sorted;
425
426 mutex_lock(&read_mutex);
427 sorted = CRAMFS_SB(dir->i_sb)->flags & CRAMFS_FLAG_SORTED_DIRS;
428 while (offset < dir->i_size) {
429 struct cramfs_inode *de;
430 char *name;
431 int namelen, retval;
432 int dir_off = OFFSET(dir) + offset;
433
434 de = cramfs_read(dir->i_sb, dir_off, sizeof(*de)+CRAMFS_MAXPATHLEN);
435 name = (char *)(de+1);
436
437 /* Try to take advantage of sorted directories */
438 if (sorted && (dentry->d_name.name[0] < name[0]))
439 break;
440
441 namelen = de->namelen << 2;
442 offset += sizeof(*de) + namelen;
443
444 /* Quick check that the name is roughly the right length */
445 if (((dentry->d_name.len + 3) & ~3) != namelen)
446 continue;
447
448 for (;;) {
449 if (!namelen) {
450 inode = ERR_PTR(-EIO);
451 goto out;
452 }
453 if (name[namelen-1])
454 break;
455 namelen--;
456 }
457 if (namelen != dentry->d_name.len)
458 continue;
459 retval = memcmp(dentry->d_name.name, name, namelen);
460 if (retval > 0)
461 continue;
462 if (!retval) {
463 inode = get_cramfs_inode(dir->i_sb, de, dir_off);
464 break;
465 }
466 /* else (retval < 0) */
467 if (sorted)
468 break;
469 }
470out:
471 mutex_unlock(&read_mutex);
472 if (IS_ERR(inode))
473 return ERR_CAST(inode);
474 d_add(dentry, inode);
475 return NULL;
476}
477
478static int cramfs_readpage(struct file *file, struct page * page)
479{
480 struct inode *inode = page->mapping->host;
481 u32 maxblock;
482 int bytes_filled;
483 void *pgdata;
484
485 maxblock = (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
486 bytes_filled = 0;
487 pgdata = kmap(page);
488
489 if (page->index < maxblock) {
490 struct super_block *sb = inode->i_sb;
491 u32 blkptr_offset = OFFSET(inode) + page->index*4;
492 u32 start_offset, compr_len;
493
494 start_offset = OFFSET(inode) + maxblock*4;
495 mutex_lock(&read_mutex);
496 if (page->index)
497 start_offset = *(u32 *) cramfs_read(sb, blkptr_offset-4,
498 4);
499 compr_len = (*(u32 *) cramfs_read(sb, blkptr_offset, 4) -
500 start_offset);
501 mutex_unlock(&read_mutex);
502
503 if (compr_len == 0)
504 ; /* hole */
505 else if (unlikely(compr_len > (PAGE_CACHE_SIZE << 1))) {
506 pr_err("cramfs: bad compressed blocksize %u\n",
507 compr_len);
508 goto err;
509 } else {
510 mutex_lock(&read_mutex);
511 bytes_filled = cramfs_uncompress_block(pgdata,
512 PAGE_CACHE_SIZE,
513 cramfs_read(sb, start_offset, compr_len),
514 compr_len);
515 mutex_unlock(&read_mutex);
516 if (unlikely(bytes_filled < 0))
517 goto err;
518 }
519 }
520
521 memset(pgdata + bytes_filled, 0, PAGE_CACHE_SIZE - bytes_filled);
522 flush_dcache_page(page);
523 kunmap(page);
524 SetPageUptodate(page);
525 unlock_page(page);
526 return 0;
527
528err:
529 kunmap(page);
530 ClearPageUptodate(page);
531 SetPageError(page);
532 unlock_page(page);
533 return 0;
534}
535
536static const struct address_space_operations cramfs_aops = {
537 .readpage = cramfs_readpage
538};
539
540/*
541 * Our operations:
542 */
543
544/*
545 * A directory can only readdir
546 */
547static const struct file_operations cramfs_directory_operations = {
548 .llseek = generic_file_llseek,
549 .read = generic_read_dir,
550 .readdir = cramfs_readdir,
551};
552
553static const struct inode_operations cramfs_dir_inode_operations = {
554 .lookup = cramfs_lookup,
555};
556
557static const struct super_operations cramfs_ops = {
558 .put_super = cramfs_put_super,
559 .remount_fs = cramfs_remount,
560 .statfs = cramfs_statfs,
561};
562
563static struct dentry *cramfs_mount(struct file_system_type *fs_type,
564 int flags, const char *dev_name, void *data)
565{
566 return mount_bdev(fs_type, flags, dev_name, data, cramfs_fill_super);
567}
568
569static struct file_system_type cramfs_fs_type = {
570 .owner = THIS_MODULE,
571 .name = "cramfs",
572 .mount = cramfs_mount,
573 .kill_sb = kill_block_super,
574 .fs_flags = FS_REQUIRES_DEV,
575};
576
577static int __init init_cramfs_fs(void)
578{
579 int rv;
580
581 rv = cramfs_uncompress_init();
582 if (rv < 0)
583 return rv;
584 rv = register_filesystem(&cramfs_fs_type);
585 if (rv < 0)
586 cramfs_uncompress_exit();
587 return rv;
588}
589
590static void __exit exit_cramfs_fs(void)
591{
592 cramfs_uncompress_exit();
593 unregister_filesystem(&cramfs_fs_type);
594}
595
596module_init(init_cramfs_fs)
597module_exit(exit_cramfs_fs)
598MODULE_LICENSE("GPL");