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Patch series " lib/base64: add generic encoder/decoder, migrate users", v5. This series introduces a generic Base64 encoder/decoder to the kernel library, eliminating duplicated implementations and delivering significant performance improvements. The Base64 API has been extended to support multiple variants (Standard, URL-safe, and IMAP) as defined in RFC 4648 and RFC 3501. The API now takes a variant parameter and an option to control padding. As part of this series, users are migrated to the new interface while preserving their specific formats: fscrypt now uses BASE64_URLSAFE, Ceph uses BASE64_IMAP, and NVMe is updated to BASE64_STD. On the encoder side, the implementation processes input in 3-byte blocks, mapping 24 bits directly to 4 output symbols. This avoids bit-by-bit streaming and reduces loop overhead, achieving about a 2.7x speedup compared to previous implementations. On the decoder side, replace strchr() lookups with per-variant reverse tables and process input in 4-character groups. Each group is mapped to numeric values and combined into 3 bytes. Padded and unpadded forms are validated explicitly, rejecting invalid '=' usage and enforcing tail rules. This improves throughput by ~43-52x. This patch (of 6): Extend the base64 API to support multiple variants (standard, URL-safe, and IMAP) as defined in RFC 4648 and RFC 3501. The API now takes a variant parameter and an option to control padding. Update NVMe auth code to use the new interface with BASE64_STD. Link: https://lkml.kernel.org/r/20251114055829.87814-1-409411716@gms.tku.edu.tw Link: https://lkml.kernel.org/r/20251114060045.88792-1-409411716@gms.tku.edu.tw Signed-off-by: Kuan-Wei Chiu <visitorckw@gmail.com> Co-developed-by: Guan-Chun Wu <409411716@gms.tku.edu.tw> Signed-off-by: Guan-Chun Wu <409411716@gms.tku.edu.tw> Reviewed-by: David Laight <david.laight.linux@gmail.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Eric Biggers <ebiggers@kernel.org> Cc: Ilya Dryomov <idryomov@gmail.com> Cc: Jaegeuk Kim <jaegeuk@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Keith Busch <kbusch@kernel.org> Cc: Sagi Grimberg <sagi@grimberg.me> Cc: "Theodore Y. Ts'o" <tytso@mit.edu> Cc: Viacheslav Dubeyko <Slava.Dubeyko@ibm.com> Cc: Xiubo Li <xiubli@redhat.com> Cc: Yu-Sheng Huang <home7438072@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.