ffa09b3bd0
Add DEFLATE compression as the 3rd supported algorithm. DEFLATE is a popular generic-purpose compression algorithm for quite long time (many advanced formats like gzip, zlib, zip, png are all based on that) as Apple documentation written "If you require interoperability with non-Apple devices, use COMPRESSION_ZLIB. [1]". Due to its popularity, there are several hardware on-market DEFLATE accelerators, such as (s390) DFLTCC, (Intel) IAA/QAT, (HiSilicon) ZIP accelerator, etc. In addition, there are also several high-performence IP cores and even open-source FPGA approches available for DEFLATE. Therefore, it's useful to support DEFLATE compression in order to find a way to utilize these accelerators for asynchronous I/Os and get benefits from these later. Besides, it's a good choice to trade off between compression ratios and performance compared to LZ4 and LZMA. The DEFLATE core format is simple as well as easy to understand, therefore the code size of its decompressor is small even for the bootloader use cases. The runtime memory consumption is quite limited too (e.g. 32K + ~7K for each zlib stream). As usual, EROFS ourperforms similar approaches too. Alternatively, DEFLATE could still be used for some specific files since EROFS supports multiple compression algorithms in one image. [1] https://developer.apple.com/documentation/compression/compression_algorithm Reviewed-by: Chao Yu <chao@kernel.org> Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com> Link: https://lore.kernel.org/r/20230810154859.118330-1-hsiangkao@linux.alibaba.com
145 lines
4.5 KiB
Plaintext
145 lines
4.5 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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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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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 LZ4 algorithm, at the
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expense of more CPU overhead.
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LZMA support is an experimental feature for now and so most file
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systems will be readable without selecting this option.
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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_ONDEMAND
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bool "EROFS fscache-based on-demand read support"
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depends on CACHEFILES_ONDEMAND && (EROFS_FS=m && FSCACHE || EROFS_FS=y && FSCACHE=y)
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default n
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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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