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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/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 page *pages[BLKS_PER_BUF];
187 unsigned i, blocknr, buffer;
188 unsigned long devsize;
189 char *data;
190
191 if (!len)
192 return NULL;
193 blocknr = offset >> PAGE_SHIFT;
194 offset &= PAGE_SIZE - 1;
195
196 /* Check if an existing buffer already has the data.. */
197 for (i = 0; i < READ_BUFFERS; i++) {
198 unsigned int blk_offset;
199
200 if (buffer_dev[i] != sb)
201 continue;
202 if (blocknr < buffer_blocknr[i])
203 continue;
204 blk_offset = (blocknr - buffer_blocknr[i]) << PAGE_SHIFT;
205 blk_offset += offset;
206 if (blk_offset > BUFFER_SIZE ||
207 blk_offset + len > BUFFER_SIZE)
208 continue;
209 return read_buffers[i] + blk_offset;
210 }
211
212 devsize = mapping->host->i_size >> PAGE_SHIFT;
213
214 /* Ok, read in BLKS_PER_BUF pages completely first. */
215 for (i = 0; i < BLKS_PER_BUF; i++) {
216 struct page *page = NULL;
217
218 if (blocknr + i < devsize) {
219 page = read_mapping_page(mapping, blocknr + i, NULL);
220 /* synchronous error? */
221 if (IS_ERR(page))
222 page = NULL;
223 }
224 pages[i] = page;
225 }
226
227 for (i = 0; i < BLKS_PER_BUF; i++) {
228 struct page *page = pages[i];
229
230 if (page) {
231 wait_on_page_locked(page);
232 if (!PageUptodate(page)) {
233 /* asynchronous error */
234 put_page(page);
235 pages[i] = NULL;
236 }
237 }
238 }
239
240 buffer = next_buffer;
241 next_buffer = NEXT_BUFFER(buffer);
242 buffer_blocknr[buffer] = blocknr;
243 buffer_dev[buffer] = sb;
244
245 data = read_buffers[buffer];
246 for (i = 0; i < BLKS_PER_BUF; i++) {
247 struct page *page = pages[i];
248
249 if (page) {
250 memcpy(data, kmap(page), PAGE_SIZE);
251 kunmap(page);
252 put_page(page);
253 } else
254 memset(data, 0, PAGE_SIZE);
255 data += PAGE_SIZE;
256 }
257 return read_buffers[buffer] + offset;
258}
259
260/*
261 * Return a pointer to the linearly addressed cramfs image in memory.
262 */
263static void *cramfs_direct_read(struct super_block *sb, unsigned int offset,
264 unsigned int len)
265{
266 struct cramfs_sb_info *sbi = CRAMFS_SB(sb);
267
268 if (!len)
269 return NULL;
270 if (len > sbi->size || offset > sbi->size - len)
271 return page_address(ZERO_PAGE(0));
272 return sbi->linear_virt_addr + offset;
273}
274
275/*
276 * Returns a pointer to a buffer containing at least LEN bytes of
277 * filesystem starting at byte offset OFFSET into the filesystem.
278 */
279static void *cramfs_read(struct super_block *sb, unsigned int offset,
280 unsigned int len)
281{
282 struct cramfs_sb_info *sbi = CRAMFS_SB(sb);
283
284 if (IS_ENABLED(CONFIG_CRAMFS_MTD) && sbi->linear_virt_addr)
285 return cramfs_direct_read(sb, offset, len);
286 else if (IS_ENABLED(CONFIG_CRAMFS_BLOCKDEV))
287 return cramfs_blkdev_read(sb, offset, len);
288 else
289 return NULL;
290}
291
292/*
293 * For a mapping to be possible, we need a range of uncompressed and
294 * contiguous blocks. Return the offset for the first block and number of
295 * valid blocks for which that is true, or zero otherwise.
296 */
297static u32 cramfs_get_block_range(struct inode *inode, u32 pgoff, u32 *pages)
298{
299 struct cramfs_sb_info *sbi = CRAMFS_SB(inode->i_sb);
300 int i;
301 u32 *blockptrs, first_block_addr;
302
303 /*
304 * We can dereference memory directly here as this code may be
305 * reached only when there is a direct filesystem image mapping
306 * available in memory.
307 */
308 blockptrs = (u32 *)(sbi->linear_virt_addr + OFFSET(inode) + pgoff * 4);
309 first_block_addr = blockptrs[0] & ~CRAMFS_BLK_FLAGS;
310 i = 0;
311 do {
312 u32 block_off = i * (PAGE_SIZE >> CRAMFS_BLK_DIRECT_PTR_SHIFT);
313 u32 expect = (first_block_addr + block_off) |
314 CRAMFS_BLK_FLAG_DIRECT_PTR |
315 CRAMFS_BLK_FLAG_UNCOMPRESSED;
316 if (blockptrs[i] != expect) {
317 pr_debug("range: block %d/%d got %#x expects %#x\n",
318 pgoff+i, pgoff + *pages - 1,
319 blockptrs[i], expect);
320 if (i == 0)
321 return 0;
322 break;
323 }
324 } while (++i < *pages);
325
326 *pages = i;
327 return first_block_addr << CRAMFS_BLK_DIRECT_PTR_SHIFT;
328}
329
330#ifdef CONFIG_MMU
331
332/*
333 * Return true if the last page of a file in the filesystem image contains
334 * some other data that doesn't belong to that file. It is assumed that the
335 * last block is CRAMFS_BLK_FLAG_DIRECT_PTR | CRAMFS_BLK_FLAG_UNCOMPRESSED
336 * (verified by cramfs_get_block_range() and directly accessible in memory.
