mirror of
https://github.com/torvalds/linux.git
synced 2025-11-04 02:30:34 +02:00
3103084afc
Signed-off-by: Wang Jianjian <wangjianjian3@huawei.com> Link: https://lore.kernel.org/r/20220520022255.2120576-2-wangjianjian3@huawei.com Signed-off-by: Theodore Ts'o <tytso@mit.edu>
27 lines
1 KiB
ReStructuredText
27 lines
1 KiB
ReStructuredText
.. SPDX-License-Identifier: GPL-2.0
|
|
|
|
High Level Design
|
|
=================
|
|
|
|
An ext4 file system is split into a series of block groups. To reduce
|
|
performance difficulties due to fragmentation, the block allocator tries
|
|
very hard to keep each file's blocks within the same group, thereby
|
|
reducing seek times. The size of a block group is specified in
|
|
``sb.s_blocks_per_group`` blocks, though it can also calculated as 8 *
|
|
``block_size_in_bytes``. With the default block size of 4KiB, each group
|
|
will contain 32,768 blocks, for a length of 128MiB. The number of block
|
|
groups is the size of the device divided by the size of a block group.
|
|
|
|
All fields in ext4 are written to disk in little-endian order. HOWEVER,
|
|
all fields in jbd2 (the journal) are written to disk in big-endian
|
|
order.
|
|
|
|
.. include:: blocks.rst
|
|
.. include:: blockgroup.rst
|
|
.. include:: special_inodes.rst
|
|
.. include:: allocators.rst
|
|
.. include:: checksums.rst
|
|
.. include:: bigalloc.rst
|
|
.. include:: inlinedata.rst
|
|
.. include:: eainode.rst
|
|
.. include:: verity.rst
|