2 * Compressed rom filesystem for Linux.
4 * Copyright (C) 1999 Linus Torvalds.
6 * This file is released under the GPL.
10 * These are the VFS interfaces to the compressed rom filesystem.
11 * The actual compression is based on zlib, see the other files.
14 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
16 #include <linux/module.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>
37 * cramfs super-block data in memory
39 struct cramfs_sb_info
{
45 void *linear_virt_addr
;
46 resource_size_t linear_phys_addr
;
47 size_t mtd_point_size
;
50 static inline struct cramfs_sb_info
*CRAMFS_SB(struct super_block
*sb
)
55 static const struct super_operations cramfs_ops
;
56 static const struct inode_operations cramfs_dir_inode_operations
;
57 static const struct file_operations cramfs_directory_operations
;
58 static const struct file_operations cramfs_physmem_fops
;
59 static const struct address_space_operations cramfs_aops
;
61 static DEFINE_MUTEX(read_mutex
);
64 /* These macros may change in future, to provide better st_ino semantics. */
65 #define OFFSET(x) ((x)->i_ino)
67 static unsigned long cramino(const struct cramfs_inode
*cino
, unsigned int offset
)
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.
79 switch (cino
->mode
& S_IFMT
) {
83 return cino
->offset
<< 2;
90 static struct inode
*get_cramfs_inode(struct super_block
*sb
,
91 const struct cramfs_inode
*cramfs_inode
, unsigned int offset
)
94 static struct timespec64 zerotime
;
96 inode
= iget_locked(sb
, cramino(cramfs_inode
, offset
));
98 return ERR_PTR(-ENOMEM
);
99 if (!(inode
->i_state
& I_NEW
))
102 switch (cramfs_inode
->mode
& S_IFMT
) {
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
;
112 inode
->i_op
= &cramfs_dir_inode_operations
;
113 inode
->i_fop
= &cramfs_directory_operations
;
116 inode
->i_op
= &page_symlink_inode_operations
;
117 inode_nohighmem(inode
);
118 inode
->i_data
.a_ops
= &cramfs_aops
;
121 init_special_inode(inode
, cramfs_inode
->mode
,
122 old_decode_dev(cramfs_inode
->size
));
125 inode
->i_mode
= cramfs_inode
->mode
;
126 i_uid_write(inode
, cramfs_inode
->uid
);
127 i_gid_write(inode
, cramfs_inode
->gid
);
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;
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. */
142 unlock_new_inode(inode
);
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..
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
158 * Note: This is all optimized away at compile time when
159 * CONFIG_CRAMFS_BLOCKDEV=n.
161 #define READ_BUFFERS (2)
162 /* NEXT_BUFFER(): Loop over [0..(READ_BUFFERS-1)]. */
163 #define NEXT_BUFFER(_ix) ((_ix) ^ 1)
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
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)
174 static unsigned char read_buffers
[READ_BUFFERS
][BUFFER_SIZE
];
175 static unsigned buffer_blocknr
[READ_BUFFERS
];
176 static struct super_block
*buffer_dev
[READ_BUFFERS
];
177 static int next_buffer
;
180 * Populate our block cache and return a pointer to it.
182 static void *cramfs_blkdev_read(struct super_block
*sb
, unsigned int offset
,
185 struct address_space
*mapping
= sb
->s_bdev
->bd_inode
->i_mapping
;
186 struct file_ra_state ra
;
187 struct page
*pages
[BLKS_PER_BUF
];
188 unsigned i
, blocknr
, buffer
;
189 unsigned long devsize
;
194 blocknr
= offset
>> PAGE_SHIFT
;
195 offset
&= PAGE_SIZE
- 1;
197 /* Check if an existing buffer already has the data.. */
198 for (i
= 0; i
< READ_BUFFERS
; i
++) {
199 unsigned int blk_offset
;
201 if (buffer_dev
[i
] != sb
)
203 if (blocknr
< buffer_blocknr
[i
])
205 blk_offset
= (blocknr
- buffer_blocknr
[i
]) << PAGE_SHIFT
;
206 blk_offset
+= offset
;
207 if (blk_offset
> BUFFER_SIZE
||
208 blk_offset
+ len
> BUFFER_SIZE
)
210 return read_buffers
[i
] + blk_offset
;
213 devsize
= bdev_nr_bytes(sb
->s_bdev
) >> PAGE_SHIFT
;
215 /* Ok, read in BLKS_PER_BUF pages completely first. */
216 file_ra_state_init(&ra
, mapping
);
217 page_cache_sync_readahead(mapping
, &ra
, NULL
, blocknr
, BLKS_PER_BUF
);
219 for (i
= 0; i
< BLKS_PER_BUF
; i
++) {
220 struct page
*page
= NULL
;
222 if (blocknr
+ i
< devsize
) {
223 page
= read_mapping_page(mapping
, blocknr
+ i
, NULL
);
224 /* synchronous error? */
231 buffer
= next_buffer
;
232 next_buffer
= NEXT_BUFFER(buffer
);
233 buffer_blocknr
[buffer
] = blocknr
;
234 buffer_dev
[buffer
] = sb
;
236 data
= read_buffers
[buffer
];
237 for (i
= 0; i
< BLKS_PER_BUF
; i
++) {
238 struct page
*page
= pages
[i
];
241 memcpy(data
, kmap(page
), PAGE_SIZE
);
245 memset(data
, 0, PAGE_SIZE
);
248 return read_buffers
[buffer
] + offset
;
252 * Return a pointer to the linearly addressed cramfs image in memory.
