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jfs_superblock.h

/*
 *   Copyright (c) International Business Machines  Corp., 2000
 *
 *   This program is free software;  you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation; either version 2 of the License, or 
 *   (at your option) any later version.
 * 
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY;  without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
 *   the GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program;  if not, write to the Free Software 
 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 *
 */
#ifndef     _H_JFS_SUPERBLOCK
#define _H_JFS_SUPERBLOCK
/*
 *    jfs_superblock.h
 */

/*
 * make the magic number something a human could read
 */
#define JFS_MAGIC       "JFS1"      /* Magic word: Version 1 */

#define JFS_VERSION     1     /* Version number: Version 1 */

#define LV_NAME_SIZE    11    /* MUST BE 11 for OS/2 boot sector */

/* 
 *    aggregate superblock 
 *
 * The name superblock is too close to super_block, so the name has been
 * changed to jfs_superblock.  The utilities are still using the old name.
 */
#ifdef _JFS_UTILITY
struct superblock
#else
struct jfs_superblock
#endif
{
      char s_magic[4];  /* 4: magic number */
      u32 s_version;          /* 4: version number */

      s64 s_size;       /* 8: aggregate size in hardware/LVM blocks;
                         * VFS: number of blocks
                         */
      s32 s_bsize;            /* 4: aggregate block size in bytes; 
                         * VFS: fragment size
                         */
      s16 s_l2bsize;          /* 2: log2 of s_bsize */
      s16 s_l2bfactor;  /* 2: log2(s_bsize/hardware block size) */
      s32 s_pbsize;           /* 4: hardware/LVM block size in bytes */
      s16 s_l2pbsize;         /* 2: log2 of s_pbsize */
      s16 pad;          /* 2: padding necessary for alignment */

      u32 s_agsize;           /* 4: allocation group size in aggr. blocks */

      u32 s_flag;       /* 4: aggregate attributes:
                         *    see jfs_filsys.h
                         */
      u32 s_state;            /* 4: mount/unmount/recovery state: 
                         *    see jfs_filsys.h
                         */
      s32 s_compress;         /* 4: > 0 if data compression */

      pxd_t s_ait2;           /* 8: first extent of secondary
                         *    aggregate inode table
                         */

      pxd_t s_aim2;           /* 8: first extent of secondary
                         *    aggregate inode map
                         */
      u32 s_logdev;           /* 4: device address of log */
      s32 s_logserial;  /* 4: log serial number at aggregate mount */
      pxd_t s_logpxd;         /* 8: inline log extent */

      pxd_t s_fsckpxd;  /* 8: inline fsck work space extent */

      struct timestruc_t s_time;    /* 8: time last updated */

      s32 s_fsckloglen; /* 4: Number of filesystem blocks reserved for
                         *    the fsck service log.  
                         *    N.B. These blocks are divided among the
                         *         versions kept.  This is not a per
                         *         version size.
                         *    N.B. These blocks are included in the 
                         *         length field of s_fsckpxd.
                         */
      s8 s_fscklog;           /* 1: which fsck service log is most recent
                         *    0 => no service log data yet
                         *    1 => the first one
                         *    2 => the 2nd one
                         */
      char s_fpack[11]; /* 11: file system volume name 
                         *     N.B. This must be 11 bytes to
                         *          conform with the OS/2 BootSector
                         *          requirements
                         */

      /* extendfs() parameter under s_state & FM_EXTENDFS */
      s64 s_xsize;            /* 8: extendfs s_size */
      pxd_t s_xfsckpxd; /* 8: extendfs fsckpxd */
      pxd_t s_xlogpxd;  /* 8: extendfs logpxd */
      /* - 128 byte boundary - */

      /*
       *      DFS VFS support (preliminary) 
       */
      char s_attach;          /* 1: VFS: flag: set when aggregate is attached
                         */
      u8 rsrvd4[7];           /* 7: reserved - set to 0 */

      u64 totalUsable;  /* 8: VFS: total of 1K blocks which are
                         * available to "normal" (non-root) users.
                         */
      u64 minFree;            /* 8: VFS: # of 1K blocks held in reserve for 
                         * exclusive use of root.  This value can be 0,
                         * and if it is then totalUsable will be equal 
                         * to # of blocks in aggregate.  I believe this
                         * means that minFree + totalUsable = # blocks.
                         * In that case, we don't need to store both 
                         * totalUsable and minFree since we can compute
                         * one from the other.  I would guess minFree 
                         * would be the one we should store, and 
                         * totalUsable would be the one we should 
                         * compute.  (Just a guess...)
                         */

      u64 realFree;           /* 8: VFS: # of free 1K blocks can be used by 
                         * "normal" users.  It may be this is something
                         * we should compute when asked for instead of 
                         * storing in the superblock.  I don't know how
                         * often this information is needed.
                         */
      /*
       *      graffiti area
       */
};

#endif /*_H_JFS_SUPERBLOCK */

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