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DEFINITIONS
This source file includes following definitions.
- cramfs_iget5_test
- cramfs_iget5_set
- get_cramfs_inode
- cramfs_drop_inode
- cramfs_read
- cramfs_put_super
- cramfs_remount
- cramfs_fill_super
- cramfs_statfs
- cramfs_readdir
- cramfs_lookup
- cramfs_readpage
- cramfs_get_sb
- init_cramfs_fs
- exit_cramfs_fs
/*
* Compressed rom filesystem for Linux.
*
* Copyright (C) 1999 Linus Torvalds.
*
* This file is released under the GPL.
*/
/*
* These are the VFS interfaces to the compressed rom filesystem.
* The actual compression is based on zlib, see the other files.
*/
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/pagemap.h>
#include <linux/init.h>
#include <linux/string.h>
#include <linux/blkdev.h>
#include <linux/cramfs_fs.h>
#include <linux/slab.h>
#include <linux/cramfs_fs_sb.h>
#include <linux/buffer_head.h>
#include <linux/vfs.h>
#include <linux/mutex.h>
#include <asm/uaccess.h>
static const struct super_operations cramfs_ops;
static const struct inode_operations cramfs_dir_inode_operations;
static const struct file_operations cramfs_directory_operations;
static const struct address_space_operations cramfs_aops;
static DEFINE_MUTEX(read_mutex);
/* These two macros may change in future, to provide better st_ino
semantics. */
#define CRAMINO(x) (((x)->offset && (x)->size)?(x)->offset<<2:1)
#define OFFSET(x) ((x)->i_ino)
static int cramfs_iget5_test(struct inode *inode, void *opaque)
{
struct cramfs_inode *cramfs_inode = opaque;
return inode->i_ino == CRAMINO(cramfs_inode) && inode->i_ino != 1;
}
static int cramfs_iget5_set(struct inode *inode, void *opaque)
{
struct cramfs_inode *cramfs_inode = opaque;
inode->i_ino = CRAMINO(cramfs_inode);
return 0;
}
static struct inode *get_cramfs_inode(struct super_block *sb,
struct cramfs_inode * cramfs_inode)
{
struct inode *inode = iget5_locked(sb, CRAMINO(cramfs_inode),
cramfs_iget5_test, cramfs_iget5_set,
cramfs_inode);
static struct timespec zerotime;
if (inode && (inode->i_state & I_NEW)) {
inode->i_mode = cramfs_inode->mode;
inode->i_uid = cramfs_inode->uid;
inode->i_size = cramfs_inode->size;
inode->i_blocks = (cramfs_inode->size - 1) / 512 + 1;
inode->i_gid = cramfs_inode->gid;
/* Struct copy intentional */
inode->i_mtime = inode->i_atime = inode->i_ctime = zerotime;
/* inode->i_nlink is left 1 - arguably wrong for directories,
but it's the best we can do without reading the directory
contents. 1 yields the right result in GNU find, even
without -noleaf option. */
if (S_ISREG(inode->i_mode)) {
inode->i_fop = &generic_ro_fops;
inode->i_data.a_ops = &cramfs_aops;
} else if (S_ISDIR(inode->i_mode)) {
inode->i_op = &cramfs_dir_inode_operations;
inode->i_fop = &cramfs_directory_operations;
} else if (S_ISLNK(inode->i_mode)) {
inode->i_op = &page_symlink_inode_operations;
inode->i_data.a_ops = &cramfs_aops;
} else {
inode->i_size = 0;
inode->i_blocks = 0;
init_special_inode(inode, inode->i_mode,
old_decode_dev(cramfs_inode->size));
}
unlock_new_inode(inode);
}
return inode;
}
static void cramfs_drop_inode(struct inode *inode)
{
if (inode->i_ino == 1)
generic_delete_inode(inode);
else
generic_drop_inode(inode);
}
/*
* We have our own block cache: don't fill up the buffer cache
* with the rom-image, because the way the filesystem is set
* up the accesses should be fairly regular and cached in the
* page cache and dentry tree anyway..
*
* This also acts as a way to guarantee contiguous areas of up to
* BLKS_PER_BUF*PAGE_CACHE_SIZE, so that the caller doesn't need to
* worry about end-of-buffer issues even when decompressing a full
* page cache.
*/
#define READ_BUFFERS (2)
/* NEXT_BUFFER(): Loop over [0..(READ_BUFFERS-1)]. */
#define NEXT_BUFFER(_ix) ((_ix) ^ 1)
/*
* BLKS_PER_BUF_SHIFT should be at least 2 to allow for "compressed"
* data that takes up more space than the original and with unlucky
* alignment.
