1 /* 2 * alloc_sb.c --- Allocate the superblock and block group descriptors for a 3 * newly initialized filesystem. Used by mke2fs when initializing a filesystem 4 * 5 * Copyright (C) 1994, 1995, 1996, 2003 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 <fcntl.h> 19 #include <time.h> 20 #if HAVE_SYS_STAT_H 21 #include <sys/stat.h> 22 #endif 23 #if HAVE_SYS_TYPES_H 24 #include <sys/types.h> 25 #endif 26 27 #include "ext2_fs.h" 28 #include "ext2fs.h" 29 30 /* 31 * This function reserves the superblock and block group descriptors 32 * for a given block group. It currently returns the number of free 33 * blocks assuming that inode table and allocation bitmaps will be in 34 * the group. This is not necessarily the case when the flex_bg 35 * feature is enabled, so callers should take care! It was only 36 * really intended for use by mke2fs, and even there it's not that 37 * useful. In the future, when we redo this function for 64-bit block 38 * numbers, we should probably return the number of blocks used by the 39 * super block and group descriptors instead. 40 * 41 * See also the comment for ext2fs_super_and_bgd_loc() 42 */ 43 int ext2fs_reserve_super_and_bgd(ext2_filsys fs, 44 dgrp_t group, 45 ext2fs_block_bitmap bmap) 46 { 47 blk_t super_blk, old_desc_blk, new_desc_blk; 48 int j, old_desc_blocks, num_blocks; 49 50 num_blocks = ext2fs_super_and_bgd_loc(fs, group, &super_blk, 51 &old_desc_blk, &new_desc_blk, 0); 52 53 if (fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG) 54 old_desc_blocks = fs->super->s_first_meta_bg; 55 else 56 old_desc_blocks = 57 fs->desc_blocks + fs->super->s_reserved_gdt_blocks; 58 59 if (super_blk || (group == 0)) 60 ext2fs_mark_block_bitmap(bmap, super_blk); 61 62 if (old_desc_blk) { 63 if (fs->super->s_reserved_gdt_blocks && fs->block_map == bmap) 64 fs->group_desc[group].bg_flags &= ~EXT2_BG_BLOCK_UNINIT; 65 for (j=0; j < old_desc_blocks; j++) 66 if (old_desc_blk + j < fs->super->s_blocks_count) 67 ext2fs_mark_block_bitmap(bmap, 68 old_desc_blk + j); 69 } 70 if (new_desc_blk) 71 ext2fs_mark_block_bitmap(bmap, new_desc_blk); 72 73 return num_blocks; 74 } 75
