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  * $FreeBSD$
    8  */
    9 /*-
   10  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
   11  *
   12  * Copyright (c) 2009 Aditya Sarawgi
   13  * All rights reserved.
   14  *
   15  * Redistribution and use in source and binary forms, with or without
   16  * modification, are permitted provided that the following conditions
   17  * are met:
   18  * 1. Redistributions of source code must retain the above copyright
   19  *    notice, this list of conditions and the following disclaimer.
   20  * 2. Redistributions in binary form must reproduce the above copyright
   21  *    notice, this list of conditions and the following disclaimer in the
   22  *    documentation and/or other materials provided with the distribution.
   23  *
   24  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   34  * SUCH DAMAGE.
   35  *
   36  *
   37  */
   38 
   39 #ifndef _FS_EXT2FS_EXT2FS_H_
   40 #define _FS_EXT2FS_EXT2FS_H_
   41 
   42 #include <sys/types.h>
   43 
   44 /*
   45  * Super block for an ext2fs file system.
   46  */
   47 struct ext2fs {
   48         uint32_t  e2fs_icount;          /* Inode count */
   49         uint32_t  e2fs_bcount;          /* blocks count */
   50         uint32_t  e2fs_rbcount;         /* reserved blocks count */
   51         uint32_t  e2fs_fbcount;         /* free blocks count */
   52         uint32_t  e2fs_ficount;         /* free inodes count */
   53         uint32_t  e2fs_first_dblock;    /* first data block */
   54         uint32_t  e2fs_log_bsize;       /* block size = 1024*(2^e2fs_log_bsize) */
   55         uint32_t  e2fs_log_fsize;       /* fragment size */
   56         uint32_t  e2fs_bpg;             /* blocks per group */
   57         uint32_t  e2fs_fpg;             /* frags per group */
   58         uint32_t  e2fs_ipg;             /* inodes per group */
   59         uint32_t  e2fs_mtime;           /* mount time */
   60         uint32_t  e2fs_wtime;           /* write time */
   61         uint16_t  e2fs_mnt_count;       /* mount count */
   62         uint16_t  e2fs_max_mnt_count;   /* max mount count */
   63         uint16_t  e2fs_magic;           /* magic number */
   64         uint16_t  e2fs_state;           /* file system state */
   65         uint16_t  e2fs_beh;             /* behavior on errors */
   66         uint16_t  e2fs_minrev;          /* minor revision level */
   67         uint32_t  e2fs_lastfsck;        /* time of last fsck */
   68         uint32_t  e2fs_fsckintv;        /* max time between fscks */
   69         uint32_t  e2fs_creator;         /* creator OS */
   70         uint32_t  e2fs_rev;             /* revision level */
   71         uint16_t  e2fs_ruid;            /* default uid for reserved blocks */
   72         uint16_t  e2fs_rgid;            /* default gid for reserved blocks */
   73         /* EXT2_DYNAMIC_REV superblocks */
   74         uint32_t  e2fs_first_ino;       /* first non-reserved inode */
   75         uint16_t  e2fs_inode_size;      /* size of inode structure */
   76         uint16_t  e2fs_block_group_nr;  /* block grp number of this sblk*/
   77         uint32_t  e2fs_features_compat; /* compatible feature set */
   78         uint32_t  e2fs_features_incompat; /* incompatible feature set */
   79         uint32_t  e2fs_features_rocompat; /* RO-compatible feature set */
   80         uint8_t   e2fs_uuid[16];        /* 128-bit uuid for volume */
   81         char      e2fs_vname[16];       /* volume name */
   82         char      e2fs_fsmnt[64];       /* name mounted on */
   83         uint32_t  e2fs_algo;            /* For compression */
   84         uint8_t   e2fs_prealloc;        /* # of blocks for old prealloc */
   85         uint8_t   e2fs_dir_prealloc;    /* # of blocks for old prealloc dirs */
   86         uint16_t  e2fs_reserved_ngdb;   /* # of reserved gd blocks for resize */
   87         char      e3fs_journal_uuid[16]; /* uuid of journal superblock */
   88         uint32_t  e3fs_journal_inum;    /* inode number of journal file */
   89         uint32_t  e3fs_journal_dev;     /* device number of journal file */
