cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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namei.c (2717B)

      1// SPDX-License-Identifier: GPL-2.0
      2/*
      3 * namei.c
      4 *
      5 * Copyright (c) 1999 Al Smith
      6 *
      7 * Portions derived from work (c) 1995,1996 Christian Vogelgsang.
      8 */
      9
     10#include <linux/buffer_head.h>
     11#include <linux/string.h>
     12#include <linux/exportfs.h>
     13#include "efs.h"
     14
     15
     16static efs_ino_t efs_find_entry(struct inode *inode, const char *name, int len)
     17{
     18	struct buffer_head *bh;
     19
     20	int			slot, namelen;
     21	char			*nameptr;
     22	struct efs_dir		*dirblock;
     23	struct efs_dentry	*dirslot;
     24	efs_ino_t		inodenum;
     25	efs_block_t		block;
     26 
     27	if (inode->i_size & (EFS_DIRBSIZE-1))
     28		pr_warn("%s(): directory size not a multiple of EFS_DIRBSIZE\n",
     29			__func__);
     30
     31	for(block = 0; block < inode->i_blocks; block++) {
     32
     33		bh = sb_bread(inode->i_sb, efs_bmap(inode, block));
     34		if (!bh) {
     35			pr_err("%s(): failed to read dir block %d\n",
     36			       __func__, block);
     37			return 0;
     38		}
     39    
     40		dirblock = (struct efs_dir *) bh->b_data;
     41
     42		if (be16_to_cpu(dirblock->magic) != EFS_DIRBLK_MAGIC) {
     43			pr_err("%s(): invalid directory block\n", __func__);
     44			brelse(bh);
     45			return 0;
     46		}
     47
     48		for (slot = 0; slot < dirblock->slots; slot++) {
     49			dirslot  = (struct efs_dentry *) (((char *) bh->b_data) + EFS_SLOTAT(dirblock, slot));
     50
     51			namelen  = dirslot->namelen;
     52			nameptr  = dirslot->name;
     53
     54			if ((namelen == len) && (!memcmp(name, nameptr, len))) {
     55				inodenum = be32_to_cpu(dirslot->inode);
     56				brelse(bh);
     57				return inodenum;
     58			}
     59		}
     60		brelse(bh);
     61	}
     62	return 0;
     63}
     64
     65struct dentry *efs_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
     66{
     67	efs_ino_t inodenum;
     68	struct inode *inode = NULL;
     69
     70	inodenum = efs_find_entry(dir, dentry->d_name.name, dentry->d_name.len);
     71	if (inodenum)
     72		inode = efs_iget(dir->i_sb, inodenum);
     73
     74	return d_splice_alias(inode, dentry);
     75}
     76
     77static struct inode *efs_nfs_get_inode(struct super_block *sb, u64 ino,
     78		u32 generation)
     79{
     80	struct inode *inode;
     81
     82	if (ino == 0)
     83		return ERR_PTR(-ESTALE);
     84	inode = efs_iget(sb, ino);
     85	if (IS_ERR(inode))
     86		return ERR_CAST(inode);
     87
     88	if (generation && inode->i_generation != generation) {
     89		iput(inode);
     90		return ERR_PTR(-ESTALE);
     91	}
     92
     93	return inode;
     94}
     95
     96struct dentry *efs_fh_to_dentry(struct super_block *sb, struct fid *fid,
     97		int fh_len, int fh_type)
     98{
     99	return generic_fh_to_dentry(sb, fid, fh_len, fh_type,
    100				    efs_nfs_get_inode);
    101}
    102
    103struct dentry *efs_fh_to_parent(struct super_block *sb, struct fid *fid,
    104		int fh_len, int fh_type)
    105{
    106	return generic_fh_to_parent(sb, fid, fh_len, fh_type,
    107				    efs_nfs_get_inode);
    108}
    109
    110struct dentry *efs_get_parent(struct dentry *child)
    111{
    112	struct dentry *parent = ERR_PTR(-ENOENT);
    113	efs_ino_t ino;
    114
    115	ino = efs_find_entry(d_inode(child), "..", 2);
    116	if (ino)
    117		parent = d_obtain_alias(efs_iget(child->d_sb, ino));
    118
    119	return parent;
    120}