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Annotation of Net2/ufs/fs.h, revision 1.1

1.1     ! root        1: /*
        !             2:  * Copyright (c) 1982, 1986 Regents of the University of California.
        !             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:  * 2. Redistributions in binary form must reproduce the above copyright
        !            11:  *    notice, this list of conditions and the following disclaimer in the
        !            12:  *    documentation and/or other materials provided with the distribution.
        !            13:  * 3. All advertising materials mentioning features or use of this software
        !            14:  *    must display the following acknowledgement:
        !            15:  *     This product includes software developed by the University of
        !            16:  *     California, Berkeley and its contributors.
        !            17:  * 4. Neither the name of the University nor the names of its contributors
        !            18:  *    may be used to endorse or promote products derived from this software
        !            19:  *    without specific prior written permission.
        !            20:  *
        !            21:  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
        !            22:  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
        !            23:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
        !            24:  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
        !            25:  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
        !            26:  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
        !            27:  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
        !            28:  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
        !            29:  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
        !            30:  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
        !            31:  * SUCH DAMAGE.
        !            32:  *
        !            33:  *     @(#)fs.h        7.12 (Berkeley) 5/8/91
        !            34:  */
        !            35: 
        !            36: /*
        !            37:  * Each disk drive contains some number of file systems.
        !            38:  * A file system consists of a number of cylinder groups.
        !            39:  * Each cylinder group has inodes and data.
        !            40:  *
        !            41:  * A file system is described by its super-block, which in turn
        !            42:  * describes the cylinder groups.  The super-block is critical
        !            43:  * data and is replicated in each cylinder group to protect against
        !            44:  * catastrophic loss.  This is done at `newfs' time and the critical
        !            45:  * super-block data does not change, so the copies need not be
        !            46:  * referenced further unless disaster strikes.
        !            47:  *
        !            48:  * For file system fs, the offsets of the various blocks of interest
        !            49:  * are given in the super block as:
        !            50:  *     [fs->fs_sblkno]         Super-block
        !            51:  *     [fs->fs_cblkno]         Cylinder group block
        !            52:  *     [fs->fs_iblkno]         Inode blocks
        !            53:  *     [fs->fs_dblkno]         Data blocks
        !            54:  * The beginning of cylinder group cg in fs, is given by
        !            55:  * the ``cgbase(fs, cg)'' macro.
        !            56:  *
        !            57:  * The first boot and super blocks are given in absolute disk addresses.
        !            58:  * The byte-offset forms are preferred, as they don't imply a sector size.
        !            59:  */
        !            60: #define BBSIZE         8192
        !            61: #define SBSIZE         8192
        !            62: #define        BBOFF           ((off_t)(0))
        !            63: #define        SBOFF           ((off_t)(BBOFF + BBSIZE))
        !            64: #define        BBLOCK          ((daddr_t)(0))
        !            65: #define        SBLOCK          ((daddr_t)(BBLOCK + BBSIZE / DEV_BSIZE))
        !            66: 
        !            67: /*
        !            68:  * Addresses stored in inodes are capable of addressing fragments
        !            69:  * of `blocks'. File system blocks of at most size MAXBSIZE can 
        !            70:  * be optionally broken into 2, 4, or 8 pieces, each of which is
        !            71:  * addressible; these pieces may be DEV_BSIZE, or some multiple of
        !            72:  * a DEV_BSIZE unit.
        !            73:  *
        !            74:  * Large files consist of exclusively large data blocks.  To avoid
        !            75:  * undue wasted disk space, the last data block of a small file may be
        !            76:  * allocated as only as many fragments of a large block as are
        !            77:  * necessary.  The file system format retains only a single pointer
        !            78:  * to such a fragment, which is a piece of a single large block that
        !            79:  * has been divided.  The size of such a fragment is determinable from
        !            80:  * information in the inode, using the ``blksize(fs, ip, lbn)'' macro.
        !            81:  *
        !            82:  * The file system records space availability at the fragment level;
        !            83:  * to determine block availability, aligned fragments are examined.
        !            84:  *
        !            85:  * The root inode is the root of the file system.
        !            86:  * Inode 0 can't be used for normal purposes and
        !            87:  * historically bad blocks were linked to inode 1,
        !            88:  * thus the root inode is 2. (inode 1 is no longer used for
        !            89:  * this purpose, however numerous dump tapes make this
        !            90:  * assumption, so we are stuck with it)
        !            91:  */
        !            92: #define        ROOTINO         ((ino_t)2)
        !            93: 
        !            94: /*
        !            95:  * MINBSIZE is the smallest allowable block size.