   90         uint32_t  e3fs_last_orphan;     /* start of list of inodes to delete */
   91         uint32_t  e3fs_hash_seed[4];    /* HTREE hash seed */
   92         char      e3fs_def_hash_version;/* Default hash version to use */
   93         char      e3fs_jnl_backup_type;
   94         uint16_t  e3fs_desc_size;       /* size of group descriptor */
   95         uint32_t  e3fs_default_mount_opts;
   96         uint32_t  e3fs_first_meta_bg;   /* First metablock block group */
   97         uint32_t  e3fs_mkfs_time;       /* when the fs was created */
   98         uint32_t  e3fs_jnl_blks[17];    /* backup of the journal inode */
   99         uint32_t  e4fs_bcount_hi;       /* high bits of blocks count */
  100         uint32_t  e4fs_rbcount_hi;      /* high bits of reserved blocks count */
  101         uint32_t  e4fs_fbcount_hi;      /* high bits of free blocks count */
  102         uint16_t  e4fs_min_extra_isize; /* all inodes have some bytes */
  103         uint16_t  e4fs_want_extra_isize;/* inodes must reserve some bytes */
  104         uint32_t  e4fs_flags;           /* miscellaneous flags */
  105         uint16_t  e4fs_raid_stride;     /* RAID stride */
  106         uint16_t  e4fs_mmpintv;         /* seconds to wait in MMP checking */
  107         uint64_t  e4fs_mmpblk;          /* block for multi-mount protection */
  108         uint32_t  e4fs_raid_stripe_wid; /* blocks on data disks (N * stride) */
  109         uint8_t   e4fs_log_gpf;         /* FLEX_BG group size */
  110         uint8_t   e4fs_chksum_type;     /* metadata checksum algorithm used */
  111         uint8_t   e4fs_encrypt;         /* versioning level for encryption */
  112         uint8_t   e4fs_reserved_pad;
  113         uint64_t  e4fs_kbytes_written;  /* number of lifetime kilobytes */
  114         uint32_t  e4fs_snapinum;        /* inode number of active snapshot */
  115         uint32_t  e4fs_snapid;          /* sequential ID of active snapshot */
  116         uint64_t  e4fs_snaprbcount;     /* reserved blocks for active snapshot */
  117         uint32_t  e4fs_snaplist;        /* inode number for on-disk snapshot */
  118         uint32_t  e4fs_errcount;        /* number of file system errors */
  119         uint32_t  e4fs_first_errtime;   /* first time an error happened */
  120         uint32_t  e4fs_first_errino;    /* inode involved in first error */
  121         uint64_t  e4fs_first_errblk;    /* block involved of first error */
  122         uint8_t   e4fs_first_errfunc[32];/* function where error happened */
  123         uint32_t  e4fs_first_errline;   /* line number where error happened */
  124         uint32_t  e4fs_last_errtime;    /* most recent time of an error */
  125         uint32_t  e4fs_last_errino;     /* inode involved in last error */
  126         uint32_t  e4fs_last_errline;    /* line number where error happened */
  127         uint64_t  e4fs_last_errblk;     /* block involved of last error */
  128         uint8_t   e4fs_last_errfunc[32]; /* function where error happened */
  129         uint8_t   e4fs_mount_opts[64];
  130         uint32_t  e4fs_usrquota_inum;   /* inode for tracking user quota */
  131         uint32_t  e4fs_grpquota_inum;   /* inode for tracking group quota */
  132         uint32_t  e4fs_overhead_clusters;/* overhead blocks/clusters */
  133         uint32_t  e4fs_backup_bgs[2];   /* groups with sparse_super2 SBs */
  134         uint8_t   e4fs_encrypt_algos[4];/* encryption algorithms in use */
  135         uint8_t   e4fs_encrypt_pw_salt[16];/* salt used for string2key */
  136         uint32_t  e4fs_lpf_ino;         /* location of the lost+found inode */
  137         uint32_t  e4fs_proj_quota_inum; /* inode for tracking project quota */
  138         uint32_t  e4fs_chksum_seed;     /* checksum seed */
  139         uint32_t  e4fs_reserved[98];    /* padding to the end of the block */
  140         uint32_t  e4fs_sbchksum;        /* superblock checksum */
  141 };
  142 
  143 /*
  144  * The path name on which the file system is mounted is maintained
  145  * in fs_fsmnt. MAXMNTLEN defines the amount of space allocated in
  146  * the super block for this name.
