FreeBSD/Linux Kernel Cross Reference
sys/sys/dirhash.h

     /* $NetBSD: dirhash.h,v 1.6 2013/07/07 19:31:26 reinoud Exp $ */
     
     /*
      * Copyright (c) 2008 Reinoud Zandijk
      * All rights reserved.
      * 
      * Redistribution and use in source and binary forms, with or without
      * modification, are permitted provided that the following conditions
      * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     * 
     * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
     * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
     * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
     * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     */
    
    #ifndef _SYS_DIRHASH_H_
    #define _SYS_DIRHASH_H_
    
    #include <sys/queue.h>
    #include <sys/dirent.h>
    
    #ifndef DIRHASH_SIZE
    #define DIRHASH_SIZE    (1024*1024)
    #endif
    
    #define DIRHASH_HASHBITS        5
    #define DIRHASH_HASHSIZE        (1 << DIRHASH_HASHBITS)
    #define DIRHASH_HASHMASK        (DIRHASH_HASHSIZE - 1)
    
    /* dirent's d_namlen is to avoid useless costly fid->dirent translations */
    struct dirhash_entry {
            uint32_t                 hashvalue;
            uint64_t                 offset;
            uint32_t                 d_namlen;
            uint32_t                 entry_size;
            LIST_ENTRY(dirhash_entry) next;
    };
    
    struct dirhash {
            uint32_t                 flags;
            uint32_t                 size;                  /* in bytes */
            uint32_t                 refcnt;
            uint32_t                 num_files;
            LIST_HEAD(, dirhash_entry) entries[DIRHASH_HASHSIZE];
            LIST_HEAD(, dirhash_entry) free_entries;
            TAILQ_ENTRY(dirhash) next;
    };
    
    #define DIRH_PURGED             0x0001  /* dirhash has been purged */
    #define DIRH_COMPLETE           0x0002  /* dirhash is complete */
    #define DIRH_BROKEN             0x0004  /* dirhash is broken on readin */
    #define DIRH_COMPACTABLE        0x0008  /* free space can be compacted */
    #define DIRH_FLAGBITS   "\1\1PURGED\2COMPLETE\3BROKEN\4COMPACTABLE"
    
    void    dirhash_init(void);
    /* void dirhash_finish(void); */
    
    void    dirhash_purge(struct dirhash **);
    void    dirhash_purge_entries(struct dirhash *);
    void    dirhash_get(struct dirhash **);
    void    dirhash_put(struct dirhash *);
    void    dirhash_enter(struct dirhash *, struct dirent *, uint64_t,
                uint32_t, int);
    void    dirhash_enter_freed(struct dirhash *, uint64_t, uint32_t);
    void    dirhash_remove(struct dirhash *, struct dirent *dirent,
                uint64_t, uint32_t);
    int     dirhash_lookup(struct dirhash *, const char *, int,
                struct dirhash_entry **);
    int     dirhash_lookup_freed(struct dirhash *, uint32_t,
                struct dirhash_entry **);
    bool    dirhash_dir_isempty(struct dirhash *dirh);
    
    #endif /* _SYS_DIRHASH_H_ */

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