mirror of
https://mirrors.bfsu.edu.cn/git/linux.git
synced 2024-12-05 18:14:07 +08:00
2b0143b5c9
that's the bulk of filesystem drivers dealing with inodes of their own Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
164 lines
4.6 KiB
C
164 lines
4.6 KiB
C
/*
|
|
* 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.
|
|
*
|
|
* 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)
|
|
{
|
|
struct squashfs_sb_info *msblk = sb->s_fs_info;
|
|
int blk = SQUASHFS_LOOKUP_BLOCK(ino_num - 1);
|
|
int offset = SQUASHFS_LOOKUP_BLOCK_OFFSET(ino_num - 1);
|
|
u64 start = le64_to_cpu(msblk->inode_lookup_table[blk]);
|
|
__le64 ino;
|
|
int err;
|
|
|
|
TRACE("Entered squashfs_inode_lookup, inode_number = %d\n", ino_num);
|
|
|
|
err = squashfs_read_metadata(sb, &ino, &start, &offset, sizeof(ino));
|
|
if (err < 0)
|
|
return err;
|
|
|
|
TRACE("squashfs_inode_lookup, inode = 0x%llx\n",
|
|
(u64) le64_to_cpu(ino));
|
|
|
|
return le64_to_cpu(ino);
|
|
}
|
|
|
|
|
|
static struct dentry *squashfs_export_iget(struct super_block *sb,
|
|
unsigned int ino_num)
|
|
{
|
|
long long ino;
|
|
struct dentry *dentry = ERR_PTR(-ENOENT);
|
|
|
|
TRACE("Entered squashfs_export_iget\n");
|
|
|
|
ino = squashfs_inode_lookup(sb, ino_num);
|
|
if (ino >= 0)
|
|
dentry = d_obtain_alias(squashfs_iget(sb, ino, ino_num));
|
|
|
|
return dentry;
|
|
}
|
|
|
|
|
|
static struct dentry *squashfs_fh_to_dentry(struct super_block *sb,
|
|
struct fid *fid, int fh_len, int fh_type)
|
|
{
|
|
if ((fh_type != FILEID_INO32_GEN && fh_type != FILEID_INO32_GEN_PARENT)
|
|
|| fh_len < 2)
|
|
return NULL;
|
|
|
|
return squashfs_export_iget(sb, fid->i32.ino);
|
|
}
|
|
|
|
|
|
static struct dentry *squashfs_fh_to_parent(struct super_block *sb,
|
|
struct fid *fid, int fh_len, int fh_type)
|
|
{
|
|
if (fh_type != FILEID_INO32_GEN_PARENT || fh_len < 4)
|
|
return NULL;
|
|
|
|
return squashfs_export_iget(sb, fid->i32.parent_ino);
|
|
}
|
|
|
|
|
|
static struct dentry *squashfs_get_parent(struct dentry *child)
|
|
{
|
|
struct inode *inode = d_inode(child);
|
|
unsigned int parent_ino = squashfs_i(inode)->parent;
|
|
|
|
return squashfs_export_iget(inode->i_sb, parent_ino);
|
|
}
|
|
|
|
|
|
/*
|
|
* 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)
|
|
{
|
|
unsigned int length = SQUASHFS_LOOKUP_BLOCK_BYTES(inodes);
|
|
__le64 *table;
|
|
|
|
TRACE("In read_inode_lookup_table, length %d\n", length);
|
|
|
|
/* Sanity check values */
|
|
|
|
/* there should always be at least one inode */
|
|
if (inodes == 0)
|
|
return ERR_PTR(-EINVAL);
|
|
|
|
/* length bytes should not extend into the next table - this check
|
|
* also traps instances where lookup_table_start is incorrectly larger
|
|
* than the next table start
|
|
*/
|
|
if (lookup_table_start + length > next_table)
|
|
return ERR_PTR(-EINVAL);
|
|
|
|
table = squashfs_read_table(sb, lookup_table_start, length);
|
|
|
|
/*
|
|
* table[0] points to the first inode lookup table metadata block,
|
|
* this should be less than lookup_table_start
|
|
*/
|
|
if (!IS_ERR(table) && le64_to_cpu(table[0]) >= lookup_table_start) {
|
|
kfree(table);
|
|
return ERR_PTR(-EINVAL);
|
|
}
|
|
|
|
return table;
|
|
}
|
|
|
|
|
|
const struct export_operations squashfs_export_ops = {
|
|
.fh_to_dentry = squashfs_fh_to_dentry,
|
|
.fh_to_parent = squashfs_fh_to_parent,
|
|
.get_parent = squashfs_get_parent
|
|
};
|