On Tue, Sep 15, 2020 at 7:57 PM Kevin Kofler <kevin.kofler@xxxxxxxxx> wrote: > > Daniel Pocock wrote: > > One issue I've come across is that a btrfs filesystem can only be used > > on hosts with the same page size as the host that created the filesystem > > Ewww! That alone should disqualify btrfs as a default file system! > > Why does a file system depend on the kernel page size? The kernel page size > is an internal implementation detail of the kernel, whereas a file system > ought to be a stable interchange format that is compatible across all > machines. > > It is unfortunate that this showstopper was not mentioned when the switch to > btrfs by default was proposed. > I hate to break it to you, but this problem is not just in filesystems, it's in basically everything in the kernel. And we've had variations of problems like this for years (endianness, page size, pointer size, single bit vs multi-bit booleans, etc.). I've personally been bitten by all of these issues in some way. This comes from the fact that there's no such thing as "internal implementation detail of the kernel" by design. This is the "joy" of the monorepo "design" where everything leaks into everything else. This didn't become a serious problem until Red Hat made the unfortunate (though not realized at the time) mistake of switching to 64k pages for ARM and POWER. We got that change in Fedora for POWER but not ARM. It has led to all kinds of unfortunate problems that are gradually being worked on and fixed upstream. Coming back to Btrfs specifically, there is work underway upstream to resolve this issue. My (semi-blind) estimate is that we'll see a fix in Linux 5.11, but Josef (cc'd to this email) may know more about it. -- 真実はいつも一つ！/ Always, there's only one truth! _______________________________________________ devel mailing list -- devel@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe send an email to devel-leave@xxxxxxxxxxxxxxxxxxxxxxx Fedora Code of Conduct: https://docs.fedoraproject.org/en-US/project/code-of-conduct/ List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines List Archives: https://lists.fedoraproject.org/archives/list/devel@xxxxxxxxxxxxxxxxxxxxxxx
