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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#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/slab.h>
21#include <linux/vfs.h>
22#include <linux/mutex.h>
23#include <uapi/linux/cramfs_fs.h>
24#include <asm/uaccess.h>
25
26#include "internal.h"
27
28/*
29 * cramfs super-block data in memory
30 */
31struct cramfs_sb_info {
32 unsigned long magic;
33 unsigned long size;
34 unsigned long blocks;
35 unsigned long files;
36 unsigned long flags;
37};
38
39static inline struct cramfs_sb_info *CRAMFS_SB(struct super_block *sb)
40{
41 return sb->s_fs_info;
42}
43
44static const struct super_operations cramfs_ops;
45static const struct inode_operations cramfs_dir_inode_operations;
46static const struct file_operations cramfs_directory_operations;
47static const struct address_space_operations cramfs_aops;
48
49static DEFINE_MUTEX(read_mutex);
50
51
52/* These macros may change in future, to provide better st_ino semantics. */
53#define OFFSET(x) ((x)->i_ino)
54
55static unsigned long cramino(const struct cramfs_inode *cino, unsigned int offset)
56{
57 if (!cino->offset)
58 return offset + 1;
59 if (!cino->size)
60 return offset + 1;
61
62 /*
63 * The file mode test fixes buggy mkcramfs implementations where
64 * cramfs_inode->offset is set to a non zero value for entries
65 * which did not contain data, like devices node and fifos.
66 */
67 switch (cino->mode & S_IFMT) {
68 case S_IFREG:
69 case S_IFDIR:
70 case S_IFLNK:
71 return cino->offset << 2;
72 default:
73 break;
74 }
75 return offset + 1;
76}
77
78static struct inode *get_cramfs_inode(struct super_block *sb,
79 const struct cramfs_inode *cramfs_inode, unsigned int offset)
80{
81 struct inode *inode;
82 static struct timespec zerotime;
83
84 inode = iget_locked(sb, cramino(cramfs_inode, offset));
85 if (!inode)
86 return ERR_PTR(-ENOMEM);
87 if (!(inode->i_state & I_NEW))
88 return inode;
89
90 switch (cramfs_inode->mode & S_IFMT) {
91 case S_IFREG:
92 inode->i_fop = &generic_ro_fops;
93 inode->i_data.a_ops = &cramfs_aops;
94 break;
95 case S_IFDIR:
96 inode->i_op = &cramfs_dir_inode_operations;
97 inode->i_fop = &cramfs_directory_operations;
98 break;
99 case S_IFLNK:
100 inode->i_op = &page_symlink_inode_operations;
101 inode->i_data.a_ops = &cramfs_aops;
102 break;
103 default:
104 init_special_inode(inode, cramfs_inode->mode,
105 old_decode_dev(cramfs_inode->size));
106 }
107
108 inode->i_mode = cramfs_inode->mode;
109 i_uid_write(inode, cramfs_inode->uid);
110 i_gid_write(inode, cramfs_inode->gid);
111
112 /* if the lower 2 bits are zero, the inode contains data */
113 if (!(inode->i_ino & 3)) {
114 inode->i_size = cramfs_inode->size;
115 inode->i_blocks = (cramfs_inode->size - 1) / 512 + 1;
116 }
117
118 /* Struct copy intentional */
119 inode->i_mtime = inode->i_atime = inode->i_ctime = zerotime;
120 /* inode->i_nlink is left 1 - arguably wrong for directories,
121 but it's the best we can do without reading the directory
122 contents. 1 yields the right result in GNU find, even
123 without -noleaf option. */
124
125 unlock_new_inode(inode);
126
127 return inode;
128}
129
130/*
131 * We have our own block cache: don't fill up the buffer cache
132 * with the rom-image, because the way the filesystem is set
133 * up the accesses should be fairly regular and cached in the
134 * page cache and dentry tree anyway..
135 *
136 * This also acts as a way to guarantee contiguous areas of up to
137 * BLKS_PER_BUF*PAGE_CACHE_SIZE, so that the caller doesn't need to
138 * worry about end-of-buffer issues even when decompressing a full
139 * page cache.
