lib/ext2fs/initialize.c

   1 /*
   2  * initialize.c --- initialize a filesystem handle given superblock
   3  *      parameters.  Used by mke2fs when initializing a filesystem.
   4  *
   5  * Copyright (C) 1994, 1995, 1996 Theodore Ts'o.
   6  *
   7  * %Begin-Header%
   8  * This file may be redistributed under the terms of the GNU Public
   9  * License.
  10  * %End-Header%
  11  */
  12
  13 #include <stdio.h>
  14 #include <string.h>
  15 #include <unistd.h>
  16 #include <stdlib.h>
  17 #include <fcntl.h>
  18 #include <time.h>
  19 #include <sys/stat.h>
  20 #include <sys/types.h>
  21 #if HAVE_ERRNO_H
  22 #include <errno.h>
  23 #endif
  24
  25 #include <linux/ext2_fs.h>
  26
  27 #include "ext2fs.h"
  28
  29 #if  defined(__linux__)    &&   defined(EXT2_OS_LINUX)
  30 #define CREATOR_OS EXT2_OS_LINUX
  31 #elif defined(__gnu__)     &&   defined(EXT2_OS_HURD)
  32 #define CREATOR_OS EXT2_OS_HURD
  33 #elif defined(__FreeBSD__) &&   defined(EXT2_OS_FREEBSD)
  34 #define CREATOR_OS EXT2_OS_FREEBSD
  35 #elif defined(LITES)       &&   defined(EXT2_OS_LITES)
  36 #define CREATOR_OS EXT2_OS_LITES
  37 #else
  38 #define CREATOR_OS EXT2_OS_LINUX /* by default */
  39 #endif
  40
  41 /*
  42  * Note we override the kernel include file's idea of what the default
  43  * check interval (never) should be.  It's a good idea to check at
  44  * least *occasionally*, specially since servers will never rarely get
  45  * to reboot, since Linux is so robust these days.  :-)
  46  *
  47  * 180 days (six months) seems like a good value.
  48  */
  49 #ifdef EXT2_DFL_CHECKINTERVAL
  50 #undef EXT2_DFL_CHECKINTERVAL
  51 #endif
  52 #define EXT2_DFL_CHECKINTERVAL (86400 * 180)
  53
  54 errcode_t ext2fs_initialize(const char *name, int flags,
  55                             struct ext2_super_block *param,
  56                             io_manager manager, ext2_filsys *ret_fs)
  57 {
  58         ext2_filsys     fs;
  59         errcode_t       retval;
  60         struct ext2_super_block *super;
  61         int             frags_per_block;
  62         int             rem;
  63         int             overhead = 0;
  64         blk_t           group_block;
  65         int             i, j;
  66         int             numblocks;
  67         char            *buf;
  68
  69         if (!param || !param->s_blocks_count)
  70                 return EINVAL;
  71
  72         fs = (ext2_filsys) malloc(sizeof(struct struct_ext2_filsys));
  73         if (!fs)
  74                 return ENOMEM;
  75
  76         memset(fs, 0, sizeof(struct struct_ext2_filsys));
  77         fs->magic = EXT2_ET_MAGIC_EXT2FS_FILSYS;
  78         fs->flags = flags | EXT2_FLAG_RW | ext2fs_native_flag();
  79         retval = manager->open(name, IO_FLAG_RW, &fs->io);
  80         if (retval)
  81                 goto cleanup;
  82         fs->device_name = malloc(strlen(name)+1);
  83         if (!fs->device_name) {
  84                 retval = ENOMEM;
  85                 goto cleanup;
  86         }
  87         strcpy(fs->device_name, name);
  88         fs->super = super = malloc(SUPERBLOCK_SIZE);
  89         if (!super) {
  90                 retval = ENOMEM;
  91                 goto cleanup;
  92         }
  93         memset(super, 0, SUPERBLOCK_SIZE);
  94
  95 #define set_field(field, default) (super->field = param->field ? \
  96                                    param->field : (default))
  97
  98         super->s_magic = EXT2_SUPER_MAGIC;
  99         super->s_state = EXT2_VALID_FS;
 100
 101         set_field(s_log_block_size, 0); /* default blocksize: 1024 bytes */
 102         set_field(s_log_frag_size, 0); /* default fragsize: 1024 bytes */
 103         set_field(s_first_data_block, super->s_log_block_size ? 0 : 1);
 104         set_field(s_max_mnt_count, EXT2_DFL_MAX_MNT_COUNT);
 105         set_field(s_errors, EXT2_ERRORS_DEFAULT);
 106
 107
 108 #ifdef EXT2_DYNAMIC_REV
 109         set_field(s_rev_level, EXT2_GOOD_OLD_REV);
 110         if (super->s_rev_level >= EXT2_DYNAMIC_REV) {
