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Add Zstandard compression as the 4th supported algorithm since it becomes more popular now and some end users have asked this for quite a while [1][2]. Each EROFS physical cluster contains only one valid standard Zstandard frame as described in [3] so that decompression can be performed on a per-pcluster basis independently. Currently, it just leverages multi-call stream decompression APIs with internal sliding window buffers. One-shot or bufferless decompression could be implemented later for even better performance if needed. [1] https://github.com/erofs/erofs-utils/issues/6 [2] https://lore.kernel.org/r/Y08h+z6CZdnS1XBm@B-P7TQMD6M-0146.lan [3] https://www.rfc-editor.org/rfc/rfc8478.txt Acked-by: Chao Yu <chao@kernel.org> Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com> Link: https://lore.kernel.org/r/20240508234453.17896-1-xiang@kernel.org
161 lines
4.9 KiB
Plaintext
161 lines
4.9 KiB
Plaintext
# SPDX-License-Identifier: GPL-2.0-only
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config EROFS_FS
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tristate "EROFS filesystem support"
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depends on BLOCK
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select FS_IOMAP
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select LIBCRC32C
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help
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EROFS (Enhanced Read-Only File System) is a lightweight read-only
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file system with modern designs (e.g. no buffer heads, inline
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xattrs/data, chunk-based deduplication, multiple devices, etc.) for
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scenarios which need high-performance read-only solutions, e.g.
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smartphones with Android OS, LiveCDs and high-density hosts with
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numerous containers;
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It also provides fixed-sized output compression support in order to
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improve storage density as well as keep relatively higher compression
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ratios and implements in-place decompression to reuse the file page
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for compressed data temporarily with proper strategies, which is
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quite useful to ensure guaranteed end-to-end runtime decompression
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performance under extremely memory pressure without extra cost.
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See the documentation at <file:Documentation/filesystems/erofs.rst>
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and the web pages at <https://erofs.docs.kernel.org> for more details.
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If unsure, say N.
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config EROFS_FS_DEBUG
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bool "EROFS debugging feature"
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depends on EROFS_FS
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help
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Print debugging messages and enable more BUG_ONs which check
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filesystem consistency and find potential issues aggressively,
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which can be used for Android eng build, for example.
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For daily use, say N.
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config EROFS_FS_XATTR
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bool "EROFS extended attributes"
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depends on EROFS_FS
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select XXHASH
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default y
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help
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Extended attributes are name:value pairs associated with inodes by
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the kernel or by users (see the attr(5) manual page, or visit
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<http://acl.bestbits.at/> for details).
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If unsure, say N.
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config EROFS_FS_POSIX_ACL
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bool "EROFS Access Control Lists"
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depends on EROFS_FS_XATTR
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select FS_POSIX_ACL
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default y
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help
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Posix Access Control Lists (ACLs) support permissions for users and
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groups beyond the owner/group/world scheme.
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To learn more about Access Control Lists, visit the POSIX ACLs for
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Linux website <http://acl.bestbits.at/>.
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If you don't know what Access Control Lists are, say N.
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config EROFS_FS_SECURITY
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bool "EROFS Security Labels"
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depends on EROFS_FS_XATTR
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default y
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help
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Security labels provide an access control facility to support Linux
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Security Models (LSMs) accepted by AppArmor, SELinux, Smack and TOMOYO
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Linux. This option enables an extended attribute handler for file
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security labels in the erofs filesystem, so that it requires enabling
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the extended attribute support in advance.
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If you are not using a security module, say N.
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config EROFS_FS_ZIP
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bool "EROFS Data Compression Support"
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depends on EROFS_FS
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select LZ4_DECOMPRESS
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default y
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help
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Enable fixed-sized output compression for EROFS.
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If you don't want to enable compression feature, say N.
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config EROFS_FS_ZIP_LZMA
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bool "EROFS LZMA compressed data support"
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depends on EROFS_FS_ZIP
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select XZ_DEC
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select XZ_DEC_MICROLZMA
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help
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Saying Y here includes support for reading EROFS file systems
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containing LZMA compressed data, specifically called microLZMA. It
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gives better compression ratios than the default LZ4 format, at the
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expense of more CPU overhead.
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If unsure, say N.
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config EROFS_FS_ZIP_DEFLATE
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bool "EROFS DEFLATE compressed data support"
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depends on EROFS_FS_ZIP
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select ZLIB_INFLATE
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help
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Saying Y here includes support for reading EROFS file systems
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containing DEFLATE compressed data. It gives better compression
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ratios than the default LZ4 format, while it costs more CPU
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overhead.
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DEFLATE support is an experimental feature for now and so most
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file systems will be readable without selecting this option.
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If unsure, say N.
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config EROFS_FS_ZIP_ZSTD
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bool "EROFS Zstandard compressed data support"
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depends on EROFS_FS_ZIP
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select ZSTD_DECOMPRESS
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help
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Saying Y here includes support for reading EROFS file systems
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containing Zstandard compressed data. It gives better compression
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ratios than the default LZ4 format, while it costs more CPU
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overhead.
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Zstandard support is an experimental feature for now and so most
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file systems will be readable without selecting this option.
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If unsure, say N.
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config EROFS_FS_ONDEMAND
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bool "EROFS fscache-based on-demand read support"
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depends on EROFS_FS
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select NETFS_SUPPORT
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select FSCACHE
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select CACHEFILES
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select CACHEFILES_ONDEMAND
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help
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This permits EROFS to use fscache-backed data blobs with on-demand
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read support.
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If unsure, say N.
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config EROFS_FS_PCPU_KTHREAD
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bool "EROFS per-cpu decompression kthread workers"
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depends on EROFS_FS_ZIP
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help
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Saying Y here enables per-CPU kthread workers pool to carry out
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async decompression for low latencies on some architectures.
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If unsure, say N.
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config EROFS_FS_PCPU_KTHREAD_HIPRI
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bool "EROFS high priority per-CPU kthread workers"
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depends on EROFS_FS_ZIP && EROFS_FS_PCPU_KTHREAD
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default y
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help
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This permits EROFS to configure per-CPU kthread workers to run
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at higher priority.
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If unsure, say N.
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