        !            96:  * In order to insure that it is possible to create files of size
        !            97:  * 2^32 with only two levels of indirection, MINBSIZE is set to 4096.
        !            98:  * MINBSIZE must be big enough to hold a cylinder group block,
        !            99:  * thus changes to (struct cg) must keep its size within MINBSIZE.
        !           100:  * Note that super blocks are always of size SBSIZE,
        !           101:  * and that both SBSIZE and MAXBSIZE must be >= MINBSIZE.
        !           102:  */
        !           103: #define MINBSIZE       4096
        !           104: 
        !           105: /*
        !           106:  * The path name on which the file system is mounted is maintained
        !           107:  * in fs_fsmnt. MAXMNTLEN defines the amount of space allocated in 
        !           108:  * the super block for this name.
        !           109:  * The limit on the amount of summary information per file system
        !           110:  * is defined by MAXCSBUFS. It is currently parameterized for a
        !           111:  * maximum of two million cylinders.
        !           112:  */
        !           113: #define MAXMNTLEN 512
        !           114: #define MAXCSBUFS 32
        !           115: 
        !           116: /*
        !           117:  * Per cylinder group information; summarized in blocks allocated
        !           118:  * from first cylinder group data blocks.  These blocks have to be
        !           119:  * read in from fs_csaddr (size fs_cssize) in addition to the
        !           120:  * super block.
        !           121:  *
        !           122:  * N.B. sizeof(struct csum) must be a power of two in order for
        !           123:  * the ``fs_cs'' macro to work (see below).
        !           124:  */
        !           125: struct csum {
        !           126:        long    cs_ndir;        /* number of directories */
        !           127:        long    cs_nbfree;      /* number of free blocks */
        !           128:        long    cs_nifree;      /* number of free inodes */
        !           129:        long    cs_nffree;      /* number of free frags */
        !           130: };
        !           131: 
        !           132: /*
        !           133:  * Super block for a file system.
        !           134:  */
        !           135: #define        FS_MAGIC        0x011954
        !           136: #define        FSOKAY          0x7c269d38
        !           137: struct fs
        !           138: {
        !           139:        struct  fs *fs_link;            /* linked list of file systems */
        !           140:        struct  fs *fs_rlink;           /*     used for incore super blocks */
        !           141:        daddr_t fs_sblkno;              /* addr of super-block in filesys */
        !           142:        daddr_t fs_cblkno;              /* offset of cyl-block in filesys */
        !           143:        daddr_t fs_iblkno;              /* offset of inode-blocks in filesys */
        !           144:        daddr_t fs_dblkno;              /* offset of first data after cg */
        !           145:        long    fs_cgoffset;            /* cylinder group offset in cylinder */
        !           146:        long    fs_cgmask;              /* used to calc mod fs_ntrak */
        !           147:        time_t  fs_time;                /* last time written */
        !           148:        long    fs_size;                /* number of blocks in fs */
        !           149:        long    fs_dsize;               /* number of data blocks in fs */
        !           150:        long    fs_ncg;                 /* number of cylinder groups */
        !           151:        long    fs_bsize;               /* size of basic blocks in fs */
        !           152:        long    fs_fsize;               /* size of frag blocks in fs */
        !           153:        long    fs_frag;                /* number of frags in a block in fs */
        !           154: /* these are configuration parameters */
        !           155:        long    fs_minfree;             /* minimum percentage of free blocks */
        !           156:        long    fs_rotdelay;            /* num of ms for optimal next block */
        !           157:        long    fs_rps;                 /* disk revolutions per second */
        !           158: /* these fields can be computed from the others */
        !           159:        long    fs_bmask;               /* ``blkoff'' calc of blk offsets */
        !           160:        long    fs_fmask;               /* ``fragoff'' calc of frag offsets */
        !           161:        long    fs_bshift;              /* ``lblkno'' calc of logical blkno */
        !           162:        long    fs_fshift;              /* ``numfrags'' calc number of frags */
        !           163: /* these are configuration parameters */
        !           164:        long    fs_maxcontig;           /* max number of contiguous blks */
        !           165:        long    fs_maxbpg;              /* max number of blks per cyl group */
        !           166: /* these fields can be computed from the others */
        !           167:        long    fs_fragshift;           /* block to frag shift */
        !           168:        long    fs_fsbtodb;             /* fsbtodb and dbtofsb shift constant */
        !           169:        long    fs_sbsize;              /* actual size of super block */
        !           170:        long    fs_csmask;              /* csum block offset */
        !           171:        long    fs_csshift;             /* csum block number */
        !           172:        long    fs_nindir;              /* value of NINDIR */
