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/10.2/sys/fs/ext2fs/ext2fs.h 281841 2015-04-22 00:38:11Z 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  * Super block for an ext2fs file system.
   44  */
   45 struct ext2fs {
   46         uint32_t  e2fs_icount;          /* Inode count */
   47         uint32_t  e2fs_bcount;          /* blocks count */
   48         uint32_t  e2fs_rbcount;         /* reserved blocks count */
   49         uint32_t  e2fs_fbcount;         /* free blocks count */
   50         uint32_t  e2fs_ficount;         /* free inodes count */
   51         uint32_t  e2fs_first_dblock;    /* first data block */
   52         uint32_t  e2fs_log_bsize;       /* block size = 1024*(2^e2fs_log_bsize) */
   53         uint32_t  e2fs_log_fsize;       /* fragment size */
   54         uint32_t  e2fs_bpg;             /* blocks per group */
   55         uint32_t  e2fs_fpg;             /* frags per group */
   56         uint32_t  e2fs_ipg;             /* inodes per group */
   57         uint32_t  e2fs_mtime;           /* mount time */
   58         uint32_t  e2fs_wtime;           /* write time */
   59         uint16_t  e2fs_mnt_count;       /* mount count */
   60         uint16_t  e2fs_max_mnt_count;   /* max mount count */
   61         uint16_t  e2fs_magic;           /* magic number */
   62         uint16_t  e2fs_state;           /* file system state */
   63         uint16_t  e2fs_beh;             /* behavior on errors */
   64         uint16_t  e2fs_minrev;          /* minor revision level */
   65         uint32_t  e2fs_lastfsck;        /* time of last fsck */
   66         uint32_t  e2fs_fsckintv;        /* max time between fscks */
   67         uint32_t  e2fs_creator;         /* creator OS */
   68         uint32_t  e2fs_rev;             /* revision level */
   69         uint16_t  e2fs_ruid;            /* default uid for reserved blocks */
   70         uint16_t  e2fs_rgid;            /* default gid for reserved blocks */
   71         /* EXT2_DYNAMIC_REV superblocks */
   72         uint32_t  e2fs_first_ino;       /* first non-reserved inode */
   73         uint16_t  e2fs_inode_size;      /* size of inode structure */
   74         uint16_t  e2fs_block_group_nr;  /* block grp number of this sblk*/
   75         uint32_t  e2fs_features_compat; /*  compatible feature set */
   76         uint32_t  e2fs_features_incompat; /* incompatible feature set */
   77         uint32_t  e2fs_features_rocompat; /* RO-compatible feature set */
   78         uint8_t   e2fs_uuid[16];        /* 128-bit uuid for volume */
   79         char      e2fs_vname[16];       /* volume name */
   80         char      e2fs_fsmnt[64];       /* name mounted on */
   81         uint32_t  e2fs_algo;            /* For compression */
   82         uint8_t   e2fs_prealloc;        /* # of blocks for old prealloc */
   83         uint8_t   e2fs_dir_prealloc;    /* # of blocks for old prealloc dirs */
   84         uint16_t  e2fs_reserved_ngdb;   /* # of reserved gd blocks for resize */
   85         char      e3fs_journal_uuid[16]; /* uuid of journal superblock */
   86         uint32_t  e3fs_journal_inum;    /* inode number of journal file */
   87         uint32_t  e3fs_journal_dev;     /* device number of journal file */
   88         uint32_t  e3fs_last_orphan;     /* start of list of inodes to delete */
   89         uint32_t  e3fs_hash_seed[4];    /* HTREE hash seed */
   90         char      e3fs_def_hash_version; /* Default hash version to use */
   91         char      e3fs_reserved_char_pad;
   92         uint32_t  e3fs_default_mount_opts;
   93         uint32_t  e3fs_first_meta_bg;   /* First metablock block group */
   94         uint32_t  e3fs_mkfs_time;      /* when the fs was created */
   95         uint32_t  e3fs_jnl_blks[17];   /* backup of the journal inode */
   96         uint32_t  e4fs_bcount_hi;      /* block count */
   97         uint32_t  e4fs_rbcount_hi;     /* reserved blocks count */
   98         uint32_t  e4fs_fbcount_hi;     /* free blocks count */
   99         uint16_t  e4fs_min_extra_isize;/* all inodes have at least some bytes */
  100         uint16_t  e4fs_want_extra_isize; /* inodes must reserve some bytes */
  101         uint32_t  e4fs_flags;     /* miscellaneous flags */
  102         uint16_t  e4fs_raid_stride;    /* RAID stride */
  103         uint16_t  e4fs_mmpintv; /* number of seconds to wait in MMP checking */
  104         uint64_t  e4fs_mmpblk;   /* block for multi-mount protection */
  105         uint32_t  e4fs_raid_stripe_wid;/* blocks on all data disks (N * stride) */
  106         uint8_t   e4fs_log_gpf; /* FLEX_BG group size */
  107         uint8_t   e4fs_char_pad2;
  108         uint16_t  e4fs_pad;
  109         uint32_t  reserved2[162];       /* Padding to the end of the block */
  110 };
  111 
  112 /*
  113  * The path name on which the file system is mounted is maintained
  114  * in fs_fsmnt. MAXMNTLEN defines the amount of space allocated in
  115  * the super block for this name.
