sys/gnu/vfs/ext2fs/fs.h

   1 /*
   2  *  modified for EXT2FS support in Lites 1.1
   3  *
   4  *  Aug 1995, Godmar Back (gback@cs.utah.edu)
   5  *  University of Utah, Department of Computer Science
   6  */
   7 /*
   8  * Copyright (c) 1982, 1986, 1993
   9  *      The Regents of the University of California.  All rights reserved.
  10  *
  11  * Redistribution and use in source and binary forms, with or without
  12  * modification, are permitted provided that the following conditions
  13  * are met:
  14  * 1. Redistributions of source code must retain the above copyright
  15  *    notice, this list of conditions and the following disclaimer.
  16  * 2. Redistributions in binary form must reproduce the above copyright
  17  *    notice, this list of conditions and the following disclaimer in the
  18  *    documentation and/or other materials provided with the distribution.
  19  * 3. All advertising materials mentioning features or use of this software
  20  *    must display the following acknowledgement:
  21  *      This product includes software developed by the University of
  22  *      California, Berkeley and its contributors.
  23  * 4. Neither the name of the University nor the names of its contributors
  24  *    may be used to endorse or promote products derived from this software
  25  *    without specific prior written permission.
  26  *
  27  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  28  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  29  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  30  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  31  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  32  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  33  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  34  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  35  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  36  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  37  * SUCH DAMAGE.
  38  *
  39  *      @(#)fs.h        8.7 (Berkeley) 4/19/94
  40  * $FreeBSD: src/sys/gnu/ext2fs/fs.h,v 1.5.2.1 2000/11/11 13:12:45 bde Exp $
  41  */
  42
  43 /*
  44  * Each disk drive contains some number of file systems.
  45  * A file system consists of a number of cylinder groups.
  46  * Each cylinder group has inodes and data.
  47  *
  48  * A file system is described by its super-block, which in turn
  49  * describes the cylinder groups.  The super-block is critical
  50  * data and is replicated in each cylinder group to protect against
  51  * catastrophic loss.  This is done at `newfs' time and the critical
  52  * super-block data does not change, so the copies need not be
  53  * referenced further unless disaster strikes.
  54  *
  55  * The first boot and super blocks are given in absolute disk addresses.
  56  * The byte-offset forms are preferred, as they don't imply a sector size.
  57  */
  58 #define BBSIZE          1024
  59 #define SBSIZE          1024
  60 #define BBOFF           ((off_t)(0))
  61 #define SBOFF           ((off_t)(BBOFF + BBSIZE))
  62 #define BBLOCK          ((daddr_t)(0))
  63 #define SBLOCK          ((daddr_t)(BBLOCK + BBSIZE / DEV_BSIZE))
  64
  65 /*
  66  * The path name on which the file system is mounted is maintained
  67  * in fs_fsmnt. MAXMNTLEN defines the amount of space allocated in
  68  * the super block for this name.
  69  */
  70 #define MAXMNTLEN 512
  71
  72 /*
  73  * Macros for access to superblock array structures
  74  */
  75
  76 /*
  77  * Convert cylinder group to base address of its global summary info.
  78  */
  79 #define fs_cs(fs, cgindx)      (((struct ext2_group_desc *) \
  80         (fs->s_group_desc[cgindx / EXT2_DESC_PER_BLOCK(fs)]->b_data)) \
  81                 [cgindx % EXT2_DESC_PER_BLOCK(fs)])
  82
  83 /*
  84  * Turn file system block numbers into disk block addresses.
  85  * This maps file system blocks to device size blocks.
  86  */
  87 #define fsbtodb(fs, b)  ((b) << ((fs)->s_fsbtodb))
  88 #define dbtofsb(fs, b)  ((b) >> ((fs)->s_fsbtodb))
  89
  90 /* get group containing inode */
  91 #define ino_to_cg(fs, x)        (((x) - 1) / EXT2_INODES_PER_GROUP(fs))
  92
  93 /* get block containing inode from its number x */
  94 #define ino_to_fsba(fs, x)      (fs_cs(fs, ino_to_cg(fs, x)).bg_inode_table + \
  95         (((x)-1) % EXT2_INODES_PER_GROUP(fs))/EXT2_INODES_PER_BLOCK(fs))
  96
  97 /* get offset for inode in block */
  98 #define ino_to_fsbo(fs, x)      ((x-1) % EXT2_INODES_PER_BLOCK(fs))
  99
 100 /*
 101  * Give cylinder group number for a file system block.
 102  * Give cylinder group block number for a file system block.
