android_kernel_motorola_sm6225/fs/cramfs/inode.c
Dave Johnson a97c9bf33f [PATCH] fix cramfs making duplicate entries in inode cache
Every time cramfs_lookup() is called to lookup and inode for a dentry,
get_cramfs_inode() will allocate a new inode without checking to see if that
inode already exists in the inode cache.

This is fine the first time, but if the dentry cache entry(ies) associated
with that inode are aged out, but the inode entry is not aged out (which can
be quite common if the inode has buffer cache linked to it), cramfs_lookup()
will be called again and another inode will be allocated and added to the
inode cache creating a duplicate in the inode cache.

The big issue here is that the buffers associated with each inode cache entry
are not shared between the duplicates!

The older inode entries are now orphaned as no dentry points to it and won't
be freed until the buffer cache assoicated with them are first freed.  The
newest entry will have to create all new buffer cache for each part of its
file as the old buffer cache is now orphaned as well.

Patch below fixes this by making get_cramfs_inode() use the inode cache before
blindly creating a new entry every time.  This eliminates the duplicate inodes
and duplicate buffer cache.

Cc: Phillip Lougher <phillip@lougher.demon.co.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-07 16:57:33 -07:00

560 lines
14 KiB
C

/*
* 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 <asm/semaphore.h>
#include <asm/uaccess.h>
static struct super_operations cramfs_ops;
static struct inode_operations cramfs_dir_inode_operations;
static struct file_operations cramfs_directory_operations;
static struct address_space_operations cramfs_aops;
static DECLARE_MUTEX(read_mutex);
/* These two macros may change in future, to provide better st_ino
semantics. */
#define CRAMINO(x) ((x)->offset?(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;
if (inode->i_ino != CRAMINO(cramfs_inode))
return 0; /* does not match */
if (inode->i_ino != 1)
return 1;
/* all empty directories, char, block, pipe, and sock, share inode #1 */
if ((inode->i_mode != cramfs_inode->mode) ||
(inode->i_gid != cramfs_inode->gid) ||
(inode->i_uid != cramfs_inode->uid))
return 0; /* does not match */
if ((S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode)) &&
(inode->i_rdev != old_decode_dev(cramfs_inode->size)))
return 0; /* does not match */
return 1; /* matches */
}
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_blksize = PAGE_CACHE_SIZE;
inode->i_gid = cramfs_inode->gid;
/* Struct copy intentional */
inode->i_mtime = inode->i_atime = inode->i_ctime = zerotime;
inode->i_ino = CRAMINO(cramfs_inode);
/* 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;
}
/*
* 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, unread;
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. */
unread = 0;
for (i = 0; i < BLKS_PER_BUF; i++) {
struct page *page = NULL;
if (blocknr + i < devsize) {
page = read_cache_page(mapping, blocknr + i,
(filler_t *)mapping->a_ops->readpage,
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 = kmalloc(sizeof(struct cramfs_sb_info), GFP_KERNEL);
if (!sbi)
return -ENOMEM;
sb->s_fs_info = sbi;
memset(sbi, 0, sizeof(struct cramfs_sb_info));
/* Invalidate the read buffers on mount: think disk change.. */
down(&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));
up(&read_mutex);
/* Do sanity checks on the superblock */
if (super.magic != CRAMFS_MAGIC) {
/* check at 512 byte offset */
down(&read_mutex);
memcpy(&super, cramfs_read(sb, 512, sizeof(super)), sizeof(super));
up(&read_mutex);
if (super.magic != CRAMFS_MAGIC) {
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 super_block *sb, struct kstatfs *buf)
{
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_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(256, 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;
down(&read_mutex);
de = cramfs_read(sb, OFFSET(inode) + offset, sizeof(*de)+256);
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;
up(&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;
down(&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)+256);
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) {
up(&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;
up(&read_mutex);
d_add(dentry, get_cramfs_inode(dir->i_sb, &entry));
return NULL;
}
/* else (retval < 0) */
if (sorted)
break;
}
up(&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;
down(&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);
up(&read_mutex);
pgdata = kmap(page);
if (compr_len == 0)
; /* hole */
else {
down(&read_mutex);
bytes_filled = cramfs_uncompress_block(pgdata,
PAGE_CACHE_SIZE,
cramfs_read(sb, start_offset, compr_len),
compr_len);
up(&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 struct address_space_operations cramfs_aops = {
.readpage = cramfs_readpage
};
/*
* Our operations:
*/
/*
* A directory can only readdir
*/
static struct file_operations cramfs_directory_operations = {
.llseek = generic_file_llseek,
.read = generic_read_dir,
.readdir = cramfs_readdir,
};
static struct inode_operations cramfs_dir_inode_operations = {
.lookup = cramfs_lookup,
};
static struct super_operations cramfs_ops = {
.put_super = cramfs_put_super,
.remount_fs = cramfs_remount,
.statfs = cramfs_statfs,
};
static struct super_block *cramfs_get_sb(struct file_system_type *fs_type,
int flags, const char *dev_name, void *data)
{
return get_sb_bdev(fs_type, flags, dev_name, data, cramfs_fill_super);
}
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)
{
cramfs_uncompress_init();
return register_filesystem(&cramfs_fs_type);
}
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");