cregit-Linux how code gets into the kernel

Release 4.17 fs/squashfs/export.c

Directory: fs/squashfs
/*
 * 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); }

Contributors

PersonTokensPropCommitsCommitProp
Phillip Lougher119100.00%1100.00%
Total119100.00%1100.00%


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; }

Contributors

PersonTokensPropCommitsCommitProp
Phillip Lougher69100.00%1100.00%
Total69100.00%1100.00%


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); }

Contributors

PersonTokensPropCommitsCommitProp
Phillip Lougher55100.00%1100.00%
Total55100.00%1100.00%


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); }

Contributors

PersonTokensPropCommitsCommitProp
Phillip Lougher49100.00%1100.00%
Total49100.00%1100.00%


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); }

Contributors

PersonTokensPropCommitsCommitProp
Phillip Lougher4193.18%150.00%
David Howells36.82%150.00%
Total44100.00%2100.00%

/* * 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; }

Contributors

PersonTokensPropCommitsCommitProp
Phillip Lougher119100.00%3100.00%
Total119100.00%3100.00%

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 };

Overall Contributors

PersonTokensPropCommitsCommitProp
Phillip Lougher50298.82%466.67%
David Howells30.59%116.67%
Pekka J Enberg30.59%116.67%
Total508100.00%6100.00%
Directory: fs/squashfs
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