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[mirror_ubuntu-bionic-kernel.git] / fs / cramfs / inode.c
CommitLineData
1da177e4
LT
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
4f21e1ea
FF
14#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
15
1da177e4
LT
16#include <linux/module.h>
17#include <linux/fs.h>
eddcd976 18#include <linux/file.h>
1da177e4 19#include <linux/pagemap.h>
eddcd976
NP
20#include <linux/pfn_t.h>
21#include <linux/ramfs.h>
1da177e4
LT
22#include <linux/init.h>
23#include <linux/string.h>
24#include <linux/blkdev.h>
99c18ce5
NP
25#include <linux/mtd/mtd.h>
26#include <linux/mtd/super.h>
1da177e4 27#include <linux/slab.h>
1da177e4 28#include <linux/vfs.h>
353ab6e9 29#include <linux/mutex.h>
f7f4f4dd 30#include <uapi/linux/cramfs_fs.h>
1508f3eb 31#include <linux/uaccess.h>
1da177e4 32
f7f4f4dd
AV
33#include "internal.h"
34
35/*
36 * cramfs super-block data in memory
37 */
38struct cramfs_sb_info {
39 unsigned long magic;
40 unsigned long size;
41 unsigned long blocks;
42 unsigned long files;
43 unsigned long flags;
99c18ce5
NP
44 void *linear_virt_addr;
45 resource_size_t linear_phys_addr;
46 size_t mtd_point_size;
f7f4f4dd
AV
47};
48
49static inline struct cramfs_sb_info *CRAMFS_SB(struct super_block *sb)
50{
51 return sb->s_fs_info;
52}
53
ee9b6d61 54static const struct super_operations cramfs_ops;
754661f1 55static const struct inode_operations cramfs_dir_inode_operations;
4b6f5d20 56static const struct file_operations cramfs_directory_operations;
eddcd976 57static const struct file_operations cramfs_physmem_fops;
f5e54d6e 58static const struct address_space_operations cramfs_aops;
1da177e4 59
353ab6e9 60static DEFINE_MUTEX(read_mutex);
1da177e4
LT
61
62
6f772fe6 63/* These macros may change in future, to provide better st_ino semantics. */
1da177e4
LT
64#define OFFSET(x) ((x)->i_ino)
65
0577d1ba 66static unsigned long cramino(const struct cramfs_inode *cino, unsigned int offset)
a97c9bf3 67{
6f772fe6
SS
68 if (!cino->offset)
69 return offset + 1;
70 if (!cino->size)
71 return offset + 1;
72
73 /*
74 * The file mode test fixes buggy mkcramfs implementations where
75 * cramfs_inode->offset is set to a non zero value for entries
76 * which did not contain data, like devices node and fifos.
77 */
78 switch (cino->mode & S_IFMT) {
79 case S_IFREG:
80 case S_IFDIR:
81 case S_IFLNK:
82 return cino->offset << 2;
83 default:
84 break;
85 }
86 return offset + 1;
87}
88
89static struct inode *get_cramfs_inode(struct super_block *sb,
0577d1ba 90 const struct cramfs_inode *cramfs_inode, unsigned int offset)
6f772fe6
SS
91{
92 struct inode *inode;
77b8a75f 93 static struct timespec zerotime;
6f772fe6
SS
94
95 inode = iget_locked(sb, cramino(cramfs_inode, offset));
96 if (!inode)
97 return ERR_PTR(-ENOMEM);
98 if (!(inode->i_state & I_NEW))
99 return inode;
100
101 switch (cramfs_inode->mode & S_IFMT) {
102 case S_IFREG:
103 inode->i_fop = &generic_ro_fops;
104 inode->i_data.a_ops = &cramfs_aops;
eddcd976
NP
105 if (IS_ENABLED(CONFIG_CRAMFS_MTD) &&
106 CRAMFS_SB(sb)->flags & CRAMFS_FLAG_EXT_BLOCK_POINTERS &&
107 CRAMFS_SB(sb)->linear_phys_addr)
108 inode->i_fop = &cramfs_physmem_fops;
6f772fe6
SS
109 break;
110 case S_IFDIR:
111 inode->i_op = &cramfs_dir_inode_operations;
112 inode->i_fop = &cramfs_directory_operations;
113 break;
114 case S_IFLNK:
115 inode->i_op = &page_symlink_inode_operations;
21fc61c7 116 inode_nohighmem(inode);
6f772fe6
SS
117 inode->i_data.a_ops = &cramfs_aops;
118 break;
119 default:
120 init_special_inode(inode, cramfs_inode->mode,
121 old_decode_dev(cramfs_inode->size));
122 }
123
77b8a75f 124 inode->i_mode = cramfs_inode->mode;
a7d9cfe9
EB
125 i_uid_write(inode, cramfs_inode->uid);
126 i_gid_write(inode, cramfs_inode->gid);
6f772fe6
SS
127
128 /* if the lower 2 bits are zero, the inode contains data */
129 if (!(inode->i_ino & 3)) {
130 inode->i_size = cramfs_inode->size;
131 inode->i_blocks = (cramfs_inode->size - 1) / 512 + 1;
132 }
133
77b8a75f
AV
134 /* Struct copy intentional */
135 inode->i_mtime = inode->i_atime = inode->i_ctime = zerotime;
136 /* inode->i_nlink is left 1 - arguably wrong for directories,
137 but it's the best we can do without reading the directory
138 contents. 1 yields the right result in GNU find, even
139 without -noleaf option. */
a97c9bf3 140
6f772fe6
SS
141 unlock_new_inode(inode);
142
1da177e4
LT
143 return inode;
144}
145
146/*
147 * We have our own block cache: don't fill up the buffer cache
148 * with the rom-image, because the way the filesystem is set
149 * up the accesses should be fairly regular and cached in the
150 * page cache and dentry tree anyway..
