The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/fs/ext2fs/ext2fs.h

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    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  * $FreeBSD: releng/9.1/sys/fs/ext2fs/ext2fs.h 233322 2012-03-22 20:31:52Z pfg $
    8  */
    9 /*-
   10  * Copyright (c) 2009 Aditya Sarawgi
   11  * All rights reserved.
   12  *
   13  * Redistribution and use in source and binary forms, with or without
   14  * modification, are permitted provided that the following conditions
   15  * are met:
   16  * 1. Redistributions of source code must retain the above copyright
   17  *    notice, this list of conditions and the following disclaimer.
   18  * 2. Redistributions in binary form must reproduce the above copyright
   19  *    notice, this list of conditions and the following disclaimer in the
   20  *    documentation and/or other materials provided with the distribution.
   21  *
   22  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   32  * SUCH DAMAGE.
   33  *
   34  * 
   35  */
   36 
   37 #ifndef _FS_EXT2FS_EXT2FS_H_
   38 #define _FS_EXT2FS_EXT2FS_H_
   39 
   40 #include <sys/types.h>
   41 
   42 /*
   43  * Maximal count of links to a file
   44  */
   45 #define EXT2_LINK_MAX           32000
   46 
   47 /*
   48  * A summary of contiguous blocks of various sizes is maintained
   49  * in each cylinder group. Normally this is set by the initial
   50  * value of fs_maxcontig.
   51  *
   52  * XXX:FS_MAXCONTIG is set to 16 to conserve space. Here we set
   53  * EXT2_MAXCONTIG to 32 for better performance.
   54  */
   55 #define EXT2_MAXCONTIG          32
   56 
   57 /*
   58  * Constants relative to the data blocks
   59  */
   60 #define EXT2_NDIR_BLOCKS                12
   61 #define EXT2_IND_BLOCK                  EXT2_NDIR_BLOCKS
   62 #define EXT2_DIND_BLOCK                 (EXT2_IND_BLOCK + 1)
   63 #define EXT2_TIND_BLOCK                 (EXT2_DIND_BLOCK + 1)
   64 #define EXT2_N_BLOCKS                   (EXT2_TIND_BLOCK + 1)
   65 #define EXT2_MAXSYMLINKLEN              (EXT2_N_BLOCKS * sizeof(uint32_t))
   66 
   67 /*
   68  * The path name on which the file system is mounted is maintained
   69  * in fs_fsmnt. MAXMNTLEN defines the amount of space allocated in
   70  * the super block for this name.
   71  */
   72 #define MAXMNTLEN 512
   73 
   74 /*
   75  * Super block for an ext2fs file system.
   76  */
   77 struct ext2fs {
   78         uint32_t  e2fs_icount;          /* Inode count */
   79         uint32_t  e2fs_bcount;          /* blocks count */
   80         uint32_t  e2fs_rbcount;         /* reserved blocks count */
   81         uint32_t  e2fs_fbcount;         /* free blocks count */
   82         uint32_t  e2fs_ficount;         /* free inodes count */
   83         uint32_t  e2fs_first_dblock;    /* first data block */
   84         uint32_t  e2fs_log_bsize;       /* block size = 1024*(2^e2fs_log_bsize) */
   85         uint32_t  e2fs_log_fsize;       /* fragment size */
   86         uint32_t  e2fs_bpg;             /* blocks per group */
   87         uint32_t  e2fs_fpg;             /* frags per group */
   88         uint32_t  e2fs_ipg;             /* inodes per group */
   89         uint32_t  e2fs_mtime;           /* mount time */