        !           173:        long    fs_inopb;               /* value of INOPB */
        !           174:        long    fs_nspf;                /* value of NSPF */
        !           175: /* yet another configuration parameter */
        !           176:        long    fs_optim;               /* optimization preference, see below */
        !           177: /* these fields are derived from the hardware */
        !           178:        long    fs_npsect;              /* # sectors/track including spares */
        !           179:        long    fs_interleave;          /* hardware sector interleave */
        !           180:        long    fs_trackskew;           /* sector 0 skew, per track */
        !           181:        long    fs_headswitch;          /* head switch time, usec */
        !           182:        long    fs_trkseek;             /* track-to-track seek, usec */
        !           183: /* sizes determined by number of cylinder groups and their sizes */
        !           184:        daddr_t fs_csaddr;              /* blk addr of cyl grp summary area */
        !           185:        long    fs_cssize;              /* size of cyl grp summary area */
        !           186:        long    fs_cgsize;              /* cylinder group size */
        !           187: /* these fields are derived from the hardware */
        !           188:        long    fs_ntrak;               /* tracks per cylinder */
        !           189:        long    fs_nsect;               /* sectors per track */
        !           190:        long    fs_spc;                 /* sectors per cylinder */
        !           191: /* this comes from the disk driver partitioning */
        !           192:        long    fs_ncyl;                /* cylinders in file system */
        !           193: /* these fields can be computed from the others */
        !           194:        long    fs_cpg;                 /* cylinders per group */
        !           195:        long    fs_ipg;                 /* inodes per group */
        !           196:        long    fs_fpg;                 /* blocks per group * fs_frag */
        !           197: /* this data must be re-computed after crashes */
        !           198:        struct  csum fs_cstotal;        /* cylinder summary information */
        !           199: /* these fields are cleared at mount time */
        !           200:        char    fs_fmod;                /* super block modified flag */
        !           201:        char    fs_clean;               /* file system is clean flag */
        !           202:        char    fs_ronly;               /* mounted read-only flag */
        !           203:        char    fs_flags;               /* currently unused flag */
        !           204:        char    fs_fsmnt[MAXMNTLEN];    /* name mounted on */
        !           205: /* these fields retain the current block allocation info */
        !           206:        long    fs_cgrotor;             /* last cg searched */
        !           207:        struct  csum *fs_csp[MAXCSBUFS];/* list of fs_cs info buffers */
        !           208:        long    fs_cpc;                 /* cyl per cycle in postbl */
        !           209:        short   fs_opostbl[16][8];      /* old rotation block list head */
        !           210:        long    fs_sparecon[55];        /* reserved for future constants */
        !           211:        long    fs_state;               /* validate fs_clean field */
        !           212:        quad    fs_qbmask;              /* ~fs_bmask - for use with quad size */
        !           213:        quad    fs_qfmask;              /* ~fs_fmask - for use with quad size */
        !           214:        long    fs_postblformat;        /* format of positional layout tables */
        !           215:        long    fs_nrpos;               /* number of rotaional positions */
        !           216:        long    fs_postbloff;           /* (short) rotation block list head */
        !           217:        long    fs_rotbloff;            /* (u_char) blocks for each rotation */
        !           218:        long    fs_magic;               /* magic number */
        !           219:        u_char  fs_space[1];            /* list of blocks for each rotation */
        !           220: /* actually longer */
        !           221: };
        !           222: /*
        !           223:  * Preference for optimization.
        !           224:  */
        !           225: #define FS_OPTTIME     0       /* minimize allocation time */
        !           226: #define FS_OPTSPACE    1       /* minimize disk fragmentation */
        !           227: 
        !           228: /*
        !           229:  * Rotational layout table format types
        !           230:  */
        !           231: #define FS_42POSTBLFMT         -1      /* 4.2BSD rotational table format */
        !           232: #define FS_DYNAMICPOSTBLFMT    1       /* dynamic rotational table format */
        !           233: /*
        !           234:  * Macros for access to superblock array structures
        !           235:  */
        !           236: #define fs_postbl(fs, cylno) \
        !           237:     (((fs)->fs_postblformat == FS_42POSTBLFMT) \
        !           238:     ? ((fs)->fs_opostbl[cylno]) \
        !           239:     : ((short *)((char *)(fs) + (fs)->fs_postbloff) + (cylno) * (fs)->fs_nrpos))
        !           240: #define fs_rotbl(fs) \
        !           241:     (((fs)->fs_postblformat == FS_42POSTBLFMT) \
        !           242:     ? ((fs)->fs_space) \
        !           243:     : ((u_char *)((char *)(fs) + (fs)->fs_rotbloff)))
        !           244: 
        !           245: /*
        !           246:  * Convert cylinder group to base address of its global summary info.