 111                 set_field(s_first_ino, EXT2_GOOD_OLD_FIRST_INO);
 112                 set_field(s_inode_size, EXT2_GOOD_OLD_INODE_SIZE);
 113         }
 114 #endif
 115
 116         set_field(s_checkinterval, EXT2_DFL_CHECKINTERVAL);
 117         super->s_lastcheck = time(NULL);
 118
 119         super->s_creator_os = CREATOR_OS;
 120
 121         fs->blocksize = EXT2_BLOCK_SIZE(super);
 122         fs->fragsize = EXT2_FRAG_SIZE(super);
 123         frags_per_block = fs->blocksize / fs->fragsize;
 124
 125         set_field(s_blocks_per_group, 8192); /* default: 8192 blocks/group */
 126         super->s_frags_per_group = super->s_blocks_per_group * frags_per_block;
 127
 128         super->s_blocks_count = param->s_blocks_count;
 129         super->s_r_blocks_count = param->s_r_blocks_count;
 130         if (super->s_r_blocks_count >= param->s_blocks_count) {
 131                 retval = EINVAL;
 132                 goto cleanup;
 133         }
 134
 135 retry:
 136         fs->group_desc_count = (super->s_blocks_count -
 137                                 super->s_first_data_block +
 138                                 EXT2_BLOCKS_PER_GROUP(super) - 1)
 139                 / EXT2_BLOCKS_PER_GROUP(super);
 140         if (fs->group_desc_count == 0)
 141                 return EXT2_ET_TOOSMALL;
 142         fs->desc_blocks = (fs->group_desc_count +
 143                            EXT2_DESC_PER_BLOCK(super) - 1)
 144                 / EXT2_DESC_PER_BLOCK(super);
 145
 146         set_field(s_inodes_count, (super->s_blocks_count*fs->blocksize)/4096);
 147
 148         /*
 149          * There should be at least as many inodes as the user
 150          * requested.  Figure out how many inodes per group that
 151          * should be.  But make sure that we don't allocate more than
 152          * one bitmap's worth of inodes
 153          */
 154         super->s_inodes_per_group = (super->s_inodes_count +
 155                                      fs->group_desc_count - 1) /
 156                                              fs->group_desc_count;
 157         if (super->s_inodes_per_group > fs->blocksize*8)
 158                 super->s_inodes_per_group = fs->blocksize*8;
 159
 160         /*
 161          * Make sure the number of inodes per group completely fills
 162          * the inode table blocks in the descriptor.  If not, add some
 163          * additional inodes/group.  Waste not, want not...
 164          */
 165         fs->inode_blocks_per_group = (((super->s_inodes_per_group *
 166                                         EXT2_INODE_SIZE(super)) +
 167                                        EXT2_BLOCK_SIZE(super) - 1) /
 168                                       EXT2_BLOCK_SIZE(super));
 169         super->s_inodes_per_group = ((fs->inode_blocks_per_group *
 170                                       EXT2_BLOCK_SIZE(super)) /
 171                                      EXT2_INODE_SIZE(super));
 172         /*
 173          * Finally, make sure the number of inodes per group is a
 174          * multiple of 8.  This is needed to simplify the bitmap
 175          * splicing code.
 176          */
 177         super->s_inodes_per_group &= ~7;
 178         fs->inode_blocks_per_group = (((super->s_inodes_per_group *
 179                                         EXT2_INODE_SIZE(super)) +
 180                                        EXT2_BLOCK_SIZE(super) - 1) /
 181                                       EXT2_BLOCK_SIZE(super));
 182
 183         /*
 184          * adjust inode count to reflect the adjusted inodes_per_group
 185          */
 186         super->s_inodes_count = super->s_inodes_per_group *
 187                 fs->group_desc_count;
 188         super->s_free_inodes_count = super->s_inodes_count;
 189
 190         /*
 191          * Overhead is the number of bookkeeping blocks per group.  It
 192          * includes the superblock backup, the group descriptor
 193          * backups, the inode bitmap, the block bitmap, and the inode
 194          * table.
