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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: %s: last page is shared\n",
396 file_dentry(file)->d_name.name);
397 pages--;
398 }
399
400 if (!pages) {
401 bailout_reason = "no suitable block remaining";
402 goto bailout;
403 }
404
405 if (pages == vma_pages(vma)) {
406 /*
407 * The entire vma is mappable. remap_pfn_range() will
408 * make it distinguishable from a non-direct mapping
409 * in /proc/<pid>/maps by substituting the file offset
410 * with the actual physical address.
411 */
412 ret = remap_pfn_range(vma, vma->vm_start, address >> PAGE_SHIFT,
413 pages * PAGE_SIZE, vma->vm_page_prot);
414 } else {
415 /*
416 * Let's create a mixed map if we can't map it all.
417 * The normal paging machinery will take care of the
418 * unpopulated ptes via cramfs_readpage().
419 */
420 int i;
421 vma->vm_flags |= VM_MIXEDMAP;
422 for (i = 0; i < pages && !ret; i++) {
423 vm_fault_t vmf;
424 unsigned long off = i * PAGE_SIZE;
425 pfn_t pfn = phys_to_pfn_t(address + off, PFN_DEV);
426 vmf = vmf_insert_mixed(vma, vma->vm_start + off, pfn);
427 if (vmf & VM_FAULT_ERROR)
428 ret = vm_fault_to_errno(vmf, 0);
429 }
430 }
431
432 if (!ret)
433 pr_debug("mapped %s[%lu] at 0x%08lx (%u/%lu pages) "
434 "to vma 0x%08lx, page_prot 0x%llx\n",
435 file_dentry(file)->d_name.name, pgoff,
436 address, pages, vma_pages(vma), vma->vm_start,
437 (unsigned long long)pgprot_val(vma->vm_page_prot));
438 return ret;
439
440bailout:
441 pr_debug("%s[%lu]: direct mmap impossible: %s\n",
442 file_dentry(file)->d_name.name, pgoff, bailout_reason);
443 /* Didn't manage any direct map, but normal paging is still possible */
444 return 0;
445}
446
447#else /* CONFIG_MMU */
448
449static int cramfs_physmem_mmap(struct file *file, struct vm_area_struct *vma)
450{
451 return vma->vm_flags & (VM_SHARED | VM_MAYSHARE) ? 0 : -ENOSYS;
452}
453
454static unsigned long cramfs_physmem_get_unmapped_area(struct file *file,
455 unsigned long addr, unsigned long len,
456 unsigned long pgoff, unsigned long flags)
457{
458 struct inode *inode = file_inode(file);
459 struct super_block *sb = inode->i_sb;
460 struct cramfs_sb_info *sbi = CRAMFS_SB(sb);
461 unsigned int pages, block_pages, max_pages, offset;
462
463 pages = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
464 max_pages = (inode->i_size + PAGE_SIZE - 1) >> PAGE_SHIFT;
465 if (pgoff >= max_pages || pages > max_pages - pgoff)
466 return -EINVAL;
467 block_pages = pages;
468 offset = cramfs_get_block_range(inode, pgoff, &block_pages);
469 if (!offset || block_pages != pages)
470 return -ENOSYS;
471 addr = sbi->linear_phys_addr + offset;
472 pr_debug("get_unmapped for %s ofs %#lx siz %lu at 0x%08lx\n",
473 file_dentry(file)->d_name.name, pgoff*PAGE_SIZE, len, addr);
474 return addr;
475}
476
477static unsigned int cramfs_physmem_mmap_capabilities(struct file *file)
478{
479 return NOMMU_MAP_COPY | NOMMU_MAP_DIRECT |
480 NOMMU_MAP_READ | NOMMU_MAP_EXEC;
481}
482
483#endif /* CONFIG_MMU */
484
485static const struct file_operations cramfs_physmem_fops = {
486 .llseek = generic_file_llseek,
487 .read_iter = generic_file_read_iter,
488 .splice_read = generic_file_splice_read,
489 .mmap = cramfs_physmem_mmap,
490#ifndef CONFIG_MMU
491 .get_unmapped_area = cramfs_physmem_get_unmapped_area,
492 .mmap_capabilities = cramfs_physmem_mmap_capabilities,
493#endif
494};
495
496static void cramfs_kill_sb(struct super_block *sb)