140 */
141#define READ_BUFFERS (2)
142/* NEXT_BUFFER(): Loop over [0..(READ_BUFFERS-1)]. */
143#define NEXT_BUFFER(_ix) ((_ix) ^ 1)
144
145/*
146 * BLKS_PER_BUF_SHIFT should be at least 2 to allow for "compressed"
147 * data that takes up more space than the original and with unlucky
148 * alignment.
149 */
150#define BLKS_PER_BUF_SHIFT (2)
151#define BLKS_PER_BUF (1 << BLKS_PER_BUF_SHIFT)
152#define BUFFER_SIZE (BLKS_PER_BUF*PAGE_CACHE_SIZE)
153
154static unsigned char read_buffers[READ_BUFFERS][BUFFER_SIZE];
155static unsigned buffer_blocknr[READ_BUFFERS];
156static struct super_block * buffer_dev[READ_BUFFERS];
157static int next_buffer;
158
159/*
160 * Returns a pointer to a buffer containing at least LEN bytes of
161 * filesystem starting at byte offset OFFSET into the filesystem.
162 */
163static void *cramfs_read(struct super_block *sb, unsigned int offset, unsigned int len)
164{
165 struct address_space *mapping = sb->s_bdev->bd_inode->i_mapping;
166 struct page *pages[BLKS_PER_BUF];
167 unsigned i, blocknr, buffer;
168 unsigned long devsize;
169 char *data;
170
171 if (!len)
172 return NULL;
173 blocknr = offset >> PAGE_CACHE_SHIFT;
174 offset &= PAGE_CACHE_SIZE - 1;
175
176 /* Check if an existing buffer already has the data.. */
177 for (i = 0; i < READ_BUFFERS; i++) {
178 unsigned int blk_offset;
179
180 if (buffer_dev[i] != sb)
181 continue;
182 if (blocknr < buffer_blocknr[i])
183 continue;
184 blk_offset = (blocknr - buffer_blocknr[i]) << PAGE_CACHE_SHIFT;
185 blk_offset += offset;
186 if (blk_offset + len > BUFFER_SIZE)
187 continue;
188 return read_buffers[i] + blk_offset;
189 }
190
191 devsize = mapping->host->i_size >> PAGE_CACHE_SHIFT;
192
193 /* Ok, read in BLKS_PER_BUF pages completely first. */
194 for (i = 0; i < BLKS_PER_BUF; i++) {
195 struct page *page = NULL;
196
197 if (blocknr + i < devsize) {
198 page = read_mapping_page(mapping, blocknr + i, NULL);
199 /* synchronous error? */
200 if (IS_ERR(page))
201 page = NULL;
202 }
203 pages[i] = page;
204 }
205
206 for (i = 0; i < BLKS_PER_BUF; i++) {
207 struct page *page = pages[i];
208 if (page) {
209 wait_on_page_locked(page);
210 if (!PageUptodate(page)) {
211 /* asynchronous error */
212 page_cache_release(page);
213 pages[i] = NULL;
214 }
215 }
216 }
217
218 buffer = next_buffer;
219 next_buffer = NEXT_BUFFER(buffer);
220 buffer_blocknr[buffer] = blocknr;
221 buffer_dev[buffer] = sb;
222
223 data = read_buffers[buffer];
224 for (i = 0; i < BLKS_PER_BUF; i++) {
225 struct page *page = pages[i];
226 if (page) {
227 memcpy(data, kmap(page), PAGE_CACHE_SIZE);
228 kunmap(page);
229 page_cache_release(page);
230 } else
231 memset(data, 0, PAGE_CACHE_SIZE);
232 data += PAGE_CACHE_SIZE;
233 }
234 return read_buffers[buffer] + offset;
235}
236
237static void cramfs_kill_sb(struct super_block *sb)
238{
239 struct cramfs_sb_info *sbi = CRAMFS_SB(sb);
240 kill_block_super(sb);
241 kfree(sbi);
242}
243
244static int cramfs_remount(struct super_block *sb, int *flags, char *data)
245{
246 sync_filesystem(sb);
247 *flags |= MS_RDONLY;
248 return 0;
249}
250
251static int cramfs_fill_super(struct super_block *sb, void *data, int silent)
252{
253 int i;
254 struct cramfs_super super;
255 unsigned long root_offset;