  147  */
  148 #define MAXMNTLEN 512
  149 
  150 /*
  151  * In-Memory Superblock
  152  */
  153 
  154 struct m_ext2fs {
  155         struct ext2fs * e2fs;
  156         char     e2fs_fsmnt[MAXMNTLEN];/* name mounted on */
  157         char     e2fs_ronly;      /* mounted read-only flag */
  158         char     e2fs_fmod;       /* super block modified flag */
  159         uint64_t e2fs_bcount;     /* blocks count */
  160         uint64_t e2fs_rbcount;    /* reserved blocks count */
  161         uint64_t e2fs_fbcount;    /* free blocks count */
  162         uint32_t e2fs_bsize;      /* Block size */
  163         uint32_t e2fs_bshift;     /* calc of logical block no */
  164         uint32_t e2fs_bpg;        /* Number of blocks per group */
  165         int64_t  e2fs_qbmask;     /* = s_blocksize -1 */
  166         uint32_t e2fs_fsbtodb;    /* Shift to get disk block */
  167         uint32_t e2fs_ipg;        /* Number of inodes per group */
  168         uint32_t e2fs_ipb;        /* Number of inodes per block */
  169         uint32_t e2fs_itpg;       /* Number of inode table per group */
  170         uint32_t e2fs_fsize;      /* Size of fragments per block */
  171         uint32_t e2fs_fpb;        /* Number of fragments per block */
  172         uint32_t e2fs_fpg;        /* Number of fragments per group */
  173         uint32_t e2fs_gdbcount;   /* Number of group descriptors */
  174         uint32_t e2fs_gcount;     /* Number of groups */
  175         uint32_t e2fs_isize;      /* Size of inode */
  176         uint32_t e2fs_total_dir;  /* Total number of directories */
  177         uint8_t *e2fs_contigdirs; /* (u) # of contig. allocated dirs */
  178         char     e2fs_wasvalid;   /* valid at mount time */
  179         off_t    e2fs_maxfilesize;
  180         struct   ext2_gd *e2fs_gd; /* Group Descriptors */
  181         int32_t  e2fs_contigsumsize;    /* size of cluster summary array */
  182         int32_t *e2fs_maxcluster;       /* max cluster in each cyl group */
  183         struct   csum *e2fs_clustersum; /* cluster summary in each cyl group */
  184         int32_t  e2fs_uhash;      /* 3 if hash should be signed, 0 if not */
  185         uint32_t e2fs_csum_seed;  /* sb checksum seed */
  186 };
  187 
  188 /* cluster summary information */
  189 
  190 struct csum {
  191         int8_t   cs_init; /* cluster summary has been initialized */
  192         int32_t *cs_sum;  /* cluster summary array */
  193 };
  194 
  195 /*
  196  * The second extended file system magic number
  197  */
  198 #define E2FS_MAGIC              0xEF53
  199 
  200 /*
  201  * Revision levels
  202  */
  203 #define E2FS_REV0               0       /* The good old (original) format */
  204 #define E2FS_REV1               1       /* V2 format w/ dynamic inode sizes */
  205 
  206 #define E2FS_REV0_INODE_SIZE 128
  207 
  208 /*
  209  * Metadata checksum algorithm codes
  210  */
  211 #define EXT4_CRC32C_CHKSUM              1
  212 
  213 /*
  214  * compatible/incompatible features
  215  */
  216 #define EXT2F_COMPAT_PREALLOC           0x0001
  217 #define EXT2F_COMPAT_IMAGIC_INODES      0x0002
  218 #define EXT2F_COMPAT_HASJOURNAL         0x0004
  219 #define EXT2F_COMPAT_EXT_ATTR           0x0008
  220 #define EXT2F_COMPAT_RESIZE             0x0010
  221 #define EXT2F_COMPAT_DIRHASHINDEX       0x0020
  222 #define EXT2F_COMPAT_LAZY_BG            0x0040
  223 #define EXT2F_COMPAT_EXCLUDE_BITMAP     0x0100
  224 #define EXT2F_COMPAT_SPARSESUPER2       0x0200
  225 
