Replacing corrupted files/directories

[Ravi Pinjala <ravi@p-static.net>]

Is there a recommended way to replace a corrupted file or directory on
btrfs? The use case I'm thinking of is handling filesystem corruption
by restoring only the corrupted files from backup. For a corrupted
file, it seems like deleting the file and replacing it with the copy
from the backup works, but I don't know if this is necessarily the
best way - the nature of copy-on-write means that there's still
corrupt data lying around on the filesystem, right? And for
directories, it's tricky, because (afaik) there's no way to delete a
directory without first walking it; not good if it's corrupted.

I think this is probably also relevant to something like Ceph or CRFS,
where redundancy exists, but isn't managed by btrfs directly.