256 struct cramfs_sb_info *sbi;
257 struct inode *root;
258
259 sb->s_flags |= MS_RDONLY;
260
261 sbi = kzalloc(sizeof(struct cramfs_sb_info), GFP_KERNEL);
262 if (!sbi)
263 return -ENOMEM;
264 sb->s_fs_info = sbi;
265
266 /* Invalidate the read buffers on mount: think disk change.. */
267 mutex_lock(&read_mutex);
268 for (i = 0; i < READ_BUFFERS; i++)
269 buffer_blocknr[i] = -1;
270
271 /* Read the first block and get the superblock from it */
272 memcpy(&super, cramfs_read(sb, 0, sizeof(super)), sizeof(super));
273 mutex_unlock(&read_mutex);
274
275 /* Do sanity checks on the superblock */
276 if (super.magic != CRAMFS_MAGIC) {
277 /* check for wrong endianness */
278 if (super.magic == CRAMFS_MAGIC_WEND) {
279 if (!silent)
280 printk(KERN_ERR "cramfs: wrong endianness\n");
281 return -EINVAL;
282 }
283
284 /* check at 512 byte offset */
285 mutex_lock(&read_mutex);
286 memcpy(&super, cramfs_read(sb, 512, sizeof(super)), sizeof(super));
287 mutex_unlock(&read_mutex);
288 if (super.magic != CRAMFS_MAGIC) {
289 if (super.magic == CRAMFS_MAGIC_WEND && !silent)
290 printk(KERN_ERR "cramfs: wrong endianness\n");
291 else if (!silent)
292 printk(KERN_ERR "cramfs: wrong magic\n");
293 return -EINVAL;
294 }
295 }
296
297 /* get feature flags first */
298 if (super.flags & ~CRAMFS_SUPPORTED_FLAGS) {
299 printk(KERN_ERR "cramfs: unsupported filesystem features\n");
300 return -EINVAL;
301 }
302
303 /* Check that the root inode is in a sane state */
304 if (!S_ISDIR(super.root.mode)) {
305 printk(KERN_ERR "cramfs: root is not a directory\n");
306 return -EINVAL;
307 }
308 /* correct strange, hard-coded permissions of mkcramfs */
309 super.root.mode |= (S_IRUSR | S_IXUSR | S_IRGRP | S_IXGRP | S_IROTH | S_IXOTH);
310
311 root_offset = super.root.offset << 2;
312 if (super.flags & CRAMFS_FLAG_FSID_VERSION_2) {
313 sbi->size=super.size;
314 sbi->blocks=super.fsid.blocks;
315 sbi->files=super.fsid.files;
316 } else {
317 sbi->size=1<<28;
318 sbi->blocks=0;
319 sbi->files=0;
320 }
321 sbi->magic=super.magic;
322 sbi->flags=super.flags;
323 if (root_offset == 0)
324 printk(KERN_INFO "cramfs: empty filesystem");
325 else if (!(super.flags & CRAMFS_FLAG_SHIFTED_ROOT_OFFSET) &&
326 ((root_offset != sizeof(struct cramfs_super)) &&
327 (root_offset != 512 + sizeof(struct cramfs_super))))
328 {
329 printk(KERN_ERR "cramfs: bad root offset %lu\n", root_offset);
330 return -EINVAL;
331 }
332
333 /* Set it all up.. */
334 sb->s_op = &cramfs_ops;
335 root = get_cramfs_inode(sb, &super.root, 0);
336 if (IS_ERR(root))
337 return PTR_ERR(root);
338 sb->s_root = d_make_root(root);
339 if (!sb->s_root)
340 return -ENOMEM;
341 return 0;
342}
343
344static int cramfs_statfs(struct dentry *dentry, struct kstatfs *buf)
345{
346 struct super_block *sb = dentry->d_sb;
347 u64 id = huge_encode_dev(sb->s_bdev->bd_dev);
348
349 buf->f_type = CRAMFS_MAGIC;
350 buf->f_bsize = PAGE_CACHE_SIZE;
351 buf->f_blocks = CRAMFS_SB(sb)->blocks;
352 buf->f_bfree = 0;
353 buf->f_bavail = 0;
354 buf->f_files = CRAMFS_SB(sb)->files;
355 buf->f_ffree = 0;
356 buf->f_fsid.val[0] = (u32)id;
357 buf->f_fsid.val[1] = (u32)(id >> 32);
358 buf->f_namelen = CRAMFS_MAXPATHLEN;
359 return 0;
360}
361
362/*
363 * Read a cramfs directory entry.
