// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* Squashfs - a compressed read only filesystem for Linux
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*
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* Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008
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* Phillip Lougher <phillip@squashfs.org.uk>
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*
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* super.c
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*/
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/*
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* This file implements code to read the superblock, read and initialise
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* in-memory structures at mount time, and all the VFS glue code to register
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* the filesystem.
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/fs.h>
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#include <linux/fs_context.h>
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#include <linux/vfs.h>
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#include <linux/slab.h>
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#include <linux/mutex.h>
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#include <linux/pagemap.h>
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#include <linux/init.h>
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#include <linux/module.h>
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#include <linux/magic.h>
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#include <linux/xattr.h>
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#include "squashfs_fs.h"
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#include "squashfs_fs_sb.h"
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#include "squashfs_fs_i.h"
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#include "squashfs.h"
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#include "decompressor.h"
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#include "xattr.h"
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static struct file_system_type squashfs_fs_type;
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static const struct super_operations squashfs_super_ops;
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static const struct squashfs_decompressor *supported_squashfs_filesystem(
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struct fs_context *fc,
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short major, short minor, short id)
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{
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const struct squashfs_decompressor *decompressor;
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if (major < SQUASHFS_MAJOR) {
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errorf(fc, "Major/Minor mismatch, older Squashfs %d.%d "
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"filesystems are unsupported", major, minor);
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return NULL;
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} else if (major > SQUASHFS_MAJOR || minor > SQUASHFS_MINOR) {
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errorf(fc, "Major/Minor mismatch, trying to mount newer "
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"%d.%d filesystem", major, minor);
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errorf(fc, "Please update your kernel");
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return NULL;
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}
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decompressor = squashfs_lookup_decompressor(id);
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if (!decompressor->supported) {
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errorf(fc, "Filesystem uses \"%s\" compression. This is not supported",
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decompressor->name);
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return NULL;
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}
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return decompressor;
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}
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static int squashfs_fill_super(struct super_block *sb, struct fs_context *fc)
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{
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struct squashfs_sb_info *msblk;
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struct squashfs_super_block *sblk = NULL;
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struct inode *root;
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long long root_inode;
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unsigned short flags;
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unsigned int fragments;
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u64 lookup_table_start, xattr_id_table_start, next_table;
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int err;
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TRACE("Entered squashfs_fill_superblock\n");
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sb->s_fs_info = kzalloc(sizeof(*msblk), GFP_KERNEL);
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if (sb->s_fs_info == NULL) {
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ERROR("Failed to allocate squashfs_sb_info\n");
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return -ENOMEM;
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}
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msblk = sb->s_fs_info;
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msblk->devblksize = sb_min_blocksize(sb, SQUASHFS_DEVBLK_SIZE);
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msblk->devblksize_log2 = ffz(~msblk->devblksize);
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mutex_init(&msblk->meta_index_mutex);
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/*
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* msblk->bytes_used is checked in squashfs_read_table to ensure reads
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* are not beyond filesystem end. But as we're using
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* squashfs_read_table here to read the superblock (including the value
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* of bytes_used) we need to set it to an initial sensible dummy value
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*/
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msblk->bytes_used = sizeof(*sblk);
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sblk = squashfs_read_table(sb, SQUASHFS_START, sizeof(*sblk));
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if (IS_ERR(sblk)) {
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errorf(fc, "unable to read squashfs_super_block");
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err = PTR_ERR(sblk);
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sblk = NULL;
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goto failed_mount;
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}
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err = -EINVAL;
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/* Check it is a SQUASHFS superblock */
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sb->s_magic = le32_to_cpu(sblk->s_magic);
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if (sb->s_magic != SQUASHFS_MAGIC) {
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if (!(fc->sb_flags & SB_SILENT))
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errorf(fc, "Can't find a SQUASHFS superblock on %pg",
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sb->s_bdev);
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goto failed_mount;
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}
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/* Check the MAJOR & MINOR versions and lookup compression type */
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msblk->decompressor = supported_squashfs_filesystem(
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fc,
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le16_to_cpu(sblk->s_major),
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le16_to_cpu(sblk->s_minor),
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le16_to_cpu(sblk->compression));
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if (msblk->decompressor == NULL)
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goto failed_mount;
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/* Check the filesystem does not extend beyond the end of the
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block device */
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msblk->bytes_used = le64_to_cpu(sblk->bytes_used);
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if (msblk->bytes_used < 0 || msblk->bytes_used >
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i_size_read(sb->s_bdev->bd_inode))
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goto failed_mount;
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/* Check block size for sanity */
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msblk->block_size = le32_to_cpu(sblk->block_size);
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if (msblk->block_size > SQUASHFS_FILE_MAX_SIZE)
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goto insanity;
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/*
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* Check the system page size is not larger than the filesystem
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* block size (by default 128K). This is currently not supported.
