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

jwbee

Make Ubuntu packages 90% faster by rebuilding them

TL;DR

You can take the same source code package that Ubuntu uses to build jq, compile it again, and realize 90% better performance.

Setting

I use jq for processing GeoJSON files and other open data offered in JSON format. Today I am working with a 500MB GeoJSON file that contains the Alameda County Assessor's parcel map. I want to run a query that prints the city for every parcel worth more than a threshold amount. The program is