151 *
152 * This also acts as a way to guarantee contiguous areas of up to
ea1754a0 153 * BLKS_PER_BUF*PAGE_SIZE, so that the caller doesn't need to
1da177e4
LT
154 * worry about end-of-buffer issues even when decompressing a full
155 * page cache.
99c18ce5
NP
156 *
157 * Note: This is all optimized away at compile time when
158 * CONFIG_CRAMFS_BLOCKDEV=n.
1da177e4
LT
159 */
160#define READ_BUFFERS (2)
161/* NEXT_BUFFER(): Loop over [0..(READ_BUFFERS-1)]. */
162#define NEXT_BUFFER(_ix) ((_ix) ^ 1)
163
164/*
165 * BLKS_PER_BUF_SHIFT should be at least 2 to allow for "compressed"
166 * data that takes up more space than the original and with unlucky
167 * alignment.
168 */
169#define BLKS_PER_BUF_SHIFT (2)
170#define BLKS_PER_BUF (1 << BLKS_PER_BUF_SHIFT)
09cbfeaf 171#define BUFFER_SIZE (BLKS_PER_BUF*PAGE_SIZE)
1da177e4
LT
172
173static unsigned char read_buffers[READ_BUFFERS][BUFFER_SIZE];
174static unsigned buffer_blocknr[READ_BUFFERS];
31d92e55 175static struct super_block *buffer_dev[READ_BUFFERS];
1da177e4
LT
176static int next_buffer;
177
178/*
99c18ce5 179 * Populate our block cache and return a pointer to it.
1da177e4 180 */
99c18ce5
NP
181static void *cramfs_blkdev_read(struct super_block *sb, unsigned int offset,
182 unsigned int len)
1da177e4
LT
183{
184 struct address_space *mapping = sb->s_bdev->bd_inode->i_mapping;
185 struct page *pages[BLKS_PER_BUF];
6bbfb077 186 unsigned i, blocknr, buffer;
1da177e4
LT
187 unsigned long devsize;
188 char *data;
189
190 if (!len)
191 return NULL;
09cbfeaf
KS
192 blocknr = offset >> PAGE_SHIFT;
193 offset &= PAGE_SIZE - 1;
1da177e4
LT
194
195 /* Check if an existing buffer already has the data.. */
196 for (i = 0; i < READ_BUFFERS; i++) {
197 unsigned int blk_offset;
198
199 if (buffer_dev[i] != sb)
200 continue;
201 if (blocknr < buffer_blocknr[i])
202 continue;
09cbfeaf 203 blk_offset = (blocknr - buffer_blocknr[i]) << PAGE_SHIFT;
1da177e4 204 blk_offset += offset;
930c647d
NP
205 if (blk_offset > BUFFER_SIZE ||
206 blk_offset + len > BUFFER_SIZE)
1da177e4
LT
207 continue;
208 return read_buffers[i] + blk_offset;
209 }
210
09cbfeaf 211 devsize = mapping->host->i_size >> PAGE_SHIFT;
1da177e4
LT
212
213 /* Ok, read in BLKS_PER_BUF pages completely first. */
1da177e4
LT
214 for (i = 0; i < BLKS_PER_BUF; i++) {
215 struct page *page = NULL;
216
217 if (blocknr + i < devsize) {
67f9fd91 218 page = read_mapping_page(mapping, blocknr + i, NULL);
1da177e4
LT
219 /* synchronous error? */
220 if (IS_ERR(page))
221 page = NULL;
222 }
223 pages[i] = page;
224 }
225
226 for (i = 0; i < BLKS_PER_BUF; i++) {
227 struct page *page = pages[i];
31d92e55 228
1da177e4
LT
229 if (page) {
230 wait_on_page_locked(page);
231 if (!PageUptodate(page)) {
232 /* asynchronous error */
09cbfeaf 233 put_page(page);
1da177e4
LT
234 pages[i] = NULL;
235 }
236 }
237 }
238
239 buffer = next_buffer;
240 next_buffer = NEXT_BUFFER(buffer);
241 buffer_blocknr[buffer] = blocknr;
242 buffer_dev[buffer] = sb;
243
244 data = read_buffers[buffer];
245 for (i = 0; i < BLKS_PER_BUF; i++) {
246 struct page *page = pages[i];
31d92e55 247
1da177e4 248 if (page) {
09cbfeaf 249 memcpy(data, kmap(page), PAGE_SIZE);
1da177e4 250 kunmap(page);
09cbfeaf 251 put_page(page);
1da177e4 252 } else
09cbfeaf
KS
253 memset(data, 0, PAGE_SIZE);
254 data += PAGE_SIZE;
1da177e4
LT
255 }
256 return read_buffers[buffer] + offset;
257}
258
99c18ce5
NP
259/*
260 * Return a pointer to the linearly addressed cramfs image in memory.
