scripts/uncow.py at master · stsquad/scripts

	#!/usr/bin/python
	# -- coding: utf-8 --
	#
	# uncow, a simple script to uncow files copied into a fresh btrfs subvolume
	#
	# (C)opyright 2012 Alex Bennée
	# License: GPLv3
	#
	# Usage:
	# - create a new btrfs subvolume with nodatacow mount option
	# - move all the data you want into the new subvolume
	# - find <SPEC> \| xargs uncow.py
	#
	# What the script does:
	# - create a new file
	# - copy the contents of the old file to new
	# - rm the old file
	# - rename the new file to the old files name
	#

	import sys,os
	import argparse
	from uuid import uuid3, NAMESPACE_URL
	from shutil import copyfile
	from subprocess import check_output,check_call,STDOUT,CalledProcessError
	from re import search
	from array import array
	from fcntl import ioctl

	# IOCTL constants, ganked from strace of lsattr/chattr
	FS_GET_FLAGS=0x80086601
	FS_SET_FLAGS=0x40086602
	FS_NOWCOW_FL=0x00800000

	checked_dirs=dict()

	def check_attributes(verbose, directory):
	flags=array('I', [0])
	fd=os.open(directory, os.O_DIRECTORY)
	ioctl(fd, FS_GET_FLAGS, flags, 1)
	if verbose: print "check_for_nowcow(%s) => %x" % (directory, flags[0])
	os.close(fd)
	return flags[0]

	def check_and_modify_dir(verbose, directory):
	"""
	check directory has +C attribute, if not set it
	"""
	if directory in checked_dirs:
	return

	flags=check_attributes(verbose, directory)
	if flags & FS_NOWCOW_FL:
	checked_dirs[directory]=1
	else:
	fd=os.open(directory, os.O_DIRECTORY)
	new_flags=array('I', [flags\|FS_NOWCOW_FL])
	if verbose: print "setting +C/%x for %s" % (new_flags[0], directory)
	try:
	ioctl(fd, FS_SET_FLAGS, new_flags)
	except:
	print "Error setting +C for %s" % (directory)
	sys.exit(-2)
	if verbose: print "new flags now %x" % (check_attributes(verbose, directory))

	os.close(fd)


	parser = argparse.ArgumentParser(description='Create new non-COW files with old data.',
	epilog='If passed a directory instead of a file it will just make '+
	'the attributes changes for new files')

	parser.add_argument('files', metavar='FILE', nargs='+', help='filepath to uncow')
	parser.add_argument('-v', '--verbose', action='store_true', default=False, help="Verbose output")
	args = parser.parse_args()

	for p in args.files:
	absp = os.path.abspath(p)
	if os.path.exists(absp):
	if os.path.isdir(absp):
	check_and_modify_dir(args.verbose, absp)
	elif os.path.isfile(absp):
	old_filename=os.path.basename(absp)
	dirname=os.path.dirname(absp)
	check_and_modify_dir(args.verbose, dirname)

	new_filename="%s/%s-%s" % (dirname, old_filename, uuid3(NAMESPACE_URL, old_filename))
	try:
	if args.verbose: print "creating new file %s" % (new_filename)
	copyfile(absp, new_filename)
	if args.verbose: print "removing old file %s" % (absp)
	os.unlink(absp)
	if args.verbose: print "renaming %s to %s" % (new_filename, absp)
	os.rename(new_filename, absp)
	except:
	print "error with %s, %s" % (absp, new_filename)
	exit -1
	else:
	print "can't operate on things that aren't directories or files (%s)" % (absp)
	exit -1