*/
#define BLKS_PER_BUF_SHIFT (2)
#define BLKS_PER_BUF (1 << BLKS_PER_BUF_SHIFT)
#define BUFFER_SIZE (BLKS_PER_BUF*PAGE_CACHE_SIZE)
static unsigned char read_buffers[READ_BUFFERS][BUFFER_SIZE];
static unsigned buffer_blocknr[READ_BUFFERS];
static struct super_block * buffer_dev[READ_BUFFERS];
static int next_buffer;
/*
* Returns a pointer to a buffer containing at least LEN bytes of
* filesystem starting at byte offset OFFSET into the filesystem.
*/
static void *cramfs_read(struct super_block *sb, unsigned int offset, unsigned int len)
{
struct address_space *mapping = sb->s_bdev->bd_inode->i_mapping;
struct page *pages[BLKS_PER_BUF];
unsigned i, blocknr, buffer;
unsigned long devsize;
char *data;
if (!len)
return NULL;
blocknr = offset >> PAGE_CACHE_SHIFT;
offset &= PAGE_CACHE_SIZE - 1;
/* Check if an existing buffer already has the data.. */
for (i = 0; i < READ_BUFFERS; i++) {
unsigned int blk_offset;
if (buffer_dev[i] != sb)
continue;
if (blocknr < buffer_blocknr[i])
continue;
blk_offset = (blocknr - buffer_blocknr[i]) << PAGE_CACHE_SHIFT;
blk_offset += offset;
if (blk_offset + len > BUFFER_SIZE)
continue;
return read_buffers[i] + blk_offset;
}
devsize = mapping->host->i_size >> PAGE_CACHE_SHIFT;
/* Ok, read in BLKS_PER_BUF pages completely first. */
for (i = 0; i < BLKS_PER_BUF; i++) {
struct page *page = NULL;
if (blocknr + i < devsize) {
page = read_mapping_page_async(mapping, blocknr + i,
NULL);
/* synchronous error? */
if (IS_ERR(page))
page = NULL;
}
pages[i] = page;
}
for (i = 0; i < BLKS_PER_BUF; i++) {
struct page *page = pages[i];
if (page) {
wait_on_page_locked(page);
if (!PageUptodate(page)) {
/* asynchronous error */
page_cache_release(page);
pages[i] = NULL;
}
}
}
buffer = next_buffer;
next_buffer = NEXT_BUFFER(buffer);
buffer_blocknr[buffer] = blocknr;
buffer_dev[buffer] = sb;
data = read_buffers[buffer];
for (i = 0; i < BLKS_PER_BUF; i++) {
struct page *page = pages[i];
if (page) {
memcpy(data, kmap(page), PAGE_CACHE_SIZE);
kunmap(page);
page_cache_release(page);
} else
memset(data, 0, PAGE_CACHE_SIZE);
data += PAGE_CACHE_SIZE;
}
return read_buffers[buffer] + offset;
}
static void cramfs_put_super(struct super_block *sb)
{
kfree(sb->s_fs_info);
sb->s_fs_info = NULL;
}
static int cramfs_remount(struct super_block *sb, int *flags, char *data)
{
*flags |= MS_RDONLY;
return 0;
}
static int cramfs_fill_super(struct super_block *sb, void *data, int silent)
{
int i;
struct cramfs_super super;
unsigned long root_offset;
struct cramfs_sb_info *sbi;
struct inode *root;
sb->s_flags |= MS_RDONLY;
sbi = kzalloc(sizeof(struct cramfs_sb_info), GFP_KERNEL);
if (!sbi)
return -ENOMEM;
sb->s_fs_info = sbi;
/* Invalidate the read buffers on mount: think disk change.. */
mutex_lock(&read_mutex);
for (i = 0; i < READ_BUFFERS; i++)
buffer_blocknr[i] = -1;
/* Read the first block and get the superblock from it */
memcpy(&super, cramfs_read(sb, 0, sizeof(super)), sizeof(super));
mutex_unlock(&read_mutex);
/* Do sanity checks on the superblock */
if (super.magic != CRAMFS_MAGIC) {
/* check for wrong endianess */
if (super.magic == CRAMFS_MAGIC_WEND) {
if (!silent)
printk(KERN_ERR "cramfs: wrong endianess\n");
goto out;
}
