After two months of development Linus Torvalds introduced Linux kernel release 5.12. Among the most notable changes: Support for zoned block devices in BTRFS, the ability to mapping user IDs for FS, cleaning outdated ARM architectures, “impatient” recording mode in NFS, LOOKUP_CACHED to determine the file pathways from cache, support for atomic instructions in BPF, debug system Kfence To detect errors when working with a memory operating in a separate nucleus stream NAPI POLL-INGA mode in a network stack, ACRN hypervisor, the ability to change on the fly of the Preempt model in the task scheduler and support for LTO optimizations when assembling in Clang.
The new version adopted 14170 (in the past release of 15480) corrections from 1946 (1991) developers,
Patch size – 38 MB (changes affected 12102 (12090) files, Added 538599 (868025) Line of code, removed 333377 (261456) lines). About 43% of all presented in 5.12
Changes are associated with device drivers, about 17% of changes have
Attitude to the update of code specific to hardware architectures, 12%
associated with a network stack, 5% – with file systems and 4% with internal
core subsystems.
- Disk subsystem, enter / output and file systems
- is implemented The possibility of mapping identifiers Users for mounted file systems (you can match the files of one user on an affected stranger section with another user in the current system). Mapping is supported for FS FAT, EXT4 and XFS. The proposed functionality allows you to simplify the sharing of files with different users and on different computers, including mapping will be used in the portable SystemD-Homed home directory mechanism, allowing users to move their home catalogs to external media and use them on different computers, layout user identifiers on which does not coincide. Another useful application is to organize sharing files from an external host, without actually changing data about the owners of files in the FS.
- The kernel adopted patches lookup_cached , allowing you to perform file path definition operations without blocking, only on the basis of the existing cache data. The LOOKUP_CACHED mode is activated in the OpenAT2 () call via the RESOLVE_CACHED flag transmission, in which the data is given only from the cache, and if the path definition requires access to the drive, Eagain error is returned.