#ifndef __LINUX_DCACHE_H
#define __LINUX_DCACHE_H

#include <asm/atomic.h>
#include <linux/list.h>
#include <linux/rculist.h>
#include <linux/spinlock.h>
#include <linux/cache.h>
#include <linux/rcupdate.h>

struct nameidata;
struct path;
struct vfsmount;

/*
 * 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).
 *
 * hash comes first so it snuggles against d_parent in the
 * dentry.
 */
struct qstr {
        unsigned int hash;
        unsigned int len;
        const unsigned char *name;
};

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);
}

/*
 * Try to keep struct dentry aligned on 64 byte cachelines (this will
 * give reasonable cacheline footprint with larger lines without the
 * large memory footprint increase).
 */
#ifdef CONFIG_64BIT
#define DNAME_INLINE_LEN_MIN 32 /* 192 bytes */
#else
#define DNAME_INLINE_LEN_MIN 40 /* 128 bytes */
#endif

struct dentry {
        atomic_t d_count;
        unsigned int d_flags;           /* protected by d_lock */
        spinlock_t d_lock;              /* per dentry lock */
        int d_mounted;
        struct inode *d_inode;          /* Where the name belongs to - NULL is
                                         * negative */
        /*
         * The next three fields are touched by __d_lookup.  Place them here
         * so they all fit in a cache line.
         */
        struct hlist_node d_hash;       /* lookup hash list */
        struct dentry *d_parent;        /* parent directory */
        struct qstr d_name;

        struct list_head d_lru;         /* LRU list */
        /*
         * d_child and d_rcu can share memory
         */
        union {
                struct list_head d_child;       /* child of parent list */
                struct rcu_head d_rcu;
        } d_u;
        struct list_head d_subdirs;     /* our children */
        struct list_head d_alias;       /* inode alias list */
        unsigned long d_time;           /* used by d_revalidate */
        struct dentry_operations *d_op;
        struct super_block *d_sb;       /* The root of the dentry tree */
        void *d_fsdata;                 /* fs-specific data */

        unsigned char d_iname[DNAME_INLINE_LEN_MIN];    /* small names */
};

/*
 * dentry->d_lock spinlock nesting subclasses:
 *
 * 0: normal
 * 1: nested
 */
enum dentry_d_lock_class
{
        DENTRY_D_LOCK_NORMAL, /* implicitly used by plain spin_lock() APIs. */
        DENTRY_D_LOCK_NESTED
};

struct dentry_operations {
        int (*d_revalidate)(struct dentry *, struct nameidata *);
        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 *);
        char *(*d_dname)(struct dentry *, char *, int);
};

/* 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     d_lock   may block
d_revalidate:   no              no              no       yes
d_hash          no              no              no       yes
d_compare:      no              yes             yes      no
d_delete:       no              yes             no       no
d_release:      no              no              no       yes
d_iput:         no              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_DISCONNECTED 0x0004
     /* This dentry is possibly not currently connected to the dcache tree,
      * in which case its parent will either be itself, or will have this
      * flag as well.  nfsd will not use a dentry with this bit set, but will
      * first endeavour to clear the bit either by discovering that it is
      * connected, or by performing lookup operations.   Any filesystem which
      * supports nfsd_operations MUST have a lookup function which, if it finds
      * a directory inode with a DCACHE_DISCONNECTED dentry, will d_move
      * that dentry into place and return that dentry rather than the passed one,
      * typically using d_splice_alias.
      */

#define DCACHE_REFERENCED       0x0008  /* Recently used, don't discard. */
#define DCACHE_UNHASHED         0x0010  

#define DCACHE_INOTIFY_PARENT_WATCHED   0x0020 /* Parent inode is watched */

#define DCACHE_COOKIE           0x0040  /* For use by dcookie subsystem */

extern spinlock_t dcache_lock;
extern seqlock_t rename_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).
 *
 * __d_drop requires dentry->d_lock.
 */

static inline void __d_drop(struct dentry *dentry)
{
        if (!(dentry->d_flags & DCACHE_UNHASHED)) {
                dentry->d_flags |= DCACHE_UNHASHED;
                hlist_del_rcu(&dentry->d_hash);
        }
}

static inline void d_drop(struct dentry *dentry)
{
        spin_lock(&dcache_lock);
        spin_lock(&dentry->d_lock);
        __d_drop(dentry);
        spin_unlock(&dentry->d_lock);
        spin_unlock(&dcache_lock);
}

static inline int dname_external(struct dentry *dentry)
{
        return dentry->d_name.name != dentry->d_iname;
}

/*
 * These are the low-level FS interfaces to the dcache..
 */
extern void d_instantiate(struct dentry *, struct inode *);
extern struct dentry * d_instantiate_unique(struct dentry *, struct inode *);
extern struct dentry * d_materialise_unique(struct dentry *, struct inode *);
extern void d_delete(struct dentry *);

/* allocate/de-allocate */
extern struct dentry * d_alloc(struct dentry *, const struct qstr *);
extern struct dentry * d_splice_alias(struct inode *, struct dentry *);
extern struct dentry * d_add_ci(struct dentry *, struct inode *, struct qstr *);
extern struct dentry * d_obtain_alias(struct inode *);
extern void shrink_dcache_sb(struct super_block *);
extern void shrink_dcache_parent(struct dentry *);
extern void shrink_dcache_for_umount(struct super_block *);
extern int d_invalidate(struct dentry *);

/* 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);
}

/**
 * d_add_unique - add dentry to hash queues without aliasing
 * @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 struct dentry *d_add_unique(struct dentry *entry, struct inode *inode)
{
        struct dentry *res;

        res = d_instantiate_unique(entry, inode);
        d_rehash(res != NULL ? res : entry);
        return res;
}

/* used for rename() and baskets */
extern void d_move(struct dentry *, struct dentry *);
extern struct dentry *d_ancestor(struct dentry *, struct dentry *);

/* appendix may either be NULL or be used for transname suffixes */
extern struct dentry * d_lookup(struct dentry *, struct qstr *);
extern struct dentry * __d_lookup(struct dentry *, struct qstr *);
extern struct dentry * d_hash_and_lookup(struct dentry *, struct qstr *);

/* validate "insecure" dentry pointer */
extern int d_validate(struct dentry *, struct dentry *);

/*
 * helper function for dentry_operations.d_dname() members
 */
extern char *dynamic_dname(struct dentry *, char *, int, const char *, ...);

extern char *__d_path(const struct path *path, struct path *root, char *, int);
extern char *d_path(const struct path *, char *, int);
extern char *dentry_path(struct dentry *, 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) {
                BUG_ON(!atomic_read(&dentry->d_count));
                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 (dentry->d_flags & DCACHE_UNHASHED);
}

static inline struct dentry *dget_parent(struct dentry *dentry)
{
        struct dentry *ret;

        spin_lock(&dentry->d_lock);
        ret = dget(dentry->d_parent);
        spin_unlock(&dentry->d_lock);
        return ret;
}

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 *);
extern struct dentry *lookup_create(struct nameidata *nd, int is_dir);

extern int sysctl_vfs_cache_pressure;

#endif  /* __LINUX_DCACHE_H */