1 files changed, 81 insertions, 0 deletions
diff --git a/lib/ext2fs/alloc_sb.c b/lib/ext2fs/alloc_sb.c
new file mode 100644
index 0000000..8530b40
--- /dev/null
+++ b/lib/ext2fs/alloc_sb.c
@@ -0,0 +1,81 @@
+/*
+ * 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 "config.h"
+#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 (ext2fs_has_feature_meta_bg(fs->super))
+		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) {
+		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  ;
+}