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 #if HAVE_UNISTD_H
  16 #include <unistd.h>
  17 #endif
  18 #include <stdlib.h>
  19 #include <fcntl.h>
  20 #include <time.h>
  21 #include <sys/stat.h>
  22 #include <sys/types.h>
  23 #if HAVE_ERRNO_H
  24 #include <errno.h>
  25 #endif
  26
  27 #include <linux/ext2_fs.h>
  28
  29 #include "ext2fs.h"
  30
  31 #if  defined(__linux__)    &&   defined(EXT2_OS_LINUX)
  32 #define CREATOR_OS EXT2_OS_LINUX
  33 #elif defined(__gnu__)     &&   defined(EXT2_OS_HURD)
  34 #define CREATOR_OS EXT2_OS_HURD
  35 #elif defined(__FreeBSD__) &&   defined(EXT2_OS_FREEBSD)
  36 #define CREATOR_OS EXT2_OS_FREEBSD
  37 #elif defined(LITES)       &&   defined(EXT2_OS_LITES)
  38 #define CREATOR_OS EXT2_OS_LITES
  39 #else
  40 #define CREATOR_OS EXT2_OS_LINUX /* by default */
  41 #endif
  42
  43 /*
  44  * Note we override the kernel include file's idea of what the default
  45  * check interval (never) should be.  It's a good idea to check at
  46  * least *occasionally*, specially since servers will never rarely get
  47  * to reboot, since Linux is so robust these days.  :-)
  48  *
  49  * 180 days (six months) seems like a good value.
  50  */
  51 #ifdef EXT2_DFL_CHECKINTERVAL
  52 #undef EXT2_DFL_CHECKINTERVAL
  53 #endif
  54 #define EXT2_DFL_CHECKINTERVAL (86400L * 180L)
  55
  56 errcode_t ext2fs_initialize(const char *name, int flags,
  57                             struct ext2_super_block *param,
  58                             io_manager manager, ext2_filsys *ret_fs)
  59 {
  60         ext2_filsys     fs;
  61         errcode_t       retval;
  62         struct ext2_super_block *super;
  63         int             frags_per_block;
  64         int             rem;
  65         int             overhead = 0;
  66         blk_t           group_block;
  67         int             i, j;
  68         blk_t           numblocks;
  69         char            *buf;
  70
  71         if (!param || !param->s_blocks_count)
  72                 return EINVAL;
  73
  74         fs = (ext2_filsys) malloc(sizeof(struct struct_ext2_filsys));
  75         if (!fs)
  76                 return ENOMEM;
  77
  78         memset(fs, 0, sizeof(struct struct_ext2_filsys));
  79         fs->magic = EXT2_ET_MAGIC_EXT2FS_FILSYS;
  80         fs->flags = flags | EXT2_FLAG_RW | ext2fs_native_flag();
  81         retval = manager->open(name, IO_FLAG_RW, &fs->io);
  82         if (retval)
  83                 goto cleanup;
  84         fs->io->app_data = fs;
  85         fs->device_name = malloc(strlen(name)+1);
  86         if (!fs->device_name) {
  87                 retval = ENOMEM;
  88                 goto cleanup;
  89         }
  90         strcpy(fs->device_name, name);
  91         fs->super = super = malloc(SUPERBLOCK_SIZE);
  92         if (!super) {
  93                 retval = ENOMEM;
  94                 goto cleanup;
  95         }
  96         memset(super, 0, SUPERBLOCK_SIZE);
  97
  98 #define set_field(field, default) (super->field = param->field ? \
  99                                    param->field : (default))
 100
 101         super->s_magic = EXT2_SUPER_MAGIC;
 102         super->s_state = EXT2_VALID_FS;
 103
 104         set_field(s_log_block_size, 0); /* default blocksize: 1024 bytes */
 105         set_field(s_log_frag_size, 0); /* default fragsize: 1024 bytes */
 106         set_field(s_first_data_block, super->s_log_block_size ? 0 : 1);
 107         set_field(s_max_mnt_count, EXT2_DFL_MAX_MNT_COUNT);
 108         set_field(s_errors, EXT2_ERRORS_DEFAULT);
 109 #ifdef EXT2_DYNAMIC_REV
 110         set_field(s_feature_compat, 0);
 111         set_field(s_feature_incompat, 0);
 112         set_field(s_feature_ro_compat, 0);
 113         if (super->s_feature_incompat & ~EXT2_LIB_FEATURE_INCOMPAT_SUPP)
 114                 return EXT2_ET_UNSUPP_FEATURE;
 115         if (super->s_feature_ro_compat & ~EXT2_LIB_FEATURE_RO_COMPAT_SUPP)
 116                 return EXT2_ET_RO_UNSUPP_FEATURE;
 117
 118         set_field(s_rev_level, EXT2_GOOD_OLD_REV);
 119         if (super->s_rev_level >= EXT2_DYNAMIC_REV) {
