linux/fs/squashfs/export.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Squashfs - a compressed read only filesystem for Linux
 *
 * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008
 * Phillip Lougher <[email protected]>
 *
 * export.c
 */

/*
 * This file implements code to make Squashfs filesystems exportable (NFS etc.)
 *
 * The export code uses an inode lookup table to map inode numbers passed in
 * filehandles to an inode location on disk.  This table is stored compressed
 * into metadata blocks.  A second index table is used to locate these.  This
 * second index table for speed of access (and because it is small) is read at
 * mount time and cached in memory.
 *
 * The inode lookup table is used only by the export code, inode disk
 * locations are directly encoded in directories, enabling direct access
 * without an intermediate lookup for all operations except the export ops.
 */

#include <linux/fs.h>
#include <linux/vfs.h>
#include <linux/dcache.h>
#include <linux/exportfs.h>
#include <linux/slab.h>

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

/*
 * Look-up inode number (ino) in table, returning the inode location.
 */
static long long squashfs_inode_lookup(struct super_block *sb, int ino_num)
{ … }


static struct dentry *squashfs_export_iget(struct super_block *sb,
	unsigned int ino_num)
{ … }


static struct dentry *squashfs_fh_to_dentry(struct super_block *sb,
		struct fid *fid, int fh_len, int fh_type)
{ … }


static struct dentry *squashfs_fh_to_parent(struct super_block *sb,
		struct fid *fid, int fh_len, int fh_type)
{ … }


static struct dentry *squashfs_get_parent(struct dentry *child)
{ … }


/*
 * Read uncompressed inode lookup table indexes off disk into memory
 */
__le64 *squashfs_read_inode_lookup_table(struct super_block *sb,
		u64 lookup_table_start, u64 next_table, unsigned int inodes)
{ … }


const struct export_operations squashfs_export_ops = …;