Linux Kernel 5.15 Released, Here Are the Top 3 New Features

During the night from Sunday to Monday, Linus Torvalds announced the Linux Kernel 5.15 release on the Linux Kernel Mailing List.

Above all, Linux Kernel 5.15 is a significant milestone in that it’s also a Long Term Support (LTS) kernel to be maintained for at least the next five years and also is a huge kernel update in general with many new features.

Kernel 5.15 Highlights

The new version is not just a maintenance release, but brings with it new features. But what are the changes in this latest kernel update? Read on for a summary of the three key Linux 5.15 features.

1. Improved NTFS File System Support

However, the most anticipated update in Linux 5.15 is, without a doubt, the inclusion of a new NTFS file system driver, NTFS3.

The existing Linux NTFS driver, which implementation dated back by 2001, is basically unmaintained in the kernel and lacks proper write support along with other features. The NTFS-3G is another open source implementation of Microsoft NTFS that includes read and write support, but it’s a filesystem in userspace (FUSE). So the main drawback of this implementation is speed.

Compared with the existing FUSE-based open source NTFS driver, the new Paragon’s NTFS3 driver in Kernel 5.15 undoubtedly wins in terms of functionality and performance. The driver fully supports reads and writes and many other features not found with the existing Linux driver.

2. New in-kernel SMB3 File Server (KSBMD)

The Kernel 5.15 first to introduce in-Kernel SMB Driver for file sharing. KSMBD is developed by Samsung and is strongly focused on delivering speedy SMB3 file serving performance.

KSMBD is a new kernel module which implements the server-side of the SMB3 protocol. Which means that KSMBD only speaks SMB version 3. Clients with earlier SMB versions cannot establish a connection to the kernel SMB.

KSMBD implements the SMB protocol (also known as CIFS, though that name has gone out of favor) that is heavily used in the Windows world. But why create an in-kernel SMB server at this point? 

At this point, Samba includes a great deal of functionality beyond simple file serving. But KSMBD doubling of performance on some tests. An in-kernel server is an easier place to support variants like SMB Direct, which uses RDMA to transfer data between systems.

It’s important to note that KSMBD doesn’t aim to be as comprehensive as well known Samba for CIFS/SMB support in user-space but is just focused on the performance and kernel feature angle.

3. Optimized File Systems

When it comes to file systems, Linux Kernel 5.15 has made great strides. Ext4 comes with quicker handling of orphan files and also increases the performance of the delalloc write buffer.

XFS stabilizes the ability to use dates after 2038. The mechanism of deferred inode deactivation and support for deferred installation and removal of file attributes has been implemented. In order to avoid problems, the ability to disable disk quotas for already mounted partitions has been removed.

In addition, Btrfs now supports the fs-verity mechanism, which is used to transparently control the integrity and authenticity of individual files using cryptographic hashes or keys stored in the metadata area associated with the files.

Other Improvements in Kernel 5.15

There are a plethora of other changes and additional features in kernel 5.15 too.

  • The temperature monitoring support added for AMD Zen 3 based APUs.
  • The IOMMU driver of Apple M1 was added to improve support for Apple’s M1 chip.
  • Improved Support for Intel’s 12th Gen CPUs.
  • The Realtek RTL8188EU WiFi driver was merged for replacing the prior Realtek WiFi driver.

For more information, you can refer to the official announcement post. Linux Kernel 5.15 is available to download as a source code from the website.

Bobby Borisov

Bobby Borisov

Bobby, an editor-in-chief at Linuxiac, is a Linux professional with over 20 years of experience. With a strong focus on Linux and open-source software, he has worked as a Senior Linux System Administrator, Software Developer, and DevOps Engineer for small and large multinational companies.

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