  226 #define EXT2F_ROCOMPAT_SPARSESUPER      0x0001
  227 #define EXT2F_ROCOMPAT_LARGEFILE        0x0002
  228 #define EXT2F_ROCOMPAT_BTREE_DIR        0x0004
  229 #define EXT2F_ROCOMPAT_HUGE_FILE        0x0008
  230 #define EXT2F_ROCOMPAT_GDT_CSUM         0x0010
  231 #define EXT2F_ROCOMPAT_DIR_NLINK        0x0020
  232 #define EXT2F_ROCOMPAT_EXTRA_ISIZE      0x0040
  233 #define EXT2F_ROCOMPAT_HAS_SNAPSHOT     0x0080
  234 #define EXT2F_ROCOMPAT_QUOTA            0x0100
  235 #define EXT2F_ROCOMPAT_BIGALLOC         0x0200
  236 #define EXT2F_ROCOMPAT_METADATA_CKSUM   0x0400
  237 #define EXT2F_ROCOMPAT_REPLICA          0x0800
  238 #define EXT2F_ROCOMPAT_READONLY         0x1000
  239 #define EXT2F_ROCOMPAT_PROJECT          0x2000
  240 
  241 #define EXT2F_INCOMPAT_COMP             0x0001
  242 #define EXT2F_INCOMPAT_FTYPE            0x0002
  243 #define EXT2F_INCOMPAT_RECOVER          0x0004
  244 #define EXT2F_INCOMPAT_JOURNAL_DEV      0x0008
  245 #define EXT2F_INCOMPAT_META_BG          0x0010
  246 #define EXT2F_INCOMPAT_EXTENTS          0x0040
  247 #define EXT2F_INCOMPAT_64BIT            0x0080
  248 #define EXT2F_INCOMPAT_MMP              0x0100
  249 #define EXT2F_INCOMPAT_FLEX_BG          0x0200
  250 #define EXT2F_INCOMPAT_EA_INODE         0x0400
  251 #define EXT2F_INCOMPAT_DIRDATA          0x1000
  252 #define EXT2F_INCOMPAT_CSUM_SEED        0x2000
  253 #define EXT2F_INCOMPAT_LARGEDIR         0x4000
  254 #define EXT2F_INCOMPAT_INLINE_DATA      0x8000
  255 #define EXT2F_INCOMPAT_ENCRYPT          0x10000
  256 
  257 struct ext2_feature
  258 {
  259         int mask;
  260         const char *name;
  261 };
  262 
  263 static const struct ext2_feature compat[] = {
  264         { EXT2F_COMPAT_PREALLOC,       "dir_prealloc"    },
  265         { EXT2F_COMPAT_IMAGIC_INODES,  "imagic_inodes"   },
  266         { EXT2F_COMPAT_HASJOURNAL,     "has_journal"     },
  267         { EXT2F_COMPAT_EXT_ATTR,       "ext_attr"        },
  268         { EXT2F_COMPAT_RESIZE,         "resize_inode"    },
  269         { EXT2F_COMPAT_DIRHASHINDEX,   "dir_index"       },
  270         { EXT2F_COMPAT_EXCLUDE_BITMAP, "snapshot_bitmap" },
  271         { EXT2F_COMPAT_SPARSESUPER2,   "sparse_super2"   }
  272 };
  273 
  274 static const struct ext2_feature ro_compat[] = {
  275         { EXT2F_ROCOMPAT_SPARSESUPER,    "sparse_super"  },
  276         { EXT2F_ROCOMPAT_LARGEFILE,      "large_file"    },
  277         { EXT2F_ROCOMPAT_BTREE_DIR,      "btree_dir"     },
  278         { EXT2F_ROCOMPAT_HUGE_FILE,      "huge_file"     },
  279         { EXT2F_ROCOMPAT_GDT_CSUM,       "uninit_groups" },
  280         { EXT2F_ROCOMPAT_DIR_NLINK,      "dir_nlink"     },
  281         { EXT2F_ROCOMPAT_EXTRA_ISIZE,    "extra_isize"   },
  282         { EXT2F_ROCOMPAT_HAS_SNAPSHOT,   "snapshot"      },
  283         { EXT2F_ROCOMPAT_QUOTA,          "quota"         },
  284         { EXT2F_ROCOMPAT_BIGALLOC,       "bigalloc"      },
  285         { EXT2F_ROCOMPAT_METADATA_CKSUM, "metadata_csum" },
  286         { EXT2F_ROCOMPAT_REPLICA,        "replica"       },
  287         { EXT2F_ROCOMPAT_READONLY,       "ro"            },
  288         { EXT2F_ROCOMPAT_PROJECT,        "project"       }
  289 };
  290 
  291 static const struct ext2_feature incompat[] = {
  292         { EXT2F_INCOMPAT_COMP,        "compression"        },
  293         { EXT2F_INCOMPAT_FTYPE,       "filetype"           },
  294         { EXT2F_INCOMPAT_RECOVER,     "needs_recovery"     },
  295         { EXT2F_INCOMPAT_JOURNAL_DEV, "journal_dev"        },