497{
498 struct cramfs_sb_info *sbi = CRAMFS_SB(sb);
499
500 if (IS_ENABLED(CONFIG_CRAMFS_MTD) && sb->s_mtd) {
501 if (sbi && sbi->mtd_point_size)
502 mtd_unpoint(sb->s_mtd, 0, sbi->mtd_point_size);
503 kill_mtd_super(sb);
504 } else if (IS_ENABLED(CONFIG_CRAMFS_BLOCKDEV) && sb->s_bdev) {
505 kill_block_super(sb);
506 }
507 kfree(sbi);
508}
509
510static int cramfs_reconfigure(struct fs_context *fc)
511{
512 sync_filesystem(fc->root->d_sb);
513 fc->sb_flags |= SB_RDONLY;
514 return 0;
515}
516
517static int cramfs_read_super(struct super_block *sb, struct fs_context *fc,
518 struct cramfs_super *super)
519{
520 struct cramfs_sb_info *sbi = CRAMFS_SB(sb);
521 unsigned long root_offset;
522 bool silent = fc->sb_flags & SB_SILENT;
523
524 /* We don't know the real size yet */
525 sbi->size = PAGE_SIZE;
526
527 /* Read the first block and get the superblock from it */
528 mutex_lock(&read_mutex);
529 memcpy(super, cramfs_read(sb, 0, sizeof(*super)), sizeof(*super));
530 mutex_unlock(&read_mutex);
531
532 /* Do sanity checks on the superblock */
533 if (super->magic != CRAMFS_MAGIC) {
534 /* check for wrong endianness */
535 if (super->magic == CRAMFS_MAGIC_WEND) {
536 if (!silent)
537 errorf(fc, "cramfs: wrong endianness");
538 return -EINVAL;
539 }
540
541 /* check at 512 byte offset */
542 mutex_lock(&read_mutex);
543 memcpy(super,
544 cramfs_read(sb, 512, sizeof(*super)),
545 sizeof(*super));
546 mutex_unlock(&read_mutex);
547 if (super->magic != CRAMFS_MAGIC) {
548 if (super->magic == CRAMFS_MAGIC_WEND && !silent)
549 errorf(fc, "cramfs: wrong endianness");
550 else if (!silent)
551 errorf(fc, "cramfs: wrong magic");
552 return -EINVAL;
553 }
554 }
555
556 /* get feature flags first */
557 if (super->flags & ~CRAMFS_SUPPORTED_FLAGS) {
558 errorf(fc, "cramfs: unsupported filesystem features");
559 return -EINVAL;
560 }
561
562 /* Check that the root inode is in a sane state */
563 if (!S_ISDIR(super->root.mode)) {
564 errorf(fc, "cramfs: root is not a directory");
565 return -EINVAL;
566 }
567 /* correct strange, hard-coded permissions of mkcramfs */
568 super->root.mode |= 0555;
569
570 root_offset = super->root.offset << 2;
571 if (super->flags & CRAMFS_FLAG_FSID_VERSION_2) {
572 sbi->size = super->size;
573 sbi->blocks = super->fsid.blocks;
574 sbi->files = super->fsid.files;
575 } else {
576 sbi->size = 1<<28;
577 sbi->blocks = 0;
578 sbi->files = 0;
579 }
580 sbi->magic = super->magic;
581 sbi->flags = super->flags;
582 if (root_offset == 0)
583 infof(fc, "cramfs: empty filesystem");
584 else if (!(super->flags & CRAMFS_FLAG_SHIFTED_ROOT_OFFSET) &&
585 ((root_offset != sizeof(struct cramfs_super)) &&
586 (root_offset != 512 + sizeof(struct cramfs_super))))
587 {
588 errorf(fc, "cramfs: bad root offset %lu", root_offset);
589 return -EINVAL;
590 }
591
592 return 0;
593}
594
595static int cramfs_finalize_super(struct super_block *sb,
596 struct cramfs_inode *cramfs_root)
597{
598 struct inode *root;
599
600 /* Set it all up.. */
601 sb->s_flags |= SB_RDONLY;
602 sb->s_time_min = 0;
603 sb->s_time_max = 0;
604 sb->s_op = &cramfs_ops;
605 root = get_cramfs_inode(sb, cramfs_root, 0);
606 if (IS_ERR(root))
607 return PTR_ERR(root);
608 sb->s_root = d_make_root(root);
609 if (!sb->s_root)
610 return -ENOMEM;
611 return 0;
612}
613
614static int cramfs_blkdev_fill_super(struct super_block *sb, struct fs_context *fc)
615{
616 struct cramfs_sb_info *sbi;
