fs/squashfs/super.c - fp2-dev/kernel/msm - Gitiles

 /*
  * 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"

 static struct file_system_type squashfs_fs_type;
 static const struct super_operations squashfs_super_ops;

 static int supported_squashfs_filesystem(short major, short minor, short comp)
 {
 	if (major < SQUASHFS_MAJOR) {
 		ERROR("Major/Minor mismatch, older Squashfs %d.%d "
 			"filesystems are unsupported\n", major, minor);
 		return -EINVAL;
 	} 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 -EINVAL;
 	}

 	if (comp != ZLIB_COMPRESSION)
 		return -EINVAL;

 	return 0;
 }


 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;

 	msblk->stream = squashfs_zlib_init();
 	if (msblk->stream == NULL)
 		goto failure;

 	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;
 	}

 	/* 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));
 		err = -EINVAL;
 		goto failed_mount;
 	}

 	/* Check the MAJOR & MINOR versions and compression type */
 	err = supported_squashfs_filesystem(le16_to_cpu(sblk->s_major),
 			le16_to_cpu(sblk->s_minor),
 			le16_to_cpu(sblk->compression));
 	if (err < 0)
 		goto failed_mount;

 	err = -EINVAL;

 	/*
 	 * 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->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_zlib_free(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:
 	squashfs_zlib_free(msblk->stream);
 	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_zlib_free(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");
	/*
	* 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"

	static struct file_system_type squashfs_fs_type;
	static const struct super_operations squashfs_super_ops;

	static int supported_squashfs_filesystem(short major, short minor, short comp)
	{
	if (major < SQUASHFS_MAJOR) {
	ERROR("Major/Minor mismatch, older Squashfs %d.%d "
	"filesystems are unsupported\n", major, minor);
	return -EINVAL;
	} 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 -EINVAL;
	}

	if (comp != ZLIB_COMPRESSION)
	return -EINVAL;

	return 0;
	}


	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;

	msblk->stream = squashfs_zlib_init();
	if (msblk->stream == NULL)
	goto failure;

	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;
	}

	/* 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));
	err = -EINVAL;
	goto failed_mount;
	}

	/* Check the MAJOR & MINOR versions and compression type */
	err = supported_squashfs_filesystem(le16_to_cpu(sblk->s_major),
	le16_to_cpu(sblk->s_minor),
	le16_to_cpu(sblk->compression));
	if (err < 0)
	goto failed_mount;

	err = -EINVAL;

	/*
	* 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->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_zlib_free(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:
	squashfs_zlib_free(msblk->stream);
	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_zlib_free(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");