erofs5
The enhanced read-only file system
Overview
erofs is a create-once read-only filesystem, with support for compression and a multi-device backing store.
There are two inode formats:
- •
-
32-byte compact with 16-bit UID/GID, 32-bit file size, and no file times
- •
-
64-byte extended with 32-bit UID/GID, 64-bit file size, and a modification time (st_mtim).
Mount options
user_xattr
nouser_xattr-
Controls whether user extended attributes are exposed. Defaults to yes.
acl
noacl-
Controls whether POSIX acl(5)s are exposed. Defaults to yes.
cache_strategy=disabled|readahead|readaround-
Cache allocation for compressed files: never, if reading from start of file, regardless of position. Defaults to
readaround.
dax
dax=always|never-
Direct Access control. If
alwaysand the source device supports DAX, uncompressed non-inlined files will be read directly, without going through the page cache.daxis a synonym foralways. Defaults to unset, which is equivalent tonever.
device=blobdev-
Add extra device holding some of the data. Must be given as many times and in the same order as
--blobdevwas to mkfs.erofs(1).
domain_id=did
fsid=id-
Control CacheFiles on-demand read support. To be documented.
Versions
erofs images are versioned through the use of feature flags; these are listed in the -E section of mkfs.erofs(1),
Configuration
Linux must be configured with the CONFIG_EROFS_FS option to mount EROFS filesystems. There are sub-configuration items that restrict the availability of some of the parameters above.
Releases
2 releases since Debian 13 (Trixie); the text changed 1 time.