617 struct cramfs_super super;
618 int i, err;
619
620 sbi = kzalloc(sizeof(struct cramfs_sb_info), GFP_KERNEL);
621 if (!sbi)
622 return -ENOMEM;
623 sb->s_fs_info = sbi;
624
625 /* Invalidate the read buffers on mount: think disk change.. */
626 for (i = 0; i < READ_BUFFERS; i++)
627 buffer_blocknr[i] = -1;
628
629 err = cramfs_read_super(sb, fc, &super);
630 if (err)
631 return err;
632 return cramfs_finalize_super(sb, &super.root);
633}
634
635static int cramfs_mtd_fill_super(struct super_block *sb, struct fs_context *fc)
636{
637 struct cramfs_sb_info *sbi;
638 struct cramfs_super super;
639 int err;
640
641 sbi = kzalloc(sizeof(struct cramfs_sb_info), GFP_KERNEL);
642 if (!sbi)
643 return -ENOMEM;
644 sb->s_fs_info = sbi;
645
646 /* Map only one page for now. Will remap it when fs size is known. */
647 err = mtd_point(sb->s_mtd, 0, PAGE_SIZE, &sbi->mtd_point_size,
648 &sbi->linear_virt_addr, &sbi->linear_phys_addr);
649 if (err || sbi->mtd_point_size != PAGE_SIZE) {
650 pr_err("unable to get direct memory access to mtd:%s\n",
651 sb->s_mtd->name);
652 return err ? : -ENODATA;
653 }
654
655 pr_info("checking physical address %pap for linear cramfs image\n",
656 &sbi->linear_phys_addr);
657 err = cramfs_read_super(sb, fc, &super);
658 if (err)
659 return err;
660
661 /* Remap the whole filesystem now */
662 pr_info("linear cramfs image on mtd:%s appears to be %lu KB in size\n",
663 sb->s_mtd->name, sbi->size/1024);
664 mtd_unpoint(sb->s_mtd, 0, PAGE_SIZE);
665 err = mtd_point(sb->s_mtd, 0, sbi->size, &sbi->mtd_point_size,
666 &sbi->linear_virt_addr, &sbi->linear_phys_addr);
667 if (err || sbi->mtd_point_size != sbi->size) {
668 pr_err("unable to get direct memory access to mtd:%s\n",
669 sb->s_mtd->name);
670 return err ? : -ENODATA;
671 }
672
673 return cramfs_finalize_super(sb, &super.root);
674}
675
676static int cramfs_statfs(struct dentry *dentry, struct kstatfs *buf)
677{
678 struct super_block *sb = dentry->d_sb;
679 u64 id = 0;
680
681 if (sb->s_bdev)
682 id = huge_encode_dev(sb->s_bdev->bd_dev);
683 else if (sb->s_dev)
684 id = huge_encode_dev(sb->s_dev);
685
686 buf->f_type = CRAMFS_MAGIC;
687 buf->f_bsize = PAGE_SIZE;
688 buf->f_blocks = CRAMFS_SB(sb)->blocks;
689 buf->f_bfree = 0;
690 buf->f_bavail = 0;
691 buf->f_files = CRAMFS_SB(sb)->files;
692 buf->f_ffree = 0;
693 buf->f_fsid.val[0] = (u32)id;
694 buf->f_fsid.val[1] = (u32)(id >> 32);
695 buf->f_namelen = CRAMFS_MAXPATHLEN;
696 return 0;
697}
698
699/*
700 * Read a cramfs directory entry.
701 */
702static int cramfs_readdir(struct file *file, struct dir_context *ctx)
703{
704 struct inode *inode = file_inode(file);
705 struct super_block *sb = inode->i_sb;
706 char *buf;
707 unsigned int offset;
708
709 /* Offset within the thing. */
710 if (ctx->pos >= inode->i_size)
711 return 0;
712 offset = ctx->pos;
713 /* Directory entries are always 4-byte aligned */
714 if (offset & 3)
715 return -EINVAL;
716
717 buf = kmalloc(CRAMFS_MAXPATHLEN, GFP_KERNEL);
718 if (!buf)
719 return -ENOMEM;
720
721 while (offset < inode->i_size) {
722 struct cramfs_inode *de;
723 unsigned long nextoffset;
724 char *name;
725 ino_t ino;
726 umode_t mode;
727 int namelen;
728
729 mutex_lock(&read_mutex);
730 de = cramfs_read(sb, OFFSET(inode) + offset, sizeof(*de)+CRAMFS_MAXPATHLEN);
731 name = (char *)(de+1);
732
733 /*
734 * Namelengths on disk are shifted by two
735 * and the name padded out to 4-byte boundaries
736 * with zeroes.
