/*
* Squashfs - a compressed read only filesystem for Linux
*
* Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008
* Phillip Lougher <phillip@lougher.demon.co.uk>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2,
* or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*
* super.c
*/
/*
* This file implements code to read the superblock, read and initialise
* in-memory structures at mount time, and all the VFS glue code to register
* the filesystem.
*/
#include <linux/fs.h>
#include <linux/vfs.h>
#include <linux/slab.h>
#include <linux/smp_lock.h>
#include <linux/mutex.h>
#include <linux/pagemap.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/magic.h>
#include "squashfs_fs.h"
#include "squashfs_fs_sb.h"
#include "squashfs_fs_i.h"
#include "squashfs.h"
#include "decompressor.h"
static struct file_system_type squashfs_fs_type;
static const struct super_operations squashfs_super_ops;
static const struct squashfs_decompressor *supported_squashfs_filesystem(short
major, short minor, short id)
{
const struct squashfs_decompressor *decompressor;
if (major < SQUASHFS_MAJOR) {
ERROR("Major/Minor mismatch, older Squashfs %d.%d "
"filesystems are unsupported\n", major, minor);
return NULL;
} else if (major > SQUASHFS_MAJOR || minor > SQUASHFS_MINOR) {
ERROR("Major/Minor mismatch, trying to mount newer "
"%d.%d filesystem\n", major, minor);
ERROR("Please update your kernel\n");
return NULL;
}
decompressor = squashfs_lookup_decompressor(id);
if (!decompressor->supported) {
ERROR("Filesystem uses \"%s\" compression. This is not "
"supported\n", decompressor->name);
return NULL;
}
return decompressor;
}
static int squashfs_fill_super(struct super_block *sb, void *data, int silent)
{
struct squashfs_sb_info *msblk;
struct squashfs_super_block *sblk = NULL;
char b[BDEVNAME_SIZE];
struct inode *root;
long long root_inode;
unsigned short flags;
unsigned int fragments;
u64 lookup_table_start;
int err;
TRACE("Entered squashfs_fill_superblock\n");
sb->s_fs_info = kzalloc(sizeof(*msblk), GFP_KERNEL);
if (sb->s_fs_info == NULL) {
ERROR("Failed to allocate squashfs_sb_info\n");
return -ENOMEM;
}
msblk = sb->s_fs_info;
sblk = kzalloc(sizeof(*sblk), GFP_KERNEL);
if (sblk == NULL) {
ERROR("Failed to allocate squashfs_super_block\n");
goto failure;
}
msblk->devblksize = sb_min_blocksize(sb, BLOCK_SIZE);
msblk->devblksize_log2 = ffz(~msblk->devblksize);
mutex_init(&msblk->read_data_mutex);
mutex_init(&msblk->meta_index_mutex);
/*
* msblk->bytes_used is checked in squashfs_read_table to ensure reads
* are not beyond filesystem end. But as we're using
* squashfs_read_table here to read the superblock (including the value
* of bytes_used) we need to set it to an initial sensible dummy value
*/
msblk->bytes_used = sizeof(*sblk);
err = squashfs_read_table(sb, sblk, SQUASHFS_START, sizeof(*sblk));
if (err < 0) {
ERROR("unable to read squashfs_super_block\n");
goto failed_mount;
}
err = -EINVAL;
/* Check it is a SQUASHFS superblock */
sb->s_magic = le32_to_cpu(sblk->s_magic);
if (sb->s_magic != SQUASHFS_MAGIC) {
if (!silent)
ERROR("Can't find a SQUASHFS superblock on %s\n",
bdevname(sb->s_bdev, b));
goto failed_mount;
}
/* Check the MAJOR & MINOR versions and lookup compression type */
msblk->decompressor = supported_squashfs_filesystem(
le16_to_cpu(sblk->s_major),
le16_to_cpu(sblk->s_minor),
le16_to_cpu(sblk->compression));
if (msblk->decompressor == NULL)
goto failed_mount;
/*
* Check if there's xattrs in the filesystem. These are not
* supported in this version, so warn that they will be ignored.
*/
if (le64_to_cpu(sblk->xattr_table_start) != SQUASHFS_INVALID_BLK)
ERROR("Xattrs in filesystem, these will be ignored\n");
/* Check the filesystem does not extend beyond the end of the
block device */
msblk->bytes_used = le64_to_cpu(sblk->bytes_used);
if (msblk->bytes_used < 0 || msblk->bytes_used >
i_size_read(sb->s_bdev->bd_inode))
goto failed_mount;
/* Check block size for sanity */
msblk->block_size = le32_to_cpu(sblk->block_size);
if (msblk->block_size > SQUASHFS_FILE_MAX_SIZE)
goto failed_mount;
/*
* Check the system page size is not larger than the filesystem
* block size (by default 128K). This is currently not supported.