   90         uint32_t  e2fs_wtime;           /* write time */
   91         uint16_t  e2fs_mnt_count;       /* mount count */
   92         uint16_t  e2fs_max_mnt_count;   /* max mount count */
   93         uint16_t  e2fs_magic;           /* magic number */
   94         uint16_t  e2fs_state;           /* file system state */
   95         uint16_t  e2fs_beh;             /* behavior on errors */
   96         uint16_t  e2fs_minrev;          /* minor revision level */
   97         uint32_t  e2fs_lastfsck;        /* time of last fsck */
   98         uint32_t  e2fs_fsckintv;        /* max time between fscks */
   99         uint32_t  e2fs_creator;         /* creator OS */
  100         uint32_t  e2fs_rev;             /* revision level */
  101         uint16_t  e2fs_ruid;            /* default uid for reserved blocks */
  102         uint16_t  e2fs_rgid;            /* default gid for reserved blocks */
  103         /* EXT2_DYNAMIC_REV superblocks */
  104         uint32_t  e2fs_first_ino;       /* first non-reserved inode */
  105         uint16_t  e2fs_inode_size;      /* size of inode structure */
  106         uint16_t  e2fs_block_group_nr;  /* block grp number of this sblk*/
  107         uint32_t  e2fs_features_compat; /*  compatible feature set */
  108         uint32_t  e2fs_features_incompat; /* incompatible feature set */
  109         uint32_t  e2fs_features_rocompat; /* RO-compatible feature set */
  110         uint8_t   e2fs_uuid[16];        /* 128-bit uuid for volume */
  111         char      e2fs_vname[16];       /* volume name */
  112         char      e2fs_fsmnt[64];       /* name mounted on */
  113         uint32_t  e2fs_algo;            /* For compression */
  114         uint8_t   e2fs_prealloc;        /* # of blocks for old prealloc */
  115         uint8_t   e2fs_dir_prealloc;    /* # of blocks for old prealloc dirs */
  116         uint16_t  e2fs_reserved_ngdb;   /* # of reserved gd blocks for resize */
  117         char      e3fs_journal_uuid[16]; /* uuid of journal superblock */
  118         uint32_t  e3fs_journal_inum;    /* inode number of journal file */
  119         uint32_t  e3fs_journal_dev;     /* device number of journal file */
  120         uint32_t  e3fs_last_orphan;     /* start of list of inodes to delete */
  121         uint32_t  e3fs_hash_seed[4];    /* HTREE hash seed */
  122         char      e3fs_def_hash_version; /* Default hash version to use */
  123         char      e3fs_reserved_char_pad;
  124         uint32_t  e3fs_default_mount_opts;
  125         uint32_t  e3fs_first_meta_bg;   /* First metablock block group */
  126         uint32_t  e3fs_mkfs_time;      /* when the fs was created */
  127         uint32_t  e3fs_jnl_blks[17];   /* backup of the journal inode */
  128         uint32_t  e4fs_bcount_hi;      /* block count */
  129         uint32_t  e4fs_rbcount_hi;     /* reserved blocks count */
  130         uint32_t  e4fs_fbcount_hi;     /* free blocks count */
  131         uint16_t  e4fs_min_extra_isize;/* all inodes have at least some bytes */
  132         uint16_t  e4fs_want_extra_isize; /* inodes must reserve some bytes */
  133         uint32_t  e4fs_flags;     /* miscellaneous flags */
  134         uint16_t  e4fs_raid_stride;    /* RAID stride */