254 static void *cramfs_direct_read(struct super_block
*sb
, unsigned int offset
,
257 struct cramfs_sb_info
*sbi
= CRAMFS_SB(sb
);
261 if (len
> sbi
->size
|| offset
> sbi
->size
- len
)
262 return page_address(ZERO_PAGE(0));
263 return sbi
->linear_virt_addr
+ offset
;
267 * Returns a pointer to a buffer containing at least LEN bytes of
268 * filesystem starting at byte offset OFFSET into the filesystem.
270 static void *cramfs_read(struct super_block
*sb
, unsigned int offset
,
273 struct cramfs_sb_info
*sbi
= CRAMFS_SB(sb
);
275 if (IS_ENABLED(CONFIG_CRAMFS_MTD
) && sbi
->linear_virt_addr
)
276 return cramfs_direct_read(sb
, offset
, len
);
277 else if (IS_ENABLED(CONFIG_CRAMFS_BLOCKDEV
))
278 return cramfs_blkdev_read(sb
, offset
, len
);
284 * For a mapping to be possible, we need a range of uncompressed and
285 * contiguous blocks. Return the offset for the first block and number of
286 * valid blocks for which that is true, or zero otherwise.
288 static u32
cramfs_get_block_range(struct inode
*inode
, u32 pgoff
, u32
*pages
)
290 struct cramfs_sb_info
*sbi
= CRAMFS_SB(inode
->i_sb
);
292 u32
*blockptrs
, first_block_addr
;
295 * We can dereference memory directly here as this code may be
296 * reached only when there is a direct filesystem image mapping
297 * available in memory.
299 blockptrs
= (u32
*)(sbi
->linear_virt_addr
+ OFFSET(inode
) + pgoff
* 4);
300 first_block_addr
= blockptrs
[0] & ~CRAMFS_BLK_FLAGS
;
303 u32 block_off
= i
* (PAGE_SIZE
>> CRAMFS_BLK_DIRECT_PTR_SHIFT
);
304 u32 expect
= (first_block_addr
+ block_off
) |
305 CRAMFS_BLK_FLAG_DIRECT_PTR
|
306 CRAMFS_BLK_FLAG_UNCOMPRESSED
;
307 if (blockptrs
[i
] != expect
) {
308 pr_debug("range: block %d/%d got %#x expects %#x\n",
309 pgoff
+i
, pgoff
+ *pages
- 1,
310 blockptrs
[i
], expect
);
315 } while (++i
< *pages
);
318 return first_block_addr
<< CRAMFS_BLK_DIRECT_PTR_SHIFT
;
324 * Return true if the last page of a file in the filesystem image contains
325 * some other data that doesn't belong to that file. It is assumed that the
326 * last block is CRAMFS_BLK_FLAG_DIRECT_PTR | CRAMFS_BLK_FLAG_UNCOMPRESSED
327 * (verified by cramfs_get_block_range() and directly accessible in memory.