364 */
365static int cramfs_readdir(struct file *file, struct dir_context *ctx)
366{
367 struct inode *inode = file_inode(file);
368 struct super_block *sb = inode->i_sb;
369 char *buf;
370 unsigned int offset;
371
372 /* Offset within the thing. */
373 if (ctx->pos >= inode->i_size)
374 return 0;
375 offset = ctx->pos;
376 /* Directory entries are always 4-byte aligned */
377 if (offset & 3)
378 return -EINVAL;
379
380 buf = kmalloc(CRAMFS_MAXPATHLEN, GFP_KERNEL);
381 if (!buf)
382 return -ENOMEM;
383
384 while (offset < inode->i_size) {
385 struct cramfs_inode *de;
386 unsigned long nextoffset;
387 char *name;
388 ino_t ino;
389 umode_t mode;
390 int namelen;
391
392 mutex_lock(&read_mutex);
393 de = cramfs_read(sb, OFFSET(inode) + offset, sizeof(*de)+CRAMFS_MAXPATHLEN);
394 name = (char *)(de+1);
395
396 /*
397 * Namelengths on disk are shifted by two
398 * and the name padded out to 4-byte boundaries
399 * with zeroes.
400 */
401 namelen = de->namelen << 2;
402 memcpy(buf, name, namelen);
403 ino = cramino(de, OFFSET(inode) + offset);
404 mode = de->mode;
405 mutex_unlock(&read_mutex);
406 nextoffset = offset + sizeof(*de) + namelen;
407 for (;;) {
408 if (!namelen) {
409 kfree(buf);
410 return -EIO;
411 }
412 if (buf[namelen-1])
413 break;
414 namelen--;
415 }
416 if (!dir_emit(ctx, buf, namelen, ino, mode >> 12))
417 break;
418
419 ctx->pos = offset = nextoffset;
420 }
421 kfree(buf);
422 return 0;
423}
424
425/*
426 * Lookup and fill in the inode data..
427 */
428static struct dentry * cramfs_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
429{
430 unsigned int offset = 0;
431 struct inode *inode = NULL;
432 int sorted;
433
434 mutex_lock(&read_mutex);
435 sorted = CRAMFS_SB(dir->i_sb)->flags & CRAMFS_FLAG_SORTED_DIRS;
436 while (offset < dir->i_size) {
437 struct cramfs_inode *de;
438 char *name;
439 int namelen, retval;
440 int dir_off = OFFSET(dir) + offset;
441
442 de = cramfs_read(dir->i_sb, dir_off, sizeof(*de)+CRAMFS_MAXPATHLEN);
443 name = (char *)(de+1);
444
445 /* Try to take advantage of sorted directories */
446 if (sorted && (dentry->d_name.name[0] < name[0]))
447 break;
448
449 namelen = de->namelen << 2;
450 offset += sizeof(*de) + namelen;
451
452 /* Quick check that the name is roughly the right length */
453 if (((dentry->d_name.len + 3) & ~3) != namelen)
454 continue;
455
456 for (;;) {
457 if (!namelen) {
458 inode = ERR_PTR(-EIO);
459 goto out;
460 }
461 if (name[namelen-1])
462 break;
463 namelen--;
464 }
465 if (namelen != dentry->d_name.len)
466 continue;
467 retval = memcmp(dentry->d_name.name, name, namelen);
468 if (retval > 0)
469 continue;
470 if (!retval) {
471 inode = get_cramfs_inode(dir->i_sb, de, dir_off);
472 break;
473 }
474 /* else (retval < 0) */
475 if (sorted)
476 break;
477 }
478out:
479 mutex_unlock(&read_mutex);
480 if (IS_ERR(inode))
481 return ERR_CAST(inode);
482 d_add(dentry, inode);
483 return NULL;
484}
485
486static int cramfs_readpage(struct file *file, struct page * page)