  135         uint16_t  e4fs_mmpintv; /* number of seconds to wait in MMP checking */
  136         uint64_t  e4fs_mmpblk;   /* block for multi-mount protection */
  137         uint32_t  e4fs_raid_stripe_wid;/* blocks on all data disks (N * stride) */
  138         uint8_t   e4fs_log_gpf; /* FLEX_BG group size */ 
  139         uint8_t   e4fs_char_pad2;
  140         uint16_t  e4fs_pad;
  141         uint32_t  reserved2[162];       /* Padding to the end of the block */   
  142 };
  143 
  144 
  145 /*
  146  * In-Memory Superblock
  147  */
  148 
  149 struct m_ext2fs {
  150         struct ext2fs * e2fs;
  151         char     e2fs_fsmnt[MAXMNTLEN];/* name mounted on */
  152         char     e2fs_ronly;      /* mounted read-only flag */
  153         char     e2fs_fmod;       /* super block modified flag */
  154         uint32_t e2fs_bsize;      /* Block size */
  155         uint32_t e2fs_bshift;     /* calc of logical block no */
  156         int32_t  e2fs_bmask;      /* calc of block offset */
  157         int32_t  e2fs_bpg;        /* Number of blocks per group */
  158         int64_t  e2fs_qbmask;     /* = s_blocksize -1 */
  159         uint32_t e2fs_fsbtodb;    /* Shift to get disk block */
  160         uint32_t e2fs_ipg;        /* Number of inodes per group */
  161         uint32_t e2fs_ipb;        /* Number of inodes per block */
  162         uint32_t e2fs_itpg;       /* Number of inode table per group */
  163         uint32_t e2fs_fsize;      /* Size of fragments per block */
  164         uint32_t e2fs_fpb;        /* Number of fragments per block */
  165         uint32_t e2fs_fpg;        /* Number of fragments per group */
  166         uint32_t e2fs_dbpg;       /* Number of descriptor blocks per group */
  167         uint32_t e2fs_descpb;     /* Number of group descriptors per block */
  168         uint32_t e2fs_gdbcount;   /* Number of group descriptors */
  169         uint32_t e2fs_gcount;     /* Number of groups */
  170         uint32_t e2fs_first_inode;/* First inode on fs */
  171         int32_t  e2fs_isize;      /* Size of inode */
  172         uint32_t e2fs_mount_opt;
  173         uint32_t e2fs_blocksize_bits;
  174         uint32_t e2fs_total_dir;  /* Total number of directories */
  175         uint8_t *e2fs_contigdirs; /* (u) # of contig. allocated dirs */
  176         char     e2fs_wasvalid;   /* valid at mount time */
  177         off_t    e2fs_maxfilesize;
  178         struct   ext2_gd *e2fs_gd; /* Group Descriptors */
  179         int32_t  e2fs_maxcontig;        /* max number of contiguous blks */
  180         int32_t  e2fs_contigsumsize;    /* size of cluster summary array */
  181         int32_t *e2fs_maxcluster;       /* max cluster in each cyl group */
  182         struct   csum *e2fs_clustersum; /* cluster summary in each cyl group */
  183 };
  184 
  185 /*
  186  * The second extended file system version
  187  */
  188 #define E2FS_DATE               "95/08/09"
  189 #define E2FS_VERSION            "0.5b"
  190 
  191 /*
  192  * The second extended file system magic number
  193  */
  194 #define E2FS_MAGIC              0xEF53
  195 
  196 /*
  197  * Revision levels
  198  */
  199 #define E2FS_REV0               0       /* The good old (original) format */