329 static bool cramfs_last_page_is_shared(struct inode
*inode
)
331 struct cramfs_sb_info
*sbi
= CRAMFS_SB(inode
->i_sb
);
332 u32 partial
, last_page
, blockaddr
, *blockptrs
;
335 partial
= offset_in_page(inode
->i_size
);
338 last_page
= inode
->i_size
>> PAGE_SHIFT
;
339 blockptrs
= (u32
*)(sbi
->linear_virt_addr
+ OFFSET(inode
));
340 blockaddr
= blockptrs
[last_page
] & ~CRAMFS_BLK_FLAGS
;
341 blockaddr
<<= CRAMFS_BLK_DIRECT_PTR_SHIFT
;
342 tail_data
= sbi
->linear_virt_addr
+ blockaddr
+ partial
;
343 return memchr_inv(tail_data
, 0, PAGE_SIZE
- partial
) ? true : false;
346 static int cramfs_physmem_mmap(struct file
*file
, struct vm_area_struct
*vma
)
348 struct inode
*inode
= file_inode(file
);
349 struct cramfs_sb_info
*sbi
= CRAMFS_SB(inode
->i_sb
);
350 unsigned int pages
, max_pages
, offset
;
351 unsigned long address
, pgoff
= vma
->vm_pgoff
;
352 char *bailout_reason
;
355 ret
= generic_file_readonly_mmap(file
, vma
);
360 * Now try to pre-populate ptes for this vma with a direct
361 * mapping avoiding memory allocation when possible.
364 /* Could COW work here? */
365 bailout_reason
= "vma is writable";
366 if (vma
->vm_flags
& VM_WRITE
)
369 max_pages
= (inode
->i_size
+ PAGE_SIZE
- 1) >> PAGE_SHIFT
;
370 bailout_reason
= "beyond file limit";
371 if (pgoff
>= max_pages
)
373 pages
= min(vma_pages(vma
), max_pages
- pgoff
);
375 offset
= cramfs_get_block_range(inode
, pgoff
, &pages
);
376 bailout_reason
= "unsuitable block layout";
379 address
= sbi
->linear_phys_addr
+ offset
;
380 bailout_reason
= "data is not page aligned";
381 if (!PAGE_ALIGNED(address
))
384 /* Don't map the last page if it contains some other data */
385 if (pgoff
+ pages
== max_pages
&& cramfs_last_page_is_shared(inode
)) {
386 pr_debug("mmap: %pD: last page is shared\n", file
);
391 bailout_reason
= "no suitable block remaining";
395 if (pages
== vma_pages(vma
)) {
397 * The entire vma is mappable. remap_pfn_range() will
398 * make it distinguishable from a non-direct mapping
399 * in /proc/<pid>/maps by substituting the file offset
400 * with the actual physical address.
402 ret
= remap_pfn_range(vma
, vma
->vm_start
, address
>> PAGE_SHIFT
,
403 pages
* PAGE_SIZE
, vma
->vm_page_prot
);
406 * Let's create a mixed map if we can't map it all.
407 * The normal paging machinery will take care of the
408 * unpopulated ptes via cramfs_read_folio().
411 vma
->vm_flags
|= VM_MIXEDMAP
;
412 for (i
= 0; i
< pages
&& !ret
; i
++) {
414 unsigned long off
= i
* PAGE_SIZE
;
415 pfn_t pfn
= phys_to_pfn_t(address
+ off
, PFN_DEV
);
416 vmf
= vmf_insert_mixed(vma
, vma
->vm_start
+ off
, pfn
);
417 if (vmf
& VM_FAULT_ERROR
)
418 ret
= vm_fault_to_errno(vmf
, 0);
423 pr_debug("mapped %pD[%lu] at 0x%08lx (%u/%lu pages) "
424 "to vma 0x%08lx, page_prot 0x%llx\n", file
,
425 pgoff
, address
, pages
, vma_pages(vma
), vma
->vm_start
,
426 (unsigned long long)pgprot_val(vma
->vm_page_prot
));
430 pr_debug("%pD[%lu]: direct mmap impossible: %s\n",
431 file
, pgoff
, bailout_reason
);
432 /* Didn't manage any direct map, but normal paging is still possible */
436 #else /* CONFIG_MMU */
438 static int cramfs_physmem_mmap(struct file
*file
, struct vm_area_struct
