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dcache.h
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2002-04-26
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/* $Id: dcache.h,v 1.2 2002/04/26 23:09:04 smilcke Exp $ */
#ifndef __LINUX_DCACHE_H
#define __LINUX_DCACHE_H
#ifdef __KERNEL__
/*
* linux/include/linux/dcache.h
*
* Dirent cache data structures
*
* (C) Copyright 1997 Thomas Schoebel-Theuer,
* with heavy changes by Linus Torvalds
*/
#define IS_ROOT(x) ((x) == (x)->d_parent)
/*
* "quick string" -- eases parameter passing, but more importantly
* saves "metadata" about the string (ie length and the hash).
*/
struct qstr {
const unsigned char * name;
unsigned int len;
unsigned int hash;
};
/* Name hashing routines. Initial hash value */
#define init_name_hash() 0
/* partial hash update function. Assume roughly 4 bits per character */
static __inline__ unsigned long partial_name_hash(unsigned long c, unsigned long prevhash)
{
prevhash = (prevhash << 4) | (prevhash >> (8*sizeof(unsigned long)-4));
return prevhash ^ c;
}
/* Finally: cut down the number of bits to a int value (and try to avoid losing bits) */
static __inline__ unsigned long end_name_hash(unsigned long hash)
{
// if (sizeof(hash) > sizeof(unsigned int))
// hash += hash >> 4*sizeof(hash);
return (unsigned int) hash;
}
/* Compute the hash for a name string. */
static __inline__ unsigned int full_name_hash(const unsigned char * name, unsigned int len)
{
unsigned long hash = init_name_hash();
while (len--)
hash = partial_name_hash(*name++, hash);
return end_name_hash(hash);
}
#define DNAME_INLINE_LEN 16
struct dentry {
#ifdef TARGET_OS2
struct inode * d_inode; /* Where the name belongs to - NULL is negative */
#else
int d_count;
unsigned int d_flags;
struct inode * d_inode; /* Where the name belongs to - NULL is negative */
struct dentry * d_parent; /* parent directory */
struct dentry * d_mounts; /* mount information */
struct dentry * d_covers;
struct list_head d_hash; /* lookup hash list */
struct list_head d_lru; /* d_count = 0 LRU list */
struct list_head d_child; /* child of parent list */
struct list_head d_subdirs; /* our children */
struct list_head d_alias; /* inode alias list */
struct qstr d_name;
unsigned long d_time; /* used by d_revalidate */
struct dentry_operations *d_op;
struct super_block * d_sb; /* The root of the dentry tree */
unsigned long d_reftime; /* last time referenced */
void * d_fsdata; /* fs-specific data */
unsigned char d_iname[DNAME_INLINE_LEN]; /* small names */
#endif
};
struct dentry_operations {
int (*d_revalidate)(struct dentry *, int);
int (*d_hash) (struct dentry *, struct qstr *);
int (*d_compare) (struct dentry *, struct qstr *, struct qstr *);
void (*d_delete)(struct dentry *);
void (*d_release)(struct dentry *);
void (*d_iput)(struct dentry *, struct inode *);
};
/* the dentry parameter passed to d_hash and d_compare is the parent
* directory of the entries to be compared. It is used in case these
* functions need any directory specific information for determining
* equivalency classes. Using the dentry itself might not work, as it
* might be a negative dentry which has no information associated with
* it */
/* d_flags entries */
#define DCACHE_AUTOFS_PENDING 0x0001 /* autofs: "under construction" */
#define DCACHE_NFSFS_RENAMED 0x0002 /* this dentry has been "silly
* renamed" and has to be
* deleted on the last dput()
*/
/*
* These are the low-level FS interfaces to the dcache..
*/
extern void d_instantiate(struct dentry *, struct inode *);
extern void d_delete(struct dentry *);
/* allocate/de-allocate */
extern struct dentry * d_alloc(struct dentry *, const struct qstr *);
extern void shrink_dcache_sb(struct super_block *);
extern void shrink_dcache_parent(struct dentry *);
extern int d_invalidate(struct dentry *);
#define shrink_dcache() prune_dcache(0)
/* dcache memory management */
extern int shrink_dcache_memory(int, unsigned int);
extern void prune_dcache(int);
/* icache memory management (defined in linux/fs/inode.c) */
extern int shrink_icache_memory(int, int);
extern void prune_icache(int);
/* only used at mount-time */
extern struct dentry * d_alloc_root(struct inode *);
/* test whether root is busy without destroying dcache */
extern int is_root_busy(struct dentry *);
/*
* This adds the entry to the hash queues.
*/
extern void d_rehash(struct dentry *);
/*
* This adds the entry to the hash queues and initializes "d_inode".
* The entry was actually filled in earlier during "d_alloc()"
*/
static __inline__ void d_add(struct dentry * entry, struct inode * inode)
{
d_rehash(entry);
d_instantiate(entry, inode);
}
/* used for rename() and baskets */
extern void d_move(struct dentry *, struct dentry *);
/* appendix may either be NULL or be used for transname suffixes */
extern struct dentry * d_lookup(struct dentry *, struct qstr *);
/* validate "insecure" dentry pointer */
extern int d_validate(struct dentry *, struct dentry *, unsigned int, unsigned int);
/* write full pathname into buffer and return start of pathname */
extern char * d_path(struct dentry *, char *, int);
/* Allocation counts.. */
struct dentry * dget(struct dentry *dentry);
//{
// if (dentry)
// dentry->d_count++;
// return dentry;
//}
extern void dput(struct dentry *);
#endif /* __KERNEL__ */
#endif /* __LINUX_DCACHE_H */