/* check at 512 byte offset */
mutex_lock(&read_mutex);
memcpy(&super, cramfs_read(sb, 512, sizeof(super)), sizeof(super));
mutex_unlock(&read_mutex);
if (super.magic != CRAMFS_MAGIC) {
if (super.magic == CRAMFS_MAGIC_WEND && !silent)
printk(KERN_ERR "cramfs: wrong endianess\n");
else if (!silent)
printk(KERN_ERR "cramfs: wrong magic\n");
goto out;
}
}
/* get feature flags first */
if (super.flags & ~CRAMFS_SUPPORTED_FLAGS) {
printk(KERN_ERR "cramfs: unsupported filesystem features\n");
goto out;
}
/* Check that the root inode is in a sane state */
if (!S_ISDIR(super.root.mode)) {
printk(KERN_ERR "cramfs: root is not a directory\n");
goto out;
}
root_offset = super.root.offset << 2;
if (super.flags & CRAMFS_FLAG_FSID_VERSION_2) {
sbi->size=super.size;
sbi->blocks=super.fsid.blocks;
sbi->files=super.fsid.files;
} else {
sbi->size=1<<28;
sbi->blocks=0;
sbi->files=0;
}
sbi->magic=super.magic;
sbi->flags=super.flags;
if (root_offset == 0)
printk(KERN_INFO "cramfs: empty filesystem");
else if (!(super.flags & CRAMFS_FLAG_SHIFTED_ROOT_OFFSET) &&
((root_offset != sizeof(struct cramfs_super)) &&
(root_offset != 512 + sizeof(struct cramfs_super))))
{
printk(KERN_ERR "cramfs: bad root offset %lu\n", root_offset);
goto out;
}
/* Set it all up.. */
sb->s_op = &cramfs_ops;
root = get_cramfs_inode(sb, &super.root);
if (!root)
goto out;
sb->s_root = d_alloc_root(root);
if (!sb->s_root) {
iput(root);
goto out;
}
return 0;
out:
kfree(sbi);
sb->s_fs_info = NULL;
return -EINVAL;
}
static int cramfs_statfs(struct dentry *dentry, struct kstatfs *buf)
{
struct super_block *sb = dentry->d_sb;
buf->f_type = CRAMFS_MAGIC;
buf->f_bsize = PAGE_CACHE_SIZE;
buf->f_blocks = CRAMFS_SB(sb)->blocks;
buf->f_bfree = 0;
buf->f_bavail = 0;
buf->f_files = CRAMFS_SB(sb)->files;
buf->f_ffree = 0;
buf->f_namelen = CRAMFS_MAXPATHLEN;
return 0;
}
/*
* Read a cramfs directory entry.
*/
static int cramfs_readdir(struct file *filp, void *dirent, filldir_t filldir)
{
struct inode *inode = filp->f_path.dentry->d_inode;
struct super_block *sb = inode->i_sb;
char *buf;
unsigned int offset;
int copied;
/* Offset within the thing. */
offset = filp->f_pos;
if (offset >= inode->i_size)
return 0;
/* Directory entries are always 4-byte aligned */
if (offset & 3)
return -EINVAL;
buf = kmalloc(CRAMFS_MAXPATHLEN, GFP_KERNEL);
if (!buf)
return -ENOMEM;
copied = 0;
while (offset < inode->i_size) {
struct cramfs_inode *de;
unsigned long nextoffset;
char *name;
ino_t ino;
mode_t mode;
int namelen, error;
mutex_lock(&read_mutex);
de = cramfs_read(sb, OFFSET(inode) + offset, sizeof(*de)+CRAMFS_MAXPATHLEN);
name = (char *)(de+1);
/*
* Namelengths on disk are shifted by two
* and the name padded out to 4-byte boundaries
* with zeroes.
*/
namelen = de->namelen << 2;
memcpy(buf, name, namelen);
ino = CRAMINO(de);
mode = de->mode;
mutex_unlock(&read_mutex);
nextoffset = offset + sizeof(*de) + namelen;
for (;;) {
if (!namelen) {
kfree(buf);
return -EIO;
}
if (buf[namelen-1])
break;
namelen--;
}
error = filldir(dirent, buf, namelen, offset, ino, mode >> 12);
if (error)
break;
offset = nextoffset;
filp->f_pos = offset;
copied++;
}
kfree(buf);
return 0;
}
/*
* Lookup and fill in the inode data..