337 */
338static bool cramfs_last_page_is_shared(struct inode *inode)
339{
340 struct cramfs_sb_info *sbi = CRAMFS_SB(inode->i_sb);
341 u32 partial, last_page, blockaddr, *blockptrs;
342 char *tail_data;
343
344 partial = offset_in_page(inode->i_size);
345 if (!partial)
346 return false;
347 last_page = inode->i_size >> PAGE_SHIFT;
348 blockptrs = (u32 *)(sbi->linear_virt_addr + OFFSET(inode));
349 blockaddr = blockptrs[last_page] & ~CRAMFS_BLK_FLAGS;
350 blockaddr <<= CRAMFS_BLK_DIRECT_PTR_SHIFT;
351 tail_data = sbi->linear_virt_addr + blockaddr + partial;
352 return memchr_inv(tail_data, 0, PAGE_SIZE - partial) ? true : false;
353}
354
355static int cramfs_physmem_mmap(struct file *file, struct vm_area_struct *vma)
356{
357 struct inode *inode = file_inode(file);
358 struct cramfs_sb_info *sbi = CRAMFS_SB(inode->i_sb);
359 unsigned int pages, max_pages, offset;
360 unsigned long address, pgoff = vma->vm_pgoff;
361 char *bailout_reason;
362 int ret;
363
364 ret = generic_file_readonly_mmap(file, vma);
365 if (ret)
366 return ret;
367
368 /*
369 * Now try to pre-populate ptes for this vma with a direct
370 * mapping avoiding memory allocation when possible.
371 */
372
373 /* Could COW work here? */
374 bailout_reason = "vma is writable";
375 if (vma->vm_flags & VM_WRITE)
376 goto bailout;
377
378 max_pages = (inode->i_size + PAGE_SIZE - 1) >> PAGE_SHIFT;
379 bailout_reason = "beyond file limit";
380 if (pgoff >= max_pages)
381 goto bailout;
382 pages = min(vma_pages(vma), max_pages - pgoff);
383
384 offset = cramfs_get_block_range(inode, pgoff, &pages);
385 bailout_reason = "unsuitable block layout";
386 if (!offset)
387 goto bailout;
388 address = sbi->linear_phys_addr + offset;
389 bailout_reason = "data is not page aligned";
390 if (!PAGE_ALIGNED(address))
391 goto bailout;
392
393 /* Don't map the last page if it contains some other data */
394 if (pgoff + pages == max_pages && cramfs_last_page_is_shared(inode)) {
395 pr_debug("mmap: %pD: last page is shared\n", file);
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 %pD[%lu] at 0x%08lx (%u/%lu pages) "
433 "to vma 0x%08lx, page_prot 0x%llx\n", file,
434 pgoff, address, pages, vma_pages(vma), vma->vm_start,
435 (unsigned long long)pgprot_val(vma->vm_page_prot));
436 return ret;
437
438bailout:
439 pr_debug("%pD[%lu]: direct mmap impossible: %s\n",
440 file, pgoff, bailout_reason);
441 /* Didn't manage any direct map, but normal paging is still possible */
442 return 0;
443}
444
445#else /* CONFIG_MMU */
446
447static int cramfs_physmem_mmap(struct file *file, struct vm_area_struct *vma)
448{
449 return vma->vm_flags & (VM_SHARED | VM_MAYSHARE) ? 0 : -ENOSYS;
450}
451
452static unsigned long cramfs_physmem_get_unmapped_area(struct file *file,
453 unsigned long addr, unsigned long len,
454 unsigned long pgoff, unsigned long flags)
455{
456 struct inode *inode = file_inode(file);
457 struct super_block *sb = inode->i_sb;
458 struct cramfs_sb_info *sbi = CRAMFS_SB(sb);
459 unsigned int pages, block_pages, max_pages, offset;
460
461 pages = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
462 max_pages = (inode->i_size + PAGE_SIZE - 1) >> PAGE_SHIFT;
463 if (pgoff >= max_pages || pages > max_pages - pgoff)
464 return -EINVAL;
465 block_pages = pages;
466 offset = cramfs_get_block_range(inode, pgoff, &block_pages);
467 if (!offset || block_pages != pages)
468 return -ENOSYS;
469 addr = sbi->linear_phys_addr + offset;
470 pr_debug("get_unmapped for %pD ofs %#lx siz %lu at 0x%08lx\n",
471 file, pgoff*PAGE_SIZE, len, addr);
472 return addr;
473}
474
475static unsigned int cramfs_physmem_mmap_capabilities(struct file *file)
476{
477 return NOMMU_MAP_COPY | NOMMU_MAP_DIRECT |
478 NOMMU_MAP_READ | NOMMU_MAP_EXEC;
479}
480
481#endif /* CONFIG_MMU */
482
483static const struct file_operations cramfs_physmem_fops = {
484 .llseek = generic_file_llseek,
485 .read_iter = generic_file_read_iter,
486 .splice_read = generic_file_splice_read,
487 .mmap = cramfs_physmem_mmap,