261 */
262static void *cramfs_direct_read(struct super_block *sb, unsigned int offset,
263 unsigned int len)
264{
265 struct cramfs_sb_info *sbi = CRAMFS_SB(sb);
266
267 if (!len)
268 return NULL;
269 if (len > sbi->size || offset > sbi->size - len)
270 return page_address(ZERO_PAGE(0));
271 return sbi->linear_virt_addr + offset;
272}
273
274/*
275 * Returns a pointer to a buffer containing at least LEN bytes of
276 * filesystem starting at byte offset OFFSET into the filesystem.
277 */
278static void *cramfs_read(struct super_block *sb, unsigned int offset,
279 unsigned int len)
280{
281 struct cramfs_sb_info *sbi = CRAMFS_SB(sb);
282
283 if (IS_ENABLED(CONFIG_CRAMFS_MTD) && sbi->linear_virt_addr)
284 return cramfs_direct_read(sb, offset, len);
285 else if (IS_ENABLED(CONFIG_CRAMFS_BLOCKDEV))
286 return cramfs_blkdev_read(sb, offset, len);
287 else
288 return NULL;
289}
290
eddcd976
NP
291/*
292 * For a mapping to be possible, we need a range of uncompressed and
293 * contiguous blocks. Return the offset for the first block and number of
294 * valid blocks for which that is true, or zero otherwise.
295 */
296static u32 cramfs_get_block_range(struct inode *inode, u32 pgoff, u32 *pages)
297{
298 struct cramfs_sb_info *sbi = CRAMFS_SB(inode->i_sb);
299 int i;
300 u32 *blockptrs, first_block_addr;
301
302 /*
303 * We can dereference memory directly here as this code may be
304 * reached only when there is a direct filesystem image mapping
305 * available in memory.
306 */
307 blockptrs = (u32 *)(sbi->linear_virt_addr + OFFSET(inode) + pgoff * 4);
308 first_block_addr = blockptrs[0] & ~CRAMFS_BLK_FLAGS;
309 i = 0;
310 do {
311 u32 block_off = i * (PAGE_SIZE >> CRAMFS_BLK_DIRECT_PTR_SHIFT);
312 u32 expect = (first_block_addr + block_off) |
313 CRAMFS_BLK_FLAG_DIRECT_PTR |
314 CRAMFS_BLK_FLAG_UNCOMPRESSED;
315 if (blockptrs[i] != expect) {
316 pr_debug("range: block %d/%d got %#x expects %#x\n",
317 pgoff+i, pgoff + *pages - 1,
318 blockptrs[i], expect);
319 if (i == 0)
320 return 0;
321 break;
322 }
323 } while (++i < *pages);
324
325 *pages = i;
326 return first_block_addr << CRAMFS_BLK_DIRECT_PTR_SHIFT;
327}
328
329#ifdef CONFIG_MMU
330
331/*
332 * Return true if the last page of a file in the filesystem image contains
333 * some other data that doesn't belong to that file. It is assumed that the
334 * last block is CRAMFS_BLK_FLAG_DIRECT_PTR | CRAMFS_BLK_FLAG_UNCOMPRESSED
335 * (verified by cramfs_get_block_range() and directly accessible in memory.
336 */
337static bool cramfs_last_page_is_shared(struct inode *inode)
338{
339 struct cramfs_sb_info *sbi = CRAMFS_SB(inode->i_sb);
340 u32 partial, last_page, blockaddr, *blockptrs;
341 char *tail_data;
342
343 partial = offset_in_page(inode->i_size);
344 if (!partial)
345 return false;
346 last_page = inode->i_size >> PAGE_SHIFT;
347 blockptrs = (u32 *)(sbi->linear_virt_addr + OFFSET(inode));
348 blockaddr = blockptrs[last_page] & ~CRAMFS_BLK_FLAGS;
349 blockaddr <<= CRAMFS_BLK_DIRECT_PTR_SHIFT;
350 tail_data = sbi->linear_virt_addr + blockaddr + partial;
351 return memchr_inv(tail_data, 0, PAGE_SIZE - partial) ? true : false;
352}
353
354static int cramfs_physmem_mmap(struct file *file, struct vm_area_struct *vma)
355{
356 struct inode *inode = file_inode(file);
357 struct cramfs_sb_info *sbi = CRAMFS_SB(inode->i_sb);
358 unsigned int pages, max_pages, offset;
359 unsigned long address, pgoff = vma->vm_pgoff;
360 char *bailout_reason;
361 int ret;
362
363 ret = generic_file_readonly_mmap(file, vma);
364 if (ret)
365 return ret;
366
367 /*
368 * Now try to pre-populate ptes for this vma with a direct
369 * mapping avoiding memory allocation when possible.