*vma
)
440 return vma
->vm_flags
& (VM_SHARED
| VM_MAYSHARE
) ? 0 : -ENOSYS
;
443 static unsigned long cramfs_physmem_get_unmapped_area(struct file
*file
,
444 unsigned long addr
, unsigned long len
,
445 unsigned long pgoff
, unsigned long flags
)
447 struct inode
*inode
= file_inode(file
);
448 struct super_block
*sb
= inode
->i_sb
;
449 struct cramfs_sb_info
*sbi
= CRAMFS_SB(sb
);
450 unsigned int pages
, block_pages
, max_pages
, offset
;
452 pages
= (len
+ PAGE_SIZE
- 1) >> PAGE_SHIFT
;
453 max_pages
= (inode
->i_size
+ PAGE_SIZE
- 1) >> PAGE_SHIFT
;
454 if (pgoff
>= max_pages
|| pages
> max_pages
- pgoff
)
457 offset
= cramfs_get_block_range(inode
, pgoff
, &block_pages
);
458 if (!offset
|| block_pages
!= pages
)
460 addr
= sbi
->linear_phys_addr
+ offset
;
461 pr_debug("get_unmapped for %pD ofs %#lx siz %lu at 0x%08lx\n",
462 file
, pgoff
*PAGE_SIZE
, len
, addr
);
466 static unsigned int cramfs_physmem_mmap_capabilities(struct file
*file
)
468 return NOMMU_MAP_COPY
| NOMMU_MAP_DIRECT
|
469 NOMMU_MAP_READ
| NOMMU_MAP_EXEC
;
472 #endif /* CONFIG_MMU */
474 static const struct file_operations cramfs_physmem_fops
= {
475 .llseek
= generic_file_llseek
,
476 .read_iter
= generic_file_read_iter
,
477 .splice_read
= generic_file_splice_read
,
478 .mmap
= cramfs_physmem_mmap
,
480 .get_unmapped_area
= cramfs_physmem_get_unmapped_area
,
481 .mmap_capabilities
= cramfs_physmem_mmap_capabilities
,
485 static void cramfs_kill_sb(struct super_block
*sb
)
487 struct cramfs_sb_info
*sbi
= CRAMFS_SB(sb
);
489 if (IS_ENABLED(CONFIG_CRAMFS_MTD
) && sb
->s_mtd
) {
490 if (sbi
&& sbi
->mtd_point_size
)
491 mtd_unpoint(sb
->s_mtd
, 0, sbi
->mtd_point_size
);
493 } else if (IS_ENABLED(CONFIG_CRAMFS_BLOCKDEV
) && sb
->s_bdev
) {
494 kill_block_super(sb
);
499 static int cramfs_reconfigure(struct fs_context
*fc
)
501 sync_filesystem(fc
->root
->d_sb
);
502 fc
->sb_flags
|= SB_RDONLY
;
506 static int cramfs_read_super(struct super_block
*sb
, struct fs_context
*fc
,
507 struct cramfs_super
*super
)
509 struct cramfs_sb_info
*sbi
= CRAMFS_SB(sb
);
510 unsigned long root_offset
;
511 bool silent
= fc
->sb_flags
& SB_SILENT
;
513 /* We don't know the real size yet */
514 sbi
->size
= PAGE_SIZE
;
516 /* Read the first block and get the superblock from it */
517 mutex_lock(&read_mutex
);
518 memcpy(super
, cramfs_read(sb
, 0, sizeof(*super
)), sizeof(*super
));
519 mutex_unlock(&read_mutex
);
521 /* Do sanity checks on the superblock */
522 if (super
->magic
!= CRAMFS_MAGIC
) {
523 /* check for wrong endianness */
524 if (super
->magic
== CRAMFS_MAGIC_WEND
) {
526 errorfc(fc
, "wrong endianness");
530 /* check at 512 byte offset */
531 mutex_lock(&read_mutex
);
533 cramfs_read(sb
, 512, sizeof(*super
)),
535 mutex_unlock(&read_mutex
);
536 if (super
->magic
!= CRAMFS_MAGIC
) {
537 if (super
->magic
== CRAMFS_MAGIC_WEND
&& !silent
)
538 errorfc(fc
, "wrong endianness");
540 errorfc(fc
, "wrong magic");
545 /* get feature flags first */
546 if (super
->flags
& ~CRAMFS_SUPPORTED_FLAGS
) {
547 errorfc(fc
, "unsupported filesystem features");
551 /* Check that the root inode is in a sane state */
552 if (!S_ISDIR(super
->root
.mode
)) {
553 errorfc(fc