488#ifndef CONFIG_MMU
489 .get_unmapped_area = cramfs_physmem_get_unmapped_area,
490 .mmap_capabilities = cramfs_physmem_mmap_capabilities,
491#endif
492};
493
494static void cramfs_kill_sb(struct super_block *sb)
495{
496 struct cramfs_sb_info *sbi = CRAMFS_SB(sb);
497
498 if (IS_ENABLED(CONFIG_CRAMFS_MTD) && sb->s_mtd) {
499 if (sbi && sbi->mtd_point_size)
500 mtd_unpoint(sb->s_mtd, 0, sbi->mtd_point_size);
501 kill_mtd_super(sb);
502 } else if (IS_ENABLED(CONFIG_CRAMFS_BLOCKDEV) && sb->s_bdev) {
503 kill_block_super(sb);
504 }
505 kfree(sbi);
506}
507
508static int cramfs_reconfigure(struct fs_context *fc)
509{
510 sync_filesystem(fc->root->d_sb);
511 fc->sb_flags |= SB_RDONLY;
512 return 0;
513}
514
515static int cramfs_read_super(struct super_block *sb, struct fs_context *fc,
516 struct cramfs_super *super)
517{
518 struct cramfs_sb_info *sbi = CRAMFS_SB(sb);
519 unsigned long root_offset;
520 bool silent = fc->sb_flags & SB_SILENT;
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 errorfc(fc, "wrong endianness");
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 errorfc(fc, "wrong endianness");
548 else if (!silent)
549 errorfc(fc, "wrong magic");
550 return -EINVAL;
551 }
552 }
553
554 /* get feature flags first */
555 if (super->flags & ~CRAMFS_SUPPORTED_FLAGS) {
556 errorfc(fc, "unsupported filesystem features");
557 return -EINVAL;
558 }
559
560 /* Check that the root inode is in a sane state */
561 if (!S_ISDIR(super->root.mode)) {
562 errorfc(fc, "root is not a directory");
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 infofc(fc, "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 errorfc(fc, "bad root offset %lu", root_offset);
587 return -EINVAL;
588 }
589
590 return 0;
591}
592
593static 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_time_min = 0;
601 sb->s_time_max = 0;
602 sb->s_op = &cramfs_ops;
603 root = get_cramfs_inode(sb, cramfs_root, 0);
604 if (IS_ERR(root))
605 return PTR_ERR(root);
606 sb->s_root = d_make_root(root);
607 if (!sb->s_root)
608 return -ENOMEM;
609 return 0;
610}
611
612static int cramfs_blkdev_fill_super(struct super_block *sb, struct fs_context *fc)
613{
614 struct cramfs_sb_info *sbi;
615 struct cramfs_super super;
616 int i, err;
617
618 sbi = kzalloc(sizeof(struct cramfs_sb_info), GFP_KERNEL);
619 if (!sbi)
620 return -ENOMEM;
621 sb->s_fs_info = sbi;
622
623 /* Invalidate the read buffers on mount: think disk change.. */
624 for (i = 0; i < READ_BUFFERS; i++)
625 buffer_blocknr[i] = -1;
626
627 err = cramfs_read_super(sb, fc, &super);
628 if (err)
629 return err;
630 return cramfs_finalize_super(sb, &super.root);
631}
632
633static int cramfs_mtd_fill_super(struct super_block *sb, struct fs_context *fc)
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, fc, &super);
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
674static 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 = u64_to_fsid(id);
692 buf->f_namelen = CRAMFS_MAXPATHLEN;
693 return 0;
694}
695
696/*
697 * Read a cramfs directory entry.
698 */
699static int cramfs_readdir(struct file *file, struct dir_context *ctx)
700{
701 struct inode *inode = file_inode(file);
702 struct super_block *sb = inode->i_sb;
703 char *buf;
704 unsigned int offset;
705
706 /* Offset within the thing. */
707 if (ctx->pos >= inode->i_size)
708 return 0;
709 offset = ctx->pos;
710 /* Directory entries are always 4-byte aligned */
711 if (offset & 3)
712 return -EINVAL;
713
714 buf = kmalloc(CRAMFS_MAXPATHLEN, GFP_KERNEL);
715 if (!buf)
716 return -ENOMEM;
717
718 while (offset < inode->i_size) {
719 struct cramfs_inode *de;
720 unsigned long nextoffset;
721 char *name;
722 ino_t ino;
723 umode_t mode;
724 int namelen;
725
726 mutex_lock(&read_mutex);
727 de = cramfs_read(sb, OFFSET(inode) + offset, sizeof(*de)+CRAMFS_MAXPATHLEN);
728 name = (char *)(de+1);
729
730 /*
731 * Namelengths on disk are shifted by two
732 * and the name padded out to 4-byte boundaries
733 * with zeroes.