  116  */
  117 #define MAXMNTLEN 512
  118 
  119 /*
  120  * In-Memory Superblock
  121  */
  122 
  123 struct m_ext2fs {
  124         struct ext2fs * e2fs;
  125         char     e2fs_fsmnt[MAXMNTLEN];/* name mounted on */
  126         char     e2fs_ronly;      /* mounted read-only flag */
  127         char     e2fs_fmod;       /* super block modified flag */
  128         uint32_t e2fs_bsize;      /* Block size */
  129         uint32_t e2fs_bshift;     /* calc of logical block no */
  130         uint32_t e2fs_bpg;        /* Number of blocks per group */
  131         int64_t  e2fs_qbmask;     /* = s_blocksize -1 */
  132         uint32_t e2fs_fsbtodb;    /* Shift to get disk block */
  133         uint32_t e2fs_ipg;        /* Number of inodes per group */
  134         uint32_t e2fs_ipb;        /* Number of inodes per block */
  135         uint32_t e2fs_itpg;       /* Number of inode table per group */
  136         uint32_t e2fs_fsize;      /* Size of fragments per block */
  137         uint32_t e2fs_fpb;        /* Number of fragments per block */
  138         uint32_t e2fs_fpg;        /* Number of fragments per group */
  139         uint32_t e2fs_gdbcount;   /* Number of group descriptors */
  140         uint32_t e2fs_gcount;     /* Number of groups */
  141         uint32_t e2fs_isize;      /* Size of inode */
  142         uint32_t e2fs_total_dir;  /* Total number of directories */
  143         uint8_t *e2fs_contigdirs; /* (u) # of contig. allocated dirs */
  144         char     e2fs_wasvalid;   /* valid at mount time */
  145         off_t    e2fs_maxfilesize;
  146         struct   ext2_gd *e2fs_gd; /* Group Descriptors */
  147         int32_t  e2fs_contigsumsize;    /* size of cluster summary array */
  148         int32_t *e2fs_maxcluster;       /* max cluster in each cyl group */
  149         struct   csum *e2fs_clustersum; /* cluster summary in each cyl group */
  150 };
  151 
  152 /* cluster summary information */
  153 
  154 struct csum {
  155         int8_t   cs_init; /* cluster summary has been initialized */
  156         int32_t *cs_sum;  /* cluster summary array */
  157 };
  158 
  159 /*
  160  * The second extended file system magic number
  161  */
  162 #define E2FS_MAGIC              0xEF53
  163 
  164 /*
  165  * Revision levels
  166  */
  167 #define E2FS_REV0               0       /* The good old (original) format */
  168 #define E2FS_REV1               1       /* V2 format w/ dynamic inode sizes */
  169 
  170 #define E2FS_REV0_INODE_SIZE 128
  171 
  172 /*
  173  * compatible/incompatible features
  174  */
  175 #define EXT2F_COMPAT_PREALLOC           0x0001
  176 #define EXT2F_COMPAT_HASJOURNAL         0x0004
  177 #define EXT2F_COMPAT_RESIZE             0x0010
  178 #define EXT2F_COMPAT_DIRHASHINDEX       0x0020
  179 
  180 #define EXT2F_ROCOMPAT_SPARSESUPER      0x0001
  181 #define EXT2F_ROCOMPAT_LARGEFILE        0x0002
  182 #define EXT2F_ROCOMPAT_BTREE_DIR        0x0004
  183 #define EXT2F_ROCOMPAT_HUGE_FILE        0x0008
  184 #define EXT2F_ROCOMPAT_GDT_CSUM         0x0010
  185 #define EXT2F_ROCOMPAT_DIR_NLINK        0x0020
  186 #define EXT2F_ROCOMPAT_EXTRA_ISIZE      0x0040
  187 
  188 #define EXT2F_INCOMPAT_COMP             0x0001
  189 #define EXT2F_INCOMPAT_FTYPE            0x0002
  190 #define EXT2F_INCOMPAT_META_BG          0x0010
  191 #define EXT2F_INCOMPAT_EXTENTS          0x0040
  192 #define EXT2F_INCOMPAT_64BIT            0x0080
  193 #define EXT2F_INCOMPAT_MMP              0x0100
  194 #define EXT2F_INCOMPAT_FLEX_BG          0x0200
  195 
  196 /*
  197  * Features supported in this implementation
  198  *
  199  * We support the following REV1 features:
  200  * - EXT2F_ROCOMPAT_SPARSESUPER
  201  * - EXT2F_ROCOMPAT_LARGEFILE
  202  * - EXT2F_ROCOMPAT_EXTRA_ISIZE
  203  * - EXT2F_INCOMPAT_FTYPE
  204  *
  205  * We partially support (read-only) the following EXT4 features:
  206  * - EXT2F_ROCOMPAT_HUGE_FILE
  207  * - EXT2F_INCOMPAT_EXTENTS