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*/
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if (PAGE_SIZE > msblk->block_size) {
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errorf(fc, "Page size > filesystem block size (%d). This is "
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"currently not supported!", msblk->block_size);
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goto failed_mount;
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}
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/* Check block log for sanity */
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msblk->block_log = le16_to_cpu(sblk->block_log);
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if (msblk->block_log > SQUASHFS_FILE_MAX_LOG)
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goto failed_mount;
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/* Check that block_size and block_log match */
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if (msblk->block_size != (1 << msblk->block_log))
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goto insanity;
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/* Check the root inode for sanity */
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root_inode = le64_to_cpu(sblk->root_inode);
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if (SQUASHFS_INODE_OFFSET(root_inode) > SQUASHFS_METADATA_SIZE)
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goto insanity;
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msblk->inode_table = le64_to_cpu(sblk->inode_table_start);
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msblk->directory_table = le64_to_cpu(sblk->directory_table_start);
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msblk->inodes = le32_to_cpu(sblk->inodes);
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msblk->fragments = le32_to_cpu(sblk->fragments);
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msblk->ids = le16_to_cpu(sblk->no_ids);
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flags = le16_to_cpu(sblk->flags);
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TRACE("Found valid superblock on %pg\n", sb->s_bdev);
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TRACE("Inodes are %scompressed\n", SQUASHFS_UNCOMPRESSED_INODES(flags)
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? "un" : "");
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TRACE("Data is %scompressed\n", SQUASHFS_UNCOMPRESSED_DATA(flags)
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? "un" : "");
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TRACE("Filesystem size %lld bytes\n", msblk->bytes_used);
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TRACE("Block size %d\n", msblk->block_size);
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TRACE("Number of inodes %d\n", msblk->inodes);
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TRACE("Number of fragments %d\n", msblk->fragments);
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TRACE("Number of ids %d\n", msblk->ids);
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TRACE("sblk->inode_table_start %llx\n", msblk->inode_table);
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TRACE("sblk->directory_table_start %llx\n", msblk->directory_table);
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TRACE("sblk->fragment_table_start %llx\n",
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(u64) le64_to_cpu(sblk->fragment_table_start));
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TRACE("sblk->id_table_start %llx\n",
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(u64) le64_to_cpu(sblk->id_table_start));
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sb->s_maxbytes = MAX_LFS_FILESIZE;
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sb->s_time_min = 0;
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sb->s_time_max = U32_MAX;
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sb->s_flags |= SB_RDONLY;
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sb->s_op = &squashfs_super_ops;
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err = -ENOMEM;
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msblk->block_cache = squashfs_cache_init("metadata",
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SQUASHFS_CACHED_BLKS, SQUASHFS_METADATA_SIZE);
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if (msblk->block_cache == NULL)
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goto failed_mount;
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/* Allocate read_page block */
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msblk->read_page = squashfs_cache_init("data",
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squashfs_max_decompressors(), msblk->block_size);
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if (msblk->read_page == NULL) {
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errorf(fc, "Failed to allocate read_page block");
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goto failed_mount;
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}
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msblk->stream = squashfs_decompressor_setup(sb, flags);
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if (IS_ERR(msblk->stream)) {
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err = PTR_ERR(msblk->stream);
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msblk->stream = NULL;
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goto insanity;
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}
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/* Handle xattrs */
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sb->s_xattr = squashfs_xattr_handlers;
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xattr_id_table_start = le64_to_cpu(sblk->xattr_id_table_start);
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if (xattr_id_table_start == SQUASHFS_INVALID_BLK) {
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next_table = msblk->bytes_used;
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goto allocate_id_index_table;
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}
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/* Allocate and read xattr id lookup table */
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msblk->xattr_id_table = squashfs_read_xattr_id_table(sb,
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xattr_id_table_start, &msblk->xattr_table, &msblk->xattr_ids);
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if (IS_ERR(msblk->xattr_id_table)) {
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errorf(fc, "unable to read xattr id index table");
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err = PTR_ERR(msblk->xattr_id_table);
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msblk->xattr_id_table = NULL;
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if (err != -ENOTSUPP)
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goto failed_mount;
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}
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next_table = msblk->xattr_table;
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allocate_id_index_table:
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/* Allocate and read id index table */
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msblk->id_table = squashfs_read_id_index_table(sb,
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le64_to_cpu(sblk->id_table_start), next_table, msblk->ids);
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if (IS_ERR(msblk->id_table)) {
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errorf(fc, "unable to read id index table");
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err = PTR_ERR(msblk->id_table);
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msblk->id_table = NULL;
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goto failed_mount;
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}
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next_table = le64_to_cpu(msblk->id_table[0]);
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/* Handle inode lookup table */
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lookup_table_start = le64_to_cpu(sblk->lookup_table_start);