*/
if (PAGE_CACHE_SIZE > msblk->block_size) {
ERROR("Page size > filesystem block size (%d). This is "
"currently not supported!\n", msblk->block_size);
goto failed_mount;
}
msblk->block_log = le16_to_cpu(sblk->block_log);
if (msblk->block_log > SQUASHFS_FILE_MAX_LOG)
goto failed_mount;
/* Check the root inode for sanity */
root_inode = le64_to_cpu(sblk->root_inode);
if (SQUASHFS_INODE_OFFSET(root_inode) > SQUASHFS_METADATA_SIZE)
goto failed_mount;
msblk->inode_table = le64_to_cpu(sblk->inode_table_start);
msblk->directory_table = le64_to_cpu(sblk->directory_table_start);
msblk->inodes = le32_to_cpu(sblk->inodes);
flags = le16_to_cpu(sblk->flags);
TRACE("Found valid superblock on %s\n", bdevname(sb->s_bdev, b));
TRACE("Inodes are %scompressed\n", SQUASHFS_UNCOMPRESSED_INODES(flags)
? "un" : "");
TRACE("Data is %scompressed\n", SQUASHFS_UNCOMPRESSED_DATA(flags)
? "un" : "");
TRACE("Filesystem size %lld bytes\n", msblk->bytes_used);
TRACE("Block size %d\n", msblk->block_size);
TRACE("Number of inodes %d\n", msblk->inodes);
TRACE("Number of fragments %d\n", le32_to_cpu(sblk->fragments));
TRACE("Number of ids %d\n", le16_to_cpu(sblk->no_ids));
TRACE("sblk->inode_table_start %llx\n", msblk->inode_table);
TRACE("sblk->directory_table_start %llx\n", msblk->directory_table);
TRACE("sblk->fragment_table_start %llx\n",
(u64) le64_to_cpu(sblk->fragment_table_start));
TRACE("sblk->id_table_start %llx\n",
(u64) le64_to_cpu(sblk->id_table_start));
sb->s_maxbytes = MAX_LFS_FILESIZE;
sb->s_flags |= MS_RDONLY;
sb->s_op = &squashfs_super_ops;
err = -ENOMEM;
msblk->stream = squashfs_decompressor_init(msblk);
if (msblk->stream == NULL)
goto failed_mount;
msblk->block_cache = squashfs_cache_init("metadata",
SQUASHFS_CACHED_BLKS, SQUASHFS_METADATA_SIZE);
if (msblk->block_cache == NULL)
goto failed_mount;
/* Allocate read_page block */
msblk->read_page = squashfs_cache_init("data", 1, msblk->block_size);
if (msblk->read_page == NULL) {
ERROR("Failed to allocate read_page block\n");
goto failed_mount;
}
/* Allocate and read id index table */
msblk->id_table = squashfs_read_id_index_table(sb,
le64_to_cpu(sblk->id_table_start), le16_to_cpu(sblk->no_ids));
if (IS_ERR(msblk->id_table)) {
err = PTR_ERR(msblk->id_table);
msblk->id_table = NULL;
goto failed_mount;
}
fragments = le32_to_cpu(sblk->fragments);
if (fragments == 0)
goto allocate_lookup_table;
msblk->fragment_cache = squashfs_cache_init("fragment",
SQUASHFS_CACHED_FRAGMENTS, msblk->block_size);
if (msblk->fragment_cache == NULL) {
err = -ENOMEM;
goto failed_mount;
}
/* Allocate and read fragment index table */
msblk->fragment_index = squashfs_read_fragment_index_table(sb,
le64_to_cpu(sblk->fragment_table_start), fragments);
if (IS_ERR(msblk->fragment_index)) {
err = PTR_ERR(msblk->fragment_index);
msblk->fragment_index = NULL;
goto failed_mount;
}
allocate_lookup_table:
lookup_table_start = le64_to_cpu(sblk->lookup_table_start);
if (lookup_table_start == SQUASHFS_INVALID_BLK)
goto allocate_root;
/* Allocate and read inode lookup table */
msblk->inode_lookup_table = squashfs_read_inode_lookup_table(sb,
lookup_table_start, msblk->inodes);
if (IS_ERR(msblk->inode_lookup_table)) {
err = PTR_ERR(msblk->inode_lookup_table);
msblk->inode_lookup_table = NULL;
goto failed_mount;
}
sb->s_export_op = &squashfs_export_ops;
allocate_root:
root = new_inode(sb);
if (!root) {
err = -ENOMEM;
goto failed_mount;
}
err = squashfs_read_inode(root, root_inode);
if (err) {
iget_failed(root);
goto failed_mount;
}
insert_inode_hash(root);
sb->s_root = d_alloc_root(root);
if (sb->s_root == NULL) {
ERROR("Root inode create failed\n");
