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      1 /* $NetBSD: dirhash.h,v 1.7 2025/10/31 10:35:52 reinoud Exp $ */
      2 
      3 /*
      4  * Copyright (c) 2008 Reinoud Zandijk
      5  * All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  *
     16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
     17  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     18  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     19  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
     20  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
     21  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     22  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     23  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     24  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     25  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     26  */
     27 
     28 #ifndef	_SYS_DIRHASH_H_
     29 #define	_SYS_DIRHASH_H_
     30 
     31 #include <sys/queue.h>
     32 #include <sys/dirent.h>
     33 
     34 #define	DIRHASH_HASHBITS	5
     35 #define	DIRHASH_HASHSIZE	(1 << DIRHASH_HASHBITS)
     36 #define	DIRHASH_HASHMASK	(DIRHASH_HASHSIZE - 1)
     37 
     38 /* dirent's d_namlen is to avoid useless costly fid->dirent translations */
     39 struct dirhash_entry {
     40 	uint32_t		 hashvalue;
     41 	uint64_t		 offset;
     42 	uint32_t		 d_namlen;
     43 	uint32_t		 entry_size;
     44 	LIST_ENTRY(dirhash_entry) next;
     45 };
     46 
     47 struct dirhash {
     48 	uint32_t		 flags;
     49 	uint32_t		 size;			/* in bytes */
     50 	uint32_t		 refcnt;
     51 	uint32_t		 num_files;
     52 	LIST_HEAD(, dirhash_entry) entries[DIRHASH_HASHSIZE];
     53 	LIST_HEAD(, dirhash_entry) free_entries;
     54 	TAILQ_ENTRY(dirhash) next;
     55 };
     56 
     57 #define	DIRH_PURGED		0x0001	/* dirhash has been purged */
     58 #define	DIRH_COMPLETE		0x0002	/* dirhash is complete */
     59 #define	DIRH_BROKEN		0x0004	/* dirhash is broken on readin */
     60 #define DIRH_COMPACTABLE	0x0008	/* free space can be compacted */
     61 #define	DIRH_FLAGBITS	"\10\1PURGED\2COMPLETE\3BROKEN\4COMPACTABLE"
     62 
     63 void	dirhash_init(void);
     64 /* void	dirhash_finish(void); */
     65 
     66 void	dirhash_purge(struct dirhash **);
     67 void	dirhash_purge_entries(struct dirhash *);
     68 void	dirhash_get(struct dirhash **);
     69 void	dirhash_put(struct dirhash *);
     70 void	dirhash_enter(struct dirhash *, struct dirent *, uint64_t,
     71 	    uint32_t, int);
     72 void	dirhash_enter_freed(struct dirhash *, uint64_t, uint32_t);
     73 void	dirhash_remove(struct dirhash *, struct dirent *dirent,
     74 	    uint64_t, uint32_t);
     75 int	dirhash_lookup(struct dirhash *, const char *, int,
     76 	    struct dirhash_entry **);
     77 int	dirhash_lookup_freed(struct dirhash *, uint32_t,
     78 	    struct dirhash_entry **);
     79 bool	dirhash_dir_isempty(struct dirhash *dirh);
     80 
     81 #endif /* _SYS_DIRHASH_H_ */
     82