On Fri, Feb 14 2025, Al Viro wrote: > On Fri, Feb 14, 2025 at 02:47:56AM +0000, Al Viro wrote: > > [snip] > >> Am I missing something subtle here? Can elen be non-positive at that point? It has been a while since I last looked into this code, so the details are quite foggy. I don't think you're missing something and that '(elen > 0)' test could be dropped. Unfortunately, I can only tell that through code analysis -- I don't have a test environment anymore where I could try that. > Another fun question: for dentries with name of form _<something>_<inumber> > we end up looking at fscrypt_has_encryption_key() not for the parent, > but for inode with inumber encoded in dentry name. Fair enough, but... > what happens if we run into such dentry in ceph_mdsc_build_path()? > > There the call of ceph_encode_encrypted_fname() is under > if (fscrypt_has_encryption_key(d_inode(parent))) > > Do we need the keys for both? I'm not sure I totally understand your question, but here are my thoughts: if we have the key for the parent, then we *do* have the key for an inode under that encrypted subtree. This is because AFAIR we can not have nested encryption. Thus, the call to ceph_encode_encrypted_fname() *should* be OK. But I'm CC'ing Jeff as he wrote most of the cephfs fscrypt code and he might correct me. Or maybe he has a better memory than I do. Cheers, -- Luís