  296         { EXT2F_INCOMPAT_META_BG,     "meta_bg"            },
  297         { EXT2F_INCOMPAT_EXTENTS,     "extents"            },
  298         { EXT2F_INCOMPAT_64BIT,       "64bit"              },
  299         { EXT2F_INCOMPAT_MMP,         "mmp"                },
  300         { EXT2F_INCOMPAT_FLEX_BG,     "flex_bg"            },
  301         { EXT2F_INCOMPAT_EA_INODE,    "ea_inode"           },
  302         { EXT2F_INCOMPAT_DIRDATA,     "dirdata"            },
  303         { EXT2F_INCOMPAT_CSUM_SEED,   "metadata_csum_seed" },
  304         { EXT2F_INCOMPAT_LARGEDIR,    "large_dir"          },
  305         { EXT2F_INCOMPAT_INLINE_DATA, "inline_data"        },
  306         { EXT2F_INCOMPAT_ENCRYPT,     "encrypt"            }
  307 };
  308 
  309 /*
  310  * Features supported in this implementation
  311  *
  312  * We support the following REV1 features:
  313  * - EXT2F_ROCOMPAT_SPARSESUPER
  314  * - EXT2F_ROCOMPAT_LARGEFILE
  315  * - EXT2F_ROCOMPAT_EXTRA_ISIZE
  316  * - EXT2F_INCOMPAT_FTYPE
  317  *
  318  * We partially (read-only) support the following EXT4 features:
  319  * - EXT2F_ROCOMPAT_HUGE_FILE
  320  * - EXT2F_INCOMPAT_EXTENTS
  321  *
  322  */
  323 #define EXT2F_COMPAT_SUPP               EXT2F_COMPAT_DIRHASHINDEX
  324 #define EXT2F_ROCOMPAT_SUPP             (EXT2F_ROCOMPAT_SPARSESUPER | \
  325                                          EXT2F_ROCOMPAT_LARGEFILE | \
  326                                          EXT2F_ROCOMPAT_GDT_CSUM | \
  327                                          EXT2F_ROCOMPAT_METADATA_CKSUM | \
  328                                          EXT2F_ROCOMPAT_DIR_NLINK | \
  329                                          EXT2F_ROCOMPAT_HUGE_FILE | \
  330                                          EXT2F_ROCOMPAT_EXTRA_ISIZE)
  331 #define EXT2F_INCOMPAT_SUPP             (EXT2F_INCOMPAT_FTYPE | \
  332                                          EXT2F_INCOMPAT_META_BG | \
  333                                          EXT2F_INCOMPAT_EXTENTS | \
  334                                          EXT2F_INCOMPAT_64BIT | \
  335                                          EXT2F_INCOMPAT_FLEX_BG | \
  336                                          EXT2F_INCOMPAT_CSUM_SEED)
  337 
  338 /* Assume that user mode programs are passing in an ext2fs superblock, not
  339  * a kernel struct super_block.  This will allow us to call the feature-test
  340  * macros from user land. */
  341 #define EXT2_SB(sb)     (sb)
  342 
  343 /*
  344  * Feature set definitions
  345  */
  346 #define EXT2_HAS_COMPAT_FEATURE(sb,mask)                        \
  347         ( EXT2_SB(sb)->e2fs->e2fs_features_compat & htole32(mask) )
  348 #define EXT2_HAS_RO_COMPAT_FEATURE(sb,mask)                     \
  349         ( EXT2_SB(sb)->e2fs->e2fs_features_rocompat & htole32(mask) )
  350 #define EXT2_HAS_INCOMPAT_FEATURE(sb,mask)                      \
  351         ( EXT2_SB(sb)->e2fs->e2fs_features_incompat & htole32(mask) )
  352 
  353 /*
  354  * File clean flags
  355  */
  356 #define E2FS_ISCLEAN                    0x0001  /* Unmounted cleanly */
  357 #define E2FS_ERRORS                     0x0002  /* Errors detected */
  358 
  359 /*
  360  * Filesystem miscellaneous flags
  361  */
  362 #define E2FS_SIGNED_HASH        0x0001
  363 #define E2FS_UNSIGNED_HASH      0x0002
  364 
  365 #define EXT2_BG_INODE_UNINIT    0x0001  /* Inode table/bitmap not in use */
  366 #define EXT2_BG_BLOCK_UNINIT    0x0002  /* Block bitmap not in use */
