On Mon, Feb 03, 2025 at 02:20:31PM -0800, Darrick J. Wong wrote: > On Mon, Feb 03, 2025 at 10:43:11AM +0100, Christoph Hellwig wrote: > > This is a quick hack to demonstrate how data checksumming can be > > implemented when it can be stored in the out of line metadata for each > > logical block. It builds on top of the previous PI infrastructure > > and instead of generating/verifying protection information it simply > > generates and verifies a crc32c checksum and stores it in the non-PI > > PI can do crc32c now? I thought it could only do that old crc16 from > like 15 years ago and crc64? NVMe has a protection information format with a crc32c, but it's not supported by Linux yet. > If we try to throw crc32c at a device, > won't it then reject the "incorrect" checksums? Or is there some other > magic in here where it works and I'm just too out of date to know? This patch implements XFS-level data checksums on devices that implement non-PI metadata, that is the device allows to store extra data with the LBA, but doesn't actually interpret and verify it іn any way. > The crc32c generation and validation looks decent though we're > definitely going to want an inode flag so that we're not stuck with > stable page writes. Yeah, support the NOCOW flag, have a sb flag to enable the checksums, maybe even a field about what checksum to use, yodda, yodda.