  200 #define E2FS_REV1               1       /* V2 format w/ dynamic inode sizes */
  201 
  202 #define E2FS_CURRENT_REV        E2FS_REV0
  203 #define E2FS_MAX_SUPP_REV       E2FS_REV1
  204 
  205 #define E2FS_REV0_INODE_SIZE 128
  206 
  207 /*
  208  * compatible/incompatible features
  209  */
  210 #define EXT2F_COMPAT_PREALLOC           0x0001
  211 #define EXT2F_COMPAT_HASJOURNAL         0x0004
  212 #define EXT2F_COMPAT_RESIZE             0x0010
  213 
  214 #define EXT2F_ROCOMPAT_SPARSESUPER      0x0001
  215 #define EXT2F_ROCOMPAT_LARGEFILE        0x0002
  216 #define EXT2F_ROCOMPAT_BTREE_DIR        0x0004
  217 #define EXT4F_ROCOMPAT_EXTRA_ISIZE      0x0040
  218 
  219 #define EXT2F_INCOMPAT_COMP             0x0001
  220 #define EXT2F_INCOMPAT_FTYPE            0x0002
  221 
  222 /*
  223  * Features supported in this implementation
  224  *
  225  * We support the following REV1 features:
  226  * - EXT2F_ROCOMPAT_SPARSESUPER
  227  * - EXT2F_ROCOMPAT_LARGEFILE
  228  * - EXT2F_INCOMPAT_FTYPE
  229  */
  230 #define EXT2F_COMPAT_SUPP               0x0000
  231 #define EXT2F_ROCOMPAT_SUPP             (EXT2F_ROCOMPAT_SPARSESUPER | \
  232                                          EXT2F_ROCOMPAT_LARGEFILE | \
  233                                          EXT4F_ROCOMPAT_EXTRA_ISIZE)
  234 #define EXT2F_INCOMPAT_SUPP             EXT2F_INCOMPAT_FTYPE
  235 
  236 /* Assume that user mode programs are passing in an ext2fs superblock, not
  237  * a kernel struct super_block.  This will allow us to call the feature-test
  238  * macros from user land. */
  239 #define EXT2_SB(sb)     (sb)
  240 
  241 /*
  242  * Feature set definitions
  243  */
  244 #define EXT2_HAS_COMPAT_FEATURE(sb,mask)                        \
  245         ( EXT2_SB(sb)->e2fs->e2fs_features_compat & htole32(mask) )
  246 #define EXT2_HAS_RO_COMPAT_FEATURE(sb,mask)                     \
  247         ( EXT2_SB(sb)->e2fs->e2fs_features_rocompat & htole32(mask) )
  248 #define EXT2_HAS_INCOMPAT_FEATURE(sb,mask)                      \
  249         ( EXT2_SB(sb)->e2fs->e2fs_features_incompat & htole32(mask) )
  250 
  251 /*
  252  * Definitions of behavior on errors
  253  */
  254 #define E2FS_BEH_CONTINUE               1       /* continue operation */
  255 #define E2FS_BEH_READONLY               2       /* remount fs read only */
  256 #define E2FS_BEH_PANIC                  3       /* cause panic */
  257 #define E2FS_BEH_DEFAULT                E2FS_BEH_CONTINUE
  258 
  259 /*
  260  * OS identification
  261  */
  262 #define E2FS_OS_LINUX           0
  263 #define E2FS_OS_HURD            1
  264 #define E2FS_OS_MASIX           2
  265 #define E2FS_OS_FREEBSD         3
  266 #define E2FS_OS_LITES           4
  267 
  268 /*
  269  * File clean flags
  270  */
  271 #define E2FS_ISCLEAN                    0x0001  /* Unmounted cleanly */
  272 #define E2FS_ERRORS                     0x0002  /* Errors detected */
  273 
  274 /* ext2 file system block group descriptor */
  275 
  276 struct ext2_gd {
  277         uint32_t ext2bgd_b_bitmap;      /* blocks bitmap block */
  278         uint32_t ext2bgd_i_bitmap;      /* inodes bitmap block */
  279         uint32_t ext2bgd_i_tables;      /* inodes table block  */
  280         uint16_t ext2bgd_nbfree;        /* number of free blocks */
