jfs_superblock.h

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/*
 *   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 3 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, see <http://www.gnu.org/licenses/>.
 *
 */
#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 file system 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 */