        !           247:  *
        !           248:  * N.B. This macro assumes that sizeof(struct csum) is a power of two.
        !           249:  */
        !           250: #define fs_cs(fs, indx) \
        !           251:        fs_csp[(indx) >> (fs)->fs_csshift][(indx) & ~(fs)->fs_csmask]
        !           252: 
        !           253: /*
        !           254:  * Cylinder group block for a file system.
        !           255:  */
        !           256: #define        CG_MAGIC        0x090255
        !           257: struct cg {
        !           258:        struct  cg *cg_link;            /* linked list of cyl groups */
        !           259:        long    cg_magic;               /* magic number */
        !           260:        time_t  cg_time;                /* time last written */
        !           261:        long    cg_cgx;                 /* we are the cgx'th cylinder group */
        !           262:        short   cg_ncyl;                /* number of cyl's this cg */
        !           263:        short   cg_niblk;               /* number of inode blocks this cg */
        !           264:        long    cg_ndblk;               /* number of data blocks this cg */
        !           265:        struct  csum cg_cs;             /* cylinder summary information */
        !           266:        long    cg_rotor;               /* position of last used block */
        !           267:        long    cg_frotor;              /* position of last used frag */
        !           268:        long    cg_irotor;              /* position of last used inode */
        !           269:        long    cg_frsum[MAXFRAG];      /* counts of available frags */
        !           270:        long    cg_btotoff;             /* (long) block totals per cylinder */
        !           271:        long    cg_boff;                /* (short) free block positions */
        !           272:        long    cg_iusedoff;            /* (char) used inode map */
        !           273:        long    cg_freeoff;             /* (u_char) free block map */
        !           274:        long    cg_nextfreeoff;         /* (u_char) next available space */
        !           275:        long    cg_sparecon[16];        /* reserved for future use */
        !           276:        u_char  cg_space[1];            /* space for cylinder group maps */
        !           277: /* actually longer */
        !           278: };
        !           279: /*
        !           280:  * Macros for access to cylinder group array structures
        !           281:  */
        !           282: #define cg_blktot(cgp) \
        !           283:     (((cgp)->cg_magic != CG_MAGIC) \
        !           284:     ? (((struct ocg *)(cgp))->cg_btot) \
        !           285:     : ((long *)((char *)(cgp) + (cgp)->cg_btotoff)))
        !           286: #define cg_blks(fs, cgp, cylno) \
        !           287:     (((cgp)->cg_magic != CG_MAGIC) \
        !           288:     ? (((struct ocg *)(cgp))->cg_b[cylno]) \
        !           289:     : ((short *)((char *)(cgp) + (cgp)->cg_boff) + (cylno) * (fs)->fs_nrpos))
        !           290: #define cg_inosused(cgp) \
        !           291:     (((cgp)->cg_magic != CG_MAGIC) \
        !           292:     ? (((struct ocg *)(cgp))->cg_iused) \
        !           293:     : ((char *)((char *)(cgp) + (cgp)->cg_iusedoff)))
        !           294: #define cg_blksfree(cgp) \
        !           295:     (((cgp)->cg_magic != CG_MAGIC) \
        !           296:     ? (((struct ocg *)(cgp))->cg_free) \
        !           297:     : ((u_char *)((char *)(cgp) + (cgp)->cg_freeoff)))
        !           298: #define cg_chkmagic(cgp) \
        !           299:     ((cgp)->cg_magic == CG_MAGIC || ((struct ocg *)(cgp))->cg_magic == CG_MAGIC)
        !           300: 
        !           301: /*
        !           302:  * The following structure is defined
        !           303:  * for compatibility with old file systems.