, "root is not a directory");
556 /* correct strange, hard-coded permissions of mkcramfs */
557 super
->root
.mode
|= 0555;
559 root_offset
= super
->root
.offset
<< 2;
560 if (super
->flags
& CRAMFS_FLAG_FSID_VERSION_2
) {
561 sbi
->size
= super
->size
;
562 sbi
->blocks
= super
->fsid
.blocks
;
563 sbi
->files
= super
->fsid
.files
;
569 sbi
->magic
= super
->magic
;
570 sbi
->flags
= super
->flags
;
571 if (root_offset
== 0)
572 infofc(fc
, "empty filesystem");
573 else if (!(super
->flags
& CRAMFS_FLAG_SHIFTED_ROOT_OFFSET
) &&
574 ((root_offset
!= sizeof(struct cramfs_super
)) &&
575 (root_offset
!= 512 + sizeof(struct cramfs_super
))))
577 errorfc(fc
, "bad root offset %lu", root_offset
);
584 static int cramfs_finalize_super(struct super_block
*sb
,
585 struct cramfs_inode
*cramfs_root
)
589 /* Set it all up.. */
590 sb
->s_flags
|= SB_RDONLY
;
593 sb
->s_op
= &cramfs_ops
;
594 root
= get_cramfs_inode(sb
, cramfs_root
, 0);
596 return PTR_ERR(root
);
597 sb
->s_root
= d_make_root(root
);
603 static int cramfs_blkdev_fill_super(struct super_block
*sb
, struct fs_context
*fc
)
605 struct cramfs_sb_info
*sbi
;
606 struct cramfs_super super
;
609 sbi
= kzalloc(sizeof(struct cramfs_sb_info
), GFP_KERNEL
);
614 /* Invalidate the read buffers on mount: think disk change.. */
615 for (i
= 0; i
< READ_BUFFERS
; i
++)
616 buffer_blocknr
[i
] = -1;
618 err
= cramfs_read_super(sb
, fc
, &super
);
621 return cramfs_finalize_super(sb
, &super
.root
);
624 static int cramfs_mtd_fill_super(struct super_block
*sb
, struct fs_context
*fc
)
626 struct cramfs_sb_info
*sbi
;
627 struct cramfs_super super
;
630 sbi
= kzalloc(sizeof(struct cramfs_sb_info
), GFP_KERNEL
);
635 /* Map only one page for now. Will remap it when fs size is known. */
636 err
= mtd_point(sb
->s_mtd
, 0, PAGE_SIZE
, &sbi
->mtd_point_size
,
637 &sbi
->linear_virt_addr
, &sbi
->linear_phys_addr
);
638 if (err
|| sbi
->mtd_point_size
!= PAGE_SIZE
) {
639 pr_err("unable to get direct memory access to mtd:%s\n",
641 return err
? : -ENODATA
;
644 pr_info("checking physical address %pap for linear cramfs image\n",
645 &sbi
->linear_phys_addr
);
646 err
= cramfs_read_super(sb
, fc
, &super
);
650 /* Remap the whole filesystem now */
651 pr_info("linear cramfs image on mtd:%s appears to be %lu KB in size\n",
652 sb
->s_mtd
->name
, sbi
->size
/1024);
653 mtd_unpoint(sb
->s_mtd
, 0, PAGE_SIZE
);
654 err
= mtd_point(sb
->s_mtd
, 0, sbi
->size
, &sbi
->mtd_point_size
,
655 &sbi
->linear_virt_addr
, &sbi
->linear_phys_addr
);
656 if (err
|| sbi
->mtd_point_size
!= sbi
->size
) {
657 pr_err("unable to get direct memory access to mtd:%s\n",
659 return err
? : -ENODATA
;
662 return cramfs_finalize_super(sb
, &super
.root
);
665 static int cramfs_statfs(struct dentry
*dentry
, struct kstatfs
*buf
)
667 struct super_block
*sb
= dentry
->d_sb
;
671 id
= huge_encode_dev(sb
->s_bdev
->bd_dev
);
673 id
= huge_encode_dev(sb
->s_dev
);
675 buf
->f_type
= CRAMFS_MAGIC
;
676 buf
->f_bsize
= PAGE_SIZE
;
677 buf
->f_blocks
= CRAMFS_SB(sb
)->blocks
;
680 buf
->f_files
= CRAMFS_SB(sb
)->files
;
682 buf
->f_fsid
= u64_to_fsid(id
);
683 buf
->f_namelen
= CRAMFS_MAXPATHLEN
;
688 * Read a cramfs directory entry.