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if (lookup_table_start == SQUASHFS_INVALID_BLK)
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goto handle_fragments;
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/* Allocate and read inode lookup table */
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msblk->inode_lookup_table = squashfs_read_inode_lookup_table(sb,
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lookup_table_start, next_table, msblk->inodes);
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if (IS_ERR(msblk->inode_lookup_table)) {
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errorf(fc, "unable to read inode lookup table");
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err = PTR_ERR(msblk->inode_lookup_table);
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msblk->inode_lookup_table = NULL;
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goto failed_mount;
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}
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next_table = le64_to_cpu(msblk->inode_lookup_table[0]);
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sb->s_export_op = &squashfs_export_ops;
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handle_fragments:
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fragments = msblk->fragments;
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if (fragments == 0)
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goto check_directory_table;
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msblk->fragment_cache = squashfs_cache_init("fragment",
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SQUASHFS_CACHED_FRAGMENTS, msblk->block_size);
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if (msblk->fragment_cache == NULL) {
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err = -ENOMEM;
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goto failed_mount;
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}
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/* Allocate and read fragment index table */
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msblk->fragment_index = squashfs_read_fragment_index_table(sb,
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le64_to_cpu(sblk->fragment_table_start), next_table, fragments);
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if (IS_ERR(msblk->fragment_index)) {
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errorf(fc, "unable to read fragment index table");
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err = PTR_ERR(msblk->fragment_index);
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msblk->fragment_index = NULL;
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goto failed_mount;
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}
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next_table = le64_to_cpu(msblk->fragment_index[0]);
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check_directory_table:
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/* Sanity check directory_table */
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if (msblk->directory_table > next_table) {
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err = -EINVAL;
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goto insanity;
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}
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/* Sanity check inode_table */
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if (msblk->inode_table >= msblk->directory_table) {
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err = -EINVAL;
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goto insanity;
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}
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/* allocate root */
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root = new_inode(sb);
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if (!root) {
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err = -ENOMEM;
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goto failed_mount;
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}
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err = squashfs_read_inode(root, root_inode);
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if (err) {
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make_bad_inode(root);
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iput(root);
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goto failed_mount;
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}
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insert_inode_hash(root);
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sb->s_root = d_make_root(root);
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if (sb->s_root == NULL) {
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ERROR("Root inode create failed\n");
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err = -ENOMEM;
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goto failed_mount;
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}
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TRACE("Leaving squashfs_fill_super\n");
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kfree(sblk);
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return 0;
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insanity:
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errorf(fc, "squashfs image failed sanity check");
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failed_mount:
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squashfs_cache_delete(msblk->block_cache);
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squashfs_cache_delete(msblk->fragment_cache);
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squashfs_cache_delete(msblk->read_page);
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squashfs_decompressor_destroy(msblk);
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kfree(msblk->inode_lookup_table);
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kfree(msblk->fragment_index);
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kfree(msblk->id_table);
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kfree(msblk->xattr_id_table);
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kfree(sb->s_fs_info);
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sb->s_fs_info = NULL;
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kfree(sblk);
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return err;
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}
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static int squashfs_get_tree(struct fs_context *fc)
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{
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return get_tree_bdev(fc, squashfs_fill_super);
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}
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static int squashfs_reconfigure(struct fs_context *fc)
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{
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sync_filesystem(fc->root->d_sb);
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fc->sb_flags |= SB_RDONLY;
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return 0;
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}
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static const struct fs_context_operations squashfs_context_ops = {
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.get_tree = squashfs_get_tree,
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.reconfigure = squashfs_reconfigure,
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};
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static int squashfs_init_fs_context(struct fs_context *fc)
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{
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fc->ops = &squashfs_context_ops;
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return 0;
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}
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static int squashfs_statfs(struct dentry *dentry, struct kstatfs *buf)
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{
