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git.ipfire.org Git - thirdparty/e2fsprogs.git/blob - lib/ext2fs/alloc_sb.c
2 * alloc_sb.c --- Allocate the superblock and block group descriptors for a
3 * newly initialized filesystem. Used by mke2fs when initializing a filesystem
5 * Copyright (C) 1994, 1995, 1996, 2003 Theodore Ts'o.
8 * This file may be redistributed under the terms of the GNU Library
9 * General Public License, version 2.
25 #include <sys/types.h>
32 * This function reserves the superblock and block group descriptors
33 * for a given block group. It currently returns the number of free
34 * blocks assuming that inode table and allocation bitmaps will be in
35 * the group. This is not necessarily the case when the flex_bg
36 * feature is enabled, so callers should take care! It was only
37 * really intended for use by mke2fs, and even there it's not that
38 * useful. In the future, when we redo this function for 64-bit block
39 * numbers, we should probably return the number of blocks used by the
40 * super block and group descriptors instead.
42 * See also the comment for ext2fs_super_and_bgd_loc()
44 int ext2fs_reserve_super_and_bgd(ext2_filsys fs
,
46 ext2fs_block_bitmap bmap
)
48 blk64_t super_blk
, old_desc_blk
, new_desc_blk
;
49 blk_t used_blks
, old_desc_blocks
, num_blocks
;
51 ext2fs_super_and_bgd_loc2(fs
, group
, &super_blk
,
52 &old_desc_blk
, &new_desc_blk
, &used_blks
);
54 if (ext2fs_has_feature_meta_bg(fs
->super
))
55 old_desc_blocks
= fs
->super
->s_first_meta_bg
;
58 fs
->desc_blocks
+ fs
->super
->s_reserved_gdt_blocks
;
60 if (super_blk
|| (group
== 0))
61 ext2fs_mark_block_bitmap2(bmap
, super_blk
);
62 if ((group
== 0) && (fs
->blocksize
== 1024) &&
63 EXT2FS_CLUSTER_RATIO(fs
) > 1)
64 ext2fs_mark_block_bitmap2(bmap
, 0);
67 num_blocks
= old_desc_blocks
;
68 if (old_desc_blk
+ num_blocks
>= ext2fs_blocks_count(fs
->super
))
69 num_blocks
= ext2fs_blocks_count(fs
->super
) -
71 ext2fs_mark_block_bitmap_range2(bmap
, old_desc_blk
, num_blocks
);
74 ext2fs_mark_block_bitmap2(bmap
, new_desc_blk
);
76 num_blocks
= ext2fs_group_blocks_count(fs
, group
);
77 num_blocks
-= 2 + fs
->inode_blocks_per_group
+ used_blks
;
83 * This function reserves the superblock and block group descriptors
84 * for a given block group and returns the number of blocks used by the
85 * super block and group descriptors by looking up the block bitmap.
87 errcode_t
ext2fs_reserve_super_and_bgd2(ext2_filsys fs
,
89 ext2fs_block_bitmap bmap
,
95 ext2fs_reserve_super_and_bgd(fs
, group
, bmap
);
97 retval
= ext2fs_count_used_blocks(fs
,
98 ext2fs_group_first_block2(fs
, group
),
99 ext2fs_group_last_block2(fs
, group
),
102 *desc_blocks
= num_blocks
;