734 */
735 namelen = de->namelen << 2;
736 memcpy(buf, name, namelen);
737 ino = cramino(de, OFFSET(inode) + offset);
738 mode = de->mode;
739 mutex_unlock(&read_mutex);
740 nextoffset = offset + sizeof(*de) + namelen;
741 for (;;) {
742 if (!namelen) {
743 kfree(buf);
744 return -EIO;
745 }
746 if (buf[namelen-1])
747 break;
748 namelen--;
749 }
750 if (!dir_emit(ctx, buf, namelen, ino, mode >> 12))
751 break;
752
753 ctx->pos = offset = nextoffset;
754 }
755 kfree(buf);
756 return 0;
757}
758
759/*
760 * Lookup and fill in the inode data..
761 */
762static struct dentry *cramfs_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
763{
764 unsigned int offset = 0;
765 struct inode *inode = NULL;
766 int sorted;
767
768 mutex_lock(&read_mutex);
769 sorted = CRAMFS_SB(dir->i_sb)->flags & CRAMFS_FLAG_SORTED_DIRS;
770 while (offset < dir->i_size) {
771 struct cramfs_inode *de;
772 char *name;
773 int namelen, retval;
774 int dir_off = OFFSET(dir) + offset;
775
776 de = cramfs_read(dir->i_sb, dir_off, sizeof(*de)+CRAMFS_MAXPATHLEN);
777 name = (char *)(de+1);
778
779 /* Try to take advantage of sorted directories */
780 if (sorted && (dentry->d_name.name[0] < name[0]))
781 break;
782
783 namelen = de->namelen << 2;
784 offset += sizeof(*de) + namelen;
785
786 /* Quick check that the name is roughly the right length */
787 if (((dentry->d_name.len + 3) & ~3) != namelen)
788 continue;
789
790 for (;;) {
791 if (!namelen) {
792 inode = ERR_PTR(-EIO);
793 goto out;
794 }
795 if (name[namelen-1])
796 break;
797 namelen--;
798 }
799 if (namelen != dentry->d_name.len)
800 continue;
801 retval = memcmp(dentry->d_name.name, name, namelen);
802 if (retval > 0)
803 continue;
804 if (!retval) {
805 inode = get_cramfs_inode(dir->i_sb, de, dir_off);
806 break;
807 }
808 /* else (retval < 0) */
809 if (sorted)
810 break;
811 }
812out:
813 mutex_unlock(&read_mutex);
814 return d_splice_alias(inode, dentry);
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 .statfs = cramfs_statfs,
950};
951
952static int cramfs_get_tree(struct fs_context *fc)
953{
954 int ret = -ENOPROTOOPT;
955
956 if (IS_ENABLED(CONFIG_CRAMFS_MTD)) {
957 ret = get_tree_mtd(fc, cramfs_mtd_fill_super);
958 if (!ret)
959 return 0;
960 }
961 if (IS_ENABLED(CONFIG_CRAMFS_BLOCKDEV))
962 ret = get_tree_bdev(fc, cramfs_blkdev_fill_super);
963 return ret;
964}
965
966static const struct fs_context_operations cramfs_context_ops = {
967 .get_tree = cramfs_get_tree,
968 .reconfigure = cramfs_reconfigure,
969};
970
971/*
972 * Set up the filesystem mount context.
973 */
974static int cramfs_init_fs_context(struct fs_context *fc)
975{
976 fc->ops = &cramfs_context_ops;
977 return 0;
978}
979
980static struct file_system_type cramfs_fs_type = {
981 .owner = THIS_MODULE,
982 .name = "cramfs",
983 .init_fs_context = cramfs_init_fs_context,
984 .kill_sb = cramfs_kill_sb,
985 .fs_flags = FS_REQUIRES_DEV,
986};
987MODULE_ALIAS_FS("cramfs");
988
989static int __init init_cramfs_fs(void)
990{
991 int rv;
992
993 rv = cramfs_uncompress_init();
994 if (rv < 0)
995 return rv;
996 rv = register_filesystem(&cramfs_fs_type);
997 if (rv < 0)
998 cramfs_uncompress_exit();
999 return rv;
1000}
1001
1002static void __exit exit_cramfs_fs(void)
1003{
1004 cramfs_uncompress_exit();
1005 unregister_filesystem(&cramfs_fs_type);
1006}
1007
1008module_init(init_cramfs_fs)
1009module_exit(exit_cramfs_fs)
1010MODULE_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/buffer_head.h>
24#include <linux/vfs.h>
25#include <linux/mutex.h>
26
27#include <asm/uaccess.h>
28
29static const struct super_operations cramfs_ops;
30static const struct inode_operations cramfs_dir_inode_operations;
31static const struct file_operations cramfs_directory_operations;
32static const struct address_space_operations cramfs_aops;
33
34static DEFINE_MUTEX(read_mutex);
35
36
37/* These macros may change in future, to provide better st_ino semantics. */
38#define OFFSET(x) ((x)->i_ino)
39
40static unsigned long cramino(const struct cramfs_inode *cino, unsigned int offset)
41{
42 if (!cino->offset)
43 return offset + 1;
44 if (!cino->size)
45 return offset + 1;
46
47 /*
48 * The file mode test fixes buggy mkcramfs implementations where
49 * cramfs_inode->offset is set to a non zero value for entries
50 * which did not contain data, like devices node and fifos.