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struct squashfs_sb_info *msblk = dentry->d_sb->s_fs_info;
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u64 id = huge_encode_dev(dentry->d_sb->s_bdev->bd_dev);
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TRACE("Entered squashfs_statfs\n");
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buf->f_type = SQUASHFS_MAGIC;
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buf->f_bsize = msblk->block_size;
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buf->f_blocks = ((msblk->bytes_used - 1) >> msblk->block_log) + 1;
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buf->f_bfree = buf->f_bavail = 0;
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buf->f_files = msblk->inodes;
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buf->f_ffree = 0;
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buf->f_namelen = SQUASHFS_NAME_LEN;
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buf->f_fsid = u64_to_fsid(id);
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return 0;
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}
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static void squashfs_put_super(struct super_block *sb)
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{
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if (sb->s_fs_info) {
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struct squashfs_sb_info *sbi = sb->s_fs_info;
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squashfs_cache_delete(sbi->block_cache);
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squashfs_cache_delete(sbi->fragment_cache);
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squashfs_cache_delete(sbi->read_page);
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squashfs_decompressor_destroy(sbi);
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kfree(sbi->id_table);
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kfree(sbi->fragment_index);
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kfree(sbi->meta_index);
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kfree(sbi->inode_lookup_table);
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kfree(sbi->xattr_id_table);
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kfree(sb->s_fs_info);
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sb->s_fs_info = NULL;
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}
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}
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static struct kmem_cache *squashfs_inode_cachep;
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static void init_once(void *foo)
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{
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struct squashfs_inode_info *ei = foo;
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inode_init_once(&ei->vfs_inode);
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}
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static int __init init_inodecache(void)
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{
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squashfs_inode_cachep = kmem_cache_create("squashfs_inode_cache",
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sizeof(struct squashfs_inode_info), 0,
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SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT|SLAB_ACCOUNT,
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init_once);
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return squashfs_inode_cachep ? 0 : -ENOMEM;
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}
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static void destroy_inodecache(void)
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{
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/*
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* Make sure all delayed rcu free inodes are flushed before we
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* destroy cache.
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*/
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rcu_barrier();
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kmem_cache_destroy(squashfs_inode_cachep);
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}
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static int __init init_squashfs_fs(void)
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{
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int err = init_inodecache();
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if (err)
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return err;
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err = register_filesystem(&squashfs_fs_type);
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if (err) {
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destroy_inodecache();
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return err;
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}
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pr_info("version 4.0 (2009/01/31) Phillip Lougher\n");
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return 0;
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}
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static void __exit exit_squashfs_fs(void)
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{
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unregister_filesystem(&squashfs_fs_type);
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destroy_inodecache();
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}
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static struct inode *squashfs_alloc_inode(struct super_block *sb)
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{
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struct squashfs_inode_info *ei =
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kmem_cache_alloc(squashfs_inode_cachep, GFP_KERNEL);
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return ei ? &ei->vfs_inode : NULL;
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}
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|
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static void squashfs_free_inode(struct inode *inode)
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{
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kmem_cache_free(squashfs_inode_cachep, squashfs_i(inode));
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}
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static struct file_system_type squashfs_fs_type = {
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.owner = THIS_MODULE,
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.name = "squashfs",
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.init_fs_context = squashfs_init_fs_context,
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.kill_sb = kill_block_super,
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.fs_flags = FS_REQUIRES_DEV
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};
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MODULE_ALIAS_FS("squashfs");
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static const struct super_operations squashfs_super_ops = {
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.alloc_inode = squashfs_alloc_inode,
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.free_inode = squashfs_free_inode,
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.statfs = squashfs_statfs,
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.put_super = squashfs_put_super,
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};
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module_init(init_squashfs_fs);
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module_exit(exit_squashfs_fs);
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MODULE_DESCRIPTION("squashfs 4.0, a compressed read-only filesystem");
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MODULE_AUTHOR("Phillip Lougher <phillip@squashfs.org.uk>");
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MODULE_LICENSE("GPL");
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MODULE_IMPORT_NS(ANDROID_GKI_VFS_EXPORT_ONLY);
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