690 static int cramfs_readdir(struct file
*file
, struct dir_context
*ctx
)
692 struct inode
*inode
= file_inode(file
);
693 struct super_block
*sb
= inode
->i_sb
;
697 /* Offset within the thing. */
698 if (ctx
->pos
>= inode
->i_size
)
701 /* Directory entries are always 4-byte aligned */
705 buf
= kmalloc(CRAMFS_MAXPATHLEN
, GFP_KERNEL
);
709 while (offset
< inode
->i_size
) {
710 struct cramfs_inode
*de
;
711 unsigned long nextoffset
;
717 mutex_lock(&read_mutex
);
718 de
= cramfs_read(sb
, OFFSET(inode
) + offset
, sizeof(*de
)+CRAMFS_MAXPATHLEN
);
719 name
= (char *)(de
+1);
722 * Namelengths on disk are shifted by two
723 * and the name padded out to 4-byte boundaries
726 namelen
= de
->namelen
<< 2;
727 memcpy(buf
, name
, namelen
);
728 ino
= cramino(de
, OFFSET(inode
) + offset
);
730 mutex_unlock(&read_mutex
);
731 nextoffset
= offset
+ sizeof(*de
) + namelen
;
741 if (!dir_emit(ctx
, buf
, namelen
, ino
, mode
>> 12))
744 ctx
->pos
= offset
= nextoffset
;
751 * Lookup and fill in the inode data..
753 static struct dentry
*cramfs_lookup(struct inode
*dir
, struct dentry
*dentry
, unsigned int flags
)
755 unsigned int offset
= 0;
756 struct inode
*inode
= NULL
;
759 mutex_lock(&read_mutex
);
760 sorted
= CRAMFS_SB(dir
->i_sb
)->flags
& CRAMFS_FLAG_SORTED_DIRS
;
761 while (offset
< dir
->i_size
) {
762 struct cramfs_inode
*de
;
765 int dir_off
= OFFSET(dir
) + offset
;
767 de
= cramfs_read(dir
->i_sb
, dir_off
, sizeof(*de
)+CRAMFS_MAXPATHLEN
);
768 name
= (char *)(de
+1);
770 /* Try to take advantage of sorted directories */
771 if (sorted
&& (dentry
->d_name
.name
[0] < name
[0]))
774 namelen
= de
->namelen
<< 2;
775 offset
+= sizeof(*de
) + namelen
;
777 /* Quick check that the name is roughly the right length */
778 if (((dentry
->d_name
.len
+ 3) & ~3) != namelen
)
783 inode
= ERR_PTR(-EIO
);
790 if (namelen
!= dentry
->d_name
.len
)
792 retval
= memcmp(dentry
->d_name
.name
, name
, namelen
);
796 inode
= get_cramfs_inode(dir
->i_sb
, de
, dir_off
);
799 /* else (retval < 0) */
804 mutex_unlock(&read_mutex
);
805 return d_splice_alias(inode
, dentry
);
808 static int cramfs_read_folio(struct file
*file
, struct folio
*folio
)
810 struct page
*page
= &folio
->page
;
811 struct inode
*inode
= page
->mapping
->host
;
816 maxblock
= (inode
->i_size
+ PAGE_SIZE
- 1) >> PAGE_SHIFT
;
820 if (page
->index
< maxblock
) {
821 struct super_block
*sb
= inode
->i_sb
;
822 u32 blkptr_offset
= OFFSET(inode
) + page
->index
* 4;
823 u32 block_ptr
, block_start
, block_len
;
824 bool uncompressed
, direct
;
826 mutex_lock(&read_mutex
);
827 block_ptr
= *(u32
*) cramfs_read(sb
, blkptr_offset
, 4);
828 uncompressed
= (block_ptr
& CRAMFS_BLK_FLAG_UNCOMPRESSED
);
829 direct
= (block_ptr
& CRAMFS_BLK_FLAG_DIRECT_PTR
);
830 block_ptr
&= ~CRAMFS_BLK_FLAGS
;
834 * The block pointer is an absolute start pointer,
835 * shifted by 2 bits. The size is included in the
836 * first 2 bytes of the data block when compressed,
837 * or PAGE_SIZE otherwise.