370 */
371
372 /* Could COW work here? */
373 bailout_reason = "vma is writable";
374 if (vma->vm_flags & VM_WRITE)
375 goto bailout;
376
377 max_pages = (inode->i_size + PAGE_SIZE - 1) >> PAGE_SHIFT;
378 bailout_reason = "beyond file limit";
379 if (pgoff >= max_pages)
380 goto bailout;
381 pages = min(vma_pages(vma), max_pages - pgoff);
382
383 offset = cramfs_get_block_range(inode, pgoff, &pages);
384 bailout_reason = "unsuitable block layout";
385 if (!offset)
386 goto bailout;
387 address = sbi->linear_phys_addr + offset;
388 bailout_reason = "data is not page aligned";
389 if (!PAGE_ALIGNED(address))
390 goto bailout;
391
392 /* Don't map the last page if it contains some other data */
393 if (pgoff + pages == max_pages && cramfs_last_page_is_shared(inode)) {
394 pr_debug("mmap: %s: last page is shared\n",
395 file_dentry(file)->d_name.name);
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 unsigned long off = i * PAGE_SIZE;
423 pfn_t pfn = phys_to_pfn_t(address + off, PFN_DEV);
424 ret = vm_insert_mixed(vma, vma->vm_start + off, pfn);
425 }
426 }
427
428 if (!ret)
429 pr_debug("mapped %s[%lu] at 0x%08lx (%u/%lu pages) "
430 "to vma 0x%08lx, page_prot 0x%llx\n",
431 file_dentry(file)->d_name.name, pgoff,
432 address, pages, vma_pages(vma), vma->vm_start,
433 (unsigned long long)pgprot_val(vma->vm_page_prot));
434 return ret;
435
436bailout:
437 pr_debug("%s[%lu]: direct mmap impossible: %s\n",
438 file_dentry(file)->d_name.name, pgoff, bailout_reason);
439 /* Didn't manage any direct map, but normal paging is still possible */
440 return 0;
441}
442
443#else /* CONFIG_MMU */
444
445static int cramfs_physmem_mmap(struct file *file, struct vm_area_struct *vma)
446{
447 return vma->vm_flags & (VM_SHARED | VM_MAYSHARE) ? 0 : -ENOSYS;
448}
449
450static unsigned long cramfs_physmem_get_unmapped_area(struct file *file,
451 unsigned long addr, unsigned long len,
452 unsigned long pgoff, unsigned long flags)
453{
454 struct inode *inode = file_inode(file);
455 struct super_block *sb = inode->i_sb;
456 struct cramfs_sb_info *sbi = CRAMFS_SB(sb);
457 unsigned int pages, block_pages, max_pages, offset;
458
459 pages = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
460 max_pages = (inode->i_size + PAGE_SIZE - 1) >> PAGE_SHIFT;
461 if (pgoff >= max_pages || pages > max_pages - pgoff)
462 return -EINVAL;
463 block_pages = pages;
464 offset = cramfs_get_block_range(inode, pgoff, &block_pages);
465 if (!offset || block_pages != pages)
466 return -ENOSYS;
467 addr = sbi->linear_phys_addr + offset;
468 pr_debug("get_unmapped for %s ofs %#lx siz %lu at 0x%08lx\n",
469 file_dentry(file)->d_name.name, pgoff*PAGE_SIZE, len, addr);
470 return addr;
471}
472
473static unsigned int cramfs_physmem_mmap_capabilities(struct file *file)
474{
475 return NOMMU_MAP_COPY | NOMMU_MAP_DIRECT |
476 NOMMU_MAP_READ | NOMMU_MAP_EXEC;
477}
478
479#endif /* CONFIG_MMU */
480
481static const struct file_operations cramfs_physmem_fops = {
482 .llseek = generic_file_llseek,
483 .read_iter = generic_file_read_iter,
484 .splice_read = generic_file_splice_read,
485 .mmap = cramfs_physmem_mmap,
486#ifndef CONFIG_MMU
487 .get_unmapped_area = cramfs_physmem_get_unmapped_area,
488 .mmap_capabilities = cramfs_physmem_mmap_capabilities,
489#endif
490};
491
2309fb8e 492static void cramfs_kill_sb(struct super_block *sb)
1da177e4 493{
f7f4f4dd 494 struct cramfs_sb_info *sbi = CRAMFS_SB(sb);
31d92e55 495
99c18ce5
NP
496 if (IS_ENABLED(CCONFIG_CRAMFS_MTD) && sb->s_mtd) {
497 if (sbi && sbi->mtd_point_size)
498 mtd_unpoint(sb->s_mtd, 0, sbi->mtd_point_size);
499 kill_mtd_super(sb);
500 } else if (IS_ENABLED(CONFIG_CRAMFS_BLOCKDEV) && sb->s_bdev) {
