[net-next-2.6.git] / fs / squashfs / export.c

/*
 * 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/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 = 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
};
Commit	Line	Data
12260140 PL	1	/*
	2	* Squashfs - a compressed read only filesystem for Linux
	3	*
	4	* Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008
	5	* Phillip Lougher <phillip@lougher.demon.co.uk>
	6	*
	7	* This program is free software; you can redistribute it and/or
	8	* modify it under the terms of the GNU General Public License
	9	* as published by the Free Software Foundation; either version 2,
	10	* or (at your option) any later version.
	11	*
	12	* This program is distributed in the hope that it will be useful,
	13	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	14	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	15	* GNU General Public License for more details.
	16	*
	17	* You should have received a copy of the GNU General Public License
	18	* along with this program; if not, write to the Free Software
	19	* Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
	20	*
	21	* export.c
	22	*/
	23
	24	/*
	25	* This file implements code to make Squashfs filesystems exportable (NFS etc.)
	26	*
	27	* The export code uses an inode lookup table to map inode numbers passed in
	28	* filehandles to an inode location on disk. This table is stored compressed
	29	* into metadata blocks. A second index table is used to locate these. This
	30	* second index table for speed of access (and because it is small) is read at
	31	* mount time and cached in memory.
	32	*
	33	* The inode lookup table is used only by the export code, inode disk
	34	* locations are directly encoded in directories, enabling direct access
	35	* without an intermediate lookup for all operations except the export ops.
	36	*/
	37
	38	#include <linux/fs.h>
	39	#include <linux/vfs.h>
	40	#include <linux/dcache.h>
	41	#include <linux/exportfs.h>
23516dc7	42	#include <linux/slab.h>
12260140 PL	43
	44	#include "squashfs_fs.h"
	45	#include "squashfs_fs_sb.h"
	46	#include "squashfs_fs_i.h"
	47	#include "squashfs.h"
	48
	49	/*
	50	* Look-up inode number (ino) in table, returning the inode location.
	51	*/
	52	static long long squashfs_inode_lookup(struct super_block *sb, int ino_num)
	53	{
	54	struct squashfs_sb_info *msblk = sb->s_fs_info;
	55	int blk = SQUASHFS_LOOKUP_BLOCK(ino_num - 1);
	56	int offset = SQUASHFS_LOOKUP_BLOCK_OFFSET(ino_num - 1);
	57	u64 start = le64_to_cpu(msblk->inode_lookup_table[blk]);
	58	__le64 ino;
	59	int err;
	60
	61	TRACE("Entered squashfs_inode_lookup, inode_number = %d\n", ino_num);
	62
	63	err = squashfs_read_metadata(sb, &ino, &start, &offset, sizeof(ino));
	64	if (err < 0)
	65	return err;
	66
	67	TRACE("squashfs_inode_lookup, inode = 0x%llx\n",
	68	(u64) le64_to_cpu(ino));
	69
	70	return le64_to_cpu(ino);
	71	}
	72
	73
	74	static struct dentry squashfs_export_iget(struct super_block sb,
	75	unsigned int ino_num)
	76	{
	77	long long ino;
	78	struct dentry *dentry = ERR_PTR(-ENOENT);
	79
	80	TRACE("Entered squashfs_export_iget\n");
	81
	82	ino = squashfs_inode_lookup(sb, ino_num);
	83	if (ino >= 0)
	84	dentry = d_obtain_alias(squashfs_iget(sb, ino, ino_num));
	85
	86	return dentry;
	87	}
	88
	89
	90	static struct dentry squashfs_fh_to_dentry(struct super_block sb,
	91	struct fid *fid, int fh_len, int fh_type)
	92	{
	93	if ((fh_type != FILEID_INO32_GEN && fh_type != FILEID_INO32_GEN_PARENT)
	94	\|\| fh_len < 2)
	95	return NULL;
	96
	97	return squashfs_export_iget(sb, fid->i32.ino);
	98	}
	99
	100
	101	static struct dentry squashfs_fh_to_parent(struct super_block sb,
	102	struct fid *fid, int fh_len, int fh_type)
	103	{
	104	if (fh_type != FILEID_INO32_GEN_PARENT \|\| fh_len < 4)
	105	return NULL;
	106
107	return squashfs_export_iget(sb, fid->i32.parent_ino);
108	}
109
110
111	static struct dentry squashfs_get_parent(struct dentry child)
112	{
113	struct inode *inode = child->d_inode;
114	unsigned int parent_ino = squashfs_i(inode)->parent;
115
116	return squashfs_export_iget(inode->i_sb, parent_ino);
117	}
118
119
120	/*
121	* Read uncompressed inode lookup table indexes off disk into memory
122	*/
123	__le64 squashfs_read_inode_lookup_table(struct super_block sb,
124	u64 lookup_table_start, unsigned int inodes)
125	{
126	unsigned int length = SQUASHFS_LOOKUP_BLOCK_BYTES(inodes);
127	__le64 *inode_lookup_table;
128	int err;
129
130	TRACE("In read_inode_lookup_table, length %d\n", length);
131
132	/* Allocate inode lookup table indexes */
133	inode_lookup_table = kmalloc(length, GFP_KERNEL);
134	if (inode_lookup_table == NULL) {
135	ERROR("Failed to allocate inode lookup table\n");
136	return ERR_PTR(-ENOMEM);
137	}
138
139	err = squashfs_read_table(sb, inode_lookup_table, lookup_table_start,
140	length);
141	if (err < 0) {
142	ERROR("unable to read inode lookup table\n");
143	kfree(inode_lookup_table);
144	return ERR_PTR(err);
145	}
146
147	return inode_lookup_table;
148	}
149
150
151	const struct export_operations squashfs_export_ops = {
152	.fh_to_dentry = squashfs_fh_to_dentry,
153	.fh_to_parent = squashfs_fh_to_parent,
154	.get_parent = squashfs_get_parent
155	};