| /* |
| * alloc_sb.c --- Allocate the superblock and block group descriptors for a |
| * newly initialized filesystem. Used by mke2fs when initializing a filesystem |
| * |
| * Copyright (C) 1994, 1995, 1996, 2003 Theodore Ts'o. |
| * |
| * %Begin-Header% |
| * This file may be redistributed under the terms of the GNU Library |
| * General Public License, version 2. |
| * %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" |
| |
| /* |
| * This function reserves the superblock and block group descriptors |
| * for a given block group. It currently returns the number of free |
| * blocks assuming that inode table and allocation bitmaps will be in |
| * the group. This is not necessarily the case when the flex_bg |
| * feature is enabled, so callers should take care! It was only |
| * really intended for use by mke2fs, and even there it's not that |
| * useful. In the future, when we redo this function for 64-bit block |
| * numbers, we should probably return the number of blocks used by the |
| * super block and group descriptors instead. |
| * |
| * See also the comment for ext2fs_super_and_bgd_loc() |
| */ |
| int ext2fs_reserve_super_and_bgd(ext2_filsys fs, |
| dgrp_t group, |
| ext2fs_block_bitmap bmap) |
| { |
| blk64_t super_blk, old_desc_blk, new_desc_blk; |
| blk_t used_blks; |
| int old_desc_blocks, num_blocks; |
| |
| ext2fs_super_and_bgd_loc2(fs, group, &super_blk, |
| &old_desc_blk, &new_desc_blk, &used_blks); |
| |
| if (fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG) |
| old_desc_blocks = fs->super->s_first_meta_bg; |
| else |
| old_desc_blocks = |
| fs->desc_blocks + fs->super->s_reserved_gdt_blocks; |
| |
| if (super_blk || (group == 0)) |
| ext2fs_mark_block_bitmap2(bmap, super_blk); |
| if ((group == 0) && (fs->blocksize == 1024) && |
| EXT2FS_CLUSTER_RATIO(fs) > 1) |
| ext2fs_mark_block_bitmap2(bmap, 0); |
| |
| if (old_desc_blk) { |
| if (fs->super->s_reserved_gdt_blocks && fs->block_map == bmap) |
| ext2fs_bg_flags_clear(fs, group, EXT2_BG_BLOCK_UNINIT); |
| num_blocks = old_desc_blocks; |
| if (old_desc_blk + num_blocks >= ext2fs_blocks_count(fs->super)) |
| num_blocks = ext2fs_blocks_count(fs->super) - |
| old_desc_blk; |
| ext2fs_mark_block_bitmap_range2(bmap, old_desc_blk, num_blocks); |
| } |
| if (new_desc_blk) |
| ext2fs_mark_block_bitmap2(bmap, new_desc_blk); |
| |
| num_blocks = ext2fs_group_blocks_count(fs, group); |
| num_blocks -= 2 + fs->inode_blocks_per_group + used_blks; |
| |
| return num_blocks ; |
| } |