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#ifndef __LINUX_DCACHE_H
#define __LINUX_DCACHE_H

#ifdef __KERNEL__

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

struct nameidata;
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).
 */

struct qstr {
        const unsigned char * name;
        unsigned int len;
        unsigned int hash;
        char name_str[0];
};

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_MIN 16

struct dcookie_struct;
 
struct dentry {
        atomic_t d_count;
        unsigned long d_vfs_flags;      /* moved here to be on same cacheline */
        spinlock_t d_lock;              /* per dentry lock */
        struct inode  * d_inode;        /* Where the name belongs to - NULL is negative */
        struct list_head d_lru;         /* 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 */
        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 int d_flags;
        int d_mounted;
        void * d_fsdata;                /* fs-specific data */
        struct rcu_head d_rcu;
        struct dcookie_struct * d_cookie; /* cookie, if any */
        unsigned long d_move_count;     /* to indicated moved dentry while lockless lookup */
        struct qstr * d_qstr;           /* quick str ptr used in lockless lookup and concurrent d_move */
        struct dentry * d_parent;       /* parent directory */
        struct qstr d_name;
        struct hlist_node d_hash;       /* lookup hash list */ 
        struct hlist_head * d_bucket;   /* lookup hash bucket */
        unsigned char d_iname[DNAME_INLINE_LEN_MIN]; /* small names */
} ____cacheline_aligned;

#define DNAME_INLINE_LEN        (sizeof(struct dentry)-offsetof(struct dentry,d_iname))
 
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 *);
};

/* 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_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 

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)
{
        if (!(dentry->d_vfs_flags & DCACHE_UNHASHED)) {
                dentry->d_vfs_flags |= DCACHE_UNHASHED;
                hlist_del_rcu(&dentry->d_hash);
        }
}

static inline void d_drop(struct dentry *dentry)
{
        spin_lock(&dcache_lock);
        __d_drop(dentry);
        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 struct dentry * d_alloc_anon(struct inode *);
extern struct dentry * d_splice_alias(struct inode *, struct dentry *);
extern void shrink_dcache_sb(struct super_block *);
extern void shrink_dcache_parent(struct dentry *);
extern void shrink_dcache_anon(struct hlist_head *);
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);
}

/* 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 *);
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 *, 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))
                        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 (dentry->d_vfs_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);

#endif /* __KERNEL__ */

#endif  /* __LINUX_DCACHE_H */