51 */
52 switch (cino->mode & S_IFMT) {
53 case S_IFREG:
54 case S_IFDIR:
55 case S_IFLNK:
56 return cino->offset << 2;
57 default:
58 break;
59 }
60 return offset + 1;
61}
62
63static struct inode *get_cramfs_inode(struct super_block *sb,
64 const struct cramfs_inode *cramfs_inode, unsigned int offset)
65{
66 struct inode *inode;
67 static struct timespec zerotime;
68
69 inode = iget_locked(sb, cramino(cramfs_inode, offset));
70 if (!inode)
71 return ERR_PTR(-ENOMEM);
72 if (!(inode->i_state & I_NEW))
73 return inode;
74
75 switch (cramfs_inode->mode & S_IFMT) {
76 case S_IFREG:
77 inode->i_fop = &generic_ro_fops;
78 inode->i_data.a_ops = &cramfs_aops;
79 break;
80 case S_IFDIR:
81 inode->i_op = &cramfs_dir_inode_operations;
82 inode->i_fop = &cramfs_directory_operations;
83 break;
84 case S_IFLNK:
85 inode->i_op = &page_symlink_inode_operations;
86 inode->i_data.a_ops = &cramfs_aops;
87 break;
88 default:
89 init_special_inode(inode, cramfs_inode->mode,
90 old_decode_dev(cramfs_inode->size));
91 }
92
93 inode->i_mode = cramfs_inode->mode;
94 inode->i_uid = cramfs_inode->uid;
95 inode->i_gid = cramfs_inode->gid;
96
97 /* if the lower 2 bits are zero, the inode contains data */
98 if (!(inode->i_ino & 3)) {
99 inode->i_size = cramfs_inode->size;
100 inode->i_blocks = (cramfs_inode->size - 1) / 512 + 1;
101 }
102
103 /* Struct copy intentional */
104 inode->i_mtime = inode->i_atime = inode->i_ctime = zerotime;
105 /* inode->i_nlink is left 1 - arguably wrong for directories,
106 but it's the best we can do without reading the directory
107 contents. 1 yields the right result in GNU find, even
108 without -noleaf option. */
109
110 unlock_new_inode(inode);
111
112 return inode;
113}
114
115/*
116 * We have our own block cache: don't fill up the buffer cache
117 * with the rom-image, because the way the filesystem is set
118 * up the accesses should be fairly regular and cached in the
119 * page cache and dentry tree anyway..
120 *
121 * This also acts as a way to guarantee contiguous areas of up to
122 * BLKS_PER_BUF*PAGE_CACHE_SIZE, so that the caller doesn't need to
123 * worry about end-of-buffer issues even when decompressing a full
124 * page cache.
125 */
126#define READ_BUFFERS (2)
127/* NEXT_BUFFER(): Loop over [0..(READ_BUFFERS-1)]. */
128#define NEXT_BUFFER(_ix) ((_ix) ^ 1)
129
130/*
131 * BLKS_PER_BUF_SHIFT should be at least 2 to allow for "compressed"
132 * data that takes up more space than the original and with unlucky
133 * alignment.
134 */
135#define BLKS_PER_BUF_SHIFT (2)
136#define BLKS_PER_BUF (1 << BLKS_PER_BUF_SHIFT)
137#define BUFFER_SIZE (BLKS_PER_BUF*PAGE_CACHE_SIZE)
138
139static unsigned char read_buffers[READ_BUFFERS][BUFFER_SIZE];
140static unsigned buffer_blocknr[READ_BUFFERS];
141static struct super_block * buffer_dev[READ_BUFFERS];
142static int next_buffer;
143
144/*
145 * Returns a pointer to a buffer containing at least LEN bytes of
146 * filesystem starting at byte offset OFFSET into the filesystem.