737 */
738 namelen = de->namelen << 2;
739 memcpy(buf, name, namelen);
740 ino = cramino(de, OFFSET(inode) + offset);
741 mode = de->mode;
742 mutex_unlock(&read_mutex);
743 nextoffset = offset + sizeof(*de) + namelen;
744 for (;;) {
745 if (!namelen) {
746 kfree(buf);
747 return -EIO;
748 }
749 if (buf[namelen-1])
750 break;
751 namelen--;
752 }
753 if (!dir_emit(ctx, buf, namelen, ino, mode >> 12))
754 break;
755
756 ctx->pos = offset = nextoffset;
757 }
758 kfree(buf);
759 return 0;
760}
761
762/*
763 * Lookup and fill in the inode data..
764 */
765static struct dentry *cramfs_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
766{
767 unsigned int offset = 0;
768 struct inode *inode = NULL;
769 int sorted;
770
771 mutex_lock(&read_mutex);
772 sorted = CRAMFS_SB(dir->i_sb)->flags & CRAMFS_FLAG_SORTED_DIRS;
773 while (offset < dir->i_size) {
774 struct cramfs_inode *de;
775 char *name;
776 int namelen, retval;
777 int dir_off = OFFSET(dir) + offset;
778
779 de = cramfs_read(dir->i_sb, dir_off, sizeof(*de)+CRAMFS_MAXPATHLEN);
780 name = (char *)(de+1);
781
782 /* Try to take advantage of sorted directories */
783 if (sorted && (dentry->d_name.name[0] < name[0]))
784 break;
785
786 namelen = de->namelen << 2;
787 offset += sizeof(*de) + namelen;
788
789 /* Quick check that the name is roughly the right length */
790 if (((dentry->d_name.len + 3) & ~3) != namelen)
791 continue;
792
793 for (;;) {
794 if (!namelen) {
795 inode = ERR_PTR(-EIO);
796 goto out;
797 }
798 if (name[namelen-1])
799 break;
800 namelen--;
801 }
802 if (namelen != dentry->d_name.len)
803 continue;
804 retval = memcmp(dentry->d_name.name, name, namelen);
805 if (retval > 0)
806 continue;
807 if (!retval) {
808 inode = get_cramfs_inode(dir->i_sb, de, dir_off);
809 break;
810 }
811 /* else (retval < 0) */
812 if (sorted)
813 break;
814 }
815out:
816 mutex_unlock(&read_mutex);
817 return d_splice_alias(inode, dentry);
818}
819
820static int cramfs_readpage(struct file *file, struct page *page)
821{
822 struct inode *inode = page->mapping->host;
823 u32 maxblock;
824 int bytes_filled;
825 void *pgdata;
826
827 maxblock = (inode->i_size + PAGE_SIZE - 1) >> PAGE_SHIFT;
828 bytes_filled = 0;
829 pgdata = kmap(page);
830
831 if (page->index < maxblock) {
832 struct super_block *sb = inode->i_sb;
833 u32 blkptr_offset = OFFSET(inode) + page->index * 4;
834 u32 block_ptr, block_start, block_len;
835 bool uncompressed, direct;
836
837 mutex_lock(&read_mutex);
838 block_ptr = *(u32 *) cramfs_read(sb, blkptr_offset, 4);
839 uncompressed = (block_ptr & CRAMFS_BLK_FLAG_UNCOMPRESSED);
840 direct = (block_ptr & CRAMFS_BLK_FLAG_DIRECT_PTR);
841 block_ptr &= ~CRAMFS_BLK_FLAGS;
842
843 if (direct) {
844 /*
845 * The block pointer is an absolute start pointer,
846 * shifted by 2 bits. The size is included in the
847 * first 2 bytes of the data block when compressed,
848 * or PAGE_SIZE otherwise.
849 */
850 block_start = block_ptr << CRAMFS_BLK_DIRECT_PTR_SHIFT;
851 if (uncompressed) {
852 block_len = PAGE_SIZE;
853 /* if last block: cap to file length */
854 if (page->index == maxblock - 1)
855 block_len =
856 offset_in_page(inode->i_size);
857 } else {
858 block_len = *(u16 *)
859 cramfs_read(sb, block_start, 2);
860 block_start += 2;
861 }
862 } else {
863 /*
864 * The block pointer indicates one past the end of
865 * the current block (start of next block). If this
866 * is the first block then it starts where the block
867 * pointer table ends, otherwise its start comes
868 * from the previous block's pointer.