 120                 set_field(s_first_ino, EXT2_GOOD_OLD_FIRST_INO);
 121                 set_field(s_inode_size, EXT2_GOOD_OLD_INODE_SIZE);
 122         }
 123 #endif
 124
 125         set_field(s_checkinterval, EXT2_DFL_CHECKINTERVAL);
 126         super->s_lastcheck = time(NULL);
 127
 128         super->s_creator_os = CREATOR_OS;
 129
 130         fs->blocksize = EXT2_BLOCK_SIZE(super);
 131         fs->fragsize = EXT2_FRAG_SIZE(super);
 132         frags_per_block = fs->blocksize / fs->fragsize;
 133
 134         /* default: (fs->blocksize*8) blocks/group */
 135         set_field(s_blocks_per_group, fs->blocksize*8);
 136         super->s_frags_per_group = super->s_blocks_per_group * frags_per_block;
 137
 138         super->s_blocks_count = param->s_blocks_count;
 139         super->s_r_blocks_count = param->s_r_blocks_count;
 140         if (super->s_r_blocks_count >= param->s_blocks_count) {
 141                 retval = EINVAL;
 142                 goto cleanup;
 143         }
 144
 145 retry:
 146         fs->group_desc_count = (super->s_blocks_count -
 147                                 super->s_first_data_block +
 148                                 EXT2_BLOCKS_PER_GROUP(super) - 1)
 149                 / EXT2_BLOCKS_PER_GROUP(super);
 150         if (fs->group_desc_count == 0)
 151                 return EXT2_ET_TOOSMALL;
 152         fs->desc_blocks = (fs->group_desc_count +
 153                            EXT2_DESC_PER_BLOCK(super) - 1)
 154                 / EXT2_DESC_PER_BLOCK(super);
 155
 156         set_field(s_inodes_count, (super->s_blocks_count*fs->blocksize)/4096);
 157
 158         /*
 159          * There should be at least as many inodes as the user
 160          * requested.  Figure out how many inodes per group that
 161          * should be.  But make sure that we don't allocate more than
 162          * one bitmap's worth of inodes
 163          */
 164         super->s_inodes_per_group = (super->s_inodes_count +
 165                                      fs->group_desc_count - 1) /
 166                                              fs->group_desc_count;
 167         if (super->s_inodes_per_group > fs->blocksize*8)
 168                 super->s_inodes_per_group = fs->blocksize*8;
 169
 170         /*
 171          * Make sure the number of inodes per group completely fills
 172          * the inode table blocks in the descriptor.  If not, add some
 173          * additional inodes/group.  Waste not, want not...
 174          */
 175         fs->inode_blocks_per_group = (((super->s_inodes_per_group *
 176                                         EXT2_INODE_SIZE(super)) +
 177                                        EXT2_BLOCK_SIZE(super) - 1) /
 178                                       EXT2_BLOCK_SIZE(super));
 179         super->s_inodes_per_group = ((fs->inode_blocks_per_group *
 180                                       EXT2_BLOCK_SIZE(super)) /
 181                                      EXT2_INODE_SIZE(super));
 182         /*
 183          * Finally, make sure the number of inodes per group is a
 184          * multiple of 8.  This is needed to simplify the bitmap
 185          * splicing code.
 186          */
 187         super->s_inodes_per_group &= ~7;
 188         fs->inode_blocks_per_group = (((super->s_inodes_per_group *
 189                                         EXT2_INODE_SIZE(super)) +
 190                                        EXT2_BLOCK_SIZE(super) - 1) /
 191                                       EXT2_BLOCK_SIZE(super));
 192
 193         /*
 194          * adjust inode count to reflect the adjusted inodes_per_group
 195          */
 196         super->s_inodes_count = super->s_inodes_per_group *
 197                 fs->group_desc_count;
 198         super->s_free_inodes_count = super->s_inodes_count;
 199
 200         /*
 201          * Overhead is the number of bookkeeping blocks per group.  It
 202          * includes the superblock backup, the group descriptor
 203          * backups, the inode bitmap, the block bitmap, and the inode
 204          * table.
