repart: support erofs

So, i think "erofs" is probably the better, more modern alternative to
"squashfs". Many of the benefits don't matter too much to us I guess,
but there's one thing that stands out: erofs has a UUID in the
superblock, squashfs has not. Having an UUID in the superblock matters
if the file systems are used in an overlayfs stack, as overlayfs uses
the UUIDs to robustly and persistently reference inodes on layers in
case of metadata copy-up.

Since we probably want to allow such uses in overlayfs as emplyoed by
sysext (and the future syscfg) we probably should ramp up our erofs game
early on. Hence let's natively support erofs, test it, and in fact
mention it in the docs before squashfs even.
This commit is contained in:
Lennart Poettering 2022-12-09 16:08:54 +01:00 committed by Luca Boccassi
parent 5e5fce3e91
commit 09e917ea4d
6 changed files with 31 additions and 10 deletions

View file

@ -223,8 +223,8 @@ images minimal.
If the image is writable, and some of the files or directories that are
overmounted from the host do not exist yet they will be automatically created.
On read-only, immutable images (e.g. squashfs images) all files and directories
to over-mount must exist already.
On read-only, immutable images (e.g. `erofs` or `squashfs` images) all files
and directories to over-mount must exist already.
Note that as no new image format or metadata is defined, it's very
straightforward to define images than can be made use of in a number of

View file

@ -383,12 +383,13 @@
<term><varname>Format=</varname></term>
<listitem><para>Takes a file system name, such as <literal>ext4</literal>, <literal>btrfs</literal>,
<literal>xfs</literal>, <literal>vfat</literal>, <literal>squashfs</literal>, or the special value
<literal>swap</literal>. If specified and the partition is newly created it is formatted with the
specified file system (or as swap device). The file system UUID and label are automatically derived
from the partition UUID and label. If this option is used, the size allocation algorithm is slightly
altered: the partition is created as least as big as required for the minimal file system of the
specified type (or 4KiB if the minimal size is not known).</para>
<literal>xfs</literal>, <literal>vfat</literal>, <literal>erofs</literal>,
<literal>squashfs</literal> or the special value <literal>swap</literal>. If specified and the partition
is newly created it is formatted with the specified file system (or as swap device). The file system
UUID and label are automatically derived from the partition UUID and label. If this option is used,
the size allocation algorithm is slightly altered: the partition is created as least as big as
required for the minimal file system of the specified type (or 4KiB if the minimal size is not
known).</para>
<para>This option has no effect if the partition already exists.</para>

View file

@ -73,7 +73,8 @@
<listitem><para>Plain directories or btrfs subvolumes containing the OS tree</para></listitem>
<listitem><para>Disk images with a GPT disk label, following the <ulink
url="https://uapi-group.org/specifications/specs/discoverable_partitions_specification">Discoverable Partitions Specification</ulink></para></listitem>
<listitem><para>Disk images lacking a partition table, with a naked Linux file system (e.g. squashfs or ext4)</para></listitem>
<listitem><para>Disk images lacking a partition table, with a naked Linux file system (e.g. erofs,
squashfs or ext4)</para></listitem>
</orderedlist>
<para>These image formats are the same ones that

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@ -335,6 +335,14 @@ int make_filesystem(
return log_error_errno(SYNTHETIC_ERRNO(EPROTONOSUPPORT), "mksquashfs binary not available.");
if (r < 0)
return log_error_errno(r, "Failed to determine whether mksquashfs binary exists: %m");
} else if (streq(fstype, "erofs")) {
r = find_executable("mkfs.erofs", &mkfs);
if (r == -ENOENT)
return log_error_errno(SYNTHETIC_ERRNO(EPROTONOSUPPORT), "mkfs.erofs binary not available.");
if (r < 0)
return log_error_errno(r, "Failed to determine whether mkfs.erofs binary exists: %m");
} else if (fstype_is_ro(fstype)) {
return log_error_errno(SYNTHETIC_ERRNO(EOPNOTSUPP),
"Don't know how to create read-only file system '%s', refusing.",
@ -501,6 +509,12 @@ int make_filesystem(
root, node,
"-quiet",
"-noappend");
else if (streq(fstype, "erofs"))
argv = strv_new(mkfs,
"-U", vol_id,
node, root);
else
/* Generic fallback for all other file systems */
argv = strv_new(mkfs, node);
@ -539,6 +553,9 @@ int make_filesystem(
if (STR_IN_SET(fstype, "ext2", "ext3", "ext4", "btrfs", "f2fs", "xfs", "vfat", "swap"))
log_info("%s successfully formatted as %s (label \"%s\", uuid %s)",
node, fstype, label, vol_id);
else if (streq(fstype, "erofs"))
log_info("%s successfully formatted as %s (uuid %s, no label)",
node, fstype, vol_id);
else
log_info("%s successfully formatted as %s (no label or uuid specified)",
node, fstype);

View file

@ -13,8 +13,10 @@ test_append_files() {
if ! get_bool "${TEST_NO_QEMU:=}"; then
install_dmevent
instmods dm_verity =md
instmods erofs
generate_module_dependencies
image_install -o /sbin/mksquashfs
image_install -o /bin/mkfs.erofs
fi
inst_binary mcopy

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@ -901,7 +901,7 @@ test_minimize() {
# shellcheck disable=SC2064
trap "rm -rf '$defs' '$imgs'" RETURN
for format in ext4 vfat; do
for format in ext4 vfat erofs; do
if ! command -v "mkfs.$format" >/dev/null; then
continue
fi