err = -ENOMEM;
iput(root);
goto failed_mount;
}
TRACE("Leaving squashfs_fill_super\n");
kfree(sblk);
return 0;
failed_mount:
squashfs_cache_delete(msblk->block_cache);
squashfs_cache_delete(msblk->fragment_cache);
squashfs_cache_delete(msblk->read_page);
squashfs_decompressor_free(msblk, msblk->stream);
kfree(msblk->inode_lookup_table);
kfree(msblk->fragment_index);
kfree(msblk->id_table);
kfree(sb->s_fs_info);
sb->s_fs_info = NULL;
kfree(sblk);
return err;
failure:
kfree(sb->s_fs_info);
sb->s_fs_info = NULL;
return -ENOMEM;
}
static int squashfs_statfs(struct dentry *dentry, struct kstatfs *buf)
{
struct squashfs_sb_info *msblk = dentry->d_sb->s_fs_info;
u64 id = huge_encode_dev(dentry->d_sb->s_bdev->bd_dev);
TRACE("Entered squashfs_statfs\n");
buf->f_type = SQUASHFS_MAGIC;
buf->f_bsize = msblk->block_size;
buf->f_blocks = ((msblk->bytes_used - 1) >> msblk->block_log) + 1;
buf->f_bfree = buf->f_bavail = 0;
buf->f_files = msblk->inodes;
buf->f_ffree = 0;
buf->f_namelen = SQUASHFS_NAME_LEN;
buf->f_fsid.val[0] = (u32)id;
buf->f_fsid.val[1] = (u32)(id >> 32);
return 0;
}
static int squashfs_remount(struct super_block *sb, int *flags, char *data)
{
*flags |= MS_RDONLY;
return 0;
}
static void squashfs_put_super(struct super_block *sb)
{
lock_kernel();
if (sb->s_fs_info) {
struct squashfs_sb_info *sbi = sb->s_fs_info;
squashfs_cache_delete(sbi->block_cache);
squashfs_cache_delete(sbi->fragment_cache);
squashfs_cache_delete(sbi->read_page);
squashfs_decompressor_free(sbi, sbi->stream);
kfree(sbi->id_table);
kfree(sbi->fragment_index);
kfree(sbi->meta_index);
kfree(sb->s_fs_info);
sb->s_fs_info = NULL;
}
unlock_kernel();
}
static int squashfs_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, squashfs_fill_super,
mnt);
}
static struct kmem_cache *squashfs_inode_cachep;
static void init_once(void *foo)
{
struct squashfs_inode_info *ei = foo;
inode_init_once(&ei->vfs_inode);
}
static int __init init_inodecache(void)
{
squashfs_inode_cachep = kmem_cache_create("squashfs_inode_cache",
sizeof(struct squashfs_inode_info), 0,
SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT, init_once);
return squashfs_inode_cachep ? 0 : -ENOMEM;
}
static void destroy_inodecache(void)
{
kmem_cache_destroy(squashfs_inode_cachep);
}
static int __init init_squashfs_fs(void)
{
int err = init_inodecache();
if (err)
return err;
err = register_filesystem(&squashfs_fs_type);
if (err) {
destroy_inodecache();
return err;
}
printk(KERN_INFO "squashfs: version 4.0 (2009/01/31) "
"Phillip Lougher\n");
return 0;
}
static void __exit exit_squashfs_fs(void)
{
unregister_filesystem(&squashfs_fs_type);
destroy_inodecache();
}
static struct inode *squashfs_alloc_inode(struct super_block *sb)
{
struct squashfs_inode_info *ei =
kmem_cache_alloc(squashfs_inode_cachep, GFP_KERNEL);
return ei ? &ei->vfs_inode : NULL;
}
static void squashfs_destroy_inode(struct inode *inode)
{
kmem_cache_free(squashfs_inode_cachep, squashfs_i(inode));
}
static struct file_system_type squashfs_fs_type = {
.owner = THIS_MODULE,
.name = "squashfs",
.get_sb = squashfs_get_sb,
.kill_sb = kill_block_super,
.fs_flags = FS_REQUIRES_DEV
};
static const struct super_operations squashfs_super_ops = {
.alloc_inode = squashfs_alloc_inode,
.destroy_inode = squashfs_destroy_inode,
.statfs = squashfs_statfs,
.put_super = squashfs_put_super,
.remount_fs = squashfs_remount
};
module_init(init_squashfs_fs);
module_exit(exit_squashfs_fs);
MODULE_DESCRIPTION("squashfs 4.0, a compressed read-only filesystem");
MODULE_AUTHOR("Phillip Lougher <phillip@lougher.demon.co.uk>");
MODULE_LICENSE("GPL");
