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Add MicroLZMA support in order to maximize compression ratios for specific scenarios. For example, it's useful for low-end embedded boards and as a secondary algorithm in a file for specific access patterns. MicroLZMA is a new container format for raw LZMA1, which was created by Lasse Collin aiming to minimize old LZMA headers and get rid of unnecessary EOPM (end of payload marker) as well as to enable fixed-sized output compression, especially for 4KiB pclusters. Similar to LZ4, inplace I/O approach is used to minimize runtime memory footprint when dealing with I/O. Overlapped decompression is handled with 1) bounced buffer for data under processing or 2) extra short-lived pages from the on-stack pagepool which will be shared in the same read request (128KiB for example). Link: https://lore.kernel.org/r/20211010213145.17462-8-xiang@kernel.org Acked-by: Chao Yu <chao@kernel.org> Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
101 lines
3.2 KiB
Plaintext
101 lines
3.2 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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