Skip to content

guest: avoid reserving unusable CAS blocks #31

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
zbarsky-openai wants to merge 1 commit into
base: main
Choose a base branch
from
Open

guest: avoid reserving unusable CAS blocks #31

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
11 changes: 8 additions & 3 deletions src/guest_init.zig
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -1,5 +1,6 @@
const builtin = @import("builtin");
const std = @import("std");
const action_runner = @import("action_runner.zig");

pub const Error = error{
MountFailed,
Expand Down Expand Up @@ -40,6 +41,10 @@ pub const cas_mount_fstype: [:0]const u8 = "ext4";
pub const cas_format_cmdline_token = "actiond.format_cas=1";
pub const cas_device_cmdline_prefix = "actiond.cas_device=";
pub const cas_mkfs_path = "/sbin/mkfs.ext4";
pub const cas_mount_data: [:0]const u8 = std.fmt.comptimePrint(
"errors=remount-ro,resuid={d}",
.{@as(action_runner.RunOptions, .{ .chroot_dir = "" }).sandbox_uid},
);
pub const cas_format_device = block_devices[0];
const cas_mount_flags = std.os.linux.MS.NOSUID |
std.os.linux.MS.NODEV |
Expand Down Expand Up @@ -209,13 +214,12 @@ fn tryMountCasDevice(stderr: *std.Io.Writer, device: [:0]const u8) !CasMountAtte
else => return .unavailable,
}

const data: [:0]const u8 = "errors=remount-ro";
const rc = linux.mount(
device.ptr,
cas_mount_target.ptr,
cas_mount_fstype.ptr,
cas_mount_flags,
@intFromPtr(data.ptr),
@intFromPtr(cas_mount_data.ptr),
);
switch (linux.errno(rc)) {
.SUCCESS => {
Expand All @@ -238,7 +242,7 @@ fn tryMountCasDevice(stderr: *std.Io.Writer, device: [:0]const u8) !CasMountAtte
}

fn formatCasDevice(io: std.Io, stderr: *std.Io.Writer, device: [:0]const u8) !void {
const argv = [_][]const u8{ cas_mkfs_path, "-F", "-q", "-t", "ext4", device };
const argv = [_][]const u8{ cas_mkfs_path, "-F", "-q", "-t", "ext4", "-m", "0", device };

stderr.print("formatting new guest CAS image on {s}\n", .{device}) catch {};
stderr.flush() catch {};
Expand Down Expand Up @@ -349,6 +353,7 @@ test "guest init mount plan stays minimal" {
try std.testing.expectEqualStrings("/cas", cas_mount_target);
try std.testing.expectEqualStrings("actiond.format_cas=1", cas_format_cmdline_token);
try std.testing.expectEqualStrings("/sbin/mkfs.ext4", cas_mkfs_path);
try std.testing.expectEqualStrings("errors=remount-ro,resuid=65534", cas_mount_data);
try std.testing.expectEqualStrings("/dev/vda", cas_format_device);
try std.testing.expect((cas_mount_flags & std.os.linux.MS.NOSUID) != 0);
try std.testing.expect((cas_mount_flags & std.os.linux.MS.NODEV) != 0);
Expand Down
Loading