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install: add target_root_path for RootSetup #1752

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Merged
cgwalters merged 6 commits into from
Jan 6, 2026
Merged

install: add target_root_path for RootSetup #1752

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10b5c32
install: empty `/boot` & `/boot/efi`
HuijingHei Nov 25, 2025
083b03d
install: add `target_root_path` for `RootSetup`
HuijingHei Nov 25, 2025
d0952c3
install: should remove the empty dir under `/boot`
HuijingHei Dec 11, 2025
18c44da
install: mount esp in `clean_boot_directories()`
HuijingHei Dec 18, 2025
d00f8d1
tests: Add test `test-tmt-on-coreos`
HuijingHei Dec 19, 2025
bab8f98
tests/plan: add `PubkeyAcceptedAlgorithms=+ssh-rsa` to ssh-option
HuijingHei Jan 4, 2026
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107 changes: 78 additions & 29 deletions crates/lib/src/install.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1122,6 +1122,8 @@ pub(crate) struct RootSetup {
pub(crate) physical_root_path: Utf8PathBuf,
/// Directory file descriptor for the above physical root.
pub(crate) physical_root: Dir,
/// Target root path /target.
pub(crate) target_root_path: Option<Utf8PathBuf>,
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@cgwalters cgwalters Jan 6, 2026

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In general, I would like if we could go to having most things be file descriptor relative; it's unfortunate to need to add a new absolute path here.

But I understand that the bootupd install is using it today.

What I would find helpful is to understand a bit more strictly the meaing of "target" here. I think we're effectively using it to be "what the user provided as an install target" right?

And for ostree/bootc systems, that's always the mounted deployment root conventionally today when they say -v /:/target.

But that's just conventional - what would happen if they passed -v /sysroot:/target say?

The more I think about this the more I feel what we should do is detect when the passed root filesystem refers to either a mounted deployment root or the physical root, and automatically canonicalize internally to "physical root" and "deployment root" (which for non-ostree systems are the same thing), and then discard the user provided input path.

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@HuijingHei HuijingHei Jan 6, 2026 •
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What I would find helpful is to understand a bit more strictly the meaing of "target" here. I think we're effectively using it to be "what the user provided as an install target" right?

And for ostree/bootc systems, that's always the mounted deployment root conventionally today when they say -v /:/target.

But that's just conventional - what would happen if they passed -v /sysroot:/target say?

The more I think about this the more I feel what we should do is detect when the passed root filesystem refers to either a mounted deployment root or the physical root, and automatically canonicalize internally to "physical root" and "deployment root" (which for non-ostree systems are the same thing), and then discard the user provided input path.

This sounds better and more sane, will try this later.

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@HuijingHei HuijingHei Jan 7, 2026 •
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what would happen if they passed -v /sysroot:/target say?

We still need /boot/efi (or separate /boot) to update the bootloader, if we pass -v /sysroot:/target, then how could we get the "physical root" like / (to get /boot/efi)?

pub(crate) rootfs_uuid: Option<String>,
/// True if we should skip finalizing
skip_finalize: bool,
Expand Down Expand Up @@ -1575,7 +1577,10 @@ async fn install_with_sysroot(
Bootloader::Grub => {
crate::bootloader::install_via_bootupd(
&rootfs.device_info,
&rootfs.physical_root_path,
&rootfs
.target_root_path
.clone()
.unwrap_or(rootfs.physical_root_path.clone()),
&state.config_opts,
Some(&deployment_path.as_str()),
)?;
Expand Down Expand Up @@ -1922,30 +1927,58 @@ fn remove_all_in_dir_no_xdev(d: &Dir, mount_err: bool) -> Result<()> {
anyhow::Ok(())
}

#[context("Removing boot directory content except loader dir on ostree")]
fn remove_all_except_loader_dirs(bootdir: &Dir, is_ostree: bool) -> Result<()> {
let entries = bootdir
.entries()
.context("Reading boot directory entries")?;

for entry in entries {
let entry = entry.context("Reading directory entry")?;
let file_name = entry.file_name();
let file_name = if let Some(n) = file_name.to_str() {
n
} else {
anyhow::bail!("Invalid non-UTF8 filename: {file_name:?} in /boot");
};

// Only preserve loader on ostree
if is_ostree && file_name.starts_with("loader") {
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@cgwalters cgwalters Dec 9, 2025

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This also relates to an issue (TODO link) where we should support preserving basically everything (including the bootloader entries on non-ostree) by default until the very end of the install. And ideally make the "commit" phase an optional step after.

This one also textually conflicts with #1727

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@HuijingHei HuijingHei Dec 10, 2025 •
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This also relates to an issue (TODO link) where we should support preserving basically everything (including the bootloader entries on non-ostree) by default until the very end of the install. And ideally make the "commit" phase an optional step after.

I think you meant preserve everything under /boot & /boot/efi, then clean them before install bootloader, is this right?

