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initialize.c

/*
 * initialize.c --- initialize a filesystem handle given superblock
 *    parameters.  Used by mke2fs when initializing a filesystem.
 * 
 * Copyright (C) 1994, 1995, 1996 Theodore Ts'o.
 * 
 * %Begin-Header%
 * This file may be redistributed under the terms of the GNU Public
 * License.
 * %End-Header%
 */

#include <stdio.h>
#include <string.h>
#if HAVE_UNISTD_H
#include <unistd.h>
#endif
#include <fcntl.h>
#include <time.h>
#if HAVE_SYS_STAT_H
#include <sys/stat.h>
#endif
#if HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif

#include "ext2_fs.h"
#include "ext2fs.h"

#if  defined(__linux__)    && defined(EXT2_OS_LINUX)
#define CREATOR_OS EXT2_OS_LINUX
#elif defined(__GNU__)     && defined(EXT2_OS_HURD)
#define CREATOR_OS EXT2_OS_HURD
#elif defined(__FreeBSD__) && defined(EXT2_OS_FREEBSD)
#define CREATOR_OS EXT2_OS_FREEBSD
#elif defined(LITES)       && defined(EXT2_OS_LITES)
#define CREATOR_OS EXT2_OS_LITES
#else
#define CREATOR_OS EXT2_OS_LINUX /* by default */
#endif

/*
 * Note we override the kernel include file's idea of what the default
 * check interval (never) should be.  It's a good idea to check at
 * least *occasionally*, specially since servers will never rarely get
 * to reboot, since Linux is so robust these days.  :-)
 * 
 * 180 days (six months) seems like a good value.
 */
#ifdef EXT2_DFL_CHECKINTERVAL
#undef EXT2_DFL_CHECKINTERVAL
#endif
#define EXT2_DFL_CHECKINTERVAL (86400L * 180L)

errcode_t ext2fs_initialize(const char *name, int flags,
                      struct ext2_super_block *param,
                      io_manager manager, ext2_filsys *ret_fs)
{
      ext2_filsys fs;
      errcode_t   retval;
      struct ext2_super_block *super;
      int         frags_per_block;
      int         rem;
      int         overhead = 0;
      blk_t       group_block;
      int         i, j;
      blk_t       numblocks;
      char        *buf;

      if (!param || !param->s_blocks_count)
            return EXT2_ET_INVALID_ARGUMENT;
      
      retval = ext2fs_get_mem(sizeof(struct struct_ext2_filsys),
                        (void **) &fs);
      if (retval)
            return retval;
      
      memset(fs, 0, sizeof(struct struct_ext2_filsys));
      fs->magic = EXT2_ET_MAGIC_EXT2FS_FILSYS;
      fs->flags = flags | EXT2_FLAG_RW;
      fs->umask = 022;
#ifdef WORDS_BIGENDIAN
      fs->flags |= EXT2_FLAG_SWAP_BYTES;
#endif
      retval = manager->open(name, IO_FLAG_RW, &fs->io);
      if (retval)
            goto cleanup;
      fs->io->app_data = fs;
      retval = ext2fs_get_mem(strlen(name)+1, (void **) &fs->device_name);
      if (retval)
            goto cleanup;

      strcpy(fs->device_name, name);
      retval = ext2fs_get_mem(SUPERBLOCK_SIZE, (void **) &super);
      if (retval)
            goto cleanup;
      fs->super = super;

      memset(super, 0, SUPERBLOCK_SIZE);

#define set_field(field, default) (super->field = param->field ? \
                           param->field : (default))

      super->s_magic = EXT2_SUPER_MAGIC;
      super->s_state = EXT2_VALID_FS;

      set_field(s_log_block_size, 0);     /* default blocksize: 1024 bytes */
      set_field(s_log_frag_size, 0); /* default fragsize: 1024 bytes */
      set_field(s_first_data_block, super->s_log_block_size ? 0 : 1);
      set_field(s_max_mnt_count, EXT2_DFL_MAX_MNT_COUNT);
      set_field(s_errors, EXT2_ERRORS_DEFAULT);
      set_field(s_feature_compat, 0);
      set_field(s_feature_incompat, 0);
      set_field(s_feature_ro_compat, 0);
      if (super->s_feature_incompat & ~EXT2_LIB_FEATURE_INCOMPAT_SUPP)
            return EXT2_ET_UNSUPP_FEATURE;
      if (super->s_feature_ro_compat & ~EXT2_LIB_FEATURE_RO_COMPAT_SUPP)
            return EXT2_ET_RO_UNSUPP_FEATURE;

