1 .. SPDX-License-Identifier: GPL-2.0 2 3 Block and inode Bitmaps 4 ----------------------- 5 6 The data block bitmap tracks the usage of data blocks within the block 7 group. 8 9 The inode bitmap records which entries in the inode table are in use. 10 11 As with most bitmaps, one bit represents the usage status of one data 12 block or inode table entry. This implies a block group size of 8 * 13 number_of_bytes_in_a_logical_block. 14 15 NOTE: If ``BLOCK_UNINIT`` is set for a given block group, various parts 16 of the kernel and e2fsprogs code pretends that the block bitmap contains 17 zeros (i.e. all blocks in the group are free). However, it is not 18 necessarily the case that no blocks are in use -- if ``meta_bg`` is set, 19 the bitmaps and group descriptor live inside the group. Unfortunately, 20 ext2fs_test_block_bitmap2() will return '0' for those locations, 21 which produces confusing debugfs output. 22 23 Inode Table 24 ----------- 25 Inode tables are statically allocated at mkfs time. Each block group 26 descriptor points to the start of the table, and the superblock records 27 the number of inodes per group. See the section on inodes for more 28 information.
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.