This one also textually conflicts with #1727

A little confused, this requires empty rootfs when --replace is not set, but when using to-existing-root it is using ReplaceMode::Alongside by default, maybe I misunderstood this?

continue;
}

let etype = entry.file_type()?;
if etype == FileType::dir() {
// Open the directory and remove its contents
if let Some(subdir) = bootdir.open_dir_noxdev(&file_name)? {
remove_all_in_dir_no_xdev(&subdir, false)
.with_context(|| format!("Removing directory contents: {}", file_name))?;
}
} else {
bootdir
.remove_file_optional(&file_name)
.with_context(|| format!("Removing file: {}", file_name))?;
}
}
Ok(())
}

#[context("Removing boot directory content")]
fn clean_boot_directories(rootfs: &Dir, is_ostree: bool) -> Result<()> {
let bootdir =
crate::utils::open_dir_remount_rw(rootfs, BOOT.into()).context("Opening /boot")?;

if is_ostree {
// On ostree systems, the boot directory already has our desired format, we should only
// remove the bootupd-state.json file to avoid bootupctl complaining it already exists.
bootdir
.remove_file_optional("bootupd-state.json")
.context("removing bootupd-state.json")?;
} else {
// This should not remove /boot/efi note.
remove_all_in_dir_no_xdev(&bootdir, false).context("Emptying /boot")?;
// TODO: Discover the ESP the same way bootupd does it; we should also
// support not wiping the ESP.
if ARCH_USES_EFI {
if let Some(efidir) = bootdir
.open_dir_optional(crate::bootloader::EFI_DIR)
.context("Opening /boot/efi")?
{
remove_all_in_dir_no_xdev(&efidir, false)
.context("Emptying EFI system partition")?;
}
// This should not remove /boot/efi note.
remove_all_except_loader_dirs(&bootdir, is_ostree).context("Emptying /boot")?;
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@cgwalters cgwalters Dec 2, 2025

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Hmm looks like this is going to conflict with #1727


// TODO: Discover the ESP the same way bootupd does it; we should also
// support not wiping the ESP.
if ARCH_USES_EFI {
if let Some(efidir) = bootdir
.open_dir_optional(crate::bootloader::EFI_DIR)
.context("Opening /boot/efi")?
{
remove_all_in_dir_no_xdev(&efidir, false).context("Emptying EFI system partition")?;
}
}

Expand Down Expand Up @@ -2082,6 +2115,18 @@ pub(crate) async fn install_to_filesystem(
.context("Mounting host / to {ALONGSIDE_ROOT_MOUNT}")?;
}

let target_root_path = fsopts.root_path.clone();
// Get a file descriptor for the root path /target
let target_rootfs_fd =
Dir::open_ambient_dir(&target_root_path, cap_std::ambient_authority())
.with_context(|| format!("Opening target root directory {target_root_path}"))?;

tracing::debug!("Target root filesystem: {target_root_path}");

if let Some(false) = target_rootfs_fd.is_mountpoint(".")? {
anyhow::bail!("Not a mountpoint: {target_root_path}");
}

// Check that the target is a directory
{
let root_path = &fsopts.root_path;
Expand All @@ -2095,10 +2140,7 @@ pub(crate) async fn install_to_filesystem(

// Check to see if this happens to be the real host root
if !fsopts.acknowledge_destructive {
let root_path = &fsopts.root_path;
let rootfs_fd = Dir::open_ambient_dir(root_path, cap_std::ambient_authority())
.with_context(|| format!("Opening target root directory {root_path}"))?;
warn_on_host_root(&rootfs_fd)?;
warn_on_host_root(&target_rootfs_fd)?;
}

// If we're installing to an ostree root, then find the physical root from
Expand All @@ -2114,7 +2156,8 @@ pub(crate) async fn install_to_filesystem(
};

// Get a file descriptor for the root path
let rootfs_fd = {
// It will be /target/sysroot on ostree OS, or will be /target
let rootfs_fd = if is_already_ostree {
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@cgwalters cgwalters Jan 6, 2026

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While I know you're just changing existing code, I think it'd be cleaner to fold this conditional with the one above.