 103  */
 104 #define dtog(fs, d)     (((d) - fs->s_es->s_first_data_block) / \
 105                         EXT2_BLOCKS_PER_GROUP(fs))
 106 #define dtogd(fs, d)    (((d) - fs->s_es->s_first_data_block) % \
 107                         EXT2_BLOCKS_PER_GROUP(fs))
 108
 109 /*
 110  * The following macros optimize certain frequently calculated
 111  * quantities by using shifts and masks in place of divisions
 112  * modulos and multiplications.
 113  */
 114 #define blkoff(fs, loc)         /* calculates (loc % fs->fs_bsize) */ \
 115         ((loc) & (fs)->s_qbmask)
 116
 117 #define lblktosize(fs, blk)     /* calculates (blk * fs->fs_bsize) */ \
 118         ((blk) << (fs->s_bshift))
 119
 120 /*
 121  * Used when converting logical blocks to offsets for getblk, bread,
 122  * etc.
 123  */
 124 #define lblktodoff(fs, blk)     /* calculates (blk * fs->fs_bsize) */ \
 125         ((off_t)(blk) << (fs)->s_bshift)
 126 #define fsbtodoff(fs, blk)      /* calculates (blk * fs->fs_fsize) */ \
 127         ((off_t)(blk) * (fs)->s_frag_size)
 128 #define dofftofsb(fs, blk)      /* calculates blk / fs->fs_fsize */   \
 129         ((daddr_t)((blk) / (fs)->s_frag_size))
 130 #define dbtodoff(fs, b)         /* calculates diskblk * sectorsize */ \
 131         ((off_t)(b) * ((fs)->s_frag_size >> (fs)->s_fsbtodb))
 132
 133 #define lblkno(fs, loc)         /* calculates (loc / fs->fs_bsize) */ \
 134         ((loc) >> (fs->s_bshift))
 135
 136 /* no fragments -> logical block number equal # of frags */
 137 #define numfrags(fs, loc)       /* calculates (loc / fs->fs_fsize) */ \
 138         ((loc) >> (fs->s_bshift))
 139
 140 #define fragroundup(fs, size)   /* calculates roundup(size, fs->fs_fsize) */ \
 141         roundup(size, fs->s_frag_size)
 142         /* was (((size) + (fs)->fs_qfmask) & (fs)->fs_fmask) */
 143
 144 /*
 145  * Determining the size of a file block in the file system.
 146  * easy w/o fragments
 147  */
 148 #define blksize(fs, ip, lbn) ((fs)->s_frag_size)
 149
 150 /*
 151  * INOPB is the number of inodes in a secondary storage block.
 152  */
 153 #define INOPB(fs)       EXT2_INODES_PER_BLOCK(fs)
 154
 155 /*
 156  * NINDIR is the number of indirects in a file system block.
 157  */
 158 #define NINDIR(fs)      (EXT2_ADDR_PER_BLOCK(fs))
 159
 160 extern int inside[], around[];
 161 extern u_char *fragtbl[];
 162
 163 /* a few remarks about superblock locking/unlocking
 164  * Linux provides special routines for doing so
 165  * I haven't figured out yet what BSD does
 166  * I think I'll try a vn_lock/vn_unlock on the device vnode
 167  */
 168 #define  DEVVP(inode)           (VFSTOEXT2(ITOV(inode)->v_mount)->um_devvp)
 169 #define  lock_super(devvp)      vn_lock(devvp, LK_EXCLUSIVE | LK_RETRY)
 170 #define  unlock_super(devvp)    vn_unlock(devvp)
 171
 172 /*
 173  * To lock a buffer, set the B_LOCKED flag and then brelse() it. To unlock,
 174  * reset the B_LOCKED flag and brelse() the buffer back on the LRU list
 175  */
 176 #define LCK_BUF(bp) { \
 177         crit_enter(); \
 178         (bp)->b_flags |= B_LOCKED; \
 179         crit_exit(); \
 180         brelse(bp); \
 181 }
 182
 183 #define ULCK_BUF(bp) { \
 184         long flags; \
 185         crit_enter(); \
 186         flags = (bp)->b_flags; \
 187         (bp)->b_flags &= ~(B_DIRTY | B_LOCKED); \
 188         BUF_LOCK(bp, LK_EXCLUSIVE); \
 189         bremfree(bp); \
 190         crit_exit(); \
 191         if (flags & B_DIRTY) \
 192                 bwrite(bp); \
 193         else \
 194                 brelse(bp); \
 195 }