# SPDX-License-Identifier: GPL-2.0-only config EROFS_FS tristate "EROFS filesystem support" depends on BLOCK select FS_IOMAP select LIBCRC32C help EROFS (Enhanced Read-Only File System) is a lightweight read-only file system with modern designs (e.g. no buffer heads, inline xattrs/data, chunk-based deduplication, multiple devices, etc.) for scenarios which need high-performance read-only solutions, e.g. smartphones with Android OS, LiveCDs and high-density hosts with numerous containers; It also provides fixed-sized output compression support in order to improve storage density as well as keep relatively higher compression ratios and implements in-place decompression to reuse the file page for compressed data temporarily with proper strategies, which is quite useful to ensure guaranteed end-to-end runtime decompression performance under extremely memory pressure without extra cost. See the documentation at and the web pages at for more details. If unsure, say N. config EROFS_FS_DEBUG bool "EROFS debugging feature" depends on EROFS_FS help Print debugging messages and enable more BUG_ONs which check filesystem consistency and find potential issues aggressively, which can be used for Android eng build, for example. For daily use, say N. config EROFS_FS_XATTR bool "EROFS extended attributes" depends on EROFS_FS select XXHASH default y help Extended attributes are name:value pairs associated with inodes by the kernel or by users (see the attr(5) manual page, or visit for details). If unsure, say N. config EROFS_FS_POSIX_ACL bool "EROFS Access Control Lists" depends on EROFS_FS_XATTR select FS_POSIX_ACL default y help Posix Access Control Lists (ACLs) support permissions for users and groups beyond the owner/group/world scheme. To learn more about Access Control Lists, visit the POSIX ACLs for Linux website . If you don't know what Access Control Lists are, say N. config EROFS_FS_SECURITY bool "EROFS Security Labels" depends on EROFS_FS_XATTR default y help Security labels provide an access control facility to support Linux Security Models (LSMs) accepted by AppArmor, SELinux, Smack and TOMOYO Linux. This option enables an extended attribute handler for file security labels in the erofs filesystem, so that it requires enabling the extended attribute support in advance. If you are not using a security module, say N. config EROFS_FS_BACKED_BY_FILE bool "File-backed EROFS filesystem support" depends on EROFS_FS default y help This allows EROFS to use filesystem image files directly, without the intercession of loopback block devices or likewise. It is particularly useful for container images with numerous blobs and other sandboxes, where loop devices behave intricately. It can also be used to simplify error-prone lifetime management of unnecessary virtual block devices. Note that this feature, along with ongoing fanotify pre-content hooks, will eventually replace "EROFS over fscache." If you don't want to enable this feature, say N. config EROFS_FS_ZIP bool "EROFS Data Compression Support" depends on EROFS_FS select LZ4_DECOMPRESS default y help Enable fixed-sized output compression for EROFS. If you don't want to enable compression feature, say N. config EROFS_FS_ZIP_LZMA bool "EROFS LZMA compressed data support" depends on EROFS_FS_ZIP select XZ_DEC select XZ_DEC_MICROLZMA help Saying Y here includes support for reading EROFS file systems containing LZMA compressed data, specifically called microLZMA. It gives better compression ratios than the default LZ4 format, at the expense of more CPU overhead. If unsure, say N. config EROFS_FS_ZIP_DEFLATE bool "EROFS DEFLATE compressed data support" depends on EROFS_FS_ZIP select ZLIB_INFLATE help Saying Y here includes support for reading EROFS file systems containing DEFLATE compressed data. It gives better compression ratios than the default LZ4 format, while it costs more CPU overhead. DEFLATE support is an experimental feature for now and so most file systems will be readable without selecting this option. If unsure, say N. config EROFS_FS_ZIP_ZSTD bool "EROFS Zstandard compressed data support" depends on EROFS_FS_ZIP select ZSTD_DECOMPRESS help Saying Y here includes support for reading EROFS file systems containing Zstandard compressed data. It gives better compression ratios than the default LZ4 format, while it costs more CPU overhead. Zstandard support is an experimental feature for now and so most file systems will be readable without selecting this option. If unsure, say N. config EROFS_FS_ONDEMAND bool "EROFS fscache-based on-demand read support (deprecated)" depends on EROFS_FS select NETFS_SUPPORT select FSCACHE select CACHEFILES select CACHEFILES_ONDEMAND help This permits EROFS to use fscache-backed data blobs with on-demand read support. It is now deprecated and scheduled to be removed from the kernel after fanotify pre-content hooks are landed. If unsure, say N. config EROFS_FS_PCPU_KTHREAD bool "EROFS per-cpu decompression kthread workers" depends on EROFS_FS_ZIP help Saying Y here enables per-CPU kthread workers pool to carry out async decompression for low latencies on some architectures. If unsure, say N. config EROFS_FS_PCPU_KTHREAD_HIPRI bool "EROFS high priority per-CPU kthread workers" depends on EROFS_FS_ZIP && EROFS_FS_PCPU_KTHREAD default y help This permits EROFS to configure per-CPU kthread workers to run at higher priority. If unsure, say N.