Orange Pi5 kernel

^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  1) .. SPDX-License-Identifier: GPL-2.0
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  2) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  3) Block and inode Bitmaps
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  4) -----------------------
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  5) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  6) The data block bitmap tracks the usage of data blocks within the block
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  7) group.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  8) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  9) The inode bitmap records which entries in the inode table are in use.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 10) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 11) As with most bitmaps, one bit represents the usage status of one data
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 12) block or inode table entry. This implies a block group size of 8 \*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 13) number\_of\_bytes\_in\_a\_logical\_block.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 14) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 15) NOTE: If ``BLOCK_UNINIT`` is set for a given block group, various parts
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 16) of the kernel and e2fsprogs code pretends that the block bitmap contains
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 17) zeros (i.e. all blocks in the group are free). However, it is not
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 18) necessarily the case that no blocks are in use -- if ``meta_bg`` is set,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 19) the bitmaps and group descriptor live inside the group. Unfortunately,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 20) ext2fs\_test\_block\_bitmap2() will return '0' for those locations,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 21) which produces confusing debugfs output.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 22) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 23) Inode Table
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 24) -----------
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 25) Inode tables are statically allocated at mkfs time.  Each block group
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 26) descriptor points to the start of the table, and the superblock records
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 27) the number of inodes per group.  See the section on inodes for more
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 28) information.