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#ifndef __LINUX_DCACHE_H
#define __LINUX_DCACHE_H
#ifdef __KERNEL__
#include <asm/atomic.h>
#include <linux/mount.h>
/*
* 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;
};
struct dentry_stat_t {
int nr_dentry;
int nr_unused;
int age_limit; /* age in seconds */
int want_pages; /* pages requested by system */
int dummy[2];
};
extern struct dentry_stat_t dentry_stat;
/* Name hashing routines. Initial hash value */
/* Hash courtesy of the R5 hash in reiserfs modulo sign bits */
#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)
{
return (prevhash + (c << 4) + (c >> 4)) * 11;
}
/* 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)
{
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 {
atomic_t 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 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 */
int d_mounted;
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_vfs_flags;
void * d_fsdata; /* fs-specific data */
unsigned char d_iname[DNAME_INLINE_LEN]; /* small names */
};
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 *);
int (*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 */
/*
locking rules:
big lock dcache_lock may block
d_revalidate: no no yes
d_hash no no yes
d_compare: no yes no
d_delete: no yes no
d_release: no no yes
d_iput: no no yes
*/
/* 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()
*/
#define DCACHE_NFSD_DISCONNECTED 0x0004 /* This dentry is not currently connected to the
* dcache tree. Its parent will either be itself,
* or will have this flag as well.
* If this dentry points to a directory, then
* s_nfsd_free_path semaphore will be down
*/
#define DCACHE_REFERENCED 0x0008 /* Recently used, don't discard. */
extern spinlock_t dcache_lock;
/**
* d_drop - drop a dentry
* @dentry: dentry to drop
*
* d_drop() unhashes the entry from the parent
* dentry hashes, so that it won't be found through
* a VFS lookup any more. Note that this is different
* from deleting the dentry - d_delete will try to
* mark the dentry negative if possible, giving a
* successful _negative_ lookup, while d_drop will
* just make the cache lookup fail.
*
* d_drop() is used mainly for stuff that wants
* to invalidate a dentry for some reason (NFS
* timeouts or autofs deletes).
*/
static __inline__ void d_drop(struct dentry * dentry)
{
spin_lock(&dcache_lock);
list_del(&dentry->d_hash);
INIT_LIST_HEAD(&dentry->d_hash);
spin_unlock(&dcache_lock);
}
static __inline__ int dname_external(struct dentry *d)
{
return d->d_name.name != d->d_iname;
}
/*
* 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)
struct zone_struct;
/* 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);
/* quota cache memory management (defined in linux/fs/dquot.c) */
extern int shrink_dqcache_memory(int, unsigned int);
/* only used at mount-time */
extern struct dentry * d_alloc_root(struct inode *);
/* <clickety>-<click> the ramfs-type tree */
extern void d_genocide(struct dentry *);
extern struct dentry *d_find_alias(struct inode *);
extern void d_prune_aliases(struct inode *);
/* test whether we have any submounts in a subdir tree */
extern int have_submounts(struct dentry *);
/*
* This adds the entry to the hash queues.
*/
extern void d_rehash(struct dentry *);
/**
* d_add - add dentry to hash queues
* @entry: dentry to add
* @inode: The inode to attach to this dentry
*
* This adds the entry to the hash queues and initializes @inode.
* The entry was actually filled in earlier during d_alloc().
*/
static __inline__ void d_add(struct dentry * entry, struct inode * inode)
{
d_instantiate(entry, inode);
d_rehash(entry);
}
/* 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 *);
extern char * __d_path(struct dentry *, struct vfsmount *, struct dentry *,
struct vfsmount *, char *, int);
/* Allocation counts.. */
/**
* dget, dget_locked - get a reference to a dentry
* @dentry: dentry to get a reference to
*
* Given a dentry or %NULL pointer increment the reference count
* if appropriate and return the dentry. A dentry will not be
* destroyed when it has references. dget() should never be
* called for dentries with zero reference counter. For these cases
* (preferably none, functions in dcache.c are sufficient for normal
* needs and they take necessary precautions) you should hold dcache_lock
* and call dget_locked() instead of dget().
*/
static __inline__ struct dentry * dget(struct dentry *dentry)
{
if (dentry) {
if (!atomic_read(&dentry->d_count))
out_of_line_bug();
atomic_inc(&dentry->d_count);
}
return dentry;
}
extern struct dentry * dget_locked(struct dentry *);
/**
* d_unhashed - is dentry hashed
* @dentry: entry to check
*
* Returns true if the dentry passed is not currently hashed.
*/
static __inline__ int d_unhashed(struct dentry *dentry)
{
return list_empty(&dentry->d_hash);
}
extern void dput(struct dentry *);
static __inline__ int d_mountpoint(struct dentry *dentry)
{
return dentry->d_mounted;
}
extern struct vfsmount *lookup_mnt(struct vfsmount *, struct dentry *);
#endif /* __KERNEL__ */
#endif /* __LINUX_DCACHE_H */
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