839 block_start
= block_ptr
<< CRAMFS_BLK_DIRECT_PTR_SHIFT
;
841 block_len
= PAGE_SIZE
;
842 /* if last block: cap to file length */
843 if (page
->index
== maxblock
- 1)
845 offset_in_page(inode
->i_size
);
848 cramfs_read(sb
, block_start
, 2);
853 * The block pointer indicates one past the end of
854 * the current block (start of next block). If this
855 * is the first block then it starts where the block
856 * pointer table ends, otherwise its start comes
857 * from the previous block's pointer.
859 block_start
= OFFSET(inode
) + maxblock
* 4;
861 block_start
= *(u32
*)
862 cramfs_read(sb
, blkptr_offset
- 4, 4);
863 /* Beware... previous ptr might be a direct ptr */
864 if (unlikely(block_start
& CRAMFS_BLK_FLAG_DIRECT_PTR
)) {
865 /* See comments on earlier code. */
866 u32 prev_start
= block_start
;
867 block_start
= prev_start
& ~CRAMFS_BLK_FLAGS
;
868 block_start
<<= CRAMFS_BLK_DIRECT_PTR_SHIFT
;
869 if (prev_start
& CRAMFS_BLK_FLAG_UNCOMPRESSED
) {
870 block_start
+= PAGE_SIZE
;
873 cramfs_read(sb
, block_start
, 2);
874 block_start
+= 2 + block_len
;
877 block_start
&= ~CRAMFS_BLK_FLAGS
;
878 block_len
= block_ptr
- block_start
;
883 else if (unlikely(block_len
> 2*PAGE_SIZE
||
884 (uncompressed
&& block_len
> PAGE_SIZE
))) {
885 mutex_unlock(&read_mutex
);
886 pr_err("bad data blocksize %u\n", block_len
);
888 } else if (uncompressed
) {
890 cramfs_read(sb
, block_start
, block_len
),
892 bytes_filled
= block_len
;
894 bytes_filled
= cramfs_uncompress_block(pgdata
,
896 cramfs_read(sb
, block_start
, block_len
),
899 mutex_unlock(&read_mutex
);
900 if (unlikely(bytes_filled
< 0))
904 memset(pgdata
+ bytes_filled
, 0, PAGE_SIZE
- bytes_filled
);
905 flush_dcache_page(page
);
907 SetPageUptodate(page
);
913 ClearPageUptodate(page
);
919 static const struct address_space_operations cramfs_aops
= {
920 .read_folio
= cramfs_read_folio
928 * A directory can only readdir
930 static const struct file_operations cramfs_directory_operations
= {
931 .llseek
= generic_file_llseek
,
932 .read
= generic_read_dir
,
933 .iterate_shared
= cramfs_readdir
,
936 static const struct inode_operations cramfs_dir_inode_operations
= {
937 .lookup
= cramfs_lookup
,
940 static const struct super_operations cramfs_ops
= {
941 .statfs
= cramfs_statfs
,
944 static int cramfs_get_tree(struct fs_context
*fc
)
946 int ret
= -ENOPROTOOPT
;
948 if (IS_ENABLED(CONFIG_CRAMFS_MTD
)) {
949 ret
= get_tree_mtd(fc
, cramfs_mtd_fill_super
);
953 if (IS_ENABLED(CONFIG_CRAMFS_BLOCKDEV
))
954 ret
= get_tree_bdev(fc
, cramfs_blkdev_fill_super
);
958 static const struct fs_context_operations cramfs_context_ops
= {
959 .get_tree
= cramfs_get_tree
,
960 .reconfigure
= cramfs_reconfigure
,
964 * Set up the filesystem mount context.
966 static int cramfs_init_fs_context(struct fs_context
*fc
)
968 fc
->ops
= &cramfs_context_ops
;
972 static struct file_system_type cramfs_fs_type
= {
973 .owner
= THIS_MODULE
,
975 .init_fs_context
= cramfs_init_fs_context
,
976 .kill_sb
= cramfs_kill_sb
,
977 .fs_flags
= FS_REQUIRES_DEV
,
979 MODULE_ALIAS_FS("cramfs");
981 static int __init
init_cramfs_fs(void)
985 rv
= cramfs_uncompress_init();
988 rv
= register_filesystem(&cramfs_fs_type
);
990 cramfs_uncompress_exit();
994 static void __exit
exit_cramfs_fs(void)
996 cramfs_uncompress_exit();
997 unregister_filesystem(&cramfs_fs_type
);
1000 module_init(init_cramfs_fs
)
1001 module_exit(exit_cramfs_fs
)
1002 MODULE_LICENSE("GPL");