xref: /openbmc/linux/fs/efs/namei.c (revision 6774def6)
1 /*
2  * namei.c
3  *
4  * Copyright (c) 1999 Al Smith
5  *
6  * Portions derived from work (c) 1995,1996 Christian Vogelgsang.
7  */
8 
9 #include <linux/buffer_head.h>
10 #include <linux/string.h>
11 #include <linux/exportfs.h>
12 #include "efs.h"
13 
14 
15 static efs_ino_t efs_find_entry(struct inode *inode, const char *name, int len)
16 {
17 	struct buffer_head *bh;
18 
19 	int			slot, namelen;
20 	char			*nameptr;
21 	struct efs_dir		*dirblock;
22 	struct efs_dentry	*dirslot;
23 	efs_ino_t		inodenum;
24 	efs_block_t		block;
25 
26 	if (inode->i_size & (EFS_DIRBSIZE-1))
27 		pr_warn("%s(): directory size not a multiple of EFS_DIRBSIZE\n",
28 			__func__);
29 
30 	for(block = 0; block < inode->i_blocks; block++) {
31 
32 		bh = sb_bread(inode->i_sb, efs_bmap(inode, block));
33 		if (!bh) {
34 			pr_err("%s(): failed to read dir block %d\n",
35 			       __func__, block);
36 			return 0;
37 		}
38 
39 		dirblock = (struct efs_dir *) bh->b_data;
40 
41 		if (be16_to_cpu(dirblock->magic) != EFS_DIRBLK_MAGIC) {
42 			pr_err("%s(): invalid directory block\n", __func__);
43 			brelse(bh);
44 			return 0;
45 		}
46 
47 		for (slot = 0; slot < dirblock->slots; slot++) {
48 			dirslot  = (struct efs_dentry *) (((char *) bh->b_data) + EFS_SLOTAT(dirblock, slot));
49 
50 			namelen  = dirslot->namelen;
51 			nameptr  = dirslot->name;
52 
53 			if ((namelen == len) && (!memcmp(name, nameptr, len))) {
54 				inodenum = be32_to_cpu(dirslot->inode);
55 				brelse(bh);
56 				return inodenum;
57 			}
58 		}
59 		brelse(bh);
60 	}
61 	return 0;
62 }
63 
64 struct dentry *efs_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
65 {
66 	efs_ino_t inodenum;
67 	struct inode *inode = NULL;
68 
69 	inodenum = efs_find_entry(dir, dentry->d_name.name, dentry->d_name.len);
70 	if (inodenum)
71 		inode = efs_iget(dir->i_sb, inodenum);
72 
73 	return d_splice_alias(inode, dentry);
74 }
75 
76 static struct inode *efs_nfs_get_inode(struct super_block *sb, u64 ino,
77 		u32 generation)
78 {
79 	struct inode *inode;
80 
81 	if (ino == 0)
82 		return ERR_PTR(-ESTALE);
83 	inode = efs_iget(sb, ino);
84 	if (IS_ERR(inode))
85 		return ERR_CAST(inode);
86 
87 	if (generation && inode->i_generation != generation) {
88 		iput(inode);
89 		return ERR_PTR(-ESTALE);
90 	}
91 
92 	return inode;
93 }
94 
95 struct dentry *efs_fh_to_dentry(struct super_block *sb, struct fid *fid,
96 		int fh_len, int fh_type)
97 {
98 	return generic_fh_to_dentry(sb, fid, fh_len, fh_type,
99 				    efs_nfs_get_inode);
100 }
101 
102 struct dentry *efs_fh_to_parent(struct super_block *sb, struct fid *fid,
103 		int fh_len, int fh_type)
104 {
105 	return generic_fh_to_parent(sb, fid, fh_len, fh_type,
106 				    efs_nfs_get_inode);
107 }
108 
109 struct dentry *efs_get_parent(struct dentry *child)
110 {
111 	struct dentry *parent = ERR_PTR(-ENOENT);
112 	efs_ino_t ino;
113 
114 	ino = efs_find_entry(child->d_inode, "..", 2);
115 	if (ino)
116 		parent = d_obtain_alias(efs_iget(child->d_inode->i_sb, ino));
117 
118 	return parent;
119 }
120