Squashfs: super block operations
Signed-off-by: Phillip Lougher <phillip@lougher.demon.co.uk>
This commit is contained in:
Phillip Lougher
parent
1dc4bba39d
commit
0aa6661905
1 changed files with 440 additions and 0 deletions
440
fs/squashfs/super.c
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440
fs/squashfs/super.c
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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@lougher.demon.co.uk>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2,
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* or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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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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#include <linux/fs.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/zlib.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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static struct file_system_type squashfs_fs_type;
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static struct super_operations squashfs_super_ops;
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static int supported_squashfs_filesystem(short major, short minor, short comp)
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{
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if (major < SQUASHFS_MAJOR) {
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ERROR("Major/Minor mismatch, older Squashfs %d.%d "
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"filesystems are unsupported\n", major, minor);
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return -EINVAL;
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} else if (major > SQUASHFS_MAJOR || minor > SQUASHFS_MINOR) {
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ERROR("Major/Minor mismatch, trying to mount newer "
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"%d.%d filesystem\n", major, minor);
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ERROR("Please update your kernel\n");
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return -EINVAL;
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}
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if (comp != ZLIB_COMPRESSION)
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return -EINVAL;
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return 0;
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}
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static int squashfs_fill_super(struct super_block *sb, void *data, int silent)
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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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char b[BDEVNAME_SIZE];
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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;
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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->stream.workspace = kmalloc(zlib_inflate_workspacesize(),
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GFP_KERNEL);
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if (msblk->stream.workspace == NULL) {
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ERROR("Failed to allocate zlib workspace\n");
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goto failure;
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}
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sblk = kzalloc(sizeof(*sblk), GFP_KERNEL);
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if (sblk == NULL) {
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ERROR("Failed to allocate squashfs_super_block\n");
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goto failure;
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}
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msblk->devblksize = sb_min_blocksize(sb, BLOCK_SIZE);
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msblk->devblksize_log2 = ffz(~msblk->devblksize);
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mutex_init(&msblk->read_data_mutex);
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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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err = squashfs_read_table(sb, sblk, SQUASHFS_START, sizeof(*sblk));
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if (err < 0) {
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ERROR("unable to read squashfs_super_block\n");
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goto failed_mount;
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}
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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 (!silent)
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ERROR("Can't find a SQUASHFS superblock on %s\n",
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bdevname(sb->s_bdev, b));
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err = -EINVAL;
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goto failed_mount;
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}
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/* Check the MAJOR & MINOR versions and compression type */
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err = supported_squashfs_filesystem(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 (err < 0)
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goto failed_mount;
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err = -EINVAL;
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/*
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* Check if there's xattrs in the filesystem. These are not
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* supported in this version, so warn that they will be ignored.
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*/
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if (le64_to_cpu(sblk->xattr_table_start) != SQUASHFS_INVALID_BLK)
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ERROR("Xattrs in filesystem, these will be ignored\n");
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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 failed_mount;
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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 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 failed_mount;
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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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flags = le16_to_cpu(sblk->flags);
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TRACE("Found valid superblock on %s\n", bdevname(sb->s_bdev, b));
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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", le32_to_cpu(sblk->fragments));
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TRACE("Number of ids %d\n", le16_to_cpu(sblk->no_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_flags |= MS_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", 1, msblk->block_size);
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if (msblk->read_page == NULL) {
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ERROR("Failed to allocate read_page block\n");
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goto failed_mount;
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}
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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), le16_to_cpu(sblk->no_ids));
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if (IS_ERR(msblk->id_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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fragments = le32_to_cpu(sblk->fragments);
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if (fragments == 0)
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goto allocate_lookup_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), fragments);
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if (IS_ERR(msblk->fragment_index)) {
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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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allocate_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 allocate_root;
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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, msblk->inodes);
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if (IS_ERR(msblk->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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sb->s_export_op = &squashfs_export_ops;
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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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iget_failed(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_alloc_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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iput(root);
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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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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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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->stream.workspace);
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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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failure:
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kfree(msblk->stream.workspace);
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kfree(sb->s_fs_info);
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sb->s_fs_info = NULL;
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return -ENOMEM;
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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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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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return 0;
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}
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static int squashfs_remount(struct super_block *sb, int *flags, char *data)
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{
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*flags |= MS_RDONLY;
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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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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->stream.workspace);
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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 int squashfs_get_sb(struct file_system_type *fs_type, int flags,
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const char *dev_name, void *data,
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struct vfsmount *mnt)
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{
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return get_sb_bdev(fs_type, flags, dev_name, data, squashfs_fill_super,
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mnt);
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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, 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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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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printk(KERN_INFO "squashfs: version 4.0 (2009/01/03) "
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"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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static void squashfs_destroy_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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.get_sb = squashfs_get_sb,
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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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static struct super_operations squashfs_super_ops = {
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.alloc_inode = squashfs_alloc_inode,
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.destroy_inode = squashfs_destroy_inode,
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.statfs = squashfs_statfs,
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.put_super = squashfs_put_super,
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.remount_fs = squashfs_remount
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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@lougher.demon.co.uk>");
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MODULE_LICENSE("GPL");
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