  208  *
  209  * We do not support these EXT4 features but they are irrelevant
  210  * for read-only support:
  211  * - EXT2F_INCOMPAT_FLEX_BG
  212  * - EXT2F_INCOMPAT_META_BG
  213  */
  214 #define EXT2F_ROCOMPAT_SUPP             (EXT2F_ROCOMPAT_SPARSESUPER | \
  215                                          EXT2F_ROCOMPAT_LARGEFILE | \
  216                                          EXT2F_ROCOMPAT_EXTRA_ISIZE)
  217 #define EXT2F_INCOMPAT_SUPP             EXT2F_INCOMPAT_FTYPE
  218 #define EXT4F_RO_INCOMPAT_SUPP          (EXT2F_INCOMPAT_EXTENTS | \
  219                                          EXT2F_INCOMPAT_FLEX_BG | \
  220                                          EXT2F_INCOMPAT_META_BG )
  221 
  222 /* Assume that user mode programs are passing in an ext2fs superblock, not
  223  * a kernel struct super_block.  This will allow us to call the feature-test
  224  * macros from user land. */
  225 #define EXT2_SB(sb)     (sb)
  226 
  227 /*
  228  * Feature set definitions
  229  */
  230 #define EXT2_HAS_COMPAT_FEATURE(sb,mask)                        \
  231         ( EXT2_SB(sb)->e2fs->e2fs_features_compat & htole32(mask) )
  232 #define EXT2_HAS_RO_COMPAT_FEATURE(sb,mask)                     \
  233         ( EXT2_SB(sb)->e2fs->e2fs_features_rocompat & htole32(mask) )
  234 #define EXT2_HAS_INCOMPAT_FEATURE(sb,mask)                      \
  235         ( EXT2_SB(sb)->e2fs->e2fs_features_incompat & htole32(mask) )
  236 
  237 /*
  238  * File clean flags
  239  */
  240 #define E2FS_ISCLEAN                    0x0001  /* Unmounted cleanly */
  241 #define E2FS_ERRORS                     0x0002  /* Errors detected */
  242 
  243 /* ext2 file system block group descriptor */
  244 
  245 struct ext2_gd {
  246         uint32_t ext2bgd_b_bitmap;      /* blocks bitmap block */
  247         uint32_t ext2bgd_i_bitmap;      /* inodes bitmap block */
  248         uint32_t ext2bgd_i_tables;      /* inodes table block  */
  249         uint16_t ext2bgd_nbfree;        /* number of free blocks */
  250         uint16_t ext2bgd_nifree;        /* number of free inodes */
  251         uint16_t ext2bgd_ndirs;         /* number of directories */
  252         uint16_t ext4bgd_flags;         /* block group flags */
  253         uint32_t ext4bgd_x_bitmap;      /* snapshot exclusion bitmap loc. */
  254         uint16_t ext4bgd_b_bmap_csum;   /* block bitmap checksum */
  255         uint16_t ext4bgd_i_bmap_csum;   /* inode bitmap checksum */
  256         uint16_t ext4bgd_i_unused;      /* unused inode count */
  257         uint16_t ext4bgd_csum;          /* group descriptor checksum */
  258 };
  259 
  260 
  261 /* EXT2FS metadatas are stored in little-endian byte order. These macros
  262  * helps reading these metadatas
  263  */
  264 
  265 #define e2fs_cgload(old, new, size) memcpy((new), (old), (size));
  266 #define e2fs_cgsave(old, new, size) memcpy((new), (old), (size));
  267 
  268 /*
  269  * Macro-instructions used to manage several block sizes
  270  */
  271 #define EXT2_MAX_BLOCK_SIZE             4096
  272 #define EXT2_MIN_BLOCK_LOG_SIZE           10
  273 #define EXT2_BLOCK_SIZE(s)              ((s)->e2fs_bsize)
  274 #define EXT2_ADDR_PER_BLOCK(s)          (EXT2_BLOCK_SIZE(s) / sizeof(uint32_t))
  275 #define EXT2_INODE_SIZE(s)              (EXT2_SB(s)->e2fs_isize)
  276 
  277 /*
  278  * Macro-instructions used to manage fragments
  279  */
  280 #define EXT2_MIN_FRAG_SIZE              1024
  281 #define EXT2_MAX_FRAG_SIZE              4096
  282 #define EXT2_MIN_FRAG_LOG_SIZE            10
  283 #define EXT2_FRAG_SIZE(s)               (EXT2_SB(s)->e2fs_fsize)
  284 #define EXT2_FRAGS_PER_BLOCK(s)         (EXT2_SB(s)->e2fs_fpb)
  285 
  286 /*
  287  * Macro-instructions used to manage group descriptors
  288  */
  289 #define EXT2_BLOCKS_PER_GROUP(s)        (EXT2_SB(s)->e2fs_bpg)
  290 
  291 #endif  /* !_FS_EXT2FS_EXT2FS_H_ */

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