>How is this an issue? Discard is issued only once we're positive >there's no >reference to the freed blocks anywhere. At that point, they're also >open >for reuse, thus they can be arbitrarily scribbled upon. Point was, how about keeping this reference for some time period? >Unless your hardware is seriously broken (such as lying about barriers, >which is nearly-guaranteed data loss on btrfs anyway), there's no way >the >filesystem will ever reference such blocks. Buggy hardware happen. So do buggy filesystems ;) Besides, most filesystems let user recover most data after losing just one sector, would be pity if BTRFS with all its COW coolness didn't. >Why would you special-case metadata? Metadata that points to >overwritten or >discarded blocks is of no use either. It takes significant time to overwrite noticeable portion of data on disk, but loss of metadata makes it gone in a moment. Moreover, user is usually prepared to lose some recently changed data in crash, but not the one that it didn't even touch. -- With Best Regards, Marat Khalili -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
