Bart Sjerps
132 lines
4.3 KiB
Python
Executable File
132 lines
4.3 KiB
Python
Executable File
#!/usr/bin/env python3
|
||
"""Resize an LVM logical volume and its filesystem.
|
||
|
||
Author: Bart Sjerps
|
||
Date: 2026-07-17
|
||
Generated by opencode
|
||
"""
|
||
import os
|
||
import sys
|
||
import subprocess
|
||
import argparse
|
||
from typing import Optional
|
||
|
||
|
||
def die(msg: str) -> None:
|
||
"""Print an error message to stderr and exit with code 2."""
|
||
print(f"Error: {msg}", file=sys.stderr)
|
||
sys.exit(2)
|
||
|
||
|
||
def run(cmd: list[str], dryrun: bool = False) -> str:
|
||
"""Execute a shell command, returning stdout. Exits on non-zero status."""
|
||
if dryrun:
|
||
print(f"[DRY-RUN] {' '.join(cmd)}")
|
||
return ""
|
||
try:
|
||
result = subprocess.run(cmd, capture_output=True, text=True, check=True)
|
||
except subprocess.CalledProcessError as e:
|
||
err = (e.stderr or e.stdout or "").strip()
|
||
die(f"{' '.join(cmd)} failed: {err or f'exit code {e.returncode}'}")
|
||
return result.stdout.strip()
|
||
|
||
|
||
def resolve_lv(mount: Optional[str] = None, lvname: Optional[str] = None) -> str:
|
||
"""Resolve a mountpoint or LV name to an absolute LVM device path."""
|
||
if mount:
|
||
dev = run(["findmnt", "-no", "SOURCE", "--target", mount])
|
||
if not dev:
|
||
die(f"No device mounted at {mount}")
|
||
else:
|
||
dev = lvname
|
||
|
||
if not dev.startswith("/dev/"):
|
||
dev = f"/dev/{dev}"
|
||
|
||
if not run(["lvs", dev]):
|
||
die(f"{dev} is not an LVM logical volume")
|
||
|
||
return dev
|
||
|
||
|
||
def detect_fs(dev: str) -> str:
|
||
"""Detect the filesystem type on a block device via blkid."""
|
||
fstype = run(["blkid", "-o", "value", "-s", "TYPE", dev])
|
||
if not fstype:
|
||
die(f"Cannot detect filesystem on {dev}")
|
||
return fstype
|
||
|
||
|
||
def resolve_mount(dev: str, mount: Optional[str] = None) -> str:
|
||
"""Return a mountpoint for a device, using the provided one or looking it up."""
|
||
if mount:
|
||
return mount
|
||
|
||
mountpoint = run(["findmnt", "-no", "TARGET", "--source", dev])
|
||
if not mountpoint:
|
||
die(f"No mountpoint found for {dev}")
|
||
return mountpoint
|
||
|
||
|
||
def lvextend_cmd(size: str, dev: str) -> list[str]:
|
||
"""Build an lvextend command, using -l for extent/percent sizes."""
|
||
if "%" in size:
|
||
return ["lvextend", "-l", size, dev]
|
||
return ["lvextend", "-L", size, dev]
|
||
|
||
|
||
def btrfs_resize_size(size: str) -> str:
|
||
"""Map an LVM size spec to a btrfs filesystem resize argument."""
|
||
if "%" in size:
|
||
return "max"
|
||
return size
|
||
|
||
|
||
def validate_resize(dev: str, fstype: str, mount: Optional[str] = None) -> Optional[str]:
|
||
"""Validate resize is possible before mutating the LV. Returns mountpoint when needed."""
|
||
if fstype in ("ext2", "ext3", "ext4"):
|
||
return None
|
||
if fstype in ("xfs", "btrfs"):
|
||
return resolve_mount(dev, mount)
|
||
die(f"Unsupported filesystem: {fstype}")
|
||
|
||
|
||
def do_resize(dev: str, fstype: str, size: str, mount: Optional[str] = None, dryrun: bool = False) -> None:
|
||
"""Extend the LV with lvextend, then resize the filesystem accordingly."""
|
||
fs_mount = validate_resize(dev, fstype, mount)
|
||
|
||
run(lvextend_cmd(size, dev), dryrun=dryrun)
|
||
|
||
if fstype in ("ext2", "ext3", "ext4"):
|
||
run(["resize2fs", dev], dryrun=dryrun)
|
||
elif fstype == "xfs":
|
||
run(["xfs_growfs", fs_mount], dryrun=dryrun)
|
||
elif fstype == "btrfs":
|
||
run(["btrfs", "filesystem", "resize", btrfs_resize_size(size), fs_mount], dryrun=dryrun)
|
||
|
||
if not dryrun:
|
||
print("Done.")
|
||
|
||
|
||
def main() -> None:
|
||
"""Parse args, validate root, then resize LV and filesystem."""
|
||
parser = argparse.ArgumentParser(description="Resize an LVM logical volume and its filesystem")
|
||
parser.add_argument("-s", dest="size", required=True, help="New size (e.g. +10G, -5G, 20G, 100%FREE)")
|
||
group = parser.add_mutually_exclusive_group(required=True)
|
||
group.add_argument("-m", dest="mount", metavar="MOUNTPOINT", help="Select LV by mountpoint")
|
||
group.add_argument("-l", dest="lvname", metavar="LVNAME", help="Select LV by name or path (e.g. vg0/data)")
|
||
parser.add_argument("-n", dest="dryrun", action="store_true", help="Dry-run – print what would be done without executing")
|
||
|
||
args = parser.parse_args()
|
||
|
||
if os.geteuid() != 0:
|
||
die("This script must be run as root")
|
||
|
||
lvdev = resolve_lv(mount=args.mount, lvname=args.lvname)
|
||
fstype = detect_fs(lvdev)
|
||
do_resize(lvdev, fstype, args.size, mount=args.mount, dryrun=args.dryrun)
|
||
|
||
|
||
if __name__ == "__main__":
|
||
main()
|