Maarten Baert MaartenBaert

Manually fixing bit flips in BTRFS

Somehow my BTRFS file system became corrupted by what appears to be a single bit flip in a metadata field. Rather than copying all the data and reformatting the file system, which would have required another disk at least as large as the original, I decided to try to fix this manually, which appears to have worked. I've documented the procedure I've used here, in case I need it again or someone else runs into a similar issue and finds it useful.

The first thing you should do is run btrfs check. For me this produced the following output:

Opening filesystem to check...
Checking filesystem on /dev/nvme0n1p1
UUID: ec7afe1c-8478-450a-82fc-d17b32d8ca3d

NumPy PR: Fix `np.generic.astype` for parametric user-defined dtypes

Summary

scalar.astype(dst) silently fails for scalars belonging to parametric new-style user-defined dtypes (introduced in NumPy 2.0). The intermediate array NumPy creates internally uses the dtype's default descriptor rather than the descriptor of the scalar instance, so setitem either rejects it or stores wrong data. The fix is a one-function change to PyArray_DescrFromScalar in numpy/_core/src/multiarray/scalarapi.c.

Revised PR: Simplify `PyArray_DescrFromScalar` per maintainer feedback

Maintainer's suggestion (decoded)

The maintainer (Sebastian Berg) suggests replacing most of PyArray_DescrFromScalar with a two-step pattern:

Get the DType class via PyArray_DescrFromTypeObject (robust, handles subclasses)
Call NPY_DT_CALL_discover_descr_from_pyobject(DType, sc) unconditionally

	#!/bin/bash

	# IMPORTANT: READ THIS BEFORE RUNNING THIS SCRIPT!
	# This script only works when the system is configured correctly. Do these things first:
	#
	# Step 1:
	# - If you have an ~/.asoundrc file, rename it to ~/.asoundrc-default. If you don't have one, create an empty file named ~/.asoundrc-default.
	# - Create ~/.asoundrc-jack with the contents found here: https://gist.github.com/MaartenBaert/3630a1863969ba344704
	# The script will create a symlink from .asoundrc to .asoundrc-jack when started, and from .asoundrc to .asoundrc-default when stopped.
	#

	# Some of this may look redundant, but this was carefully written to
	# work around various bugs in alsa-plugins, so don't mess with it :).

	# override default
	pcm.!default {
	type plug
	slave {
	pcm "rjack"
	}
	}

	from pylab import *

	def segment_intersects_rectangle(x1, y1, x2, y2, cx, cy, w, h):
	return (fabs(x1 + x2 - 2.0 * cx) < fabs(x1 - x2) + w and
	fabs(y1 + y2 - 2.0 * cy) < fabs(y1 - y2) + h and
	2.0 * fabs((x1 - cx) * (y1 - y2) - (y1 - cy) * (x1 - x2)) < w * fabs(y1 - y2) + h * fabs(x1 - x2))

	def test_intersect(plot_line, plot_rect):
	for line in plot_line:
	(x1, x2) = line.get_xdata()

	# Maintainer: Schala <schalaalexiazeal "at" gmail {dot} com>
	# Contributor: calegria <calegria+al "at" gmail {dot} com>

	pkgbase=mingw-w64-harfbuzz
	pkgname=(mingw-w64-harfbuzz mingw-w64-harfbuzz-icu)
	pkgver=1.5.1
	pkgrel=1
	pkgdesc="OpenType text shaping engine (mingw-w64)"
	arch=(any)
	url="http://www.freedesktop.org/wiki/Software/HarfBuzz"

	QProgressDialog dialog("Parameter sweep ...", "Cancel", 0, (int) sweep_values.size(), this);
	dialog.setWindowTitle(MainWindow::WINDOW_CAPTION);
	dialog.setWindowModality(Qt::WindowModal);
	dialog.setMinimumDuration(0);
	dialog.setValue(0);
	std::atomic<bool> worker_canceled(false), worker_stopped(false);
	std::exception_ptr worker_exception;
	std::thread worker_thread([&]() {
	try {
	for(size_t i = 0; i < sweep_values.size(); ++i) {

	import ctypes
	import glob
	import mmap
	import operator
	import os.path
	import time

	import numpy
	import matplotlib.pyplot as plt

	import numpy as np
	import scipy.signal

	def sscascade(sslist):

	# The cascaded state-space representation can be constructed as block
	# matrices of the following form (example for 4 sub-systems):
	# A = [ A1 , , , ]
	# [ B2 @ C1 , A2 , , ]
	# [ B3 @ D2 @ C1 , B3 @ C2 , A3 , ]