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1# SPDX-License-Identifier: GPL-2.0-only2 3config EROFS_FS4 tristate "EROFS filesystem support"5 depends on BLOCK6 select FS_IOMAP7 select LIBCRC32C8 help9 EROFS (Enhanced Read-Only File System) is a lightweight read-only10 file system with modern designs (e.g. no buffer heads, inline11 xattrs/data, chunk-based deduplication, multiple devices, etc.) for12 scenarios which need high-performance read-only solutions, e.g.13 smartphones with Android OS, LiveCDs and high-density hosts with14 numerous containers;15 16 It also provides fixed-sized output compression support in order to17 improve storage density as well as keep relatively higher compression18 ratios and implements in-place decompression to reuse the file page19 for compressed data temporarily with proper strategies, which is20 quite useful to ensure guaranteed end-to-end runtime decompression21 performance under extremely memory pressure without extra cost.22 23 See the documentation at <file:Documentation/filesystems/erofs.rst>24 and the web pages at <https://erofs.docs.kernel.org> for more details.25 26 If unsure, say N.27 28config EROFS_FS_DEBUG29 bool "EROFS debugging feature"30 depends on EROFS_FS31 help32 Print debugging messages and enable more BUG_ONs which check33 filesystem consistency and find potential issues aggressively,34 which can be used for Android eng build, for example.35 36 For daily use, say N.37 38config EROFS_FS_XATTR39 bool "EROFS extended attributes"40 depends on EROFS_FS41 select XXHASH42 default y43 help44 Extended attributes are name:value pairs associated with inodes by45 the kernel or by users (see the attr(5) manual page, or visit46 <http://acl.bestbits.at/> for details).47 48 If unsure, say N.49 50config EROFS_FS_POSIX_ACL51 bool "EROFS Access Control Lists"52 depends on EROFS_FS_XATTR53 select FS_POSIX_ACL54 default y55 help56 Posix Access Control Lists (ACLs) support permissions for users and57 groups beyond the owner/group/world scheme.58 59 To learn more about Access Control Lists, visit the POSIX ACLs for60 Linux website <http://acl.bestbits.at/>.61 62 If you don't know what Access Control Lists are, say N.63 64config EROFS_FS_SECURITY65 bool "EROFS Security Labels"66 depends on EROFS_FS_XATTR67 default y68 help69 Security labels provide an access control facility to support Linux70 Security Models (LSMs) accepted by AppArmor, SELinux, Smack and TOMOYO71 Linux. This option enables an extended attribute handler for file72 security labels in the erofs filesystem, so that it requires enabling73 the extended attribute support in advance.74 75 If you are not using a security module, say N.76 77config EROFS_FS_BACKED_BY_FILE78 bool "File-backed EROFS filesystem support"79 depends on EROFS_FS80 default y81 help82 This allows EROFS to use filesystem image files directly, without83 the intercession of loopback block devices or likewise. It is84 particularly useful for container images with numerous blobs and85 other sandboxes, where loop devices behave intricately. It can also86 be used to simplify error-prone lifetime management of unnecessary87 virtual block devices.88 89 Note that this feature, along with ongoing fanotify pre-content90 hooks, will eventually replace "EROFS over fscache."91 92 If you don't want to enable this feature, say N.93 94config EROFS_FS_ZIP95 bool "EROFS Data Compression Support"96 depends on EROFS_FS97 select LZ4_DECOMPRESS98 default y99 help100 Enable fixed-sized output compression for EROFS.101 102 If you don't want to enable compression feature, say N.103 104config EROFS_FS_ZIP_LZMA105 bool "EROFS LZMA compressed data support"106 depends on EROFS_FS_ZIP107 select XZ_DEC108 select XZ_DEC_MICROLZMA109 help110 Saying Y here includes support for reading EROFS file systems111 containing LZMA compressed data, specifically called microLZMA. It112 gives better compression ratios than the default LZ4 format, at the113 expense of more CPU overhead.114 115 If unsure, say N.116 117config EROFS_FS_ZIP_DEFLATE118 bool "EROFS DEFLATE compressed data support"119 depends on EROFS_FS_ZIP120 select ZLIB_INFLATE121 help122 Saying Y here includes support for reading EROFS file systems123 containing DEFLATE compressed data. It gives better compression124 ratios than the default LZ4 format, while it costs more CPU125 overhead.126 127 DEFLATE support is an experimental feature for now and so most128 file systems will be readable without selecting this option.129 130 If unsure, say N.131 132config EROFS_FS_ZIP_ZSTD133 bool "EROFS Zstandard compressed data support"134 depends on EROFS_FS_ZIP135 select ZSTD_DECOMPRESS136 help137 Saying Y here includes support for reading EROFS file systems138 containing Zstandard compressed data. It gives better compression139 ratios than the default LZ4 format, while it costs more CPU140 overhead.141 142 Zstandard support is an experimental feature for now and so most143 file systems will be readable without selecting this option.144 145 If unsure, say N.146 147config EROFS_FS_ONDEMAND148 bool "EROFS fscache-based on-demand read support (deprecated)"149 depends on EROFS_FS150 select NETFS_SUPPORT151 select FSCACHE152 select CACHEFILES153 select CACHEFILES_ONDEMAND154 help155 This permits EROFS to use fscache-backed data blobs with on-demand156 read support.157 158 It is now deprecated and scheduled to be removed from the kernel159 after fanotify pre-content hooks are landed.160 161 If unsure, say N.162 163config EROFS_FS_PCPU_KTHREAD164 bool "EROFS per-cpu decompression kthread workers"165 depends on EROFS_FS_ZIP166 help167 Saying Y here enables per-CPU kthread workers pool to carry out168 async decompression for low latencies on some architectures.169 170 If unsure, say N.171 172config EROFS_FS_PCPU_KTHREAD_HIPRI173 bool "EROFS high priority per-CPU kthread workers"174 depends on EROFS_FS_ZIP && EROFS_FS_PCPU_KTHREAD175 default y176 help177 This permits EROFS to configure per-CPU kthread workers to run178 at higher priority.179 180 If unsure, say N.181