xref: /openbmc/linux/fs/efs/namei.c (revision b2441318)
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 
efs_find_entry(struct inode * inode,const char * name,int len)16 static 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 
efs_lookup(struct inode * dir,struct dentry * dentry,unsigned int flags)65 struct 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 
efs_nfs_get_inode(struct super_block * sb,u64 ino,u32 generation)77 static 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 
efs_fh_to_dentry(struct super_block * sb,struct fid * fid,int fh_len,int fh_type)96 struct 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 
efs_fh_to_parent(struct super_block * sb,struct fid * fid,int fh_len,int fh_type)103 struct 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 
efs_get_parent(struct dentry * child)110 struct 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