source: GPL/include/linux/dcache.h@ 18

Last change on this file since 18 was 18, checked in by vladest, 20 years ago

initial import
File size: 5.3 KB
Line 
1/* $Id: dcache.h,v 1.1.1.1 2003/07/02 13:57:00 eleph Exp $ */
2
3#ifndef __LINUX_DCACHE_H
4#define __LINUX_DCACHE_H
5
6#ifdef __KERNEL__
7
8/*
9 * linux/include/linux/dcache.h
10 *
11 * Dirent cache data structures
12 *
13 * (C) Copyright 1997 Thomas Schoebel-Theuer,
14 * with heavy changes by Linus Torvalds
15 */
16
17#define IS_ROOT(x) ((x) == (x)->d_parent)
18
19/*
20 * "quick string" -- eases parameter passing, but more importantly
21 * saves "metadata" about the string (ie length and the hash).
22 */
23struct qstr {
24 const unsigned char * name;
25 unsigned int len;
26 unsigned int hash;
27};
28
29/* Name hashing routines. Initial hash value */
30#define init_name_hash() 0
31
32/* partial hash update function. Assume roughly 4 bits per character */
33static __inline__ unsigned long partial_name_hash(unsigned long c, unsigned long prevhash)
34{
35 prevhash = (prevhash << 4) | (prevhash >> (8*sizeof(unsigned long)-4));
36 return prevhash ^ c;
37}
38
39/* Finally: cut down the number of bits to a int value (and try to avoid losing bits) */
40static __inline__ unsigned long end_name_hash(unsigned long hash)
41{
42// if (sizeof(hash) > sizeof(unsigned int))
43// hash += hash >> 4*sizeof(hash);
44 return (unsigned int) hash;
45}
46
47/* Compute the hash for a name string. */
48static __inline__ unsigned int full_name_hash(const unsigned char * name, unsigned int len)
49{
50 unsigned long hash = init_name_hash();
51 while (len--)
52 hash = partial_name_hash(*name++, hash);
53 return end_name_hash(hash);
54}
55
56#define DNAME_INLINE_LEN 16
57
58struct dentry {
59#ifdef TARGET_OS2
60 struct inode * d_inode; /* Where the name belongs to - NULL is negative */
61#else
62 int d_count;
63 unsigned int d_flags;
64 struct inode * d_inode; /* Where the name belongs to - NULL is negative */
65 struct dentry * d_parent; /* parent directory */
66 struct dentry * d_mounts; /* mount information */
67 struct dentry * d_covers;
68 struct list_head d_hash; /* lookup hash list */
69 struct list_head d_lru; /* d_count = 0 LRU list */
70 struct list_head d_child; /* child of parent list */
71 struct list_head d_subdirs; /* our children */
72 struct list_head d_alias; /* inode alias list */
73 struct qstr d_name;
74 unsigned long d_time; /* used by d_revalidate */
75 struct dentry_operations *d_op;
76 struct super_block * d_sb; /* The root of the dentry tree */
77 unsigned long d_reftime; /* last time referenced */
78 void * d_fsdata; /* fs-specific data */
79 unsigned char d_iname[DNAME_INLINE_LEN]; /* small names */
80#endif
81};
82
83struct dentry_operations {
84 int (*d_revalidate)(struct dentry *, int);
85 int (*d_hash) (struct dentry *, struct qstr *);
86 int (*d_compare) (struct dentry *, struct qstr *, struct qstr *);
87 void (*d_delete)(struct dentry *);
88 void (*d_release)(struct dentry *);
89 void (*d_iput)(struct dentry *, struct inode *);
90};
91
92/* the dentry parameter passed to d_hash and d_compare is the parent
93 * directory of the entries to be compared. It is used in case these
94 * functions need any directory specific information for determining
95 * equivalency classes. Using the dentry itself might not work, as it
96 * might be a negative dentry which has no information associated with
97 * it */
98
99
100
101/* d_flags entries */
102#define DCACHE_AUTOFS_PENDING 0x0001 /* autofs: "under construction" */
103#define DCACHE_NFSFS_RENAMED 0x0002 /* this dentry has been "silly
104 * renamed" and has to be
105 * deleted on the last dput()
106 */
107
108
109/*
110 * These are the low-level FS interfaces to the dcache..
111 */
112extern void d_instantiate(struct dentry *, struct inode *);
113extern void d_delete(struct dentry *);
114
115/* allocate/de-allocate */
116extern struct dentry * d_alloc(struct dentry *, const struct qstr *);
117extern void shrink_dcache_sb(struct super_block *);
118extern void shrink_dcache_parent(struct dentry *);
119extern int d_invalidate(struct dentry *);
120
121#define shrink_dcache() prune_dcache(0)
122
123/* dcache memory management */
124extern int shrink_dcache_memory(int, unsigned int);
125extern void prune_dcache(int);
126
127/* icache memory management (defined in linux/fs/inode.c) */
128extern int shrink_icache_memory(int, int);
129extern void prune_icache(int);
130
131/* only used at mount-time */
132extern struct dentry * d_alloc_root(struct inode *);
133
134/* test whether root is busy without destroying dcache */
135extern int is_root_busy(struct dentry *);
136
137/*
138 * This adds the entry to the hash queues.
139 */
140extern void d_rehash(struct dentry *);
141/*
142 * This adds the entry to the hash queues and initializes "d_inode".
143 * The entry was actually filled in earlier during "d_alloc()"
144 */
145static __inline__ void d_add(struct dentry * entry, struct inode * inode)
146{
147 d_rehash(entry);
148 d_instantiate(entry, inode);
149}
150
151/* used for rename() and baskets */
152extern void d_move(struct dentry *, struct dentry *);
153
154/* appendix may either be NULL or be used for transname suffixes */
155extern struct dentry * d_lookup(struct dentry *, struct qstr *);
156
157/* validate "insecure" dentry pointer */
158extern int d_validate(struct dentry *, struct dentry *, unsigned int, unsigned int);
159
160/* write full pathname into buffer and return start of pathname */
161extern char * d_path(struct dentry *, char *, int);
162
163/* Allocation counts.. */
164struct dentry * dget(struct dentry *dentry);
165//{
166// if (dentry)
167// dentry->d_count++;
168// return dentry;
169//}
170
171extern void dput(struct dentry *);
172
173#endif /* __KERNEL__ */
174
175#endif /* __LINUX_DCACHE_H */
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