147 */
148static void *cramfs_read(struct super_block *sb, unsigned int offset, unsigned int len)
149{
150 struct address_space *mapping = sb->s_bdev->bd_inode->i_mapping;
151 struct page *pages[BLKS_PER_BUF];
152 unsigned i, blocknr, buffer;
153 unsigned long devsize;
154 char *data;
155
156 if (!len)
157 return NULL;
158 blocknr = offset >> PAGE_CACHE_SHIFT;
159 offset &= PAGE_CACHE_SIZE - 1;
160
161 /* Check if an existing buffer already has the data.. */
162 for (i = 0; i < READ_BUFFERS; i++) {
163 unsigned int blk_offset;
164
165 if (buffer_dev[i] != sb)
166 continue;
167 if (blocknr < buffer_blocknr[i])
168 continue;
169 blk_offset = (blocknr - buffer_blocknr[i]) << PAGE_CACHE_SHIFT;
170 blk_offset += offset;
171 if (blk_offset + len > BUFFER_SIZE)
172 continue;
173 return read_buffers[i] + blk_offset;
174 }
175
176 devsize = mapping->host->i_size >> PAGE_CACHE_SHIFT;
177
178 /* Ok, read in BLKS_PER_BUF pages completely first. */
179 for (i = 0; i < BLKS_PER_BUF; i++) {
180 struct page *page = NULL;
181
182 if (blocknr + i < devsize) {
183 page = read_mapping_page_async(mapping, blocknr + i,
184 NULL);
185 /* synchronous error? */
186 if (IS_ERR(page))
187 page = NULL;
188 }
189 pages[i] = page;
190 }
191
192 for (i = 0; i < BLKS_PER_BUF; i++) {
193 struct page *page = pages[i];
194 if (page) {
195 wait_on_page_locked(page);
196 if (!PageUptodate(page)) {
197 /* asynchronous error */
198 page_cache_release(page);
199 pages[i] = NULL;
200 }
201 }
202 }
203
204 buffer = next_buffer;
205 next_buffer = NEXT_BUFFER(buffer);
206 buffer_blocknr[buffer] = blocknr;
207 buffer_dev[buffer] = sb;
208
209 data = read_buffers[buffer];
210 for (i = 0; i < BLKS_PER_BUF; i++) {
211 struct page *page = pages[i];
212 if (page) {
213 memcpy(data, kmap(page), PAGE_CACHE_SIZE);
214 kunmap(page);
215 page_cache_release(page);
216 } else
217 memset(data, 0, PAGE_CACHE_SIZE);
218 data += PAGE_CACHE_SIZE;
219 }
220 return read_buffers[buffer] + offset;
221}
222
223static void cramfs_put_super(struct super_block *sb)
224{
225 kfree(sb->s_fs_info);
226 sb->s_fs_info = NULL;
227}
228
229static int cramfs_remount(struct super_block *sb, int *flags, char *data)
230{
231 *flags |= MS_RDONLY;
232 return 0;
233}
234
235static int cramfs_fill_super(struct super_block *sb, void *data, int silent)
236{
237 int i;
238 struct cramfs_super super;
239 unsigned long root_offset;
240 struct cramfs_sb_info *sbi;
241 struct inode *root;
242
243 sb->s_flags |= MS_RDONLY;
244
245 sbi = kzalloc(sizeof(struct cramfs_sb_info), GFP_KERNEL);
246 if (!sbi)
247 return -ENOMEM;
248 sb->s_fs_info = sbi;
249
250 /* Invalidate the read buffers on mount: think disk change.. */
251 mutex_lock(&read_mutex);
252 for (i = 0; i < READ_BUFFERS; i++)
253 buffer_blocknr[i] = -1;
254
255 /* Read the first block and get the superblock from it */
256 memcpy(&super, cramfs_read(sb, 0, sizeof(super)), sizeof(super));
257 mutex_unlock(&read_mutex);
258
259 /* Do sanity checks on the superblock */
260 if (super.magic != CRAMFS_MAGIC) {
261 /* check for wrong endianess */
262 if (super.magic == CRAMFS_MAGIC_WEND) {
263 if (!silent)
264 printk(KERN_ERR "cramfs: wrong endianess\n");
265 goto out;
266 }
267
268 /* check at 512 byte offset */
269 mutex_lock(&read_mutex);
270 memcpy(&super, cramfs_read(sb, 512, sizeof(super)), sizeof(super));
271 mutex_unlock(&read_mutex);
272 if (super.magic != CRAMFS_MAGIC) {
273 if (super.magic == CRAMFS_MAGIC_WEND && !silent)
274 printk(KERN_ERR "cramfs: wrong endianess\n");
275 else if (!silent)
276 printk(KERN_ERR "cramfs: wrong magic\n");
277 goto out;
278 }
279 }
280
281 /* get feature flags first */
