Squashfs: export operations
Signed-off-by: Phillip Lougher <phillip@lougher.demon.co.uk>
This commit is contained in:
Phillip Lougher
parent
0aa6661905
commit
122601408d
155
fs/squashfs/export.c
Normal file
155
fs/squashfs/export.c
Normal file
@ -0,0 +1,155 @@
|
||||
/*
|
||||
* Squashfs - a compressed read only filesystem for Linux
|
||||
*
|
||||
* Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008
|
||||
* Phillip Lougher <phillip@lougher.demon.co.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/zlib.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 = child->d_inode;
|
||||
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, unsigned int inodes)
|
||||
{
|
||||
unsigned int length = SQUASHFS_LOOKUP_BLOCK_BYTES(inodes);
|
||||
__le64 *inode_lookup_table;
|
||||
int err;
|
||||
|
||||
TRACE("In read_inode_lookup_table, length %d\n", length);
|
||||
|
||||
/* Allocate inode lookup table indexes */
|
||||
inode_lookup_table = kmalloc(length, GFP_KERNEL);
|
||||
if (inode_lookup_table == NULL) {
|
||||
ERROR("Failed to allocate inode lookup table\n");
|
||||
return ERR_PTR(-ENOMEM);
|
||||
}
|
||||
|
||||
err = squashfs_read_table(sb, inode_lookup_table, lookup_table_start,
|
||||
length);
|
||||
if (err < 0) {
|
||||
ERROR("unable to read inode lookup table\n");
|
||||
kfree(inode_lookup_table);
|
||||
return ERR_PTR(err);
|
||||
}
|
||||
|
||||
return inode_lookup_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
|
||||
};
|
||||
Loading…
Reference in New Issue
Block a user