sys/fs/efs/efs_extent.h

   1 /*      $NetBSD: efs_extent.h,v 1.2 2007/06/30 15:56:16 rumble Exp $    */
   2
   3 /*
   4  * Copyright (c) 2006 Stephen M. Rumble <rumble@ephemeral.org>
   5  *
   6  * Permission to use, copy, modify, and distribute this software for any
   7  * purpose with or without fee is hereby granted, provided that the above
   8  * copyright notice and this permission notice appear in all copies.
   9  *
  10  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  11  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  12  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  13  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  14  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  15  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  16  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  17  */
  18
  19 /*
  20  * EFS extent descriptor format and sundry.
  21  *
  22  * See IRIX inode(4)
  23  */
  24
  25 #ifndef _FS_EFS_EFS_EXTENT_H_
  26 #define _FS_EFS_EFS_EXTENT_H_
  27
  28 /*
  29  * EFS on-disk extent descriptor (8 bytes)
  30  *
  31  * SGI smushed this structure's members into bit fields, but we have to
  32  * be a little more portable. Therefore we use the efs_extent (see below)
  33  * type for in-core manipulation and convert immediately to and from disk.
  34  */
  35 struct efs_dextent {
  36         union {
  37                 uint64_t ex_magic:8,    /* magic number (always 0) */
  38                          ex_bn:24,      /* bb number in filesystem */
  39                          ex_length:8,   /* length of extent (in bb) */
  40                          ex_offset:24;  /* logical file offset (in bb) */
  41                 uint8_t  bytes[8];
  42                 uint32_t words[2];
  43         } ex_muddle;
  44 } __packed;
  45 #define ex_bytes ex_muddle.bytes
  46 #define ex_words ex_muddle.words
  47
  48 /*
  49  * In-core, unsquished representation of an extent.
  50  */
  51 struct efs_extent {
  52         uint8_t  ex_magic;
  53         uint32_t ex_bn;                 /* NB: only 24 bits on disk */
  54         uint8_t  ex_length;
  55         uint32_t ex_offset;             /* NB: only 24 bits on disk */
  56 };
  57
  58 #define EFS_EXTENT_MAGIC        0
  59 #define EFS_EXTENT_BN_MASK      0x00ffffff
  60 #define EFS_EXTENT_OFFSET_MASK  0x00ffffff
  61
  62 #define EFS_EXTENTS_PER_BB      (EFS_BB_SIZE / sizeof(struct efs_dextent))
  63
  64 #endif /* !_FS_EFS_EFS_EXTENT_H_ */