File system changes

Kernel Log Penguin New in the Linux 2.6.29 main development tree is the 'copy on write' file system Btrfs, dubbed the "next generation file system" for Linux by many major Linux file system developers. Btrfs is, however, far from finished â the kernel developers plan to continue to enhance it and allow it to come to maturity within the framework of kernel development, as happened with Ext4. The latter was incorporated into Linux 2.6.19 in autumn 2006 and has been improved ever since, with the main development phase having recently ended with Linux 2.6.28.

Also new is the latest version 4.0 of SquashFS â a compressed read-only file system long deployed by various Linux distributions on installation or live media booted from USB, CD or DVD. The alternative to Cramfs it is also much used in embedded systems â the kernel documentation on SquashFS provides a detailed explanation of the differences between Cramfs and SquashFS and how the new file system works.

There have also been numerous, mostly minor, improvements, tidying-up and corrections to the Ext4 file system. Thanks to various patches introduced by the Google development team, Ext4 can now run without a journal â some users had been sticking with Ext2 to escape the journalling overhead.

There were also many changes to some other file systems which have long been part of the kernel â these are discussed in more detail in part five of the "What's new in 2.6.29" Kernel Log series.

The details

This article may look long, but it provides a mere overview of the most important changes in Linux version 2.6.29. Detailed explanations of the new features discussed can be found in the individual parts of the "What's new in 2.6.29" Kernel Log series published on The H Open over the last few weeks. This article is based on the most important sections of that series of articles. If you wish to know about the changes in Linux 2.6.29 in more detail, please read that series of articles and the last page of this article.

The article on file system changes, for example, goes into more detail on the features of Btrfs and links to sources with further information on this completely new file system, which has been developed specifically for Linux. It also briefly discusses a number of patches to Ext4, intended to further improve file system performance, which are not described in this article. The (many) links in the text will lead you to the relevant commits in the kernel.org Git web interface, subsystem administrator Git pull requests, or other sources with further information on the changes described.

Each of the articles also includes an appendix with links to a selection of further important changes for which space has not been found in the main text, but which may be of importance to some users. The appendix to the article on changes relating to audio and video drivers, for example, has links to many patches which improve support for the audio hardware in various makes of PC, laptop or motherboard and the list of changes to the V4L/DVB subsystem includes the names of many TV hardware products which Linux has learnt to deal with in version 2.6.29.