501 kill_block_super(sb);
502 }
2309fb8e 503 kfree(sbi);
1da177e4
LT
504}
505
506static int cramfs_remount(struct super_block *sb, int *flags, char *data)
507{
02b9984d 508 sync_filesystem(sb);
1751e8a6 509 *flags |= SB_RDONLY;
1da177e4
LT
510 return 0;
511}
512
99c18ce5
NP
513static int cramfs_read_super(struct super_block *sb,
514 struct cramfs_super *super, int silent)
1da177e4 515{
99c18ce5 516 struct cramfs_sb_info *sbi = CRAMFS_SB(sb);
1da177e4 517 unsigned long root_offset;
1da177e4 518
99c18ce5
NP
519 /* We don't know the real size yet */
520 sbi->size = PAGE_SIZE;
1da177e4
LT
521
522 /* Read the first block and get the superblock from it */
99c18ce5
NP
523 mutex_lock(&read_mutex);
524 memcpy(super, cramfs_read(sb, 0, sizeof(*super)), sizeof(*super));
353ab6e9 525 mutex_unlock(&read_mutex);
1da177e4
LT
526
527 /* Do sanity checks on the superblock */
99c18ce5 528 if (super->magic != CRAMFS_MAGIC) {
0cc785ec 529 /* check for wrong endianness */
99c18ce5 530 if (super->magic == CRAMFS_MAGIC_WEND) {
ac8d35c5 531 if (!silent)
4f21e1ea 532 pr_err("wrong endianness\n");
2309fb8e 533 return -EINVAL;
ac8d35c5
AD
534 }
535
1da177e4 536 /* check at 512 byte offset */
353ab6e9 537 mutex_lock(&read_mutex);
99c18ce5
NP
538 memcpy(super,
539 cramfs_read(sb, 512, sizeof(*super)),
540 sizeof(*super));
353ab6e9 541 mutex_unlock(&read_mutex);
99c18ce5
NP
542 if (super->magic != CRAMFS_MAGIC) {
543 if (super->magic == CRAMFS_MAGIC_WEND && !silent)
4f21e1ea 544 pr_err("wrong endianness\n");
ac8d35c5 545 else if (!silent)
4f21e1ea 546 pr_err("wrong magic\n");
2309fb8e 547 return -EINVAL;
1da177e4
LT
548 }
549 }
550
551 /* get feature flags first */
99c18ce5 552 if (super->flags & ~CRAMFS_SUPPORTED_FLAGS) {
4f21e1ea 553 pr_err("unsupported filesystem features\n");
2309fb8e 554 return -EINVAL;
1da177e4
LT
555 }
556
557 /* Check that the root inode is in a sane state */
99c18ce5 558 if (!S_ISDIR(super->root.mode)) {
4f21e1ea 559 pr_err("root is not a directory\n");
2309fb8e 560 return -EINVAL;
1da177e4 561 }
6f772fe6 562 /* correct strange, hard-coded permissions of mkcramfs */
99c18ce5 563 super->root.mode |= 0555;
6f772fe6 564
99c18ce5
NP
565 root_offset = super->root.offset << 2;
566 if (super->flags & CRAMFS_FLAG_FSID_VERSION_2) {
567 sbi->size = super->size;
568 sbi->blocks = super->fsid.blocks;
569 sbi->files = super->fsid.files;
1da177e4 570 } else {
31d92e55
FF
571 sbi->size = 1<<28;
572 sbi->blocks = 0;
573 sbi->files = 0;
1da177e4 574 }
99c18ce5
NP
575 sbi->magic = super->magic;
576 sbi->flags = super->flags;
1da177e4 577 if (root_offset == 0)
4f21e1ea 578 pr_info("empty filesystem");
99c18ce5 579 else if (!(super->flags & CRAMFS_FLAG_SHIFTED_ROOT_OFFSET) &&
1da177e4
LT
580 ((root_offset != sizeof(struct cramfs_super)) &&
581 (root_offset != 512 + sizeof(struct cramfs_super))))
582 {
4f21e1ea 583 pr_err("bad root offset %lu\n", root_offset);
2309fb8e 584 return -EINVAL;
1da177e4
LT
585 }
586
99c18ce5
NP
587 return 0;
588}
589
590static int cramfs_finalize_super(struct super_block *sb,
591 struct cramfs_inode *cramfs_root)
592{
593 struct inode *root;
594
1da177e4 595 /* Set it all up.. */
1751e8a6 596 sb->s_flags |= SB_RDONLY;
1da177e4 597 sb->s_op = &cramfs_ops;
99c18ce5 598 root = get_cramfs_inode(sb, cramfs_root, 0);
0577d1ba 599 if (IS_ERR(root))
2309fb8e 600 return PTR_ERR(root);
48fde701
AV
601 sb->s_root = d_make_root(root);
602 if (!sb->s_root)
2309fb8e 603 return -ENOMEM;
1da177e4 604 return 0;
1da177e4
LT
605}
606
99c18ce5
NP
607static int cramfs_blkdev_fill_super(struct super_block *sb, void *data,
608 int silent)
609{
610 struct cramfs_sb_info *sbi;
611 struct cramfs_super super;
612 int i, err;
613
