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