  281         uint16_t ext2bgd_nifree;        /* number of free inodes */
  282         uint16_t ext2bgd_ndirs; /* number of directories */
  283         uint16_t reserved;
  284         uint32_t reserved2[3];
  285 };
  286 
  287 /* cluster summary information */
  288 
  289 struct csum {
  290         int8_t   cs_init; /* cluster summary has been initialized */
  291         int32_t *cs_sum;  /* cluster summary array */
  292 };
  293 
  294 /* EXT2FS metadatas are stored in little-endian byte order. These macros
  295  * helps reading these metadatas
  296  */
  297 
  298 #define e2fs_cgload(old, new, size) memcpy((new), (old), (size));
  299 #define e2fs_cgsave(old, new, size) memcpy((new), (old), (size));
  300 
  301 /*
  302  * Macro-instructions used to manage several block sizes
  303  */
  304 #define EXT2_MIN_BLOCK_SIZE             1024
  305 #define EXT2_MAX_BLOCK_SIZE             4096
  306 #define EXT2_MIN_BLOCK_LOG_SIZE           10
  307 #if defined(_KERNEL)
  308 # define EXT2_BLOCK_SIZE(s)             ((s)->e2fs_bsize)
  309 #else
  310 # define EXT2_BLOCK_SIZE(s)             (EXT2_MIN_BLOCK_SIZE << (s)->e2fs_log_bsize)
  311 #endif
  312 #define EXT2_ADDR_PER_BLOCK(s)          (EXT2_BLOCK_SIZE(s) / sizeof(uint32_t))
  313 #if defined(_KERNEL)
  314 # define EXT2_BLOCK_SIZE_BITS(s)        ((s)->e2fs_blocksize_bits)
  315 #else
  316 # define EXT2_BLOCK_SIZE_BITS(s)        ((s)->e2fs_log_bsize + 10)
  317 #endif
  318 #if defined(_KERNEL)
  319 #define EXT2_ADDR_PER_BLOCK_BITS(s)     (EXT2_SB(s)->s_addr_per_block_bits)
  320 #define EXT2_INODE_SIZE(s)              (EXT2_SB(s)->e2fs_isize)
  321 #define EXT2_FIRST_INO(s)               (EXT2_SB(s)->e2fs_first_inode)
  322 #else
  323 #define EXT2_INODE_SIZE(s)      (((s)->s_rev_level == E2FS_REV0) ? \
  324                                  E2FS_REV0 : (s)->s_inode_size)
  325 #define EXT2_FIRST_INO(s)       (((s)->s_rev_level == E2FS_REV0) ? \
  326                                  E2FS_REV0 : (s)->e2fs_first_ino)
  327 #endif
  328 
  329 /*
  330  * Macro-instructions used to manage fragments
  331  */
  332 #define EXT2_MIN_FRAG_SIZE              1024
  333 #define EXT2_MAX_FRAG_SIZE              4096
  334 #define EXT2_MIN_FRAG_LOG_SIZE            10
  335 #if defined(_KERNEL)
  336 # define EXT2_FRAG_SIZE(s)              (EXT2_SB(s)->e2fs_fsize)
  337 # define EXT2_FRAGS_PER_BLOCK(s)        (EXT2_SB(s)->e2fs_fpb)
  338 #else
  339 # define EXT2_FRAG_SIZE(s)              (EXT2_MIN_FRAG_SIZE << (s)->e2fs_log_fsize)
  340 # define EXT2_FRAGS_PER_BLOCK(s)        (EXT2_BLOCK_SIZE(s) / EXT2_FRAG_SIZE(s))
  341 #endif
  342 
  343 /*
  344  * Macro-instructions used to manage group descriptors
  345  */
  346 #if defined(_KERNEL)
  347 # define EXT2_BLOCKS_PER_GROUP(s)       (EXT2_SB(s)->e2fs_bpg)
  348 # define EXT2_DESC_PER_BLOCK(s)         (EXT2_SB(s)->e2fs_descpb)
  349 # define EXT2_DESC_PER_BLOCK_BITS(s)    (EXT2_SB(s)->s_desc_per_block_bits)
  350 #else
  351 # define EXT2_BLOCKS_PER_GROUP(s)       ((s)->e2fs_bpg)
  352 # define EXT2_DESC_PER_BLOCK(s)         (EXT2_BLOCK_SIZE(s) / sizeof(struct ext2_gd))
  353 
  354 #endif
  355 
  356 #endif  /* !_FS_EXT2FS_EXT2FS_H_ */

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