 195          */
 196         overhead = 3 + fs->desc_blocks + fs->inode_blocks_per_group;
 197         super->s_free_blocks_count = super->s_blocks_count -
 198                 super->s_first_data_block - (overhead*fs->group_desc_count);
 199
 200         /*
 201          * See if the last group is big enough to support the
 202          * necessary data structures.  If not, we need to get rid of
 203          * it.
 204          */
 205         rem = (super->s_blocks_count - super->s_first_data_block) %
 206                 super->s_blocks_per_group;
 207         if ((fs->group_desc_count == 1) && rem && (rem < overhead))
 208                 return EXT2_ET_TOOSMALL;
 209         if (rem && (rem < overhead+50)) {
 210                 super->s_blocks_count -= rem;
 211                 goto retry;
 212         }
 213
 214         /*
 215          * At this point we know how big the filesystem will be.  So
 216          * we can do any and all allocations that depend on the block
 217          * count.
 218          */
 219
 220         buf = malloc(strlen(fs->device_name) + 80);
 221         if (!buf) {
 222                 retval = ENOMEM;
 223                 goto cleanup;
 224         }
 225
 226         sprintf(buf, "block bitmap for %s", fs->device_name);
 227         retval = ext2fs_allocate_block_bitmap(fs, buf, &fs->block_map);
 228         if (retval)
 229                 goto cleanup;
 230
 231         sprintf(buf, "inode bitmap for %s", fs->device_name);
 232         retval = ext2fs_allocate_inode_bitmap(fs, buf, &fs->inode_map);
 233         if (retval)
 234                 goto cleanup;
 235
 236         free(buf);
 237
 238         fs->group_desc = malloc(fs->desc_blocks * fs->blocksize);
 239         if (!fs->group_desc) {
 240                 retval = ENOMEM;
 241                 goto cleanup;
 242         }
 243         memset(fs->group_desc, 0, fs->desc_blocks * fs->blocksize);
 244
 245         /*
 246          * Reserve the superblock and group descriptors for each
 247          * group, and fill in the correct group statistics for group.
 248          * Note that although the block bitmap, inode bitmap, and
 249          * inode table have not been allocated (and in fact won't be
 250          * by this routine), they are accounted for nevertheless.
 251          */
 252         group_block = super->s_first_data_block;
 253         for (i = 0; i < fs->group_desc_count; i++) {
 254                 for (j=0; j < fs->desc_blocks+1; j++)
 255                         ext2fs_mark_block_bitmap(fs->block_map,
 256                                                  group_block + j);
 257
 258                 if (i == fs->group_desc_count-1) {
 259                         numblocks = (fs->super->s_blocks_count -
 260                                      fs->super->s_first_data_block) %
 261                                              fs->super->s_blocks_per_group;
 262                         if (!numblocks)
 263                                 numblocks = fs->super->s_blocks_per_group;
 264                 } else
 265                         numblocks = fs->super->s_blocks_per_group;
 266                 numblocks -= 3 + fs->desc_blocks + fs->inode_blocks_per_group;
 267
 268                 fs->group_desc[i].bg_free_blocks_count = numblocks;
 269                 fs->group_desc[i].bg_free_inodes_count =
 270                         fs->super->s_inodes_per_group;
 271                 fs->group_desc[i].bg_used_dirs_count = 0;
 272
 273                 group_block += super->s_blocks_per_group;
 274         }
 275
 276         ext2fs_mark_super_dirty(fs);
 277         ext2fs_mark_bb_dirty(fs);
 278         ext2fs_mark_ib_dirty(fs);
 279
 280         io_channel_set_blksize(fs->io, fs->blocksize);
 281
 282         *ret_fs = fs;
 283         return 0;
 284 cleanup:
 285         ext2fs_free(fs);
 286         return retval;
 287 }
 288
 289
 290