282 if (super.flags & ~CRAMFS_SUPPORTED_FLAGS) {
283 printk(KERN_ERR "cramfs: unsupported filesystem features\n");
284 goto out;
285 }
286
287 /* Check that the root inode is in a sane state */
288 if (!S_ISDIR(super.root.mode)) {
289 printk(KERN_ERR "cramfs: root is not a directory\n");
290 goto out;
291 }
292 /* correct strange, hard-coded permissions of mkcramfs */
293 super.root.mode |= (S_IRUSR | S_IXUSR | S_IRGRP | S_IXGRP | S_IROTH | S_IXOTH);
294
295 root_offset = super.root.offset << 2;
296 if (super.flags & CRAMFS_FLAG_FSID_VERSION_2) {
297 sbi->size=super.size;
298 sbi->blocks=super.fsid.blocks;
299 sbi->files=super.fsid.files;
300 } else {
301 sbi->size=1<<28;
302 sbi->blocks=0;
303 sbi->files=0;
304 }
305 sbi->magic=super.magic;
306 sbi->flags=super.flags;
307 if (root_offset == 0)
308 printk(KERN_INFO "cramfs: empty filesystem");
309 else if (!(super.flags & CRAMFS_FLAG_SHIFTED_ROOT_OFFSET) &&
310 ((root_offset != sizeof(struct cramfs_super)) &&
311 (root_offset != 512 + sizeof(struct cramfs_super))))
312 {
313 printk(KERN_ERR "cramfs: bad root offset %lu\n", root_offset);
314 goto out;
315 }
316
317 /* Set it all up.. */
318 sb->s_op = &cramfs_ops;
319 root = get_cramfs_inode(sb, &super.root, 0);
320 if (IS_ERR(root))
321 goto out;
322 sb->s_root = d_alloc_root(root);
323 if (!sb->s_root) {
324 iput(root);
325 goto out;
326 }
327 return 0;
328out:
329 kfree(sbi);
330 sb->s_fs_info = NULL;
331 return -EINVAL;
332}
333
334static int cramfs_statfs(struct dentry *dentry, struct kstatfs *buf)
335{
336 struct super_block *sb = dentry->d_sb;
337 u64 id = huge_encode_dev(sb->s_bdev->bd_dev);
338
339 buf->f_type = CRAMFS_MAGIC;
340 buf->f_bsize = PAGE_CACHE_SIZE;
341 buf->f_blocks = CRAMFS_SB(sb)->blocks;
342 buf->f_bfree = 0;
343 buf->f_bavail = 0;
344 buf->f_files = CRAMFS_SB(sb)->files;
345 buf->f_ffree = 0;
346 buf->f_fsid.val[0] = (u32)id;
347 buf->f_fsid.val[1] = (u32)(id >> 32);
348 buf->f_namelen = CRAMFS_MAXPATHLEN;
349 return 0;
350}
351
352/*
353 * Read a cramfs directory entry.
354 */
355static int cramfs_readdir(struct file *filp, void *dirent, filldir_t filldir)
356{
357 struct inode *inode = filp->f_path.dentry->d_inode;
358 struct super_block *sb = inode->i_sb;
359 char *buf;
360 unsigned int offset;
361 int copied;
362
363 /* Offset within the thing. */
364 offset = filp->f_pos;
365 if (offset >= inode->i_size)
366 return 0;
367 /* Directory entries are always 4-byte aligned */
368 if (offset & 3)
369 return -EINVAL;
370
371 buf = kmalloc(CRAMFS_MAXPATHLEN, GFP_KERNEL);
372 if (!buf)
373 return -ENOMEM;
374
375 copied = 0;
376 while (offset < inode->i_size) {
377 struct cramfs_inode *de;
378 unsigned long nextoffset;
379 char *name;
380 ino_t ino;
381 mode_t mode;
382 int namelen, error;
383
384 mutex_lock(&read_mutex);
385 de = cramfs_read(sb, OFFSET(inode) + offset, sizeof(*de)+CRAMFS_MAXPATHLEN);
386 name = (char *)(de+1);
387
388 /*
389 * Namelengths on disk are shifted by two
390 * and the name padded out to 4-byte boundaries
391 * with zeroes.
392 */
393 namelen = de->namelen << 2;
394 memcpy(buf, name, namelen);
395 ino = cramino(de, OFFSET(inode) + offset);
396 mode = de->mode;
397 mutex_unlock(&read_mutex);
398 nextoffset = offset + sizeof(*de) + namelen;
399 for (;;) {
400 if (!namelen) {
401 kfree(buf);
402 return -EIO;
403 }
404 if (buf[namelen-1])
405 break;
406 namelen--;
407 }
408 error = filldir(dirent, buf, namelen, offset, ino, mode >> 12);
409 if (error)
410 break;
411
412 offset = nextoffset;
413 filp->f_pos = offset;
414 copied++;
415 }
416 kfree(buf);
417 return 0;
418}
419
420/*
421 * Lookup and fill in the inode data..