614 sbi = kzalloc(sizeof(struct cramfs_sb_info), GFP_KERNEL);
615 if (!sbi)
616 return -ENOMEM;
617 sb->s_fs_info = sbi;
618
619 /* Invalidate the read buffers on mount: think disk change.. */
620 for (i = 0; i < READ_BUFFERS; i++)
621 buffer_blocknr[i] = -1;
622
623 err = cramfs_read_super(sb, &super, silent);
624 if (err)
625 return err;
626 return cramfs_finalize_super(sb, &super.root);
627}
628
629static int cramfs_mtd_fill_super(struct super_block *sb, void *data,
630 int silent)
631{
632 struct cramfs_sb_info *sbi;
633 struct cramfs_super super;
634 int err;
635
636 sbi = kzalloc(sizeof(struct cramfs_sb_info), GFP_KERNEL);
637 if (!sbi)
638 return -ENOMEM;
639 sb->s_fs_info = sbi;
640
641 /* Map only one page for now. Will remap it when fs size is known. */
642 err = mtd_point(sb->s_mtd, 0, PAGE_SIZE, &sbi->mtd_point_size,
643 &sbi->linear_virt_addr, &sbi->linear_phys_addr);
644 if (err || sbi->mtd_point_size != PAGE_SIZE) {
645 pr_err("unable to get direct memory access to mtd:%s\n",
646 sb->s_mtd->name);
647 return err ? : -ENODATA;
648 }
649
650 pr_info("checking physical address %pap for linear cramfs image\n",
651 &sbi->linear_phys_addr);
652 err = cramfs_read_super(sb, &super, silent);
653 if (err)
654 return err;
655
656 /* Remap the whole filesystem now */
657 pr_info("linear cramfs image on mtd:%s appears to be %lu KB in size\n",
658 sb->s_mtd->name, sbi->size/1024);
659 mtd_unpoint(sb->s_mtd, 0, PAGE_SIZE);
660 err = mtd_point(sb->s_mtd, 0, sbi->size, &sbi->mtd_point_size,
661 &sbi->linear_virt_addr, &sbi->linear_phys_addr);
662 if (err || sbi->mtd_point_size != sbi->size) {
663 pr_err("unable to get direct memory access to mtd:%s\n",
664 sb->s_mtd->name);
665 return err ? : -ENODATA;
666 }
667
668 return cramfs_finalize_super(sb, &super.root);
669}
670
726c3342 671static int cramfs_statfs(struct dentry *dentry, struct kstatfs *buf)
1da177e4 672{
726c3342 673 struct super_block *sb = dentry->d_sb;
99c18ce5
NP
674 u64 id = 0;
675
676 if (sb->s_bdev)
677 id = huge_encode_dev(sb->s_bdev->bd_dev);
678 else if (sb->s_dev)
679 id = huge_encode_dev(sb->s_dev);
726c3342 680
1da177e4 681 buf->f_type = CRAMFS_MAGIC;
09cbfeaf 682 buf->f_bsize = PAGE_SIZE;
1da177e4
LT
683 buf->f_blocks = CRAMFS_SB(sb)->blocks;
684 buf->f_bfree = 0;
685 buf->f_bavail = 0;
686 buf->f_files = CRAMFS_SB(sb)->files;
687 buf->f_ffree = 0;
94ea77ac
CL
688 buf->f_fsid.val[0] = (u32)id;
689 buf->f_fsid.val[1] = (u32)(id >> 32);
1da177e4
LT
690 buf->f_namelen = CRAMFS_MAXPATHLEN;
691 return 0;
692}
693
694/*
695 * Read a cramfs directory entry.
696 */
6f7f231e 697static int cramfs_readdir(struct file *file, struct dir_context *ctx)
1da177e4 698{
6f7f231e 699 struct inode *inode = file_inode(file);
1da177e4
LT
700 struct super_block *sb = inode->i_sb;
701 char *buf;
702 unsigned int offset;
1da177e4
LT
703
704 /* Offset within the thing. */
6f7f231e 705 if (ctx->pos >= inode->i_size)
1da177e4 706 return 0;
6f7f231e 707 offset = ctx->pos;
1da177e4
LT
708 /* Directory entries are always 4-byte aligned */
709 if (offset & 3)
710 return -EINVAL;
711
4176ed59 712 buf = kmalloc(CRAMFS_MAXPATHLEN, GFP_KERNEL);
1da177e4
LT
713 if (!buf)
714 return -ENOMEM;
715
1da177e4
LT
716 while (offset < inode->i_size) {
717 struct cramfs_inode *de;
718 unsigned long nextoffset;
719 char *name;
720 ino_t ino;
175a4eb7 721 umode_t mode;
6f7f231e 722 int namelen;
1da177e4 723
353ab6e9 724 mutex_lock(&read_mutex);
4176ed59 725 de = cramfs_read(sb, OFFSET(inode) + offset, sizeof(*de)+CRAMFS_MAXPATHLEN);
1da177e4
LT
726 name = (char *)(de+1);
727
728 /*
729 * Namelengths on disk are shifted by two
730 * and the name padded out to 4-byte boundaries
731 * with zeroes.
