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erofs(5) File Formats Manual erofs(5)

NAME

erofs - the Enhanced Read-Only File System

DESCRIPTION

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

Controls whether user extended attributes are exposed. Defaults to yes.
Controls whether POSIX acl(5)s are exposed. Defaults to yes.
Cache allocation for compressed files: never, if reading from start of file, regardless of position. Defaults to readaround.
Direct Access control. If always and the source device supports DAX, uncompressed non-inlined files will be read directly, without going through the page cache. dax is a synonym for always. Defaults to unset, which is equivalent to never.
Add extra device holding some of the data. Must be given as many times and in the same order as --blobdev was to mkfs.erofs(1).
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.

SEE ALSO

mkfs.erofs(1), fsck.erofs(1), dump.erofs(1)

Documentation/filesystems/erofs.txt in the Linux source.

2024-05-02 Linux man-pages (unreleased)