  367 #define EXT2_BG_INODE_ZEROED    0x0004  /* On-disk itable initialized to zero */
  368 
  369 /* ext2 file system block group descriptor */
  370 
  371 struct ext2_gd {
  372         uint32_t ext2bgd_b_bitmap;      /* blocks bitmap block */
  373         uint32_t ext2bgd_i_bitmap;      /* inodes bitmap block */
  374         uint32_t ext2bgd_i_tables;      /* inodes table block  */
  375         uint16_t ext2bgd_nbfree;        /* number of free blocks */
  376         uint16_t ext2bgd_nifree;        /* number of free inodes */
  377         uint16_t ext2bgd_ndirs;         /* number of directories */
  378         uint16_t ext4bgd_flags;         /* block group flags */
  379         uint32_t ext4bgd_x_bitmap;      /* snapshot exclusion bitmap loc. */
  380         uint16_t ext4bgd_b_bmap_csum;   /* block bitmap checksum */
  381         uint16_t ext4bgd_i_bmap_csum;   /* inode bitmap checksum */
  382         uint16_t ext4bgd_i_unused;      /* unused inode count */
  383         uint16_t ext4bgd_csum;          /* group descriptor checksum */
  384         uint32_t ext4bgd_b_bitmap_hi;   /* high bits of blocks bitmap block */
  385         uint32_t ext4bgd_i_bitmap_hi;   /* high bits of inodes bitmap block */
  386         uint32_t ext4bgd_i_tables_hi;   /* high bits of inodes table block */
  387         uint16_t ext4bgd_nbfree_hi;     /* high bits of number of free blocks */
  388         uint16_t ext4bgd_nifree_hi;     /* high bits of number of free inodes */
  389         uint16_t ext4bgd_ndirs_hi;      /* high bits of number of directories */
  390         uint16_t ext4bgd_i_unused_hi;   /* high bits of unused inode count */
  391         uint32_t ext4bgd_x_bitmap_hi;   /* high bits of snapshot exclusion */
  392         uint16_t ext4bgd_b_bmap_csum_hi;/* high bits of block bitmap checksum */
  393         uint16_t ext4bgd_i_bmap_csum_hi;/* high bits of inode bitmap checksum */
  394         uint32_t ext4bgd_reserved;
  395 };
  396 
  397 #define E2FS_REV0_GD_SIZE (sizeof(struct ext2_gd) / 2)
  398 #define E2FS_64BIT_GD_SIZE (sizeof(struct ext2_gd))
  399 
  400 /*
  401  * Macro-instructions used to manage several block sizes
  402  */
  403 #define EXT2_MIN_BLOCK_LOG_SIZE           10
  404 #define EXT2_BLOCK_SIZE(s)              ((s)->e2fs_bsize)
  405 #define EXT2_ADDR_PER_BLOCK(s)          (EXT2_BLOCK_SIZE(s) / sizeof(uint32_t))
  406 #define EXT2_INODE_SIZE(s)              (EXT2_SB(s)->e2fs_isize)
  407 
  408 /*
  409  * Macro-instructions used to manage fragments
  410  */
  411 #define EXT2_MIN_FRAG_SIZE              1024
  412 #define EXT2_MIN_FRAG_LOG_SIZE          10
  413 #define EXT2_MAX_FRAG_LOG_SIZE          30
  414 #define EXT2_FRAG_SIZE(s)               (EXT2_SB(s)->e2fs_fsize)
  415 #define EXT2_FRAGS_PER_BLOCK(s)         (EXT2_SB(s)->e2fs_fpb)
  416 
  417 /*
  418  * Macro-instructions used to manage group descriptors
  419  */
  420 #define EXT2_BLOCKS_PER_GROUP(s)        (EXT2_SB(s)->e2fs_bpg)
  421 #define EXT2_DESCS_PER_BLOCK(s)         (EXT2_HAS_INCOMPAT_FEATURE((s), \
  422         EXT2F_INCOMPAT_64BIT) ? ((s)->e2fs_bsize / sizeof(struct ext2_gd)) : \
  423         ((s)->e2fs_bsize / E2FS_REV0_GD_SIZE))
  424 
  425 /*
  426  * Macro-instructions used to manage inodes
  427  */
  428 #define EXT2_FIRST_INO(s)       ((EXT2_SB(s)->e2fs->e2fs_rev == E2FS_REV0) ? \
  429                                  EXT2_FIRSTINO : \
  430                                  EXT2_SB(s)->e2fs->e2fs_first_ino)
  431 
  432 #endif  /* !_FS_EXT2FS_EXT2FS_H_ */

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