422 */
423static struct dentry * cramfs_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
424{
425 unsigned int offset = 0;
426 struct inode *inode = NULL;
427 int sorted;
428
429 mutex_lock(&read_mutex);
430 sorted = CRAMFS_SB(dir->i_sb)->flags & CRAMFS_FLAG_SORTED_DIRS;
431 while (offset < dir->i_size) {
432 struct cramfs_inode *de;
433 char *name;
434 int namelen, retval;
435 int dir_off = OFFSET(dir) + offset;
436
437 de = cramfs_read(dir->i_sb, dir_off, sizeof(*de)+CRAMFS_MAXPATHLEN);
438 name = (char *)(de+1);
439
440 /* Try to take advantage of sorted directories */
441 if (sorted && (dentry->d_name.name[0] < name[0]))
442 break;
443
444 namelen = de->namelen << 2;
445 offset += sizeof(*de) + namelen;
446
447 /* Quick check that the name is roughly the right length */
448 if (((dentry->d_name.len + 3) & ~3) != namelen)
449 continue;
450
451 for (;;) {
452 if (!namelen) {
453 inode = ERR_PTR(-EIO);
454 goto out;
455 }
456 if (name[namelen-1])
457 break;
458 namelen--;
459 }
460 if (namelen != dentry->d_name.len)
461 continue;
462 retval = memcmp(dentry->d_name.name, name, namelen);
463 if (retval > 0)
464 continue;
465 if (!retval) {
466 inode = get_cramfs_inode(dir->i_sb, de, dir_off);
467 break;
468 }
469 /* else (retval < 0) */
470 if (sorted)
471 break;
472 }
473out:
474 mutex_unlock(&read_mutex);
475 if (IS_ERR(inode))
476 return ERR_CAST(inode);
477 d_add(dentry, inode);
478 return NULL;
479}
480
481static int cramfs_readpage(struct file *file, struct page * page)
482{
483 struct inode *inode = page->mapping->host;
484 u32 maxblock;
485 int bytes_filled;
486 void *pgdata;
487
488 maxblock = (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
489 bytes_filled = 0;
490 pgdata = kmap(page);
491
492 if (page->index < maxblock) {
493 struct super_block *sb = inode->i_sb;
494 u32 blkptr_offset = OFFSET(inode) + page->index*4;
495 u32 start_offset, compr_len;
496
497 start_offset = OFFSET(inode) + maxblock*4;
498 mutex_lock(&read_mutex);
499 if (page->index)
500 start_offset = *(u32 *) cramfs_read(sb, blkptr_offset-4,
501 4);
502 compr_len = (*(u32 *) cramfs_read(sb, blkptr_offset, 4) -
503 start_offset);
504 mutex_unlock(&read_mutex);
505
506 if (compr_len == 0)
507 ; /* hole */
508 else if (unlikely(compr_len > (PAGE_CACHE_SIZE << 1))) {
509 pr_err("cramfs: bad compressed blocksize %u\n",
510 compr_len);
511 goto err;
512 } else {
513 mutex_lock(&read_mutex);
514 bytes_filled = cramfs_uncompress_block(pgdata,
515 PAGE_CACHE_SIZE,
516 cramfs_read(sb, start_offset, compr_len),
517 compr_len);
518 mutex_unlock(&read_mutex);
519 if (unlikely(bytes_filled < 0))
520 goto err;
521 }
522 }
523
524 memset(pgdata + bytes_filled, 0, PAGE_CACHE_SIZE - bytes_filled);
525 flush_dcache_page(page);
526 kunmap(page);
527 SetPageUptodate(page);
528 unlock_page(page);
529 return 0;
530
531err:
532 kunmap(page);
533 ClearPageUptodate(page);
534 SetPageError(page);
535 unlock_page(page);
536 return 0;
537}
538
539static const struct address_space_operations cramfs_aops = {
540 .readpage = cramfs_readpage
541};
542
543/*
544 * Our operations:
545 */
546
547/*
548 * A directory can only readdir
549 */
550static const struct file_operations cramfs_directory_operations = {
551 .llseek = generic_file_llseek,
552 .read = generic_read_dir,
553 .readdir = cramfs_readdir,
554};
555
556static const struct inode_operations cramfs_dir_inode_operations = {
557 .lookup = cramfs_lookup,
558};
559
560static const struct super_operations cramfs_ops = {
561 .put_super = cramfs_put_super,
562 .remount_fs = cramfs_remount,
563 .statfs = cramfs_statfs,
564};
565
566static struct dentry *cramfs_mount(struct file_system_type *fs_type,
567 int flags, const char *dev_name, void *data)
568{
569 return mount_bdev(fs_type, flags, dev_name, data, cramfs_fill_super);
570}
571
572static struct file_system_type cramfs_fs_type = {
573 .owner = THIS_MODULE,
574 .name = "cramfs",
575 .mount = cramfs_mount,
576 .kill_sb = kill_block_super,
577 .fs_flags = FS_REQUIRES_DEV,
578};
579
580static int __init init_cramfs_fs(void)
581{
582 int rv;
583
584 rv = cramfs_uncompress_init();
585 if (rv < 0)
586 return rv;
587 rv = register_filesystem(&cramfs_fs_type);
588 if (rv < 0)
589 cramfs_uncompress_exit();
590 return rv;
591}
592
593static void __exit exit_cramfs_fs(void)
594{
595 cramfs_uncompress_exit();
596 unregister_filesystem(&cramfs_fs_type);
597}
598
599module_init(init_cramfs_fs)
600module_exit(exit_cramfs_fs)
601MODULE_LICENSE("GPL");