I had to read this whole logic a few times to notice that a key bit here is we're mutating the user input fsopts.root_path = possible_physical_root just above, and that's an important aspect.

let root_path = &fsopts.root_path;
let rootfs_fd = Dir::open_ambient_dir(&fsopts.root_path, cap_std::ambient_authority())
.with_context(|| format!("Opening target root directory {root_path}"))?;
Expand All @@ -2125,6 +2168,8 @@ pub(crate) async fn install_to_filesystem(
anyhow::bail!("Not a mountpoint: {root_path}");
}
rootfs_fd
} else {
target_rootfs_fd.try_clone()?
};

match fsopts.replace {
Expand All @@ -2134,7 +2179,9 @@ pub(crate) async fn install_to_filesystem(
tokio::task::spawn_blocking(move || remove_all_in_dir_no_xdev(&rootfs_fd, true))
.await??;
}
Some(ReplaceMode::Alongside) => clean_boot_directories(&rootfs_fd, is_already_ostree)?,
Some(ReplaceMode::Alongside) => {
clean_boot_directories(&target_rootfs_fd, is_already_ostree)?
}
None => require_empty_rootdir(&rootfs_fd)?,
}

Expand Down Expand Up @@ -2179,7 +2226,7 @@ pub(crate) async fn install_to_filesystem(

let boot_is_mount = {
let root_dev = rootfs_fd.dir_metadata()?.dev();
let boot_dev = rootfs_fd
let boot_dev = target_rootfs_fd
.symlink_metadata_optional(BOOT)?
.ok_or_else(|| {
anyhow!("No /{BOOT} directory found in root; this is is currently required")
Expand All @@ -2190,9 +2237,10 @@ pub(crate) async fn install_to_filesystem(
};
// Find the UUID of /boot because we need it for GRUB.
let boot_uuid = if boot_is_mount {
let boot_path = fsopts.root_path.join(BOOT);
let boot_path = target_root_path.join(BOOT);
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This seems to be a key change here. I guess we needed this because in the ostree case we'd mutated fsopts.root_path to refer to the physical root, and when /boot is actually a separate mount point that was broken on ostree setups?

But this relates to what I mean above - we could instead just know to look at the deployment's /boot explicitly.

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@HuijingHei HuijingHei Jan 7, 2026 •
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This seems to be a key change here. I guess we needed this because in the ostree case we'd mutated fsopts.root_path to refer to the physical root, and when /boot is actually a separate mount point that was broken on ostree setups?

I am a little confused, do you mean "physical root" is /target, and "deployment root" is /target/sysroot?

From following log (copy from bug), we passed /target/sysroot, but we should pass /target.

> bootupctl backend install --write-uuid -vvvv --update-firmware --auto --device /dev/vda /target/sysroot
...
[DEBUG bootupd::efi] Mounted at "/target/sysroot/boot"
...
Could not find /boot/efi/EFI when installing "redhat/grub.cfg"

And I do not understand /sysroot/boot and /boot correctly, are they the same?

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@cgwalters cgwalters Jan 7, 2026

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For non-bootc/ostree setups, "physical root == root", so the user always passes -v /:/target - in other words /target inside there is always the filesystem root.

For bootc/ostree setups, they are not the same. What I am saying though is we should support being passed either thing (/sysroot or /) for /target and automatically do the right thing, and resolve the right roots.

And I do not understand /sysroot/boot and /boot correctly, are they the same?

Typically we only mount the separate boot partition in the target root, not the physical root.

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@HuijingHei HuijingHei Jan 8, 2026

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Understood, thank you for the detail info.

For bootc/ostree setups, they are not the same. What I am saying though is we should support being passed either thing (/sysroot or /) for /target and automatically do the right thing, and resolve the right roots.

Try to catch your meaning, for bootc/ostree setups, if passed -v /sysroot:/target, my concern is how to get ESP part, but looks can get /target part, then get its parent disk, then get separate boot part if there is (maybe need to mount it to /target/boot?), and ESP.

podman run --rm -it --privileged -v /dev:/dev -v /var/lib/containers:/var/lib/containers -v /sysroot:/target \
--pid=host --security-opt label=type:unconfined_t \
quay.io/fedora/fedora-bootc:rawhide bash
bash-5.3# cd /target
bash-5.3# findmnt .
TARGET  SOURCE    FSTYPE OPTIONS
/target /dev/vda4 xfs    rw,relatime,seclabel,attr2,inode64,logbufs=8,logbsize=32k,prjquota

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@HuijingHei HuijingHei Jan 8, 2026

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Will try this later.

tracing::debug!("boot_path={boot_path}");
let u = bootc_mount::inspect_filesystem(&boot_path)
.context("Inspecting /{BOOT}")?
.with_context(|| format!("Inspecting /{BOOT}"))?
.uuid
.ok_or_else(|| anyhow!("No UUID found for /{BOOT}"))?;
Some(u)
Expand Down Expand Up @@ -2279,6 +2327,7 @@ pub(crate) async fn install_to_filesystem(
device_info,
physical_root_path: fsopts.root_path,
physical_root: rootfs_fd,
target_root_path: Some(target_root_path.clone()),
rootfs_uuid: inspect.uuid.clone(),
boot,
kargs,
Expand Down
1 change: 1 addition & 0 deletions crates/lib/src/install/baseline.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -491,6 +491,7 @@ pub(crate) fn install_create_rootfs(
device_info,
physical_root_path,
physical_root,
target_root_path: None,
rootfs_uuid: Some(root_uuid.to_string()),
boot,
kargs,
Expand Down