      set_field(s_rev_level, EXT2_GOOD_OLD_REV);
      if (super->s_rev_level >= EXT2_DYNAMIC_REV) {
            set_field(s_first_ino, EXT2_GOOD_OLD_FIRST_INO);
            set_field(s_inode_size, EXT2_GOOD_OLD_INODE_SIZE);
      }

      set_field(s_checkinterval, EXT2_DFL_CHECKINTERVAL);
      super->s_lastcheck = time(NULL);

      super->s_creator_os = CREATOR_OS;

      fs->blocksize = EXT2_BLOCK_SIZE(super);
      fs->fragsize = EXT2_FRAG_SIZE(super);
      frags_per_block = fs->blocksize / fs->fragsize;
      
      /* default: (fs->blocksize*8) blocks/group */
      set_field(s_blocks_per_group, fs->blocksize*8); 
      super->s_frags_per_group = super->s_blocks_per_group * frags_per_block;
      
      super->s_blocks_count = param->s_blocks_count;
      super->s_r_blocks_count = param->s_r_blocks_count;
      if (super->s_r_blocks_count >= param->s_blocks_count) {
            retval = EXT2_ET_INVALID_ARGUMENT;
            goto cleanup;
      }

      /*
       * If we're creating an external journal device, we don't need
       * to bother with the rest.
       */
      if (super->s_feature_incompat &
          EXT3_FEATURE_INCOMPAT_JOURNAL_DEV) {
            fs->group_desc_count = 0;
            ext2fs_mark_super_dirty(fs);
            *ret_fs = fs;
            return 0;
      }

retry:
      fs->group_desc_count = (super->s_blocks_count -
                        super->s_first_data_block +
                        EXT2_BLOCKS_PER_GROUP(super) - 1)
            / EXT2_BLOCKS_PER_GROUP(super);
      if (fs->group_desc_count == 0)
            return EXT2_ET_TOOSMALL;
      fs->desc_blocks = (fs->group_desc_count +
                     EXT2_DESC_PER_BLOCK(super) - 1)
            / EXT2_DESC_PER_BLOCK(super);

      /* n.b., fs->blocksize is <= 4096 */
      set_field(s_inodes_count, super->s_blocks_count/(4096/fs->blocksize));

      /*
       * Make sure we have at least EXT2_FIRST_INO + 1 inodes, so
       * that we have enough inodes for the filesystem(!)
       */
      if (super->s_inodes_count < EXT2_FIRST_INODE(super)+1)
            super->s_inodes_count = EXT2_FIRST_INODE(super)+1;
      
      /*
       * There should be at least as many inodes as the user
       * requested.  Figure out how many inodes per group that
       * should be.  But make sure that we don't allocate more than
       * one bitmap's worth of inodes
       */
      super->s_inodes_per_group = (super->s_inodes_count +
                             fs->group_desc_count - 1) /
                                   fs->group_desc_count;
      if (super->s_inodes_per_group > fs->blocksize*8)
            super->s_inodes_per_group = fs->blocksize*8;
      
      /*
       * Make sure the number of inodes per group completely fills
       * the inode table blocks in the descriptor.  If not, add some
       * additional inodes/group.  Waste not, want not...
       */
      fs->inode_blocks_per_group = (((super->s_inodes_per_group *
                              EXT2_INODE_SIZE(super)) +
                               EXT2_BLOCK_SIZE(super) - 1) /
                              EXT2_BLOCK_SIZE(super));
      super->s_inodes_per_group = ((fs->inode_blocks_per_group *
                              EXT2_BLOCK_SIZE(super)) /
                             EXT2_INODE_SIZE(super));
      /*
       * Finally, make sure the number of inodes per group is a
       * multiple of 8.  This is needed to simplify the bitmap
       * splicing code.
       */
      super->s_inodes_per_group &= ~7;
      fs->inode_blocks_per_group = (((super->s_inodes_per_group *
                              EXT2_INODE_SIZE(super)) +
                               EXT2_BLOCK_SIZE(super) - 1) /
                              EXT2_BLOCK_SIZE(super));