 205          *
 206          * XXX Not all block groups need the descriptor blocks, but
 207          * being clever is tricky...
 208          */
 209         overhead = (int) (3 + fs->desc_blocks + fs->inode_blocks_per_group);
 210
 211         /*
 212          * See if the last group is big enough to support the
 213          * necessary data structures.  If not, we need to get rid of
 214          * it.
 215          */
 216         rem = (int) ((super->s_blocks_count - super->s_first_data_block) %
 217                      super->s_blocks_per_group);
 218         if ((fs->group_desc_count == 1) && rem && (rem < overhead))
 219                 return EXT2_ET_TOOSMALL;
 220         if (rem && (rem < overhead+50)) {
 221                 super->s_blocks_count -= rem;
 222                 goto retry;
 223         }
 224
 225         /*
 226          * At this point we know how big the filesystem will be.  So
 227          * we can do any and all allocations that depend on the block
 228          * count.
 229          */
 230
 231         buf = malloc(strlen(fs->device_name) + 80);
 232         if (!buf) {
 233                 retval = ENOMEM;
 234                 goto cleanup;
 235         }
 236
 237         sprintf(buf, "block bitmap for %s", fs->device_name);
 238         retval = ext2fs_allocate_block_bitmap(fs, buf, &fs->block_map);
 239         if (retval)
 240                 goto cleanup;
 241
 242         sprintf(buf, "inode bitmap for %s", fs->device_name);
 243         retval = ext2fs_allocate_inode_bitmap(fs, buf, &fs->inode_map);
 244         if (retval)
 245                 goto cleanup;
 246
 247         free(buf);
 248
 249         fs->group_desc = malloc((size_t) fs->desc_blocks * fs->blocksize);
 250         if (!fs->group_desc) {
 251                 retval = ENOMEM;
 252                 goto cleanup;
 253         }
 254         memset(fs->group_desc, 0, (size_t) fs->desc_blocks * fs->blocksize);
 255
 256         /*
 257          * Reserve the superblock and group descriptors for each
 258          * group, and fill in the correct group statistics for group.
 259          * Note that although the block bitmap, inode bitmap, and
 260          * inode table have not been allocated (and in fact won't be
 261          * by this routine), they are accounted for nevertheless.
 262          */
 263         group_block = super->s_first_data_block;
 264         super->s_free_blocks_count = 0;
 265         for (i = 0; i < fs->group_desc_count; i++) {
 266                 if (i == fs->group_desc_count-1) {
 267                         numblocks = (fs->super->s_blocks_count -
 268                                      fs->super->s_first_data_block) %
 269                                              fs->super->s_blocks_per_group;
 270                         if (!numblocks)
 271                                 numblocks = fs->super->s_blocks_per_group;
 272                 } else
 273                         numblocks = fs->super->s_blocks_per_group;
 274
 275                 if (ext2fs_bg_has_super(fs, i)) {
 276                         for (j=0; j < fs->desc_blocks+1; j++)
 277                                 ext2fs_mark_block_bitmap(fs->block_map,
 278                                                          group_block + j);
 279                         numblocks -= 1 + fs->desc_blocks;
 280                 }
 281
 282                 numblocks -= 2 + fs->inode_blocks_per_group;
 283
 284                 super->s_free_blocks_count += numblocks;
 285                 fs->group_desc[i].bg_free_blocks_count = numblocks;
 286                 fs->group_desc[i].bg_free_inodes_count =
 287                         fs->super->s_inodes_per_group;
 288                 fs->group_desc[i].bg_used_dirs_count = 0;
 289
 290                 group_block += super->s_blocks_per_group;
 291         }
 292
 293         ext2fs_mark_super_dirty(fs);
 294         ext2fs_mark_bb_dirty(fs);
 295         ext2fs_mark_ib_dirty(fs);
 296
 297         io_channel_set_blksize(fs->io, fs->blocksize);
 298
 299         *ret_fs = fs;
 300         return 0;
 301 cleanup:
 302         ext2fs_free(fs);
 303         return retval;
 304 }
 305
 306
 307