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}
121