1# SPDX-License-Identifier: GPL-2.0-only 2 3config EROFS_FS 4 tristate "EROFS filesystem support" 5 depends on BLOCK 6 select FS_IOMAP 7 select LIBCRC32C 8 help 9 EROFS (Enhanced Read-Only File System) is a lightweight read-only 10 file system with modern designs (e.g. no buffer heads, inline 11 xattrs/data, chunk-based deduplication, multiple devices, etc.) for 12 scenarios which need high-performance read-only solutions, e.g. 13 smartphones with Android OS, LiveCDs and high-density hosts with 14 numerous containers; 15 16 It also provides fixed-sized output compression support in order to 17 improve storage density as well as keep relatively higher compression 18 ratios and implements in-place decompression to reuse the file page 19 for compressed data temporarily with proper strategies, which is 20 quite useful to ensure guaranteed end-to-end runtime decompression 21 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_DEBUG 29 bool "EROFS debugging feature" 30 depends on EROFS_FS 31 help 32 Print debugging messages and enable more BUG_ONs which check 33 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_XATTR 39 bool "EROFS extended attributes" 40 depends on EROFS_FS 41 select XXHASH 42 default y 43 help 44 Extended attributes are name:value pairs associated with inodes by 45 the kernel or by users (see the attr(5) manual page, or visit 46 <http://acl.bestbits.at/> for details). 47 48 If unsure, say N. 49 50config EROFS_FS_POSIX_ACL 51 bool "EROFS Access Control Lists" 52 depends on EROFS_FS_XATTR 53 select FS_POSIX_ACL 54 default y 55 help 56 Posix Access Control Lists (ACLs) support permissions for users and 57 groups beyond the owner/group/world scheme. 58 59 To learn more about Access Control Lists, visit the POSIX ACLs for 60 Linux website <http://acl.bestbits.at/>. 61 62 If you don't know what Access Control Lists are, say N. 63 64config EROFS_FS_SECURITY 65 bool "EROFS Security Labels" 66 depends on EROFS_FS_XATTR 67 default y 68 help 69 Security labels provide an access control facility to support Linux 70 Security Models (LSMs) accepted by AppArmor, SELinux, Smack and TOMOYO 71 Linux. This option enables an extended attribute handler for file 72 security labels in the erofs filesystem, so that it requires enabling 73 the extended attribute support in advance. 74 75 If you are not using a security module, say N. 76 77config EROFS_FS_BACKED_BY_FILE 78 bool "File-backed EROFS filesystem support" 79 depends on EROFS_FS 80 default y 81 help 82 This allows EROFS to use filesystem image files directly, without 83 the intercession of loopback block devices or likewise. It is 84 particularly useful for container images with numerous blobs and 85 other sandboxes, where loop devices behave intricately. It can also 86 be used to simplify error-prone lifetime management of unnecessary 87 virtual block devices. 88 89 Note that this feature, along with ongoing fanotify pre-content 90 hooks, will eventually replace "EROFS over fscache." 91 92 If you don't want to enable this feature, say N. 93 94config EROFS_FS_ZIP 95 bool "EROFS Data Compression Support" 96 depends on EROFS_FS 97 select LZ4_DECOMPRESS 98 default y 99 help 100 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_LZMA 105 bool "EROFS LZMA compressed data support" 106 depends on EROFS_FS_ZIP 107 select XZ_DEC 108 select XZ_DEC_MICROLZMA 109 help 110 Saying Y here includes support for reading EROFS file systems 111 containing LZMA compressed data, specifically called microLZMA. It 112 gives better compression ratios than the default LZ4 format, at the 113 expense of more CPU overhead. 114 115 If unsure, say N. 116 117config EROFS_FS_ZIP_DEFLATE 118 bool "EROFS DEFLATE compressed data support" 119 depends on EROFS_FS_ZIP 120 select ZLIB_INFLATE 121 help 122 Saying Y here includes support for reading EROFS file systems 123 containing DEFLATE compressed data. It gives better compression 124 ratios than the default LZ4 format, while it costs more CPU 125 overhead. 126 127 DEFLATE support is an experimental feature for now and so most 128 file systems will be readable without selecting this option. 129 130 If unsure, say N. 131 132config EROFS_FS_ZIP_ZSTD 133 bool "EROFS Zstandard compressed data support" 134 depends on EROFS_FS_ZIP 135 select ZSTD_DECOMPRESS 136 help 137 Saying Y here includes support for reading EROFS file systems 138 containing Zstandard compressed data. It gives better compression 139 ratios than the default LZ4 format, while it costs more CPU 140 overhead. 141 142 Zstandard support is an experimental feature for now and so most 143 file systems will be readable without selecting this option. 144 145 If unsure, say N. 146 147config EROFS_FS_ONDEMAND 148 bool "EROFS fscache-based on-demand read support (deprecated)" 149 depends on EROFS_FS 150 select NETFS_SUPPORT 151 select FSCACHE 152 select CACHEFILES 153 select CACHEFILES_ONDEMAND 154 help 155 This permits EROFS to use fscache-backed data blobs with on-demand 156 read support. 157 158 It is now deprecated and scheduled to be removed from the kernel 159 after fanotify pre-content hooks are landed. 160 161 If unsure, say N. 162 163config EROFS_FS_PCPU_KTHREAD 164 bool "EROFS per-cpu decompression kthread workers" 165 depends on EROFS_FS_ZIP 166 help 167 Saying Y here enables per-CPU kthread workers pool to carry out 168 async decompression for low latencies on some architectures. 169 170 If unsure, say N. 171 172config EROFS_FS_PCPU_KTHREAD_HIPRI 173 bool "EROFS high priority per-CPU kthread workers" 174 depends on EROFS_FS_ZIP && EROFS_FS_PCPU_KTHREAD 175 default y 176 help 177 This permits EROFS to configure per-CPU kthread workers to run 178 at higher priority. 179 180 If unsure, say N. 181