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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 */