869 */
870 block_start = OFFSET(inode) + maxblock * 4;
871 if (page->index)
872 block_start = *(u32 *)
873 cramfs_read(sb, blkptr_offset - 4, 4);
874 /* Beware... previous ptr might be a direct ptr */
875 if (unlikely(block_start & CRAMFS_BLK_FLAG_DIRECT_PTR)) {
876 /* See comments on earlier code. */
877 u32 prev_start = block_start;
878 block_start = prev_start & ~CRAMFS_BLK_FLAGS;
879 block_start <<= CRAMFS_BLK_DIRECT_PTR_SHIFT;
880 if (prev_start & CRAMFS_BLK_FLAG_UNCOMPRESSED) {
881 block_start += PAGE_SIZE;
882 } else {
883 block_len = *(u16 *)
884 cramfs_read(sb, block_start, 2);
885 block_start += 2 + block_len;
886 }
887 }
888 block_start &= ~CRAMFS_BLK_FLAGS;
889 block_len = block_ptr - block_start;
890 }
891
892 if (block_len == 0)
893 ; /* hole */
894 else if (unlikely(block_len > 2*PAGE_SIZE ||
895 (uncompressed && block_len > PAGE_SIZE))) {
896 mutex_unlock(&read_mutex);
897 pr_err("bad data blocksize %u\n", block_len);
898 goto err;
899 } else if (uncompressed) {
900 memcpy(pgdata,
901 cramfs_read(sb, block_start, block_len),
902 block_len);
903 bytes_filled = block_len;
904 } else {
905 bytes_filled = cramfs_uncompress_block(pgdata,
906 PAGE_SIZE,
907 cramfs_read(sb, block_start, block_len),
908 block_len);
909 }
910 mutex_unlock(&read_mutex);
911 if (unlikely(bytes_filled < 0))
912 goto err;
913 }
914
915 memset(pgdata + bytes_filled, 0, PAGE_SIZE - bytes_filled);
916 flush_dcache_page(page);
917 kunmap(page);
918 SetPageUptodate(page);
919 unlock_page(page);
920 return 0;
921
922err:
923 kunmap(page);
924 ClearPageUptodate(page);
925 SetPageError(page);
926 unlock_page(page);
927 return 0;
928}
929
930static const struct address_space_operations cramfs_aops = {
931 .readpage = cramfs_readpage
932};
933
934/*
935 * Our operations:
936 */
937
938/*
939 * A directory can only readdir
940 */
941static const struct file_operations cramfs_directory_operations = {
942 .llseek = generic_file_llseek,
943 .read = generic_read_dir,
944 .iterate_shared = cramfs_readdir,
945};
946
947static const struct inode_operations cramfs_dir_inode_operations = {
948 .lookup = cramfs_lookup,
949};
950
951static const struct super_operations cramfs_ops = {
952 .statfs = cramfs_statfs,
953};
954
955static int cramfs_get_tree(struct fs_context *fc)
956{
957 int ret = -ENOPROTOOPT;
958
959 if (IS_ENABLED(CONFIG_CRAMFS_MTD)) {
960 ret = get_tree_mtd(fc, cramfs_mtd_fill_super);
961 if (!ret)
962 return 0;
963 }
964 if (IS_ENABLED(CONFIG_CRAMFS_BLOCKDEV))
965 ret = get_tree_bdev(fc, cramfs_blkdev_fill_super);
966 return ret;
967}
968
969static const struct fs_context_operations cramfs_context_ops = {
970 .get_tree = cramfs_get_tree,
971 .reconfigure = cramfs_reconfigure,
972};
973
974/*
975 * Set up the filesystem mount context.
976 */
977static int cramfs_init_fs_context(struct fs_context *fc)
978{
979 fc->ops = &cramfs_context_ops;
980 return 0;
981}
982
983static struct file_system_type cramfs_fs_type = {
984 .owner = THIS_MODULE,
985 .name = "cramfs",
986 .init_fs_context = cramfs_init_fs_context,
987 .kill_sb = cramfs_kill_sb,
988 .fs_flags = FS_REQUIRES_DEV,
989};
990MODULE_ALIAS_FS("cramfs");
991
992static int __init init_cramfs_fs(void)
993{
994 int rv;
995
996 rv = cramfs_uncompress_init();
997 if (rv < 0)
998 return rv;
999 rv = register_filesystem(&cramfs_fs_type);
1000 if (rv < 0)
1001 cramfs_uncompress_exit();
1002 return rv;
1003}
1004
1005static void __exit exit_cramfs_fs(void)
1006{
1007 cramfs_uncompress_exit();
1008 unregister_filesystem(&cramfs_fs_type);
1009}
1010
1011module_init(init_cramfs_fs)
1012module_exit(exit_cramfs_fs)
1013MODULE_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_shared = 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");