      /*
       * adjust inode count to reflect the adjusted inodes_per_group
       */
      super->s_inodes_count = super->s_inodes_per_group *
            fs->group_desc_count;
      super->s_free_inodes_count = super->s_inodes_count;

      /*
       * Overhead is the number of bookkeeping blocks per group.  It
       * includes the superblock backup, the group descriptor
       * backups, the inode bitmap, the block bitmap, and the inode
       * table.
       *
       * XXX Not all block groups need the descriptor blocks, but
       * being clever is tricky...
       */
      overhead = (int) (3 + fs->desc_blocks + fs->inode_blocks_per_group);
      
      /*
       * See if the last group is big enough to support the
       * necessary data structures.  If not, we need to get rid of
       * it.
       */
      rem = (int) ((super->s_blocks_count - super->s_first_data_block) %
                 super->s_blocks_per_group);
      if ((fs->group_desc_count == 1) && rem && (rem < overhead))
            return EXT2_ET_TOOSMALL;
      if (rem && (rem < overhead+50)) {
            super->s_blocks_count -= rem;
            goto retry;
      }

      /*
       * At this point we know how big the filesystem will be.  So
       * we can do any and all allocations that depend on the block
       * count.
       */

      retval = ext2fs_get_mem(strlen(fs->device_name) + 80,
                        (void **) &buf);
      if (retval)
            goto cleanup;
      
      sprintf(buf, "block bitmap for %s", fs->device_name);
      retval = ext2fs_allocate_block_bitmap(fs, buf, &fs->block_map);
      if (retval)
            goto cleanup;
      
      sprintf(buf, "inode bitmap for %s", fs->device_name);
      retval = ext2fs_allocate_inode_bitmap(fs, buf, &fs->inode_map);
      if (retval)
            goto cleanup;

      ext2fs_free_mem((void **) &buf);

      retval = ext2fs_get_mem((size_t) fs->desc_blocks * fs->blocksize,
                        (void **) &fs->group_desc);
      if (retval)
            goto cleanup;

      memset(fs->group_desc, 0, (size_t) fs->desc_blocks * fs->blocksize);

      /*
       * Reserve the superblock and group descriptors for each
       * group, and fill in the correct group statistics for group.
       * Note that although the block bitmap, inode bitmap, and
       * inode table have not been allocated (and in fact won't be
       * by this routine), they are accounted for nevertheless.
       */
      group_block = super->s_first_data_block;
      super->s_free_blocks_count = 0;
      for (i = 0; i < fs->group_desc_count; i++) {
            if (i == fs->group_desc_count-1) {
                  numblocks = (fs->super->s_blocks_count -
                             fs->super->s_first_data_block) %
                                   fs->super->s_blocks_per_group;
                  if (!numblocks)
                        numblocks = fs->super->s_blocks_per_group;
            } else
                  numblocks = fs->super->s_blocks_per_group;

            if (ext2fs_bg_has_super(fs, i)) {
                  for (j=0; j < fs->desc_blocks+1; j++)
                        ext2fs_mark_block_bitmap(fs->block_map,
                                           group_block + j);
                  numblocks -= 1 + fs->desc_blocks;
            }
            
            numblocks -= 2 + fs->inode_blocks_per_group;
            
            super->s_free_blocks_count += numblocks;
            fs->group_desc[i].bg_free_blocks_count = numblocks;
            fs->group_desc[i].bg_free_inodes_count =
                  fs->super->s_inodes_per_group;
            fs->group_desc[i].bg_used_dirs_count = 0;
            
            group_block += super->s_blocks_per_group;
      }
      
      ext2fs_mark_super_dirty(fs);
      ext2fs_mark_bb_dirty(fs);
      ext2fs_mark_ib_dirty(fs);
      
      io_channel_set_blksize(fs->io, fs->blocksize);

      *ret_fs = fs;
      return 0;
cleanup:
      ext2fs_free(fs);
      return retval;
}
      



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