732 */
733 namelen = de->namelen << 2;
734 memcpy(buf, name, namelen);
6f772fe6 735 ino = cramino(de, OFFSET(inode) + offset);
1da177e4 736 mode = de->mode;
353ab6e9 737 mutex_unlock(&read_mutex);
1da177e4
LT
738 nextoffset = offset + sizeof(*de) + namelen;
739 for (;;) {
740 if (!namelen) {
741 kfree(buf);
742 return -EIO;
743 }
744 if (buf[namelen-1])
745 break;
746 namelen--;
747 }
6f7f231e 748 if (!dir_emit(ctx, buf, namelen, ino, mode >> 12))
1da177e4
LT
749 break;
750
6f7f231e 751 ctx->pos = offset = nextoffset;
1da177e4
LT
752 }
753 kfree(buf);
754 return 0;
755}
756
757/*
758 * Lookup and fill in the inode data..
759 */
31d92e55 760static struct dentry *cramfs_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
1da177e4
LT
761{
762 unsigned int offset = 0;
0577d1ba 763 struct inode *inode = NULL;
1da177e4
LT
764 int sorted;
765
353ab6e9 766 mutex_lock(&read_mutex);
1da177e4
LT
767 sorted = CRAMFS_SB(dir->i_sb)->flags & CRAMFS_FLAG_SORTED_DIRS;
768 while (offset < dir->i_size) {
769 struct cramfs_inode *de;
770 char *name;
771 int namelen, retval;
6f772fe6 772 int dir_off = OFFSET(dir) + offset;
1da177e4 773
6f772fe6 774 de = cramfs_read(dir->i_sb, dir_off, sizeof(*de)+CRAMFS_MAXPATHLEN);
1da177e4
LT
775 name = (char *)(de+1);
776
777 /* Try to take advantage of sorted directories */
778 if (sorted && (dentry->d_name.name[0] < name[0]))
779 break;
780
781 namelen = de->namelen << 2;
782 offset += sizeof(*de) + namelen;
783
784 /* Quick check that the name is roughly the right length */
785 if (((dentry->d_name.len + 3) & ~3) != namelen)
786 continue;
787
788 for (;;) {
789 if (!namelen) {
0577d1ba
AV
790 inode = ERR_PTR(-EIO);
791 goto out;
1da177e4
LT
792 }
793 if (name[namelen-1])
794 break;
795 namelen--;
796 }
797 if (namelen != dentry->d_name.len)
798 continue;
799 retval = memcmp(dentry->d_name.name, name, namelen);
800 if (retval > 0)
801 continue;
802 if (!retval) {
0577d1ba
AV
803 inode = get_cramfs_inode(dir->i_sb, de, dir_off);
804 break;
1da177e4
LT
805 }
806 /* else (retval < 0) */
807 if (sorted)
808 break;
809 }
0577d1ba 810out:
353ab6e9 811 mutex_unlock(&read_mutex);
0577d1ba
AV
812 if (IS_ERR(inode))
813 return ERR_CAST(inode);
814 d_add(dentry, inode);
1da177e4
LT
815 return NULL;
816}
817
31d92e55 818static int cramfs_readpage(struct file *file, struct page *page)
1da177e4
LT
819{
820 struct inode *inode = page->mapping->host;
98310e58
DV
821 u32 maxblock;
822 int bytes_filled;
1da177e4
LT
823 void *pgdata;
824
09cbfeaf 825 maxblock = (inode->i_size + PAGE_SIZE - 1) >> PAGE_SHIFT;
1da177e4 826 bytes_filled = 0;
98310e58
DV
827 pgdata = kmap(page);
828
1da177e4
LT
829 if (page->index < maxblock) {
830 struct super_block *sb = inode->i_sb;
fd4f6f2a
NP
831 u32 blkptr_offset = OFFSET(inode) + page->index * 4;
832 u32 block_ptr, block_start, block_len;
833 bool uncompressed, direct;
1da177e4 834
353ab6e9 835 mutex_lock(&read_mutex);
fd4f6f2a
NP
836 block_ptr = *(u32 *) cramfs_read(sb, blkptr_offset, 4);
837 uncompressed = (block_ptr & CRAMFS_BLK_FLAG_UNCOMPRESSED);
838 direct = (block_ptr & CRAMFS_BLK_FLAG_DIRECT_PTR);
839 block_ptr &= ~CRAMFS_BLK_FLAGS;
840
841 if (direct) {
842 /*
843 * The block pointer is an absolute start pointer,
844 * shifted by 2 bits. The size is included in the
845 * first 2 bytes of the data block when compressed,
846 * or PAGE_SIZE otherwise.
847 */
848 block_start = block_ptr << CRAMFS_BLK_DIRECT_PTR_SHIFT;
849 if (uncompressed) {
850 block_len = PAGE_SIZE;
851 /* if last block: cap to file length */
852 if (page->index == maxblock - 1)
853 block_len =
854 offset_in_page(inode->i_size);
855 } else {
856 block_len = *(u16 *)
857 cramfs_read(sb, block_start, 2);
858 block_start += 2;
859 }
860 } else {
861 /*
862 * The block pointer indicates one past the end of
863 * the current block (start of next block). If this
864 * is the first block then it starts where the block
865 * pointer table ends, otherwise its start comes
866 * from the previous block's pointer.
