release/src-rt-6.x.4708/linux/linux-2.6.36/fs/freevxfs/vxfs_dir.h

   1 /*
   2  * Copyright (c) 2000-2001 Christoph Hellwig.
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions, and the following disclaimer,
  10  *    without modification.
  11  * 2. The name of the author may not be used to endorse or promote products
  12  *    derived from this software without specific prior written permission.
  13  *
  14  * Alternatively, this software may be distributed under the terms of the
  15  * GNU General Public License ("GPL").
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
  21  * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  *
  29  */
  30 #ifndef _VXFS_DIR_H_
  31 #define _VXFS_DIR_H_
  32
  33 /*
  34  * Veritas filesystem driver - directory structure.
  35  *
  36  * This file contains the definition of the vxfs directory format.
  37  */
  38
  39
  40 /*
  41  * VxFS directory block header.
  42  *
  43  * This entry is the head of every filesystem block in a directory.
  44  * It is used for free space management and additionally includes
  45  * a hash for speeding up directory search (lookup).
  46  *
  47  * The hash may be empty and in fact we do not use it all in the
  48  * Linux driver for now.
  49  */
  50 struct vxfs_dirblk {
  51         u_int16_t       d_free;         /* free space in dirblock */
  52         u_int16_t       d_nhash;        /* no of hash chains */
  53         u_int16_t       d_hash[1];      /* hash chain */
  54 };
  55
  56 /*
  57  * VXFS_NAMELEN is the maximum length of the d_name field
  58  *      of an VxFS directory entry.
  59  */
  60 #define VXFS_NAMELEN    256
  61
  62 /*
  63  * VxFS directory entry.
  64  */
  65 struct vxfs_direct {
  66         vx_ino_t        d_ino;                  /* inode number */
  67         u_int16_t       d_reclen;               /* record length */
  68         u_int16_t       d_namelen;              /* d_name length */
  69         u_int16_t       d_hashnext;             /* next hash entry */
  70         char            d_name[VXFS_NAMELEN];   /* name */
  71 };
  72
  73 /*
  74  * VXFS_DIRPAD defines the directory entry boundaries, is _must_ be
  75  *      a multiple of four.
  76  * VXFS_NAMEMIN is the length of a directory entry with a NULL d_name.
  77  * VXFS_DIRROUND is an internal macros that rounds a length to a value
  78  *      usable for directory sizes.
  79  * VXFS_DIRLEN calculates the directory entry size for an entry with
  80  *      a d_name with size len.
  81  */
  82 #define VXFS_DIRPAD             4
  83 #define VXFS_NAMEMIN            offsetof(struct vxfs_direct, d_name)
  84 #define VXFS_DIRROUND(len)      ((VXFS_DIRPAD + (len) - 1) & ~(VXFS_DIRPAD -1))
  85 #define VXFS_DIRLEN(len)        (VXFS_DIRROUND(VXFS_NAMEMIN + (len)))
  86
  87 /*
  88  * VXFS_DIRBLKOV is the overhead of a specific dirblock.
  89  */
  90 #define VXFS_DIRBLKOV(dbp)      ((sizeof(short) * dbp->d_nhash) + 4)
  91
  92 #endif /* _VXFS_DIR_H_ */