*/
static struct dentry * cramfs_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
{
unsigned int offset = 0;
int sorted;
mutex_lock(&read_mutex);
sorted = CRAMFS_SB(dir->i_sb)->flags & CRAMFS_FLAG_SORTED_DIRS;
while (offset < dir->i_size) {
struct cramfs_inode *de;
char *name;
int namelen, retval;
de = cramfs_read(dir->i_sb, OFFSET(dir) + offset, sizeof(*de)+CRAMFS_MAXPATHLEN);
name = (char *)(de+1);
/* Try to take advantage of sorted directories */
if (sorted && (dentry->d_name.name[0] < name[0]))
break;
namelen = de->namelen << 2;
offset += sizeof(*de) + namelen;
/* Quick check that the name is roughly the right length */
if (((dentry->d_name.len + 3) & ~3) != namelen)
continue;
for (;;) {
if (!namelen) {
mutex_unlock(&read_mutex);
return ERR_PTR(-EIO);
}
if (name[namelen-1])
break;
namelen--;
}
if (namelen != dentry->d_name.len)
continue;
retval = memcmp(dentry->d_name.name, name, namelen);
if (retval > 0)
continue;
if (!retval) {
struct cramfs_inode entry = *de;
mutex_unlock(&read_mutex);
d_add(dentry, get_cramfs_inode(dir->i_sb, &entry));
return NULL;
}
/* else (retval < 0) */
if (sorted)
break;
}
mutex_unlock(&read_mutex);
d_add(dentry, NULL);
return NULL;
}
static int cramfs_readpage(struct file *file, struct page * page)
{
struct inode *inode = page->mapping->host;
u32 maxblock, bytes_filled;
void *pgdata;
maxblock = (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
bytes_filled = 0;
if (page->index < maxblock) {
struct super_block *sb = inode->i_sb;
u32 blkptr_offset = OFFSET(inode) + page->index*4;
u32 start_offset, compr_len;
start_offset = OFFSET(inode) + maxblock*4;
mutex_lock(&read_mutex);
if (page->index)
start_offset = *(u32 *) cramfs_read(sb, blkptr_offset-4, 4);
compr_len = (*(u32 *) cramfs_read(sb, blkptr_offset, 4) - start_offset);
mutex_unlock(&read_mutex);
pgdata = kmap(page);
if (compr_len == 0)
; /* hole */
else if (compr_len > (PAGE_CACHE_SIZE << 1))
printk(KERN_ERR "cramfs: bad compressed blocksize %u\n", compr_len);
else {
mutex_lock(&read_mutex);
bytes_filled = cramfs_uncompress_block(pgdata,
PAGE_CACHE_SIZE,
cramfs_read(sb, start_offset, compr_len),
compr_len);
mutex_unlock(&read_mutex);
}
} else
pgdata = kmap(page);
memset(pgdata + bytes_filled, 0, PAGE_CACHE_SIZE - bytes_filled);
kunmap(page);
flush_dcache_page(page);
SetPageUptodate(page);
unlock_page(page);
return 0;
}
static const struct address_space_operations cramfs_aops = {
.readpage = cramfs_readpage
};
/*
* Our operations:
*/
/*
* A directory can only readdir
*/
static const struct file_operations cramfs_directory_operations = {
.llseek = generic_file_llseek,
.read = generic_read_dir,
.readdir = cramfs_readdir,
};
static const struct inode_operations cramfs_dir_inode_operations = {
.lookup = cramfs_lookup,
};
static const struct super_operations cramfs_ops = {
.put_super = cramfs_put_super,
.remount_fs = cramfs_remount,
.statfs = cramfs_statfs,
.drop_inode = cramfs_drop_inode,
};
static int cramfs_get_sb(struct file_system_type *fs_type,
int flags, const char *dev_name, void *data, struct vfsmount *mnt)
{
return get_sb_bdev(fs_type, flags, dev_name, data, cramfs_fill_super,
mnt);
}
static struct file_system_type cramfs_fs_type = {
.owner = THIS_MODULE,
.name = "cramfs",
.get_sb = cramfs_get_sb,
.kill_sb = kill_block_super,
.fs_flags = FS_REQUIRES_DEV,
};
static int __init init_cramfs_fs(void)
{
int rv;
rv = cramfs_uncompress_init();
if (rv < 0)
return rv;
rv = register_filesystem(&cramfs_fs_type);
if (rv < 0)
cramfs_uncompress_exit();
return rv;
}
static void __exit exit_cramfs_fs(void)
{
cramfs_uncompress_exit();
unregister_filesystem(&cramfs_fs_type);
}
module_init(init_cramfs_fs)
module_exit(exit_cramfs_fs)
MODULE_LICENSE("GPL");