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