82 lines
2.4 KiB
C
82 lines
2.4 KiB
C
/*
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* alloc_sb.c --- Allocate the superblock and block group descriptors for a
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* newly initialized filesystem. Used by mke2fs when initializing a filesystem
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*
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* Copyright (C) 1994, 1995, 1996, 2003 Theodore Ts'o.
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*
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* %Begin-Header%
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* This file may be redistributed under the terms of the GNU Library
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* General Public License, version 2.
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* %End-Header%
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*/
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#include "config.h"
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#include <stdio.h>
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#include <string.h>
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#if HAVE_UNISTD_H
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#include <unistd.h>
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#endif
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#include <fcntl.h>
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#include <time.h>
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#if HAVE_SYS_STAT_H
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#include <sys/stat.h>
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#endif
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#if HAVE_SYS_TYPES_H
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#include <sys/types.h>
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#endif
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#include "ext2_fs.h"
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#include "ext2fs.h"
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/*
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* This function reserves the superblock and block group descriptors
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* for a given block group. It currently returns the number of free
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* blocks assuming that inode table and allocation bitmaps will be in
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* the group. This is not necessarily the case when the flex_bg
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* feature is enabled, so callers should take care! It was only
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* really intended for use by mke2fs, and even there it's not that
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* useful. In the future, when we redo this function for 64-bit block
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* numbers, we should probably return the number of blocks used by the
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* super block and group descriptors instead.
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*
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* See also the comment for ext2fs_super_and_bgd_loc()
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*/
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int ext2fs_reserve_super_and_bgd(ext2_filsys fs,
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dgrp_t group,
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ext2fs_block_bitmap bmap)
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{
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blk64_t super_blk, old_desc_blk, new_desc_blk;
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blk_t used_blks;
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int old_desc_blocks, num_blocks;
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ext2fs_super_and_bgd_loc2(fs, group, &super_blk,
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&old_desc_blk, &new_desc_blk, &used_blks);
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if (ext2fs_has_feature_meta_bg(fs->super))
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old_desc_blocks = fs->super->s_first_meta_bg;
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else
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old_desc_blocks =
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fs->desc_blocks + fs->super->s_reserved_gdt_blocks;
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if (super_blk || (group == 0))
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ext2fs_mark_block_bitmap2(bmap, super_blk);
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if ((group == 0) && (fs->blocksize == 1024) &&
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EXT2FS_CLUSTER_RATIO(fs) > 1)
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ext2fs_mark_block_bitmap2(bmap, 0);
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if (old_desc_blk) {
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num_blocks = old_desc_blocks;
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if (old_desc_blk + num_blocks >= ext2fs_blocks_count(fs->super))
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num_blocks = ext2fs_blocks_count(fs->super) -
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old_desc_blk;
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ext2fs_mark_block_bitmap_range2(bmap, old_desc_blk, num_blocks);
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}
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if (new_desc_blk)
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ext2fs_mark_block_bitmap2(bmap, new_desc_blk);
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num_blocks = ext2fs_group_blocks_count(fs, group);
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num_blocks -= 2 + fs->inode_blocks_per_group + used_blks;
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return num_blocks ;
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}
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