        !           304:  */
        !           305: struct ocg {
        !           306:        struct  ocg *cg_link;           /* linked list of cyl groups */
        !           307:        struct  ocg *cg_rlink;          /*     used for incore cyl groups */
        !           308:        time_t  cg_time;                /* time last written */
        !           309:        long    cg_cgx;                 /* we are the cgx'th cylinder group */
        !           310:        short   cg_ncyl;                /* number of cyl's this cg */
        !           311:        short   cg_niblk;               /* number of inode blocks this cg */
        !           312:        long    cg_ndblk;               /* number of data blocks this cg */
        !           313:        struct  csum cg_cs;             /* cylinder summary information */
        !           314:        long    cg_rotor;               /* position of last used block */
        !           315:        long    cg_frotor;              /* position of last used frag */
        !           316:        long    cg_irotor;              /* position of last used inode */
        !           317:        long    cg_frsum[8];            /* counts of available frags */
        !           318:        long    cg_btot[32];            /* block totals per cylinder */
        !           319:        short   cg_b[32][8];            /* positions of free blocks */
        !           320:        char    cg_iused[256];          /* used inode map */
        !           321:        long    cg_magic;               /* magic number */
        !           322:        u_char  cg_free[1];             /* free block map */
        !           323: /* actually longer */
        !           324: };
        !           325: 
        !           326: /*
        !           327:  * Turn file system block numbers into disk block addresses.
        !           328:  * This maps file system blocks to device size blocks.
        !           329:  */
        !           330: #define fsbtodb(fs, b) ((b) << (fs)->fs_fsbtodb)
        !           331: #define        dbtofsb(fs, b)  ((b) >> (fs)->fs_fsbtodb)
        !           332: 
        !           333: /*
        !           334:  * Cylinder group macros to locate things in cylinder groups.
        !           335:  * They calc file system addresses of cylinder group data structures.
        !           336:  */
        !           337: #define        cgbase(fs, c)   ((daddr_t)((fs)->fs_fpg * (c)))
        !           338: #define cgstart(fs, c) \
        !           339:        (cgbase(fs, c) + (fs)->fs_cgoffset * ((c) & ~((fs)->fs_cgmask)))
        !           340: #define        cgsblock(fs, c) (cgstart(fs, c) + (fs)->fs_sblkno)      /* super blk */
        !           341: #define        cgtod(fs, c)    (cgstart(fs, c) + (fs)->fs_cblkno)      /* cg block */
        !           342: #define        cgimin(fs, c)   (cgstart(fs, c) + (fs)->fs_iblkno)      /* inode blk */
        !           343: #define        cgdmin(fs, c)   (cgstart(fs, c) + (fs)->fs_dblkno)      /* 1st data */
        !           344: 
        !           345: /*
        !           346:  * Macros for handling inode numbers:
        !           347:  *     inode number to file system block offset.
        !           348:  *     inode number to cylinder group number.
        !           349:  *     inode number to file system block address.
        !           350:  */
        !           351: #define        itoo(fs, x)     ((x) % INOPB(fs))
        !           352: #define        itog(fs, x)     ((x) / (fs)->fs_ipg)
        !           353: #define        itod(fs, x) \
        !           354:        ((daddr_t)(cgimin(fs, itog(fs, x)) + \
        !           355:        (blkstofrags((fs), (((x) % (fs)->fs_ipg) / INOPB(fs))))))
        !           356: 
        !           357: /*
        !           358:  * Give cylinder group number for a file system block.
        !           359:  * Give cylinder group block number for a file system block.
        !           360:  */
        !           361: #define        dtog(fs, d)     ((d) / (fs)->fs_fpg)
        !           362: #define        dtogd(fs, d)    ((d) % (fs)->fs_fpg)
        !           363: 
        !           364: /*
        !           365:  * Extract the bits for a block from a map.
        !           366:  * Compute the cylinder and rotational position of a cyl block addr.
        !           367:  */
        !           368: #define blkmap(fs, map, loc) \
        !           369:     (((map)[(loc) / NBBY] >> ((loc) % NBBY)) & (0xff >> (NBBY - (fs)->fs_frag)))
        !           370: #define cbtocylno(fs, bno) \
        !           371:     ((bno) * NSPF(fs) / (fs)->fs_spc)
        !           372: #define cbtorpos(fs, bno) \
        !           373:     (((bno) * NSPF(fs) % (fs)->fs_spc / (fs)->fs_nsect * (fs)->fs_trackskew + \
        !           374:      (bno) * NSPF(fs) % (fs)->fs_spc % (fs)->fs_nsect * (fs)->fs_interleave) % \
        !           375:      (fs)->fs_nsect * (fs)->fs_nrpos / (fs)->fs_npsect)
        !           376: 
        !           377: /*
        !           378:  * The following macros optimize certain frequently calculated
        !           379:  * quantities by using shifts and masks in place of divisions
        !           380:  * modulos and multiplications.