487{
488 struct inode *inode = page->mapping->host;
489 u32 maxblock;
490 int bytes_filled;
491 void *pgdata;
492
493 maxblock = (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
494 bytes_filled = 0;
495 pgdata = kmap(page);
496
497 if (page->index < maxblock) {
498 struct super_block *sb = inode->i_sb;
499 u32 blkptr_offset = OFFSET(inode) + page->index*4;
500 u32 start_offset, compr_len;
501
502 start_offset = OFFSET(inode) + maxblock*4;
503 mutex_lock(&read_mutex);
504 if (page->index)
505 start_offset = *(u32 *) cramfs_read(sb, blkptr_offset-4,
506 4);
507 compr_len = (*(u32 *) cramfs_read(sb, blkptr_offset, 4) -
508 start_offset);
509 mutex_unlock(&read_mutex);
510
511 if (compr_len == 0)
512 ; /* hole */
513 else if (unlikely(compr_len > (PAGE_CACHE_SIZE << 1))) {
514 pr_err("cramfs: bad compressed blocksize %u\n",
515 compr_len);
516 goto err;
517 } else {
518 mutex_lock(&read_mutex);
519 bytes_filled = cramfs_uncompress_block(pgdata,
520 PAGE_CACHE_SIZE,
521 cramfs_read(sb, start_offset, compr_len),
522 compr_len);
523 mutex_unlock(&read_mutex);
524 if (unlikely(bytes_filled < 0))
525 goto err;
526 }
527 }
528
529 memset(pgdata + bytes_filled, 0, PAGE_CACHE_SIZE - bytes_filled);
530 flush_dcache_page(page);
531 kunmap(page);
532 SetPageUptodate(page);
533 unlock_page(page);
534 return 0;
535
536err:
537 kunmap(page);
538 ClearPageUptodate(page);
539 SetPageError(page);
540 unlock_page(page);
541 return 0;
542}
543
544static const struct address_space_operations cramfs_aops = {
545 .readpage = cramfs_readpage
546};
547
548/*
549 * Our operations:
550 */
551
552/*
553 * A directory can only readdir
554 */
555static const struct file_operations cramfs_directory_operations = {
556 .llseek = generic_file_llseek,
557 .read = generic_read_dir,
558 .iterate = cramfs_readdir,
559};
560
561static const struct inode_operations cramfs_dir_inode_operations = {
562 .lookup = cramfs_lookup,
563};
564
565static const struct super_operations cramfs_ops = {
566 .remount_fs = cramfs_remount,
567 .statfs = cramfs_statfs,
568};
569
570static struct dentry *cramfs_mount(struct file_system_type *fs_type,
571 int flags, const char *dev_name, void *data)
572{
573 return mount_bdev(fs_type, flags, dev_name, data, cramfs_fill_super);
574}
575
576static struct file_system_type cramfs_fs_type = {
577 .owner = THIS_MODULE,
578 .name = "cramfs",
579 .mount = cramfs_mount,
580 .kill_sb = cramfs_kill_sb,
581 .fs_flags = FS_REQUIRES_DEV,
582};
583MODULE_ALIAS_FS("cramfs");
584
585static int __init init_cramfs_fs(void)
586{
587 int rv;
588
589 rv = cramfs_uncompress_init();
590 if (rv < 0)
591 return rv;
592 rv = register_filesystem(&cramfs_fs_type);
593 if (rv < 0)
594 cramfs_uncompress_exit();
595 return rv;
596}
597
598static void __exit exit_cramfs_fs(void)
599{
600 cramfs_uncompress_exit();
601 unregister_filesystem(&cramfs_fs_type);
602}
603
604module_init(init_cramfs_fs)
605module_exit(exit_cramfs_fs)
606MODULE_LICENSE("GPL");