/*
   * Squashfs - a compressed read only filesystem for Linux
   *
   * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008

   * Phillip Lougher <phillip@squashfs.org.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/mutex.h>
  #include <linux/pagemap.h>
  #include <linux/init.h>
  #include <linux/module.h>

  #include <linux/magic.h>

  #include <linux/xattr.h>

  
  #include "squashfs_fs.h"
  #include "squashfs_fs_sb.h"
  #include "squashfs_fs_i.h"
  #include "squashfs.h"

  #include "decompressor.h"

  #include "xattr.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
  ", major, minor);

  		return NULL;

  	} else if (major > SQUASHFS_MAJOR || minor > SQUASHFS_MINOR) {
  		ERROR("Major/Minor mismatch, trying to mount newer "
  			"%d.%d filesystem
  ", major, minor);
  		ERROR("Please update your kernel
  ");

  		return NULL;

  	}

  	decompressor = squashfs_lookup_decompressor(id);
  	if (!decompressor->supported) {
  		ERROR("Filesystem uses \"%s\" compression. This is not "
  			"supported
  ", 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, xattr_id_table_start, next_table;

  	int err;
  
  	TRACE("Entered squashfs_fill_superblock
  ");
  
  	sb->s_fs_info = kzalloc(sizeof(*msblk), GFP_KERNEL);
  	if (sb->s_fs_info == NULL) {
  		ERROR("Failed to allocate squashfs_sb_info
  ");
  		return -ENOMEM;
  	}
  	msblk = sb->s_fs_info;

  	msblk->devblksize = sb_min_blocksize(sb, SQUASHFS_DEVBLK_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);

  	sblk = squashfs_read_table(sb, SQUASHFS_START, sizeof(*sblk));

  	if (IS_ERR(sblk)) {

  		ERROR("unable to read squashfs_super_block
  ");

  		err = PTR_ERR(sblk);
  		sblk = NULL;

  		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
  ",
  						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 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!
  ", 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
  ", bdevname(sb->s_bdev, b));
  	TRACE("Inodes are %scompressed
  ", SQUASHFS_UNCOMPRESSED_INODES(flags)
  				? "un" : "");
  	TRACE("Data is %scompressed
  ", SQUASHFS_UNCOMPRESSED_DATA(flags)
  				? "un" : "");
  	TRACE("Filesystem size %lld bytes
  ", msblk->bytes_used);
  	TRACE("Block size %d
  ", msblk->block_size);
  	TRACE("Number of inodes %d
  ", msblk->inodes);
  	TRACE("Number of fragments %d
  ", le32_to_cpu(sblk->fragments));
  	TRACE("Number of ids %d
  ", le16_to_cpu(sblk->no_ids));
  	TRACE("sblk->inode_table_start %llx
  ", msblk->inode_table);
  	TRACE("sblk->directory_table_start %llx
  ", msblk->directory_table);
  	TRACE("sblk->fragment_table_start %llx
  ",
  		(u64) le64_to_cpu(sblk->fragment_table_start));
  	TRACE("sblk->id_table_start %llx
  ",
  		(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
  ");
  		goto failed_mount;
  	}

  	msblk->stream = squashfs_decompressor_init(sb, flags);
  	if (IS_ERR(msblk->stream)) {
  		err = PTR_ERR(msblk->stream);
  		msblk->stream = NULL;
  		goto failed_mount;
  	}

  	/* Handle xattrs */
  	sb->s_xattr = squashfs_xattr_handlers;
  	xattr_id_table_start = le64_to_cpu(sblk->xattr_id_table_start);

  	if (xattr_id_table_start == SQUASHFS_INVALID_BLK) {
  		next_table = msblk->bytes_used;

  		goto allocate_id_index_table;

  	}

  
  	/* Allocate and read xattr id lookup table */
  	msblk->xattr_id_table = squashfs_read_xattr_id_table(sb,
  		xattr_id_table_start, &msblk->xattr_table, &msblk->xattr_ids);
  	if (IS_ERR(msblk->xattr_id_table)) {
  		ERROR("unable to read xattr id index table
  ");
  		err = PTR_ERR(msblk->xattr_id_table);
  		msblk->xattr_id_table = NULL;
  		if (err != -ENOTSUPP)
  			goto failed_mount;
  	}

  	next_table = msblk->xattr_table;

  
  allocate_id_index_table:

  	/* Allocate and read id index table */
  	msblk->id_table = squashfs_read_id_index_table(sb,

  		le64_to_cpu(sblk->id_table_start), next_table,
  		le16_to_cpu(sblk->no_ids));

  	if (IS_ERR(msblk->id_table)) {

  		ERROR("unable to read id index table
  ");

  		err = PTR_ERR(msblk->id_table);
  		msblk->id_table = NULL;
  		goto failed_mount;
  	}

  	next_table = le64_to_cpu(msblk->id_table[0]);

  	/* Handle inode lookup table */
  	lookup_table_start = le64_to_cpu(sblk->lookup_table_start);
  	if (lookup_table_start == SQUASHFS_INVALID_BLK)
  		goto handle_fragments;
  
  	/* Allocate and read inode lookup table */
  	msblk->inode_lookup_table = squashfs_read_inode_lookup_table(sb,

  		lookup_table_start, next_table, msblk->inodes);

  	if (IS_ERR(msblk->inode_lookup_table)) {
  		ERROR("unable to read inode lookup table
  ");
  		err = PTR_ERR(msblk->inode_lookup_table);
  		msblk->inode_lookup_table = NULL;
  		goto failed_mount;
  	}

  	next_table = le64_to_cpu(msblk->inode_lookup_table[0]);

  
  	sb->s_export_op = &squashfs_export_ops;
  
  handle_fragments:

  	fragments = le32_to_cpu(sblk->fragments);
  	if (fragments == 0)

  		goto check_directory_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), next_table, fragments);

  	if (IS_ERR(msblk->fragment_index)) {

  		ERROR("unable to read fragment index table
  ");

  		err = PTR_ERR(msblk->fragment_index);
  		msblk->fragment_index = NULL;
  		goto failed_mount;
  	}

  	next_table = le64_to_cpu(msblk->fragment_index[0]);

  check_directory_table:
  	/* Sanity check directory_table */

  	if (msblk->directory_table > next_table) {

  		err = -EINVAL;
  		goto failed_mount;
  	}
  
  	/* Sanity check inode_table */
  	if (msblk->inode_table >= msblk->directory_table) {
  		err = -EINVAL;
  		goto failed_mount;
  	}
  
  	/* allocate root */

  	root = new_inode(sb);
  	if (!root) {
  		err = -ENOMEM;
  		goto failed_mount;
  	}
  
  	err = squashfs_read_inode(root, root_inode);
  	if (err) {

  		make_bad_inode(root);
  		iput(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
  ");
  		err = -ENOMEM;
  		iput(root);
  		goto failed_mount;
  	}
  
  	TRACE("Leaving squashfs_fill_super
  ");
  	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(msblk->xattr_id_table);

  	kfree(sb->s_fs_info);
  	sb->s_fs_info = NULL;
  	kfree(sblk);
  	return err;

  }
  
  
  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
  ");
  
  	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)
  {
  	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(sbi->inode_lookup_table);

  		kfree(sbi->xattr_id_table);

  		kfree(sb->s_fs_info);
  		sb->s_fs_info = NULL;
  	}
  }

  static struct dentry *squashfs_mount(struct file_system_type *fs_type,
  				int flags, const char *dev_name, void *data)

  {

  	return mount_bdev(fs_type, flags, dev_name, data, squashfs_fill_super);

  }
  
  
  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
  ");
  
  	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_i_callback(struct rcu_head *head)

  {

  	struct inode *inode = container_of(head, struct inode, i_rcu);

  	kmem_cache_free(squashfs_inode_cachep, squashfs_i(inode));
  }

  static void squashfs_destroy_inode(struct inode *inode)
  {
  	call_rcu(&inode->i_rcu, squashfs_i_callback);
  }

  
  static struct file_system_type squashfs_fs_type = {
  	.owner = THIS_MODULE,
  	.name = "squashfs",

  	.mount = squashfs_mount,

  	.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@squashfs.org.uk>");

  MODULE_LICENSE("GPL");