        !           381:  */
        !           382: #define blkoff(fs, loc)                /* calculates (loc % fs->fs_bsize) */ \
        !           383:        ((loc) & ~(fs)->fs_bmask)
        !           384: #define fragoff(fs, loc)       /* calculates (loc % fs->fs_fsize) */ \
        !           385:        ((loc) & ~(fs)->fs_fmask)
        !           386: #define lblktosize(fs, blk)    /* calculates (blk * fs->fs_bsize) */ \
        !           387:        ((blk) << (fs)->fs_bshift)
        !           388: #define lblkno(fs, loc)                /* calculates (loc / fs->fs_bsize) */ \
        !           389:        ((loc) >> (fs)->fs_bshift)
        !           390: #define numfrags(fs, loc)      /* calculates (loc / fs->fs_fsize) */ \
        !           391:        ((loc) >> (fs)->fs_fshift)
        !           392: #define blkroundup(fs, size)   /* calculates roundup(size, fs->fs_bsize) */ \
        !           393:        (((size) + (fs)->fs_bsize - 1) & (fs)->fs_bmask)
        !           394: #define fragroundup(fs, size)  /* calculates roundup(size, fs->fs_fsize) */ \
        !           395:        (((size) + (fs)->fs_fsize - 1) & (fs)->fs_fmask)
        !           396: #define fragstoblks(fs, frags) /* calculates (frags / fs->fs_frag) */ \
        !           397:        ((frags) >> (fs)->fs_fragshift)
        !           398: #define blkstofrags(fs, blks)  /* calculates (blks * fs->fs_frag) */ \
        !           399:        ((blks) << (fs)->fs_fragshift)
        !           400: #define fragnum(fs, fsb)       /* calculates (fsb % fs->fs_frag) */ \
        !           401:        ((fsb) & ((fs)->fs_frag - 1))
        !           402: #define blknum(fs, fsb)                /* calculates rounddown(fsb, fs->fs_frag) */ \
        !           403:        ((fsb) &~ ((fs)->fs_frag - 1))
        !           404: 
        !           405: /*
        !           406:  * Determine the number of available frags given a
        !           407:  * percentage to hold in reserve
        !           408:  */
        !           409: #define freespace(fs, percentreserved) \
        !           410:        (blkstofrags((fs), (fs)->fs_cstotal.cs_nbfree) + \
        !           411:        (fs)->fs_cstotal.cs_nffree - ((fs)->fs_dsize * (percentreserved) / 100))
        !           412: 
        !           413: /*
        !           414:  * Determining the size of a file block in the file system.
        !           415:  */
        !           416: #define blksize(fs, ip, lbn) \
        !           417:        (((lbn) >= NDADDR || (ip)->i_size >= ((lbn) + 1) << (fs)->fs_bshift) \
        !           418:            ? (fs)->fs_bsize \
        !           419:            : (fragroundup(fs, blkoff(fs, (ip)->i_size))))
        !           420: #define dblksize(fs, dip, lbn) \
        !           421:        (((lbn) >= NDADDR || (dip)->di_size >= ((lbn) + 1) << (fs)->fs_bshift) \
        !           422:            ? (fs)->fs_bsize \
        !           423:            : (fragroundup(fs, blkoff(fs, (dip)->di_size))))
        !           424: 
        !           425: /*
        !           426:  * Number of disk sectors per block; assumes DEV_BSIZE byte sector size.
        !           427:  */
        !           428: #define        NSPB(fs)        ((fs)->fs_nspf << (fs)->fs_fragshift)
        !           429: #define        NSPF(fs)        ((fs)->fs_nspf)
        !           430: 
        !           431: /*
        !           432:  * INOPB is the number of inodes in a secondary storage block.
        !           433:  */
        !           434: #define        INOPB(fs)       ((fs)->fs_inopb)
        !           435: #define        INOPF(fs)       ((fs)->fs_inopb >> (fs)->fs_fragshift)
        !           436: 
        !           437: /*
        !           438:  * NINDIR is the number of indirects in a file system block.
        !           439:  */
        !           440: #define        NINDIR(fs)      ((fs)->fs_nindir)

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