On Wed, May 11, 2016 at 04:57:48PM -0700, Marc MERLIN wrote: > On Thu, May 12, 2016 at 07:34:26AM +0800, ching wrote: > > for example https://btrfs.wiki.kernel.org/index.php/Manpage/btrfs-scrub > > btrfs scrub is designed to make sure all the blocks and checksums are > consistent. > Ching makes a good point that it would be helpful to have a way to > access the underlying backing device directly to ensure it is > consistent. > > I think currently you can use dmsetup with an offset to get the real > filesystem past the bcache header, mount that read only somewhere and > scrub that. > Not ideal because scrub will not be able to fix issues that are fixable, > but at least it should report errors. Look at the verify code in drivers/md/bcache/debug.c, there's a CONFIG_BCACHE_DEBUG mode where every time it reads clean cached data it reads the data from the backing device and compares. But for a scrub though you really want to walk all the _cached_ data, so it'd take a bit more code than that. -- To unsubscribe from this list: send the line "unsubscribe linux-bcache" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