867 */
868 block_start = OFFSET(inode) + maxblock * 4;
869 if (page->index)
870 block_start = *(u32 *)
871 cramfs_read(sb, blkptr_offset - 4, 4);
872 /* Beware... previous ptr might be a direct ptr */
873 if (unlikely(block_start & CRAMFS_BLK_FLAG_DIRECT_PTR)) {
874 /* See comments on earlier code. */
875 u32 prev_start = block_start;
876 block_start = prev_start & ~CRAMFS_BLK_FLAGS;
877 block_start <<= CRAMFS_BLK_DIRECT_PTR_SHIFT;
878 if (prev_start & CRAMFS_BLK_FLAG_UNCOMPRESSED) {
879 block_start += PAGE_SIZE;
880 } else {
881 block_len = *(u16 *)
882 cramfs_read(sb, block_start, 2);
883 block_start += 2 + block_len;
884 }
885 }
886 block_start &= ~CRAMFS_BLK_FLAGS;
887 block_len = block_ptr - block_start;
888 }
98310e58 889
fd4f6f2a 890 if (block_len == 0)
1da177e4 891 ; /* hole */
fd4f6f2a
NP
892 else if (unlikely(block_len > 2*PAGE_SIZE ||
893 (uncompressed && block_len > PAGE_SIZE))) {
894 mutex_unlock(&read_mutex);
895 pr_err("bad data blocksize %u\n", block_len);
98310e58 896 goto err;
fd4f6f2a
NP
897 } else if (uncompressed) {
898 memcpy(pgdata,
899 cramfs_read(sb, block_start, block_len),
900 block_len);
901 bytes_filled = block_len;
98310e58 902 } else {
1da177e4 903 bytes_filled = cramfs_uncompress_block(pgdata,
09cbfeaf 904 PAGE_SIZE,
fd4f6f2a
NP
905 cramfs_read(sb, block_start, block_len),
906 block_len);
1da177e4 907 }
fd4f6f2a
NP
908 mutex_unlock(&read_mutex);
909 if (unlikely(bytes_filled < 0))
910 goto err;
98310e58
DV
911 }
912
09cbfeaf 913 memset(pgdata + bytes_filled, 0, PAGE_SIZE - bytes_filled);
1da177e4 914 flush_dcache_page(page);
98310e58 915 kunmap(page);
1da177e4
LT
916 SetPageUptodate(page);
917 unlock_page(page);
918 return 0;
98310e58
DV
919
920err:
921 kunmap(page);
922 ClearPageUptodate(page);
923 SetPageError(page);
924 unlock_page(page);
925 return 0;
1da177e4
LT
926}
927
f5e54d6e 928static const struct address_space_operations cramfs_aops = {
1da177e4
LT
929 .readpage = cramfs_readpage
930};
931
932/*
933 * Our operations:
934 */
935
936/*
937 * A directory can only readdir
938 */
4b6f5d20 939static const struct file_operations cramfs_directory_operations = {
1da177e4
LT
940 .llseek = generic_file_llseek,
941 .read = generic_read_dir,
c51da20c 942 .iterate_shared = cramfs_readdir,
1da177e4
LT
943};
944
754661f1 945static const struct inode_operations cramfs_dir_inode_operations = {
1da177e4
LT
946 .lookup = cramfs_lookup,
947};
948
ee9b6d61 949static const struct super_operations cramfs_ops = {
1da177e4
LT
950 .remount_fs = cramfs_remount,
951 .statfs = cramfs_statfs,
952};
953
99c18ce5
NP
954static struct dentry *cramfs_mount(struct file_system_type *fs_type, int flags,
955 const char *dev_name, void *data)
1da177e4 956{
99c18ce5
NP
957 struct dentry *ret = ERR_PTR(-ENOPROTOOPT);
958
959 if (IS_ENABLED(CONFIG_CRAMFS_MTD)) {
960 ret = mount_mtd(fs_type, flags, dev_name, data,
961 cramfs_mtd_fill_super);
962 if (!IS_ERR(ret))
963 return ret;
964 }
965 if (IS_ENABLED(CONFIG_CRAMFS_BLOCKDEV)) {
966 ret = mount_bdev(fs_type, flags, dev_name, data,
967 cramfs_blkdev_fill_super);
968 }
969 return ret;
1da177e4
LT
970}
971
972static struct file_system_type cramfs_fs_type = {
973 .owner = THIS_MODULE,
974 .name = "cramfs",
152a0836 975 .mount = cramfs_mount,
2309fb8e 976 .kill_sb = cramfs_kill_sb,
1da177e4
LT
977 .fs_flags = FS_REQUIRES_DEV,
978};
7f78e035 979MODULE_ALIAS_FS("cramfs");
1da177e4
LT
980
981static int __init init_cramfs_fs(void)
982{
50d44ed0
AD
983 int rv;
984
985 rv = cramfs_uncompress_init();
986 if (rv < 0)
987 return rv;
988 rv = register_filesystem(&cramfs_fs_type);
989 if (rv < 0)
990 cramfs_uncompress_exit();
991 return rv;
1da177e4
LT
992}
993
994static void __exit exit_cramfs_fs(void)
995{
996 cramfs_uncompress_exit();
997 unregister_filesystem(&cramfs_fs_type);
998}
999
1000module_init(init_cramfs_fs)
1001module_exit(exit_cramfs_fs)
1002MODULE_LICENSE("GPL");